Cancer and apoptosis: The apoptotic activity of plant and marine natural products and their potential as targeted cancer therapeutics

1Cancer is the uncontrolled growth of specific cells possessed mutated genes or dys-regulatory cell division and growth. The word cancer means carcinoma, derived from a Greek word—cancer well-defined by the unregulated and uncontrolled multiplication of the cell. The specific alteration in genotype classified the normal cells as cancer cells responsible for uncontrol growth, re-location, and cancer metastasis. The cancer cell has a tremendous ability to divide and re-divide and metastatic abilities. The unchecked and over multiplication of cells leads to cancer tissue development and tends to move to various locations, resulting in metastasis development. In cancer, the different proteins involved in cell-cell attachment and regulation play a crucial role in regulating cancer cell movement. The matrix metalloproteases regulate the initiation and development of metastasis and enhancement of tumor spreading. The dysregulation in the expression of cell-cell attachment receptors fails cancer cell attachment. It encourages the ability to circulate in the bloodstream and re-locate to other locations inside the body—the abnormality in cell division, growth, and development results in cancer formation. The process of cancer development mainly comprises two fundamental alterations; i) genetical alternation and ii) Cellular alteration. The dys-regulatory genetic or cellular mechanism detected in cancer development. Genetically, the essential genes involved in the onset of cancer mainly comprised oncogenes and tumor suppression genes. The activation and deactivation of various “tumor suppressor genes” regulate the activation of cancer initiation and development. Furthermore, the variation in established genetic mechanisms involves genetic mutation, chromosomal abrasion or alteration, i.e., addition or deletion, and changes in cell cycling. The cellular alteration involves the dysregulated signaling pathways involved in the regulatory mechanism of dividing cells. However, the hallmarks of cancer cells include: Selective proliferative advantage. i) Vascularization, immune modulation. ii) Metabolic rewiring. iii) Abetting microenvironment. iv) Tissue invasion/metastasis. v) Altered stress response. The cancer development process or carcinogenesis is mainly composed of diversified steps. Due to its rapidly dividing ability, the cell forms several cells or tumors and translocates to another site, leading to metastasis. Apart from general genetic and cellular alterations, epigenetic variations include; i) hypomethylation of oncogenes, ii) hypermethylation of tumor suppressor genes, iii) depletion of hydroxymethylation, iv) changes of histone acetylation, and v) methylation patterns and vi) miRNA expression level variations, are known to be associated with many cancers. Apoptosis is the primary mechanism that plays an essential role in balancing cells growth and cell division to prevent uncontrol cancer. Carcinogenesis occurs due to damage, insult, or induction of alteration via various modes, including; physical, chemical, genetic, and biological. The cancer development and establishment process comprises cancer initiation, promotion, and progression (Figure 1). Various carcinogens act as initiators of cancer, which results in cancer formation along with promotor molecules. As in cancer initiation, most carcinogens cause irreversible damage to DNA. This damage causes the mutation in a particular genetic code that could be transferred to daughter cells and rapidly dividing cells with a mutated pattern. The cancer initiation trigger point could be an internal route or external via direct interaction with receptors on the cell surface or via various unspecified means. Thus, cancer initiation is based on irreversible genetic changes via the different genetic modes, including; i) simple mutations, small deletions, transitions, and transversions in DNA molecules. In the second stage of cancer development, there are no changes in the structure of DNA. The promotion of cancer is a reversible stage of advancement but rather in the expression of the genome mediated through promoter-receptor interactions. Interestingly, cancer progression depends on the protein involved in the migration of cancer. The extracellular environment (ECM) of cells is a pool of substances that could act like inducers that target the particular site and activate the cancer development or progression mechanisms. The last stage is characterized by cancer progression and migration, and karyotypic instability is considered an irreversible stage. However, the previous stage provides in-depth knowledge of molecular alteration, genetic changes in various tumor suppression genes, oncogenes, protooncogenes, and chromosomal aberrations. A better understanding of cancer etiology, initiation, and development of cancer has thoughtful consequences for targeting cancer biomarkers in developing therapeutics and considering agents/chemicals as carcinogens. In the cell death context, the fundamental process controlling the number of cells in tissue or organ development is apoptosis; however, in most cancers, the activation of oncogenes and dys-regulatory tumor suppressor genes occurs. The absence of apoptosis found in primary cancers makes the rapidly dividing cells unable to undergo the fundamental process of cell death.

2Various potential players play an active role in inhibiting cell proliferation. Here, we highlighted apoptosis regulating proteins/elements and other than apoptosis-inducing factors as a targeted strategy to regulate the process of carcinogenesis or cell proliferation. The apoptosis regulating strategy begins with the cell cycle—the regulators involved in cell division, cell arrest, and induction of apoptosis. The various genetic regulators of cell proliferation hold a remarkable role in cancer cell division and growth (as shown in Figure 2). The cell cycle plays a critical function in cellular genomic integrity and cell progression. It is important to know that the cell cycle comprises various stages such as the first one, G1 (gap 1), as well as the second, G2 (gap 2), and the last one, M (mitosis). For genetic information to be passed down across generations, DNA synthesis and genome replication must occur during the S phase. The M-phase is characterized by the separation of genetic information, the development of sister chromatids, and cell division. The G1 phase is the transition from M to S, while the G2 phase is the transition from S to M. These breaks (G1 and G2) are necessary to ensure that each phase is completed before moving on to the next.. Cell cycle checkpoints are frequently activated in response to replication stress and DNA damage. Cycle-dependent kinase activation and inactivation are critical for cell growth and cell cycle regulation.. In normal cell division, there is tight regulation at each checkpoint. Any dysregulation in those checkpoints results in the rapid division of cells without the hindering. The rapid division increases cell growth. Similarly, up-regulating the various pro-apoptosis proteins/elements and down-regulating the anti-apoptosis proteins might be a positive regulators of apoptosis. The signaling pathway is described in Section 3. The p53 role in induction apoptosis could be enhanced by up-regulating the transcription of mRNA and translated product. The use of inhibitors to suppress the activation of inhibitors of apoptosis (IAPs) also aids in the successful establishment of apoptosis in cancer cells. The other strategy involves various regulator proteins involved in cell progression and growth, such as MMPs (matrix metalloproteinases), play a vital role in cancer progression. MMP inhibition or blockade is a critical target for reducing metastatic potential. In addition to MMPs, metastasis suppressor genes such as MKK4 (mitogen-activated protein kinase 4), BRMS1 (breast cancer metastasis suppressor 1), and NM23 (non-metastasis gene 23) play important roles in metastasis inhibition.. Conventional therapy options are exceedingly tough, particularly in patients with metastatic disease. Invasion, intravasation, and extravasation are part of the metastatic pathway. The spread of cancer cells to distant places via the circulatory system marks the invasion phase. On the other hand, extravasation necessitates cancer cells penetrating the endothelium and the basement membrane. Cancer cells can develop in a secondary focus in extravasation.. Additionally, regulation of uPA and uPAR expression and TIMP expression are critical for metastasis prevention.. A complex net of signaling molecule cascades largely transduced several “pro-survival signaling pathways” that determined the fate of a cancer cell. Several cytokines and growth factors trigger pro-survival signaling cascades such as IP3K-PKB/Akt and MAPK. Nuclear factor-B (NFB) is a protein that plays a crucial function in controlling inflammation and immunological responses. The importance of blocking these pro-survival signaling pathways in various cancers has been thoroughly researched. Angiogenesis, autophagy, reduction of ER expression, intracellular ROS decrease production, and activation of “mitochondrial membrane potential” are among the signaling pathways that cause cytotoxicity in cancer cells.

3Apoptosis is an essential physiological process of cell death that is meant to occur without the discharge of intracellular contents, and subsequent no activation of an inflammatory response as apoptosis is a crucial process in embryonic development, regulation of the immune system, and the response to DNA damage. However, dysregulation of apoptosis results in significant consequences in carcinogenesis. The imbalance between cell proliferation and cell death is considered the malignant tumor’s hallmark. Therefore, maintaining cellular homeostasis between proliferation and cell death is essential for normal physiological processes.

4The signaling molecules of the apoptotic pathway played an essential role in the regulation of the apoptosis process. Therefore, these molecular proteins might be considered potential apoptotic biomarkers that can be targeted in advanced cancer treatment and therapeutics. Due to the development of potential biomarkers in cancer, targeted therapy research has emerged as an effective tool for cancer treatment compared to the conventional method. The standard chemotherapies act on rapidly dividing normal and cancerous cells, whereas targeted therapy plays an influential role as they act upon specific molecular targets related to specific cancer. The targeted apoptotic biomarkers in cancer are in clinical trials. However, the targeted therapies are designed so that they interact with their target, whereas many standard chemotherapies were identified because they kill cells. Furthermore, targeted therapies are often cytostatic as they block tumor cell proliferation, whereas standard chemotherapy agents are cytotoxic and kill tumor cells). Therefore, the apoptotic biomarkers and chemotherapy could combine targeted drug therapy to get the maximized results. Apoptosis has been extensively investigated over the last two decades. It is now a critical process of controlled death activated in response to cell injury and during normal “development and morphogenesis.” For instance, the apoptotic death of nearly half of newly produced peripheral neurotransmitters throughout formation forms the nervous system of vertebrates to regulate their quantity, so it matches the requirements of their target organs in the peripheral. Induction of apoptosis is essential for complex organisms’ embryonic development and differentiation equilibrium. It occurs in a controlled manner, with characteristic morphologic markers such as “cell shrinkage, “chromatin condensation,” and “blabbing of the cytoplasmic membrane.” Apoptosis dysregulation has indeed been linked to several pathologies, notably tumor growth and the formation of cancerous cells’ chemoresistance. Among mammals, apoptosis is triggered by two well-known pathways (Figure 3). Extrinsic signals, such as TNF “tumor necrosis factor,” Fas (CD95/APO1), and TRAIL (TNF-related apoptosis-inducing ligand receptors), might induce apoptosis. In contrast, internal stimuli, including mitochondrial transduction, also can trigger apoptosis. For example, the activation of cysteine aspartyl proteases (caspases) causes permeabilization of mitochondrial membranes, chromatin condensation, and DNA fragmentation, resulting in cell death.

5The intrinsic route is triggered by physical and chemical inputs, including hypoxic conditions, growth factor shortages, cell detachment, and stress signals. The initiator caspases activation activates effector caspases; these are “aspartate-specific proteases” regulated post-translationally. Caspase inside as inactive proenzyme consists of a prodomain (a small and large subunit), which must be oligomerized and cleaved to activate. On the other hand, Caspases-independent apoptosis has been documented. The death ligand binds the intracellular death domain of death receptors to begin the extrinsic pathway. Many apoptotic signals are relayed to cell death machinery by p53, which interacts with other proteins like TNF, Fas, and TRAIL receptors, which are particular physiologic mediators of the extrinsic signaling route of apoptosis. Mitochondria have a role in several vital processes, including the caspase activators (cytochrome C), alterations in electron transport, mitochondrial membrane potential regulation, and the involvement of both pro-and antiapoptotic Bcl-2 family proteins.

6The proteins involved in the intrinsic route are “SMAC/DIABLO, Caspase-9, Bcl-2, Bcl-w, and Nox. The intrinsic mechanism involves “Bax/Bak membrane insertion and cytochrome c release from the mitochondrial intermembrane gap into the cytosol. The apoptosome is a multi-protein complex consisting of a “seven-spoke ring-shaped complex” that activates caspase 9 and then the caspase-3 signaling cascade, which leads to cell destruction and apoptosis. According to experimental findings, caspases have an overwhelming role in apoptosis. There is a hopeful future for cancer therapy techniques that induce apoptosis in cancer cells by disrupting mitochondrial biogenesis, outflowing matrix calcium glutathione, or releasing membrane proteins due to mitochondrial failure. Anti-apoptotic proteins Bcl-2 and Bcl-xL block the cytochrome c release. The development of a death-inducing signaling complex DISC which is made up of the adaptor molecule Fas-associated death domain (DD), procaspase-8, procaspase-10, and the cellular FLICE inhibitory proteins, is caused by the activation of SDRs by specific death ligands (DLs). This Caspase 8 is activated in a real way that the “prodomain of caspase 8″ remains attached to the DISC. In contrast, the “active caspase 8 dissociates from the DISC” to initiate the cascade of caspase activation that occurs during the “execution phase of apoptosis. Traditionally, “caspases have been divided into i) initiator, ii) effector, and iii) executioner” types based on where they are located in an apoptotic signaling chain. At the same point, both extrinsic and intrinsic paths converge (execution phase). The execution phase is the last step in the apoptotic process. Certain caspases have lengthy pro-domains that contain specific motif sequences, such as the death effector domain (DED) and caspase recruitment domains (CARD), which enable them to interact with other proteins and connect to signaling pathways. Caspases-1, caspase-2, caspase-4, caspase-5, caspase-9, caspase-11, and caspase-12 are involved in DED, whereas caspase-1, caspase-2, caspase-4, caspase-5, caspase-9, caspase-11, and caspase-12 are involved in CARD. Caspases are critical apoptosis initiators and executors, and their function is strongly linked to their structure, which has distinct substrate preferences. The “Caspase-8 and 9 are initiator caspases, while Caspase-3, Caspase-6, Caspase-7, Caspase-10, CAD, and PARP” are effector or executioner caspases. Caspase initiators are triggered by autocleavage, activating executioner caspases, which later proteolyze certain substrates, resulting in apoptosis. They have extended pro-domains that link big adaptor molecules, allowing them to multimerize and activate other caspases. However, effector caspases, on the other hand, have “short pro-domains” that execute apoptosis when activated by initiator caspases. As a result of the cytoplasmic endonuclease activated by executor caspases, chromatin condenses, cytoplasmic blebs develop, and apoptotic bodies are formed. Numerous target proteins are cleaved by caspases to regulate apoptotic cell death. Caspases 3 and 4 are the essential executioner caspases, and an initiator caspase can activate them. Caspases-3 specifically activates endonuclease CAD, resulting in chromosomal DNA degradation and chromatin condensation inside nuclei. The cytoskeletal rearrangement and generation of cytoplasmic blebs and apoptotic bodies are both dependent on execution caspases. Execution caspases are activated first, followed by cytoplasmic endonuclease activation. Interestingly, nuclear material is degraded by cytoplasmic endonuclease, and proteases then degrade nuclear and cytoskeletal proteins.

7An anti-cancer treatment mainly kills cancer cells and may or may not cause side effects to healthy cells. Currently accepted cancer therapy methods include a combination of medications, surgery, radiation, or a combination of all of these. Chemotherapeutic drugs can relieve symptoms, extend life, and even cure cancer in some cases. One of the best cancer drugs has a low risk of harming healthy cells in treating patients. Apoptosis substantially impacts both the lifespan of healthy cells and the prognosis of malignant cells. As a result, regulating default apoptosis could benefit cancer treatment and prevention. The aberrant response of malignant cells to apoptosis induction is caused by excessive cellular proliferation, which can also be described as overexpression of inhibitors or IAP family members. The Cell cycle-regulating genes are inactivated in cancer cells, and Bcl-2) adjusts their expression in tumors. Different malignancies, inflammatory illnesses, viral infections, and autoimmune diseases are caused by inhibiting or suppressing apoptosis.

8Interestingly, apoptotic induction has emerged as a novel target for novel mechanism-based drug discovery. Previously, it was thought that an increase in cellular proliferation was only linked to the rise in the number of cells accumulating in the body; however, it has now been discovered that a decrease in cell death is also responsible for cell proliferation. As a result, it is crucial to screen apoptotic inducers from natural products, either as crude extracts (plants or animal/marine organisms) or as separated components. Various studies have found evidence that compounds derived from natural sources effectively treat and prevent cancer. The isolated secondary metabolites from multiple natural sources, and mechanistic study (in-vitro), give better molecular fundamental knowledge of the future therapeutic agent. Various plants extracts, fractions, synthetic palladium, and other complexes are used to screen cytotoxicity and mode of cell death, which reduces the cost of isolation of phytochemicals and synthetic compounds and gives insight into a potential therapeutic agent. The ability to trigger apoptosis may serve as a unifying principle for many distinct types of chemo preventive drugs, each with a unique mode of action. Also, insight into the mechanisms of action of these chemicals could lead to new cancer-preventive and treatment strategies. Synthesis or modification of previously recognized medications in cancer treatment is still a significant research focus. Despite massive amounts of synthetic effort, the final products have improved slightly over a few prototypes. Thus, there is a constant demand for new chemotherapeutic agent prototypes–templates to develop more effective chemotherapy. Natural products (NPs) serve as models for new prototypes in the search for drug discovery. Apart from chemotherapy treatment, epidemiological studies suggest that eating lots of fruits and vegetables, rich in phytochemicals and other nutrients, may lower one’s risk of getting cancer. In addition, it has been shown that natural product-derived tumor inhibitory chemicals have revealed a remarkable array of novel structural forms.

9Apoptosis is a cell death process that is conserved and well-controlled. It is essential to complex organisms’ development and homeostasis. Apoptosis inducers work very well in causing cytotoxicity in cancer cells. Due to their selective targeting of cancer cells, dys-regulatory apoptosis machinery only targets normal cells compared to cytotoxic agents. Therefore, they can work along with potential chemotherapy and reduce the risk of re-occurrence via killing the cell in a natural suicidal way. One of the essential factors in combination medication therapy is awareness of diverse phytochemicals and their synergistic approach. By indicating the presence of a potential agent, the extracts/fractions screening lowers the cost of phytochemical separation. Apoptosis’s external and intrinsic triggers include; radiation, growth factor withdrawal, ligands, tumor suppressor protein (p53), and oxidative stress. Additional pathological activities associated with the physiologic apoptosis pathway include cancer, inflammatory, and neurological diseases. As shown in a substantial body of research, many cancerous tumors have a decreased capacity to die by apoptosis in reaction to physiological stimuli. Therefore, it is critical to broadening the chemical repertory of agents that might induce or sensitize resistant cells to apoptosis to combat cancer. Furthermore, employing natural compounds as anti-carcinogenic or cytotoxicity-inducing compounds may be promising cancer prevention and therapy strategy. An in vitro investigation of secondary metabolites from various natural sources provides a better understanding of the molecular fundamentals of the therapeutic drug in the future.

10Alkaloids are chemical compounds found in nature that are predominantly made up of basic nitrogen atoms, neutral groups, and mildly acidic. Alkaloid Solamargine, located in the Chinese Plant Solanum incanum, has been demonstrated to trigger apoptosis in cancer cells (Hep-3B) and standard (“skin fibroblast cells”). Also, the level of TNF receptor I significantly elevated after solamargine treatment. Necrophilia guyanensis and Genipa Americana extract fractionation contain alkaloid cryptolepine, which appeared as the predominant active component. The cryptolepine compounds demonstrated substantial cytotoxic effects in human cells via the underlying mechanisms of apoptosis. Camptothecin (CPT), an inhibitor of topoisomerase I, causes triggered Oxygen radicals which cause DNA fragmentation and eventually induction and completion of apoptosis..

11The monoterpenes D-limonene and perillyl alcohol were found to have anti-carcinogenic properties in various cancer cell lines by exhibiting apoptosis. For example, perillyl alcohol was very effective in causing cell death of breast cancer cells. Similarly, Limonene inhibits stomach carcinogenesis caused by sodium chloride by enhancing apoptosis. Taxol is a cytotoxic diterpene discovered in Taxus brevifolia that suppresses cell growth and proliferation. The mechanism of action is triggered via stabilizing power of Taxol during the spindle fiber formation in the cell division stage (mitosis). The polymerization of the Microtubule and improved stimulation of the formation of microtubule (MT) bundle impeded entry into the S phase, limiting cell division and apoptosis and also triggering necrosis at higher concentrations of Taxol. However, Paclitaxel-induced cell death also occurs via a signaling pathway not dependent on G2/M arrest.

12Polyphenols obtained from Plant are abundant in the human diet and are deemed healthy at the recommended dose (one G/day). A range of mutated cell lines show that gallic acid predominantly induces cell death. Similarly, in HL-60 cells, caffeine and tannic acids induce DNA breakage. CAPE, the main ingredient in traditional medicinal propolis, has been shown to have particular cytotoxic activity against mutated cloned rat embryo fibroblast (CREF) cells by apoptotic cell death. CAPE, the main ingredient in traditional medicinal propolis, has been shown to have particular cytotoxic activity against mutated cloned rat embryo fibroblast (CREF) cells by apoptotic cell death. It has been established and demonstrated that curcumin, the primary color in turmeric, is a phenolic compound that causes apoptosis—a beneficial chemotherapeutic addition since it does not affect normal cells. The activation of apoptosis was boosted by curcumin’s ability to block cyclooxygenase (COX) products. Moreover, chilli pepper and hot red pepper contain capsaicin, triggering HL-60 cells to undergo apoptosis.

13Xanthones are found in the naturally occurring substances in both plants and microbes. This new species from marine fungi contains anti-cancer xanthone compounds, which have been noticed recently. This is established that toxic compounds and anti-carcinogenic medication breakdown and elimination affect certain proteins. Xanthone compounds with anti-carcinogenic characteristics may be found in aquatic species and microalgae. In mangostana’s pericarp -mangostin, the xanthone induced apoptosis via up-regulation of caspase-3.

14The Table 1 shows the list of potential plant extracts as apoptotic inducers. Pepino, the extract was essential for the onset of DNA fragmentation and PARP cleavage. Similarly, Viscum album L. (Loranthaceae) extract in human lymphocytes causes cytotoxicity, more probably via apoptosis. Salvia miltiorrhiza is often used to cure liver problems throughout Asia for centuries. Investigators found that sage salvia miltiorrhiza extracts showed significant cytotoxic activity and could have reduced the human hepatoma (HepG2) cell line. Apoptosis was shown to drive the cytotoxic activity of Conifer Tetraclinis articulate (essential oil) on several human cancers, including blood lymphocytes. Bussing et al. employed a seed extract of these and discovered that it produced oxygen radical mediators and induction of apoptosis. The “tumor necrosis factor” (alpha) and “interleukin-6" (IL-6) constitute pro-inflammatory factors, whereas “interleukin-5" (IL-5) and “interferon-gamma” (IFN-g) are T-cell associated cytokines. Genistein (a hydroxyisoflavone) was found to induce cell death in human promyelocytic (HL-60) leukemic cells according to flow cytometric analysis. Vitex rotundifolia (leave) fraction remarkably induces apoptosis in MCF-7 & T47D via extrinsic and intrinsic pathways. Squamous cell carcinoma was inhibited by an ethanolic extract of Azadirachta indica (neem) leaves in a hamster cancer model. The presence of extract increased the pro-apoptotic proteins (caspase-3 and -8, BIM, and Bcl-2), indicating that both internal and external mechanisms were significantly impacted. The Bax and Bcl-2 are up-regulated in breast cancer cell lines (MCF-7 and MDA-MB-231) by Phaseolus vulgaris (Fabaceae) extract treatment in cells, respectively (Bcl-2, Bcl-xL). In addition, a methanolic extract of Fragaria ananassa (Strawberry) increased Bax, Bid, and p73 expression in T-47D cells while decreasing Bcl-xL expression. According to apoptosis-inducing meisoindigo, the receptors on the cell surface and mitochondria are involved, according to the study. The colorectal cancer cell lines, methyl ferulate, a Tamarix aucheriana plant product, enhanced caspase-2, -3, -6, -7, -8, and -9 expression while decreasing the anti-apoptotic proteins Bcl2 and FLIP. Inula racemosa (also known as pushkarmool) roots induced apoptosis and necrosis in human leukaemia cell line HL-60 when treated with an ethanolic extract of Inula racemosa roots. While cytochrome C (release) and Bax (translocation) dramatically reduced, this substance boosted the activity of Caspase-9, -3, and -8. The activation of intrinsic caspase-6, -8, and-9 by Oenocarpus bacaba aqueous extract promoted apoptosis in MCF-7 cells. Solanum lyratum (known as nightshades) chloroform extract is triggered by the extrinsic and intrinsic apoptotic mechanism in HSC-3, CAL-27 & SAS cancer cells. Among the cell lines studied, the extract decreased anti-apoptotic proteins (Bcl-2 and Bcl-xl) while elevating pro-apoptotic (Bax and Caspases). The cardiac glycoside (Ouabain) significantly decreased ROS and MMP levels while increasing Ca2+, activation of pro-apoptotic members, and reduced expression of Bcl-2 levels. The cardiac glycoside (Ouabain) significantly decreased ROS and MMP levels while increasing Ca2+, activation of “pro-apoptotic” members, and reduced expression of Bcl-2 levels. Cell cycle arrest and apoptosis were caused by “Rosamultic acid,” a triterpenoid, which cleaves PARP and activates caspase-3, -8, and -9 in SGC-7901 cells. A flavonoid produced from plants, Acacetin triggers an apoptotic cascade in stomach cancer cells (AGS cells) and kills them. “When ROS are produced, MMP collapses and “Bax and p53″ are increased “Bcl-2 is decreased”. Extrinsic activation of “caspase-8 and Bid proteins” is facilitated by an increase in the expressions of Fas and FasL. Caspase-8 and Caspase-7 were activated in breast cancer (MCF-7) cells after exposure to extracts (methanol and & butanol) of “Oldenlandia diffusa” (Willd) Roxb. As a result, Bax expression was increased, and Bcl-2 levels were decreased. Cell death was prevented in MCF-7 cells by Cucurbita ficifolia (chloroform) extract. There was an increase in the expression of FADD, BAK, BAX, and caspase-8, -9, and -3. Lycorine, an alkaloid molecule (from the Amaryllidaceae family), has been shown to enhance the “Bax/Bcl-2″ protein ratio and the activity of caspase-(8, -9, and -3) enzymes in cells compared to untreated cells. A mango peel ethanolic extract (Mangifera indica) has been shown to cause the death of HeLa cells. As a result of activating pro-apoptotic proteins (caspase-3, 7, 8 & 9) and the suppression of Bcl-2. Celastrol, a pentacyclic triterpenoid, induces apoptosis via acting on receptor protein (death receptor) and internal pathways. Celastrol stimulated the signal transduction in mitochondria and increased Bax while decreasing Bcl-2 protein levels in the intrinsic route. To increase the expression of FAS and FASL, it induced FASL expression in the extrinsic pathway. Because celastrol activated caspases 9, 8, 3, and PARP, these enzymes began to break down proteins. Using a mouse model of cancer, Celastrol prevents the development of human glioblastoma xenografts by suppressing angiogenesis. It also induces apoptosis in osteosarcoma cells and increases the activities of pro-apoptotic caspase-3, -8, and 9. An ethanolic extract of Brucea javanica fruits was discovered to have apoptotic properties when tested on colon cancer (HT29) cells. The drug’s mode of action involves both receptor- and mitochondrial-mediated processes. The extract also increased TNF2 and DR6 in the extrinsic route. Caspase-8 and TRAIL-4 were also increased. Caspase-9 was also activated, which led to an increase in Bax, Bad, and cytochrome-c while decreasing Bcl-2. Experiments on human cancer cell lines have shown that plant extracts can activate intrinsic and extrinsic pathways to cause cell death. They were also beneficial in vivo, killing cancer cells and delaying cancer progression. Because of this, even though these plant extracts have long been used in traditional cancer treatments, western science and medicine need proof of their anti-cancer properties using pure plant compounds isolated from plants. The intrinsic and external mechanisms in adult tumor cells can be affected by an N, N-dimethyl plant sphinganine (DMPS) derivative known as phytosphingosine (PS) (HL-60 cells). -Caspase-8 activation is a major element at the beginning of the intrinsic pathway, followed by the cytochrome C release and activation of pro-apoptotic proteins (caspase-9 and caspase-3, and inhibition of Bcl-2 (anti-apoptotic members of the family. Anthocyanins, a kind of flavonoid, are well-known for their medicinal qualities. Anthocyanin components produced from Vitis coignetiae destroy human leukaemia (U937) cells by apoptosis induction in these cells. Bax levels rise when Bid and caspases 3, 9, and 8 are activated, followed by a decrease in MMP, Bcl-2, and other MMPs, cIAP-1, and cIAP-2 levels well. Anthocyanins, which induce apoptosis, did not affect U937 cells with elevated Bcl-2 protein levels. breast cancer (“MDA-MB-468″) cells treated with extracts (“Vatica diospyroides”) exhibit apoptosis as a result of Bax upregulation. An Anemone raddeana triterpenoid molecule, raddeanin A, is shown to activate apoptosis in stomach cancer cells. Raddeanin A upregulation pro-apoptotic protein (Bax) while decreasing the expressions of anti-apoptotic (BCL-xL) using molecular biology techniques. Additionally, in all three cell lines, this terpenoid increased the activity of caspase-3, -8, and -9, and the PARP enzyme. Non-small cell lung cancer cells” can be made to die by LA, which inhibits Bcl-2, FLIP, and XIAP while increasing “Bid” and caspase-3, -,8-9. LA is derived from the leaves of the Pinus koraiensis tree. The sBax and protein caspases up-regulated treated with Momordica cochinchinensis fruit extract, inducing apoptosis in MCF-7. Using 34 HL-60 cells, ethyl acetate extract from Uncaria tomentoa (ethyl acetate (EA) extract) was found to activate the intrinsic pathway by compressing Matrix Metallo Protein and lowering anti-apoptotic (Bcl-XL protein), as well as by raising the membrane-bound Fas and activating caspase-8. Protoberberine activated pro-apoptotic caspases, promoting cell death (apoptosis) in tongue cancer cells. Increased ratio (Bax/Bcl-2) and altered matrix protein were also observed. Two breast cancer cells were injected into athymic nude mice, and wogonin was found to have an anti-cancer effect in vivo. After 4 weeks of treatment, the xenograft burden was reduced by 88 percent. Apoptosis in “breast cancer” (MCF-7) cells is caused by the methanolic fractions of Scrophularia oxystepala. oleandrin, a carcinogenic glycoside, kills cancer cells in the U2OS and SaOS-2 lines by inducing cell apoptosis through the ROS Generation as well as the damage of Mitochondrial membrane potential, which discharges hydrolytic Enzymes into the cytosol and regulates the proteins (decreases the Bcl-2 level and increase Bax) along with caspases (caspases 9 and 8 and -3.

15Aquatic environments, especially marine species, contain abundant various natural compounds which may have therapeutic significance. However, recent marine biomaterials experience demonstrates that ocean life seems to be an untapped resource. Bioactive compounds found naturally are the most effective. Apart from a few exceptions, most compounds used in medicines originate through biological and chemical modifications rather than from the initial natural substance. Our previous studies confirm apoptosis induction in the cancer cell (in-vitro) by marine extracts and fractions. The Aaptos sp., marine (fraction) causes the DNA fragmentation in the MCF-7 cell line, which is a remarkable feature of apoptosis (late). Similarly, marine sponges (whole) extracts and fractions also induce the fragmentation in DNA in breast cancer (MCF-7) cell lines. The details information mention in Table 2. The “Stichopus chloronotus” and “Holothuria nobilis” fractions induced cytotoxicity via apoptosis induction in cervical cancer (HeLa) cells shows the remarkable potential of marine phytochemicals in the induction of apoptosis. The “Bruguiera gymnorrhiza” extracts potential phytochemicals that trigger DNA fragmentation, leading to the induction of apoptosis in MCF-7 cells. The other marine species, “Acanthaster planci” sp., and “Diadema setosum” sp., fractions Induction of apoptosis in HeLa cells. The “Xylocarpus moluccensis” induce the triggering of the Extrinsic pathway of apoptosis which causes the primary factor for cytotoxicity of fractions in human hepatocellular carcinoma (HepG2) and human cervical cancer cell line (HeLa). Some alkaloid chemicals discovered in traditional medicines, tetrandrine (TET) and cepharanthine (CEP), operate as apoptotic agents. There is reduction in the progression of malignant tumors. When viewing human leukemia cells treated with alkaloids, Xu et al. found that both initiator and effector caspases were dramatically increased (caspase-3 and& -6). Saikosaponin A, a triterpenoid saponin, was studied by Kim and colleagues to see if it could kill human colon cancer cell lines. According to the researchers’ findings, the activation of Bax and Bid proteins and the activation of caspase-2, -8, and -9 in saikosaponin A increased apoptosis in cells. Emodin (40 mg/kg/day) suppressed tumor weight in “nude mice xenografts” carrying “LS1034” colon cancer cells in vivo, according to in vitro findings. “Anti-apoptotic” proteins “Bcl-2” and Bcl-xL, Bax, XIAP and cFLIP are reduced in “HT-29”, “HCT-116” and “SW480” cells by the flavonoid compound Casticin. The “OVCAR-3” and “SKOV-3” (ovarian cancer) cell lines were exposed to kaempferol (kaempferol), a flavonoid, the levels of apoptosis-inducing factors like proteins (Bax, caspase-3, -8, & -9) were significantly increased. In contrast, apoptosis inhibiting proteins decreased in these cells. Similar outcomes were found when combined with the anti-inflammatory agent TRAIL.

16Besides extracts/fractions, the various marine-based drug also show apoptosis-inducing potential. And over 50 years since cytarabine was authorized, four marine-derived drugs have been approved. Some other items have been included in the marine anticancer medicinal route in clinical studies in different phases of development as we focused on apoptotic inducers. Table 3 shows the list of respective drugs (approved or in clinical trials) having the potential for inducing apoptosis. These include; Brentuximab2 vedotin (AdcetrisTM), Brentuximab2 vedotin (AdcetrisTM), as “Antibody-drug3 conjugate in a mixture of anti-CD30 antibody and monomethyl auristatin E (MMAE), isolated from sea hare Dollabella auricularia/cyanobacteria” used for Blockage in cell cycle progression (G2 to M) induce induction of apoptosis phase III and I treatment of classical HL in a mixture using chemotherapy for curing HL and chronic large cell anaplastic lymphoma. Enfortumab vedotin, Marizomib, Polatuzumab Vedotin, use in phase III. Besides, GSK2857916, Aplidine, plitidepsin (Aplidin), Ladiratuzumab vedotin, Glembatumumab vedotin, Denintuzumab mafodotin, in phase II trials. However, Pinatuzumab vedotin, ASG-15ME, CEP-2563, Lifastuzumab vedotin, and Vandortuzumab vedotin were discontinued after phase I used for lymphoma, bladder, ovarian, as Peritoneal cancer. Vandortuzumab isolated from Cyanobacterium. (Caldora penicillata) acts as apoptotic inducer and mitotic inhibitor for Prostate cancer.

17The potential use of natural substances as either a combination treatment with standard therapies or as an individual derivative molecule as anticancer medicine requires an understanding of cancer initiation and activation of cancer development, the role of signalling pathway in activation of cancer initiation and progression, pro-oncogenes, and oncogenes. Since apoptosis is a crucial regulating mechanism for normal cells, any disruption in this process might lead to unchecked cell growth. An in-depth mechanistic knowledge of apoptotic signalling pathways is necessary for the creation of efficient cancer therapies. Plant extracts, marine extracts/fractions, and the chemicals described in this research may represent a promising and efficient approach to cancer treatment. Researchers found that natural product derivatives may have an important role in the prevention and treatment of several different types of cancer. To verify their overall usefulness as potent chemotherapeutic drugs, however, more preclinical and clinical research are required. It is interesting to note that natural compounds produced from plant extracts/marine can be used in combination with possible anticancer treatment to enhance drug sensitivity in aggressive and resistant kind of cancer. Due to the promising results seen when using natural goods in conjunction with cancer medications, intensive study into the therapeutic uses of natural products is required to get the best possible outcomes in individualized, targeted cancer care. Similarly, the use of more than one compounds as multitargeted signaling pathway inhibitors or activator should be consider with one signaling target as apoptosis pathway. However, natural chemical derivatives that induce apoptosis, along with cutting-edge drug delivery methods like polymeric nanoparticles, may yield impressive results. Compounds with low solubility and bioavailability are less likely to be effective in the development of chemotherapy drugs. In conclusion, this study aims to bring to the notice of scientists and researchers the numerous beneficial impacts of natural products in the development of novel and safe pharmaceuticals or in combine delivery technique with anticancer treatments for probable sensitization of cancer therapy. It might also serve as a solid basis for further research into natural compounds in cancer therapeutics.