Mitochondria-Judges and Executioners of Cell Death Sentences

Dynamic Changes of the Mitochondria in Psychiatric Illnesses: New Mechanistic Insights From Human Neuronal Models

Mitochondria play a crucial role in neuronal function, especially in energy production, the generation of reactive oxygen species, and calcium signaling. Multiple lines of evidence have suggested the possible involvement of mitochondrial deficits in major psychiatric disorders, such as schizophrenia and bipolar disorder. This review will outline the current understanding of the physiological role of mitochondria and their dysfunction under pathological conditions, particularly in psychiatric disorders. The current knowledge about mitochondrial deficits in these disorders is somewhat limited because of the lack of effective methods to dissect dynamic changes in functional deficits that are directly associated with psychiatric conditions. Human neuronal cell model systems have been dramatically developed in recent years with the use of stem cell technology, and these systems may be key tools for overcoming this dilemma and improving our understanding of the dynamic changes in the mitochondrial deficits in patients with psychiatric disorders. We introduce recent discoveries from new experimental models and conclude the discussion by referring to future perspectives. We emphasize the significance of combining studies of human neuronal cell models with those of other experimental systems, including animal models.

Antiapoptotic BCL-2 proteins determine sorafenib/regorafenib resistance and BH3-mimetic efficacy in hepatocellular carcinoma

Sorafenib, systemic treatment for advanced hepatocellular carcinoma (HCC), and regorafenib, novel second line treatment after sorafenib failure, have efficacy limited by evasive mechanisms of acquired-drug resistance. BCL-2 proteins participate in the response to tyrosine kinase inhibitors; however, their role in HCC therapy with sorafenib/regorafenib remains uncertain. BH3-mimetic ABT-263 (navitoclax) enhanced sorafenib activity, inducing cell death via a mitochondrial caspase-dependent mechanism, after BCL-xL/BCL-2 inhibition. Sorafenib-resistant hepatoma cells (HepG2R and Hep3BR) exhibited altered mRNA expression of BCL-2 and other anti-apoptotic family members, such as MCL-1, priming drug-resistant cancer cells to death by BH3-mimetics. ABT-263 restored sorafenib efficacy in sorafenib-resistant cell lines and HCC mouse models. Moreover, in mice xenografts from patient-derived BCLC9 cells, better tumor response to sorafenib was associated to higher changes in the BCL-2 mRNA pattern. HCC non-treated patients displayed altered BCL-2, MCL-1 and BCL-xL mRNA levels respect to adjacent non-tumoral biopsies and an increased BCL-2/MCL-1 ratio, predictive of navitoclax efficacy. Moreover, regorafenib administration also modified the BCL-2/MCL-1 ratio and navitoclax sensitized hepatoma cells to regorafenib by a mitochondrial caspase-dependent mechanism. In conclusion, sorafenib/regorafenib response is determined by BCL-2 proteins, while increased BCL-2/MCL-1 ratio in HCC sensitizes drug resistant-tumors against ABT-263 co-administration. Thus, changes in the BCL-2 profile, altered in HCC patients, could help to follow-up sorafenib efficacy, allowing patient selection for combined therapy with BH3-mimetics or early switch them to second line therapy.

Molecular mechanisms of cell death: recommendations of the Nomenclature Committee on Cell Death 2018

Over the past decade, the Nomenclature Committee on Cell Death (NCCD) has formulated guidelines for the definition and interpretation of cell death from morphological, biochemical, and functional perspectives. Since the field continues to expand and novel mechanisms that orchestrate multiple cell death pathways are unveiled, we propose an updated classification of cell death subroutines focusing on mechanistic and essential (as opposed to correlative and dispensable) aspects of the process. As we provide molecularly oriented definitions of terms including intrinsic apoptosis, extrinsic apoptosis, mitochondrial permeability transition (MPT)-driven necrosis, necroptosis, ferroptosis, pyroptosis, parthanatos, entotic cell death, NETotic cell death, lysosome-dependent cell death, autophagy-dependent cell death, immunogenic cell death, cellular senescence, and mitotic catastrophe, we discuss the utility of neologisms that refer to highly specialized instances of these processes. The mission of the NCCD is to provide a widely accepted nomenclature on cell death in support of the continued development of the field.

A matter of life and death: stem cell survival in tissue regeneration and tumour formation

In recent years, great strides have been made in our understanding of how stem cells (SCs) govern tissue homeostasis and regeneration. The inherent longevity of SCs raises the possibility that the unique protective mechanisms in these cells might also be involved in tumorigenesis. In this Opinion article, we discuss how SCs are protected throughout their lifespan, focusing on quiescent behaviour, DNA damage response and programmed cell death. We briefly examine the roles of adult SCs and progenitors in tissue repair and tumorigenesis and explore how signals released from dying or dormant cells influence the function of healthy or aberrant SCs. Important insight into the mechanisms that regulate SC death and survival, as well as the 'legacy' imparted by departing cells, may unlock novel avenues for regenerative medicine and cancer therapy.

UPRmt regulation and output: a stress response mediated by mitochondrial-nuclear communication

The mitochondrial network is not only required for the production of energy, essential cofactors and amino acids, but also serves as a signaling hub for innate immune and apoptotic pathways. Multiple mechanisms have evolved to identify and combat mitochondrial dysfunction to maintain the health of the organism. One such pathway is the mitochondrial unfolded protein response (UPRmt), which is regulated by the mitochondrial import efficiency of the transcription factor ATFS-1 in C. elegans and potentially orthologous transcription factors in mammals (ATF4, ATF5, CHOP). Upon mitochondrial dysfunction, import of ATFS-1 into mitochondria is reduced, allowing it to be trafficked to the nucleus where it promotes the expression of genes that promote survival and recovery of the mitochondrial network. Here, we discuss recent findings underlying UPRmt signal transduction and how this adaptive transcriptional response may interact with other mitochondrial stress response pathways.

Marsdenia tenacissimae extraction (MTE) inhibits the proliferation and induces the apoptosis of human acute T cell leukemia cells through inactivating PI3K/AKT/mTOR signaling pathway via PTEN enhancement

Marsdenia tenacissimae extraction (MTE) as a traditional Chinese herb has long been used to treat some diseases such as tumors in China. However, the potential effectiveness of MTE in leukemia has not yet been fully understood, and the related molecular mechanism is still unknown. In the present study, we aimed to evaluate the effects of MTE on the proliferation and apoptosis of Jurkat cells (T-ALL lines) and lymphocytes from T-ALL (T-cell acute lymphoblastic leukemia) patients. Firstly, CCK8 assays and flow cytometry assays revealed that MTE dose-dependently reduced the proliferation of Jurkat cells by arresting cell cycle at S phase. Secondly, Annexin V-FITC/PI-stained flow cytometry and TUNEL staining assays showed that MTE promoted the apoptosis of Jurkat cells. Mechanistically, MTE enhanced PTEN (phosphatases and tensin homolog) level and inactivated PI3K/AKT/mTOR signaling pathway in Jurkat cells, which mediated the inhibition of cell proliferation by MTE and MTE-induced apoptosis. Finally, MTE significantly inhibited the proliferation and promoted the apoptosis of lymphocytes from T-ALL patients, compared with lymphocytes from healthy peoples. Taken together, these results reveal an unrecognized function of MTE in inhibiting the proliferation and inducing the apoptosis of T-ALL cells, and identify a pathway of PTEN/PI3K/AKT/mTOR for the effects of MTE on leukemia therapy.

Iterative optimization yields Mcl-1-targeting stapled peptides with selective cytotoxicity to Mcl-1-dependent cancer cells

Bcl-2 family proteins regulate apoptosis, and aberrant interactions of overexpressed antiapoptotic family members such as Mcl-1 promote cell transformation, cancer survival, and resistance to chemotherapy. Discovering potent and selective Mcl-1 inhibitors that can relieve apoptotic blockades is thus a high priority for cancer research. An attractive strategy for disabling Mcl-1 involves using designer peptides to competitively engage its binding groove, mimicking the structural mechanism of action of native sensitizer BH3-only proteins. We transformed Mcl-1-binding peptides into α-helical, cell-penetrating constructs that are selectively cytotoxic to Mcl-1-dependent cancer cells. Critical to the design of effective inhibitors was our introduction of an all-hydrocarbon cross-link or "staple" that stabilizes α-helical structure, increases target binding affinity, and independently confers binding specificity for Mcl-1 over related Bcl-2 family paralogs. Two crystal structures of complexes at 1.4 Å and 1.9 Å resolution demonstrate how the hydrophobic staple induces an unanticipated structural rearrangement in Mcl-1 upon binding. Systematic sampling of staple location and iterative optimization of peptide sequence in accordance with established design principles provided peptides that target intracellular Mcl-1. This work provides proof of concept for the development of potent, selective, and cell-permeable stapled peptides for therapeutic targeting of Mcl-1 in cancer, applying a design and validation workflow applicable to a host of challenging biomedical targets.

Electroacupuncture preconditioning protects against focal cerebral ischemia/reperfusion injury via suppression of dynamin-related protein 1

Electroacupuncture preconditioning at acupoint Baihui (GV20) can reduce focal cerebral ischemia/reperfusion injury. However, the precise protective mechanism remains unknown. Mitochondrial fission mediated by dynamin-related protein 1 (Drp1) can trigger neuronal apoptosis following cerebral ischemia/reperfusion injury. Herein, we examined the hypothesis that electroacupuncture pretreatment can regulate Drp1, and thus inhibit mitochondrial fission to provide cerebral protection. Rat models of focal cerebral ischemia/reperfusion injury were established by middle cerebral artery occlusion at 24 hours after 5 consecutive days of preconditioning with electroacupuncture at GV20 (depth 2 mm, intensity 1 mA, frequency 2/15 Hz, for 30 minutes, once a day). Neurological function was assessed using the Longa neurological deficit score. Pathological changes in the ischemic penumbra on the injury side were assessed by hematoxylin-eosin staining. Cellular apoptosis in the ischemic penumbra on the injury side was assessed by terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling staining. Mitochondrial ultrastructure in the ischemic penumbra on the injury side was assessed by transmission electron microscopy. Drp1 and cytochrome c expression in the ischemic penumbra on the injury side were assessed by western blot assay. Results showed that electroacupuncture preconditioning decreased expression of total and mitochondrial Drp1, decreased expression of total and cytosolic cytochrome c, maintained mitochondrial morphology and reduced the proportion of apoptotic cells in the ischemic penumbra on the injury side, with associated improvements in neurological function. These data suggest that electroacupuncture preconditioning-induced neuronal protection involves inhibition of the expression and translocation of Drp1.

MOMP, cell suicide as a BCL-2 family business

Apoptosis shapes development and differentiation, has a key role in tissue homeostasis, and is deregulated in cancer. In most cases, successful apoptosis is triggered by mitochondrial outer membrane permeabilization (MOMP), which defines the mitochondrial or intrinsic pathway and ultimately leads to caspase activation and protein substrate cleavage. The mitochondrial apoptotic pathway centered on MOMP is controlled by an intricate network of events that determine the balance of the cell fate choice between survival and death. Here we will review how MOMP proceeds and how the main effectors cytochrome c, a heme protein that has a crucial role in respiration, and second mitochondria-derived activator of caspase (SMAC), as well as other intermembrane space proteins, orchestrate caspase activation. Moreover, we discuss recent insights on the interplay of the upstream coordinators and initiators of MOMP, the BCL-2 family. This review highlights how our increasing knowledge on the regulation of critical checkpoints of apoptosis integrates with understanding of cancer development and has begun to translate into therapeutic clinical benefit.

Combined targeting of BCL-2 and BCR-ABL tyrosine kinase eradicates chronic myeloid leukemia stem cells

BCR-ABL tyrosine kinase inhibitors (TKIs) are effective against chronic myeloid leukemia (CML), but they rarely eliminate CML stem cells. Disease relapse is common upon therapy cessation, even in patients with complete molecular responses. Furthermore, once CML progresses to blast crisis (BC), treatment outcomes are dismal. We hypothesized that concomitant targeting of BCL-2 and BCR-ABL tyrosine kinase could overcome these limitations. We demonstrate increased BCL-2 expression at the protein level in bone marrow cells, particularly in Lin(-)Sca-1(+)cKit(+) cells of inducible CML in mice, as determined by CyTOF mass cytometry. Further, selective inhibition of BCL-2, aided by TKI-mediated MCL-1 and BCL-XL inhibition, markedly decreased leukemic Lin(-)Sca-1(+)cKit(+) cell numbers and long-term stem cell frequency and prolonged survival in a murine CML model. Additionally, this combination effectively eradicated CD34(+)CD38(-), CD34(+)CD38(+), and quiescent stem/progenitor CD34(+) cells from BC CML patient samples. Our results suggest that BCL-2 is a key survival factor for CML stem/progenitor cells and that combined inhibition of BCL-2 and BCR-ABL tyrosine kinase has the potential to significantly improve depth of response and cure rates of chronic-phase and BC CML.

Mitochondrial dysfunction and damage associated molecular patterns (DAMPs) in chronic inflammatory diseases

Inflammation represents a comprehensive host response to external stimuli for the purpose of eliminating the offending agent, minimizing injury to host tissues and fostering repair of damaged tissues back to homeostatic levels. In normal physiologic context, inflammatory response culminates with the resolution of infection and tissue damage response. However, in a pathologic context, persistent or inappropriately regulated inflammation occurs that can lead to chronic inflammatory diseases. Recent scientific advances have integrated the role of innate immune response to be an important arm of the inflammatory process. Accordingly, the dysregulation of innate immunity has been increasingly recognized as a driving force of chronic inflammatory diseases. Mitochondria have recently emerged as organelles which govern fundamental cellular functions including cell proliferation or differentiation, cell death, metabolism and cellular signaling that are important in innate immunity and inflammation-mediated diseases. As a natural consequence, mitochondrial dysfunction has been highlighted in a myriad of chronic inflammatory diseases. Moreover, the similarities between mitochondrial and bacterial constituents highlight the intrinsic links in the innate immune mechanisms that control chronic inflammation in diseases where mitochondrial damage associated molecular patterns (DAMPs) have been involved. Here in this review, the role of mitochondria in innate immune responses is discussed and how it pertains to the mitochondrial dysfunction or DAMPs seen in chronic inflammatory diseases is reviewed.

C21 steroid-enriched fraction refined from Marsdenia tenacissima inhibits hepatocellular carcinoma through the coordination of Hippo-Yap and PTEN-PI3K/AKT signaling pathways

Marsdenia tenacissimae extraction (MTE), a traditional herbal medicine, has exhibited anti-tumor effects on a variety of cancers. However, its effectiveness and the mechanism of action in Hepatocellular carcinoma (HCC) has not been fully understood. In the present study, we demonstrate that C21 steroid-enriched fraction from MTE, which contains five main C21 steroids (FR5) exhibits obvious pharmacological activities on HCC cells in vitro and in vivo. FR5 induces apoptosis and inhibits proliferation and migration of HepG2 and Bel7402 cells in a dose and time dependent manner. Furthermore, in HCC cells, we found that FR5 inhibits Hippo pathway, leading to inactivation of YAP and increase of PTEN. Enhanced PTEN results in the inhibition of PI3K/AKT signaling pathway, inhibiting cell proliferation by FR5 and FR5-induced apoptosis. Moreover, it was proved that FR5 treatment could inhibit tumor growth in a HCC xenograft mouse model, and immunohistochemistry results showed FR5 treatment resulted in down-regulation of Bcl-2 and YAP, and up-regulation of PTEN and PI3K. Taken together, we found that FR5 effectively inhibits proliferation and induces apoptosis of HCC cells through coordinated inhibition of YAP in the Hippo pathway and AKT in the PI3K-PTEN-mTOR pathway, and suggest FR5 as a potential therapy for HCC.

Dynein light chain 1 induces assembly of large Bim complexes on mitochondria that stabilize Mcl-1 and regulate apoptosis

In this study, Singh et al. investigated Bim structure and activity and show that Bim is regulated by the formation of large protein complexes containing dynein light chain 1 (DLC1). Their findings demonstrate that control of apoptosis at mitochondria extends beyond the interaction of monomers of proapoptotic and anti-apoptotic Bcl-2 family members and involves more complex structures of proteins at the mitochondrial outer membrane.

The Bcl-2 family protein Bim triggers mitochondrial apoptosis. Bim is expressed in nonapoptotic cells at the mitochondrial outer membrane, where it is activated by largely unknown mechanisms. We found that Bim is regulated by formation of large protein complexes containing dynein light chain 1 (DLC1). Bim rapidly inserted into cardiolipin-containing membranes in vitro and recruited DLC1 to the membrane. Bim binding to DLC1 induced the formation of large Bim complexes on lipid vesicles, on isolated mitochondria, and in intact cells. Native gel electrophoresis and gel filtration showed Bim-containing mitochondrial complexes of several hundred kilodaltons in all cells tested. Bim unable to form complexes was consistently more active than complexed Bim, which correlated with its substantially reduced binding to anti-apoptotic Bcl-2 proteins. At endogenous levels, Bim surprisingly bound only anti-apoptotic Mcl-1 but not Bcl-2 or Bcl-X_L, recruiting only Mcl-1 into large complexes. Targeting of DLC1 by RNAi in human cell lines induced disassembly of Bim–Mcl-1 complexes and the proteasomal degradation of Mcl-1 and sensitized the cells to the Bcl-2/Bcl-X_L inhibitor ABT-737. Regulation of apoptosis at mitochondria thus extends beyond the interaction of monomers of proapoptotic and anti-apoptotic Bcl-2 family members but involves more complex structures of proteins at the mitochondrial outer membrane, and targeting complexes may be a novel therapeutic strategy.

DJ‑1 alleviates high glucose‑induced endothelial cells injury via PI3K/Akt‑eNOS signaling pathway

Hyperglycemia mediated endothelial cells (ECs) injury is closely associated with diabetic vascular complications. It was revealed that DJ‑1 possesses cellular protective effects by suppressing oxidative stress. The present study aimed to investigate the beneficial effects of DJ‑1 on high glucose (HG)‑induced human umbilical vein endothelial cell (HUVEC) injury and to elucidate its underlying mechanisms. HUVECs were incubated under 5.5 mM (control group) or 25 mM D‑glucose (HG group) and then transfected with recombinant adenoviral vectors to overexpression of DJ‑1. Cell proliferation and apoptosis were measured using the EdU incorporation assay and flow cytometry with Annexin V-FITC/propidium iodide double staining, respectively. Apoptotic‑related proteins were determined using western blot analysis. Reactive oxygen species (ROS) production, lactate dehydrogenase (LDH) and nitric oxide (NO) levels, the content of malondialdehyde (MDA), and the activities of superoxide dismutase (SOD) were measured. Results demonstrated that overexpression of DJ‑1 promoted cell proliferation and inhibited HUVECs apoptosis stimulated by HG. DJ‑1 also suppressed the HG‑induced reduction in the Bcl‑2/Bax ratio and HG activated ROS generation in HUVECs. Furthermore, HG significantly increased the levels of LDH and MDA, and reduced the level of SOD; however, these effects were reversed by Ad‑DJ‑1 transfection. Furthermore, the cellular protective effect of overexpression of DJ‑1 enhanced p‑Akt/Akt ratio, eNOS activation and NO production, and these trends were partially reversed by a phosphatidylinositol‑4,5‑bisphosphate 3‑kinase (PI3K) inhibitor (LY294002). Taken together, the present study highlighted the involvement of DJ‑1 in HG‑related EC injury and identified that DJ‑1 exerts a cellular protective effect in HUVECs exposed to HG induced oxidative stress via activation of the PI3K/Akt‑eNOS signaling pathway.

Organelle membrane derived patches: reshaping classical methods for new targets

Intracellular ion channels are involved in multiple signaling processes, including such crucial ones as regulation of cellular motility and fate. With 95% of the cellular membrane belonging to intracellular organelles, it is hard to overestimate the importance of intracellular ion channels. Multiple studies have been performed on these channels over the years, however, a unified approach allowing not only to characterize their activity but also to study their regulation by partner proteins, analogous to the patch clamp “golden standard”, is lacking. Here, we present a universal approach that combines the extraction of intracellular membrane fractions with the preparation of patchable substrates that allows to characterize these channels in endogenous protein environment and to study their regulation by partner proteins. We validate this method by characterizing activity of multiple intracellular ion channels localized to different organelles and by providing detailed electrophysiological characterization of the regulation of IP₃R activity by endogenous Bcl-2. Thus, after synthesis and reshaping of the well-established approaches, organelle membrane derived patch clamp provides the means to assess ion channels from arbitrary cellular membranes at the single channel level.

Stendomycin selectively inhibits TIM23-dependent mitochondrial protein import

Tim17 and Tim23 are the main subunits of the TIM23 complex, one of the two major essential mitochondrial inner-membrane protein translocon machineries (TIMs). No chemical probes that specifically inhibit TIM23-dependent protein import were known to exist. Here we show that the natural product stendomycin, produced by Streptomyces hygroscopicus, is a potent and specific inhibitor of the TIM23 complex in yeast and mammalian cells. Furthermore, stendomycin-mediated blockage of the TIM23 complex does not alter normal processing of the major regulatory mitophagy kinase PINK1, but TIM23 is required to stabilize PINK1 on the outside of mitochondria to initiate mitophagy upon membrane depolarization.

Functional precision cancer medicine-moving beyond pure genomics

The essential job of precision medicine is to match the right drugs to the right patients. In cancer, precision medicine has been nearly synonymous with genomics. However, sobering recent studies have generally shown that most patients with cancer who receive genomic testing do not benefit from a genomic precision medicine strategy. Although some call the entire project of precision cancer medicine into question, I suggest instead that the tools employed must be broadened. Instead of relying exclusively on big data measurements of initial conditions, we should also acquire highly actionable functional information by perturbing-for example, with cancer therapies-viable primary tumor cells from patients with cancer.

The path from mitochondrial ROS to aging runs through the mitochondrial permeability transition pore

Excessive production of mitochondrial reactive oxygen species (mROS) is strongly associated with mitochondrial and cellular oxidative damage, aging, and degenerative diseases. However, mROS also induces pathways of protection of mitochondria that slow aging, inhibit cell death, and increase lifespan. Recent studies show that the activation of the mitochondrial permeability transition pore (mPTP), which is triggered by mROS and mitochondrial calcium overloading, is enhanced in aged animals and humans and in aging-related degenerative diseases. mPTP opening initiates further production and release of mROS that damage both mitochondrial and nuclear DNA, proteins, and phospholipids, and also releases matrix NAD that is hydrolyzed in the intermembrane space, thus contributing to the depletion of cellular NAD that accelerates aging. Oxidative damage to calcium transporters leads to calcium overload and more frequent opening of mPTP. Because aging enhances the opening of the mPTP and mPTP opening accelerates aging, we suggest that mPTP opening drives the progression of aging. Activation of the mPTP is regulated, directly and indirectly, not only by the mitochondrial protection pathways that are induced by mROS, but also by pro-apoptotic signals that are induced by DNA damage. We suggest that the integration of these contrasting signals by the mPTP largely determines the rate of cell aging and the initiation of cell death, and thus animal lifespan. The suggestion that the control of mPTP activation is critical for the progression of aging can explain the conflicting and confusing evidence regarding the beneficial and deleterious effects of mROS on health and lifespan.

Extra-mitochondrial prosurvival BCL-2 proteins regulate gene transcription by inhibiting the SUFU tumour suppressor

Direct interactions between pro- and anti-apoptotic BCL-2 family members form the basis of cell death decision-making at the outer mitochondrial membrane (OMM). Here we report that three antiapoptotic BCL-2 proteins (MCL-1, BCL-2, and BCL-XL) found untethered from the OMM function as transcriptional regulators of a prosurvival and growth program. Antiapoptotic BCL-2 proteins engage a BCL-2 homology (BH) domain sequence found in Suppressor of Fused (SUFU), a tumor suppressor and antagonist of the GLI DNA binding proteins. BCL-2 proteins directly promote SUFU turnover, inhibit SUFU-GLI interaction, and induce the expression of the GLI target genes BCL-2, MCL-1, and BCL-XL. Antiapoptotic BCL-2 protein/SUFU feedforward signaling promotes cancer cell survival and growth and can be disabled with BH3 mimetics – small molecules that target antiapoptotic BCL-2 proteins. Our findings delineate a chemical strategy for countering drug resistance in GLI-associated tumors and reveal unanticipated functions for BCL-2 proteins as transcriptional regulators.

Emerging therapies for acute myeloid leukemia: translating biology into the clinic

Acute myeloid leukemia (AML) is an aggressive hematological malignancy with a poor outcome; overall survival is approximately 35% at two years and some subgroups have a less than 5% two-year survival. Recently, significant improvements have been made in our understanding of AML biology and genetics. These fundamental discoveries are now being translated into new therapies for this disease. This review will discuss recent advances in AML biology and the emerging treatments that are arising from biological studies. Specifically, we will consider new therapies that target molecular mutations in AML and dysregulated pathways such as apoptosis and mitochondrial metabolism. We will also discuss recent advances in immune and cellular therapy for AML.

The optimal regulation mode of Bcl-2 apoptotic switch revealed by bistability analysis

In most cell types, apoptosis occurs by the mitochondrial outer membrane permeability (MOMP)-mediated pathway, which is controlled by Bcl-2 family proteins (often referred to as Bcl-2 apoptotic switch). These proteins, which display a range of bioactivities, can be divided into four types: effectors, inhibitors, activators and sensitizers. Although the complex interactions among Bcl-2 family members have been studied intensively, a unifying hypothesis for the mechanism they use to regulate MOMP remains elusive. The bistable behaviors are often used to explain the all-or-none decisions of apoptosis. Here, we attempt to reveal the optimal interaction mode by comparing the bistable performances of three different modes (direct activation, indirect activation, and unified mode) proposed by biologists. Using the method that combines mathematical analysis and numerical simulation, we discover that bistability can only emerge from the unified mode when proteins synthesis and degradation are considered, which is in favor of it as an optimal regulation mode of Bcl-2 apoptotic switch. The parameter sensitivity analysis for the unified mode further consolidates this view. Moreover, two-parameter bifurcation analysis suggests that the sensitizers lower the threshold of activation of Bax, but have a negative influence on the width of the bistability region. Our study may provide mechanistic insights into the heterogeneity of tumor cells and the efficiency of BH3 mimetic-mediated killing of cancer cells, and suggest that a combination treatment might be required to overcome apoptosis resistance in the Bcl-2 family targeted therapies.

SOX5/6/21 Prevent Oncogene-Driven Transformation of Brain Stem Cells

Molecular mechanisms preventing self-renewing brain stem cells from oncogenic transformation are poorly defined. We show that the expression levels of SOX5, SOX6, and SOX21 (SOX5/6/21) transcription factors increase in stem cells of the subventricular zone (SVZ) upon oncogenic stress, whereas their expression in human glioma decreases during malignant progression. Elevated levels of SOX5/6/21 promoted SVZ cells to exit the cell cycle, whereas genetic ablation of SOX5/6/21 dramatically increased the capacity of these cells to form glioma-like tumors in an oncogene-driven mouse brain tumor model. Loss-of-function experiments revealed that SOX5/6/21 prevent detrimental hyperproliferation of oncogene expressing SVZ cells by facilitating an antiproliferative expression profile. Consistently, restoring high levels of SOX5/6/21 in human primary glioblastoma cells enabled expression of CDK inhibitors and decreased p53 protein turnover, which blocked their tumorigenic capacity through cellular senescence and apoptosis. Altogether, these results provide evidence that SOX5/6/21 play a central role in driving a tumor suppressor response in brain stem cells upon oncogenic insult. Cancer Res; 77(18); 4985-97. ©2017 AACR.

Molecular mechanisms for tumour resistance to chemotherapy

Chemotherapy is one of the prevailing methods used to treat malignant tumours, but the outcome and prognosis of tumour patients are not optimistic. Cancer cells gradually generate resistance to almost all chemotherapeutic drugs via a variety of distinct mechanisms and pathways. Chemotherapeutic resistance, either intrinsic or acquired, is caused and sustained by reduced drug accumulation and increased drug export, alterations in drug targets and signalling transduction molecules, increased repair of drug-induced DNA damage, and evasion of apoptosis. In order to better understand the mechanisms of chemoresistance, this review highlights our current knowledge of the role of altered drug metabolism and transport and deregulation of apoptosis and autophagy in the development of tumour chemoresistance. Reduced intracellular activation of prodrugs (e.g. thiotepa and tegafur) or enhanced drug inactivation by Phase I and II enzymes contributes to the development of chemoresistance. Both primary and acquired resistance can be caused by alterations in the transport of anticancer drugs which is mediated by a variety of drug transporters such as P-glycoprotein (P-gp), multidrug resistance associated proteins, and breast cancer resistance protein. Presently there is a line of evidence indicating that deregulation of programmed cell death including apoptosis and autophagy is also an important mechanism for tumour resistance to anticancer drugs. Reversal of chemoresistance is likely via pharmacological and biological approaches. Further studies are warranted to grasp the full picture of how each type of cancer cells develop resistance to anticancer drugs and to identify novel strategies to overcome it.

Biphasic ROS production, p53 and BIK dictate the mode of cell death in response to DNA damage in colon cancer cells

Necrosis, apoptosis and autophagic cell death are the main cell death pathways in multicellular organisms, all with distinct and overlapping cellular and biochemical features. DNA damage may trigger different types of cell death in cancer cells but the molecular events governing the mode of cell death remain elusive. Here we showed that increased BH3-only protein BIK levels promoted cisplatin- and UV-induced mitochondrial apoptosis and biphasic ROS production in HCT-116 wild-type cells. Nonetheless, early single peak of ROS formation along with lysosomal membrane permeabilization and cathepsin activation regulated cisplatin- and UV-induced necrosis in p53-null HCT-116 cells. Of note, necrotic cell death in p53-null HCT-116 cells did not depend on BIK, mitochondrial outer membrane permeabilization or caspase activation. These data demonstrate how cancer cells with different p53 background respond to DNA-damaging agents by integrating distinct cell signaling pathways dictating the mode of cell death.

Mis-targeting of the mitochondrial protein LIPT2 leads to apoptotic cell death

Lipoyl(Octanoyl) Transferase 2 (LIPT2) is a protein involved in the post-translational modification of key energy metabolism enzymes in humans. Defects of lipoic acid synthesis and transfer start to emerge as causes of fatal or severe early-onset disease. We show that the first 31 amino acids of the N-terminus of LIPT2 represent a mitochondrial targeting sequence and inhibition of the transit of LIPT2 to the mitochondrion results in apoptotic cell death associated with activation of the apoptotic volume decrease (AVD) current in normotonic conditions, as well as over-activation of the swelling-activated chloride current (IClswell), mitochondrial membrane potential collapse, caspase-3 cleavage and nuclear DNA fragmentation. The findings presented here may help elucidate the molecular mechanisms underlying derangements of lipoic acid biosynthesis.

Role of apoptosis in the development of autosomal dominant polycystic kidney disease (ADPKD)

Autosomal dominant polycystic kidney disease (ADPKD) is a widespread genetic disorder in the Western world and is characterized by cystogenesis that often leads to end-stage renal disease (ESRD). Mutations in the pkd1 gene, encoding for polycystin-1 (PC1) and its interaction partner pkd2, encoding for polycystin-2 (PC2), are the main drivers of this disease. PC1 and PC2 form a multiprotein membrane complex at cilia sites of the plasma membrane and at intracellular membranes. This complex mediates calcium influx and stimulates various signaling pathways regulating cell survival, proliferation and differentiation. The molecular consequences of pkd1 and pkd2 mutations are still a matter of debate. In particular, the ways in which the cysts are initially formed and progress throughout the disease are unknown. The mechanisms proposed to play a role include enhanced cell proliferation, increased apoptotic cell death and diminished autophagy. In this review, we summarize our current understanding about the contribution of apoptosis to cystogenesis and ADPKD. We present the animal models and the tools and methods that have been created to analyze this process. We also critically review the data that are in favor or against the involvement of apoptosis in disease generation. We argue that apoptosis is probably not the sole driver of cystogenesis but that a cooperative action of cell death, compensatory cell proliferation and perturbed autophagy gradually establish the disease. Finally, we propose novel strategies for uncovering the mode of action of PC1 and PC2 and suggest means by which their dysfunction or loss of expression lead to cystogenesis and ADPKD development.

Connecting mitochondrial dynamics and life-or-death events via Bcl-2 family proteins

The morphology of a population of mitochondria is the result of several interacting dynamical phenomena, including fission, fusion, movement, elimination and biogenesis. Each of these phenomena is controlled by underlying molecular machinery, and when defective can cause disease. New understanding of the relationships between form and function of mitochondria in health and disease is beginning to be unraveled on several fronts. Studies in mammals and model organisms have revealed that mitochondrial morphology, dynamics and function appear to be subject to regulation by the same proteins that regulate apoptotic cell death. One protein family that influences mitochondrial dynamics in both healthy and dying cells is the Bcl-2 protein family. Connecting mitochondrial dynamics with life-death pathway forks may arise from the intersection of Bcl-2 family proteins with the proteins and lipids that determine mitochondrial shape and function. Bcl-2 family proteins also have multifaceted influences on cells and mitochondria, including calcium handling, autophagy and energetics, as well as the subcellular localization of mitochondrial organelles to neuronal synapses. The remarkable range of physical or functional interactions by Bcl-2 family proteins is challenging to assimilate into a cohesive understanding. Most of their effects may be distinct from their direct roles in apoptotic cell death and are particularly apparent in the nervous system. Dual roles in mitochondrial dynamics and cell death extend beyond BCL-2 family proteins. In this review, we discuss many processes that govern mitochondrial structure and function in health and disease, and how Bcl-2 family proteins integrate into some of these processes.

Design, synthesis and biological evaluation of 3-substituted-2-oxindole hybrid derivatives as novel anticancer agents

The 2-oxindole nucleus is the central core to develop new anticancer agents and its substitution at the 3-position can effect antitumor activity. Utilizing a pharmacophore hybridization approach, a novel series of antiproliferative agents was obtained by the modification of the structure of 3-substituted-2-oxindole pharmacophore by the attachment of the α-bromoacryloyl moiety, acting as a Michael acceptor, at the 5-position of 2-oxindole framework. The impact of the substituent at the 3-position of 2-oxindole core on the potency and selectivity against a panel of seven different cancer cell lines was examined. We found that these hybrid molecules displayed potent antiproliferative activity against a panel of four cancer cell lines, with one-to double digit nanomolar 50% inhibitory concentrations (IC₅₀). A distinctive selective antiproliferative activity was obtained towards CCRF-CEM and RS4; 11 leukemic cell lines. In order to study the possible mechanism of action, we observed that the two most active compounds namely 3(E) and 6(Z) strongly induce apoptosis that follow the mitochondrial pathway. Interestingly a decrease of intracellular reduced glutathione content (GSH) and reactive oxygen species (ROS) production was detected in treated cells compared with controls suggesting that these effects may be involved in their mechanism of action.

Vitexin alleviates ox-LDL-mediated endothelial injury by inducing autophagy via AMPK signaling activation

Endothelial cell injury plays a crucial role in the development and pathogenesis of cardiovascular disease. Vitexin is a natural flavonoid characterized by anti-oxidative and anti-inflammatory properties. The purpose of this study was to investigate the effects of vitexin on ox-LDL-induced endothelial dysfunction and to explore the underlying molecular mechanisms. In the present study, vitexin was found to play a protective role against ox-LDL-induced endothelial injury. Vitexin significantly promoted cell viability and inhibited apoptosis in ox-LDL-treated HUVECs. The up-regulation of cleaved Caspase-3, cleaved Caspase-9 and Bax induced by ox-LDL were inhibited by treatment with vitexin; meanwhile, the down-regulation of Bcl-2 was suppressed by vitexin. Pretreatment with vitexin was found to inhibit the ox-LDL-induced overexpression of IL-1β, IL-6, TNF-α, E-selectin, ICAM1 and VCAM1. Moreover, vitexin reduced ox-LDL-induced oxidative stress by inhibiting the production of ROS and MDA, and by promoting the expression of SOD. Furthermore, we had shown that vitexin protected against the ox-LDL induced cell injury by activating autophagy. The protective effects of vitexin in ox-LDL-treated HUVECs were all reversed following treatment with the autophagy inhibitor 3-MA. In addition, we found that vitexin increased the expression of p-AMPK and decreased the expression of p-mTOR. The combination of the AMPK inhibitor Compound C plus vitexin significantly reversed the effects of vitexin in ox-LDL-treated HUVECs, such as the inhibition of autophagy, reduction in cell viability, increase in apoptosis and ROS production. In conclusion, these data suggest that vitexin ameliorates ox-LDL-mediated endothelial injury by inducing autophagy via AMPK signaling.

Mcl-1 Degradation Is Required for Targeted Therapeutics to Eradicate Colon Cancer Cells

The Bcl-2 family protein Mcl-1 is often degraded in cancer cells subjected to effective therapeutic treatment, and defective Mcl-1 degradation has been associated with intrinsic and acquired drug resistance. However, a causal relationship between Mcl-1 degradation and anticancer drug responses has not been directly established, especially in solid tumor cells where Mcl-1 inhibition alone is insufficient to trigger cell death. In this study, we present evidence that Mcl-1 participates directly in determining effective therapeutic responses in colon cancer cells. In this setting, Mcl-1 degradation was induced by a variety of multikinase inhibitor drugs, where it relied upon GSK3β phosphorylation and FBW7-dependent ubiquitination. Specific blockade by genetic knock-in (KI) abolished apoptotic responses and conferred resistance to kinase inhibitors. Mcl-1-KI also suppressed the antiangiogenic and anti-hypoxic effects of kinase inhibitors in the tumor microenvironment. Interestingly, these same inhibitors also induced the BH3-only Bcl-2 family protein PUMA, which is required for apoptosis. Degradation-resistant Mcl-1 bound and sequestered PUMA from other prosurvival proteins to maintain cell survival, which was abolished by small-molecule Mcl-1 inhibitors. Our findings establish a pivotal role for Mcl-1 degradation in the response of colon cancer cells to targeted therapeutics, and they provide a useful rational platform to develop Mcl-1-targeting agents that can overcome drug resistance. Cancer Res; 77(9); 2512-21. ©2017 AACR.

A BH3 Mimetic for Killing Cancer Cells

Venetoclax is a BH3 mimetic approved for treating chronic lymphocytic leukemia. Cancer cells are resistant to apoptosis but "primed for death" by elevated BCL-2, which binds to pro-apoptotic proteins and holds them in check. Venetoclax releases this antagonism and is the first approved drug to target a protein-protein interaction.

Myofibrillar Myopathies: New Perspectives from Animal Models to Potential Therapeutic Approaches

Myofibrillar myopathies (MFMs) are muscular disorders involving proteins that play a role in the structure, maintenance processes and protein quality control mechanisms closely related to the Z-disc in the muscular fibers. MFMs share common histological characteristics including progressive disorganization of the interfibrillar network and protein aggregation. Currently no treatment is available. In this review, we describe first clinical symptoms associated with mutations of the six genes (DES, CRYAB, MYOT, ZASP, FLNC and BAG3) primary involved in MFM and defining the origin of this pathology. As mechanisms determining the aetiology of the disease remain unclear yet, several research teams have developed animal models from invertebrates to mammalians species. Thus we describe here these different models that often recapitulate human clinical symptoms. Therefore they are very useful for deeper studies to understand early molecular and progressive mechanisms determining the pathology. Finally in the last part, we emphasize on the potential therapeutic approaches for MFM that could be conducted in the future. In conclusion, this review offers a link from patients to future therapy through the use of MFMs animal models.

How to unleash mitochondrial apoptotic blockades to kill cancers?

Apoptosis, especially the intrinsic mitochondrial cell death pathway, is regulated by the BCL-2 family of proteins. Defects in apoptotic machinery are one of the main mechanisms that cells employ to evade cell death and become cancerous. Targeting the apoptotic defects, either by direct inhibition of BCL-2 family proteins or through modulation of regulatory pathways, can restore cell sensitivity to cell death. This review will focus on the aspects of BCL-2 family proteins, their interactions with kinase pathways, and how novel targeted agents can help overcome the apoptotic blockades. Furthermore, functional assays, such as BH3 profiling, may help in predicting responses to chemotherapies and aid in the selection of combination therapies by determining the mitochondrial threshold for initiating cell death.

S63845, an MCL-1 Selective BH3 Mimetic: Another Arrow in Our Quiver

A recent study reports a novel small molecule inhibitor of MCL-1 with efficacy in killing MCL-1-dependent cancer cells in vitro and in vivo. With the advent of S63845, the targeting of BCL-2, BCL-XL, and MCL-1 is now possible in vivo, but optimal clinical use is yet to be determined.

Cell-specific increased expression of calpastatin prevents diabetes induced by islet amyloid polypeptide toxicity

The islet in type 2 diabetes (T2D) shares many features of the brain in protein misfolding diseases. There is a deficit of β cells with islet amyloid derived from islet amyloid polypeptide (IAPP), a protein coexpressed with insulin. Small intracellular membrane-permeant oligomers, the most toxic form of IAPP, are more frequent in β cells of patients with T2D and rodents expressing human IAPP. β Cells in T2D, and affected cells in neurodegenerative diseases, share a comparable pattern of molecular pathology, including endoplasmic reticulum stress, mitochondrial dysfunction, attenuation of autophagy, and calpain hyperactivation. While this adverse functional cascade in response to toxic oligomers is well described, the sequence of events and how best to intervene is unknown. We hypothesized that calpain hyperactivation is a proximal event and tested this in vivo by β cell-specific suppression of calpain hyperactivation with calpastatin overexpression in human IAPP transgenic mice. β Cell-specific calpastatin overexpression was remarkably protective against β cell dysfunction and loss and diabetes onset. The critical autophagy/lysosomal pathway for β cell viability was protected with calpain suppression, consistent with findings in models of neurodegenerative diseases. We conclude that suppression of calpain hyperactivation is a potentially beneficial disease-modifying strategy for protein misfolding diseases, including T2D.

V8 induces apoptosis and the endoplasmic reticulum stress response in human multiple myeloma RPMI 8226 cells via the PERK-eIF2α-ATF4 signaling pathway

Multiple myeloma (MM) is a fatal hematological cancer characterized by clonal plasma cell proliferation in the bone marrow. MM has an increasing global incidence and a poor prognosis. There are limited treatment options available for MM, and this is further compounded by the development of drug resistance. The present study demonstrated that 7-{4-[Bis-(2-hydroxyethyl)-amino]-butoxy}-5-hydroxy-8-methoxy-2-phenylchromen-4-one (V8), a novel synthetic flavonoid, induced apoptosis in human MM RPMI 8226 cells in a dose- and time-dependent manner, using cell viability assays and flow cytometry. Subsequently, V8-induced apoptosis in RPMI 8226 cells was revealed to occur via mitochondria-mediated pathways. The activity of caspase-3, -8 and -9, and the mRNA level of B-cell lymphoma 2 (Bcl-2) and B-cell lymphoma-extra large were greatly increased, while the expression of Bcl-2-like protein 4 and BH3 interacting domain death agonist was significantly decreased in RPMI 8226 cells following V8 treatment, as observed using quantitative polymerase chain reaction (qPCR). In addition, western blotting revealed that the release of mitochondrial cytochrome c into the cytosol was promoted by V8. Furthermore, a clear alteration in endoplasmic reticulum (ER) stress was observed in cells treated with V8; upregulation of glucose-regulated protein (GRP) 78, GRP94, C/EBP homologous protein, cleavage of caspase-12, phosphorylated protein kinase RNA-like endoplasmic reticulum kinase (p-PERK), phosphorylated eukaryotic initiation factor 2α (p-eIF2α) and activating transcription factor 4 (ATF4) was observed with qPCR and western blotting, suggesting that V8-induced apoptosis is involved in the ER stress response. Overall, the present results demonstrated that V8 induced apoptosis in human MM RPMI 8226 cells via the PERK-eIF2α-ATF4 ER stress response pathway, which may provide novel directions for exploiting this compound as a potential anti-neoplastic drug for MM therapy.

A Mitochondrial Perspective of Chronic Obstructive Pulmonary Disease Pathogenesis

Chronic obstructive pulmonary disease (COPD) encompasses several clinical syndromes, most notably emphysema and chronic bronchitis. Most of the current treatments fail to attenuate severity and progression of the disease, thereby requiring better mechanistic understandings of pathogenesis to develop disease-modifying therapeutics. A number of theories on COPD pathogenesis have been promulgated wherein an increase in protease burden from chronic inflammation, exaggerated production of reactive oxygen species and the resulting oxidant injury, or superfluous cell death responses caused by enhanced cellular injury/damage were proposed as the culprit. These hypotheses are not mutually exclusive and together likely represent the multifaceted biological processes involved in COPD pathogenesis. Recent studies demonstrate that mitochondria are involved in innate immune signaling that plays important roles in cigarette smoke-induced inflammasome activation, pulmonary inflammation and tissue remodeling responses. These responses are reviewed herein and synthesized into a view of COPD pathogenesis whereby mitochondria play a central role.

Molecular mechanisms of chemoresistance in gastric cancer

Gastric cancer is the fourth most common cancer and the second leading cause of cancer deaths worldwide. Chemotherapy is one of the major treatments for gastric cancer, but drug resistance limits the effectiveness of chemotherapy, which results in treatment failure. Resistance to chemotherapy can be present intrinsically before the administration of chemotherapy or it can develop during chemotherapy. The mechanisms of chemotherapy resistance in gastric cancer are complex and multifactorial. A variety of factors have been demonstrated to be involved in chemoresistance, including the reduced intracellular concentrations of drugs, alterations in drug targets, the dysregulation of cell survival and death signaling pathways, and interactions between cancer cells and the tumor microenvironment. This review focuses on the molecular mechanisms of chemoresistance in gastric cancer and on recent studies that have sought to overcome the underlying mechanisms of chemoresistance.

The PB2 Subunit of the Influenza A Virus RNA Polymerase Is Imported into the Mitochondrial Matrix

The polymerase basic 2 (PB2) subunit of the RNA polymerase complex of seasonal human influenza A viruses has been shown to localize to the mitochondria. Various roles, including the regulation of apoptosis and innate immune responses to viral infection, have been proposed for mitochondrial PB2. In particular, PB2 has been shown to inhibit interferon expression by associating with the mitochondrial antiviral signaling (MAVS) protein, which acts downstream of RIG-I and MDA-5 in the interferon induction pathway. However, in spite of a growing body of literature on the potential roles of mitochondrial PB2, the exact location of PB2 in mitochondria has not been determined. Here, we used enhanced ascorbate peroxidase (APEX)-tagged PB2 proteins and electron microscopy to study the localization of PB2 in mitochondria. We found that PB2 is imported into mitochondria, where it localizes to the mitochondrial matrix. We also demonstrated that MAVS is not required for the import of PB2 into mitochondria by showing that PB2 associates with mitochondria in MAVS knockout mouse embryo fibroblasts. Instead, we found that amino acid residue 9 in the N-terminal mitochondrial targeting sequence is a determinant of the mitochondrial import of PB2, differentiating the localization of PB2 of human from that of avian influenza A virus strains. We also showed that a virus encoding nonmitochondrial PB2 is attenuated in mouse embryonic fibroblasts (MEFs) compared with an isogenic virus encoding mitochondrial PB2, in a MAVS-independent manner, suggesting a role for PB2 within the mitochondrial matrix. This work extends our understanding of the interplay between influenza virus and mitochondria.

IMPORTANCE The PB2 subunit of the influenza virus RNA polymerase is a major determinant of viral pathogenicity. However, the molecular mechanisms of how PB2 determines pathogenicity remain poorly understood. PB2 associates with mitochondria and inhibits the function of the mitochondrial antiviral signaling protein MAVS, implicating PB2 in the regulation of innate immune responses. We found that PB2 is imported into the mitochondrial matrix and showed that amino acid residue 9 is a determinant of mitochondrial import. The presence of asparagine or threonine in over 99% of all human seasonal influenza virus pre-2009 H1N1, H2N2, and H3N2 strains is compatible with mitochondrial import, whereas the presence of an aspartic acid in over 95% of all avian influenza viruses is not, resulting in a clear distinction between human-adapted and avian influenza viruses. These findings provide insights into the interplay between influenza virus and mitochondria and suggest mechanisms by which PB2 could affect pathogenicity.

A novel water-soluble benzothiazole derivative BD926 triggers ROS-mediated B lymphoma cell apoptosis via mitochondrial and endoplasmic reticulum signaling pathways

Benzothiazole derivatives are known for various biological activities, and their potency in cancer therapy have received considerable attention in recent years. However, the poor water solubility of most benzothiazole derivatives has limited their clinical application. We developed BD926, a novel water-soluble benzothiazole derivative and showed here that it could inhibit the proliferation and induce apoptosis of human Ramos B-lymphoma cells. We further showed that BD926 triggered apoptosis through both mitochondria and endoplasmic reticulum pathways. Moreover, BD926 caused cell cycle arrest at G0/G1 stage. Furthermore, accumulation of reactive oxygen species (ROS) were observed after BD926 treatment and ROS inhibitor was able to attenuate BD926-induced apoptosis, which suggested that BD926-induced apoptosis may be due to over-producing ROS. These results demonstrate the anticancer effects of BD926 in cell models and raise the possibility for the application of BD926 in cancer therapy.

Capsaicin: From Plants to a Cancer-Suppressing Agent

Capsaicinoids are plant secondary metabolites, capsaicin being the principal responsible for the pungency of chili peppers. It is biosynthesized through two pathways involved in phenylpropanoid and fatty acid metabolism. Plant capsaicin concentration is mainly affected by genetic, environmental and crop management factors. However, its synthesis can be enhanced by the use of elicitors. Capsaicin is employed as food additive and in pharmaceutical applications. Additionally, it has been found that capsaicin can act as a cancer preventive agent and shows wide applications against various types of cancer. This review is an approach in contextualizing the use of controlled stress on the plant to increase the content of capsaicin, highlighting its synthesis and its potential use as anticancer agent.