Capsaicin induces apoptosis in human osteosarcoma cells through AMPK-dependent and AMPK-independent signaling pathways

Capsaicin: A chili pepper bioactive phytocompound with a potential role in suppressing cancer development and progression

Cancer profoundly influences morbidity and fatality rates worldwide. Patients often have dismal prognoses despite recent improvements in cancer therapy regimens. However, potent biomolecules derived from natural sources, including medicinal and dietary plants, contain biological and pharmacological properties to prevent and treat various human malignancies. Capsaicin is a bioactive phytocompound present in red hot chili peppers. Capsaicin has demonstrated many biological effects, including antioxidant, anti-inflammatory, antimicrobial, and anticarcinogenic capabilities. This review highlights the cellular and molecular pathways through which capsaicin exhibits antineoplastic activities. Our work also depicts the synergistic anticancer properties of capsaicin in conjunction with other natural bioactive components and approved anticancer drugs. Capsaicin inhibits proliferation in various cancerous cells, and its antineoplastic actions in numerous in vitro and in vivo carcinoma models impact oncogenesis, tumor-promoting and suppressor genes, and associated signaling pathways. Capsaicin alone or combined with other phytocompounds or approved antineoplastic drugs triggers cell cycle progression arrest, generating reactive oxygen species and disrupting mitochondrial membrane integrity, ultimately stimulating caspases and promoting death. Furthermore, capsaicin alone or in combination can promote apoptosis in carcinoma cells by enhancing the p53 and c-Myc gene expressions. In conclusion, capsaicin alone or in combination can have enormous potential for cancer prevention and intervention, but further high-quality studies are needed to firmly establish the clinical efficacy of this phytocompound.

Versatile function of AMPK signaling in osteosarcoma: An old player with new emerging carcinogenic functions

AMP-activated protein kinase (AMPK) signaling has a versatile role in Osteosarcoma (OS), an aggressive bone malignancy with a poor prognosis, particularly in cases that have metastasized or recurred. This review explores the regulatory mechanisms, functional roles, and therapeutic applications of AMPK signaling in OS. It focuses on the molecular activation of AMPK and its interactions with cellular processes like proliferation, apoptosis, and metabolism. The uncertain role of AMPK in cancer is also discussed, highlighting its potential as both a tumor suppressor and a contributor to carcinogenesis. The therapeutic potential of targeting AMPK signaling in OS treatment is examined, including direct and indirect activators like metformin, A-769662, resveratrol, and salicylate. Further research is needed to determine dosing, toxicities, and molecular mechanisms responsible for the anti-osteosarcoma effects of these compounds. This review underscores the complex involvement of AMPK signaling in OS and emphasizes the need for a comprehensive understanding of its molecular mechanisms. By elucidating the role of AMPK in OS, the aim is to pave the way for innovative therapeutic approaches that target this pathway, ultimately improving the prognosis and quality of life for OS patients.

Metabolic Reprogramming and Potential Therapeutic Targets in Lymphoma

Lymphoma is a heterogeneous group of diseases that often require their metabolism program to fulfill the demand of cell proliferation. Features of metabolism in lymphoma cells include high glucose uptake, deregulated expression of enzymes related to glycolysis, dual capacity for glycolytic and oxidative metabolism, elevated glutamine metabolism, and fatty acid synthesis. These aberrant metabolic changes lead to tumorigenesis, disease progression, and resistance to lymphoma chemotherapy. This metabolic reprogramming, including glucose, nucleic acid, fatty acid, and amino acid metabolism, is a dynamic process caused not only by genetic and epigenetic changes, but also by changes in the microenvironment affected by viral infections. Notably, some critical metabolic enzymes and metabolites may play vital roles in lymphomagenesis and progression. Recent studies have uncovered that metabolic pathways might have clinical impacts on the diagnosis, characterization, and treatment of lymphoma subtypes. However, determining the clinical relevance of biomarkers and therapeutic targets related to lymphoma metabolism is still challenging. In this review, we systematically summarize current studies on metabolism reprogramming in lymphoma, and we mainly focus on disorders of glucose, amino acids, and lipid metabolisms, as well as dysregulation of molecules in metabolic pathways, oncometabolites, and potential metabolic biomarkers. We then discuss strategies directly or indirectly for those potential therapeutic targets. Finally, we prospect the future directions of lymphoma treatment on metabolic reprogramming.

Capsaicin decreases fecundity in the Asian malaria vector Anopheles stephensi by inhibiting the target of rapamycin signaling pathway

BACKGROUND

Mosquito-borne diseases threaten human health, but mosquito control faces various challenges, such as resistance to chemical insecticides. Thus, there is an urgent need for more effective and environment-friendly control agents. Capsaicin can downregulate the mTOR signaling pathway of tumor cells. The TOR signaling pathway can mediate the expression of vitellogenin (Vg) to regulate the fecundity of insects. Whether capsaicin has the potential to inhibit fecundity of mosquitoes by regulating TOR pathway and Vg expression is currently unclear.

METHODS

Anopheles stephensi were fed with blood of mice administered capsaicin by gavage or sugar containing capsaicin followed by a blood feeding with normal mice. Then, the engorged female mosquitoes were tubed individually and underwent oviposition. The eggs and individuals in the subsequent development stages, including larvae, pupae, and emerging adults, were counted and compared between the capsaicin treatment and control groups. Additionally, total RNA and protein were extracted from the engorged mosquitoes at 24 h post blood feeding. Real-time PCR and western blot were performed to detect the transcriptional level and protein expression of the key fecundity-related molecules of mosquitoes. Finally, TOR signaling pathway was inhibited via rapamycin treatment, and changes in fecundity and the key molecule transcription and protein expression levels were examined to verify the role of TOR signaling pathway in the effect of capsaicin on mosquito fecundity.

RESULTS

The laid and total eggs (laid eggs plus retained eggs) of An. stephensi were significantly reduced by feeding on the blood of capsaicin-treated mice (P < 0.01) or capsaicin-containing sugar (P < 0.01) compared with those in the control group. Moreover, the transcription and protein expression or phosphorylation levels of fecundity-related molecules, such as Akt, TOR, S6K, and Vg, were significantly decreased by capsaicin treatment. However, the effects disappeared between control group and CAP group after the TOR signaling pathway was inhibited by rapamycin.

CONCLUSIONS

Capsaicin can decrease the fecundity of An. stephensi by inhibiting the TOR signaling pathway. These data can help us to not only understand the effect of capsaicin on the reproductive ability of An. stephensi and its underlying mechanism, but also develop new efficient, safe, and pollution-free mosquito vector control agents.

PF-06409577 Activates AMPK Signaling and Inhibits Osteosarcoma Cell Growth

Osteosarcoma (OS) is a common primary bone malignancy. We here investigated the potential activity of PF-06409577, a novel, potent, and direct activator of AMP-activated protein kinase (AMPK), against human OS cells. In established (U2OS, MG-63, and SaOs-2 lines) and primary human OS cells, PF-06409577 inhibited cell viability and proliferation, while inducing cell apoptosis and cell cycle arrest. PF-06409577 induced AMPK activation, mTORC1 inhibition, autophagy induction, and downregulation of multiple receptor tyrosine kinase inOS cells. AMPK inactivation by AMPKα1 shRNA, CRISPR/Cas9 knockout, or dominant negative mutation (T172A) was able to abolish PF-06409577-induced activity in OS cells. In vivo, PF-06409577 oral administration at well-tolerated doses potently inhibited growth of U2OS cells and primary human OS cells in severe combined immunodeficient mice. AMPK activation, mTORC1 inhibition, autophagy induction, as well as RTK degradation and apoptosis activation were detected in PF-06409577-treated xenografts. In conclusion, activation of AMPK by PF-06409577 inhibits OS cell growth.

Tanshinone IIA inhibits osteosarcoma growth through modulation of AMPK-Nrf2 signaling pathway

Tanshinone IIA (Tan IIA) is a member of the major lipophilic components extracted from the root of Salvia miltiorrhiza Bunge. Osteosarcomas are primary malignant tumors of bone. The aim of our study is to explore the role of Tan IIA in osteosarcomas survival, migration, and proliferation. MG63 osteosarcoma cell line was cultured in vitro and treated with different concentrations of Tan IIA. Then, ELISA, immunofluorescence, qPCR, western blots, and pathway analysis were conducted to verify whether Tan II modulated osteosarcoma survival, migration, and proliferation through the AMPK/Nrf2 signaling pathway. Our results indicated that Tan IIA dose-dependently inhibited MG63 osteosarcoma cell survival, migration, and proliferation. Mechanistically, Tan IIA reduced cell viability and inhibited the transcriptions of migratory factors. In addition, the number of proliferative MG63 osteosarcoma cell was also reduced by Tan IIA. Molecular investigations demonstrated that Tan IIA treatment caused a drop in the transcriptions and activities of AMPK and Nrf2. Interestingly, knockdown of AMPK and Nrf2 markedly attenuated MG63 osteosarcoma cell survival, migration, and proliferation. Altogether, our results indicate that Tan IIA could be used as an effective anticancer drug to control osteosarcoma proliferation through affecting its survival, migration, and proliferation.

Brosimone I, an isoprenoid-substituted flavonoid, induces cell cycle G1 phase arrest and apoptosis through ROS-dependent endoplasmic reticulum stress in HCT116 human colon cancer cells

Brosimone I is an isoprenoid-substituted flavonoid from Artocarpus heterophyllus. Here, we reported for the first time that brosimone I induced cell cycle G1 phase arrest and apoptosis in HCT116 human colon cancer cells. Brosimone I treatment increased the cytosolic Ca2+ level, and subsequently activated the CaMKKβ-AMPK pathway. STO-609, a CaMKKβ inhibitor, and compound C, an AMPK-specific inhibitor, attenuated brosimone I-induced loss of cell viability in HCT116 cells. Furthermore, brosimone I enhanced ER stress. Salubrinal, an ER stress inhibitor, reduced brosimone I-induced cell growth inhibition. In addition, brosimone I was found to increase ROS generation and the inhibition of ROS formation by NAC, a ROS inhibitor, attenuated brosimone I-induced cell death, cytosolic Ca2+ increase, and ER stress markers. Collectively, our findings reveal that brosimone I induces cell cycle G1 phase arrest and apoptosis via the induction of ROS-mediated increased cytosolic Ca2+, ER stress, and the activation of the CaMKKβ-AMPK signaling pathway.

Baicalein Induces Autophagy and Apoptosis through AMPK Pathway in Human Glioma Cells

Baicalein (BAI) is a natural flavonoid. It has been shown that BAI has anticancer effects, but the molecular mechanism is still unclear. The aim of the current study was to confirm whether or not BAI triggers autophagy and induces AMPK activation in glioma U251 cells. The Ad-mcherry-GFP-LC3B adenovirus experiments indicated that BAI induces glioma cell autophagy. Western blotting showed that the level of LC3II expression increased with the time and concentration of BAI. Following treatment with chloroquine, the expression of LC3 was enhanced Immunofluorescence also confirmed this result. At the same time, cleaved caspase-3, DAPI staining, and JC-1 staining revealed that apoptosis was also induced in the induction of autophagy. In addition, we found that BAI activates phosphorylation of AMPK, which is further confirmed using compound C in this process. When the phosphorylation of AMPK was inhibited, autophagy, and apoptosis were also inhibited. In conclusion, BAI induces autophagy and apoptosis through AMPK pathway. Surprisingly, our research provides new insight with the function of anticancer of BAI, and the potential of the promotion in glioma cell apoptosis might be related to autophagy activation. These results demonstrate the anticancer activity of BAI, which can be used as potential therapeutic agents for cancer therapy.

Transient Receptor Potential V Channels Are Essential for Glucose Sensing by Aldolase and AMPK

Fructose-1,6-bisphosphate (FBP) aldolase links sensing of declining glucose availability to AMPK activation via the lysosomal pathway. However, how aldolase transmits lack of occupancy by FBP to AMPK activation remains unclear. Here, we show that FBP-unoccupied aldolase interacts with and inhibits endoplasmic reticulum (ER)-localized transient receptor potential channel subfamily V, inhibiting calcium release in low glucose. The decrease of calcium at contact sites between ER and lysosome renders the inhibited TRPV accessible to bind the lysosomal v-ATPase that then recruits AXIN:LKB1 to activate AMPK independently of AMP. Genetic depletion of TRPVs blocks glucose starvation-induced AMPK activation in cells and liver of mice, and in nematodes, indicative of physical requirement of TRPVs. Pharmacological inhibition of TRPVs activates AMPK and elevates NAD+ levels in aged muscles, rejuvenating the animals' running capacity. Our study elucidates that TRPVs relay the FBP-free status of aldolase to the reconfiguration of v-ATPase, leading to AMPK activation in low glucose.

The Mediterranean Diet as source of bioactive compounds with multi-targeting anti-cancer profile

Many bioactive agents have been extracted from plants or belong to functional foods and have been considered in the treatment of serious and multifactorial diseases, such as cancer. In particular, this review is focused on the anti-cancer properties owned by several natural products typically from the Mediterranean area. In some regions of the South of Italy, a lower cancer incidence has been observed. There is increasing evidence that adherence to a Mediterranean dietary pattern correlates with reduced risk of several cancer types. This could be mainly attributed to the typical lifestyle aspects of the Mediterranean diet, such as high consumption of fruit and vegetables. In this review, the main natural products of the Mediterranean area are discussed, with particular attention on their anti-cancer properties endowed with multi-target profiles.

Capsaicin induces cytotoxicity in human osteosarcoma MG63 cells through TRPV1-dependent and -independent pathways

An accumulating body of evidence has shown that capsaicin induces apoptosis in various tumor cells as a mechanism of its anti-tumor activity. However, the effects of capsaicin on osteosarcoma have not been studied extensively. In the current study, we explore the molecular mechanism of capsaicin-mediated tumor suppressive function in osteosarcoma. We found that capsaicin-induced apoptosis and the activation of transient receptor potential receptor vanilloid 1 (TRPV1) in a dose- and time-dependent manner in human osteosarcoma MG63 cells in vitro. Blocking TRPV1 using capsazepine attenuated the capsaicin-induced cytotoxicity, mitochondrial dysfunction, overproduction of reactive oxygen species (ROS) and decrease in superoxide dismutase (SOD) activity. In addition, the results demonstrated that capsaicin induced the activation of adenosine 5'-monophosphate-activated protein kinase (AMPK), p53 and C-jun N-terminal kinase (JNK). In addition, Compound C (antagonist of AMPK) attenuated the activation of p53, which appeared to be TRPV1 independent. Taken together, the present study suggests that capsaicin effectively causes cell death in human osteosarcoma MG63 cells via the activation of TRPV1-dependent (mitochondrial dysfunction, and overproduction of ROS and JNK) and TRPV1-independent (AMPK-p53) pathways. Thus, capsaicin may be a potential anti-osteosarcoma agent.

Capsaicin enhances erlotinib-induced cytotoxicity via AKT inactivation and excision repair cross-complementary 1 (ERCC1) down-regulation in human lung cancer cells

Capsaicin, a natural active ingredient of green and red peppers, has been demonstrated to exhibit anti-cancer properties in several malignant cell lines. Excision repair cross-complementary 1 (ERCC1) has a leading role in the nucleotide excision repair (NER) process because of its involvement in the excision of DNA adducts. Erlotinib (Tarceva^R) is a selective epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor that has demonstrated clinical activity in non-small cell lung cancer (NSCLC) cells. However, whether capsaicin and erlotinib could induce synergistic cytotoxicity in NSCLC cells through modulating ERCC1 expression is unknown. In this study, capsaicin decreased the ERCC1 expression in an AKT inactivation dependent manner in two human lung adenocarcinoma cells, namely, A549 and H1975. Enhancement of AKT activity by transfection with constitutive active AKT vectors increased the ERCC1 protein level as well as the cell survival by capsaicin. Moreover, capsaicin synergistically enhanced the cytotoxicity and cell growth inhibition of erlotinib in NSCLC cells, which were associated with the down-regulation of ERCC1 expression and inactivation of AKT in A549 and H1975 cells. Together, these results may provide a rationale to combine capsaicin with erlotinib for lung cancer treatment.

Capsaicin-induced TRIB3 upregulation promotes apoptosis in cancer cells

Background

Capsaicin (8-methyl-N-vanillyl-6-nonenamide) is one of the main pungent components of chili peppers and has been shown to exert various effects on numerous physiological processes. Recent studies have focused on the chemopreventive effects of capsaicin, which can combat growth in various human cancer cell systems. The tribbles-related protein 3 (TRIB3) is evolutionarily conserved from Drosophila to humans. In the latter, TRIB3 is a key determinant in numerous cellular processes, including apoptosis.

Purpose

The aim of this study was to examine the importance of TRIB3 in the antitumor efficacy of capsaicin in human cancer cells, and further assess potential mechanism(s) underlying the capsaicin-induced upregulation of TRIB3.

Methods

Human cancer cell lines were treated with capsaicin, then evaluated for levels of TRIB3 and molecules related to apoptosis or signaling pathways. The impact of TRIB3 on capsaicin-induced apoptosis was investigated using si-RNA or overexpression of TRIB3.

Results

It is the first time to show that TRIB3 is targeted by capsaicin to promote apoptosis. Capsaicin promotes apoptotic cell death by upregulating TRIB3 expression in cancer cells. Overexpression of TRIB3 enhances capsaicin-induced apoptosis, and TRIB3 knockdown experiments demonstrate that the effect of capsaicin in apoptotic cell death is correlated with the induction of TRIB3 in cancer cells. Finally, enhancements in gene expression and protein stability are involved in the capsaicin-induced upregulation of TRIB3.

Conclusion

Our results show that the capsaicin-induced upregulation of TRIB3 triggers apoptosis and thereby contributes to the suppression of cell growth in cancer cell lines.

Food derived respiratory complex I inhibitors modify the effect of Leber hereditary optic neuropathy mutations

Mitochondrial DNA mutations in genes encoding respiratory complex I polypeptides can cause Leber hereditary optic neuropathy. Toxics affecting oxidative phosphorylation system can also cause mitochondrial optic neuropathy. Some complex I inhibitors found in edible plants might differentially interact with these pathologic mutations and modify their penetrance. To analyze this interaction, we have compared the effect of rotenone, capsaicin and rolliniastatin-1 on cybrids harboring the most frequent Leber hereditary optic neuropathy mutations and found that m.3460G > A mutation increases rotenone resistance but capsaicin and rolliniastatin-1 susceptibility. Thus, to explain the pathogenicity of mitochondrial diseases due to mitochondrial DNA mutations, their potential interactions with environment factors will have to be considered.

mTOR: An attractive therapeutic target for osteosarcoma?

Osteosarcoma (OS) is a common primary malignant bone tumor with high morbidity and mortality in children and young adults. How to improve poor prognosis of OS due to resistance to chemotherapy remains a challenge. Recently, growing findings show activation of mammalian target of rapamycin (mTOR), is associated with OS cell growth, proliferation, metastasis. Targeting mTOR may be a promising therapeutic approach for treating OS. This review summarizes the roles of mTOR pathway in OS and present research status of mTOR inhibitors in the context of OS. In addition, we have attempted to discuss how to design a better treatment project for OS by combining mTOR inhibitor with other drugs.

Capsaicin inhibits proliferation and induces apoptosis in osteosarcoma cell lines via the mitogen‑activated protein kinase pathway

Capsaicin, a pungent molecular compound present in many hot peppers, exerts anticancer activities against various human cancer cell lines by inducing apoptosis. However, the effects of capsaicin on human osteosarcoma (OS) as well as the related mechanisms remain to be fully elucidated. In the present study, the anticancer effects of capsaicin on 3 human OS cell lines (MG63, 143B and HOS) were investigated. Various concentrations of capsaicin (50-300 µM) effectively decreased cell viability in all 3 OS cell lines in a dose-dependent manner. Notably, capsaicin-induced apoptosis was observed when OS cells were treated with relatively high concentrations of capsaicin (starting at 250 µM). In addition, the mitochondrial apoptotic pathway was involved in the capsaicin-induced apoptosis in the OS cells. Meanwhile, our results also indicated that at relatively low concentrations (e.g., 100 µM), capsaicin could inhibit the proliferation, decrease the colony forming ability and induce G0/G1 phase cell cycle arrest of OS cells in a dose-dependent manner. Moreover, our results revealed that the anticancer effects induced by capsaicin on OS cell lines involved multiple MAPK signaling pathways as indicated by inactivation of the ERK1/2 and p38 pathways and activation of the JNK pathway. Furthermore, the results of animal experiments showed that capsaicin inhibited tumor growth in a xenograft model of human OS. In conclusion, these results indicate that capsaicin may exert therapeutic benefits as an adjunct to current cancer therapies but not as an independent anticancer agent.

An updated review on molecular mechanisms underlying the anticancer effects of capsaicin

The quest for developing anticancer principles from natural sources has a long historical track record and remarkable success stories. The pungent principle of hot chili pepper, capsaicin, has been a subject of research for anticancer drug discovery for more than three decades. However, the majority of research has revealed that capsaicin interferes with various hallmarks of cancer, such as increased cell proliferation, evasion from apoptosis, inflammation, tumor angiogenesis and metastasis, and tumor immune escape. Moreover, the compound has been reported to inhibit carcinogen activation and chemically induced experimental tumor growth. Capsaicin has also been reported to inhibit the activation of various kinases and transcription that are involved in tumor promotion and progression. The compound activated mitochondria-dependent and death receptor-mediated tumor cell apoptosis. Considering the growing interest in capsaicin, this review provides an update on the molecular targets of capsaicin in modulating oncogenic signaling.

5-Aminoimidazole-4-carboxamide ribonucleoside-mediated adenosine monophosphate-activated protein kinase activation induces protective innate responses in bacterial endophthalmitis

The retina is considered to be the most metabolically active tissue in the body. However, the link between energy metabolism and retinal inflammation, as incited by microbial infection such as endophthalmitis, remains unexplored. In this study, using a mouse model of Staphylococcus aureus (SA) endophthalmitis, we demonstrate that the activity (phosphorylation) of 5' adenosine monophosphate-activated protein kinase alpha (AMPKα), a cellular energy sensor and its endogenous substrate; acetyl-CoA carboxylase is down-regulated in the SA-infected retina. Intravitreal administration of an AMPK activator, 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR), restored AMPKα and acetyl-CoA carboxylase phosphorylation. AICAR treatment reduced both the bacterial burden and intraocular inflammation in SA-infected eyes by inhibiting NF-kB and MAP kinases (p38 and JNK) signalling. The anti-inflammatory effects of AICAR were diminished in eyes pretreated with AMPK inhibitor, Compound C. The bioenergetics (Seahorse) analysis of SA-infected microglia and bone marrow-derived macrophages revealed an increase in glycolysis, which was reinstated by AICAR treatment. AICAR also reduced the expression of SA-induced glycolytic genes, including hexokinase 2 and glucose transporter 1 in microglia, bone marrow-derived macrophages and the mouse retina. Interestingly, AICAR treatment enhanced the bacterial phagocytic and intracellular killing activities of cultured microglia, macrophages and neutrophils. Furthermore, AMPKα1 global knockout mice exhibited increased susceptibility towards SA endophthalmitis, as evidenced by increased inflammatory mediators and bacterial burden and reduced retinal function. Together, these findings provide the first evidence that AMPK activation promotes retinal innate defence in endophthalmitis by modulating energy metabolism and that it can be targeted therapeutically to treat ocular infections.

Sirtuin 1 (SIRT1) Deacetylase Activity and NAD⁺/NADH Ratio Are Imperative for Capsaicin-Mediated Programmed Cell Death

Capsaicin is considered a chemopreventive agent by virtue of its selective antigrowth activity, commonly associated with apoptosis, against cancer cells. However, noncancerous cells possess relatively higher tolerance to capsaicin, although the underlying mechanism for this difference remains unclear. Hence, this study aimed to elucidate the differential effects of capsaicin on cell lines from lung tissues by addressing the signal pathway leading to two types of cell death. In MRC-5 human fetal lung cells, capsaicin augmented silent mating type information regulation 1 (SIRT1) deacetylase activity and the intracellular NAD(+)/NADH ratio, decreasing acetylation of p53 and inducing autophagy. In contrast, capsaicin decreased the intracellular NAD(+)/NADH ratio, possibly through inhibition of tumor-associated NADH oxidase (tNOX), and diminished SIRT1 expression leading to enhanced p53 acetylation and apoptosis. Moreover, SIRT1 depletion by RNA interference attenuated capsaicin-induced apoptosis in A549 cancer cells and autophagy in MRC-5 cells, suggesting a vital role for SIRT1 in capsaicin-mediated cell death. Collectively, these data not only explain the differential cytotoxicity of capsaicin but shed light on the distinct cellular responses to capsaicin in cancerous and noncancerous cell lines.

CTAB induced mitochondrial apoptosis by activating the AMPK–p53 pathway in hepatocarcinoma cells

CTAB induced mitochondrial apoptosis by activating the AMPK-p53 pathway in hepatocarcinoma cells.

Capsaicin mediates cell cycle arrest and apoptosis in human colon cancer cells via stabilizing and activating p53

Capsaicin is the major pungent ingredient in red peppers which is world widely consumed. Except its potent pain relieving efficacy as reported, capsaicin also exerted its antitumor activity in several tumor models. Here, we reported that capsaicin had a profound anti-proliferative effect on human colon cancer cells via inducing cell cycle G0/G1 phase arrest and apoptosis, which was associated with an increase of p21, Bax and cleaved PARP. The underlying mechanism of capsaicin's antitumor potency was mainly attributed to the stabilization and activation of p53. Capsaicin substantially prolonged the half-life of p53 and significantly elevated the transcriptional activity of p53. Through suppressing the interaction between p53 and MDM2, MDM2-mediated p53 ubiquitination was remarkably decreased after capsaicin treatment, which resulted in the stabilization and accumulation of p53. The results of p53-shRNA experiment further demonstrated that p53 knockdown severely impaired the sensitivity of tested cells to capsaicin, G0/G1 phase arrest and the apoptosis induced by capsaicin in p53-knockdown cells was also dramatically decreased, implicating the important role of p53 played in capsaicin's antitumor activity. In summary, our data suggested that capsaicin, or a related analogue, may have a role in the management of human colon cancer.