Indole-3-carbinol inhibits LPS-induced inflammatory response by blocking TRIF-dependent signaling pathway in macrophages

Indole-3-carbinol (I3C), a natural hydrolysis product of glucobrassicin, is a member of the Brassica family of vegetables and is known to have various anti-cancer activities. In the present study, we assessed in vitro and in vivo anti-inflammatory effects of I3C and its molecular mechanisms. I3C attenuated the production of pro-inflammatory mediators such as NO, IL-6, and IL-1β in LPS-induced Raw264.7 cells and THP-1 cells through attenuation of the TRIF-dependent signaling pathway. Furthermore, I3C suppressed the infiltration of immune cells into the lung and pro-inflammatory cytokine production such as IL-6, TNF-α in broncho-alveolar lavage fluid (BALF) in the LPS-induced acute lung injury mouse model. I3C also suppressed IL-1β secretion in nigericin treated in vivo model. I3C has potent anti-inflammatory effects through regulating TRIF-dependent signaling pathways, suggesting that I3C may provide a valuable therapeutic strategy in treating various inflammatory diseases.     

Indole-3-carbinol enhances anti-proliferative, but not anti-invasive effects of oxaliplatin in colorectal cancer cell lines

The primary aim of this study was to determine whether combination of the chemopreventive agent indole-3-carbinol (I3C) with oxaliplatin would decrease proliferative index and invasive potential of human colorectal tumour cells. Combination of the agents resulted in a 170-fold decrease in proliferative capacity in SW480 and SW620 cell lines, which was approximately 6-fold greater than for oxaliplatin alone. Decreased proliferation was attributed to enhanced S-phase cell cycle arrest for SW480, and increased apoptosis for SW620 cells. The combined agents resulted in significantly increased E-cadherin levels in SW480 cells, and beta-catenin levels in both cell lines (assessed by in-cell westerns). In SW480 cells confocal microscopy revealed an increase in membrane-associated beta-catenin levels, with oxaliplatin treatments enhancing nuclear export and cytoplasmic localisation. In SW620 cells, all treatments increased membrane localisation of E-cadherin. Whilst both oxaliplatin and I3C decreased invasive capacity of SW480 cells, this was not further enhanced by the combined treatment.     

Indole-3-carbinol induces apoptosis through p53 and activation of caspase-8 pathway in lung cancer A549 cells

Indole-3-carbinol (I3C) has anti-tumor effects in various cancer cell lines. However, the anti-tumor effect of I3C on human lung cancers has been rarely reported. We investigated the anti-tumor effects and its mechanism of I3C on human lung carcinoma A549 cell line. Treatment of the A549 cells with I3C significantly reduced cell proliferation, increased formations of fragmented DNA and apoptotic body, and induced cell cycle arrest at G0/G1 phase. I3C increased not only the protein levels of cyclin D1, phosphorylated p53, and p21 but also the expression of Fas mRNA. Cleavage of caspase-9, -8, -3 and PARP also was increased by I3C. Treatment with wortmannin significantly suppressed both I3C-induced Ser15 phosphorylation and accumulation of p53 protein. The inhibition of caspase-8 by z-IETD-FMK significantly decreased cleavage of procaspase-8,-3 and PARP in I3C-treated A549 cells. Taken together, these results demonstrate that I3C induces cell cycle arrest at G0/G1 through the activation of p-p53 at Ser 15 and induces caspase-8 mediated apoptosis via the Fas death receptor. This molecular mechanism for apoptotic effect of I3C on A549 lung carcinoma cells may be a first report and suggest that I3C may be a preventive and therapeutic agent against lung cancer.     

Schizandra chinensis extracts induce apoptosis in human gastric cancer cells via JNK/p38 MAPK activation and the ROS-mediated/mitochondria-dependent pathway

Abstract

Context: Schizandra chinensis Baill (Magnoliaceae) fruit extract (SCE) is considered a traditional herbal medicine for the treatment and alleviation of various diseases. Gastric cancer is the second most common cause of cancer-related death worldwide, and the first most common in Korea.

Objectives: This study investigates the mechanism of SCE-induced apoptosis in AGS human gastric cancer cells.

Materials and methods: SCE concentrations from 100 to 400?µg/ml were used. Cell viabilities were determined using MTT assay. Members of the Bcl-2 family and Bax were detected by Western blotting. RT-PCR was performed to measure the expression level of the Fas/FasL pro-apoptotic genes.

Results: SCE inhibited the proliferation AGS cells for 24 or 72?h (inhibition by 3.1%?±?5.2% at 100?µg/ml and 87.3%?±?7.6% at 400?µg/ml at 24?h and by 40.2%?±?5.3% 100?µg/ml and 95.3%?±?1.3% 400?µg/ml at 72?h) and increased the sub-G1 phase (25.3%?±?5.2% at 100?µg/ml and 370.2%?±?7.2% at 400?µg/ml) and the mitochondrial membrane depolarization (11.2%?±?2.1% at 100?µg/ml and 311.5%?±?6.1% at 400?µg/ml). The SCE-induced apoptotic cell death showed the down-regulation of Bcl-2, but up-regulation of Bax. Subsequently, SCE increased the expression level of Fas/FasL, activated caspase-9 and -3, and increased reactive oxygen species generation. Also, JNK II inhibitor or a p38 MAPK inhibitor inhibited SCE-induced cell death.

Discussion and conclusion: These results indicate that SCE might be an effective chemotherapeutic for the treatment of human gastric cancer.     

New 6(17)-epoxylathyrane diterpene: aellinane from Euphorbia aellenii induces apoptosis via mitochondrial pathway in ovarian cancer cell line

Euphorbia species have been used in traditional medicine in many countries for the treatment of cancer. This article aims to evaluate the capability of a new lathyrane diterpene isolated from Euphorbia aellenii to induce apoptosis in the Caov-4 cell line to determine the underlying mechanism of its anticancer effects. A new 6(17)-epoxylathyrane diterpenes: aellinane from Euphorbia aellenii was evaluated for viability of Caov-4 cells by MTT method. Apoptosis induction by lathyrane diterpene was confirmed by annexin V-FITC/PI staining, and caspase-6 activation. The Bcl2 and Bax protein content were detected by Western blot analysis. Finally, we employed the fluorescent ROS detection kit and fluorochrome JC-1 to determine ROS levels and loss of mitochondria membrane potential (ΔΨm) in Caov-4 cells, respectively. The results show that lathyrane diterpene has significant cytotoxic effect against Caov-4 cells. The IC50 value was 45?μM. Annexin V/propidium iodide (PI) staining and caspase-6 activity assay confirmed that lathyrane diterpene is able to induce apoptosis in Caov-4 cells. The results also demonstrate that lathyrane diterpene up-regulated Bax and down-regulated Bcl-2 proteins. Moreover, apoptotic effect of lathyrane diterpene was also related to ROS production and loss of mitochondrial membrane potential (ΔΨm). This study demonstrated that lathyrane diterpene has profound activity against Caov-4 cells. Analysis of apoptosis-related proteins revealed that lathyrane diterpene triggered the mitochondrion-mediated apoptosis pathway, which led to the loss of mitochondrial membrane potential (ΔΨm) and activation of caspase-6. Therefore, we believe that lathyrane diterpene might be a promising natural compound in ovarian cancer therapy.     

吲哚-3-原醇对人肺癌细胞株A549的促凋亡和增殖抑制作用

目的探讨吲哚-3-原醇(Indol-3-carbinol,I3C)对肺腺癌细胞株A549细胞增殖和凋亡的影响及其作用机制。方法将对数生长期的A549细胞分别用不同浓度的I3C处理(0、25、50、100μg/m L)。细胞培养72 h后,采用M TT观察I3C对A549细胞的增殖抑制作用;Annexin V-PI/FITC检测细胞凋亡;Western blotting检测细胞中PI3K、p-AKT、Bax、Bcl-2、Cleavage-PARP、Clevage-Caspase3蛋白的变化。结果 I3C可以呈浓度依赖性地诱导A549细胞的增殖抑制和凋亡,上调Bax和Cleavage-PARP、Cleavage-Caspase3表达,下调PI3K、p-AKT和Bcl-2,对AKT表达无明显影响。结论 I3C可通过抑制PI3K/AKT信号通路而诱导A549细胞增殖抑制和凋亡。     

Glycoborinine induces apoptosis through mitochondrial pathway in HepG2 cells

Glycoborinine (GB), a natural carbazole alkaloid isolated from Glycosmis pentaphylla, has been shown to be a potential molecule against cancer cells. In this study, the cell-signaling pathway of its anti-tumor activity was investigated. MTT assay result showed that GB inhibited HepG2 cell proliferation in a dose- and time-dependent manner and 50% inhibiting concentration (IC₅₀) of GB-induced cell death was 39.7 μM for a period of 48 h. GB-induced HepG2 apoptosis was confirmed by Hochest 33258 staining and PI staining. The level of reactive oxygen species (ROS) was measured with H₂DCF-DA staining and the change of mitochondrial membrane potential (△Ψ^m) was analyzed with tetrechloro-tetraethylbenzimidazolcarbocyanine iodide (JC-1) probe. Results showed that GB at 12.5, 25, and 50 μM promoted ROS production. GB induced HepG2 apoptosis through a mitochondrial apoptotic pathway, which was demonstrated by GB-induced increase in the ratio of Bax/Bcl-2, cytochrome C release, the ratio of cleaved caspase-3/procaspase-3, and the ratio of cleaved poly ADP-ribose polymerase (cleaved PARP)/poly ADP-ribose polymerase (PARP). To summarize, this study demonstrated that GB could induce HepG2 apoptosis through the mitochondrial-dependent pathway, which might provide a promising approach to cure liver cancer with GB.     

OSU-A9, an indole-3-carbinol derivative,induces cytotoxicity in acute myeloid leukemia through reactive oxygen species-mediated apoptosis

Indole-3-carbinol (I3C) is a broadly targeted phytochemical shown to prevent carcinogenesis in animal studies and to suppress the proliferation of cancer cells of human breast, colon, prostate, and endometrium. Here we demonstrate that OSU-A9, an I3C derivative with improved anticancer potency, induces cytotoxicity in acute myeloid leukemia (AML) cell lines (HL-60 and THP-1) and primary leukemia cells from AML patients in a dose-responsive manner. Normal human bone marrow cells were less sensitive to OSU-A9 than leukemia cells. OSU-A9 induces caspase activation, PARP cleavage, and autophagy but not autophagic cell death. Interestingly, pretreatment of AML cell lines and primary AML cells with N-acetylcysteine or glutathione rescues them from apoptosis (and concomitant PARP cleavage) and Akt hypophosphorylation, implicating a key role of reactive oxygen species (ROS) in OSU-A9-related cytotoxicity. Importantly, the anticancer utility of OSU-A9 is extended in vivo as it, administered intraperitoneally, suppresses the growth of THP-1 xenograft tumors in athymic nude mice without obvious toxicity. This study shows that ROS-mediated apoptosis contributes to the anticancer activity of OSU-A9 in AML cell lines and primary AML cells, and thus should be considered in the future assessment of its translational value in AML therapy.     

参术胶囊对脾虚胃癌小鼠细胞凋亡线粒体途径下游基因的影响

<正>前期研究表明,具有健脾功效的中药五类新药参术胶囊对胃癌及癌前病变具有治疗和预防作用[1-3],但其机制尚未完全阐明。目前,用药物治疗肿瘤的重要机制之一就是诱导细胞凋亡[4]。为研究参术胶囊治疗胃癌与诱导细胞凋亡之间的关系,我们采用TUNEL-AP法和免疫组化法研究参术胶囊对脾虚胃癌小鼠细胞凋亡线粒体途径下游基因的影响。1材料与方法1.1主要试剂和仪器原位细胞死亡检测试剂盒(美国     

Indole-3-carbinol, but not its major digestive product 3,3'-diindolylmethane, induces reversible hepatocyte hypertrophy and cytochromes P450

Indole-3-carbinol (I-3-C) and 3,3′-diindolylmethane (DIM) have been shown to reduce the incidence and multiplicity of cancers in laboratory animal models. Based on the observation that I-3-C induced hepatocyte hypertrophy when administered orally for 13 weeks to rats, a treatment and recovery study was undertaken to test the hypothesis that the induction of hepatocyte hypertrophy and cytochrome P450 (CYP) activity by I-3-C are adaptive, reversible responses. Additionally, we directly compared the effects of I-3-C to those of its principle metabolite DIM. Rats were treated orally for 28 days with 2 doses of I-3-C (5 and 50 mg I-3-C/kg body weight/day) and DIM (7.5 and 75 mg DIM/kg body weight/day) and then one-half of the animals were not treated for an additional 28 days. Organ weights, histopathology, and the CYP enzyme activities of 1A1/2, 2B1/2, 2C9, 2D6, 2E1, 3A4, and 19 A were measured both after treatment and after recovery. Oral administration of 50 mg I-3-C/kg body weight/day to rats for 28 days significantly increased liver weights and CYP enzyme activities. The effects in males were more pronounced and persistent after recovery than the effects in females. The increased organ weights returned to control values after treatment. Conversely, DIM did not alter liver weights and had no effect on CYP activities after the 28-day treatment. Some changes in CYP activities were measured after the DIM recovery period but the magnitudes of the changes were considered biologically insignificant. The results show that I-3-C, but not DIM, induces reversible adaptive responses in the liver.     

Indole-3-carbinol attenuates the deleterious gestational effects of bisphenol A exposure on the prostate gland of male F1 rats

Bisphenol A (BPA) is a chemical that has been investigated for it potential to cause prostate diseases. In this study, pregnant Sprague-Dawley rats were treated with 25 or 250 μg/kg BPA from gestational day (GD) 10 to GD21 with or without concurrent indole-3-carbinol (I3C) feeding. I3C is a phytochemical, and it affords chemoprotection against many types of neoplasia. Male F1 rats from different litters were euthanized on post-natal day (PND) 21 and PND180. BPA-treated groups showed a significant increase in histopathological lesions, but I3C feeding reversed many of these changes, mainly at PND180. Maternal I3C feeding increased prostate epithelial apoptosis in the BPA-treated groups and across age groups. Furthermore, I3C induced partial normalization of the prostate histoarchitecture. The results pointed to a protective effect of maternal I3C feeding during pregnancy in the BPA-exposed male offspring, thereby indicating reduction in the harmful effects of gestational BPA imprinting on the prostate.     

雷公藤红素通过PI3K/AKT/mTOR信号通路对胃癌MFC细胞增殖和凋亡的影响

目的研究雷公藤红素对胃癌MFC细胞内PI3K/AKT/mTOR信号通路的影响及其对胃癌MFC细胞增殖的抑制和促凋亡作用机制。方法分别设置对照组和雷公藤红素低、中、高剂量(5、10、20 mmol/L)组,采用MTT法检测雷公藤红素对胃癌MFC细胞增殖的影响;采用流式细胞技术检测雷公藤红素对胃癌MFC细胞周期的影响及MFC细胞凋亡的情况;Western blotting检测雷公藤红素对胃癌MFC细胞内凋亡相关蛋白Bax、Bcl-2和PI3K、AKT和mTOR蛋白表达的影响;实时定量PCR检测雷公藤红素对胃癌MFC细胞内PI3K、AKT和mTORm RNA表达的影响。结果与对照组比较,雷公藤红素能够呈剂量相关性地显著抑制胃癌MFC细胞的增殖(P0.05);与对照组比较,雷公藤红素能够呈剂量相关性地显著引起MFC细胞G2/M期阻滞(P0.05);与对照组比较,雷公藤红素能够呈剂量相关性地显著促进MFC细胞的凋亡(P0.05);与对照组比较,雷公藤红素能够呈剂量相关性地显著抑制MFC细胞内抗凋亡蛋白Bcl-2蛋白和PI3K、AKT、mTOR蛋白的表达(P0.05),显著促进MFC细胞内促凋亡蛋白Bax的表达(P0.05);与对照组比较,雷公藤红素能够呈剂量相关性地显著抑制MFC细胞内PI3K、AKT和mTORm RNA的表达(P0.05)。结论雷公藤红素能够抑制胃癌MFC细胞的增殖并促进胃癌MFC细胞凋亡,其作用机制可能是通过抑制胃癌MFC细胞内PI3K/AKT/mTOR信号通路中PI3K、AKT、mTOR等蛋白的表达而抑制胃癌MFC细胞的增殖,进而促进胃癌MFC细胞内促凋亡蛋白Bax的表达,同时抑制抗凋亡蛋白Bcl-2的表达,从而促进胃癌MFC细胞凋亡。     

Osthole induces human nasopharyngeal cancer cells apoptosis through Fas–Fas ligand and mitochondrial pathway

Nasopharyngeal carcinoma (NPC) is endemic in Southern China and Southeast Asia. The present study investigated the activity of osthole in suppressing NPC along with the underlying mechanism. Cell growth inhibition was measured using the MTT assay. Apoptosis was detected through 4ʹ,6‐diamidino‐2‐phenylindole staining and flow cytometry. Western blotting was used to identify the signaling pathway. Osthole markedly inhibited cell proliferation and induced apoptosis in the NPC cell line. Western blotting results revealed the increased activation of caspases 3, 8, and 9 and poly (ADP‐ribose) polymerase. Osthole treatment significantly reduced the expression of the antiapoptotic protein Bcl‐2 and increased the expression of the proapoptotic proteins Bax, Bak, BimL, BimS, and t‐Bid. Osthole treatment also increased the expression of Fas, FADD, TNF‐R1, TNF‐R2, DcR2, RIP, and DR5. In addition, osthole treatment significantly increased the expression levels of phosphorylated ERK1/2 and JNK1/2. These results suggested that osthole exerts cytotoxic effects on NPC cell lines mainly through apoptosis mediated by the Fas–Fas ligand and mitochondrial pathway. Osthole could be a potential anticancer agent for NPC.     

Fisetin induces apoptosis through mitochondrial apoptosis pathway in human uveal melanoma cells

Fisetin, a diatery flavonoid, been reported that possess anticancer effects in various cancers. The purpose of the study was to investigate the antitumor effects of fisetin in cultured uveal melanoma cell lines and compared with normal retinal pigment epithelial (RPE) cells. MTT assay was used for evaluating cytotoxic effects of fisetin. Flow cytometry study was used for the determination of apoptosis. JC‐1 fluorescent reader was used to determine mitochondrial transmembrane potential changes. The results shown that fisetin dose‐dependently decreased the cell viability of uveal melanoma cells but not influenced the cell viability of RPE cells. Apoptosis of uveal melanoma cells was induced by fisetin efficiently. Fisetin inhibited antiapoptotic Bcl‐2 family proteins and damaged the mitochondrial transmembrane potential. The levels of proapoptotic Bcl‐2 proteins, cytochrome c, and various caspase activities were increased by fisetin. In conclusion, fisetin induces apoptosis of uveal melanoma cells selectively and may be a promising agent to be explored for the treatment of uveal melanoma.     

磷脂酰肌醇3-激酶抑制剂LY29400联合吲哚-3-甲醇对人甲状腺未分化癌细胞FRO增殖的抑制作用

目的:研究磷脂酰肌醇3-激酶(PI3K)抑制剂LY29400(简称LY)联合吲哚-3-甲醇(I3C)对人甲状腺未分化癌细胞FRO增殖的抑制作用。方法:取对数生长期FRO细胞,分为空白对照组、I3C(250μmol/L)组、LY(10μmol/L)组和联用(I3C 250μmol/L+LY 10μmol/L)组,药物作用24、48、72 h。采用MTT法测定并计算各组细胞的增殖抑制率;流式细胞术检测作用48 h后的细胞凋亡率;Western blot法检测作用48 h后半胱氨酸天冬氨酸蛋白酶3(Caspase-3)蛋白的表达;免疫组化法检测作用48 h后Bcl-2、Bax蛋白的表达。结果:细胞增殖抑制率随药物作用时间的延长而明显升高,联用组各时间点间差异具有统计学意义(P<0.05)。与I3C组和LY组比较,联用组细胞的增殖抑制率、细胞凋亡率和Caspase-3、Bax蛋白表达均增强,Bcl-2蛋白表达和Bcl-2/Bax均降低,差异有统计学意义(P<0.01)。结论:LY与I3C联用对FRO细胞的增殖具有协同抑制作用,其机制可能与下调Bcl-2表达、上调Bax表达、激活Caspase级联反应诱导细胞凋亡有关。     

Emodin-induced apoptosis in human breast cancer BCap-37 cells through the mitochondrial signaling pathway

Emodin, a natural anthraquinone compound isolated from the rhizome of rhubarb, is reported to suppress the growth of tumor in many clinical situations. In this study, we focused on the effect of emodin in human breast cancer BCap-37 cells and further understand the underlying molecular mechanism in treating breast cancer. Using MTT assay and flow cytometry, we demonstrated the critical role of emodin in the suppression of the proliferation of BCap-37 cells based on a concentration-and time-dependent manner. The increase of apoptotic rate was also observed after incubation of BCap-37 cells on emodin at 20 microM and 50 microM for 48 h. The cells exhibited typical apoptotic features including cellular morphological change, chromatin condensation and membrane blebbing. The results of the study further showed that Bcl-2 level decreased, while Bax and cytosolic cytochrome c levels in sample cells increased after the emodin treatment by using Western blot. The decline in the Bcl-2/Bax ratio and the increase of cytosolic cytochrome c concentration were consistent with the increase of the apoptotic ratio. The results strongly suggest that the disruption of the mitochondrial signaling pathway was involved in emodin-induced apoptosis in BCap-37 cells.     

Modulation of P-glycoprotein-mediated multidrug resistance in K562 leukemic cells by indole-3-carbinol

Resistance to chemotherapeutic drugs is one of the major problems in the treatment of cancer. P-glycoprotein (P-gp) encoded by the mdr gene is a highly conserved protein, acts as a multidrug transporter, and has a major role in multiple drug resistance (MDR). Targeting of P-gp by naturally occurring compounds is an effective strategy to overcome MDR. Indole-3-carbinol (I3C), a glucosinolates present in cruciferous vegetables, is a promising chemopreventive agent as it is reported to possess antimutagenic, antitumorigenic, and antiestrogenic properties in experimental studies. In the present investigation, the potential of I3C to modulate P-gp expression was evaluated in vinblastine (VBL)-resistant K562 human leukemic cells. The resistant K562 cells (K562/R10) were found to be cross-resistant to vincristine (VCR), doxorubicin (DXR), and other antineoplastic agents. I3C at a nontoxic dose (10 x 10(-3) M) enhanced the cytotoxic effects of VBL time dependently in VBL-resistant human leukemia (K562/R10) cells but had no effect on parent-sensitive cells (K562/S). The Western blot analysis of K 562/R 10 cells showed that I3C downregulates the induced levels of P-gp in resistant cells near to normal levels. The quantitation of immunocytochemically stained K562/R10 cells showed 24%, 48%, and 80% decrease in the levels of P-gp by I3C for 24, 48, and 72 h of incubation. The above features thus indicate that I3C could be used as a novel modulator of P-gp-mediated multidrug resistance in vitro and may be effective as a dietary adjuvant in the treatment of MDR cancers.     

Genistein induces activation of the mitochondrial apoptosis pathway by inhibiting phosphorylation of Akt in colorectal cancer cells

Context: Genistein inhibits the proliferation and induces apoptosis of colorectal cancer cells; however, the underling molecular mechanisms remain to be determined.

Aim: The aim of this study was to investigate whether genistein reduces cell viability by suppressing the phosphorylation of AKT and activating the mitochondrial apoptosis pathway in colorectal cancer cells.

Materials and methods: The anti-proliferative effects of genistein (0, 25, 50, and 100?μM) on HCT-116 and LoVo cells were assessed using MTT assay. Genistein-induced apoptosis was measured by Hoechst 33258 staining and flow cytometry. The mRNA level of Bax was detected by real-time PCR. The protein levels of Bax, total Akt, and phosphorylated Akt were assessed by western blot.

Results: The IC₅₀ values of genistein were 690, 135, and 61?μM in HCT-116 cells and 204, 135, and 93?μM in LoVo cells after treatment for 24, 48, and 72?h, respectively. After treatment with different concentrations of genistein (0, 25, 50, and 100?μM) for 48?h, the early apoptotic cells in HCT-116 increased from 1.99%?±?0.55% to 6.78%?±?2.12%, 23.16%?±?3.87%, and 36.99%?±?3.76%, respectively. The same concentrations of genistein increased the early apoptotic cells in LoVo from 2.56%?±?1.42% to 3.21%?±?1.52%, 18.22%?±?3.56%, and 23.56%?±?3.02%, respectively. Moreover, genistein increased the mRNA and protein levels of Bax, while it inhibited the phosphorylation of Akt in HCT-116 cells.

Conclusion: Genistein inhibited cell proliferation and induced apoptosis of colorectal cancer cells. Genistein induced the mitochondrial pathway of apoptosis in HCT-116 cells by inhibiting phosphorylation of Akt.     

Atorvastatin induces mitochondrial dysfunction and cell apoptosis in HepG2 cells via inhibition of the Nrf2 pathway

Atorvastatin (ATO) is a 3‐hydroxy‐3‐methylglutaryl‐CoA reductase inhibitor widely used to treat hypercholesterolemia. However, clinical application is limited by potential hepatotoxicity. Nuclear factor‐erythroid 2‐related factor 2 (Nrf2) is a master regulator of cellular antioxidants, and oxidative stress is implicated in statin‐induced liver injury. This study investigated mechanisms of ATO‐induced hepatotoxicity and potential mitigation by Nrf2 signaling. ATO reduced Nrf2 and antioxidant enzyme superoxide dismutase‐2 (SOD2) expression in human hepatocarcinoma HepG2 cells. ATO also induced concentration‐dependent HepG2 cell toxicity, reactive oxygen species (ROS) accumulation, and mitochondrial dysfunction as evidenced by decreased mitochondrial membrane potential (MMP) and cellular adenosine triphosphate (ATP). Further, ATO induced mitochondria‐dependent apoptosis as indicated by increased Bax/Bcl‐2 ratio, cleaved caspase‐3, mitochondrial cytochrome c release and Annexin V‐fluorescein isothiocyanate/propidium iodide staining. Tert‐butylhydroquinone enhanced Nrf2 and SOD2 expression, and partially reversed ATO‐induced cytotoxicity, ROS accumulation, MMP reduction, ATP depletion and mitochondria‐dependent apoptosis. In conclusion, the present study demonstrates that ATO induces mitochondrial dysfunction and cell apoptosis in HepG2 cells, at least in part, via inhibition of the Nrf2 pathway. Nrf2 pathway activation is a potential prevention for ATO‐induced liver injury.     

Bufalin induces apoptosis via mitochondrial ROS-mediated caspase-3 activation in HCT-116 and SW620 human colon cancer cells

Objective: Bufalin has been reported to kill various types of cancer including human colorectal cancer. Our previous study demonstrated that bufalin induced cell death via autophagy in HT-29 and Caco-2 colon cancer cells, but the action of bufalin remains unclear. This study was conducted to investigate the role of bufalin in other colon cancer HCT-116 and SW620 cells as well as its potential mechanism.

Methods: The effect of bufalin in HCT-116 and SW620 colon cancer cells was detected by assessing cell viability and cell death. Apoptotic cells were analyzed by Western blot and trypan blue dye exclusion assay. Mitochondrial ROS production was analyzed by flow cytometry after DCFDA and DHR-123 staining. The potential mechanism was investigated via pharmacological inhibitors.

Results: Bufalin had high potency against HCT-116 and SW620 cells with IC50 values of 12.823?±?1.792?nM and 26.303?±?2.498?nM in HCT-116 and SW620 cells, respectively. Bufalin decreased cell viability, increased cell death as well as caspase-3 downstream target (cleaved PARP) accumulation, and these actions were significantly blocked by pan-caspase inhibitor zVAD-FMK. Mechanistically, ROS production, but neither the NAD(P)H oxidase, AMPK, ERK nor p38, is responsible for bufalin-induced apoptotic cell death. Moreover, bufalin-induced ROS generation is derived from mitochondria.

Conclusion: Bufalin significantly induces apoptosis in HCT-116 and SW620 colon cancer cells via mitochondrial ROS-mediated caspase-3 activation. We believe that our novel findings will greatly alter our current understanding on the anti-cancer mechanism of bufalin in colon cancer cells and will pave the way for further exploiting the clinical application.