Adiponectin receptor agonist AdipoRon induces apoptotic cell death and suppresses proliferation in human ovarian cancer cells

Molecular and Cellular Biochemistry - The aim of our study is to explore the regulation of C1QTNF1-AS1 on its target miR-221-3p/SOCS3 in human hepatocellular carcinoma (HCC). To explore the...     

A potent lead induces apoptosis in pancreatic cancer cells

Pancreatic cancer is considered a lethal and treatment-refractory disease. To obtain a potent anticancer drug, the cytotoxic effect of 2-(benzo[d]oxazol-3(2H)-ylmethyl)-5-((cyclohexylamino)methyl)benzene-1,4-diol, dihydrochloride (NSC48693) on human pancreatic cancer cells CFPAC-1, MiaPaCa-2, and BxPC-3 was assessed in vitro. The proliferation of CFPAC-1, MiaPaCa-2, and BxPC-3 is inhibited with IC(50) value of 12.9±0.2, 20.6±0.3, and 6.2±0.6 μM at 48 h, respectively. This discovery is followed with additional analysis to demonstrate that NSC48693 inhibition is due to induction of apoptosis, including Annexin V staining, chromatins staining, and colony forming assays. It is further revealed that NSC48693 induces the release of cytochrome c, reduces mitochondrial membrane potential, generates reactive oxygen species, and activates caspase. These results collectively indicate that NSC48693 mainly induces apoptosis of CFPAC-1, MiaPaCa-2, and BxPC-3 cells by the mitochondrial-mediated apoptotic pathway. Excitingly, the study highlights an encouraging inhibition effect that human embryonic kidney (HEK-293) and liver (HL-7702) cells are more resistant to the antigrowth effect of NSC48693 compared to the three cancer cell lines. From this perspective, NSC48693 should help to open up a new opportunity for the treatment of patients with pancreatic cancer.     

Blocking CD147 induces cell death in cancer cells through impairment of glycolytic energy metabolism

CD147 is a multifunctional transmembrane protein and promotes cancer progression. We found that the anti-human CD147 mouse monoclonal antibody MEM-M6/1 strongly induces necrosis-like cell death in LoVo, HT-29, WiDr, and SW620 colon cancer cells and A2058 melanoma cells, but not in WI-38 and TIG-113 normal fibroblasts. Silencing or overexpression of CD147 in LoVo cells enhanced or decreased the MEM-M6/1 induced cell death, respectively. CD147 is known to form complex with proton-linked monocarboxylate transporters (MCTs), which is critical for lactate transport and intracellular pH (pHi) homeostasis. In LoVo cells, CD147 and MCT-1 co-localized on the cell surface, and MEM-M6/1 inhibited the association of these molecules. MEM-M6/1 inhibited lactate uptake, lactate release, and reduced pHi. Further, the induction of acidification was parallel to the decrease of the glycolytic flux and intracellular ATP levels. These effects were not found in the normal fibroblasts. As cancer cells depend on glycolysis for their energy production, CD147 inhibition might induce cell death specific to cancer cells.     

Imexon induces an oxidative endoplasmic reticulum stress response in pancreatic cancer cells

Oxidative protein folding in the endoplasmic reticulum (ER) requires strict regulation of redox homeostasis. Disruption of the lumenal redox balance induces an integrated ER stress response that is associated with reduced protein translation, increased chaperone activity, and ultimately cell death. Imexon is a small-molecule chemotherapeutic agent that has been shown to bind glutathione (GSH) and induce oxidative stress in tumor cells; however, the mechanism of cytotoxicity is not well understood. In this report, we investigate the effects of imexon on the integrated ER stress response in pancreatic carcinoma cells. Acute exposure to imexon induces an ER stress response characterized by accumulation of the oxidized form of the oxidoreductase Ero1α, phosphorylation of eIF2α, and inhibition of protein synthesis. An RNA interference chemosensitization screen identified the eukaryotic translation initiation factor eIF2B5 as a target that enhanced imexon-induced growth inhibition of MiaPaCa-2 pancreatic cancer cells, but did not significantly augment the effects of imexon on protein synthesis. Concurrent reduction of intracellular thiols with N-acetyl cysteine reversed imexon activity, however cotreatment with superoxide scavengers had no effect, suggesting thiol binding may be a primary component of the oxidative effects of imexon. Moreover, the data suggest that disruption of the redox balance in the ER is a potential therapeutic target.     

Vitamin E succinate inhibits survivin and induces apoptosis in pancreatic cancer cells

Pancreatic cancer is the fourth leading cause of cancer-related deaths in the United States. Identifying novel chemotherapeutic and chemopreventive approaches is critical in the prevention and treatment of cancers such as pancreatic cancer. Vitamin E succinate (VES) is a redox-silent analog of the fat-soluble vitamin alpha-tocopherol. In the present study, we explored the antiproliferative action of VES and its effects on inhibitor of apoptosis proteins in pancreatic cancer cells. We show that VES inhibits cell proliferation and induces apoptosis in pancreatic cancer cells. Further, we demonstrate that VES downregulates the expression of survivin and X-linked inhibitor of apoptosis proteins. The apoptosis induced by VES was augmented by siRNA-mediated inhibition of survivin in PANC-1 cells. In summary, our results suggest that VES targets survivin signaling and induces apoptosis in pancreatic cancer cells.     

Raloxifene,a mixed estrogen agonist/antagonist,induces apoptosis through cleavage of BAD in TSU-PR1 human cancer cells

Selective estrogen receptor modulator is a proven agent for chemoprevention and chemotherapy of cancer. Raloxifene, a mixed estrogen agonist/antagonist, was developed to prevent osteoporosis and potentially reduce the risk of breast cancer. In this study, we examined the effect of raloxifene on the TSU-PR1 cell line. This cell line was originally reported to be a prostate cancer cell line, but recently it has been shown to be a human bladder transitional cell carcinoma cell line. The TSU-PR1 cell line contains high levels of estrogen receptor beta. Following treatment with raloxifene, evidence of apoptosis, including change in nuclear morphology, DNA fragmentation, and cytochrome c release, was observed in a dose-dependent manner in the TSU-PR1 cells (10(-9) to 10(-6) m range). We observed no detectable change in the steady-state levels of Bax, Bcl-2, and Bcl-X(L) following raloxifene treatment. However, raloxifene induced caspase-dependent cleavage of BAD to generate a 15-kDa truncated protein. Overexpression of a double mutant BAD resistant to caspase 3 cleavage blocked raloxifene-induced apoptosis. These results demonstrate that raloxifene induces apoptosis through the cleavage of BAD in TSU-PR1 cells. This molecular mechanism of apoptosis suggests that raloxifene may be a therapeutic agent for human bladder cancer.     

Deviant energetic metabolism of glycolytic cancer cells.

The central glycolytic and oxidative pathways and the ATP-producing mechanisms differ in sane and malignant cells by their regulation and dynamics. Fast-growing, poorly-differentiated cancer cells characteristically show high aerobic glycolysis. In the same way, cholesterol biosynthesis, which occurs by normal pathways in tumors, is deficient in feed-back regulation and in sterol-transport mechanisms. Other metabolic ways are deficient, as for example, intramitochondrial aldehyde catabolism, at the origin of a possible acetaldehyde toxicity, which can be circumvented by the synthesis of an unusual and neutral product for mammalian cells acetoin, through tumoral pyruvate dehydrogenase. If most of the glycolytic pyruvate is deviated to lactate production, little of the remaining carbons enter a truncated Krebs cycle where citrate is preferentially extruded to the cytosol where it feeds sterol synthesis. Glutamine is the major oxidizable substrate by tumor cells. Inside the mitochondrion, it is deaminated to glutamate through a phosphate-dependent glutaminase. Glutamate is then preferentially transaminated to alpha-ketoglutarate that enters the Krebs cycle. Glutamine may be completely oxidized through the abnormal Krebs cycle only if a way of forming acetyl CoA is present: cytosolic malate entering mitochondria is preferentially oxidized to pyruvate + CO2 through an intramitochondrial NAD(P)(+)-malic enzyme, whereas intramitochondrial malate is preferentially oxidized to oxaloacetate through malate dehydrogenase, thus providing a high level of intramitochondrial substrate compartmentation. These and other regulatory aberrations in tumor cells appear to be reflections of a complex set of non-random phenotypic changes, initiated by expression of oncogenes.     

Simultaneous knock-down of Bcl-xL and Mcl-1 induces apoptosis through Bax activation in pancreatic cancer cells

Anti-apoptotic Bcl-2 family proteins have been reported to play an important role in apoptotic cell death of human malignancies. The aim of this study was to delineate the mechanism of anti-apoptotic Bcl-2 family proteins in pancreatic cancer (PaCa) cell survival. We first analyzed the endogenous expression and subcellular localization of anti-apoptotic Bcl-2 family proteins in six PaCa cell lines by Western blot. To delineate the functional role of Bcl-2 family proteins, siRNA-mediated knock-down of protein expression was used. Apoptosis was measured by Cell Death ELISA and Hoechst 33258 staining. In the results, the expression of anti-apoptotic Bcl-2 family proteins varied between PaCa cell lines. Mcl-1 knock-down resulted in marked cleavage of PARP and induction of apoptosis. Down-regulation of Bcl-2 or Bcl-xL had a much weaker effect. Simultaneous knock-down of Bcl-xL and Mcl-1 strongly induced apoptosis, but simultaneous knock-down of Bcl-xL/Bcl-2 or Mcl-1/Bcl-2 had no additive effect. The apoptosis-inducing effect of simultaneous knock-down of Bcl-xL and Mcl-1 was associated with translocation of Bax from the cytosol to the mitochondrial membrane, cytochrome c release, and caspase activation. These results demonstrated that Bcl-xL and Mcl-1 play an important role in pancreatic cancer cell survival. Targeting both Bcl-xL and Mcl-1 may be an intriguing therapeutic strategy in PaCa.     

Synthetic retinoid CD437 induces mitochondria-mediated apoptosis in hepatocellular carcinoma cells

Retinoids play an important role in the regulation of cell growth and death. Synthetic retinoid CD437 reportedly induces apoptosis in various cancer cell lines. However, the mechanism of inducing apoptosis in hepatocellular carcinoma (HCC) cells by this agent remains to be clarified. In this study, we investigated the signaling pathway by which CD437 induces apoptosis in HCC cell lines. Apoptosis of six human HCC cell lines was induced by treatment with CD437. Caspase-3 and -9 were activated by CD437, suggesting that the apoptosis is mediated by mitochondrial pathways. Consistent with these findings, the treatment with CD437 upregulated Bax protein, downregulated Bcl-2 protein and released cytochrome c into the cytoplasm. Moreover, rhodamine123 staining revealed mitochondrial depolarization in the cells treated with CD437. These data of the present study suggest that CD437 induces apoptosis in HCC cells via mitochondrial pathways.     

Synthetic retinoid CD437 induces apoptosis and acts synergistically with TRAIL receptor-2 agonist in malignant melanoma

The novel synthetic retinoid, CD437, shows potent anti-tumor activity in a range of different cancer cell lines and now serves as a prototype for development of new retinoid related molecules (RRMs). The purpose of this study was to examine the effect and cellular targets of CD437 in the human metastatic melanoma cell lines FEMX-1 and WM239. We showed that treatment with CD437 led to cell cycle arrest and induced apoptosis through both the extrinsic- and intrinsic pathways (caspase 8, -9 and PARP cleavage) in both cell lines. Interestingly, apoptosis was induced independently of DNA-fragmentation in FEMX-1 cells, and appeared partially caspase-independent in the WM239 cells. Additionally, up-regulation of CHOP mRNA and cathepsin D protein expression, following retinoid treatment, suggests involvement of the endoplasmatic reticulum (ER) and lysosomes, respectively. Combination of suboptimal concentrations of CD437 and lexatumumab, a TRAIL death receptor-2 agonist, resulted in synergistic reduction of viable cells, along with increased PARP cleavage. These results indicate that CD437 has a strong anti-neoplastic effect alone and in combination with lexatumumab in melanoma cell lines.     

Targeting elongation factor-2 kinase (eEF-2K) induces apoptosis in human pancreatic cancer cells

Pancreatic cancer (PaCa) is one of the most aggressive, apoptosis-resistant and currently incurable cancers with a poor survival rate. Eukaryotic elongation factor-2 kinase (eEF-2K) is an atypical kinase, whose role in PaCa survival is not yet known. Here, we show that eEF-2K is overexpressed in PaCa cells and its down-regulation induces apoptotic cell death. Rottlerin (ROT), a polyphenolic compound initially identified as a PKC-δ inhibitor, induces apoptosis and autophagy in a variety of cancer cells including PaCa cells. We demonstrated that ROT induces intrinsic apoptosis, with dissipation of mitochondrial membrane potential (ΔΨm), and stimulates extrinsic apoptosis with concomitant induction of TNF-related apoptosis inducing ligand (TRAIL) receptors, DR4 and DR5, with caspase-8 activation, in PANC-1 and MIAPaCa-2 cells. Notably, while none of these effects were dependent on PKC-δ inhibition, ROT down-regulates eEF-2K at mRNA level, and induce eEF-2K protein degradation through ubiquitin–proteasome pathway. Down-regulation of eEF-2K recapitulates the events observed after ROT treatment, while its over-expression suppressed the ROT-induced apoptosis. Furthermore, eEF-2K regulates the expression of tissue transglutaminase (TG2), an enzyme previously implicated in proliferation, drug resistance and survival of cancer cells. Inhibition of eEF-2K/TG2 axis leads to caspase-independent apoptosis which is associated with induction of apoptosis-inducing factor (AIF). Collectively, these results indicate, for the first time, that the down-regulation of eEF-2K leads to induction of intrinsic, extrinsic as well as AIF-dependent apoptosis in PaCa cells, suggesting that eEF-2K may represent an attractive therapeutic target for the future anticancer agents in PaCa.     

BAF45D knockdown decreases cell viability,inhibits colony formation,induces cell apoptosis and S-phase arrest in human pancreatic cancer cells

ABSTRACT

Pancreatic cancer, an extremely aggressive malignancy, is resistant to chemo- or radiotherapy. The rapid progression of pancreatic cancer without distinctive clinical sign makes early diagnosing and/or treating very difficult. BAF45D, a member of the d4 domain family, is involved in oncogenic processes. However, the role of BAF45D in pancreatic tumorigenesis is largely unclear. Our goal is to examine BAF45D protein expression after lentivirus-mediated Baf45d RNAi and explore the effects of BAF45D knockdown on cell proliferation, cell apoptosis, and cell cycle of human pancreatic cancer cells. Here our results showed that Baf45d RNAi downregulated BAF45D protein levels and decreased cell viability, increased cell apoptosis, and decreased colony formation in BxPC-3 cells. Moreover, BAF45D knockdown induced S-phase arrest in BxPC-3 cells. Our results here suggest that BAF45D may play a crucial role in tumorigenic properties of human pancreatic cancer cells.     

Peroxisome proliferator-activated receptor gamma induces pancreatic cancer cell apoptosis

Peroxisome proliferator-activated receptor gamma (PPAR-gamma) decreases the growth of certain cancer cells. In the present study, we found that six different human pancreatic cancer cell lines (AsPC-1, BxPC-3, Capan-2, HPAF-II, MIA PaCa-2, and PANC-1) expressed PPAR-gamma m-RNA and synthesized the protein. The endogenous and exogenous PPAR-gamma ligands 15-deoxy-d12,14-prostaglandin J(2) (15-PGJ(2)) and ciglitazone decreased cell number, cell viability, and increased floating/attached ratio, in a time- and dose-dependent fashion. 15-PGJ(2) increased intracellular nucleosome concentration after 6 h, but did not increase caspase-3 activity even after 96 h. Combined treatment with both 15-PGJ(2) and the caspase-3 inhibitor DEVD-CHO had no effect on cell viability, but the general caspase inhibitor ZVAD-FMK reduced 15-PGJ(2)-induced apoptosis. We concluded that the six human pancreatic cancer cells tested all expressed PPAR-gamma receptor, and treatment with PPAR-gamma agonists decreased cell viability and growth in a time- and dose-dependent manner. These effects were partially mediated by induction of caspase-3 independent apoptosis.