Involvement of endoplasmic reticulum stress in capsaicin-induced apoptosis of human pancreatic cancer cells.

Capsaicin, main pungent ingredient of hot chilli peppers, has been shown to have anticarcinogenic effect on various cancer cells through multiple mechanisms. In this study, we investigated the apoptotic effect of capsaicin on human pancreatic cancer cells in both in vitro and in vivo systems, as well as the possible mechanisms involved. In vitro, treatment of both the pancreatic cancer cells (PANC-1 and SW1990) with capsaicin resulted in cells growth inhibition, G0/G1 phase arrest, and apoptosis in a dose-dependent manner. Knockdown of growth arrest- and DNA damage-inducible gene 153 (GADD153), a marker of the endoplasmic-reticulum-stress- (ERS-) mediated apoptosis pathway, by specific siRNA attenuated capsaicin-induced apoptosis both in PANC-1 and SW1990 cells. Moreover, in vivo studies capsaicin effectively inhibited the growth and metabolism of pancreatic cancer and prolonged the survival time of pancreatic cancer xenograft tumor-induced mice. Furthermore, capsaicin increased the expression of some key ERS markers, including glucose-regulated protein 78 (GRP78), phosphoprotein kinase-like endoplasmic reticulum kinase (phosphoPERK), and phosphoeukaryotic initiation factor-2 α (phospho-eIF2 α ), activating transcription factor 4 (ATF4) and GADD153 in tumor tissues. In conclusion, we for the first time provide important evidence to support the involvement of ERS in the induction of apoptosis in pancreatic cancer cells by capsaicin.

Emodin induces Panc-1 cell apoptosis via declining the mitochondrial membrane potential.

In this study, we investigated the apoptotic effect of emodin on human pancreatic cancer cell line Panc-1 in vitro and in vivo as well as the possible mechanisms involved. In vitro, human pancreatic cancer cell line Panc-1 was exposed to varying concentrations of emodin (0, 10, 20, 40 or 80 µmol/l). Then the mitochondrial membrane potential (MMP) was analyzed by JC-1 staining, cell apoptosis was analyzed by flow cytometry (FCM) and cell proliferation was analyzed by MTT. In vivo, nude mice orthotopically implanted were randomly divided into five groups to receive treatments by different doses of emodin: control group (normal saline 0.2 ml), E10 group (emodin 10 mg/kg), E20 group (emodin 20 mg/kg), E40 group (emodin 40 mg/kg) and E80 group (emodin 80 mg/kg). Each mouse was treated 5 times by intraperitoneal injection of emodin every 3 days. During the treatment, the feeding stuff was recorded. One week after the last treatment, we recorded the body weight and the maximum diameter of tumor in each group before the mice were sacrificed. Then the cell apoptosis of the tumor was tested by TUNEL assay. The results in vitro showed that the MMP of the cells declined and the apoptosis rate increased with the emodin concentration increasing and the cell proliferation of each group was inhibited in a dose- and time-dependent manner by emodin. The feeding stuff curve did not decline significantly in E40 group and the apoptosis rate of the tumor cells in this group was higher than the lower-dose groups. Taken together, our results demonstrate that emodin may induce the pancreatic cancer cell apoptosis via declining the MMP and a moderate dose of emodin improved the living state of the model mice.

Effect of emodin in suppressing acute rejection following liver allograft transplantation in rats.

OBJECTIVE: To investigate the mechanism of action of emodin for suppressing acute allograft rejection in a rat model of liver transplantation. METHODS: Brown Norway (BW) recipient rats of orthotopic liver transplantation (OLT) were divided into three groups, Group A receiving isografting (with BW rats as donor), Group B receiving allografting (with Lewis rats as donor), Group C receiving allografting and emodin treatment (50 mg/kg daily). They were sacrificed on day 7 of post-transplantation, and their hepatic histology, plasma cytokine levels, and T-cell subset expression were detected. RESULTS: Compared with those in Group A, rats: in Group B exhibited severe allograft rejection with a rejection activity index (RAI) of 7.67+/-0.98, extensive hepatocellular apoptosis with an apoptosis index (AI) of 35.83+/-2.32, and elevated plasma levels of interleukin-2 (IL-2), interleukin-10 (IL-10), tumor necrosis factor-alpha (TNF-alpha), CD4(+) and CD4 CD4(+)/CD8(+) ratio. However, recipients in Group C showed a decrease in histological grade of rejection and hepatocellular apoptosis, as well as a decrease in plasma levels of IL-2, TNF-alpha, CD4(+) and CD4(+)/CD8(+) ratio, but elevated levels of IL-10 as compared with the allograft group. CONCLUSION: Post-OLT acute rejection could be attenuated by emodin, its mechanism of action may be associated with protecting hepatocytes from apoptosis, polarizing the Th 1 paradigm to Th2, and inhibiting the proliferation of CD4(+) T cell in plasma.