Effect of Grape Seed Procyanidins Combined with Allicin on Lipid Levels in Hyperlipidemic Rats.

OBJECTIVES: To study the effects of grape seed proanthocyanidins (GSP) combined with allicin on serum lipids level and vascular damage in a rat model of hyperlipidemia. MATERIALS AND METHODS: SD rats(male, 170-220 gn= 40) were randomized into five groups (n = 8/group): modelhigh fat and cholesterol diet; controlnormal diet; model+low-dose (GSP+allicin )(GSP 45mg/kg, allicin 30mg/kg, orally); model+high-dose (GSP+allicin) (GSP180mg/kg, allicin 90mg/kg, orally) and positive control (model+simvastatin (4 mg/kg)). Normal control group was fed conventionally, and remaining four groups were fed high cholesterol and fat food to replicate the high fat model. After 9 weeks, the normal control group continued to receive regular feeding, while the other groups continued to receive high-fat feeding. At the same time, model and normal control groups were given equal volume of physiological saline by gavage, and the other treatment groups began to receive corresponding drugs by gavage once a day. After 4 weeks, serum levels of total cholesterol (TC), triglyceride (TG), low density lipoprotein cholesterol (LDL-C) as well as high-density lipoprotein cholesterol (HDL-C) in rats were determined. And the body weight of rat, total antioxidant capacity (T-AOC), superoxide dismutase (SOD) and malondialdehyde (MDA)in serum were identified. The level of endothelin-1(ET-1) was quantitative analysis by ELISA assay. RESULTS: In comparison to normal controls, the model group displayed a marked rise in body weight, an increment in serum concentrations of LDL-C, TG and TC, as well as a decline in HDL (P<0.01), demonstrating successful model replication; All doses of GSP in combination with allicin resulted in a reduction in TG, LDL-C, and TC and an enhancement in HDL-C in contrast to the model control (all P<0.05). High-dose (GSP+allicin ) decreased MDA, and increased T-AOC and SOD activity(all P<0.01). All doses of GSP combined with allicin decreased ET-1 (all P<0.05). In addition, the protective effect of GSP combined with allicin was dose-dependent. CONCLUSIONS: Studies have shown that GSP combined with allicin can significantly improve blood lipids in hyperlipidemic rats, and this mechanism may be related to antioxidants and reduced endothelial damage.

Xc- inhibitor sulfasalazine sensitizes colorectal cancer to cisplatin by a GSH-dependent mechanism.

Sulfasalazine (SSZ) is an anti-inflammatory drug that has been demonstrated to induce apoptosis and tumor regression through inhibition of plasma membrane cystine transporter xc(-). Cysteine is a rate-limiting precursor for intracellular glutathione (GSH) synthesis, which is vital for compound detoxification and maintaining redox balance. Platinum-based chemotherapy is an important regimen used in clinics for various cancers including colorectal cancer (CRC). We hypothesized that targeting xc(-) transporter by SSZ may annihilate cellular detoxification through interruption of GSH synthesis and may enhance the anti-cancer activity of cisplatin (CDDP) by increasing drug transport. In the present study, we revealed that xCT, the active subunit of xc(-), is highly expressed in CRC cell lines and human colorectal carcinoma tissues compared with their normal counterparts. SSZ effectively depleted cellular GSH, leading to significant accumulation of reactive oxygen species and growth inhibition in CRC cells. In contrast, the normal epithelial cells of colon origin were less sensitive to SSZ, showing a moderate ROS elevation. Importantly, SSZ effectively enhanced the intracellular platinum level and cytotoxicity of CDDP in CRC cells. The synergistic effect of SSZ and CDDP was reversed by antioxidant N-acetyl-L-cysteine (NAC). Together, these results suggest that SSZ, a relatively non-toxic drug that targets cystine transporter, may, in combination with CDDP, have effective therapy for colorectal cancer.

Identification of NDUFAF1 in mediating K-Ras induced mitochondrial dysfunction by a proteomic screening approach.

Increase in aerobic glycolysis and mitochondrial dysfunction are important biochemical features observed in human cancers. Recent studies suggest oncogenic K-Ras can cause suppression of mitochondrial respiration and up-regulation of glycolytic activity through a yet unknown mechanism. Here we employed proteomic approach and used a K-RasG12V inducible cell system to investigate the impact of oncogenic K-Ras on mitochondria and cell metabolism. Mitochondria isolated from cells before and after K-Ras induction were subjected to protein analysis using stable isotope labeling with amino acids (SILAC) and liquid chromatography coupled with mass spectrometry (LC-MS). 70 mitochondrial proteins with significant expression alteration after K-Ras induction were identified. A majority of these proteins were involved in energy metabolism. Five proteins with significant decrease belong to mitochondrial respiratory chain complex I. NADH dehydrogenase 1 alpha subcomplex assembly factor 1 (NDUFAF1) showed most significant decrease by 50%. Such decrease was validated in primary human pancreatic cancer tissues. Knockdown of NDUFAF1 by siRNA caused mitochondrial respiration deficiency, accumulation of NADH and subsequent increase of glycolytic activity. Our study revealed that oncogenic K-Ras is able to induce significant alterations in mitochondrial protein expression, and identified NDUFAF1 as an important molecule whose low expression contributes to mitochondrial dysfunction induced by K-Ras.

Micro-RNA-155 is induced by K-Ras oncogenic signal and promotes ROS stress in pancreatic cancer.

The oncogenic K-Ras can transform various mammalian cells and plays a critical role in development of pancreatic cancer. MicroRNAs (miRNA) have been shown to contribute to tumorigenic progression. However, the nature of miRNAs involved in K-Ras transformation remains to be investigated. Here, by using microarray we identified miR-155 as the most upregulated miRNA after both acute and prolonged activation of K-Ras in a doxycyline-inducible system. Pharmacological inhibition of MAPK and NF-κB pathway blocked the induction of miR-155 in response to K-Ras activation. Overexpression of miR-155 caused inhibition of Foxo3a, leading to decrease of major antioxidants including SOD2 and catalase, and enhanced pancreatic cell proliferation induced by ROS generation. Importantly, correlations of K-Ras, miR-155 and Foxo3a were also validated in human pancreatic cancer tissues. Therefore, we propose that miR-155 plays an important role in oncogenic K-Ras transformation mediated by cellular redox regulation.