Cepharanthine hydrochloride reverses P­glycoprotein-mediated multidrug resistance in human ovarian carcinoma A2780/Taxol cells by inhibiting the PI3K/Akt signaling pathway.

Ovarian cancer has the highest mortality rate among gynecologic malignant tumors. The major obstacle to treatment success is multidrug resistance (MDR) to chemotherapy drugs. Cepharanthine hydrochloride (CH), a natural alkaloid-derived compound, has shown MDR reversal potency in several tumor cell lines; however, the molecular mechanism is not entirely known. In the present study, we assessed whether CH sensitized malignant cells to chemotherapy drugs in ovarian cancer and explored the relevant mechanism. We found that CH reduced the IC50 value of paclitaxel and increased intracellular rhodamine-123 accumulation in human ovarian cancer A2780/Taxol cells in a concentration-dependent manner. Reverse transcription polymerase chain reaction and western blot assay demonstrated that CH inhibited MDR1 expression as indicated by reduced mRNA and protein levels in A2780/Taxol cells. In addition, the inhibitory effect was strengthened after CH was combined with the specific PI3K/Akt signaling pathway inhibitor LY294002. Furthermore, p­Akt expression decreased gradually with the concentration of CH (2, 4 and 8 µM). Taken together, these findings indicated that CH reversed P­glycoprotein-mediated MDR in A2780/Taxol cells by inhibiting the PI3K/Akt signaling pathway.

Dexmedetomidine improves early postoperative cognitive dysfunction in aged mice.

Postoperative cognitive dysfunction (POCD) is a frequent complication following major surgery in the elderly. However, the exact pathogenic mechanisms are still unknown. Dexmedetomidine, a selective alpha 2 adrenal receptor agonist, was revealed anesthesia and brain protective role. The present study aimed to examine whether dexmedetomdine protects against POCD induced by major surgical trauma under general anesthesia in aged mice. In the present study, cognitive function was assessed by Y-maze. Proinflammatory cytokines interleukin-1ß (IL-1ß) and tumor necrosis factor (TNF-α), apoptosis-related factor caspase-3 and Bax were detected by real-time PCR, Western blot or immunohistochemistry. The results showed that anesthesia alone caused weak cognitive dysfunction on the first day after general anesthesia. Cognitive function in mice with splenectomy under general anesthesia was significantly exacerbated at the first and third days after surgery, and was significantly improved by dexmedetomidine administration. Splenectomy increased the expression of IL-1ß, TNF-α, Bax and caspase-3 in hippocampus. These changes were significantly inversed by dexmedetomidine. These results suggest that hippocampal inflammatory response and neuronal apoptosis may contribute to POCD, and selective alpha 2 adrenal receptor excitation play a protective role.

Azvudine, a novel nucleoside reverse transcriptase inhibitor showed good drug combination features and better inhibition on drug-resistant strains than lamivudine in vitro.

Azvudine is a novel nucleoside reverse transcriptase inhibitor with antiviral activity on human immunodeficiency virus, hepatitis B virus and hepatitis C virus. Here we reported the in vitro activity of azvudine against HIV-1 and HIV-2 when used alone or in combination with other antiretroviral drugs and its drug resistance features. Azvudine exerted highly potent inhibition on HIV-1 (EC(50)s ranging from 0.03 to 6.92 nM) and HIV-2 (EC(50)s ranging from 0.018 to 0.025 nM). It also showed synergism in combination with six approved anti-HIV drugs on both C8166 and PBMC. In combination assay, the concentrations of azvudine used were 1000 or 500 fold lower than other drugs. Azvudine also showed potent inhibition on NRTI-resistant strains (L74V and T69N). Although M184V caused 250 fold reduction in susceptibility, azvudine remained active at nanomolar range. In in vitro induced resistant assay, the frequency of M184I mutation increased with induction time which suggests M184I as the key mutation in azvudine treatment. As control, lamivudine treatment resulted in a higher frequency of M184I/V given the same induction time and higher occurrence of M184V was found. Molecular modeling analysis suggests that steric hindrance is more pronounced in mutant M184I than M184V due to the azido group of azvudine. The present data demonstrates the potential of azvudine as a complementary drug to current anti-HIV drugs. M184I should be the key mutation, however, azvudine still remains active on HIV-1LAI-M184V at nanomolar range.

[Correlation between reversing effect of cepharanthine hydrochloride on multidrug resistance and P-glycoprotein expression and function of K562/ADR cells].

In this study, cepharanthine hydrochloride (CH) was tested for its potential ability to modulate the expression and function of P-glycoprotein (P-gp) in the multidrug-resistant human chronic myelogenous leukemia cell line K562/ADR. Cytotoxicity of adriamycin (ADR) alone or in combination with CH or verapamil (VER) in K562 and K562/ADR cells was determined by MTT assay. Based on flow cytometric technology, the effect of CH or VER on the uptake and efflux of rhodamine123 (Rho123) and the accumulation of ADR in these cells was detected by measuring Rho123 or ADR-associated mean fluorescence intensity (MFI). The effects of CH and VER on P-glycoprotein (P-gp) expression in K562 and K562/ADR cells were also measured using a flow cytometry with PE-conjugated P-glycoprotein antibody. The results show that CH significantly enhanced the sensitivity of K562/ADR cells to ADR, 4 micromol x L(-1) of CH enhanced the sensitivity of K562/ADR cells to ADR by 7.43 folds, the reversal activity was 3.19 times higher than that of verapamil. However, CH had no effect on drug-sensitive K562 cells (P < 0.05). CH increased Rho123 and ADR accumulation in a concentration-dependent manner (2-8 micromol x L(-1)) and inhibited the efflux of Rho123 from these cells, but did not affect the accumulation and efflux of Rho123 from the wild-type drug-sensitive K562 cells. The inhibition effect of CH on P-gp expression in K562/ADR cells is in a time- and concentration-dependent manner. The reversal activity of CH is possibility related to inhibition of P-gp function and expression, which lead to an increased intracellular accumulation of anticancer drugs.