XRCC2-Deficient Cells are Highly Sensitive to 5-Fluorouracil in Colorectal Cancer.

BACKGROUND/AIMS: Inhibition of the repair of 5-fluorouracil (5-FU)-induced DNA lesions may improve the responses of tumors to anticancer agents. XRCC2 is a key factor in DNA repair. However, the role of XRCC2 in the chemoresistance of colorectal cancer (CRC) treated with 5-FU remains unclear. The aim of this study is to investigate whether XRCC2 expression affects the chemosensitivity of colorectal cancer. METHODS: XRCC2 expression in CRC tissues was assessed, and the outcomes were analyzed to determine the clinical importance of XRCC2 expression. Following treatment with 5-FU, the effect of XRCC2 on proliferation was evaluated via a CCK-8 assay, the effects on cell cycle distribution and apoptosis were analyzed using flow cytometry, and γH2AX foci formation assays were performed to examine the influence of 5-FU on DNA Double-strand breaks(DSBs) repair in CRC cells. RESULTS: XRCC2 expression in CRC tissues was significantly higher than that in normal tissues, and this increased XRCC2 expression was associated with advanced T staging, M staging, TNM staging, Duke's staging, and greater liver and lymph node metastases. XRCC2 expression might be an independent prognostic indicator for CRC patients. Patients with negative XRCC2 expression exhibit greater sensitivity to treatment with 5-FU-based chemotherapy than those with positive XRCC2 expression. Moreover, our observations revealed that the knockdown of XRCC2 in CRC cells increased the sensitivities to 5-FU in terms of cell proliferation, apoptosis and cell cycle arrest. DNA DSBs repair was slower in the XRCC2-deficient cells than in the XRCC2-wild type cells. CONCLUSION: Our study demonstrated that XRCC2 might play an important role in CRC and function as a novel prognostic indicator and that the down-regulation of XRCC2 may be useful for sensitizing CRC cells during 5-FU chemotherapy.

[Preparation and Synchronized Release Behavior on Porosity Osmotic Pump Tablets of Total Glucosides of Paeony].

Objective: To prepare porosity osmotic pump tablets of total glucosides of paeony( TGP),and to study the behavior on synchronous release of its main components. Methods: Taking the accumulative release of TGP as indexes, through single-factor test and orthogonal design to investigate the optimal formulation porosity osmotic pump tablets of TGP. The main components, paeoniflorin, albiflorin and benzoylpaeoniflorin were employed to study synchronous release of the optimal formulation. Results: The membrane weight, and the content of PEG 400,and diethyl phthalate( DEP) were the main factors influencing the behavior of TGP release. The accumulated release of the prepared osmotic pump release tablets achieved about 90%. Three main components achieved the desired zero-order release profile and had a synchronized release behavior. Conclusion: The prepared porosity osmotic pump tablets of TGP can achieve the behavior of synchronized release of multi-components with good reproducibility.

[Comparison of bioavailability of two kinds of solid dispersion from 10-hydroxycamptothecin in SD rats in vivo].

To improve the bioavailability of 10-hydroxycamptothecin, 10-hydroxycamptothecin solid dispersion(HCPT-SD) and 10-hydroxycamptothecin-phospholipid complex-solid dispersion(HCPT-PC-SD) were prepared, and their solubility and dissolution rate were evaluated in this study. SD rates were administered intragastrically with HCPT-SD or HCPT-PC-SD respectively, then their blood samples were collected at different time intervals. The concentration of HCPT in blood was detected by HPLC method with camptothecin as internal standard, and then its pharmacokinetic parameters were calculated and obtained. The results showed that the Cmax, AUC0-t and AUC0-∞ of both kinds of solid dispersion of HCPT were significantly increased than those of crude drug. The AUC0-t of HCPT-SD was increased by 176.87%, and AUC0-t of HCPT-PC-SD was increased by 254.31% as compared with crude drug. Therefore, the two kinds of solid dispersion of HCPT could significantly enhance the bioavailability of HCPT in SD rates, and the effect of HCPT-PC-SD was more obvious.

[Study and Evaluation on Preparation of Monolithic Osmotic Pump Tablet of Resveratrol].

OBJECTIVE: To prepare monolithic osmotic pump tablet of resveratrol. METHODS: Inclusion technology was adopted to enhance its solubility. The optimal formulation of resveratrol inclusion complex osmotic pump tablets was selected by the single-factor method and orthogonal design. The release in vitro of the optimized formulation was also fitted to different models. RESULTS: The tablets with optimized formulation achieved the desired zero-order release profile in 12 h (r = 0.9963) with the cumulative release over 90%. CONCLUSION: Resveratrol can be prepared into monolithic osmotic pump tablets based on the intermediate of inclusion technology, which have obvious characteristic of zero release.

[Protective effect of polysaccharides extracts from corn silk against cyclophosphamide induced host damages in mice bearing H22 tumors].

OBJECTIVE: To study the protective effect of polysaccharides from corn silk (PCS) against cyclophosphamide (CTX) induced host damages in mice bearing H22 tumors. METHODS: The ascitic and solid tumor bearing mice model were established to investigate the anti-tumor effects of different dose of PCS (100, 200 and 300 mg/kg). The effects of PCS alone and with combination of CTX on tumor weight, survival time, thymus and spleen index, white blood cell, nucleated cell of marrow, serum ALT and AST level were tested. RESULTS: The high-dose PCS (300 mg/kg) had significant inhibitory effects on tumor. After combination with CTX, the tumor inhibitory ratio was enhanced to 68.71%, the survival time of tumor-burdened ascites tumor mice was significantly prolonged to 72.07% compared with CTX group. The Q value of combination group was 0.997. Thymus and spleen index, white blood cell, nucleated cell of marrow decreased by CTX were ameliorated significantly. The level of ALT and AST increased by CTX were reduced by combination with PCS. CONCLUSION: PCS has a potent inhibitory effect on the growth of implanted H22 tumors in mice and has a synergetic effect and an attenuated toxic effect in combination with CTX.