Influence On NF-κB P65 And ASPP2 Of Murine Lewis Lung Cancer Of NF-кB Inhibitor PDTC And Cisplatin

Backgrounds and Objective:Chemotherapy is major therapy for advanced lung cancer and limited by chemoresistance and severe toxic reaction. There are prominent requirement for new drugs and drug combination to enhance antitumor effects of existing antitumor drugs. Nuclear factor-κB (NF-κB) is an important transcription factors involved in the regulation of proliferation,survival and apoptosis, immune and inflammatory reaction and cancer metastasis. Antioxidant pyrrolidine dithiocarbamate( PDTC)inhibits NF-κB activity by means of reducing degradation of inhibitor ofκB and nuclear translocation of p65/Rel A. In vitro antitumor effect of PDTC was reported. In vivo effects of PDTC on lung cancer and its mechanisms are to be investigated. Cisplatin (CDDP) is one of cytotoxic chemotherapeutic agents with potent antitumor effect and severe nephrotoxicity. In the test cells mice were inoculated with Lewis lung cancer and treated with PDTC, CDDP only or combined intratumor administration. Their antitumor effect was appraised by decrease in tumor volume and weight on indicated point. NF-κB P65 and ASPP2 expression in tumor and kidneys of treated and control mice with Lewis lung cancer were measured with immunohistochemical staining techniques. The purpose of the experiment was to implore whether PDTC may be used to potentiate the antitumor effect and alleviate the nephrotoxicity of CDDP.Methods:32 healthy SPF C57BL/6 mice (body weight was in 18-22g) were randomized into 4 groups. They were inoculated subcutaneously with 1×107 Lewis lung cancer cells. A week later they were treated daily with intratumoral injection of normal saline (NS), PDTC, CDDP or combined injection of PDTC and CDDP for 15 days. General condition of all mice was observed. Changes in tumor volume were measured on day 5, 10 and 15 after therapy. Mice were killed and dissected on day 16 after therapy. Their tumor and kidneys were weighted and sampled. The expression of NF-κB p65 and ASPP2 were assayed with immunohistochemical method. The date was analyzed with SPSS11.5.1. Inhibitory effects on growth of Lewis lung cancer of PDTC and CDDP: On day 5 tumor volume of mice injected with NS was 1.701±0.749 cm3. The tumor volume in treatment groups was lower than that of NS group, difference between PDTC plus CDDP group ( 0.981±0.403 cm3) and NS group was significant statistically(P<0.05)。The tumor volume of CDDP group and PDTC plus CDDP group on day10 and 15 was lower than that of NS group(P<0.05)。Tumor weight of NS group was 5.913±1.153g,that of PDTC group was 3.519±1.008g (p>0.05), that of CDDP group was 1.900±1.233g,that of PDTC plus CDDP was 1.825±0.616g,The difference between the two groups and NS group was significant statistically(P<0.05), the difference between them was not.2. Influence on NF-κB P65 expression of Lewis lung cancer of PDTC and CDDP: Tumor tissues injected with NS expressed highly NF-κB P65, stained particles in cells and positive cells in tumor were the most among groups. PDTC and CDDP treatment decreased the ratio of the positive cells and color of stained particles. Stained particles in cells and positive cells in tumor treated with PDTC plus CDDP were the least among groups.3. Influence on ASPP2 expression of Lewis lung cancer of PDTC and CDDP: No or low ASPP2 expression was common in tumor samples injected with NS. PDTC or CDDP treatment induced ASPP2 expression; their combination produced synergetic effects in inducing ASPP2 expression.4. Influence on NF-κB P65 expression of kidneys of PDTC and CDDP:Less or no NF-κB P65 positive renal tubular cells were seen in kidney samples of mice treated with NS, NF-κB P65 positive cells did not increased significantly in kidneys of mice treated with PDTC. In kidneys of mice treated with CDDP a lot of stained highly NF-κB P65 positive cells were found in renal tubules, less interstitial cell was NF-κB P65 positive cells. In kidneys of mice treated with CDDP plus PDTC NF-κB P65 positive cells were decreased and staining was light.5. Influence on ASPP2 expression of kidneys of PDTC and CDDP:ASPP2 positive renal tubular cells may be seen in kidney samples of mice either injected NS or test drugs. Strong positive tubular cells were significantly increased in the kidneys of mice treated with CDDP.Conclusions:1. CDDP inhibited the growth of murine Lewis lung cancer, PDTC exhibited antitumor effects on early tumor, no antitumor effects on advanced tumor. PDTC did not potentiate the antitumor effects of CDDP.2. Lewis lung cancer cells highly expressed NF-κB P65. In tumor treated with PDTC, CDDP and PDTC plus CDDP expression level of NF-κB P65 was down regulated.3. PDTC, CDDP and PDTC plus CDDP treatment induced proapoptotic ASPP2 expression.4. Kidneys expressed no or less NF-κB P65, but expressed ASPP2. CDDP treatment induced the expression of NF-κB P65 and ASPP2 in tubular cells, PDTC treatment did not changed NF-κB P65 expression of kidneys of mice and down regulated ASPP2 expression.These results showed that PDTC inhibited the NF-κB P65 expression and induced ASPP2 expression of Lewis lung cancer. PDTC exhibited anticancer effects on early tumor and no growth-inhibition effects on advanced tumor. Anticancer drugs cisplatin induced expression of NF-κB P65 and ASPP2 responsible for regulation of cell survival and apoptosis in renal tubular cells; Which was associated with nepherotoxicity of cisplatin.