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Objective To evaluate the antitumor effect of dacarbazine (DTIC) on B16-F1 melanoma after CDK2 gene silencing.Methods Cultured B16-F1 melanoma cells were divided into 4 groups:control group receiving no treatment,CDK2-shRNA group infected with a recombinant lentivirus pUL-CDK2-shRNA,DTIC group cultured in 96-well plates followed 12 hours later by the treatment with 250 μmol/L DTIC,CDK2-shRNA + DTIC group infected with pUL-CDK2-shRNA followed 12 hours later by the treatment with 250 μmol/L DTIC.MTT assay was performed to evaluate the growth inhibition of B16-F1 melanoma cells,and coefficient of drug interaction (CDI) was calculated.AnnexinV-FITC/PI double staining was conducted to detect cell apoptosis.C57BL/6 mice were subcutaneously injected with B16-F1 cells at exponential growth phase into the right groin to establish melanoma-bearing mouse models.Twenty mouse models were randomly and equally divided into 4 groups:control mouse group injected with phosphate-buffered solution (PBS) into tumors,CDK2-shRNA mouse group injected with pUL-CDK2-shRNA into tumors,DTIC mouse group injected with DTIC into the abdominal cavity,and CDK2-shRNA + DTIC mouse group treated with pUL-CDK2-shRNA and DTIC.The animal experiment lasted 18 days,and the tumor growth curve was drawn.After 18-day treatment,all the mice were sacrificed,and tumors were isolated and weighed.The tumor growth inhibition rate was calculated,and the tumor cell apoptosis was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick-end-labeling (TUNEL).Results After 72-hour culture,compared with the control group,the CDK2-shRNA group,DTIC group,and CDK2-shRNA + DTIC group showed significantly decreased relative cell survival rates (40.6％ ± 2.8％,45.2％ ± 3.7％,28.7％ ± 2.1％,respectively;F =458.04,P ＜ 0.05),but significantly increased cell apoptosis rates (25.1％ ± 3.3％,15.6％ ± 2.2％,45.6％ ± 3.5％,respectively;F =115.46,P ＜ 0.05).Additionally,CDK2-shRNA + DTIC group showed significantly lower relative cell survival rates (P ＜ 0.01),but higher cell apoptosis rates (P ＜ 0.01) compared with the DTIC group.The CDI value was less than 0.7.On the sixth day after the in vivo treatment,the tumor volumes in the control mouse group,CDK2-shRNA mouse group,DTIC mouse group,and CDK2-shRNA + DTIC mouse group were (185.44 ± 68.97) mm3,(83.91 ± 14.33) mm3,(123.70 ± 20.85) mm3,and (34.54 ± 10.72) mm3 respectively.From then on,the CDK2-shRNA mouse group,DTIC mouse group,and CDK2-shRNA + DTIC mouse group showed significantly decreased tumor growth rates compared with the control mouse group (F =11.819,P ＜ 0.05),and the tumor growth rate was significantly lower in the CDK2-shRNA + DTIC mouse group than in the DTIC mouse group (P =0.04).The calculated tumor growth inhibition rates in the CDK2-shRNA mouse group,DTIC mouse group and CDK2-shRNA + DTIC mouse group were 52.2％,41.2％ and 86.4％ respectively.Compared with the control mouse group,the CDK2-shRNA mouse group,DTIC mouse group,and CDK2-shRNA + DTIC mouse group showed significantly increased tumor cell apoptosis indice (32.93％ ± 3.72％,21.62％ ± 3.54％,63.29％ ± 4.74％ respectively;F =222.25,P ＜ 0.05).Moreover,the tumor cell apoptosis index was significantly higher in the CDK2-shRNA + DTIC mouse group than in the DTIC mouse group (P ＜ 0.01).Conclusion CDK2 gene silencing can enhance the inhibitory effect of DTIC on the growth of melanoma,and show a synergistic effect with DTIC,likely by increasing the apoptosis of tumor cells.
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Objective To study the expression status of estrogen receptor-alpha36(ER-α36)in breast cancer tissue and its rela-tionships with the occurrence,development and clinical prognosis of breast cancer.Methods 653 cases of breast cancer tissues were selected in this study.The real-time reverse transcription polymerase chain reaction(RT-PCR)and immunohistochemistry were used to detect the expression of ER-α36,estrogen receptor-alpha66 (ER-α66),progesterone receptor(PR)and human epidermal growth factor receptor-2(Her-2).The relationships between the expression of ER-α36,ER-α66,PR and Her-2 and the pathological charac-ter were analyzed.Results The expression rate of ER-α36 in all cases was 40%.The expression rate of ER-α36 in Her-2 positive tissues(63%)was significantly higher than that in the Her-2 negative group(44%,P 0.05).The expression rate of ER-α36 in stage Ⅲ+Ⅳ breast cancer tissues(54%) was significantly higher than that in stage Ⅰ+Ⅱ breast cancer tissues(28%,P <0.05).The expression rate of ER-α36 in breast cancer tissues with lymph node metastasis (55%)was significantly higher than that in breast cancer tissues without lymph node me-tastasis (23%,P <0.05).Conclusion The results indicate that ER-α36 may play a very important role in the occurrence,develop-ment and lymph node metastasis of breast cancer,and be associated with the expression of Her-2,breast cancer staging and lymph node metastasis.ER-α36 is expected to become a new tumor marker and clinical diagnosis and treatment target.