Correlation of Elevated mRNA Expression of p53 Gene and Repair Genes with Lung Cancer Chemoresistance

Abstract

肺癌是國人最重要的為癌致死原因，大部分接受放射線治療及化學治療的肺癌患者，常常因產生抗性而治療失敗，因此了解癌細胞抗藥性之機制對於發展更有效的治療將有莫大的幫助。已有文獻指出p53抑癌基因與數種DNA修補基因其mRNA表現增加與癌症病人化療抗藥性具有正相關，所以本研究以定量同步反轉錄聚合酵素反應(quantitative multiplex reverse transcription-polymerase chain reaction) 同時檢測p53抑癌基因與四種DNA修補基因XPCC，hMSH2，XRCCl，與ERCCl的表現量；為了暸解這些基因的mRNA表現是否能作為肺癌病人治療效果的監控指標，此定量同步反轉錄聚合酵素分析，以12位具有化療抗藥性的肺癌病人與11位治療有效的病人作比較分析。在改良過的定量同步反轉錄聚合酵素反應中，顯示p53抑癌基因與四種修補基因分別在放大26-32與30-34個循環數時，會呈現線性關係，因此利用此反應條件，分析肺癌病人之p53抑癌基因與四種修補基因mRNA的表現量與抗藥性的相關性。結是顯示，具化療抗藥性的病人其p53抑癌基因的平均表現量為0.65肘，化療無效的病人為0.28，此差異有接近顯著的統計分析趨勢(P=0.07)。本研究結果推測，p53基因的mRNA表現量的提高或許可以成為肺癌病人化療抗藥性的預測指標。

Lung cancer is the leading cause of cancer death in Taiwan. In the chemotherapeutic modalities used to treat the lung cancer, the great majority of patients will relapse with tumor that is largely resistant to further treatment. In addition, clinical and experimental studies suggest that alteration of the expression level of the p53 gene and repair genes may be associated with chemoresistance. Therefore, we evaluated the differences in the expression levels of p53 gene and four repair genes, including XPCC, hMSH2, XRCC1, and ERCCI, in 12 chemo-resistant lung cancer patients and 11 chemo-sensitive lung cancer patients using an optimized quantitative multiplex reverse transcriptase-polymerase chain reaction (RT-PCR). The modification experiments of the quantitative multiplex RT-PCR showed that amplification was linear between 26-32 cycles and 30-34 cycles for the analyses of the p53 gene and repair genes, respectively. We used this optimized quantitative multiplex RT-PCR to analyze the correlation of mRNA expression of the p53 gene and the repair genes with chemo-resistance of lung cancer. The data indicated that the mean mRNA level of the p53 gene in chemo-resistant patients (0.65) was 132.1 % higher than that of the chemo-sensitive patients (0.28). The chemo-resistant cases had an almost significantly higher (P=0.07) mean expression level of the p53 gene than did the effective cases. Our results suggest that an elevated p53 mRNA level may predict the chemoresistance of lung cancer patients.