Aberrant expression of various microRNAs (miRNA) has shown diagnostic and prognostic significance in non-small cell lung cancer (NSCLC). qRT-PCR analysis confirmed altered expression of miR-125a-5p, let-7e, miR-30a, miR-30e and miR-30e-3p in 70 paired tissue and serum samples from NSCLC patients. The reduced expression of miR-125a-5p, let-7e and miR-30e was strongly associated with NSCLC dedifferentiation. The lost expression of miR-125a-5p and let-7e was associated with shorter overall survival and let-7e was an independent prognostic factor for NSCLC patients. These five miRNA expressions should be further evaluated as biomarkers for the early detection and prognosis of NSCLC patients.
Nicotine is not only a major component in tobacco but is also a survival agonist that inhibits apoptosis induced by certain agents including chemotherapeutic drugs. Here, we first showed that nicotine inhibits cisplatin-induced apoptosis in NCI-H446 cells. An MTT assay, Annexin V-FITC staining, RT-PCR, and Western blot were applied to identify the viability of cells, stages of apoptosis, mRNA and signaling proteins expression, respectively. First, we observed that nicotine induced no significant apoptosis when used alone and promoted cell proliferation at a low concentration or for a short time, but the opposite was observed at a high concentration or for a long time. In addition, an increase in XIAP and Survivin mRNA or protein was observed. Next, when combined with cisplatin, growth inhibition rates were concentration dependent, decreased to the lowest level at first, but later climbed to the highest point. Furthermore, nicotine inhibited apoptosis induced by cisplatin and caused a concentration-dependent increase in both XIAP and Survivin mRNA or protein. Moreover, the apoptotic effect of the combination group was obviously higher than that of nicotine used alone at the same nicotine concentration and lower than that of cisplatin used alone at the same cisplatin concentration. These studies suggest that exposure to nicotine might negatively impact the apoptotic potential of chemotherapeutics.
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