Effects Of Gemcitabin With Erlotinib On Human Lung Cancer Cell Lines In Different Sequences Administration

Lung cancer is the leading cause of cancer death with highest incidence in our country. Comprehensive therapy has been more and more important for the treatment of lung cancer. The drugs of molecular target therapy have been widely used in clinical practice. Erlotinib is a reversible epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), which was approved in2004by the US Food and Drug Administration (FDA) for patients with advanced non small cell lung cancer. So how to make full use of EGFR-TKI, how to combine EGFR-TKI with chemotherapy is the focus area nowdays. Gemcitabine is is a cell-cycle-dependent (S-phase-specific) deoxycytidine analogue of the antimetabolite class, which can prevent DNA synthesis, thereby inducing apoptosis. Gemcitabine plus platinum is one of the standard first-line chemotherapy in non small cell lung cancer. The previous study showed different results of the different sequence addiministration effect of EGFR-TKI with chemotherapy. The aim of this study is to observe the effects of gemcitabine in combination with elotinib on human lung cancer cell lines in different sequence administration, and to evaluate the interaction between these two drugs. In addition, we tried to find possible mechanisms of the interaction in GLC-82cell line by observing the ultrastructure through electron microscopy, examining the mutation of EGFR and Kras gene by PCR and direct sequencing, detecting the expression of p-AKT and CDK2by Western blot and cell-cycle modulation and apoptosis by flow cytometry.The work described here include two parts:(1) to investigate the effects of gemcitabine in combination with elotinib on human lung cancer cell lines in different sequences administration;(2) to analyze the underlying mechanisms responsible for different antitumor effect in GLC-82cell line.The analysis of the cell growth inhibition by gemcitabine with elotinib in different sequence addiministration showed that the combination of gemcitabine and elotinib in different sequence administration had different interations. The simultaneously administration of gemcitabine and elotinib in the four human lung cancer cell lines showed synergistic effect. The sequential administration of gemcitabine and elotinib in the four human lung cancer cell lines showed different effects. Then we investigated the mechanism of synergy in GLC-82cell lines. Numerous large autophagic vacuoles presented in gefitinib-treated GLC-82cells, which probably associated with the blocking of the PI3K/Akt/mTOR signaling pathway by elotinib. The synergistic effect of the two drugs in GLC-82cell lines was observed. According to the results of western blot, we suppose that the effects of down-regulating the expression of CDK2and blocking the PI3K-PTEN-Akt signaling pathway by elotinib may play a role in the mechanism of synergistic effect of the two drugs in GLC-82cell lines.