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A resistant non-small cell lung carcinoma cell line-NSCLC (NCI-H460/R) was established in order to investigate the potential of sulfinosine (SF) to overcome multidrug resistance (MDR). The cytotoxicity of doxorubicin (DOX) in NCI-H460/R cells was enhanced by interaction with SF. SF improved the sensitivity of resistant cells to DOX when NCI-H460/R cells were pretreated with SF. Synergism was accompanied by the accumulation of cells in S and G(2)/M phases. Pretreatment with SF was more potent in improving the sensitivity to DOX than verapamil (VER). The decrease of mdr1 and topo II alpha expression (assessed by RT-PCR), was consistent with the DOX accumulation assay and cell cycle analysis. Also, SF significantly decreased intracellular glutathione (GSH) concentration. These results point to SF as a potential agent of MDR reversal and a valuable drug for improving chemotherapy of NSCLC.

p16 and PTEN are tumor suppressors that are commonly inactivated in human cancers. Loss of each of these molecules is widely studied in lung cancer, including non-small cell lung carcinoma (NSCLC), its most common clinical form. However, the importance of their mutual alterations for NSCLC pathogenesis has been barely examined so far. In this study we tested hypothesis that aberrant p16 might cooperate with inactive PTEN during pathogenesis of NSCLC, particularly in promoting tumor aggressiveness and invasiveness. Initially, we screened NSCLC tumor samples from patients for the presence of the most common genetic and epigenetic alterations of p16 and further correlated them with previously detected aberrations in PTEN gene. Statistical analyses showed that aberrant p16 directly correlated with altered PTEN. Such significant correlation was also observed in groups of patients with high genomic instability, with squamocellular histological subtype, with disease grade 2 and with lymph node invasion. Finally, survival analyses revealed dramatic decrease in survival rate of patients with mutual alterations of p16 and PTEN, but without prognostic significance. Overall results implicate cooperation between aberrant p16 and PTEN in pathogenesis of NSCLC and suggest that their combination might be considered as potential molecular marker for specific subgroups of NSCLC patients.