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Background: We recently showed that the mRNA levels of mismatch repair (MMR) proteins in non-small cell lung carcinoma (NSCLC) tissue specimens and the phenotypic translation of molecular MMR data refines the biology of the MMR system with consequent diagnostic implications in the clinical assessment of lung cancer patients., Methods: hMLH1 and hMSH2 mRNA expression was previously evaluated by qPCR for 29 NSCLC patients (13 with squamous cell carcinoma [SQC] and 16 with adenocarcinoma [ADC]) and MMR mRNA levels were converted into clinically distinct phenotypic entities. In this study, we evaluated the correlation of the hMSH2 and hMLH1 mRNA phenotypes with patient survival and their response to adjuvant chemotherapy., Results: hMSH2 and hMLH1 mRNA phenotypic distribution differed between SQC and ADC. The MMR phenotypes differed also between advanced and early stage SQC. SQC patients with an increased hMSH2 expression had a better outcome than patients with a reduced hMSH2 expression. However, ADC patients with an increased hMSH2 expression had a poor outcome compared to those with low hMSH2 levels. SQC patients with a high hMSH2 expression exhibited a better response to adjuvant chemotherapy, whereas ADC patients with high hMSH2 levels had a poor response. ADC patients with low hMSH2 levels showed good response to adjuvant chemotherapy compared to SQC patients bearing the same phenotypic profile., Conclusions: Our findings show that MMR mRNA phenotypes may be added to the known biological differences between SQC and ADC. hMLH1 and hMSH2 phenotypes distributed differently according to the NSCLC stage. Distinct MMR mRNA phenotypes in SQC and ADC corresponded to patient response to adjuvant chemotherapy.

Background: The expression of indoleamine 2,3-dioxygenase (IDO) by tumor cells has been considered as a major tumor immune escape mechanism. The aim of this study was to investigate the expression of IDO in lung cancer cell lines as well as in surgically resected lung cancer specimens comparing the latter, to the expression in autologous samples from the corresponding non malignant lung tissue. Correlations of IDO expression with clinicopathological parameters of the disease were performed., Methods: Nine human lung cancer cell lines and 28 patients with various types of primary lung cancer were enrolled in the study. IDO expression was determined by quantitative real-time PCR using a sample of lung hamartoma as reference., Results: IDO expression was detected in all but three patients' tumor samples, in all but four autologous non malignant lung tissues and in three out of the nine cell lines that were examined. The relative expression of IDO in lung cancer cell lines (4.7 +/- 11.1) was significantly lower than that of all patients' tumor samples (p = 0.006) as well as than that of the autologous non affected lung tissues (p = 0.027). No statistically significant differences were noted between ADC and SCC regarding either the tumor samples or the autologous non affected samples. No significant correlations between IDO expression and clinicopathological parameters were found., Conclusion: Direct evidence is provided demonstrating that IDO mRNA can be constitutively expressed by lung cancer cells. The higher IDO expression observed in patients' samples can be attributed to the production of the enzyme by other cells recruited in the tumor microenvironment and the peri-tumoral lung area and/or to its induction by soluble factors of tumor origin.