Evaluation of the relationship between the IL-17A gene expression level and regulatory miRNA-9 in relation to tumor progression in patients with non-small cell lung cancer: a pilot study

A pro-inflammatory cytokine, IL-17A, is associated with increased risk of developing numerous cancers, including non-small cell lung cancer (NSCLC). IL-17A is a target gene for miR-9. This encouraged us to analyze these two genes in terms of their usefulness as prognostic markers in NSCLC. The expression levels of IL-17A gene and miR-9 was assessed in 26 NSCLC tissue samples and 26 unchanged lung tissue adjacent to lung tumors (control tissue), using qPCR. In both tissue groups, a decreased expression of IL-17A was observed in 100% of samples. Increased expression of miRNA-9 was observed in 92% of tumor samples, and in 100% of control samples. Neither statistical differences in the level of expression IL-17A depending on the patient's age, gender, smoking status, nor histopathology of the cancer was found. Regarding the presence of nodule metastasis ('N' value in TNM classification), significantly lower expression level of IL-17A was observed in cN2 as compared with cN1 group. Additionally, statistically lower IL-17A expression was found in III versus II tumor stage (cAJCC classification). Significant negative correlation between both studied genes was revealed in SCC subgroup. This leads to the conclusion that miRNA-9 can regulate the expression of IL-17A as an IL-17A mRNA antagonistic mediator. Inhibition of proinflammatory action of IL-17A in correlation with tumor progression can be related to various activity of Th17 cells on cancer development according to its immunogenicity, and also may suggest suppressive role of IL-17A in tumor progression. However, because of low number of analyzed samples, further studies on the functional role of IL-17A in development and/or progression NSCLC seem warranted.