Tumor suppressor microRNAs in lung cancer: An insight to signaling pathways and drug resistance.

Lung cancer (LC) is the second common cancer for both women and men all over the world. Unfortunately, the number of LC deaths is increasing rapidly each year so early diagnosis of LC can be lifesaving. MicroRNAs are involved in multiple processes, such as cell differentiation, transcription, inflammation, proliferation, cell signaling, and apoptosis. In LC, microRNAs function as tumor suppressors (TS) or oncogenes depending on the targets. Changes in microRNAs expression level are related to tumor initiation, progression, and metastasis. MicroRNAs can regulate gene expression and thus affect the activity status of different signaling pathways including AKT, JAK-STAT, MAPK, TGF-β, WNT, and ERK signaling pathways. Positive or negative effects on drug resistance of LC are directly affected by microRNAs and their target genes. MicroRNAs can be beneficial in combination therapy with other drugs and chemotherapeutic agents for LC.