Molecular mechanisms and cellular contribution from lung fibrosis to lung cancer development.

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, fibrosing interstitial lung 28 disease (ILD) of unknown etiology, with a median survival of 2-4 years from the time of diagnosis. 29 Although IPF has unknown etiology by definition, there have been identified several risks factors 30 increasing the probability of the onset and progression of the disease in IPF patients such as cigarette 31 smoking and environmental risks factors associated to domestic and occupational exposure. Among 32 them, cigarette smoking together with concomitant emphysema might predispose IPF patients to 33 lung cancer (LC), mostly to non-small cell lung cancer (NSCLC), increasing the risk of lung cancer 34 development. To this purpose, IPF and LC share several cellular and molecular processes driving 35 the progression of both pathologies such as fibroblast transition proliferation and activation, endo- 36 plasmic reticulum stress, oxidative stress, and many genetic and epigenetic markers that predispose 37 the IPF patients to LC development. Nintedanib, a tyrosine-kinase inhibitor, was firstly developed 38 as an anticancer drug and then recognized as an anti-fibrotic agent based on the common target 39 molecular pathway. In this review our aim is to describe the updated studies on common cellular 40 and molecular mechanisms between IPF and lung cancer, whose knowledge might help to find 41 novel therapeutic targets for this disease combination.