Notes on Recurrence and Second Tumors in Lung Cancer

Role of LASP-1, a novel SOX9 transcriptional target, in the progression of lung cancer

Lung cancer accounts for most cancer-related deaths worldwide. However, the underlying mechanism by which it mediates the progression of lung cancer remains unclear. Expression of LASP-1 (LIM and SH3 protein 1) was evaluated in lung cancer tissues and tumor-adjacent normal tissues using immunohistochemistry and western blotting. Functional studies have shown that siRNA-mediated silencing of LASP-1 in human lung cancer cells and reduced cell proliferation, migration, and invasion. Flow cytometry and immunofluorescence staining also revealed that rate of cell apoptosis was increased after knockdown of expression of LASP-1, thereby suggesting that LASP-1 may function as an oncogene during lung cancer progression. SOX9 is an important transcription factor, which is involved in the development of several types of human cancer. Further analysis has showed the presence of a consensus-binding site of SOX9 in the promoter region of LASP-1. Mechanistic investigations showed that LASP-1 was transcriptionally activated by SOX9. Through luciferase reporter and ChIP assays, we demonstrated that LASP-1 was a direct target gene of sex determining region Y-box 9 (SOX9). Knockdown of SOX9 expression by RNA interference reduces cell proliferation and induces apoptosis of lung cancer cells, which was consistent with the results obtained from silencing the expression of LASP-1 in NCI‑H1650 cells. Together, these findings indicated that LASP-1, as a downstream target of SOX9, may act as a novel biomarker for lung cancer and plays an important role in cell proliferation, migration, and invasion.

Relationships between chronic obstructive pulmonary disease and lung cancer: biological insights

Lung cancer (LC) has become one of the leading causes of preventable death in the last few decades. Cigarette smoking (CS) stays as the main etiologic factor of LC despite that many other causes such as occupational exposures, air pollution, asbestos, or radiation have also been implicated. Patients with chronic obstructive pulmonary disease (COPD), which also represents a major cause of morbidity and mortality in developed countries, exhibit a significantly greater risk of LC. The study of the underlying biological mechanisms that may predispose patients with chronic respiratory diseases to a higher incidence of LC has also gained much attention in the last few years. The present review has been divided into three major sections in which different aspects have been addressed: (I) relevant etiologic agents of LC; (II) studies confirming the hypothesis that COPD patients are exposed to a greater risk of developing LC; and (III) evidence on the most relevant underlying biological mechanisms that support the links between COPD and LC. Several carcinogenic agents have been described in the last decades but CS remains to be the leading etiologic agent in most geographical regions in which the incidence of LC is very high. Growing evidence has put the line forward the implications of COPD and especially of emphysema in LC development. Hence, COPD represents a major risk factor of LC in patients. Different avenues of research have demonstrated the presence of relevant biological mechanisms that may predispose COPD patients to develop LC. Importantly, the so far identified biological mechanisms offer targets for the design of specific therapeutic strategies that will further the current treatment options for patients with LC. Prospective screening studies, in which patients with COPD should be followed up for several years will help identify biomarkers that may predict the risk of LC among these patients.