Gli1 Mediates Lung Cancer Cell Proliferation and Sonic Hedgehog-Dependent Mesenchymal Cell Activation

Abstract

Non-Small-Cell-Lung-Cancer (NSCLC) represents approximately 85% of all lung cancers and remains poorly understood. While signaling pathways operative during organ development, including Sonic Hedgehog (Shh) and associated Gli transcription factors (Gli1-3), have recently been found to be reactivated in NSCLC, their functional role remains unclear. Here, we hypothesized that Shh/Gli1-3 could mediate NSCLC autonomous proliferation and epithelial/stromal signaling in the tumoral tissue. In this context, we have investigated the activity of Shh/Gli1-3 signaling in NSCLC in both, cancer and stromal cells. We report here that inhibition of Shh signaling induces a significant decrease in the proliferation of NSCLC cells. This effect is mediated by Gli1 and Gli2, but not Gli3, through regulation of cyclin D1 and cyclin D2 expression. While exogenous Shh was unable to induce signaling in either A549 lung adenocarcinoma or H520 lung squamous carcinoma cells, both cells were found to secrete Shh ligand, which induced fibroblast proliferation, survival, migration, invasion, and collagen synthesis. Furthermore, Shh secreted by NSCLC mediates the production of proangiogenic and metastatic factors in lung fibroblasts. Our results thus provide evidence that Shh plays an important role in mediating epithelial/mesenchymal crosstalk in NSCLC. While autonomous Gli activity controls NSCLC proliferation, increased Shh expression by NSCLC is associated with fibroblast activation in tumor-associated stroma. Our study highlights the relevance of studying stromal-associated cells in the context of NSCLC regarding new prognosis and therapeutic options.

Screening for tumor suppressors: Loss of ephrin receptor A2 cooperates with oncogenic KRas in promoting lung adenocarcinoma

“…Oncogenic KRas or Egfr were shown to cooperate with dominant active Gli2 activation in a mouse model of pancreatic ductal adenocarcinoma (59). In human non-small cell lung cancer cell lines, knockdown of Gli1 and Gli2 affects proliferation, migration, and invasion (60). Moreover, TCGA data analysis of lung adenocarcinoma patients showed that GLI1 and KRAS copy number alterations coexist in a subset of patients (Fig.…”

Tissue remodelling in chronic bronchial diseases: from the epithelial to mesenchymal phenotype

“…Together, these data show that Hh-related molecules are highly expressed in IPF lungs, indicating an activation of the Hh pathway in this type of lung fibrosis. Moreover, in fibroblasts, Shh increases the synthesis of proteins related to ECM, such as collagen and fibronectin [112,113]. Interestingly, inhibition of the Hh pathway reduces the expression of a-SMA, collagen 1 and fibronectin and abrogates the effect of TGF-b on these proteins [111], highlighting the importance of the TGF-b/Hh crosstalk that may promote a mesenchymal phenotype in pathological contexts.…”

“…Interestingly, inhibition of the Hh pathway reduces the expression of a-SMA, collagen 1 and fibronectin and abrogates the effect of TGF-b on these proteins [111], highlighting the importance of the TGF-b/Hh crosstalk that may promote a mesenchymal phenotype in pathological contexts. In different types of lung cancer, the Shh pathway has also been found to be re-activated [99,[113][114][115][116], and is involved in the mesenchymal transition of tumoural cells associated with the formation of metastases. In a model of lung metastases, colon carcinoma cells injected into nude mice induced pulmonary lesions.…”

Fibroblasts Enhance Migration of Human Lung Cancer Cells in a Paper‐Based Coculture System

“…In the co-culture experiments, we used VXN2 (passage number [10][11][12][13][14][15][16][17][18][19] and TF (passage number 3-12) cells. After harvesting the cells from tissue cultures flasks, we labeled the VXN2 cells by cell tracker green.…”

“…[15] We suggest that this behavior could, in part, be due to the activity of the transforming growth factor-beta (TGF-beta)…”