Blocked expression of key genes of the angiogenic pathway in JSRV-induced pulmonary adenocarcinomas

Maryline Gomes,Nicolas Girard,Barbara Gineys,Fabienne Archer,Jean-François Mornex,Christine Dolmazon,Alexandra Bobet Erny,Caroline Leroux

doi:10.1186/s13567-017-0480-z

Abstract

JSRV (Jaagsiekte Sheep Retrovirus) is a retrovirus inducing a transmissible lung adenocarcinoma in sheep and goats with predominantly lepidic and papillary lesions. This naturally occurring lung cancer in large animals shares many features with human pneumonic-type lung adenocarcinomas with predominant lepidic growth. The metastatic spread is rare in both human and animal cancers. This unique feature prompted us to decipher the angiogenesis pathway in these cancers. We focused on the levels of mRNA and proteins of genes implicated in the extension of JSRV-induced lung adenocarcinomas by studying their expression in lung cancers (n = 10) and normal lungs (n = 10) and in primary epithelial alveolar type II cells derived from cancers (n = 10) or normal lungs (n = 6). In parallel, we evaluated the levels of expression of key genes in lung tissues collected from lepidic (n = 13) or papillary (n = 5) human adenocarcinomas and, when available, adjacent normal lungs (n = 11). We measured the expression of the same key genes implicated in angiogenesis, lymphangiogenesis and degradation of the extracellular matrix. In ovine adenocarcinomas, VEGFR2 and VEGFD mRNA were downregulated in cancers; MMP9, TIMP1 and FGFR2 mRNA were overexpressed as compared to normal lungs. Importantly, VEGFA and VEGFR2 proteins were not expressed in JSRV-induced cancers. In human lepidic adenocarcinomas, VEGFA and VEGFR2 mRNA were weakly expressed and no VEGFR2 protein was detectable. Downregulation of key angiogenic players may contribute to the control of extra thoracic invasion of cancer cells in human and ovine pneumonic-type adenocarcinoma with predominant lepidic growth.

Highlights

Cancers develop as the result of deregulation of multiple cell processes such as resistance to cell death, independence from growth suppressors and inflammation [1]
The VEGF pathway is downregulated in JSRV‐induced adenocarcinomas We analyzed the levels of mRNA expression of VEGFA using RT-qPCR and its protein expression by Western blot in normal lungs, cancers, and lung-derived AECII cultures
The expression of VEGFA protein was abolished in most cancers (90%), while the protein was expressed in 80% normal lungs (Figures 2A and C)

Summary

Introduction

Cancers develop as the result of deregulation of multiple cell processes such as resistance to cell death, independence from growth suppressors and inflammation [1]. Ovine pulmonary adenocarcinoma shares striking similarities with human pneumonic-type lung adenocarcinoma (PTLA) with predominant lepidic growth [15–17] This growth pattern refers to the lining of cancer cells along the alveolar septa without disorganization of the alveolar architecture and with no evidence of stromal, vascular or pleural invasion. Lepidic adenocarcinoma affects more non-smokers, women and young subjects than other lung adenocarcinomas [18] These cancers are slow-growing and as with ovine pulmonary adenocarcinoma, metastatic spread is rare. This unique feature prompted us to decipher the angiogenesis pathway in JSRV-induced pulmonary adenocarcinomas and human lepidic adenocarcinomas especially when considering that most lung cancers in humans are highly invasive [19] and that the activation of angiogenesis is associated with a poor prognosis [20]. Downregulation of key angiogenic players may contribute to the control of extra thoracic invasion of cancer cells in lepidic-predominant adenocarcinomas both in sheep and humans

Materials and methods

Results

B RECEPTORS

Discussion

B PEPTIDASE INHIBITOR

B Protein expression NORMAL