Leucine-rich repeats and immunoglobulin-like domains protein 1 (LRIG1) is downregulated in Invasive ductal carcinoma and potential prognostic marker of breast cancer.

Abstract

LRIG1 belongs to the family of transmembrane proteins containing leucine-rich repeats. LRIGs are considered as tumor suppressors as they negatively regulate receptor tyrosine kinases. The role of LRIG1 as an EGFR regulator makes it an important marker to be studied in various epithelial-derived cancers. LRIG1 expression was determined in Erbb2 + cell lines by western blotting, and cell motility was examined by cell migration assay. The AKT/GSK3-β/β-catenin pathway was determined in the presence of LRIG1 and Erbb2 by using western blotting. So far, no study has reported the expression of LRIG1 in benign forms of tumor such as fibroadenoma. The current study aims to analyze LRIG1 expression in fibroadenoma and invasive ductal carcinoma (IDC) tissues. In this study, we compared the LRIG1 expression with different clinicopathological parameters of patients having IDC or fibroadenoma. LRIG1 expression was low in Erbb2+ cell lines, and more cell motility was observed. The AKT/GSK3-β/β-catenin pathway was activated when LRIG1 was downregulated; consequently, Erbb2 was upregulated. Our results indicated that LRIG1 expression can be significantly correlated with age, Nottingham index, and Her2/neu status of cancer. The expression of LRIG1 in IDC and fibroadenoma were found to be significantly different. The fibroadenoma tissue sections were found to express LRIG1 more intensely as compared to the IDC sections, which are in line with the studies reporting reduced copy number of the gene either due to gene deletion or transcriptional inhibition. This further supports that the downregulation of LRIG1 may lead to malignant tumor acting as a tumor suppressor.