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

LRIG1 (leucine-rich repeat and immunoglobulin-like domain containing), belongs to LRIG family of transmembrane proteins containing leucine rich repeats. LRIGs are considered as tumor suppressor 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 low in Erbb2 + cell lines and more cell motility were observed. AKT/GSK3-β/β-catenin pathway was activated when LRIG1 was downregulated and consequently, Erbb2 was upregulated. So far, no study has reported the expression of LRIG1 in benign forms of tumor such as fibroadenoma. 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. 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 lends supports to the previous studies showing that the down regulation of LRIG1 may lead to a more aggressive and malignant tumor thus acting as a tumor suppressor.