57P - V-set and immunoglobulin domain containing 1 (VSIG1): Gene vs protein expression in colorectal cancer tissue samples

Background

V-set and immunoglobulin domain containing 1 (VSIG1) is a cell-cell adhesion molecule considered specific for gastric carcinomas. No data about correlation between gene and protein expression in colorectal cancer (CRC) were published to date. Aim: To examine the possible association between the gene and protein expressions of VSIG1 in CRC.

Methods

In 77 CRCs the protein expression of VSIG1 (polyclonal; Sigma-Aldrich), and p53 (ready to use, Agilent) was examined immunohistochemically (IHC) using formalin-fixed paraffin-embedded tissues. Gene expressions of VSIG1 and TP53 were also analyzed after RNA isolation from fresh tissue samples stored at -80°C. A relative quantitation (RQ) value RQ>1 was considered highly expressed whereas RQ<1 was used to identify low gene expressions for VSIG1 and TP53. No cases with preoperative oncologic therapy were included.

Results

VSIG1 was highly expressed in 44/77 cases (gene level) whereas 18/77 CRCs presented IHC membrane positivity. A low VSIG1 gene expression level was associated with complete loss of IHC positivity for VSIG1 (p=0.001). Although no association between the level of the two examined genes was found (p=0.21), most of the cases showing p53≥50% associated low VSIG1 expression (p=0.008). Half of the IHC positive cases presented KRAS-mutations (9/18) compared with only 32.20% (19/59) from the VSIG1-negative group. From the 21 carcinomas of the rectum, 19 showed complete IHC loss of VSIG1. No association was seen between VSIG1 and tumor stage (p=0.34), budding degree (p=0.57), microsatellite status (p=0.89) or survival rate. The present data firstly proved that loss of IHC positivity of VSIG1 seems to be more frequent in the carcinomas of the rectum, especially in Kras-wild type cases.

Conclusions

Loss of positivity might be the expression of a low gene expression level but the clinical implications are far to be understood. This study was partially funded by the CNCS – UEFISCDI, project number PCCF 20/2018.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

Research Center of Oncopathology and Transdisciplinary Research (CCOMT), George Emil Palade University of Medicine, Pharmacy, Science and Technology, Targu Mures, Romania.

Funding

CNCS – UEFISCDI, project number PCCF 20/2018.

Disclosure

All authors have declared no conflicts of interest.