K. H. Pardiwala1, G. Qiao1, B. Prabhakar1, A. V. Maker1 1University Of Illinois At Chicago,Chicago, IL, USA
Introduction:
T-cell infiltration in primary and metastatic colorectal cancer tumors is associated with improved patient survival. LIGHT (TNFSF14) is an immunomodulator that has been shown to increase T-cell trafficking to tumors that we have previously shown to be associated with improved patient survival when expressed at high levels in metastatic colon cancer deposits. However, the mechanism of LIGHT-associated survival benefit is not completely understood.
Methods:
Murine colorectal cancer cells (CT26) were designed to stabily over-express LIGHT by lentiviral transduction. Cell morphology was assessed by light microscopy, survival was evaluated with Annexin V/propridium idodide staining, proliferation was determined using the MTS colorimetric assay, and 3D cell migration assays were performed in collagen gel matrix and analyzed on Image J software. Natural Killer (NK) and T-cells were obtained from the spleens of Balb/C mice and cultured with LIGHT+CT26 syngeneic colon cancer cells in various E:T ratios. Cell proliferation was determined with CFSE staining. In vivo models were created by tumor cell flank injections of LIGHT+CT26 or wtCT26 cells into syngenic, immunocompetent Balb/C mice.
Results:
LIGHT+CT26 colon cancer cells demonstrated similar morphology, survival, apoptosis, and migration compared to wtCT26 cells. T-cell proliferation was increased in the presence of LIGHT+CT26 compared to control CT26 cells(67.3%vs. 50.3% ). Similarly, when compared to wtCT26, LIGHT over-expressing CT26 cells stimulated natural-killer (NK) cell proliferation nearly three-fold (24% vs. 8 %). Eight of eight mice inoculated with wtCT26 formed palpable tumors with an average volume of 2458 ± 572 mm3 while 0 of 8 mice inoculated with CT26LIGHT developed tumors (p= 0.0026). (figure)
Conclusion:
Over-expression of the immunostimulatory cytokine LIGHT in colorectal cancer cells stimulates lymphocyte proliferation and inhibits in-vivo tumor growth. Further studies to determine the mechanism of LIGHT-induced anti-tumor responses and to determine its potential as an immunotherapeutic agent in colorectal cancer are warranted.
