Abstract 1065: IL-10 as an indicator of metastatic potential in colorectal carcinoma
Authors: Townsend Michelle H. , Cox Taylor P. , Felsted Abigail M. , Piccolo Steven R. , Robison Richard A. , O'Neill Kim L. 
Published: August 2018

The purpose of this study was to evaluate the expression of TGF-β and IL-10 in primary and metastatic tumors to determine the contribution that these cytokines may have to metastasis. Interleukin-10 (IL-10) is an anti-inflammatory cytokine that inhibits antigen-presenting cells and the secretion of pro-inflammatory cytokines. Because tumors typically thrive in a pro-inflammatory microenvironment, the anti-inflammatory properties of IL-10 have been shown to decrease the metastatic ability of tumors. IL-10 has also been shown to suppress the anti-tumor immune response, thereby increasing metastatic potential. These conflicting conclusions led us to investigate the possible correlation IL-10 expression may have on the metastatic capabilities of colorectal cancer. TGF-β was also chosen for this study because of the observed connection between cytokine expression and metastasis. In order to evaluate cytokine expression, we utilized standard immunohistochemistry procedures. Human tissues were stained with antibodies against TGF-β and IL-10, along with GAPDH as a positive control and a universal negative isotype control. We tested colon adenocarcinoma (n=30), metastatic colon adenocarcinoma (n=30), cancer adjacent normal tissue (n=20), normal colon tissue (n=10), and tubular adenoma (n=10). Using ImageJ software, samples were analyzed by converting tissue images to a grayscale and then assigning a threshold to ensure analysis was not affected by negative space within the tissue. Gray intensity values above 115 were determined to be ‘negative' for expression, while samples with gray intensity values below 115 were ‘positive' for expression. Our results show that IL-10 expression was significantly higher in patients with metastatic colon cancer when compared to patients with non-metastatic colon cancer, suggesting a connection between the over expression of IL-10 and metastatic capability. In colon adenocarcinoma samples, 20% of patients expressed high levels of IL-10 (average gray intensity = 111.46), while 80% of patients expressed low levels of IL-10 (average gray intensity = 125.51). In metastatic colon adenocarcinoma samples the proportion of high cytokine expression was higher, with 53% of patients expressing high levels of IL-10 and 47% of patients expressing low levels of IL-10. Additionally, IL-10 levels were significantly greater (p&lt;.0001) in patients with metastatic colorectal carcinoma, with an average gray intensity of 106.42 in Metastatic IL-10 High patients and 119.95 in Metastatic IL-10 Low patients. TGF-β expression appeared to remain consistent between normal and cancerous tissues, showing no significant variation between primary tumor and metastatic tissue samples. We have concluded that while TGF-β expression showed little variability between primary and metastatic tumors, IL-10 may be an effective biomarker for characterizing tumors and determining their metastatic potential.

Citation Format: Michelle H. Townsend, Taylor P. Cox, Abigail M. Felsted, Steven R. Piccolo, Richard A. Robison, Kim L. O'Neill. IL-10 as an indicator of metastatic potential in colorectal carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1065.