Abstract B03: HURP and ZEB1: Novel prognostic biomarkers in colorectal carcinomas

Abstract

Abstract The current clinicopathologic diagnosis of colorectal cancer (CRC) is based on tumor-node-metastasis staging. This classification system has weaknesses due to the different genetic and epigenetic backgrounds not currently incorporated into CRC staging which can ultimately lead to treatment failure. Biological markers would improve early detection and guide clinicians in subsequent treatment decisions. Recently, we and others have identified “stem-like” molecules with the potential to identify patients at high risk of developing aggressive carcinomas. Herein, Hepatoma Up-Regulate Protein (HURP) and Zinc finger E-box binding homeobox 1 (ZEB1) are assessed as potential prognostic biomarkers in CRC. Tumors (N=21) obtained from colectomies and 5 µm formalin-fixed paraffin-embedded blocks were sectioned and immunostained for HURP and ZEB1. For certain cases (N=8), flash frozen tissues from tumor and adjacent normal colonic tissue were used to extract total RNA, synthesize cDNA, and perform RT-PCR. Presence of tumor cells in analyzed tissue sections was assessed by a pathologist. HURP mRNA expression was 4-fold higher (p=0.0005) in tumor tissue relative to adjacent normal tissue. Furthermore, an increase in HURP expression was evident in all tumor samples relative to their respective normal tissue control with an average 3-fold increase (p=0.001). Immunohistochemical analysis (IHC) of HURP revealed expression in all analyzed specimens. Although the stroma was weakly stained for HURP in some cases, all tumors were immunostained for this protein (average intensity score = ++, p<0.0001). These results suggest HURP’s potential as a tumor marker in CRC. In contrast to those results, ZEB1 mRNA expression in tumors did not differ from that observed in normal adjacent tissue; moreover, a tendency of mRNA to a decrease (n.s.) was observed. IHC for ZEB1 showed immunostaining in all analyzed cases. Weak staining was observed in both tumor and stroma (average intensity score = ++, n.s.). Further stratification of patients by race revealed that in Caucasian-American (CA) patients, staining of ZEB1 was less likely to be associated with disease progression or death after at least 2 years of follow-up. Interestingly, samples obtained from African-American (AA) individuals, known to have worse CRC outcomes, had an association between ZEB1 presence and poor survival regardless of the immunostaining intensity. These findings suggest that IHC localization of ZEB1 may represent a marker of a poor CRC prognosis, particularly in AA patients. However, one must be careful not to over-interpret these results as a Fischer’s Exact test revealed a non-significant p value = 0.387. Any conclusions about population-based distribution of poor prognosis with regards to ZEB1 positive CRC will require an adequately powered sample size. Overall, we have identified two stem cell-like molecules, HURP and ZEB1, with potential as markers of aggressiveness in CRC. Our findings also provide evidence of a possible biological basis for ethnicity-related differences with regards to stemness and regulatory factors of CRC aggressiveness. Citation Format: Logan Fair, Ingrid Espinoza, Xu Zhang, Abdelouahid Elkhattouti, Tangeng Ma, Joy King, Elizabeth Tarsi, Richard Whitlock, Vijay Kannuthurai, Ryan Jimenez, Tara Craft, Mary Graichen, Sharon Lobert, Roy Duhe, Charulochana Subramony, Christian R. Gomez, Christopher Lahr. HURP and ZEB1: Novel prognostic biomarkers in colorectal carcinomas. [abstract]. In: Proceedings of the Fourth AACR International Conference on Frontiers in Basic Cancer Research; 2015 Oct 23-26; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2016;76(3 Suppl):Abstract nr B03.