HABP4 and colon cancer: characterization of the HABP4 role in tumor cells and animal model

Author(s)

Carolina Colleti

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Ciências Farmacêuticas
• Defense date: 2020-02-20

Examining board members

Jörg Kobarg; Carmen Veríssima Ferreira; Juliana Helena Costa Smetana

• Advisor: Jörg Kobarg

Abstract

HABP4 protein was first identified by cross-reacting with the Ki-1 antibody, which recognizes malignant Hodgkin's lymphoma cells. Since its discovery, effort has been made to characterization its structure and function. It has been shown that HABP4 undergoes several types of post-translational modifications, such as phosphorylation, methylation and SUMOylation, and it is part of the intrinsically unstructured class of proteins. These and other identified features, such as shuttling between nucleus and cytoplasm and transcriptional regulation activity, suggest that HABP4 may be involved in cancerous processes. HABP4 has a paralogue protein, SERBP1, that shares 40.7% identity and 67.4% similarity with HABP4 and possesses nuclear and cytoplasmic localization, indicating likely similar or redundant functions in cells. Yeast two-hybrid experiments and global gene expression analysis by DNA microarray performed by our group identified 413 genes with altered expression profile by HABP4 overexpression (88% down-regulated). Most genes were related to proliferation, cell cycle and apoptosis, which indicates their involvement in cellular stress response mechanisms. In this work the effects of HABP4 deletion in mouse and in human colorectal carcinoma cell line are presented. In mouse model, HABP4 deletion leads to a higher rate of intestinal cell proliferation. PCNA and Cyclin D1 expression were found to be are elevated in knockout animals, even in the absence of tumor induction by AOM/DSS treatment, showing that the HABP4 knockout confers a genetic susceptibility to colorectal cancer development. HABP4 knockout in human HCT116 cells was successfully obtained and revealed increase in cell proliferation, as observed in mice. Moreover, DNA damage response caused by etoposide is presented. It was observed that knockout cells have lower ?H2AX expression. Therefore, during the cell cycle there is no G2 / M checkpoint stop, allowing knockout cells to accumulate DNA errors (AU)

• FAPESP's process: 17/20266-6 - Generation of specific antibodies against Ki-1/57 regulatory protein for functional analysis of Ki-1/57 knockout mice
• Grantee: Carolina Colleti
• Support Opportunities: Scholarships in Brazil - Master