Intracellular hyaluronic acid-binding protein 4 (HABP4): a candidate tumor suppressor in colorectal cancer
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Talita Diniz Melo-Hanchuk2,*, Carolina Colleti1,*, Ângela Saito3,*, Maria Carolina Santos Mendes4, José Barreto Campello Carvalheira4, Jose Vassallo5 and Jörg Kobarg1
1 School of Pharmaceutical Sciences, State University of Campinas (UNICAMP), Campinas, SP, Brazil
2 Department of Biochemistry and Tissue Biology, Institute of Biology, State University of Campinas (UNICAMP), Campinas, SP, Brazil
3 Brazilian Biosciences National Laboratory (LNBio), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, SP, Brazil
4 Division of Oncology, Department of Internal Medicine, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Campinas, SP, Brazil
5 Laboratory of Investigative Pathology, CIPED, Faculty of Medical Sciences, State University of Campinas, Campinas, SP, Brazil
* These authors contributed equally to this work
Keywords: colon cancer; regulatory protein; gene knockout; proliferation; tumor marker
Received: September 08, 2020 Accepted: October 27, 2020 Published: November 17, 2020
Hyaluronic Acid-binding protein 4 (HABP4) is a regulatory protein of 57 kDa that is functionally involved in transcription regulation and RNA metabolism and shows several characteristics common to oncoproteins or tumor suppressors, including altered expression in cancer tissues, nucleus/cytoplasm shuttling, intrinsic lack of protein structure, complex interactomes and post translational modifications. Its gene has been found in a region on chromosome 9q22.3-31, which contains SNP haplotypes occurring in individuals with a high risk for familial colon cancer. To test a possible role of HABP4 in tumorigenesis we generated knockout mice by the CRISPR/Cas9 method and treated the animals with azoxymethane (AOM)/dextran sodium sulfate (DSS) for induction of colon tumors. HABP4–/– mice, compared to wild type mice, had more and larger tumors, and expressed more of the proliferation marker proteins Cyclin-D1, CDK4 and PCNA. Furthermore, the cells of the bottom of the colon crypts in the HABP4–/– mice divided more rapidly. Next, we generated also HABP4–/– HCT 116 cells, in cell culture and found again an increased proliferation in clonogenic assays in comparison to wild-type cells. Our study of the protein expression levels of HABP4 in human colon cancer samples, through immunohistochemistry assays, showed, that 30% of the tumors analyzed had low expression of HABP4. Our data suggest that HABP4 is involved in proliferation regulation of colon cells in vitro and in vivo and that it is a promising new candidate for a tumor suppressor protein that can be explored both in the diagnosis and possibly therapy of colon cancer.
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