CARACTERIZAÇÃO GÊNICA DO ESTRESSE DO RETÍCULO ENDOPLASMÁTICO NA PROGRESSÃO DA CARCINOGÊNESE EM MODELO DE CÂNCER COLORRETAL ASSOCIADO A COLITE INDUZIDOS COM AZOXIMETANO/DSS EM CAMUNDONGOS HAIRLESS

Abstract

Objetive: The main objective of this work was to characterize the histopathological and molecular evolution of endoplasmic reticulum stress (ERE) in an experimental animal model of colorectal cancer associated with Azoxymethane (AOM) and colitis induced by Dextran Sodium Sulfate (DSS). Methodology: The work was carried out at the Faculty of Medicine of the Federal University of Mato Grosso do Sul, in Campo Grande, from March 2021 to January 2024. The present study was carried out on 84 Hairless mice. The animals were distributed into 3 groups: Group 1 – Negative control (n=28); Group 2(n=28) – Received 1 dose of intraperitoneal (IP) AOM at the beginning of the 3rd week and 2.5% DSS in drinking water, for 7 consecutive days, in the 2nd, 5th and 8th weeks and Group 3(n=28) – Received 2 doses of AOM IP and 2.5% DSS in drinking water, at the beginning of the 3rd and 4th weeks, for 7 consecutive days, in the 2nd, 5th and 8th weeks. Euthanasia was performed in 4 moments, at the end of the 5th, 10th, 15th and 20th weeks, respectively). Colons were explanted, divided into two fragments of ~ 1 cm, duly stored, either in buffered formalin (10%) for histopathological analysis, or immediate preservation in liquid nitrogen with subsequent storage at -80C, for subsequent extraction of total RNA, and evaluation of relative expression by RT-qPCR of ERS target genes IRE1-α, PERK, ATF6 and CHOP, involved in the Unfolded Protein Response (UPR) of colorectal carcinogenesis associated with colitis. Results: Animals treated with AOM/DSS developed pre-neoplastic lesions associated with colitis in colorectal tissue cells. Controls (G1) presented progressive profiles in the relative expression of each target gene analyzed, corresponding to the chronology of weeks and ages of the animals. The groups under intervention, G2 (1 AOM + 3 DSS) and G3 (2 AOM + 3 DSS), showed initial under-expression of IRE1-α, PERK, ATF6 and CHOP mRNAs, followed by a slight increase in the expressions of target genes, without recovery of control levels, except for the G3 group (2 AOM + 3 DSS), whose target gene ATF6 initially showed slight down regulation, followed by upregulation in relation to the initial levels of the 5th week. Conclusion: The present experimental model in the Hairless mouse presented biometric and histopathological parameters, characteristic of inflammatory and pre-neoplastic lesions, with the presentation of pre-carcinogenic polyps, typical of the experimental evolution of CRC, through the combined use of AOM/DSS. The relative expressions of mRNAs for the IRE1-α, PERK, ATF6 and CHOP genes showed a profile of successive and progressive increases for each week of the experimental protocol in the control groups, which suggests the influence of animal aging on the expression of these genes ERS regulations. On the other hand, the relative expressions of target mRNAs were sub modulated in most experimental groups under AOM/DSS treatment. The findings are compatible with the activation of adaptive mechanisms of cell survival and proliferation, through inflammatory and carcinogenic stimuli, applied to the animal model of the present work. Keywords: Azoxymethane. Dextran Sodium Sulfate. Colorectal cancer. Colitis. Endoplasmic reticulum stress. Unfolded protein response. CCR signaling pathways.