Dynamics of Postmortem Gene Expression in Normal and Neoplastic Murine Liver

The use of postmortem (autopsy) material in fundamental and applied biomedical research significantly facilitates the collection of biomaterial for statistically robust sample cohorts. However, natural adaptive processes to developing cellular stress in the early postmortem period, caused by oxygen and nutrient deprivation, trigger the activation of numerous genes promoting cell survival under stress. Many of these activated pathways are also crucial for tumor cell survival in vivo, as evidenced by various transcriptomic studies. This study aimed to investigate the potential influence of postmortem interval (PMI) duration on gene expression in normal and tumor tissues. Using a model of chemically induced hepatocellular carcinoma in mouse liver, we comparatively analyzed the dynamics of transcript levels for several genes (BRCA1, BRCA2, CHEK1, CHEK2, ATM, CDK12) in paired samples of normal and tumor tissue over a 24-h PMI using RT-qPCR. In normal tissue, gene expression increased significantly, while tumor tissue demonstrated relative transcriptional stability, with no substantial changes in the studied transcript levels. A critical finding was the observed convergence of expression profiles: initial differences between the tissues were completely eliminated by 24 h PMI. This pattern developed despite formally adequate RNA quality (RQN) and the absence of clear signs of progressive autolysis in histology, indicating the insufficiency of standard quality criteria for detecting postmortem changes. These findings collectively underscore the critical importance of minimizing and controlling PMI during the biobanking of oncological samples for reliable transcriptomic research.