DNAJB4/HLJ1 deficiency sensitizes diethylnitrosamine-induced hepatocarcinogenesis with peritumoral STAT3 activation.

Environmental chemicals and toxins are known to impact human health and contribute to cancer developments. Among these, genotoxins induce genetic mutations critical for cancer initiation. In the liver, proliferation serves not only as a compensatory mechanism for tissue repair but also as a potential risk factor for the progression of premalignant lesions. The role of Human Liver DnaJ-Like Protein (DNAJB4/HLJ1), a stress-responsive heat shock protein 40, in genotoxin-induced liver carcinogenesis remains unexplored. Using whole-genome transcriptomic analysis, we demonstrate that HLJ1 deficiency in mice results in altered gene signatures enriched in pathways associated with chemically induced liver cancer and IL-6/STAT3 signaling activation. Employing diethylnitrosamine (DEN) as a carcinogen, we further reveal that STAT3 and H2AX phosphorylation induced by short-term DEN treatment are amplified in HLJ1-deficient mice. In long-term DEN experiments, HLJ1 deletion enhances tumor proliferation and progression, accompanied by pronounced STAT3 phosphorylation in normal tissues rather than in tumor regions. The tumor-suppressive role of peritumoral HLJ1 is validated through the transplantation of HLJ1-wildtype B16F1 and LLC cancer cell lines into syngeneic HLJ1-deficient mice, which exhibits an augmented tumorigenic phenotype compared to wildtype controls. This study uncovers a previously unrecognized role of HLJ1 in suppressing liver carcinogenesis via the downregulation of STAT3 signaling in peritumoral normal cells. These findings suggest that HLJ1 reinforcement represents a promising strategy for liver cancer treatment and prevention.