Peritumoral HLJ1-STAT3 pathway investigation in carcinogen-induced hepatocellular carcinoma.

Abstract

e16251 Background: Hepatocellular carcinoma (HCC) is a major global health issue and its treatment options have been limited. Therefore, it is urgent to develop cancer biomarkers for defining cancer risk, diagnosis, prognosis, and even finding new therapeutic targets. Human Liver DnaJ-Like Protein (HLJ1), which belongs to DnaJ heat shock protein family (HSP40) member B4 (DNAJB4), has been identified as a tumor suppressor in various cancers including lung cancer and colorectal cancer. Though the biological function of HLJ1 in either cancer or the liver has emerged in recent years, the precise role of HLJ1 in HCC carcinogenesis is still unclear. Methods: Samples for gene expression cDNA microarray were from 6-8 weeks wild-type (WT) and HLJ1 knockout (HLJ1-/-) mice liver. For the long-term carcinogenesis study, both mice are injected with 20 mg/kgbw diethylnitrosamine (DEN) at postnatal day 15. After that, 50 mg/kgbw DEN was administrated weekly to mice between the ages of 4 to 12 weeks. Mice were sacrificed at ages 30 and 36 weeks to assess the tumor count and size. For the short-term DEN study, 6-8-week-old mice were injected with 100 mg/kg DEN, and 24 and 48 hours after administration the liver tissues were frozen and fixed for western blotting and IHC analysis. Cancer cell transplantation was performed by intrasplenic injection of HLJ1-wildtype LLC and B16F1 cells into both genotypes. Clinical information of 362 liver cancer patients from the TCGA database was analyzed for the correlation between HLJ1 expression and survival. Results: In cDNA microarray analysis, We demonstrated that HLJ1 deficiency led to HCC gene signatures associated with activated IL-6/STAT3 signaling pathways. We used the DEN as a carcinogen and found STAT3 and H2AX phosphorylation induced by short-term DEN treatment was amplified in HLJ1-deficient mice. In long-term DEN experiments, HLJ1 deletion promoted tumor initiation and proliferation at the early and late stages of HCC progression accompanied by pronounced STAT3 phosphorylation in the normal part instead of the tumor part. Furthermore, transplantation of HLJ1-wildtype B16F1 and LLC cell lines into HLJ1-deficient mice led to more tumorigenic phenotype than into wildtype mice. Clinical information of 362 liver cancer patients from the TCGA database exhibited that higher expression of HLJ1 in the tumor part is correlated to a lower disease-specific survival rate. Conclusions: In summary, HLJ1 protects against DEN-induced HCC hepatocarcinogenesis through the regulation of STAT3 signaling in the peritumoral normal cells. Hence, HLJ1 can be a prognostic biomarker for liver cancer and a promising therapeutic target for HCC in the future.