A developmentally prometastatic niche to hepatoblastoma in neonatal liver mediated by the Cxcl1/Cxcr2 axis

Abstract

Background and Aims Hepatoblastoma (HB) is the most common pediatric liver cancer. Its predominant occurrence in very young children led us to investigate whether the neonatal liver provides a protumorigenic niche to HB development. Approach and Results HB development was compared between orthotopic transplantation models established in postnatal day 5 (P5) and 60 (P60) mice (P5Tx and P60Tx models). Single‐cell RNA‐sequencing (sc‐RNAseq) was performed using tumor and liver tissues from both models and the top candidate cell types and genes identified are investigated for their roles in HB cell growth, migration, and survival. Conclusions We found that various HB cell lines including HepG2 cells were consistently and considerably more tumorigenic and metastatic in the P5Tx model than in the P60Tx models. Sc‐RNAseq of the P5Tx and P60Tx HepG2 models revealed that the P5Tx tumor was more hypoxic and had a larger number of activated hepatic stellate cells (aHSCs) in the tumor‐surrounding liver that express significantly higher levels of Cxcl1 than those from the P60Tx model. We found these differences were developmentally present in normal P5 and P60 liver. We showed that the Cxcl1/Cxcr2 axis mediated HB cell migration and was critical to HB cell survival under hypoxia. Treating HepG2 P60Tx model with recombinant CXCL1 protein induced intrahepatic and pulmonary metastasis and CXCR2 knockout (KO) in HepG2 cells abolished their metastatic potential in the P5Tx model. Lastly, we showed that in tumors from patients with metastatic HB, there was a similar larger population of aHSCs in the tumor‐surrounding liver than in localized tumors, and tumor hypoxia was uniquely associated with prognosis of patients with HB among pediatric cancers. We demonstrated that the neonatal liver provides a prometastatic niche to HB development through the Cxcl1/Cxcr2 axis.

Ribonucleotide Reductase Subunit Switching in Hepatoblastoma Drug Response and Relapse

“…HB214 cells were derived from a previously reported HB PDX model, 30 and they generated tumors with faithful HB histopathology when transplanted into NSG mouse liver. 31 Both cell lines were fairly resistant to all the drugs tested with high IC 50 values ( Suppl Table S2) , and triapine and MK1775 did not show higher efficacies compared to the other drugs ( Figure 4A ). Consistent with their RRM2-inhibiting function, triapine and MK1775 treatment led to a significant reduction in the nucleotide levels in HepG2 cells along with a strong induction of the cell cycle suppressor p21 and the DNA damage marker γ-H2AX ( Suppl Figure S6 ).…”

“…5, 6, 42, 43 Past HB studies have mainly focused on the “natural” biology driving advanced tumor progression in an effort on finding better treatment for the high-risk forms of this disease that are resistant to standard treatment. 31, 44, 45 With the increasing appreciation of cancer cell plasticity in drug resistance through studies in adults, understanding mechanisms that enable HB cells to survive drug treatment and support subsequent relapse has become a potential path leading to a better treatment of this pediatric cancer.…”

“…Liver and tumor tissues were fixed in neutral buffered formalin for one day at room temperature and submitted to HistoWiz Inc. (Brooklyn, NY) for paraffin processing and embedding. Paraffin sections were cut at 4 µm and analyzed for direct fluorescence microscopy, H&E staining, IHC, and RNAscope 31 . IHC was performed based on the standard protocol.…”

Recent insights into the pathogenesis and therapeutic targets of chronic liver diseases

“…As the most common paediatric liver cancer, mechanisms of tumourigenesis in hepatoblastoma (HB) are not well understood. Fan et al 128…”

Intratumoral CXCR4hi neutrophils display ferroptotic and immunosuppressive signatures in hepatoblastoma

“…Despite several attempts to explore the immune cell function in HB, the effect of ferroptosis on immune cells, especially neutrophils, remains poorly understood ( 21 ). Here, we provided evidence that HB tissue–infiltrated neutrophils were immunosuppressive and had a higher susceptibility to ferroptosis.…”