Insights into Growth Factors in Liver Carcinogenesis and Regeneration: An Ongoing Debate on Minimizing Cancer Recurrence after Liver Resection

Prognostic Role of Serum Vascular Endothelial Growth Factor and Hepatocyte Growth Factor Post Stereotactic Body Radiation in Advanced Hepatocellular Carcinoma

Background/Aims

Stereotactic body radiation therapy (SBRT) has evolved as a treatment alternative for advanced hepatocellular carcinoma (HCC) patients who are ineligible for other local therapies. Posttreatment responses are assessed by imaging modalities, serum AFP, and protein induced by vitamin K absence-II (PIVKA) II levels. Despite good specificity, both AFP and PIVKA-II have low to medium sensitivity. The study aimed to find more effective biomarkers that have an impact on the survival outcomes of the patients.

Methods

We have prospectively collected blood samples from 18 patients undergoing SBRT. Serum levels of hepatocyte growth factor (HGF) and vascular endothelial growth factor-A (VEGF-A) were analyzed kinetically pre-SBRT following day 5 and day 30 post-SBRT. Local control (LC), overall survival (OS), progression free survival (PFS), and postprocedure adverse events were recorded.

Results

The cohort had a median follow-up duration of 12.5 months (range 4-30 months). In the entire cohort, the estimated mean OS was 21.2 months (95% confidence interval [CI], 15.9-26.4), and the median progression free survival (mPFS) was 8 months (95% CI, 1.7-14.2). Patients with higher PIVKA-II levels (pre- and post-SBRT) also showed increased concentrations of VEGF-A and HGF. Patients with metastasis at presentation had higher HGF (P = 0.028) and VEGF-A (P = 0.027) concentrations compared to the nonmetastatic group. Patients with increased levels of VEGF-A and HGF at day 30 post-SBRT compared to day 5 had poor PFS. Indeed, the mPFS was 22 months vs 6 months (P = 0.301) in patients with low VEGF-A post SBRT on day 30 compared to day 5. Similarly, mPFS in patients with increase in HGF was 6 months as compared to 22 months (P = 0.326) in patients in whom HGF was reduced post-SBRT.

Conclusion

We conclude that in addition to PIVKA-II, HGF, and VEGF-A can be used as prognostic and predictive markers for early progression of disease post-SBRT. However, further prospective trials are warranted in the future to validate the results.

The roles of cancer stem cell-derived secretory factors in shaping the immunosuppressive tumor microenvironment in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most prevalent malignancies worldwide and has a poor prognosis. Although immune checkpoint inhibitors have entered a new era of HCC treatment, their response rates are modest, which can be attributed to the immunosuppressive tumor microenvironment within HCC tumors. Accumulating evidence has shown that tumor growth is fueled by cancer stem cells (CSCs), which contribute to therapeutic resistance to the above treatments. Given that CSCs can regulate cellular and physical factors within the tumor niche by secreting various soluble factors in a paracrine manner, there have been increasing efforts toward understanding the roles of CSC-derived secretory factors in creating an immunosuppressive tumor microenvironment. In this review, we provide an update on how these secretory factors, including growth factors, cytokines, chemokines, and exosomes, contribute to the immunosuppressive TME, which leads to immune resistance. In addition, we present current therapeutic strategies targeting CSC-derived secretory factors and describe future perspectives. In summary, a better understanding of CSC biology in the TME provides a rational therapeutic basis for combination therapy with ICIs for effective HCC treatment.

Partial Hepatectomy Promotes the Development of KRASG12V-Induced Hepatocellular Carcinoma in Zebrafish

The purpose of this study was to investigate the effects of PH on the development of oncogenic krasG12V-induced HCC in zebrafish. The inducible HCC model in Tg(fabp10a:rtTA2s-M2; TRE2:EGFP-krasG12V) zebrafish was used. PH or sham surgery was performed before the induction of oncogenic krasG12V expression in the livers of transgenic zebrafish. Histological analysis was carried out to determine the progression of HCC and other HCC-associated features including hepatocyte proliferation, extracellular matrix production, and local oxidative stress. The similarity between the process of PH-induced liver regeneration and that of krasG12V-induced HCC development was further compared by RNA-Seq analysis. The results show that PH promotes the development of krasG12V-induced HCC in zebrafish possibly through enhancing neutrophil-mediated oxidative stress and promoting the upregulation of s100a1, and the downregulation of ribosome biogenesis.

Role of Fibrinogen-like Protein 1 in Tumor Recurrence Following Hepatectomy

Partial hepatectomy is a first-line treatment for hepatocellular carcinoma. Within 2 weeks following partial hepatectomy, specific molecular pathways are activated to promote liver regeneration. Nevertheless, residual microtumors may also exploit these pathways to reappear and metastasize. Therapeutically targeting molecules that are differentially regulated between normal cells and malignancies, such as fibrinogen-like protein 1 (FGL1), appears to be an effective approach. The potential functions of FGL1 in both regenerative and malignant cells are discussed within the ambit of this review. While FGL1 is normally elevated in regenerative hepatocytes, it is normally downregulated in malignant cells. Hepatectomy does indeed upregulate FGL1 by increasing the release of transcription factors that promote FGL1, including HNF-1α and STAT3, and inflammatory effectors, such as TGF-β and IL6. This, in turn, stimulates certain proliferative pathways, including EGFR/Src/ERK. Hepatectomy alters the phase transition of highly differentiated hepatocytes from G0 to G1, thereby transforming susceptible cells into cancerous ones. Activation of the PI3K/Akt/mTOR pathway by FGL1 allele loss on chromosome 8, a tumor suppressor area, may also cause hepatocellular carcinoma. Interestingly, FGL1 is specifically expressed in the liver via HNF-1α histone acetylase activity, which triggers lipid metabolic reprogramming in malignancies. FGL1 might also be involved in other carcinogenesis processes such as hypoxia, epithelial-mesenchymal transition, immunosuppression, and sorafenib-mediated drug resistance. This study highlights a research gap in these disciplines and the necessity for additional research on FGL1 function in the described processes.

The role of gut microbiota in liver regeneration

The liver has unique regeneration potential, which ensures the continuous dependence of the human body on hepatic functions. As the composition and function of gut microbiota has been gradually elucidated, the vital role of gut microbiota in liver regeneration through gut-liver axis has recently been accepted. In the process of liver regeneration, gut microbiota composition is changed. Moreover, gut microbiota can contribute to the regulation of the liver immune microenvironment, thereby modulating the release of inflammatory factors including IL-6, TNF-α, HGF, IFN-γ and TGF-β, which involve in different phases of liver regeneration. And previous research have demonstrated that through enterohepatic circulation, bile acids (BAs), lipopolysaccharide, short-chain fatty acids and other metabolites of gut microbiota associate with liver and may promote liver regeneration through various pathways. In this perspective, by summarizing gut microbiota-derived signaling pathways that promote liver regeneration, we unveil the role of gut microbiota in liver regeneration and provide feasible strategies to promote liver regeneration by altering gut microbiota composition.

Dysregulation of Liver Regeneration by Hepatitis B Virus Infection: Impact on Development of Hepatocellular Carcinoma

The liver is unique in its ability to regenerate in response to damage. The complex process of liver regeneration consists of multiple interactive pathways. About 2 billion people worldwide have been infected with hepatitis B virus (HBV), and HBV causes 686,000 deaths each year due to its complications. Long-term infection with HBV, which causes chronic inflammation, leads to serious liver-related diseases, including cirrhosis and hepatocellular carcinoma. HBV infection has been reported to interfere with the critical mechanisms required for liver regeneration. In this review, the studies on liver tissue characteristics and liver regeneration mechanisms are summarized. Moreover, the inhibitory mechanisms of HBV infection in liver regeneration are investigated. Finally, the association between interrupted liver regeneration and hepatocarcinogenesis, which are both triggered by HBV infection, is outlined. Understanding the fundamental and complex liver regeneration process is expected to provide significant therapeutic advantages for HBV-associated hepatocellular carcinoma.