Cooperative Role of Thrombopoietin and Vascular Endothelial Growth Factor-A in the Progression of Liver Cirrhosis to Hepatocellular Carcinoma.

Barbara Vizio,Gian Paolo Caviglia,Angela Pucci,Giuseppe Montrucchio,Renato Romagnoli,Enrico Lupia,Martina Schiavello,Graziella Bellone,Gianluca Paraluppi,Ornella Bosco,Antonina Smedile,Maria Lorena Abate,Ezio David

doi:10.3390/ijms22041818

Barbara Vizio, Gian Paolo Caviglia + Show 11 more

Open Access

https://doi.org/10.3390/ijms22041818

Copy DOI

Abstract

Primary thrombopoietic mediator thrombopoietin (THPO) is mainly produced by the liver; it may act as a growth factor for hepatic progenitors. Principal angiogenesis inducer vascular endothelial growth factor-A (VEGF-A) is critical for the complex vascular network within the liver architecture. As a cross-regulatory loop between THPO and VEGF-A has been demonstrated in the hematopoietic system, the two growth factors were hypothesized to cooperatively contribute to the progression from liver cirrhosis (LC) to hepatocellular carcinoma (HCC). The mRNA and protein expression levels of THPO, VEGF-A, and their receptors were examined, compared, and correlated in paired cancerous and LC tissues from 26 cirrhosis-related HCC patients, using qRT-PCR and immunohistochemistry. THPO and VEGF-A were alternatively silenced by small interfering RNA (siRNA) in human liver cancer cell lines Huh7 and HepG2. THPO and VEGF-A expressions significantly increased in tumor versus LC tissues. HCC and paired LC cells expressed similar levels of THPO receptor (R), whereas vascular endothelial growth factor receptor (VEGFR) -1 and VEGFR-2 levels were higher in HCC than in corresponding LC tissue samples. A significant linear correlation emerged between THPO and VEGF-A transcripts in HCC and, at the protein level, THPO and THPOR were significantly correlated with VEGF-A in tumor tissues. Both HCC and LC expressed similar levels of gene and protein hypoxia inducible factor (HIF)-1α. Positive cross-regulation occurred with the alternative administration of siRNAs targeting THPO and those targeting VEGF-A in hypoxic liver cancer cell lines. These results suggest THPO and VEGF-A might act as interdependently regulated autocrine and/or paracrine systems for cellular growth in HCC. This might be clinically interesting, since new classes of THPOR agonistic/antagonistic drugs may provide novel therapeutic options to correct the frequent hemostatic abnormality seen in HCC patients.

Highlights

Hepatocellular carcinoma (HCC) is the most prevalent primary liver malignancy, ranking as the third-highest cause of cancer deaths worldwide
The present innovative study targeted expression of THPO, vascular endothelial growth factor-A (VEGF-A), and their receptors on hepatocytes in hepatocellular carcinoma (HCC) and matched cirrhotic tissues, and showed that: (i) hepatic THPO production increased in the transition from cirrhosis to liver cancer; (ii) in the tumor context, but not in liver cirrhosis (LC), the THPO, THPOR, and VEGF-A protein expressions were positively correlated; (iii) HCC and LC expressed comparable levels of hypoxia inducible factor (HIF)-1α at both mRNA and protein levels; and (iv) small interfering RNA (siRNA)-mediated knock-down of THPO and VEGF-A signaling in hypoxic hepatic cancer cell lines Huh7 and HepG2, and induced significant cross-inhibitory effects on both mRNA and protein expression
These results suggest that interdependence between THPO and VEGF-A exists in HCC, creating a favorable shift toward tumor growth and expansion in an angiogenesis dependent/independent manner

Summary

Introduction

Hepatocellular carcinoma (HCC) is the most prevalent primary liver malignancy, ranking as the third-highest cause of cancer deaths worldwide. Liver transplantation, and local ablation have improved the outcome in early-stage disease, but tumor recurrence after treatment is high. HCC is a classic example of an inflammation-triggered malignancy, with more than 90% of cases arising as the end stage of persistent inflammation and chronic liver disease, with hepatitis B or C virus infections, alcoholic liver disease, and non-alcoholic fatty liver disease as the main causes underlying the formation and progression of liver cirrhosis (LC) [3]. In order to identify and characterize early tumors, which may have a better prognosis than larger lesions, and to develop more effective therapeutic approaches, it is vital to clarify the molecular events governing tumor initiation and progression in the context of chronic liver injury, such as LC

Methods

Results

Conclusion