Hepatic Stellate Cells in Hepatocellular Carcinoma Promote Tumor Growth Via Growth Differentiation Factor 15 Production.

Although the tumor microenvironment plays an important role in tumor growth, it is not fully understood what role hepatic stellate cells (HSCs) play in the hepatocellular carcinoma (HCC) microenvironment. A high-fat diet after streptozotocin was administered to HSC-specific Atg7-deficient (GFAP-Atg7 knockout [KO]) or growth differentiation factor 15 (GDF15)-deficient (GFAP-GDF15KO) mice. LX-2 cells, a human HSC cell line, were cultured with human hepatoma cells. In the steatohepatitis-based tumorigenesis model, GFAP-Atg7KO mice formed fewer and smaller liver tumors than their wild-type littermates. Mixed culture of LX-2 cells and hepatoma cells promoted LX-2 cell autophagy and hepatoma cell proliferation, which were attenuated by Atg7 KO in LX-2 cells. Hepatoma cell xenograft tumors grew rapidly in the presence of LX-2 cells, but Atg7 KO in LX-2 cells abolished this growth. RNA-sequencing revealed that LX-2 cells cultured with HepG2 cells highly expressed GDF15, which was abolished by Atg7 KO in LX-2 cells. GDF15 KO LX-2 cells did not show a growth-promoting effect on hepatoma cells either in vitro or in the xenograft model. GDF15 deficiency in HSCs reduced liver tumor size caused by the steatohepatitis-based tumorigenesis model. GDF15 was highly expressed and GDF15-positive nonparenchymal cells were more abundant in human HCC compared with noncancerous parts. Single-cell RNA sequencing showed that GDF15-positive rates in HSCs were higher in HCC than in background liver. Serum GDF15 levels were high in HCC patients and increased with tumor progression. In the HCC microenvironment, an increase of HSCs that produces GDF15 in an autophagy-dependent manner may be involved in tumor progression.

Myojin Y ，Hikita H ，Sugiyama M ，Sasaki Y ，Fukumoto K ，Sakane S ，Makino Y ，Takemura N ，Yamada R ，Shigekawa M ，Kodama T ，Sakamori R ，Kobayashi S ，Tatsumi T ，Suemizu H ，Eguchi H ，Kokudo N ，Mizokami M ，Takehara T ... -  《-》

CTGF Mediates Tumor-Stroma Interactions between Hepatoma Cells and Hepatic Stellate Cells to Accelerate HCC Progression.

Connective tissue growth factor (CTGF) is a matricellular protein related to hepatic fibrosis. This study aims to clarify the roles of CTGF in hepatocellular carcinoma (HCC), which usually develops from fibrotic liver. CTGF was overexpressed in 93 human HCC compared with nontumorous tissues, primarily in tumor cells. Increased CTGF expression was associated with clinicopathologic malignancy of HCC. CTGF was upregulated in hepatoma cells in hepatocyte-specific Kras-mutated mice (Alb-Cre KrasLSL-G12D/+). Hepatocyte-specific knockout of CTGF in these mice (Alb-Cre KrasLSL-G12D/+ CTGFfl/fl) decreased liver tumor number and size. Hepatic stellate cells (HSC) were present in both human and murine liver tumors, and α-SMA expression, a marker of HSC activation, positively correlated with CTGF expression. Forced expression of CTGF did not affect growth of PLC/PRF/5 cells, a hepatoma cell line with little CTGF expression, but facilitated their growth in the presence of LX-2 cells, an HSC line. The growth of HepG2 cells, which express high levels of CTGF, was promoted by coculture with LX-2 cells compared with monoculture. Growth promotion by LX-2 cells was negated by an anti-CTGF antibody in both culture and xenografts. Coculturing LX-2 cells with HepG2 cells drove LX-2-derived production of IL6, which led to STAT-3 activation and proliferation of HepG2 cells. An anti-CTGF antibody reduced IL6 production in LX-2 cells and suppressed STAT-3 activation in HepG2 cells. In conclusion, our data identify tumor cell-derived CTGF as a keystone in the HCC microenvironment, activating nearby HSC that transmit progrowth signals to HCC cells, and this interaction is susceptible to inhibition by an anti-CTGF antibody.Significance: Protumor cross-talk between cancer cells and hepatic stellate cells presents an opportunity for therapeutic intervention against HCC.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/78/17/4902/F1.large.jpg Cancer Res; 78(17); 4902-14. ©2018 AACR.

Makino Y ，Hikita H ，Kodama T ，Shigekawa M ，Yamada R ，Sakamori R ，Eguchi H ，Morii E ，Yokoi H ，Mukoyama M ，Hiroshi S ，Tatsumi T ，Takehara T ... -  《-》

Activated human hepatic stellate cells promote growth of human hepatocellular carcinoma in a subcutaneous xenograft nude mouse model.

Geng ZM ，Li QH ，Li WZ ，Zheng JB ，Shah V ... -  《-》

Growth differentiation factor 15 ameliorates nonalcoholic steatohepatitis and related metabolic disorders in mice.

Kim KH ，Kim SH ，Han DH ，Jo YS ，Lee YH ，Lee MS ... -  《Scientific Reports》

Proteinase-activated receptor 2 (PAR2) in hepatic stellate cells - evidence for a role in hepatocellular carcinoma growth in vivo.

Mußbach F ，Ungefroren H ，Günther B ，Katenkamp K ，Henklein P ，Westermann M ，Settmacher U ，Lenk L ，Sebens S ，Müller JP ，Böhmer FD ，Kaufmann R ... -  《Molecular Cancer》