Wei-Hua Ren

Ligation of TLR2 by Versican: A Link Between Inflammation and Metastasis

Versican, a large extracellular matrix proteoglycan, accumulates both in tumor stroma and cancer cells. It participates in cell adhesion, migration, and angiogenesis, all features of invasion and metastasis. However, the mechanism(s) whereby versican promotes cancer invasion and metastasis is not yet fully understood. A recent study has documented that versican can activate tumor-infiltrating myeloid cells through toll-like receptor (TLR) 2 and its co-receptors TLR6 and CD14 and elicit the production of proinflammatory cytokines including TNF-alpha that enhance tumor metastasis. As both resident fibroblasts and endothelial cells (ECs) also express functional TLR2 and its co-receptors, we hypothesized that, in addition to myeloid cells, versican may trigger the activation of both fibroblasts and ECs. Of interest, TLR2-mediated activation of EC and fibroblast has been observed to increase the secretion of interleukin-8, a proinflammatory CXC chemokine that potentiates neutrophil infiltration and angiogenesis, as well as metastatic growth. Ligation of TLR2 by versican appears to be directly involved in the activation of multiple types of cells in tumor stroma and the induction of inflammatory cytokine secretion, providing a link between inflammation and cancer metastasis. Accordingly, antagonists of versican and TLR2 restrain the activation of tumor stromal cells, which may offer a novel approach to cancer therapy by targeting tumor microenvironment.

Prognostic significance of osteopontin in hepatocellular carcinoma: A meta‐analysis

Osteopontin (OPN) has been implicated in tumor development and progression for several years. However, the prognostic value of OPN overexpression in patients with hepatocellular carcinoma (HCC) remains controversial. We performed a meta‐analysis to assess the relationship between OPN overexpression and clinical outcome of HCC. A meta‐analysis of seven studies (1,158 patients) was carried out to evaluate the association between OPN and overall survival (OS) and disease‐free survival (DFS) in HCC patients. The correlation between OPN and tumor vascular invasion or other invasion‐related parameters was also assessed. Data were synthesized with random effect model of DerSimonian and Laird, hazard ratio (HR) or odds ratio (OR) with its 95% confidence interval (CI) was used as the effect size estimate. Our analysis results indicated that high OPN expression predicted poor OS (HR: 1.37, 95% CI: 1.21–1.55) and DFS (HR: 1.62, 95% CI: 1.24‐2.11) of HCC. OPN overexpression tended to be associated with the presence of tumor vascular invasion (OR: 1.93, 95% CI: 0.97–3.84) and advanced tumor grade (OR: 1.74, 95% CI: 0.95–3.18). By this study, we conclude that OPN overexpression indicates a poor prognosis for patients with HCC, it may also have predictive potential for HCC invasion and metastasis.

Hepatocellular Carcinoma-propagating Cells are Detectable by Side Population Analysis and Possess an Expression Profile Reflective of a Primitive Origin

The recent identification of “Side Population” (SP) cells in a number of unrelated human cancers has renewed interests in the hypothesis of cancer stem cells. Here we isolated SP cells from HepG2 cells and 18 of the 21 fresh hepatocellular carcinoma (HCC) tissue samples. These SP cells have higher abilities of forming spheroids, invasion and migration. Tumors could generate only from SP, not non-SP (NSP), cells in a low dose of subcutaneous injection to the NOD/SCID mice (5 × 102 cells/mouse). The mRNA microarray analysis of the SP vs. NSP cells isolated from HepG2 cells revealed that the SP cells express higher levels of pluripotency- and stem cell-associated transcription factors including Klf4, NF-Ya, SALL4 and HMGA2. Some of the known hepatobiliary progenitor/stem cell markers, such as Sox9 was also up-regulated. RT-qPCR analysis of the gene expression between SP cells and NSP cells isolated from both HepG2 cells and HCC tissue samples showed that most of the tested mRNAs’ changes were in consistent with the microarray data, including the general progenitor/stem cells markers such as Klf4, NF-Ya, SALL4 and HMGA2, which were up-regulated in SP cells. Our data indicates that HCC cancer stem cells exist in HepG2 and HCC fresh tissue samples and can be isolated by SP assay.

A novel multi-target RNAi adenovirus inhibits hepatoma cell proliferation, migration, and induction of angiogenesis

The pathogenesis of hepatocellular carcinoma (HCC) is a multi-step process involving many genes. Consequently, single gene targeting therapy has limited efficacy, making combination therapy targeting multiple genes a necessity. Based on our previous findings, we constructed a single vector mediating simultaneous expression of multiple short hairpin RNAs (shRNAs) against human vascular endothelial growth factor receptor 2 (VEGFR2), chemokine C-C motif receptor 1 (CCR1), and epithelial cell adhesion molecule (EpCAM), three genes closely related to HCC progression that act through separate pathways. The shRNA vector efficiently downregulated the mRNA and protein of all three molecules in Huh7 hepatoma cells. The vector also inhibited cell proliferation and migration and reduced angiogenesis. Furthermore, this shRNA vector can be recombined into adenovirus, a gene therapy vector, for better in vivo application. It thus offers a potentially effective future gene therapy approach to treating human liver cancer.