Combined Functional Genome Survey of Therapeutic Targets for Hepatocellular Carcinoma

Abstract

Purpose: The outcome of patients with advanced hepatocellular carcinoma (HCC) has remained unsatisfactory. Patients with HCC suffer from chronic hepatitis or liver cirrhosis, and their reserve liver function is often limited.Experimental Design: To develop new therapeutic agents that act specifically on HCC but interfere only minimally with residual liver function, we searched for genes that were upregulated in 20 cases of HCC [namely, discovery sets 1 (n = 10) and 2 (n = 10)] in comparison with corresponding nontumorous liver and a panel representing normal organs using high-density microarrays capable of detecting all exons in the human genome.Results: Eleven transcripts whose expression was significantly increased in HCC were subjected to siRNAbased secondary screening of genes required for HCC cell proliferation as well as quantitative reverse transcription-PCR analysis [validation sets 1 (n = 20) and 2 (n = 44)] and immunohistochemistry (n = 19). We finally extracted four genes, AKR1B10, HCAP-G, RRM2, and TPX2, as candidate therapeutic targets for HCC. siRNA-mediated knockdown of these candidate genes inhibited the proliferation of HCC cells and the growth of HCC xenografts transplanted into immunodeficient mice.Conclusions: The four genes we identified were highly expressed in HCC, and HCC cells are highly dependent on these genes for proliferation. Although many important genes must have been overlooked, the selected genes were biologically relevant. The combination of genome-wide expression and functional screening described here is a rapid and comprehensive approach that could be applied in the identification of therapeutic targets in any type of human malignancy. Clin Cancer Res; 16(9); 2518-28. ©2010 AACR.

Targeting ribonucleotide reductase M2 subunit by small interfering RNA exerts anti-oncogenic effects in gastric adenocarcinoma

“…These previous studies suggested that RRM2 may serve as a potential diagnostic biomarker in breast cancer (20), bladder cancer (21) and ovarian cancer (10). RRM2 may also be a potential prognostic marker in non-small cell lung cancer receiving chemotherapeutic agents (22) and a potential therapeutic target for hepatocellular carcinoma (HCC) (23), bladder cancer (21) and pancreatic carcinoma (24,25). The functional studies demonstrated for the first time that RRM2 knockdown by siRNA suppressed in vitro and in vivo growth of gastric cancer cells, and reduced cancer cell invasiveness.…”

Targeting Protein for Xenopus Kinesin-like Protein 2 (TPX2) Regulates γ-Histone 2AX (γ-H2AX) Levels upon Ionizing Radiation

“…Moreover, TPX2 levels are altered in cancers associated with aberrant cellular responses to DNA damage and genomic instability (12)(13)(14)(15)(16)(17)(18)(19). These observations raise the question as to whether TPX2 is involved in the DNA damage response.…”

“…), and amplification of the TPX2 gene has been suggested to promote the progression of colorectal malignancies (12)(13)(14)(15)(16)(17)(18)(19). Conversely, TPX2 haploinsufficiency, leading to decreased levels of TPX2, significantly increases the propensity for the development of tumors in mice (20).…”

RRM2 (ribonucleotide reductase M2)

“…Satow and colleagues performed whole-genome RNA interference-based functional screening in order to identify genes that sensitize lung cancer cells to drug and genes required for proliferation and survival of HCC cells. In this study four genes (AKR1B10, HCAP-G, RRM2, and TPX2) were found to be expressed strongly in HCC, suggeting their role as potential therapeutic targets in hepatocellular carcinoma (Satow et al, 2010).…”