Abstract 2556: Granulin-epithelin precursor modulates chemo-resistance in liver cancer

Abstract

Abstract Background and Objective: Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide and is responsible for 80% of the primary liver tumors in adults. HCC is found to be resistant to most current chemo-therapeutic agents, making the disease as one of the most mortal in the world. There is therefore an urgent demand for better therapeutic approaches. Granulin-epithelin precursor (GEP) was identified as a potential therapeutic target from our genome-wide expression profiles study for HCC. It was an autocrine growth factor with over-expression in most HCCs, and involved in HCCs proliferation, invasion and tumorigenicity. The aim of the current study is to examine the role and signaling mechanism of GEP in chemo-resistance, and if chemo-resistant HCC would response to GEP targeted therapy using GEP monoclonal antibody (mAb). Methods: HCC cells Hep3B was stably transfected with GEP cDNA for overexpression, and antisense fragment for suppression studies, respectively. Chemo-resistant HCC populations were obtained by selection and expansion of Hep3B cells under different class of chemo-therapeutic agents, including cisplatin, doxorubicin and fluorouracil. The cells were examined for chemotherapy induced apoptosis with chemo-therapeutic agents alone, or in combination with GEP targeted therapy using GEP mAb. The ERK signaling molecules were examined by western blot, and caspases activity by the Caspase-Glo luminescent assay. Results: The Hep3B transfectants with GEP overexpression demonstrated increased resistance to apoptosis under different class of chemo-therapeutic agents with reference to the parental population. Hep3B cells with GEP suppression resulted in enhanced sensitivity to the chemotherapy induced apoptosis. The Hep3B cells with acquired resistance demonstrated an increment of 8-16 folds in IC50 to cisplatin, doxorubicin and fluorouracil, respectively, with reference to the parental population. The chemoresistant Hep3B cells were responsive to GEP targeted therapy, and combined chemotherapy with GEP targeted therapy demonstrated synergistic effect on apoptosis induction. GEP regulated the ERK pathway including the activation of p-p38 and p-p44/42. GEP targeted therapy alone did not affect the caspases activities, however, combination treatment using the GEP mAb and chemo-therapeutic agents provided a synergistic effect on activation of caspase 3, and magnified the apoptotic effect. Summary: The present study demonstrated that GEP regulated chemoresistance, and GEP mAb could sensitize both the parental and chemoresistant liver cancer cells to chemo-therapeutic agents. The GEP targeted therapy indicated a new therapeutic approach for chemo-resistant liver cancer patients. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2556.