CF101 enhances the apoptotic effect of chemotherapy on colon and pancreatic carcinoma cell lines: Molecular mechanisms involved

Abstract

3173 Background: The A3 adenosine Gi protein-coupled receptor is highly expressed in tumor as compared to normal cells. Targeting the A3 adenosine receptor (A3AR) with the highly selective agonist CF101 induces growth inhibition of colon carcinoma and other tumor cell types via down-regulation of PKB/Akt and NF-kB. High expression level of these two signaling proteins is associated with the development of chemo-resistance in various tumor cell types, thus it prompted us to explore whether CF101 would enhance the anti-tumor effect of chemotherapy. Methods: HCT-116 human colon and Bx-PC3 human pancreatic carcinoma cell lines were used. Cells were cultured for 48h in the presence of 5-FU (0.625 μM), oxaliplatin (0.5 μM) or gemcitabine (0.02 mM) and CF101 (10nM) was introduced for an additional 24h. Proliferation assay (MTT) and protein expression profile were conducted at 72h. In vivo studies included nude mice that were inoculated with the tumor cells. Treatment with chemotherapy alone or in combination with CF101 was initiated when tumor reached a size of 150 mm3. Tumor size was monitored each 4 days and study was terminated after 35 days. Results: In HCT-116 human colon and Bx-PC3 human pancreatic carcinoma cells, CF101 enhanced the cytotoxic effect of 5-FU, oxaliplatin and gemcitabine in vitro by 20% 25% and 32% respectively (P<0.01). The molecular mechanism involved a marked decrease in the level of PKB/Akt and NF-kB followed by an increase in caspase-3 level resulting in apoptosis, as observed by DNA ladder analysis. In xenograft models of HCT-116 colon carcinoma, CF101 doubled the time to tumor progression (p<0.002) when given in combination with 5-FU. Conclusions: CF101 enhanced the chemotherapeutic effect in vitro and doubled the time to tumor progression in xenograft models. It is thus suggested that CF101 may be further developed as an add-on treatment to chemotherapy for colon and pancreatic carcinoma. Author Disclosure Employment or Leadership Consultant or Advisory Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Can-Fite BioPharma