Efficacy In Vitro of Caffeine and Valproic Acid on Patient-Derived Undifferentiated Pleomorphic Sarcoma and Rhabdomyosarcoma Cell Lines.

We have previously reported that caffeine (CAF) can enhance chemotherapy efficacy of bone and soft-tissue sarcoma established cell lines via cell-cycle perturbation. We subsequently tested the combination of valproic acid (VPA), a histone deacetylase (HDAC) inhibitor, with caffeine on established human osteosarcoma cells in vitro. Both VPA and CAF caused concentration-dependent cell death of the osteosarcoma cell lines in vitro, and their combination was synergistic. We subsequently established patient-derived cell lines from undifferentiated pleomorphic sarcoma (UPS) and rhabdomyosarcoma (RMS), both of which are recalcitrant cancers. These cell lines are termed AC-UPS01 and AC-RMS01, respectively.

In the present study, we tested CAF and VPA and their combination on the two patient-derived sarcoma cell lines. Cell survival after a 72 h exposure to each drug was determined by the WST-8 assay. IC50 values were calculated for each drug.

CAF and VPA caused concentration-dependent cytocidal efficacy for both cell lines. The IC50 for CAF for AC-UPS01 was 2.02 ± 0.22 mM. The IC50 for VPA for AC-UPS01 was 9.54 ± 1.44 mM. The IC50 for CAF for AC-RMS01 was 2.37 ± 0.48 mM. The IC50 for VPA for AC-RMS01 was 2.13 ± 0.20 mM. Synergistic efficacy of combination treatment of CAF and VPA was also observed for both cell lines.

The results of the present study suggest that CAF and VPA may be useful in the treatment of recalcitrant sarcoma.