Improved anticancer activity of clotam as a copper-complex

Abstract Clotam (tolfenamic acid or TA) is a nonsteroidal anti-inflammatory drug used to treat migraine headaches. Research from our laboratory and other groups has demonstrated that TA also acts as an anticancer agent in several adult and pediatric cancer models. It is well established that the anticancer activity of TA is partly mediated by its ability to downregulate the specificity protein (Sp) family of transcription factors and their downstream targets, notably the inhibitor of apoptosis protein family member survivin. Both Sp1 and survivin are upregulated in cancer cells and are associated with poor prognosis, making them ideal therapeutic targets. It was recently suggested that the therapeutic potential of TA could be enhanced by forming a complex with copper(II). In this study we synthesized a copper(II) complex of TA (Cu-TA) and tested its anticancer activity using cell lines representing various cancers such as breast, prostate, pancreatic, brain, colon, neuroblastoma, medulloblastoma, and sarcoma. The compound was synthesized and its purity was assessed by UV-visible spectrophotometry. Purified compound (>98%) was dissolved in DMSO and its antiproliferative activity was determined using the CellTiter-Glo cell viability assay kit. In our initial screening various cancer cells were treated with increasing concentration of Cu-TA or TA, and cell viability was assessed at 24 and 48h post-treatment. The effect of Cu-TA on expression of Sp1 and survivin was determined by Western blot analysis of lysates prepared using cells treated with Cu-TA or TA for 48h. We also studied the effect of Cu-TA on cell cycle and apoptosis using medulloblastoma cell lines. Both Cu-TA and TA decreased cell viability in a dose-dependent manner; however, Cu-TA consistently had lower IC50 values in all the cell lines tested, suggesting its higher efficacy compared to TA. In line with the viability results, Western blot analysis of survivin expression demonstrated that Cu-TA was more effective in inhibiting its expression compared to TA. Also, treatment of medulloblastoma cells with Cu-TA resulted in cell cycle arrest in G0/G1 phase accompanied by an increased apoptosis as determined by annexin-V staining. This preliminary screening demonstrates the potential of Cu-TA as an effective anticancer agent with the ability to target survivin. Further studies to delineate the mechanism of action of Cu-TA are under way. Citation Format: Umesh T. Sankpal, Rafid Patel, Bianca Arechiga, Abigail Hunter, Jaya Chhabra, Deondra T. Brown, Raj K. Gurung, Alvin A. Holder, Riyaz M. Basha. Improved anticancer activity of clotam as a copper-complex [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5424.