Role of SPARC in cancer therapy

Colorectal cancer (CRC) is the third most common cancer in both men and women, and was responsible for an estimated 8,300 deaths in 2004 in Canada. While there has been an overall decline in the incidence and mortality of CRC in the past two decades because of better cancer prevention, the overall five-year survival rate continues to be poor. This is due in part to chemotherapy resistance, which is common in many solid tumours. Dr. Isabella Tai’s research is directed at understanding the mechanisms enabling cancer cells to become resistant to cancer drugs and other therapies. Using a high-throughput “genomics” approach, her research team has developed a comprehensive list of genes involved in chemo- and radiotherapy resistance. One such gene, SPARC, had low levels of expression in colorectal cancer cells that were resistant to several chemotherapy agents. By increasing the levels of SPARC in therapy refractory cells, response to radiotherapy and chemotherapy was restored and tumor size reduction was observed. Dr. Tai’s team is now examining the general applicability of SPARC-based therapy in other cancer model systems, how it promotes tumor regression, and whether patients who are likely to become resistant to therapy can be identified based on a potential diagnostic marker. The results of the project could lead to improvements in cancer treatment and potentially provide a diagnostic marker to identify individuals likely to develop chemotherapy resistance.