Inhibition of COX-2 Slows Skin Cancer Growth

Reducing expression of the enzyme COX-2 (cyclooxygenase-2) either by genetic engineering or through specific drug inhibition was found to slow growth of the most common form of skin cancer, skin basal cell carcinoma (BCC).

Investigators at Stanford University (Palo Alto, CA, USA) genetically engineered a line of mice normally prone to developing BCC to lack the gene for COX-2. They reported in the January 1, 2010, issue of the journal Cancer Prevention that deletion of the COX-2 gene reduced the overall tumor burden by 70%. Conversely, the overall size of the tumors doubled in mice engineered to express higher than usual amounts of COX-2.

A three-year human clinical trial using the selective COX-2 inhibitor celecoxib was truncated after the second year due to the possibility that the drug might cause cardiovascular damage. Nonetheless, results that were collected indicated that celecoxib treatment decreased the growth of skin tumors by about 50% as compared to placebo in participants who entered the trial with 15 or fewer basal cell carcinomas.

"Basal cell carcinomas are the most common human cancer in the United States," said first author Dr. Jean Tang, assistant professor of dermatology at Stanford University, "and their incidence is increasing steadily. This work identifies a possible way to prevent them." The investigators are seeking to continue this line of study by developing a topical form of celecoxib that can be applied directly to the skin to achieve a similar protective effect without associated cardiovascular risk.

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