Abundant Interleukin-9 Blocks Growth of Melanoma in Mouse Models

Cancer researchers have linked elevated levels of the cytokine interleukin-9 (IL-9) to inhibition of melanoma growth in several mouse models.

Investigators at Harvard Medical School (Boston, MA, USA) worked with several lines of genetically engineered mice including one variety that lacked the gene for production of IL-9. These mice showed accelerated tumor growth as compared to a different line of mice that were deficient in T helper type 17 (TH17) pathway genes encoding retinoid-related orphan receptor gamma (ROR-gamma) and IL-23 receptor (IL-23R). These mice produced abundant IL-9 and demonstrated substantial growth inhibition of B16F10 melanoma.

Administration of recombinant IL-9 (rIL-9) to tumor-bearing mice inhibited melanoma as well as lung carcinoma growth. This inhibitory effect was abrogated by treatment with neutralizing antibodies to IL-9.

The investigators wrote in the July 8, 2012, online edition of the journal Nature Medicine that they had found higher numbers of IL-9 producing cells in normal human skin and blood compared to metastatic lesions of subjects with progressive stage IV melanoma.

“Immunotherapy of cancer is coming of age, and there have been exciting recent results in patients with melanoma treated with drugs that stimulate the immune system,” said senior author Dr. Thomas S. Kupper, professor of dermatology at Harvard Medical School. “We hope that our results will also translate to the treatment of melanoma patients, but much work still needs to be done.”

These results suggest a role for IL-9 in tumor immunity and offer insights into potential therapeutic strategies for treatment of melanoma.

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