Melanoma cell lines express the receptor for interleukin-29 and respond via the Jak/Stat signaling pathway

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Introduction: Interlukin-29 (IL-29) is a member of the type III interferon (IFN) family that has been shown to have antiviral activity and inhibit cell growth. To date, expression of the receptor for IL-29 (IL-29R) has been described in hepatic and colonic cells, and ligand-receptor interactions on these cells lead to activation of the janus-kinase/signal transducer and activator of transcription (Jak/STAT) leading to signal transduction. We hypothesized that the IL-29R would also be expressed on human melanoma cell lines. Methods: Expression of IL-29R was evaluated using Reverse Transcriptase Polymerase Chain Reaction (RT-PCR). A combination of western immunoblot and flow cytometry were used to evaluate for cell signaling. The 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) proliefation assay was used to measure cell line proliferation. Real Time PCR was used to evaluate mRNA expression of Suppressor of Cytokine Signaling-1 (SOCS-1), SOCS-4, SOCS-6, MxA, and OAS. Results: Ten melanoma cell lines were examined for expression of the IL-28R1 and IL-10R2 subunits of the IL-29R. Both receptors were expressed on the A375, 1106 Mel, HS294T, 18105 Mel, HT144, Mel 39, and F01 cell lines. The IL-10R2 was expressed on the 1174 Mel and SK Mel 5 cell lines in the absence of detectable IL-28R1. Only the 1259 Mel cell line lacked both receptors. Incubation of A375, 1106 Mel, F01, and 1259 Mel with IL-29 (10-1,000 ng/mL) led to phosphorylation of STAT1 (p-STAT1), p-STAT2, p-STAT3 and p-STAT5 within 15 minutes of exposure, an effect which was dose dependent in nature. Cell proliferation was not inhibited by IL-29 treatment in any cell line tested. IL-29 treatment did not induce apoptosis (as measured by the cleavage of PARP) in any melanoma cell line. SOCS-1, SOCS-4, and SOCS-6 showed no significant change over a 12 hour time interval, however there was an increase in expression of MxA and OAS mRNA in 1106 Mel, A375, and F01 over a 12 hr time period. Conclusion: IL-29 receptors are expressed on the surface of several melanoma cell lines and IL-29 treatment of these cell lines leads to signaling via the Jak/STAT pathway and activation of some viral signals, but does not induce apoptosis. Further exploration could lead to anti-cancer therapies aimed at the IL-29R.