STAT3 activation is associated with IL-10 expression and survival in primary central nervous system lymphoma

Abstract Background Several studies have confirmed that signal transducer and activator of transcription 3 (STAT3) is constitutively phosphorylated in primary central nervous system lymphoma (PCNSL). However, the underlying mechanism and prognostic significance of STAT3 activation have not been clarified. Methods The expression of STAT3, phosphorylated STAT3 (p-STAT3) and interleukin-10 (IL-10) was examined in 32 PCNSL samples by immunohistochemistry (IHC). The relationship between IL-10 expression and STAT3 phosphorylation was determined. In addition, the associations of the expression of these proteins with clinical factors and survival were analyzed. Results Expression of STAT3, p-STAT3 and IL-10 was detected in 28 (87.5%), 17 (53.1%) and 25 (78.1%) samples, respectively; IL-10 expression was significantly associated with STAT3 phosphorylation in PCNSL (P = 0.033). STAT3 phosphorylation and IL-10 expression were associated with the presence of multiple brain lesions (P = 0.004 and P = 0.027, respectively), suggesting that STAT3 activation may enhance the intracranial spread of tumors in PCNSL. The 2-year overall survival (OS) and progression-free survival (PFS) rates were 67.8% and 35.5%, respectively. Kaplan-Meier survival analysis demonstrated that STAT3 phosphorylation, IL-10 expression and multiple brain lesions were significantly associated with PFS in PCNSL (P = 0.009, P = 0.030 and P = 0.040, respectively). However, Cox regression analysis indicated that only STAT3 phosphorylation was significantly associated with a shorter PFS (P = 0.016, HR: 3.22, 95%CI: 1.24-8.37). Conclusion Our results indicate that STAT3 activation is closely related to IL-10 expression and that p-STAT3 may be a novel biomarker predicting poor survival in PCNSL.