Abstract
Background: Little is known about the associations between PAK1 and anti-tumor immunity in clear-cell renal cell carcinoma (ccRCC). This study aims to explore the prognostic value of PAK1 in ccRCC patients and investigated the molecular immune mechanism for its oncogenic role.
Methods: We retrospectively enrolled 282 ccRCC patients undergoing nephrectomy between 2005 and 2007 in Zhongshan hospital. Immunohistochemistry evaluated PAK1, CCL22, FOXP3 and CD8 expression in clinical specimens. Fresh tumor tissues, para-tumor tissues and peripheral blood samples for RT-PCR, ELISA, flow cytometry analyses were collected from patients who underwent nephrectomy in Zhongshan Hospital from September 2017 to April 2018. We compared clinical outcomes by Kaplan-Meier survival analysis and Cox regression model. Bioinformatics analysis performed in TCGA KIRC cohort.
Results: High PAK1 expression indicated poorer overall survival (OS) and recurrence free survival (RFS) (both p<0.001) in ccRCC patients. Multivariate analyses indicated PAK1 as an independent prognostic factor. In clinical samples, PAK1 clearly correlated with immunosuppressive microenvironment in ccRCC tissues. Significantly, PAK1 positively correlated with Tumor-infiltrating regulatory T lymphocytes (Tregs). Furthermore, IL-10+ and TGF-β+ tumor-infiltrating Tregs both increased in PAK1 high tumors. Additionally, CCL22 was highly secreted in PAK1 high tumors. After treated by IPA-3 (an PAK1 inhibitor), CCL22 secretion was clearly inhibited (p<0.001). Finally, we built a nomogram to predict overall survival for ccRCC patients with higher predictive accuracy.
Conclusions: Increased PAK1 expression predicted dismal prognosis in ccRCC patients by inducing tumor immune escape. IL-10+ and TGF-β+ tumor-infiltrating Tregs recruited by CCL22 play dominant immunosuppressive roles in PAK1 high tumors.
Tumor-infiltrating regulatory T lymphocytes orchestrate oncogenic PAK1-conferred immune evasion in clear-cell renal cell carcinoma
