Characteristics Of Tumor Immune Microenvironment And PEBP1 Expression In Relation To The Prognosis Of Hepatocellular Carcinoma

The immune system can both promote tumor progression or mediated tumor rejection, as a balance between pro-tumor and antitumor immunity. Tumor microenvironment plays an important role in the progression of tumor. Presumably, the local tumor immune microenvironment polarizes host immune response toward a specific phenotype, in favoring or suppressing tumor progression. However, the exact local immune status is unclear in hepatocellular carcinoma.For comprehensive immune characterization, it is also important to investigate T cells from diseased organs/tissues. We compared the immune status of different local microenvironments (peripheral circulation, peritumoral microenvironment and intratumoral microenvironment) in hepatocellular carcinoma. The present study was focused on analyzing the immunophenotypic of tumor infiltrating lymphocytes. We found the number of CD8+ T cells was significantly decreased in intratumoral microenvironment, compared with peripheral circulation and peritumoral microenvironment. We also found CD8+T cell of HCC patients expressed high level of the B and T lymphocyte attenuator (BTLA), a newly discovered coinhibitory molecule, when compared with healthy donors, indicating impaired function of CD8+T cell in HCC. Notably, we also found the enrichment of CD4+CD25+ regulatory T cells (Treg) in intratumoral microenvironment. Moreover, the highest expression level and intensity level of FoxP3 presented in CD4+CD25+ Treg in intratumoral microenvironment. We also found the inherent immunity cell of y8T to be downregulated in intratumoral microenvironment.Our results indicated that the tumor microenvironment of hepatocellular carcinoma is featured by the immunosuppressive status: Tumor immune microenvironment plays an important role in the progression of tumor. We investigated whether immune status of tumor microenvironment correlated with prognosis of hepatocellular carcinoma.Immunohistochemical staining of CD8 and Foxp3 was conducted in a set of tissue microarrays which based on a cohort of 240 hepatocellular carcinoma patients after curative resection. We used the ratio of CD8/Treg as a comprehensive index to represent the immune status of intratumoral microenvironment. Survival analysis was performed by univariate and multivariate analysis.Based on immunohistochemisty, we found that the number of CD8+ infiltrating cells was decreased and FoxP3+ infiltrating cells increased in intratumoral microenvironment, when compared with peritumoral microenvironment. The number of FoxP3+Treg was significantly associated with invasive characteristics (such as vascular invasion, poor differentiation and large size). Multivariate analysis indicated the ratio of CD8/Treg was an independent predictor for time to recurrence and overall survival time. In vitro co-culture study, we found Treg had the ability to promote the invasive potential HCC tumor cells. In conclusion, we found the immunosuppressive status of intratumoral microenvironment was an adverse index for HCC prognosis. Treg had the ability to promote the invasive potential HCC tumor cells which beyond its immunopotency. Phosphatidylethanolamine binding protein 1 (PEBP1) plays a pivotal role in cancer by regulating multiple cellular signaling processes, potentiating immune-mediated apoptosis and suppressing metastasis in animal models. We examined whether RKIP expression in hepatocellular carcinoma (HCC) correlated with the risk of recurrence and survival after resection.A randomly selected cohort of 240 Chinese HCC patients, predominantly hepatitis B-related, formed the basis of the study. PEBP1 expression levels were evaluated by immunohistochemistry and real-time reverse-transcriptase PCR. Immunostaining results of CD8+ cytotoxic to Foxp3+ regulatory T cells (Tregs) ratio was also evaluated as a comprehensive immune index in relation to PEBP1 expression. Survival analysis was performed by univariate and multivariate analysis. The results were further validated in an independent series of 403 patients. The relevance of RKIP to phospho-ERK was determined by Western blot analysis on clinical samples and HCC cell lines.We found that PEBP1 prevalently down-regulated in HCC and was significantly associated with tumor aggressiveness. Both PEBP1 mRNA and protein levels were adverse predictors for time to recurrence and patient overall survival time. The prognostic value of PEBP1 was then confirmed in the validation cohort. In addition, Western blot suggested the loss of PEBP1 led to hyperactivity of MAPK signaling. Subgroup analysis indicated that low level of PEBP1 expression in HCC aggravated the unfavorable prognosis of low intratumoral CD8+/Tregs ratio, while high level of PEBP1 expression reinforced the favorable prognosis of high intratumoral CD8+/Tregs ratio.Our current study indicated that down-regulation of RKIP in HCC was an independent predicator for poor patient outcome, which not only contributed to aggressive tumor behaviors but also may represent a tumor-intrinsic mechanism of active immune escape. The progression of hepatocellular carcinoma is controlled by both the cell-intrinsic mechanism of gene mutation and the cell-extrinsic mechanism of tumor immune microenvironment.