Prostate cancer C5a receptor expression and augmentation of cancer cell proliferation, invasion, and PD-L1 expression by C5a.

BACKGROUND: The treatment of castration-resistant prostate cancer (CRPC) is a urological issue. Recent studies have revealed cancer promotion via the C5a-C5a receptor (C5aR) system. To establish a new therapeutic target for CRPC, we investigated an association of the system with CRPC progression and evasion from the antitumor immune responses. METHODS: C5aR and PD-L1 were immunostained in the prostate cancer (PC) tissues. The relationship of PC C5aR expression to clinicopathological parameters was analyzed. CRPC cell lines were examined for C5aR expression by real-time reverse transcription polymerase chain reaction, immunoblotting, and flow cytometry. C5a effects were examined on CRPC cell glutamine consumption, proliferation, invasion, and PD-L1 expression. RESULTS: PC cells expressed C5aR in 83 of the 161 patients (52%) and in three of the six CRPC patients. Basal cells, but not luminal cells, of noncancerous prostate glands expressed C5aR. Three CRPC cell lines expressed C5aR. C5a increased CRPC cell glutamine consumption 2.1-fold, proliferation 1.3-1.6-fold, and invasion 2-3-fold in a C5a-concentration and a C5aR-dependent manner. High expression of C5aR did not relate to the PC patients' clinical parameters but the PD-L1-positive rate was higher in the C5aR high-expression patients (37.5%) compared to low- or no expression patients (17.8%), and double-positive PC cells were present. C5a increased CRPC cell PD-L1 production 1.4-fold and cell-surface expression 2.6-fold. CONCLUSIONS: C5aR expression of PC cells in patients' tissues and C5a augmentation of C5aR-dependent CRPC proliferation, invasion, and PD-L1 expression suggested participation of the C5a-C5aR system in CRPC promotion and evasion from antitumor immune responses. Targeting this signaling pathway may provide a useful therapeutic option for CRPC.

Association of high cellular expression and plasma concentration of angiopoietin-like 4 with tongue cancer lung metastasis and poor prognosis.

Angiopoietin-like 4 (ANGPTL4) promotes cancer cell migration through vessels and has been implicated in cancer metastasis. Our previous study identified a robust increase in ANGPTL4 mRNA expression in lung-metastasized tongue cancer (TC) cells. Therefore, the present study investigated the association of ANGPTL4 with lung metastasis and outcomes of patient with TC. ANGPTL4 expression in TC cells was investigated by immunohistochemical staining. Patients were classified into 'low (0-30%)' and 'high (>30%)' ANGPTL4-expression groups based on the proportion of ANGPTL4-positive TC cells. The high ANGPTL4-expression group included 15 of 48 patients with TC. Notably, a significantly greater proportion of patients with lung metastasis exhibited a high rate of ANGPTL4-expressing cancer cells compared with patients without lung metastasis (P=0.029). The overall 5-year survival rate was lower in the high (27%) ANGPTL4-expression group compared with the low (68%) ANGPTL4-expression group. Univariate and multivariate analyses revealed that patients with high ANGPTL4 expression in TC cells exhibited significantly lower overall survival (OS) rates [hazard ratio (HR), 2.99; 95% confidence interval (95% CI), 1.34-6.69; P=0.008 and HR, 2.72; 95% CI, 1.14-6.51; P=0.024, respectively]. High plasma ANGPTL4 concentrations as measured by ELISA were associated with lung metastasis (P<0.001). The optimal cut-point for prediction of TC lung metastasis was 9.1 ng/ml (P<0.001; 95% CI, 7.2-10.9). The OS of patients with plasma ANPTL4 above the cut-point was significantly lower than that of patients with plasma ANGPTL4 ≤9.1 ng/ml (P<0.001). These results suggest that a high level of ANGPTL4 in cancer cells and plasma may predict lung metastasis and/or a poor prognosis of patients with TC.

Enhancement of cancer invasion and growth via the C5a-C5a receptor system: Implications for cancer promotion by autoimmune diseases and association with cervical cancer invasion.

Autoimmune diseases are caused by immune complex-induced activation of the complement system and subsequent inflammation. Recent studies have revealed an association between autoimmune diseases and worse survival in patients with cancer; however, the underlying mechanism is still unknown. The C5a-C5a receptor (C5aR) system has been shown to enhance cancer activity and recruit myeloid-derived suppressor cells (MDSCs) that suppress the anti-tumor immune response. The Arthus reaction is inflammation caused by complement system activation by the immune complex and thus is a model of autoimmune diseases. To explore the effect of the Arthus reaction on cancer progression, mouse cancer cells were inoculated in syngeneic mouse skin, where the Arthus reaction was induced simultaneously. The Arthus reaction enhanced invasion and tumor growth of C5aR-positive cancer cells, but not control cells, and induced MDSC recruitment. Intravenous injection of C5a-stimulated C5aR-positive cancer cells into nude mice resulted in more lung nodules than injection of nontreated C5aR-positive cells and C5a-stimulated C5aR-negative cells, supporting C5a-C5aR-mediated enhancement of cancer growth. C5aR expression in uterine cervical carcinoma stage I cells, which invade into the deeper tissues, was significantly higher than that in CIN3 cells, which remain in the epithelium. These results indicate that cancer promotion by the C5a-C5aR system may underlie poor prognosis in cancer patients with autoimmune diseases, particularly in patients with C5aR-positive cancer, and may be associated with cervical cancer invasion. The enhancement of cancer cell invasion and growth by the C5a-C5aR system suggests that this system is a possible target of cancer therapy.

Enhancement of active MMP release and invasive activity of lymph node metastatic tongue cancer cells by elevated signaling via the TNF-α-TNFR1-NF-κB pathway and a possible involvement of angiopoietin-like 4 in lung metastasis.

To study the role of TNF-α in tongue cancer metastasis, we made highly metastatic cells from a human oral squamous cell carcinoma cell line (SAS) by repeating the passage in which the cells were injected into a nude mouse tongue and harvested from metastasized cervical lymph nodes. Cancer cells after 5 passages (GSAS/N5) increased invasive activity 7-fold in a TNF-α receptor 1 (TNFR1)-dependent manner and enhanced mRNA expression of TNF-α and TNFR1. In the highly metastatic cells, NF-κB activation was upregulated via elevated phosphorylation of Akt and Ikkα/ß in the signaling pathway and secretion of TNF-α, active MMP-2 and MMP-9 increased. Suppression of increase of TNF-α mRNA expression and MMP secretion by NF-κB inhibitor NBD peptide suggested a positive feedback loop in GSAS/N5 cells; TNF-α activates NF-κB and activated NF-κB induces further TNF-α secretion, leading to increase of active MMP release and promotion of invasion and metastasis of the cells. GSAS/N5 cells that had been injected into the nude mouse tongue and harvested from metastasized lungs multiplied angiopoietin-like 4 (angptl4) expression with enhanced migration activity, which indicated a possible involvement of angptl4 in lung metastasis of the cells. These results suggest that TNF-α and angptl4 promote metastasis of the oral cancer cells, thus, these molecules may be therapeutic targets for patients with tongue cancer.