ARRDC3 Inhibits the Progression of Human Prostate Cancer Through ARRDC3-ITGß4 Pathway.

BACKGROUND: Arrestin domain-containing protein 3 (ARRDC3) is a member of the mammalian α-arrestins family, which has been identified as a tumor suppressor gene in human breast cancer, but its functions are still not clear in human prostate cancer (PCa). OBJECTIVE: The purpose of the present study was to investigate clinical significance, biological functions and underlying mechanisms of ARRDC3 deregulation in PCa. METHOD: Involvement of ARRDC3 deregulation in malignant phenotypes of PCa was demonstrated by clinical sample evaluation, microarray analysis, and in vitro and in vivo experiments. The mechanisms underlying its regulatory effect on tumor progression were determined. RESULTS: Microarray analysis found that ARRDC3 low expression was significantly associated with high Gleason score in TMA, and the expression level of ARRDC3 was negatively correlated with Gleason score, metastasis and biochemical recurrence in online Taylor Dataset. As revealed by the dataset, Kaplan-Meier analyses revealed that the biochemical recurrence-free survival (BCR-free) time of PCa patients with ARRDC3 high expression was longer than those with ARRDC3 low expression. Additionally, both univariate and multivariate analyses showed that the downregulation of ARRDC3 was an independent prognostic marker for BCR-free survival of patients with PCa. In vitro studies revealed that ARRDC3 could inhibit proliferation, migration and invasion of PCa cell lines. In vivo studies proved that ARRDC3 over-expressing cells formed significantly larger tumor nodules and remarkably speeded up tumor xenografts growth compared with the controls. Moreover, immunohistochemical scores of Ki67 and MMP-9 were significantly lower than those of the control group. Finally, correlation analysis indicated that the expression of ARRDC3 was negatively correlated with ITGß4 in clinical PCa tissues and cell lines. CONCLUSION: Our data revealed that ARRDC3 can serve as a tumor suppressor to inhibit PCa progression and an independent marker to predict the risk of biochemical recurrence and metastasis after radical resection of PCa.

Prognostic value of ZFP36 and SOCS3 expressions in human prostate cancer.

PURPOSE: ZFP36 ring finger protein (ZFP36) and the suppressor of cytokine signaling 3 (SOCS3) have been reported to, respectively, regulate NF-κB and STAT3 signaling pathways. To better understand the correlation of NF-κB and STAT3 negative regulates pathway, we have investigated the involvement of ZFP36 and SOCS3 expressions in human prostate cancer (PCa). METHODS: In the present study, paired patient tissue microarrays were analyzed by immunohistochemistry, and the ZFP36 protein expression was quantitated as immunoreactive scores in patients with PCa. Associations between ZFP36/SOCS3 expression and various clinicopathological features and prognosis of PCa patients were statistically analyzed based on the Taylor database. Then, the functions of ZFP36 and SOCS3 in cancerous inflammation were determined using qPCR and immunohistochemistry in vitro and in vivo. RESULTS: ZFP36 protein expression in PCa tissues was significantly lower than those in non-cancerous prostate tissues (P < 0.05). In mRNA level, ZFP36 and SOCS3 had a close correlation with each other (P < 0.01, Pearson r = 0.848), and its upregulation was both significantly associated with low Gleason score (P < 0.001 and P < 0.001, respectively), negative metastasis (P < 0.001 and P < 0.001, respectively), favorable overall survival (P < 0.001 and P < 0.05, respectively), and negative biochemical recurrence (P < 0.001 and P < 0.001, respectively). Functionally, LPS treatment could lead to the overexpression of ZFP36 and SOCS3 in vitro and vivo. CONCLUSIONS: Our data offer the convincing evidence for the first time that the aberrant expressions of ZFP36 and SOCS3 may be involved into the progression and patients' prognosis of PCa, implying their potentials as candidate markers of this cancer.

Biodistribution of a benzoporphyrin derivative-monoclonal antibody conjugate in A549-tumor-bearing nude mice.

Biodistribution of the photosensitizer benzoporphyrin derivative monoacid ring A (BPD) was compared in DBA/2 mice bearing the syngeneic M-1 tumor and nude mice bearing the A549 human squamous cell carcinoma. These studies, using internally labeled 14C-BPD showed that in general, biodistribution between the two strains was equivalent with the exception of two tissues; lymph nodes (BPD levels were higher in nude mice) and tumor (BPD levels were lower in nude mice). Further studies were carried out in A549-tumor-bearing nude mice in which the biodistribution of BPD conjugated to a monoclonal antibody (5E8) with specificity for an antigen on A549 cells was compared to a conjugate prepared with an irrelevant monoclonal antibody (T48). These studies showed that both conjugates had biodistribution characteristics which distinguished them from free BPD in that they remained in the circulation and most tissues for significantly longer times than did free BPD. Also, with the exception of the 5E8-BPD conjugate and A549 tumor tissue, levels in all tissues were highest at the 3-h time point following injection of conjugates. In the case of A549 tumor and the 5E8-BPD conjugate the highest concentration of 14C-labeled material was observed at the 14-h time point following injection. The results reported herein show that the conjugates tested behaved differently from free BPD, indicating that the materials did not become dissociated in vivo and that the specific conjugate (5E8-BPD) demonstrated specificity for the A549 tumor in terms of the kinetics of its accumulation in tumor tissue.

Photodynamic killing of human squamous cell carcinoma cells using a monoclonal antibody-photosensitizer conjugate.

We have developed procedures in which the photosensitizer benzoporphyrin derivative monoacid ring A (BPD) can be covalently linked to carrier molecules of modified polyvinyl alcohol (PVA) to produce water-soluble PVA-BPD conjugates with a molecular mass in the range of 30 kd. These carriers can subsequently be covalently linked to monoclonal antibodies (MoAbs) using heterobifunctional linking agents. We describe here such a conjugate in which the MoAb (5E8) has specificity for a glycoprotein detected on human squamous cell carcinomas of the lung. We provide evidence that the conjugates produced were covalently linked and retained both their photosensitizing and antigen-binding activities. We show further that the MoAb-PVA-BPD conjugate, in the presence of 10% fetal calf serum, exhibited highly enhanced phototoxic killing of the target cell line (A549) over that exhibited by free BPD or a control MoAb-PVA-BPD conjugate. These results demonstrate, therefore, both the selectivity and specificity of this MoAb conjugate.

Development of technology for linking photosensitizers to a model monoclonal antibody.

A procedure is described whereby the photosensitizer, benzoporphyrin derivative monoacid ring A (BPD-MA) was covalently linked to a model monoclonal antibody in a manner which is reproducible, quantifiable, and retains both the biological activity of the antibody and the cytotoxicity of the photosensitizer. Preliminary steps involved the linkage of BPD-MA to a modified polyvinyl alcohol (PVA) backbone, followed by conjugation to the antibody using heterobifunctional linking technology. Briefly, polyvinyl alcohol (MW ca. 10,000) was modified with 2-fluoro-1-methyl pyridinium toluene-4-sulfonate and 1,6-hexanediamine to produce side chains containing free amino groups. The free carboxyl group of BPD-MA was utilized to conjugate photosensitizer molecules to modified PVA using a standard carbodiimide reaction. Final linkage of the PVA-BPD to a model monoclonal antibody involved further substitution of the carrier with 3-mercaptopropionic acid and carbodiimide to introduce 3-4 sulfhydryl residues per carrier molecule, and introduction of sulfo-m-maleimidobenzoyl-N-hydroxysulfosuccinimide ester residues to the monoclonal (3-4 residues/molecule). Conjugation was effected by reaction of the two species at pH 5.5 for 18 h. Detailed methodology and tests for efficacy of the procedure are provided.