Antitumor activity of a newly developed monoclonal antibody against ROR1 in ovarian cancer cells Antitumor activity of a newly developed monoclonal antibody against ROR1 in ovarian cancer cells

Endometrial cancer (EC) is the most common form of malignant gynecological tumor. Treatment with cisplatin (CDDP) is the mainstay of EC chemotherapy. The apoptotic machinery is regarded as an important etiological factor in chemoresistance. Recent evidence has suggested that overexpression of the transcription factor SOX17 prevented apoptosis in tumor cell lines. The effect of SOX17 on apoptosis in EC cisplatin chemoresistance remains unclear. Immunohistochemistry and the reverse transcription-polymerase chain reaction were employed to detect gene expression in paraffin-embedded EC tissues and blood samples. The anti-proliferative ability of SOX17 on EC cells was assessed by MTT. Flow cytometric analysis was used to detect cell apoptosis by annexin V/PI double-staining. The expression of apoptosis-related proteins was analyzed by western blot. In the in vivo study, nude mice were subcutaneously injected with EC cells, and received cisplatin treatment through intraperitoneal chemotherapy. Apoptosis of in vivo samples was analyzed by TUNEL assay. SOX17 expression decreased the chemical resistance of EC cells to CDDP. HEC-1B cells with an elevated expression of SOX17 had a lower cell viability and higher apoptosis rate after cisplatin exposure. Overexpression SOX17 up-regulated wild type p53 after being exposed to cisplatin, while the expression of BCL2-associated X protein and cleaved caspase-3 simultaneously increased. Caspase-9 inhibitor reduced the efficacy of SOX17 in HEC-1B cells after cisplatin treatment. In the in vivo study, SOX17 overexpression clearly restrained the tumor growth and increased the cisplatin toxicity and apoptosis of tumor cells. SOX17 is involved in the p53-mediated apoptosis pathway, and increases the sensitivity of HEC-1B cells to cisplatin.

Over-expression of Receptor-tyrosine-kinase-like Orphan Receptor 1 (ROR1) in cancer cells has been reported in the context of several tumors (including ovarian cancer) and is associated with poor prognosis. The aim of this study was to construct a fully chimeric anti-ROR1 IgG antibody (ROR1-IgG) and investigate its antitumor activity against ovarian cancer cells, bothin vitro and in vivo. A fully chimeric anti-ROR1 IgG antibody (ROR1-IgG) eukaryotic expression vector was constructed and ROR1-IgG antibody was expressed in CHO cells. The characteristics of ROR1-IgG were investigated by ELISA, SPR, Western blotting, FACS and fluorescence staining analyses. CCK8 and wound healing assays were performed to determine inhibition and migration capacity of ovarian cancer cells after treatment with ROR1-IgGin vitro. Further, the antitumor activity of ROR1-IgG was assessed in vivo using tumor-mice xenograft model. The results showed that ROR1-IgG could specifically bind to ROR1-positive cells (HO8910 and A2780) with a high affinity. Functional studies revealed that ROR1-IgG inhibited the malignant behavior of ROR1-positive cells (HO8910 and A2780) in a time- and dose-dependent manner. These effects were not observed in ROR1-negative lose386 cells. The tumor inhibition rates following treatment with low, medium, and high concentrations of ROR1-IgG were approximately 47.72%, 53.79%, and 60.51%, respectively. In addition, the expression of Bcl-2 was obviously reduced while that of Bax was distinctly elevated in xenografts. Collectively, our findings suggest that ROR1-IgG may be a novel therapeutic agent for patients with ROR1-positive ovarian cancer.