An Anti-TAZ Monoclonal Antibody Recognizing Cell Surface Expressed TAZ Protein in Human Tumor Cells.

Background: WWTR1 or TAZ is a transcriptional co-activator protein expressed in cytoplasm which functions as the main downstream effector of the Hippo signaling pathway. This pathway is an evolutionally conserved signal cascade, which plays a pivotal role in organ size control and tumorigenesis. Ectopic expression of TAZ has already been observed in many malignancies, while the ectopic localization of TAZ is reported for the first time. The aim of this study was to produce a specific monoclonal antibody (mAb) against a synthetic peptide derived from WWTR1 protein to be used as a research tool in human carcinomas. Methods: A 21-mer synthetic peptide (derived from human TAZ protein) was used for immunization of BALB/c mice after conjugation with Keyhole Limpet Haemocyanin (KLH) using hybridoma technology. The generated mAb reacted with the immunizing peptide employing ELISA assay. The reactivity of the antibody with native TAZ protein was assessed through Western blot, immunocytochemistry, and flow cytometry using different cancer cell lines. Results: The produced mAb could recognize the immunizing peptide in ELISA and Kaff was 0.6×10-9 M. The produced anti-TAZ mAb unlike available commercial anti-TAZ antibody, was capable of specifically recognizing cell surface TAZ in human carcinoma cell lines including MCF-7, Raji, and A431 in Western blot, immunocytochemistry, and flow cytometry assays. As expected, no reactivity was observed using normal Peripheral Blood Mononuclear Cell (PBMC) from healthy donors. Conclusion: Based on the results, TAZ is ectopically expressed on the surface of tumor cell lines which is not the case in normal cells. The generated mAb has a potential to be used as a research tool in studying the expression of TAZ in human carcinomas in different applications.

A novel ADC targeting cell surface fibromodulin in a mouse model of triple-negative breast cancer.

BACKGROUND: Triple-negative breast cancers (TNBCs) are highly aggressive and metastatic. To date, finding efficacious targeted therapy molecules might be the only window of hope to cure cancer. Fibromodulin (FMOD), is ectopically highly expressed on the surface of Chronic Lymphocytic Leukemia (CLL) and bladder carcinoma cells; thus, it could be a promising molecule for targeted therapy of cancer. The objective of this study was to evaluate cell surface expression of FMOD in two TNBC cell lines and develop an antibody-drug conjugate (ADC) to target FMOD positive TNBC in vitro and in vivo. MATERIALS AND METHODS: Two TNBC-derived cell lines 4T1 and MDA-MB-231 were used in this study. The specific binding of anti-FMOD monoclonal antibody (mAb) was evaluated by flow cytometry and its internalization was verified using phAb amine reactive dye. A microtubulin inhibitor Mertansine (DM1) was used for conjugation to anti-FMOD mAb. The binding efficacy of FMOD-ADC was assessed by immunocytochemistry technique. The anti-FMOD mAb and FMOD-ADC apoptosis induction were measured using Annexin V-FITC and flow cytometry. Tumor growth inhibition of anti-FMOD mAb and FMOD-ADC was evaluated using BALB/c mice injected with 4T1 cells. RESULTS: Our results indicate that both anti-FMOD mAb and FMOD-ADC recognize cell surface FMOD molecules. FMOD-ADC could induce apoptosis in 4T1 and MDA-MB-231 cells in vitro. In vivo tumor growth inhibition was observed using FMOD-ADC in 4T1 inoculated BALB/c mice. CONCLUSION: Our results suggests high cell surface FMOD expression could be a novel bio-marker TNBCs. Furthermore, FMOD-ADC could be a promising candidate for targeting TNBCs.

Monoclonal Antibody Against Sortilin Induces Apoptosis in Human Breast Cancer Cells.

Background: Sortilin has an important role in various malignances and can be used as a promising target to eradicate cancer cells. Methods: In this study, the expression of sortilin in 4T1 and MDA-MB231 cell lines was evaluated by flow cytometry and immunocytochemistry. Apoptosis assay was also applied to evaluate apoptosis induction in 4T1 and MDA-MB231 cell lines. Results: Based on cell surface flow cytometry results, anti-sortilin (2D8-E3) mAb could recognize sortilin molecules in 79.2% and 90.3% of 4T1 and MDA-MB231 cell-lines, respectively. The immunocytochemistry staining results confirmed sortilin surface expression. Apoptosis assay indicated that anti-sortilin mAb could induce apoptosis in 4T1 and MDA-MB231 cell lines. Conclusion: Our study revealed the important role of surface sortilin in breast carcinoma cell survival and its possible application as a therapeutic agent in cancer targeted therapies.

Immunotherapy for Breast Cancer Treatment.

Breast cancer, as a heterogeneous disease, includes a wide range of pathological and clinical behaviors. Current treatment protocols, including radiotherapy, chemotherapy, and hormone replacement therapy, are mainly associated with poor response and high rate of recurrence. Therefore, more efforts are needed to develop alternative therapies for this type of cancer. Immunotherapy, as a novel strategy in cancer treatment, has a potential in treating breast cancer patients. Although breast cancer has long been considered problematic to treat with immunotherapy, as it is immunologically "cold," numerous newer preclinical and clinical reports now recommend that immunotherapy has the capability to treat breast cancer patients. In this review, we highlight the different immunotherapy strategies in breast cancer treatment.