Anti-Tumor Effect against Human Cancer Xenografts by a Fully Human Monoclonal Antibody to a Variant 8-Epitope of CD44R1 Expressed on Cancer Stem Cells

Abstract

BackgroundCD44 is a major cellular receptor for hyaluronic acids. The stem structure of CD44 encoded by ten normal exons can be enlarged by ten variant exons (v1-v10) by alternative splicing. We have succeeded in preparing MV5 fully human IgM and its class-switched GV5 IgG monoclonal antibody (mAb) recognizing the extracellular domain of a CD44R1 isoform that contains the inserted region coded by variant (v8, v9 and v10) exons and is expressed on the surface of various human epithelial cancer cells.Methods and Principal FindingsWe demonstrated the growth inhibition of human cancer xenografts by a GV5 IgG mAb reshaped from an MV5 IgM. The epitope recognized by MV5 and GV5 was identified to a v8-coding region by the analysis of mAb binding to various recombinant CD44 proteins by enzyme-linked immunosorbent assay. GV5 showed preferential reactivity against various malignant human cells versus normal human cells assessed by flow cytometry and immunohistological analysis. When ME180 human uterine cervix carcinoma cells were subcutaneously inoculated to athymic mice with GV5, significant inhibition of tumor formation was observed. Furthermore, intraperitoneal injections of GV5markedly inhibited the growth of visible established tumors from HSC-3 human larynx carcinoma cells that had been subcutaneously transplanted one week before the first treatment with GV5. From in vitro experiments, antibody-dependent cellular cytotoxicity and internalization of CD44R1 seemed to be possible mechanisms for in vivo anti-tumor activity by GV5.ConclusionsCD44R1 is an excellent molecular target for mAb therapy of cancer, possibly superior to molecules targeted by existing therapeutic mAb, such as Trastuzumab and Cetuximab recognizing human epidermal growth factor receptor family.

Characterization of cervical cancer stem cell-like cells: phenotyping, stemness, and human papilloma virus co-receptor expression

“…Mazuko and collaborators demonstrated, in vivo, a protective effect of inhibiting the stem cell receptor CD44RI using an antibody against this isoform, in mice previously challenged with 1×10 6 cells from ME180, a human cervical cancer cell line [25]. Furthermore, Feng and collaborators evaluated the presence of CD44 and CK-17 in tumorigenic cervospheres injected into mice challenged with 100,000 total cervosphere cells [26].…”

Effect of CD44 Binding Peptide Conjugated to an Engineered Inert Matrix on Maintenance of Breast Cancer Stem Cells and Tumorsphere Formation

“…CD44 has been used for CSC detection and targeting but the mechanism of its involvement in the maintenance of CSCs is not clear. Antibodies against CD44 inhibit breast tumor growth and prevent cancer recurrence [12]. Anti-CD44 antibodies are found to induce the differentiation of acute myeloid leukemia (AML) stem cells [13].…”

NIH3T3 cells overexpressing CD98 heavy chain resist early G1 arrest and apoptosis induced by serum starvation

“…(62) Our recent data provide evidence that the expression of CD44v and its association with an xCT CD98lc block the reactive oxygen species-induced stress signaling that results in growth arrest, cell differentiation and senescence, and, thereby, promote the proliferation of cancer cells and the formation of lethal gastrointestinal tumors, (58) and that anti-CD44v fully human mAb could inhibit tumor formation or tumor growth of xenografted human cancers. (63) Given that CD44v-expressing CSC play a central role in resistance to cancer therapy, it has been suggested that definitive treatment should target the xCT-CD44v high cell population in cancer. (58) We expect that anti-CD98 therapeutic reagents will be applied to various types of human cancers, and that CD98hc/CD98lc Fig.…”