gms | German Medical Science

Objective: Glioblastoma (GBM) is the most aggressive form of brain cancers. Yet, there is still no targeted therapy clinically approved to prolong survival time of the patients.

Carbonic anhydrase XII (CA XII) is highly expressed on glioma cells while being absent from normal brain. Given the strong association between CA XII and brain cancer, better understanding of CA XII inhibitory monoclonal antibody, termed 6A10, might help in developing future therapy.

Methods: We studied the effect of 6A10 on a pathophysiological stem cell disease model platform in vitro. Cells were treated up to 4 days with 25µg/ml of testing antibody 6A10 that specifically targets CA XII epitope. Further functional assays were conducted, such as quantification of cell proliferation using Ki67 assay, apoptosis by Annexin V and caspase 3/7 assay as well as PI-based cell cycle analysis as well as appreciation of tumorigenicity using Soft agar assay as well as cell invasion using transwell assay. Effects on the regulation on a series of biomarkers indicating stemness was conducted via RT-qPCR and Western blot. Clinical significance of findings are validated by interrogating patient bioinformatics data from public sources.

Results: Elevated CA XII mRNA levels are negative prognostic value for predicting overall survival of brain cancer patients. No association to CD133, MGMT promoter methylation status is detected. In addition, experimental data reveal the growth-limiting effect of the 6A10 antibody to some extent on GBM in vitro. Additionally, it significantly reduces ZEB1, a critical stemness regulator, and significantly impaired the invasive feature of GBM1 cell line. Of note, a trend of CA XII upregulation was observed in all treated cell lines, which might indicate a negative feedback regulation in response to 6A10 treatment.

Conclusion: 6A10 antibody might be a promising drug candidate in glioblastoma. However, in vivo experiments are needed for further confirmation. Moreover, the characterization of the biological meaning of observed upregulation of target upon treatment is warranted to appreciate risk of emergence of therapy resistance in stem cells of GBM.