Cytokeratin-14 (CK14), also known as keratin 14, is mainly expressed in the basal layer of stratified squamous epithelium. It has a critical role in maintaining cell morphology and resisting external mechanical stress. High levels of CK14 have been found in multiple types of tumors, especially basal-like breast cancer (BLBC). In this study, an anti-CK14 monoclonal antibody was successfully produced, purified, and labeled with 99mTc to evaluate the feasibility of visualizing the CK14 level in BLBC. Higher CK14 levels were found in MDA-MB-468 cells and tumors compared with the levels in MDA-MB-231 cells and tumors as revealed by Western blotting and immunohistochemistry experiments. The high binding specificity of 99mTc-HYNIC-Anti-CK14 mAb to CK14+ BLBC cells was verified by cell uptake and blocking studies. Single-photon emission computed tomography (SPECT) images exhibited higher radioactivity accumulation in MDA-MB-468 tumors compared with MDA-MB-231 tumors. The signal in MDA-MB-468 tumors decreased significantly when 100-fold excess amounts of anti-CK14 mAb were injected 1 h prior to SPECT, further validating the high specificity of the tracer. Biodistribution study results were consistent with SPECT imaging. In conclusion, we successfully constructed a CK14 targeting tracer, 99mTc-HYNIC-Anti-CK14 mAb, which has a high binding ability to CK14+ tumors, signifying its potential value in the immunoSPECT imaging of BLBC.
Keywords: anti-CK14 monoclonal antibody; basal-like breast cancer (BLBC); cytokeratin-14 (CK14); immuno-single-photon emission computed tomography (immunoSPECT); molecular imaging; radioimmunoimaging (RII).