Expression, purification and characterisation of a human anti-CDK4 single-chain variable fragment antibody.

BACKGROUND: Cyclin-dependent kinase 4 (CDK4) when hyperactivated drives development and maintenance of most tumour types, thus prompting its use as an essential cancer treatment target and a diagnostic tool. Target-binding molecules, such as single-chain variable fragment (scFv) antibodies, hold tremendous potential for use in a wide range of cancer diagnostic and therapeutic applications. RESULTS: A human anti-CDK4 scFv antibody (AK2) derived from a human phage display library was expressed in soluble form in Escherichia coli and shown to be secreted into the culture supernatant. Next, soluble AK2 within culture supernatant was successfully purified using affinity chromatography then was shown, using enzyme-linked immunosorbent assays, to bind to recombinant human CDK4 with high affinity and specificity. Further analyses of AK2 interactions with intracellular components demonstrated that AK2 recognised and interacted specifically with endogenous CDK4 and thus could be useful for detection of CDK4 within tumour cells. CONCLUSIONS: A novel anti-CDK4 scFv antibody that can recognise and interact specifically with recombinant human CDK4 and endogenous CDK4 in tumour cells was expressed and purified successfully. These results suggest that the anti-CDK4 scFv antibody may serve as a new and promising tool for achieving CDK4-targeted diagnosis, prognosis and treatment of numerous types of cancers.