Novel EBV LMP1 C-terminal Domain Binding Affibody Molecules As Potential Agents for in Vivo Molecular Imaging Diagnosis of Nasopharyngeal Carcinoma

Nasopharyngeal carcinoma (NPC) is consistently associated with Epstein-Barr virus (EBV) latent infection and is common in Southern China and Southeast Asia. The viral latent membrane proteins LMP1 and LMP2 are persistently expressed in NPC tissues; the cytoplasmic domain of LMP1 (LMP1 C-terminal) and LMP2A (LMP2A N-terminal) proteins is essential for maintenance of latency and can alter host cell signaling to facilitate tumor growth and progression. Thus, targeting LMP1 or LMP2 oncoprotein has been an increasing interest for diagnosis and targeted therapy of NPC. Affibody molecules, a new class of small-affinity engineered scaffold proteins, have demonstrated high potential for therapeutics, diagnostics, and biotechnological applications. More recently, radiolabelled HER2-specific affibody molecules have demonstrated to be useful in imaging of HER2 expressing tumor. In this study, we report three novel EBV LMP1 C-terminal (EBV LMP1-C) domain affibody molecules (ZLMP1-C15, ZLMP1-C114, and ZLMP1-C277) were selected by biopanning from a random-peptide displayed phage library and used for molecular imaging in tumor-bearing nude mice. Surface plasmon resonance (SPR), indirect immunofluorescence, and immunohistochemistry (IHC) clearly showed that all three selected affibody molecules have high affinity and specificity in binding to EBV LMP1 protein. Moreover, in vivo tumor imaging revealed that Dylight-755-labeled affibody molecules accumulated rapidly in tumor site after injection (1 h) and then were continuously maintained for 24 h in EBV-positive NPC xenograft mice model. In conclusion, our findings highlight the potential use of ZLMP1-C affibody molecules as tumor-specific molecular imaging agents of EBV-associated NPC. Key points • We screened three novel affibody molecules (ZLMP1-C15, ZLMP1-C114, and ZLMP1-C277) targeting EBV LMP1-C terminal domain • ZLMP1-C recognize the recombinant and native LMP1-C with high affinity and specificity • ZLMP1-C can be used for molecular imaging