Potential Advantages of Idarubicin-Loaded Trastuzumab-Coated Liposomes for Combating Head and Neck Squamous Cancer Cells.

Objective: Head and neck squamous cell carcinoma (HNSCC) with a high mortality rate is among the most common types of cancer in the world. Human epidermal growth factor receptor 2 (HER2) is expressed higher than normal level in the most HNSCC tumors, making them resistant to chemotherapy and radiotherapy. Therefore, HER2 has been introduced as a suitable target for anticancer drugs. The aim of this study is to examine the efficacy of a treatment protocol involving targeted delivery of idarubicin encapsulated in trastuzumab-decorated liposomes to HNSCC cells.

Materials and methods: In the current experimental study, efficacies of idarubicin, prepared liposomal idarubicin, and constructed immunoliposomal idarubicin (trastuzumab-decorated) were investigated in killing HN5 cells, a HER2- overexpressing HNSCC-originating cell line. Liposomal content of idarubicin and trastuzumab were qualified by UVVisible spectroscopy and preparations were characterized for shape and size by atomic force microscopy (AFM) and dynamic light scattering (DLS). To clarify role of the missing parts of the available crystal structure (PDB ID: 1n8z) within trastuzumab-HER2 interactions, we used a 40 ns molecular dynamic simulation approach.

Results: Based on the obtained results, liposomal idarubicin showed higher toxicity of the encapsulated drug on HN5 cells compared to the traditional free drug formulations. The immunoliposomal form of idarubicin was more effective than the liposomal formulation, in killing of HN5 cells. In addition, simulation of interactions between trastuzumab and HER2 revealed that the missing parts (in the crystal structure) of HER2 have critical interaction with trastuzumab, through salt-bridges and hydrogen bonds.

Conclusion: It seems that the prepared immunoliposomes could attach more efficiently to HER2 overexpressing cells, which consequently leads to increasing cellular uptake of idarubicin through a receptor-mediated endocytosis mechanism. Moreover, simulation of the interaction between HER2 and trastuzumab suggested considerable possibilities for increasing trastuzumab affinity to HER2.