Abstract
Trastuzumab, the first targeted antibody against human epidermal growth factor receptor 2 (HER2), has been used to treat gastric cancer patients with HER2 overexpression. However, trastuzumab resistance often occurs following an initial period of benefits, and the underlying mechanisms remain largely unclear. The present study revealed that collagen type IV α1 chain (COL4A1), whose expression is upregulated in gastric cancer tissues and trastuzumab‑resistant gastric cancer cells, may potentially confer trastuzumab resistance in gastric cancer. By performing bioinformatics analysis of 2 microarray datasets, the present study initially identified COL4A1, overexpressed in gastric cancer tissues and trastuzumab‑resistant gastric cancer cells, as a potential candidate for inducing trastuzumab resistance. The drug resistance function of COL4A1 in gastric cancer was then validated by performing protein/gene interactions and biological process annotation analyses, and further validated by analyzing the functionality of microRNAs that target COL4A1 mRNA. Collectively, these data indicated that COL4A1 may confer trastuzumab resistance in gastric cancer.