Knockdown of PYCR1 inhibits proliferation, migration, and invasion in oesophageal squamous cell cancer by limiting its interaction with EGFR

Background: The expression and functions of pyrroline‐5‐carboxylate reductase 1 (PYCR1) in oesophageal squamous cell cancer (ESCC) are obscure. Here, we aimed to investigate the role of PYCR1 in ESCC. Methods: : Immunohistochemistry with a human oesophageal cancer tissue microarray was used to assessPYCR1 levels in ESCC tissues and RT-qPCR was used to measure PYCR1 in ESCC cell lines. PYCR1 was knocked down in ESCC cells by lentivirus transduction. Cell viability was measured by MTT assays, proliferation by the multiplication of green fluorescent protein-labelled cells, and migration and invasion of cells using wound-healing and Transwell assays, respectively, with and without extracellular matrix. Caspase 7/3 assays were used to assess apoptosis. In vivo functions of PYCR1 were investigated in xenograft mouse models and potential protein interactors were identified by mass spectrometry, bioinformatics, and coimmunoprecipitation (Co-IP), and the results were verified by rescue experiments. Results: : PYCR1 was strongly expressed in both ESCC cells and tissues and downregulation was confirmed after its knockdown. Knockdown led to reduced cellular proliferation, migration, and invasion, together with increased apoptosis. Knockdown also inhibited the growth of xenograft tumours. PYCR1 was found to coimmunoprecipitate with EGFR and rescue experiments showed that EGRF overexpression counteracted the effects of PYCR1 knockdown. Conclusions: : Upregulation of PYCR1 was observed in ESCC tissues and PYCR1 knockdown reduced tumour growth by preventing the PYCR1-EGFR interaction. This suggests that PYCR1 has oncogenic functions and may be a potential target for ESCC treatment.