Synaptotagmin-like 5 is a potential biomarker and correlates with immune infiltrates in thyroid carcinoma

Thyroid carcinoma (TC) continues to show concerning rates of metastasis and recurrence, despite an overall favorable prognosis. This study aimed to investigate the characteristics and predictive value of synaptotagmin-like 5 (SYTL5) expression and its association with immune infiltration and potential effects on cell apoptosis and proliferation in TC. Messenger ribonucleic acid expression profiles from 45 TC samples and 37 normal samples in The Cancer Genome Atlas database were analysed. The differentially expressed gene SYTL5 was highly expressed in TC tissues and closely associated with the tumour–node–metastasis classification in TC. The receiver operating characteristic curve for predicting TC showed an area under the curve of 0.878. Immune cell expression significantly differed between SYTL5 low- and high-expression groups. Zinc-finger protein 384 (ZNF384) was predicted as the transcription factor of SYTL5 and was found to be underexpressed in TC tissues, showing a negative correlation with SYTL5. Molecular biology experiments demonstrated that SYTL5 expression was elevated in human TC cells and tissues, while SYTL5 knockdown promoted apoptosis and inhibited proliferation in vitro. Zinc-finger protein 384 was shown to bind to the promoter of SYTL5, and overexpression of SYTL5 reversed the effects of ZNF384 overexpression on TC cells. These findings indicate that SYTL5 acts as a potential oncogene in TC and may serve as a biomarker for TC diagnosis. Moreover, this study enhances our understanding of TC’s underlying mechanisms and highlights SYTL5 as a promising target for immunotherapy.