TROP2 PROMOTES EXPRESSION OF VIMENTIN BY REGULATING E-CADHERIN AND INDUCES EMT TO PROMOTE INVASION AND METASTASIS OF NASOPHARYNGEAL CARCINOMA

Shunjin Chen^{1, #}, Fengping Wang^{2, #}, Xiaoxiao Yu³, Gang Li³, Di Jiang¹, Jintian He^{1, *}

¹Department of Otorhinolaryngology, Dongguan People’s Hospital, Dongguan, PR China - ²Department of Laboratory, Dongguan People’s Hospital, Dongguan, PR China - ³Department of Otorhinolaryngology, Southern Hospital, Guangzhou, PR China

Objective: To explore the effect of tumour-associated calcium signalling protein-2 (Trop2) on the invasion and metastasis of nasopharyngeal carcinoma and its relationship to epithelial-mesenchymal transition (EMT) as well as the possible mechanisms.

Methods: A total of 80 patients with undifferentiated nasopharyngeal carcinoma and 60 patients with benign pharyngeal benign lesions confirmed by pathology in our hospital from April 2016 to April 2019 were enrolled in the study. The expression of Trop2, E-cadherin and vimentin in nasopharyngeal carcinoma and benign lesion tissues was detected using immunohistochemical methods. A small interfering RNA vector that specifically interferes with the Trop2 gene and transient transfection of nasopharyngeal carcinoma CNE2 cells was constructed, and a low expression model of Trop2 was established. The expression of EMT-related protein, E-cadherin and vimentin in CNE2 cells following the low expression of Trop2 was determined by western blotting. The effects of low expression of Trop 2 on the migration and invasion of CNE2 cells were monitored by a transwell migration and invasion experiment.

Results: The findings of immunohistochemical staining indicated that the positive expression rate of Trop2 in nasopharyngeal carcinoma tissues was 72.50%, which is much higher than in the benign pharyngeal lesion tissues (16.67%, P<0.05). The results of western blotting showed that 48 hours after nasopharyngeal carcinoma cell CNE2 transfection, the expression of E-cadherin protein was much higher; however, the expression of vimentin protein was significantly lower in the study group than in the control group (P<0.05). The findings of the transwell migration and invasion experiment revealed that 48 hours after nasopharyngeal carcinoma cell CNE2 transfection, the number of invasive and metastatic cells was significantly lower in the observation group than in the control group (P<0.01).

Conclusions: Trop2 is highly expressed in nasopharyngeal carcinoma tissues. After knocking down Trop2 expression, the migration and invasion of nasopharyngeal carcinoma CNE2 cells are significantly reduced, and its mechanism may be related to the inhibition of EMT.