Role of miR-21 in the growth and metastasis of human salivary adenoid cystic carcinoma

Aberrant microRNA (miRNA/miR) expression has been reported in various cancer types. miR-21, which is considered to be a proto-oncogene and is frequently overexpressed in certain cancer types, has been implicated in tumorigenesis. The aim of the present study was to investigate the effect of miR-21 degradation on tumor progression and its potential mechanisms in human salivary adenoid cystic carcinoma (SACC) development. Results of reverse transcription-quantitative polymerase chain reaction analysis indicated that SACC cells with high metastatic potential (SACC-LM cells) exhibited a significantly higher expression of miR-21 compared with SACC cells with a lower metastatic potential (SACC-83 cells). In addition, following transfection of SACC-LM cells with miR-21 inhibitor, cell viability was reduced, which may be a result of reduced cell proliferation and metastasis, and the induction of apoptosis, as determined by Cell Counting Kit-8, wound healing, Matrigel invasion and flow cytometry assays. Furthermore, bioinformatics analysis indicated that programmed cell death 4 (PDCD4), phosphatase and tensin homolog deleted on chromosome ten (PTEN) and B-cell lymphoma (Bcl)-2 are potential target genes of miR-21. Therefore, western blotting was performed to investigate the expression of these proteins, and the results demonstrated that miR-21 expression level was negatively associated with PDCD4 and PTEN protein expression, and positively associated with Bcl-2 protein expression, in SACC-LM cells, indicating that miR-21 may promote SACC progression via PDCD4, PTEN and Bcl-2. In conclusion, the present study indicates that miR-21 may be a novel target for SACC therapy and provide a novel basis for the clinical treatment of SACC.