5-fluorouracil (5-FU) is a pyrimidine-like antimetabolite. It has been widely used in human cancer therapies; however, the drug sensitivity can be very low and the survival outcome can be very poor dependent on tumor types and individual heterogeneity. This research was aimed to study the effects of matrix metalloproteinase 1 (MMP1) gene on nasopharyngeal carcinoma (NPC) cell proliferation, viability, invasiveness, apoptosis, and sensitivity to 5-FU.

Bioinformatics method was used to screen out the differentiated expressed genes in nasopharyngeal carcinomas compared with normal nasopharyngeal epithelial tissues. qRT-PCR was used to determine the expression of MMP1 mRNA, and western blot was used to determine the protein expression of MMP1, thymidylate synthase (TS), and dihydropyrimidine dehydrogenase (DPD). Colony foci formation assay, CCK8 assay, and BrdU incorporation assay were used to study the cell proliferation. Transwell invasion assay was carried out to determine cell invasion. Flow cytometry and caspase 3/7 activation assay were used to detect cell apoptosis.

MMP1 gene was the most significantly upregulated gene in nasopharyngeal carcinomas according to the bioinformatics analysis. And the upregulation of MMP1 gene was confirmed in both NPC tissues and cell lines using RT-QPCR and western blot technique. When 5-FU was not a player, the forced overexpression of MMP1 gene led to enhanced growth and invasion of CNE1 and HNE1 cell lines, whereas MMP1 gene knockdown resulted in the opposite outcome. When 5-FU was added, MMP1 gene knockdown led to significantly suppressed cell proliferation and enhanced cell apoptosis. Also, MMP1 gene knockdown caused significantly lower level of TS and DPD enzymes.

Not only the knockdown of MMP1 gene led to suppressed proliferation and invasion but also increased the sensitivity to 5-FU of CNE1 and HNE1 cells. Our results provided convincing evidence that MMP1 gene knockdown could offer a favorable sensitivity approach for NPC with 5-FU treatment.