Negative regulation between the expression levels of receptor for hyaluronic acid-mediated motility and hyaluronan leads to cell migration in pancreatic cancer

Receptor for hyaluronic acid (HA)-mediated motility (RHAMM) expression is upregulated in pancreatic ductal adenocarcinoma (PDAC). In the present study, small interfering RNA knockdown was used to investigate the regulatory mechanism and function of RHAMM in PDAC cells. Reverse transcription-quantitative PCR was used to measure the mRNA expression levels of RHAMM, hyaluronan synthases (HAS1, HAS2 and HAS3) and hyaluronidases (HYAL1, HYAL2 and HYAL3) in eight PDAC cell lines. Cell migration was assessed using a Transwell assay, while HA concentration was measured using an ELISA. The results revealed that RHAMM-knockdown significantly increased migration in two PDAC cell lines, significantly decreased migration in one cell line and did not affect migration in the other cell lines, and was positively associated with changes in HA production. There was a linear negative correlation between RHAMM mRNA expression and HA concentration in PDAC cells and tissues. The negative correlation between RHAMM mRNA expression and HA concentration was demonstrated in other models, including SUIT2 cells treated with an HA inhibitor or stimulator and a system involving co-culture of SUIT2 cells and stromal fibroblasts. The present findings demonstrated a negative correlation between RHAMM mRNA expression and HA production in a subset of PDAC cell lines. The efficacy of a therapeutic strategy targeting RHAMM should be carefully evaluated in future studies.