<i>RAB37</i> Hypermethylation Regulates Metastasis and Resistance to Docetaxel-Based Induction Chemotherapy in Nasopharyngeal Carcinoma.

Abstract

Epigenetic alterations play important roles in metastasis and drug resistance through gene regulation. However, the functional features and molecular mechanisms of epigenetic changes remain largely unclear in nasopharyngeal carcinoma (NPC) metastasis. Gene regulatory network analysis was used to identify metastatic-specific dysregulated genes between normal and NPC tissues and the expression was validated in published Gene-Expression Omnibus data set. The regulatory and functional role of <i>RAB37</i> downregulation was examined in NPC and was validated <i>in vitro</i> and <i>in vivo</i>, and downstream target of <i>RAB37</i> was explored. The clinical value of <i>RAB37</i> methylation was evaluated in NPC metastasis and chemosensitivity. We identified <i>RAB37</i> as a specific hypermethylated gene that is most commonly downregulated in NPC. Moreover, <i>RAB37</i> downregulation was attributed to hypermethylation of its promoter and was significantly associated with metastasis- and docetaxel chemoresistance-related features in NPC. Ectopic <i>RAB37</i> overexpression suppressed NPC cell metastasis and enhanced chemosensitivity to docetaxel. Mechanistically, RAB37 colocalized with TIMP2, regulated TIMP2 secretion, inhibited downstream MMP2 activity, and consequently altered NPC cell metastasis. Furthermore, <i>RAB37</i> hypermethylation was correlated with poor clinical outcomes in patients with NPC. We developed a prognostic model based on <i>RAB37</i> methylation and N stage that effectively predicted an increased risk of distant metastasis and a favorable response to docetaxel-containing induction chemotherapy (IC) in NPC patients. This study shows that <i>RAB37</i> hypermethylation is involved in NPC metastasis and chemoresistance, and that our prognostic model can identify patients who are at a high risk of distant metastasis and might benefit from for docetaxel IC.