A direct plasma assay of circulating microRNA-210 of hypoxia can identify early systemic metastasis recurrence in melanoma patients

// Shigeshi Ono 1 , Takashi Oyama 1 , Stella Lam 1 , Kelly Chong 1 , Leland J. Foshag 2 , Dave S.B. Hoon 1 1 Department of Molecular Oncology, John Wayne Cancer Institute, Providence Saint John's Health Center, Santa Monica, CA, USA 2 Division of Surgical Oncology, John Wayne Cancer Institute, Providence Saint John's Health Center, Santa Monica, CA, USA Correspondence to: Dave S.B. Hoon, e-mail: hoond@jwci.org Keywords: cell-free microRNA, diagnosis, plasma, metastatic melanoma recurrence, LDH Received: January 06, 2015      Accepted: January 10, 2015      Published: February 05, 2015 ABSTRACT Circulating cell-free(cf) microRNAs (miRNAs) have been reported to exist in plasma. MicroRNA-210(miR-210) is known to play important roles in the tumor hypoxic state. We hypothesized that the expression levels of cf-miR-210 in plasma would predict early clinical recurrence in melanoma patients. A direct miRNA assay on plasma (RT-qPCR-DP) was developed to improve cf-miRNA assay logistics, eliminate RNA extraction, and reduce specimen amount required. RNA was extracted from formalin-fixed paraffin-embedded (FFPE) melanoma tissues ( n = 108) and assessed by RT-qPCR. Plasma (10 μl; n = 264) was procured from AJCC Stage III/IV patients in phase III clinical trials. A RT-qPCR-DP was performed to detect cf-miR-210. MiR-210 was significantly higher in metastatic tumors compared to primary tumors. Cf-miR-210 was significantly higher in melanoma patients versus healthy donor controls. In serial bloods within individual patients, cf-miR-210 < 3 months prior to disease recurrence significantly increased compared to baseline levels ( p = 0.012). ROC curve analysis demonstrated that patients with elevated cf-miR-210 were more likely to have disease recurrence. Moreover, cf-miR-210 increase significantly correlated with poorer prognosis ( p < 0.001). Lactate dehydrogenase (LDH) level was also assessed within patients, and the AIC values for proportional hazards regression models of cf-miR-210(120.01) and LDH (122.91) demonstrated that cf-miR-210 is a better recurrence indicator. We concluded enhanced cf-miR-210 provides identification of early systemic melanoma recurrence.