Significance of dysregulated metadherin and microRNA-375 in head and neck cancer.
OBJECTIVE
Despite recent improvements in local control of head and neck cancers (HNC), distant metastasis remains a major cause of death. Hence, further understanding of HNC biology, and in particular, the genes/pathways driving metastasis is essential to improve outcome.


METHODS
Quantitative reverse transcriptase PCR (qRT-PCR) was used to measure the expression of miR-375 and metadherin (MTDH) in HNC patient samples. Targets of miR-375 were confirmed using qRT-PCR, Western blot analysis, and luciferase assays. Phenotypic effects of miR-375 reexpression and MTDH knockdown were assessed using viability (MTS), clonogenic survival, cell migration/invasion, as well as in vivo tumor formation assays. The prognostic significance of miR-375 or MTDH in nasopharyngeal carcinoma (NPC) was determined by comparing low versus high expression groups.


RESULTS
MiR-375 expression was significantly reduced (P = 0.01), and conversely, MTDH was significantly increased (P = 0.0001) in NPC samples. qRT-PCR, Western blots, and luciferase assays corroborated MTDH as a target of miR-375. Reexpression of miR-375 and siRNA knockdown of MTDH both decreased cell viability and clonogenic survival, cell migration/invasion, as well as in vivo tumor formation. NPC patients whose tumors expressed high levels of MTDH experienced significantly lower survival and, in particular, higher distant relapse rates (5-year distant relapse rates: 26% vs. 5%; P = 0.005).


CONCLUSIONS
Dysregulation of miR-375 and MTDH may represent an important oncogenic pathway driving human HNC progression, particularly distant metastases, which is now emerging as a major cause of death for HNC patients. Hence, targeting this pathway could potentially be a novel therapeutic strategy by which HNC patient outcome could be improved.
Department of Pathology, Princess Margaret Hospital/Ontario Cancer Institute, 610 University Avenue, Toronto, Ontario, Canada, M5G 2M9.
Angela B Y
AB
Hui
Jeff P
JP
Bruce
Nehad M
NM
Alajez
Wei
W
Shi
Shijun
S
Yue
Bayardo
B
Perez-Ordonez
Wei
W
Xu
Brian
B
O'Sullivan
John
J
Waldron
Bernard
B
Cummings
Patrick
P
Gullane
Lillian
L
Siu
Fei-Fei
FF
Liu
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D015153:Blotting, Western; D015815:Cell Adhesion Molecules / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D002465:Cell Movement; D002470:Cell Survival; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006258:Head and Neck Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry; D053208:Kaplan-Meier Estimate; D008565:Membrane Proteins; D051379:Mice; D008807:Mice, Inbred BALB C; D035683:MicroRNAs / Q000235:genetics*; D008875:Middle Aged; D009374:Neoplasms, Experimental / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D034622:RNA Interference; D016601:RNA-Binding Proteins; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014183:Transplantation, Heterologous; D055815:Young Adult
D015815:Cell Adhesion Molecules; C540933:MIRN375 microRNA, human; C483039:MTDH protein, human; D008565:Membrane Proteins; D035683:MicroRNAs; D016601:RNA-Binding Proteins