title: Role of neurofilament light polypeptide in head and neck cancer chemoresistance.
abstract: Resistance to cisplatin-based chemotherapy is responsible for therapeutic failure of many common human cancers including cancer of head and neck (HNC). Mechanisms underlying cisplatin resistance remain unclear. In this study, we identified neurofilament light polypeptide (NEFL) as a novel hypermethylated gene associated with resistance to cisplatin-based chemotherapy in HNC. Analysis of 14 HNC cell lines revealed that downregulation of NEFL expression significantly correlated with increased resistance to cisplatin. Hypermethylation of NEFL promoter CpG islands was observed in cell lines as examined by bisulfite DNA sequencing and methylation-specific PCR (MSP) and tightly correlated with reduced NEFL mRNA and protein expression. Furthermore, in patient samples with HNC (n = 51) analyzed by quantitative MSP, NEFL promoter hypermethylation was associated with resistance to cisplatin-based chemotherapy [relative risk (RR), 3.045; 95% confidence interval (CI), 1.459-6.355; P = 0.007] and predicted diminished overall and disease-free survival for patients treated with cisplatin-based chemotherapy. Knockdown of NEFL by siRNA in the highly cisplatin-sensitive cell line PCI13 increased (P < 0.01) resistance to cisplatin. In cisplatin-resistant O11 and SCC25cp cells, restored expression of NEFL significantly increased sensitivity to the drug. Furthermore, NEFL physically associated with tuberous sclerosis complex 1 (TSC1), a known inhibitor of the mTOR pathway, and NEFL downregulation led to functional activation of mTOR pathway and consequentially conferred cisplatin resistance. This is the first study to show a role for NEFL in HNC chemoresistance. Our findings suggest that NEFL methylation is a novel mechanism for HNC chemoresistance and may represent a candidate biomarker predictive of chemotherapeutic response and survival in patients with HNC.
authors.affiliation: Medical Sciences Program, Indiana University School of Medicine, Jordan Hall 104, 1001 E. Third St., Bloomington, IN 47405, USA.
authors.forename: Baishen
authors.initials: B
authors.lastname: Chen
authors.forename: Ju
authors.initials: J
authors.lastname: Chen
authors.forename: Michael G
authors.initials: MG
authors.lastname: House
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Cullen
authors.forename: Kenneth P
authors.initials: KP
authors.lastname: Nephew
authors.forename: Zhongmin
authors.initials: Z
authors.lastname: Guo
mesh_terms: D045744:Cell Line, Tumor; D002945:Cisplatin / Q000494:pharmacology / Q000627:therapeutic use; D019175:DNA Methylation / Q000187:drug effects / Q000235:genetics; D015536:Down-Regulation / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000187:drug effects / Q000235:genetics; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D020868:Gene Silencing / Q000187:drug effects; D006258:Head and Neck Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D016900:Neurofilament Proteins / Q000235:genetics / Q000378:metabolism*; D010455:Peptides / Q000235:genetics / Q000378:metabolism*; D011379:Prognosis; D011401:Promoter Regions, Genetic; D011485:Protein Binding / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D016019:Survival Analysis; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism; D000077004:Tuberous Sclerosis Complex 1 Protein; D025521:Tumor Suppressor Proteins / Q000378:metabolism
chemical_list: D016900:Neurofilament Proteins; D010455:Peptides; D012333:RNA, Messenger; C000624650:TSC1 protein, human; D000077004:Tuberous Sclerosis Complex 1 Protein; D025521:Tumor Suppressor Proteins; C044882:neurofilament protein L; D058570:TOR Serine-Threonine Kinases; D002945:Cisplatin