Identificating cathepsin D as a biomarker for differentiation and prognosis of nasopharyngeal carcinoma by laser capture microdissection and proteomic analysis.
In this study, we applied laser capture microdissection and a proteomic approach to identify novel nasopharyngeal carcinoma (NPC) biomarkers. Proteins from pooled microdissected NPC and normal nasopharyngeal epithelial tissues (NNET) were separated by two-dimensional gel electrophoresis, and differential proteins were identified by mass spectrometry. Expression of the differential protein cathepsin D in the above two tissues as well as four NPC cell lines was determined by Western blotting. Next, siRNA was used to inhibit the expression of cathepsin D in highly metastatic NPC cell line 5-8F to examine whether it associates with NPC metastasis. Immunohistochemistry was also performed to detect the expression of cathepsin D in 72 cases of primary NPC, 28 cases of NNET, and 20 cases of cervical lymph node metastases, and the correlation of its expression level with clinicopathologic features and clinical outcomes were evaluated. Thirty-six differential proteins between the NPC and NNET were identified. The expression level of cathepsin D in the two types of tissues was confirmed by Western blotting and related to differentiation degree and metastatic potential of the NPC cell lines. Down-regulated cathepsin D expression by siRNA significantly decreased in vitro invasive ability of 5-8F cells. Significant cathepsin D down-regulation was observed in NPC versus NNET, whereas significant cathepsin D up-regulation was observed in lymph node metastasis versus primary NPC. In addition, cathepsin D down-regulation was significantly correlated with poor histological differentiation, whereas cathepsin D up-regulation was significantly correlated with advanced clinical stage, recurrence, and lymph node and distant metastasis. Furthermore, survival curves showed that patients with cathepsin D up-regulation had a poor prognosis. Multivariate analysis confirmed that cathepsin D expression was an independent prognostic indicator. The data suggest that cathepsin D is a potential biomarker for the differentiation and prognosis of NPC, and its dysregulation might play an important role in the pathogenesis of NPC.
Cheng
Ai-Lan
AL
Key Laboratory of Cancer Proteomics of Chinese Ministry of Health, Xiangya Hospital, Central South University, Changsha 410008, China.
Huang
Wei-Guo
WG
Chen
Zhu-Chu
ZC
Zhang
Peng-Fei
PF
Li
Mao-Yu
MY
Li
Feng
F
Li
Jian-Ling
JL
Li
Cui
C
Yi
Hong
H
Peng
Fang
F
Duan
Chao-Jun
CJ
Xiao
Zhi-Qiang
ZQ
D000951:Antigens, Neoplasm / Q000032:analysis / Q000378:metabolism; D015415:Biomarkers / Q000032:analysis / Q000378:metabolism*; D002402:Cathepsin D / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D003937:Diagnosis, Differential; D015180:Electrophoresis, Gel, Two-Dimensional; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D053533:Keratin-8 / Q000032:analysis / Q000378:metabolism; D007834:Lasers; D008297:Male; D013058:Mass Spectrometry / Q000379:methods; D042282:Microdissection / Q000379:methods; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000175:diagnosis / Q000201:enzymology / Q000378:metabolism*; D009305:Nasopharynx / Q000201:enzymology / Q000378:metabolism / Q000473:pathology; D009361:Neoplasm Invasiveness / Q000235:genetics; D009362:Neoplasm Metastasis / Q000473:pathology; D009367:Neoplasm Staging; D011379:Prognosis; D040901:Proteomics / Q000379:methods*; D034741:RNA, Small Interfering / Q000235:genetics; D020545:Respiratory Mucosa / Q000201:enzymology / Q000378:metabolism / Q000473:pathology; D015843:Serpins / Q000032:analysis / Q000378:metabolism; D014162:Transfection
D000951:Antigens, Neoplasm; D015415:Biomarkers; D053533:Keratin-8; D034741:RNA, Small Interfering; D015843:Serpins; C051072:squamous cell carcinoma-related antigen; D002402:Cathepsin D