Characterization of a novel epigenetically-silenced, growth-suppressive gene, ADAMTS9, and its association with lymph node metastases in nasopharyngeal carcinoma.
By using a functional complementation approach, suppression of tumorigenicity was observed after transfer of intact or truncated copies of chromosome 3 into a nasopharyngeal carcinoma (NPC) HONE1 cell line. The extra exogenous chromosome 3 in the microcell hybrids (MCHs) significantly extended the lag period of tumor formation, which may be associated with loss or inactivation of wild type alleles from the normal donor chromosome 3. Representative tumors, which grew in nude mice were reconstituted into culture and expanded as tumor segregants (TSs). In our study, a disintegrin-like and metalloprotease with thrombospondin type 1 motif 9 (ADAMTS9), a gene mapping to 3p14.2, was identified to be critically associated with tumor suppression in NPC. Gene expression analysis showed that ADAMTS9 was either not expressed or was downregulated in HONE1 cells, TSs and NPC cell lines. The mechanism of ADAMTS9 gene inactivation in the NPC cell lines and tissues was attributed to promoter hypermethylation. Using a tissue microarray and immunohistochemical staining, 31 of 66 (47%) of the NPC cases showed downregulated or absence of ADAMTS9 expression. ADAMTS9 expression was downregulated or lost in 17 of 23 (73.9%) lymph node metastatic NPC specimens, which was significantly higher than in 14 of 43 (32.6%) primary tumors. After transfection of the ADAMTS9 gene into 7 NPC cell lines, a dramatic reduction of colony forming ability was observed. These findings support ADAMTS9 as a putative tumor suppressor gene in vivo in NPC that is significantly associated with lymph node metastases.
Lung
Hong Lok
HL
Department of Biology and Center for Cancer Research, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (SAR), People's Republic of China.
Lo
Paulisally Hau Yi
PHY
Department of Biology and Center for Cancer Research, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (SAR), People's Republic of China.
Xie
Dan
D
State Key Laboratory of Oncology in Southern China, Cancer Center, Sun Yat-Sen University, Guangzhou, People's Republic of China.
Apte
Suneel S
SS
Department of Biomedical Engineering and Orthopedic Research Center, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH.
Cheung
Arthur Kwok Leung
AKL
Department of Biology and Center for Cancer Research, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (SAR), People's Republic of China.
Cheng
Yue
Y
Department of Biology and Center for Cancer Research, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (SAR), People's Republic of China.|City of Hope, Beckman Research Institute, Department of Biology, 1500 East Duarte Road, Duarte, CA.
Law
Evan Wai Lok
EWL
Department of Biology and Center for Cancer Research, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (SAR), People's Republic of China.
Chua
Daniel
D
Department of Clinical Oncology, University of Hong Kong, Pokfulam, Hong Kong (SAR), People's Republic of China.
Zeng
Yi-Xin
YX
State Key Laboratory of Oncology in Southern China, Cancer Center, Sun Yat-Sen University, Guangzhou, People's Republic of China.
Tsao
Sai Wah
SW
Department of Anatomy, University of Hong Kong, Pokfulam, Hong Kong (SAR), People's Republic of China.
Stanbridge
Eric J
EJ
Department of Microbiology and Molecular Genetics, University of California, Irvine, CA.
Lung
Maria Li
ML
Department of Biology and Center for Cancer Research, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (SAR), People's Republic of China.
D051722:ADAM Proteins / Q000235:genetics*; D000071119:ADAMTS9 Protein; D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000235:genetics; D002277:Carcinoma / Q000235:genetics* / Q000556:secondary; D002893:Chromosomes, Human, Pair 3; D015536:Down-Regulation; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D005838:Genotype; D006801:Humans; D007150:Immunohistochemistry; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis; D008297:Male; D046228:Microarray Analysis; D018895:Microsatellite Repeats; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000235:genetics* / Q000473:pathology; D020133:Reverse Transcriptase Polymerase Chain Reaction
D014408:Biomarkers, Tumor; D051722:ADAM Proteins; D000071119:ADAMTS9 Protein; C412869:ADAMTS9 protein, human