Down-regulation of an inhibitor of cell growth, transmembrane protein 34 (TMEM34), in anaplastic thyroid cancer.
OBJECTIVE
Ansaplastic thyroid cancer (ATC) is one of the most lethal malignancies, but the carcinogenic mechanism of ATC has not been clarified. Recently, we performed a cDNA microarray analysis and identified transmembrane protein 34 (TMEM34) that down-regulated in anaplastic thyroid cancer cell lines (ACL)s as compared to normal thyroid tissues.


METHODS
To investigate the role of TMEM34 in ATC carcinogenesis, we examined expression levels of TMEM34 in ACLs as well as differentiated thyroid cancers (DTC)s and normal human tissues. To explore the effect of TMEM34 in ATC development, cell-growth assays with KTA2 cells were performed.


RESULTS
Expression of TMEM34 was down-regulated in all 11 ACLs, as compared to either normal thyroid tissues or cell lines derived from papillary or follicular thyroid cancers. TMEM34 was expressed ubiquitously in normal human tissues tested. Transfection of TMEM34 into KTA2 cells led to inhibition of cell growth.


CONCLUSIONS
Our findings suggest that TMEM34 might be a tumor suppressor gene, associated with the development of ATC from DTC.
Akaishi
J
J
Department of Molecular Biology, Institute of Gerontology. Nippon Medical School, Kawasaki 211-8533, Japan. s4067@nms.ac.jp
Onda
M
M
Okamoto
J
J
Miyamoto
S
S
Nagahama
M
M
Ito
K
K
Yoshida
A
A
Shimizu
K
K
D002277:Carcinoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D048708:Cell Growth Processes / Q000235:genetics*; D045744:Cell Line, Tumor; D003001:Cloning, Molecular; D017931:DNA Primers; D015536:Down-Regulation; D020869:Gene Expression Profiling / Q000379:methods; D015972:Gene Expression Regulation, Neoplastic; D016147:Genes, Tumor Suppressor; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods; D012334:RNA, Neoplasm / Q000235:genetics / Q000302:isolation & purification; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013964:Thyroid Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D014162:Transfection; D025521:Tumor Suppressor Proteins / Q000737:chemistry / Q000378:metabolism*
D017931:DNA Primers; D008565:Membrane Proteins; D012334:RNA, Neoplasm; D025521:Tumor Suppressor Proteins; C521838:transmembrane protein 34, human