Differentially expressed genes in asbestos-induced tumorigenic human bronchial epithelial cells: implication for mechanism.
Although exposure to asbestos fibers is associated with the development of lung cancer, the underlying mechanism(s) remains unclear. Using human papillomavirus-immortalized human bronchial epithelial (BEP2D) cells, we previously showed that UICC chrysotiles can malignantly transform these cells in a stepwise fashion before they become tumorigenic in nude mice. In the present study we used cDNA expression arrays to screen differentially expressed genes among the tumorigenic cells. A total of 15 genes were identified, 11 of which were further confirmed by northern blot. Expression levels of these genes were then determined among transformed BEP2D cells at different stages of the neoplastic process, including non-tumorigenic cells that were resistant to serum-induced terminal differentiation, early and late passage transformed BEP2D cells, five representative tumor cell lines and fused tumorigenic-control cell lines which were no longer tumorigenic. A consistent 2- to 3-fold down-regulation of the DCC (deleted in colon cancer), Ku70 and heat shock protein 27 genes were detected in all the independently generated tumor cell lines while expression levels in early transformants as well as in the fusion cell lines remained normal. In contrast, all the tumor cell lines examined demonstrated 2- to 4-fold overexpression of the insulin receptor and its signal transduction genes. Differential expression of these genes was completely restored in the fusion cell lines examined. No alteration in c-jun or EGF receptor expression was found in any of the cell lines. Our data suggest that activation of the insulin receptor pathway and inactivation of DCC and Ku70 may cooperate in malignant transformation of BEP2D cells induced by asbestos.
Zhao
Y L
YL
Center for Radiological Research, College of Physicians & Surgeons of Columbia University, VC11-218, 630 West 168th Street, New York, NY 10032, USA.
Piao
C Q
CQ
Wu
L J
LJ
Suzuki
M
M
Hei
T K
TK
D000818:Animals; D034961:Antigens, Nuclear; D017632:Asbestos, Serpentine / Q000009:adverse effects*; D015152:Blotting, Northern; D001980:Bronchi / Q000187:drug effects / Q000473:pathology / Q000821:virology; D015815:Cell Adhesion Molecules / Q000096:biosynthesis / Q000235:genetics; D002459:Cell Fusion; D002461:Cell Line, Transformed; D002471:Cell Transformation, Neoplastic / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D000075389:DCC Receptor; D004265:DNA Helicases; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics; D015536:Down-Regulation; D004847:Epithelial Cells / Q000187:drug effects / Q000473:pathology / Q000821:virology; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D000072200:Ku Autoantigen; D008175:Lung Neoplasms / Q000209:etiology* / Q000235:genetics* / Q000378:metabolism; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009687:Nuclear Proteins / Q000096:biosynthesis / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D027383:Papillomaviridae; D010641:Phenotype; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis / Q000235:genetics; D011972:Receptor, Insulin / Q000096:biosynthesis / Q000235:genetics; D011956:Receptors, Cell Surface; D025521:Tumor Suppressor Proteins
D034961:Antigens, Nuclear; D017632:Asbestos, Serpentine; D015815:Cell Adhesion Molecules; D000075389:DCC Receptor; C501909:DCC protein, human; D004268:DNA-Binding Proteins; C501910:Dcc protein, mouse; D009687:Nuclear Proteins; D011956:Receptors, Cell Surface; D025521:Tumor Suppressor Proteins; D011972:Receptor, Insulin; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D017346:Protein Serine-Threonine Kinases; D004265:DNA Helicases; C106893:XRCC5 protein, human; C000606509:Xrcc6 protein, human; C000606510:Xrcc6 protein, mouse; D000072200:Ku Autoantigen