Global gene expression profiling of cells overexpressing SMC3.
BACKGROUND
The Structural Maintenance of Chromosome 3 protein (SMC3) plays an essential role during the sister chromatid separation, is involved in DNA repair and recombination and participates in microtubule-mediated intracellular transport. SMC3 is frequently elevated in human colon carcinoma and overexpression of the protein transforms murine NIH3T3 fibroblasts. In order to gain insight into the mechanism of SMC3-mediated tumorigenesis a gene expression profiling was performed on human 293 cells line stably overexpressing SMC3.


RESULTS
Biotinylated complementary RNA (cRNA) was used for hybridization of a cDNAmicroarray chip harboring 18,861 65-mer oligos derived from the published dEST sequences. After filtering, the hybridization data were normalized and statistically analyzed. Sixty-five genes for which a putative function could be assigned displayed at least two-fold change in their expression level. Eighteen of the affected genes is either a transcriptional factor or is involved in DNA and chromatin related mechanisms whereas most of those involved in signal transduction are members or modulators of the ras-rho/GTPase and cAMP signaling pathways. In particular the expression of RhoB and CRE-BPa, two mediators of cellular transformation, was significantly enhanced. This association was confirmed by analyzing the RhoB and CRE-BPa transcript levels in cells transiently transfected with an SMC3 expression vector. Consistent with the idea that the activation of ras-rho/GTPase and cAMP pathways is relevant in the context of the cellular changes following SMC3 overexpression, gene transactivation through the related serum (SRE) and cAMP (CRE) cis-acting response elements was significantly increased.


CONCLUSIONS
We have documented a selective effect of the ectopic expression of SMC3 on a set of genes and transcriptional signaling pathways that are relevant for tumorigenesis. The results lead to postulate that RhoB and CRE-BPa two known oncogenic mediators whose expression is significantly increased following SMC3 overexpression play a significant role in mediating SMC3 tumorigenesis.
Ghiselli
Giancarlo
G
Department of Pathology and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA. giancarlo.ghiselli@jefferson.edu
Liu
Chang-Gong
CG
D000818:Animals; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism*; D002460:Cell Line; D049109:Cell Proliferation; D002471:Cell Transformation, Neoplastic / Q000473:pathology; D011508:Chondroitin Sulfate Proteoglycans / Q000235:genetics* / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics* / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D015894:Genome, Human / Q000235:genetics*; D006801:Humans; D051379:Mice; D020411:Oligonucleotide Array Sequence Analysis; D020218:Response Elements / Q000235:genetics; D013997:Time Factors; D014158:Transcription, Genetic / Q000235:genetics
D018797:Cell Cycle Proteins; D011508:Chondroitin Sulfate Proteoglycans; D002868:Chromosomal Proteins, Non-Histone; C492318:SMC3 protein, human; D000242:Cyclic AMP