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GULP1, a potential tumor suppressor gene in ovarian tumors and its utility as a biomarker

Leonel Maldonado, Mariana Brait, Shahnaz Begum, Aditi Chatterjee, Myriam Loyo, Alvaro Barbosa, M Luana Poeta, Vito M Fazio, Angioli Roberto and Elisabetta Tarquini, et al. (2010) American Association for Cancer Research, 101st Annual meeting, Abstracts.
abstract
Identification of tumor suppressor genes (TSGs) silenced by CpG methylation uncovers the molecular mechanism of tumorigenesis and potential tumor biomarkers. GULP1, a molecule not previously related to cancer, is a cytoplasmic adaptor protein with a phosphotyrosine binding domain that plays a role in one of two partially redundant pathways that lead to the engulfment and clearance of apoptotic cells, according to several genetic studies performed in Caenorhabditis elegans. Performing a pharmacologic unmasking technique we observed that this molecule is downregulated in ovarian tumor tissues when compared to normal ovary. Ovarian cancer is the leading cause of death among gynaecological cancers worldwide, this due to the fact that women are diagnosed with advanced stage disease and because of the lack of truly sensitive/specific screening techniques and unavailability of individualized therapy. We performed an expression microarray on 15 ovarian tumor samples, 10 ovarian normal surface epithelium, 3 ovarian cancer cell lines and 3 normal cell lines. All cells have been treated with a demethylating agent which comprehensively uncovers genes silenced by promoter hypermethylation. The selection of the best candidates was based upon the differential expression between normal and tumor samples (or cell lines), them being downregulated in cancer when compared to normal, and finally the re-activation after the treatment with the demethylating agent. One of these promising genes was GULP1, which expression pattern was then assessed by Reverse Transcriptase PCR and Western Blot and compared to its methylation status in the same six ovarian cell lines and showed correlation between absence of expression and presence of methylation (or the opposite situation). We developed quantitative fluorogenic methylation specific PCR (QMSP) for GULP1 and profiled 437 ovarian tumor samples, 17 borderline tumors, 19 cystadenoma samples and 13 normal ovarian samples, finding 34.7% (151/437), 11.7% (2/17), 10.5% (2/19) and 0% (0/13) of methylation frequency, respectively, (establishing an empiric cutoff). Using fisher´s exact test, we observe a significant increase in methylation when comparing tumors with cystadenomas and normals (p=0.0439 and p=0.0131, respectively). Late stage tumors also showed a higher frequency of methylation versus early stage (p=0.004). So far, we have demonstrated reduced log growth rates after transiently overexpressing GULP1 in one ovarian cell line (IGROVCP). To assess its potential as a TSG, we have ongoing experiments to assess its biological function as ectopic overexpression of this gene in ovarian cancer cell lines as well as creating knock downs using shRNAs. These preliminary data indicate that GULP1 may be an ovarian cancer biomarker. Further studies on the biology of this gene are needed to evaluate its potential as a TSG and its role in ovarian cancer carcinogenesis.
Please use this url to cite or link to this publication:
author
organization
year
type
conference
publication status
published
subject
keyword
methylation, GULP1, ovarian cancer, biomarker
in
American Association for Cancer Research, 101st Annual meeting, Abstracts
publisher
American Association for Cancer Research (AACC)
conference name
101st Annual meeting of the American Association for Cancer Research (AACC 2010)
conference location
Washington, DC, USA
conference start
2010-04-17
conference end
2010-04-21
language
English
UGent publication?
no
classification
C3
id
1148146
handle
http://hdl.handle.net/1854/LU-1148146
alternative location
http://www.abstractsonline.com/Plan/ViewAbstract.aspx?mID=2521&sKey=e485c59f-bc1b-4fff-89f0-bb3cdb59cf4e&cKey=be5af0cc-0dd3-48e0-a446-030613fc94c8&mKey=%7B0591FA3B-AFEF-49D2-8E65-55F41EE8117E%7D
date created
2011-02-12 10:48:59
date last changed
2011-03-31 16:15:46
@inproceedings{1148146,
  abstract     = {Identification of tumor suppressor genes (TSGs) silenced by CpG methylation uncovers the molecular mechanism of tumorigenesis and potential tumor biomarkers.
GULP1, a molecule not previously related to cancer, is a cytoplasmic adaptor protein with a phosphotyrosine binding domain that plays a role in one of two partially redundant pathways that lead to the engulfment and clearance of apoptotic cells, according to several genetic studies performed in Caenorhabditis elegans.
Performing a pharmacologic unmasking technique we observed that this molecule is downregulated in ovarian tumor tissues when compared to normal ovary. Ovarian cancer is the leading cause of death among gynaecological cancers worldwide, this due to the fact that women are diagnosed with advanced stage disease and because of the lack of truly sensitive/specific screening techniques and unavailability of individualized therapy.
We performed an expression microarray on 15 ovarian tumor samples, 10 ovarian normal surface epithelium, 3 ovarian cancer cell lines and 3 normal cell lines. All cells have been treated with a demethylating agent which comprehensively uncovers genes silenced by promoter hypermethylation. The selection of the best candidates was based upon the differential expression between normal and tumor samples (or cell lines), them being downregulated in cancer when compared to normal, and finally the re-activation after the treatment with the demethylating agent.
One of these promising genes was GULP1, which expression pattern was then assessed by Reverse Transcriptase PCR and Western Blot and compared to its methylation status in the same six ovarian cell lines and showed correlation between absence of expression and presence of methylation (or the opposite situation).
We developed quantitative fluorogenic methylation specific PCR (QMSP) for GULP1 and profiled 437 ovarian tumor samples, 17 borderline tumors, 19 cystadenoma samples and 13 normal ovarian samples, finding 34.7\% (151/437), 11.7\% (2/17), 10.5\% (2/19) and 0\% (0/13) of methylation frequency, respectively, (establishing an empiric cutoff). Using fisher{\textasciiacute}s exact test, we observe a significant increase in methylation when comparing tumors with cystadenomas and normals (p=0.0439 and p=0.0131, respectively). Late stage tumors also showed a higher frequency of methylation versus early stage (p=0.004).
So far, we have demonstrated reduced log growth rates after transiently overexpressing GULP1 in one ovarian cell line (IGROVCP). To assess its potential as a TSG, we have ongoing experiments to assess its biological function as ectopic overexpression of this gene in ovarian cancer cell lines as well as creating knock downs using shRNAs.
These preliminary data indicate that GULP1 may be an ovarian cancer biomarker. Further studies on the biology of this gene are needed to evaluate its potential as a TSG and its role in ovarian cancer carcinogenesis.},
  author       = {Maldonado, Leonel and Brait, Mariana and Begum, Shahnaz and Chatterjee, Aditi and Loyo, Myriam and Barbosa, Alvaro and Poeta, M Luana and Fazio, Vito M and Roberto, Angioli and Tarquini, Elisabetta and Van Criekinge, Wim and Ongenaert, Mat{\'e} and Wisman, G Bea A and de Graeff, Pauline and Van der Zee, Ate and Sidransky, David and Hoque, Mohammad},
  booktitle    = {American Association for Cancer Research, 101st Annual meeting, Abstracts},
  keyword      = {methylation,GULP1,ovarian cancer,biomarker},
  language     = {eng},
  location     = {Washington, DC, USA},
  publisher    = {American Association for Cancer Research (AACC)},
  title        = {GULP1, a potential tumor suppressor gene in ovarian tumors and its utility as a biomarker},
  url          = {http://www.abstractsonline.com/Plan/ViewAbstract.aspx?mID=2521\&sKey=e485c59f-bc1b-4fff-89f0-bb3cdb59cf4e\&cKey=be5af0cc-0dd3-48e0-a446-030613fc94c8\&mKey=\%7B0591FA3B-AFEF-49D2-8E65-55F41EE8117E\%7D},
  year         = {2010},
}

Chicago
Maldonado, Leonel, Mariana Brait, Shahnaz Begum, Aditi Chatterjee, Myriam Loyo, Alvaro Barbosa, M Luana Poeta, et al. 2010. “GULP1, a Potential Tumor Suppressor Gene in Ovarian Tumors and Its Utility as a Biomarker.” In American Association for Cancer Research, 101st Annual Meeting, Abstracts. American Association for Cancer Research (AACC).
APA
Maldonado, L., Brait, M., Begum, S., Chatterjee, A., Loyo, M., Barbosa, A., Poeta, M. L., et al. (2010). GULP1, a potential tumor suppressor gene in ovarian tumors and its utility as a biomarker. American Association for Cancer Research, 101st Annual meeting, Abstracts. Presented at the 101st Annual meeting of the American Association for Cancer Research (AACC 2010), American Association for Cancer Research (AACC).
Vancouver
1.
Maldonado L, Brait M, Begum S, Chatterjee A, Loyo M, Barbosa A, et al. GULP1, a potential tumor suppressor gene in ovarian tumors and its utility as a biomarker. American Association for Cancer Research, 101st Annual meeting, Abstracts. American Association for Cancer Research (AACC); 2010.
MLA
Maldonado, Leonel, Mariana Brait, Shahnaz Begum, et al. “GULP1, a Potential Tumor Suppressor Gene in Ovarian Tumors and Its Utility as a Biomarker.” American Association for Cancer Research, 101st Annual Meeting, Abstracts. American Association for Cancer Research (AACC), 2010. Print.