Lamina-associated polypeptide 2 (LAP2) expression patterns in transformed and cancer cells

dc.contributor.advisorLeaner, Virna Den_ZA
dc.contributor.authorWard, Michelle Claireen_ZA
dc.date.accessioned2014-07-28T14:56:03Z
dc.date.available2014-07-28T14:56:03Z
dc.date.issued2009en_ZA
dc.description.abstractThe Lamina-associated polypeptide two (LAP2) proteins comprising three human isoforms, LAP2 +- LAP2β and LAP2 have been shown to provide a structural framework in the nucleus and to facilitate nuclear assembly and disassembly during the cell cycle. Expression profiling studies, using microarrays, identified elevated levels of LAP2α in cervical cancer patient material compared to normal. Altered expression of LAP2 may thus have significance in the development of certain cancers. The aim of this project was thus to independently confirm the up-regulation of LAP2α in cancer material and to determine the effect of inhibiting its expression on the biology of cancer and transformed cells. LAP2α mRNA and protein expression was shown to be elevated in cervical cancer tissue compared to normal cervical tissue by Real-time RT-PCR and immunohistochemical analysis respectively. Interestingly, LAP2 (both the LAP2α and LAP2β isoforms) was shown to be overexpressed in cervical cancer cell lines compared to a normal primary cervical epithelial cell line. Higher LAP2 expression appears to associate with cellular transformation as increased expression was observed in transformed human fibroblast cells compared to normal fibroblasts. LAP2 expression was also elevated in oesophageal cancer cell lines compared to normal suggesting that the overexpression of LAP2 associates with multiple cancer types. In order to determine the role of LAP2 in cancer cell biology, its expression was inhibited using specific siRNA molecules. Inhibition of LAP2 did not have an effect on adherent cell proliferation; however under anchorage-independent growth conditions a significant decrease in cell proliferation and colony formation was observed in LAP2 knockdown cells. This was accompanied by a decrease in cyclin D1 levels and an increase in p16 levels in LAP2 siRNA transfected cells. Our results did not conclusively show xiii that this decrease in proliferation was as a result of an alteration in the cell cycle profile or due to an increase in apoptosis. In addition, inhibition of LAP2 expression resulted in a decrease in Rb protein expression. It is proposed that LAP2 plays a role in stabilizing the Rb protein, as inhibition of LAP2 expression did not affect Rb mRNA levels but substantially reduced the protein half-life. In summary, increased LAP2 expression associates with transformed and cancer cells and suggests potential for use as a cancer biomarker. Its potential as an anti-cancer therapeutic, however requires further investigation.en_ZA
dc.identifier.apacitationWard, M. C. (2009). <i>Lamina-associated polypeptide 2 (LAP2) expression patterns in transformed and cancer cells</i>. (Thesis). University of Cape Town ,Faculty of Health Sciences ,Division of Medical Biochemistry. Retrieved from http://hdl.handle.net/11427/3153en_ZA
dc.identifier.chicagocitationWard, Michelle Claire. <i>"Lamina-associated polypeptide 2 (LAP2) expression patterns in transformed and cancer cells."</i> Thesis., University of Cape Town ,Faculty of Health Sciences ,Division of Medical Biochemistry, 2009. http://hdl.handle.net/11427/3153en_ZA
dc.identifier.citationWard, M. 2009. Lamina-associated polypeptide 2 (LAP2) expression patterns in transformed and cancer cells. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Ward, Michelle Claire AB - The Lamina-associated polypeptide two (LAP2) proteins comprising three human isoforms, LAP2 +- LAP2&Icirc;&sup2; and LAP2 have been shown to provide a structural framework in the nucleus and to facilitate nuclear assembly and disassembly during the cell cycle. Expression profiling studies, using microarrays, identified elevated levels of LAP2&Icirc;&plusmn; in cervical cancer patient material compared to normal. Altered expression of LAP2 may thus have significance in the development of certain cancers. The aim of this project was thus to independently confirm the up-regulation of LAP2&Icirc;&plusmn; in cancer material and to determine the effect of inhibiting its expression on the biology of cancer and transformed cells. LAP2&Icirc;&plusmn; mRNA and protein expression was shown to be elevated in cervical cancer tissue compared to normal cervical tissue by Real-time RT-PCR and immunohistochemical analysis respectively. Interestingly, LAP2 (both the LAP2&Icirc;&plusmn; and LAP2&Icirc;&sup2; isoforms) was shown to be overexpressed in cervical cancer cell lines compared to a normal primary cervical epithelial cell line. Higher LAP2 expression appears to associate with cellular transformation as increased expression was observed in transformed human fibroblast cells compared to normal fibroblasts. LAP2 expression was also elevated in oesophageal cancer cell lines compared to normal suggesting that the overexpression of LAP2 associates with multiple cancer types. In order to determine the role of LAP2 in cancer cell biology, its expression was inhibited using specific siRNA molecules. Inhibition of LAP2 did not have an effect on adherent cell proliferation; however under anchorage-independent growth conditions a significant decrease in cell proliferation and colony formation was observed in LAP2 knockdown cells. This was accompanied by a decrease in cyclin D1 levels and an increase in p16 levels in LAP2 siRNA transfected cells. Our results did not conclusively show xiii that this decrease in proliferation was as a result of an alteration in the cell cycle profile or due to an increase in apoptosis. In addition, inhibition of LAP2 expression resulted in a decrease in Rb protein expression. It is proposed that LAP2 plays a role in stabilizing the Rb protein, as inhibition of LAP2 expression did not affect Rb mRNA levels but substantially reduced the protein half-life. In summary, increased LAP2 expression associates with transformed and cancer cells and suggests potential for use as a cancer biomarker. Its potential as an anti-cancer therapeutic, however requires further investigation. DA - 2009 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2009 T1 - Lamina-associated polypeptide 2 (LAP2) expression patterns in transformed and cancer cells TI - Lamina-associated polypeptide 2 (LAP2) expression patterns in transformed and cancer cells UR - http://hdl.handle.net/11427/3153 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/3153
dc.identifier.vancouvercitationWard MC. Lamina-associated polypeptide 2 (LAP2) expression patterns in transformed and cancer cells. [Thesis]. University of Cape Town ,Faculty of Health Sciences ,Division of Medical Biochemistry, 2009 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/3153en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDivision of Medical Biochemistryen_ZA
dc.publisher.facultyFaculty of Health Sciencesen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherMedicineen_ZA
dc.titleLamina-associated polypeptide 2 (LAP2) expression patterns in transformed and cancer cellsen_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMScen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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