title: Overexpression of PAX5 induces apoptosis in multiple myeloma cells.
abstract: PAX5 is an essential transcription factor for the commitment of lymphoid progenitors to the B-lymphocyte lineage. PAX5 suppression results in retrodifferentiation of B lymphocytes to an uncommitted progenitor cell stage, whereas PAX5 suppression in mature B lymphocytes leads to further development into plasma cells. Here, we have analyzed the fate of plasma cell lines following PAX5 reexpression. Human B cell lines were infected with Ad5/F35 adenoviruses encoding either EYFP or PAX5. Expression analysis of specific plasma cell transcription factors (IRF4, Blimp-1 and XBP-1) suggests that PAX5 reexpression does not induce retrodifferentiation of plasma cells into B lymphocytes. Interestingly, the viability of RPMI-8226 and U266 multiple myeloma cell lines markedly declined at 4-7 days post-transduction, whereas other plasma cell lines maintained their viability. Apoptosis analysis through Annexin V measurement also revealed a higher level of apoptosis in PAX5-expressing myeloma cell lines. Finally, Western blot analysis of pro- and anti-apoptotic proteins revealed that the anti-apoptotic protein MCL-1 was down-modulated in PAX5-transduced multiple myeloma cell lines. In conclusion, our results show that the expression of PAX5 in plasma cell lines induces apoptosis exclusively in multiple myelomas. This might represent a potential therapeutic avenue in the treatment of multiple myeloma.
authors.affiliation: Héma-Québec, Quebec, G1V 5C3, QC, Canada.
authors.forename: Maryse
authors.initials: M
authors.lastname: Proulx
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Cayer
authors.forename: Mathieu
authors.initials: M
authors.lastname: Drouin
authors.forename: André
authors.initials: A
authors.lastname: Laroche
authors.forename: Daniel
authors.initials: D
authors.lastname: Jung
mesh_terms: D017209:Apoptosis; D045744:Cell Line, Tumor; D002470:Cell Survival; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D009101:Multiple Myeloma / Q000235:genetics / Q000378:metabolism*; D051757:PAX5 Transcription Factor / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics
chemical_list: D051757:PAX5 Transcription Factor; C497281:PAX5 protein, human; D014157:Transcription Factors