Thalidomide down-regulates transcript levels of GC-rich promoter genes in multiple myeloma.
Thalidomide (Thd), a potent teratogen, was shown to have therapeutic potential in cancer, primarily in multiple myeloma (MM), yet its mechanism of action has not been elucidated. It was recently suggested that its teratogenicity is derived from interference in expression of genes regulated by GC-rich promoters by blocking the binding of SP1 transcription factor to its motif. We explored the validation of the proposed model by focusing on potential molecular targets associated with MM pathogenesis. Cell lines RPMI 8226, U266, and ARH-77 were exposed for 24 h to racemic Thd and analyzed for apoptosis, membranal expression of CD29 and CD63, transcript level of hTERT, CD63, and IGFI-R (characterized by GC-rich motifs) and telomerase activity. Analysis of an hTERT core promoter reporter gene expression [enhanced green fluorescent protein (EGFP)] in transiently transfected RPMI 8226 incubated with racemic and steric (+/-)-enantiomers of Thd was performed. A consistent reduction ( approximately 10-40%) in transcript levels of all three assayed genes in all three cell lines was demonstrated in the presence of racemic Thd. Significant reduction of EGFP was demonstrated in cells transfected with hTERT reporter gene and treated with racemic and (S)-Thd. Our results show that Thd's antimyeloma activity can be ascribed to the same mechanism responsible for its teratogenic effect and that the inhibition of GC-rich promoter genes is mostly attributed to the S-racemate. Indeed, this selectivity delineates GC-rich promoter genes as a unique group eligible for specific drug targeting.
Drucker
Liat
L
Oncogenetic Laboratory, Sapir Medical Center, Meir Hospital, Kfar Sava, 44281, Israel. druckerl@clalit.org.il
Uziel
Orit
O
Tohami
Tali
T
Shapiro
Hava
H
Radnay
Judith
J
Yarkoni
Shai
S
Lahav
Meir
M
Lishner
Michael
M
D025601:Adenomatous Polyposis Coli Protein / Q000235:genetics / Q000378:metabolism; D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins; D020862:GC Rich Sequence / Q000187:drug effects* / Q000235:genetics; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology; D019012:Integrin beta1 / Q000378:metabolism; D009101:Multiple Myeloma / Q000473:pathology*; D010954:Plasmacytoma; D010980:Platelet Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000187:drug effects* / Q000235:genetics; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D017451:Receptors, Somatomedin / Q000235:genetics / Q000378:metabolism; D019098:Telomerase / Q000235:genetics / Q000378:metabolism; D060149:Tetraspanin 30; D013792:Thalidomide / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D025601:Adenomatous Polyposis Coli Protein; D015703:Antigens, CD; C554586:CD63 protein, human; D004268:DNA-Binding Proteins; D007166:Immunosuppressive Agents; D019012:Integrin beta1; D010980:Platelet Membrane Glycoproteins; D012333:RNA, Messenger; D017451:Receptors, Somatomedin; D060149:Tetraspanin 30; D013792:Thalidomide; D019098:Telomerase