Telomerase inhibition and cell growth arrest by G-quadruplex interactive agent in multiple myeloma.
OBJECTIVE
The aim of this study was to test the efficacy of telomerase inhibitor (TMPyP4 [tetra(N-methyl-4-pyridyl)-porphyrin chloride]; a G-quadruplex-intercalating porphyrin) as a potential therapeutic agent for multiple myeloma.


METHODS
We studied telomere length, telomerase activity, and effect of telomerase inhibition in multiple myeloma cells. Several myeloma cell lines were analyzed for telomerase activity, telomere length, and gene expression. Three myeloma cell lines (U266, ARH77, and ARD) were treated with TMPyP4 for 3-4 weeks. Viable cell number was assessed by trypan blue exclusion, and nature of cell death was determined by annexin labeling and/or DNA fragmentation. In situ oligo ligation technique was used to identify specific DNase I-type DNA cleavage.


RESULTS
We report high telomerase activity and shortened telomeres in myeloma cells compared to normal B cells. We have also observed inhibition of telomerase activity, reduction in telomere length, and decline of myeloma cell growth, as measured by trypan blue dye exclusion, following exposure to TMPyP4. Exposure to porphyrin reduced telomerase activity of U266, ARH77, and ARD myeloma cells by 98%, 92%, and 99%, respectively. Exposure to porphyrin had no effect on viability for the first 14 days, followed by death of 75-90% of cells over the next 2 weeks. The nature of cell death was apoptotic, as determined by annexin and DNA nick labeling. Majority of cells showed DNA fragmentation specific to caspase-3-activated DNase I.


CONCLUSIONS
These results demonstrate anti-proliferative activity of G-quadruplex-intercalating agents, and suggest telomerase as an important therapeutic target for myeloma therapy.
Shammas
Masood A
MA
Boston VA Health Care System, West Roxbury, MA, USA.
Shmookler Reis
Robert J
RJ
Akiyama
Masaharu
M
Koley
Hemanta
H
Chauhan
Dharminder
D
Hideshima
Teru
T
Goyal
Raj K
RK
Hurley
Laurence H
LH
Anderson
Kenneth C
KC
Munshi
Nikhil C
NC
D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D002455:Cell Division / Q000187:drug effects; D004247:DNA / Q000378:metabolism*; D003850:Deoxyribonuclease I / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D054856:G-Quadruplexes; D006801:Humans; D009101:Multiple Myeloma / Q000378:metabolism / Q000473:pathology*; D011166:Porphyrins / Q000494:pharmacology*; D019098:Telomerase / Q000037:antagonists & inhibitors* / Q000187:drug effects / Q000378:metabolism; D016615:Telomere / Q000378:metabolism*; D014407:Tumor Cells, Cultured / Q000187:drug effects
D000970:Antineoplastic Agents; D004791:Enzyme Inhibitors; D011166:Porphyrins; C021096:tetra(4-N-methylpyridyl)porphine; D004247:DNA; D019098:Telomerase; D003850:Deoxyribonuclease I