PMID- 23405159
OWN - NLM
STAT- MEDLINE
DCOM- 20130820
LR  - 20211021
IS  - 1932-6203 (Electronic)
IS  - 1932-6203 (Linking)
VI  - 8
IP  - 2
DP  - 2013
TI  - An inverse switch in DNA base excision and strand break repair contributes to 
      melphalan resistance in multiple myeloma cells.
PG  - e55493
LID - 10.1371/journal.pone.0055493 [doi]
LID - e55493
AB  - Alterations in checkpoint and DNA repair pathways may provide adaptive mechanisms 
      contributing to acquired drug resistance. Here, we investigated the levels of 
      proteins mediating DNA damage signaling and -repair in RPMI8226 multiple myeloma 
      cells and its Melphalan-resistant derivative 8226-LR5. We observed markedly 
      reduced steady-state levels of DNA glycosylases UNG2, NEIL1 and MPG in the 
      resistant cells and cross-resistance to agents inducing their respective DNA base 
      lesions. Conversely, repair of alkali-labile sites was apparently enhanced in the 
      resistant cells, as substantiated by alkaline comet assay, autoribosylation of 
      PARP-1, and increased sensitivity to PARP-1 inhibition by 4-AN or KU58684. 
      Reduced base-excision and enhanced single-strand break repair would both 
      contribute to the observed reduction in genomic alkali-labile sites, which could 
      jeopardize productive processing of the more cytotoxic Melphalan-induced 
      interstrand DNA crosslinks (ICLs). Furthermore, we found a marked upregulation of 
      proteins in the non-homologous end-joining (NHEJ) pathway of double-strand break 
      (DSB) repair, likely contributing to the observed increase in DSB repair kinetics 
      in the resistant cells. Finally, we observed apparent upregulation of 
      ATR-signaling and downregulation of ATM-signaling in the resistant cells. This 
      was accompanied by markedly increased sensitivity towards Melphalan in the 
      presence of ATR-, DNA-PK, or CHK1/2 inhibitors whereas no sensitizing effect was 
      observed subsequent to ATM inhibition, suggesting that replication blocking 
      lesions are primary triggers of the DNA damage response in the Melphalan 
      resistant cells. In conclusion, Melphalan resistance is apparently contributed by 
      modulation of the DNA damage response at multiple levels, including 
      downregulation of specific repair pathways to avoid repair intermediates that 
      could impair efficient processing of cytotoxic ICLs and ICL-induced DSBs. This 
      study has revealed several novel candidate biomarkers for Melphalan sensitivity 
      that will be included in targeted quantitation studies in larger patient cohorts 
      to validate their value in prognosis as well as targets for replacement- or 
      adjuvant therapies.
FAU - Sousa, Mirta M L
AU  - Sousa MM
AD  - Department of Cancer Research and Molecular Medicine, Norwegian University of 
      Science and Technology (NTNU), Trondheim, Norway.
FAU - Zub, Kamila Anna
AU  - Zub KA
FAU - Aas, Per Arne
AU  - Aas PA
FAU - Hanssen-Bauer, Audun
AU  - Hanssen-Bauer A
FAU - Demirovic, Aida
AU  - Demirovic A
FAU - Sarno, Antonio
AU  - Sarno A
FAU - Tian, Erming
AU  - Tian E
FAU - Liabakk, Nina B
AU  - Liabakk NB
FAU - Slupphaug, Geir
AU  - Slupphaug G
LA  - eng
GR  - P01 CA055819/CA/NCI NIH HHS/United States
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20130206
PL  - United States
TA  - PLoS One
JT  - PloS one
JID - 101285081
RN  - 0 (Antineoplastic Agents, Alkylating)
RN  - 0 (Biomarkers, Tumor)
RN  - 88847-89-6 (8-Hydroxy-2'-Deoxyguanosine)
RN  - EC 2.4.2.30 (Poly(ADP-ribose) Polymerases)
RN  - EC 2.7.11.1 (DNA-Activated Protein Kinase)
RN  - G9481N71RO (Deoxyguanosine)
RN  - Q41OR9510P (Melphalan)
SB  - IM
MH  - 8-Hydroxy-2'-Deoxyguanosine
MH  - Antineoplastic Agents, Alkylating/*pharmacology
MH  - Apoptosis
MH  - Biomarkers, Tumor/*metabolism
MH  - Blotting, Western
MH  - Cell Cycle/genetics
MH  - Cell Proliferation
MH  - Comet Assay
MH  - DNA Breaks, Double-Stranded/*drug effects
MH  - DNA Repair/drug effects/*genetics
MH  - DNA Replication/genetics
MH  - DNA-Activated Protein Kinase
MH  - Deoxyguanosine/analogs & derivatives/metabolism
MH  - Drug Resistance, Neoplasm/*genetics
MH  - Flow Cytometry
MH  - Fluorescent Antibody Technique
MH  - Humans
MH  - Melphalan/*pharmacology
MH  - Multiple Myeloma/drug therapy/*genetics/pathology
MH  - Poly(ADP-ribose) Polymerases/metabolism
MH  - Tumor Cells, Cultured
PMC - PMC3566207
COIS- Competing Interests: The authors have declared that no competing interests exist.
EDAT- 2013/02/14 06:00
MHDA- 2013/08/21 06:00
PMCR- 2013/02/06
CRDT- 2013/02/14 06:00
PHST- 2012/09/13 00:00 [received]
PHST- 2012/12/23 00:00 [accepted]
PHST- 2013/02/14 06:00 [entrez]
PHST- 2013/02/14 06:00 [pubmed]
PHST- 2013/08/21 06:00 [medline]
PHST- 2013/02/06 00:00 [pmc-release]
AID - PONE-D-12-27809 [pii]
AID - 10.1371/journal.pone.0055493 [doi]
PST - ppublish
SO  - PLoS One. 2013;8(2):e55493. doi: 10.1371/journal.pone.0055493. Epub 2013 Feb 6.