Suberoylanilide hydroxamic acid as a radiosensitizer through modulation of RAD51 protein and inhibition of homology-directed repair in multiple myeloma.
Histone deacetylase inhibitors (HDI) have shown promise as candidate radiosensitizers for many types of cancers. However, the mechanisms of action are not well understood, and whether they could sensitize multiple myeloma (MM) to radiation therapy is unclear. In this study, we show that suberoylanilide hydroxamic acid (SAHA) at low concentrations has minimal cytotoxic effects, yet can significantly increase radiosensitivity of MM cells. SAHA seems to block RAD51 protein response to ionizing radiation, consistent with an inhibitory effect on the formation of RAD51 focus in irradiated MM cells. These effects of SAHA on RAD51 focus are independent of cell-cycle distribution changes. Furthermore, we show that SAHA selectively inhibits the homology-directed repair (HDR) pathway. The results of this study suggest that SAHA, a recently approved HDI in clinical trials for malignancies, at lower concentrations may act as a radiosensitizer via disruption of the RAD51-dependent HDR pathway.
Department of Radiation Oncology, City of Hope Cancer Center, Duarte, CA 91010, USA.
Xufeng
X
Chen
Patty
P
Wong
Eric H
EH
Radany
Jeremy M
JM
Stark
Corentin
C
Laulier
Jeffrey Y C
JY
Wong
D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D056572:Histone Deacetylase Inhibitors / Q000009:adverse effects / Q000494:pharmacology; D006801:Humans; D006877:Hydroxamic Acids / Q000009:adverse effects / Q000494:pharmacology; D009101:Multiple Myeloma / Q000188:drug therapy / Q000532:radiotherapy; D051135:Rad51 Recombinase / Q000378:metabolism*; D011838:Radiation-Sensitizing Agents / Q000009:adverse effects / Q000494:pharmacology; D059767:Recombinational DNA Repair / Q000187:drug effects / Q000235:genetics; D000077337:Vorinostat
D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D011838:Radiation-Sensitizing Agents; D000077337:Vorinostat; C495153:RAD51 protein, human; D051135:Rad51 Recombinase