A novel alkylating agent Melflufen induces irreversible DNA damage and cytotoxicity in multiple myeloma cells

• Our prior study utilized both invitro and invivo multiple myeloma (MM) xenograft models to show that a novel alkylator melphalan-flufenamide (Melflufen) is a more potent anti-MM agent than melphalan and overcomes conventional drug resistance. Here we examined whether this potent anti-MM activity of melflufen versus melphalan is due to their differential effect on DNA damage and repair signalling pathways via -H2AX/ATR/CHK1/Ku80. Melflufen-induced apoptosis was associated with dose- and time-dependent rapid phosphorylation of -H2AX. Melflufen induces -H2AX, ATR, and CHK1 as early as after 2h exposure in both melphalan-sensitive and -resistant cells. However, melphalan induces -H2AX in melphalan-sensitive cells at 6h and 24h; no -H2AX induction was observed in melphalan-resistant cells even after 24h exposure. Similar kinetics was observed for ATR and CHK1 in meflufen- versus melphalan-treated cells. DNA repair is linked to melphalan-resistance; and importantly, we found that melphalan, but not melflufen, upregulates Ku80 that repairs DNA double-strand breaks. Washout experiments showed that a brief (2h) exposure of MM cells to melflufen is sufficient to initiate an irreversible DNA damage and cytotoxicity. Our data therefore suggest that melflufen triggers a rapid, robust, and an irreversible DNA damage which may account for its ability to overcome melphalan-resistance in MM cells.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Hematologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Hematology (hsv//eng)

Nyckelord

Myeloma

apoptosis

novel therapeutics

alkylating agents

melflufen

melphalan

Publikations- och innehållstyp

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