PARP1 promotes tumor proliferation in lenalidomide-resistant multiple myeloma via the downregulation of microRNA-192-5p-AKT signaling

Background: Lenalidomide-based therapies are recommended as first-line treatment for multiple myeloma (MM) patients, regardless of the transplant eligibility. Resistance to lenalidomide is a clinical problem that urgently needs to be addressed. The expression of poly(ADP-ribose) polymerase 1 (PARP1) is abnormally high in a variety of tumor tissues including MM. However, in lenalidomide-resistant MM, it is not yet known whether the abnormally high expression of PARP1 is involved in the occurrence of drug resistance, and whether the inhibition of PARP1 can reverse lenalidomide resistance. The aim of this study was to investigate the mechanism of PARP1 promoting lenalidomide-resistant in MM patients.

Methods: Samples of bone marrow from patients with MM who were sensitive or resistant to lenalidomide were collected. The expression levels of PARP1 at the messenger RNA and protein levels were detected through polymerase chain reaction and western blot. MM cell lines were cultivated in vitro, cell lines resistant to lenalidomide were screened out, and the expression levels of PARP1 in the resistant cell lines were detected. The apoptosis level was also detected in the lenalidomide-resistant MM cell lines treated with a PARP1 inhibitor. The proliferation rates of the two groups of cells at different time points were evaluated by mono-methyl terephthalate (MMT) experiments. Finally, the effect of PARP1 on the proliferation of lenalidomide-resistant MM through the microRNA-192-5p-AKT signaling pathway was analyzed.

Results: In the lenalidomide-resistant cell lines, the expression level of PARP1 was higher, the proliferation more rapid, and the apoptosis rate was lower than lenalidomide-sensitive cell lines. Additionally, the activated AKT pathway was suppressed by downregulating the expression of microRNA-192-5p. MM resistance can be inhibited to some extent by impacting PARP1.

Conclusions: PARP1 is involved in the production of lenalidomide resistance in MM, and could serve as a potential target for the treatment of MM in the future.