GSE162403
Proteomic profiling reveals CDK6 upregulation as a targetable resistance mechanism for lenalidomide in multiple myeloma
Multiple myeloma is a genetically heterogeneous disease of plasma cells. The thalidomide analog lenalidomide is a mainstay in the treatment of multiple myeloma and is used in combination with other drugs such as corticosteroids, chemotherapy and proteasome inhibitors, achieving high remission rates. However, most patients relapse due to acquired resistance of the malignant cells. Genetic analyses have revealed mutations in CRBN, the target of all IMiDs, as a resistance mechanism in 10% of patients, while for the majority of cases, the mechanism of resistance is unknown. Here, we performed integrated global quantitative tandem mass tag (TMT)-based proteomic and phosphoproteomic analyses and RNA sequencing in five paired pre-treatment and relapse samples from multiple myeloma patients. These analyses revealed proteins highly upregulated at relapse, including TRIP13, RRM1 and CDK6, which was not reflected on the RNA expression level. Overexpression of CDK6 in multiple myeloma cell lines reduced sensitivity to lenalidomide and pomalidomide in a kinase-dependent fashion. CDK6 inactivation by palbociclib or a CDK6-specific proteolysis targeting chimera (PROTAC) plus lenalidomide or pomalidomide was highly synergistic. Proteomic analyses in cell lines revealed that CDK6 inhibition reverses a complex protein resistance signature including RRM1 and TRIP13 and in combination with IMiDs promotes metabolic remodeling and c-MYC downregulation .  In conclusion, our global proteomic analyses identified CDK6 upregulation as a drug target to overcome lenalidomide resistance in multiple myeloma. Overall design: mRNA profiles of CD138+ (Multiple Myelom) were generated using TruSeq RNA Exome (TruSeq RNA Access Kit) (Illumina) followed by sequencing with 50 bp single-end reads on HiSeq 2000.