CDK4 overexpression is a predictive biomarker for resistance to conventional chemotherapy in patients with osteosarcoma

Abstract

Osteosarcoma (OS) is the most common malignant bone tumor, and its sensitivity to preoperative chemotherapy is a significant prognostic factor. The present study aimed to identify potential genomic markers for the prediction of chemosensitivity in patients with OS using a genomic approach. A total of 50 pediatric and adolescent patients diagnosed with high-grade OS were selected. Each pre-therapeutic biopsy sample was subjected to comparative genomic hybridization array analysis and targeted exome sequencing. Although no recurrent gene mutation was observed in chemoresistant tumors, copy number analysis detected recurrent gain of chromosome 12q14.1, which was significantly more frequent (5/21; 24%) in the poor responder cohort than in the good responder cohort (0/29; 0%; P<0.01). Subsequent expression analysis revealed that CDK4 was the only gene in the 12q14.1 gained region with an expression level that was positively associated with copy number gains. In order to elucidate the effect of CDK4 on drug sensitivity, CDK4-overexpressing OS cell lines were treated with cisplatin (CDDP); significant attenuation of CDDP sensitivity, demonstrated by increased cell viability and decreased expression of cleaved caspase-9, was induced by enforced expression of CDK4. In addition, treatment with CDK4/6 inhibitor palbociclib in CDK4-overexpressing U2OS cells facilitated apoptosis and a significant decrease in cell viability in a dose-dependent manner. In conclusion, the results of the present study showed that higher expression and amplification of CDK4 in tumors is a predictive biomarker for resistance to conventional chemotherapy in patients with OS and that palbociclib is a promising drug for this therapeutically challenging cohort.

Target actionability review to evaluate CDK4/6 as a therapeutic target in paediatric solid and brain tumours

“…CDKN2A mutations did also not correlate with CDK4/6 inhibitor sensitivity in RMS [44], whereas knockdown of p16INK4a (one of the genes encoded by the CDKN2A locus) did significantly increase the sensitivity of one MRT cell line to palbociclib [32]. In OS, there is some evidence that pRb function and CDK4 levels correlate with sensitivity [16,39]. In ATRT cell lines, on the other hand, there was no correlation with CDK4 but with cyclin D1 [34].…”

An overview of resistance to chemotherapy in osteosarcoma and future perspectives

“…In patients with OS, genes of the VEGF pathway are amplified; the most frequent copy-number aberration is the amplification at 6p12-21 that involves VEGFA (27%), and a subset of tumors had amplifications in 4q11-12, including platelet-derived growth factor receptor A (PDGFRA) and kinase insert domain receptor (KDR) (18%). These findings suggest angiogenesis as a target in OS [46] . The activation of this pathway in OS affects survival outcomes.…”

“…For example, following the overexpression of murine double minute 2 (MDM2) (a downstream mediator of p53) in tumor cells, p53-mediated apoptosis is inhibited, and cells develop resistance to DNA-damaging agents [18,45] . The amplification of MDM2 is present in 20% of OS cells [46] .…”

“…The activity of this kinase is restricted to the G1-S phase, and it is responsible for the phosphorylation of the retinoblastoma (RB) protein. The amplification of CDK4 is found in 20% of OS cells [46] . In a study of 50 pediatric and adolescent patients diagnosed with high-grade OS, the copy number analysis detected a recurrent gain of chromosome 12q14.1.…”

Juvenile trabecular ossifying fibroma: Immunohistochemical expression of MDM2, CDK4 and p53 compared to conventional ossifying fibroma

“…In particular, co-amplification of MDM2 and CDK4 is more prevalent in the low-grade parosteal OS (67%) compared to high-grade classical OS (12%) ( 8 ), showing a correlation between amplification levels and tumor grading and progression in the former group ( 29 ). Noticeably, CDK4 amplification and overexpression may serve as a useful predictive biomarker of chemoresistance in patients with OS ( 30 ).…”