Copy number analysis of OVCAR-3 and CDK2 resistant sublines
Ontology highlight
ABSTRACT: Cyclin E1 (CCNE1) is amplified in various tumor types including high-grade serous ovarian cancer where it is associated with poor clinical outcome. We have demonstrate that suppression of the Cyclin E1 partner kinase, CDK2, induces apoptosis in a CCNE1 amplicon-dependent manner. Little is known of mechanisms of resistance to CDK inhibitors. We therefore generated OVCAR-3 sublines with reduced sensitivity to CDK2 inhibitors and profiled by SNP copy number microarrays.
Project description:Cyclin E1 (CCNE1) is amplified in various tumor types including high-grade serous ovarian cancer where it is associated with poor clinical outcome. We have demonstrate that suppression of the Cyclin E1 partner kinase, CDK2, induces apoptosis in a CCNE1 amplicon-dependent manner. Little is known of mechanisms of resistance to CDK inhibitors. We therefore generated OVCAR-3 sublines with reduced sensitivity to CDK2 inhibitors and profiled by SNP copy number microarrays. Arrayed samples included parental OVCAR-3 cells and five independently derived sublines resistant to PHA-533533 (OVCAR3-533533-R1, -R3, -R5, -R6, -R7). The resistant cell lines were arrayed after drug selection (P5).
Project description:Cyclin E1 (CCNE1) is amplified in various tumor types including high-grade serous ovarian cancer where it is associated with poor clinical outcome. We have demonstrate that suppression of the Cyclin E1 partner kinase, CDK2, induces apoptosis in a CCNE1 amplicon-dependent manner. Little is known of mechanisms of resistance to CDK inhibitors. We therefore generated OVCAR-3 sublines with reduced sensitivity to CDK2 inhibitors and profiled by gene expression microarrays.
Project description:Cyclin E1 (CCNE1) is amplified in various tumor types including high-grade serous ovarian cancer where it is associated with poor clinical outcome. We have demonstrate that suppression of the Cyclin E1 partner kinase, CDK2, induces apoptosis in a CCNE1 amplicon-dependent manner. Little is known of mechanisms of resistance to CDK inhibitors. We therefore generated OVCAR-3 sublines with reduced sensitivity to CDK2 inhibitors and profiled by gene expression microarrays. Arrayed samples included parental OVCAR-3 cells (n = 4 replicates) and five independently derived sublines resistant to PHA-533533 (OVCAR3-533533-R1, -R3, -R5, -R6, -R7). The resistant cell lines were arrayed after drug selection (P5) and after continued passage in the absence of inhibitor (P10+).
Project description:Cyclin dependent kinase 2 (CDK2) regulate cell cycle and is an emerging target for cancer therapy. There are relatively small numbers of tumor models that exhibit strong dependence on CDK2 and undergo G1 cell cycle arrest following CDK2 inhibition. The expression of P16INK4A and cyclin E1 determines this sensitivity to CDK2 inhibition. The co-expression of these genes occurs in breast cancer patients highlighting their clinical significance as predictive biomarkers for CDK2-targeted therapies. In cancer models that are genetically independent of CDK2; pharmacological inhibitors suppress cell proliferation by inducing 4N cell cycle arrest and increasing the expressions of phospho-CDK1 (Y15) and cyclin B1. CRISPR screens identifiy CDK2 loss as a mediator of resistance to INX-315. Furthermore, CDK2 deletion reverses the G2/M block induced by CDK2 inhibitors and restores cell proliferation. Complementary drug screens define multiple means to cooperate with CDK2 inhibition beyond G1/S. These include the depletion of mitotic regulators as well as CDK4/6 inhibitors cooperate with CDK2 inhibition in multiple phases of the cell cycle. Overall, this study underscores two fundamentally distinct features of response to CDK2 inhibitors that are conditioned by tumor context and could serve as the basis for differential therapeutic strategies in a wide range of cancers.
Project description:The selective CDK2 inhibitor BLU-222 was evaluated for mechanisms of response in the context of ovarian and breast cancer models. Using sensors of cellular CDK activity, it was found that sensitivity to either CDK4/6 or CDK2 inhibition is related to the differential dependence on a single CDK for G1/S transition. Unlike CDK4/6 inhibitors, BLU-222 was able to robustly inhibit proliferation through cell cycle inhibition in both G1 and G2 phases. However, it remained possible for cells to re-enter the cell cycle upon drug withdrawal. The anti-proliferative strength and impact on G1/S versus G2/M accumulation was found to be mediated by the RB tumor suppressor, as determined by functional perturbation strategies. To broaden the sensitivity to CDK2 inhibition, combinatorial drug screens were performed that identified both synergistic (e.g., CDK4/6 inhibitors) and antagonistic (e.g., WEE1 inhibitors) relationships. Models that were exceptionally sensitive to CDK2 inhibition displayed coordinate expression of Cyclin E1 and P16INK4A, an endogenous CDK4/6 inhibitor. Functional studies demonstrated that P16INK4A and CDK4/6 activity were key mediators of sensitivity to BLU-222. Clinical gene and protein expression analysis revealed a positive correlation between Cyclin E1 and P16INK4A and that ~25% of ovarian cancers exhibited coordinate expression of Cyclin E, P16INK4A, and RB, indicative of strong sensitivity to CDK2 inhibition. Together, this work advances a precision strategy for the use of CDK2 inhibitors in the context of ovarian and breast cancers.
Project description:Cyclin dependent kinase 2 (CDK2) regulate cell cycle and is an emerging target for cancer therapy. There are relatively small numbers of tumor models that exhibit strong dependence on CDK2 and undergo G1 cell cycle arrest following CDK2 inhibition. The expression of P16INK4A and cyclin E1 determines this sensitivity to CDK2 inhibition. The co-expression of these genes occurs in breast cancer patients highlighting their clinical significance as predictive biomarkers for CDK2-targeted therapies. In cancer models that are genetically independent of CDK2; pharmacological inhibitors suppress cell proliferation by inducing 4N cell cycle arrest and increasing the expressions of phospho-CDK1 (Y15) and cyclin B1. CRISPR screens identifiy CDK2 loss as a mediator of resistance to INX-315. Furthermore, CDK2 deletion reverses the G2/M block induced by CDK2 inhibitors and restores cell proliferation. Complementary drug screens define multiple means to cooperate with CDK2 inhibition beyond G1/S. These include the depletion of mitotic regulators as well as CDK4/6 inhibitors cooperate with CDK2 inhibition in multiple phases of the cell cycle. Overall, this study underscores two fundamentally distinct features of response to CDK2 inhibitors that are conditioned by tumor context and could serve as the basis for differential therapeutic strategies in a wide range of cancers.
Project description:High-grade serous ovarian cancers (HGSOC) are genomically complex, heterogeneous cancers with a high mortality rate, due to acquired chemoresistance and lack of targeted therapy options. Cyclin-dependent kinase inhibitors (CDKi) target the retinoblastoma (RB) signaling network, and have been successfully incorporated into treatment regimens for breast and other cancers. Here, we have compared mechanisms of response and resistance to three CDKi that target either CDK4/6 or CDK2 and abrogate E2F target gene expression. We identify CCNE1 gain and RB1 loss as mechanisms of resistance to CDK4/6 inhibition, whereas receptor tyrosine kinase (RTK) and RAS signaling is associated with CDK2 inhibitor resistance. Mechanistically, we show that ETS factors are mediators of RTK/RAS signaling that cooperate with E2F in cell cycle progression. Consequently, CDK2 inhibition sensitizes cyclin E1-driven but not RAS-driven ovarian cancer cells to platinum-based chemotherapy. In summary, this study outlines a rational approach for incorporating CDKi into treatment regimens for HGSOC. For parental HEY, two replicates per condition (control=10%, SNS032-treated, PD0332991-treated) were analyzed. For CDKi-resistant cells, two individual subclones derived from single cells were analyzed, except OAW28 sublines (two polyclonal populations per subline), OV90-PD/SNS-R (two polyclonal populations) and OV90-SNS-R-1 (polyclonal population, whereas OV90-SNS-R-2 is derived from a single colony).
Project description:High-grade serous ovarian cancers (HGSOC) are genomically complex, heterogeneous cancers with a high mortality rate, due to acquired chemoresistance and lack of targeted therapy options. Cyclin-dependent kinase inhibitors (CDKi) target the retinoblastoma (RB) signaling network, and have been successfully incorporated into treatment regimens for breast and other cancers. Here, we have compared mechanisms of response and resistance to three CDKi that target either CDK4/6 or CDK2 and abrogate E2F target gene expression. We identify CCNE1 gain and RB1 loss as mechanisms of resistance to CDK4/6 inhibition, whereas receptor tyrosine kinase (RTK) and RAS signaling is associated with CDK2 inhibitor resistance. Mechanistically, we show that ETS factors are mediators of RTK/RAS signaling that cooperate with E2F in cell cycle progression. Consequently, CDK2 inhibition sensitizes cyclin E1-driven but not RAS-driven ovarian cancer cells to platinum-based chemotherapy. In summary, this study outlines a rational approach for incorporating CDKi into treatment regimens for HGSOC.
Project description:More than half of the ∼20,000 protein-encoding human genes have at least one paralog. Chemical proteomics has uncovered many electrophile-sensitive cysteines that are exclusive to a subset of paralogous proteins. Here, we explore whether such covalent compound-cysteine interactions can be used to discover ligandable pockets in paralogs that lack the cysteine. Leveraging the covalent ligandability of C109 in the cyclin CCNE2, we mutated the corresponding residue in paralog CCNE1 to cysteine (N112C) and found through activity-based protein profiling (ABPP) that this mutant reacts stereoselectively and site-specifically with tryptoline acrylamides. We then converted the tryptoline acrylamide-N112C-CCNE1 interaction into a NanoBRET-ABPP assay capable of identifying compounds that reversibly inhibit both N112C- and WT-CCNE1:CDK2 complexes. X-ray crystallography revealed a cryptic allosteric pocket at the CCNE1:CDK2 interface adjacent to N112 that binds the reversible inhibitors. Our findings thus provide a roadmap for leveraging electrophile-cysteine interactions to extend the ligandability of the proteome beyond covalent chemistry.