Project description:The combination of endocrine therapy (ET) with CDK4/6 inhibitors (CDK4/6i) was the most recent life-changing hallmark in metastatic Luminal breast cancer (BC). However, intrinsic and acquired resistance affect long-term efficacy. Here, we studied the role of receptor activator of nuclear factor-kB (RANK) pathway in CDK4/6i resistance. We found that RANK overexpression in Luminal BC associates with intrinsic resistance to CDK4/6i, both in vitro and in mouse xenografts. Transcriptomic analysis of mouse tumors highlighted decreased proliferation rate and chronic interferon (IFN)-response as resistance drivers.
Project description:Combining CDK4/6 inhibitors (CDK4/6i) with endocrine therapy has proven clinically effective and represents now the first-line treatment for advanced Luminal Breast Cancer (LBC) patients. However, resistance to CDK4/6i almost invariably arises in these patients, emphasising the critical need to comprehend these mechanisms and develop new strategies to overcome resistance. We report on the generation and characterisation of a LBC PDX displaying acquired resistance to CDK4/6i palbociclib. Treating a sensitive luminal BC PDX with the CDK4/6i palbociclib revealed that, despite initial tumour shrinkage, some tumours might eventually regrow under drug treatment. RNA sequencing, followed by gene set enrichment analyses, unveiled that this PDX have become refractory to CDK4/6i, both at biological and molecular level.
Project description:RANK-positive and RANK-negative luminal progenitor cells were isolated by FACS from histologically normal human breast tissue from wild-type human donors. RNA-seq gene expression profiling was used to find differentially expressed genes between the RANK-positive and RANK-negative cell populations.
Project description:CDK4/6 inhibitors are highly effective against ER+/HER2- breast cancer (BC); however, intrinsic and acquired resistance is common. Elucidating the molecular features of sensitivity and resistance to CDK4/6 inhibitors may lead to the identification of predictive biomarkers and novel therapeutic targets, paving the way toward improving patient outcomes. Parental BC cells and their endocrine-resistant derivatives (EndoR) were used in this study. Derivatives with acquired resistance to palbociclib (PalboR) were generated from parental and estrogen deprivation-resistant MCF7 and T47D cells. Transcriptomic and proteomic analyses were performed in palbociclib-sensitive and PalboR lines. We found that parental and EndoR BC lines showed varying degrees of sensitivity to palbociclib. Transcriptomic analysis of these cell lines identified an association between high Interferon (IFN) signaling and reduced sensitivity to CDK4/6 inhibitors, thus an ‘IFN-Related Palbociclib-Resistance Signature’ (IRPS) was derived. In two neoadjuvant trials of a CDK4/6 inhibitor plus endocrine therapy, IRPS and other IFN-related signatures were highly enriched in patients with tumors exhibiting intrinsic resistance to CDK4/6 inhibition. PalboR derivatives displayed a dramatic activation of IFN/STAT1-signaling compared to their short-term treated or untreated counterparts. In primary ER+/HER2- tumors, the IRPS score was significantly higher in lumB than lumA subtype and correlated with increased gene expression of immune checkpoints, endocrine resistance, and poor prognosis. Our study demonstrates that aberrant IFN-signaling is associated with intrinsic resistance to CDK4/6 inhibitors. Experimentally, acquired resistance to palbociclib is associated with activation of the IFN-pathway, which warrants additional studies to clarify its involvement in resistance to CDK4/6 inhibitors.
Project description:Despite significant improvement in therapeutic development in the past decades, breast cancer remains a formidable cause of death for women worldwide. The hormone positive subtype (HR(+)) (also known as luminal type) is the most prevalant category of breast cancer, comprising ~70% of patients. The clinical success of the three CDK4/6 inhibitors palbociclib, ribociclib, and abemaciclib has revolutionzied the treatment of choice for metastatic HR(+) breast cancer. Accumulating evidence demonstrate that the properties of CDK4/6 inhibitors extend beyond inhibition of the cell cycle, including modulation of immune function , sensitizing PI3K inhibitors, metabolism reprogramming , kinome rewiring, modulation of the proteosome, and many others. The ubiquitin–proteasome pathway (UPP) is a crucial cellular proteolytic system that maintains the homeostasis and turnover of proteins. By transcriptional profiling of the HR(+) breast cancer cell lines treated with the three CDK4/6 inhibitors, we have uncovered a novel mechanism that demonstrate the CDK4/6 inhibitors suppress the expression of three ubiquitin conjugating enzymes UBE2C, UBE2S, UBE2T. These three E2 enzymes modulate a number of E3 ubiquitin ligases, including the APC/C complex which plays a role in G1/S progression. Our study provide a novel link between CDK4/6 inhibitor and UPP which could have important implications in cancer biology.
Project description:CDK4/6 inhibitors (CDK4/6i) are effective in metastatic breast cancer, but they have been only modestly effective in most other tumor types. Here we show that tumors expressing low CDK6 rely on CDK4 function, and are exquisitely sensitive to CDK4/6i. In contrast, tumor cells expressing both CDK4 and CDK6 have increased reliance on CDK6 to ensure cell cycle progression. We discovered that CDK4/6i and CDK4/6 degraders potently bind and inhibit CDK6 selectively in tumors in which CDK6 is highly thermo-unstable and strongly associated with the HSP90/CDC37 complex. In contrast, CDK4/6i and CDK4/6 degraders are ineffective in antagonizing tumor cells expressing thermostable CDK6, due to their weaker binding to CDK6 in these cells. Thus, we uncover a general mechanism of intrinsic resistance to CDK4/6i and CDK4/6i-derived degraders and the need for novel inhibitors targeting the CDK4/6i-resistant, thermostable form of CDK6 for application as cancer therapeutics.
Project description:CDK4/6 inhibitors are used in the treatment of advanced estrogen receptor (ER)(+) breast cancer (BC). Their efficacy in ER(-) and early stage BC is currently under investigation. Here, we show that palbociclib, a CDK4/6 inhibitor, can inhibit both progression of ductal carcinoma in situ (DCIS) and growth of invasive disease in both an ER(-) basal BC model (MCFDCIS) and an ER(+) luminal model (MCF7 intraductal injection). In MCFDCIS cells palbociclib repressed cell cycle gene expression, inhibited proliferation, induced senescence and normalized tumorspheres formed in Matrigel whilst the formation of acini by normal mammary epithelial cells (MCF10A) was not affected. Palbociclib treatment of mice with MCFDCIS tumors inhibited their malignant progression and reduced proliferation of invasive lesions. Transcriptomic analysis of the tumor and stromal cell compartments showed that cell cycle and senescence genes, and MUC16, an ovarian cancer biomarker gene, were repressed during treatment. Knockdown of MUC16 in MCFDCIS cells inhibited proliferation of invasive lesions but not progression of DCIS. After cessation of palbociclib treatment genes associated with differentiation, e.g. p63, inflammation, IFNγ response and antigen processing and presentation remained suppressed in the tumor and surrounding stroma. We conclude that palbociclib can prevent progression of DCIS and is anti-proliferative in ER(-) invasive disease mediated in part via MUC16. Lasting effects of CDK4/6 inhibition after drug withdrawal on differentiation and the immune response could impact the approach to treatment of early stage ER(-) breast cancer.
Project description:The CDK4/6 kinase is dysregulated in melanoma highlighting a potential therapeutic benefit. Indeed, such CDK4/6 inhibitors are being evaluated in trials for melanoma and additional cancers. While beneficial, resistance to therapy is a concern and the molecular mechanisms of such resistance remain undefined. Here, we demonstrate that reactivation of mTORC1 signaling through increased expression of the amino acid transporter, SLC36A1, drives resistance to CDK4/6 inhibitors. Increased expression of SLC36A1 reflects two distinct mechanisms; 1) Rb loss which drives SLC36A1 via reduced suppression of E2f; 2) FXR1 overexpression which promotes SLC36A1 translation and subsequently mTORC1. Finally, we demonstrate that a combination of a CDK4/6 inhibitor with an mTORC1 inhibitor has increased therapeutic efficacy in vivo providing an important avenue for improved therapeutic intervention in aggressive melanoma.
Project description:The combination of CDK4/6 inhibitors (CDK4/6i) and endocrine therapy (ET) has significantly improved outcomes for patients with hormone receptor-positive (HR+) metastatic breast cancer. However, most patients eventually develop resistance, leading to treatment discontinuation. The therapeutic benefits of maintaining CDK4/6i or transitioning to CDK2 inhibitors (CDK2i) beyond disease progression remain unclear. Here, we show that maintaining CDK4/6i and ET or combining them with CDK2i effectively suppresses the growth of drug-resistant HR+ breast cancer cells by prolonging G1-phase progression. CDK4/6i maintenance triggers a non-canonical pathway for Rb inactivation through post-translational degradation, resulting in attenuated E2F activity and slowed G1 progression. ET further augments this effect by inhibiting c-Myc-mediated E2F amplification. Although the maintenance of CDK4/6i and ET outperforms CDK2i with ET, the triple combination of CDK4/6i, CDK2i, and ET most effectively suppresses both E2F activity and tumor growth. Moreover, while overexpression of both cyclin E and A can promote resistance to the CDK4/6i and CDK2i combination, cyclin E plays a more pivotal role in developing resistance. These findings highlight the potential of sustained CDK4/6i therapy and the incorporation of CDK2i to mitigate resistance in HR+ breast cancer.
Project description:This data set belongs to the publication 'Distinct CDK6 complexes determine tumor cell response to CDK4/6 inhibitors and degraders' from Xuewei Wu et al (PI: Poulikos I. Poulikakos) and contains the mass spectrometry files for affinity purification of endogenous CDK6 from tumor cell lines either sensitive or resistant to CDK4/6 inhibitors. The data showed a higher degree of interaction of CDK6 with components of the HSP90/CDC37 chaperoning complex in CDK4/6i-sensitive compared to CDK4/6i-resistant cells.