Project description:We identified PLK1 as a key gene methylated by METTL3 in MeRIP-sq using the sh-METTL3 cell line of MIAPaCa-2. In the present study, we evaluated the changes in gene expression paterns induced by PLK1 inhibition and METTL3-KD
Project description:Polo-like kinase 1 (PLK1) is a serine/threonine kinase required for mitosis and cytokinesis. As cancer cells are often hypersensitive to partial PLK1 inactivation, chemical inhibitors of PLK1 have been developed and tested in clinical trials. However, these molecules alone were not completely effective. PLK1 promotes numerous molecular and cellular events in the cell division cycle. To date, it is unclear which of these events most crucially depend on PLK1 activity. We used a CRISPR-based genome-wide screening strategy to identify genes whose inactivation enhances cell proliferation defects upon partial chemical inhibition of PLK1. Genes identified encode proteins that are functionally linked to PLK1 in multiple ways. Among them, factors that promote centromere and kinetochore function were clearly enriched. In particular, inactivation of the kinesin KIF18A or SKA1 in PLK1-compromised cells results in mitotic defects, activation of the spindle assembly checkpoint and nuclear reassembly defects. Our results suggest that functions of PLK1 at kinetochores are most sensitive to its inhibition, and point at KIF18A as a possible target for combinatorial therapies using existing PLK1 inhibitors.
Project description:Transcriptional profiling of mouse aortas comparing control wild-type animals with aortas from three different Plk1(+/-) mice. Goal was to determine the effects of Plk1 haploinsufficiency in aorta expression profiles.
Project description:Fibrolamellar carcinoma (FLC), a rare and fatal liver cancer lacking effective drug therapy, is driven by the DNAJ-PKAc fusion oncoprotein. However, the underlying mechanism of DNAJ-PKAc's role in FLC tumor growth remains enigmatic. Employing an unbiased systems-based approach, we uncovered a new role of DNAJ-PKAc oncoprotein in FLC and identified downstream kinases involved in this process. Functional screening, coupled with computational analysis, highlighted Polo-like kinase 1 (PLK1) as vital for FLC cell viability. Genetic and pharmacological PLK1 inhibition significantly reduced FLC cell growth, inducing apoptosis. Further studies showed DNAJ-PKAc's centrosomal presence and direct interaction with PLK1, revealing a novel mechanism that promotes PLK1 activation and mitotic progression. Clinical-grade PLK1 inhibitors effectively suppressed FLC tumor growth across multiple preclinical models, including patient-derived xenograft and an orthotopic model of FLC, suggesting promising therapeutic avenues. Our findings underscore the role of DNAJ-PKAc in rewiring signaling networks and highlight valuable clinical implications for PLK1-targeted therapies for FLC.
Project description:Polo-like kinase 1 (Plk1) is an essential protein kinase that promotes faithful mitotic progression in eukaryotes. Plk1 subcellular localization and substrate interactions are tightly controlled and require binding of Plk1 to phosphorylated sequences. Here, we use quantitative proteomics to identify phosphorylation-dependent interactions within the Plk1 network in human mitotic HeLa cells using kinase inhibitors and a Plk1 mutant deficient in phosphorylation-dependent substrate binding. We find that many interactions are abolished upon kinase inhibition; however, a subset are protected from phosphatase opposition or are unopposed, resulting in persistent Plk1-substrate interactions. This subset includes Phosphoprotein Phosphatase 6 (PP6), whose activity towards Aurora kinase A (AURKA) is inhibited by Plk1. This Plk1-PP6 interaction creates a feedback loop that coordinates and reinforces the activities of Plk1 and AURKA during mitotic entry and is terminated by Plk1 degradation during mitotic exit. Collectively, this work provides a cellular mechanism for the observed regulation of AURKA by Plk1.
Project description:Inhibitors of the mitotic kinase PLK1 yield objective responses in a subset of refractory cancers. However, PLK1 overexpression in cancer does not correlate with drug sensitivity, and the clinical development of PLK1 inhibitors has been hampered by the lack of patient selection marker. Using a high-throughput chemical screen, we discovered that cells deficient for the tumor suppressor ARID1A are highly sensitive to PLK1 inhibition. Interestingly this sensitivity was unrelated to canonical functions of PLK1 in mediating G2-M cell cycle transition. Instead, a whole-genome CRISPR screen revealed PLK1 inhibitor sensitivity in ARID1A deficient cells to be dependent on the mitochondrial translation machinery. We find that ARID1A knock-out (KO) cells have an unusual mitochondrial phenotype with aberrant biogenesis, increased oxygen consumption/ expression of oxidative phosphorylation genes, but without increased ATP production. Using expansion microscopy and biochemical fractionation, we see that a subset of PLK1 localizes to the mitochondria in interphase cells. Inhibition of PLK1 in ARID1A KO cells further uncouples oxygen consumption from ATP production, with subsequent membrane depolarization and apoptosis. Knockdown of specific subunits of the mitochondrial ribosome reverses PLK1-inhibitor induced apoptosis in ARID1A deficient cells, confirming specificity of the phenotype. Together, these findings highlight a novel interphase role for PLK1 in maintaining mitochondrial fitness under metabolic stress, and a strategy for therapeutic use of PLK1 inhibitors. To translate these findings, we describe a quantitative microscopy assay for assessment of ARID1A protein loss, which could offer a novel patient selection strategy for the clinical development of PLK1 inhibitors in cancer.
Project description:Although 3-Phosphoinositide-dependent protein kinase-1 (PDK1) has been predominately linked to PI3K-AKT pathway, it may also evoke additional signaling outputs to promote tumorigenesis. Here we report that PDK1 directly induces phosphorylation of Polo-like kinase 1 (PLK1), which in turn induces Myc phosphorylation and protein accumulation. We show that PDK1-PLK1-Myc signaling is critical for cancer cell growth and survival and small molecule inhibition of PDK1/PLK1 provides an effective approach for therapeutic targeting Myc-dependency. Intriguingly, PDK1-PLK1-Myc signaling induces an embryonic stem cell-like gene signature associated with aggressive tumor behaviors and is a robust signaling axis driving cancer stem cell (CSC) self renewal. Finally, we show that PLK1 inhibitor synergizes with mTOR inhibitor to induce synergistic anti-tumor effect in colorectal cancer by antagonizing a compensatory Myc induction. These findings identify a novel pathway in human cancer and CSC activation and provide a therapeutic strategy for targeting Myc-associated tumorigenesis and therapeutic resistance. Gene expression profiling of Human Embryonic Kidney Cells (HEK-TERV) under different conditions: PMN, PDK1, MYC and E545K
Project description:Melanoma is one of the most serious forms of skin cancer, and its increasing incidence coupled with non-lasting therapeutic options for metastatic disease highlight the need for additional novel approaches for its management. In this study, we determined the potential interactions between polo-like kinase 1 (PLK1, a serine/threonine kinase involved in mitotic regulation) and NOTCH1 (a type I transmembrane protein deciding cell fate during development) in melanoma. Employing an in-house human melanoma tissue microarray (TMA) containing multiple cases of melanomas and benign nevi, coupled with high-throughput, multispectral quantitative fluorescence imaging analysis, we found a positive correlation between PLK1 and NOTCH1 in melanoma. Further, TCGA database analysis of melanoma patients showed an association of higher mRNA levels of PLK1 and NOTCH1 with poor overall as well as disease-free survival. Next, utilizing small-molecule inhibitors of PLK1 and NOTCH (BI 6727 and MK-0752, respectively), we found a synergistic anti-proliferative response of combined treatment in multiple human melanoma cells. To determine the molecular targets of the overall and synergistic responses of combined PLK1-NOTCH inhibition, we conducted RNA-sequencing analysis employing a unique regression model with interaction terms. We identified the modulations of several key genes relevant to melanoma progression/metastasis, including MAPK, PI3K, and RAS, as well as some new genes such as Apobec3G, BTK and FCER1G which have not been well-studied in melanoma. In conclusion, our study demonstrated a synergistic anti-proliferative response of a concomitant targeting of PLK1 and NOTCH in melanoma, unravelling a potential novel therapeutic approach for detailed preclinical/clinical evaluation.
Project description:Analysis of MCF7 breast cancer cells treated with estadiol for 6 h in presence or absence of the specific PLK1 inhibitor BI2536. Together with CHIP and global phosphoproteome data, the results demonstrate a key role of PLK1 in the estrogen receptor-mediated gene response. Hormone-deprived MCF7 cells were pretreated with BI2536 or vehicle (DMSO) followed by induction with estradiol (E2) or vehicle (ethanol). RNA of each condition was analysed in triplicate on an Agilent Human genome 4x44k v2 microarray [note: MCF7_DMSO_E2_rep3 sample was a clear technical outlier (poor hybridization), and was therefore excluded from the further analysis/this record].
Project description:To investigate the function of PLK1 in the regulation of lung cancer development in mice, we performed genetic crosses to incorporate a Plk1 transgene into the KP mouse model (herein KPP) . We then performed gene expression profiling analysis using data from RNA-seq of tumors from either cohort respectively.