Project description:Polo-like kinase 1 (PLK1), a serine/threonine kinase and important cell cycle regulator, is overexpressed in melanoma and its expression has been associated with poor disease prognosis. PLK1 has been shown to interact with NUMB, a NOTCH antagonist. However, the exact role of PLK1-NUMB-NOTCH axis in epithelial-mesenchymal transition (EMT) and melanoma progression is unclear. In this study, Affymetrix microarray analysis was performed to determine differentially expressed genes following doxycyclin induced shRNA-mediated knockdown of PLK1 in human melanoma cells that showed significant modulations in EMT and metastasis related genes.
Project description:Polo-like kinase 1 (PLK1), a serine/threonine kinase, is overexpressed in melanoma and its expression has been associated with poor disease prognosis. PLK1 has been shown to interact with NUMB, a NOTCH antagonist. However, the exact role of PLK1, NUMB, and NOTCH signaling in epithelial-mesenchymal transition (EMT) in melanoma progression is unclear. In this study, Affymetrix microarray analysis was performed to determine differentially expressed genes following shRNA-mediated knockdown of PLK1 in human melanoma cells that showed significant modulations in EMT and metastasis-related genes. Using multiple PLK1-modulated melanoma cell lines, we found that PLK1 is involved in the regulation of cell migration, invasion, and EMT via its kinase activity and NOTCH activation. In vitro kinase assay and mass spectrometry analysis demonstrated a previously unknown PLK1 phosphorylation site (Ser413) on NUMB. Overexpression of non-phosphorylatable (S413A) and phosphomimetic (S413D) mutants of NUMB in melanoma cells implicated the involvement of NUMB-S413 phosphorylation in cell migration and invasion, which was independent of NOTCH activation. To determine the clinical relevance of these findings, immunohistochemistry was performed using melanoma tissue microarray, which indicated a strong positive correlation between PLK1 and N-cadherin, a protein required for successful EMT. These findings were supported by TCGA analysis, where expression of high PLK1 with low NUMB or high NOTCH or N-cadherin showed a significant decrease in survival of melanoma patients. Overall, these results suggest a potential role of PLK1 in EMT, migration, and invasion of melanoma cells. Our findings support the therapeutic targeting of PLK1, NUMB, and NOTCH for melanoma management.
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:Cellular plasticity confers cancer cells the ability to adapt to micro-environmental changes, a fundamental requirement for tumour progression and metastasis. The epithelial to mesenchymal transition (EMT) is a transcriptional programme associated with increased cell motility and stemness. Beside EMT, the mesenchymal to amoeboid transition (MAT) has been described during tumour progression but, to date, little is known about its transcriptional control and involvement in stemness. The aim of this study is to investigate (i) the transcriptional profile associated with the MAT programme and (ii) to study whether MAT acquisition in melanoma cancer cells correlate with clonogenic potential to promote tumor growth. Our results demonstrate that MAT programme in melanoma is characterised by increased stemness and clonogenic features of cancer cells, thus sustaining tumour progression. Furthermore, these data suggest that stemness is not an exclusive feature of cells undergoing EMT, but more generally is associated with an increase in cellular plasticity of cancer cells. Hs294T in the presence of Ilomastat, Hs294T treated with the Rho activator Calpeptin and EphA2-overexpressing Hs294Tcells were obtained. Duplicate sample from 2 independent experiments were hybridized onto Human AffymetrixHuGene St 1.0 GeneChip array (Affymetrix).
Project description:Epithelial-mesenchymal transition (EMT) is a highly conserved morphogenic process defined by the loss of epithelial characteristics and the acquisition of a mesenchymal phenotype. EMT is associated with increased aggressiveness, invasiveness, and metastatic potential in carcinoma cells. To assess the contribution of extracellular vesicles following EMT, we conducted a proteomic analysis of shed microvesicles released from Madin-Darby canine kidney (MDCK) cells, and MDCK cells transformed with oncogenic H-Ras (21D1 cells).
Project description:PLK1 inhibitors are emerging anti-cancer agents being tested in monotherapy and combination therapies for various cancers. Although PLK1 inhibition in experimental models shows potent antitumor effects, translation to the clinic has been hampered by low antitumor activity and tumor relapse. Here, we report the identification of mitochondrial protein signatures that determine sensitivity to approaches targeting PLK1 in human melanoma cell lines. In response to PLK1 inhibition or gene silencing, resistant cells adopt a pro-inflammatory and dedifferentiated phenotype, while sensitive cells engage apoptosis. Mitochondrial DNA depletion and silencing of the ABCD1 transporter sensitize cells to PLK1 inhibition and attenuate the associated pro-inflammatory response. We also found that non-selective inhibitors of the p90 ribosomal S6 kinase (RSK) exert their anti-proliferative and pro-inflammatory effects via PLK1 inhibition. This work reveals overlooked impacts of PLK1 on phenotype switching and suggests that mitochondrial precision medicine can help improve response to targeted therapies.