The kinase PLK1 promotes the development of <i>Kras</i>/<i>Tp53</i>-mutant lung adenocarcinoma through transcriptional activation of the receptor RET

Characteristics of folic acid metabolism-related genes unveil prognosis and treatment strategy in lung adenocarcinoma

BACKGROUND

Lung adenocarcinoma (LUAD) is the most common subtype of lung cancer. Folic acid metabolism-related genes (FAMGs) have received increased attention because of their distinct role in DNA synthesis and repair. Nevertheless, the function of FAMGs in LUAD remains ambiguous.

METHODS

LUAD transcriptome data from GEO and TCGA were analyzed. Patients were classified into two clusters based on gene expression levels, revealing distinct overall survival (OS) outcomes. Common differentially expressed genes (DEGs) were identified between LUAD and normal tissues, as well as between the two clusters. A prognostic risk model was established using Cox regression analysis to predict outcomes of LUAD patients and was validated with Kaplan-Meier and ROC curve analysis. Clinical correlations and enrichment analyses were carried out to explore the functions of DEGs and their associations with clinical characteristics of LUAD patients. The tumor microenvironment and drug sensitivity were evaluated between two risk subgroups. Moreover, expression levels of prognostic genes were validated across datasets using the Wilcoxon-test.

RESULTS

The study identified seventy-seven common DEGs and nine prognostic genes (ANLN, PLK1, DLGAP5, PRC1, CYP4B1, MKI67, KIF23, BIRC5, TK1). The risk model could effectively predict the prognosis of LUAD patients. Clinical correlation analysis revealed that age, pathologic-T, pathologic-N, and tumor stage were significantly correlated with the risk score. Enrichment analysis showed that DEGs between the two risk subgroups were predominantly enriched in cell cycle and cellular senescence pathways. Differences in immune cell infiltration and immunotherapy markers were markedly noted between the two risk subgroups. Drug sensitivity analysis disclosed significantly diverse responses to sixty-eight drugs between the two risk subgroups. Consistent expression tendencies of prognostic genes were observed across datasets.

CONCLUSION

The prognostic model based on FAMGs demonstrates considerable potential for guiding diagnosis and clinical management of LUAD patients.

Identification of targetable vulnerabilities of PLK1-overexpressing cancers by synthetic dosage lethality

Chromosomal instability (CIN) drives tumor heterogeneity, complicating cancer therapy. Although Polo-like kinase 1 (PLK1) overexpression induces CIN, direct inhibition of PLK1 has shown limited clinical benefits. We therefore performed a genome-wide synthetic dosage lethality (SDL) screen to identify effective alternative targets and validated over 100 candidates using in vivo and in vitro secondary CRISPR screens. We employed direct-capture Perturb-seq to assess the transcriptional consequences and viability of each SDL perturbation at a single-cell resolution. This revealed IGF2BP2 as a critical genetic dependency that, when targeted, downregulated PLK1 and significantly restricted tumor growth. Mechanistic analyses showed that IGF2BP2 loss disrupted cellular energy metabolism and mitochondrial ATP production by downregulating PLK1 levels as well as genes associated with oxidative phosphorylation. Consistent with this, pharmacological inhibition of IGF2BP2 severely impacts the viability of PLK1-overexpressing cancer cells addicted to higher metabolic rates. Our work offers a novel therapeutic strategy against PLK1-driven heterogeneous malignancies.

Targeting PLK1-CBX8-GPX4 axis overcomes BRAF/EGFR inhibitor resistance in BRAFV600E colorectal cancer via ferroptosis

Metastatic BRAFV600E colorectal cancer (CRC) confers poor prognosis and represents a therapeutic bottleneck. To identify resistance mechanisms of the mitogen-activated protein kinase (MAPK) pathway in BRAFV600E CRC, we perform genome-wide CRISPR-Cas9 screening and discover that targeting glutathione peroxidase 4 (GPX4) overcomes resistance to BRAF inhibitor (BRAFi) combined with or without epidermal growth factor receptor inhibitor (EGFRi) in BRAFV600E CRC. Specifically, BRAFi ± EGFRi upregulates GPX4 expression, which antagonizes therapy-induced ferroptosis. Moreover, polo-like kinase 1 (PLK1) substrate activation promotes PLK1 translocation to the nucleus, activating chromobox protein homolog 8 (CBX8) phosphorylation at Ser265 to drives GPX4 expression. Targeting PLK1 enhances BRAFi ± EGFRi inhibition and triggers ferroptosis in vitro, vivo, organoid, and patient-derived xenograft model. Collectively, we demonstrate a PLK1-CBX8-GPX4 signaling axis that relays the ferroptosis mechanism of therapeutic resistance and propose a clinically actionable strategy to overcome BRAFi ± EGFRi resistance in BRAFV600E CRC.

Multi-omics insights into the roles of CCNB1, PLK1, and HPSE in breast cancer progression: implications for prognosis and immunotherapy

BACKGROUND

This study examines the roles of Cyclin B1 (CCNB1), Polo-Like Kinase 1 (PLK1), and Heparanase (HPSE) in breast cancer progression using a multi-omics approach. These genes are known for their involvement in various cancer-related processes, but their precise contributions to breast cancer remain unclear.

METHODS

We employed an integrative analysis combining transcriptomics, proteomics, DNA methylation profiling, immune infiltration analysis, and single-cell RNA sequencing to investigate the expression patterns, regulatory mechanisms, and functional impacts of CCNB1, PLK1, and HPSE in breast cancer. Functional assays using si-RNA knockdown of CCNB1 and PLK1 were performed to assess their roles in cell proliferation.

RESULTS

CCNB1, PLK1, and HPSE are upregulated in breast tumors at the mRNA and protein levels. CCNB1 and PLK1 promote tumor growth and metastasis, while HPSE is linked to immune pathways. DNA methylation in BRCA correlates with prognosis, with PLK1 alterations protective for recurrence-free survival. High expression of these genes worsens prognosis, with CCNB1 as a risk factor for overall survival. Immune infiltration analysis associates these genes with tumor-infiltrating immune cells, highlighting HPSE's immunotherapeutic potential. Single-cell RNA sequencing confirms CCNB1 and PLK1 drive malignant proliferation and an immunosuppressive environment. Functional assays demonstrated that silencing CCNB1 and PLK1 significantly reduced breast cancer cell proliferation, indicating regulatory interactions among PLK1, CCNB1, and MKI67.

CONCLUSIONS

This study provides evidence that CCNB1, PLK1, and HPSE are key players in breast cancer progression and potential biomarkers for prognosis. Furthermore, their roles in immune regulation suggest they could be promising targets for immunotherapy.

NF-κB-mediated EAAT3 upregulation in antioxidant defense and ferroptosis sensitivity in lung cancer

Cellular glutathione (GSH) in lung cancer cells represents the most abundant antioxidant. GSH production is regulated not only by upregulated cystine/glutamate exchanger (xCT) but also by the involvement of glutamate transporters, specifically excitatory amino acid transporter 3 (EAAT3). Our prior research established that the uptake of glutamate via EAAT3 plays a pivotal role in driving cystine uptake through xCT, contributing to GSH biosynthesis during lung tumorigenesis. Nevertheless, the underlying mechanism governing the upregulation of EAAT3 remains enigmatic. In this study, we conducted a comprehensive reanalysis of publicly available data and employed the Gprc5a-/-/SR-IκB mouse model alongside in vitro cell experiments to elucidate the correlations between NF-κB and EAAT3 in lung cancer. We observed that EAAT3 knockdown, similar to NF-κB inhibition, led to the accumulation of reactive oxygen species (ROS) and increased sensitivity to ferroptosis induction by RAS-selective lethal 3 (RSL3). Mechanistic insights were obtained through chromatin immunoprecipitation and luciferase reporter assays, revealing that NF-κB induces EAAT3 expression via two putative cis-elements within its promoter. Furthermore, our investigation unveiled the upregulation of EAAT3 in a subset of clinical non-small cell lung cancer (NSCLC) tissues, exhibiting a positive correlation with the P65 protein. In addition, the inflammatory factor of smoking was found to augment EAAT3 expression in both human and murine experimental models. These findings collectively emphasize the pivotal role of the NF-κB/EAAT3 axis in managing antioxidant stress and influencing lung cancer development. Moreover, this research offers insights into the potential for a combined ferroptosis therapy strategy in lung cancer treatment.

Exploration of telomere-related biomarkers for lung adenocarcinoma and targeted drug prediction

AIM

Bioinformatics analyses were performed to identify telomere biomarkers to develop a diagnostic model for lung adenocarcinoma (LUAD) and to predict potential target drugs for patients with LUAD.

BACKGROUND

Telomeres function crucially in maintaining genome stability and chromosome integrity, and telomere-related genes (TRGs) serve as potential prognostic markers in a variety of cancers. However, studies focusing on TRGs in LUAD are limited.

OBJECTIVE

To screen key telomere-related markers for LUAD and to evaluate their potential impact on the occurrence and development of LUAD.

METHODS

LUAD samples were collected from University of California Santa Cruz (UCSC) Xena and 2093 telomere-related genes (TRGs) were obtained from TelNet database. Hub genes were screened using "WGCNA" package. Differentially expressed genes (DEGs) between tumor and control samples were filtered using "DESeq" package. Protein-protein interaction (PPI) network analysis was performed to select candidate genes, from which telomere-related biomarkers were identified by machine learning and used to develop a nomogram. Functional enrichment pathways of the biomarkers were analyzed using "clusterProfiler" package. Correlation between immune cell infiltration and the biomarkers was examined by Spearman method. Targeted drugs were predicted and molecular docking models were developed using AutoDockTools. Finally, the screened biomarkers were validated by performing in vitro cellular assays.

RESULTS

A total of 259 hub genes, 2848 DEGs, and 48 differentially expressed TRGs in LUAD were screened. Subsequently, 13 candidate genes were obtained by PPI network analysis. LASSO and support vector machine-recursive feature elimination (SVM-RFE) algorithms further reduced the number of telomere-related biomarkers to four (CCNB1, CDC20, PLK1, and TOP2A). A nomogram with a strong predictive performance was created. These four biomarkers were mainly enriched in the mitogenic pathways and exhibited a strong correlation with immune cell infiltration. Three drugs (Lucanthone, Fulvestrant, and Myricetin) targeting the four biomarkers were predicted to be able to treat LUAD. Finally, in vitro cellular experiments demonstrated that CCNB1 and PLK1 have potential effects on proliferation, migration, invasion and AKT/mTOR signaling pathway in LUAD cells.

CONCLUSION

This study provided novel diagnostic biomarkers, therapeutic targets, and potential drugs for LUAD.

Comprehensive analysis identifies YKT6 as a potential prognostic and diagnostic biomarker in lung adenocarcinoma

BACKGROUND

Lung cancer is the most common cause of cancer-related death worldwide. The most prevalent histological subtype of lung cancer is lung adenocarcinoma (LUAD), with incidence rising each year. Treating LUAD remains a significant issue due to a lack of early diagnosis and poor therapy outcomes. YKT6 is a member of the SNARE protein family, whose clinical value and biological function in LUAD has yet to be established.

METHODS

TCGA, HPA and UALCAN were used to analyze YKT6 mRNA and protein levels, the correlation between YKT6 expression and clinicopathological features and prognosis. YKT6 mRNA and protein expression were verified by qRT-PCR, immunohistochemistry (IHC) and tissue microarrays (TMA). Additionally, lung cancer cell lines were chosen for YKT6 silencing to explore the effects on cell proliferation and migration. The cBioPortal was used to select YKT6-related genes. Protein-protein interaction (PPI) network was created based on STRING database and hub genes were screened, with their expression levels and prognosis values in LUAD analyzed accordingly. YKT6-related genes were enriched by gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) analyses.

RESULTS

In LUAD, YKT6 was distinctly highly expressed with relation to clinical features of staging, smoking, lymph node metastasis, and TP53 mutation. Elevated YKT6 expression was linked to adverse prognosis, serving as an independent unfavorable prognostic factor. Moreover, YKT6 presented high diagnostic value in LUAD patients (AUC = 0.856). Experimental validation indicated that freshly collected LUAD tissues showed significantly high mRNA expression of YKT6. IHC and TMA verified increased YKT6 protein level in LUAD. Knockdown of YKT6 inhibited cell proliferation and promoted apoptosis, with mitigated capability of migration and invasion. The top ten hub genes screened by PPI network were highly expressed in LUAD, and significantly associated with poor prognosis. GO and KEGG analyses showed that YKT6-related genes were mainly involved in cell cycle.

CONCLUSION

Elevated YKT6 expression is related to poor prognosis of LUAD patients. YKT6 can serve as a novel biomarker for LUAD diagnosis and prognosis. Cell proliferation, migration and invasion was impaired with increased apoptosis upon YKT6 silencing in lung cancer cells. In summary, this study comprehensively uncovered that YKT6 could be identified as a potential prognostic and diagnostic biomarker in LUAD.

UBASH3B-mediated MRPL12 Y60 dephosphorylation inhibits LUAD development by driving mitochondrial metabolism reprogramming

BACKGROUND

Metabolic reprogramming plays a pivotal role in tumorigenesis and development of lung adenocarcinoma (LUAD). However, the precise mechanisms and potential targets for metabolic reprogramming in LUAD remain elusive. Our prior investigations revealed that the mitochondrial ribosomal protein MRPL12, identified as a novel mitochondrial transcriptional regulatory gene, exerts a critical influence on mitochondrial metabolism. Despite this, the role and regulatory mechanisms underlying MRPL12's transcriptional activity in cancers remain unexplored.

METHODS

Human LUAD tissues, Tp53fl/fl;KrasG12D-driven LUAD mouse models, LUAD patient-derived organoids (PDO), and LUAD cell lines were used to explored the expression and function of MRPL12. The posttranslational modification of MRPL12 was analyzed by mass spectrometry, and the oncogenic role of key phosphorylation sites of MRPL12 in LUAD development was verified in vivo and in vitro.

RESULTS

MRPL12 was upregulated in human LUAD tissues, Tp53fl/fl;KrasG12D-driven LUAD tissues in mice, LUAD PDO, and LUAD cell lines, correlating with poor patient survival. Overexpression of MRPL12 significantly promoted LUAD tumorigenesis, metastasis, and PDO formation, while MRPL12 knockdown elicited the opposite phenotype. Additionally, MRPL12 deletion in a Tp53fl/fl;KrasG12D-driven mouse LUAD model conferred a notable survival advantage, delaying tumor onset and reducing malignant progression. Mechanistically, we discovered that MRPL12 promotes tumor progression by upregulating mitochondrial oxidative phosphorylation. Furthermore, we identified UBASH3B as a specific binder of MRPL12, dephosphorylating tyrosine 60 in MRPL12 (MRPL12 Y60) and inhibiting its oncogenic functions. The decrease in MRPL12 Y60 phosphorylation impeded the binding of MRPL12 to POLRMT, downregulating mitochondrial metabolism in LUAD cells. In-depth in vivo, in vitro, and organoid models validated the inhibitory effect of MRPL12 Y60 mutation on LUAD.

CONCLUSION

This study establishes MRPL12 as a novel oncogene in LUAD, contributing to LUAD pathogenesis by orchestrating mitochondrial metabolism reprogramming towards oxidative phosphorylation (OXPHOS). Furthermore, it confirms Y60 as a specific phosphorylation modification site regulating MRPL12's oncogenic functions, offering insights for the development of LUAD-specific targeted drugs and clinical interventions.

Metformin synergizes with gilteritinib in treating FLT3-mutated leukemia via targeting PLK1 signaling

Fms-like tyrosine kinase 3 (FLT3) mutations, present in over 30% of acute myeloid leukemia (AML) cases and dominated by FLT3-internal tandem duplication (FLT3-ITD), are associated with poor outcomes in patients with AML. While tyrosine kinase inhibitors (TKIs; e.g., gilteritinib) are effective, they face challenges such as drug resistance, relapse, and high costs. Here, we report that metformin, a cheap, safe, and widely used anti-diabetic agent, exhibits a striking synergistic effect with gilteritinib in treating FLT3-ITD AML. Metformin significantly sensitizes FLT3-ITD AML cells (including TKI-resistant ones) to gilteritinib. Metformin plus gilteritinib (low dose) dramatically suppresses leukemia progression and prolongs survival in FLT3-ITD AML mouse models. Mechanistically, the combinational treatment cooperatively suppresses polo-like kinase 1 (PLK1) expression and phosphorylation of FLT3/STAT5/ERK/mTOR. Clinical analysis also shows improved survival rates in patients with FLT3-ITD AML taking metformin. Thus, the metformin/gilteritinib combination represents a promising and cost-effective treatment for patients with FLT3-mutated AML, particularly for those with low income/affordability.

Gene Regulatory Programs that Specify Age-Related Differences during Thymocyte Development

T cell development is fundamental to immune system establishment, yet how this development changes with age remains poorly understood. Here, we construct a transcriptional and epigenetic atlas of T cell developmental programs in neonatal and adult mice, revealing the ontogeny of divergent gene regulatory programs and their link to age-related differences in phenotype and function. Specifically, we identify a gene module that diverges with age from the earliest stages of genesis and includes programs that govern effector response and cell cycle regulation. Moreover, we reveal that neonates possess more accessible chromatin during early thymocyte development, likely establishing poised gene expression programs that manifest later in thymocyte development. Finally, we leverage this atlas, employing a CRISPR-based perturbation approach coupled with single-cell RNA sequencing as a readout to uncover a conserved transcriptional regulator, Zbtb20, that contributes to age-dependent differences in T cell development. Altogether, our study defines transcriptional and epigenetic programs that regulate age-specific differences in T cell development.

Single-cell analysis identifies PLK1 as a driver of immunosuppressive tumor microenvironment in LUAD

PLK1 (Polo-like kinase 1) plays a critical role in the progression of lung adenocarcinoma (LUAD). Recent studies have unveiled that targeting PLK1 improves the efficacy of immunotherapy, highlighting its important role in the regulation of tumor immunity. Nevertheless, our understanding of the intricate interplay between PLK1 and the tumor microenvironment (TME) remains incomplete. Here, using genetically engineered mouse model and single-cell RNA-seq analysis, we report that PLK1 promotes an immunosuppressive TME in LUAD, characterized with enhanced M2 polarization of tumor associated macrophages (TAM) and dampened antigen presentation process. Mechanistically, elevated PLK1 coincides with increased secretion of CXCL2 cytokine, which promotes M2 polarization of TAM and diminishes expression of class II major histocompatibility complex (MHC-II) in professional antigen-presenting cells. Furthermore, PLK1 negatively regulates MHC-II expression in cancer cells, which has been shown to be associated with compromised tumor immunity and unfavorable patient outcomes. Taken together, our results reveal PLK1 as a novel modulator of TME in LUAD and provide possible therapeutic interventions.

Exploring the mechanism of 6-Methoxydihydrosanguinarine in the treatment of lung adenocarcinoma based on network pharmacology, molecular docking and experimental investigation

BACKGROUND

6-Methoxydihydrosanguinarine (6-MDS) has shown promising potential in fighting against a variety of malignancies. Yet, its anti‑lung adenocarcinoma (LUAD) effect and the underlying mechanism remain largely unexplored. This study sought to explore the targets and the probable mechanism of 6-MDS in LUAD through network pharmacology and experimental validation.

METHODS

The proliferative activity of human LUAD cell line A549 was evaluated by Cell Counting Kit-8 (CCK8) assay. LUAD related targets, potential targets of 6-MDS were obtained from databases. Venn plot analysis were performed on 6-MDS target genes and LUAD related genes to obtain potential target genes for 6-MDS treatment of LUAD. The Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) database was utilized to perform a protein-protein interaction (PPI) analysis, which was then visualized by Cytoscape. The hub genes in the network were singled out by CytoHubba. Metascape was employed for GO and KEGG enrichment analyses. molecular docking was carried out using AutoDock Vina 4.2 software. Gene expression levels, overall survival of hub genes were validated by the GEPIA database. Protein expression levels, promotor methylation levels of hub genes were confirmed by the UALCAN database. Timer database was used for evaluating the association between the expression of hub genes and the abundance of infiltrating immune cells. Furthermore, correlation analysis of hub genes expression with immune subtypes of LUAD were performed by using the TISIDB database. Finally, the results of network pharmacology analysis were validated by qPCR.

RESULTS

Experiments in vitro revealed that 6-MDS significantly reduced tumor growth. A total of 33 potential targets of 6-MDS in LUAD were obtained by crossing the LUAD related targets with 6-MDS targets. Utilizing CytoHubba, a network analysis tool, the top 10 genes with the highest centrality measures were pinpointed, including MMP9, CDK1, TYMS, CCNA2, ERBB2, CHEK1, KIF11, AURKB, PLK1 and TTK. Analysis of KEGG enrichment hinted that these 10 hub genes were located in the cell cycle signaling pathway, suggesting that 6-MDS may mainly inhibit the occurrence of LUAD by affecting the cell cycle. Molecular docking analysis revealed that the binding energies between 6-MDS and the hub proteins were all higher than - 6 kcal/Mol with the exception of AURKB, indicating that the 9 targets had strong binding ability with 6-MDS.These results were corroborated through assessments of mRNA expression levels, protein expression levels, overall survival analysis, promotor methylation level, immune subtypes andimmune infiltration. Furthermore, qPCR results indicated that 6-MDS can significantly decreased the mRNA levels of CDK1, CHEK1, KIF11, PLK1 and TTK.

CONCLUSIONS

According to our findings, it appears that 6-MDS could possibly serve as a promising option for the treatment of LUAD. Further investigations in live animal models are necessary to confirm its potential in fighting cancer and to delve into the mechanisms at play.

Eph signal inhibition potentiates the growth-inhibitory effects of PLK1 inhibition toward cancer cells

Anti-mitotic drugs are clinically used as anti-cancer treatments. Polo-like kinase 1 (PLK1) is a promising target against cancer cell division due to its importance in the whole process of mitosis, and thus PLK1-targeting agents have been developed in the last few decades. Clinical trial studies show that several PLK1 inhibitors are generally well-tolerated. However, the response rates are limited; therefore, it is needed to improve the efficacy of those drugs. Here, we show that NVP-BHG712, an erythropoietin-producing human hepatocellular (Eph) signaling inhibitor, potentiates the growth-inhibitory effects of the PLK1 inhibitors BI2536 and BI6727 in cancer cells. This combination treatment strongly suppresses cancer spheroid formation. Moreover, the combination drastically arrests cells at mitosis by continuous activation of the spindle assembly checkpoint (SAC), thereby inducing apoptosis. SAC activation caused by the combination of NVP-BHG712 and BI2536 is due to the inhibition of centrosome maturation and separation. Although the inactivation level of the PLK1 kinase is comparable between BI2536 treatment alone and combination treatment, the combination treatment strongly inactivates MAPK signaling in mitosis. Since inhibition of MAPK signaling potentiates the efficacy of BI2536 treatment, inactivation of PLK1 kinase and MAPK signaling contributes to the strong inhibition of centrosome separation. These results suggest that Eph signal inhibition potentiates the effect of PLK1 inhibition, leading to strong mitotic arrest via SAC activation and the subsequent reduction of cancer cell survival. The combination of PLK1 inhibition and Eph signal inhibition will provide a new effective strategy for targeting cancer cell division.

Loss of ATOH1 in Pit Cell Drives Stemness and Progression of Gastric Adenocarcinoma by Activating AKT/mTOR Signaling through GAS1

Gastric cancer stem cells (GCSCs) are self-renewing tumor cells that govern chemoresistance in gastric adenocarcinoma (GAC), whereas their regulatory mechanisms remain elusive. Here, the study aims to elucidate the role of ATOH1 in the maintenance of GCSCs. The preclinical model and GAC sample analysis indicate that ATOH1 deficiency is correlated with poor GAC prognosis and chemoresistance. ScRNA-seq reveals that ATOH1 is downregulated in the pit cells of GAC compared with those in paracarcinoma samples. Lineage tracing reveals that Atoh1 deletion strongly confers pit cell stemness. ATOH1 depletion significantly accelerates cancer stemness and chemoresistance in Tff1-CreERT2; Rosa26Tdtomato and Tff1-CreERT2; Apcfl/fl ; p53fl/fl (TcPP) mouse models and organoids. ATOH1 deficiency downregulates growth arrest-specific protein 1 (GAS1) by suppressing GAS1 promoter transcription. GAS1 forms a complex with RET, which inhibits Tyr1062 phosphorylation, and consequently activates the RET/AKT/mTOR signaling pathway by ATOH1 deficiency. Combining chemotherapy with drugs targeting AKT/mTOR signaling can overcome ATOH1 deficiency-induced chemoresistance. Moreover, it is confirmed that abnormal DNA hypermethylation induces ATOH1 deficiency. Taken together, the results demonstrate that ATOH1 loss promotes cancer stemness through the ATOH1/GAS1/RET/AKT/mTOR signaling pathway in GAC, thus providing a potential therapeutic strategy for AKT/mTOR inhibitors in GAC patients with ATOH1 deficiency.

Phosphorylation of AHR by PLK1 promotes metastasis of LUAD via DIO2-TH signaling

Metastasis of lung adenocarcinoma (LUAD) is a major cause of death in patients. Aryl hydrocarbon receptor (AHR), an important transcription factor, is involved in the initiation and progression of lung cancer. Polo-like kinase 1 (PLK1), a serine/threonine kinase, acts as an oncogene promoting the malignancy of multiple cancer types. However, the interaction between these two factors and their significance in lung cancer remain to be determined. In this study, we demonstrate that PLK1 phosphorylates AHR at S489 in LUAD, leading to epithelial-mesenchymal transition (EMT) and metastatic events. RNA-seq analyses reveal that type 2 deiodinase (DIO2) is responsible for EMT and enhanced metastatic potential. DIO2 converts tetraiodothyronine (T4) to triiodothyronine (T3), activating thyroid hormone (TH) signaling. In vitro and in vivo experiments demonstrate that treatment with T3 or T4 promotes the metastasis of LUAD, whereas depletion of DIO2 or a deiodinase inhibitor disrupts this property. Taking together, our results identify the AHR phosphorylation by PLK1 and subsequent activation of DIO2-TH signaling as mechanisms leading to LUAD metastasis. These findings can inform possible therapeutic interventions for this event.

Single-cell analysis characterizes PLK1 as a catalyst of an immunosuppressive tumor microenvironment in LUAD

PLK1 (Polo-like kinase 1) plays a critical role in the progression of lung adenocarcinoma (LUAD). Recent studies have unveiled that targeting PLK1 improves the efficacy of immunotherapy, highlighting its important role in the regulation of tumor immunity. Nevertheless, our understanding of the intricate interplay between PLK1 and the tumor microenvironment (TME) remains incomplete. Here, using genetically engineered mouse model and single-cell RNA-seq analysis, we report that PLK1 promotes an immunosuppressive TME in LUAD, characterized with enhanced M2 polarization of tumor associated macrophages (TAM) and dampened antigen presentation process. Mechanistically, elevated PLK1 coincides with increased secretion of CXCL2 cytokine, which promotes M2 polarization of TAM and diminishes expression of class II major histocompatibility complex (MHC-II) in professional antigen-presenting cells. Furthermore, PLK1 negatively regulates MHC-II expression in cancer cells, which has been shown to be associated with compromised tumor immunity and unfavorable patient outcomes. Taken together, our results reveal PLK1 as a novel modulator of TME in LUAD and provide possible therapeutic interventions.

Identification and validation of tumor microenvironment-related signature for predicting prognosis and immunotherapy response in patients with lung adenocarcinoma

Mounting evidence has found that tumor microenvironment (TME) plays an important role in the tumor progression of lung adenocarcinoma (LUAD). However, the roles of tumor microenvironment-related genes in immunotherapy and clinical outcomes remain unclear. In this study, 6 TME-related genes (PLK1, LDHA, FURIN, FSCN1, RAB27B, and MS4A1) were identified to construct the prognostic model. The established risk scores were able to predict outcomes at 1, 3, and 5 years with greater accuracy than previously known models. Moreover, the risk score was closely associated with immune cell infiltration and the immunoregulatory genes including T cell exhaustion markers. In conclusion, the TME risk score can function as an independent prognostic biomarker and a predictor for evaluating immunotherapy response in LUAD patients, which provides recommendations for improving patients' response to immunotherapy and promoting personalized tumor immunotherapy in the future.

Phosphorylation of AHR by PLK1 promotes metastasis of LUAD via DIO2-TH signaling

Metastasis of Lung adenocarcinoma (LUAD) is a major cause of death in patients. Aryl hydrocarbon receptor (AHR) is an important transcription factor involved in the initiation and progression of lung cancer. Polo-like kinase 1 (PLK1), a serine/threonine kinase, is an oncogene that promotes the malignancy of multiple cancer types. Nonetheless, the interaction between these two factors and significance in lung cancer remains to be determined. Here, we demonstrate that PLK1 phosphorylates AHR at S489 in LUAD, which leads to epithelial-mesenchymal transition (EMT) and metastatic events. RNA-seq analyses show that type 2 deiodinase (DIO2) is responsible for EMT and enhanced metastatic potential. DIO2 converts tetraiodothyronine (T4) to triiodothyronine (T3), which then activates thyroid hormone signaling. In vitro and in vivo experiments demonstrate that treatment with T3 or T4 promotes the metastasis of LUAD, whereas depletion of DIO2 or deiodinase inhibitor disrupts this property. Taken together, our results identify the phosphorylation of AHR by PLK1 as a mechanism leading to the progression of LUAD and provide possible therapeutic interventions for this event.

The Role of Polo-Like Kinase 1 in Regulating the Forkhead Box Family Transcription Factors

Polo-like kinase 1 (PLK1) is a serine/threonine kinase with more than 600 phosphorylation substrates through which it regulates many biological processes, including mitosis, apoptosis, metabolism, RNA processing, vesicle transport, and G₂ DNA-damage checkpoint recovery, among others. Among the many PLK1 targets are members of the FOX family of transcription factors (FOX TFs), including FOXM1, FOXO1, FOXO3, and FOXK1. FOXM1 and FOXK1 have critical oncogenic roles in cancer through their antagonism of apoptotic signals and their promotion of cell proliferation, metastasis, angiogenesis, and therapeutic resistance. In contrast, FOXO1 and FOXO3 have been identified to have broad functions in maintaining cellular homeostasis. In this review, we discuss PLK1-mediated regulation of FOX TFs, highlighting the effects of PLK1 on the activity and stability of these proteins. In addition, we review the prognostic and clinical significance of these proteins in human cancers and, more importantly, the different approaches that have been used to disrupt PLK1 and FOX TF-mediated signaling networks. Furthermore, we discuss the therapeutic potential of targeting PLK1-regulated FOX TFs in human cancers.