Chronic TGFβ stimulation promotes the metastatic potential of lung cancer cells by Snail protein stabilization through integrin β3-Akt-GSK3β signaling

Concurrent targeting of GSK3 and MEK as a therapeutic strategy to treat pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies worldwide. However, drug discovery for PDAC treatment has proven complicated, leading to stagnant therapeutic outcomes. Here, we identify Glycogen synthase kinase 3 (GSK3) as a therapeutic target through a whole-body genetic screening utilizing a '4-hit' Drosophila model mimicking the PDAC genotype. Reducing the gene dosage of GSK3 in a whole-body manner or knocking down GSK3 specifically in transformed cells suppressed 4-hit fly lethality, similar to Mitogen-activated protein kinase kinase (MEK), the therapeutic target in PDAC we have recently reported. Consistently, a combination of the GSK3 inhibitor CHIR99021 and the MEK inhibitor trametinib suppressed the phosphorylation of Polo-like kinase 1 (PLK1) as well as the growth of orthotopic human PDAC xenografts in mice. Additionally, reducing PLK1 genetically in 4-hit flies rescued their lethality. Our results reveal a therapeutic vulnerability in PDAC that offers a treatment opportunity for patients by inhibiting multiple targets.

Chronic Leptin Treatment Induces Epithelial-Mesenchymal Transition in MCF10A Mammary Epithelial Cells

Leptin is a cytokine-like hormone that functions as a link between obesity and breast cancer (BC). Leptin treatment induces Epithelial to Mesenchymal Transition (EMT) in BC cell lines. In non-tumoral breast epithelial MCF10A cells, acute leptin treatment induces partial EMT. However, the effect of chronic leptin treatment on EMT in non-tumorigenic breast cells has not been fully explored. This study aimed to evaluate the effect of chronic leptin treatment on the induction of EMT in MCF10A cells. We found that chronic leptin treatment induces a switch from an epithelial to a mesenchymal morphology, partial loss of E-cadherin and gain of vimentin expression. Immunolocalization experiments showed a partial loss of E-cadherin at cell junctions and increased cytoplasmic localization of vimentin in leptin-treated cells. Moreover, chronic leptin treatment increased collective cell migration and invasion. Furthermore, when cultured in non-adherent conditions leptin treated cells exhibited reduced cell aggregation, increased survival, and decreased apoptosis, which correlates with increased FAK and AKT phosphorylation. Finally, bioinformatic analysis in two publicly available RNAseq datasets from normal breast tissue shows that high levels of leptin mRNA correlate positively with the expression of mesenchymal markers, and negatively with epithelial markers. Thus, our results demonstrate that chronic leptin treatment induces EMT in non-tumorigenic MCF10A cells and suggest that high leptin expression in normal breast tissue may induce EMT and contribute to increased risk of breast cancer.

TGFβ promotes YAP-dependent AXL induction in mesenchymal-type lung cancer cells

The acquisition of chemoresistance remains a major cause of cancer mortality due to the limited accessibility of targeted or immune therapies. However, given that severe alterations of molecular features during epithelial-to-mesenchymal transition (EMT) lead to acquired chemoresistance, emerging studies have focused on identifying targetable drivers associated with acquired chemoresistance. Particularly, AXL, a key receptor tyrosine kinase that confers resistance against targets and chemotherapeutics, is highly expressed in mesenchymal cancer cells. However, the underlying mechanism of AXL induction in mesenchymal cancer cells is poorly understood. Our study revealed that the YAP signature, which was highly enriched in mesenchymal-type lung cancer, was closely correlated to AXL expression in 181 lung cancer cell lines. Moreover, using isogenic lung cancer cell pairs, we also found that doxorubicin treatment induced YAP nuclear translocation in mesenchymal-type lung cancer cells to induce AXL expression. Additionally, the concurrent activation of TGFβ signaling coordinated YAP-dependent AXL expression through SMAD4. These data suggest that crosstalk between YAP and the TGFβ/SMAD axis upon treatment with chemotherapeutics might be a promising target to improve chemosensitivity in mesenchymal-type lung cancer.

A prolonged exposure of human lung carcinoma epithelial cells to benzo[a]pyrene induces p21-dependent epithelial-to-mesenchymal transition (EMT)-like phenotype

Deciphering the role of the aryl hydrocarbon receptor (AhR) in lung cancer cells may help us to better understand the role of toxic AhR ligands in lung carcinogenesis, including cancer progression. We employed human lung carcinoma A549 cells to investigate their fate after continuous two-week exposure to model AhR agonists, genotoxic benzo[a]pyrene (BaP; 1 μM) and non-genotoxic 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD; 10 nM). While TCDD increased proliferative rate of A549 cells, exposure to BaP decreased cell proliferation and induced epithelial-to-mesenchymal transition (EMT)-like phenotype, which was associated with enhanced cell migration, invasion, and altered cell morphology. Although TCDD also suppressed expression of E-cadherin and activated some genes linked to EMT, it did not induce the EMT-like phenotype. The results of transcriptomic analysis, and the opposite effects of BaP and TCDD on cell proliferation, indicated that a delay in cell cycle progression, together with a slight increase of senescence (when coupled with AhR activation), favors the induction of EMT-like phenotype. The shift towards EMT-like phenotype observed after simultaneous treatment with TCDD and mitomycin C (an inhibitor of cell proliferation) confirmed the hypothesis. Since BaP decreased cell proliferative rate via induction of p21 expression, we generated the A549 cell model with reduced p21 expression and exposed it to BaP for two weeks. The p21 knockdown suppressed the BaP-mediated EMT-like phenotype in A549 cells, thus confirming that a delayed cell cycle progression, together with p21-dependent induction of senescence-related chemokine CCL2, may contribute to induction of EMT-like cell phenotype in lung cells exposed to genotoxic AhR ligands.

Systematic identification of a nuclear receptor-enriched predictive signature for erastin-induced ferroptosis

Erastin, a synthetic lethal compound against cancer expressing an oncogenic RAS, inhibits cystine/glutamate antiporters and causes ferroptosis. However, despite recent evidence for the mechanisms underlying ferroptosis, molecular biomarkers of erastin-dependent ferroptosis have not been identified. Here, we employed isogenic lung cancer cell models to show that a redox imbalance leads to glutathione depletion and ferroptosis. Subsequent transcriptome analysis of pan-cancer cell lines revealed that the activity of transcription factors, including NRF2 and AhR, serve as important markers of erastin resistance. Based on the integrated expression of genes in the nuclear receptor meta-pathway (NRM), we constructed an NRM model and validated its robustness using an independent pharmacogenomics dataset. The NRM model was further evaluated by sensitivity tests on nine cancer cell lines for which erastin sensitivities had not been determined. Our pharmacogenomics approach has the potential to pave the way for the efficient classification of patients for therapeutic intervention using erastin.

Stochastic and Heterogeneous Cancer Cell Migration: Experiment and Theory

Cell migration, an essential process for normal cell development and cancer metastasis, differs from a simple random walk: the mean-square displacement (〈(Δr)²(t)〉) of cells sometimes shows non-Fickian behavior, and the spatiotemporal correlation function (G(r, t)) of cells is often non-Gaussian. We find that this intriguing cell migration should be attributed to heterogeneity in a cell population, even one with a homogeneous genetic background. There are two limiting types of heterogeneity in a cell population: cellular heterogeneity and temporal heterogeneity. Cellular heterogeneity accounts for the cell-to-cell variation in migration capacity, while temporal heterogeneity arises from the temporal noise in the migration capacity of single cells. We illustrate that both cellular and temporal heterogeneity need to be taken into account simultaneously to elucidate cell migration. We investigate the two-dimensional migration of A549 lung cancer cells using time-lapse microscopy and find that the migration of A549 cells is Fickian but has a non-Gaussian spatiotemporal correlation. We find that when a theoretical model considers both cellular and temporal heterogeneity, the model reproduces all of the anomalous behaviors of cancer cell migration.

In silico drug repositioning: from large-scale transcriptome data to therapeutics

Drug repositioning is an attractive alternative to conventional drug development when new beneficial effects of old drugs are clinically validated because pharmacokinetic and safety profiles are generally already available. Since ~ 30% of drugs newly approved by the US food and drug administration (FDA) are developed through drug repositioning, identifying novel usage for existing drugs is an emerging strategy for developing disease treatments. With advances in next-generation sequencing technologies, available transcriptome data related to diseases have expanded rapidly. Harnessing these resources enables a better understanding of disease mechanisms and drug mode of action (MOA), and moves toward personalized pharmacotherapy. In this review, we briefly outline publicly available large-scale transcriptome databases and tools for drug repositioning. We also highlight recent approaches leading to the discovery of novel drug targets, drug response biomarkers, drug indications, and drug MOA.

Crosstalk between cancer and immune cells: Role of tumor-associated macrophages in the tumor microenvironment

Tumor microenvironment is a complex system that contains multiple cells and cytokines. Among the multiple immune cells, macrophage is particularly abundant and plays an important role throughout the tumor progression process, namely, tumor‐associated macrophage (TAM) in this special tumor microenvironment. Many kinds of cytokines from TAMs and other immune cells in tumor niche are involved in the linkage of inflammation, immunity and tumorigenesis. Inflammatory responses induced by TAMs are crucial to tumor development of different stages. This review highlights the critical role of TAMs in the linkage of inflammation, immunity, and cancer. It outlines the molecules of inflammatory cytokines, chemokines, and growth factors mainly from TAMs in tumor microenvironment and their functions in tumor development during the major issues of angiogenesis, chronic inflammation, and immune suppression. Additionally, the signaling pathways involved in tumor progression and the crosstalk between them are also summarized.

Simultaneous Detection of Autophagy and Epithelial to Mesenchymal Transition in the Non-small Cell Lung Cancer Cells

Autophagy is increasingly identified as a central player in many cellular activities from cell proliferation to cell division, migration, and differentiation. However, it is also considered as a double-edged sword in cancer biology which either promotes oncogenesis/invasion or sensitizes the tumor cells to chemotherapy induced apoptosis. Recent investigations have provided direct evidence for regulation of cellular phenotype via autophagy pathway. One of the most important types of phenotype conversion is Epithelial-Mesenchymal-Transition (EMT), resulting in alteration of epithelial cell properties to a more mesenchymal form. In the current chapter, we provide a method which is established and being used in our laboratory for detection of autophagy and EMT in lung epithelial cells and show the involvement of autophagy in modulation of cellular phenotype.

TGF-β signaling in cancer

Signals from the transforming growth factor-β (TGF-β) superfamily mediate a broad spectrum of cellular processes and are deregulated in many diseases, including cancer. TGF-β signaling has dual roles in tumorigenesis. In the early phase of tumorigenesis, TGF-β has tumor suppressive functions, primarily through cell cycle arrest and apoptosis. However, in the late stage of cancer, TGF-β acts as a driver of tumor progression and metastasis by increasing tumor cell invasiveness and migration and promoting chemo-resistance. Here, we briefly review the mechanisms and functions of TGF-β signaling during tumor progression and discuss the therapeutic potentials of targeting the TGF-β pathway in cancer.

Autophagy modulates transforming growth factor beta 1 induced epithelial to mesenchymal transition in non-small cell lung cancer cells

Lung cancer is considered one of the most frequent causes of cancer-related death worldwide and Non-Small Cell Lung Cancer (NSCLC) accounts for 80% of all lung cancer cases. Autophagy is a cellular process responsible for the recycling of damaged organelles and protein aggregates. Transforming growth factor beta-1 (TGFβ₁) is involved in Epithelial to Mesenchymal Transition (EMT) and autophagy induction in different cancer models and plays an important role in the pathogenesis of NSCLC. It is not clear how autophagy can regulate EMT in NSCLC cells. In the present study, we have investigated the regulatory role of autophagy in EMT induction in NSCLC and show that TGFβ₁ can simultaneously induce both autophagy and EMT in the NSCL lines A549 and H1975. Upon chemical inhibition of autophagy using Bafilomycin-A1, the expression of the mesenchymal marker vimentin and N-cadherin was reduced. Immunoblotting and immunocytochemistry (ICC) showed that the mesenchymal marker vimentin was significantly downregulated upon TGFβ₁ treatment in ATG7 knockdown cells when compared to corresponding cells treated with scramble shRNA (negative control), while E-cadherin was unchanged. Furthermore, autophagy inhibition (Bafilomycin A1 and ATG7 knockdown) decreased two important mesenchymal functions, migration and contraction, of NSCLC cells upon TGFβ₁ treatment. This study identified a crucial role of autophagy as a potential positive regulator of TGFβ₁-induced EMT in NSCLC cells and identifies inhibitors of autophagy as promising new drugs in antagonizing the role of EMT inducers, like TGFβ₁, in the clinical progression of NSCLC.

Cytosolic THUMPD1 promotes breast cancer cells invasion and metastasis via the AKT-GSK3-Snail pathway

Human THUMP domain-containing protein 1 (THUMPD1) is a specific adaptor protein that modulates tRNA acetylation through interaction with NAT10. Immunohistochemical analysis of 146 breast cancer specimens (82 triple-negative and 64 non-triple-negative cases) indicated THUMPD1 expression is higher in breast cancer tissues (60.9%, 89/146) than normal breast tissues (28.3%, 15/53; p < 0.001). Overall and cytosolic, but not nuclear, THUMPD1 expression in breast cancer correlated with advanced TNM stage (p = 0.003 and p < 0.001, respectively), lymph node metastasis (p = 0.001 and p < 0.001, respectively), and poor patient prognosis (p = 0.001 and p < 0.001, respectively). THUMPD1 interacted and co-localized with YAP, but did not affect Hippo pathway activity. THUMPD1 overexpression enhanced breast cancer cells invasion and migration in vivo and in vitro, possibly through activation of AKT, GSK3β and Snail, and inhibition of E-cadherin. Treatment with the AKT inhibitor, LY294002, reduced the effects of THUMPD1 overexpression in breast cancer cells. These results indicate that THUMPD1 promotes breast cancer cells invasion and migration via the AKT-GSK3β-Snail pathway.

Prognostic value of high-expression of miR-17-92 cluster in various tumors: evidence from a meta-analysis

The prognostic value of miR-17-92 cluster high-expression in various tumors remains controversial. Therefore, we conducted this meta-analysis by searching literatures in PubMed, Embase, Cochrane Library, China Biology Medicine disc, China National Knowledge Infrastructure to identify eligible studies. Eventually, we analyzed 36 articles that examined 17 tumor types from 4965 patients. Consequently, high-expression of miR-17-92 cluster in various tumors was associated with unfavorable overall survival in both univariate (HR = 2.05, 95%CI: 1.58-2.65, P<0.001) and multivariate (HR = 2.14, 95%CI: 1.75-2.61, P<0.001) analyses. Likewise, similar results were found in different subgroups of country, test method, miR-17-92 cluster component, sample source and size. Additionally, high-expression of miR-17-92 cluster was linked with poor disease-free survival (Univariate: HR = 1.96, 95%CI: 1.55-2.48, P<0.001; Multivariate: HR = 2.18, 95%CI: 1.63-2.91, P<0.001), favorable progression-free survival (Univariate: HR = 0.36, 95%CI: 0.16-0.80, P = 0.012; Multivariate: HR = 1.55, 95%CI: 0.79-3.05, P = 0.201) and poor cancer specific survival in univariate rather than multivariate analyses (Univariate: HR = 1.77, 95%CI: 1.21-2.60, P = 0.004; Multivariate: HR = 1.77, 95%CI: 0.80-3.92, P = 0.160). However, no association of miR-17-92 cluster high-expression was detected with recurrence or relapse-free survival. In summary, this meta-analysis towards high-expression of miR-17-92 cluster has indicated poor prognosis of various cancers. Notably, future studies comprising large cohort size from multicenter are required to confirm our conclusions.

TRIM22 confers poor prognosis and promotes epithelial-mesenchymal transition through regulation of AKT/GSK3β/β-catenin signaling in non-small cell lung cancer

Expression pattern and biological roles of TRIM22 remains unknown in most human cancers. The present study aims to discover its clinical significance and function in human non-small cell lung cancer (NSCLC). Immunohistochemistry was used to examine TRIM22 expression in 126 cases of NSCLC specimens. TRIM22 protein was upregulated in 70/126 (55.6%) non-small cell lung cancer tissues compared with normal lung tissue. TRIM22 overexpression was associated with advanced TNM stage, positive nodal metastasis and poor prognosis. Plasmid and siRNA transfection were performed in lung cancer cell lines. TRIM22 overexpression promoted proliferation, colony formation and invasion in A549 cells. While its depletion exhibited the opposite effects in H1299 cell line. TRIM22 overexpression promoted cell cycle progression through regulation of cyclin D1, cyclin E and p27. TRIM22 also changed the expression of epithelial to mesenchymal transition (EMT) markers including E-cadherin N-cadherin, Vimentin and Snail. Furthermore, TRIM22 activated PI3K/AKT/GSK3β/β-catenin oncogenic signaling pathways. Treatment with PI3K inhibitor LY294002 and β-catenin siRNA blocked the effects of TRIM22 on EMT in TRIM22-overexpressing cells. In conclusion,TRIM22 serves as an important oncoprotein and a promoter of cell proliferation and invasion through AKT/ GSK3β/β-catenin induced EMT in NSCLC.

LncRNA ANCR down-regulation promotes TGF-β-induced EMT and metastasis in breast cancer

Epithelial to mesenchymal transition (EMT) is a progression of cellular plasticity critical for development, differentiation, cancer cells migration and tumor metastasis. As a well-studied factor, TGF-β participates in EMT and involves in physiological and pathological functions of tumor progression. Accumulating evidence indicates that long noncoding RNAs(lncRNAs) play crucial roles in EMT and tumor metastasis. Here, we find that lncRNA ANCR participates in TGF-β1-induced EMT. By our ChIP and Real-time PCR assays, we reveal that TGF-β1 down-regulates ANCR expression by increasing HDAC3 enrichment at ANCR promoter region, which decreases both H3 and H4 acetylation of ANCR promoter. In addition, by western blot and transwell assays, we indicate that ectopic expression of ANCR partly attenuates the TGF-β1-induced EMT. Downstream, ANCR inhibits breast cancer cell migration and breast cancer metastasis by decreasing RUNX2 expression in vitro and in vivo. Thus, our study identifies ANCR, as a new TGF-β downstream molecular, is essential for TGF-β1-induced EMT by decreasing RUNX2 expression. These results implicate that ANCR might become a prognostic biomarker and an anti-metastasis therapy target for breast cancer.

TGFΒ-induced transcription in cancer

The Transforming Growth Factor-beta (TGFβ) pathway mediates a broad spectrum of cellular processes and is involved in several diseases, including cancer. TGFβ has a dual role in tumours, acting as a tumour suppressor in the early phase of tumorigenesis and as a tumour promoter in more advanced stages. In this review, we discuss the effects of TGFβ-driven transcription on all stages of tumour progression, with special focus on lung cancer. Since some TGFβ target genes are specifically involved in promoting metastasis, we speculate that these genes might be good targets to block tumour progression without compromising the tumour suppressor effects of the TGFβ pathway.