EMT Transition States during Tumor Progression and Metastasis

AXL Controls Directed Migration of Mesenchymal Triple-Negative Breast Cancer Cells

Triple-negative breast cancer (TNBC) is an aggressive form of breast cancer with high risk of relapse and metastasis. TNBC is a heterogeneous disease comprising different molecular subtypes including those with mesenchymal features. The tyrosine kinase AXL is expressed in mesenchymal cells and plays a role in drug resistance, migration and metastasis. We confirm that AXL is more expressed in mesenchymal TNBC cells compared to luminal breast cancer cells, and that its invalidation impairs cell migration while having no or little effect on cell viability. Here, we found that AXL controls directed migration. We observed that AXL displays a polarized localization at the Golgi apparatus and the leading edge of migratory mesenchymal TNBC cells. AXL co-localizes with F-actin at the front of the cells. In migratory polarized cells, the specific AXL inhibitor R428 displaces AXL and F-actin from the leading edge to a lateral area localized between the front and the rear of the cells where both are enriched in protrusions. In addition, R428 treatment disrupts the polarized localization of the Golgi apparatus towards the leading edge in migratory cells. Immunohistochemical analysis of aggressive chemo-resistant TNBC samples obtained before treatment reveals inter- and intra-tumor heterogeneity of the percentage of AXL expressing tumor cells, and a preference of these cells to be in contact with the stroma. Taken together, our study demonstrates that AXL controls directed cell migration most likely by regulating cell polarity.

Updates on mechanistic insights and targeting of tumour metastasis

Malignant tumours are one of the major diseases that seriously endanger human health. The characteristics of their invasion and metastasis are one of the main causes of death in cancer patients, and these features cannot be separated from the participation of various molecules-related cells living in the tumour microenvironment and specific structures. Tumour invasion can approximately be divided into several specific steps according to the movement of tumour cells. In each step, there are different actions in the tumour microenvironment that mediate the interactions among substances. Researchers are attempting to clarify every mechanism of the tumour dissemination. However, there is still a long way to the final determination. Here, we review these interactions in tumour invasion and metastasis at the structural, molecular and cellular levels. We also discuss the ongoing studies and the promise of targeting metastasis in tumour therapy.

HMGA Genes and Proteins in Development and Evolution

HMGA (high mobility group A) (HMGA1 and HMGA2) are small non-histone proteins that can bind DNA and modify chromatin state, thus modulating the accessibility of regulatory factors to the DNA and contributing to the overall panorama of gene expression tuning. In general, they are abundantly expressed during embryogenesis, but are downregulated in the adult differentiated tissues. In the present review, we summarize some aspects of their role during development, also dealing with relevant studies that have shed light on their functioning in cell biology and with emerging possible involvement of HMGA1 and HMGA2 in evolutionary biology.

Calcitriol inhibits migration and invasion of renal cell carcinoma cells by suppressing Smad2/3-, STAT3- and β-catenin-mediated epithelial-mesenchymal transition

Low vitamin D status is associated with progression in patients with renal cell carcinoma (RCC). The present study found that vimentin, a mesenchymal marker, was accordingly upregulated, and E-cadherin, an epithelial marker, was downregulated in RCC patients with low vitamin D status. Thus, we investigated the effects of calcitriol or vitamin D3, an active form of vitamin D, on epithelial-mesenchymal transition (EMT) in RCC cells. RCC cells were treated by two models. In model 1, three RCC cell lines, ACHN, 786-O and CAKI-2, were incubated with either LPS (2.0 μg/mL) or transforming growth factor (TGF)-β1 (10 ng/mL) in the presence or absence of calcitriol (200 nmol/L). In model 2, two RCC cell lines, ACHN and CAKI-2, were incubated with calcitriol (200 nmol/L) only. Calcitriol inhibited migration and invasion not only in TGF-β1-stimulated but also in TGF-β1-unstimulated RCC cells. Moreover, calcitriol suppressed E-cadherin downregulation and vimentin upregulation not only in TGF-β1-stimulated but also in TGF-β1-unstimulated ACHN and CAKI-2 cells. Calcitriol attenuated LPS-induced upregulation of MMP-2, MMP-7, MMP-9, MMP-26 and urokinase-type plasminogen activator (u-PA) in ACHN cells. In addition, calcitriol blocked TGF-β1-induced nuclear translocation of ZEB1, Snail and Twist1 in ACHN and CAKI-2 cells. Mechanistically, calcitriol suppressed EMT through different signaling pathways: (i) calcitriol suppressed Smad2/3 phosphorylation by reinforcing physical interaction between vitamin D receptor (VDR) and Smad3 in TGF-β1-stimulated RCC cells; (ii) calcitriol inhibited signal transducer and activator of transcription (STAT)3 activation in LPS-stimulated RCC cells; (iii) calcitriol inhibited β-catenin/TCF-4 activation by promoting integration of VDR with β-catenin in TGF-β1-unstimulated RCC cells. Taken together, calcitriol inhibits migration and invasion of RCC cells partially by suppressing Smad2/3-, STAT3- and β-catenin-mediated EMT.

TGFβ1-induced beta-site APP-cleaving enzyme 2 upregulation promotes tumorigenesis through the NF-κB signalling pathway in human gliomas

Gliomas are the most common primary malignant tumours of the central nervous system, and new molecular biomarkers are urgently needed for diagnosis and targeted therapy. Here, we report that increased beta-site APP-cleaving enzyme 2 (BACE2) expression is associated with increases in the grade of human glioma, the incidence of the mesenchymal molecular glioblastoma multiforme subtype and the likelihood of poor prognoses for patients. BACE2 knockdown suppressed cell invasion, cell migration and tumour growth both in vitro and in vivo, while BACE2 overexpression promoted the mesenchymal transition and cell proliferation. Furthermore, TGFβ1 stimulated BACE2 expression through Smad-dependent signalling, which modulated TNF-α-induced NF-κB activity through the PP1A/IKK pathway to promote tumorigenesis in both U87MG and U251 cells. Our study indicated that BACE2 plays a significant role in glioma development. Therefore, BACE2 is a potential therapeutic target for human gliomas due to its function and ability to be regulated.

Metabolic Fitness and Plasticity in Cancer Progression

Cancer cells have enhanced metabolic needs due to their rapid proliferation. Moreover, throughout their progression from tumor precursors to metastases, cancer cells face challenging physiological conditions, including hypoxia, low nutrient availability, and exposure to therapeutic drugs. The ability of cancer cells to tailor their metabolic activities to support their energy demand and biosynthetic needs throughout disease progression is key for their survival. Here, we review the metabolic adaptations of cancer cells, from primary tumors to therapy resistant cancers, and the mechanisms underpinning their metabolic plasticity. We also discuss the metabolic coupling that can develop between tumors and the tumor microenvironment. Finally, we consider potential metabolic interventions that could be used in combination with standard therapeutic approaches to improve clinical outcome.

Positive feedback loop of FAM83A/PI3K/AKT/c-Jun induces migration, invasion and metastasis in hepatocellular carcinoma

FAM83A is part of an 8-member protein family of unknown function and is reported to be a cancer-promoting and treatment-resistance factor in several cancers. However, its role in hepatocellular carcinoma (HCC) remains unclear. Analysis of the Cancer Genome Atlas (TCGA) showed that FAM83A mRNA expression is upregulated in HCC, as are the protein expression levels in both HCC cell lines and tissues. Clinical data have demonstrated that high FAM83A expression is positively correlated with poor progression-free survival time, thus suggesting its cancer-promoting potential. Functional analyses showed that FAM83A overexpression promoted HCC cell migration and invasion in vitro and suppressed sorafenib sensitivity. Inhibiting FAM83A reversed these results. A pulmonary metastasis model further confirmed that FAM83A promoted HCC cell metastasis in vivo. Mechanistic analyses indicated that FAM83A activated the PI3K/AKT signaling pathway, its downstream c-JUN protein, and epithelial-to-mesenchymal transition (EMT)-related protein levels, including downregulation of E-cadherin and upregulation of Vimentin and N-cadherin. Interestingly, c-JUN induced FAM83A expression by directly binding to its promoter region and thus forming a positive-feedback loop for FAM83A/PI3K/AKT/c-JUN. In conclusion, we demonstrated that FAM83A, as a cancer-metastasis promoter, accelerates migration, invasion and metastasis by activating the PI3K/AKT/c-JUN pathway and inducing its self-expression via feedback, thus forming a FAM83A/PI3K/AKT/c-JUN positive-feedback loop to activate EMT signaling and finally promote HCC migration, invasion and metastasis.

MAGI1 Inhibits the Proliferation, Migration and Invasion of Glioma Cells

Background

Membrane-associated guanylate kinase inverted repeat member 1 (MAGI1) acts as a tumor suppressor in a variety of tumors; however, its expression and biological function in glioma are still unknown.

Methods

MAGI1 expression in glioma was examined by immunohistochemistry. In addition, overexpression of MAGI1 in U87 and U373 cells, colony formation and MTT assays were used to evaluate cell proliferation, Transwell assays to determine cell migration and invasion, and a xenograft model established using U87 cells to evaluate the effect of MAGI1 overexpression in vivo. Western blot assays were used to analyze the Akt, MMP2, MMP9 and E-cadherin/N-cadherin/vimentin pathway changes after overexpression of MAGI1.

Results

We demonstrated that MAGI1 was expressed at low levels in glioma. Low MAGI1 expression was positively correlated with the malignant progression of glioma and indicated a poor prognosis. Moreover, we found that overexpressed MAGI1 inhibited the proliferation, migration and invasion of glioma cells by regulating cell growth and EMT through Akt, MMP2, MMP9 and the E-cadherin/N-cadherin/vimentin pathway.

Conclusion

These findings demonstrate a novel function of MAGI1 in glioma progression and suggest that MAGI1 might be a target for the diagnosis and treatment of glioma.

Genetically Engineered Lung Cancer Cells for Analyzing Epithelial-Mesenchymal Transition

Cell plasticity, defined as the ability to undergo phenotypical transformation in a reversible manner, is a physiological process that also exerts important roles in disease progression. Two forms of cellular plasticity are epithelial-mesenchymal transition (EMT) and its inverse process, mesenchymal-epithelial transition (MET). These processes have been correlated to the poor outcome of different types of neoplasias as well as drug resistance development. Since EMT/MET are transitional processes, we generated and validated a reporter cell line. Specifically, a far-red fluorescent protein was knocked-in in-frame with the mesenchymal gene marker VIMENTIN (VIM) in H2170 lung cancer cells. The vimentin reporter cells (VRCs) are a reliable model for studying EMT and MET showing cellular plasticity upon a series of stimulations. These cells are a robust platform to dissect the molecular mechanisms of these processes, and for drug discovery in vitro and in vivo in the future.

Genome-wide screening of abberant methylated drivers combined with relative risk loci in bladder cancer

Background

To explore important methylation‐driven genes (MDGs) and risk loci to construct risk model for prognosis of bladder cancer (BCa).

Methods

We utilized TCGA‐Assembler package to download 450K methylation data and corresponding transcriptome profiles. MethylMix package was used for identifying methylation‐driven genes and functional analysis was mainly performed based on ConsensusPathDB database. Then, Cox regression method was utilized to find prognostic MDGs, and we selected 17 hub genes via stepwise regression and multivariate Cox models. Kruskal‐Wallis test was implemented for comparisons between risk with other clinical variables. Moreover, we constructed the risk model and validated it in http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE13507. Gene set enrichment analysis was performed using the levels of risk score as the phenotype. Additionally, we further screened out the relative methylation sites associated with the 17 hub genes. Cox regression and Survival analysis were conducted to find the specifically prognostic sites.

Results

Two hundred and twenty‐eight MDGs were chosen by ConsensusPathDB database. Results revealed that most conspicuous pathways were transcriptional mis‐regulation pathways in cancer and EMT. After Cox regression analysis, 17 hub epigenetic MDGs were identified. We calculated the risk score and found satisfactory predictive efficiency by ROC curve (AUC = 0.762). In the validation group from http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE13507, 17 hub genes remained higher predictive value with AUC = 0.723 and patients in high‐risk group. Meanwhile, Kruskal‐Wallis test revealed that higher risk score correlated with a higher level of TNM stage, tumor grade, and advanced pathological stages. Then, identified 38 risk methylated loci that highly associated with prognosis. Last, gene set enrichment analysis revealed that high‐risk level of MDGs may correlate with several important pathways, including MAPK signaling pathway and so on.

Conclusion

Our study indicated several hub‐MDGs, calculated novel risk score and explored the prognostic value in BCa, which provided a promising approach to BCA prognosis assessment.

BRCA1-associated protein inhibits glioma cell proliferation and migration and glioma stem cell self-renewal via the TGF-β/PI3K/AKT/mTOR signalling pathway

PURPOSE

BRCA1-associated protein (BRAP) was first identified by its ability to bind to the nuclear localization signalling motif of BRCA1 and other proteins. Subsequently, human BRAP has been found to exert multiple functions, many of which are related to cancer development. Up till now, however, the role of BRAP in glioma development has remained obscure. Here, we report a role for BRAP in mediating the proliferation and migration of glioma cells both in vitro and in vivo.

METHODS

The expression of BRAP in 98 glioma patient samples was determined by immunohistochemistry, after which associations between BRAP expression and patient prognosis were assessed. A short hairpin RNA (shRNA) was used to knock down BRAP and an expression vector was used to exogenously overexpress BRAP in glioma cells. The effects of BRAP expression on tumour cell behaviour in vitro and in an in vivo xenograft mouse model were examined.

RESULTS

We found that in glioma patients BRAP expression was associated with a favourable prognosis. We also found that shRNA-mediated knockdown of BRAP facilitated the proliferation and migration of glioma cells and the self-renewal of glioma stem cells. In parallel, we found that BRAP knockdown increased tumour growth and invasion and decreased survival in an in vivo glioma xenograft mouse model. Mechanistically, we found that BRAP inhibited glioma cell proliferation and migration, as well as glioma stem cell self-renewal via the TGF-β/PI3K/AKT/mTOR signalling pathway.

CONCLUSIONS

Together, our findings identify BRAP as a mediator of glioma cell proliferation, migration and glioma stem cell self-renewal.

Long Non-Coding RNA: Dual Effects on Breast Cancer Metastasis and Clinical Applications

As a highly heterogeneous malignancy, breast cancer (BC) has become the most significant threat to female health. Distant metastasis and therapy resistance of BC are responsible for most of the cases of mortality and recurrence. Distant metastasis relies on an array of processes, such as cell proliferation, epithelial-to-mesenchymal transition (EMT), mesenchymal-to-epithelial transition (MET), and angiogenesis. Long non-coding RNA (lncRNA) refers to a class of non-coding RNA with a length of over 200 nucleotides. Currently, a rising number of studies have managed to investigate the association between BC and lncRNA. In this study, we summarized how lncRNA has dual effects in BC metastasis by regulating invasion, migration, and distant metastasis of BC cells. We also emphasize that lncRNA has crucial regulatory effects in the stemness and angiogenesis of BC. Clinically, some lncRNAs can regulate chemotherapy sensitivity in BC patients and may function as novel biomarkers to diagnose or predict prognosis for BC patients. The exact impact on clinical relevance deserves further study. This review can be an approach to understanding the dual effects of lncRNAs in BC, thereby linking lncRNAs to quasi-personalized treatment in the future.

RASSF6-TRIM16 axis promotes cell proliferation, migration and invasion in esophageal squamous cell carcinoma

Ras-association (RA) domain family number 6 (RASSF6) is a member of the Ras-association domain protein family. It is epigenetically inactive and negatively regulates the malignant progression of some tumors. However, its precise role in esophageal squamous cell carcinoma (ESCC) has not been reported. In this study, we performed immunohistochemistry (IHC) assay. The results show that RASSF6 is upregulated in ESCC and that the elevated expression level of RASSF6 is associated with lymph node metastasis and poor survival of ESCC patients. Consistent with the clinical observations, the upregulation of RASSF6 greatly promotes ESCC cell proliferation, migration and invasion as well as the cell cycle transition to G1/S phase in vitro. According to models in vivo, the downregulation of RASSF6 considerably inhibits ESCC tumor growth and lung metastasis. Mechanistically, RASSF6 negatively regulates the tumor suppressor tripartite-motif-containing protein 16 (TRIM16) by promoting its ubiquitination-dependent degradation and eventually activates pathways associated with the cell cycle and epithelial-mesenchymal transition (EMT). Together, these results indicate that the RASSF6-TRIM16 axis is a key effector in ESCC progression and that RASSF6 serves as a potential target for the treatment of ESCC.

Targeting Epithelial Mesenchymal Plasticity in Pancreatic Cancer: A Compendium of Preclinical Discovery in a Heterogeneous Disease

Pancreatic Ductal Adenocarcinoma (PDAC) is a particularly insidious and aggressive disease that causes significant mortality worldwide. The direct correlation between PDAC incidence, disease progression, and mortality highlights the critical need to understand the mechanisms by which PDAC cells rapidly progress to drive metastatic disease in order to identify actionable vulnerabilities. One such proposed vulnerability is epithelial mesenchymal plasticity (EMP), a process whereby neoplastic epithelial cells delaminate from their neighbours, either collectively or individually, allowing for their subsequent invasion into host tissue. This disruption of tissue homeostasis, particularly in PDAC, further promotes cellular transformation by inducing inflammatory interactions with the stromal compartment, which in turn contributes to intratumoural heterogeneity. This review describes the role of EMP in PDAC, and the preclinical target discovery that has been conducted to identify the molecular regulators and effectors of this EMP program. While inhibition of individual targets may provide therapeutic insights, a single 'master-key' remains elusive, making their collective interactions of greater importance in controlling the behaviours' of heterogeneous tumour cell populations. Much work has been undertaken to understand key transcriptional programs that drive EMP in certain contexts, however, a collaborative appreciation for the subtle, context-dependent programs governing EMP regulation is needed in order to design therapeutic strategies to curb PDAC mortality.

MST4 Predicts Poor Prognosis And Promotes Metastasis By Facilitating Epithelial-Mesenchymal Transition In Gastric Cancer

Background

Metastasis is the main cause for gastric cancer (GC)-related deaths. Better understanding of GC metastatic mechanism would provide novel diagnostic markers and therapeutic targets. Though it has been reported that mammalian sterile-20-like kinase 4 (MST4) exerts the oncogenic role in other tumors, the prognostic value and biological role of MST4 in GC are still unknown.

Methods

The expression level of MST4 in GC was analyzed by using TCGA database. Then, Western blot and polymerase chain reaction (PCR) were used to determine the MST4 expression in GC tissues and cell lines. Immunohistochemistry was performed to investigate the expression of proteins in human GC tissues, and its correlation with clinicopathologic parameters as well as the prognosis for patients with GC was analyzed. In addition, the biological function and its molecular mechanism of MST4 in GC were investigated by in vitro and in vivo assays.

Results

It demonstrated that MST4 expression was significantly upregulated in GC tissues and cell lines. High expression of MST4 was correlated with aggressive clinicopathological parameters such as lymph node metastasis, lymphovascular invasion (all P < 0.05). GC patients with high MST4 expression had both shorter overall survival (OS) and disease-free survival (DFS) than those with low MST4 expression (all P < 0.05). MST4 expression was an independent and significant risk factor for OS and DFS of GC patients (all P < 0.05). Results of functional experiments showed that MST4 could promote GC cells migration, invasion in vitro and metastasis in vivo. In terms of mechanism, MST4 promoted metastasis by facilitating epithelial–mesenchymal transition (EMT) through activating Ezrin pathway in GC. Further studies indicate that down-regulated miR-124-3p expression contributes to upregulated MST4 expression in GC.

Conclusion

Our data showed that MST4 predicts poor prognosis and promotes metastasis by facilitating epithelial–mesenchymal transition in GC. Therefore, our study suggests that MST4 can be used as a valuable prognostic biomarker and a potential therapeutic target in GC.

LOXL 2 Promotes The Epithelial-Mesenchymal Transition And Malignant Progression Of Cervical Cancer

Purpose

Increasing evidence suggests that lysyl oxidase-like 2 (LOXL2) contributes to tumor progression. However, the role of LOXL2 in cervical cancer still remains unclear.

Patients and methods

We used the TCGA database to analyze the expression of LOXL2 in cervical cancer and its role on survival. The effects of LOXL2 on cervical cancer metastasis and EMT were verified by transwell and wound healing assay. Western blot assay was used to detect the effect of LOXL2 on EMT-related gene expression. In addition, we used animal experiments to observe the role of LOXL2 on tumor genesis and metastasis in cervical cancer.

Results

Here we found that LOXL2 participates in epithelial–mesenchymal transition-related cervical cancer progression. LOXL2 ablation in cervical cancer cells inhibited cell metastatic ability, whereas LOXL2 overexpression promoted cell metastasis. In addition, more clinical data from TCGA revealed that LOXL2 is closely related to the prognosis and is highly expressed in highly malignant and metastatic cervical tumors.

Conclusion

Taken together, our findings established a pathophysiologic role and new function for LOXL2 in cervical cancer metastasis.

Ribosomal protein uL3 targets E2F1 and Cyclin D1 in cancer cell response to nucleolar stress

Several experimental strategies in the treatment of cancer include drug alteration of cell cycle regulatory pathways as a useful strategy. Extra-ribosomal functions of human ribosomal protein L3 (uL3) may affect DNA repair, cell cycle arrest and apoptosis. In the present study, we demonstrated that uL3 is required for the activation of G1/S transition genes. Luciferase assays established that uL3 negatively regulates the activity of E2F1 promoter. Induced ribosome-free uL3 reduces Cyclin D1 mRNA and protein levels. Using protein/protein immunoprecipitation methods, we demonstrated that uL3 physically interacts with PARP-1 affecting E2F1 transcriptional activity. Our findings led to the identification of a new pathway mediated by uL3 involving E2F1 and Cyclin D1 in the regulation of cell cycle progression.

Silencing circular RNA hsa_circ_0004491 promotes metastasis of oral squamous cell carcinoma

AIMS

Oral squamous cell carcinoma (OSCC) is an oral cavity malignancy which is the eighth most common cancer. However, the molecular mechanisms underlying the pathogenesis of OSCC remain largely unknown, and effective methods for the prognosis and diagnosis of this disease are lacking. Circular RNAs (circRNAs) are widely expressed among mammals. A growing number of studies have shown that circRNA expression is altered in cancers. In this study, we investigated the role of hsa_circ_0004491 in OSCC cell migration and invasion and examined the clinical characteristics associated with its expression.

MAIN METHODS

Hsa_circ_0004491 expression was examined in 40 paired OSCC and normal tissue samples using quantitative real-time PCR (qRT-PCR). Wound healing, transwell and western blotting assays were conducted in OSCC cells up- or down-regulation of hsa_circ_0004491 to evaluate changes in cell migration, invasion and protein expression. KEYFINDINGS: qRT-PCR analysis revealed that hsa_circ_0004491 was significantly downregulated in OSCC tissues compared with paired normal tissues (P < 0.001), and this low expression was associated with lymph node metastasis (P = 0.0398; area under ROC curve = 0.7510). Hsa_circ_000449 silencing or overexpression significantly affected the invasion and migration abilities of OSCC cells. Western blotting analysis showed that EMT-related proteins expression was significantly changed after hsa_circ_000449 silencing or overexpression.

SIGNIFICANCE

The expression level of hsa_circ_0004491 affects the migration and invasion of OSCC cells. Hsa_circ_0004491 may therefore play a role in the progression of oral squamous cell carcinoma.

Impact of the actin cytoskeleton on cell development and function mediated via tropomyosin isoforms

The physiological function of actin filaments is challenging to dissect because of the pleiotropic impact of global disruption of the actin cytoskeleton. Tropomyosin isoforms have provided a unique opportunity to address this issue. A substantial fraction of actin filaments in animal cells consist of co-polymers of actin with specific tropomyosin isoforms which determine the functional capacity of the filament. Genetic manipulation of the tropomyosins has revealed isoform specific roles and identified the physiological function of the different actin filament types based on their tropomyosin isoform composition. Surprisingly, there is remarkably little redundancy between the tropomyosins resulting in highly penetrant impacts of both ectopic overexpression and knockout of isoforms. The physiological roles of the tropomyosins cover a broad range from development and morphogenesis to cell migration and specialised tissue function and human diseases.

Tex10 promotes stemness and EMT phenotypes in esophageal squamous cell carcinoma via the Wnt/β‑catenin pathway

A previous study by our group suggested that testis expressed 10 (Tex10) contributes to tumor progression by promoting stem cell-like features in hepatocellular carcinoma. However, the relevance of pluripotency factor Tex10 in esophageal squamous cell carcinoma (ESCC) has remained elusive. The objective of the present study was to investigate the role of Tex10 in ESCC. For this purpose, the mRNA and protein expression of Tex10 was detected by reverse transcription-quantitative PCR, western blot analysis and immunohistochemistry. In a loss-of-function experiment, EC109 cells were transfected with lentiviral vectors containing Tex10 short hairpin RNA or negative control. Cell proliferation was assessed using a Cell Counting kit-8, and flow cytometry was used to analyze apoptosis and the cell cycle. Transwell assays were employed to examine the migratory and invasive capacity, and a sphere formation assay was performed to assess the clonogenicity of the EC109 cells. The results revealed that the elevated expression of Tex10 was positively associated with malignancy and with epithelial-mesenchymal transition (EMT)-associated mesenchymal markers in human ESCC specimens. The knockdown of Tex10 led to the inhibition of cell proliferation, the induction of apoptosis and cell cycle arrest, and decreased the stemness, migratory and invasive capacity of the EC109 cells. Furthermore, the silencing of Tex10 enhanced the sensitivity of the ESCC cells to 5-fluorouracil. In addition, the present study revealed that Tex10 plays an essential role in regulating EMT via the activation of Wnt/β-catenin signaling. On the whole, the findings of the present study suggest that the downregulation of Tex10 in ESCC specimens is significantly associated with tumor malignancy, and that Tex10 promotes stem cell-like features and induces the EMT of ESCC cells through the enhancement of Wnt/β-catenin signaling.

PRR14 overexpression promotes cell growth, epithelial to mesenchymal transition and metastasis of colon cancer via the AKT pathway

Background

PRR14 (Proline rich protein 14) was firstly identified for its ability to specify and localize heterochromatin during cell cycle progression. Aberrant expression of PRR14 is associated with the tumorigenesis and progression of lung cancer. However, its involvement in colon cancer remains unknown. Herein, we report the role of PRR14 in colon cancer.

Methods

Colon cancer tissue microarray was used to analyze and compare the expression of PRR14 among some clinicopathological characteristics of colon cancer. HCT116 and RKO cells were transfected with siRNA to downregulate PRR14 expression. The roles of PRR14 in proliferation, migration and invasion of the cell lines were determined using cell counting kit-8, colony formation assay, wound healing assay and transwell assays respectively. The expression of PRR14 was measured using immunofluorescence, qRT- PCR and western blot. Epithelial-mesenchymal transition (EMT) markers were determined by western blot.

Results

PRR14 was highly expressed in colon cancer tissues, and the expression level was correlated with tumor size, distant metastasis and Tumor Node Metastasis stages. Functional study revealed that downregulation of PRR14 inhibited colon cancer cells growth, migration and invasion. Furthermore, knockdown of PRR14 inhibited epithelial-mesenchymal transition (EMT) process, cell cycle-associated proteins expression and p-AKT level.

Conclusion

PRR14 may promote the progression and metastasis of colon cancer, and may be a novel prognostic and therapeutic marker for the disease.

Role of E2Fs and mitotic regulators controlled by E2Fs in the epithelial to mesenchymal transition

The epithelial-to-mesenchymal transition (EMT) is a complex cellular process in which epithelial cells acquire mesenchymal properties. EMT occurs in three biological settings: development, wound healing and fibrosis, and tumor progression. Despite occurring in three independent biological settings, EMT signaling shares some molecular mechanisms that allow epithelial cells to de-differentiate and acquire mesenchymal characteristics that confer cells invasive and migratory capacity to distant sites. Here we summarize the molecular mechanism that delineates EMT and we will focus on the role of E2 promoter binding factors (E2Fs) in EMT during tumor progression. Since the E2Fs are presently undruggable due to their control in numerous pivotal cellular functions and due to the lack of selectivity against individual E2Fs, we will also discuss the role of three mitotic regulators and/or mitotic kinases controlled by the E2Fs (NEK2, Mps1/TTK, and SGO1) in EMT that can be useful as drug targets.

Impact statement

The study of the epithelial to mesenchymal transition (EMT) is an active area of research since it is one of the early intermediates to invasion and metastasis—a state of the cancer cells that ultimately kills many cancer patients. We will present in this review that besides their canonical roles as regulators of proliferation, unregulated expression of the E2F transcription factors may contribute to cancer initiation and progression to metastasis by signaling centrosome amplification, chromosome instability, and EMT. Since our discovery that the E2F activators control centrosome amplification and mitosis in cancer cells, we have identified centrosome and mitotic regulators that may represent actionable targets against EMT and metastasis in cancer cells. This is impactful to all of the cancer patients in which the Cdk/Rb/E2F pathway is deregulated, which has been estimated to be most cancer patients with solid tumors.

TIP-B1 promotes kidney clear cell carcinoma growth and metastasis via EGFR/AKT signaling

Kidney clear cell carcinoma (KIRC) is the most prevalent kidney malignancy. Accumulating evidence shows that high expression of TIP-B1 correlates with development of tumor progression. However, the detailed functions of TIP-B1 in the KIRC remain to be further elucidated. Here, we firstly found TIP-B1 expression was significantly increased in KIRC compared with adjacent normal tissues. What’s more, higher expression of TIP-B1 were correlated with aggressive clinico-pathological characteristics. In vitro assay found TIP-B1 knockdown dramatically inhibited KIRC cells proliferation, migration and invasion. In vivo assay found down regulated TIP-B1 could suppress tumor growth and metastasis. Mechanism analysis indicated that TIP-B1 could bind EGFR and suppress EGFR degradation, then promoted EGF-induced AKT signaling. Together, TIP-B1 could be applied as an independent risk factor to predict KIRC progression and metastasis. Targeting TIP-B1 might be a new potential therapeutic strategy for KIRC treatment.

Dynamics of Phenotypic Heterogeneity Associated with EMT and Stemness during Cancer Progression

Genetic and phenotypic heterogeneity contribute to the generation of diverse tumor cell populations, thus enhancing cancer aggressiveness and therapy resistance. Compared to genetic heterogeneity, a consequence of mutational events, phenotypic heterogeneity arises from dynamic, reversible cell state transitions in response to varying intracellular/extracellular signals. Such phenotypic plasticity enables rapid adaptive responses to various stressful conditions and can have a strong impact on cancer progression. Herein, we have reviewed relevant literature on mechanisms associated with dynamic phenotypic changes and cellular plasticity, such as epithelial-mesenchymal transition (EMT) and cancer stemness, which have been reported to facilitate cancer metastasis. We also discuss how non-cell-autonomous mechanisms such as cell-cell communication can lead to an emergent population-level response in tumors. The molecular mechanisms underlying the complexity of tumor systems are crucial for comprehending cancer progression, and may provide new avenues for designing therapeutic strategies.

PD-L1 regulation by SDH5 via β-catenin/ZEB1 signaling

Programmed death-ligand 1 (PD-L1) is a crucial target for lung cancer immunotherapy. In lung cancer patients with high PD-L1 expression, blocking or reducing its expression can inhibit tumor growth. PD-L1 is regulated by signaling pathways, transcription factors and epigenetic factors, such as the GSK3β/β-catenin pathway, P53 protein and EMT. In our previous study, succinate dehydrogenase 5 (SDH5) was reported to regulate ZEB1 expression, induce EMT and lead to lung cancer metastasis via the GSK3β/β-catenin pathway. It is possible that SDH5 is involved in the mechanisms of PD-L1 regulation.In the present study, we observed a negative correlation between the expression of PD-L1 and SDH5 in vivo and in vitro. The examination of patient tissues also confirmed our results. Furthermore, we also found that SDH5 could reverse PD-L1 expression by the GSK3β/β-catenin/ZEB1 pathways. All these results reveal that SDH5 regulates PD-L1 expression and suggest that SDH5 can be used as a marker to predict tumor immune micro-states and provide guidance for clinical immunotherapy.

Cell Heterogeneity and Phenotypic Plasticity in Metastasis Formation: The Case of Colon Cancer

The adenoma-to-carcinoma progression in colon cancer is driven by a sequential accumulation of genetic alterations at specific tumor suppressors and oncogenes. In contrast, the multistage route from the primary site to metastasis formation is underlined by phenotypic plasticity, i.e., the capacity of disseminated tumor cells to undergo transiently and reversible transformations in order to adapt to the ever-changing environmental contexts. Notwithstanding the considerable body of evidence in support of the role played by epithelial-to-mesenchymal transition (EMT)/mesenchymal-to-epithelial transition (MET) in metastasis, its rate-limiting function, the detailed underlying cellular and molecular mechanisms, and the extension of the necessary morphologic and epigenetic changes are still a matter of debate. Rather than leading to a complete epithelial or mesenchymal state, the EMT/MET-program generates migrating cancer cells displaying intermediate phenotypes featuring both epithelial and mesenchymal characteristics. In this review, we will address the role of colon cancer heterogeneity and phenotypic plasticity in metastasis formation and the contribution of EMT to these processes. The alleged role of hybrid epithelial/mesenchymal (E/M) in collective and/or single-cell migration during local dissemination at the primary site and more systemic spreading will also be highlighted.

Dnmt3a is required for the tumor stemness of B16 melanoma cells

The relationship of carcinogenesis and DNA methyltransferases has attracted extensive attention in tumor research. We reported previously that inhibition of de novo DNA methyltransferase 3a (Dnmt3a) in murine B16 melanoma cells significantly suppressed tumor growth and metastasis in xenografted mouse model. Here, we further demonstrated that knockdown of Dnmt3a enhanced the proliferation in anchor-independent conditions of B16 cells, but severely disrupted its multipotent differentiation capacity in vitro. Furthermore, transforming growth factor β1, a key trigger in stem cell differentiation and tumor cell epithelial-mesenchymal transition (EMT), mainly induced apoptosis, but not EMT in Dnmt3a-deficient B16 cells. These data suggested that Dnmt3a is required for maintaining the tumor stemness of B16 cells and it assists B16 cells to escape from death during cell differentiation. Thus it is hypothesized that not only extraordinary self-renewal ability, but also the capacity of multipotent differentiation is necessary for the melanoma tumorigenesis. Inhibition of multipotent differentiation of tumor cells may shed light on the tumor treatment.

The Multifaceted Roles of Pyroptotic Cell Death Pathways in Cancer

Cancer is a category of diseases involving abnormal cell growth with the potential to invade other parts of the body. Chemotherapy is the most widely used first-line treatment for multiple forms of cancer. Chemotherapeutic agents act via targeting the cellular apoptotic pathway. However, cancer cells usually acquire chemoresistance, leading to poor outcomes in cancer patients. For that reason, it is imperative to discover other cell death pathways for improved cancer intervention. Pyroptosis is a new form of programmed cell death that commonly occurs upon pathogen invasion. Pyroptosis is marked by cell swelling and plasma membrane rupture, which results in the release of cytosolic contents into the extracellular space. Currently, pyroptosis is proposed to be an alternative mode of cell death in cancer treatment. Accumulating evidence shows that the key components of pyroptotic cell death pathways, including inflammasomes, gasdermins and pro-inflammatory cytokines, are involved in the initiation and progression of cancer. Interfering with pyroptotic cell death pathways may represent a promising therapeutic option for cancer management. In this review, we describe the current knowledge regarding the biological significance of pyroptotic cell death pathways in cancer pathogenesis and also discuss their potential therapeutic utility.

[Decellularized matrix of human fatty liver used for three-dimensional culture of hepatocellular carcinoma cells]

OBJECTIVE

To construct a decellularized matrix of human fatty liver as the scaffold for three-dimensional (3D) culture of hepatocarcinoma cells.

METHODS

Human fatty liver decellularized matrix (hFLM) was prepared by repeated freezingthawing, perfusion with gradient SDS and 1% Triton X-100 through the portal vein and hepatic artery, and repeated agitation with Triton X-100. HepG2 cells were cultured in the prepared hFLM, and the cell survival, morphology, proliferation and cellular expressions of the adhesion molecules were detected.

RESULTS

The decellularization procedure shortened the time for scaffold preparation and preserved the 3D ultrastructure and the composition of the extracellular matrix. HepG2 cells cultured in hFLM scaffold maintained proliferation for up to 15 days and showed a growth pattern with a long lag phase and a slow growth rate, which was similar to the growth pattern in vivo. The cultured HepG2 exhibited a low expression of E-cadherin and a high expression of vimentin, which was consistent with the xenograft but opposite to 2D cultured cells. However, the lack of adequate nutrient transport in this hepatocarcinoma cell model led to a slowdown of cell proliferation in the later stage. The PCNA index of HepG2 cells cultured in hFLM was lowered by 29.3% on day 12 as compared with that on day 6.

CONCLUSIONS

We established a new protocol for preparing hFLM and confirmed the feasibility of constructing hepatocarcinoma cell models using the hFLM scaffold.

CTCs 2020: Great Expectations or Unreasonable Dreams

Circulating tumor cells (CTCs) are cellular elements that can be scattered into the bloodstream from primary cancer, metastasis, and even from a disseminated tumor cell (DTC) reservoir. CTCs are “seeds”, able to give rise to new metastatic lesions. Since metastases are the cause of about 90% of cancer-related deaths, the significance of CTCs is unquestionable. However, two major issues have stalled their full clinical exploitation: rarity and heterogeneity. Therefore, their full clinical potential has only been predicted. Finding new ways of studying and using such tremendously rare and important events can open new areas of research in the field of cancer research, and could drastically improve tumor companion diagnostics, personalized treatment strategies, overall patients management, and reduce healthcare costs.

FAM83A signaling induces epithelial-mesenchymal transition by the PI3K/AKT/Snail pathway in NSCLC

Family with sequence similarity 83, member A (FAM83A), as a potential tumor promoter, was reported to contribute to the progression of several malignant tumors. However, the significance of FAM83A in invasion and metastasis of non-small cell lung cancer (NSCLC) remains largely unknown. In this study, we found that FAM83A expression was significantly increased in NSCLC tissues. High expression of FAM83A was positively associated with tumor metastasis and poor survival of NSCLC patients. Functional experiments revealed that FAM83A knockdown could suppress NSCLC cell migration and invasion both in vivo and in vitro. While opposite results were observed in FAM83A-transfected cells. Mechanically, we found that FAM83A promoted NSCLC cell migration and invasion by inducing epithelial-mesenchymal transition (EMT) via PI3K/ATK/Snail signaling. Rescue experiment demonstrated that inhibition of either AKT or Snail could partially counteract the promoting effect of FAM83A overexpression in NSCLC metastasis. Taken together, our findings are the first time to demonstrate that increased expression of FAM83A in NSCLC was correlated with EMT and tumor metastasis, which may provide a novel therapeutic target in NSCLC treatment.

LncRNA LINC00460 promotes EMT in head and neck squamous cell carcinoma by facilitating peroxiredoxin-1 into the nucleus

BACKGROUND

The lncRNA LINC00460 plays crucial roles in several epithelial cancers, although its mechanisms of action differ greatly in different cellular contexts. In this study, we aimed to determine the potential clinical applications of LINC00460 and elucidate the mechanisms by which LINC00460 affects the development and progression of head and neck squamous cell carcinoma (HNSCC).

METHODS

The biological functions of LINC00460 were assessed in several epithelial cancer cell lines. The subcellular localization of LINC00460 was evaluated by cell nuclear/cytoplasmic fractionation and fluorescence in situ hybridization. RNA pull-down assays, LS-MS/MS analysis, and RNA and chromatin immunoprecipitation assays were performed to identify the molecular mechanism by which LINC00460 promotes HNSCC progression. The clinical pathological features of LINC00460 and PRDX1 were evaluated in HNSCC tissues and paired adjacent normal tissues.

RESULTS

LINC00460 enhanced HNSCC cell proliferation and metastasis in vitro and in vivo and induced epithelial-mesenchymal transition (EMT). LINC00460 primarily localized within the cytoplasm of HNSCC cells, physically interacted with PRDX1 and facilitated PRDX1 entry into the nucleus. PRDX1 promoted the transcription of LINC00460, forming a positive feedback loop. In addition, PRDX1 also promoted the transcription of EMT-related genes (such as ZEB1, ZEB2 and VIM) through enrichment on gene promoters in the nucleus. LINC00460 effectively induced HNSCC cell EMT in a PRDX1-dependent manner, and PRDX1 mainly mediated the EMT-promoting effect of LINC00460. High levels of LINC00460 and PRDX1 expression were positively associated with lymph metastasis, pathological differentiation and tumor size in HNSCC patients.

CONCLUSIONS

LINC00460 promoted EMT in HNSCC cells by facilitating PRDX1 entry into the nucleus. LINC00460 and PRDX1 are promising candidate prognostic predictors and potential targets for cancer therapy for HNSCC.

TGF-β-induced transgelin promotes bladder cancer metastasis by regulating epithelial-mesenchymal transition and invadopodia formation

Background

Metastatic bladder cancer (BLCA) is a lethal disease with an unmet need for study. Transgelin (TAGLN) is an actin-binding protein that affects the dynamics of the actin cytoskeleton indicating its robust potential as a metastasis initiator. Here, we sought to explore the expression pattern of TAGLN and elucidate its specific functioning and mechanisms in BLCA.

Methods

A comprehensive assessment of TAGLN expression in BLCA was performed in three cohorts with a total of 847 patients. The potential effects of TAGLN on BLCA were further determined using clinical genomic analyses that guided the subsequent functional and mechanistic studies. In vitro migration, invasion assays and in vivo metastatic mouse model were performed to explore the biological functions of TAGLN in BLCA cells. Immunofluorescence, western blot and correlation analysis were used to investigate the molecular mechanisms of TAGLN.

Findings

TAGLN was highly expressed in BLCA and correlated with advanced prognostic features. TAGLN promoted cell colony formation and cell migration and invasion both in vitro and in vivo by inducing invadopodia formation and epithelial-mesenchymal transition, during which a significant correlation between TAGLN and Slug was observed. The progression-dependent correlation between TGF-β and TAGLN was analysed at both the cellular and tissue levels, while TGF-β-mediated migration was abolished by the suppression of TAGLN.

Interpretation

Overall, TAGLN is a promising novel prognosis biomarker of BLCA, and its metastatic mechanisms indicate that TAGLN may represent a novel target agent that can be utilized for the clinical management of invasive and metastatic BLCA.

Fund

This work was supported by the National Natural Science Foundation of China [81772703, 81672546, 81602253]; the Natural Science Foundation of Beijing [71772219, 7152146]. and Innovative Fund for Doctoral Students of Peking University Health Science Center (BUM2018BSS002). Funders had no role in the design of the study, data collection, data analysis, interpretation, or the writing of this report.

Significant epitranscriptomes in heterogeneous cancer

Precision medicine places significant emphasis on techniques for the identification of DNA mutations and gene expression by deep sequencing of gene panels to obtain medical data. However, other diverse information that is not easily readable using bioinformatics, including RNA modifications, has emerged as a novel diagnostic and innovative therapy owing to its multifunctional aspects. It is suggested that this breakthrough innovation might open new avenues for the elucidation of uncharacterized cancer cellular functions to develop more precise medical applications. The functional characteristics and regulatory mechanisms of RNA modifications, ie, the epitranscriptome (ETR), which reflects RNA metabolism, remains unclear, mainly due to detection methods being limited. Recent studies have revealed that N6‐methyl adenosine, the most common modification in mRNA in eukaryotes, is affected in various types of cancer and, in some cases, cancer stem cells, but also affects cellular responses to viral infections. The ETR can control cancer cell fate through mRNA splicing, stability, nuclear export, and translation. Here we report on the recent progress of ETR detection methods, and biological findings regarding the significance of ETR in cancer precision medicine.

Deciphering Hydrodynamic and Drug-Resistant Behaviors of Metastatic EMT Breast Cancer Cells Moving in a Constricted Microcapillary

Epithelial to mesenchymal transition (EMT) induces cell migration, invasion, and drug resistance, and consequently, contributes to cancer metastasis and disease aggressiveness. This study attempted to address crucial biological parameters to correlate EMT and drug-treated cancer cells traversing through microcapillaries, reminiscent of metastatic conditions. MDA-MB-468 breast cancer cells induced to undergo EMT by treatment with 20 ng/mL of epidermal growth factor (EGF) were initially passed through several blockages and then through a constricted microchannel, mimicking the flow of invasive metastatic cells through constricted blood microcapillaries. EMT cells acquired enhanced migratory properties and retained 50% viability, even after migration through wells 10-15 μm in size and a constricted passage of 7 μm and 150 μm in length at a constant flow rate of 50 μL/h. The hydrodynamic properties revealed cellular deformation with a deformation index, average transit velocity, and entry time of 2.45, 12.3 mm/s, and 31,000 μs, respectively for a cell of average diameter 19 μm passing through one of the 7 μm constricted sections. Interestingly, cells collected at the channel outlet regained epithelial character, undergoing reverse transition (mesenchymal to epithelial transition, MET) in the absence of EGF. Remarkably, real-time polymerase chain reaction (PCR) analysis confirmed increases of 2- and 2.7-fold in the vimentin and fibronectin expression in EMT cells, respectively; however, their expression reduced to basal level in the MET cells. A scratch assay revealed the pronounced migratory nature of EMT cells compared with MET cells. Furthermore, the number of colonies formed from EMT cells and paclitaxel-treated EMT cells after passing through a constriction were found to be 95 ± 10 and 79 ± 4, respectively, confirming that the EMT cells were more drug resistant with a concomitant two-fold higher expression of the multi-drug resistance (MDR1) gene. Our results highlight the hydrodynamic and drug-evading properties of cells that have undergone an EMT, when passed through a constricted microcapillary that mimics their journey in blood circulation.

WTAP is a prognostic marker of high-grade serous ovarian cancer and regulates the progression of ovarian cancer cells

Background

The Wilms' tumor suppressor WT1 is reported to work in a range of physiological processes at both transcriptional and posttranscriptional level. WT1-associating protein (WTAP), a nuclear protein co-localized with splicing factors, also plays a vital role in cellular function and cancer progression. However, little is known about the role of WTAP in ovarian cancer and the underlying mechanism.

Materials and methods

To evaluate the expression of WTAP, multiple means were applied in clinical tissues, including immunohistochemistry, quantitative reverse transcriptase PCR (qRT-PCR), and Western blot. Two representative ovarian cancer cell lines (3AO and SKOV3) were used to assess the malignant influence of WTAP on proliferation, apoptosis, and migration. To explore its function, WTAP was additionally down-regulated by lentivirus.

Results

High expression of WTAP in high-grade serous ovarian carcinoma (HGSOC) predicted a shorter overall survival (P<0.01). Furthermore, WTAP expression was higher in HGSOC, compared with that in normal ovary group (P<0.01), benign ovarian tumor group (P<0.01), and non-HGSOC group (P<0.05). In HGSOC, high expression of WTAP was significantly related with the lymph node metastasis (P<0.05). In ovarian cancer cell lines, cell proliferation and migration were considerably reduced after WTAP was down-regulated, while apoptotic rate was increased. Moreover, the effect of WTAP in 3AO and SKOV3 might be relevant with MAPK and AKT signaling pathways.

Conclusion

WTAP is highly expressed in HGSOC, and indicates a worse survival outcome. Therefore, it is highly possible that WTAP has a prognostic implication in the patients of HGSOC. In addition, WTAP down-regulation also plays a tumor suppressor role in 3AO and SKOV3 cell lines.

Gold Nanoparticles sensitize pancreatic cancer cells to gemcitabine

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest solid cancers with dismal prognosis. Several mechanisms that are mainly responsible for aggressiveness and therapy resistance of PDAC cells include epithelial to mesenchymal transition (EMT), stemness and Mitogen Activated Protein Kinase (MAPK) signaling. Strategies that inhibit these mechanisms are critically important to improve therapeutic outcome in PDAC. In the current study, we wanted to investigate whether gold nanoparticles (AuNPs) could sensitize pancreatic cancer cells to the chemotherapeutic agent gemcitabine. We demonstrated that treatment with AuNPs of 20 nm diameter inhibited migration and colony forming ability of pancreatic cancer cells. Pre-treatment with AuNPs sensitized pancreatic cancer cells to gemcitabine in both viability and colony forming assays. Mechanistically, pre-treatment of pancreatic cancer cells with AuNPs decreased gemcitabine induced EMT, stemness and MAPK activation. Taken together, these findings suggest that AuNPs could be considered as a potential agent to sensitize pancreatic cancer cells to gemcitabine.

ZEB2 in T-cells and T-ALL

The identification of the rare but recurrent t(2; 14)(q22; q32) translocation involving the ZEB2 locus in T-cell acute lymphoblastic leukemia, suggested that ZEB2 is an oncogenic driver of this high-risk subtype of leukemia. ZEB2, a zinc finger E-box homeobox binding transcription factor, is a master regulator of cellular plasticity and its expression is correlated with poor overall survival of cancer patients. Recent loss- and gain-of-function in the mouse revealed important roles of ZEB2 during different stages of hematopoiesis, including the T-cell lineage. Here, we summarize the roles of ZEB2 in T-cells, their development, and malignant transformation to T-ALL.

KLF4 Regulates Corneal Epithelial Cell Cycle Progression by Suppressing Canonical TGF-β Signaling and Upregulating CDK Inhibitors P16 and P27

Purpose

Krüppel-like factor 4 (KLF4) promotes corneal epithelial (CE) cell fate while suppressing mesenchymal properties. TGF-β plays a crucial role in cell differentiation and development, and if dysregulated, it induces epithelial-mesenchymal transition (EMT). As KLF4 and TGF-β regulate each other in a context-dependent manner, we evaluated the role of the crosstalk between KLF4 and TGF-β-signaling in CE homeostasis.

Methods

We used spatiotemporally regulated ablation of Klf4 within the adult mouse CE in ternary transgenic Klf4^Δ/ΔCE (Klf4^LoxP/LoxP/ Krt12^rtTA/rtTA/ Tet-O-Cre) mice and short hairpin RNA (shRNA)-mediated knockdown or lentiviral vector-mediated overexpression of KLF4 in human corneal limbal epithelial (HCLE) cells to evaluate the crosstalk between KLF4 and TGF-β-signaling components. Expression of TGF-β signaling components and cyclin-dependent kinase (CDK) inhibitors was quantified by quantitative PCR, immunoblots, and/or immunofluorescent staining.

Results

CE-specific ablation of Klf4 resulted in (1) upregulation of TGF-β1, -β2, -βR1, and -βR2; (2) downregulation of inhibitory Smad7; (3) hyperphosphorylation of Smad2/3; (4) elevated nuclear localization of phospho-Smad2/3 and Smad4; and (5) downregulation of CDK inhibitors p16 and p27. Consistently, shRNA-mediated knockdown of KLF4 in HCLE cells resulted in upregulation of TGF-β1 and -β2, hyperphosphorylation and nuclear localization of SMAD2/3, downregulation of SMAD7, and elevated SMAD4 nuclear localization. Furthermore, overexpression of KLF4 in HCLE cells resulted in downregulation of TGF-β1, -βR1, and -βR2 and upregulation of SMAD7, p16, and p27.

Conclusions

Collectively, these results demonstrate that KLF4 regulates CE cell cycle progression by suppressing canonical TGF-β signaling and overcomes the undesirable concomitant decrease in TGF-β–dependent CDK inhibitors p16 and p27 expression by directly upregulating them.

The Central Contributions of Breast Cancer Stem Cells in Developing Resistance to Endocrine Therapy in Estrogen Receptor (ER)-Positive Breast Cancer

Breast cancer stem cells (BCSC) play critical roles in the acquisition of resistance to endocrine therapy in estrogen receptor (ER)-positive (ER + ve) breast cancer (BC). The resistance results from complex alterations involving ER, growth factor receptors, NOTCH, Wnt/β-catenin, hedgehog, YAP/TAZ, and the tumor microenvironment. These mechanisms are likely converged on regulating BCSCs, which then drive the development of endocrine therapy resistance. In this regard, hormone therapies enrich BCSCs in ER + ve BCs under both pre-clinical and clinical settings along with upregulation of the core components of “stemness” transcriptional factors including SOX2, NANOG, and OCT4. SOX2 initiates a set of reactions involving SOX9, Wnt, FXY3D, and Src tyrosine kinase; these reactions stimulate BCSCs and contribute to endocrine resistance. The central contributions of BCSCs to endocrine resistance regulated by complex mechanisms offer a unified strategy to counter the resistance. ER + ve BCs constitute approximately 75% of BCs to which hormone therapy is the major therapeutic approach. Likewise, resistance to endocrine therapy remains the major challenge in the management of patients with ER + ve BC. In this review we will discuss evidence supporting a central role of BCSCs in developing endocrine resistance and outline the strategy of targeting BCSCs to reduce hormone therapy resistance.

Targeting Cancer Cell Metastasis by Converting Cancer Cells into Fat

Cancer is a systemic heterogeneous disease that can undergo several rounds of latency and activation. Malignant tumors evolve through dynamic responses to microenvironmental signals and development of resistance following therapeutic interventions. Cancer cell adaptation is required for cell survival during metastatic dissemination and outgrowth. Epithelial-mesenchymal transition (EMT) plays a major role in facilitating cell plasticity in cancer and allows cancer cells to escape chemotherapies and targeted therapies through dedifferentiation and signaling adaptation processes. In our recent study, we showed that breast cancer cells that have undergone EMT can be terminally differentiated into adipocytes using the PPARγ agonist rosiglitazone combined with the MEK inhibitor trametinib. The conversion of invasive cancer cells into adipocytes repressed primary tumor invasion and metastasis formation in mouse models of breast cancer. The transdifferentiated cancer cell-derived adipocytes were growth-arrested and lost their cellular plasticity. These results indicate the high potential of utilizing the increased cell plasticity inherent to invasive cancer cells for transdifferentiation therapy.

STC2 Is a Potential Prognostic Biomarker for Pancreatic Cancer and Promotes Migration and Invasion by Inducing Epithelial-Mesenchymal Transition

Aberrant expression of stanniocalcin 2 (STC2) is implicated in cancer development. STC2 acts as a tumor promoter to drive some cancers. However, its contribution to the development of pancreatic cancer remains unclear. This study showed that the expression of STC2 was significantly upregulated in pancreatic cancer tissues. Moreover, its expression was positively correlated with tumor size and lymph node metastasis and negatively correlated with 5-year survival rate of pancreatic cancer patients. Additionally, the expression levels of STC2 were a novel biomarker for predicting overall survival rate after surgery. Furthermore, overexpression of STC2 could promote the proliferation, migration, and invasion of pancreatic cancer cell lines, while knocking down of STC2 led to antiproliferation and antimetastasis activities. Further mechanistic investigations revealed that the expression of STC2 could significantly promote the epithelial-mesenchymal transition (EMT) in pancreatic cancer cells. These data indicated that the overexpression of STC2 in pancreatic cancer contributes to the metastasis through the promotion of EMT, suggesting that STC2 is a potential prognostic biomarker and therapeutic target for pancreatic cancer.

Molecular Basis of Tumor Heterogeneity in Endometrial Carcinosarcoma

Endometrial carcinosarcoma (ECS) represents one of the most extreme examples of tumor heterogeneity among human cancers. ECS is a clinically aggressive, high-grade, metaplastic carcinoma. At the morphological level, intratumor heterogeneity in ECS is due to an admixture of epithelial (carcinoma) and mesenchymal (sarcoma) components that can include heterologous tissues, such as skeletal muscle, cartilage, or bone. Most ECSs belong to the copy-number high serous-like molecular subtype of endometrial carcinoma, characterized by the TP53 mutation and the frequently accompanied by a large number of gene copy-number alterations, including the amplification of important oncogenes, such as CCNE1 and c-MYC. However, a proportion of cases (20%) probably represent the progression of tumors initially belonging to the copy-number low endometrioid-like molecular subtype (characterized by mutations in genes such as PTEN, PI3KCA, or ARID1A), after the acquisition of the TP53 mutations. Only a few ECS belong to the microsatellite-unstable hypermutated molecular type and the POLE-mutated, ultramutated molecular type. A common characteristic of all ECSs is the modulation of genes involved in the epithelial to mesenchymal process. Thus, the acquisition of a mesenchymal phenotype is associated with a switch from E- to N-cadherin, the up-regulation of transcriptional repressors of E-cadherin, such as Snail Family Transcriptional Repressor 1 and 2 (SNAI1 and SNAI2), Zinc Finger E-Box Binding Homeobox 1 and 2 (ZEB1 and ZEB2), and the down-regulation, among others, of members of the miR-200 family involved in the maintenance of an epithelial phenotype. Subsequent differentiation to different types of mesenchymal tissues increases tumor heterogeneity and probably modulates clinical behavior and therapy response.

High-Risk Multiple Myeloma: Integrated Clinical and Omics Approach Dissects the Neoplastic Clone and the Tumor Microenvironment

Multiple myeloma (MM) is a genetically heterogeneous disease that includes a subgroup of 10–15% of patients facing dismal survival despite the most intensive treatment. Despite improvements in biological knowledge, MM is still an incurable neoplasia, and therapeutic options able to overcome the relapsing/refractory behavior represent an unmet clinical need. The aim of this review is to provide an integrated clinical and biological overview of high-risk MM, discussing novel therapeutic perspectives, targeting the neoplastic clone and its microenvironment. The dissection of the molecular determinants of the aggressive phenotypes and drug-resistance can foster a better tailored clinical management of the high-risk profile and therapy-refractoriness. Among the current clinical difficulties in MM, patients’ management by manipulating the tumor niche represents a major challenge. The angiogenesis and the stromal infiltrate constitute pivotal mechanisms of a mutual collaboration between MM and the non-tumoral counterpart. Immuno-modulatory and anti-angiogenic therapy hold great efficacy, but variable and unpredictable responses in high-risk MM. The comprehensive understanding of the genetic heterogeneity and MM high-risk ecosystem enforce a systematic bench-to-bedside approach. Here, we provide a broad outlook of novel druggable targets. We also summarize the existing multi-omics-based risk profiling tools, in order to better select candidates for dual immune/vasculogenesis targeting.

The Role of Peroxiredoxin Family in Cancer Signaling

Peroxiredoxins (Prxs) are antioxidant enzymes that protect cells from oxidative stress by reducing intracellular accumulation of reactive oxygen species (ROS). In mammalian cells, the six Prx isoforms are ubiquitously expressed in diverse intracellular locations. They are involved in the regulation of various physiological processes including cell growth, differentiation, apoptosis, immune response and metabolism as well as intracellular ROS homeostasis. Although there are increasing evidences that Prxs are involved in carcinogenesis of many cancers, their role in cancer is controversial. The ROS levels in cancer cells are increased compared to normal cells, thus promoting cancer development. Nevertheless, for various cancer types, an overexpression of Prxs has been found to be associated with poor patient prognosis, and an increasing number of studies have reported that tumorigenesis is either facilitated or inhibited by regulation of cancer-associated signaling pathways. This review summarizes Prx isoforms and their basic functions, the relationship between the expression level and the physiological role of Prxs in cancer cells, and their roles in regulating cancer-associated signaling pathways.