Breast tumor cell-specific knockout of Twist1 inhibits cancer cell plasticity, dissemination, and lung metastasis in mice

Advances in the study of epithelial mesenchymal transition in cancer progression: Role of miRNAs

Epithelial-mesenchymal transition (EMT) has been extensively studied for its roles in tumor metastasis, the generation and maintenance of cancer stem cells and treatment resistance. Epithelial mesenchymal plasticity allows cells to switch between various states within the epithelial-mesenchymal spectrum, resulting in a mixed epithelial/mesenchymal phenotypic profile. This plasticity underlies the acquisition of multiple malignant features during cancer progression and poses challenges for EMT in tumors. MicroRNAs (miRNAs) in the microenvironment affect numerous signaling processes through diverse mechanisms, influencing physiological activities. This paper reviews recent advances in EMT, the role of different hybrid states in tumor progression, and the important role of miRNAs in EMT. Furthermore, it explores the relationship between miRNA-based EMT therapies and their implications for clinical practice, discussing how ongoing developments may enhance therapeutic outcomes.

TWIST1 Regulates FOXM1/β-Catenin to Promote the Growth, Migration, and Invasion of Ovarian Cancer Cells by Activating MFAP2

TWIST1 is aberrantly expressed in ovarian cancer (OC). MFAP2 is a downstream target of TWIST1, and we previously found MFAP2 facilitated OC development by activating FOXM1/β-catenin. We planned to investigate the mechanisms of TWIST1 in OC. GEPIA (a database for gene expression analysis) and UALCAN (a database containing comprehensive cancer transcriptome and clinical patient data) investigated TWIST1's connection to MFAP2 and patient survival in ovarian serous cystadenocarcinoma (OV). Human OC cells (A2780 and CAOV3) were transfected with si-TWIST1, oe-TWIST1, oe-MFAP2, or si-TWIST1 + oe-MFAP2. Cellular apoptosis, viability, migration, and invasion were detected. TWIST1, MFAP2, FOXM1, and β-catenin protein expressions were tested. Dual-luciferase and ChIP-qPCR validated the correlation between MFAP2 and TWIST1. Moreover, OC mice were established by injecting OC cells subcutaneously. The pathology, apoptosis, as well as Ki67, TWIST1, MFAP2, FOXM1, and β-catenin protein levels of tumors were assessed. TWIST1 expression positively correlated with MFAP2 expression, but negatively related to patients' survival in OV. TWIST1 overexpression promoted malignant behaviors, and increased MFAP2, FOXM1, and β-catenin protein levels for OC cells. TWIST1 knockdown exhibited the opposite trend. In vivo, TWIST1 knockdown disrupted tissue structure, induced apoptosis, decreased Ki67, TWIST1, MFAP2, FOXM1, and β-catenin protein levels in tumor. Interestingly, MFAP2 overexpression reversed the effects of TWIST1 knockdown in vitro and in vivo. Additionally, dual-luciferase and ChIP-qPCR confirmed MFAP2 was a downstream target for TWIST1 in OC. TWIST1 regulated FOXM1/β-catenin to promote the growth, migration, and invasion of OC cells by activating MFAP2, indicating that targeting TWIST1 may be effective for treating OC.

Twist-Induced Epithelial-to-Mesenchymal Transition Confers Specific Metabolic and Mitochondrial Alterations

Cells undergo significant epigenetic and phenotypic change during the epithelial-to-mesenchymal transition (EMT), a process observed in development, wound healing, and cancer metastasis. EMT confers several advantageous characteristics, including enhanced migration and invasion, resistance to cell death, and altered metabolism. In disease, these adaptations could be leveraged as therapeutic targets. Here, we analyze Twist-induced EMT in non-transformed HMLE cells as well as a breast cancer cell line with (MDA-MB-231) and without (MCF7) EMT features to compare differences in metabolic pathways and mitochondrial morphology. Analysis of oxidative and glycolytic metabolism reveals a general EMT-associated glycolytic metabolic phenotype accompanied by increased ATP production. Furthermore, a decrease in mitochondrial size was also associated with EMT-positive cells. However, mitochondrial elongation and spatial dynamics were not consistently altered, as HMLE Twist cells exhibit more rounded and dispersed mitochondria compared to control, while MDA-MB-231 cells exhibit more elongated and clustered mitochondria compared to MCF7 cells. These results provide further insight as to the contextual nature of EMT conferred properties.

Mechanisms of microRNA Regulation of the Epithelial-Mesenchymal Transition (EMT) in Lung Cancer

Lung cancer remains the cancer with the highest mortality worldwide, largely due to a limited understanding of the precise molecular mechanisms that drive its progression. microRNAs (miRNAs) have emerged as crucial regulators of lung cancer progression by influencing key cellular processes, notably the epithelial-mesenchymal transition (EMT). EMT is a complex and potentially reversible process where epithelial cells lose their polarity and adhesion, reorganize their cytoskeleton, and transition to a mesenchymal phenotype, enhancing their migratory and invasive capacities. While EMT plays an essential role in normal physiological contexts such as tissue development and wound healing, it is also a critical mechanism underlying the progression and metastasis of lung cancer. This review aims to summarize the latest research findings on the role of endogenous and exosome-derived microRNAs in regulating EMT in lung cancer, focusing on studies conducted over the past five years. It also provides an overview of EMT's essential molecular mechanisms to better understand how miRNAs regulate EMT in lung cancer.

TWIST1 Drives Cytotoxic CD8+ T-Cell Exhaustion through Transcriptional Activation of CD274 (PD-L1) Expression in Breast Cancer Cells

In breast cancer, epithelial-mesenchymal transition (EMT) is positively associated with programmed death ligand 1 (PD-L1) expression and immune escape, and TWIST1 silences ERα expression and induces EMT and cancer metastasis. However, how TWIST1 regulates PD-L1 and immune evasion is unknown. This study analyzed TWIST1 and PD-L1 expression in breast cancers, investigated the mechanism for TWIST1 to regulate PD-L1 transcription, and assessed the effects of TWIST1 and PD-L1 in cancer cells on cytotoxic CD8+ T cells. Interestingly, TWIST1 expression is correlated with high-level PD-L1 expression in ERα-negative breast cancer cells. The overexpression and knockdown of TWIST1 robustly upregulate and downregulate PD-L1 expression, respectively. TWIST1 binds to the PD-L1 promoter and recruits the TIP60 acetyltransferase complex in a BRD8-dependent manner to transcriptionally activate PD-L1 expression, which significantly accelerates the exhaustion and death of the cytotoxic CD8+ T cells. Accordingly, knockdown of TWIST1 or BRD8 or inhibition of PD-L1 significantly enhances the tumor antigen-specific CD8+ T cells to suppress the growth of breast cancer cells. These results demonstrate that TWIST1 directly induces PD-L1 expression in ERα-negative breast cancer cells to promote immune evasion. Targeting TWIST1, BRD8, and/or PD-L1 in ERα-negative breast cancer cells with TWIST1 expression may sensitize CD8+ T-cell-mediated immunotherapy.

Loss of p53 epigenetically modulates epithelial to mesenchymal transition in colorectal cancer

Epithelial to Mesenchymal transition (EMT) drives cancer metastasis and is governed by genetic and epigenetic alterations at multiple levels of regulation. It is well established that loss/mutation of p53 confers oncogenic function to cancer cells and promotes metastasis. Though transcription factors like ZEB1, SLUG, SNAIL and TWIST have been implied in EMT signalling, p53 mediated alterations in the epigenetic machinery accompanying EMT are not clearly understood. This work attempts to explore epigenetic signalling during EMT in colorectal cancer (CRC) cells with varying status of p53. Towards this, we have induced EMT using TGFβ on CRC cell lines with wild type, null and mutant p53 and have assayed epigenetic alterations after EMT induction. Transcriptomic profiling of the four CRC cell lines revealed that the loss of p53 confers more mesenchymal phenotype with EMT induction than its mutant counterparts. This was also accompanied by upregulation of epigenetic writer and eraser machinery suggesting an epigenetic signalling cascade triggered by TGFβ signalling in CRC. Significant agonist and antagonistic relationships observed between EMT factor SNAI1 and SNAI2 with epigenetic enzymes KDM6A/6B and the chromatin organiser SATB1 in p53 null CRC cells suggest a crosstalk between epigenetic and EMT factors. The observed epigenetic regulation of EMT factor SNAI1 correlates with poor clinical outcomes in 270 colorectal cancer patients taken from TCGA-COAD. This unique p53 dependent interplay between epigenetic enzymes and EMT factors in CRC cells may be exploited for development of synergistic therapies for CRC patients presenting to the clinic with loss of p53.

Translational Aspects in Metaplastic Breast Carcinoma

Breast cancer is the most common cancer among women. Metaplastic breast carcinoma (MpBC) is a rare, heterogeneous group of invasive breast carcinomas, which are classified as predominantly triple-negative breast carcinomas (TNBCs; HR-negative/HER2-negative). Histologically, MpBC is classified into six subtypes. Two of these are considered low-grade and the others are high-grade. MpBCs seem to be more aggressive, less responsive to neoadjuvant chemotherapy, and have higher rates of chemoresistance than other TNBCs. MpBCs have a lower survival rate than expected for TNBCs. MpBC treatment represents a challenge, leading to a thorough exploration of the tumor immune microenvironment, which has recently opened the possibility of new therapeutic strategies. The epithelial-mesenchymal transition in MpBC is characterized by the loss of intercellular adhesion, downregulation of epithelial markers, underexpression of genes with biological epithelial functions, upregulation of mesenchymal markers, overexpression of genes with biological mesenchymal functions, acquisition of fibroblast-like (spindle) morphology, cytoskeleton reorganization, increased motility, invasiveness, and metastatic capabilities. This article reviews and summarizes the current knowledge and translational aspects of MpBC.

Cancer cell plasticity, stem cell factors, and therapy resistance: how are they linked?

Cellular plasticity can occur naturally in an organism and is considered an adapting mechanism during the developmental stage. However, abnormal cellular plasticity is observed in different diseased conditions, including cancer. Cancer cell plasticity triggers the stimuli of epithelial-mesenchymal transition (EMT), abnormal epigenetic changes, expression of stem cell factors and implicated signaling pathways, etc., and helps in the maintenance of CSC phenotype. Conversely, CSC maintains the cancer cell plasticity, EMT, and epigenetic plasticity. EMT contributes to increased cell migration and greater diversity within tumors, while epigenetic changes, stem cell factors (OCT4, NANOG, and SOX2), and various signaling pathways allow cancer cells to maintain various phenotypes, giving rise to intra- and inter-tumoral heterogeneity. The intricate relationships between cancer cell plasticity and stem cell factors help the tumor cells adopt drug-tolerant states, evade senescence, and successfully acquire drug resistance with treatment dismissal. Inhibiting molecules/signaling pathways involved in promoting CSCs, cellular plasticity, EMT, and epigenetic plasticity might be helpful for successful cancer therapy management. This review discussed the role of cellular plasticity, EMT, and stem cell factors in tumor initiation, progression, reprogramming, and therapy resistance. Finally, we discussed how the intervention in this axis will help better manage cancers and improve patient survivability.

Glucocorticoid receptor: a harmonizer of cellular plasticity in breast cancer-directs the road towards therapy resistance, metastatic progression and recurrence

Recent therapeutic advances have significantly uplifted the quality of life in breast cancer patients, yet several impediments block the road to disease-free survival. This involves unresponsiveness towards administered therapy, epithelial to mesenchymal transition, and metastatic progression with the eventual appearance of recurrent disease. Attainment of such characteristics is a huge adaptive challenge to which tumour cells respond by acquiring diverse phenotypically plastic states. Several signalling networks and mediators are involved in such a process. Glucocorticoid receptor being a mediator of stress response imparts prognostic significance in the context of breast carcinoma. Involvement of the glucocorticoid receptor in the signalling cascade of breast cancer phenotypic plasticity needs further elucidation. This review attempted to shed light on the inter-regulatory interactions of the glucocorticoid receptor with the mediators of the plasticity program in breast cancer; which may provide a hint for strategizing therapeutics against the glucocorticoid/glucocorticoid receptor axis so as to modulate phenotypic plasticity in breast carcinoma.

The TGFβ2-Snail1-miRNATGFβ2 Circuitry is Critical for the Development of Aggressive Functions in Breast Cancer

There have been contradictory reports on the biological role of transforming growth factor-βs (TGFβs) in breast cancer (BC), especially with regard to their ability to promote epithelial-mesenchymal transition (EMT). Here, we show that TGFβ2 is preferentially expressed in mesenchymal-like BCs and maintains the EMT phenotype, correlating with cancer stem cell-like characteristics, growth, metastasis and chemo-resistance and predicting worse clinical outcomes. However, this is only true in ERα- BC. In ERα+ luminal-type BC, estrogen receptor interacts with p-Smads to block TGFβ signalling. Furthermore, we also identify a microRNAs (miRNAs) signature (miRNAsTGFβ2 ) that is weakened in TGFβ2-overexpressing BC cells. We discover that TGFβ2-Snail1 recruits enhancer of zeste homolog-2 to convert miRNAsTGFβ2 promoters from an active to repressive chromatin configuration and then repress miRNAsTGFβ2 transcription, forming a negative feedback loop. On the other hand, miRNAsTGFβ2 overexpression reverses the mesenchymal-like traits in agreement with the inhibition of TGFβ2-Snail1 signalling in BC cells. These findings clarify the roles of TGFβ2 in BC and suggest novel therapeutic strategies based on the TGFβ2-Snail1-miRNAsTGFβ2 loop for a subset type of human BCs.

Update on Epithelial-Mesenchymal Plasticity in Cancer Progression

Epithelial-mesenchymal transition (EMT) is a cellular process by which epithelial cells lose their characteristics and acquire mesenchymal traits to promote cell movement. This program is aberrantly activated in human cancers and endows tumor cells with increased abilities in tumor initiation, cell migration, invasion, metastasis, and therapy resistance. The EMT program in tumors is rarely binary and often leads to a series of gradual or intermediate epithelial-mesenchymal states. Functionally, epithelial-mesenchymal plasticity (EMP) improves the fitness of cancer cells during tumor progression and in response to therapies. Here, we discuss the most recent advances in our understanding of the diverse roles of EMP in tumor initiation, progression, metastasis, and therapy resistance and address major clinical challenges due to EMP-driven phenotypic heterogeneity in cancer. Uncovering novel molecular markers and key regulators of EMP in cancer will aid the development of new therapeutic strategies to prevent cancer recurrence and overcome therapy resistance.

miR-29c-3p acts as a tumor promoter by regulating β-catenin signaling through suppressing DNMT3A, TET1 and HBP1 in ovarian carcinoma

Ovarian Carcinoma (OvCa) is characterized by rapid and sustained growth, activated invasion and metastasis. Studies have shown that microRNAs recruit and alter the expression of key regulators to modulate carcinogenesis. Here, we find that miR-29c-3p is increased in benign OvCa and malignant OvCa compared to normal ovary. Univariate and multivariate analyses report that miR-29c-3p overexpression is associated with poor prognosis in OvCa. Furthermore, we investigate that expression of miR-29c-3p is inversely correlated to DNA methyltransferase (DNMT) 3 A and Ten-Eleven-Translocation enzyme TET1. The high-throughput mRNA sequencing, bioinformatics analysis and pharmacological studies confirm that aberrant miR-29c-3p modulates tumorigenesis in OvCa cells, including epithelial-mesenchymal transition (EMT), proliferation, migration, and invasion. This modulation occurs through the regulation of β-catenin signaling by directly targeting 3'UTR of DNMT3A, TET1 and the HMG box transcription factor HBP1 and suppressing their expression. The further 3D spheres assay clearly shows the regulatory effects of miR-29c-3p on OvCa tumorigenesis. Additionally, the receiver operating characteristic (ROC) curve analysis of miR-29c-3p and the clinical detection/diagnostic biomarker CA125 suggests that miR-29c-3p may be conducive for clinical diagnosis or co-diagnosis of OvCa. These findings support miR-29c-3p functions as a tumor promoter by targeting its functional targets, providing new potential biomarker (s) for precision medicine strategies in OvCa.

Stabilizing vimentin phosphorylation inhibits stem-like cell properties and metastasis of hybrid epithelial/mesenchymal carcinomas

Epithelial-mesenchymal transition (EMT) empowers epithelial cells with mesenchymal and stem-like attributes, facilitating metastasis, a leading cause of cancer-related mortality. Hybrid epithelial-mesenchymal (E/M) cells, retaining both epithelial and mesenchymal traits, exhibit heightened metastatic potential and stemness. The mesenchymal intermediate filament, vimentin, is upregulated during EMT, enhancing the resilience and invasiveness of carcinoma cells. The phosphorylation of vimentin is critical to its structure and function. Here, we identify that stabilizing vimentin phosphorylation at serine 56 induces multinucleation, specifically in hybrid E/M cells with stemness properties but not epithelial or mesenchymal cells. Cancer stem-like cells are especially susceptible to vimentin-induced multinucleation relative to differentiated cells, leading to a reduction in self-renewal and stemness. As a result, vimentin-induced multinucleation leads to sustained inhibition of stemness properties, tumor initiation, and metastasis. These observations indicate that a single, targetable phosphorylation event in vimentin is critical for stemness and metastasis in carcinomas with hybrid E/M properties.

Molecular mechanisms of TWIST1-regulated transcription in EMT and cancer metastasis

TWIST1 induces epithelial-to-mesenchymal transition (EMT) to drive cancer metastasis. It is yet unclear what determines TWIST1 functions to activate or repress transcription. We found that the TWIST1 N-terminus antagonizes TWIST1-regulated gene expression, cancer growth and metastasis. TWIST1 interacts with both the NuRD complex and the NuA4/TIP60 complex (TIP60-Com) via its N-terminus. Non-acetylated TWIST1-K73/76 selectively interacts with and recruits NuRD to repress epithelial target gene transcription. Diacetylated TWIST1-acK73/76 binds BRD8, a component of TIP60-Com that also binds histone H4-acK5/8, to recruit TIP60-Com to activate mesenchymal target genes and MYC. Knockdown of BRD8 abolishes TWIST1 and TIP60-Com interaction and TIP60-Com recruitment to TWIST1-activated genes, resulting in decreasing TWIST1-activated target gene expression and cancer metastasis. Both TWIST1/NuRD and TWIST1/TIP60-Com complexes are required for TWIST1 to promote EMT, proliferation, and metastasis at full capacity. Therefore, the diacetylation status of TWIST1-K73/76 dictates whether TWIST1 interacts either with NuRD to repress epithelial genes, or with TIP60-Com to activate mesenchymal genes and MYC. Since BRD8 is essential for TWIST1-acK73/76 and TIP60-Com interaction, targeting BRD8 could be a means to inhibit TWIST1-activated gene expression.

Ciliated, Mitochondria-Rich Postmitotic Cells are Immune-privileged, and Mimic Immunosuppressive Microenvironment of Tumor-Initiating Stem Cells: From Molecular Anatomy to Molecular Pathway

Cancer whose major problems are metastasis, treatment resistance, and recurrence is the leading cause of death worldwide. Tumor-initiating stem cells (TiSCs) are a subset of the tumor population responsible for tumor resistance and relapse. Understanding the characteristics and shared features between tumor-initiating stem cells (TiSCs) and long-lived postmitotic cells may hold a key to better understanding the biology of cancer. Postmitotic cells have exited the cell cycle and are transitioned into a non-dividing and terminally differentiated state with a specialized function within a tissue. Conversely, a cancer cell with TiSC feature can divide and produce a variety of progenies, and is responsible for disease progression, tumor resistance to therapy and immune system and disease relapse. Surprisingly, our comprehensive evaluation of TiSCs suggests common features with long-lived post-mitotic cells. They are similar in structure (primary cilia, high mitochondrial content, and being protected by a barrier), metabolism (autophagy and senescence), and function (immunoescape and/or immune-privileged by a blood barrier). In-depth exploration showed how mitochondrial metabolism contributes to these shared features, including high energy demands arising from ciliary and microtubular functionality, increased metabolic activity, and movement. These findings can assist in decoding the remaining properties which offer insights into the biology of TiSCs, with potential implications for enhancing cancer treatment strategies and patient prognosis.

ING1 inhibits Twist1 expression to block EMT and is antagonized by the HDAC inhibitor vorinostat

ING1 is a chromatin targeting subunit of the Sin3a histone deacetylase (HDAC) complex that alters chromatin structure to subsequently regulate gene expression. We find that ING1 knockdown increases expression of Twist1, Zeb 1&2, Snai1, Bmi1 and TSHZ1 drivers of EMT, promoting EMT and cell motility. ING1 expression had the opposite effect, promoting epithelial cell morphology and inhibiting basal and TGF-β-induced motility in 3D organoid cultures. ING1 binds the Twist1 promoter and Twist1 was largely responsible for the ability of ING1 to reduce cell migration. Consistent with ING1 inhibiting Twist1 expression in vivo, an inverse relationship between ING1 and Twist1 levels was seen in breast cancer samples from The Cancer Genome Atlas (TCGA). The HDAC inhibitor vorinostat is approved for treatment of multiple myeloma and cutaneous T cell lymphoma and is in clinical trials for solid tumours as adjuvant therapy. One molecular target of vorinostat is INhibitor of Growth 2 (ING2), that together with ING1 serve as targeting subunits of the Sin3a HDAC complex. Treatment with sublethal (LD25-LD50) levels of vorinostat promoted breast cancer cell migration several-fold, which increased further upon ING1 knockout. These observations indicate that correct targeting of the Sin3a HDAC complex, and HDAC activity in general decreases luminal and basal breast cancer cell motility, suggesting that use of HDAC inhibitors as adjuvant therapies in breast cancers that are prone to metastasize may not be optimal and requires further investigation.

Resistance to mesenchymal reprogramming sustains clonal propagation in metastatic breast cancer

The acquisition of mesenchymal traits is considered a hallmark of breast cancer progression. However, the functional relevance of epithelial-to-mesenchymal transition (EMT) remains controversial and context dependent. Here, we isolate epithelial and mesenchymal populations from human breast cancer metastatic biopsies and assess their functional potential in vivo. Strikingly, progressively decreasing epithelial cell adhesion molecule (EPCAM) levels correlate with declining disease propagation. Mechanistically, we find that persistent EPCAM expression marks epithelial clones that resist EMT induction and propagate competitively. In contrast, loss of EPCAM defines clones arrested in a mesenchymal state, with concomitant suppression of tumorigenicity and metastatic potential. This dichotomy results from distinct clonal trajectories impacting global epigenetic programs that are determined by the interplay between human ZEB1 and its target GRHL2. Collectively, our results indicate that susceptibility to irreversible EMT restrains clonal propagation, whereas resistance to mesenchymal reprogramming sustains disease spread in multiple models of human metastatic breast cancer, including patient-derived cells in vivo.

Understanding and targeting resistance mechanisms in cancer

Resistance to cancer therapies has been a commonly observed phenomenon in clinical practice, which is one of the major causes of treatment failure and poor patient survival. The reduced responsiveness of cancer cells is a multifaceted phenomenon that can arise from genetic, epigenetic, and microenvironmental factors. Various mechanisms have been discovered and extensively studied, including drug inactivation, reduced intracellular drug accumulation by reduced uptake or increased efflux, drug target alteration, activation of compensatory pathways for cell survival, regulation of DNA repair and cell death, tumor plasticity, and the regulation from tumor microenvironments (TMEs). To overcome cancer resistance, a variety of strategies have been proposed, which are designed to enhance the effectiveness of cancer treatment or reduce drug resistance. These include identifying biomarkers that can predict drug response and resistance, identifying new targets, developing new targeted drugs, combination therapies targeting multiple signaling pathways, and modulating the TME. The present article focuses on the different mechanisms of drug resistance in cancer and the corresponding tackling approaches with recent updates. Perspectives on polytherapy targeting multiple resistance mechanisms, novel nanoparticle delivery systems, and advanced drug design tools for overcoming resistance are also reviewed.

m6 A-Dependent Modulation via IGF2BP3/MCM5/Notch Axis Promotes Partial EMT and LUAD Metastasis

The importance of mRNA N6-methyladenosine (m⁶ A) modification during tumor metastasis is controversial as it plays distinct roles in different biological contexts. Moreover, how cancer cell plasticity is shaped by m⁶ A modification is interesting but remains uncharacterized. Here, this work shows that m⁶ A reader insulin like growth factor 2 mRNA binding protein 3 (IGF2BP3) is remarkably upregulated in metastatic lung adenocarcinoma (LUAD) and indicates worse prognosis of patients. Interestingly, IGF2BP3 induces partial epithelial-mesenchymal-transition (EMT) and confers LUAD cells plasticity to metastasize through m⁶ A-dependent overactivation of Notch signaling. Mechanistically, IGF2BP3 recognized m⁶ A-modified minichromosome maintenance complex component (MCM5) mRNAs to prolong stability of them, subsequently upregulating MCM5 protein, which competitively inhibits SIRT1-mediated deacetylation of Notch1 intracellular domain (NICD1), stabilizes NICD1 protein and contributes to m⁶ A-dependent IGF2BP3-mediated cellular plasticity. Notably, a tight correlation of the IGF2BP3/MCM5/Notch axis is evidenced in clinical LUAD specimens. Therefore, this study elucidates a critical role of m⁶ A modification on LUAD cell plasticity in fostering tumor metastasis via the above axis, providing potential targets for metastatic LUAD.

Molecular profiles of single circulating tumor cells from early breast cancer patients with different lymph node statuses

BACKGROUND

Characterization of early breast cancer circulating tumor cells (CTCs) may provide valuable information on tumor metastasis.

METHODS

We used immunomagnetic nanospheres to capture CTCs from the peripheral blood of eight early breast cancer patients and then performed single-cell RNA sequencing using our proposed bead-dd-seq method.

RESULTS

CTCs displayed obvious tumor cell characteristics, such as the activation of oxidative stress, proliferation, and promotion of metastasis. CTCs were clustered into two subtypes significantly correlated with the lymph node metastasis status of patients. CTCs in subtype 1 showed a strong metastatic ability because these CTCs have the phenotype of partial epithelial-mesenchymal transition and enriched transcripts, indicating breast cancer responsiveness and proliferation. Furthermore, DNA damage repair pathways were significantly upregulated in subtype 1. We performed in vitro and in vivo investigations, and found that cellular oxidative stress and further DNA damage existed in CTCs. The activated DNA damage repair pathway in CTCs favors resistance to cisplatin. A checkpoint kinase 1 inhibitor sensitized CTCs to cisplatin in mouse models of breast cancer metastasis.

CONCLUSION

The present study dissects the molecular characteristics of CTCs from early-stage breast cancer, providing novel insight into the understanding of CTC behavior in breast cancer metastasis.

The role of Actopaxin in tumor metastasis

Actopaxin is a newly discovered focal adhesions (FAs) protein, actin-binding protein and pseudopodia-enriched molecule. It can not only bind to a variety of FAs proteins (such as Paxillin, ILK and PINCH) and non-FAs proteins (such as TESK1, CdGAP, β2-adaptin, G3BP2, ADAR1 and CD29), but also participates in multiple signaling pathways. Thus, it plays a crucial role in regulating important processes of tumor metastasis, including matrix degradation, migration, and invasion, etc. This review covers the latest progress in the structure and function of Actopaxin, its interaction with other proteins as well as its involvement in regulating tumor development and metastasis. Additionally, the current limitations for Actopaxin related studies and the possible research directions on it in the future are also discussed. It is hoped that this review can assist relevant researchers to obtain a deep understanding of the role that Actopaxin plays in tumor progression, and also enlighten further research and development of therapeutic approaches for the treatment of tumor metastasis.

FOXD1-dependent RalA-ANXA2-Src complex promotes CTC formation in breast cancer

BACKGROUND

Early metastasis is a key factor contributing to poor breast cancer (BC) prognosis. Circulating tumor cells (CTCs) are regarded as the precursor cells of metastasis, which are ultimately responsible for the main cause of death in BC. However, to date molecular mechanisms underlying CTC formation in BC have been insufficiently defined.

METHODS

RNA-seq was carried out in primary tissues from early-stage BC patients (with CTCs≥5 and CTCs = 0, respectively) and the validation study was conducted in untreated 80 BC patients. Multiple in vitro and in vivo models were used in functional studies. Luciferase reporter, ChIP-seq, CUT&Tag-seq, and GST-pulldown, etc. were utilized in mechanistic studies. CTCs were counted by the CanPatrol™ CTC classification system or LiquidBiospy™ microfluidic chips. ERK1/2 inhibitor SCH772984 was applied to in vivo treatment.

RESULTS

Highly expressed FOXD1 of primary BC tissues was observed to be significantly associated with increased CTCs in BC patients, particularly in early BC patients. Overexpressing FOXD1 enhanced the migration capability of BC cells, CTC formation and BC metastasis, via facilitating epithelial-mesenchymal transition of tumor cells. Mechanistically, FOXD1 was discovered to induce RalA expression by directly bound to RalA promotor. Then, RalA formed a complex with ANXA2 and Src, promoting the interaction between ANXA2 and Src, thus increasing the phosphorylation (Tyr23) of ANXA2. Inhibiting RalA-GTP form attenuated the interaction between ANXA2 and Src. This cascade culminated in the activation of ERK1/2 signal that enhanced metastatic ability of BC cells. In addition, in vivo treatment with SCH772984, a specific inhibitor of ERK1/2, was used to dramatically inhibit the CTC formation and BC metastasis.

CONCLUSION

Here, we report a FOXD1-dependent RalA-ANXA2-Src complex that promotes CTC formation via activating ERK1/2 signal in BC. FOXD1 may serve as a prognostic factor in evaluation of BC metastasis risks. This signaling cascade is druggable and effective for overcoming CTC formation from the early stages of BC.

The molecular mechanisms and therapeutic strategies of EMT in tumor progression and metastasis

Epithelial–mesenchymal transition (EMT) is an essential process in normal embryonic development and tissue regeneration. However, aberrant reactivation of EMT is associated with malignant properties of tumor cells during cancer progression and metastasis, including promoted migration and invasiveness, increased tumor stemness, and enhanced resistance to chemotherapy and immunotherapy. EMT is tightly regulated by a complex network which is orchestrated with several intrinsic and extrinsic factors, including multiple transcription factors, post-translational control, epigenetic modifications, and noncoding RNA-mediated regulation. In this review, we described the molecular mechanisms, signaling pathways, and the stages of tumorigenesis involved in the EMT process and discussed the dynamic non-binary process of EMT and its role in tumor metastasis. Finally, we summarized the challenges of chemotherapy and immunotherapy in EMT and proposed strategies for tumor therapy targeting EMT.

Suppression of the malignancy of mammary tumor in mice model by inactivated preparation of Mycobacterium obuense

Breast cancer (BC) is a significant cause of global mortality in women. This study was aimed to evaluate the immune-activation of malignant BC via the administration of attenuated Mycobacterium obuense. For this purpose, an in vivo model was developed with BALB/c mice. Mice were injected with 2.00 × 10⁶ 4T1 cells with breast tumor cell line. Forty-two mice were equally divided into control as well as low dose (0.20 mg 100 µL^-1) and high dose (0.50 mg 100 µL^-1) groups of M. obuense to investigate gene expression in the antitumor effects of M. obuense. In one group, paclitaxel was administrated as a choice drug in BC treatment. Antitumor manners were characterized by cytotoxicity against tumor target cells, size of the tumor and the expression of some BC metastatic genes together with pathology. The MTT assay demonstrated that different concentrations of both low and a high dose of bacteria did present no cytotoxicity effect on 4T1 cells. According to our findings, M. obuense significantly repressed tumor growth. M. obuense downregulated the expression of collagen type I alpha 1 (COLIA1), cFos, alkaline phosphatase (ALP), claudin 3 (cldn3), and conversely, activated transcription factor 4 (ATF4) and Twist related protein-1 (Twist1). All these alternations induced a decrease in the migratory and invasive capabilities of BC. The result of pathology was indicative of tumor regression in the paclitaxel and HK- M. obuense -recipient group. Thus, it seems most likely that M. obuense might impinge upon cell growth and metastatic behavior of malignant cells exerting anti-tumor activity in BC.

Repurposing maduramicin as a novel anticancer and anti-metastasis agent for triple-negative breast cancer as enhanced by nanoemulsion

Triple-negative breast cancer (TNBC) is featured by aggression and metastasis and remains an unmet medical challenge due to high death rate. We aimed to repurpose maduramicin (MAD) as an effective drug against TNBC, and develop a nanoemulsion system to enhance anticancer efficacy of MAD. MDA-MB-231 and 4 T1 cells were used as in vitro model, and cell viability was determined by performing cell counting kit-8 and a colony-formation assay. Furthermore, MAD loaded nanoemulsion (MAD-NEs) was manufactured and characterized by a series of tests. The anticancer and anti-metastasis mechanism of MAD-NEs were assessed by performing cell cycle, apoptosis, wound-healing, transwell assay and Western blotting assays. Herein, MAD was firstly demonstrated to be an effective agent to suppress growth of TNBC cells. Subsequently, the optimized MAD-NEs were shown to have stability and high encapsulation efficiency, and could arrested cells in G0/G1 phase and induced apoptosis in TNBC cells. More importantly, MAD-NEs significantly impeded the metastasis of tumor cells, which was further demonstrated by the significant altered expression of epithelial-mesenchymal transition and extracellular matrix markers in vitro and in vivo. Moreover, compared to MAD, MAD-NEs exhibited higher efficacy in shrinking breast tumor size and repressing liver and lung metastasis in vivo, and showed excellent biocompatibility in tumor-bearing mice. The successfully prepared MAD-NEs are expected to be harnessed to suppress tumor growth, invasion and metastasis in the battle against malignant TNBC.

TWIST1 interacts with β/δ-catenins during neural tube development and regulates fate transition in cranial neural crest cells

Cell fate determination is a necessary and tightly regulated process for producing different cell types and structures during development. Cranial neural crest cells (CNCCs) are unique to vertebrate embryos and emerge from the neural plate borders into multiple cell lineages that differentiate into bone, cartilage, neurons and glial cells. We have previously reported that Irf6 genetically interacts with Twist1 during CNCC-derived tissue formation. Here, we have investigated the mechanistic role of Twist1 and Irf6 at early stages of craniofacial development. Our data indicate that TWIST1 is expressed in endocytic vesicles at the apical surface and interacts with β/δ-catenins during neural tube closure, and Irf6 is involved in defining neural fold borders by restricting AP2α expression. Twist1 suppresses Irf6 and other epithelial genes in CNCCs during the epithelial-to-mesenchymal transition (EMT) process and cell migration. Conversely, a loss of Twist1 leads to a sustained expression of epithelial and cell adhesion markers in migratory CNCCs. Disruption of TWIST1 phosphorylation in vivo leads to epidermal blebbing, edema, neural tube defects and CNCC-derived structural abnormalities. Altogether, this study describes a previously uncharacterized function of mammalian Twist1 and Irf6 in the neural tube and CNCCs, and provides new target genes for Twist1 that are involved in cytoskeletal remodeling.

Epithelial-Mesenchymal Transition Suppresses AMPK and Sensitizes Cancer Cells to Pyroptosis under Energy Stress

Epithelial-mesenchymal transition (EMT) is implicated in tumor metastasis and therapeutic resistance. It remains a challenge to target cancer cells that have undergone EMT. The Snail family of key EMT-inducing transcription factors directly binds to and transcriptionally represses not only epithelial genes but also a myriad of additional genomic targets that may carry out significant biological functions. Therefore, we reasoned that EMT inherently causes various concomitant phenotypes, some of which may create targetable vulnerabilities for cancer treatment. In the present study, we found that Snail transcription factors bind to the promoters of multiple genes encoding subunits of the AMP-activated protein kinase (AMPK) complex, and expression of AMPK genes was markedly downregulated by EMT. Accordingly, high AMPK expression in tumors correlated with epithelial cell markers and low AMPK expression in tumors was strongly associated with adverse prognosis. AMPK is the principal sensor of cellular energy status. In response to energy stress, AMPK is activated and critically reprograms cellular metabolism to restore energy homeostasis and maintain cell survival. We showed that activation of AMPK by energy stress was severely impaired by EMT. Consequently, EMT cancer cells became hypersensitive to a variety of energy stress conditions and primarily underwent pyroptosis, a regulated form of necrotic cell death. Collectively, the study suggests that EMT impedes the activation of AMPK signaling induced by energy stress and sensitizes cancer cells to pyroptotic cell death under energy stress conditions. Therefore, while EMT promotes malignant progression, it concurrently induces collateral vulnerabilities that may be therapeutically exploited.

Essential role of aerobic glycolysis in epithelial-to-mesenchymal transition during carcinogenesis

Epithelial-to-mesenchymal transition (EMT) confers the most lethal characteristics to cancer cells i.e., metastasis and resistance to chemo-and-radio-therapy, and therefore exhibit an appealing target in the field of oncology. Research in the past decade has demonstrated the crucial role of aerobic glycolysis in EMT, which is generally credited as the glucose metabolism for the creation of biomass such as fatty acids, amino acids, and nucleotides thereby providing building blocks for limitless proliferation. In the present review, apart from discussing EMT's evident role in the metastatic process and cancer stemness, we also talked about the vital role of glycolytic enzymes viz. GLUTs, HKs, PGI, PFK-1, aldolase, enolase, PK, LDHA, etc. in the induction of the EMT process in cancerous cells.

Dedifferentiation-mediated stem cell niche maintenance in early-stage ductal carcinoma in situ progression: insights from a multiscale modeling study

We present a multiscale agent-based model of ductal carcinoma in situ (DCIS) to study how key phenotypic and signaling pathways are involved in the early stages of disease progression. The model includes a phenotypic hierarchy, and key endocrine and paracrine signaling pathways, and simulates cancer ductal growth in a 3D lattice-free domain. In particular, by considering stochastic cell dedifferentiation plasticity, the model allows for study of how dedifferentiation to a more stem-like phenotype plays key roles in the maintenance of cancer stem cell populations and disease progression. Through extensive parameter perturbation studies, we have quantified and ranked how DCIS is sensitive to perturbations in several key mechanisms that are instrumental to early disease development. Our studies reveal that long-term maintenance of multipotent stem-like cell niches within the tumor are dependent on cell dedifferentiation plasticity, and that disease progression will become arrested due to dilution of the multipotent stem-like population in the absence of dedifferentiation. We have identified dedifferentiation rates necessary to maintain biologically relevant multipotent cell populations, and also explored quantitative relationships between dedifferentiation rates and disease progression rates, which may potentially help to optimize the efficacy of emerging anti-cancer stem cell therapeutics.

Epithelial–mesenchymal transition: The history, regulatory mechanism, and cancer therapeutic opportunities

Epithelial–mesenchymal transition (EMT) is a program wherein epithelial cells lose their junctions and polarity while acquiring mesenchymal properties and invasive ability. Originally defined as an embryogenesis event, EMT has been recognized as a crucial process in tumor progression. During EMT, cell–cell junctions and cell–matrix attachments are disrupted, and the cytoskeleton is remodeled to enhance mobility of cells. This transition of phenotype is largely driven by a group of key transcription factors, typically Snail, Twist, and ZEB, through epigenetic repression of epithelial markers, transcriptional activation of matrix metalloproteinases, and reorganization of cytoskeleton. Mechanistically, EMT is orchestrated by multiple pathways, especially those involved in embryogenesis such as TGFβ, Wnt, Hedgehog, and Hippo, suggesting EMT as an intrinsic link between embryonic development and cancer progression. In addition, redox signaling has also emerged as critical EMT modulator. EMT confers cancer cells with increased metastatic potential and drug resistant capacity, which accounts for tumor recurrence in most clinic cases. Thus, targeting EMT can be a therapeutic option providing a chance of cure for cancer patients. Here, we introduce a brief history of EMT and summarize recent advances in understanding EMT mechanisms, as well as highlighting the therapeutic opportunities by targeting EMT in cancer treatment.

Identification of dynamic driver sets controlling phenotypical landscapes

Controlling phenotypical landscapes is of vital interest to modern biology. This task becomes highly demanding because cellular decisions involve complex networks engaging in crosstalk interactions. Previous work on control theory indicates that small sets of compounds can control single phenotypes. However, a dynamic approach is missing to determine the drivers of the whole network dynamics. By analyzing 35 biologically motivated Boolean networks, we developed a method to identify small sets of compounds sufficient to decide on the entire phenotypical landscape. These compounds do not strictly prefer highly related compounds and show a smaller impact on the stability of the attractor landscape. The dynamic driver sets include many intervention targets and cellular reprogramming drivers in human networks. Finally, by using a new comprehensive model of colorectal cancer, we provide a complete workflow on how to implement our approach to shift from in silico to in vitro guided experiments.

Mechanical transmission enables EMT cancer cells to drive epithelial cancer cell migration to guide tumor spheroid disaggregation

Cell phenotype heterogeneity within tumor tissue, especially which due to the emergence of epithelial-mesenchymal transition (EMT) in cancer cells, is associated with cancer invasion and metastasis. However, our understanding of the cellular mechanism(s) underlying the cooperation between EMT cell and epithelial cancer cell migration remains incomplete. Herein, heterotypic tumor spheroids containing both epithelial and EMT cancer cells were generated in vitro. We observed that EMT cells dominated the peripheral region of the self-organized heterotypic tumor spheroid. Furthermore, our results demonstrated that EMT cells could serve as leader cells to improve the collective migration efficiency of epithelial cancer cells and promote dispersion and invasion of the tumor spheroids, which was regulated by the force transition between EMT cells and epithelial cancer cells. Mechanistically, our data further suggest that force transmission is mediated by heterophilic N-cadherin/E-cadherin adhesion complexes between EMT and epithelial cancer cells. Impairment of N-cadherin/E-cadherin adhesion complex formation abrogated the ability of EMT cells to guide epithelial cancer cell migration and blocked the dispersion of tumor spheroids. Together, our data provide new insight into the mechanical interaction between epithelial and EMT cancer cells through heterophilic cadherin adhesion, which enables cooperative tumor cell migration, highlighting the role of EMT cells in tumor invasion.

Heterogeneity and dynamic of EMT through the plasticity of ribosome and mRNA translation

Growing evidence exposes translation and its translational machinery as key players in establishing and maintaining physiological and pathological biological processes. Examining translation may not only provide new biological insight but also identify novel innovative therapeutic targets in several fields of biology, including that of epithelial-to-mesenchymal transition (EMT). EMT is currently considered as a dynamic and reversible transdifferentiation process sustaining the transition from an epithelial to mesenchymal phenotype, known to be mainly driven by transcriptional reprogramming. However, it seems that the characterization of EMT plasticity is challenging, relying exclusively on transcriptomic and epigenetic approaches. Indeed, heterogeneity in EMT programs was reported to depend on the biological context. Here, by reviewing the involvement of translational control, translational machinery and ribosome biogenesis characterizing the different types of EMT, from embryonic and adult physiological to pathological contexts, we discuss the added value of integrating translational control and its machinery to depict the heterogeneity and dynamics of EMT programs.

Transcriptional and post-transcriptional control of epithelial-mesenchymal plasticity: why so many regulators?

The dynamic transition between epithelial-like and mesenchymal-like cell states has been a focus for extensive investigation for decades, reflective of the importance of Epithelial-Mesenchymal Transition (EMT) through development, in the adult, and the contributing role EMT has to pathologies including metastasis and fibrosis. Not surprisingly, regulation of the complex genetic networks that underlie EMT have been attributed to multiple transcription factors and microRNAs. What is surprising, however, are the sheer number of different regulators (hundreds of transcription factors and microRNAs) for which critical roles have been described. This review seeks not to collate these studies, but to provide a perspective on the fundamental question of whether it is really feasible that so many regulators play important roles and if so, what does this tell us about EMT and more generally, the genetic machinery that controls complex biological processes.

Circulating Tumor Cells in Breast Cancer Patients: A Balancing Act between Stemness, EMT Features and DNA Damage Responses

Circulating tumor cells (CTCs) traverse vessels to travel from the primary tumor to distant organs where they adhere, transmigrate, and seed metastases. To cope with these challenges, CTCs have reached maximal flexibility to change their differentiation status, morphology, migratory capacity, and their responses to genotoxic stress caused by metabolic changes, hormones, the inflammatory environment, or cytostatic treatment. A significant percentage of breast cancer cells are defective in homologous recombination repair and other mechanisms that protect the integrity of the replication fork. To prevent cell death caused by broken forks, alternative, mutagenic repair, and bypass pathways are engaged but these increase genomic instability. CTCs, arising from such breast tumors, are endowed with an even larger toolbox of escape mechanisms that can be switched on and off at different stages during their journey according to the stress stimulus. Accumulating evidence suggests that DNA damage responses, DNA repair, and replication are integral parts of a regulatory network orchestrating the plasticity of stemness features and transitions between epithelial and mesenchymal states in CTCs. This review summarizes the published information on these regulatory circuits of relevance for the design of biomarkers reflecting CTC functions in real-time to monitor therapeutic responses and detect evolving chemoresistance mechanisms.

TWIST1 expression is associated with high-risk neuroblastoma and promotes primary and metastatic tumor growth

The embryonic transcription factors TWIST1/2 are frequently overexpressed in cancer, acting as multifunctional oncogenes. Here we investigate their role in neuroblastoma (NB), a heterogeneous childhood malignancy ranging from spontaneous regression to dismal outcomes despite multimodal therapy. We first reveal the association of TWIST1 expression with poor survival and metastasis in primary NB, while TWIST2 correlates with good prognosis. Secondly, suppression of TWIST1 by CRISPR/Cas9 results in a reduction of tumor growth and metastasis colonization in immunocompromised mice. Moreover, TWIST1 knockout tumors display a less aggressive cellular morphology and a reduced disruption of the extracellular matrix (ECM) reticulin network. Additionally, we identify a TWIST1-mediated transcriptional program associated with dismal outcome in NB and involved in the control of pathways mainly linked to the signaling, migration, adhesion, the organization of the ECM, and the tumor cells versus tumor stroma crosstalk. Taken together, our findings confirm TWIST1 as promising therapeutic target in NB.

Effect of Lipopolysaccharides on Liver Tumor Metastasis of twist1a/krasV12 Double Transgenic Zebrafish

The poor prognosis of patients diagnosed with hepatocellular carcinoma (HCC) is directly associated with the multi-step process of tumor metastasis. TWIST1, a basic helix-loop-helix (bHLH) transcription factor, is the most important epithelial-mesenchymal transition (EMT) gene involved in embryonic development, tumor progression, and metastasis. However, the role that TWIST1 gene plays in the process of liver tumor metastasis in vivo is still not well understood. Zebrafish can serve as a powerful model for cancer research. Thus, in this study, we crossed twist1a+ and kras+ transgenic zebrafish, which, respectively, express hepatocyte-specific mCherry and enhanced green fluorescent protein (EGFP); they also drive overexpression of their respective transcription factors. This was found to exacerbate the development of metastatic HCC. Fluorescence of mCherry and EGFP-labeled hepatocytes revealed that approximately 37.5% to 45.5% of the twist1a+/kras+ double transgenic zebrafish exhibited spontaneous tumor metastasis from the liver to the abdomen and tail areas, respectively. We also investigated the inflammatory effects of lipopolysaccharides (LPS) on the hepatocyte-specific co-expression of twist1a+ and kras+ in double transgenic zebrafish. Following LPS exposure, co-expression of twist1a+ and kras+ was found to increase tumor metastasis by 57.8%, likely due to crosstalk with the EMT pathway. Our results confirm that twist1a and kras are important mediators in the development of metastatic HCC. Taken together, our in-vivo model demonstrated that co-expression of twist1a+/kras+ in conjunction with exposure to LPS enhanced metastatic HCC offers a useful platform for the study of tumor initiation and metastasis in liver cancer.

CTCF Expression and Dynamic Motif Accessibility Modulates Epithelial-Mesenchymal Gene Expression

Epithelial-mesenchymal transition (EMT) and its reversal, mesenchymal-epithelial transition (MET) drive tissue reorganization critical for early development. In carcinomas, processing through EMT, MET, or partial states promotes migration, invasion, dormancy, and metastatic colonization. As a reversible process, EMT is inherently regulated at epigenetic and epigenomic levels. To understand the epigenomic nature of reversible EMT and its partial states, we characterized chromatin accessibility dynamics, transcriptomic output, protein expression, and cellular phenotypes during stepwise reversible EMT. We find that the chromatin insulating protein machinery, including CTCF, is suppressed and re-expressed, coincident with broad alterations in chromatin accessibility, during EMT/MET, and is lower in triple-negative breast cancer cell lines with EMT features. Through an analysis of chromatin accessibility using ATAC-seq, we identify that early phases of EMT are characterized by enrichment for AP-1 family member binding motifs, but also by a diminished enrichment for CTCF binding motifs. Through a loss-of-function analysis, we demonstrate that the suppression of CTCF alters cellular plasticity, strengthening the epithelial phenotype via the upregulation of epithelial markers E-cadherin/CDH1 and downregulation of N-cadherin/CDH2. Conversely, the upregulation of CTCF leads to the upregulation of EMT gene expression and an increase in mesenchymal traits. These findings are indicative of a role of CTCF in regulating epithelial-mesenchymal plasticity and gene expression.

Determinants of renal cell carcinoma invasion and metastatic competence

Metastasis is the principal cause of cancer related deaths. Tumor invasion is essential for metastatic spread. However, determinants of invasion are poorly understood. We addressed this knowledge gap by leveraging a unique attribute of kidney cancer. Renal tumors invade into large vessels forming tumor thrombi (TT) that migrate extending sometimes into the heart. Over a decade, we prospectively enrolled 83 ethnically-diverse patients undergoing surgical resection for grossly invasive tumors at UT Southwestern Kidney Cancer Program. In this study, we perform comprehensive histological analyses, integrate multi-region genomic studies, generate in vivo models, and execute functional studies to define tumor invasion and metastatic competence. We find that invasion is not always associated with the most aggressive clone. Driven by immediate early genes, invasion appears to be an opportunistic trait attained by subclones with diverse oncogenomic status in geospatial proximity to vasculature. We show that not all invasive tumors metastasize and identify determinants of metastatic competency. TT associated with metastases are characterized by higher grade, mTOR activation and a particular immune contexture. Moreover, TT grade is a better predictor of metastasis than overall tumor grade, which may have implications for clinical practice.

CD44v6 Defines a New Population of Circulating Tumor Cells Not Expressing EpCAM

Simple Summary

In the present work, we describe (for the first time) the use of the transmembrane protein, CD44v6, to detect CTCs from blood samples of several patients with colorectal or breast cancer. We used CD44v6 antibodies to demonstrate that live CTCs can be specifically purified from CRC patient blood samples via magnetic bead- or FACS-based isolation techniques. Finally, we demonstrated that CD44v6-positive CTCs rarely expressed EpCam, which is currently the gold standard to enumerate CTCs, suggesting the need to use a combination of markers for a more comprehensive view of CTC heterogeneity.

Abstract

Circulating tumor cells (CTCs) are promising diagnostic and prognostic tools for clinical use. In several cancers, including colorectal and breast, the CTC load has been associated with a therapeutic response as well as progression-free and overall survival. However, counting and isolating CTCs remains sub-optimal because they are currently largely identified by epithelial markers such as EpCAM. New, complementary CTC surface markers are therefore urgently needed. We previously demonstrated that a splice variant of CD44, CD44 variable alternative exon 6 (CD44v6), is highly and specifically expressed by CTC cell lines derived from blood samples in colorectal cancer (CRC) patients. Two different approaches—immune detection coupled with magnetic beads and fluorescence-activated cell sorting—were optimized to purify CTCs from patient blood samples based on high expressions of CD44v6. We revealed the potential of the CD44v6 as a complementary marker to EpCAM to detect and purify CTCs in colorectal cancer blood samples. Furthermore, this marker is not restricted to colorectal cancer since CD44v6 is also expressed on CTCs from breast cancer patients. Overall, these results strongly suggest that CD44v6 could be useful to enumerate and purify CTCs from cancers of different origins, paving the way to more efficacious combined markers that encompass CTC heterogeneity.

Dynamic EMT: a multi-tool for tumor progression

The process of epithelial-mesenchymal transition (EMT) is fundamental for embryonic morphogenesis. Cells undergoing it lose epithelial characteristics and integrity, acquire mesenchymal features, and become motile. In cancer, this program is hijacked to confer essential changes in morphology and motility that fuel invasion. In addition, EMT is increasingly understood to orchestrate a large variety of complementary cancer features, such as tumor cell stemness, tumorigenicity, resistance to therapy and adaptation to changes in the microenvironment. In this review, we summarize recent findings related to these various classical and non-classical functions, and introduce EMT as a true tumorigenic multi-tool, involved in many aspects of cancer. We suggest that therapeutic targeting of the EMT process will-if acknowledging these complexities-be a possibility to concurrently interfere with tumor progression on many levels.

Chemoresistance is mediated by ovarian cancer leader cells in vitro

Background

Leader cells are a subset of cancer cells that coordinate the complex cell-cell and cell-matrix interactions required for ovarian cancer migration, invasion, tumour deposition and are negatively associated with progression-free survival and response to therapy. Emerging evidence suggests leader cells may be enriched in response to chemotherapy, underlying disease recurrence following treatment.

Methods

CRISPR was used to insert a bicistronic T2A-GFP cassette under the native KRT14 (leader cell) promoter. 2D and 3D drug screens were completed in the presence of chemotherapies used in ovarian cancer management. Leader cell; proliferative (Ki67); and apoptotic status (Cleaved Caspase 3) were defined by live cell imaging and flow cytometry. Quantitative real-time PCR defined “stemness” profiles. Proliferation was assessed on the xCELLigence real time cell analyser. Statistical Analysis was performed using unpaired non-parametric t-tests or one-way ANOVA and Tukey’s multiple comparison post hoc.

Results

Leader cells represent a transcriptionally plastic subpopulation of ovarian cancer cells that arise independently of cell division or DNA replication, and exhibit a “stemness” profile that does not correlate with epithelial-to-mesenchymal transition. Chemotherapeutics increased apoptosis-resistant leader cells in vitro, who retained motility and expressed known chemo-resistance markers including ALDH1, Twist and CD44v6. Functional impairment of leader cells restored chemosensitivity, with leader cell-deficient lines failing to recover following chemotherapeutic intervention.

Conclusions

Our data demonstrate that ovarian cancer leader cells are resistant to a diverse array of chemotherapeutic agents, and are likely to play a critical role in the recurrence of chemo-resistant disease as drivers of poor treatment outcomes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-02086-3.

Nanoliposomal Delivery of MicroRNA-203 Suppresses Migration of Triple-Negative Breast Cancer through Distinct Target Suppression

Triple-negative breast cancers affect thousands of women in the United States and disproportionately drive mortality from breast cancer. MicroRNAs are small, non-coding RNAs that negatively regulate gene expression post-transcriptionally by inhibiting target mRNA translation or by promoting mRNA degradation. We have identified that miRNA-203, silenced by epithelial-mesenchymal transition (EMT), is a tumor suppressor and can promote differentiation of breast cancer stem cells. In this study, we tested the ability of liposomal delivery of miR-203 to reverse aspects of breast cancer pathogenesis using breast cancer and EMT cell lines. We show that translationally relevant methods for increasing miR-203 abundance within a target tissue affects cellular properties associated with cancer progression. While stable miR-203 expression suppresses LASP1 and survivin, nanoliposomal delivery suppresses BMI1, indicating that suppression of distinct mRNA target profiles can lead to loss of cancer cell migration.

Breast cancer as an example of tumour heterogeneity and tumour cell plasticity during malignant progression

Heterogeneity within a tumour increases its ability to adapt to constantly changing constraints, but adversely affects a patient's prognosis, therapy response and clinical outcome. Intratumoural heterogeneity results from a combination of extrinsic factors from the tumour microenvironment and intrinsic parameters from the cancer cells themselves, including their genetic, epigenetic and transcriptomic traits, their ability to proliferate, migrate and invade, and their stemness and plasticity attributes. Cell plasticity constitutes the ability of cancer cells to rapidly reprogramme their gene expression repertoire, to change their behaviour and identities, and to adapt to microenvironmental cues. These features also directly contribute to tumour heterogeneity and are critical for malignant tumour progression. In this article, we use breast cancer as an example of the origins of tumour heterogeneity (in particular, the mutational spectrum and clonal evolution of progressing tumours) and of tumour cell plasticity (in particular, that shown by tumour cells undergoing epithelial-to-mesenchymal transition), as well as considering interclonal cooperativity and cell plasticity as sources of cancer cell heterogeneity. We review current knowledge on the functional contribution of cell plasticity and tumour heterogeneity to malignant tumour progression, metastasis formation and therapy resistance.

Epithelial-to-Mesenchymal Transition in the Light of Plasticity and Hybrid E/M States

Epithelial-to-mesenchymal transition (EMT) is a cellular program which leads to cells losing epithelial features, including cell polarity, cell-cell adhesion and attachment to the basement membrane, while gaining mesenchymal characteristics, such as invasive properties and stemness. This program is involved in embryogenesis, wound healing and cancer progression. Over the years, the role of EMT in cancer progression has been heavily debated, and the requirement of this process in metastasis even has been disputed. In this review, we discuss previous discrepancies in the light of recent findings on EMT, plasticity and hybrid E/M states. Moreover, we highlight various tumor microenvironmental cues and cell intrinsic signaling pathways that induce and sustain EMT programs, plasticity and hybrid E/M states. Lastly, we discuss how recent findings on plasticity, especially on those that enable cells to switch between hybrid E/M states, have changed our understanding on the role of EMT in cancer metastasis, stemness and therapy resistance.

MUC1-C in chronic inflammation and carcinogenesis; emergence as a target for cancer treatment

Chronic inflammation is a highly prevalent consequence of changes in environmental and lifestyle factors that contribute to the development of cancer. The basis for this critical association has largely remained unclear. The MUC1 gene evolved in mammals to protect epithelia from the external environment. The MUC1-C subunit promotes responses found in wound healing and cancer. MUC1-C induces EMT, epigenetic reprogramming, dedifferentiation and pluripotency factor expression, which when prolonged in chronic inflammation promote cancer progression. As discussed in this review, MUC1-C also drives drug resistance and immune evasion, and is an important target for cancer therapeutics now under development.

Cell lineage tracing links ERα loss in Erbb2-positive breast cancers to the arising of a highly aggressive breast cancer subtype

HER2-positive (HER2⁺) breast cancers (BrCs) contain approximately equal numbers of ERα⁺HER2⁺ and ERα^-HER2⁺ cases. An enduring obstacle is the unclear cell lineage-related characteristics of these BrCs. Although ERα⁺HER2⁺ BrCs could lose ERα to become ERα^-HER2⁺ BrCs, direct evidence is missing. To investigate ERα dependencies and their implications during BrC growth and metastasis, we generated ERα^CreRFP-T mice that produce an RFP-marked ERα⁺ mammary gland epithelial cell (MGEC) lineage. RCAS virus-mediated expression of Erbb2, a rodent Her2 homolog, first produced comparable numbers of ERα⁺RFP⁺Erbb2⁺ and ERα^-RFP^-Erbb2⁺ MGECs. Early hyperplasia developed mostly from ERα⁺RFP⁺Erbb2⁺ cells and ERα^-RFP^-Erbb2⁺ cells in these lesions were rare. The subsequently developed ductal carcinomas in situ had 64% slow-proliferating ERα⁺RFP⁺Erbb2⁺ cells, 15% fast-proliferating ERα^-RFP⁺Erbb2⁺ cells derived from ERα⁺RFP⁺Erbb2⁺ cells, and 20% fast-proliferating ERα^-RFP^-Erbb2⁺ cells. The advanced tumors had mostly ERα^-RFP⁺Erbb2⁺ and ERα^-RFP^-Erbb2⁺ cells and only a very small population of ERα⁺RFP⁺Erbb2⁺ cells. In ERα^-RFP⁺Erbb2⁺ cells, GATA3 and FoxA1 decreased expression and ERα promoter regions became methylated, consistent with the loss of ERα expression. Lung metastases consisted of mostly ERα^-RFP⁺Erbb2⁺ cells, a few ERα^-RFP^-Erbb2⁺ cells, and no ERα⁺RFP⁺Erbb2⁺ cells. The high metastatic capacity of ERα^-RFP⁺Erbb2⁺ cells was associated with ERK1/2 activation. These results show that the slow-proliferating, nonmetastatic ERα⁺RFP⁺Erbb2⁺ cells progressively lose ERα during tumorigenesis to become fast-proliferating, highly metastatic ERα^-RFP⁺Erbb2⁺ cells. The ERα^-Erbb2⁺ BrCs with an ERα⁺ origin are more aggressive than those ERα^-Erbb2⁺ BrCs with an ERα^- origin, and thus, they should be distinguished and treated differently in the future.

Capturing dynamic relevance in Boolean networks using graph theoretical measures

Motivation

Interaction graphs are able to describe regulatory dependencies between compounds without capturing dynamics. In contrast, mathematical models that are based on interaction graphs allow to investigate the dynamics of biological systems. However, since dynamic complexity of these models grows exponentially with their size, exhaustive analyses of the dynamics and consequently screening all possible interventions eventually becomes infeasible. Thus, we designed an approach to identify dynamically relevant compounds based on the static network topology.

Results

Here, we present a method only based on static properties to identify dynamically influencing nodes. Coupling vertex betweenness and determinative power, we could capture relevant nodes for changing dynamics with an accuracy of 75% in a set of 35 published logical models. Further analyses of the selected compounds’ connectivity unravelled a new class of not highly connected nodes with high impact on the networks’ dynamics, which we call gatekeepers. We validated our method’s working concept on logical models, which can be readily scaled up to complex interaction networks, where dynamic analyses are not even feasible.

Availability and implementation

Code is freely available at https://github.com/sysbio-bioinf/BNStatic.

Supplementary information

Supplementary data are available at Bioinformatics online.