Twist modulates breast cancer stem cells by transcriptional regulation of CD24 expression

The FZD7-TWIST1 axis is responsible for anoikis resistance and tumorigenesis in ovarian carcinoma

Frizzled family receptor 7 (FZD7), a Wnt signaling receptor, is associated with the maintenance of stem cell properties and cancer progression. FZD7 has emerged as a potential therapeutic target because it is capable of transducing both canonical and noncanonical Wnt signals. In this study, we investigated the regulatory pathway downstream of FZD7 and its functional roles. We found that FZD7 expression was crucial to the maintenance of the mesenchymal phenotype, anoikis resistance, and spheroid and tumor formation in ovarian cancer (OC). We identified TWIST1 as the crucial downstream effector of the FZD7 pathway. TWIST1, a basic helix loop helix transcription factor, is known to associate with mesenchymal and cancer stem cell phenotypes. Manipulating TWIST1 expression mimicked the functional consequences observed in the FZD7 model, and overexpression of TWIST1 partially rescued the functional phenotypes abolished by FZD7 knockdown. We further proved that FZD7 regulated TWIST1 expression through epigenetic modifications of H3K4me3 and H3K27ac at the TWIST1 proximal promoter. We also identified that the FZD7‐TWIST1 axis regulates the expression of BCL2, a gene that controls apoptosis. Identification of this FZD7‐TWIST1‐BCL2 pathway reaffirms the mechanism of anoikis resistance in OC. We subsequently showed that the FZD7‐TWIST1 axis can be targeted by using a small molecule inhibitor of porcupine, an enzyme essential for secretion and functional activation of Wnts. In conclusion, our results identified that the FZD7‐TWIST1 axis is important for tumorigenesis and anoikis resistance, and therapeutic inhibition results in cell death in OCs.

siRNA-Conjugated Nanoparticles to Treat Ovarian Cancer

Ovarian cancer is the fifth-most lethal cancer among women due to a lack of early detection and late-stage treatment options, and it is responsible for more than 14,000 deaths each year in the United States. Recently, there have been advances in RNA interference therapy, specifically with small interfering RNA (siRNA), to reduce tumor burden for ovarian cancer via gene down-regulation. However, delivery of siRNA poses its own challenges, as siRNA is unstable in circulation, is unable to be effectively internalized by cells, and may cause toxicity in off-target sites. To address such challenges, nanoparticle carriers have emerged as delivery platforms for the biocompatible, targeted delivery of siRNA-based therapies. Several preclinical studies have shown the promising effects of siRNA therapy to reduce chemotherapy resistance and proliferation of ovarian cancer cells. This review evaluates the recent advances, clinical applications, and future potential of nanoparticle-mediated delivery of siRNA therapeutics to target genes implicated in ovarian cancer.

Signaling Pathways Induced by Leptin during Epithelial⁻Mesenchymal Transition in Breast Cancer

Leptin is an adipokine that is overexpressed in obese and overweight people. Interestingly, women with breast cancer present high levels of leptin and of its receptor ObR. Leptin plays an important role in breast cancer progression due to the biological processes it participates in, such as epithelial⁻mesenchymal transition (EMT). EMT consists of a series of orchestrated events in which cell⁻cell and cell⁻extracellular matrix interactions are altered and lead to the release of epithelial cells from the surrounding tissue. The cytoskeleton is also re-arranged, allowing the three-dimensional movement of epithelial cells into the extracellular matrix. This transition provides cells with the ability to migrate and invade adjacent or distal tissues, which is a classic feature of invasive or metastatic carcinoma cells. In recent years, the number of cases of breast cancer has increased, making this disease a public health problem worldwide and the leading cause of death due to cancer in women. In this review, we focus on recent advances that establish: (1) leptin as a risk factor for the development of breast cancer, and (2) leptin as an inducer of EMT, an event that promotes tumor progression.

Nanoparticle Delivery of TWIST Small Interfering RNA and Anticancer Drugs: A Therapeutic Approach for Combating Cancer

Breast and ovarian cancer are the leading cause of cancer-related deaths in women in the United States with over 232,000 new Breast Cancer (BC) diagnoses expected in 2018 and almost 40,000 deaths and an estimated 239,000 new ovarian cancer (OC) cases and 152,000 deaths worldwide annually. OC is the most lethal gynecologic malignancy. This high mortality rate is due to tumor recurrence and metastasis, primarily caused by chemoresistant cancer stem-like cells (CSCs). Triple Negative Breast Cancer (TNBC) patients also become resistant to chemotherapy due to recurrence of CSCs. Currently, no ovarian or breast cancer therapies target CSC specifically. TWIST is overexpressed in the majority of chemoresistant cancers resulting in a low survival rate. Our long-term goal is to develop novel treatments for women with ovarian and breast cancer, specifically treatments that sensitize chemoresistant tumors. Despite successful initial surgery and chemotherapy, over 70% of advanced EOC will recur, and only 15-30% of recurrent disease will respond to chemotherapy (Cortez et al., 2017; Berezhnaya, 2010; Jackson et al., 2015). Moreover, drug resistance causes treatment failure in over 90% of patients with metastatic disease (Solmaz et al., 2015). Thus, recurrent metastatic disease is a major clinical challenge without effective therapy. One of the major challenges in the treatment of breast cancer is the presence of a subpopulation of cancer cells that are chemoresistant (CRC) and metastatic. Given that metastasis is the driving force behind mortality for breast and ovarian cancer patients, it is essential to identify the characteristics of these aberrant cancer cells that allow them to spread to distant sites in the body and develop into metastatic tumors. Understanding the metastatic mechanisms driving cancer cell dispersal will open the door to developing novel therapies that prevent metastasis and improve long-term outcomes for patients. In this chapter we assess the feasibility of targeting the Twist and EMT signaling pathways in breast and ovarian cancer. Additional discussions of the pathways that mediate epithelial-mesenchymal transition (EMT), a process that can give rise to chemoresistance. We review potential treatment strategies for targeting EMT and drug resistance as well as the problems that may arise with these targeted delivery therapeutic approaches. Finally, we examine recent advances in the field, including cancer stem cell targeted nanoparticle delivery and small interference RNA (siRNA) technology, and discuss the impact that these approaches may have on translating much needed therapeutic approaches into the clinic, for the benefit of patients battling this devastating disease.

Hyaluronic acid conjugated nanoparticle delivery of siRNA against TWIST reduces tumor burden and enhances sensitivity to cisplatin in ovarian cancer

TWIST protein is critical to development and is activated in many cancers. TWIST regulates epithelial-mesenchymal transition, and is linked to angiogenesis, metastasis, cancer stem cell phenotype, and drug resistance. The majority of epithelial ovarian cancer (EOC) patients with metastatic disease respond well to first-line chemotherapy but most relapse with disease that is both metastatic and drug resistant, leading to a five-year survival rate under 20%. We are investigating the role of TWIST in mediating these relapses. We demonstrate TWIST-siRNA (siTWIST) and a novel nanoparticle delivery platform to reverse chemoresistance in an EOC model. Hyaluronic-acid conjugated mesoporous silica nanoparticles (MSN-HAs) carried siTWIST into target cells and led to sustained TWIST knockdown in vitro. Mice treated with siTWIST-MSN-HA and cisplatin exhibited specific tumor targeting and reduction of tumor burden. This platform has potential application for overcoming clinical challenges of tumor cell targeting, metastasis and chemoresistance in ovarian and other TWIST overexpressing cancers.

U94 of human herpesvirus 6 down-modulates Src, promotes a partial mesenchymal-to-epithelial transition and inhibits tumor cell growth, invasion and metastasis

U94, the latency gene of human herpesvirus 6, was found to inhibit migration, invasion and proliferation of vascular endothelial cells (ECs). Because of its potent anti-migratory activity on ECs, we tested the capability of U94 to interfere with the individual steps of the metastatic cascade. We examined the U94 biological activity on the human breast cancer cell line MDA-MB 231, as a model of highly aggressive cancer cell. Here we show that the expression of U94 delivered by an HSV-1-based amplicon promoted down-modulation of Src and downstream molecules linked to cell motility and proliferation. Indeed, U94 expression strongly inhibited cell migration, invasiveness and clonogenicity. We investigated the effects of U94 in a three-dimensional rotary cell-culture system and observed the ability of U94 to modify tumor cell morphology by inducing a partial mesenchymal-to-epithelial transition. In fact, despite U94 did not induce any expression of the epithelial marker E-cadherin, it down-modulated different mesenchymal markers as β-catenin, Vimentin, TWIST, Snail1, and MMP2. In vivo data on the tumorigenicity of MDA-MB 231 displayed the capability of U94 to control tumor growth, invasiveness and metastasis, as well as tumor-driven angiogenesis. The antitumor U94 activity was also confirmed on the human cervical cancer cell line HeLa. The ability of U94 to inhibit cell growth, invasion and metastasis opens the way to a promising field of research aimed to develop new therapeutic approaches for treating tumor and cancer metastasis.

Replication-incompetent gammaretroviral and lentiviral vector-based insertional mutagenesis screens identify prostate cancer progression genes

Replication-incompetent gammaretroviral (γRV) and lentiviral (LV) vectors have both been used in insertional mutagenesis screens to identify cancer drivers. In this approach the vectors stably integrate in the host cell genome and induce cancers by dysregulating nearby genes. The cells that contain a retroviral vector provirus in or near a proto-oncogene or tumor suppressor are preferentially enriched in a tumor. γRV and LV vectors have different integration profiles and genotoxic potential, making them potentially complementary tools for insertional mutagenesis screens. We performed screens using both γRV and LV vectors to identify driver genes that mediate progression of androgen-independent prostate cancer (AIPC) using a xenotransplant mouse model. Vector transduced LNCaP cells were injected orthotopically into the prostate gland of immunodeficient mice. Mice that developed tumors were castrated to create an androgen-deficient environment and metastatic tumors that developed were analyzed. A high-throughput modified genomic sequencing PCR (MGS-PCR) approach identified the positions of vector integrations in these metastatic tumors. OR2A14, FER1L6, TAOK3, MAN1A2, MBNL2, SERBP1, PLEKHA2, SPTAN1, ADAMTS1, SLC30A5, ABCC1, SLC7A1 and SLC25A24 were identified as candidate prostate cancer (PC) progression genes. TAOK3 and ABCC1 expression in PC patients predicted the risk of recurrence after androgen deprivation therapy. Our data shows that γRV and LV vectors are complementary approaches to identify cancer driver genes which may be promising potential biomarkers and therapeutic targets.

Inflammation and Prostate Cancer

Chronic inflammation resulting from infections, altered metabolism, inflammatory diseases or other environmental factors can be a major contributor to the development of several types of cancer. In fact around 20% of all cancers are linked to some form of inflammation. Evidence gathered from genetic, epidemiological and molecular pathological studies suggest that inflammation plays a crucial role at various stages of prostatic carcinogenesis and tumor progression. These include initiation, promotion, malignant conversion, invasion, and metastasis. Detailed basic and clinical research in these areas, focused towards understanding the etiology of prostatic inflammation, as well as the exact roles that various signaling pathways play in promoting tumor growth, is critical for understanding this complex process. The information gained would be useful in developing novel therapeutic strategies such as molecular targeting of inflammatory mediators and immunotherapy-based approaches.

Cytoplasmic expression of Twist1, an EMT-related transcription factor, is associated with higher grades renal cell carcinomas and worse progression-free survival in clear cell renal cell carcinoma

Twist1 is a key transcription factor, which confers tumor cells with cancer stem cell (CSC)-like characteristics and enhances epithelial-mesenchymal transition in pathological conditions including tumor malignancy and metastasis. This study aimed to evaluate the expression patterns and clinical significance of Twist1 in renal cell carcinoma (RCC). The cytoplasmic and nuclear expression of Twist1 were examined in 252 well-defined renal tumor tissues, including 173 (68.7%) clear cell renal cell carcinomas (ccRCC), 45 (17.9%) papillary renal cell carcinomas (pRCC) and 34 (13.5%) chromophobe renal cell carcinoma, by immunohistochemistry on a tissue microarray. The association between expression of this marker and clinicopathologic parameters and survival outcomes were then analyzed. Twist1 was mainly localized to the cytoplasm of tumor cells (98.8%). Increased cytoplasmic expression of Twist1 was associated with higher grade tumors (P = 0.045), renal vein invasion (P = 0.031) and microvascular invasion (P = 0.044) in RCC. It was positively correlated with higher grade tumors (P = 0.026), shorter progression-free survival time (P = 0.027) in patients with ccRCC, and also with higher stage in pRCC patients (P = 0.036). Significantly higher cytoplasmic expression levels of Twist1 were found in ccRCC and pRCC subtypes, due to their more aggressive tumor behavior. Increased cytoplasmic expression of Twist1 had a critical role in worse prognosis in ccRCC. These findings suggest that cytoplasmic, rather than nuclear expression of Twist1 can be considered as a prognostic and therapeutic marker for targeted therapy of RCC, especially for ccRCC patients.

Clinical and biological significance of miR-193a-3p targeted KRAS in colorectal cancer pathogenesis

This study was to investigate the expression pattern, mechanisms and clinicopathological implications of miR-193a-3p in colorectal cancer. Fresh-frozen tissues from 70 matched colorectal adenocarciomas and the adjacent non-neoplastic mucosae were prospectively collected. Two colorectal cancer cell lines (SW480 and SW48) and a non-neoplastic colon cell line (FHC) were also used. The expression levels of miR193a-3p in the cells and tissues were measured by quantitative real-time polymerase chain reaction. The expression of KRAS protein as a predicted downstream target for miR-193a was studied by immunohistochemistry. Restoration of the miR-193a level in the cell lines by permanent transfection was achieved and multiple functional and immunological assays were performed to analyze the functions of miR-193a in vitro. Down-regulation of miR-193a-3p was noted in 70% of the colorectal cancer tissues when compared to non-neoplastic colorectal tissues. In addition, down-regulation of miR-193a was significantly correlated with carcinoma of early stages (P<.05). Significant inverse correlation between miR-193a-3p and its target KRAS protein was determined (P<.05). Overexpression of miR-193a in colon cancer cells resulted in reduced cell proliferation, increased apoptosis, induced significant changes in cell cycle events and decreased the expression of epithelial-mesenchymal transition marker TWIST. This study confirms the tumor suppressor roles of miR-193a-3p, its downstream target affinity to KRAS and clinical significance in patients with colorectal adenocarcinoma.

Multiple biological functions of Twist1 in various cancers

Twist1 is a well-known regulator of transcription during embryonic organogenesis in many species. In humans, Twist1 malfunction was first linked to Saethre-Chotzen syndrome and later identified to play an essential role in tumor initiation, stemness, angiogenesis, invasion, metastasis, and chemo-resistance in a variety of carcinomas, sarcomas, and hematological malignances. In this review, we will first focus on systematically elaborating the diverse pathological functions of Twist1 in various cancers, then delineating the intricate underlying network of molecular mechanisms, based on which we will summarize current therapeutic strategies in cancer treatment that target and modulate Twist1-involved signaling pathways. Most importantly, we will put special emphasis on revealing the independence and interdependency of these multiple biological functions of Twist1, piecing together the whole delicate picture of Twist1's diversified pathological roles in different cancers and providing new perspectives to guide future research.

Wogonoside inhibits invasion and migration through suppressing TRAF2/4 expression in breast cancer

Background

Twist1 is involved in tumor initiation and progression, which especially contributes to tumor invasion and metastasis. Wogonoside is the main in-vivo metabolite of wogonin, and it is also a natural product with potential treatment effects against cancer.

Methods

In this study, we investigated the in-vitro anti-invasion and in-vivo anti-metastasis effects of wogonoside on breast cancer cells and uncovered its underlying mechanism.

Results

The results showed that wogonoside could suppress the growth and metastasis of breast tumor in the orthotopic model of MDA-MB-231 cells. We found that wogonoside could reduce the overexpression of TNF-α, TRAF2 and TRAF4 in later stage of tumor, and improved tumor microenvironment. Therefore, TNF-α was utilized to induce metastases of breast cancer cell in vitro. Wogonoside could inhibit invasion and migration in TNF-α-induced MDA-MB-231, MDA-MB-435, and BT-474 cells. Mechanically, wogonoside inactivated NF-κB signaling through decreasing the protein expression of TRAF2/4, which further inhibited Twist1 expression. Consequently, wogonoside could down-regulate MMP-9, MMP-2, vimentin and CD44v6 expression in TNF-α-induced MDA-MB-231 and MDA-MB-435 cells. Then, these findings were proved in TNF-α + TGF-β1-induced MCF7 cells.

Conclusions

Wogonoside might be a potential therapeutic agent for the treatment of tumor metastasis in breast cancer.

Twist1/Dnmt3a and miR186 establish a regulatory circuit that controls inflammation-associated prostate cancer progression

Increasing evidences suggest that inflammatory microenvironment has a crucial role in prostate cancer (PCa) progression; however, the underlying mechanisms are unclear. Here, we used the inflammation-associated prostate cellular transformation model to screen out a crucial microRNA, miR186, which was significantly downregulated in the transformed cells and effectively rescued the transformed phenotype. On stimulation of inflammatory cytokines, the activated nuclear factor kappa B (NF-κB)/p65 was able to induce miR186 expression through binding to its promoter in non-transformed cells, whereas this pathway was lost in transformed cells. Interestingly, Twist1, which is a reported downstream target of miR186, was responsible for the loss of NF-κB/p65-miR186 pathway. Twist1 downregulated miR186 expression in a novel negative feedback loop binding to the E-box and simultaneously recruiting Dnmt3a, which facilitated the site-specific CpG methylation of the miR186 promoter, thereby blocked the transcriptional activity of NF-κB/p65 and the responsiveness of miR186 to inflammatory signals. The high level of Twist1 triggered this feedback loop that underlies the epigenetic switch, which was essential for maintaining transformed and advanced PCa state. Finally, our clinical data confirmed that the CpG methylation and miR186 expression levels were closely related with inflammation-associated human PCa progression.

Evidence for circulating cancer stem-like cells and epithelial-mesenchymal transition phenotype in the pleurospheres derived from lung adenocarcinoma using liquid biopsy

Lung cancer stem cells are supposed to be the main drivers of tumor initiation, maintenance, drug resistance, and relapse of the disease. Hence, identification of the cellular and molecular aspects of these cells is a prerequisite for targeted therapy of lung cancer. Currently, analysis of circulating tumor cells has the potential to become the main diagnostic technique to monitor disease progression or therapeutic response as it is non-invasive. However, accurate detection of circulating tumor cells has remained a challenge, as epithelial cell markers used so far are not always trustworthy for detecting circulating tumor cells, especially during epithelial-mesenchymal transition. As cancer stem cells are the only culprit to initiate metastatic tumors, our aim was to isolate and characterize circulating tumor stem cells rather than circulating tumor cells from the peripheral blood of NSCLC adenocarcinoma as limited data are available addressing the gene expression profiling of lung cancer stem cells. Here, we reveal that CD44(+)/CD24(-) population in circulation not only exhibit stem cell-related genes but also possess epithelial-mesenchymal transition characteristics. In conclusion, the use of one or more cancer stem cell markers along with epithelial, mesenchymal and epithelial mesenchymal transition markers will prospectively provide the most precise assessment of the threat for recurrence and metastatic disease and has a great potential for forthcoming applications in harvesting circulating tumor stem cells and their downstream applications. Our results will aid in developing diagnostic and prognostic modalities and personalized treatment regimens like dendritic cell-based immunotherapy that can be utilized for targeting and eliminating circulating tumor stem cells, to significantly reduce the possibility of relapse and improve clinical outcomes.

Disruption of TWIST1-RELA binding by mutation and competitive inhibition to validate the TWIST1 WR domain as a therapeutic target

Background

Most cancer deaths result from tumor cells that have metastasized beyond their tissue of origin, or have developed drug resistance. Across many cancer types, patients with advanced stage disease would benefit from a novel therapy preventing or reversing these changes. To this end, we have investigated the unique WR domain of the transcription factor TWIST1, which has been shown to play a role in driving metastasis and drug resistance.

Methods

In this study, we identified evolutionarily well-conserved residues within the TWIST1 WR domain and used alanine substitution to determine their role in WR domain-mediated protein binding. Co-immunoprecipitation was used to assay binding affinity between TWIST1 and the NFκB subunit p65 (RELA). Biological activity of this complex was assayed using a dual luciferase assay system in which firefly luciferase was driven by the interleukin-8 (IL-8) promoter, which is upregulated by the TWIST1-RELA complex. Finally, in order to inhibit the TWIST1-RELA interaction, we created a fusion protein comprising GFP and the WR domain. Cell fractionation and proteasome inhibition experiments were utilized to elucidate the mechanism of action of the GFP-WR fusion.

Results

We found that the central residues of the WR domain (W190, R191, E193) were important for TWIST1 binding to RELA, and for increased activation of the IL-8 promoter. We also found that the C-terminal 245 residues of RELA are important for TWIST1 binding and IL-8 promoter activation. Finally, we found the GFP-WR fusion protein antagonized TWIST1-RELA binding and downstream signaling. Co-expression of GFP-WR with TWIST1 and RELA led to proteasomal degradation of TWIST1, which could be inhibited by MG132 treatment.

Conclusions

These data provide evidence that mutation or inhibition of the WR domain reduces TWIST1 activity, and may represent a potential therapeutic modality.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-017-3169-9) contains supplementary material, which is available to authorized users.

BRCA1-IRIS overexpression promotes and maintains the tumor initiating phenotype: implications for triple negative breast cancer early lesions

Tumor-initiating cells (TICs) are cancer cells endowed with self-renewal, multi-lineage differentiation, increased chemo-resistance, and in breast cancers the CD44+/CD24-/ALDH1+ phenotype. Triple negative breast cancers show lack of BRCA1 expression in addition to enhanced basal, epithelial-to-mesenchymal transition (EMT), and TIC phenotypes. BRCA1-IRIS (hereafter IRIS) is an oncogene produced by the alternative usage of the BRCA1 locus. IRIS is involved in induction of replication, transcription of selected oncogenes, and promoting breast cancer cells aggressiveness. Here, we demonstrate that IRIS overexpression (IRISOE) promotes TNBCs through suppressing BRCA1 expression, enhancing basal-biomarkers, EMT-inducers, and stemness-enforcers expression. IRISOE also activates the TIC phenotype in TNBC cells through elevating CD44 and ALDH1 expression/activity and preventing CD24 surface presentation by activating the internalization pathway EGFR→c-Src→cortactin. We show that the intrinsic sensitivity to an anti-CD24 cross-linking antibody-induced cell death in membranous CD24 expressing/luminal A cells could be acquired in cytoplasmic CD24 expressing IRISOE TNBC/TIC cells through IRIS silencing or inactivation. We show that fewer IRISOE TNBC/TICs cells form large tumors composed of TICs, resembling TNBCs early lesions in patients that contain metastatic precursors capable of disseminating and metastasizing at an early stage of the disease. IRIS-inhibitory peptide killed these IRISOE TNBC/TICs, in vivo and prevented their dissemination and metastasis. We propose IRIS inactivation could be pursued to prevent dissemination and metastasis from early TNBC tumor lesions in patients.

Combination Twist1 and CA15-3 in axillary lymph nodes for breast cancer prognosis

Twist1 overexpression is involved in epithelial-mesenchymal transition resulting in migration and metastasis of breast cancer. Carcinoma antigen 15–3 (CA15-3) is widely used to monitor the prognosis for patients after treatment. However, the significance of Twist1 in axillary lymph nodes (ALN) and CA15-3 for co-examination for survival rates remains to be elucidated. The present study aimed to explore the role of the combination of Twist1 expression in metastasized ALN and the serum level of CA15-3 in evaluating the prognosis of patients with breast cancer. cluster of differentiation (CD)44, CD24, aldehyde dehydrogenase (ALDH)1 and Twist1 expression in normal and metastasized ALN from 102 patients with breast cancer were detected using laser confocal microscopy and the expression of the genes evaluated by reverse transcription-quantitative polymerase chain reaction; E-cadherin, N-cadherin and vimentin expression was also tested by western blotting. The serum concentrations of CA15-3 prior to and following surgery were analyzed by chemiluminescence immunoassay. The expression of CD44, ALDH1 and Twist1 mRNA in the primary breast cancer tissues and involved ALN was upregulated compared with the normal ALN (P<0.05). The proteins N-cadherin and vimentin of the involved ALN were poorly expressed compared with breast cancer tissues, however E-cadherin protein expression was higher in metastasized and normal ALN compared with primary cancer tissues (P<0.05). Of the 102 patients, the serum CA15-3 levels of the patients in stages I and II were significantly lower compared with stages III and IV (P<0.05). Twist1⁺/CA15-3⁺, HER2-negative/Twist1⁺/CA15-3⁺ and Triple-receptor negative/Twist1⁺/CA15-3⁺ groups displayed a shorter progression-free survival compared with others. The results of the present study demonstrated that CD44, ALDH1 and Twist1 were significantly overexpressed in involved ALN. The serum levels of CA15-3 in those patients were clearly increased and the survival rates decreased, which suggested that a combination of Twist1 in ALN and CA15-3 may function as an indicator for the prognosis of patients with breast cancer.

Genomic pathways modulated by Twist in breast cancer

Background

The basic helix-loop-helix transcription factor TWIST1 (Twist) is involved in embryonic cell lineage determination and mesodermal differentiation. There is evidence to indicate that Twist expression plays a role in breast tumor formation and metastasis, but the role of Twist in dysregulating pathways that drive the metastatic cascade is unclear. Moreover, many of the genes and pathways dysregulated by Twist in cell lines and mouse models have not been validated against data obtained from larger, independant datasets of breast cancer patients.

Methods

We over-expressed the human Twist gene in non-metastatic MCF-7 breast cancer cells to generate the estrogen-independent metastatic breast cancer cell line MCF-7/Twist. These cells were inoculated in the mammary fat pad of female severe compromised immunodeficient mice, which subsequently formed xenograft tumors that metastasized to the lungs. Microarray data was collected from both in vitro (MCF-7 and MCF-7/Twist cell lines) and in vivo (primary tumors and lung metastases) models of Twist expression. Our data was compared to several gene datasets of various subtypes, classes, and grades of human breast cancers.

Results

Our data establishes a Twist over-expressing mouse model of breast cancer, which metastasizes to the lung and replicates some of the ontogeny of human breast cancer progression. Gene profiling data, following Twist expression, exhibited novel metastasis driver genes as well as cellular maintenance genes that were synonymous with the metastatic process. We demonstrated that the genes and pathways altered in the transgenic cell line and metastatic animal models parallel many of the dysregulated gene pathways observed in human breast cancers.

Conclusions

Analogous gene expression patterns were observed in both in vitro and in vivo Twist preclinical models of breast cancer metastasis and breast cancer patient datasets supporting the functional role of Twist in promoting breast cancer metastasis. The data suggests that genetic dysregulation of Twist at the cellular level drives alterations in gene pathways in the Twist metastatic mouse model which are comparable to changes seen in human breast cancers. Lastly, we have identified novel genes and pathways that could be further investigated as targets for drugs to treat metastatic breast cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-3033-3) contains supplementary material, which is available to authorized users.

Emerging Non-Canonical Functions and Regulation by p53: p53 and Stemness

Since its discovery nearly 40 years ago, p53 has ascended to the forefront of investigated genes and proteins across diverse research disciplines and is recognized most exclusively for its role in cancer as a tumor suppressor. Levine and Oren (2009) reviewed the evolution of p53 detailing the significant discoveries of each decade since its first report in 1979. In this review, we will highlight the emerging non-canonical functions and regulation of p53 in stem cells. We will focus on general themes shared among p53's functions in non-malignant stem cells and cancer stem-like cells (CSCs) and the influence of p53 on the microenvironment and CSC niche. We will also examine p53 gain of function (GOF) roles in stemness. Mutant p53 (mutp53) GOFs that lead to survival, drug resistance and colonization are reviewed in the context of the acquisition of advantageous transformation processes, such as differentiation and dedifferentiation, epithelial-to-mesenchymal transition (EMT) and stem cell senescence and quiescence. Finally, we will conclude with therapeutic strategies that restore wild-type p53 (wtp53) function in cancer and CSCs, including RING finger E3 ligases and CSC maintenance. The mechanisms by which wtp53 and mutp53 influence stemness in non-malignant stem cells and CSCs or tumor-initiating cells (TICs) are poorly understood thus far. Further elucidation of p53's effects on stemness could lead to novel therapeutic strategies in cancer research.

Nanoparticle delivery of siRNA against TWIST to reduce drug resistance and tumor growth in ovarian cancer models

Epithelial ovarian cancer (EOC) is the most deadly gynecologic malignancy on account of its late stage at diagnosis and frequency of drug resistant recurrences. Novel therapies to overcome these barriers are urgently needed. TWIST is a developmental transcription factor reactivated in cancers and linked to angiogenesis, metastasis, cancer stem cell phenotype, and drug resistance, making it a promising therapeutic target. In this work, we demonstrate the efficacy of TWIST siRNA (siTWIST) and two nanoparticle delivery platforms to reverse chemoresistance in EOC models. Polyamidoamine dendrimers and mesoporous silica nanoparticles (MSNs) carried siTWIST into target cells and led to sustained TWIST knockdown in vitro. Mice treated with cisplatin plus MSN-siTWIST exhibited lower tumor burden than mice treated with cisplatin alone, with most of the effect coming from reduction in disseminated tumors. This platform has potential application for overcoming the clinical challenges of metastasis and chemoresistance in EOC and other TWIST overexpressing cancers.

TWIST1 drives cisplatin resistance and cell survival in an ovarian cancer model, via upregulation of GAS6, L1CAM, and Akt signalling

Epithelial ovarian cancer (EOC) is the most deadly gynaecologic malignancy due to late onset of symptoms and propensity towards drug resistance. Epithelial-mesenchymal transition (EMT) has been linked to the development of chemoresistance in other cancers, yet little is known regarding its role in EOC. In this study, we sought to determine the role of the transcription factor TWIST1, a master regulator of EMT, on cisplatin resistance in an EOC model. We created two Ovcar8-derived cell lines that differed only in their TWIST1 expression. TWIST1 expression led to increased tumour engraftment in mice, as well as cisplatin resistance in vitro. RNA sequencing analysis revealed that TWIST1 expression resulted in upregulation of GAS6 and L1CAM and downregulation of HMGA2. Knockdown studies of these genes demonstrated that loss of GAS6 or L1CAM sensitized cells to cisplatin, but that loss of HMGA2 did not give rise to chemoresistance. TWIST1, in part via GAS6 and L1CAM, led to higher expression and activation of Akt upon cisplatin treatment, and inhibition of Akt activation sensitized cells to cisplatin. These results suggest TWIST1- and EMT-driven increase in Akt activation, and thus tumour cell proliferation, as a potential mechanism of drug resistance in EOC.

NF-kappaΒ-inducing kinase regulates stem cell phenotype in breast cancer

Breast cancer stem cells (BCSCs) overexpress components of the Nuclear factor-kappa B (NF-κB) signaling cascade and consequently display high NF-κB activity levels. Breast cancer cell lines with high proportion of CSCs exhibit high NF-κB-inducing kinase (NIK) expression. The role of NIK in the phenotype of cancer stem cell regulation is poorly understood. Expression of NIK was analyzed by quantitative RT-PCR in BCSCs. NIK levels were manipulated through transfection of specific shRNAs or an expression vector. The effect of NIK in the cancer stem cell properties was assessed by mammosphere formation, mice xenografts and stem markers expression. BCSCs expressed higher levels of NIK and its inhibition through small hairpin (shRNA), reduced the expression of CSC markers and impaired clonogenicity and tumorigenesis. Genome-wide expression analyses suggested that NIK acts on ERK1/2 pathway to exert its activity. In addition, forced expression of NIK increased the BCSC population and enhanced breast cancer cell tumorigenicity. The in vivo relevance of these results is further supported by a tissue microarray of breast cancer samples in which we observed correlated expression of Aldehyde dehydrogenase (ALDH) and NIK protein. Our results support the essential involvement of NIK in BCSC phenotypic regulation via ERK1/2 and NF-κB.

PAK1 confers chemoresistance and poor outcome in non-small cell lung cancer via β-catenin-mediated stemness

PAK1 confers resistance to the estrogen antagonist tamoxifen in breast cancer. However, a role for PAK1 remains to be elucidated for chemoresistance and prognosis in non-small cell lung cancer (NSCLC). We provide evidence that PAK1 confers cisplatin resistance by increasing β-catenin expression through ERK/GSK3β signaling. The increased β-catenin expression promotes sphere cell formation and expression of stemness markers and this β-catenin-induced stemness is responsible for PAK1-mediated cisplatin resistance. We enrolled 87 NSCLC patients who had received cisplatin-based chemotherapy to confirm the association between PAK1 expression and response to chemotherapy and outcomes. PAK1 expression, evaluated by immunohistochemistry, was positively correlated with pERK and β-catenin expression in lung tumors. Patients with high-PAK1, high-pERK, and high-nuclear β-catenin tumors more frequently showed an unfavorable response to cisplatin-based chemotherapy when compared to their counterparts. Kaplan-Meier and Cox regression analysis also indicated a poorer overall survival (OS) and relapse free survival (RFS) in patients with high-PAK1, high-pERK, and high-nuclear β-catenin tumors. In conclusion, PAK1 confers cisplatin resistance in NSCLC via β-catenin-mediated stemness. Therefore, we suggest that clinical use of a combination of the MEK/ERK inhibitor AZD6244 and cisplatin might improve sensitivity to cisplatin-based chemotherapy and outcomes in NSCLC patients who harbor high-PAK1-expressing tumors.

Stand-Sit Microchip for High-Throughput, Multiplexed Analysis of Single Cancer Cells

Cellular heterogeneity in function and response to therapeutics has been a major challenge in cancer treatment. The complex nature of tumor systems calls for the development of advanced multiplexed single-cell tools that can address the heterogeneity issue. However, to date such tools are only available in a laboratory setting and don’t have the portability to meet the needs in point-of-care cancer diagnostics. Towards that application, we have developed a portable single-cell system that is comprised of a microchip and an adjustable clamp, so on-chip operation only needs pipetting and adjusting of clamping force. Up to 10 proteins can be quantitated from each cell with hundreds of single-cell assays performed in parallel from one chip operation. We validated the technology and analyzed the oncogenic signatures of cancer stem cells by quantitating both aldehyde dehydrogenase (ALDH) activities and 5 signaling proteins in single MDA-MB-231 breast cancer cells. The technology has also been used to investigate the PI3K pathway activities of brain cancer cells expressing mutant epidermal growth factor receptor (EGFR) after drug intervention targeting EGFR signaling. Our portable single-cell system will potentially have broad application in the preclinical and clinical settings for cancer diagnosis in the future.

Targeting the SIN3A-PF1 interaction inhibits epithelial to mesenchymal transition and maintenance of a stem cell phenotype in triple negative breast cancer

Triple negative breast cancer (TNBC) is characterized by a poorly differentiated phenotype and limited treatment options. Aberrant epigenetics in this subtype represent a potential therapeutic opportunity, but a better understanding of the mechanisms contributing to the TNBC pathogenesis is required. The SIN3 molecular scaffold performs a critical role in multiple cellular processes, including epigenetic regulation, and has been identified as a potential therapeutic target. Using a competitive peptide corresponding to the SIN3 interaction domain of MAD (Tat-SID), we investigated the functional consequences of selectively blocking the paired amphipathic α-helix (PAH2) domain of SIN3. Here, we report the identification of the SID-containing adaptor PF1 as a factor required for maintenance of the TNBC stem cell phenotype and epithelial-to-mesenchymal transition (EMT). Tat-SID peptide blocked the interaction between SIN3A and PF1, leading to epigenetic modulation and transcriptional downregulation of TNBC stem cell and EMT markers. Importantly, Tat-SID treatment also led to a reduction in primary tumor growth and disseminated metastatic disease in vivo. In support of these findings, knockdown of PF1 expression phenocopied treatment with Tat-SID both in vitro and in vivo. These results demonstrate a critical role for a complex containing SIN3A and PF1 in TNBC and provide a rational for its therapeutic targeting.

Poly(rC)-Binding Protein 2 Regulates Hippo Signaling To Control Growth in Breast Epithelial Cells

Poly(rC)-binding proteins (PCBPs) are multifunctional adapters that mediate interactions between nucleic acids, iron cofactors, and other proteins, affecting the fates and activities of the components of these interactions. Here, we show that PCBP2 forms a complex with the Hippo pathway components Salvador (Sav1), Mst1, Mst2, and Lats1 in human cells and mouse tissues. Hippo is a kinase cascade that functions to phosphorylate and inactivate the transcriptional coactivators YAP and TAZ, which control cell growth and proliferation. PCBP2 specifically interacts with the scaffold protein Sav1 and prevents proteolytic cleavage of the Mst1 kinase, resulting in increased signaling through Hippo and suppressed activity of YAP and TAZ. Human breast epithelial cells lacking PCBP2 exhibit impaired proteasomal degradation of TAZ. They accumulate TAZ in both the nucleus and the cytosol, increase expression of YAP and TAZ connective tissue growth factor (CTGF) and Cyr61 target genes, and exhibit anchorage-independent growth. Thus, PCBP2 can function as a component of the Hippo complex, enhancing signaling, suppressing activity of YAP and TAZ, and altering the growth characteristics of cells.

TWIST-1 promotes cell growth, drug resistance and progenitor clonogenic capacities in myeloid leukemia and is a novel poor prognostic factor in acute myeloid leukemia

Alterations of TWIST-1 expression are often seen in solid tumors and contribute to tumorigenesis and cancer progression. However, studies concerning its pathogenic role in leukemia are scarce. Our study shows that TWIST-1 is overexpressed in bone marrow mononuclear cells of patients with acute myeloid leukemia (AML) and chronic myeloid leukemia (CML). Gain-of-function and loss-of-function analyses demonstrate that TWIST-1 promotes cell growth, colony formation and drug resistance of AML and CML cell lines. Furthermore, TWIST-1 is aberrantly highly expressed in CD34⁺CD38⁻ leukemia stem cell candidates and its expression declines with differentiation. Down-modulation of TWIST-1 in myeloid leukemia CD34⁺ cells impairs their colony-forming capacity. Mechanistically, c-MPL, which is highly expressed in myeloid leukemia cells and associated with poor prognosis, is identified as a TWIST-1 coexpressed gene in myeloid leukemia patients and partially contributes to TWIST-1-mediated leukemogenic effects. Moreover, patients with higher TWIST-1 expression have shorter overall and event-free survival (OS and EFS) in AML. Multivariate analysis further demonstrates that TWIST-1 overexpression is a novel independent unfavourable predictor for both OS and EFS in AML. These data highlight TWIST-1 as a new candidate gene contributing to leukemogenesis of myeloid leukemia, and propose possible new avenues for improving risk and treatment stratification in AML.

HOXA5 determines cell fate transition and impedes tumor initiation and progression in breast cancer through regulation of E-cadherin and CD24

Loss of HOXA5 expression occurs frequently in breast cancer and correlates with higher pathological grade and poorer disease outcome. However, how HOX proteins drive differentiation in mammalian cells is poorly understood. In this paper, we investigated cellular and molecular consequences of loss of HOXA5 in breast cancer, and the role played by retinoic acid in HOXA5 function. Analysis of global gene expression data from HOXA5-depleted MCF10A breast epithelial cells, followed by validation, pointed to a role for HOXA5 in maintaining several molecular traits typical of the epithelial lineage such as cell-cell adhesion, tight junctions and markers of differentiation. Depleting HOXA5 in immortalized MCF10A or transformed MCF10A-Kras cells reduced their CD24⁺/CD44^lo population, enhanced self-renewal capacity and reduced expression of E-cadherin (CDH1) and CD24. In the case of MCF10A-Kras, HOXA5 loss increased branching and protrusive morphology in Matrigel, all features suggestive of epithelial to basal transition. Further, orthotopically implanted xenografts of MCF10A-Kras-scr grew as well-differentiated pseudo-luminal carcinomas, while MCF10A-Kras-shHOXA5 cells formed aggressive, poorly differentiated carcinomas. Conversely, ectopic expression of HOXA5 in aggressive SUM149 or SUM159 breast cancer cells reversed the cellular and molecular alterations observed in the HOXA5-depleted cells. Retinoic acid is a known upstream regulator of HOXA5 expression. HOXA5 depletion in MCF10A cells engineered to express doxycycline-induced shHOXA5 slowed transition of cells from a less differentiated CD24^-/CD44⁺ to the more differentiated CD24⁺/CD44⁺ state. This transition was promoted by retinal treatment, which upregulated endogenous HOXA5 expression and caused re-expression of occludin and claudin-7 (CLDN7). Expression of CDH1 and CD24 was transcriptionally upregulated by direct binding of HOXA5 to their promoter sequences as demonstrated by luciferase and ChIP analyses. Thus, loss of HOXA5 in mammary cells leads to loss of epithelial traits, an increase in stemness and cell plasticity, and the acquisition of more aggressive phenotypes.

An improved strategy to detect the epithelial-mesenchymal transition process in circulating tumor cells in hepatocellular carcinoma patients

PURPOSE

We adopted a new strategy to explore the relationship between the EMT process of CTCs and hepatocellular carcinoma (HCC). Furthermore, we intend to illustrate the potential diagnostic value of CTCs of distinct phenotypes in HCC.

METHODS

The clinical data of 33 HCC patients and 10 healthy volunteers were collected retrospectively. By using the optimized CanPatrol CTC enrichment technique, patient blood samples of about 5 ml were collected, and CTCs were identified and characterized. The first step of this detection process was to isolate CTCs via a filter-based method; then, an RNA in situ hybridization (RNA-ISH) technique based on the branched DNA signal amplification technology was used to classify the CTCs according to EMT markers. The relationships between HCC CTCs and clinical characteristics were analyzed.

RESULTS

The number of epithelial CTCs was related to tumor size (r = 0.456, p = 0.008), epithelial-mesenchymal-mixed CTCs were related to tumor number (r = 0.421, p = 0.015), and mesenchymal CTC was associated with metastasis (r = 0.375, p = 0.032). There was no significant correlation between CTC number and other clinicopathological factors, such as age, serum AFP level or cirrhosis.

CONCLUSIONS

Epithelial-mesenchymal-mixed CTCs seem to play an important role in EMT transition in HCC, mixed CTCs might be a vital factor for intrahepatic metastasis, and mesenchymal CTCs had the potential to be a predictor of extrahepatic metastasis.

miR-10b expression in breast cancer stem cells supports self-renewal through negative PTEN regulation and sustained AKT activation

Cancer stem cells (CSCs) are linked to metastasis. Moreover, a discrete group of miRNAs (metastamiRs) has been shown to promote metastasis. Accordingly, we propose that miRNAs that function as metastatic promoters may influence the CSC phenotype. To study this issue, we compared the expression of 353 miRNAs in CSCs enriched from breast cancer cell lines using qRT-PCR analysis. One of the most altered miRNAs was miR-10b, which is a reported promoter of metastasis and migration. Stable overexpression of miR-10b in MCF-7 cells (miR-10b-OE cells) promoted higher self-renewal and expression of stemness and epithelial-mesenchymal transition (EMT) markers. In agreement with these results, inhibiting miR-10b expression using synthetic antisense RNAs resulted in a decrease in CSCs self-renewal. Bioinformatics analyses identified several potential miR-10b mRNA targets, including phosphatase and tensin homolog (PTEN), a key regulator of the PI3K/AKT pathway involved in metastasis, cell survival, and self-renewal. The targeting of PTEN by miR-10b was confirmed using a luciferase reporter, qRT-PCR, and Western blot analyses. Lower PTEN levels were observed in CSCs, and miR-10b depletion not only increased PTEN mRNA and protein expression but also decreased the activity of AKT, a downstream PTEN target kinase. Correspondingly, PTEN knockdown increased stem cell markers, whereas AKT inhibitors compromised the self-renewal ability of CSCs and breast cancer cell lines overexpressing miR-10b. In conclusion, miR-10b regulates the self-renewal of the breast CSC phenotype by inhibiting PTEN and maintaining AKT pathway activation.

Osteopontin-A Master Regulator of Epithelial-Mesenchymal Transition

Osteopontin (OPN) plays an important functional role in both physiologic and pathologic states. OPN is implicated in the progression of fibrosis, cancer, and metastatic disease in several organ systems. The epithelial-mesenchymal transition (EMT), first described in embryology, is increasingly being recognized as a significant contributor to fibrotic phenotypes and tumor progression. Several well-established transcription factors regulate EMT and are conserved across tissue types and organ systems, including TWIST, zinc finger E-box-binding homeobox (ZEB), and SNAIL-family members. Recent literature points to an important relationship between OPN and EMT, implicating OPN as a key regulatory component of EMT programs. In this review, OPN’s interplay with traditional EMT activators, both directly and indirectly, will be discussed. Also, OPN’s ability to restructure the tissue and tumor microenvironment to indirectly modify EMT will be reviewed. Together, these diverse pathways demonstrate that OPN is able to modulate EMT and provide new targets for directing therapeutics.

Novel Molecular Markers for Breast Cancer

The use of molecular biomarkers assures that breast cancer (BC) patients receive optimal treatment. Established biomarkers, such as estrogen receptor, progesterone receptor, HER2, and Ki67, have been playing significant roles in the subcategorization of BC to predict the prognosis and decide the specific therapy to each patient. Antihormonal therapy using 4-hydroxytamoxifen or aromatase inhibitors have been employed in patients whose tumor cells express hormone receptors, while monoclonal antibody to HER2 has been administered to HER2-positive BCs. Although new therapeutic agents have been developed in the past few decades, many patients still die of the disease due to relapse; thus, novel molecular markers that predict therapeutic failure and those that can be targets for specific therapy are expected. We have chosen four of such molecules by reviewing recent publications, which are cyclin E, B-Myb, Twist, and DMP1β. The oncogenicity of these molecules has been demonstrated in vivo and/or in vitro through studies using transgenic mice or siRNAs, and their expressions have been shown to be associated with shortened overall or disease-free survival of BC patients. The former three molecules have been shown to accelerate epithelial-mesenchymal transition that is often associated with cancer stem cell-ness and metastasis; all these four can be novel therapeutic targets as well. Thus, large prospective studies employing immunohistochemistry will be needed to establish the predictive values of these molecules in patients with BC.

Inflammation fuels tumor progress and metastasis

Inflammation is a beneficial response that can remove pathogens, repair injured tissue and restore homeostasis to damaged tissues and organs. However, increasing evidence indicate that chronic inflammation plays a pivotal role in tumor development, as well as progression, metastasis, and resistance to chemotherapy. We will review the current knowledge regarding the contribution of inflammation to epithelial mesenchymal transition. We will also provide some perspectives on the relationship between ER-stress signals and metabolism, and the role of these processes in the development of inflammation.

Absence of DAB2IP promotes cancer stem cell like signatures and indicates poor survival outcome in colorectal cancer

Metastasis is a critical factor for the high mortality of colorectal cancer (CRC), but its mechanism is not completely understood. Epithelial-mesenchymal transition (EMT) is thought to play a key role in metastasis and also increases the cancer stem cell (CSC) feature that facilitates metastatic colonization. In this study, we investigated the biological roles of DAB2IP regulating EMT and stem cell-like features in human CRC. We demonstrate that DAB2IP suppresses NF-κB-mediated EMT and CSC features in CRC cells. In DAB2IP knockout mice, we discovered the hyperplasia in colonic epithelium which aberrantly represents the mesenchymal feature and NF-κB pathway activation. In clinic CRC tissue, we also reveal that reduced DAB2IP can enrich the CD133(+) subpopulation. DAB2IP expression was inversely correlated with tumor differentiation and metastasis, and patients with lower DAB2IP expression had shorter overall survival time. Taken together, our study demonstrates that DAB2IP inhibits NF-κB-inducing EMT and CSC to suppress the CRC progression, and also suggests that DAB2IP is a beneficial prediction factor for CRC patient prognosis.

Twist-BRD4 complex: potential drug target for basal-like breast cancer

As an important basic helix-loop-helix (bHLH) transcription factor, Twist associates with several physiological processes such as mesodermal development, and pathological processes such as Saethre-Chotzen syndrome. During cancer progression, Twist induces epithelial-mesenchymal transition (EMT), potentiating cancer cell invasion and metastasis. Although many studies have revealed its multiple biological roles, it remained unclear how Twist transcriptionally activates targeted genes. Recently we discovered tip60-mediated Twist di-acetylation in the ''histone H4-mimic'' GK-X-GK motif. The di-acetylated Twist recruits BRD4 and related transcriptional components to super-enhancer of its targeted genes during progression of basal-like breast cancer (BLBC). Here, we review this new advance of regulation and functional mechanism of Twist.

Links between cancer stem cells and epithelial-mesenchymal transition

The epithelial-mesenchymal transition (EMT) has been reported to be an important program that is often activated during the process of cancer invasion and metastasis. Cancer stem cells (CSCs) that can initiate and maintain cancer are also involved in invasion and metastasis of cancer. Recently, insights into the molecular mechanisms and functional features of mesenchymal cells have been greatly colored by findings that some of them have been endowed with the self-renewal trait associated with normal tissue stem cells and CSCs. Among cancer cells experiencing EMT, only some of the most competent CSCs will succeed in planting in another organ. In this paper, we review the molecular mechanism behind the link of EMT and CSCs in cancer progression.

CD24 Overexpression Is Associated with Poor Prognosis in Luminal A and Triple-Negative Breast Cancer

CD24 is associated with unfavourable prognoses in various cancers, but the prevalence of CD24 expression and its influence on clinical outcome in subtypes of breast cancers remain unclear. CD24 expression was analyzed by immunohistochemistry in 747 breast cancer tissues, and DNA methylation and histone modification status in the promoter region of CD24 were assessed using bisulfite sequencing and chromatin immunoprecipitation assay. 213 (28.5%) samples exhibited high CD24 expression in the membrane and/or cytoplasm of breast cancer cells, and CD24 overexpression was significantly correlated with the presence of lymph node metastasis and more advanced pathological stage. Patients with CD24-high tumours had significantly shorter patient survival than those with CD24-low tumours. Importantly, multivariate analysis that included tumour size, lymph node metastasis and chemotherapy demonstrated that high CD24 expression is independently associated with poorer survival in luminal A and triple-negative breast cancer (TNBC) subtypes. Furthermore, CD24 gene expression was associated with histone acetylation independent of DNA methylation, suggesting its epigenetic regulation in breast cancer. Our results suggest that CD24 overexpression is an independent unfavourable prognostic factor in breast cancer, especially for luminal A and TNBC subtypes, and CD24 may be a promising therapeutic target for specific subtypes of breast cancer.

The network of pluripotency, epithelial-mesenchymal transition, and prognosis of breast cancer

Breast cancer is the leading female cancer in terms of prevalence. Progress in molecular biology has brought forward a better understanding of its pathogenesis that has led to better prognostication and treatment. Subtypes of breast cancer have been identified at the genomic level and guide therapeutic decisions based on their biology and the expected benefit from various interventions. Despite this progress, a significant percentage of patients die from their disease and further improvements are needed. The cancer stem cell theory and the epithelial-mesenchymal transition are two comparatively novel concepts that have been introduced in the area of cancer research and are actively investigated. Both processes have their physiologic roots in normal development and common mediators have begun to surface. This review discusses the associations of these networks as a prognostic framework in breast cancer.

Repression of CD24 surface protein expression by oncogenic Ras is relieved by inhibition of Raf but not MEK or PI3K

CD24 is a dynamically regulated cell surface protein. High expression of CD24 leads to progression of lung, prostrate, colon, and pancreatic cancers, among others. In contrast, low expression of CD24 leads to cell proliferation and metastasis of breast cancer stem cells (BCSCs). Activating mutations in Ras are found in 30% of all human cancers. Oncogenic Ras constitutively stimulates the Raf, PI3K, and Ral GDS signaling pathways, leading to cellular transformation. Previous studies have shown that expression of oncogenic Ras in breast cancer cells generates CD24⁻ cells from CD24⁺ cells. However, the molecular mechanisms involved in the generation of CD24⁻ cells were not determined. Here, we demonstrate that oncogenic Ras (RasV12) expression suppresses CD24 mRNA, protein, and promoter levels when expressed in NIH/3T3 cells. Furthermore, activation of only the Raf pathway was sufficient to downregulate CD24 mRNA and protein expression to levels similar to those seen in with RasV12 expression. In contrast, activation of the PI3K pathway downregulated mRNA expression with a partial effect on protein expression whereas activation of the RalGDS pathway only partially affected protein expression. Surprisingly, inhibition of MEK with U0126 only partially restored CD24 mRNA expression but not surface protein expression. In contrast, inhibition of Raf with sorafenib did not restore CD24 mRNA expression but significantly increased the proportion of RasV12 cells expressing CD24. Therefore, the Raf pathway is the major repressor of CD24 mRNA and protein expression, with PI3K also able to substantially inhibit CD24 expression. Moreover, these data indicate that the levels of CD24 mRNA and surface protein are independently regulated. Although inhibition of Raf by sorafenib only partially restored CD24 expression, sorafenib should still be considered as a potential therapeutic strategy to alter CD24 expression in CD24⁻ cells, such as BCSCs.

Epithelial-mesenchymal transition and drug resistance in breast cancer (Review)

Breast cancer is the leading cause of cancer death in women worldwide. Insensitivity of tumor cells to drug therapies is an essential reason arousing such high mortality. Epithelial-mesenchymal transition (EMT) is defined by the loss of epithelial characteristics and the acquisition of a mesenchymal phenotype. It is well known that EMT plays an important role in breast cancer progression. Recently, mounting evidence has demonstrated involvement of EMT in antagonizing chemotherapy in breast cancer. Here, we discuss the biological significance and clinical implications of these findings, with an emphasis on novel approaches that effectively target EMT to increase the efficacy of anticancer therapies.

Implications of Akt2/Twist crosstalk on breast cancer metastatic outcome

Akt2 is a pivotal player in a complex web of signaling pathways controlling cell growth, proliferation, and survival. The deregulation or aberrations of Akt2 have been associated with tumor progression, metastatic spread, and, lastly, chemoresistance. The impairment of its activity has gained more attention because Akt2 is intertwined with a range of signaling paths, including the Phosphatidylinositol 3 kinase/Akt/Mammalian target of rapamycin (PI3K/mTOR) signaling axis, which are involved in macromolecules synthesis and metabolism. Here, we focus on Akt2 because of its involvement in the acquisition of stem cell-like properties, responsible for invasiveness and chemoresistance, also promoted by Twist. We also suggest therapeutic strategies targeting Akt2 to overcome the drawbacks of current cancer therapies.

Mesoporous silica nanoparticle delivery of chemically modified siRNA against TWIST1 leads to reduced tumor burden

Growth and progression of solid tumors depend on the integration of multiple pro-growth and survival signals, including the induction of angiogenesis. TWIST1 is a transcription factor whose reactivation in tumors leads to epithelial to mesenchymal transition (EMT), including increased cancer cell stemness, survival, and invasiveness. Additionally, TWIST1 drives angiogenesis via activation of IL-8 and CCL2, independent of VEGF signaling. In this work, results suggest that chemically modified siRNA against TWIST1 reverses EMT both in vitro and in vivo. siRNA delivery with a polyethyleneimine-coated mesoporous silica nanoparticle (MSN) led to reduction of TWIST1 target genes and migratory potential in vitro. In mice bearing xenograft tumors, weekly intravenous injections of the siRNA-nanoparticle complexes resulted in decreased tumor burden together with a loss of CCL2 suggesting a possible anti-angiogenic response. Therapeutic use of TWIST1 siRNA delivered via MSNs has the potential to inhibit tumor growth and progression in many solid tumor types.

FROM THE CLINICAL EDITOR

Tumor progression and metastasis eventually lead to patient mortality in the clinical setting. In other studies, it has been found that TWIST1, a transcription factor, if reactivated in tumors, would lead to downstream events including angiogenesis and result in poor prognosis in cancer patients. In this article, the authors were able to show that when siRNA against TWIST1 was delivered via mesoporous silica nanoparticle, there was tumor reduction in an in-vivo model. The results have opened up a new avenue for further research in this field.