p63 controls cell migration and invasion by transcriptional regulation of MTSS1

ΔNp63 drives dysplastic alveolar remodeling and restricts epithelial plasticity upon severe lung injury

The lung exhibits a robust, multifaceted regenerative response to severe injuries such as influenza infection, during which quiescent lung-resident epithelial progenitors participate in two distinct reparative pathways: functionally beneficial regeneration via alveolar type 2 (AT2) cell proliferation and differentiation, and dysplastic tissue remodeling via intrapulmonary airway-resident basal p63+ progenitors. Here we show that the basal cell transcription factor ΔNp63 is required for intrapulmonary basal progenitors to participate in dysplastic alveolar remodeling following injury. We find that ΔNp63 restricts the plasticity of intrapulmonary basal progenitors by maintaining either active or repressive histone modifications at key differentiation gene loci. Following loss of ΔNp63, intrapulmonary basal progenitors are capable of either airway or alveolar differentiation depending on their surrounding environment both in vitro and in vivo. Uncovering these regulatory mechanisms of dysplastic repair and lung basal cell fate choice highlight potential therapeutic targets to promote functional alveolar regeneration following severe lung injuries.

Functional antagonism between ΔNp63α and GCM1 regulates human trophoblast stemness and differentiation

The combination of EGF, CHIR99021, A83-01, SB431542, VPA, and Y27632 (EGF/CASVY) facilitates the derivation of trophoblast stem (TS) cells from human blastocysts and first-trimester, but not term, cytotrophoblasts. The mechanism underlying this chemical induction of TS cells remains elusive. Here we demonstrate that the induction efficiency of cytotrophoblast is determined by functional antagonism of the placental transcription factor GCM1 and the stemness regulator ΔNp63α. ΔNp63α reduces GCM1 transcriptional activity, whereas GCM1 inhibits ΔNp63α oligomerization and autoregulation. EGF/CASVY cocktail activates ΔNp63α, thereby partially inhibiting GCM1 activity and reverting term cytotrophoblasts into stem cells. By applying hypoxia condition, we can further reduce GCM1 activity and successfully induce term cytotrophoblasts into TS cells. Consequently, we identify mitochondrial creatine kinase 1 (CKMT1) as a key GCM1 target crucial for syncytiotrophoblast differentiation and reveal decreased CKMT1 expression in preeclampsia. Our study delineates the molecular underpinnings of trophoblast stemness and differentiation and an efficient method to establish TS cells from term placentas.

Trophoblast stem cells can be derived from human blastocysts and first-trimester, but not term, cytotrophoblasts. Here the authors show that induction efficiency of cytotrophoblast is determined by antagonism between GCM1 and ΔNp63α and manipulating this antagonism facilitates derivation of TS cells from term placenta.

ARID2 deficiency promotes tumor progression and is associated with higher sensitivity to chemotherapy in lung cancer

The survival rate in lung cancer remains stubbornly low and there is an urgent need for the identification of new therapeutic targets. In the last decade, several members of the SWI/SNF chromatin remodeling complexes have been described altered in different tumor types. Nevertheless, the precise mechanisms of their impact on cancer progression, as well as the application of this knowledge to cancer patient management are largely unknown. In this study, we performed targeted sequencing of a cohort of lung cancer patients on genes involved in chromatin structure. In addition, we studied at the protein level the expression of these genes in cancer samples and performed functional experiments to identify the molecular mechanisms linking alterations of chromatin remodeling genes and tumor development. Remarkably, we found that 20% of lung cancer patients show ARID2 protein loss, partially explained by the presence of ARID2 mutations. In addition, we showed that ARID2 deficiency provokes profound chromatin structural changes altering cell transcriptional programs, which bolsters the proliferative and metastatic potential of the cells both in vitro and in vivo. Moreover, we demonstrated that ARID2 deficiency impairs DNA repair, enhancing the sensitivity of the cells to DNA-damaging agents. Our findings support that ARID2 is a bona fide tumor suppressor gene in lung cancer that may be exploited therapeutically.

New immunological potential markers for triple negative breast cancer: IL18R1, CD53, TRIM, Jaw1, LTB, PTPRCAP

Breast cancer (BC) is the second leading cause of cancer death in women worldwide, and settings of specific prognostic factors and efficacious therapies are made difficult by phenotypic heterogeneity of BC subtypes. Therefore, there is a current urgent need to define novel predictive genetic predictors that may be useful for stratifying patients with distinct prognostic outcomes. Here, we looked for novel molecular signatures for triple negative breast cancers (TNBCs). By a bioinformatic approach, we identified a panel of genes, whose expression was positively correlated with disease-free survival in TNBC patients, namely IL18R1, CD53, TRIM, Jaw1, LTB, and PTPRCAP, showing specific immune expression profiles linked to survival prediction; most of these genes are indeed expressed in immune cells and are required for productive lymphocyte activation. According to our hypothesis, these genes were not, or poorly, expressed in different TNBC cell lines, derived from either primary breast tumours or metastatic pleural effusions. This conclusion was further supported in vivo, as immuno-histochemical analysis on biopsies of TNBC invasive ductal carcinomas highlighted differential expression of these six genes in cancer cells, as well as in intra- and peri-tumoral infiltrating lymphocytes. Our data open to the possibility that inter-tumour heterogeneity of immune markers might have predictive value; further investigations are recommended in order to establish the real power of cancer-related immune profiles as prognostic factors.

Supercharging BRD4 with NUT in carcinoma

NUT carcinoma (NC) is an extremely aggressive squamous cancer with no effective therapy. NC is driven, most commonly, by the BRD4-NUT fusion oncoprotein. BRD4-NUT combines the chromatin-binding bromo- and extraterminal domain-containing (BET) protein, BRD4, with an unstructured, poorly understood protein, NUT, which recruits and activates the histone acetyltransferase p300. Recruitment of p300 to chromatin by BRD4 is believed to lead to the formation of hyperacetylated nuclear foci, as seen by immunofluorescence. BRD4-NUT nuclear foci correspond with massive contiguous regions of chromatin co-enriched with BRD4-NUT, p300, and acetylated histones, termed "megadomains" (MD). Megadomains stretch for as long as 2 MB. Proteomics has defined a BRD4-NUT chromatin complex in which members that associate with BRD4 also exist as rare NUT-fusion partners. This suggests that the common pathogenic denominator is the presence of both BRD4 and NUT, and that the function of BRD4-NUT may mimic that of wild-type BRD4. If so, then MDs may function as massive super-enhancers, activating transcription in a BET-dependent manner. Common targets of MDs across multiple NCs and tissues are three stem cell-related transcription factors frequently implicated in cancer: MYC, SOX2, and TP63. Recently, MDs were found to form a novel nuclear sub-compartment, called subcompartment M (subM), where MD-MD interactions occur both intra- and inter-chromosomally. Included in subM are MYC, SOX2, and TP63. Here we explore the possibility that if MDs are simply large super-enhancers, subM may exist in other cell systems, with broad implications for how 3D organization of the genome may function in gene regulation and maintenance of cell identity. Finally, we discuss how our knowledge of BRD4-NUT function has been leveraged for the therapeutic development of first-in-class BET inhibitors and other targeted strategies.

miRNA-182 regulated MTSS1 inhibits proliferation and invasion in Glioma Cells

Human glioma is the most common malignant and fatal primary tumor in the central nervous system. Currently, the high incidence and low cure rate of glioma make it a considerable threat to human health. Thus, elucidating the molecular mechanisms of glioma development and progression has become a major focus to identify new and effective biomarkers and improve the comprehensive neurosurgical treatment of glioma from the basic research and clinical perspectives. In our present study, we aimed to investigate the expression pattern and biological function of Metastasis suppressor protein 1(MTSS1) in glioma and to further explore whether miRNAs were involved in the deregulation of MTSS1. By overexpressing MTSS1 in highly malignant human glioma cells, we discovered a role for MTSS1 in suppressing the proliferation and invasion of glioma cells, and we showed that MTSS1 participated in transforming growth factor-beta 1 (TGF-β1) -induced epithelial-mesenchymal transition (EMT) in glioma cells. Biochemical analyses suggested that miR-182 may target MTSS1 and that miR-182 expression is negatively correlated with MTSS1 expression in glioma tissues. This finding was further confirmed by luciferase reporter experiments. Furthermore, a miR-182 inhibitor induced glioma cell proliferation and invasion by increasing MTSS1 expression. In conclusion, we believed that miR-182 modulates glioma cell migration and invasion by targeting the MTSS1 and suggested that miR-182 was a potential therapeutic target for gliomas.

Synergetic Effects of Intronic Mature miR-944 and ΔNp63 Isoforms on Tumorigenesis in a Cervical Cancer Cell Line

miR-944 is located in an intron of the tumor protein p63 gene (TP63). miR-944 expression levels in cervical cancer tissues are significantly higher than in normal tissues and are associated with tumor size, International Federation of Gynecology and Obstetrics (FIGO) stage, lymph node metastasis, and survival. However, associations of miR-944 with its host gene, TP63, which encodes TAp63 and ΔNp63, in cervical cancer have not been fully investigated. A positive correlation between miR-944 and ΔNp63 mRNA expression was identified in cervical cancer tissues. Furthermore, when the expression of miR-944 and ΔNp63 was simultaneously inhibited, cell proliferation-, differentiation- epithelial-mesenchymal transition (EMT)-, transcription-, and virus-associated gene clusters were shown to be significantly more active according to functional annotation analysis. Cell viability and migration were more reduced upon simultaneous inhibition with anti-miR-944 or ΔNp63 siRNA than with inhibition with anti-miR-944 or ΔNp63 siRNA alone, or scramble. In addition, Western blot analysis showed that the simultaneous inhibition of miR-944 and ΔNp63 reduced EMT by increasing the expression of epithelial markers such as claudin and by decreasing mesenchymal markers such as N-cadherin and vimentin. Slug, an EMT transcription factor, was also decreased by the simultaneous inhibition of miR-944 and ΔNp63. Thus, associations between miR-944 and ΔNp63 in cervical cancer could help to elucidate the function of this intronic microRNA and its role in carcinogenesis.

p63 at the Crossroads between Stemness and Metastasis in Breast Cancer

After lung cancer, breast cancer (BC) is the most frequent cause of cancer death among women, worldwide. Although advances in screening approaches and targeted therapeutic agents have decreased BC incidence and mortality, over the past five years, triple-negative breast cancer (TNBC) remains the breast cancer subtype that displays the worst prognosis, mainly due to the lack of clinically actionable targets. Genetic and molecular profiling has unveiled the high intrinsic heterogeneity of TNBC, with the basal-like molecular subtypes representing the most diffuse TNBC subtypes, characterized by the expression of basal epithelial markers, such as the transcription factor p63. In this review, we will provide a broad picture on the physiological role of p63, in maintaining the basal epithelial identity, as well as its involvement in breast cancer progression, emphasizing its relevance in tumor cell invasion and stemness.

ΔNp63 in squamous cell carcinoma: defining the oncogenic routes affecting epigenetic landscape and tumour microenvironment

Squamous cell carcinoma (SCC) is a treatment‐refractory tumour which arises from the epithelium of diverse anatomical sites such as oesophagus, head and neck, lung and skin. Accumulating evidence has revealed a number of genomic, clinical and molecular features commonly observed in SCC of distinct origins. Some of these genetic events culminate in fostering the activity of ΔNp63, a potent oncogene which exerts its pro‐tumourigenic effects by regulating specific transcriptional programmes to sustain malignant cell proliferation and survival. In this review, we will describe the genetic and epigenetic determinants underlying ΔNp63 oncogenic activities in SCC, and discuss some relevant transcriptional effectors of ΔNp63, emphasizing their impact in modulating the crosstalk between tumour cells and tumour microenvironment (TME).

Atypical GATA transcription factor TRPS1 represses gene expression by recruiting CHD4/NuRD(MTA2) and suppresses cell migration and invasion by repressing TP63 expression

Transcriptional repressor GATA binding 1 (TRPS1), an atypical GATA transcription factor, functions as a transcriptional repressor and is also implicated in human cancers. However, the underlying mechanism of TRPS1 contributing to malignancy remains obscure. In the current study, we report that TRPS1 recognizes both gene proximal and distal transcription start site (TSS) sequences to repress gene expression. Co-IP mass spectrometry and biochemical studies showed that TRPS1 binds to CHD4/NuRD(MTA2). Genome-wide and molecular studies revealed that CHD4/NuRD(MTA2) is required for TRPS1 transcriptional repression. Mechanically, TRPS1 and CHD4/NuRD(MTA2) form precision-guided transcriptional repression machinery in which TRPS1 guides the machinery to specific target sites by recognizing GATA elements, and CHD4/NuRD(MTA2) represses the transcription of target genes. Furthermore, TP63 was identified and validated to be a direct target of TRPS1-CHD4/NuRD(MTA2) complex, which represses TP63 expression by involving decommission of TP63 enhancer in the described precision-guided manner, leading to a reduction of the ΔNp63 level and contributing to migration and invasion of cancer cells.

Biological functions and clinical significance of the newly identified long non‑coding RNA RP1‑85F18.6 in colorectal cancer

The biological functions of long non‑coding RNAs (lncRNAs) in cancer have not been fully elucidated. The present study demonstrated that the expression of a newly identified lncRNA, RP1‑85F18.6, was upregulated in colorectal cancer (CRC) tissues and cell lines. Knockdown of lncRNA RP1‑85F18.6 served a key role in tumor inhibition, reduced cell proliferation and invasion, disrupted the cell cycle, and increased apoptosis and pyroptosis of CRC cells. Conversely, overexpression of lncRNA RP1‑85F18.6 exerted the opposite effects. Furthermore, silencing lncRNA RP1‑85F18.6 decreased ΔNp63 expression at both the mRNA and protein levels. Furthermore, co‑transfection with ΔNp63 siRNA and lncRNA RP1‑85F18.6‑expressing vector attenuated the tumor‑promoting effects of lncRNA RP1‑85F18.6 overexpression. The expression levels of lncRNA RP1‑85F18.6, ΔNp63 and gasdermin D (GSDMD) were revealed to be associated with lymph node and distant metastases in patients with CRC, and therefore may serve as predictors in CRC. The findings of the present study suggested that lncRNA RP1‑85F18.6 may trigger CRC cell proliferation, invasion and cell cycle disruption, and suppress apoptosis and pyroptosis of CRC cells through regulating ΔNp63 expression. Therefore, lncRNA RP1‑85F18.6 and ΔNp63 may be considered unfavorable biomarkers, whereas GSDMD may be a favorable biomarker in CRC; these markers may prove valuable in the future diagnosis and prognosis of CRC.

ΔNp63 regulates the expression of hyaluronic acid-related genes in breast cancer cells

Triple negative breast cancers (TNBC) represent the most aggressive and clinically relevant breast carcinomas. On the basis of specific molecular signature, the majority of TNBC can be classified as basal-like breast carcinoma. Here, we report data showing that in basal-like breast carcinoma cells ΔNp63 is capable of sustaining the production of the hyaluronic acid (HA), one of the major component of the extracellular matrix (ECM). At molecular level, we found that ΔNp63 regulates the expression of HA-related genes, such as the HA synthase HAS3, the hyaluronidase HYAL-1 and CD44, the major HA cell membrane receptor. By controlling this pathway, ∆Np63 contributes to maintain the self-renewal of breast cancer stem cells. Importantly, high HAS3 expression is a negative prognostic factor of TNBC patients. Our data suggest that in basal-type breast carcinoma ∆Np63 might favor a HA-rich microenviroment, which can sustain tumor proliferation and stemness.

The miR-124-p63 feedback loop modulates colorectal cancer growth

Among the diverse co-regulatory relationships between transcription factors (TFs) and microRNAs (miRNAs), feedback loops have received the most extensive research attention. The co-regulation of TFs and miRNAs plays an important role in colorectal cancer (CRC) growth. Here, we show that miR-124 can regulate two isoforms of p63, TAp63 and ΔNp63, via iASPP, while p63 modulates signal transducers and activators of transcription 1 (STAT1) expression by targeting miR-155. Moreover, STAT1 acts as a regulator of CRC growth by targeting miR-124. Taken together, these results reveal a feedback loop between miRNAs and TFs. This feedback loop comprises miR-124, iASPP, STAT1, miR-155, TAp63 and ΔNp63, which are essential for CRC growth. Moreover, this feedback loop is perturbed in human colon carcinomas, which suggests that the manipulation of this microRNA-TF feedback loop has therapeutic potential for CRC.

MTSS1 and SCAMP1 cooperate to prevent invasion in breast cancer

Cell-cell adhesions constitute the structural "glue" that retains cells together and contributes to tissue organisation and physiological function. The integrity of these structures is regulated by extracellular and intracellular signals and pathways that act on the functional units of cell adhesion such as the cell adhesion molecules/adhesion receptors, the extracellular matrix (ECM) proteins and the cytoplasmic plaque/peripheral membrane proteins. In advanced cancer, these regulatory pathways are dysregulated and lead to cell-cell adhesion disassembly, increased invasion and metastasis. The Metastasis suppressor protein 1 (MTSS1) plays a key role in the maintenance of cell-cell adhesions and its loss correlates with tumour progression in a variety of cancers. However, the mechanisms that regulate its function are not well-known. Using a system biology approach, we unravelled potential interacting partners of MTSS1. We found that the secretory carrier-associated membrane protein 1 (SCAMP1), a molecule involved in post-Golgi recycling pathways and in endosome cell membrane recycling, enhances Mtss1 anti-invasive function in HER2+/ER-/PR- breast cancer, by promoting its protein trafficking leading to elevated levels of RAC1-GTP and increased cell-cell adhesions. This was clinically tested in HER2 breast cancer tissue and shown that loss of MTSS1 and SCAMP1 correlates with reduced disease-specific survival. In summary, we provide evidence of the cooperative roles of MTSS1 and SCAMP1 in preventing HER2+/ER-/PR- breast cancer invasion and we show that the loss of Mtss1 and Scamp1 results in a more aggressive cancer cell phenotype.

p63 isoforms in triple-negative breast cancer: ΔNp63 associates with the basal phenotype whereas TAp63 associates with androgen receptor, lack of BRCA mutation, PTEN and improved survival

The TP63 gene encodes two major protein variants that differ in their N-terminal sequences and have opposing effects. In breast, ΔNp63 is expressed by immature stem/progenitor cells and mature myoepithelial/basal cells and is a characteristic feature of basal-like triple-negative breast cancers (TNBCs). The expression and potential role of TAp63 in the mammary gland and breast cancers is less clear, partly due to the lack of studies that employ p63 isoform-specific antibodies. We used immunohistochemistry with ΔNp63-specific or TAp63-specific monoclonal antibodies to investigate p63 isoforms in 236 TNBCs. TAp63, but not ΔNp63, was seen in tumour-associated lymphocytes and other stromal cells. Tumour cells showed nuclear staining for ΔNp63 in 17% of TNBCs compared to 7.3% that were positive for TAp63. Whilst most TAp63⁺ tumours also contained ΔNp63⁺ cells, the levels of the two isoforms were independent of each other. ΔNp63 associated with metaplastic and medullary cancers, and with a basal phenotype, whereas TAp63 associated with androgen receptor, BRCA1/2 wild-type status and PTEN positivity. Despite the proposed effects of p63 on proliferation, Ki67 did not correlate with either p63 isoform, nor did they associate with p53 mutation status. ΔNp63 showed no association with patient outcomes, whereas TAp63⁺ patients showed fewer recurrences and improved overall survival. These findings indicate that both major p63 protein isoforms are expressed in TNBCs with different tumour characteristics, indicating distinct functional activities of p63 variants in breast cancer. Analysis of individual p63 isoforms provides additional information into TNBC biology, with TAp63 expression indicating improved prognosis.

ΔNp63 drives metastasis in breast cancer cells via PI3K/CD44v6 axis

P63 is a transcription factor belonging to the family of p53, essential for the development and differentiation of epithelia. In recent years, it has become clear that altered expression of the different isoforms of this gene can play an important role in carcinogenesis. The p63 gene encodes for two main isoforms known as TA and ΔN p63 with different functions. The role of these different isoforms in sustaining tumor progression and metastatic spreading however has not entirely been clarified. Here we show that breast cancer initiating cells express ΔNp63 isoform that supports a more mesenchymal phenotype associated with a higher tumorigenic and metastatic potential. On the contrary, the majority of cells within the tumor appears to express predominantly TAp63 isoform. While ΔNp63 exerts its effects by regulating a PI3K/CD44v6 pathway, TAp63 modulates this pathway in an opposite fashion. As a result, tumorigenicity and invasive capacity of breast cancer cells is a balance of the two isoforms. Finally, we found that tumor microenvironmental cytokines significantly contribute to the establishment of breast cancer cell phenotype by positively regulating ΔNp63 and CD44v6 expression.

Setdb1, a novel interactor of ΔNp63, is involved in breast tumorigenesis

ΔNp63 has been recently involved in self-renewal potential of breast cancer stem cells. Although the p63 transcriptional profile has been extensively characterized, our knowledge of the p63-binding partners potentially involved in the regulation of breast tumour progression is limited. Here, we performed the yeast two hybrid approach to identify p63α interactors involved in breast tumorigenesis and we found that SETDB1, a histone lysine methyl transferases, interacts with ΔNp63α and that this interaction contributes to p63 protein stability. SETDB1 is often amplified in primary breast tumours, and its depletion confers to breast cancer cells growth disadvantage. We identified a list of thirty genes repressed by ΔNp63 in a SETDB1-dependent manner, whose expression is positively correlated to survival of breast cancer patients. These results suggest that p63 and SETDB1 expression, together with the repressed genes, may have diagnostic and prognostic potential.

miR-96 promotes breast cancer metastasis by suppressing MTSS1

Novel, non-invasive biomarkers with high sensitivity and specificity are critical for breast cancer treatment, and prognosis. MicroRNA (miR)-96 has been demonstrated to be highly expressed in several solid malignancies, including breast cancer. However, its expression and function in the metastasis and prognosis of breast cancer have not been fully explored, and its regulation mechanisms remain unclear. In the present study, the serum miR-96 expression in healthy controls, benign and malignant breast cancer types was compared by using reverse transcription-quantitative polymerase chain reaction. The effect of chemotherapy on miR-96 expression in breast cancer was also investigated. Result revealed that miR-96 expression was increased in malignant breast cancer types and reduced in patients following chemotherapy treatment. The effect of miR-96 manipulation on the migration of breast cancer cells was also investigated by using wound healing, and Transwell migration assays. These results revealed that the induced expression of miR96 led to enhanced wound closing and trans-membrane cell numbers. By using bioinformatics analysis, western blotting and immunohistochemical staining, the metastasis suppressor-1 (MTSS1) gene was identified to be the functional target of miR-96 in the promotion of cell migration. In conclusion, it was identified that miR-96 exhibited an increased level in serum samples of patients with malignant breast cancer in comparison with benign breast tumor types and health controls and may be substantially reduced by chemotherapy treatment, implying that it may be used as a prognostic marker in breast cancer. miR-96 overexpression may inhibit migration of breast cancer cells by downregulating MTSS1 expression.

Metabolic pathways regulated by TAp73 in response to oxidative stress

Reactive oxygen species are involved in both physiological and pathological processes including neurodegeneration and cancer. Therefore, cells have developed scavenging mechanisms to maintain redox homeostasis under control. Tumor suppressor genes play a critical role in the regulation of antioxidant genes. Here, we investigated whether the tumor suppressor gene TAp73 is involved in the regulation of metabolic adaptations triggered in response to oxidative stress. H₂O₂ treatment resulted in numerous biochemical changes in both control and TAp73 knockout (TAp73−/−) mouse embryonic fibroblasts, however the extent of these changes was more pronounced in TAp73−/− cells when compared to control cells. In particular, loss of TAp73 led to alterations in glucose, nucleotide and amino acid metabolism. In addition, H₂O₂ treatment resulted in increased pentose phosphate pathway (PPP) activity in null mouse embryonic fibroblasts. Overall, our results suggest that in the absence of TAp73, H₂O₂ treatment results in an enhanced oxidative environment, and at the same time in an increased pro-anabolic phenotype. In conclusion, the metabolic profile observed reinforces the role of TAp73 as tumor suppressor and indicates that TAp73 exerts this function, at least partially, by regulation of cellular metabolism.

ΔNp63-mediated regulation of hyaluronic acid metabolism and signaling supports HNSCC tumorigenesis

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide, and several molecular pathways that underlie the molecular tumorigenesis of HNSCC have been identified. Among them, amplification or overexpression of ΔNp63 isoforms is observed in the majority of HNSCCs. Here, we unveiled a ΔNp63-dependent transcriptional program able to regulate the metabolism and the signaling of hyaluronic acid (HA), the major component of the extracellular matrix (ECM). We found that ∆Np63 is capable of sustaining the production of HA levels in cell culture and in vivo by regulating the expression of the HA synthase HAS3 and two hyaluronidase genes, HYAL-1 and HYAL-3. In addition, ∆Np63 directly regulates the expression of CD44, the major HA cell membrane receptor. By controlling this transcriptional program, ∆Np63 sustains the epithelial growth factor receptor (EGF-R) activation and the expression of ABCC1 multidrug transporter gene, thus contributing to tumor cell proliferation and chemoresistance. Importantly, p63 expression is positively correlated with CD44, HAS3, and ABCC1 expression in squamous cell carcinoma datasets and p63-HA pathway is a negative prognostic factor of HNSCC patient survival. Altogether, our data shed light on a ∆Np63-dependent pathway functionally important to the regulation of HNSCC progression.

ΔNp63α induces the expression of FAT2 and Slug to promote tumor invasion

Tumor invasion can be induced by changes in gene expression that alter cell phenotype. The transcription factor ΔNp63α promotes basal-like breast cancer (BLBC) migration by inducing the expression of the mesenchymal genes Slug and Axl, which confers cells with a hybrid epithelial/mesenchymal state. However, the extent of the ΔNp63α regulated genes that support invasive behavior is not known. Here, using gene expression analysis, ChIP-seq, and functional testing, we find that ΔNp63α promotes BLBC motility by inducing the expression of the atypical cadherin FAT2, the vesicular binding protein SNCA, the carbonic anhydrase CA12, the lipid binding protein CPNE8 and the kinase NEK1, along with Slug and Axl. Notably, lung squamous cell carcinoma migration also required ΔNp63α dependent FAT2 and Slug expression, demonstrating that ΔNp63α promotes migration in multiple tumor types by inducing mesenchymal and non-mesenchymal genes. ΔNp63α activation of FAT2 and Slug influenced E-cadherin localization to cell-cell contacts, which can restrict spontaneous cell movement. Moreover, live-imaging of spheroids in organotypic culture demonstrated that ΔNp63α, FAT2 and Slug were essential for the extension of cellular protrusions that initiate collective invasion. Importantly, ΔNp63α is co-expressed with FAT2 and Slug in patient tumors and the elevated expression of ΔNp63α, FAT2 and Slug correlated with poor patient outcome. Together, these results reveal how ΔNp63α promotes cell migration by directly inducing the expression of a cohort of genes with distinct cellular functions and suggest that FAT2 is a new regulator of collective invasion that may influence patient outcome.

TAp73 inhibits cell invasion and migration by directly activating KAI1 expression in colorectal carcinoma

p73 is a member of the p53 family of transcription factors and, like p53, plays a role as a tumor suppressor. p73 is involved in development, proliferation, apoptosis and metastasis. However, the precise molecular mechanisms underlying its function in inhibiting metastasis remain largely unknown. Here, we show that induction of TAp73 decreased invasion and migration activity of colorectal cancer cells, whereas knockdown of TAp73 led to increased invasion and migration activity. KAI1 was identified as a transcriptional target of TAp73 and its expression is indispensable for TAp73-mediated inhibition of cell invasion and migration. Furthermore, induction of TAp73 in colorectal cancer cells elevated KAI1 expression and decreased the frequency of hepatic metastasis in vivo. Whereas, the decreased invasion and migration activities caused by TAp73 induction were abrogated by knockdown of KAI1. Interestingly, TAp73 and KAI1 are overexpressed in primary colorectal cancers and a significant correlation between TAp73 and KAI1 expression was detected, but their expressions were significantly down-regulated in metastatic cancers. Taken together, our results support a novel role for TAp73 in controlling colorectal cancer cell invasion, migration and metastasis by regulating transcription of KAI1.

Molecular determinants of prostate cancer metastasis

Metastatic cancer remains largely incurable and fatal. The general course of cancer, from the initiation of primary tumor formation and progression to metastasis, is a multistep process wherein tumor cells at each step must display specific phenotypic features. Distinctive capabilities required for primary tumor initiation and growth form the foundation, and sometimes may remain critical, for subsequent metastases. These phenotypic features must remain easily malleable during the acquisition of additional capabilities unique and essential to the metastatic process such as dissemination to distant tissues wherein tumor cells interact with foreign microenvironments. Thus, the metastatic phenotype is a culmination of multiple genetic and epigenetic alterations and subsequent selection for favorable traits under the pressure of ever-changing tumor microenvironments. Although our understanding of the molecular programs that drive cancer metastasis are incomplete, increasing evidence suggests that successful metastatic colonization relies on the dissemination of cancer stem cells (CSCs) with tumor-regenerating capacity and adaptive programs for survival in distant organs. In the past 2-3 years, a myriad of novel molecular regulators and determinants of prostate cancer metastasis have been reported, and in this Perspective, we comprehensively review this body of literature and summarize recent findings regarding cell autonomous molecular mechanisms critical for prostate cancer metastasis.

Comprehensive circular RNA profiling reveals the regulatory role of the circRNA-100338/miR-141-3p pathway in hepatitis B-related hepatocellular carcinoma

Circular RNAs (circRNAs) represent a class of endogenous noncoding RNAs that have recently been recognized as important regulators of gene expression and pathological networks. However, their transcriptional activities and functional mechanisms in cancer remain largely unknown. Here, we present results from a global circRNA expression and functional analysis of patients with hepatocellular carcinoma (HCC). Using a circRNA microarray, we identified 226 differentially expressed circRNAs, of which 189 were significantly upregulated and 37 were downregulated. High expression of circRNA_100338, one of the upregulated circRNAs in HCC, is closely correlated with a low cumulative survival rate and metastatic progression in HCC patients with hepatitis B. Furthermore, our in silico and experimental analyses identified miR-141-3p as a direct target of circRNA_100338. Thus, circRNA_100338 functions as an endogenous sponge for miR-141-3p in HCC. In addition, we identified the crucial antagonistic roles of circRNA_100338 and miR-141-3p in the regulation of invasive potential in liver cancer cells. Overall, the differential expression of multiple circRNAs in HCC tissues and their clinical significance in hepatitis B-related HCC patients as revealed by our study suggests that circRNA_100338 is a potentially valuable biomarker for HCC diagnosis and target for HCC therapeutics.

Ultraconserved long non-coding RNA uc.63 in breast cancer

Transcribed-ultraconserved regions (T-UCRs) are long non-coding RNAs (lncRNA) encoded by a subset of long ultraconserved stretches in the human genome. Recent studies revealed that the expression of several T-UCRs is altered in cancer and growing evidences underline the importance of T-UCRs in oncogenesis, offering also potential new strategies for diagnosis and prognosis. We found that overexpression of one specific T-UCRs named uc.63 is associated with bad outcome in luminal A subtype of breast cancer patients. uc.63 is localized in the third intron of exportin-1 gene (XPO1) and is transcribed in the same orientation of its host gene. Interestingly, silencing of uc.63 induces apoptosis in vitro. However, silencing of host gene XPO1 does not cause the same effect suggesting that the transcription of uc.63 is independent of XPO1. Our results reveal an important role of uc.63 in promoting breast cancer cells survival and offer the prospect to identify a signature associated with poor prognosis.

Repression of Wnt/β-catenin response elements by p63 (TP63)

Submitted: TP63 (p63), a member of the tumor suppressor TP53 (p53) gene family, is expressed in keratinocyte stem cells and well-differentiated squamous cell carcinomas to maintain cellular potential for growth and differentiation. Controversially, activation of the Wnt/β-catenin signaling by p63 (Patturajan M. et al., 2002, Cancer Cells) and inhibition of the target gene expression (Drewelus I. et al., 2010, Cell Cycle) have been reported. Upon p63 RNA-silencing in squamous cell carcinoma (SCC) lines, a few Wnt target gene expression substantially increased, while several target genes moderately decreased. Although ΔNp63α, the most abundant isoform of p63, appeared to interact with protein phosphatase PP2A, neither GSK-3β phosphorylation nor β-catenin nuclear localization was altered by the loss of p63. As reported earlier, ΔNp63α enhanced β-catenin-dependent luc gene expression from pGL3-OT having 3 artificial Wnt response elements (WREs). However, this activation was detectable only in HEK293 cells examined so far, and involved a p53 family-related sequence 5' to the WREs. In Wnt3-expressing SAOS-2 cells, ΔNp63α rather strongly inhibited transcription of pGL3-OT. Importantly, ΔNp63α repressed WREs isolated from the regulatory regions of MMP7. ΔNp63α-TCF4 association occurred in their soluble forms in the nucleus. Furthermore, p63 and TCF4 coexisted at a WRE of MMP7 on the chromatin, where β-catenin recruitment was attenuated. The combined results indicate that ΔNp63α serves as a repressor that regulates β-catenin-mediated gene expression.

Overexpression of maelstrom promotes bladder urothelial carcinoma cell aggressiveness by epigenetically downregulating MTSS1 through DNMT3B

We have recently identified and characterized a novel oncogene, maelstrom (MAEL) from 1q24, in the pathogenesis of hepatocellular carcinoma. In this study, MAEL was investigated for its oncogenic role in urothelial carcinoma of the bladder (UCB) tumorigenesis/aggressiveness and underlying molecular mechanisms. Here, we report that overexpression of MAEL in UCB is important in the acquisition of an aggressive and/or poor prognostic phenotype. In UCB cell lines, knockdown of MAEL by short hairpin RNA is sufficient to inhibit cell growth, invasiveness/metastasis and suppressed epithelial-mesenchymal transition (EMT), whereas ectopic overexpression of MAEL promoted cell growth, invasive and/or metastatic capacity and enhanced EMT both in vitro and in vivo. We further demonstrate that MAEL could induce UCB cell EMT by downregulating a critical downstream target, the metastasis suppressor 1 (MTSS1) gene, ultimately leading to an increased invasiveness of cancer cells. Notably, overexpression of MAEL in UCB cells substantially enhanced the enrichment of DNA methyltrans-ferase (DNMT)3B and histone deacetylase (HDAC)1/2 on the promoter of the MTSS1, and thereby epigenetically suppressing the MTSS1 transcription. Downregulation of MTSS1 by MAEL in UCB cells is partially dependent on DNMT3B. Furthermore, we identify that beside the gene amplification of MAEL, miR-186 is a key negative regulator of MAEL and downregulation of miR-186 is another important mechanism for MAEL overexpression in UCBs. These data suggest that overexpression of MAEL, caused by gene amplification and/or decreased miR-186, has a critical oncogenic role in UCB pathogenesis by downregulation of MTSS1, and MAEL could be used as a novel prognostic marker and/or effective therapeutic target for human UCB.

Understanding the biology of urothelial cancer metastasis

Management of unresectable urothelial cancer (UC) has been a clinical challenge for decades. While drug resistance is a key issue, precise understanding of biology of UC metastasis is another challenge for the improvement of treatment outcome of UC patients. Introduction of the cell biology concepts including epithelial-mesenchymal transition (EMT) and cancer stemness seems to explain UC metastasis. Molecular genetics based on gene expression profiling, next generation sequencing, and explosion of non-coding RNA world has opened the door to intrinsic molecular subtyping of UC. Next steps include, based on the recently accumulated understanding, the establishment of novel disease models representing UC metastasis in various experimental platforms, particularly in vivo animal systems. Indeed, novel knowledge molecular genetics has not been fully linked to the modeling of UC metastasis. Further understanding of bladder carcinogenesis is needed particularly with regard to cell of origin related to tumor characteristics including driver gene alterations, pathological differentiations, and metastatic ability. Then we will be able to establish better disease models, which will consequently lead us to further understanding of biology and eventually the development of novel therapeutic strategies for UC metastasis.

Downregulation of CXCL12 in mesenchymal stromal cells by TGFβ promotes breast cancer metastasis

Mesenchymal stromal cells (MSCs) are one of major components of the tumour microenvironment. Recent studies have shown that MSC tumour residence and their close interactions with inflammatory factors are important factors that affect tumour progression. Among tumour-associated inflammatory factors, transforming growth factor β (TGFβ) is regarded as a key determinant of malignancy. By employing a lung metastasis model of a murine breast cancer, we show here that the prometastatic effect of MSCs was dependent on their response to TGFβ. Interestingly, we found that MSC-produced CXCL12, an important chemokine in tumour metastasis, was markedly inhibited by TGFβ. Furthermore, silencing of CXCL12 in TGFβ-unresponsive MSCs restored their ability to promote tumour metastasis. We found that 4T1 breast cancer cells expressed high levels of CXCR7, but not of CXCR4, both of which are CXCL12 receptors. In presence of CXCL12, CXCR7 expression on tumour cells was decreased. Indeed, when CXCR7 was silenced in breast cancer cells, their metastatic ability was inhibited. Therefore, our data demonstrated that sustained expression of CXCL12 by MSCs in the primary tumour site inhibits metastasis through reduction of CXCR7, while, in the presence of TGFβ, this CXCL12 effect of MSCs on tumour cells is relieved. Importantly, elevated CXCR7 and depressed CXCL12 expression levels were prominent features of clinical breast cancer lesions and were related significantly with poor survival. Our findings reveal a novel mechanism of MSC effects on malignant cells through which crosstalk between MSCs and TGFβ regulates tumour metastasis.

TNFα-activated mesenchymal stromal cells promote breast cancer metastasis by recruiting CXCR2+ neutrophils

Mesenchymal stromal cells (MSCs) tend to infiltrate into tumors and form a major component of the tumor microenvironment. Our previous work demonstrated that tumor necrosis factor α (TNFα)-activated MSCs significantly promoted tumor growth. However, the role of TNFα-treated MSCs in tumor metastasis remains elusive. Employing a lung metastasis model of murine breast cancer, we found that TNFα-activated MSCs strikingly enhanced tumor metastasis compared with normal MSCs. We analyzed the chemokine profiles and found that the expression of CCL5, CCR2 and CXCR2 ligands were enhanced in TNFα-activated MSCs. Using genetic or pharmacological strategies to inhibit CCL5 or CCR2, we demonstrated that CCL5 and CCR2 ligands were indispensable in supporting TNFα-activated MSCs to promote tumor metastasis. Analysis of immune cells revealed that CXCR2 ligands (CXCL1, CXCL 2 and CXCL5) expressed by TNFα-activated MSCs efficiently recruited CXCR2⁺ neutrophils into tumor. These neutrophils were responsible for the pro-metastatic effect of MSCs since inhibition of this chemotaxis abolished increased neutrophil recruitment and tumor metastasis. The interaction between neutrophils and tumor cells resulted in markedly elevated metastasis-related genes by tumor cells, including CXCR4, CXCR7, MMP12, MMP13, IL-6 and TGFβ. Importantly, in IL8^high human breast cancer samples, we also observed similar alterations of gene expression. Collectively, our findings demonstrate that TNFα-activated MSCs promote tumor metastasis via CXCR2⁺ neutrophil recruitment.

Elevated MTSS1 expression associated with metastasis and poor prognosis of residual hepatitis B-related hepatocellular carcinoma

Background

Hepatectomy generally offers the best chance of long-term survival for patients with hepatocellular carcinoma (HCC). Many studies have shown that hepatectomy accelerates tumor metastasis, but the mechanism remains unclear.

Methods

An orthotopic nude mice model with palliative HCC hepatectomy was performed in this study. Metastasis-related genes in tumor following resection were screened; HCC invasion, metastasis, and some molecular alterations were examined in vivo and in vitro. Clinical significance of key gene mRNA expression was also analyzed.

Results

Metastasis suppressor 1 (MTSS1) located in the central position of gene function net of residual HCC. MTSS1 was up-regulated in residual tumor after palliative resection. In hepatitis B-related HCC patients undergone palliative hepatectomy, those with higher MTSS1 mRNA expression accompanied by activation of matrix metalloproteinase 2 (MMP2) in residual HCC, had earlier residual HCC detection after hepatectomy and poorer survival when compared to those with lower MTSS1. In different cell lines, the levels of MTSS1 mRNA increased in parallel with metastatic potential. MTSS1 down regulation via siRNA decreased MMP2 activity, reduced invasive potentials of HCC by 28.9 % in vitro, and averted the deteriorated lung metastatic extent in vivo.

Conclusions

The poor prognosis of hepatitis B-related HCC patients following palliative hepatectomy associates with elevated MTSS1 mRNA expression; therefore, MTSS1 may provide a new research field for HCC diagnosis and treatment.

Electronic supplementary material

The online version of this article (doi:10.1186/s13046-016-0361-8) contains supplementary material, which is available to authorized users.

Estrogen Enhances the Cell Viability and Motility of Breast Cancer Cells through the ERα-ΔNp63-Integrin β4 Signaling Pathway

Estrogen induces ERα-positive breast cancer aggressiveness via the promotion of cell proliferation and survival, the epithelial-mesenchymal transition, and stem-like properties. Integrin β4 signaling has been implicated in estrogen/ERα-induced tumorigenicity and anti-apoptosis; however, this signaling cascade poorly understood. ΔNp63, an N-terminally truncated isoform of the p63 transcription factor, functions as a transcription factor of integrinβ4 and therefore regulates cellular adhesion and survival. Therefore, the aim of the present study was to investigate the estrogen-induced interaction between ERα, ΔNp63 and integrin β4 in breast cancer cells. In ERα-positive MCF-7 cells, estrogen activated ERα transcription, which induced ΔNp63 expression. And ΔNp63 subsequently induced integrin β4 expression, which resulted in AKT phosphorylation and enhanced cell viability and motility. Conversely, there was no inductive effect of estrogen on ΔNp63-integrinβ4-AKT signaling or on cell viability and motility in ERα-negative MDA-MB-231 cells. ΔNp63 knockdown abolishes these estrogen-induced effects and reduces cell viability and motility in MCF-7 cells. Nevertheless, ΔNp63 knockdown also inhibited cell migration in MDA-MB-231 cells through reducing integrin β4 expression and AKT phosphorylation. In conclusion, estrogen enhances ERα-positive breast cancer cell viability and motility through activating the ERα-ΔNp63-integrin β4 signaling pathway to induce AKT phosphorylated activation. Those findings should be useful to elucidate the crosstalk between estrogen/ER signaling and ΔNp63 signaling and provide novel insights into the effects of estrogen on breast cancer progression.

p63 supports aerobic respiration through hexokinase II

Short p63 isoform, ΔNp63, is crucial for epidermis formation, and it plays a pivotal role in controlling the turnover of basal keratinocytes by regulating the expression of a subset of genes involved in cell cycle and cell adhesion programs. The glycolytic enzyme hexokinase 2 (HK2) represents the first step of glucose utilization in cells. The family of HKs has four isoforms that differ mainly in their tissue and subcellular distribution. The preferential mitochondrial localization of HK2 at voltage-dependent anion channels provides access to ATP generated by oxidative phosphorylation and generates an ADP/ATP recycling mechanism to maintain high respiration rates and low electron leak. Here, we report that ΔNp63 depletion in human keratinocytes impairs mitochondrial basal respiration and increases mitochondrial membrane polarization and intracellular reactive oxygen species. We show ΔNp63-dependent regulation of HK2 expression, and we use ChIP, validated by p63-Chip sequencing genomewide profiling analysis, and luciferase assays to demonstrate the presence of one p63-specific responsive element within the 15th intronic region of the HK2 gene, providing evidence of a direct interaction. Our data support the notion of ΔNp63 as a master regulator in epithelial cells of a combined subset of molecular mechanisms, including cellular energy metabolism and respiration. The ΔNp63-HK2 axis is also present in epithelial cancer cells, suggesting that ΔNp63 could participate in cancer metabolic reprogramming.