TMEPAI/PMEPA1 inhibits Wnt signaling by regulating β-catenin stability and nuclear accumulation in triple negative breast cancer cells

Prostate transmembrane androgen inducible protein 1 (PMEPA1): regulation and clinical implications

Prostate transmembrane androgen inducible protein 1 (PMEPA1) can promote or inhibit prostate cancer cell growth based on the cancer cell response to the androgen receptor (AR). Further, it can be upregulated by transforming growth factor (TGF), which downregulates transforming growth factor-β (TGF-β) signaling by interfering with R-Smad phosphorylation to facilitate TGF-β receptor degradation. Studies have indicated the increased expression of PMEPA1 in some solid tumors and its functioning as a regulator of multiple signaling pathways. This review highlights the multiple potential signaling pathways associated with PMEPA1 and the role of the PMEPA1 gene in regulating prognosis, including transcriptional regulation and epithelial mesenchymal transition (EMT). Moreover, the relevant implications in and outside tumors, for example, as a biomarker and its potential functions in lysosomes have also been discussed.

New insight in urological cancer therapy: From epithelial-mesenchymal transition (EMT) to application of nano-biomaterials

A high number of cancer-related deaths (up to 90) are due to metastasis and simple definition of metastasis is new colony formation of tumor cells in a secondary site. In tumor cells, epithelial-mesenchymal transition (EMT) stimulates metastasis and invasion, and it is a common characteristic of malignant tumors. Prostate cancer, bladder cancer and renal cancer are three main types of urological tumors that their malignant and aggressive behaviors are due to abnormal proliferation and metastasis. EMT has been well-documented as a mechanism for promoting invasion of tumor cells and in the current review, a special attention is directed towards understanding role of EMT in malignancy, metastasis and therapy response of urological cancers. The invasion and metastatic characteristics of urological tumors enhance due to EMT induction and this is essential for ensuring survival and ability in developing new colonies in neighboring and distant tissues and organs. When EMT induction occurs, malignant behavior of tumor cells enhances and their tend in developing therapy resistance especially chemoresistance promotes that is one of the underlying reasons for therapy failure and patient death. The lncRNAs, microRNAs, eIF5A2, Notch-4 and hypoxia are among common modulators of EMT mechanism in urological tumors. Moreover, anti-tumor compounds such as metformin can be utilized in suppressing malignancy of urological tumors. Besides, genes and epigenetic factors modulating EMT mechanism can be therapeutically targeted for interfering malignancy of urological tumors. Nanomaterials are new emerging agents in urological cancer therapy that they can improve potential of current therapeutics by their targeted delivery to tumor site. The important hallmarks of urological cancers including growth, invasion and angiogenesis can be suppressed by cargo-loaded nanomaterials. Moreover, nanomaterials can improve chemotherapy potential in urological cancer elimination and by providing phototherapy, they mediate synergistic tumor suppression. The clinical application depends on development of biocompatible nanomaterials.

AGO-RBP crosstalk on target mRNAs: Implications in miRNA-guided gene silencing and cancer

MicroRNAs (miRNAs) and RNA-binding proteins (RBPs) are important regulators of mRNA translation and stability in eukaryotes. While miRNAs can only bind their target mRNAs in association with Argonaute proteins (AGOs), RBPs directly bind their targets either as single entities or in complex with other RBPs to control mRNA metabolism. miRNA binding in 3' untranslated regions (3' UTRs) of mRNAs facilitates an intricate network of interactions between miRNA-AGO and RBPs, thus determining the fate of overlapping targets. Here, we review the current knowledge on the interplay between miRNA-AGO and multiple RBPs in different cellular contexts, the rules underlying their synergism and antagonism on target mRNAs, as well as highlight the implications of these regulatory modules in cancer initiation and progression.

Target Protein for Xklp2 Functions as Coactivator of Androgen Receptor and Promotes the Proliferation of Prostate Carcinoma Cells

The activation of the androgen receptor (AR) pathway is crucial in the progression of human prostate cancer. Results of the present study indicated that the target protein xenopus kinesin-like protein (TPX2) enhanced the transcription activation of AR and promoted the proliferation of LNCaP (ligand-dependent prostate carcinoma) cells. The protein-protein interaction between AR and TPX2 was investigated using coimmunoprecipitation assays. Results of the present study further demonstrated that TPX2 enhanced the transcription factor activation of AR and enhanced the expression levels of the downstream gene prostate-specific antigen (PSA). TPX2 did this by promoting the accumulation of AR in the nucleus and also promoting the recruitment of AR to the androgen response element, located in the promoter region of the PSA gene. Overexpression of TPX2 enhanced both the in vitro and in vivo proliferation of LNCaP cells. By revealing a novel role of TPX2 in the AR signaling pathway, the present study indicated that TPX2 may be an activator of AR and thus exhibits potential as a novel target for prostate carcinoma treatment.

PMEPA1 interference activates PTEN/PI3K/AKT, thereby inhibiting the proliferation, invasion and migration of pancreatic cancer cells and enhancing the sensitivity to gemcitabine and cisplatin

To explore the biological activity of transmembrane prostateandrogen induced RNA (PMEPA1) in human pancreatic cancer (hPAC) cells and its drug sensitivity to gemcitabine (GEM) and cisplatin (DDP). Gene Expression Profiling Interactive Analysis (GEPIA) and Cancer Cell Line Encyclopedia (CCLE) were consulted to indicate the expression of PMEPA1 in hPAC tissues and cells. Quantitative real-time PCR (RT-qPCR) and western blot were performed to verify the indication. RT-qPCR and western blot also detected the expressions of PTEN/PI3K/AKT before and after transfection of PMEPA1 siRNA plasmids. Cell counting Kit-8 (CCK-8) and EdU staining were performed to examine cell proliferation before and after transfection of phosphatase and tensin homologue delet2ed on chromosome ten (PTEN) siRNA plasmids. Transwell and wound healing detected the invasion and migration of hPAC cells. The expressions of MMP-2 and MMP-9 were detected by western blot. After GEM or DDP treatment, cell viability was observed by commercial kits and cell apoptosis by flow cytometry. GEPIA and CCLE predicted increased expression of PMEPA1 in hPAC tissues and cells, which was confirmed by quantitative reverse transcription polymerase chain reaction (RT-qPCR) and western blot. PMEPA1 was also shown to be associated with disease-free survival. Transfection of PMEPA1 siRNA plasmids affected the expressions of PTEN/PI3K/AKT. PMEPA1 interference inhibited the proliferation, invasion and migration of hPAC cells. Furthermore, PMEPA1 interference also enhanced the sensitivity of hPAC cells to GEM and DDP via PTEN interference. PMEPA1 interference inhibits the proliferation, invasion and migration of pancreatic cancer cells and enhances the sensitivity to GEM and cisplatin by activating PTEN/PI3K/AKT signaling.

The Wnt/β-catenin pathway in breast cancer therapy: a pre-clinical perspective of its targeting for clinical translation

INTRODUCTION

Despite various treatments available, there is still a high mortality rate in breast cancer patients. Thus, there exists an unmet need for new therapeutic interventions. Studies show that the Wnt/β-catenin signaling pathway is involved in breast cancer metastasis because of its transcriptional control on epithelial to mesenchymal transition.

AREAS COVERED

This comprehensive review explores the Wnt signaling pathway as a potential target for treating breast cancer and other breast cancer subtypes. We discuss the Wnt signaling pathway, its role in breast cancer metastasis, and its effect on breast cancer stem cells. Further, endogenous agents that cause Wnt pathway inactivation are outlined. Finally, various natural and chemical compounds modulating the Wnt pathway used in pre-clinical or clinical trials for breast cancer treatment are discussed.

EXPERT OPINION

In vitro and in vivo studies indicate an immense potential of agents targeting the Wnt signaling pathway to prevent and manage breast cancer. Still, more clinical studies are required to support their use in humans. Apart from the agents already in clinical trials, several drug combinations discussed may be translated into clinical practice in a few years.

TGF-β-Induced TMEPAI Promotes Epithelial-Mesenchymal Transition in Doxorubicin-Treated Triple-Negative Breast Cancer Cells via SMAD3 and PI3K/AKT Pathway Alteration

Introduction

Epithelial–mesenchymal transition (EMT) and overexpression of drug efflux transporters have been reported to cause doxorubicin resistance. Our previous study indicated that TMEPAI (transmembrane prostate androgen-induced protein) attenuated doxorubicin sensitivity in triple-negative breast cancer cells. However, how TMEPAI contributes to doxorubicin resistance in TNBC remains unclear. Thus, the present study aimed to elucidate the mechanism of TMEPAI in doxorubicin resistance in triple-negative breast cancer cells.

Methods

We used BT549, triple-negative cells wild type (WT), and BT549 TMEPAI knock-out. Both cells were treated with TGF-β 2 ng/mL for 24 hours, followed by TGF-β 2 ng/mL and doxorubicin 12.9 nM for another 24 hours. Afterward, the cells were harvested and counted. Cells were further lysed and used for RT-PCR and Western blot analysis. We determined the expression levels of proliferation, apoptosis, EMT markers, and drug efflux transporters. Additionally, we investigated the expressions of PI3K as well as SMAD3 and AKT phosphorylation.

Results

TNBC cells were shown to be less sensitive to doxorubicin in the presence of TMEPAI. TMEPAI was shown to alleviate the mRNA expressions of apoptosis markers: Bax, Bcl2, Caspase-3, and Caspase-9. Our results indicated that the presence of TMEPAI greatly amplifies EMT and increases drug efflux transporter expressions after doxorubicin treatment. Furthermore, our findings demonstrated that TMEPAI reduced the action of doxorubicin in inhibiting SMAD3 phosphorylation. TMEPAI was also shown to modify the effect of doxorubicin by reducing PI3K expressions and Akt phosphorylation in triple-negative breast cancer cells.

Conclusion

Our findings indicate that TMEPAI promotes EMT and drug efflux transporters at least in part by shifting doxorubicin action from SMAD3 phosphorylation reduction to PI3K/AKT inhibition in triple-negative breast cancer cells.

PMEPA1 Stimulates the Proliferation, Colony Formation of Pancreatic Cancer Cells via the MAPK Signaling Pathway

BACKGROUND

Prostate transmembrane protein androgen-induced 1 (PMEPA1) is reportedly highly expressed in pancreatic cancer (PC). However, its biological role and associated mechanisms have not been addressed in PC progression.

METHODS

PMEPA1 mRNA expression and survival outcome of PC patients were evaluated via the GEPIA website. Lentiviral-mediated shRNA knockdown and ectopic expression of PMEPA1 were implemented in the pancreatic cancer cell line PANC1 cells. CCK-8 and colony formation assays were carried out to assess the biological function of PMEPA1 in PANC1 proliferation and viability. Dual-luciferase reporter assays and RT-qPCR were used to assess the interactive relationship between PMEPA1 and the MAPK signaling pathway.

RESULTS

By analyzing the data from GEPIA, we found that PMEPA1 mRNA expression is overexpressed in PC tissues compared with matched nontumor tissues. PMEPA1-high PC patients are predicted to have a worse prognosis than PMEPA1-low PC patients. We found that PMEPA1 shRNA suppressed PANC1 proliferation and colony formation capacity, while enforced expression of PMEPA1 yielded the opposite results. Mechanical investigations showed that PMEPA1 exerts its tumor-promoting function in pancreatic cancer via activation of the MAPK signaling pathway.

CONCLUSION

PMEPA1 promotes the progression of PC at least partially by activating the MAPK signaling pathway; thus, the PMEPA1/MAPK axis may be a potential therapeutic target in pancreatic cancer.

CSDE1 attenuates microRNA-mediated silencing of PMEPA1 in melanoma

MicroRNAs and RNA-binding proteins (RBPs) primarily target the 3' UTR of mRNAs to control their translation and stability. However, their co-regulatory effects on specific mRNAs in physiology and disease are yet to be fully explored. CSDE1 is an RBP that promotes metastasis in melanoma and mechanisms underlying its oncogenic activities need to be completely defined. Here we report that CSDE1 interacts with specific miRNA-induced silencing complexes (miRISC) in melanoma. We find an association of CSDE1 with AGO2, the essential component of miRISC, which is facilitated by target mRNAs and depends on the first cold shock domain of CSDE1. Both CSDE1 and AGO2 bind to 3' UTR of PMEPA1. CSDE1 counters AGO2 binding, leading to an increase of PMEPA1 expression. We also identify a miRNA, miR-129-5p, that represses PMEPA1 expression in melanoma. Collectively, our results show that PMEPA1 promotes tumorigenic traits and that CSDE1 along with miR-129-5p/AGO2 miRISC act antagonistically to fine-tune PMEPA1 expression toward the progression of melanoma.

Diagnostic and therapeutic values of PMEPA1 and its correlation with tumor immunity in pan-cancer

AIMS

The prostate transmembrane protein, androgen induced 1 (PMEPA1) is differentially expressed in pan-cancer. However, PMEPA1 specific role in cancers has not been fully clarified. This study aims to explore the potential role of Pmepa1 in pan-cancer and specific cancer, with a view to deepening the research on the pathological mechanism of cancer.

MAIN METHODS

The Perl language and R language were used to identify the correlation between PMEPA1 expression level and clinical indicators, prognosis values, tumor microenvironment, immune cells' infiltration, immune checkpoint genes, TMB and MSI. The Therapeutic Target Database was used for identifying potential therapeutic drugs that target the pathways that are significantly affected by PMEPA1 expression.

KEY FINDINGS

PMEPA1 differential expression significantly correlated with patients' age, race, tumors' stage and status. PMEPA1 high expression was closely correlated with poor prognosis in many cancer types, excluding prostate adenocarcinoma. PMEPA1 expression was closely related to tumor cells and the immune microenvironment in stromal and immune cells' level, immune cells' infiltration, immune checkpoint genes, tumor mutational burden and microsatellite instability. We also found that the activity of the olfactory transduction pathway was closely related to PMEPA1 expression. In pan-cancer, Trifluoperazine and Halofantrine have the potential to reduce PMEPA1 expression.

SIGNIFICANCE

This study integrated existing data to explore PMEPA1 potential function in cancers, provided insights for the future cancer-related studies.

New insights of the correlation between AXIN2 polymorphism and cancer risk and susceptibility: evidence from 72 studies

Background

Numerous studies have reported the correlation between AXIN2 polymorphism and cancer risk, but the results seem not consistent. In order to get an overall, accurate and updated results about AXIN2 polymorphism and cancer risk, we conducted this study.

Methods

An updated analysis was performed to analyze the correlation between AXIN2 polymorphisms and cancer risk. Linkage disequilibrium (LD) analysis was also used to show the associations.

Results

Seventy-two case-control studies were involved in the study, including 22,087 cases and 18,846 controls. The overall results showed rs11079571 had significant association with cancer risk (allele contrast model: OR = 0.539, 95%CI = 0.478–0.609, PAdjust = 0.025; homozygote model: OR = 0.22, 95% CI = 0.164–0.295, PAdjust< 0.001; heterozygote model: OR = 0.292, 95% CI = 0.216–0.394, PAdjust< 0.001; dominant model: OR = 0.249, 95% CI = 0.189–0.33, PAdjust< 0.001). The same results were obtained with rs1133683 in homozygote and recessive models (PAdjust< 0.05), and in rs35285779 in heterozygote and dominant models (PAdjust< 0.05). LD analysis revealed significant correlation between rs7210356 and rs9915936 in the populations of CEU, CHB&CHS, ESN and JPT (CEU: r² = 0.91; CHB&CHS: r² = 0.74; ESN: r² = 0.62, JPT: r² = 0.57), and a significant correlation between rs9915936 and rs7224837 in the populations of CHB&CHS, ESN and JPT (r²>0.5), between rs7224837 and rs7210356 in the populations of CEU, CHB&CHS, JPT (r²>0.5), between rs35435678 and rs35285779 in the populations of CEU, CHB&CHS and JPT (r²>0.5).

Conclusions

AXIN2 rs11079571, rs1133683 and rs35285779 polymorphisms have significant correlations with overall cancer risk. What’s more, two or more polymorphisms such as rs7210356 and rs9915936, rs9915936 and rs7224837, rs7224837 and rs7210356, rs35435678 and rs35285779 have significant correlation with cancer susceptibility in different populations.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08092-0.

miR-130a-3p regulates steroid hormone synthesis in goat ovarian granulosa cells by targeting the PMEPA1 gene

MicroRNAs (miRNAs) are key epigenomic regulators of proliferation, differentiation, and secretion in cells involved in follicular development. We here studied the functional role of one such molecule, miR-130a-3p, in goat ovarian granulosa cells (GCs). High expression of this miRNA was evident in goat GCs by fluorescence in situ hybridization and suppressed estradiol and progesterone secretion from these cells, as determined by ELISA. miR-130a-3p was predicted to have a binding site for the 3' UTR of the prostate transmembrane protein androgen induced 1 gene (PMEPA1), and this was verified by a dual-luciferase reporter assay. PMEPA1 mRNA and protein expression were both found to be regulated by miR-130a-3p in GCs. Moreover, the overexpression or knockdown of PMEPA1 enhanced or suppressed estradiol and progesterone secretion from these cells, respectively. Furthermore, the secretion of estradiol and progesterone did not change significantly after the offsetting of PMEPA1 overexpression in GCs by miR-130a-3p. In summary, our present data indicate that miR-130a-3p inhibits the secretion of estradiol and progesterone in GCs by targeting PMEPA1. Our study thus provides seminal data and important new insights into the regulation of reproductive mechanisms in the nanny goat and other female mammals.

Study on the cellular internalization mechanisms and in vivo anti-bone metastasis prostate cancer efficiency of the peptide T7-modified polypeptide nanoparticles

Bone-metastasis prostate cancer (BMPCa)-targeting gene therapy is gaining increasing concern in recent years. The peptide T7-modified polypeptide nanoparticles for delivery DNA (CRD-PEG-T7/pPMEPA1) was prepared as our previous study. However, the feasibility of CRD-PEG-T7/pPMEPA1 for BMPCa treatment, the mechanisms underlying cellular uptake, anti-BMPCa effect, and administration safety requires further research. LNCaP cells treated with endocytosis inhibitors and excessive T7 under different culture condition were carried out to investigate the mechanisms of cellular uptake of the CRD-PEG-T7-pPMEPA1. A transwell assay was applied to evaluate the cell migration ability. Besides, the tumor volume and survival rates of the PCa xenograft mice model were recorded to estimate the anti-tumor effect. In addition, the weight profiles of the PCa tumor-bearing mice, the blood chemistry, and the HE analysis of visceral organs and tumor was conducted to investigate the administration safety of CRD-PEG-T7/pPMEPA1. The results showed that PCa cellular uptake was decreased after treating with excessive free T7, endocytosis inhibitors and lower incubation temperature. Besides, CRD-PEG-T7/pPMEPA1 could inhibit the LNCaP cells chemotaxis and tumor growth. In addition, the survival duration of the PCa tumor-bearing mice treating with CRD-PEG-T7/pPMEPA1 was significantly prolonged with any systemic toxicity or damage to the organs. In conclusion, this research proposes a promising stratagem for treatment BMPCa by providing the biocompatible and effective carrier for delivery DNA therapeutic agents.

PMEPA1/TMEPAI isoforms function via its PY and Smad-interaction motifs for tumorigenic activities of breast cancer cells

PMEPA1 (prostate transmembrane protein, androgen-induced 1)/TMEPAI (transmembrane prostate androgen-induced protein) is highly expressed in diverse cancers, including breast, lung and prostate cancers. It consists of four isoforms with distinct extracellular regions (isoforms a-d). The expression and function of these isoforms are still poorly understood. Hence, we aimed to identify the preferentially expressed isoforms in breast cancer cells and analyze possible differences in tumorigenic functions. In this study, we used 5' Rapid Amplification of cDNA Ends (RACE) and Western blot analyses to identify the mRNA variants and protein isoforms of TMEPAI and found that TMEPAI isoform d as the major isoform expressed by TGF-β stimulation in breast cancer cells. We then generated CRISPR/Cas9-mediated TMEPAI knockout (KO) breast cancer cell lines and used a lentiviral expression system to complement each isoform individually. Although there were no clear functional differences between isoforms, double PPxY (PY) motifs and a Smad-interaction motif (SIM) of TMEPAI were both essential for colony and sphere formation. Collectively, our results provide a novel insight into TMEPAI isoforms in breast cancer cells and showed that coordination between double PY motifs and a SIM of TMEPAI are essential for colony and sphere formation but not for monolayer cell proliferation.

TGF-β-Induced TMEPAI Attenuates the Response of Triple-Negative Breast Cancer Cells to Doxorubicin and Paclitaxel

Purpose

Triple-negative breast cancer (TNBC) is a refractory type of breast cancer with poor prognosis and limited choice for treatment. Previous studies had shown that TNBC has high expressions of transmembrane prostate androgen-induced protein (TMEPAI). TMEPAI was known to be induced by TGF-β/Smad signaling and have tumorigenic functions that converting TGF-β from tumor suppressor to tumor promoter and inducing epithelial–mesenchymal transition (EMT). Therefore, we aimed to define the role of TMEPAI in triple-negative breast cancer cells treatment using several anti-cancers in the presence of TGF-β.

Methods

TMEPAI-knock out (KO) was carried out in a triple-negative breast cancer cell, BT549. TMEPAI editing was developed using the CRISPR-Cas9 system using two combinations of sgRNA to remove exon 4 of the TMEPAI gene entirely. Genotyping and proteomic analysis were performed to check the establishment of the TMEPAI-KO cells. Wild type (WT) and KO cells were used to determine inhibitory concentration 50% (IC₅₀) of several anti-cancers: doxorubicin, cisplatin, paclitaxel, and bicalutamide in the presence of TGF-β treatment.

Results

KO cells were successfully established by completely removing the TMEPAI gene, which was proven in genomic and proteomic analysis. Further, in TMEPAI-KO cells, we found a significant reduction of IC₅₀ for doxorubicin and paclitaxel, and minimal effects were seen for cisplatin and bicalutamide. Our findings suggest that TGF-β-induced TMEPAI attenuates the response of TNBC to doxorubicin and paclitaxel, but not to cisplatin and bicalutamide.

Conclusion

TGF-β induced TMEPAI contributes to the reduced response of TNBC treatment to doxorubicin and paclitaxel, but minimal on cisplatin and bicalutamide. Further study is needed to confirm our findings in other growth factor-induced cells, as well as in in vivo model.

Analysis of PMEPA1 Isoforms (a and b) as Selective Inhibitors of Androgen and TGF-β Signaling Reveals Distinct Biological and Prognostic Features in Prostate Cancer

Dysfunctions of androgen/TGF-β signaling play important roles in prostate tumorigenesis. Prostate Transmembrane Protein Androgen Induced 1 (PMEPA1) inhibits androgen and TGF-β signaling via a negative feedback loop. The loss of PMEPA1 confers resistance to androgen signaling inhibitors and promotes bone metastasis. Conflicting reports on the expression and biological functions of PMEPA1 in prostate and other cancers propelled us to investigate isoform specific functions in prostate cancer (PCa). One hundred and twenty laser capture micro-dissection matched normal prostate and prostate tumor tissues were analyzed for correlations between quantitative expression of PMEPA1 isoforms and clinical outcomes with Q-RT-PCR, and further validated with a The Cancer Genome Atlas (TCGA) RNA-Seq dataset of 499 PCa. Cell proliferation was assessed with cell counting, plating efficiency and soft agar assay in androgen responsive LNCaP and TGF-β responsive PC3 cells. TGF-β signaling was measured by SMAD dual-luciferase reporter assay. Higher PMEPA1-a mRNA levels indicated biochemical recurrence (p = 0.0183) and lower PMEPA1-b expression associated with metastasis (p = 0.0173). Further, lower PMEPA1-b and a higher ratio of PMEPA1-a vs. -b were correlated to higher Gleason scores and lower progression free survival rate (p < 0.01). TGF-β-responsive PMEPA1-a promoted PCa cell growth, and androgen-responsive PMEPA1-b inhibited cancer cell proliferation. PMEPA1 isoforms -a and -b were shown to be promising candidate biomarkers indicating PCa aggressiveness including earlier biochemical relapse and lower disease specific life expectancy via interrupting androgen/TGF-β signaling.

Forkhead box (FOX) G1 promotes hepatocellular carcinoma epithelial-Mesenchymal transition by activating Wnt signal through forming T-cell factor-4/Beta-catenin/FOXG1 complex

Background

Forkhead box G1 (FOXG1) is a member of the Fox transcription factor family involved in regulation of many cancers. However, the role of FOXG1 in hepatocellular carcinogenesisis largely unclear. The present study aimed at examining the biological function and underlying mechanism of FOXG1 on hepatocellular carcinoma (HCC) tumor metastasis as well as its clinical significance.

Methods

Levels of FOXG1 were determined by immunohistochemical and real-time PCR analysis in HCC cell lines and human HCC samples. The effect of FOXG1 on cancer cell invasion and metastasis was investigated in vitro and in vivo in either FOXG1-silenced or overexpressing human HCC cell lines. Immunoprecipitation and chromatin immunoprecipitation assays were performed to investigate the interaction of FOXG1, β-catenin, TCF4 and the effect on Wnt target-gene promoters.

Results

In human HCC, the level of FOXG1 progressively increased from surrounding non tumorous livers to HCC, reaching the highest levels in metastatic HCC. Furthermore, expression levels of FOXG1 directly correlated with cancer cell epithelial-mesenchymal transition (EMT) phenotype. In FOXG1-overexpressing cells, FOXG1 promotes the stabilization and nuclear accumulation of β-catenin by directly binding to β-catenin and it associates with the lymphoid enhancer factor/T cell factor proteins (LEF/TCFs) on Wnt responsive enhancers (WREs) in chromatin.

Conclusions

The results show that FOXG1 plays a key role in mediating cancer cell metastasis through the Wnt/β-catenin pathway in HCC cells and predicts HCC prognosis after surgery. Targeting FOXG1 may provide a new approach for therapeutic treatment in the future.

Prostaglandin F2α-induced Prostate Transmembrane Protein, Androgen Induced 1 mediates ovarian cancer progression increasing epithelial plasticity

The role of prostaglandin (PG) F_2α has been scarcely studied in cancer. We have identified a new function for PGF_2α in ovarian cancer, stimulating the production of Prostate Transmembrane Protein, Androgen Induced 1 (PMEPA1). We show that this induction increases cell plasticity and proliferation, enhancing tumor growth through PMEPA1. Thus, PMEPA1 overexpression in ovarian carcinoma cells, significantly increased cell proliferation rates, whereas PMEPA1 silencing decreased proliferation. In addition, PMEPA1 overexpression buffered TGFβ signaling, via reduction of SMAD-dependent signaling. PMEPA1 overexpressing cells acquired an epithelial morphology, associated with higher E-cadherin expression levels while β-catenin nuclear translocation was inhibited. Notwithstanding, high PMEPA1 levels also correlated with epithelial to mesenchymal transition markers, such as vimentin and ZEB1, allowing the cells to take advantage of both epithelial and mesenchymal characteristics, gaining in cell plasticity and adaptability. Interestingly, in mouse xenografts, PMEPA1 overexpressing ovarian cells had a clear survival and proliferative advantage, resulting in higher metastatic capacity, while PMEPA1 silencing had the opposite effect. Furthermore, high PMEPA1 expression in a cohort of advanced ovarian cancer patients was observed, correlating with E-cadherin expression. Most importantly, high PMEPA1 mRNA levels were associated with lower patient survival.

Role of the kringle-like domain in glycoprotein NMB for its tumorigenic potential

Glycoprotein NMB (GPNMB) is highly expressed in many types of malignant tumors and thought to be a poor prognostic factor in those cancers, including breast cancer. Glycoprotein NMB is a type IA transmembrane protein that has a long extracellular domain (ECD) and a short intracellular domain (ICD). In general, the ECD of a protein is involved in protein‐protein or protein‐carbohydrate interactions, whereas the ICD is important for intracellular signaling. We previously reported that GPNMB contributes to the initiation and malignant progression of breast cancer through the hemi‐immunoreceptor tyrosine‐based activation motif (hemITAM) in its ICD. Furthermore, we showed that the tyrosine residue in hemITAM is involved in induction of the stem‐like properties of breast cancer cells. However, the contribution of the ECD to its tumorigenic function has yet to be fully elucidated. In this study, we focused on the region, the so‐called kringle‐like domain (KLD), that is conserved among species, and made a deletion mutant, GPNMB(ΔKLD). Enhanced expression of WT GPNMB induced sphere and tumor formation in breast epithelial cells; in contrast, GPNMB(ΔKLD) lacked these activities without affecting its molecular properties, such as subcellular localization, Src‐induced tyrosine phosphorylation at least in overexpression experiments, and homo‐oligomerization. Additionally, GPNMB(ΔKLD) lost its cell migration promoting activity, even though it reduced E‐cadherin expression. Although the interaction partner binding to KLD has not yet been identified, we found that the KLD of GPNMB plays an important role in its tumorigenic potential.