TFAP2C regulates carbonic anhydrase XII in human breast cancer

TFAP2A downregulation mediates tumor-suppressive effect of miR-8072 in triple-negative breast cancer via inhibiting SNAI1 transcription

BACKGROUND

Triple-negative breast cancer (TNBC) represents a highly aggressive subset of breast malignancies characterized by its challenging clinical management and unfavorable prognosis. While TFAP2A, a member of the AP-2 transcription factor family, has been implicated in maintaining the basal phenotype of breast cancer, its precise regulatory role in TNBC remains undefined.

METHODS

In vitro assessments of TNBC cell growth and migratory potential were conducted using MTS, colony formation, and EdU assays. Quantitative PCR was employed to analyze mRNA expression levels, while Western blot was utilized to evaluate protein expression and phosphorylation status of AKT and ERK. The post-transcriptional regulation of TFAP2A by miR-8072 and the transcriptional activation of SNAI1 by TFAP2A were investigated through luciferase reporter assays. A xenograft mouse model was employed to assess the in vivo growth capacity of TNBC cells.

RESULTS

Selective silencing of TFAP2A significantly impeded the proliferation and migration of TNBC cells, with elevated TFAP2A expression observed in breast cancer tissues. Notably, TNBC patients exhibiting heightened TFAP2A levels experienced abbreviated overall survival. Mechanistically, TFAP2A was identified as a transcriptional activator of SNAI1, a crucial regulator of epithelial-mesenchymal transition (EMT) and cellular proliferation, thereby augmenting the oncogenic properties of TFAP2A in TNBC. Moreover, miR-8072 was unveiled as a negative regulator of TFAP2A, exerting potent inhibitory effects on TNBC cell growth and migration. Importantly, the tumor-suppressive actions mediated by the miR-8072/TFAP2A axis were intricately associated with the attenuation of AKT/ERK signaling cascades and the blockade of EMT processes.

CONCLUSIONS

Our findings unravel the role and underlying molecular mechanism of TFAP2A in driving tumorigenesis of TNBC. Targeting the TFAP2A/SNAI1 pathway and utilizing miR-8072 as a suppressor represent promising therapeutic strategies for treating TNBC.

Unlocking Overexpressed Membrane Proteins to Guide Breast Cancer Precision Medicine

Breast cancer (BC) is a prevalent form of cancer affecting women worldwide. However, the effectiveness of current BC drugs is limited by issues such as systemic toxicity, drug resistance, and severe side effects. Consequently, there is an urgent need for new therapeutic targets and improved tumor tracking methods. This study aims to address these challenges by proposing a strategy for identifying membrane proteins in tumors that can be targeted for specific BC therapy and diagnosis. The strategy involves the analyses of gene expressions in breast tumor and non-tumor tissues and other healthy tissues by using comprehensive bioinformatics analysis from The Cancer Genome Atlas (TCGA), UALCAN, TNM Plot, and LinkedOmics. By employing this strategy, we identified four transcripts (LRRC15, EFNA3, TSPAN13, and CA12) that encoded membrane proteins with an increased expression in BC tissue compared to healthy tissue. These four transcripts also demonstrated high accuracy, specificity, and accuracy in identifying tumor samples, as confirmed by the ROC curve. Additionally, tissue microarray (TMA) analysis revealed increased expressions of the four proteins in tumor tissues across all molecular subtypes compared to the adjacent breast tissue. Moreover, the analysis of human interactome data demonstrated the important roles of these proteins in various cancer-related pathways. Taken together, these findings suggest that LRRC15, EFNA3, TSPAN13, and CA12 can serve as potential biomarkers for improving cancer diagnosis screening and as suitable targets for therapy with reduced side effects and enhanced efficacy.

TFAP2C Activates CST1 Transcription to Facilitate Breast Cancer Progression and Suppress Ferroptosis

Cystatin SN (CST1) appears to have pro-tumor effects in breast cancer (BC) and is involved in ferroptosis; however, there is no report on the regulation of ferroptosis by CST1 for BC development. The purpose of this study is to investigate the functions and mechanisms operated by CST1 in BC development and ferroptosis. Transcription Factor Activator Protein 2γ (TFAP2C) and CST1 levels in BC tissues and estrogen receptor (ER)+ cells were quantified by RT-qPCR and western blotting. After knocking down TFAP2C and CST1 expression in MCF7 and T47D cells, the proliferation, colony formation ability, apoptosis, and cell cycle were assessed. Ferroptosis was verified by detecting glutathione peroxidase 4 (GPX4) and 4-hydroxy-2-nonenal (4HNE) levels. The kits were used to test Fe2+, reactive oxygen species, malondialdehyde, and glutathione levels, and ultrastructure of mitochondria was observed through transmission electron microscope. Dual-luciferase reporter assay and chromatin immunoprecipitation test were carried out to investigate the interaction of TFAP2C and CST1. A transplanted tumor model was established to explore the function of TFAP2C in tumorigenesis by quantifying TFAP2C, CST1, Ki67, and GPX4 levels through western blotting and immunochemistry after silencing TFAP2C. TFAP2C and CST1 were predominantly expressed in BC cells. Silencing of TFAP2C or CST1 expression suppressed ER+ BC cell proliferation, promoted apoptosis and ferroptosis, and blocked cell cycle transition from G1 phase to S phase. TFAP2C knockdown in transplanted tumors inhibited tumor growth and GPX4 level. Upregulating CST1 nullified the anti-tumor effects of TFAP2C knockdown and TFAP2C promoted CST1 expression through transcription activation. TFAP2C activates CST1 transcription to facilitate BC development and block ferroptosis.

Estrogen-Induced LncRNA, LINC02568, Promotes Estrogen Receptor-Positive Breast Cancer Development and Drug Resistance Through Both In Trans and In Cis Mechanisms

Endocrine therapy is the frontline treatment for estrogen receptor (ER) positive breast cancer patients. However, the primary and acquired resistance to endocrine therapy drugs remain as a major challenge in the clinic. Here, this work identifies an estrogen-induced lncRNA, LINC02568, which is highly expressed in ER-positive breast cancer and functional important in cell growth in vitro and tumorigenesis in vivo as well as endocrine therapy drug resistance. Mechanically, this work demonstrates that LINC02568 regulates estrogen/ERα-induced gene transcriptional activation in trans by stabilizing ESR1 mRNA through sponging miR-1233-5p in the cytoplasm. Meanwhile, LINC02568 contributes to tumor-specific pH homeostasis by regulating carbonic anhydrase CA12 in cis in the nucleus. The dual functions of LINC02568 together contribute to breast cancer cell growth and tumorigenesis as well as endocrine therapy drug resistance. Antisense oligonucleotides (ASO) targeting LINC02568 significantly inhibits ER-positive breast cancer cell growth in vitro and tumorigenesis in vivo. Furthermore, combination treatment with ASO targeting LINC02568 and endocrine therapy drugs or CA12 inhibitor U-104 exhibits synergistic effects on tumor growth. Taken together, the findings reveal the dual mechanisms of LINC02568 in regulating ERα signaling and pH homeostasis in ER-positive breast cancer, and indicated that targeting LINC02568 might represent a potential therapeutic avenue in the clinic.

Crucial role of the transcription factors family activator protein 2 in cancer: current clue and views

The transcription factor family activator protein 2 (TFAP2) is vital for regulating both embryonic and oncogenic development. The TFAP2 family consists of five DNA-binding proteins, including TFAP2A, TFAP2B, TFAP2C, TFAP2D and TFAP2E. The importance of TFAP2 in tumor biology is becoming more widely recognized. While TFAP2D is not well studied, here, we mainly focus on the other four TFAP2 members. As a transcription factor, TFAP2 regulates the downstream targets directly by binding to their regulatory region. In addition, the regulation of downstream targets by epigenetic modification, posttranslational regulation, and interaction with noncoding RNA have also been identified. According to the pathways in which the downstream targets are involved in, the regulatory effects of TFAP2 on tumorigenesis are generally summarized as follows: stemness and EMT, interaction between TFAP2 and tumor microenvironment, cell cycle and DNA damage repair, ER- and ERBB2-related signaling pathway, ferroptosis and therapeutic response. Moreover, the factors that affect TFAP2 expression in oncogenesis are also summarized. Here, we review and discuss the most recent studies on TFAP2 and its effects on carcinogenesis and regulatory mechanisms.

Astrocyte-derived exosomal lncRNA 4933431K23Rik modulates microglial phenotype and improves post-traumatic recovery via SMAD7 regulation

Astrocyte-microglial interaction plays a crucial role in brain injury-associated neuroinflammation. Our previous data illustrated that astrocytes secrete microRNA, leading to anti-inflammatory effects on microglia. Long non-coding RNAs participate in neuroinflammation regulation after traumatic brain injury. However, the effect of astrocytes on microglial phenotype via long non-coding RNAs and the underlying molecular mechanisms remain elusive. We used long non-coding RNA sequencing on murine astrocytes and found that exosomal long non-coding RNA 4933431K23Rik attenuated traumatic brain injury-induced microglial activation in vitro and in vivo and ameliorated cognitive function deficiency. Furthermore, microRNA and messenger RNA sequencing together with binding prediction illustrated that exosomal long non-coding RNA 4933431K23Rik up-regulates E2F7 and TFAP2C expression by sponging miR-10a-5p. Additionally, E2F7 and TFAP2C, as transcription factors, regulated microglial Smad7 expression. Using Cx3cr1-Smad7 overexpression of adeno-associated virus, microglia specifically overexpressed Smad7 in the attenuation of neuroinflammation, resulting in less cognitive deficiency after traumatic brain injury. Mechanically, overexpressed Smad7 physically binds to IκBα and inhibits its ubiquitination, preventing NF-κB signaling activation. The Smad7 activator asiaticoside alleviates neuroinflammation and protects neuronal function in traumatic brain injury mice. This study revealed that an exosomal long non-coding RNA from astrocytes attenuates microglial activation after traumatic brain injury by up-regulating Smad7, providing a potential therapeutic target.

Differential CMS-Related Expression of Cell Surface Carbonic Anhydrases IX and XII in Colorectal Cancer Models-Implications for Therapy

Tumor-associated carbonic anhydrases IX (CAIX) and XII (CAXII) have long been in the spotlight as potential new targets for anti-cancer therapy. Recently, CAIX/CAXII specific inhibitor SLC-0111 has passed clinical phase I study and showed differential response among patients with colorectal cancer (CRC). CRC can be classified into four different consensus molecular subgroups (CMS) showing unique expression patterns and molecular traits. We questioned whether there is a CMS-related CAIX/CAXII expression pattern in CRC predicting response. As such, we analyzed transcriptomic data of tumor samples for CA9/CA12 expression using Cancertool. Protein expression pattern was examined in preclinical models comprising cell lines, spheroids and xenograft tumors representing the CMS groups. Impact of CAIX/CAXII knockdown and SLC-0111 treatment was investigated in 2D and 3D cell culture. The transcriptomic data revealed a characteristic CMS-related CA9/CA12 expression pattern with pronounced co-expression of both CAs as a typical feature of CMS3 tumors. Protein expression in spheroid- and xenograft tumor tissue clearly differed, ranging from close to none (CMS1) to strong CAIX/CAXII co-expression in CMS3 models (HT29, LS174T). Accordingly, response to SLC-0111 analyzed in the spheroid model ranged from no (CMS1) to clear (CMS3), with moderate in CMS2 and mixed in CMS4. Furthermore, SLC-0111 positively affected impact of single and combined chemotherapeutic treatment of CMS3 spheroids. In addition, combined CAIX/CAXII knockdown and more effective treatment with SLC-0111 reduced clonogenic survival of CMS3 modelling single cells. In conclusion, the preclinical data support the clinical approach of targeted CAIX/CAXII inhibition by showing linkage of expression with response and suggest that patients with CMS3-classified tumors would most benefit from such treatment.

Comparative Analysis of Transcriptomic Changes including mRNA and microRNA Expression Induced by the Xenoestrogens Zearalenone and Bisphenol A in Human Ovarian Cells

Xenoestrogens are natural or synthetic compounds that mimic the effect of endogenous estrogens and might cause cancer. We aimed to compare the global transcriptomic response to zearalenone (ZEA; mycotoxin) and bisphenol A (BPA; plastic additive) with the effect of physiological estradiol (E2) in the PEO1 human ovarian cell line by mRNA and microRNA sequencing. Estrogen exposure induced remarkable transcriptomic changes: 308, 288 and 63 genes were upregulated (log₂FC > 1); 292, 260 and 45 genes were downregulated (log₂FC < -1) in response to E2 (10 nM), ZEA (10 nM) and BPA (100 nM), respectively. Furthermore, the expression of 13, 11 and 10 miRNAs changed significantly (log₂FC > 1, or log₂FC < -1) after exposure to E2, ZEA and BPA, respectively. Functional enrichment analysis of the significantly differentially expressed genes and miRNAs revealed several pathways related to the regulation of cell proliferation and migration. The effect of E2 and ZEA was highly comparable: 407 genes were coregulated by these molecules. We could identify 83 genes that were regulated by all three treatments that might have a significant role in the estrogen response of ovarian cells. Furthermore, the downregulation of several miRNAs (miR-501-5p, let-7a-2-3p, miR-26a-2-3p, miR-197-5p and miR-582-3p) was confirmed by qPCR, which might support the proliferative effect of estrogens in ovarian cells.

HN1L/AP-2γ/PLK1 signaling drives tumor progression and chemotherapy resistance in esophageal squamous cell carcinoma

Hematological and neurological expressed 1 like (HN1L) is a newly identified oncogene in lung cancer and hepatocellular carcinoma recently identified by our team, but its roles in the development and treatment of esophageal squamous cell carcinoma (ESCC) remain incompletely cataloged. Here, using ESCC tissue array and public database analysis, we demonstrated that HN1L was highly expressed in ESCC tissues, which was associated with tumor tissue invasion, poor clinical stage and short survival for ESCC patients. Loss- and gain-of-function studies in ESCC cells revealed that HN1L enhances ESCC cell metastasis and proliferation in vitro and in mice models. Moreover, high level of HN1L reduces the sensibility of ESCC cells to chemotherapeutic drugs, such as Docetaxel. Mechanism studies revealed that HN1L activated the transcription of polo-like kinase 1 (PLK1) by interacting with transcription factor AP-2γ, which increased the expression of malignancy related proteins Cyclin D1 and Slug in ESCC cells. Blocking PLK1 with inhibitor BI-2356 abrogated the oncogenic function of HN1L and significantly suppressed ESCC progression by combining with chemotherapy. Therefore, this study demonstrates the vital pro-tumor role of HN1L/AP-2γ/PLK1 signaling axis in ESCC, offering a potential therapeutic strategy for ESCC patients with high HN1L by blocking PLK1.

Epigenetic oncogenesis, biomarkers and emerging chemotherapeutics for breast cancer

Breast cancer remains one of the leading causes of cancer-related deaths globally and the most prominent among females, yet with limited effective therapeutic options. Most of the current medications are challenged by various factors including low efficacy, incessant resistance, immune evasion and frequent recurrence of the disease. Further understanding of the prognosis and identification of plausible therapeutic channels thus requires multimodal approaches. In this review, epigenetics studies of several pathways to BC oncogenesis via the inducement of oncogenic changes on relevant markers have been overviewed. Similarly, the counter-epigenetic mechanisms to reverse such changes as effective therapeutic strategies were surveyed. The epigenetic oncogenesis occurs through several pathways, notably, DNMT-mediated hypermethylation of DNA, dysregulated expression for ERα, HER2/ERBB and PR, histone modification, overexpression of transcription factors including the CDK9-cyclin T1 complex and suppression of tumour suppressor genes. Scientifically, the regulatory reversal of the mechanisms constitutes effective epigenetic approaches for mitigating BC initiation, progression and metastasis. These were exhibited at various experimental levels by classical chemotherapeutic agents including some repurposable drugs, endocrine inhibitors, monoclonal antibodies and miRNAs, natural products, metal complexes and nanoparticles. Dozens of the potential candidates are currently in clinical trials while others are still at preclinical experimental stages showing promising anti-BC efficacy. The review presents a model for a wider understanding of epigenetic oncogenic pathways to BC and reveals plausible channels for reversing the unpleasant changes through epigenetic modifications. It advances the science of therapeutic designs for ameliorating the global burden of BC upon further translational studies.

Roles of activator protein-2 gamma in breast cancer: A narrative review (SANRA)

Activator protein-2 gamma (AP-2γ) is a crucial transcription factor involved in breast cancer development. Abnormal expression and activity of AP-2γ have also been identified as important markers of malignancy. In the last decade, the importance of AP-2γ in breast cancer progression has been widely studied. In this review, we summarize the current knowledge on the regulatory roles of AP-2γ in breast cancer oncogenesis and progression and its potential as a diagnostic biomarker and drug target in breast cancer treatment.

TRIM37 Augments AP-2γ Transcriptional Activity and Cellular Localization via K63-linked Ubiquitination to Drive Breast Cancer Progression

Activator Protein 2 gamma (AP-2γ) is a master transcription factor that plays a critical role in the development and progression of breast cancer. However, the underlying mechanism is still unclear. Herein, using a proteomics approach, we identified Tripartite motif-containing 37 (TRIM37) as a novel coactivator of AP-2γ-mediated transcription in breast cancer cells. We demonstrate that TRIM37 facilitates AP-2γ chromatin binding to directly regulate the AP-2γ mediated transcriptional program. We also show that TRIM37 achieves this by stimulating K63 chain-linked ubiquitination of AP-2γ, promoting protein localization from the cytoplasm to the nucleus. In clinical analyses, we find TRIM37 is upregulated in multiple breast cancer datasets, supporting our findings that the TRIM37-AP-2γ interaction is essential for breast cancer tumor growth. Overall, our work reveals that TRIM37 is an oncogenic coactivator of AP-2γ in breast cancer and provides a novel therapeutic target for treating the disease.

Selection and identification of a specific peptide binding to ovarian cancer cells from a phage-displayed peptide library

OBJECTIVES

Ovarian cancer is one of the most fatal gynecological malignancies. It is emergently needed to select a novel molecular fragment as a targeting element for the future development of molecular imaging diagnosis and targeting chemotherapy to ovarian cancer.

RESULTS

After five rounds of biopanning, a total of 44 positive phage clones were selected from final phage displayed peptide library. Nine consensus sequences were found based on the assay of sequencing results, then one clone of each consensus group was characterized and identified further by immunofluorescence assay. The result showed the phage clone R20 presents best targeting capacity. Then we synthesized peptide (OSP2) clone R20 displayed, it was characterized with high specificity and sensitivity binding to human ovarian cancer by a tissue chip assay. The target of OSP2 was predicted and docked as human carbonic anhydrase XII (CA12), an important protein usually deregulated in cancer.

CONCLUSIONS

Taken together, OSP2 and its target indicate a novel investigation way in future to develop novel agent or drug delivery formulation for molecular imaging diagnosis and targeting chemotherapy of ovarian cancer.

Cooperative interaction between ERα and the EMT-inducer ZEB1 reprograms breast cancer cells for bone metastasis

The epithelial to mesenchymal transition (EMT) has been proposed to contribute to the metastatic spread of breast cancer cells. EMT-promoting transcription factors determine a continuum of different EMT states. In contrast, estrogen receptor α (ERα) helps to maintain the epithelial phenotype of breast cancer cells and its expression is crucial for effective endocrine therapies. Determining whether and how EMT-associated transcription factors such as ZEB1 modulate ERα signaling during early stages of EMT could promote the discovery of therapeutic approaches to suppress metastasis. Here we show that, shortly after induction of EMT and while cells are still epithelial, ZEB1 modulates ERα-mediated transcription induced by estrogen or cAMP signaling in breast cancer cells. Based on these findings and our ex vivo and xenograft results, we suggest that the functional interaction between ZEB1 and ERα may alter the tissue tropism of metastatic breast cancer cells towards bone.

The epithelial mesenchymal transition (EMT) is important in the metastatic spread of cancer cells. Here, the authors show that the EMT transcription factor, ZEB1, can modify estrogen receptor α during EMT and facilitate the migration of breast cancer cells to the bone

Anlotinib inhibits the proliferation, migration and invasion, and induces apoptosis of breast cancer cells by downregulating TFAP2C

The vascular endothelial growth factor receptor (VEGFR) network contributes to breast cancer pathogenesis and progression. Anlotinib is a highly potent multi-target tyrosine kinase inhibitor that has been previously shown to exert antitumor effects in various types of cancer. The aim of the present study is to investigate the effect of Anlotinib against breast cancer cells in vitro and uncover the possible underlying mechanisms. The human breast cancer cell line MCF-7 was treated with different concentrations of Anlotinib, before cell proliferation, migration, invasion and apoptosis were assessed using colony formation, wound healing, Transwell and TUNEL staining assays. In addition, the expression of transcription factor AP-2γ (TFAP2C) following Anlotinib stimulation was measured using reverse transcription-quantitative PCR and western blot analysis. TFAP2C was overexpressed in MCF-7 using transfection with a pcDNA3.1 vector, before the aforementioned experiments were repeated. The results revealed that Anlotinib impaired cell viability and colony formation, reduced proliferating cell nuclear antigen, Ki-67, MMP2, MMP9 and Bcl-2 expression levels, and inhibited cell migration and invasion. By contrast, the expression levels of tissue inhibitor of metalloproteinase 1, the frequency of apoptotic cells, the expression of Bax and the cleaved caspase-3/caspase-3 ratio increased in a concentration-dependent manner. Additionally, the expression of TFAP2C decreased after Anlotinib treatment. However, TFAP2C overexpression partially blocked the effects of Anlotinib on the proliferation, migration, invasion and apoptosis of MCF-7 cells. To conclude, Anlotinib suppressed proliferation, migration and invasion, whilst inducing apoptosis of MCF-7 cells, which may be partially dependent on the inhibition of TFAP2C expression.

Interaction of transcription factor AP-2 gamma with proto-oncogene PELP1 promotes tumorigenesis by enhancing RET signaling

A significant proportion of estrogen receptor-positive (ER+) breast cancer (BC) initially responds to endocrine therapy but eventually evolves into therapy-resistant BC. Transcription factor AP-2 gamma (TFAP2C) is a known regulator of ER activity, and high expression of TFAP2C is associated with a decreased response to endocrine therapies. PELP1 is a nuclear receptor coregulator, commonly overexpressed in BC, and its levels are correlated with poorer survival. In this study, we identified PELP1 as a novel interacting protein of TFAP2C. RNA-seq analysis of PELP1 knockdown BC cells followed by transcription factor motif prediction pointed to TFAP2C being enriched in PELP1-regulated genes. Gene set enrichment analysis (GSEA) revealed that the TFAP2C-PELP1 axis induced a subset of common genes. Reporter gene assays confirmed PELP1 functions as a coactivator of TFAP2C. Mechanistic studies showed that PELP1-mediated changes in histone methylation contributed to increased expression of the TFAP2C target gene RET. Furthermore, the TFAP2C-PELP1 axis promoted the activation of the RET signaling pathway, which contributed to downstream activation of AKT and ERK pathways in ER+ BC cells. Concomitantly, knockdown of PELP1 attenuated these effects mediated by TFAP2C. Overexpression of TFAP2C contributed to increased cell proliferation and therapy resistance in ER+ BC models, while knockdown of PELP1 mitigated these effects. Utilizing ZR75-TFAP2C xenografts with or without PELP1 knockdown, we provided genetic evidence that endogenous PELP1 is essential for TFAP2C-driven BC progression in vivo. Collectively, our studies demonstrated that PELP1 plays a critical role in TFAP2C transcriptional and tumorigenic functions in BC and blocking the PELP1-TFAP2C axis could have utility for treating therapy resistance.