Oncogenic Role In Breast Cancer Research Articles

Abstract 7595: PRMT5 inhibitor synergizes with PARP inhibitors in triple-negative breast cancer cells

Abstract Background: Treating triple-negative breast cancer (TNBC) patients, an aggressive subtype of breast cancer, is an ongoing clinical challenge. Small-molecule inhibitors targeting the poly ADP-ribose polymerase (PARP) DNA repair enzymes, have been approved for treating only a subset of TNBC patients with a specific genetic landscape (BRCA1 mutation). However, TNBC patients with wildtype BRCA1 (BRCA1WT) are still lacking targeted therapy and chemotherapy remains their main treatment strategy. High expression of protein arginine methyltransferase 5 (PRMT5) is linked to poor prognosis in breast cancer and PRMT5 alone or via its interacting proteins plays an oncogenic role in breast cancer. Recent evidence suggests that PRMT5 is a key player in regulating the repair of DNA double strand breaks (DSBs) either through homologous recombination (HR) or non-homologous end joining (NHEJ) depending on the PRMT5 expression level within the cell. This dependency of cancer cells on PRMT5 expression levels in deciding the repair pathway of choice can be exploited for developing therapies. We hypothesize that in BRCA1 wildtype TNBC cells, inhibiting PRMT5 activity will force the cells to rely on NHEJ rather than HR to repair DNA DSBs, and introducing PARP inhibitors in this setting will inactivate NHEJ as well, causing synthetic lethality and cell death. In this study, we evaluated the pre-clinical benefit of combining PARP inhibitors with a PRMT5 inhibitor in TNBC cells. Methods: Human TNBC cell lines with wildtype BRCA1 (MDA-MB-468, HCC1806) and mutant BRCA1 (MDA-MB-436, SUM149-PT) were treated with varying doses of two PARP inhibitors (Olaparib, Talazoparib) and a PRMT5 inhibitor (GSK3326595) as single agents or in combination. MTT-based cell viability assay was used to determine cytotoxicity of the treatments. mRNA expression was determined by RT-qPCR after drug treatment. Results and Conclusion: We report that PRMT5 inhibition synergizes with both Olaparib and Talazoparib, to potentiate cell death in two BRCA1WT but not in BRCA1mut TNBC cell lines. Furthermore, we show that inhibiting PRMT5 in BRCA1WT cells upregulates the mRNA expression of RAD50, a DNA damage sensing gene in the HR pathway. Our ongoing study is to delineate the molecular mechanism of action for the observed synergy and whether PRMT5 inhibition can overcome resistance to PARP inhibitors. Through this study, we will identify a novel treatment strategy for the majority of TNBC patients (BRCA1WT) who currently lack targeted therapies. Citation Format: Samyuktha Suresh, Lisa A. McPherson, James M. Ford. PRMT5 inhibitor synergizes with PARP inhibitors in triple-negative breast cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7595.

LncSNHG3 drives breast cancer progression by epigenetically increasing CSNK2A1 expression level.

Mounting evidence demonstrates that long noncoding RNAs (lncRNAs) have critical roles in the initiation and progression of cancer. Here, we report that small nucleolar RNA host gene 3 (SNHG3) is a key regulator of breast cancer progression. We analyzed RNA sequencing data to explore abnormally expressed lncRNAs in breast cancer. The effects of SNHG3 on breast cancer were investigated via in vitro and in vivo assays (CCK-8 assay, colony formation assay, flow cytometry assay, EdU assay, xenograft model, immunohistochemistry, and Western blot). The mechanism of SNHG3 action was explored through bioinformatics, RNA fluorescence in situ hybridization, luciferase reporter assay, RNA pull-down assay, chromatin immunoprecipitation assay and RNA immunoprecipitation assay. We found that SNHG3 expression was upregulated in breast cancer tissues and that its high expression level was associated with poor survival. We also found that high SNHG3 expression was partly induced by STAT3. Moreover, SNHG3 knockdown significantly repressed breast cancer cell growth both in vitro and in vivo. In the cytoplasm, SNHG3 facilitated the expression of Casein kinase II-A1 (CSNK2A1) by absorbing miR-485-5p and recruiting the HuR protein, participating in the malignant progression of breast cancer. Taken together, our study reveals a SNHG3-based regulatory network, which plays an oncogenic role in breast cancer and suggests that SNHG3 may serve as a potential target for the diagnosis and treatment of breast cancer.

LINC00963-FOSB-mediated transcription activation of UBE3C enhances radioresistance of breast cancer cells by inducing ubiquitination-dependent protein degradation of TP73

BackgroundThe ubiquitin protein ligase E3C (UBE3C) has been reported to play an oncogenic role in breast cancer (BRCA). This work further investigates the effect of UBE3C on the radioresistance of BRCA cells.MethodsMolecules linking to radioresistance in BRCA were identified by analyzing two GEO datasets, GSE31863 and GSE101920. UBE3C overexpression or knockdown was induced in parental or radioresistant BRCA cells, followed by irradiation treatment. The malignant properties of cells in vitro, and the growth and metastatic activity of cells in nude mice, were analyzed. Downstream target proteins, as well as upstream transcriptional regulators of UBE3C, were predicted by bioinformatics tools. Molecular interactions were confirmed by immunoprecipitation and immunofluorescence assays. Furthermore, artificial alterations of TP73 and FOSB were induced in the BRCA cells for functional rescue assays.ResultsAccording to bioinformatics analyses, UBE3C expression was linked to radioresistance in BRCA. UBE3C knockdown in radioresistant BRCA cells reduced while its overexpression in parental BRCA cells increased the radioresistance of cells in vitro and in vivo. UBE3C, which induced ubiquitination-dependent protein degradation of TP73, was transcriptionally activated by FOSB. The radioresistance of cancer cells was blocked by TP73 overexpression or FOSB knockdown. Additionally, LINC00963 was found to be responsible for the recruitment of FOSB to the UBE3C promoter for transcription activation.ConclusionThis work demonstrates that LINC00963 induces nuclear translocation of FOSB and the consequent transcription activation of UBE3C, which enhances radioresistance of BRCA cells by inducing ubiquitination-dependent protein degradation of TP73.Graphical

189O A phase II study of patritumab deruxtecan (HER3-DXd), in patients (pts) with advanced breast cancer (ABC), with biomarker analysis to characterize response to therapy (ICARUS-BREAST01)

HER3 plays a key oncogenic role in breast cancer, being associated with poor prognosis and resistance to PI3K/AKT/mTOR inhibitors (inh) and endocrine therapy (ET). HER3-DXd is an anti-HER3 monoclonal antibody conjugated to a topoisomerase I inh by a peptide-based cleavable linker, which showed activity in HER3-expressing ABC (NCT02980341). ICARUS-BREAST01 (NCT04965766) is an ongoing multi-center, single-arm, phase II study in pts with HR+ and HER2- ABC, unselected for HER3 expression, who progressed on CDK 4/6 inh, any line of targeted/ET and 1 line of chemotherapy for ABC. Enrolled pts receive HER3-DXd 5.6 mg/kg IV every 3 weeks and undergo tumor biopsy at baseline, on-treatment and end of treatment (EoT); 100 pts are planned; enrollment on HER3 IHC expression level was removed by amendment on Apr 21st, 2022. Primary endpoint is confirmed objective response rate; secondary: progression-free survival; duration of response; clinical benefit rate; overall survival and safety. We report the 3-months response rate (3m-RR) of patients included before Sept 15 2022 and safety data up to Nov 4 2022, based on data cut-off [DCO] of Jan 23, 2023. Multiplex imaging mass cytometry, DNA sequencing, circulating tumor cells (CTC) and association with treatment response will be presented. At DCO, 85 pts were included in the study and 56 were evaluable for this analysis. Pts and treatment characteristics are reported in the table. Among the 56 pts: 16 had partial response, 30 stable disease, 10 progressive disease. The 3 m-RR was 28.6% [95%CI: 18.4-41.5]. Most common any-grade adverse events (AEs) were: fatigue (89.3%), nausea (76.8%); most frequent grade ≥3 AEs was fatigue (14.0%). Confirmed ILD: 1 G1 (1.8%). Table: 189OCharacteristicsPatients N = 56 [range]; (%)Median age, years57 [28; 82]Median lines of therapy for ABC4 [2; 8]Median HER3-DXd cycles7 [3;20]Treatment discontinuationDisease progressionAdverse events (AEs)Others32 (57.1%)2363 Open table in a new tab HER3-DXd showed early signs of activity and a manageable safety profile in pts with HR+ HER2- ABC. Results on biomarkers analysis will also be presented.

Histocompatibility Minor 13 (HM13), targeted by miR-760, exerts oncogenic role in breast cancer by suppressing autophagy and activating PI3K-AKT-mTOR pathway

Histocompatibility Minor 13 (HM13) is reported to participate in regulating multiple cancers. In the present study, we uncovered that HM13 was highly expressed in breast cancer and correlated with worse prognosis. Downregulation of HM13 could suppress breast cancer cell proliferation and metastasis abilities. Tumorigenicity mediated by HM13 was also observed in the xenograft model. Knockdown of HM13 could activate autophagy by inducing endoplasmic reticulum (ER) stress. Moreover, further experiments demonstrated that downregulated HM13 could inhibit PI3K-AKT-mTOR pathway. We then verified that HM13 was a direct target of miR-760 functioned as a tumor -suppressor in breast cancer. And the tumor suppressive effects of miR-760 could be partially reversed by HM13. Taken together, these findings elucidated that HM13, targeted by miR-760, could play an oncogenic role in breast cancer by inducing autophagic inhibition and facilitating PI3K-AKT-mTOR pathway. Our findings suggested HM13 could act as a novel therapeutic target candidate for breast cancer and supported the idea that autophagy inducers might represent a new approach to treat breast cancer.

Abstract 1000: E-cadherin and EGFR interactions result in hyper-proliferation via ERK signaling in breast cancer

Abstract The loss of the intercellular adhesion molecule E-cadherin is a hallmark of the epithelial-mesenchymal transition (EMT), during which tumor cells transition into an invasive phenotype. Thus, E-cadherin has long been considered a tumor suppressor gene. However, recent studies have provided evidence that E-cadherin may promote metastasis rather than suppress it, suggesting oncogenic behavior. Here we provide data that E-cadherin plays an oncogenic role in breast cancer by promoting a hyper-proliferative phenotype in breast cancer cells via interaction with EGFR. This interaction results in the activation of the MEK/ERK signaling pathway, leading directly to changes in proliferation via transcription factors such as c-Fos. Pharmacological inhibition of MEK in E-cadherin positive breast cancer cells significantly decreases both tumor growth and macro-metastasis in vivo. This work provides evidence for a novel role of E-cadherin in breast tumor progression and identifies a potential new target to treat hyper-proliferative E-cadherin-positive breast tumors. Citation Format: Gabriella C. Russo, Ashleigh Crawford, David J. Clark, Julie Cui, Ryan Carney, Michelle N. Karl, Boyang Su, Batrholomew Starich, Tung-Shing Lee, Qiming Zhang, Pei-hsun Wu, Meng-Horng Lee, Hon S. Leong, Vito Rebecca, Hui Zhang, Denis Wirtz. E-cadherin and EGFR interactions result in hyper-proliferation via ERK signaling in breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1000.

Abstract 854: The role of protocadherin, FAT2 in breast cancer

Abstract Protocadherins are cell adhesion molecules that belong to the cadherin superfamily. They are novel cadherin like proteins predominantly associated with early development and morphogenesis, cell growth and patterning, cell-cell adhesion, cell motility (including cell invasion and migration). The Fat-protocadherins are derived from an ancestral Drosophila FAT like cadherin and are evolutionarily conserved. They have been primarily implicated in neuronal cell development and cancer. Several studies have implicated protocadherin dysfunction in cancer. Loss of protocadherin expression, chromosome deletion and epigenetic silencing have been implicated in kidney, prostate, colorectal and breast cancer. More recently they have been implicated in gastric tumors and gliomas. Based on these findings, protocadherins are thought to be tumor suppressors and in general seem to regulate cancer cell proliferation, migration and/or apoptosis. However, multiple exceptions have also been observed and individual protocadherin functions seem to be context-dependent, as some can be considered either tumor suppressors or proto-oncogenes according to the type of cancer being examined. The mechanistics of the roles of the protocadherins in neuronal development have been well dissected but most oncological studies have focused on their characterization as potential biomarkers while the molecular signaling pathways through which the protocadherins regulate growth, invasion and metastasis are still poorly understood. For example recent research has shown that FAT1 is repressed in oral cancer owing to homozygous deletion or epigenetic silencing and is preferentially downregulated in invasive breast cancer. On the other hand, FAT1 is upregulated in leukemia and prognosis of preB-ALL patients with FAT1 upregulation is poor. Therefore FAT1 is tumor suppressive or oncogenic in a context-dependent manner, while FAT4 is tumor suppressive. FAT2 is highly expressed in breast cancer and lung squamous cell carcinoma and the elevated expression of FAT2 is correlated with poor patient outcome.Our preliminary research analysis of the TCGA data from the Genomic Data Commons Portal shows that protocadherins FAT4 and FAT1 are among the top dysregulated genes in cancer. We have also determined that FAT2 has higher Copy Number Variation (CNV) gain events than loss events. Given that there is a well-known concordance between CNV and differential gene expression we believe that FAT2 has a paradoxical oncogenic role in breast cancer. Citation Format: Thomas Roache, Megan Sumera, Zalaila Laird, Amrita Datta. The role of protocadherin, FAT2 in breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 854.

Retracted] MicroRNA‑181 serves an oncogenic role in breast cancer via the inhibition of SPRY4.

Following the publication of this paper, it was drawn to the Editors' attention by a concerned reader that the Transwell cell migration assay data shown in Figs.3B and 9B were strikingly similar to data appearing in different form in other articles by different authors. Owing to the fact that the contentious data in the above article had already been published elsewhere, or were already under consideration for publication, prior to its submission to Molecular Medicine Reports, the Editor has decided that this paper should be retracted from the Journal. After having been in contact with the authors, they agreed with the decision to retract the paper. The Editor apologizes to the readership for any inconvenience caused. [Molecular Medicine Reports 18: 5603‑5613, 2018; DOI: 10.3892/mmr.2018.9572].

KIF18B promotes breast cancer cell proliferation, migration and invasion by targeting TRIP13 and activating the Wnt/β-catenin signaling pathway.

Kinesin superfamily member 18B (KIF18B) has previously been reported to be upregulated in breast cancer (BC) and is involved in BC tumorigenesis. Therefore, the present study aimed to investigate the effects and underlying mechanisms of KIF18B in BC. Comprehensive bioinformatics analysis was performed, using data from The Cancer Genome Atlas. KIF18B knockdown and thyroid hormone receptor-interacting protein 13 (TRIP13) overexpression in BC cells were induced via transfection, by using the short hairpin RNA-KIF18B and overexpression-TRIP13 vectors, respectively. Cellular processes, including proliferation, migration and invasion were assessed using colony formation, wound healing and Transwell assays, respectively. mRNA and protein expression levels were determined using reverse transcription-quantitative PCR and western blot analysis, respectively. Protein-protein interactions were determined using co-immunoprecipitation. The results demonstrated that the KIF18B expression levels were upregulated in BC, particularly in triple-negative BC (TNBC) tissues and cell lines. KIF18B knockdown inhibited the proliferation, migration and invasion of HCC-1937 TNBC cells. Furthermore, MMP12 and MMP9 protein expression levels were decreased by KIF18B knockdown. TRIP13 expression was also demonstrated to be upregulated in BC, particularly in TNBC tissues and cell lines. TRIP13 expression levels positively correlated with those of KIF18B in BC tissues and cells, and further analysis verified that TRIP13 and KIF14B were able to directly bind to each other. However, TRIP13 overexpression abolished the effects of KIF18B knockdown on HCC-1937 cells. Furthermore, KIF18B knockdown decreased β-catenin, c-Myc and cyclin D1 protein expression levels; however, TRIP13 overexpression resulted in the recovery of all respective protein expression levels. On the whole, the present study demonstrates that KIF18B promotes BC malignant events, including the proliferation, migration and invasion of TNBC cells. These results indicate that KIF18B may play an oncogenic role in BC by upregulating TRIP13 expression, thereby activating the Wnt/β-catenin signaling pathway.

Long Noncoding RNA HCG18 Promotes Malignant Phenotypes of Breast Cancer Cells via the HCG18/miR-103a-3p/UBE2O/mTORC1/HIF-1α-Positive Feedback Loop.

In recent years, an increasing number of studies have reported that long noncoding RNAs (lncRNAs) play crucial roles in breast cancer (BC) progression and metastasis. Another study group of our research center reported that lncRNA HCG18 was one of the 30 upregulated lncRNAs in BC tissues compared with normal tissues in The Cancer Genome Atlas database. However, the exact biological roles of HCG18 in BC remain unclear. In this study, we demonstrated that HCG18 is significantly upregulated in BC tissues and cells and that BC patients with high HCG18 expression tend to have poor prognosis. In vitro assays indicated that HCG18 promotes BC cell proliferation and invasion and endows BC cells with cancer stemness properties. In vivo assays revealed that reducing HCG18 expression in the BC cell line MDA-MB-231 markedly decreased tumor growth and lung metastasis in xenograft mouse models. In terms of mechanism, we found that HCG18 positively regulated the expression of BC-related ubiquitin-conjugating enzyme E2O (UBE2O) by sponging miR-103a-3p, and our previous research verified that UBE2O could promote the malignant phenotypes of BC cells through the UBE2O/AMPKα2/mTORC1 axis. Furthermore, as a downstream target of the HCG18/miR-103a-3p/UBE2O/mTORC1 axis, hypoxia-inducible factor 1α transcriptionally promoted HCG18 expression and then formed a positive feedback loop in BC. Taken together, these results confirm that HCG18 plays an oncogenic role in BC and might serve as a prognostic biomarker and a potential therapeutic target for BC treatment.

A Novel Circular RNA circPTCD3 Promotes Breast Cancer Progression Through Sponging miR-198.

IntroductionCircular RNAs (circRNAs), a new type of non-coding RNA, have been demonstrated to play critical roles in the progression of various of malignant cancers. However, the function of circRNAs in breast cancer is not clearly understood.MethodsqPCR was used to evaluate the gene expression. Function studies including MTT, transwell, wound healing and colony formation assay were performed to evaluate the function of circPTCD3 in breast cancer. Luciferase and RNA pull-down assays were used to verify the interaction between circPTCD3 and miR-198. The xenograft model was established to evaluate the function of circPTCD3 in vivo.ResultsIn the present study, we identified a novel circRNA termed as circPTCD3 which was indicated to be significantly up-regulated in breast cancer tissues and cell lines. The results revealed that ectopic expression of circPTCD3 promoted the cell proliferation, migration and colony formation ability of breast cancer cells. Constantly, silencing of circPTCD3 inhibited those of breast cancer cells. Furthermore, we identified that circPTCD3 was able to target miR-198 in breast cancer cell. miR-198 has the function of inhibiting proliferation and migration of breast cancer cells which can be reversed by circPTCD3.ConclusionTaken together, our findings for the first time identified a novel circRNA (circPTCD3) and revealed its oncogenic role in breast cancer. Mechanically, we reported that circPTCD3 served as a competing endogenous RNA (ceRNA) to sponge miR-198. These findings provide insights into breast cancer progression and also potential new targets for diagnosis or treatment of breast cancer.

Systematic dissection of transcriptional regulatory networks by genome-scale and single-cell CRISPR screens.

Millions of putative transcriptional regulatory elements (TREs) have been cataloged in the human genome, yet their functional relevance in specific pathophysiological settings remains to be determined. This is critical to understand how oncogenic transcription factors (TFs) engage specific TREs to impose transcriptional programs underlying malignant phenotypes. Here, we combine cutting edge CRISPR screens and epigenomic profiling to functionally survey ≈15,000 TREs engaged by estrogen receptor (ER). We show that ER exerts its oncogenic role in breast cancer by engaging TREs enriched in GATA3, TFAP2C, and H3K27Ac signal. These TREs control critical downstream TFs, among which TFAP2C plays an essential role in ER-driven cell proliferation. Together, our work reveals novel insights into a critical oncogenic transcription program and provides a framework to map regulatory networks, enabling to dissect the function of the noncoding genome of cancer cells.

Retraction.

Retraction: "Long noncoding RNA TALNEC2 plays an oncogenic role in breast cancer by binding to EZH2 to target p57KIP2 and involving in p-p38 MAPK and NF-κB pathways," by Enqi Qiao, Daobao Chen, Qinglin Li, Weiliang Feng, Xingfei Yu, Xiping Zhang, Liang Xia, Ju Jin, Hongjian Yang, J Cell Biochem. 2019; 3978-3988: The above article, published online on 30 October 2018 in Wiley Online Library (https://onlinelibrary.wiley.com/doi/abs/10.1002/jcb.27680), has been retracted by agreement between the the journal's Editor in Chief, Prof. Dr. Christian Behl, and Wiley Periodicals LLC. The retraction has been agreed following an investigation based on allegations raised by a third party. Several flaws and inconsistencies between results presented and experimental methods described were found, the editors consider the conclusions of this article to be invalid. The authors collaborated in the investigation initially, but were not available for a final confirmation of the retraction.

Evaluation of the use of long noncoding RNAs as biomarkers for diagnosis of breast cancer: Thesis Abstract

Background: FAM83H antisense RNA 1 (FAM83H-AS1) and long noncoding RNA activated by TGF β (lncRNA-ATB) are two lncRNAs that have tumor promoting functions in breast cancer (BC). Matrix metalloproteinase-9 (MMP-9) is another tumor marker that exerts an oncogenic role in BC and facilitate cancer invasion and metastasis. Aims: Our study aimed to 1) analyze serum levels of FAM83H-AS1, lncRNA-ATB, and MMP-9 in BC patients, 2) compare their diagnostic role with that of CA15-3 in BC patients with different stages (I-II, III, and IV), and 3) correlate the levels of the measured lncRNAs, MMP-9, and CA15-3 with the clinicopathological features of BC. Materials and Methods: Serum FAM83H-AS1 and lncRNA-ATB levels were analyzed in 90 BC patients and 30 healthy controls using RT-PCR. While serum levels of MMP-9 and CA15-3 were measured in the same studied groups by ELISA. Results: FAM83H-AS1, lncRNA-ATB, MMP-9, and CA15-3 levels were significantly elevated in sera of BC patients. ROC curve analysis showed that lncRNA-ATB and MMP-9 had higher AUC values than CA15-3 in diagnosis of stage I-II patients (AUC: 0.844 and 0.898, p= 0.000 for lncRNA-ATB and MMP-9, respectively versus 0.738, p= 0.002 for CA15-3). FAM83H-AS1 level was significantly correlated with higher stage, larger tumor size, positive lymph node metastasis, and distant metastasis. FAM83H-AS1 level was also significantly increased in PR-negative and ki67-rich tumors. Conclusion: Our study demonstrated that circulating lncRNA-ATB and MMP-9 could be used as diagnostic biomarkers for early BC. FAM83H-AS1 could also be a potential candidate for staging BC and monitoring disease progression.

Discovery and Pharmacological Evaluation of STEAP4 as a Novel Target for HER2 Overexpressing Breast Cancer.

Breast cancer (BC) is a highly heterogeneous disease encompassing multiple subtypes with different molecular and histopathological features, disease prognosis, and therapeutic responses. Among these, the Triple Negative BC form (TNBC) is an aggressive subtype with poor prognosis and therapeutic outcome. With respect to HER2 overexpressing BC, although advanced targeted therapies have improved the survival of patients, disease relapse and metastasis remains a challenge for therapeutic efficacy. In this study the aim was to identify key membrane-associated proteins which are overexpressed in these aggressive BC subtypes and can serve as potential biomarkers or drug targets. We leveraged on the development of a membrane enrichment protocol in combination with the global profiling GeLC-MS/MS technique, and compared the proteomic profiles of a HER2 overexpressing (HCC-1954) and a TNBC (MDA-MB-231) cell line with that of a benign control breast cell line (MCF-10A). An average of 2300 proteins were identified from each cell line, of which approximately 600 were membrane-associated proteins. Our global proteomic methodology in tandem with invigoration by Western blot and Immunofluorescence analysis, readily detected several previously-established BC receptors like HER2 and EPHA2, but importantly STEAP4 and CD97 emerged as novel potential candidate markers. This is the first time that the mitochondrial iron reductase STEAP4 protein up-regulation is linked to BC (HER2+ subtype), while for CD97, its role in BC has been previously described, but never before by a global proteomic technology in TNBC. STEAP4 was selected for further detailed evaluation by the employment of Immunohistochemical analysis of BC xenografts and clinical tissue microarray studies. Results showed that STEAP4 expression was evident only in malignant breast tissues whereas all the benign breast cases had no detectable levels. A functional role of STEAP4 intervention was established in HER2 overexpressing BC by pharmacological studies, where blockage of the STEAP4 pathway with an iron chelator (Deferiprone) in combination with the HER2 inhibitor Lapatinib led to a significant reduction in cell growth in vitro. Furthermore, siRNA mediated knockdown of STEAP4 also suppressed cell proliferation and enhanced the inhibition of Lapatinib in HER2 overexpressing BC, confirming its potential oncogenic role in BC. In conclusion, STEAP4 may represent a novel BC related biomarker and a potential pharmacological target for the treatment of HER2 overexpressing BC.

CircSKA3 Downregulates miR-1 Through Methylation in Glioblastoma to Promote Cancer Cell Proliferation.

BackgroundCircular RNA circSKA3 plays an oncogenic role in breast cancer, while its role in glioblastoma (GBM) is unknown. This study aimed to explore the role of circSKA3 in GBM.MethodsDifferential expression of circSKA3 and miR-1 in GBM and adjacent non-cancer tissue samples were analyzed by RT-qPCR. GBM cells were transfected with circSKA3 expression vector or miR-1 mimic, followed by RT-qPCR to explore the potential crosstalk between them. Methylation-specific PCR (MSP) was carried out to assess the role of circSKA3 in regulating the methylation of miR-1 gene. The role of circSKA3 and miR-1 in regulating GBM cell proliferation was analyzed by CCK-8 assay.ResultsWe found that circSKA3 was upregulated in GBM and inversely correlated with miR-1 across GBM tissues. High expression levels of circSKA3 and low expression levels of miR-1 were significantly correlated with the poor survival of GBM patients. In GBM cells, overexpression of circSKA3 increased the methylation of miR-1 gene and decreased the expression of miR-1. CCK-8 assay showed that overexpression of circSKA3 reduced the inhibitory effects of miR-1 on cell proliferation.ConclusionTherefore, circSKA3 may downregulate miR-1 through methylation in GBM to promote cancer cell proliferation.

BARD1 and Breast Cancer: The Possibility of Creating Screening Tests and New Preventive and Therapeutic Pathways for Predisposed Women.

Current oncological developments are based on improved understanding of genetics, and especially the discovery of genes whose alterations affect cell functions with consequences for the whole body. Our work is focused on the one of these genes, BRCA1-associated RING domain protein 1 (BARD1), and its oncogenic role in breast cancer. Most importantly, the study points to new avenues in the treatment and prevention of the most frequent female cancer based on BARD1 research. The BARD1 and BRCA1 (BReast CAncer type 1) proteins have similar structures and functions, and they combine to form the new molecule BARD1-BRCA1 heterodimer. The BARD1-BRCA1 complex is involved in genetic stabilization at the cellular level. It allows to mark abnormal DNA fragments by attaching ubiquitin to them. In addition, it blocks (by ubiquitination of RNA polymerase II) the transcription of damaged DNA. Ubiquitination, as well as stabilizing chromatin, or regulating the number of centrosomes, confirms the protective cooperation of BARD1 and BRCA1 in the stabilization of the genome. The overexpression of the oncogenic isoforms BARD1β and BARD1δ permit cancer development. The introduction of routine tests, for instance, to identify the presence of the BARD1β isoform, would make it possible to detect patients at high risk of developing cancer. On the other hand, introducing BARD1δ isoform blocking therapy, which would reduce estrogen sensitivity, may be a new line of cancer therapy with potential to modulate responses to existing treatments. It is possible that the BARD 1 gene offers new hope for improving breast cancer therapy.

Lysine demethylase 2A expression in cancer-associated fibroblasts promotes breast tumour growth

BackgroundOur previous study demonstrated that lysine demethylase 2A (KDM2A) enhances stemness in breast cancer cells. This demethylase is also highly expressed in cancer-associated fibroblasts (CAFs). However, its clinical significance is unclear.MethodsThe expression of KDM2A in CAFs was studied using immunohistochemical staining and its association with clinicopathological features and patient’s survival was tested. Overexpression and knockdown strategies were used to investigate KDM2A-regulated genes in fibroblasts. Senescent cells were detected by using β-galactosidase staining. The in vivo tumour-promoting activity of stromal KDM2A was confirmed by animal study.ResultsIncrease of stromal KDM2A is associated with advanced tumour stage and poor clinical outcome in breast cancer patients. Cancer-derived cytokines stimulated KDM2A expression in normal fibroblasts and transformed them into CAFs. Upregulation of KDM2A induced p53-dependent senescence in fibroblasts and enhanced the release of cytokines, which reciprocally promoted cancer cell proliferation. Additionally, KDM2A upregulated programmed death-ligand 1 (PD-L1) expression via transcriptional activation in fibroblasts. Knockdown of KDM2A completely abolished the tumour-promoting activity of CAFs on breast tumour growth in vivo and diminished PD-L1 expression in the stroma of tumour tissues.ConclusionsStromal KDM2A plays an oncogenic role in breast cancer and inhibition of KDM2A reduces fibroblast senescence and suppresses tumour growth.

LINC00657 knockdown suppresses hepatocellular carcinoma progression by sponging miR-424 to regulate PD-L1 expression.

Hepatocellular carcinoma (HCC) is the sixth most commonly diagnosed malignant tumor and the fourth leading cause of cancer-related deaths worldwide. As a novel non-coding RNA, LINC00657 was firstly identified as an oncogenic role in breast cancer. However, few research focus on the effect of LINC00657 on the progression of HCC. The purpose of this study was to investigate the effect of LINC00657 on HCC tissues and cells, and further explore the potential mechanism. We first measured the expression of LINC00657 in HCC tissues and cell lines using qRT-PCR. Next we established LINC00657 knockdown in HCC cells. CCK-8 assay, cell invasion assay, flow cytometry analysis, qRT-PCR and western blotting were applied to assess the role of LINC00657 knockdown in the biological behavior of HCC cells. The bioinformatics analysis and the rescue experiment were devoted to the underlying mechanism. LINC00657 was remarkably overexpressed in HCC tissues and cell lines, associated with poor prognosis. LINC00657 knockdown repressed cell proliferation and invasion, promoted cell apoptosis of HCC cell lines. The bioinformatics analysis showed LINC00657 sponged miR-424 as a ceRNA. Besides, PD-L1 mimic rescued the suppression of si-LINC00657 in the biological behavior of HCC cells. In a word, we observed LINC00657 regulated PD-L1 expression by sponging miR-424, thus affecting the developments of hepatocellular carcinoma. These findings LINC00657 may provide new evidence for therapeutic application in hepatocellular carcinoma.

A Novel Circular RNA hsa_circRPPH1_015 Exerts an Oncogenic Role in Breast Cancer by Impairing miRNA-326-Mediated ELK1 Inhibition.

Background: Breast cancer (BC) represents a heterogeneous disease with distinct subtypes and high tumor metastatic potentials. Recent researchers identify the implication of circular RNAs (circRNAs) in the initiation of BC. Herein, we uncover a novel circRNA hsa_circRPPH1_015 as a tumor promoter in BC.Methods: A total of 86 paired cancerous and non-cancerous tissues were surgically resected and collected from BC patients. Cell proliferation, colony formation, and cell invasion were examined by Edu staining, clone formation assays, propidium iodide (PI)-labeled flow cytometry, and Transwell invasion assays. PCNA, Ki67, MMP-2, MMP-9, Cyclin D1, and CDK4 expression was assayed using Western blot analysis. RNA pull-down, dual-luciferase reporter gene assay, and RNA binding protein immunoprecipitation (RIP) assay were performed to investigate the relationships among hsa_circRPPH1_015, microRNA-326 (miR-326), and ELK1. The tumor growth of human BC MCF-7 cells in vivo was evaluated in nude mice by subcutaneous xenografts of MCF-7 cells.Results: hsa_circRPPH1_015 expression was upregulated in BC tissues. Knockdown of hsa_circRPPH1_015 restrained the aggressive behavior of MCF-7. hsa_circRPPH1_015 could bind to miRNA-326 that negatively regulates ELK1. Elevation of miRNA-326 expression resulted in inhibition of cell proliferation, colony formation, and cell invasion of MCF-7. Disturbance of miRNA-326 or overexpression of ELK1 restored the proliferation and aggressiveness in hsa_circRPPH1_015-depleted MCF-7 cells. Tumor growth of MCF-7 cells in vivo was reduced in nude mice lack of endogenous hsa_circRPPH1_015 expression.Conclusion: Overall, the present study demonstrates that hsa_circRPPH1_015 was an oncogene and unfavorable prognostic factor in BC, providing an exquisite therapeutic target for BC.