bims-merabr 2024-07-21 papers

bims-merabr

Biomed News

on Metabolic rewiring in aggressive breast cancer

Issue of 2024‒07‒21
fifteen papers selected by
Barbara Mensah Sankofi, University of Oklahoma Health Sciences Center

TSP50 facilitates breast cancer stem cell-like properties maintenance and epithelial-mesenchymal transition via PI3K p110α mediated activation of AKT signaling pathway.
GAPVD1 Promotes the Proliferation of Triple-Negative Breast Cancer Cells by Regulating the ERK/MAPK Signaling Pathway.
A Novel Signature Based on Angiogenesis-Related Genes Predicts the Prognosis and Immunotherapy Response in HER2-Positive Breast Cancer.
Apolipoprotein L3 inhibits breast cancer proliferation and modulates cell cycle via the P53 pathway.
Induced expression of AMOT reverses adriamycin resistance in breast cancer cells.
The potential role of collagen type VII in breast cancer proliferation.
PKMYT1 knockdown inhibits cholesterol biosynthesis and promotes the drug sensitivity of triple-negative breast cancer cells to atorvastatin.
FABP4-mediated lipid accumulation and lipolysis in tumor associated macrophages promote breast cancer metastasis.
MAZ-mediated up-regulation of BCKDK reprograms glucose metabolism and promotes growth by regulating glucose-6-phosphate dehydrogenase stability in triple-negative breast cancer.
CCN6 suppresses metaplastic breast carcinoma by antagonizing WNT/β-catenin signaling to inhibit EZH2-driven EMT.
Targeting Cholesterol Biosynthesis with Statins Synergizes with AKT Inhibitors in Triple-Negative Breast Cancer.
Tumor suppressor KEAP1 promotes HSPA9 degradation, controlling mitochondrial biogenesis in breast cancer.
Oncogenic NOVA1 expression dysregulates alternative splicing in breast cancer.
MicroRNA-138 inhibits hypoxia-inducible factor 1α expression in breast cancer cells.
Genomic and transcriptomic profiling of inflammatory breast cancer reveals distinct molecular characteristics to non-inflammatory breast cancers.

J Exp Clin Cancer Res. 2024 Jul 20. 43(1): 201

TSP50 facilitates breast cancer stem cell-like properties maintenance and epithelial-mesenchymal transition via PI3K p110α mediated activation of AKT signaling pathway.

Feng Gao, Sichen Liu, Jing Wang, Gang Wei, Chunlei Yu, Lihua Zheng, Luguo Sun, Guannan Wang, Ying Sun, Yongli Bao, Zhenbo Song.

  BACKGROUND: Studies have confirmed that epithelial-mesenchymal transition (EMT) and cancer stem cell (CSC)-like properties are conducive to cancer metastasis. In recent years, testes-specific protease 50 (TSP50) has been identified as a prognostic factor and is involved in tumorigenesis regulation. However, the role and molecular mechanisms of TSP50 in EMT and CSC-like properties maintenance remain unclear.METHODS: The expression and prognostic value of TSP50 in breast cancer were excavated from public databases and explored using bioinformatics analysis. Then the expression of TSP50 and related genes was further validated by quantitative RT-PCR (qRT-PCR), Western blot, and immunohistochemistry (IHC). In order to investigate the function of TSP50 in breast cancer, loss- and gain-of-function experiments were conducted, both in vitro and in vivo. Furthermore, immunofluorescence (IF) and immunoprecipitation (IP) assays were performed to explore the potential molecular mechanisms of TSP50. Finally, the correlation between the expression of TSP50 and related genes in breast cancer tissue microarray and clinicopathological characteristics was analyzed by IHC.
RESULTS: TSP50 was negatively correlated with the prognosis of patients with breast cancer. TSP50 promoted CSC-like traits and EMT in both breast cancer cells and mouse xenograft tumor tissues. Additionally, inhibition of PI3K/AKT partly reversed TSP50-induced activation of CSC-like properties, EMT and tumorigenesis. Mechanistically, TSP50 and PI3K p85α regulatory subunit could competitively interact with the PI3K p110α catalytic subunit to promote p110α enzymatic activity, thereby activating the PI3K/AKT signaling pathway for CSC-like phenotypes maintenance and EMT promotion. Moreover, IHC analysis of human breast cancer specimens revealed that TSP50 expression was positively correlated with p-AKT and ALDH1 protein levels. Notably, breast cancer clinicopathological characteristics, such as patient survival time, tumor size, Ki67, pathologic stage, N stage, estrogen receptor (ER) and progesterone receptor (PR) levels, correlated well with TSP50/p-AKT/ALDH1 expression status.
CONCLUSION: The effects of TSP50 on EMT and CSC-like properties promotion were verified to be dependent on PI3K p110α. Together, our study revealed a novel mechanism by which TSP50 facilitates the progression of breast cancer, which can provide new insights into TSP50-based breast cancer treatment strategies.

Keywords:  Breast cancer; CSC-like properties; EMT; PI3K/AKT pathway; TSP50

DOI:  https://doi.org/10.1186/s13046-024-03118-4
Curr Cancer Drug Targets. 2024 Jul 15.

GAPVD1 Promotes the Proliferation of Triple-Negative Breast Cancer Cells by Regulating the ERK/MAPK Signaling Pathway.

Lu Wang, Lifen Zhang, Pei Luo, Zeyu Xia, Shan Shao, Qian Ning, Shanzhi Gu, Xinhan Zhao, Minna Luo.

  BACKGROUND: Triple-Negative Breast Cancer (TNBC) accounts for 15-20% of all breast cancers and approximately 50% of breast cancer deaths. Chemotherapy remains the mainstay of systemic treatment due to the lack of effective therapy targets. Thus, more studies are urgently needed to identify new therapeutic targets in TNBC patients.METHODS: GAPVD1 expression and prognosis value in breast cancer samples were explored in The Cancer Genome Atlas database (TCGA). GAPVD1 knockdown and overexpression TNBC cell lines were constructed. CCK-8 and colony formation assays were performed to detect cell viability. Flow cytometry analysis was performed to detect cell cycle variation. Western blotting was conducted to determine the levels of target genes. Finally, an enrichment analysis of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were performed.
RESULTS: GAPVD1 is overexpressed in breast cancer tissues and predicts poor prognosis. In vitro experiments demonstrated that GAPVD1 is correlated with cell proliferation and the cell cycle of TNBC cells. Mechanistically, alteration in GAPVD1 expression was found to be associated with cell cycle-related proteins PCNA, Cyclin A, and the activity of the ERK/MAPK signaling pathway. Consistent with these findings, enrichment analysis of GAPVD1-involving partners and signaling pathways revealed that the cellular biosynthetic process, macromolecule biosynthetic process, and cell cycle signaling are related to GAPVD1. In vivo experiment demonstrated that GAPVD1 inhibition impedes tumor growth and expression of cell cyclerelated proteins.
CONCLUSION: Taken together, our results indicate that GAPVD1 may participate in TNBC cell growth by regulating the cell cycle and ERK/MAPK signaling pathway.

Keywords:  ERK signaling pathway.; GAPVD1; Triple-negative breast cancer; cell proliferation

DOI:  https://doi.org/10.2174/0115680096303983240616191051
J Cancer. 2024 ;15(14): 4731-4748

A Novel Signature Based on Angiogenesis-Related Genes Predicts the Prognosis and Immunotherapy Response in HER2-Positive Breast Cancer.

Shuanglong Chen, Weiheng Cui, Jiale Dong, Wenyan Chen, Hongmei Dong, Ruijun Zhao.

  Background: HER2-positive breast cancer is one of the most prevalent subtypes of breast cancer and represents a significant health concern for women worldwide due to its high morbidity and mortality rates. Recent studies have consistently underscored the pivotal role of angiogenesis in the development and progression of HER2-positive breast cancer. Here, we developed a prognostic signature based on angiogenesis-related genes (ARGs) to categorize HER2-positive breast cancer patients and provide insights into their survival outcomes. Methods: Kaplan-Meier survival curve, time-dependent receiver operating characteristic (ROC) and nomogram were performed to investigate the prognostic performance of the signature. In addition, we comprehensively analyzed the correlation of the prognostic signature with immune cell infiltration, immune checkpoint inhibitors (ICIs) therapy. Finally, Immunohistochemistry (IHC) and immunoblotting were used to investigate XBP1 expression in HER2-positive breast cancer tissues. Colony formation assay was performed to examine cell proliferation of HER2-positive breast cancer cells. Results: The Kaplan-Meier curves and the ROC curves demonstrated that the ARGs had good performance in predicting the prognosis of HER2-positive breast cancer patients. In addition, we observed that the low-risk group was remarkably associated with immune infiltration and better response to ICIs. Further experimental results show that XBP1 is upregulated in human HER2-positive breast cancer, and its knockdown significantly inhibited cell proliferation. Conclusions: Our study demonstrated that the ARGs could serve as a novel biomarker for predicting the prognosis of patients with HER2-positive breast cancer and providing new insights into immunotherapy strategies for these patients.

Keywords:  HER2-positive breast cancer; angiogenesis-related gene signature; immune cell infiltration; immunotherapy; prognosis

DOI:  https://doi.org/10.7150/jca.94120
J Cancer. 2024 ;15(14): 4623-4635

Apolipoprotein L3 inhibits breast cancer proliferation and modulates cell cycle via the P53 pathway.

Hao Yu, Siyan Li, Xing Li, Yanbiao Liu, Zhaobu Wang, Mengyao Cui, Feng Jin, Xinmiao Yu.

  Background: Breast cancer is the second most common cause of cancer-related mortality globally. Apolipoprotein L3 (APOL3), a member of the apolipoprotein family, has been implicated in the pathogenesis of cardiovascular diseases. Nevertheless, the functions and underlying mechanisms of APOL3 in breast cancer have yet to be elucidated. Methods: The patient data were sourced from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) database. Quantitative real-time PCR (qRT-PCR), western blotting, and immunohistochemistry (IHC) assays were used to assess expression of APOL3. Cell proliferation rates were determined by Cell Counting Kit-8 (CCK-8) and colony formation assays. Flow cytometry was used to examine cell cycle distribution. Western blotting was conducted to investigate the expression of cell cycle related proteins. A xenograft model was used to evaluate the effect of APOL3 in vivo. APOL3-binding proteins were identified through mass spectrometry, co-immunoprecipitation (CO-IP) assay and immunofluorescence assay. Results: APOL3 expression was significantly downregulated in breast cancer, and its low expression was correlated with poor prognostic outcomes. Overexpression of APOL3 suppressed breast cancer cell proliferation, induced cell cycle disruption. Conversely, knockdown of APOL3 promoted cell proliferation. In vivo animal experiments demonstrated that APOL3 overexpression can inhibit tumor proliferation. Mass spectrometry, CO-IP and immunofluorescence assay confirmed the interaction between APOL3 and Y-box binding protein 1 (YBX1). Furthermore, YBX1 knockdown following APOL3 knockdown mitigated the enhanced proliferation. These results provide new ideas for clinically targeting APOL3 to inhibit proliferation in breast cancer. Conclusions: Our findings indicate that APOL3 inhibits breast cancer cell proliferation and cell cycle modulating P53 pathway through the interaction of YBX1.

Keywords:  Apolipoprotein; Breast cancer; Cell cycle; P53; Proliferation; Y-box binding protein 1

DOI:  https://doi.org/10.7150/jca.96903
Cell Biol Int. 2024 Jul 17.

Induced expression of AMOT reverses adriamycin resistance in breast cancer cells.

Haige Zhang, Yingyi Wang, Ya Gao, Mingming Du, Erhu Pan, Mingliang Sun, Xiaozhi Zhang.

  Adriamycin (ADR) is widely used against breast cancer, but subsequent resistance always occurs. YAP, a downstream protein of angiomotin (AMOT), importantly contributes to ADR resistance, whereas the mechanism is largely unknown. MCF-7 cells and MDA-MB-231 cells were used to establish ADR-resistant cell. Then, mRNA and protein expressions of AMOT and YAP expressions were determined. After AMOT transfection alone or in combination with YAP, the sensitivity of the cells to ADR were evaluated in vitro by examining cell proliferation, apoptosis, and cell cycle, as well as in vivo by examining tumor growth. Additionally, the expressions of proteins in YAP pathway were determined in AMOT-overexpressing cells. In the ADR-resistant cells, the expression of AMOT was decreased while YAP was increased, respectively, and the nucleus localization of YAP was increased at the same time. After AMOT overexpression, these were inhibited, whereas the cell sensitivity to ADR was enhanced. However, the AMOT-induced changes were significantly suppressed by YAP knockdown. The consistent results in vivo showed that AMOT enhanced the inhibition of ADR on tumor growth, and inhibited YAP signaling, evidenced by decreased levels of YAP, CycD1, and p-ERK. Our data revealed that decreased AMOT contributed to ADR resistance in breast cancer cells, which was importantly negatively mediated YAP. These observations provide a potential therapy against breast cancer with ADR resistance.

Keywords:  AMOT; YAP; adriamycin; breast cancer; drug resistance

DOI:  https://doi.org/10.1002/cbin.12198
Cancer Cell Int. 2024 Jul 20. 24(1): 254

The potential role of collagen type VII in breast cancer proliferation.

Sergio Pérez-Díaz, Jessica Lindberg, Luis Oliveros Anerillas, Paul J Kingham, Malin Sund, Gunilla Rask, Johan Svensson, Malin Jansson, Rebecca Wiberg.

  BACKGROUND: Breast cancer is the most common cancer in women. Cancer cells can persist in a prolonged dormant state for years without any clinical evidence of disease creating an urgent need to better understand the molecular mechanisms leading to relapse. This study aimed to identify extracellular matrix (ECM) components associated with hypoxia-induced breast cancer dormancy. The effects of selected ECM proteins on breast cancer cell proliferation were analyzed, along with their correlation with established prognostic markers in human breast cancer tissue.MATERIALS AND METHODS: Screening of extracellular matrix proteins was performed in hypoxia-induced dormant MCF-7 breast cancer cells. Proliferation of MCF-7 cells in vitro was subsequently determined in the presence of recombinant ColVII. Adipose tissue-derived mesenchymal stem cells (AdMSCs) subpopulation overexpressing ColVII were indirectly isolated by ColVII receptor integrin-α6 specific antibodies. AdMSCs- MCF-7 3D spheroid cultures were generated to model solid tumour conditions. In addition, the association between ColVII and various prognostic markers was evaluated in clinical samples of human breast cancer tissue.
RESULTS: Dormant MCF-7 cells showed an elevated expression of ColVII while MCF-7 cells cultured on ColVII exhibited reduced proliferation in vitro. In AdMSCs-MCF-7 3D spheroids, a reduced proliferation of MCF-7 cells was observed in Int-α6+/ ColVIIhigh compared with Int-α6-/ ColVIIlow AdMSCs spheroids. In human tissue, high ColVII expression correlated to several positive prognostic markers. Staining for Cytokeratin-5 revealed that ColVIIhigh-expressing cells were predominantly myoepithelial cells.
CONCLUSION: ColVII is associated with reduced proliferation of breast cancer cells in vitro. ColVII is strongly expressed in myoepithelial cells and in breast cancer tissue the high ColVII expression correlates with several well-known positive prognostic markers, highlighting its potential as a prognostic marker in breast cancer.

Keywords:  Breast cancer; Collagen type VII; Extracellular matrix; Mesenchymal stem cell

DOI:  https://doi.org/10.1186/s12935-024-03449-4
PeerJ. 2024 ;12 e17749

PKMYT1 knockdown inhibits cholesterol biosynthesis and promotes the drug sensitivity of triple-negative breast cancer cells to atorvastatin.

Wei Gao, Xin Guo, Linlin Sun, Jinwei Gai, Yinan Cao, Shuqun Zhang.

  Triple negative breast cancer (TNBC) as the most aggressive molecular subtype of breast cancer is characterized by high cancer cell proliferation and poor patient prognosis. Abnormal lipid metabolism contributes to the malignant process of cancers. Study observed significantly enhanced cholesterol biosynthesis in TNBC. However, the mechanisms underlying the abnormal increase of cholesterol biosynthesis in TNBC are still unclear. Hence, we identified a member of the serine/threonine protein kinase family PKMYT1 as a key driver of cholesterol synthesis in TNBC cells. Aberrantly high-expressed PKMYT1 in TNBC was indicative of unfavorable prognostic outcomes. In addition, PKMYT1 promoted sterol regulatory element-binding protein 2 (SREBP2)-mediated expression of enzymes related to cholesterol biosynthesis through activating the TNF/ TNF receptor-associated factor 1 (TRAF1)/AKT pathway. Notably, downregulation of PKMYT1 significantly inhibited the feedback upregulation of statin-mediated cholesterol biosynthesis, whereas knockdown of PKMYT1 promoted the drug sensitivity of atorvastatin in TNBC cells. Overall, our study revealed a novel function of PKMYT1 in TNBC cholesterol biosynthesis, providing a new target for targeting tumor metabolic reprogramming in the cancer.

Keywords:  Atorvastatin; Lipid metabolism; PKMYT1; TNF/TRAF1/AKT pathway; Triple-negative breast cancer

DOI:  https://doi.org/10.7717/peerj.17749
bioRxiv. 2024 Jul 04. pii: 2024.07.02.601733. [Epub ahead of print]

FABP4-mediated lipid accumulation and lipolysis in tumor associated macrophages promote breast cancer metastasis.

Matthew Yorek, Xingshan Jiang, Shanshan Liu, Jiaqing Hao, Jianyu Yu, Anthony Avellino, Zhanxu Liu, Melissa Curry, Henry Keen, Jianqiang Shao, Anand Kanagasabapathy, Maiying Kong, Yiqin Xiong, Edward R Sauter, Sonia L Sugg, Bing Li.

A high density of tumor-associated macrophages (TAMs) is associated with poorer prognosis and survival in breast cancer patients. Recent studies have shown that lipid accumulation in TAMs can promote tumor growth and metastasis in various models. However, the specific molecular mechanisms that drive lipid accumulation and tumor progression in TAMs remain largely unknown. Herein, we demonstrated that unsaturated fatty acids (FAs), unlike saturated ones, are more likely to form lipid droplets in macrophages. Specifically, unsaturated FAs, including linoleic acids (LA), activate the FABP4/CEBPα pathway, leading to triglyceride synthesis and lipid droplet formation. Furthermore, FABP4 enhances lipolysis and FA utilization by breast cancer cells, which promotes cancer cell migration in vitro and metastasis in vivo . Notably, a deficiency of FABP4 in macrophages significantly reduces LA-induced lipid metabolism. Therefore, our findings suggest FABP4 as a crucial lipid messenger that facilitates unsaturated FA-mediated lipid accumulation and lipolysis in TAMs, thus contributing to the metastasis of breast cancer.Graphic Abstract:
Highlights: Unlike saturated fatty acids, unsaturated fatty acids preferentially promote lipid droplet formation in macrophages.Unsaturated fatty acids activate the FABP4/CEBPα axis for neutral lipid biosynthesis in macrophagesDeficiency of FABP4 compromised unsaturated fatty acid-mediated lipid accumulation and utilization in macrophagesFABP4-mediated lipid metabolism in macrophages contributes to breast cancer metastasis.

DOI: https://doi.org/10.1101/2024.07.02.601733
Cell Death Dis. 2024 Jul 18. 15(7): 516

MAZ-mediated up-regulation of BCKDK reprograms glucose metabolism and promotes growth by regulating glucose-6-phosphate dehydrogenase stability in triple-negative breast cancer.

Yan Li, Yuxiang Lin, Yali Tang, Meichen Jiang, Xiaobin Chen, Hanxi Chen, Qian Nie, Jinqiao Wu, Xin Tong, Jing Li, Liuwen Yu, Jialin Hou, Wenhui Guo, Lili Chen, Minyan Chen, Jie Zhang, Shuhai Lin, Fangmeng Fu, Chuan Wang.

Tumour metabolic reprogramming is pivotal for tumour survival and proliferation. Investigating potential molecular mechanisms within the heterogeneous and clinically aggressive triple-negative breast cancer (TNBC) subtype is essential to identifying novel therapeutic targets. Accordingly, we investigated the role of branched-chain α-keto acid dehydrogenase kinase (BCKDK) in promoting tumorigenesis in TNBC. We analysed The Cancer Genome Atlas dataset and immunohistochemically stained surgical specimens to investigate BCKDK expression and its prognostic implications in TNBC. The effects of BCKDK on tumorigenesis were assessed using cell viability, colony formation, apoptosis, and cell cycle assays, and subsequently validated in vivo. Metabolomic screening was performed via isotope tracer studies. The downstream target was confirmed using mass spectrometry and a co-immunoprecipitation experiment coupled with immunofluorescence analysis. Upstream transcription factors were also examined using chromatin immunoprecipitation and luciferase assays. BCKDK was upregulated in TNBC tumour tissues and associated with poor prognosis. BCKDK depletion led to reduced cell proliferation both in vitro and vivo. MYC-associated zinc finger protein (MAZ) was confirmed as the major transcription factor directly regulating BCKDK expression in TNBC. Mechanistically, BCKDK interacted with glucose-6-phosphate dehydrogenase (G6PD), leading to increased flux in the pentose phosphate pathway for macromolecule synthesis and detoxification of reactive oxygen species. Forced expression of G6PD rescued the growth defect in BCKDK-deficient cells. Notably, the small-molecule inhibitor of BCKDK, 3,6-dichlorobenzo(b)thiophene-2-carboxylic acid, exhibited anti-tumour effects in a patient-derived tumour xenograft model. Our findings hold significant promise for developing targeted therapies aimed at disrupting the MAZ/BCKDK/G6PD signalling pathway, offering potential advancements in treating TNBC through metabolic reprogramming.

DOI: https://doi.org/10.1038/s41419-024-06835-y
Cancer Res. 2024 Jul 18.

CCN6 suppresses metaplastic breast carcinoma by antagonizing WNT/β-catenin signaling to inhibit EZH2-driven EMT.

Maria E Gonzalez, Bryce Brophy, Ahmad Eido, Adele E Leonetti, Sabra I Djomehri, Giuseppina Augimeri, Nicholas J Carruthers, Raymond G Cavalcante, Francesca Giordano, Sebastiano Andò, Alexey I Nesvizhskii, Eric R Fearon, Celina G Kleer.

Metaplastic breast carcinomas (mBrCAs) are a highly aggressive subtype of triple negative breast cancer (TNBC) with histological evidence of epithelial to mesenchymal transition (EMT) and aberrant differentiation. Inactivation of the tumor suppressor gene CCN6 (also known as WISP3) is a feature of mBrCAs, and mice with conditional inactivation of Ccn6 in mammary epithelium (Ccn6-KO) develop spindle mBrCAs with EMT. Elucidation of the precise mechanistic details of how CCN6 acts as a tumor suppressor in mBrCA could help identify improved treatment strategies. Here, we showed that CCN6 interacts with the Wnt receptor FZD8 and co-receptor LRP6 on mBrCA cells to antagonize Wnt-induced activation of β-catenin/TCF-mediated transcription. The histone methyltransferase EZH2 was identified as a β-catenin/TCF transcriptional target in Ccn6-KO mBrCA cells. Inhibiting Wnt/β-catenin/TCF signaling in Ccn6-KO mBrCa cells led to reduced EZH2 expression, decreased histone H3 lysine 27 trimethylation, and deregulation of specific target genes. Pharmacological inhibition of EZH2 reduced growth and metastasis of Ccn6-KO mBrCA mammary tumors in vivo. Low CCN6 is significantly associated with activated β-catenin and high EZH2 in human spindle mBrCAs compared to other subtypes. Collectively, these findings establish CCN6 as a key negative regulator of a β-catenin/TCF-EZH2 axis and highlight inhibition of β-catenin or EZH2 as a potential therapeutic approach for patients with spindle mBrCAs.

DOI: https://doi.org/10.1158/0008-5472.CAN-23-4054
Cancer Res. 2024 Jul 18.

Targeting Cholesterol Biosynthesis with Statins Synergizes with AKT Inhibitors in Triple-Negative Breast Cancer.

Alissandra L Hillis, Timothy D Martin, Haley E Manchester, Jenny Högström, Na Zhang, Emmalyn Lecky, Nina Kozlova, Jonah Lee, Nicole S Persky, David E Root, Myles Brown, Karen Cichowski, Stephen J Elledge, Taru Muranen, David A Fruman, Simon T Barry, John G Clohessy, Ralitsa R Madsen, Alex Toker.

Triple-negative breast cancer (TNBC) is responsible for a disproportionate number of breast cancer patient deaths due to extensive molecular heterogeneity, high recurrence rates and lack of targeted therapies. Dysregulation of the phosphoinositide 3-kinase (PI3K)/AKT pathway occurs in approximately 50% of TNBC patients. Here, we performed a genome-wide CRISPR/Cas9 screen with PI3Kα and AKT inhibitors to find targetable synthetic lethalities in TNBC. Cholesterol homeostasis was identified as a collateral vulnerability with AKT inhibition. Disruption of cholesterol homeostasis with pitavastatin synergized with AKT inhibition to induce TNBC cytotoxicity in vitro, in mouse TNBC xenografts and in patient-derived, estrogen receptor (ER)-negative breast cancer organoids. Neither ER-positive breast cancer cell lines nor ER-positive organoids were sensitive to combined AKT inhibitor and pitavastatin. Mechanistically, TNBC cells showed impaired sterol regulatory element-binding protein 2 (SREBP-2) activation in response to single agent or combination treatment with AKT inhibitor and pitavastatin, which was rescued by inhibition of the cholesterol trafficking protein Niemann-Pick C1 (NPC1). NPC1 loss caused lysosomal cholesterol accumulation, decreased endoplasmic reticulum cholesterol levels, and promoted SREBP-2 activation. Taken together, these data identify a TNBC-specific vulnerability to the combination of AKT inhibitors and pitavastatin mediated by dysregulated cholesterol trafficking. These findings support combining AKT inhibitors with pitavastatin as a therapeutic modality in TNBC. .

DOI: https://doi.org/10.1158/0008-5472.CAN-24-0970
Cell Rep. 2024 Jul 13. pii: S2211-1247(24)00836-2. [Epub ahead of print]43(7): 114507

Tumor suppressor KEAP1 promotes HSPA9 degradation, controlling mitochondrial biogenesis in breast cancer.

Bing Han, Fang Zhen, Yue Sun, Bin Sun, Hong-Yi Wang, Wei Liu, Jian Huang, Xiao Liang, Ya-Ru Wang, Xue-Song Chen, Shui-Jie Li, Jing Hu.

  The oxidative-stress-related protein Kelch-like ECH-associated protein 1 (KEAP1) is a substrate articulator of E3 ubiquitin ligase, which plays an important role in the ubiquitination modification of proteins. However, the function of KEAP1 in breast cancer and its impact on the survival of patients with breast cancer remain unclear. Our study demonstrates that KEAP1, a positive prognostic factor, plays a crucial role in regulating cell proliferation, apoptosis, and cell cycle transition in breast cancer. We investigate the underlying mechanism using human tumor tissues, high-throughput detection technology, and a mouse xenograft tumor model. KEAP1 serves as a key regulator of cellular metabolism, the reprogramming of which is one of the hallmarks of tumorigenesis. KEAP1 has a significant effect on mitochondrial biogenesis and oxidative phosphorylation by regulating HSPA9 ubiquitination and degradation. These results suggest that KEAP1 could serve as a potential biomarker and therapeutic target in the treatment of breast cancer.

Keywords:  CP: Cancer; CP: Cell biology

DOI:  https://doi.org/10.1016/j.celrep.2024.114507
bioRxiv. 2024 Jul 10. pii: 2024.07.08.602566. [Epub ahead of print]

Oncogenic NOVA1 expression dysregulates alternative splicing in breast cancer.

Daniel F Moakley, Chaolin Zhang.

Neuro-Oncological Ventral Antigen 1 ( NOVA1 ) is best known for its role in mediating an alternative splicing (AS) program in neurons, yet was first discovered as an antigen expressed in breast tumors, causing rare autoimmune reactions and paraneoplastic neurological disorders (PNDs). The PND model suggests a plausible role of the tumor antigen expression in tumor suppression, whereas it has emerged that NOVA may function as an oncogene in a variety of cancers. In addition, whether NOVA mediates AS in breast cancer remains unanswered. Here we examine the AS profiles of breast invasive carcinoma (BRCA) tumor samples and demonstrate that ectopic NOVA1 expression led to the activation of neuron-like splicing patterns in many genes, including exons targeted by NOVA in the brain. The splicing dysregulation is especially prevalent in cell periphery and cytoskeleton genes related to cell-cell communication, actin-based movement, and neuronal functions. We find that NOVA1-mediated AS is most prominent in Luminal A tumors and high NOVA1 expression in this subtype is associated with poorer prognosis. Our results suggest that ectopic NOVA1 in tumors has regulatory activity affecting pathways with high relevance to tumor progression and that this might be a more general mechanism for PND antigens.

DOI: https://doi.org/10.1101/2024.07.08.602566
Nucleosides Nucleotides Nucleic Acids. 2024 Jul 14. 1-16

MicroRNA-138 inhibits hypoxia-inducible factor 1α expression in breast cancer cells.

Mohammad Fayyad-Kazan, Rim ElDirani, Michella Ghassibe-Sabbagh, Eva Hamade, Nader Hadifeh, Rania El Majzoub, Hussein Fayyad-Kazan, Bassam Badran.

  BACKGROUND: Hypoxia, a critical feature during cancer development, leads to the stabilization and activation of the hypoxia-inducible factor 1-alpha (HIF-1α) to drive the expression of many target genes which in turn can promote many aspects of breast cancer biology, mainly metastasis and resistance to therapy. MicroRNAs are known to modulate the expression of many genes involved in breast cancer tumorigenesis. In this study, we examined the regulatory effect of miRNAs on HIF1α expression.METHODS: MCF-7 and MDA-MB-231 were cultivated under normoxia or hypoxia conditions. TaqMan-Low Density Array (TLDA) was used to characterize the miRNA signatures. Wild-Type (WT) or mutated fragments of HIF-1α 3'UTR containing the miR-138 potential target site were cloned downstream of the Renilla luciferase gene in the psiCHECK-1 plasmid. Luciferase assays were then carried out. A lentiviral vector containing copGFP as a reporter gene was prepared and transduced into MCF-7 and MDA-MB-231 cells to assess the effect of identified deregulated miRNAs on HIF-1α expression.
RESULTS: Under hypoxic conditions, MCF-7 cells showed deregulated expression for 12 miRNAs. In the case of MDA-MB-231 cells, 16 miRNAs were deregulated in response to hypoxia. Interestingly, miR-138 that was downregulated in both MCF-7 and MDA-MB-231 cells cultivated under hypoxic conditions appeared to have a binding site in 3'UTR of HIF-1α. Moreover, our results indicated that miR-138 could down regulate HIF-1α expression, upon binding directly to its 3'UTR.
CONCLUSIONS: Interestingly, our data highlights miR-138 as a potential therapeutic target to reduce HIF-1α expression and subsequently restrain breast cancer invasion and metastasis.

Keywords:  Breast cancer; HIF-1α; hypoxia; miRNAs

DOI:  https://doi.org/10.1080/15257770.2024.2351134
Breast Cancer Res Treat. 2024 Jul 19.

Genomic and transcriptomic profiling of inflammatory breast cancer reveals distinct molecular characteristics to non-inflammatory breast cancers.

Kaiwen Zhou, Mengmeng Zhang, Duanyang Zhai, Zilin Wang, Ting Liu, Yubin Xie, Yawei Shi, Huijuan Shi, Qianjun Chen, Xiaoping Li, Juan Xu, Zhenhai Cai, Yunjian Zhang, Nan Shao, Ying Lin.

  PURPOSE: Inflammatory breast cancer (IBC), a rare and highly aggressive form of breast cancer, accounts for 10% of breast cancer-related deaths. Previous omics studies of IBC have focused solely on one of genomics or transcriptomics and did not discover common differences that could distinguish IBC from non-IBC.METHODS: Seventeen IBC patients and five non-IBC patients as well as additional thirty-three Asian breast cancer samples from TCGA-BRCA were included for the study. We performed whole-exon sequencing (WES) to investigate different somatic genomic alterations, copy number variants, and large structural variants between IBC and non-IBC. Bulk RNA sequencing (RNA-seq) was performed to examine the differentially expressed genes, pathway enrichment, and gene fusions. WES and RNA-seq data were further investigated in combination to discover genes that were dysregulated in both genomics and transcriptomics.
RESULTS: Copy number variation analysis identified 10 cytobands that showed higher frequency in IBC. Structural variation analysis showed more frequent deletions in IBC. Pathway enrichment and immune infiltration analysis indicated increased immune activation in IBC samples. Gene fusions including CTSC-RAB38 were found to be more common in IBC. We demonstrated more commonly dysregulated RAS pathway in IBC according to both WES and RNA-seq. Inhibitors targeting RAS signaling and its downstream pathways were predicted to possess promising effects in IBC treatment.
CONCLUSION: We discovered differences unique in Asian women that could potentially explain IBC etiology and presented RAS signaling pathway as a potential therapeutic target in IBC treatment.

Keywords:  Bulk RNA sequencing (RNA-seq); Inflammatory breast cancer (IBC); Whole-exome sequencing (WES)

DOI:  https://doi.org/10.1007/s10549-024-07437-0