Rad51 Silencing with siRNA Delivered by Porous Silicon-Based Microparticle Enhances the Anti-Cancer Effect of Doxorubicin in Triple-Negative Breast Cancer

2021 ◽  
Vol 17 (12) ◽  
pp. 2351-2363
Author(s):  
Zeliang Wu ◽  
Lin Zhu ◽  
Junhua Mai ◽  
Haifa Shen ◽  
Rong Xu
Keyword(s):  
Breast Cancer ◽  
Dna Damage ◽  
Porous Silicon ◽  
Lung Metastasis ◽  
Triple Negative Breast Cancer ◽  
Triple Negative ◽  
Antitumor Effects ◽  
Mesenchymal Transition ◽  
Tnbc Cell

Due to its high heterogeneity and aggressiveness, cytotoxic chemotherapy is still a mainstay treatment for triple negative breast cancer. Unfortunately, the above mentioned has not significantly ameliorated TNBC patients and induces drug resistance. Exploring the mechanisms underlying the chemotherapy sensitivity of TNBC and developing novel sensitization strategies are promising approaches for improving the prognosis of patients. Rad51, a key regulator of DNA damage response pathway, repairs DNA damage caused by genotoxic agents through “homologous recombination repair.” Therefore, Rad51 inhibition may increase TNBC cell sensitivity to anticancer agents. Based on these findings, we first designed Rad51 siRNA to inhibit the Rad51 protein expression in vitro and evaluated the sensitivity of TNBC cells to doxorubicin. Subsequently, we constructed discoidal porous silicon microparticles (pSi) and encapsulated discoidal 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) liposomes/siRad51 (PS-DOPC/siRad51) to explore the synergistic antitumor effects of siRad51 and doxorubicin on two mouse models of TNBC in vivo. Our in vitro studies indicated that siRad51 enhanced the efficacy of DOX chemotherapy and significantly suppressed TNBC cell proliferation and metastasis. This effect was related to apoptosis induction and epithelial to mesenchymal transition (EMT) inhibition. siRad51 altered the expression of apoptosis- and EMT-related proteins. In orthotopic and lung metastasis xenograft models, the administration of PS-DOPC/siRad51 in combination with DOX significantly alleviated the primary tumor burden and lung metastasis, respectively. Our current studies present an efficient strategy to surmount chemotherapy resistance in TNBC through microvector delivery of siRad51.

scholarly journals Efficacy and mechanism of the combination of PARP and CDK4/6 inhibitors in the treatment of triple-negative breast cancer

2021 ◽  
Vol 40 (1) ◽  
Author(s):  
Xiuzhi Zhu ◽  
Li Chen ◽  
Binhao Huang ◽  
Xiaoguang Li ◽  
Liu Yang ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Dna Damage ◽  
Cell Lines ◽  
Triple Negative Breast Cancer ◽  
Triple Negative ◽  
Single Agent ◽  
Wnt Signalling ◽  
Tnbc Cell

Abstract Background PARP inhibitors (PARPi) benefit only a fraction of breast cancer patients with BRCA mutations, and their efficacy is even more limited in triple-negative breast cancer (TNBC) due to clinical primary and acquired resistance. Here, we found that the efficacy of the PARPi olaparib in TNBC can be improved by combination with the CDK4/6 inhibitor (CDK4/6i) palbociclib. Methods We screened primary olaparib-sensitive and olaparib-resistant cell lines from existing BRCAmut/TNBC cell lines and generated cells with acquired olaparib resistance by gradually increasing the concentration. The effects of the PARPi olaparib and the CDK4/6i palbociclib on BRCAmut/TNBC cell lines were examined in both sensitive and resistant cells in vitro and in vivo. Pathway and gene alterations were assessed mechanistically and pharmacologically. Results We demonstrated for the first time that the combination of olaparib and palbociclib has synergistic effects against BRCAmut/TNBC both in vitro and in vivo. In olaparib-sensitive MDA-MB-436 cells, the single agent olaparib significantly inhibited cell viability and affected cell growth due to severe DNA damage. In olaparib-resistant HCC1937 and SUM149 cells, single-agent olaparib was ineffective due to potential homologous recombination (HR) repair, and the combination of olaparib and palbociclib greatly inhibited HR during the G2 phase, increased DNA damage and inhibited tumour growth. Inadequate DNA damage caused by olaparib activated the Wnt signalling pathway and upregulated MYC. Further experiments indicated that the overexpression of β-catenin, especially its hyperphosphorylation at the Ser675 site, activated the Wnt signalling pathway and mediated olaparib resistance, which could be strongly inhibited by combined treatment with palbociclib. Conclusions Our data provide a rationale for clinical evaluation of the therapeutic synergy of the PARPi olaparib and CDK4/6i palbociclib in BRCAmut/TNBCs with high Wnt signalling activation and high MYC expression that do not respond to PARPi monotherapy.

scholarly journals CX-5461 Enhances the Efficacy of APR-246 via Induction of DNA Damage and Replication Stress in Triple-Negative Breast Cancer

2021 ◽  
Vol 22 (11) ◽  
pp. 5782
Author(s):  
Ashwini Makhale ◽  
Devathri Nanayakkara ◽  
Prahlad Raninga ◽  
Kum Kum Khanna ◽  
Murugan Kalimutho
Keyword(s):  
Breast Cancer ◽  
Dna Damage ◽  
Triple Negative Breast Cancer ◽  
Combination Treatment ◽  
Triple Negative ◽  
Annexin V ◽  
Replication Stress ◽  
Breast Cancer Cell Lines ◽  
Combination Strategy

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer lacking targeted therapy. Here, we evaluated the anti-cancer activity of APR-246, a P53 activator, and CX-5461, a RNA polymerase I inhibitor, in the treatment of TNBC cells. We tested the efficacy of individual and combination therapy of CX-5461 and APR-246 in vitro, using a panel of breast cancer cell lines. Using publicly available breast cancer datasets, we found that components of RNA Pol I are predominately upregulated in basal-like breast cancer, compared to other subtypes, and this upregulation is associated with poor overall and relapse-free survival. Notably, we found that the treatment of breast cancer cells lines with CX-5461 significantly hampered cell proliferation and synergistically enhanced the efficacy of APR-246. The combination treatment significantly induced apoptosis that is associated with cleaved PARP and Caspase 3 along with Annexin V positivity. Likewise, we also found that combination treatment significantly induced DNA damage and replication stress in these cells. Our data provide a novel combination strategy by utilizing APR-246 in combination CX-5461 in killing TNBC cells that can be further developed into more effective therapy in TNBC therapeutic armamentarium.

scholarly journals Overexpression of SERPINA3 promotes tumor invasion and migration, epithelial-mesenchymal-transition in triple-negative breast cancer cells

Breast Cancer ◽  
2021 ◽  
Author(s):  
Yingzi Zhang ◽  
Jiao Tian ◽  
Chi Qu ◽  
Yang Peng ◽  
Jinwei Lei ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cell Proliferation ◽  
Cell Lines ◽  
Triple Negative Breast Cancer ◽  
Triple Negative ◽  
Epithelial Mesenchymal Transition ◽  
Cell Counting ◽  
Migration And Invasion ◽  
Mesenchymal Transition ◽  
Tnbc Cell

Abstract Background Recent studies have indicated that serpin peptidase inhibitor, clade A, member 3 (SERPINA3) is a potential marker associated with tumor progression, which connoted that SERPINA3 is related to malignant phenotypes in cancer. However, the biological function of SERPINA3 in breast cancer (BC) remains unclear. Methods Bioinformatics data were downloaded from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. Immunohistochemical staining (IHC) was conducted to determine SERPINA3 expression. With strong aggressive abilities, triple-negative breast cancer (TNBC) cell lines (MDA-MB-231, BT549 and MDA-MB-436) were obtained to examine SERPINA3 expression and functions. Wound healing and Transwell assays were performed to measure cell migration and invasion. Cell Counting Kit-8 (CCK-8) assay was conducted to detect cell proliferation abilities and cell viabilities. Results SERPINA3 was upregulated in BC tissues. Functional assays suggested that overexpression of SERPINA3 significantly promoted cell proliferation, where migration and invasion of TNBC cells were accelerated. Knockdown of SERPINA3 had the opposite effects. These results causing by overexpression of SERPINA3 were also confirmed in non-TNBC cell lines. Overexpression of SERPINA3 remarkably enhanced the epithelial–mesenchymal transition (EMT) by upregulating the EMT markers and EZH2. In addition, the overexpression of SERPINA3 reduced the sensitivity of TNBC cells to cisplatin. Conclusion SERPINA3 can regulate the migration, invasion and EMT of TNBC cells and increased expression of SERPINA3 confers resistance to cisplatin in TNBC cells. We discern it is required for the regulation of BC progression and is a critical target for the clinical treatment of BC.

scholarly journals CD73 facilitates EMT progression and promotes lung metastases in triple-negative breast cancer

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Nataliia Petruk ◽  
Sanni Tuominen ◽  
Malin Åkerfelt ◽  
Jesse Mattsson ◽  
Jouko Sandholm ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Triple Negative Breast Cancer ◽  
Triple Negative ◽  
Epithelial Mesenchymal Transition ◽  
Lung Metastases ◽  
Vimentin Expression ◽  
Mesenchymal Transition ◽  
Cell Protrusion

AbstractCD73 is a cell surface ecto-5′-nucleotidase, which converts extracellular adenosine monophosphate to adenosine. High tumor CD73 expression is associated with poor outcome among triple-negative breast cancer (TNBC) patients. Here we investigated the mechanisms by which CD73 might contribute to TNBC progression. This was done by inhibiting CD73 with adenosine 5′-(α, β-methylene) diphosphate (APCP) in MDA-MB-231 or 4T1 TNBC cells or through shRNA-silencing (sh-CD73). Effects of such inhibition on cell behavior was then studied in normoxia and hypoxia in vitro and in an orthotopic mouse model in vivo. CD73 inhibition, through shRNA or APCP significantly decreased cellular viability and migration in normoxia. Inhibition of CD73 also resulted in suppression of hypoxia-induced increase in viability and prevented cell protrusion elongation in both normoxia and hypoxia in cancer cells. Sh-CD73 4T1 cells formed significantly smaller and less invasive 3D organoids in vitro, and significantly smaller orthotopic tumors and less lung metastases than control shRNA cells in vivo. CD73 suppression increased E-cadherin and decreased vimentin expression in vitro and in vivo, proposing maintenance of a more epithelial phenotype. In conclusion, our results suggest that CD73 may promote early steps of tumor progression, possibly through facilitating epithelial–mesenchymal transition.

scholarly journals CircNR3C2 promotes HRD1-mediated tumor-suppressive effect via sponging miR-513a-3p in triple-negative breast cancer

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Ya Fan ◽  
Jia Wang ◽  
Wen Jin ◽  
Yifei Sun ◽  
Yuemei Xu ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Rna Sequencing ◽  
Cancer Progression ◽  
Triple Negative Breast Cancer ◽  
Triple Negative ◽  
Proteasomal Degradation ◽  
Circular Rnas ◽  
Mesenchymal Transition

Abstract Background E3 ubiquitin ligase HRD1 (HMG-CoA reductase degradation protein 1, alias synoviolin with SYVN1 as the official gene symbol) was found downregulated and acting as a tumor suppressor in breast cancer, while the exact expression profile of HRD1 in different breast cancer subtypes remains unknown. Recent studies characterized circular RNAs (circRNAs) playing an regulatory role as miRNA sponge in tumor progression, presenting a new viewpoint for the post-transcriptional regulation of cancer-related genes. Methods Examination of the expression of HRD1 protein and mRNA was implemented using public microarray/RNA-sequencing datasets and breast cancer tissues/cell lines. Based on public RNA-sequencing results, online databases and enrichment/clustering analyses were used to predict the specific combinations of circRNA/miRNA that potentially govern HRD1 expression. Gain-of-function and rescue experiments in vitro and in vivo were executed to evaluate the suppressive effects of circNR3C2 on breast cancer progression through HRD1-mediated proteasomal degradation of Vimentin, which was identified using immunoblotting, immunoprecipitation, and in vitro ubiquitination assays. Results HRD1 is significantly underexpressed in triple-negative breast cancer (TNBC) against other subtypes and has an inverse correlation with Vimentin, inhibiting the proliferation, migration, invasion and EMT (epithelial-mesenchymal transition) process of breast cancer cells via inducing polyubiquitination-mediated proteasomal degradation of Vimentin. CircNR3C2 (hsa_circ_0071127) is also remarkably downregulated in TNBC, negatively correlated with the distant metastasis and lethality of invasive breast carcinoma. Overexpressing circNR3C2 in vitro and in vivo leads to a crucial enhancement of the tumor-suppressive effects of HRD1 through sponging miR-513a-3p. Conclusions Collectively, we elucidated a bona fide circNR3C2/miR-513a-3p/HRD1/Vimentin axis that negatively regulates the metastasis of TNBC, suggesting that circNR3C2 and HRD1 can act as potential prognostic biomarkers. Our study may facilitate the development of therapeutic agents targeting circNR3C2 and HRD1 for patients with aggressive breast cancer.

scholarly journals MicroRNA-1246 Suppresses the Metastasis of Breast Cancer Cells by Targeting the DRAK1A/PGRN Axis to Prevent the Epithelial-Mesenchymal Transition

2021 ◽  
Author(s):  
Pan Wang ◽  
Wenju Chen ◽  
Yaqiong Zhang ◽  
Qianyi Zhong ◽  
Zhaoyun Li ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Triple Negative Breast Cancer ◽  
Breast Cancer Cells ◽  
Triple Negative ◽  
Epithelial Mesenchymal Transition ◽  
Migration And Invasion ◽  
Mesenchymal Transition ◽  
Tnbc Cell ◽  
Novel Target

Abstract Objective. Breast cancer is one of the most common malignant and highly heterogeneous tumors in women. MicroRNAs (miRNAs), such as miR-1246, play important roles in various types of malignant cancers, including triple-negative breast cancer (TNBC). However, the biological role of miR-1246 in TNBC has not yet been fully elucidated. In this study, we studied the role of miR-1246 in the occurrence and development of TNBC and its mechanism of action.Methods. Cell Counting Kit-8 (CCK-8), wound healing, and Transwell assays were performed to observe the effects of miR-1246 on TNBC cell proliferation, migration, and invasion, respectively. The expression of epithelial-mesenchymal transition (EMT) markers was detected by western blotting. Dual luciferase reporter assays were performed to determine whether DYRK1A is a novel target of miR-1246. In addition, an immunoprecipitation experiment was performed to verify the binding of DYRK1A to PGRN. Rescue experiments were performed to determine whether DYRK1A is a novel target of miR-1246 and whether miR-1246 suppresses the metastasis of breast cancer cells by targeting the DRAK1A/PGRN axis to prevent the epithelial-mesenchymal transition.Results. Our results show that miR‑1246 suppresses the proliferation, migration, and invasion of TNBC cells and that DYRK1A is a novel target of miR-1246. MiR‑1246 plays a suppressive role in the regulation of the EMT of TNBC cells by targeting DYRK1A. DYRK1A mediates the metastasis of triple-negative breast cancer via activation of the EMT. We identified PGRN as a novel DYRK1A-interacting protein. DYRK1A and PGRN act together to regulate the occurrence and development of breast cancer through miR-1246.Conclusion. miR-1246 attenuates TNBC cell invasion and the EMT by targeting the DRAK1A/PGRN axis. Our data suggest that miR‑1246 may be used to develop novel early-stage diagnostic and therapeutic strategies for TNBC.

Co-loading of an anthracycline analogue Pirarubicin and Salinomycin in a 1:3 ratio into Quatramerbiodegradable polymeric nanoparticles synergistically inhibit growth of triple-negative breast cancer.

2021 ◽  
Vol 39 (15_suppl) ◽  
pp. e15047-e15047
Author(s):  
Surender Kharbanda ◽  
Anees Mohammad ◽  
Sachchidanand Tiwari ◽  
Neha Mehrotra ◽  
Sireesh Appajosyula ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Triple Negative Breast Cancer ◽  
Triple Negative ◽  
Breast Cancers ◽  
Mice Model ◽  
Single Drug ◽  
Tnbc Cell ◽  
Dual Drug

e15047 Background: Triple negative breast cancer (TNBC) accounts for about 10-15% of all breast cancers and differ from other types of invasive breast cancers in that they grow and spread faster. TNBCs have limited treatment options and a worse prognosis. Therapy with anthracyclines considered to be one of the most effective agents in the treatment. Unfortunately, resistance to anthracycline therapy is very common due to drug efflux mediated by overexpression of ABC transporter. Pirarubicin (PIRA), an analogue of doxorubicin (DOX), is approved in Japan, Korea and China and is shown to be less cardiotoxic than DOX. Recent studies suggest that cancer stem cells (CSCs) play an important role in tumorigenesis and biology of TNBC. Targeting CSCs may be a promising, novel strategy for the treatment of this aggressive disease. Recent studies have shown that salinomycin (SAL) preferentially targets the viability of CSCs. Methods: SAL and PIRA were co-encapsulated in polylactic acid (PLA)-based block copolymeric nanoparticles (NPs) to efficiently co-deliver these agents to treat TNBC cells. Results: Generated SAL-PIRA co-encapsulated dual drug-loaded NPs showed an average diameter of 110 ± 7 nm, zeta potential of -12.5 mV and PDI of less than 0.25. Both of these anti-cancer agents showed slow and sustained release profile in non-physiological buffer (PBS, pH 7.4) from these dual drug-encapsulated NPs. Additionally, multiple ratios (PIRA:SAL = 3:1, 1:1, 1:3) were encapsulated to generate diverse dual drug-loaded NPs. The results demonstrate that, in contrast to 1:1 and 3:1, treatment of TNBC cells with 1:3 ratio of PIRA:SAL dual drug-loaded NPs, was associated with significant inhibition of growth in vitro in multiple TNBC cell lines. Interestingly, PIRA:SAL (1:3) was synergistic as compared to either SAL- or PIRA single drug-loaded NPs. The IC50 of PIRA and SAL in single drug-encapsulated NPs is 150 nM and 700 nM respectively in MDA-MB-468. Importantly, the IC50 of PIRA in dual drug-encapsulated NPs dropped down to 30 nM (5-fold). Similar results were obtained in SUM-149 TNBC cell line. Studies are underway to evaluate in vivo biological activity of PIRA:SAL (1:3) on tumor growth in a TNBC xenograft mice model. Conclusions: These results demonstrate that a novel dual drug-loaded NP formulation of PIRA and SAL in a unique ratio of 1:3 represents an approach for successful targeting of CSCs and bulk tumor cells in TNBC and potentially other cancer types.

Lignin-graft-PLGA drug-delivery system improves efficacy of MEK1/2 inhibitors in triple-negative breast cancer cell line

Nanomedicine ◽  
2020 ◽  
Vol 15 (10) ◽  
pp. 981-1000
Author(s):  
C Ethan Byrne ◽  
Carlos E Astete ◽  
Manibarathi Vaithiyanathan ◽  
Adam T Melvin ◽  
Mahsa Moradipour ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Drug Delivery ◽  
Cell Line ◽  
Drug Delivery System ◽  
Delivery System ◽  
Triple Negative Breast Cancer ◽  
Targeted Therapies ◽  
Triple Negative ◽  
Mesenchymal Transition

Aim: Few targeted therapies are available for triple-negative breast cancer (TNBC) patients. Here, we propose a novel alkaline-lignin-conjugated-poly(lactic- co-glycolic acid) (L-PLGA) nanoparticle drug delivery system to improve the efficacy of targeted therapies. Materials & methods: L-PLGA nanoparticles (NPs) loaded with the MEK1/2 inhibitor GDC-0623 were characterized, tested in vitro on MDA-MB-231 TNBC cell line and compared with loaded PLGA NPs. Results: Loaded L-PLGA NPs were less than half the size of PLGA NPs, had slower drug release and improved the efficacy of GDC-0623 when tested in vitro. We demonstrated that GDC-0623 reversed epithelial-to-mesenchymal transition in TNBC. Conclusion: Our findings indicate that L-PLGA NPs are superior to PLGA NPs in delivering GDC-0623 to cancer cells for improved efficacy in vitro.

scholarly journals Looking for a Better Characterization of Triple-Negative Breast Cancer by Means of Circulating Tumor Cells

2020 ◽  
Vol 9 (2) ◽  
pp. 353 ◽  
Author(s):  
Manuel Abreu ◽  
Pablo Cabezas-Sainz ◽  
Thais Pereira-Veiga ◽  
Catalina Falo ◽  
Alicia Abalo ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Tumor Cells ◽  
Circulating Tumor Cells ◽  
Triple Negative Breast Cancer ◽  
Triple Negative ◽  
Mesenchymal Transition ◽  
Intermediate Phenotypes ◽  
Tumor Dissemination

Traditionally, studies to address the characterization of mechanisms promoting tumor aggressiveness and progression have been focused only on primary tumor analyses, which could provide relevant information but have limitations to really characterize the more aggressive tumor population. To overcome these limitations, circulating tumor cells (CTCs) represent a noninvasive and valuable tool for real-time profiling of disseminated tumor cells. Therefore, the aim of the present study was to explore the value of CTC enumeration and characterization to identify markers associated with the outcome and the aggressiveness of triple-negative breast cancer (TNBC). For that aim, the CTC population from 32 patients diagnosed with TNBC was isolated and characterized. This population showed important cell plasticity in terms of expression of epithelia/mesenchymal and stemness markers, suggesting the relevance of epithelial to mesenchymal transition (EMT) intermediate phenotypes for efficient tumor dissemination. Importantly, the CTC signature demonstrated prognostic value to predict the patients’ outcome and pointed to a relevant role of tissue inhibitor of metalloproteinases 1 (TIMP1) and androgen receptor (AR) for TNBC biology. Furthermore, we also analyzed the usefulness of the AR and TIMP1 blockade to target TNBC proliferation and dissemination using in vitro and in vivo zebra fish and mouse models. Overall, the molecular characterization of CTCs from advanced TNBC patients identifies highly specific biomarkers with potential applicability as noninvasive prognostic markers and reinforced the value of TIMP1 and AR as potential therapeutic targets to tackle the most aggressive breast cancer.

scholarly journals The oncogenic kinase NEK2 regulates an RBFOX2-dependent pro-mesenchymal splicing program in triple-negative breast cancer cells

2021 ◽  
Vol 40 (1) ◽  
Author(s):  
Chiara Naro ◽  
Monica De Musso ◽  
Francesca Delle Monache ◽  
Valentina Panzeri ◽  
Pierre de la Grange ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cancer Cells ◽  
Triple Negative Breast Cancer ◽  
Epithelial To Mesenchymal Transition ◽  
Triple Negative ◽  
Splice Variants ◽  
The Cancer Genome Atlas ◽  
Mesenchymal Transition ◽  
Tnbc Cell ◽  
Tnbc Cell Line

Abstract Background Triple-negative breast cancer (TNBC) is the most heterogeneous and malignant subtype of breast cancer (BC). TNBC is defined by the absence of expression of estrogen, progesterone and HER2 receptors and lacks efficacious targeted therapies. NEK2 is an oncogenic kinase that is significantly upregulated in TNBC, thereby representing a promising therapeutic target. NEK2 localizes in the nucleus and promotes oncogenic splice variants in different cancer cells. Notably, alternative splicing (AS) dysregulation has recently emerged as a featuring trait of TNBC that contributes to its aggressive phenotype. Methods To investigate whether NEK2 modulates TNBC transcriptome we performed RNA-sequencing analyses in a representative TNBC cell line (MDA-MB-231) and results were validated in multiple TNBC cell lines. Bioinformatics and functional analyses were carried out to elucidate the mechanism of splicing regulation by NEK2. Data from The Cancer Genome Atlas were mined to evaluate the potential of NEK2-sensitive exons as markers to identify the TNBC subtype and to assess their prognostic value. Results Transcriptome analysis revealed a widespread impact of NEK2 on the transcriptome of TNBC cells, with 1830 AS events that are susceptible to its expression. NEK2 regulates the inclusion of cassette exons in splice variants that discriminate TNBC from other BC and that correlate with poor prognosis, suggesting that this kinase contributes to the TNBC-specific splicing program. NEK2 elicits its effects by modulating the expression of the splicing factor RBFOX2, a well-known regulator of epithelial to mesenchymal transition (EMT). Accordingly, NEK2 splicing-regulated genes are enriched in functional terms related to cell adhesion and contractile cytoskeleton and NEK2 depletion in mesenchymal TNBC cells induces phenotypic and molecular traits typical of epithelial cells. Remarkably, depletion of select NEK2-sensitive splice-variants that are prognostic in TNBC patients is sufficient to interfere with TNBC cell morphology and motility, suggesting that NEK2 orchestrates a pro-mesenchymal splicing program that modulates migratory and invasive properties of TNBC cells. Conclusions Our study uncovers an extensive splicing program modulated by NEK2 involving splice variants that confer an invasive phenotype to TNBCs and that might represent, together with NEK2 itself, valuable therapeutic targets for this disease.

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