Response to anti-HER2 neoadjuvant chemotherapy in HER2-positive invasive breast cancers with different HER2 FISH patterns.

AIMS: Human epidermal growth factor receptor 2 (HER2)-positive patients with breast cancer may have different HER2/CEP17 ratios and HER2 copy numbers, with inconsistent responses to anti-HER2 neoadjuvant chemotherapy (NACT). Our study aimed to explore the relationship between different HER2 fluorescence in situ hybridisation (FISH) patterns in HER2-positive patients with breast cancer and responses to anti-HER2 NACT. METHODS: 527 patients with HER2-positive invasive breast cancer who received anti-HER2 NACT from 2015 to 2022 were included and divided into three groups by FISH results, namely group A: HER2/CEP17<2.0 and HER2 copy numbers ≥6.0, HER2 immunohistochemistry 2/3+; group B: HER2/CEP17≥2.0 and HER2 copy numbers ≥4.0 and <6.0; group C: HER2/CEP17≥2.0 and HER2 copy numbers ≥6.0. We compared clinicopathological characteristics and pathological complete response (pCR) rates of different groups. RESULTS: According to HER2 FISH results, 12 patients (2.3%, 12/527) were in group A, 40 (7.6%, 40/527) were in group B and 475 (90.1%, 475/527) were in group C. The pCR rate was the lowest in group B (5.0%), while the pCR rates in group A and group C were 33.3% and 44.4%, respectively (p (group A vs. B) =0.021, p (group C vs. B) < 0.001). Both univariate and multivariate analyses revealed that HER2 FISH pattern was correlated with pCR rate (p (group C vs. B) < 0.001, p (group C vs. B) = 0.025). CONCLUSIONS: Patients with HER2/CEP17≥2.0 and HER2 copy numbers ≥4.0 and <6.0 do not benefit to the same extent from current anti-HER2 therapies as FISH-positive patients with other patterns.

Spermatid perinuclear RNA-binding protein promotes UBR5-mediated proteolysis of Dicer to accelerate triple-negative breast cancer progression.

Triple-negative breast cancer (TNBC) is the most lethal subtype of breast cancer with no targeted therapy. Spermatid perinuclear RNA binding protein (STRBP), a poorly characterized RNA-binding protein (RBP), has an essential role in normal spermatogenesis and sperm function, but whether and how its dysregulation contributing to cancer progression has not yet been explored. Here, we report that STRBP functions as a novel oncogene to drive TNBC progression. STRBP expression was upregulated in TNBC tissues and correlated with poor disease prognosis. Functionally, STRBP promoted TNBC cell proliferation, migration, and invasion in vitro, and enhanced xenograft tumor growth and lung colonization in mice. Mechanistically, STRBP interacted with Dicer, a core component of the microRNA biogenesis machinery, and promoted its proteasomal degradation through enhancing its interaction with E3 ubiquitin ligase UBR5. MicroRNA-sequencing analysis identified miR-200a-3p as a downstream effector of STRBP, which was regulated by Dicer and affected epithelial-mesenchymal transition. Importantly, the impaired malignant phenotypes of TNBC cells caused by STRBP depletion were largely rescued by knockdown of Dicer, and these effects were compromised by transfection of miR-200a-3p mimics. Collectively, these findings revealed a previously unrecognized oncogenic role of STRBP in TNBC progression and identified STRBP as a promising target against TNBC.

C9orf142 transcriptionally activates MTBP to drive progression and resistance to CDK4/6 inhibitor in triple-negative breast cancer.

BACKGROUND: Triple-negative breast cancer (TNBC) presents the most challenging subtype of all breast cancers because of its aggressive clinical phenotypes and absence of viable therapy targets. In order to identify effective molecular targets for treating patients with TNBC, we conducted an integration analysis of our recently published TNBC dataset of quantitative proteomics and RNA-Sequencing, and found the abnormal upregulation of chromosome 9 open reading frame 142 (C9orf142) in TNBC. However, the functional roles of C9orf142 in TNBC are unclear. METHODS: In vitro and in vivo functional experiments were performed to assess potential roles of C9orf142 in TNBC. Immunoblotting, real-time quantitative polymerase chain reaction (RT-qPCR), and immunofluorescent staining were used to investigate the expression levels of C9orf142 and its downstream molecules. The molecular mechanisms underlying C9orf142-regulated mouse double minute 2 (MDM2)-binding protein (MTBP) were determined by chromatin immunoprecipitation (ChIP) and dual-luciferase reporter assays. RESULTS: In TNBC tissues and metastatic lymph nodes, we observed that C9orf142 exhibited abnormal up-regulation, and its elevated expression was indicative of unfavorable prognosis for TNBC patients. Both in vitro and in vivo functional experiments demonstrated that C9orf142 accelerated TNBC growth and metastasis. Further mechanism exploration revealed that C9orf142 transcriptionally activated MTBP, thereby regulating its downstream MDM2/p53/p21 signaling axis and the transition of cell cycle from G1 to S phase. Functional rescue experiment demonstrated that knockdown of MTBP attenuated C9orf142-mediated tumour growth and metastasis. Furthermore, depletion of C9orf142 remarkably increased the responsiveness of TNBC cells to CDK4/6 inhibitor abemaciclib. CONCLUSIONS: Together, these findings unveil a previously unrecognized effect of C9orf142 in TNBC progression and responsiveness to CDK4/6 inhibitor, and emphasize C9orf142 as a promising intervention target for TNBC treatment.

Destabilization of microrchidia family CW-type zinc finger 2 via the cyclin-dependent kinase 1-chaperone-mediated autophagy pathway promotes mitotic arrest and enhances cancer cellular sensitivity to microtubule-targeting agents.

BACKGROUND: Microtubule-targeing agents (MTAs), such as paclitaxel (PTX) and vincristine (VCR), kill cancer cells through activtion of the spindle assembly checkpoint (SAC) and induction of mitotic arrest, but the development of resistance poses significant clinical challenges. METHODS: Immunoblotting and RT-qPCR were used to investigate potential function and related mechanism of MORC2. Flow cytometry analyses were carried out to determine cell cycle distribution and apoptosis. The effect of MORC2 on cellular sensitivity to PTX and VCR was determined by immunoblotting, flow cytometry, and colony formation assays. Immunoprecipitation assays and immunofluorescent staining were utilized to investigate protein-protein interaction and protein co-localization. RESULTS: Here, we identified microrchidia family CW-type zinc finger 2 (MORC2), a poorly characterized oncoprotein, as a novel regulator of SAC activation, mitotic progression, and resistance of cancer cells to PTX and VCR. Mechanically, PTX and VCR activate cyclin-dependent kinase 1, which in turn induces MORC2 phosphorylation at threonine 717 (T717) and T733. Phosphorylated MORC2 enhances its interation with HSPA8 and LAMP2A, two essential components of the chaperone-mediated autophagy (CMA) mechinery, resulting in its autophagic degradation. Degradation of MORC2 during mitosis leads to SAC activation through stabilizing anaphase promoting complex/cyclosome activator protein Cdc20 and facilitating mitotic checkpoint complex assembly, thus contributing to mitotic arrest induced by PTX and VCR. Notably, knockdown of MORC2 promotes mitotic arrest induced by PTX and VCR and enhances the sensitivity of cancer cells to PTX and VCR. CONCLUSIONS: Collectively, these findings unveil a previously unrecognized function and regulatory mechanism of MORC2 in mitotic progression and resistance of cancer cells to MTAs. These results also provide a new clue for developing combined treatmentstrategy by targeting MORC2 in combination with MTAs against human cancer.

Dynamic SUMOylation of MORC2 orchestrates chromatin remodelling and DNA repair in response to DNA damage and drives chemoresistance in breast cancer.

Rationale: SUMOylation regulates a plethora of biological processes, and its inhibitors are currently under investigation in clinical trials as anticancer agents. Thus, identifying new targets with site-specific SUMOylation and defining their biological functions will not only provide new mechanistic insights into the SUMOylation signaling but also open an avenue for developing new strategy for cancer therapy. MORC family CW-type zinc finger 2 (MORC2) is a newly identified chromatin-remodeling enzyme with an emerging role in the DNA damage response (DDR), but its regulatory mechanism remains enigmatic. Methods: In vivo and in vitro SUMOylation assays were used to determine the SUMOylation levels of MORC2. Overexpression and knockdown of SUMO-associated enzymes were used to detect their effects on MORC2 SUMOylation. The effect of dynamic MORC2 SUMOylation on the sensitivity of breast cancer cells to chemotherapeutic drugs was examined through in vitro and in vivo functional assays. Immunoprecipitation, GST pull-down, MNase, and chromatin segregation assays were used to explore the underlying mechanisms. Results: Here, we report that MORC2 is modified by small ubiquitin-like modifier 1 (SUMO1) and SUMO2/3 at lysine 767 (K767) in a SUMO-interacting motif dependent manner. MORC2 SUMOylation is induced by SUMO E3 ligase tripartite motif containing 28 (TRIM28) and reversed by deSUMOylase sentrin-specific protease 1 (SENP1). Intriguingly, SUMOylation of MORC2 is decreased at the early stage of DNA damage induced by chemotherapeutic drugs that attenuate the interaction of MORC2 with TRIM28. MORC2 deSUMOylation induces transient chromatin relaxation to enable efficient DNA repair. At the relatively late stage of DNA damage, MORC2 SUMOylation is restored, and SUMOylated MORC2 interacts with protein kinase CSK21 (casein kinase II subunit alpha), which in turn phosphorylates DNA-PKcs (DNA-dependent protein kinase catalytic subunit), thus promoting DNA repair. Notably, expression of a SUMOylation-deficient mutant MORC2 or administration of SUMO inhibitor enhances the sensitivity of breast cancer cells to DNA-damaging chemotherapeutic drugs. Conclusions: Collectively, these findings uncover a novel regulatory mechanism of MORC2 by SUMOylation and reveal the intricate dynamics of MORC2 SUMOylation important for proper DDR. We also propose a promising strategy to sensitize MORC2-driven breast tumors to chemotherapeutic drugs by inhibition of the SUMO pathway.

Protein Phosphatase 1 Subunit PPP1R14B Stabilizes STMN1 to Promote Progression and Paclitaxel Resistance in Triple-Negative Breast Cancer.

Triple-negative breast cancer (TNBC) represents the most lethal subtype of breast cancer due to its aggressive clinical features and the lack of effective therapeutic targets. To identify novel approaches for targeting TNBC, we examined the role of protein phosphatases in TNBC progression and chemoresistance. Protein phosphatase 1 regulatory subunit 14B (PPP1R14B), a poorly defined member of the protein phosphatase 1 regulatory subunits, was aberrantly upregulated in TNBC tissues and predicted poor prognosis. PPP1R14B was degraded mainly through the ubiquitin-proteasome pathway. RPS27A recruited deubiquitinase USP9X to deubiquitinate and stabilize PPP1R14B, resulting in overexpression of PPP1R14B in TNBC tissues. Gain- and loss-of-function assays demonstrated that PPP1R14B promoted TNBC cell proliferation, colony formation, migration, invasion, and resistance to paclitaxel in vitro. PPP1R14B also induced xenograft tumor growth, lung metastasis, and paclitaxel resistance in vivo. Mechanistic investigations revealed that PPP1R14B maintained phosphorylation and stability of oncoprotein stathmin 1 (STMN1), a microtubule-destabilizing phosphoprotein critically involved in cancer progression and paclitaxel resistance, which was dependent on PP1 catalytic subunits α and γ. Importantly, the tumor-suppressive effects of PPP1R14B deficiency could be partially rescued by ectopic expression of wild-type but not phosphorylation-deficient STMN1. Moreover, PPP1R14B decreased STMN1-mediated α-tubulin acetylation, microtubule stability, and promoted cell-cycle progression, leading to resistance of TNBC cells to paclitaxel. Collectively, these findings uncover a functional and mechanistic role of PPP1R14B in TNBC progression and paclitaxel resistance, indicating PPP1R14B is a potential therapeutic target for TNBC. SIGNIFICANCE: PPP1R14B upregulation induced by RPS27A/USP9X in TNBC increases STMN1 activity, leading to cancer progression and paclitaxel resistance.

TOLLIP-mediated autophagic degradation pathway links the VCP-TMEM63A-DERL1 signaling axis to triple-negative breast cancer progression.

Triple-negative breast cancer (TNBC) is the most challenging breast cancer subtype to treat due to the lack of effective targeted therapies. Transmembrane (TMEM) proteins represent attractive drug targets for cancer therapy, but biological functions of most members of the TMEM family remain unknown. Here, we report for the first time that TMEM63A (transmembrane protein 63A), a poorly characterized TMEM protein with unknown functions in human cancer, functions as a novel oncogene to promote TNBC cell proliferation, migration, and invasion in vitro and xenograft tumor growth and lung metastasis in vivo. Mechanistic investigations revealed that TMEM63A localizes in endoplasmic reticulum (ER) and lysosome membranes, and interacts with VCP (valosin-containing protein) and its cofactor DERL1 (derlin 1). Furthermore, TMEM63A undergoes autophagy receptor TOLLIP-mediated autophagic degradation and is stabilized by VCP through blocking its lysosomal degradation. Strikingly, TMEM63A in turn stabilizes oncoprotein DERL1 through preventing TOLLIP-mediated autophagic degradation. Notably, pharmacological inhibition of VCP by CB-5083 or knockdown of DERL1 partially abolishes the oncogenic effects of TMEM63A on TNBC progression both in vitro and in vivo. Collectively, these findings uncover a previously unknown functional and mechanistic role for TMEM63A in TNBC progression and provide a new clue for targeting TMEM63A-driven TNBC tumors by using a VCP inhibitor.Abbreviations: ATG16L1, autophagy related 16 like 1; ATG5, autophagy related 5; ATP5F1B/ATP5B, ATP synthase F1 subunit beta; Baf-A1, bafilomycin A1; CALCOCO2/NDP52, calcium binding and coiled-coil domain 2; CANX, calnexin; DERL1, derlin 1; EGFR, epidermal growth factor receptor; ER, endoplasmic reticulum; ERAD, endoplasmic reticulum-associated degradation; HSPA8, heat shock protein family A (Hsp70) member 8; IP, immunoprecipitation; LAMP2A, lysosomal associated membrane protein 2; NBR1, NBR1 autophagy cargo receptor; OPTN, optineurin; RT-qPCR, reverse transcription-quantitative PCR; SQSTM1/p62, sequestosome 1; TAX1BP1, Tax1 binding protein 1; TMEM63A, transmembrane protein 63A; TNBC, triple-negative breast cancer; TOLLIP, toll interacting protein; VCP, valosin containing protein.

HSP90 N-terminal inhibitors target oncoprotein MORC2 for autophagic degradation and suppress MORC2-driven breast cancer progression.

AIMS: MORC family CW-type zinc finger 2 (MORC2), a GHKL-type ATPase, is aberrantly upregulated in multiple types of human tumors with profound effects on cancer aggressiveness, therapeutic resistance, and clinical outcome, thus making it an attractive drug target for anticancer therapy. However, the antagonists of MORC2 have not yet been documented. METHODS AND RESULTS: We report that MORC2 is a relatively stable protein, and the N-terminal homodimerization but not ATP binding and hydrolysis is crucial for its stability through immunoblotting analysis and Quantitative real-time PCR. The N-terminal but not C-terminal inhibitors of heat shock protein 90 (HSP90) destabilize MORC2 in multiple cancer cell lines, and strikingly, this process is independent on HSP90. Mechanistical investigations revealed that HSP90 N-terminal inhibitors disrupt MORC2 homodimer formation without affecting its ATPase activities, and promote its lysosomal degradation through the chaperone-mediated autophagy pathway. Consequently, HSP90 inhibitor 17-AAG effectively blocks the growth and metastatic potential of MORC2-expressing breast cancer cells both in vitro and in vivo, and these noted effects are not due to HSP90 inhibition. CONCLUSION: We uncover a previously unknown role for HSP90 N-terminal inhibitors in promoting MORC2 degradation in a HSP90-indepentent manner and support the potential application of these inhibitors for treating MORC2-overexpressing tumors, even those with low or absent HSP90 expression. These results also provide new clue for further design of novel small-molecule inhibitors of MORC2 for anticancer therapeutic application.

Overexpression of Long Non-Coding RNA Linc01315 Predicts Poor Prognosis in Breast Cancer.

BACKGROUND: LncRNAs have been shown to play critical roles in regulating tumorigenesis and tumor progression. Using LncRNAs to predict prognosis and therapeutic response to cancer treatment has been caused for concern, but the predictive value of lncRNAs remains to be explored and underlying mechanisms have not been completely understood. METHODS: The Linc01315 expression level was detected in 282 breast cancer tissues by using quantitative RT-PCR. The association between Linc01315 expression level and clinicopathological features of these breast cancer patients was further analyzed. Multiple regression analysis was used to evaluate Linc01315 predictive value of patients' prognosis. RESULTS: Our study revealed that Linc01315 expression level was significantly correlated with vessel invasion (P = 0.028) and tumor subtype (P = 0.039). The Kaplan-Meier survival curves demonstrated that patients with lower Linc01315 expression level had significantly longer disease free survival (DFS) (P = 0.002) and overall survival (OS) (P=0.019). Multiple regression analysis showed that Linc01315 level could be an independent predictive factor for DFS (hazards ratio = 0.613, 95% confidence interval = 0.375-1.003; P = 0.049) and OS (hazards ratio = 0.439, 95% confidence interval = 0.228-0.845; P = 0.014). Further analysis showed that low Linc01315 level patients with endocrine therapy could benefit patients DFS (P=0.037) and OS (P=0.025). CONCLUSION: Our results demonstrate that Linc01315 expression level is significantly correlated with breast cancer patients' prognosis. Linc01315 may represent an independent prognostic marker and therapeutic target in breast cancer.

TEM8 marks neovasculogenic tumor-initiating cells in triple-negative breast cancer.

Enhanced neovasculogenesis, especially vasculogenic mimicry (VM), contributes to the development of triple-negative breast cancer (TNBC). Breast tumor-initiating cells (BTICs) are involved in forming VM; however, the specific VM-forming BTIC population and the regulatory mechanisms remain undefined. We find that tumor endothelial marker 8 (TEM8) is abundantly expressed in TNBC and serves as a marker for VM-forming BTICs. Mechanistically, TEM8 increases active RhoC level and induces ROCK1-mediated phosphorylation of SMAD5, in a cascade essential for promoting stemness and VM capacity of breast cancer cells. ASB10, an estrogen receptor ERα trans-activated E3 ligase, ubiquitylates TEM8 for degradation, and its deficiency in TNBC resulted in a high homeostatic level of TEM8. In this work, we identify TEM8 as a functional marker for VM-forming BTICs in TNBC, providing a target for the development of effective therapies against TNBC targeting both BTIC self-renewal and neovasculogenesis simultaneously.

The Biological Function of TUSC7/miR-1224-3p Axis in Triple-Negative Breast Cancer.

BACKGROUND: Triple-negative breast cancers (TNBC), comprising about 20% of breast cancers, have a poor prognosis. Currently, there is no effective target therapy for TNBC. LncRNA TUSC7 has been identified as a tumor suppressor in osteosarcoma and colorectal cancer. In this study, we investigated the clinical significance and the biological function of TUSC7 in breast cancer. METHODS: We retrospectively evaluated the expression level and clinical significance of TUSC7 in 90 paired breast cancer tissues and normal tissues. The proliferation, migration, and invasion assays were performed to investigate the biological function of TUSC7 in breast cancer. Finally, microarray, a luciferase reporter assay, and quantitative real-time polymerase chain reaction (qPCR) were used to explore the potential underlying mechanism of tumor suppressor role of TUSC7. RESULTS: Low TUSC7 expression was found to be an independent prognostic factor of poor overall survival (OS) in TNBC patients. Ectopic expression of TUSC7 inhibited tumor cell growth both in vitro and in vivo. TUSC7 overexpression significantly promoted the sensitivity of MDA-MB-468 cells to paclitaxel and carboplatin. In terms of the mechanism, TUSC7 might perform its biological function through binding with miR-1224-3P and regulating its expression level. Besides, genes in cell cycle pathways, such as BUB3 (budding uninhibited by benzimidazoles 3) and TGF-ß (targeting transforming growth factor ß) pathways were downregulated, and genes involved in the MAPK (mitogen-activated protein kinase) (TGFBR2, transforming growth factor-beta receptor 2), PI3K-AKT (phosphoinositide 3-kinase- AKT serine/threonine kinase 1) and NF-κB (nuclear factor-kappa B subunit) pathways were upregulated in TUSC7 knockdown MDA-MB-231 cells. CONCLUSION: The low TUSC7 expression is an independent prognostic factor of poor OS of TNBC patients. TUSC7 might inhibit breast cancer cell growth and metastasis both in vitro and vivo through binding with miR-1224-3P and regulating MAPK, PI3K/AKT, and NF-κB signaling pathways.

Abemaciclib Combined With Endocrine Therapy for the Adjuvant Treatment of HR+, HER2-, Node-Positive, High-Risk, Early Breast Cancer (monarchE).

PURPOSE: Many patients with HR+, HER2- early breast cancer (EBC) will not experience recurrence or have distant recurrence with currently available standard therapies. However, up to 30% of patients with high-risk clinical and/or pathologic features may experience distant recurrence, many in the first few years. Superior treatment options are needed to prevent early recurrence and development of metastases for this group of patients. Abemaciclib is an oral, continuously dosed, CDK4/6 inhibitor approved for HR+, HER2- advanced breast cancer (ABC). Efficacy and safety of abemaciclib in ABC supported evaluation in the adjuvant setting. METHODS: This open-label, phase III study included patients with HR+, HER2-, high-risk EBC, who had surgery and, as indicated, radiotherapy and/or adjuvant/neoadjuvant chemotherapy. Patients with four or more positive nodes, or one to three nodes and either tumor size ≥ 5 cm, histologic grade 3, or central Ki-67 ≥ 20%, were eligible and randomly assigned (1:1) to standard-of-care adjuvant endocrine therapy (ET) with or without abemaciclib (150 mg twice daily for 2 years). The primary end point was invasive disease-free survival (IDFS), and secondary end points included distant relapse-free survival, overall survival, and safety. RESULTS: At a preplanned efficacy interim analysis, among 5,637 randomly assigned patients, 323 IDFS events were observed in the intent-to-treat population. Abemaciclib plus ET demonstrated superior IDFS versus ET alone (P = .01; hazard ratio, 0.75; 95% CI, 0.60 to 0.93), with 2-year IDFS rates of 92.2% versus 88.7%, respectively. Safety data were consistent with the known safety profile of abemaciclib. CONCLUSION: Abemaciclib when combined with ET is the first CDK4/6 inhibitor to demonstrate a significant improvement in IDFS in patients with HR+, HER2- node-positive EBC at high risk of early recurrence.

Discrete functional and mechanistic roles of chromodomain Y-like 2 (CDYL2) transcript variants in breast cancer growth and metastasis.

Rationale: Chromodomain Y-like 2 (CDYL2) is a member of the CDY gene family involved in spermatogenesis, but its role in human cancer has not been reported. Analyses of publicly available databases demonstrate that CDYL2 is abundantly expressed in breast tumors. However, whether CDYL2 is involved in breast cancer progression remains unknown. Methods: Quantitative real-time PCR and immunoblotting assays were used to determine the expression levels of CDYL2 transcript variants in breast cancer cell lines and primary breast tumors. The effect of CDYL2 transcript variants on the malignant phenotypes of breast cancer cells was examined through in vitro and in vivo assays. Immunofluorescent staining, RNA-seq, ATAC-seq, and ChIP-qPCR were used to investigate the underlying mechanisms behind the aforementioned observations. Results: Here we show that CDYL2 generated four transcript variants, named CDYL2a-CDYL2d. CDYL2a and CDYL2b were the predominant variants expressed in breast cancer cell lines and breast tumors and exerted strikingly discrete functions in breast cancer growth and metastasis. CDYL2a was upregulated in the majority of the breast cancer cell lines and tumors, and promoted breast cancer cell proliferation, colony formation in vitro, and tumorigenesis in xenografts. In contrast, CDYL2b was mainly expressed in luminal- and HER2-positive types of breast cancer cell lines and tumors, and suppressed the migratory, invasive, and metastatic potential of breast cancer cells in vitro and in vivo. Mechanistically, CDYL2a partially localized to SC35-positive nuclear speckles and promoted alternative splicing of a subset of target genes, including FIP1L1, NKTR, and ADD3 by exon skipping. Elimination of full-length FIP1L1, NKTR, and ADD3 rescued the impaired cell proliferation through CDYL2a depletion. In contrast, CDYL2b localized to heterochromatin and transcriptionally repressed several metastasis-promoting genes, including HPSE, HLA-F, and SELL. Restoration of HPSE, HLA-F, or SELL expression in CDYL2b-overexpressing cells attenuated the ability of CDYL2b to suppress breast cancer cell migration and invasion. Conclusions: Collectively, these findings establish an isoform-specific function of CDYL2 in breast cancer development and progression and highlight that pharmacological inhibition of the CDYL2a, but not the CDYL2b, isoform may be an effective strategy for breast cancer therapy.

Acetylation of MORC2 by NAT10 regulates cell-cycle checkpoint control and resistance to DNA-damaging chemotherapy and radiotherapy in breast cancer.

MORC family CW-type zinc finger 2 (MORC2) is an oncogenic chromatin-remodeling enzyme with an emerging role in DNA repair. Here, we report a novel function for MORC2 in cell-cycle checkpoint control through an acetylation-dependent mechanism. MORC2 is acetylated by the acetyltransferase NAT10 at lysine 767 (K767Ac) and this process is counteracted by the deacetylase SIRT2 under unperturbed conditions. DNA-damaging chemotherapeutic agents and ionizing radiation stimulate MORC2 K767Ac through enhancing the interaction between MORC2 and NAT10. Notably, acetylated MORC2 binds to histone H3 phosphorylation at threonine 11 (H3T11P) and is essential for DNA damage-induced reduction of H3T11P and transcriptional repression of its downstream target genes CDK1 and Cyclin B1, thus contributing to DNA damage-induced G2 checkpoint activation. Chemical inhibition or depletion of NAT10 or expression of an acetylation-defective MORC2 (K767R) forces cells to pass through G2 checkpoint, resulting in hypersensitivity to DNA-damaging agents. Moreover, MORC2 acetylation levels are associated with elevated NAT10 expression in clinical breast tumor samples. Together, these findings uncover a previously unrecognized role for MORC2 in regulating DNA damage-induced G2 checkpoint through NAT10-mediated acetylation and provide a potential therapeutic strategy to sensitize breast cancer cells to DNA-damaging chemotherapy and radiotherapy by targeting NAT10.

Comparison of hepatic resection and systemic treatment of breast cancer liver metastases: A propensity score matching study.

BACKGROUND: The role of surgery in breast cancer liver metastases (BCLM) remains elusive, and current application is limited. Our aim is to investigate whether hepatic resection (HR) of BCLM improves survival compared with non-hepatic resection (NHR) treatment. METHODS: Three hundred and eighty-four patients with BCLM from 2008 to 2018 were divided into two groups. Propensity score matching (PSM) analysis was used to compare the clinical outcomes. RESULTS: After PSM the mean overall survival (OS) and the 1, 3, and 5-year OS rates in HR group were 61.8 months, 92.6%, 54.7% and 54.7%, respectively; while for NHR group these values were 38.6 months, 79.2%, 45.6% and 21.9%, respectively (p < 0.007). Multivariate analysis indicated hormonal receptor status (p = 0.039) and hepatic resection (p = 0.032) were independent prognostic factors. CONCLUSION: Our study revealed that hepatectomy yields a survival benefit safely compared with medical treatments, especially for patients with positive hormonal receptors.

Neoadjuvant therapy and sentinel lymph node biopsy in HER2-positive breast cancer patients: results from the PEONY trial.

OBJECTIVE: The aim of the study is to evaluate the optimal timing of sentinel lymph node biopsy (SLNB) in patients with clinical negative axillary lymph nodes (ALNs) before neoadjuvant therapy (NAT) and the feasibility of SLNB substituting for ALN dissection in patients with positive ALNs who convert to node negative, for HER2-positive disease. METHODS: Patients receiving SLNB with dual tracer mapping in the PEONY trial were analyzed. RESULTS: For 80 patients with clinical negative ALNs, the node negative rate by pathology after NAT was 83.8%. SLNB was performed after NAT in 71 patients. The identification rate of sentinel lymph nodes (SLNs) was 100%. For patients with positive ALNs before NAT, the axillary pathologic complete response rate in the dual HER2 blockade arm was significantly higher than that in the single blockade arm (p = 0.002). SLNB was performed in 71 patients. The identification rate was 100% and the false-negative rate was 17.2%. The false-negative rates were 33.3%, 14.3%, and 0 when 1, 2, and more than 2 SLNs were detected. There was no false-negative case when more than 1 SLN and the clipped nodes were removed simultaneously. CONCLUSIONS: For clinical ALN negative patients, HER2-positive subtype is found to have high node negative rate by pathology and it is recommended to undergo SLNB after NAT. For patients with positive ALNs who convert to negative, the false-negative rate is high. Dual tracer mapping, more than 2 SLNs detected, more than 1 SLN identified plus the clips placed are the guarantees for lower false-negative rate.

RNF144A functions as a tumor suppressor in breast cancer through ubiquitin ligase activity-dependent regulation of stability and oncogenic functions of HSPA2.

Deregulation of E3 ubiquitin ligases is intimately implicated in breast cancer pathogenesis and progression, but the underlying mechanisms still remain elusive. Here we report that RING finger protein 144A (RNF144A), a poorly characterized member of the RING-in-between-RING family of E3 ubiquitin ligases, functions as a tumor suppressor in breast cancer. RNF144A was  downregulated in a subset of primary breast tumors and restoration of RNF144A suppressed breast cancer cell proliferation, colony formation, migration, invasion in vitro, tumor growth, and lung metastasis in vivo. In contrast, knockdown of RNF144A promoted malignant phenotypes of breast cancer cells. Quantitative proteomics and biochemical analysis revealed that RNF144A interacted with and targeted heat-shock protein family A member 2 (HSPA2), a putative oncoprotein that is frequently upregulated in human cancer and promotes tumor growth and progression, for ubiquitination and degradation. Notably, the ligase activity-defective mutants of RNF144A impaired its ability to induce ubiquitination and degradation of HSPA2, and to suppress breast cancer cell proliferation, migration, and invasion as compared with its wild-type counterpart. Moreover, RNF144A-mediated suppression of breast cancer cell proliferation, migration, and invasion was rescued by ectopic HSPA2 expression. Clinically, low RNF144A and high HSPA2 expression in breast cancer patients was correlated with aggressive clinicopathological characteristics and decreased overall and disease-free survival. Collectively, these findings reveal a previously unappreciated role for RNF144A in suppression of breast cancer growth and metastasis, and identify RNF144A as the first, to our knowledge, E3 ubiquitin ligase for HSPA2 in human cancer.

Detection of breast cancer stem cell gene mutations in circulating free DNA during the evolution of metastases.

PURPOSE: Limited knowledge exists on the detection of breast cancer stem cell (BCSC)-related mutations in circulating free DNA (cfDNA) from patients with advanced cancers. Identification of new cancer biomarkers may allow for earlier detection of disease progression and treatment strategy modifications. METHODS: We conducted a prospective study to determine the feasibility and prognostic utility of droplet digital polymerase chain reaction (ddPCR)-based BCSC gene mutation analysis of cfDNA in patients with breast cancer. RESULTS: Detection of quantitative BCSC gene mutation in cfDNA by ddPCR mirrors disease progression and thus may represent a valuable and cost-effective measure of tumor burden. We have previously shown that hematological and neurological expressed 1-like (HN1L), ribosomal protein L39 (RPL39), and myeloid leukemia factor 2 (MLF2) are novel targets for BCSC self-renewal, and targeting these genetic alterations could be useful for personalized genomic-based therapy. CONCLUSION: BCSC mutation detection in cfDNA may have important implications for diagnosis, prognosis, and serial monitoring.

Evaluating the effect of Avastin on breast cancer angiogenesis using synchrotron radiation.

BACKGROUND: The visualization of microvasculature is an essential step in understanding the mechanisms underlying early vessel disorders involved in breast cancer and for developing effective therapeutic strategies. However, generating detailed and reproducible data using immunohistochemistry analysis of breast cancer angiogenesis has been difficult. METHODS: To analyze the diversification of angiogenesis in the development of tumor growth and evaluate the anti-vascular effects of Avastin (bevacizumab), we used new X-ray microangiography and third-generation synchrotron radiation-based micro-computed tomography (SR micro-CT) technology. With these techniques, we were able to investigate the structures and density of microvessels in xenograft mouse models (n=24). Barium sulfate nanoparticles were injected into the left cardiac ventricle of the mice to allow the visualization of blood vessels. RESULTS: Three-dimensional structures of microvessels were displayed with a high spatial image resolution of 20-30 µm. The density of angiogenesis and the incidence of lung metastasis were significantly reduced in xenograft mouse models of breast cancer treated with Avastin compared with control groups. Also, the density of smaller vessels (diameter <50 µm) was significantly decreased in the Avastin-treated mice, while the density of larger vessels (diameter >100 µm) was not significantly changed. CONCLUSIONS: Avastin inhibited tumor growth and lung metastasis by reducing microvessels. Additionally, synchrotron radiation (SR) techniques are useful as an additional tool for more precise quantification of angiogenesis.

Survival and chemotherapy-related risk of second primary malignancy in breast cancer patients: a SEER-based study.

BACKGROUND: With the improvement in the survival of breast cancer, developing second primary malignancy becomes a serious health issue. The aim of this study was to explore the survival of breast cancer patients with second primary malignancy, and to evaluate the impact of chemotherapy on the risk of different cancer sites. METHOD: Obtaining data from the Surveillance, Epidemiology, and End Results database, we calculated the standardized incidence ratio (SIR) for second primary malignancy in breast cancer survivors between 2000 and 2014. Overall survival and cancer-specific survival were analyzed with Kaplan-Meier method. Then, we further conducted stratified sub-analyses according to chemotherapy. RESULTS: The overall risk of second primary cancer for all sites was significantly elevated in breast cancer patients (SIR = 1.15, 95% CI 1.14-1.16). Overall survival and cancer-specific survival of the patients with breast cancer only were significantly better than the patients with multiple primary cancers (both P < 0.001). Chemotherapy was associated with increased incidences for all sites, except lymphoma, myeloma, and chronic lymphocytic leukemia (SIR = 0.80, 95% CI 0.72-0.88; SIR = 0.85, 95% CI 0.71-1.01; SIR = 0.57, 95% CI 0.43-0.74, respectively). The risk for developing second acute myeloid leukemia after chemotherapy in breast cancer patients varied with age and latency. CONCLUSION: Female breast cancer patients showed higher incidence of second primary malignancy, which was associated with poorer prognosis. Chemotherapy benefits should be weighed against the risks of second primary malignancy.