HER2-positive Breast Cancer Progression Research Articles

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

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.

Integrative whole-genome and transcriptome analysis of HER2-amplified metastatic breast cancer

BackgroundIn breast cancer, the advent of anti-HER2 therapies has made HER2+ tumors a highly relevant subgroup. However, the exact characteristics which prohibit clinical response to anti-HER2 therapies and drive disease progression are not yet fully known. Integrative whole-genome and transcriptomic sequencing data from both primary and metastatic HER2-positive breast cancer will enhance our understanding of underlying biological processes.MethodsHere, we used WGS and RNA sequencing data of 700 metastatic breast tumors, of which 68 being HER2+, to search for specific genomic features of HER2+ disease and therapy resistance. Furthermore, we integrated results with transcriptomic data to associate tumors exhibiting a HER2+-specific gene expression profile with ERBB2 mutation status, prior therapy and relevant gene expression signatures.ResultsOverall genomic profiles of primary and metastatic HER2+ breast cancers were similar, and no specific acquired genomics traits connected to prior anti-HER2 treatment were observed. However, specific genomic features were predictive of progression-free survival on post-biopsy anti-HER2 treatment. Furthermore, a HER2-driven expression profile grouped HER2-amplified tumors with ERBB2-mutated cases and cases without HER2 alterations. The latter were reported as ER positive in primary disease, but the metastatic biopsy showed low ESR1 expression and upregulation of the MAPK pathway, suggesting transformation to ER independence.ConclusionsIn summary, although the quantity of variants increased throughout HER2-positive breast cancer progression, the genomic composition remained largely consistent, thus yielding no new major processes beside those already operational in primary disease. Our results suggest that integrated genomic and transcriptomic analyses may be key in establishing therapeutic options.

Stereotactic Radiotherapy or Whole Brain Radiotherapy Combined with Pyrotinib and Capecitabine in HER2-Positive Advanced Breast Cancer Patients with Brain Metastases (BROPTIMA): A Prospective, Phase Ib/II Single-Arm Clinical Study

Approximately half of patients with advanced HER2-positive breast cancer (BC) will develop brain metastases (BM) over time. Local therapy including stereotactic radiotherapy (SRT) and whole brain radiotherapy (WBRT) is the main initial treatment in malignant tumor patients with BM. However, more than 50% patients after radiotherapy in one year suffered intracranial recurrence. Pyrotinib, a small molecule, irreversible, pan-ErbB receptor tyrosine kinase inhibitor (TKI), has a high potency for controlling BM and reducing the occurrence of brain metastases in advanced HER2-positive BC patients. We hypothesized that SRT or WBRT combined with pyrotinib and capecitabine could decrease intracranial progression in HER2 positive BC with newly diagnosed BM. In this prospective single-arm phase Ib/II trial (NCT04582968), eligible patients were assigned to either fractionated stereotactic radiotherapy (FSRT) or whole-brain radiation therapy (WBRT), combined with pyrotinib and capecitabine. The primary endpoint was one-year CNS progression-free survival (PFS) rate. Secondary endpoints included intracranial objective response rate (IC-ORR) according to RANO-BM criteria, progression-free survival (PFS), overall survival (OS) and evaluation of safety and neurocognitive function. From January 2020 to August 2022, 40 patients were enrolled. Twenty-nine patients were treated with FSRT in 8 Gy per fraction with 3 to 5 fractions and 11 were treated with WBRT in 3 Gy per fraction with 10 fractions, and then received chemotherapy in a time frame starting from 0 to 7 days after radiotherapy. At a median follow-up of 17.3 months, 1-year CNS-PFS rate was 74.9% (95% CI 61.9-90.7%) and median CNS-PFS was 18 months (95% CI, 15.5 to NA months). One-year PFS rate was 66.9% (53.1-84.2%) and median PFS time was 17.6 months (95% CI 12.8-34.1 months). The best intracranial response rate (IC-ORR: complete response and partial response) was 92.5% (37/40). The most common grade 3 or worse toxicity was diarrhea (7.5%) and asymptomatic radiation necrosis was detected in 4 of 67(6.0%) lesions treated with FSRT. No differences of neurocognitive function evaluated by MMSE (Mini-Mental State Exam) were observed between different groups at any time point. Radiotherapy combined with pyrotinib and capecitabine resulted in a promising efficacy that crossed the pre-specified boundary in patients with HER2-positive advanced breast cancer with brain metastases. This is the first prospective study showing the efficacy and safety of CNS radiotherapy concurrent with pyrotinib and capecitabine in patients with BM from HER2-positive breast cancer. Further investigation in a randomized controlled study is warranted.

Breast cancer progression and kynurenine pathway enzymes are induced by hexachlorobenzene exposure in a Her2-positive model.

Breast cancer is one of the leading cancers among women worldwide. Given the evidence that pesticides play an important role in breast cancer, interest has grown in pesticide impact on disease progression. Hexachlorobenzene (HCB), an aryl hydrocarbon receptor (AhR) ligand, promotes triple-negative breast cancer cell migration and invasion. Estrogen receptor β (ERβ) inhibits cancer motility, while G protein-coupled ER (GPER) modulates the neoplastic transformation. Tryptophan is metabolized through the kynurenine pathway by indoleamine-2,3-dioxygenase (IDO) and tryptophan-2,3-dioxygenase (TDO), with kynurenine signaling activation often predicting worse prognosis in cancer. In this context, we examined the HCB (0.005; 0.05; 0.5 and 5μM) effect on LM3 cells, a human epidermal growth factor receptor 2 (HER2)-positive breast cancer model. Results show that HCB increases IDO and TDO mRNA levels and promotes cell viability, proliferation and migration through the AhR pathway. Moreover, HCB boosts mammosphere formation, vascular endothelial growth factor and cyclooxygenase-2 expression and reduces IL-10 levels. For some parameters, U-shaped or inverted U-shaped dose-response curves are shown. HCB alters ER levels, reducing ERβ while increasing GPER. These results demonstrate that exposure to environmentally relevant concentrations of HCB up-regulates the kynurenine pathway and dysregulates ERβ and GPER levels, collaborating in HER2-positive breast cancer progression.

Abstract P5-02-41: UBE2E3 promotes the progression of HER2-positive breast cancer and influences the efficacy of targeted therapy via EGFR stabilization

Abstract Background: In the past 20 years, the efficacy and prognosis of HER2-positive breast cancer have significantly improved. However, nearly 50% of patients still have residual invasive tumors after chemotherapy combined with dual-targeted neoadjuvant therapy, especially for those with disease progression during treatment. A lack of effective therapeutic regimens results from the failure of targeted therapy, whose heterogeneity is especially worthy of our attention. The aim of this study was to look for efficacy markers and investigate new drug-resistance mechanisms. Methods: Firstly, the high-throughput sequencing data from 81 patients who received neoadjuvant chemotherapy TCbH (paclitaxel + carboplatin + trastuzumab) was analyzed by the efficacy outcomes. They were divided into 8 patients with stable or progressive disease (SD/PD), 35 with partial response (PR), and 38 with pathological complete remission (pCR). Then, UBE2E3 was chosen from the different expression genes between SD/PD and pCR based on efficacy results and the weighted gene co-expression network (WGCNA). UBE2E3 clinical correlations were investigated using publicly available data from The Cancer Genome Atlas (TCGA) and the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC), and UBE2E3 was validated using immunohistochemistry (IHC) on 200 HER2-positive breast cancer tissue chips. Further, the UBE2E3 knockdown and overexpression stable transfer cell lines were constructed, and the effects of UBE2E3 on cell proliferation, clone formation, and drug sensitivity were verified by live cell imaging, the CCK8 assay, plate cloning, and IC50 assays, respectively. The tumor growth of UBE2E3 in vivo was investigated by an in situ transplantation tumor assay in nude mice. Meanwhile, the p-RB assay of mouse tissues by IHC was used to explore the effect of UBE2E3 on cell proliferation. RNA-seq was used to screen the downstream molecules of UBE2E3. Western blotting was used to verify the results of bioinformatics analysis and to explore the downstream key molecules. The protease inhibitor MG132 and actinomycin CHX were used to look at the effect on the stability of the target protein. Immunoprecipitation and silver staining assays were used to find interacting proteins with the UBE2E3. Results: Ten hub-genes which were efficacy-related were identified by WGCNA analysis, in which UBE2E3 was highly expressed in the SD/PD group (p < 0.05). In HER2-positive breast cancer, high expression of UBE2E3 was associated with poor prognosis and decreased disease-free survival both in public data and Fudan University Shanghai Cancer Center (FUSCC) data [HR 2. 36, (1.25–4.47), p < 0.05]. The experimental results demonstrated that UBE2E3 promoted the proliferation of HER2-positive breast cancer cells, enhanced clone formation, and resisted lapatinib’s treatment in cellular phenotype; and that UBE2E3 promoted tumor growth in vivo and upregulated the expression of p-RB. The differentially expressed genes’ sets of the RNA-seq between overexpressed cell lines and control showed that overexpressing UBE2E3 activated the EGFR pathway. Further, an immunoblot assay confirmed that UBE2E3 positively regulated EGFR levels and activated the downstream MAPK pathway. The proteasome inhibitor MG132 and CHX assays showed that UBE2E3 could stabilize EGFR proteins. The co-immunoprecipitation and silver staining assays showed that UBE2E3 stabilized EGFR proteins by interacting with c-Cbl. Conclusion: UBE2E3 could negatively affect the efficacy of HER2-positive breast cancer therapy and is significantly associated with poor prognosis. UBE2E3 may serve as a potential marker of efficacy and prognosis for HER2-positive breast cancer in the future. Therapeutic efficacy is affected by UBE2E3, which binds to c-Cbl and causes upregulation of EGFR expression in vivo, which in turn causes the MAPK pathway to be activated and tumor growth to be pushed up. Citation Format: Pei Li, Wei-Ru Chi, Bingqiu Xiu, Qi Zhang, Liyi Zhang, Ming Chen, Jingyan Xue, Xiaoyan Huang, Yayun Chi, Jiong Wu. UBE2E3 promotes the progression of HER2-positive breast cancer and influences the efficacy of targeted therapy via EGFR stabilization [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P5-02-41.

Abstract P6-14-07: Genetic ablation of ACF7, a member of the +TIP family of microtubule-binding proteins, impairs metastasis of HER2-positive breast cancer

Abstract Breast cancer is the leading cause of cancer death in women worldwide. Among the different subtypes of this disease, HER2-positive breast cancer is known to be one of the most aggressive and is linked to poor prognosis. This subtype is prone to develop metastases, reflecting a significant cellular plasticity. While the molecular machinery controlling actin dynamics is well implicated in cell invasion, the contribution of the microtubules is ill-defined. We recently conducted a functional screen to identify such regulators, and characterized ACF7, a microtubule plus-end binding protein (+TIP), as a new promoter of invasion. Here, we aim to determine the in vivo contribution of ACF7 to tumor progression and to reveal the cellular and molecular mechanisms allowing this +TIP to promote metastasis. We analyzed the expression of ACF7 at the protein level across a panel of tumor microarrays and found that it is detectable in all breast cancer subtypes with the highest levels seen in HER2-positive. To study the role of ACF7 during tumor progression, we generated an ACF7 genetically engineered mouse model of breast cancer. We exploited a HER2-positive breast cancer mouse model (MMTV-NIC) that we bred with ACF7Flox mice. This approach allows for conditional deletion of ACF7 in mammary glands and represents a powerful model to define the roles of ACF7 in HER2-driven breast cancer. Our results show that ACF7 is not involved in tumor initiation and tumor growth as no difference between number of nodules per mouse, tumor mass or number of mammary intraepithelial neoplastic lesions was shown. However, our results show a significant decrease in lung metastasis in the ACF7cKO mice. To gain mechanistic insights into the roles of ACF7 in this specific process, we derived primary cell lines from tumors isolated from MMTV-NIC-ACF7WT and MMTV-NIC-ACF7cKO mice. We explored if ACF7 contributes to migration and invasion in a HER2 context. By using live-cell imaging, we demonstrated that ACF7-null cells display defects in both random and directed cell migration, as they show a delay in wound closure. We determined that ACF7KO cells show an increase in focal adhesions size, and exhibit defects in reorienting their actin and microtubules cytoskeletons parallel to the direction of migration. ACF7 was also found to promote cell invasion since ACF7KO cells were less efficient to cross a Matrigel membrane. To investigate the metastatic potential of ACF7-null tumors, we performed RNA-sequencing using RNA isolated from MMTV-NIC-ACF7WT and MMTV-NIC-ACF7cKO tumors. We identified a striking change in expression of genes involved in epithelial to mesenchymal transition (EMT), such as for example E-cadherin, Vimentin or the transcription factor Twist. These results suggest that ACF7 promotes metastasis through maintaining an EMT state in HER2 breast cancer cells. Collectively, our work demonstrates ACF7 as an important player in HER2 positive breast cancer progression via its functions in both cell migration and cell invasion. This works also suggests that developing approaches to therapeutically target regulators of microtubule dynamics may reveal new opportunities to decrease tumor progression and metastatic expansion. Citation Format: Rebecca Cusseddu, Jean-François Côté. Genetic ablation of ACF7, a member of the +TIP family of microtubule-binding proteins, impairs metastasis of HER2-positive breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-14-07.

Abstract P1-13-05: Extracellular vesicles-transported lncRNA BCDR1 promotes tumor cell proliferation and therapy resistance via upregulating G1/S-phase transition in breast cancer

Abstract Background Extracellular vesicles (EVs), secreted by tumor cells for intercellular communication, play an important role in breast cancer progression. Previous studies have proved that lncRNA could use EVs to transmit signals and affect the progression and treatment of breast cancer. In addition, a previous study has found that, in HER2 therapy-resistant tumors, CDK4/6 activity and cell cycle progression genes were involved and might serve as treatment targets. However, recent clinical trials were not supportive of the use of CDK4/6 inhibitors in HER2 enriched internal subtypes of breast cancer. In this study, we aim to explore the role of EVs-transported long noncoding RNA BCDR1 in the promotion of cell cycle progression in HER2-positive breast cancer, exploring a new potential target in combination with CDK4/6 inhibitor and anti-HER2 treatment. Methods Samples were collected from patients with HER2 overexpression receiving neoadjuvant therapy. RNA-seq was performed to identify differentially expressed RNAs between pathological complete response (pCR) and non-pCR group. In addition, serum extracellular vesicles were collected and determined through RNA-seq. The drug response and proliferation rate of tumor cells were measured in breast cancer cells (HCC-1954, BT-474 and MCF-7). Quantitative RT-PCR (qRT-PCR) was used to detect the expression levels of BCDR1 and its potential target genes. RNA-seq and GSEA analysis was carried out to determine the target pathways regulated by BCDR1. DNA fiber assay, mass spectrometry, and flow cytometry were used to understand the underlying mechanism of BCDR1. Results Core needle biopsy tissues from HER2-positive breast cancer patients with any ER status were collected before NAC. Among genes differentially overexpressed, BCDR1 was found to be downregulated in pCR group compared with non-pCR group. BCDR1 was also elevated in plasma EVs in the non-pCR group. In addition, overexpression of BCDR1 in breast cancer cells promoted cell proliferation and HER2 treatment resistance. Through pathway analysis, we found BCDR1 could facilitate G1/S-phase transition. Flow cytometry confirmed these findings. We also noticed that proteins that regulate DNA licensing including minichromosome maintenance proteins (MCMs) were enriched in BCDR1 overexpression cells. Through DNA fiber assay, we confirmed that BCDR1 could promote DNA replication initiation. Interestingly, under CDK4/6 inhibitor treatment, BCDR1 was induced, unrevealing an internal treatment-resistant mechanism in these tumor cells. Through EVs RT-qPCR, we found BCDR1 could transport from high expression cells to low, with the same biological function. We also explored antisense oligonucleotide (ASO) use in the inhibition of BCDR1 biological function and transportation. Conclusion BCDR1 promotes cell proliferation and therapy resistance via upregulating DNA licensing in breast cancer. BCDR1 could transported through EVs with same biological function. This study also suggests that BCDR1 could serve as a biomarker and therapeutic target in breast cancer. Citation Format: Qi Zhang, Bingqiu Xiu, Yayun Chi, Jiong Wu. Extracellular vesicles-transported lncRNA BCDR1 promotes tumor cell proliferation and therapy resistance via upregulating G1/S-phase transition in breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-13-05.

Pathophysiological role of ion channels and transporters in HER2-positive breast cancer.

The incidence of breast cancer (BC) has been increasing each year, and BC is now the most common malignant tumor in women. Among the numerous BC subtypes, HER2-positive BC can be treated with a variety of strategies based on targeting HER2. Although there has been great progress in the treatment of HER2-positive BC, recurrence, metastasis and drug resistance remain considerable challenges. The dysfunction of ion channels and transporters can affect the development and progression of HER2-positive BC, so these entities are expected to be new therapeutic targets. This review summarizes various ion channels and transporters associated with HER2-positive BC and suggests potential targets for the development of new and effective therapies.

P020 - Upregulation of SLC26A9 resulted in the development and progression of HER2-positive breast cancer via activating PI3 K/ AKT signaling pathway

P020 - Upregulation of SLC26A9 resulted in the development and progression of HER2-positive breast cancer via activating PI3 K/ AKT signaling pathway

Abstract PS19-27: Upregulation of SLC26A9 resulted in the development and progression of HER2 positive breast cancer via activating TGFβ signaling pathway

Abstract Background: Slc26a9 (Solute carrier family 26 member 9) is a member of Slc26a family of multifunctional anion transporters, which functions as Cl- channel (Liu et al., Front Physiol 2018). Our previous study showed that SLC26A9 deficiency results in the development and progression of gastric cancer, which demonstrated that the key role of SLC26A9 in the tumorigenesis first time (Liu et al., Gastroenterology 2018). However, what’s the role of SLC26A9 in the breast cancer (BC) onset is not clear. We therefore wondered whether Slc26a9 gene is involved in promoting breast carcinogenesis and its mechanisms. Methods: The tissue microarrays and IHC assay were used to detect the expression and clinic relevance of SLC26A9 in the human BC. Different BC cell lines were used to investigate the expression and function of SLC26A9 in the BC. SLC26A9 gene transfect and knockout experiment were performed to detect the regulator role of SLC26A9 in BC cell behaviors. Results: Compared with adjacent normal tissues, SLC26A9 expression was significantly increased in the BC tissue, SLC26A9 expression level in BC correlated with the differentiated state of BC and patient’s clinical outcome, indicating that SLC26A9 may be involved in BC pathogenesis and progression in humans and it might be a novel poor prognosis marker for BC. Moreover, HER2 positive BC tissues exhibited high SLC26A9 expression than HER2 negative BC tissues. Compared with normal mammary cell line, SLC26A9 was significantly upregulated in the all BC cell lines, with highest expression in HER2 enriched cell line SKBR3. Deletion of SLC26A9 in SKBR3 resulted in inhibition of BC cell proliferation, migration and invasion, but promotion of cell apoptosis, which were investigated by different cell function assays, including cell counting Kit-8, cell proliferation curve, Annexin VFITC/PI double staining, Wound-healing and transwell assays respectively. Moreover, SLC26A9 deficiency in SKBR3 caused alteration of epithelial mesenchymal transition (EMT) markers, including downregulation of N-cadherin, Snail1, Fibronectin and Vimentin, but increasement of E-cadherin and ZO-1, accompany with disrupting TGFβ signaling pathways, including downregulation of TGF-β1, p-Smad2 and p-Smad3. However, overexpression of SLC26A9 in SKBR3 resulted in inhibition of cell proliferation, migration and invasion, but promotion of cell apoptosis. Accompanying with activation of TGFβ pathway mediate EMT. Conclusions: Upregulation of SLC26A9 resulted in the development and progression of HER2 positive BC via activation of TGFβ signaling pathways. SLC26A9 might be a novel prognosis marker and therapeutic target for BC. Citation Format: Zhiyuan Ma, Xuemei Liu, Chengli Lu, Jiaxing Zhu, Xiaoming Cheng, Biguang Tuo, Taolang Li. Upregulation of SLC26A9 resulted in the development and progression of HER2 positive breast cancer via activating TGFβ signaling pathway [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS19-27.

Trastuzumab beyond progression in HER2-positive metastatic breast cancer.

Background: The data about continuing trastuzumab treatment beyond progression in HER2-positive breast cancer are lacking in Iraq. This study aimed for investigating the use of trastuzumab in Iraqi women with metastatic HER2-positive breast cancer. Methods: A single-arm non-comparative observational prospective study was conducted in Oncology Teaching Hospital between 2013 and 2019. The study included patients with metastatic HER2-positive breast cancer progressing after first-line chemotherapy plus trastuzumab. Results: Only 16 (27%) cases had tumor progression while on second-line trastuzumab. Median time to progression was 16 months (95% CI: 11.0 – 20.9). Fifty-five (93%) patients had a progression-free survival of ≥ 6 months, whereas 32 (54%) had a progression-free survival of ≥ 12 months. Conclusion: The continuing trastuzumab beyond progression has clinical benefits in HER2-positive metastatic breast cancer patients. Funding Statement: This study was sponsored and funded by Hoffmann-La Roche Ltd., Iraq. Declaration of Interests: None. Ethics Approval Statement: The study protocol was approved by the local ethics committee of the hospital (MOH Approval No. 11). A verbal informed consent was collected from all participants.

Trastuzumab Beyond Progression in HER2-Positive Metastatic Breast Cancer

Background: The data about continuing trastuzumab treatment beyond progression in HER2-positive breast cancer are lacking in Iraq. This study aimed for investigating the use of trastuzumab in Iraqi women with metastatic HER2-positive breast cancer. Methods: A single-arm non-comparative observational prospective study was conducted in Oncology Teaching Hospital between 2013 and 2019. The study included patients with metastatic HER2-positive breast cancer progressing after first-line chemotherapy plus trastuzumab. Results: Only 16 (27%) cases had tumor progression while on second-line trastuzumab. Median time to progression was 16 months (95% CI: 11.0 – 20.9). Fifty-five (93%) patients had a progression-free survival of ≥ 6 months, whereas 32 (54%) had a progression-free survival of ≥ 12 months. Conclusion: The continuing trastuzumab beyond progression has clinical benefits in HER2-positive metastatic breast cancer patients. Funding Statement: This study was sponsored and funded by Hoffmann-La Roche Ltd., Iraq. Declaration of Interests: None. Ethics Approval Statement: The study protocol was approved by the local ethics committee of the hospital (MOH Approval No. 11). A verbal informed consent was collected from all participants.

Development of a risk scoring system for evaluating the prognosis of patients with Her2-positive breast cancer

BackgroundAs one of the many breast cancer subtypes, human epidermal growth factor receptor 2 (Her2)-positive breast cancer has higher invasiveness and poor prognosis, although the advent of anti-Her2 drugs has brought good news to patients. However, the emergence of drug resistance still limits its clinical efficacy, so there is an urgent need to explore new targets and develop a risk scoring system to improve treatments and evaluate patient prognosis.MethodsDifferentially expressed mRNAs associated with Her2-positive breast cancer were screened from a TCGA cohort. The prognostic risk scoring system was constructed according to univariate and Lasso Cox regression model analyses and combined with clinical factors (such as age and TNM) for univariate and multivariate analyses to verify the specificity and sensitivity of the risk scoring system. Finally, based on correlation and CNV mutation analyses, we explored the research value of the mRNAs involved in the system as key genes of the model.ResultsIn this study, six mRNAs were screened and identified to construct a prognostic risk scoring system, including four up-regulated mRNA (RDH16, SPC25, SPC24, and SCUBE3) and two down-regulated mRNA (DGAT2 and CCDC69). The risk scoring system can divide Her2-positive breast cancer samples into high-risk and low-risk groups to evaluate patient prognosis. In addition, whether through the time-dependent receiver operating characteristics curve or compared with clinical factors, the risk scoring system showed high predictive sensitivity and specificity. Moreover, some CNV mutations in mRNA increase patient risk by influencing expression levels.ConclusionThe risk scoring system constructed in this study is helpful to improve the screening of high-risk patients with Her2-positive breast cancer and is beneficial for implementing early diagnosis and personalized treatment. It is suggested that these mRNAs may play an important role in the progression of Her2-positive breast cancer.

AK4 Promotes the Progression of HER2-Positive Breast Cancer by Facilitating Cell Proliferation and Invasion.

Breast cancer (BC) is a type of malignant tumor originating from the epithelial tissue of the mammary gland, and about 20% of breast cancers are human epidermal growth factor receptor 2 positive (HER2+), which is a subtype with more aggression. Recently, HER2-positive breast cancer is often accompanied by poor prognosis of patients, and targeted therapy showed a promising prospect. To combat this disease, novel therapeutic targets are still needed. Adenylate kinase 4 (AK4) is a member of the adenylate kinase family and is expressed in the mitochondrial matrix. AK4 is involved in multiple cellular functions such as energy metabolism homeostasis. Interestingly, AK4 was observed highly expressed in several tumor tissues, and the involvement of AK4 in cancer development was generally revealed. However, the possible role of AK4 on the growth and development of breast cancer is still unclear. Here, we investigated the possible functions of AK4 on the progression of HER2-positive breast cancer. We found the high expression of AK4 in HER2-positive breast cancer tissues from patients who received surgical treatment. Additionally, AK4 expression levels were obviously correlated with clinical-pathological features, including pTNM stage (P = 0.017) and lymph node metastasis (P = 0.046). We mechanically confirmed that AK4 depletion showed the obvious impairment of cell proliferation and invasion in MCF7 and MDA-MB-231 cells. AK4 also facilitates tumor growth and metastasis of HER2-positive breast cancer in vivo. In conclusion, we identified and mechanically confirmed that AK4 is a novel therapeutic target of HER2-positive breast cancer.

Abstract 19: Trastuzumab resistance accompanies vasculogenic mimicry in HER2-positive breast cancer cells

Abstract Trastuzumab (Tzm) is a drug that targets HER2/ERBB2/Neu, and is essential for the treatment of HER2-positive breast cancer. However, resistance to the drug is a major obstacle in controlling the progression of this devastating disease. We hypothesized that Tzm load might induce a phenotypic change in HER2-positive breast cancer cells, enabling them to escape and survive Tzm activity. We conducted comprehensive immunophenotyping to detect the phenotypic changes in HER2-positive breast cancer cells loaded with Tzm, and compared the immunophenotype of Tzm-loaded cells with that of control cells based on the criteria determined a priori. Out of 242 cell surface antigens, 9 antigens were significantly upregulated and 3 were significantly downregulated. Surprisingly, all the antigens were related to endothelial and stem cell phenotypes, suggesting that Tzm load induced vasculogenic mimicry (VM). Moreover, we found VM markers like COX2, MMP2, MMP14, phospho-SMAD2/3, VEGFA, HIF1A, and TWIST1 to be upregulated in Tzm-loaded cells. However, Tzm-loaded cells did not exhibit tube formation on Matrigel, a hallmark of VM. Since the Tzm-loaded cells were still sensitive to Tzm, we used three Tzm-resistant cell lines to investigate if Tzm resistance accompanied VM. All Tzm-resistant cell lines exhibited tube formation on Matrigel. Importantly, several growth factors including EGF, FGF2, IGF1, and VEGF promoted VM in these cells, suggesting that single molecular-targeted drugs did not effectively inhibit VM as other growth factors could quickly compensate the VM pathways. We then examined if eribulin, a tubulin-binding chemotherapeutic drug that promotes vascular remodeling, inhibited VM in Tzm-resistant cells. Eribulin inhibited tube formation in Tzm-resistant cells at a clinically relevant concentration. In conclusion, Tzm load induces an incomplete vasculogenic phenotype in HER2-positive breast cancer cells. The cells exhibit VM after eventually acquiring Tzm resistance. Since VM drives metastasis, its regulation in Tzm-resistant HER2-positive breast cancer appears to be a promising approach in suppressing the progression of HER2-positive breast cancer. Citation Format: Masafumi Shimoda, Ami Hori, Shinzaburo Noguchi. Trastuzumab resistance accompanies vasculogenic mimicry in HER2-positive breast cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 19.

The Receptor Tyrosine Kinase AXL Is Required at Multiple Steps of the Metastatic Cascade during HER2-Positive Breast Cancer Progression

AXL is activated by its ligand GAS6 and is expressed in triple-negative breast cancer cells. In the current study, we report AXL expression in HER2-positive (HER2+) breast cancers where it correlates with poor patient survival. Using murine models of HER2+ breast cancer, Axl, but not its ligand Gas6, was found to be essential for metastasis. We determined that AXL is required for intravasation, extravasation, and growth at the metastatic site. We found that AXL is expressed in HER2+ cancers displaying epithelial-to-mesenchymal transition (EMT) signatures where it contributes to sustain EMT. Interfering with AXL in a patient-derived xenograft (PDX) impaired transforming growth factor β (TGF-β)-induced cell invasion. Last, pharmacological inhibition of AXL specifically decreased the metastatic burden of mice developing HER2+ breast cancer. Our data identify AXL as a potential anti-metastatic co-therapeutic target for the treatment of HER2+ breast cancers.

The Receptor Tyrosine Kinase AXL Is Required at Multiple Steps of the Metastatic Cascade During HER2-Positive Breast Cancer Progression

AXL is activated by its ligand GAS6 and is expressed in triple-negative breast cancer cells. In the current study, we report that AXL is also expressed in HER2 breast cancers where it correlates with poor patient survival. Using murine models of HER2 breast cancer, Axl, but not Gas6, was found to be essential for metastasis. We determined that AXL is required for intravasation, extravasation and growth at the metastatic site. AXL is expressed in HER2 cancers displaying EMT signatures where it contributes to sustained EMT. Interfering with AXL in a patient-derived xenograft impaired TGF-β-induced cell invasion. Lastly, pharmacological inhibition of AXL decreased the metastatic burden of mice developing HER2 breast cancer. Our data identify AXL as a potential anti-metastatic, co-therapeutic target for the treatment of HER2 breast cancers.

Amphiregulin regulates proliferation and migration of HER2-positive breast cancer cells.

Tumor initiation and progression rely on cellular proliferation and migration. Many factors are involved in these processes, including growth factors. Amphiregulin (AREG) is involved in normal mammary development and the development of estrogen receptor (ER)-positive breast cancer. The aim of this project was to determine if AREG is involved in the proliferation and progression of HER2-positive breast cancer. Mouse cell lines MMTV-neu, HC-11 and COMMA-D, as well as human cell lines MCF10A, SKBR3, HCC1954 and BT474 were used. Real-time PCR was used to quantify AREG expression and neutralizing antibodies were used to reduce the autocrine/paracrine effects of AREG. Transfections using siRNA and shRNA were used to knockdown AREG expression in the cancer cell lines. Free-floating sphere formation, colony forming, scratch wound and Transwell assays were used to assess the proliferation, tumor forming and migratory capacities of transfected cancer cells. We found AREG expression in both normal epithelial cell lines and tumor-derived cell lines. Knockdown of AREG protein expression resulted in reduced sphere sizes and reduced sphere numbers in both mouse and human cancer cells that overexpress erbB2/HER2. AREG was found to be involved in cancer cell migration and invasion. In addition, we found that AREG expression knockdown resulted in different migration capacities in normal and erbB2/HER2 overexpressing cancer cells. Based on our results we conclude that AREG is involved in regulating the proliferation and migration of erbB2/HER2-positive breast cancer cells.

The CBM Complex Underwrites NF-κB Activation to Promote HER2-Associated Tumor Malignancy

The HER2/Neu protein is overexpressed in a large fraction of human breast cancers. NF-κB is one of several transcription factors that are aberrantly activated in HER2-positive breast cancers; however, the molecular mechanism by which HER2 activates NF-κB remains unclear. The CARMA3-BCL10-MALT1 (CBM) complex is required for GPCR- and EGFR-induced NF-κB activation. In the current study, the role of the CBM complex in HER2-mediated NF-κB activation and HER2-positive breast cancer was investigated. Interestingly, HER2-mediated NF-κB activation requires protein kinase C (PKC) activity rather than AKT activity. Using biochemical and genetic approaches, it was shown that the CBM complex is required for HER2-induced NF-κB activation and functionally contributes to multiple properties of malignancy, such as proliferation, avoidance of apoptosis, migration, and invasion, both in vitro and in vivo. In addition, CARMA3-mediated NF-κB activity was required for the upregulation of two matrix metalloproteinases (MMP), MMP1 and MMP13, both of which contribute to tumor metastasis. To further access the physiologic role of CBM complex-mediated NF-κB activation in HER2-positive breast cancer progression, Malt1 knockout mice (Malt1(-/-)) were crossed with MMTV-Neu mice, in which mammary tumors spontaneously developed with HER2 overexpression. We observed delayed onset and prolonged progression time in mammary tumors in Malt1 knockout mice compared with control mice. In summary, these data demonstrate that the CBM complex is a crucial component mediating HER2-induced NF-κB signaling and tumor malignancy in HER2-positive breast cancer. The CBM complex bridges key signaling pathways to confer malignant phenotypes and metastatic potential in HER2-associated breast cancer.

Akt phosphorylates and activates HSF-1 independent of heat shock, leading to Slug overexpression and epithelial–mesenchymal transition (EMT) of HER2-overexpressing breast cancer cells

Epithelial-mesenchymal transition (EMT) is an essential step for tumor progression, although the mechanisms driving EMT are still not fully understood. In an effort to investigate these mechanisms, we observed that heregulin-mediated activation of HER2, or HER2 overexpression, resulted in EMT, which is accompanied with increased expression of a known EMT regulator Slug, but not TWIST or Snail. We then investigated how HER2 induced Slug expression and found, for the first time, that there are four consensus HSF Sequence-binding Elements (HSEs), the binding sites for heat shock factor-1 (HSF-1), located in the Slug promoter. HSF-1 bound to and transactivated the Slug promoter independent of heat shock, leading to Slug expression in breast cancer cells. Mutation of the putative HSEs ablated Slug transcriptional activation induced by heregulin or HSF-1 overexpression. Knockdown of HSF-1 expression by siRNA reduced Slug expression and heregulin-induced EMT. The positive association between HSF-1 and Slug was confirmed by immunohistochemical staining of a cohort of 100 invasive breast carcinoma specimens. While investigating how HER2 activated HSF-1 independent of heat shock, we observed that HER2 activation resulted in concurrent phosphorylation of Akt and HSF-1. We then observed, also for the first time, that Akt directly interacted with HSF-1 and phosphorylated HSF-1 at S326. Inhibition of Akt using siRNA, dominant-negative Akt mutant, or small molecule inhibitors prevented heregulin-induced HSF-1 activation and Slug expression. Conversely, constitutively active Akt induced HSF-1 phosphorylation and Slug expression. HSF-1 knockdown reduced the ability of Akt to induce Slug expression, indicating an essential that HSF-1 plays in Akt-induced Slug upregulation. Together, our study uncovered the existence of a novel Akt-HSF-1 signaling axis that leads to Slug upregulation and EMT, and potentially contributes to progression of HER2-positive breast cancer.