Histological Subtype Of Breast Cancer Research Articles

Spatial transcriptomics reveals gene expression characteristics in invasive micropapillary carcinoma of the breast

Invasive micropapillary carcinoma (IMPC) is a special histological subtype of breast cancer, featured with extremely high rates of lymphovascular invasion and lymph node metastasis. Based on a previous series of studies, our team proposed the hypothesis of “clustered metastasis of IMPC tumor cells”. However, the transcriptomics characteristics underlying its metastasis are unknown, especially in spatial transcriptomics (ST). In this paper, we perform ST sequencing on four freshly frozen IMPC samples. We draw the transcriptomic maps of IMPC for the first time and reveal its extensive heterogeneity, associated with metabolic reprogramming. We also find that IMPC subpopulations with abnormal metabolism are arranged in different spatial areas, and higher levels of lipid metabolism are observed in all IMPC hierarchical clusters. Moreover, we find that the stromal regions show varieties of gene expression programs, and this difference depends on their distance from IMPC regions. Furthermore, a total of seven IMPC hierarchical clusters of four samples share a common higher expression level of the SREBF1 gene. Immunohistochemistry results further show that high SREBF1 protein expression is associated with lymph node metastasis and poor survival in IMPC patients. Together, these findings provide a valuable resource for exploring the inter- and intra-tumoral heterogeneity of IMPC and identify a new marker, SREBF1, which may facilitate accurate diagnosis and treatment of this disease.

Triple-Negative Breast Cancer Histological Subtypes with a Favourable Prognosis.

Simple SummaryBreast cancers that lack expression of the predictive markers oestrogen receptor, progesterone receptor and human epidermal growth factor receptor-2 are known as triple-negative breast cancers (TNBCs) and are generally considered to have a poor prognosis. As available targeted treatments are not effective, aggressive chemotherapy is frequently advocated for patients with TNBC. It is now becoming apparent that TNBC is not one entity but constitutes a range of malignancies with different clinical behaviour. This paper reviews 7 distinct histological subtypes of TNBC where the overall prognosis is favourable, and aggressive systemic treatment is generally not indicated. Their recognition and separation from the larger group of no special type TNBC are important. The members of the European Working Group for Breast Screening Pathology review the morphology, known molecular features and reported outcomes, and formulate a consensus statement regarding the approach to the subtypes that are associated with a favourable prognosis.Triple-negative breast cancers (TNBC), as a group of tumours, have a worse prognosis than stage-matched non-TNBC and lack the benefits of routinely available targeted therapy. However, TNBC is a heterogeneous group of neoplasms, which includes some special type carcinomas with a relatively indolent course. This review on behalf of the European Working Group for Breast Screening Pathology reviews the literature on the special histological types of BC that are reported to have a triple negative phenotype and indolent behaviour. These include adenoid cystic carcinoma of classical type, low-grade adenosquamous carcinoma, fibromatosis-like metaplastic carcinoma, low-grade mucoepidermoid carcinoma, secretory carcinoma, acinic cell carcinoma, and tall cell carcinoma with reversed polarity. The pathological and known molecular features as well as clinical data including treatment and prognosis of these special TNBC subtypes are summarised and it is concluded that many patients with these rare TNBC pure subtypes are unlikely to benefit from systemic chemotherapy. A consensus statement of the working group relating to the multidisciplinary approach and treatment of these rare tumour types concludes the review.

Circular RNA circ-ERBB2 Elevates the Warburg Effect and Facilitates Triple-Negative Breast Cancer Growth by the MicroRNA 136-5p/Pyruvate Dehydrogenase Kinase 4 Axis.

Triple-negative breast cancer (TNBC) is an aggressive histological subtype of breast cancer. It has been reported that the circular RNA (circRNA) circ-ERBB2 (circBase identifier hsa_circ_0007766) is mainly distributed in the cytoplasm of TNBC cells and promotes the proliferation and invasion of TNBC cells. This study aimed to explore the molecular mechanism of circ-ERBB2 regulating the progression of TNBC. The expression of circ-ERBB2 was detected by quantitative real-time PCR (qRT-PCR). Loss-of-function experiments were performed to investigate the function of circ-ERBB2 in TNBC cells in vitro and in vivo. The regulatory mechanism of circ-ERBB2 was surveyed by bioinformatics analysis and dual-luciferase reporter and RNA immunoprecipitation (RIP) or RNA pulldown assays. We observed that circ-ERBB2 was overexpressed in TNBC, and TNBC patients with high circ-ERBB2 expression levels had a poor prognosis. Functionally, circ-ERBB2 knockdown constrained TNBC growth in vivo, reduced the Warburg effect, accelerated apoptosis, and repressed the proliferation, migration, and invasion of TNBC cells in vitro. Mechanically, circ-ERBB2 sponged microRNA 136-5p (miR-136-5p) to elevate pyruvate dehydrogenase kinase 4 (PDK4) expression. In conclusion, circ-ERBB2 facilitated the Warburg effect and malignancy of TNBC cells by the miR-136-5p/PDK4 pathway, at least in part. This study supports circ-ERBB2 as a prognostic indicator for TNBC.

S3168 Metastatic Breast Cancer to a J-Shaped Muscular Bag – The Stomach

Introduction: Female breast cancer was the leading cause of global cancer incidence in 2020, with an estimated 2.3 million new cases, representing 11.7% of all cancer cases. The most common primary target sites of breast cancer metastasis are bone, lung, liver, and brain. The stomach is an infrequent site of breast cancer metastasis, accounting for an incidence ranging from 0.3% in retrospective studies to 8-18% in autopsy series. Needless to say, metastasis to the stomach from any primary tumor is itself atypical, with an incidence of 0.2-1.7%. We present a case of breast cancer metastasis to the stomach from a rare histological subtype of breast cancer- glycogen-rich, clear cell breast carcinoma. Case Description/Methods: 75- year-old female with clear cell glycogen rich invasive carcinoma, stage IIIB of the right breast presented to the emergency department (ED) complaining of fatigue and weakness for two days. Vital signs were normal. Physical examination revealed ataxic gait and right-sided hemiparesis. Labs showed a hemoglobin of 7.5 g/dl (baseline 9.8 g/dl) and hematocrit 23.5% (baseline 30%). The following day her hemoglobin asymptomatically dropped to 6.8 g/dl, and a repeat reading showed a further decline to 5.8 g/dl. Two units of packed red blood cells (PRBC) were transfused, which increased her hemoglobin to 7.8 g/dl. Fecal Occult Blood Test (FOBT) was positive, and gastroenterology was consulted to investigate further. Computerized Tomography (CT) of the abdomen showed a 4.4 cm intraperitoneal mass in the left mid-abdomen highly suggestive of metastasis. Esophagogastroduodenoscopy (EGD) revealed several gastric ulcers on the greater aspect of the stomach's body located on the mucosal mound or raised mucosa (Figure 1). Given the undermining margins and the ulcer's location, there was increased suspicion for malignancy and she was diagnosed with metastatic poorly differentiated gastric adenocarcinoma. Due to the patient's low-performance status, hospice/palliative care was pursued. Discussion: The exact mechanism of gastric metastasis of breast cancer is still unclear. Gastric metastasis can have a negative impact on survival and must be investigated in patients with breast cancer who present with non-specific gastrointestinal symptoms. There should be a very high index of suspicion for a prompt diagnosis. In patients with a history of breast cancer, gastric endoscopy should be offered in cases of GI symptoms, even when the symptoms are vague.Figure 1.: Gastric perforation secondary to malignant gastric outlet obstruction.

The 21-Gene Recurrence Score in Special Histologic Subtypes of Breast Cancer.

Recurrence score (RS) testing was developed and validated in invasive ductal and rare lobular carcinomas, although it is used for all special types of breast cancers. To determine association of histologic type (HT) and RS, specifically high-risk RS. We used RSs linked to Surveillance, Epidemiology, and End Results Program registries of invasive breast cancers diagnosed in 2004 through 2015. Multivariable logistic regression was used to evaluate association between HT and high-risk RS. Relationships between HT and low-, intermediate-, and high-risk RS were compared with χ2 test. Kaplan-Meier curves were compared using log-rank test. A total of 110 318 patients had RS testing. Of these, 23 220 (21%) had low, 70 822 (64.2%) intermediate, and 16 276 (14.8%) high RS. Histologic types were 80 476 (73%) ductal, 12 713 (11.5%) lobular, 12 449 (11.3%) mixed, 2151 (2%) mucinous, 610 (0.6%) tubular, 382 (0.4%) micropapillary, 365 (0.3%) salivary, 208 (0.2%) papillary, 49 (0.04%) medullary, 26 (0.02%) metaplastic, 26 (0.02%) neuroendocrine, and 863 (0.8%) unknown. The distribution of low-, intermediate-, and high-risk RS was significantly different among HTs. Higher percentages of high-risk RS were identified in patients with ductal, medullary, and metaplastic types (P < .001). The odds of having high-risk RS were lower for some HTs, including micropapillary, after multivariable adjustment (P < .05). The low number of estrogen receptor-positive medullary and metaplastic carcinomas tested had higher odds of having high-risk RS. In T1 and T2 tumors, when ductal, lobular, mixed, and other types combined were compared, the mortality was different. This population-based study of RS in HTs showed high-risk RSs are identified in traditionally good prognostic subtypes. Micropapillary carcinoma has lower odds of high-risk RS even after multivariable adjustment.

Valproic Acid and Breast Cancer: State of the Art in 2021.

Simple SummaryBreast cancer (BC) is the most common cancer diagnosed among women worldwide. Despite numerous studies, the pathogenesis of BC is still poorly understood, and effective therapy of this disease remains a challenge for medicine. This article provides the current state of knowledge of the impact of valproic acid (VPA) on different histological subtypes of BC, used in monotherapy or in combination with other active agents in experimental studies in vitro and in vivo. The comprehensive review highlights the progress that has been made on this topic recently.Valproic acid (2-propylpentanoic acid, VPA) is a short-chain fatty acid, a member of the group of histone deacetylase inhibitors (HDIs). VPA has been successfully used in the treatment of epilepsy, bipolar disorders, and schizophrenia for over 50 years. Numerous in vitro and in vivo pre-clinical studies suggest that this well-known anticonvulsant drug significantly inhibits cancer cell proliferation by modulating multiple signaling pathways. Breast cancer (BC) is the most common malignancy affecting women worldwide. Despite significant progress in the treatment of BC, serious adverse effects, high toxicity to normal cells, and the occurrence of multi-drug resistance (MDR) still limit the effective therapy of BC patients. Thus, new agents which improve the effectiveness of currently used methods, decrease the emergence of MDR, and increase disease-free survival are highly needed. This review focuses on in vitro and in vivo experimental data on VPA, applied individually or in combination with other anti-cancer agents, in the treatment of different histological subtypes of BC.

Abstract 2993: Intraductal xenografts model ERα-positive invasive lobular carcinoma of the breast

Abstract Invasive lobular carcinoma (ILC) is the most frequent special histological subtype of breast cancer, typically characterized by loss of E-cadherin. It has clinical features distinct from other estrogen receptor-positive (ER+) breast cancers but the molecular mechanisms underlying its characteristic biology are poorly understood because we lack experimental models to study them. By xenografting lobular cells to the milk ducts, we recapitulate the human disease, including invasion and metastasis to clinically relevant organs. Using patient-derived intraductal xenografts from lobular and non-lobular ER+ HER2- tumors to compare global gene expression we identify extracellular matrix modulation as a lobular carcinoma cell-intrinsic trait. Analysis of TCGA patient datasets shows matrisome signature is enriched in lobular carcinomas with overexpression of elastin, collagens, and the collagen modifying enzyme LOXL1. Pharmacological treatment and silencing of LOXL1 expression decrease tumor growth, invasion, and metastasis by disrupting ECM structure resulting in decreased ER signaling. We conclude that LOXL1 inhibition is a promising therapeutic strategy for ILC. This is the first study of a hormone-responsive ER+ preclinical lobular model that mimics their clinical counterparts and opens opportunities for the development and evaluation of therapies. Citation Format: George Sflomos , Laura Battista, Patrick Aouad, Fabio De Martino, Valentina Scabia, Athina Stravodimou, Ayyakkannu Ayyanan, Assia Ifticene-Treboux, RLS, Philipp Bucher, Maryse Fiche, Giovanna Ambrosini, Cathrin Brisken. Intraductal xenografts model ERα-positive invasive lobular carcinoma of the breast [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2993.

Outcomes of patients with invasive mucinous and tubular carcinomas of the breast.

Invasive tubular carcinoma (ITC) and invasive mucinous carcinoma (IMC) of the breast are rare histologic subtypes of breast cancer associated with favorable prognoses. The aim of our study was to investigate the outcomes for these rare subtypes using the National Cancer Database. Female patients diagnosed with ITC or IMC between 2005 and 2014 were analyzed. The primary outcome was overall survival (OS), and we analyzed its association with adjuvant therapy. 2735 patients with ITC and 5602 patients with IMC were identified. ITC presented in younger patients (57 vs. 67years), had smaller tumors (size <1cm, 63.1% vs. 25.4%), earlier stage, and less node-positive disease (5% vs. 8.6%), compared with IMC. Older age, government insurance, lower income, treatment in a community cancer program, large tumor size, positive nodal status, and without endocrine therapy were associated with worse OS with either subtype on multivariate analysis. No OS benefit was found for node-positive ITC that received adjuvant chemotherapy compared with those who did not. (5-year OS of 96.0% vs. 91.3%, p=0.17).OS was improved for IMC that received adjuvant chemotherapy (10-year OS: 82.5% vs. 60.1%, p=0.008) and endocrine therapy (10-year OS: 86.6% vs. 81.2%, p<0.001). We concluded that ITC has favorable clinicopathological characteristics and prognosis, even with node-positive disease. ITC and IMC may need to be evaluated independently when administering adjuvant treatment plans.

Mediator of DNA Damage Checkpoint 1 (MDC1) Is a Novel Estrogen Receptor Coregulator in Invasive Lobular Carcinoma of the Breast.

Invasive lobular carcinoma (ILC) is the most common special histologic subtype of breast cancer, and nearly all ILC tumors express estrogen receptor alpha (ER). However, clinical and laboratory data suggest ILC are strongly estrogen-driven but not equally antiestrogen-sensitive. We hypothesized ILC-specific ER coregulators mediate ER functions and antiestrogen resistance in ILC, and profiled ER-associated proteins by mass spectrometry. Three ER+ ILC cell lines (MDA MB 134VI, SUM44PE, and BCK4) were compared with ER+ invasive ductal carcinoma (IDC) line data, and we examined whether siRNA of identified proteins suppressed ER-driven proliferation in ILC cells. This identified mediator of DNA damage checkpoint 1 (MDC1), a tumor suppressor in DNA damage response (DDR), as a novel ER coregulator in ILC. We confirmed ER:MDC1 interaction was specific to ILC versus IDC cells, and found MDC1 knockdown suppressed ILC cell proliferation and tamoxifen resistance. Using RNA-sequencing, we found in ILC cells MDC1 knockdown broadly dysregulates the ER transcriptome, with ER:MDC1 target genes enriched for promoter hormone response elements. Importantly, our data are inconsistent with MDC1 tumor suppressor functions in DDR, but suggest a novel oncogenic role for MDC1 as an ER coregulator. Supporting this, in breast tumor tissue microarrays, MDC1 protein was frequently low or absent in IDC, but MDC1 loss was rare in ER+ ILC. ER:MDC1 interaction and MDC1 coregulator functions may underlie ER function in ILC and serve as targets to overcome antiestrogen resistance in ILC. IMPLICATIONS: MDC1 has novel ER coregulator activity in ILC, which may underlie ILC-specific ER functions, estrogen response, and antiestrogen resistance.

LBA3 Atezolizumab with carboplatin as immune induction in metastatic lobular breast cancer: First results of the GELATO-trial

Invasive lobular breast cancer (ILC) is a special histological breast cancer subtype for which endocrine treatment is effective, but options thereafter are limited. ILC appears to be a different disease entity than invasive breast cancer of no special type. Translational data suggested that a subgroup of ILC has high expression of immune-related genes. Preclinical data revealed that this subtype may be responsive to combined platinum and immune checkpoint blockade. Here we present the first results of a single-arm phase II trial of atezolizumab (atezo) after immune induction with carboplatin in metastatic (m)ILC. In the single-arm, multicenter GELATO-trial (NCT03147040), patients with mILC were treated with 12 cycles of carboplatin q1w (AUC 1.5 mg/mL·min) and atezo (1200 mg) q3w starting from the third cycle of carboplatin and continuing until progression or intolerability. Patients had received a maximum of 2 lines of palliative chemotherapy and were endocrine refractory in case of ER-positive tumors. The primary endpoint was progression-free survival at 24 weeks according to RECIST1.1. Following a Simon’s two-stage design, 22 patients, receiving at least 1 cycle of atezo, needed to be included in the first stage, of whom at least 3 patients had to be free of progression after 24 weeks to warrant further investigation in the second stage. Among 23 included evaluable patients, 4 patients were free of progression at 24 weeks, meeting the primary endpoint of the first stage of the trial. 1 patient has an ongoing response and 2 patients have started treatment but have not yet reached an endpoint. 4 out of these 21 patients had a partial response resulting in an objective response rate of 19% and 2 patients had stable disease, resulting in a clinical benefit rate of 29%. 4 of the patients with clinical benefit had triple negative (TN)-ILC, whereas in total 5 out of 23 patients had TN-ILC. Stromal tumor-infiltrating lymphocytes were not associated with clinical benefit. PD-L1 and CD8 will be presented at the meeting. This is the first clinical immunotherapy trial executed exclusively in mILC. We show a clear efficacy signal of PDL1-blockade in combination with carboplatin in mILC, mainly in patients with TN-ILC.

Clinical and Demographic Factors, Treatment Patterns, and Overall Survival Associated With Rare Triple-Negative Breast Carcinomas in the US

Triple-negative breast cancers are known collectively to demonstrate a more aggressive clinical course and earlier recurrence than cancers of other histological subtypes. However, the literature on rare triple-negative breast cancers and the association of histological type with survival and risk of metastasis is sparse. To present the clinical and demographic characteristics, treatment patterns, and overall survival (OS) for histologically rare (<10% of breast cancers) triple-negative breast cancer types: medullary carcinoma, adenoid cystic carcinoma, and metaplastic breast carcinoma. This cohort study was performed in the US using data reported by the National Cancer Database between 2010 and 2016. Confirmed cases of medullary carcinoma, adenoid cystic carcinoma, and metaplastic breast cancer were analyzed. Univariable analyses and multivariable Cox regression models were performed. Data analysis was performed from April to May 2020. The primary outcome was 5-year OS. Secondary outcomes included site of metastasis, effect of immunohistochemistry, management, and 2-year mortality. A total of 8479 patients with breast cancer (mean [SD] age; 62.6 [14.3] years; 8435 women [99.48%]) were analyzed. Metaplastic carcinoma was the most commonly diagnosed histological type in this cohort, with 6867 patients (81%), followed by 1357 (16%) with adenoid cystic carcinoma and only 255 (3%) with medullary carcinoma. Medullary carcinoma presented earlier in life, at a median (interquartile range) age of 53 (45-62) years, compared with 62 (53-72) years for patients with adenoid cystic carcinoma and 63 (52-74) years for patients with metaplastic carcinoma. The proportion of tumors with triple-negative immunohistochemistry varied by histological type for medullary carcinoma (57 patients [22.4%]), adenoid cystic carcinoma (653 patients [48.1%]), and metaplastic carcinoma (3637 patients [53.0%]). Patients with adenoid cystic carcinoma were less likely to receive radiotherapy (711 patients [52.4%]) and chemotherapy (175 patients [12.9%]) compared with patients with medullary carcinoma (radiotherapy, 156 patients [61.2%]; chemotherapy, 190 patients [74.5%]) and metaplastic carcinoma (radiotherapy, 3416 patients [49.7%]; chemotherapy, 4709 patients [68.6%]). The 5-year OS rate was superior for patients with medullary (91.7%) and adenoid cystic carcinoma (88.4%) compared with patients with metaplastic carcinoma (63.1%). The 5-year mortality rate for adenoid cystic carcinoma was 8.33% vs 36.91% for metaplastic carcinoma. Nationally, over the course of 7 years, medullary carcinoma was most common and metaplastic carcinoma had the worst 5-year OS among the rare histological breast cancer subtypes analyzed. Factors associated with a poor prognosis for metaplastic carcinoma included advanced stage, lung metastasis, older age, and not receiving chemotherapy or radiation therapy. Future research focusing on rare subtypes of breast cancer is desirable and could inform the optimal management of these relatively understudied carcinomas.

Competing-Risk Nomograms for Predicting the Prognosis of Patients With Infiltrating Lobular Carcinoma of the Breast

BackgroundInfiltrating lobular carcinoma (ILC) is the second most common histologic subtype of breast cancer. We assessed the rates of cause-specific death in ILC patients with the aim of establishing competing-risk nomograms for predicting their prognosis. Patients and MethodsData on ILC patients were extracted from the Surveillance, Epidemiology, and End Results (SEER) database. The cumulative incidence function was used to calculate the cumulative incidence rates of cause-specific death, and Gray's test was applied to test the differences in cumulative incidence rates among groups. We then identified independent prognostic factors by applying the Fine–Gray proportional subdistribution hazard analysis method and established nomograms based on the results. Calibration curves and the concordance index were employed to validate the nomograms. ResultsThe study enrolled 11,361 patients. The 3-, 5-, and 10-year overall cumulative incidence rates for those who died of ILC were 3.1%, 6.2%, and 12.2%, respectively, whereas the rates for those who died from other causes were 3.2%, 5.8%, and 14.1%. Age, marriage, grade, size, regional node positivity, American Joint Committee on Cancer M stage, progesterone receptor, and surgery were independent prognostic factors for dying of ILC, whereas the independent prognostic factors for dying of other causes were age, race, marriage, size, radiation, and chemotherapy. The nomograms were well calibrated and had good discrimination ability. ConclusionWe applied competing-risk analysis to ILC patients based on the SEER database and established nomograms that perform well in predicting the cause-specific death rates at 3, 5, and 10 years after the diagnosis.

Mucinous Breast Carcinoma: Clinicopathological Comparison With Invasive Ductal Carcinoma.

IntroductionInvasive ductal carcinoma (IDC) is the most common histological subtype of breast cancer. Conversely, many special types of breast carcinoma were described with varying prognosis and hormone receptor status. Mucinous carcinoma (MC) is a rare special subtype of breast cancer, and only a few studies have evaluated the clinicopathological and hormone receptor profile of this type of breast cancer. Therefore, in this study, we compared the clinicopathological characteristics of MC with IDC in our population.MethodsA retrospective observational study was conducted in the Department of Histopathology, Liaquat National Hospital and Medical College, from January 2013 till December 2020, for eight years. During this period, 38 cases of MC were diagnosed and 1268 cases of IDC were identified. All specimens were grossed according to standard protocols and representative sections were submitted from tumors, resection margins, and lymph nodes. Slides were examined by histopathologists to determine tumor type and grade. Immunohistochemical (IHC) stains were applied to evaluate estrogen receptor (ER), progesterone receptor (PR), Ki67, and human epidermal growth factor receptor 2 (HER2/neu) statuses.ResultsThe mean age of the patients with MC was 56.47±13.90 years, and most of the patients were above 50 years of age. The mean tumor size was 34.89±19.70 mm. Most tumors were grade 1 (68.4%) with a low mean Ki67 index (15.21±14.06%). Axillary metastasis was present in 31.6% of cases and all of them were nodal (N)-stage N1. ER, PR, and HER2/neu positivity were noted in 94.7%, 78.9, and 10.5% cases, respectively. Compared with IDC, a significant association of MC was noted with age, Ki67 index, tumor (T)-stage, N-stage, and tumor grade. MC cases had a higher mean age than IDC cases. Comparative analysis revealed that MC had a lower frequency of axillary metastasis, a lower mean Ki67 index, and a lower tumor grade than IDC. About biomarker status, MC was noted to have a higher frequency of ER and PR expression, and a lower frequency of HER2/neu expression than IDC.ConclusionMC is a rare subtype of breast cancer. However, it is important to recognize this subtype of breast cancer as it is associated with a prognostically better pathological profile, such as lower tumor grade and Ki67 index, lower frequency of axillary metastasis, higher expression of ER and PR, and lower expression of HER2/neu.

Intraductal xenografts show lobular carcinoma cells rely on their own extracellular matrix and LOXL1

Invasive lobular carcinoma (ILC) is the most frequent special histological subtype of breast cancer, typically characterized by loss of E‐cadherin. It has clinical features distinct from other estrogen receptor‐positive (ER+) breast cancers but the molecular mechanisms underlying its characteristic biology are poorly understood because we lack experimental models to study them. Here, we recapitulate the human disease, including its metastatic pattern, by grafting ILC‐derived breast cancer cell lines, SUM‐44 PE and MDA‐MB‐134‐VI cells, into the mouse milk ducts. Using patient‐derived intraductal xenografts from lobular and non‐lobular ER+ HER2− tumors to compare global gene expression, we identify extracellular matrix modulation as a lobular carcinoma cell‐intrinsic trait. Analysis of TCGA patient datasets shows matrisome signature is enriched in lobular carcinomas with overexpression of elastin, collagens, and the collagen modifying enzyme LOXL1. Treatment with the pan LOX inhibitor BAPN and silencing of LOXL1 expression decrease tumor growth, invasion, and metastasis by disrupting ECM structure resulting in decreased ER signaling. We conclude that LOXL1 inhibition is a promising therapeutic strategy for ILC.

Abstract PS19-06: Role of the calcium-sensing receptor (CaSR) in invasive lobular breast carcinoma metastasis to the ovary

Abstract Invasive lobular carcinoma (ILC) is the second most common histological subtype of breast cancer, after the more common invasive ductal carcinoma (IDC). ILC accounts for 10 to 15% of all invasive breast carcinomas, affecting approx. 26,000-40,000 women in 2020 in the US alone. Despite 95% of ILC being Luminal A conferring patients a favorable prognosis, patients with ILC have poorer long-term outcomes when compared to patients with Luminal A IDC. ILC spread to common sites of ER+ breast cancer metastasis such as the bones, but are also three times more likely to spread to the ovaries, peritoneum, and gastrointestinal tract compared to IDC, and these unique aspects of metastases remain poorly understood. To better understand metastasis to the ovary we performed DNA and RNA sequencing of 11 pairs of primary breast tumor and ovarian metastasis as well as 13 orphan breast cancer ovarian metastases. Our cohort was enriched for lobular histology, with 13 samples originating from ILC, 6 from IDC and 6 from mixed ILC/IDC. We found mutations in CDH1 (43%), PIK3CA (40%), and FOXA1 (29%) highlighting the enrichment in ILC cases present in our cohort. Gene expression analysis lead to identification of 874 differentially expressed between primary tumors and ovarian metastases. We identified the calcium-sensing receptor CaSR as one of the top upregulated in ovarian metastases compared to primary tumor in 10 out of the 11 paired samples. Other genes highly expressed in ovarian metastases included TAC3, GLRA2, ALLC, MUC19, CHRNA2, PIP, CST4, and TEX15. Pathways analyses showed an enrichment of signaling through glutamate receptor and glycine receptor families. To assess the contribution of CaSR to breast cancer cell proliferation and metastatic properties, and due to the absence of breast cancer cell lines expressing CaSR, we generated CaSR overexpression models using lentiviral infection in MDA-MB-134, MDA-MB-330, BCK4 and SUM44PE ILC cell lines. While overexpression of CaSR alone did not confer a cell growth advantage or migratory ability to the cell lines, stimulation with calcium or a calcium mimetic resulted in enhanced migration in transwell assays in 3 of the 4 cell lines. Scratch assays further confirmed the stimulation of cell migration in cells with CaSR overexpression in the presence of calcium. Cell migration in CaSR overexpression models could be stimulated with the calcimimetic R568, and inhibited by the calcilytics NPS2143, and F-actin staining confirmed the need to activate the receptor to enhance migratory properties. Our studies further revealed that the induced migratory properties of CaSR overexpressing cells required estradiol and ER signaling, and that migration could be blocked with ER inhibitors such as ICI 182,780 and tamoxifen. Western blotting data revealed that the enhanced cell migratory properties of CaSR overexpressing cells was via activation of the MEK/ERK pathway and migration could be inhibited using specific small molecule pathway inhibitors.Altogether, our study provides insight on the potential mechanism by which upregulation of the CaSR supports breast cancer ovarian metastasis. We hope that these studies will not only deepen our understanding of ILC ovarian metastasis but will eventually lead to the development of more effective therapies and improve the outcome of patients with this understudied type of breast cancer. Citation Format: Ye Qin, Laura Savariau, Ahmed Mohammed Basudan, Osama Shah, Zheqi Li, Tiantong Liu, Nilgun Tasdemir, Lan Coffman, Esther Elishaev, Jennifer M Atkinson, Peter Lucas, Adrian V Lee, Steffi Oesterreich. Role of the calcium-sensing receptor (CaSR) in invasive lobular breast carcinoma metastasis to the ovary [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 PS19-06.

Abstract PS11-02: Comprehensive comparative analysis of invasive ductal and lobular breast cancer cases in great lakes breast cancer consortium

Abstract Background: Invasive lobular breast cancer (ILC) is the second most common histologic subtype of breast cancer following invasive ductal cancer (IDC). ILC accounts for ~10-15% of all breast cancers (~26-40,000 cases annually in the US) and ranks as the 6th most common cancer in women in the US. While there is increasing recognition that ILC has distinct clinical, histologic, molecular, and biological characteristics compared to IDC, it remains understudied. There are very few large cohort analyses comparing clinic-pathological features of ILC, and therefore we performed a large multi-institutional retrospective cohort study. Methods: Investigators from UPMC Hillman Cancer Center, James Cancer Hospital/OSU, and Cleveland Clinic Taussig Cancer Institute/CWRU formed the Great Lakes Breast Cancer consortium, and worked with their respective cancer registries to collect comprehensive data on patients with IDC and ILC seen at their institutions between 1990 and 2017. Descriptive statistics were performed to compare clinic-pathological features, treatments, metastases sites, and co-morbidities. Survival rates were analyzed using the Kaplan-Meier (KM) method and compared using the Cox proportional hazards model. A total of N=38,175 records (N=15,792 for UPMC, N=13,040 for CCF, and N=9,343 for OSU) were included in the study. Results Among the N=38,175 records, we identified N=30,100 unique IDC (not otherwise specific, NOS) (89.3%) and N=3,618 unique ILC cases (10.7%). There were no significant differences between IDC and ILC with respect to laterality of the cancer (IDC: Left 51%, Right 49%; 0.2% Other vs ILC: Left 51%, Right 48%, Other 0.5%) and body mass index (IDC: 28.4 vs ILC: 28.2). In contrast, we observed significant difference with respect to age - patients with ILC were significantly older (61.2 vs 57.5 years; p&amp;lt;0.0001), and there were significant differences in race (7.6% vs 9.2% African American patients in ILC vs IDC, respectively; p=0.004). Among ILC cases, there were fewer grade III tumors (11.4% vs 40.3% in IDC; p&amp;lt;0.0001). ILCs were more frequently stage III (16.6% vs 8.0% in IDC) and stage IV (3.7% vs 2.4% in IDC) (p&amp;lt;0.0001), and ILC were significantly larger than IDC (13.7% T3 vs 2.8% in IDC, p&amp;lt;0.0001). There was also significantly more lymph node involvement in patients with ILC (N2: 5.3% vs 4.0%; N3: 4.6% vs 1.5%) (p&amp;lt;0.0001). The ILC cohort had significantly fewer HER2+ cases (5.5% vs 18.1% in IDC) (p&amp;lt;0.0001), and the proportion of patients with a high recurrence score as determined by 21 gene recurrence score was significantly lower in ILC compared to IDC (1.7% vs 10.4% in IDC; p&amp;lt;0.0001). As expected, there was a significant enrichment of ER+ tumors in ILC (96.1% compared to IDC (76.6%) (p&amp;lt;0.0001). Age, stage, grade, ER, Her2, and lymph node involvement remained significantly associated with histology in a logistic regression analysis. KM analysis showed significantly shortened disease-free (p=0.041) and overall survival (p&amp;lt;0.0001) for patients with ER+ ILC (N=2,565) compared to ER+ IDC N=17,278). The estimated 5yr and 10yr DFS rates for patients with IDC are 0.94 and 0.89, and for ILC 0.94 and 0.86, confirming prior data of late recurrences in patients with ILC. Conclusions: In the largest cohort of patients with ILC made possible by multi-center collaborations we show that lobular histology carries distinct prognostic implications and that outcomes are significantly worse. This highlights the need for more ILC research and clinical trials for patients with ILC. Citation Format: Steffi Oesterreich, Azadeh Nasrazadani, Jian Zou, Tiffany Onger, Matthew Wright, George Tseng, Bhuvana Ramaswamy, Adrian V Lee, Nicole Williams, Megan Kruse. Comprehensive comparative analysis of invasive ductal and lobular breast cancer cases in great lakes breast cancer consortium [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 PS11-02.

USP1-WDR48 deubiquitinase complex enhances TGF-β induced epithelial–mesenchymal transition of TNBC cells via stabilizing TAK1

ABSTRACT Triple-negative breast cancer (TNBC) is the most aggressive histological subtype of breast cancer and is characterized by poor outcomes and a lack of specific-targeted therapies. Transforming growth factor-β (TGF-β) acts as the key cytokine in the epithelial–mesenchymal transition (EMT) and the metastasis of TNBC. However, the regulatory mechanisms of the TGF-β signaling pathway remain largely unknown. In this study, we identified that the USP1/WDR48 complex could effectively enhance TGF-β-mediated EMT and migration of TNBC cells. Furthermore, lower phosphorylation of Smad2/3, Erk, Jnk, and p38 was noted on the suppression of the expression of endogenous USP1 or WDR48. Moreover, the USP1-WDR48 complex was found to downregulate the polyubiquitination of TAK1 and mediate its in vitro stability. Therefore, our findings have shed a light on the novel role of the USP1/WDR48 complex in promoting TGF-β-induced EMT and migration in TNBC via in vitro stabilization of TAK1.

Single-Cell Transcriptomic Heterogeneity in Invasive Ductal and Lobular Breast Cancer Cells.

Invasive lobular breast carcinoma (ILC), one of the major breast cancer histologic subtypes, exhibits unique features compared with the well-studied ductal cancer subtype (IDC). The pathognomonic feature of ILC is loss of E-cadherin, mainly caused by inactivating mutations, but the contribution of this genetic alteration to ILC-specific molecular characteristics remains largely understudied. To profile these features transcriptionally, we conducted single-cell RNA sequencing on a panel of IDC and ILC cell lines, and an IDC cell line (T47D) with CRISPR-Cas9-mediated E-cadherin knockout (KO). Inspection of intracell line heterogeneity illustrated genetically and transcriptionally distinct subpopulations in multiple cell lines and highlighted rare populations of MCF7 cells highly expressing an apoptosis-related signature, positively correlated with a preadaptation signature to estrogen deprivation. Investigation of E-cadherin KO-induced alterations showed transcriptomic membranous systems remodeling, elevated resemblance to ILCs in regulon activation, and increased sensitivity to IFNγ-mediated growth inhibition via activation of IRF1. This study reveals single-cell transcriptional heterogeneity in breast cancer cell lines and provides a resource to identify drivers of cancer progression and drug resistance. SIGNIFICANCE: This study represents a key step towards understanding heterogeneity in cancer cell lines and the role of E-cadherin depletion in contributing to the molecular features of invasive lobular breast carcinoma.

Breast cancer incidence and mortality in women in China: temporal trends and projections to 2030.

Objective:Breast cancer was the most common cancer and the fifth cause of cancer deaths among women in China in 2015. The evaluation of the long-term incidence and mortality trends and the prediction of the future burden of breast cancer could provide valuable information for developing prevention and control strategies.Methods:The burden of breast cancer in China in 2015 was estimated by using qualified data from 368 cancer registries from the National Central Cancer Registry. Incident cases and deaths in 22 cancer registries were used to assess the time trends from 2000 to 2015. A Bayesian age-period-cohort model was used to project the burden of breast cancer to 2030.Results:Approximately 303,600 new cases of breast cancer (205,100 from urban areas and 98,500 from rural areas) and 70,400 breast cancer deaths (45,100 from urban areas and 24,500 from rural areas) occurred in China in 2015. Urban regions of China had the highest incidence and mortality rates. The most common histological subtype of breast cancer was invasive ductal carcinoma, followed by invasive lobular carcinoma. The age-standardized incidence and mortality rates increased by 3.3% and 1.0% per year during 2000–2015, and were projected to increase by more than 11% until 2030. Changes in risk and demographic factors between 2015 and 2030 in cases are predicted to increase by approximately 13.3% and 22.9%, whereas deaths are predicted to increase by 13.1% and 40.9%, respectively.Conclusions:The incidence and mortality of breast cancer continue to increase in China. There are no signs that this trend will stop by 2030, particularly in rural areas. Effective breast cancer prevention strategies are therefore urgently needed in China.

Breast cancer in togolese women: immunohistochemistry subtypes

BackgroundMolecular classification of breast cancer is an important factor for prognostic and clinical outcomes. There are no data regarding molecular breast cancer subtypes among Togolese women. The objective of this study was to evaluate the expression of ER, PR, HER2, and molecular subtypes of breast cancer receptors in Togolese patients and to establish the correlation between clinical and histological data and molecular types.MethodsClinicopathologic data of patients were collected from clinical records. Immunohistochemistry biomarkers (ER, PR, and HER2) were assessed in patients who have been diagnosed with invasive breast cancer from March 2016 to March 2020 in the department of oncology. The analysis of variance and the Chi-square Test was used to analyze the data.ResultsA total of 117 cases were collected. The mean age of patients was 52.05 ± 12.38 with an age range of 30 to 85 years. Half of the patients were over 50 years old and the majority (70.9%) was postmenopausal. More than half of patients (52.1%) presented with T3-T4tumors.The most common histologic subtype of breast cancer was invasive ductal carcinoma of no special type (95.7%). Tumors grade 2 were predominant (51.3%) followed by grade 3 (42.7%). Advanced carcinomas were found in 69 patients (59%). The percentage of ER+, PR+, and HER2 positive tumors was 54.7%, 41%, and 15.4% respectively. The predominant molecular subtype was Triple negative (37.6%), followed by Luminal A (30.8.7%), Luminal B subtype (23.9%), and HER2 enriched (7.7%). There was a significant association between stage and breast cancer subtypes (p 0.025), histologic grade, and subtype (p < 0.0001) but no correlation was found with age, menopausal status, and tumor size.ConclusionBreast carcinoma in our patients are high grade tumors and are diagnosed at an advanced stage. Triple negative and Luminal A are the two predominant breast cancer subtypes in Togolese women. Consequently, Receptor testing availability should be a priority to offer the best breast cancer treatment.