A Novel Long Non-Coding RNA Regulates The Integrin, ITGA2 in Breast Cancer

Purpose ITGA2 encodes the integrin, a2 which mediates metastatic progression, and is a predictor of poor prognosis and chemoresistance in breast cancer. Decreased ITGA2 promoter methylation is implicated as a driver of increased gene expression in aggressive prostate and pancreatic tumours, however the contribution of altered methylation to ITGA2 expression changes in breast tumours has not been examined. Methods ITGA2 gene methylation and gene expression was examined in publicly available breast cancer datasets, and ITGA2 promoter methylation was mapped by targeted bisulphite sequencing analysis in breast tumour cell lines. The expression of a putative regulatory long noncoding RNA (lncRNA) was examined by qPCR and its’ functionality was investigated using gene knockdown (antisense oligonucleotides) and over expression analysis in breast cancer cell lines. Results In breast tumours and breast cancer cell lines the ITGA2 promoter is largely unmethylated, with gene expression variable in tumour subtypes, irrespective of promoter methylation. A novel lncRNA (AC025180.1;ENSG00000249899), named herein I2ALR, was identified at the ITGA2 gene locus, and was variably expressed in breast tumours and breast cancer cell subtypes. I2LAR knockdown resulted in upregulation of ITGA2 gene expression, whilst over-expression of I2ALR resulted in downregulation of ITGA2 mRNA. Further, examination of two downstream targets of ITGA2 associated with breast tumor stemness and metastasis (CCND1 and ACLY), revealed concomitant gene expression changes in response to I2ALR modulation. Conclusion I2ALR represents a novel regulatory molecule targeting ITGA2 expression in breast tumours; a finding of significant and topical interest to the development of therapeutics targeting this integrin.

Metabolic Flexibility Is a Determinant of Breast Cancer Heterogeneity and Progression

Breast cancer progression is characterized by changes in cellular metabolism that contribute to enhanced tumour growth and adaptation to microenvironmental stresses. Metabolic changes within breast tumours are still poorly understood and are not as yet exploited for therapeutic intervention, in part due to a high level of metabolic heterogeneity within tumours. The metabolic profiles of breast cancer cells are flexible, providing dynamic switches in metabolic states to accommodate nutrient and energy demands and further aggravating the challenges of targeting metabolic dependencies in cancer. In this review, we discuss the intrinsic and extrinsic factors that contribute to metabolic heterogeneity of breast tumours. Next, we examine how metabolic flexibility, which contributes to the metabolic heterogeneity of breast tumours, can alter epigenetic landscapes and increase a variety of pro-tumorigenic functions. Finally, we highlight the difficulties in pharmacologically targeting the metabolic adaptations of breast tumours and provide an overview of possible strategies to sensitize heterogeneous breast tumours to the targeting of metabolic vulnerabilities.

Small Molecules Targeting Programmed Cell Death in Breast Cancer Cells

Targeted chemotherapy has become the forefront for cancer treatment in recent years. The selective and specific features allow more effective treatment with reduced side effects. Most targeted therapies, which include small molecules, act on specific molecular targets that are altered in tumour cells, mainly in cancers such as breast, lung, colorectal, lymphoma and leukaemia. With the recent exponential progress in drug development, programmed cell death, which includes apoptosis and autophagy, has become a promising therapeutic target. The research in identifying effective small molecules that target compensatory mechanisms in tumour cells alleviates the emergence of drug resistance. Due to the heterogenous nature of breast cancer, various attempts were made to overcome chemoresistance. Amongst breast cancers, triple negative breast cancer (TNBC) is of particular interest due to its heterogeneous nature in response to chemotherapy. TNBC represents approximately 15% of all breast tumours, however, and still has a poor prognosis. Unlike other breast tumours, signature targets lack for TNBCs, causing high morbidity and mortality. This review highlights several small molecules with promising preclinical data that target autophagy and apoptosis to induce cell death in TNBC cells.

534 Use of Ultrasound by Breast Surgeons Reduces the Need for Wire-Guided Localisation Of Impalpable Breast Tumours By Radiologists

Aim Ultrasound is increasingly being used by non-radiologists in clinical practice. Currently wire-guided localisation (WGL) of impalpable breast tumours requires the expertise of radiologists but can be uncomfortable and demands significant radiology resource. Furthermore, for logistical reasons at our institution during the COVID pandemic, wires were inserted the day before surgery, resulting in disruption to patients. At our institution, two of eight breast surgeons use ultrasound intraoperatively for localisation of breast lesions, thus obviating the need for a radiologist to localise the lesion for the surgeon. We hypothesise that ultrasound-localisation by surgeons is an effective way to improve patient experience. Method We undertook a retrospective review of all patients undergoing wire-guided localisation of impalpable breast tumours between 01/05/20-01/08/20. We retrospectively collected the following data: modality of image-guided insertion (ultrasound versus x-ray), operating surgeon and size of tumour. Results 48 tumours were excised using WGL. 45 of these relied on ultrasound guidance for insertion. The median lesion size was 17mm, with 30 (62.5%) of lumps being ³10mm in size. Conclusions Most impalpable lumps were visualised using ultrasound. The majority of these lumps were >10mm. Surgeons trained in ultrasound did not need localisation by radiologists. If breast surgeons were unanimously trained to use ultrasound for intra-operative localisation, a significant proportion of wires could be avoided, saving cost, radiology time, patient time and improving the patient experience. We argue that ultrasound should be a core part of breast trainees’ curriculum.

1331 An Observational Study Investigating the Role of Therapeutic Mammoplasty in Breast Tumours Greater Than 40mm

Aim For large breast tumours, therapeutic mammoplasty (TM) provides a breast-conserving approach to the conventional mastectomy. The prevalence and outcomes following TM in larger breast tumours is relatively unknown. This study aims to analyse the short-term outcomes and local recurrence rate following TM for breast tumours of varying sizes. Method Single-centre retrospective analysis of data from all patients undergoing a TM between June 2016-October 2019. Variables reviewed included age, imaging, tumour size, pre-operative histology, adjuvant chemotherapy and radiotherapy, post-operative pathology, post-operative complications, and recurrence rates. Results 192 patients undergoing a TM procedure were included, 126 (66%) patients had tumours <40mm and 66 (34%) patients had tumours >40mm. The average age of participants was 61 years with a mean follow-up of 31 months. The mean size of tumours >40mm was 56.8mm, of these patients 15% had positive margins, 2 (3%) patients required a further mastectomy and 8 (12%) underwent margin re-excisions. In lesions >40mm there were six episodes (9%) of T-junction delayed wound healing with two requiring surgical management, two episodes (3%) of wound infections requiring antibiotics and four episodes (6%) of seroma with one requiring surgery for an infected seroma. Two patients were found to have metastatic disease and no patients were found to have local recurrence at the most recent follow-up. Conclusions Our study demonstrated TM offers a surgical option with suitable cosmetic and oncological outcomes for women with early breast tumours above 40mm. These results warrant further study into the long-term outcomes for patients undergoing TM with tumours >40mm.

Determination of risk factors using Nonlinear Principal Component Analysis in patients with breast tumour

Objective: Breast cancer, which is the most common among women in the world and constitutes approximately 30% of all cancers, takes places near the top among the diseases that threaten women's health. The purpose of this study is to determine the risk factors in patients with breast tumours using nonlinear principal component analysis. Materials and Methods: During the application process, a data set of 569 (357 benign, 212 malign) patients with breast tumours was used. To find independent features, the data set was reduced to two dimensions via nonlinear principal component analysis. The results were evaluated by comparing the success of the method with the ROC curve. Results: The cut-off values for the radius, perimeter, area, smoothness and texture of the tumour were 14.19, 656.10, 0.09, 2.87 and 0.11, respectively. The sensitivity of the current values according to the results of ROC analysis was determined as 84% for radius, 80% for perimeter, 86% for the area and 94% for texture. It is seen that the method has an overall success of over 80% in detecting malignant tumours. Conclusions: It is hoped that this method, which is used to reveal risk factors and identify distinctive features in breast tumours, will reduce medical costs and provide a second opinion to physicians. In terms of decision making, it is predicted that the method can recognize malignant tumours and reduce the need for unnecessary biopsy for benign tumours.

Increased gene expression variability in BRCA1-associated and basal-like breast tumours

Purpose Inherited variants in the cancer susceptibility genes, BRCA1 and BRCA2 account for up to 5% of breast cancers. Multiple gene expression studies have analysed gene expression patterns that maybe associated with BRCA12 pathogenic variant status; however, results from these studies lack consensus. These studies have focused on the differences in population means to identified genes associated with BRCA1/2-carriers with little consideration for gene expression variability, which is also under genetic control and is a feature of cellular function. Methods We measured differential gene expression variability in three of the largest familial breast cancer datasets and a 2116 breast cancer meta-cohort. Additionally, we used RNA in situ hybridisation to confirm expression variability of EN1 in an independent cohort of more than 500 breast tumours. Results BRCA1-associated breast tumours exhibited a 22.8% (95% CI 22.3–23.2) increase in transcriptome-wide gene expression variability compared to BRCAx tumours. Additionally, 40 genes were associated with BRCA1-related breast cancers that had ChIP-seq data suggestive of enriched EZH2 binding. Of these, two genes (EN1 and IGF2BP3) were significantly variable in both BRCA1-associated and basal-like breast tumours. RNA in situ analysis of EN1 supported a significant (p = 6.3 × 10−04) increase in expression variability in BRCA1-associated breast tumours. Conclusion Our novel results describe a state of increased gene expression variability in BRCA1-related and basal-like breast tumours. Furthermore, genes with increased variability may be driven by changes in DNA occupancy of epigenetic effectors. The variation in gene expression is replicable and led to the identification of novel associations between genes and disease phenotypes.