Development of a clinically relevant subclassification of luminal breast cancer related to response to endocrine therapy

Endocrine therapy is widely used in clinical practice as adjuvant treatment for luminal breast cancer. Although clinical outcome of patients with this subtype have markedly improved with endocrine therapy, around 30-50% of patients relapse despite treatment. Therefore, as part of the growing concept of personalised medicine, research priorities are required to more accurately identify predictive markers of endocrine therapy response to aid clinician decision-making. This thesis aimed to identify markers that are able to classify luminal breast tumours into distinct groups with different outcomes in the context of response to endocrine therapy. Large, well-characterised cohorts of primary luminal breast cancer patients with long-term follow-up were assessed for the clinical impact of selected markers at the transcriptomic and proteomic levels. Prognostic significance of these markers with clinical outcome and benefit of endocrine therapy as well as their association with clinicopathological variables and other related-genes were analysed. Bioinformatic analysis was performed to identify differentially expressed genes (DEGs) in terms of response to adjuvant endocrine therapy. In vitro experiments were conducted to investigate the effect of knockdown of key markers in the proliferation of cancer cells and to the sensitivity to endocrine treatment. This thesis has identified key markers with different function including amino acid transporters (SLC1A5, SLC3A2/SLC7A5), cell cycle regulators (KIF18A) and markers of cell motility (PPFIA1 and DBN1) that are associated with worse outcome in luminal tumours. Additionally, results indicate that assessment of their expression prior to adjuvant treatment could subclassify luminal subtype tumours into distinct groups with different outcome in the context of response to endocrine therapy. This could have a great clinical impact in helping guide clinician decision-making. Additional or alternative targeted therapies could then be given to those who have been predicted to have resistance to endocrine therapy, this would be a significant shift toward a more truly individualised medicine. This thesis provides a set of useful targets for future investigation, which could pave the way for novel targeted therapy to overcome endocrine therapy resistance

The Role Of Glutaminase In Cancer

Increased glutamine metabolism (glutaminolysis) is a hallmark of cancer and is recognised as a key metabolic change in cancer cells. As a heterogeneous disease with different morpholog- ical and molecular subtypes and response to therapy, breast cancer cells are known to rewire glutamine metabolism to support survival and proliferation. Glutaminase isoenzymes (GLS and GLS2) are key enzymes for glutamine metabolism. Interestingly, GLS and GLS2 display contrasting functions in tumourigenesis. In this review, we explore the role of glutaminase in cancer, primarily focussing on breast cancer, address the role played by oncogenes and tu- mour suppressor genes in regulating glutaminase, and discuss current therapeutic approaches in targeting glutaminase

The solute carrier SLC7A8 is a marker of favourable prognosis in ER-positive low proliferative invasive breast cancer

Purpose: Breast cancer (BC) is a heterogeneous disease consisting of various subtypes, withdifferent prognostic and therapeutic outcomes. The amino acid transporter, SLC7A8, is over expressed in estrogen receptor positive BC. However the consequences of this overexpression, it terms of disease prognosis, is still obscure. This study aimed to evaluate the biological and prognostic value of SLC7A8 in BC with emphasis on the intrinsic molecular subtypes.Methods: SLC7A8 was assessed at the genomic, using METABRIC data (n=1,980), and proteomic, using immunohistochemistry and TMA (n=1,562), levels in well-characterised primary BC cohorts. SLC7A8 expression was examined with clinicopathological parameters, molecular subtypes, and patient outcome.Results: SLC7A8 mRNA and SLC7A8 protein expression were strongly associated with good prognostic features, including small tumour size, low tumour grade and good Nottingham Prognostic Index (NPI) (all

PPFIA1 expression associates with poor response to endocrine treatment in luminal breast cancer

BackgroundPPFIA1 is an important regulator of cell migration and invasion, regulating focal adhesion signalling and disassembly. PPFIA1 is frequently amplified in breast cancer, and recent functional studies indicate that PPFIA1 is an important promoter of migration and invasion in breast cancer. This study aims to evaluate the utility of PPFIA1 expression in the luminal breast cancer as a prognostic marker to predict the response to endocrine therapy.MethodsLarge, well-characterised cohorts of primary luminal breast cancer patients with long-term follow-up was assessed for the clinical impact of PPFIA1 expression at the transcriptomic and proteomic levels. Prognostic significance of PPFIA1 and its relationship with clinical outcome and benefit of endocrine therapy were analysed. In addition, its association with other related-genes was analysed.ResultsThere was significant association between PPFIA1 expression and a member of the liprin family that involves in cell invasion (PPFIBPI), and the cell cycle regulator (CCND1), whereas a negative association was observed with the tumour suppressor gene (CD82). Patients with high PPFIA1 expression were associated with high risk of recurrence, distant metastasis and death from breast cancer (P< 0.05). Importantly, high PPFIA1 expression predicted relapse in a subset of patients who were subject to endocrine treatment alone, and was an independent prognostic marker of unfavourable outcome in these patients (P< 0.05).ConclusionsThese findings support the proposed role for PPFIA1 as a regulator of cell migration in breast cancer and provides definitive evidence for the clinical utility of PPFIA1 expression in patients with luminal breast cancer. Most importantly, our data suggests that PPFIA1 might be a potential predictive marker for poor benefit from endocrine therapy

CDC20 expression in oestrogen receptor positive breast cancer predicts poor prognosis and lack of response to endocrine therapy

PurposeEndocrine therapy is the standard treatment for oestrogen receptor positive (ER+) breast cancer. Despite its efficacy, around half of patients will develop resistance to this treatment and eventually relapse. Identification of effective and reliable biomarkers to predict the efficacy of endocrine therapy is of crucial importance in the management of ER+ breast cancer. Emerging evidence has revealed that the cell division regulator CDC20 exhibits an oncogenic function and plays important roles in tumourigenesis and progression of solid tumours. In this study, we investigated the prognostic and predictive role of CDC20 in early ER+ breast cancer patients.MethodsThe biological and clinical impact of CDC20 expression was assessed in large clinical annotated cohort of ER+ breast cancer with long-term follow-up at the mRNA level, using METABRIC and KM-Plotter datasets, and the protein level using immunohistochemistry on patients presenting at Nottingham. CDC20 expression was correlated with clinico-pathological parameters, molecular subtypes, clinical outcome and efficacy of endocrine therapy.ResultsHigh CDC20 mRNA expression was associated with poor clinico-pathological parameters including large tumour size and high tumour grade (P

Co-Expression Effect of SLC7A5/SLC3A2 to Predict Response to Endocrine Therapy in Oestrogen-Receptor-Positive Breast Cancer

The majority of breast cancers are oestrogen receptor positive (ER+) and are subject to endocrine therapy however, an unpredictable subgroup of patients will develop resistance to endocrine therapy. SLC7A5/SLC3A2 complex is a major route for the transport of large neutral essential amino acids through the plasma membrane. Alterations in the expression and function of those amino acid transporters lead to metabolic reprogramming, which contributing to the tumorigenesis and drug resistance. This study aims to assess the effects and roles of SLC7A5/SLC3A2 co-expression in predicting response to endocrine therapy in patients with ER+ breast cancer. The biological and clinical impact of SLC7A5/SLC3A2 co-expression was assessed in large annotated cohorts of ER+/HER2- breast cancer with long-term follow-up at the mRNA and protein levels. In vitro experiments were conducted to investigate the effect of SLC7A5/SLC3A2 knockdown in the proliferation of cancer cells and to the sensitivity to tamoxifen. We found that proliferation-related genes are highly expressed in subgroup of patients with high SLC7A5/SLC3A2, and knockdown of SLC7A5/SLC3A2 decreased proliferation of ER+ breast cancer cells. In patients treated with endocrine therapy, high SLC7A5/SLC3A2 co-expression was associated with poor patient outcome, and depletion of SLC7A5/SLC3A2 using siRNA increased the sensitivity of breast cancer cells to tamoxifen. On the basis of our findings, SLC7A5/SLC3A2 co-expression has the potential of identifying a subgroup of ER+/HER2- breast cancer patients who fail to benefit from endocrine therapy and could guide the choice of other alternative therapy

Kinesin family member-18A (KIF18A) is a predictive biomarker of poor benefit from endocrine therapy in early ER+ breast cancer

PURPOSE: Identification of effective and reliable biomarkers that could be used to predict the efficacy of endocrine therapy is of crucial importance to the management of oestrogen receptor positive (ER+) breast cancer (BC). KIF18A, a key regulator of cell cycle, is overexpressed in many human cancers, including BC. In this study, we investigated the role of KIF18A as a biomarker to predict the benefit from endocrine treatment in early ER + BC patients.METHODS: KIF18A expression was assessed at the genomic level using the METABRIC dataset to explore its prognostic and predictive value in ER + BC patients (n = 1506). Predictive significance of KIF18A mRNA was validated using KM-Plot datasets (n = 2061). KIF18A protein expression was assessed using immunohistochemistry in a large annotated series of early-stage ER + BC (n = 1592) with long-term follow-up.RESULTS: High mRNA and protein expression of KIF18A were associated with short recurrence-free survival (RFS), distant-metastasis free survival (DMFS) and BC specific survival (all P  less than 0.05) in ER + BC in patients who received no adjuvant treatment or adjuvant endocrine therapy. In multivariate analysis, high KIF18A expression was an independent prognostic biomarker for poor RFS (P = 0.027) and DMFS (P = 0.028) in patients treated with adjuvant endocrine therapy.Conclusion: KIF18A appears to be a candidate biomarker of a subgroup of ER + BC characterised by poor clinical outcome. High KIF18A expression has prognostic significance to predict poor benefit from endocrine treatment for patients with ER + BC. Therefore, measurement of KIF18A on ER + BC patients prior to treatment could guide clinician decision on benefit from endocrine therapy

The amino acid transporter SLC7A11 expression in breast cancer

Breast cancer (BC) is a complex disease with diverse molecular profiles and clinical outcomes, making it challenging to develop effective treatments. Metabolic reprogramming is a hallmark of cancer and SLC7A11, an amino acid transporter, plays a crucial role in this process. This study investigated the role of SLC7A11 in BC using genomic, transcriptomic, and protein analyses.SLC7A11 gene copy number and mRNA expression were evaluated using the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) cohort (n=1,980) and Breast Cancer Gene Expression Miner (n=4,712). SLC7A11 protein was assessed using immunohistochemistry in a large BC cohort (n=1,981). Additionally, The Cancer Genome Atlas (TCGA) dataset was used to explore SLC7A11 DNA methylation patterns using MethSurv (n=782) and association of SLC7A11 mRNA expression with immune infiltrates using TIMER (n=1,100). High SLC7A11 mRNA and SLC7A11 protein expression were significantly associated with high tumor grade (p≤0.02). Interestingly, SLC7A11 copy number gain was observed in HER2+ tumors (p=0.01) whilst SLC7A11 mRNA expression was higher in basal-like/triple-negative (TN) and luminal B tumors (p≤0.02). In contrast, high SLC7A11 protein expression was predominantly observed in Estrogen Receptor (ER)-negative and TN BC. SLC7A11 correlated with other amino acid transporters and glutamine metabolism enzymes and with neutrophil and macrophage infiltration.These findings suggest that SLC7A11 plays a significant role in BC metabolism and may be a potential therapeutic target. Further studies are needed to elucidate its precise mechanisms and explore its therapeutic potential

The Biological and Clinical Significance of Glutaminase in Luminal Breast Cancer

Glutamine metabolism has a key role in the regulation of uncontrolled tumour growth. This study aimed to evaluate the expression and prognostic significance of glutaminase in luminal breast cancer (BC). The glutaminase isoforms (GLS/GLS2) were assessed at genomic/transcriptomic levels, using METABRIC (n=1 398) and GeneMiner datasets (n=4 712), and protein using immunohistochemistry in well characterised cohorts of Oestrogen Receptor-positive/HER2-negative BC patients: ductal carcinoma in situ (DCIS; n=206) and invasive breast cancer (IBC; n=717). Glutaminase expression was associated with clinicopathological features, patient outcome and glutamine-metabolism related genes. In DCIS, GLS alone and GLS+/GLS2- expression was a risk factor for shorter local recurrence-free interval (

Development of a clinically relevant subclassification of luminal breast cancer related to response to endocrine therapy

Endocrine therapy is widely used in clinical practice as adjuvant treatment for luminal breast cancer. Although clinical outcome of patients with this subtype have markedly improved with endocrine therapy, around 30-50% of patients relapse despite treatment. Therefore, as part of the growing concept of personalised medicine, research priorities are required to more accurately identify predictive markers of endocrine therapy response to aid clinician decision-making. This thesis aimed to identify markers that are able to classify luminal breast tumours into distinct groups with different outcomes in the context of response to endocrine therapy. Large, well-characterised cohorts of primary luminal breast cancer patients with long-term follow-up were assessed for the clinical impact of selected markers at the transcriptomic and proteomic levels. Prognostic significance of these markers with clinical outcome and benefit of endocrine therapy as well as their association with clinicopathological variables and other related-genes were analysed. Bioinformatic analysis was performed to identify differentially expressed genes (DEGs) in terms of response to adjuvant endocrine therapy. In vitro experiments were conducted to investigate the effect of knockdown of key markers in the proliferation of cancer cells and to the sensitivity to endocrine treatment. This thesis has identified key markers with different function including amino acid transporters (SLC1A5, SLC3A2/SLC7A5), cell cycle regulators (KIF18A) and markers of cell motility (PPFIA1 and DBN1) that are associated with worse outcome in luminal tumours. Additionally, results indicate that assessment of their expression prior to adjuvant treatment could subclassify luminal subtype tumours into distinct groups with different outcome in the context of response to endocrine therapy. This could have a great clinical impact in helping guide clinician decision-making. Additional or alternative targeted therapies could then be given to those who have been predicted to have resistance to endocrine therapy, this would be a significant shift toward a more truly individualised medicine. This thesis provides a set of useful targets for future investigation, which could pave the way for novel targeted therapy to overcome endocrine therapy resistance