Expression of CDK7, cyclin H and MAT1 is elevated in breast cancer and is prognostic in estrogen receptor-positive breast cancer

PURPOSE: CDK-activation kinase (CAK) is required for the regulation of the cell-cycle and is a trimeric complex consisting of Cyclin Dependent Kinase 7 (CDK7), Cyclin H and the accessory protein, MAT1. CDK7 also plays a critical role in regulating transcription, primarily by phosphorylating RNA polymerase II, as well as transcription factors such as estrogen receptor-alpha(ERalpha).). Deregulation of cell cycle and transcriptional control is aare general featurefeatures of cancertumor cells, highlighting the potential for the use of CDK7 inhibitors as novel cancer therapeutics in cancer. EXPERIMENTAL DESIGN: mRNA and protein expression of CDK7 and its essential co-factors cyclinH and MAT1, were evaluated in breast cancer samples to determine if their levels are altered in cancer. Immunohistochemical staining of >900 breast cancers was used to determine the association with clinicopathological features and patient outcome. RESULTS: We show that expression of CDK7, cyclinH and MAT1 are all closely linked at the mRNA and protein level and their expression is elevated in breast cancer compared with the normal breast tissue. Intriguingly, CDK7 expression was inversely proportional to tumour grade and size and outcome analysis showed an association between CAK levels and better outcome. Moreover, CDK7 expression was positively associated with ERalpha expression and in particular with phosphorylation of ERalpha at serine 118, a site important for ERalpha transcriptional activity. CONCLUSIONS: Expression of components of the CAK complex, CDK7, MAT1 and Cyclin H are elevated in breast cancer and correlates with ERalpha.. Like ERalpha, CDK7 expression is inversely proportional to poor prognostic factors and survival

The multifunctional solute carrier 3A2 (SLC3A2) confers a poor prognosis in the highly proliferative breast cancer subtypes

Background: Breast cancer (BC) is a heterogeneous disease characterised by variant biology, metabolic activity and patient outcome. This study aimed to evaluate the biological and prognostic value of the membrane solute carrier, SLC3A2 in BC with emphasis on the intrinsic molecular subtypes. Methods: SLC3A2 was assessed at the genomic level, using METABRIC data (n=1,980), and proteomic level, using immunohistochemistry on TMA sections constructed from a large well-characterised primary BC cohort (n=2,500). SLC3A2 expression was correlated with clinicopathological parameters, molecular subtypes, and patient outcome. Results: SLC3A2 mRNA and protein expression were strongly correlated with higher tumour grade and poor Nottingham prognostic index (NPI). High expression of SLC3A2 was observed in triple negative (TN), HER2+, and ER+ high proliferation subtypes. SLC3A2 mRNA and protein expression were significantly associated with the expression of c-MYC in all BC subtypes (p<0.001). High expression of SLC3A2 protein was associated with poor patient outcome (p<0.001)), but only in the ER+ high proliferation (p=0.01) and triple negative (p=0.04) subtypes. In multivariate analysis SLC3A2 protein was an independent risk factor for shorter breast cancer specific survival (p<0.001). Conclusions: SLC3A2 appears to play a role in the aggressive BC subtypes driven by MYC and could act as a potential prognostic marker. Functional assessment is necessary to reveal its potential therapeutic value in the different BC subtypes

Checkpoint kinase1 (CHK1) is an important biomarker in breast cancer having a role in chemotherapy response

Background:Checkpoint kinase1 (CHK1), which is a key component of DNA-damage-activated checkpoint signalling response, may have a role in breast cancer (BC) pathogenesis and influence response to chemotherapy. This study investigated the clinicopathological significance of phosphorylated CHK1 (pCHK1) protein in BC.Method:pCHK1 protein expression was assessed using immunohistochemistry in a large, well-characterized annotated series of early-stage primary operable invasive BC prepared as tissue microarray (n=1200).Result:pCHK1 showed nuclear and/or cytoplasmic expression. Tumours with nuclear expression showed positive associations with favourable prognostic features such as lower grade, lower mitotic activity, expression of hormone receptor and lack of expression of KI67 and PI3K (

Novel immunohistochemistry-based signatures to predict metastatic site of triple-negative breast cancers

Background: Although distant metastasis (DM) in breast cancer (BC) is the most lethal form of recurrence and the most commonunderlying cause of cancer related deaths, the outcome following the development of DM is related to the site of metastasis.Triple negative BC (TNBC) is an aggressive form of BC characterised by early recurrences and high mortality. Athough multiplevariables can be used to predict the risk of metastasis, few markers can predict the specific site of metastasis. This study aimed atidentifying a biomarker signature to predict particular sites of DM in TNBC.Methods: A clinically annotated series of 322 TNBC were immunohistochemically stained with 133 biomarkers relevant to BC, todevelop multibiomarker models for predicting metastasis to the bone, liver, lung and brain. Patients who experienced metastasisto each site were compared with those who did not, by gradually filtering the biomarker set via a two-tailed t-test and Coxunivariate analyses. Biomarker combinations were finally ranked based on statistical significance, and evaluated in multivariableanalyses.Results: Our final models were able to stratify TNBC patients into high risk groups that showed over 5, 6, 7 and 8 times higher riskof developing metastasis to the bone, liver, lung and brain, respectively, than low-risk subgroups. These models for predictingsite-specific metastasis retained significance following adjustment for tumour size, patient age and chemotherapy status.Conclusions: Our novel IHC-based biomarkers signatures, when assessed in primary TNBC tumours, enable prediction of specificsites of metastasis, and potentially unravel biomarkers previously unknown in site tropism

Prognostic significance of androgen receptor expression in invasive breast cancer: transcriptomic and protein expression analysis

Differential prognostic roles of Androgen Receptor (AR) have been proposed in breast cancer (BC) depending on tumour oestrogen receptor (ER) status. This study aimed to evaluate the prognostic and/or predictive significance of AR expression in invasive BC. In this study AR expression was studied on a large (n = 1141) consecutive series of early-stage (I-III) BC using tissue microarray and immunohistochemistry (IHC). AR mRNA expression was assessed in a subset of cases. The prognostic impact of AR mRNA expression was externally validated using the online BC gene expression data sets (n = 25 data sets, 4078 patients). Nuclear AR IHC expression was significantly associated with features of good prognosis including older age, smaller tumour size, lower grade and lobular histology particularly in the ER-positive tumours. AR was associated with ER-related markers GATA3, FOXa1, RERG and BEX1. Negative association was observed with HER2, p53, Ki67, TK1, CD71 and AGTR1. AR Overexpression was associated with longer survival (p < 0.001), independent of tumour size, grade, stage [p = 0.033, hazard ratio (HR) = 0.80 95 % CI = 0.64-0.98]. Similar associations were maintained in ER+ tumours in univariate and multivariate analysis (p < 0.01) both in patients with and without adjuvant endocrine or chemotherapy. AR mRNA expression showed significant association with tumour grade, molecular subtypes, and longer 10 and 15 years survival in luminal BC. In the external validation cohorts, AR gene expression data were associated with improved patients' outcome (p < 0.001, HR = 0.84, 95 % CI 0.79-0.90). AR is not only an independent prognostic factor in ER-positive luminal BC but is also expressed in ER-negative tumours. AR could act as a molecular target in patients with ER-positive disease predicting response to adjuvant therapy

Prognostic and biological significance of proliferation and HER2 expression in the luminal class of breast cancer

The definition of Luminal-B subclass of breast cancer (BC) varies in literature. In this study, we have compared the proliferation status; assessed using KI67 labeling index (KI67-LI), and HER2-expression in estrogen receptor positive (ER+) BC to assess their impact on the biological and clinical characteristics of luminal-BC. 1547 (73.8 %) well-characterized clinically annotated stage I–III ER + BC were assessed for expression of KI67, HER2 (ASCO guidelines), and a large panel of relevant biomarkers (no = 37). 46.3 % of the cases show high KI67-LI (>13 %) and 8.4 % show HER2+ and both markers are positively associated with younger age, higher tumor grade and poorer outcome. High KI67-LI and HER2+ are associated with upregulation of ER-coactivators and proliferation-related markers and with downregulation of good prognostic markers. High KI67-LI is associated with larger size, advanced stage, and lymphovascular invasion (LVI) and with downregulation of luminal-enriched and DNA-damage repair markers. In contrast, HER2+ is associated with upregulation of ER-regulated proteins and E-cadherin. When analysis is restricted to high KI67-LI subgroup, HER2+ shows an association with upregulation of differentiation-associated proteins and E-cadherin. Conversely, within HER2+ class, high KI67-LI maintains its association with downregulation of differentiation-associated/luminal-enriched proteins. Outcome analyses indicate that both markers are independently associated with shorter survival but HER2+ is associated with a worse outcome. Although both are associated with high proliferation and poor prognosis within ER + BC, HER2+ is less frequent than high KI67-LI. Unlike KI67, HER2 seems to independently drive the aggressive behavior of ER+ tumors without downregulation of luminal proteins