Chemokine (C-C motif) receptor 7 (CCR7) associates with the tumour immune microenvironment but not progression in invasive breast carcinoma

Some previous studies have reported that the chemokine (C-C motif) receptor 7 (CCR7) plays a role in breast cancer, is associated with lymph node metastasis and drives the site of distant metastasis. However, the impact of its expression on patient outcome and its association with tumour infiltrating inflammatory cells remain to be validated. We evaluated CCR7 protein expression by immunohistochemistry in a large well characterized cohort (n = 866) of early invasive primary breast cancers. CCR7 was expressed in the cytoplasm and membrane of tumour cells. We observed a weak positive association of high CCR7 expression when in either cellular component, but not both together, with axillary lymph node stage 3 tumours (p = 0.043). Logistic regression analysis of lymph node stage revealed no independent predictive value for CCR7 expression. CCR7 expression was higher in HER2 positive tumours (p = 0.03) and associated with positive CD68+ FOXP3+ tumour infiltrating cells. CCR7 staining was negatively associated with CD3+ cells. There was no significant association of CCR7 expression with breast cancer recurrence or survival. We conclude that while CCR7 is not a useful biomarker for predicting lymph node metastasis, it may reflect altered intra- and inter-cellular signalling related to the immune microenvironment. The subcellular localization of CCR7 appears to affect the nature of these interactions

Ki67 expression in invasive breast cancer: the use of tissue microarrays compared with whole tissue sections.

BACKGROUND: Although the prognostic value of Ki67 in breast cancer is well documented, using optimal cut-points for patient stratification, reproducibility of the scoring and interpretation of the results remains a matter of debate particularly when using tissue microarrays (TMAs). This study aims to assess Ki67 expression assessed on TMAs and their matched whole tissue sections (WTS). Moreover, whether the cut-off used for WTS is reproducible on TMA in BC molecular classes and the association between Ki67 expression cut-off, assessed on TMAs and WTS, and clinicopathological parameters and patient outcome were tested. METHOD: A large series (n = 707) of primary invasive breast tumours were immunostained for Ki67 using both TMA and WTS and assessed as percentage staining and correlated with each other, clinicopathological parameters and patient outcome. In addition, MKI67 mRNA expression was correlated with Ki67 protein levels on WTS and TMAs in a subset of cases included in the METABRIC study. RESULTS: There was moderate concordance in Ki67 expression between WTS and TMA when analysed as a continuous variable (Intraclass correlation coefficient = 0.61) and low concordance when dichotomised (kappa value = 0.3). TMA showed low levels of Ki67 with mean percentage of expression of 35 and 22% on WTS and TMA, respectively. MKI67 mRNA expression was significantly correlated with protein expression determined on WTS (Spearman Correlation, r = 0.52) and to a lesser extent on TMA (r = 0.34) (p < 0.001). Regarding prediction of patient outcome, statistically significant differences were detected upon stratification of patients with tumours expressing Ki67 at 10, 15, 20, 25 or 30% in TMA. Using TMA, ≥20% Ki67 provided the best prognostic cut-off particularly in triple-negative and HER2-positive classes. CONCLUSION: Ki67 expression in breast cancer can be evaluated using TMA although different cut-points are required to emulate results from WTS. A cut-off of ≥20% for Ki67 expression in BC provides the best prognostic correlations when TMAs are used

ADA3 regulates normal and tumor mammary epithelial cell proliferation through c-MYC

Background: We have established the critical role of ADA3 as a coactivator of estrogen receptor (ER), as well as its role in cell cycle progression. Furthermore, we showed that ADA3 is predominantly nuclear in mammary epithelium, and in ER+, but is cytoplasmic in ER- breast cancers, the latter correlating with poor survival. However, the role of nuclear ADA3 in human mammary epithelial cells (hMECs), and in ER+ breast cancer cells, as well as the importance of ADA3 expression in relation to patient prognosis and survival in ER+ breast cancer have remained uncharacterized.Methods: We overexpressed ADA3 in hMECs or in ER+ breast cancer cells and assessed the effect on cell proliferation. The expression of ADA3 was analyzed then correlated with the expression of various prognostic markers, as well as survival of breast cancer patients.Results: Overexpression of ADA3 in ER- hMECs as well as in ER+ breast cancer cell lines enhanced cell proliferation. These cells showed increased cyclin B and c-MYC, decreased p27 and increased SKP2 levels. This was accompanied by increased mRNA levels of early response genes c-FOS, EGR1, and c-MYC. Analysis of breast cancer tissue specimens showed a significant correlation of ADA3 nuclear expression with c-MYC expression. Furthermore, nuclear ADA3 andc-MYC expression together showed significant correlation with tumor grade, mitosis, pleomorphism, NPI, ER/PR status, Ki67 and p27 expression. Importantly, within ER+ cases, expression of nuclear ADA3 and c-MYC also significantly correlated with Ki67 and p27 expression. Univariate Kaplan Meier analysis of four groups in the whole, as well as the ER+ patients showed that c-MYC and ADA3 combinatorial phenotypes showed significantly different breast cancer specific survival with c-MYC-high and ADA3-Low subgroup had the worst outcome. Using multivariate analyses within the whole cohort and the ER+ subgroups, the significant association of ADA3 and c-MYC expression with patients’ outcome was independent of tumor grade, stage and size, and ER status.Conclusion: ADA3 overexpression enhances cell proliferation that is associated with increased expression of c-MYC. Expression patterns with respect to ADA3/c-MYC can divide patients into four significantly different subgroups, with c-MYC High and ADA3 Low status independently predicting poor survival in patients

Clinicopathological and functional significance of RECQL1 helicase in sporadic breast cancers

RECQL1, a key member of the RecQ family of DNA helicases, is required for DNA replication and DNA repair. Two recent studies have shown that germline RECQL1 mutations are associated with increased breast cancer susceptibility. Whether altered RECQL1 expression has clinicopathologic significance in sporadic breast cancers is unknown. We evaluated RECQL1 at the transcriptomic level (METABRIC cohort, n = 1,977) and at the protein level [cohort 1, n = 897; cohort 2, n = 252; cohort 3 (BRCA germline deficient), n = 74]. In RECQL1-depleted breast cancer cells, we investigated anthracycline sensitivity. High RECQL1 mRNA was associated with intClust.3 (P = 0.026), which is characterized by low genomic instability. On the other hand, low RECQL1 mRNA was linked to intClust.8 [luminal A estrogen receptor–positive (ER+) subgroup; P = 0.0455] and intClust.9 (luminal B ER+ subgroup; P = 0.0346) molecular phenotypes. Low RECQL1 expression was associated with shorter breast cancer–specific survival (P = 0.001). At the protein level, low nuclear RECQL1 level was associated with larger tumor size, lymph node positivity, high tumor grade, high mitotic index, pleomorphism, dedifferentiation, ER negativity, and HER-2 overexpression (P < 0.05). In ER+ tumors that received endocrine therapy, low RECQL1 was associated with poor survival (P = 0.008). However, in ER− tumors that received anthracycline-based chemotherapy, high RECQL1 was associated with poor survival (P = 0.048). In RECQL1-depleted breast cancer cell lines, we confirmed doxorubicin sensitivity, which was associated with DNA double-strand breaks accumulation, S-phase cell-cycle arrest, and apoptosis. We conclude that RECQL1 has prognostic and predictive significance in breast cancers

Clinicopathological and prognostic significance of RECQL5 helicase expression in breast cancers

RECQL5 is a member of the RecQ family of DNA helicases and has key roles in homologous recombination, base excision repair, replication and transcription. The clinicopathological significance of RECQL5 expression in breast cancer is unknown. In the current study we have evaluated RECQL5 mRNA expression in 1977 breast cancers, and RECQL5 protein level in 1902 breast cancers [Nottingham Tenovus series (n=1650) and ER- cohort (n=252)]. Expression levels were correlated to aggressive phenotypes and survival outcomes. High RECQL5 mRNA expression was significantly associated with high histological grade (p=0.007), HER2 overexpression (p=0.032), ER+/HER2-/high proliferation genefu subtype, integrative molecular clusters (intClust 1and 9) and poor breast cancer specific survival (BCSS) (ps<0.0001). In sub-group analysis, high RECQL5 mRNA level remains significantly associated with poor BCSS in ER+ cohort (p<0.0001) but not in ER- cohort (p=0.116). At the protein level, in tumours with low RAD51, high RECQL5 level was significantly associated with high histological grade (p<0.0001), higher mitotic index (p=0.008), de-differentiation (p=0.025), pleomorphism (p=0.027) and poor BCSS (P=0.003). In sub-group analysis, high RECQL5/low RAD51 remains significantly associated with poor BCSS in ER+ cohort (p=0.010), but not in ER- cohort (p=0.628). In multivariate analysis, high RECQL5 mRNA and high RECQL5/low RAD51 nuclear protein co-expression independently influenced BCSS (p=0.022) in whole cohort and in the ER+ sub-group. Pre-clinically, we show that exogenous expression of RECQL5 in MCF10A cells can drive proliferation supporting an oncogenic function for RECQL5 in breast cancer. We conclude that RECQL5 is a promising biomarker in breast cancer

RECQL4 helicase has oncogenic potential in sporadic breast cancers

RECQL4 helicase is a molecular motor that unwinds DNA, a process essential during DNA replication and DNA repair. Germ-line mutations in RECQL4 cause type II Rothmund–Thomson syndrome (RTS), characterized by a premature ageing phenotype and cancer predisposition. RECQL4 is widely considered to be a tumour suppressor, although its role in human breast cancer is largely unknown. As the RECQL4 gene is localized to chromosome 8q24, a site frequently amplified in sporadic breast cancers, we hypothesized that it may play an oncogenic role in breast tumourigenesis. To address this, we analysed large cohorts for gene copy number changes (n = 1977), mRNA expression (n = 1977) and protein level (n = 1902). Breast cancer incidence was also explored in 58 patients with type II RTS. DNA replication dynamics and chemosensitivity was evaluated in RECQL4-depleted breast cancer cells in vitro. Amplification or gain in gene copy number (30.6%), high-level mRNA expression (51%) and high levels of protein (23%) significantly associated with aggressive tumour behaviour, including lymph node positivity, larger tumour size, HER2 overexpression, ER-negativity, triple-negative phenotypes and poor survival. RECQL4 depletion impaired the DNA replication rate and increased chemosensitivity in cultured breast cancer cells. Thus, although recognized as a ’safe guardian of the genome’, our data provide compelling evidence that RECQL4 is tumour promoting in established breast cancers

Transcriptomic and Protein Expression Analysis Reveals Clinicopathological Significance of Bloom Syndrome Helicase (BLM) in Breast Cancer

BLM has key roles in homologous recombination repair, telomere maintenance and DNA replication. Germ-line mutation in the BLM gene causes Bloom’s syndrome, a rare disorder characterised by premature aging and predisposition to multiple cancers including breast cancer. The clinicopathological significance of BLM in sporadic breast cancers is unknown. We investigated BLM mRNA expression in the Molecular Taxonomy of Breast Cancer International Consortium cohort (n=1950) and validated in an external dataset of 2413 tumours. BLM protein level was evaluated in the Nottingham Tenovus series comprising 1650 breast tumours. High BLM mRNA expression was highly significantly associated with high histological grade, larger tumour size, ER negative, PgR negative and triple negative phenotypes (ps<0.0001). High BLM mRNA expression was also linked to aggressive molecular phenotypes including PAM50.Her2 (p<0.0001), PAM50.Bas al (p<0.0001) and PAM50.LumB (p<0.0001) and Genufu subtype (ER+/Her2-/High proliferation) (p<0.0001). PAM50.LumA tumours and Genufu subtype (ER+/Her2-/low proliferation) were more likely to express low levels of BLM mRNA (ps<0.0001). Integrative molecular clusters (intClust) intClust.1 (p<0.0001), intClust.5 (p<0.0001), intClust.9 (p<0.0 001) and intClust.10 (p<0.0001) were also more likely in tumours with high BLM mRNA expression. High BLM mRNA expression was associated with poor breast cancer specific survival (BCSS) (ps<0.000001). At the protein level, altered sub-cellular localisation with high cytoplasmic BLM and low nuclear BLM was linked to aggressive phenotypes. In multivariate analysis, BLM mRNA and BLM protein levels independently influenced BCSS ( p=0.03). This is the first and the largest study to provide evidence that BLM is a promising biomarker in breast cancer

The prognostic significance of BMI1 expression in invasive breast cancer is dependent on its molecular subtypes

Purpose: BMI-1, which is a major component of the polycomb groupcomplex 1 is an essential epigenetic repressor of multiple regulatory genes and has been identified as a cancer stem cell (CSC) marker in several cancers. However, its role in breast cancer (BC) remains to be defined. In this study, we have evaluated the prognostic significance of BMI-1 among the different molecular subtypes and assessed its association with other breast CSC markers (BCSC).Material and Method: BMI-1 copy number and mRNA was assessed in large and well-characterised cohorts of early-stage BC patients [METABRIC (n=1980) and the Bc-GenExMiner (n=9616) databases]. BMI-1 protein expression was assessed using tissue microarray and immunohistochemistry in a cohort of 870 invasive BC patients with long- term outcome data and the expression of a panel of BCSC markers was monitored.Result: BMI-1 expression, prognostic significance and its association with BCSC markers were differed between molecular classes. In the luminal oestrogen receptor positive (ER+) BC, BMI-1 showed significantly higher expression compared to ER- tumours. BMI-1 showed positive correlation with favourable prognostic features and it was negatively associated with the expression of key BCSC markers (ALDH1A1, CD24, CD44, CD133, SOX10 and SOX9). High expression of BMI-1 was associated with longer breast cancer specific survival (BCSS) independent of other prognostic variables. In the basal triple negative BC subtype, BMI-1 expression showed positive association with CD133 and SOX10 and it was significantly associated with shorter BCSS.Conclusion: High variables and outcome in BC. However, this association is dependent on the molecular subtypes. Further functional assessment to detect its underlying mechanistic roles in BC subtypes is warranted

The prognostic significance of ALDH1A1 expression in early invasive breast cancer

Aims: Aldehyde dehydrogenase family 1 member A1 (ALDH1A1)is reportedly a key ALDH isozyme linked to the cancer stem cells (CSC) of many solid tumours, where it is involved in self-renewal, differentiation and self-protection. In this study, the prognostic significance of ALDH1A1 expression in early invasive breast cancer (BC) and its role as a BC stem cell (BCSC) were evaluated.Methods: ALDH1A1 expression was assessed, using immunohistochemistry and tissue microarrays, in a large well- characterised BC cohort. ALDH1A1 mRNA expression was also assessed at the transcriptomic levels, utilising data from the Molecular Taxonomy of Breast Cancer International Consortium. The associations of ALDH1A1 with clinicopathological parameters, other stem cell markers and patient outcomes were determined.Results: ALDH1A1 was expressed in 71% of BC cases, at both the protein and mRNA levels. High ALDH1A1 expression was associated with poor prognostic features, including high grade, poor Nottingham Prognostic Index (NPI), lymph node metastasis and highly proliferative ER+ (luminal B) and triple negative (TNBC) subtypes. ALDH1A1 expression was positively correlated with the expression of CD44, CD24, TWIST, SOX9, EPCAM and CD133. The high immunoexpression of ALDH1A1 was significantly associated with poor BC-specific survival [less than] 0.001), and specifically in the luminal B and TNBC subtypes (P=0.042 and P=0.003, respectively). The immunoexpression of ALDH1A1 was an independent predictor of poor prognosis (P=0.015).Conclusions: ALDH1A1, as assessed using IHC, seems to act as a BCSC marker associated not only with other BCSC markers but also with poor prognostic characteristics and poor outcomes, particularly in the luminal B and TNBC subtypes

MYC functions are specific in biological subtypes of breast cancer and confers resistance to endocrine therapy in luminal tumours.

BACKGROUND: MYC is amplified in approximately 15% of breast cancers (BCs) and is associated with poor outcome. c-MYC protein is multi-faceted and participates in many aspects of cellular function and is linked with therapeutic response in BCs. We hypothesised that the functional role of c-MYC differs between molecular subtypes of BCs. METHODS: We therefore investigated the correlation between c-MYC protein expression and other proteins involved in different cellular functions together with clinicopathological parameters, patients' outcome and treatments in a large early-stage molecularly characterised series of primary invasive BCs (n=1106) using immunohistochemistry. The METABRIC BC cohort (n=1980) was evaluated for MYC mRNA expression and a systems biology approach utilised to identify genes associated with MYC in the different BC molecular subtypes. RESULTS: High MYC and c-MYC expression was significantly associated with poor prognostic factors, including grade and basal-like BCs. In luminal A tumours, c-MYC was associated with ATM (P=0.005), Cyclin B1 (P=0.002), PIK3CA (P=0.009) and Ki67 (P<0.001). In contrast, in basal-like tumours, c-MYC showed positive association with Cyclin E (P=0.003) and p16 (P=0.042) expression only. c-MYC was an independent predictor of a shorter distant metastases-free survival in luminal A LN+ tumours treated with endocrine therapy (ET; P=0.013). In luminal tumours treated with ET, MYC mRNA expression was associated with BC-specific survival (P=0.001). In ER-positive tumours, MYC was associated with expression of translational genes while in ER-negative tumours it was associated with upregulation of glucose metabolism genes. CONCLUSIONS: c-MYC function is associated with specific molecular subtypes of BCs and its overexpression confers resistance to ET. The diverse mechanisms of c-MYC function in the different molecular classes of BCs warrants further investigation particularly as potential therapeutic targets