Somaia Elsheikh

Triple-Negative Breast Cancer: Distinguishing between Basal and Nonbasal Subtypes

Purpose: Triple-negative (TN; estrogen receptor, progesterone receptor, and HER-2 negative) cancer and basal-like breast cancer (BLBC) are associated with poor outcome and lack the benefit of targeted therapy. It is widely perceived that BLBC and TN tumors are synonymous and BLBC can be defined using a TN definition without the need for the expression of basal markers. Experimental Design: We have used two well-defined cohorts of breast cancers with a large panel of biomarkers, BRCA1 mutation status, and follow-up data to compare the clinicopathologic and immunohistochemical features of TN tumors expressing one or more of the specific basal markers (CK5/6, CK17, CK14, and epidermal growth factor receptor; BLBC) with those TN tumors that express none of these markers (TN3BKE−). Results: Here, we show that although the morphologic features of BLBC are not significantly different from that of TN3BKE- tumors, BLBC showed distinct clinical and immunophenotypic differences. BLBC showed a statistically significant association with the expression of the hypoxia-associated factor (CA9), neuroendocrine markers, and other markers of poor prognosis such as p53. A difference in the expression of cell cycle-associated proteins and biomarkers involved in the immunologic portrait of tumors was seen. Compared with TN3BKE- tumors, BLBC was positively associated with BRCA1 mutation status and showed a unique pattern of distant metastasis, better response to chemotherapy, and shorter survival. Conclusion: TN breast cancers encompass a remarkably heterogeneous group of tumors. Expression of basal markers identifies a biologically and clinically distinct subgroup of TN tumors, justifying the use of basal markers (in TN tumors) to define BLBC.

Global Histone Modifications in Breast Cancer Correlate with Tumor Phenotypes, Prognostic Factors, and Patient Outcome

Post-translational histone modifications are known to be altered in cancer cells, and loss of selected histone acetylation and methylation marks has recently been shown to predict patient outcome in human carcinoma. Immunohistochemistry was used to detect a series of histone lysine acetylation (H3K9ac, H3K18ac, H4K12ac, and H4K16ac), lysine methylation (H3K4me2 and H4K20me3), and arginine methylation (H4R3me2) marks in a well-characterized series of human breast carcinomas (n = 880). Tissue staining intensities were assessed using blinded semiquantitative scoring. Validation studies were done using immunofluorescence staining and Western blotting. Our analyses revealed low or absent H4K16ac in the majority of breast cancer cases (78.9%), suggesting that this alteration may represent an early sign of breast cancer. There was a highly significant correlation between histone modifications status, tumor biomarker phenotype, and clinical outcome, where high relative levels of global histone acetylation and methylation were associated with a favorable prognosis and detected almost exclusively in luminal-like breast tumors (93%). Moderate to low levels of lysine acetylation (H3K9ac, H3K18ac, and H4K12ac), lysine (H3K4me2 and H4K20me3), and arginine methylation (H4R3me2) were observed in carcinomas of poorer prognostic subtypes, including basal carcinomas and HER-2-positive tumors. Clustering analysis identified three groups of histone displaying distinct pattern in breast cancer, which have distinct relationships to known prognostic factors and clinical outcome. This study identifies the presence of variations in global levels of histone marks in different grades, morphologic types, and phenotype classes of invasive breast cancer and shows that these differences have clinical significance.

FGFR1 amplification in breast carcinomas: a chromogenic in situ hybridisation analysis

BackgroundThe amplicon on 8p11.2 is reported to be found in up to 10% of breast carcinomas. It has been demonstrated recently that this amplicon has four separate cores. The second core encompasses important oncogene candidates, including the fibroblast growth factor receptor 1 (FGFR1) gene. Recent studies have demonstrated that specific FGFR1 amplification correlates with gene expression and that FGFR1 activity is required for the survival of a FGFR1 amplified breast cancer cell line.MethodsFGFR1 amplification was analysed in tissue microarrays comprising a cohort of 880 unselected breast tumours by means of chromogenic in situ hybridisation using inhouse-generated FGFR1-specific probes. Chromogenic in situ hybridisation signals were counted in a minimum 30 morphologically unequivocal neoplastic cells. Amplification was defined as >5 signals per nucleus in more than 50% of cancer cells or when large gene copy clusters were seen.ResultsFGFR1 amplification was observed in 8.7% of the tumours and was significantly more prevalent in patients >50 years of age and in tumours that lacked HER2 expression. No association was found with other histological parameters. Survival analysis revealed FGFR1 amplification as an independent prognostic factor for overall survival in the whole cohort. Subgroup analysis demonstrated that the independent prognostic impact of FGFR1 amplification was only seen in patients with oestrogen-receptor-positive tumours, where FGFR1 amplification was the strongest independent predictor of poor outcome.ConclusionGiven that up to 8.7% of all breast cancers harbour FGFR1 amplification and that this amplification is an independent predictor of overall survival, further studies analysing the FGFR1 as a potential therapeutic target for breast cancer patients are warranted.

Caveolin 1 and Caveolin 2 are associated with breast cancer basal-like and triple-negative immunophenotype

Caveolin-1 (CAV1) and caveolin 2 (CAV2) are the principal structural proteins of caveolae, sphingolipid and cholesterol-rich invaginations of the plasma membrane involved in vesicular trafficking and signal transduction. Over the recent years there has been controversy about their role in breast cancer and their suitability as markers of basal-like phenotype. Caveolin-1 and CAV2 protein expression was assessed on a tissue microarray containing 880 unselected invasive breast cancer cases, by means of immunohistochemistry. Caveolin-1 and CAV2 expression was observed in 13.4 and 5.9% of all breast cancer, respectively. Their expression was strongly associated with high histological grade, lack of steroid hormone receptor positivity (ER and PR), and expression of basal markers (basal cytokeratins, P63, P-cadherin). Furthermore, there was a significant association between CAV1 and CAV2 expression and basal-like phenotype. On univariate analysis only CAV2 had a prognostic impact on breast cancer-specific survival; however, this was not independent from other traditional markers on multivariate analysis. Our results demonstrate that both CAV1 and CAV2 are associated with basal-like phenotype. Further studies are warranted to determine whether they play an oncogenic role in basal-like/triple-negative breast cancer development or are just surrogate markers for this subgroup.

Expression of BRCA1 protein in breast cancer and its prognostic significance

BRCA1 is a tumor suppressor gene which, when mutated, is associated with the development of hereditary breast cancers. In sporadic tumors, although inherent gene mutations are rare, loss of BRCA1, resulting from reduced expression or incorrect subcellular localization, is postulated to be important. The purpose of the current study was to examine the expression and localization of BRCA1 protein and to assess its prognostic value, in a well-characterized series of unselected breast carcinomas. We have examined BRCA1 in a series of invasive breast carcinoma (1940 cases) using tissue microarray and immunohistochemistry, to evaluate its expression pattern and to correlate this with clinicopathologic variables and patient outcome. In breast cancer, complete loss of nuclear expression was observed in 223 cases (15%) and cytoplasmic expression was found in 541 breast cancers (36.6%). Absent or reduced nuclear BRCA1 expression was observed more frequently in ductal carcinoma of no special type and medullary-like carcinoma and less frequently in lobular and tubular mixed carcinomas. It was also associated with high-grade, advanced lymph node stage, larger size, vascular invasion, negative estrogen receptor, progesterone receptor and androgen receptor expression, and positive p53 and P-cadherin expression, and with the basal-like class of breast cancer. Altered BRCA1 was associated with shorter disease-free interval. Cytoplasmic expression was also associated with development of recurrence and positive EGFR and HER2 expression. It showed an inverse association with survival particularly in low-grade, small-size, and estrogen receptor-positive subgroups. In the grade 1 subgroup, multivariate analysis with adjustment for other prognostic factors showed that cytoplasmic expression of BRCA1 was an independent predictor of disease-free interval. BRCA1 alteration may play a significant role in the development and progression of breast cancer. Immunohistochemical assessment of BRCA1 expression could provide additional clinically relevant information in routine classification of breast cancer.

The Collagen Receptor Endo180 (CD280) Is Expressed on Basal-like Breast Tumor Cells and Promotes Tumor Growth In vivo

Tumor cell invasion into the surrounding stroma requires increased cell motility and extensive remodeling of the extracellular matrix. Endo180 (CD280, MRC2, urokinase-type plasminogen activator receptor-associated protein) is a recycling endocytic receptor that functions in both these cellular activities by promoting cell migration and uptake of collagens for intracellular degradation. In the normal breast, Endo180 is predominantly expressed by stromal fibroblasts. The contrary observation that Endo180 is expressed on epithelial tumor cell lines that display a high invasive capacity suggested that up-regulation of this receptor may be an associated and functional component in the acquisition of a more aggressive phenotype by tumor cells in vivo. Here, we show that high levels of Endo180 are found in a subset of basal-like breast cancers and that this expression is an independent prognostic marker for shorter disease-free survival. Two potential mechanisms for Endo180 up-regulation were uncovered. First, it was shown that Endo180 can be transcriptionally up-regulated in vitro following transforming growth factor-beta treatment of breast cancer cells. Second, a proportion of Endo180(+) tumors were shown to have Endo180 gene copy number gains and amplifications. To investigate the functional consequence of Endo180 up-regulation, MCF7 cells transfected with Endo180 were inoculated into immunocompromised mice. Expression of wild-type Endo180, but not an internalization-defective Endo180 mutant, resulted in enhanced tumor growth together with a reduction in tumor collagen content. Together, these data argue that elevated expression of this receptor in tumor cells could have important consequences in subsets of basal-like carcinomas for which there is a current lack of effective treatment.

Prognostic significance of steroid receptor co-regulators in breast cancer: co-repressor NCOR2/SMRT is an independent indicator of poor outcome

Background Advances in understanding the molecular basis of breast cancer has necessitated a definition of improved indicators of prognosis that are central to the underlying cancer biology and that reflect the heterogeneous nature of the disease. This study investigates the pattern of expression of the steroid receptor co-regulators NCOA1/SRC1, NCOA3/RAC3, NCOR2/SMRT, and CBP/p300 in breast cancer. The aims were to identify whether their expression was related to patient outcome, their relationships to known prognostic factors and to provide a basis for further research into the mechanistic significance of such associations.

Lymphatic and angiogenic characteristics in breast cancer: morphometric analysis and prognostic implications

Controversy exists regarding the topography of lymph vessels in breast cancer, their usefulness as prognostic factors, relationship with angiogenesis and whether active lymphangiogenesis occurs within the tumour. A series of 177 well-characterized breast cancers, with long term follow up, were stained with D2-40, CD31 and CD34. Distribution of lymphatics and lymph vessel density (LVD) were assessed in three areas, intratumoural, peripheral and peritumoural and correlated with clinicopathological criteria and patient prognosis. Microvessel density (MVD) was assessed and correlated with LVD. Double immunohistochemical staining with D2-40 and MIB-1 was carried out to assess the proliferative status of lymphatics and of the tumour emboli within. Peritumoural lymphatics were detected in all tumours whereas peripheral and intratumoural lymphatics were detected in 86 and 41% of specimens, respectively. Tumours with higher total LVD were significantly associated with the presence of lymph node (LN) metastasis and shorter overall survival (OS). In multivariate analysis, tumour grade, LN status and the presence of lymphovascular invasion, but not LVD, were independent poor prognostic factors. No association was found between LVD and MVD. Proliferating lymphatics were detected in 29% of specimens and were significantly associated with dense inflammatory infiltrate. In conclusion, lymphatics are located primarily in the peritumoural and peripheral areas in breast cancer and seem to play an important role in disease progression by being routes for tumour dissemination. The lack of correlation between lymphangiogenic and angiogenic characteristics suggests two distinct processes and the presence of active lymphangiogenesis, albeit in a small portion of specimens, may have important therapeutic implications.

The prognostic significance of steroid receptor co-regulators in breast cancer: co-repressor NCOR2/SMRT is an independent indicator of poor outcome

BackgroundAdvances in understanding the molecular basis of breast cancer has necessitated a definition of improved indicators of prognosis that are central to the underlying cancer biology and that reflect the heterogeneous nature of the disease. This study investigates the pattern of expression of the steroid receptor co-regulators NCOA1/SRC1, NCOA3/RAC3, NCOR2/SMRT, and CBP/p300 in breast cancer. The aims were to identify whether their expression was related to patient outcome, their relationships to known prognostic factors and to provide a basis for further research into the mechanistic significance of such associations.MethodsThe protein levels of steroid receptor co-regulators were assessed by immunohistochemistry in a large well-characterised series of breast carcinomas prepared as tissue microarrays. Relationships between these targets, other clinicopathological variables and patients’ outcome were examined.ResultsNCOR2/SMRT was an independent prognostic indicator of overall patient survival (OS) and disease free interval (DFI) and was significantly correlated with distant metastases and local recurrence whereas tumours expressing NCOA1/SRC1 had a significantly longer OS and DFI. There were also significant correlations between co-regulator expression of NCOA1/SRC1, CBP/p300 and NCOA3/RAC3, which were associated with lower tumour grade. NCOA1/SRC1 was also correlated with smaller tumour size. Furthermore, the co-activators had a significant association with steroid receptors, particularly ERα.ConclusionsNCOR2/SMRT is associated with poor patient outcome, independent of other prognostic factors. In contrast, steroid receptor co-activator expression is generally associated with a good prognosis. Further investigations are needed to establish the mechanisms of these links between the steroid receptor co-regulator system and patient outcome.

Growth fraction as a predictor of response to chemotherapy in node-negative breast cancer

Accurate predictive markers of chemotherapeutic response in early breast cancer are still lacking. The role of tumour growth fraction as a predictor of response to chemotherapy was assessed in early breast cancer. In this study, immunohistochemical expression of MIB1 was studied in a well‐characterised series of early (Stages I and II) node‐negative breast carcinoma cases (n = 100) with long‐term follow‐up that have received adjuvant chemotherapy (cyclophosphamide/methotrexate/5‐fluorouracil regimen). In addition, 728 cases who did not receive adjuvant chemotherapy were used as a control group. Increased tumour growth fraction was associated with a better response to adjuvant chemotherapy in terms of longer breast cancer specific survival and disease‐free interval [hazard ratio (HR) = 0.354, 95% CI = 0.177–0.688, p = 0.003 and HR = 0.396, 95% CI = 0.205–0.768, p = 0.006, respectively]. In contrast to the control group, patients with high growth fraction tumour (>70%) showed an excellent outcome with infrequently reported events during the period of follow‐up. Importantly, patients with a low growth fraction (≤10%) showed frequent recurrences and shorter survival time with outcome comparable to those of high growth fraction who did not receive chemotherapy. Therefore, tumour growth fraction can be used to assign patients into distinct groups showing differential response to adjuvant chemotherapy. Patients with a high growth fraction appear to be ideal candidates for adjuvant chemotherapy while those with low growth fraction are less likely to benefit and are prone to the potential serious side effects of adjuvant chemotherapy.