Dina Leitão

Breast cancer stem cell markers CD44, CD24 and ALDH1: expression distribution within intrinsic molecular subtype

Background and Aim The study of CD44/CD24 and ALDH1 expression is the most accurate method to identify cancer stem cells (CSC) from breast cancer populations. However, the overlap between CD44+CD24−/low and ALDH1high CSC phenotypes in breast cancer seems to be very small, as well as their distribution among intrinsic breast cancer subtypes. Due to this discrepancy, it is imperative to improve the understanding of breast CSC marker distribution. Methods 466 invasive breast carcinomas and eight breast cancer cell lines were analysed for the expression of CD44, CD24 and ALDH1, to evaluate their distribution among the distinct molecular subtypes. Results Basal-like tumours (76.5%) contained the higher percentage of cells with the CSC phenotype CD44+CD24−/low (p<0.0001). From ALDH1-positive cases, 39.4% were also basal-like tumours (p<0.0001). The analysis of breast cancer cell lines indicated that luminal cell lines are mainly enriched in a CD44−/lowCD24+ cell population, basal/mesenchymal breast cancer cell lines are enriched in the CD44+CD24−/low phenotype, whereas the remaining basal/epithelial cell lines are mainly positive for both markers. ALDH1 activity was mainly found in HER-OE and basal/epithelial breast cancer cell. Conclusions CD44+CD24−/low and ALDH1+ phenotypes seem to identify CSC with distinct levels of differentiation. It seems that the paramount method and biomarkers that identify breast CSC within the distinct molecular subtypes need to be better explored, because it is pivotal to translate the CSC concept to clinical practice. In the future, the recognition of reliable markers to distinguish the CSC pool in each molecular subtype will be decisive for the development of specific target therapies.

Association of ERBB2 gene status with histopathological parameters and disease-specific survival in gastric carcinoma patients.

The clinical significance of ERBB2 amplification/overexpression in gastric cancer remains unclear. In this study, we evaluated the ERBB2 status in 463 gastric carcinomas using immunohistochemistry (IHC) and fluorescence in situ hybridisation (FISH), and compared the findings with histopathological characteristics and with disease-specific survival. ERBB2 overexpression (2+ and 3+) and amplification (ratio ERBB2/CEP17⩾2) were found in 43 (9.3%) and 38 (8.2%) gastric carcinomas, respectively. Perfect IHC/FISH correlation was found for the 19 cases scored as 0 (all negative by FISH), and also for the 25 cases scored as 3+ (all positive by FISH). One out of six carcinomas scored as 1+ and 12 out of 18 carcinomas scored as 2+ were positive by FISH. ERBB2 amplification was associated with gastric carcinomas of intestinal type (P=0.007) and with an expansive growth pattern (P=0.021). ERBB2 amplification was detected in both histological components of two mixed carcinomas, indicating a common clonal origin. A statistically significant association was found between ERBB2 amplification and worse survival in patients with expansive gastric carcinomas (P=0.011). We conclude that ERBB2 status may have clinical significance in subsets of gastric cancer patients, and that further studies are warranted to evaluate whether patients whose gastric carcinomas present ERBB2 amplification/overexpression may benefit from therapy targeting this surface receptor.

c-erb B-2 Expression Is Associated with Tumor Location and Venous Invasion and Influences Survival of Patients with Gastric Carcinoma:

The HER-2/neu gene or c-erb B-2, localized on chromosome 17q, belongs to a family of tyrosine kinase receptors and shares extensive homology with the epidermal growth factor receptor. c-erb B-2 gene amplification and protein overexpression have been reported in several human cancers. The prognostic value of this genetic alteration in gastric carcinoma is far from being established. In the present study, formalin-fixed, paraffin-embedded gastric carcinoma tissues from 157 patients were evaluated for c-erb B-2 overexpression, by immunohistochemistry using a polyclonal antibody. c-erb B-2 expression was evaluated according to clinical and pathological parameters, and to the survival of the patients. Our results show that: (1) c-erb B-2 was overexpressed in 15.3% of gastric carcinoma cases; (2) c-erb B-2 overexpression was significantly more frequent in cardia (23.8%) and fundus/body (25.0%) carcinomas than in antrum (7.2%) carcinomas; (3) c-erb B-2 overexpression was significantly associated with venous invasion; (4) c-erb B-2 is a prognostic factor for gastric carcinoma.

Ki67 LABELLING INDEX IN GASTRIC CARCINOMAS. AN IMMUNOHISTOCHEMICAL STUDY USING DOUBLE STAINING FOR THE EVALUATION OF THE PROLIFERATIVE ACTIVITY OF DIFFUSE‐TYPE CARCINOMAS

The aim of the present study was to clarify the conflicting recorded data on the proliferative features of gastric carcinoma. The Ki67 labelling index (Ki67 LI) was evaluated using MIB‐1 in 43 carcinomas (24 diffuse and 19 intestinal). In 18 cases, differential counts were performed in superficial and deep layers. In ten diffuse carcinomas with a prominent desmoplastic response, Ki67 LI was evaluated in sections double‐stained with MIB‐1 and CAM5.2. Flow cytometry was performed in 26 cases. Ki67 LI of diffuse carcinomas (36·3±19·0) was not significantly different from that of intestinal carcinomas (28·2±18·5). Ki67 LI was significantly higher (P=0·006) in superficial than in deep areas (41·9±22·7 and 29·7±19·7, respectively) regardless of histological tumour type. No significant relationship was observed between Ki67 LI and wall invasion, lymph node metastasis, vascular invasion or ploidy. The following conclusions were drawn: double immunostaining techniques are apparently the best way to overcome the underestimation of cell proliferation in diffuse gastric carcinomas with a prominent desmoplastic response; the diffuse and intestinal types of gastric carcinoma have proliferation rates within the same range, even when the comparison is restricted to diploid tumours; and, finally, the major pool of proliferating cells resides in the superficial areas of gastric carcinomas, regardless of the histotype, which should be taken into consideration when overall counts are performed, using either immunohistochemical markers in tissue sections or suspensions of nuclei in flow cytometry.

c-KIT and PDGFRA in breast phyllodes tumours: overexpression without mutations?

Aim: To study the immunoexpression and mutational status of c-KIT and PDGFRA in a series of benign and malignant phyllodes tumours of the breast. Material/methods: Nineteen phyllodes tumours (13 benign and six malignant) were analysed by immunohistochemistry for the expression of c-KIT and PDGFRA. Direct sequencing of exons 9, 11, 13, and 17 of the c-KIT gene and exons 12 and 18 of PDGFRA was performed to check the mutational status of these two genes. Results: c-KIT expression was found in 12 of the 19 cases (six of the 13 benign cases and all six malignant ones) and PDGFRA expression was seen in two of the 19 cases (one benign and one malignant case); the 2415 C>T alteration in exon 17 of the c-KIT gene was found in two cases (both benign); the intronic insertion IVS17-50insT and the 2866 G>T alteration in the coding region of exon 18 of the PDGFRA gene were also found in two cases (one malignant and one benign). However, the activating mutations described for these genes in gastrointestinal stromal tumours were not present. Conclusion: c-KIT expression is a frequent finding in phyllodes tumours, particularly in malignant cases; however, no activating mutations similar to those described for gastrointestinal stromal tumours were found. The PDGFRA does not seem to be an alternative pathway to tumour development in phyllodes tumours because neither expression nor activating mutations were noteworthy.

Aberrant P-cadherin expression: Is it associated with estrogen-independent growth in breast cancer?

Breast carcinomas represent a heterogeneous group of tumors, with a diverse biologic behavior, outcome, and response to therapy. Recent studies have demonstrated that alterations in the expression of adhesion molecules in cancer cells are related to aggressiveness and poor prognosis. The aim of our study was to investigate the expression of P-cadherin in breast carcinomas and correlate it with estrogen receptor (ER) status. We selected 73 ductal carcinomas in situ (DCIS) and 149 invasive carcinomas of the breast, and assessed the expression of P-cadherin as well as other biologic markers. P-cadherin expression showed a strong inverse correlation with ER expression in both types of breast carcinoma (in situ and invasive). P-cadherin-positive and ER-negative tumors were related to a higher histologic grade, a high proliferation rate, and expression of c-erbB-2. We demonstrated that P-cadherin identifies a subgroup of breast carcinomas that lacks ER expression, and correlates with higher proliferation rates and other predictors of aggressive behavior. We believe that these tumors represent an advanced step in cancer progression, and our data support the hypothesis that an estrogen-independent pathway regulates P-cadherin expression.

CD99/MIC‐2 surface protein expression in breast carcinomas

CD99/MIC‐2 surface protein expression in breast carcinomas

Clinicopathological significance and survival influence of p53 protein expression in gastric carcinoma

Aims:  Mutations in the gene coding for p53 protein are among the most frequent genetic alterations observed in human cancers. The relevance and biological significance of p53 expression in gastric carcinoma are far from being fully established. The aim of our study was to evaluate the influence of p53 detected by immunohistochemistry in the clinicopathological behaviour of a series of gastric carcinoma cases.

Topoisomerase II-alfa gene as a predictive marker of response to anthracyclines in breast cancer.

Amplification or deletion of the topoisomerase IIα (TOP2A) gene in breast cancer has been related with responsiveness to anthracyclines-based chemotherapy. The purpose of this study was to evaluate the predictive value of TOP2A gene for the efficacy of neo-adjuvant anthracycline in a population with locally advanced breast cancer. Sixty-two patients were included, and the status of TOP2A gene was determined by in situ hybridization method. Treatment efficacy was determined by clinical and pathological response and overall survival. TOP2A gene alterations were found in 22.6% (21.0% of cases with amplification and 1.6% with deletion), and these tumors were biologically more aggressive, with higher nuclear grade, more frequently with HER2 amplification and inflammatory type. Also in these tumors response to chemotherapy appeared to be increased. There was a higher clinical and pathological response rate (complete pathological response of 21.4% vs. 8.3%), a trend toward longer progression-free survival (82.51 vs. 63.12 months) and a trend to increased overall survival (92.08 months; 95% CI 82.81-101.35 vs. 73.40 months; 95% CI 63.44-83.36; p=0.113). These results corroborate that the TOP2A gene alterations may play an important role in determining anthracycline sensitivity in breast cancer.

Immunohistochemical diagnosis of Fabry nephropathy and localisation of globotriaosylceramide deposits in paraffin-embedded kidney tissue sections

Fabry disease (FD) is a rare X-linked lysosomal storage disorder of glycosphingolipids, mostly globotriaosylceramide (Gb3). Proteinuric chronic kidney disease develops frequently, and recognition of Fabry nephropathy on a kidney biopsy may be the first clue to the underlying diagnosis. Since the accumulated glycosphingolipids are largely extracted by the paraffin-embedding procedure, the most characteristic feature of Fabry nephropathy on routine light microscopy (LM) is nonspecific cell vacuolization. To test whether residual Gb3 in kidney tissue might be exploited for the specific diagnosis of Fabry nephropathy, paraffin-embedded kidney biopsies of nine FD patients (one boy, four men, four women) and of a female carrier of a mild genetic mutation, with no evidence of Fabry nephropathy, were immunostained with an anti-Gb3 antibody. The adult biopsies were additionally co-stained with a lysosomal marker (anti-lysosomal-associated membrane protein 2 (anti-LAMP2) antibody). The distribution of Gb3 deposits was scored per cell type and compared to the histological scorings of glycosphingolipid inclusions on semi-thin sections. FD patients had residual Gb3 in all types of glomerular, tubular, interstitial and vascular kidney cells. The highest expression of LAMP2 was seen in tubular cells, but there were no meaningful associations between LAMP2 expression and prevalence of Gb3 deposits on different kidney cell types. The histological scorings of glycosphingolipid inclusions were relatively higher than the corresponding immunohistochemical scorings of Gb3 deposits. In the mildly affected female, Gb3 expression was limited to tubular cells, a pattern similar to controls. Gb3 immunostaining allows the specific diagnosis of Fabry nephropathy even in kidney biopsies routinely processed for LM.