Maria Grazia Daidone

Isolation and In vitro Propagation of Tumorigenic Breast Cancer Cells with Stem/Progenitor Cell Properties

Breast cancer-initiating cells have been recently identified in breast carcinoma as CD44+/CD24(-/low) cells, which exclusively retain tumorigenic activity and display stem cell-like properties. However, at present, direct evidence that breast cancer-initiating cells can be propagated in vitro is still lacking. We report here the isolation and in vitro propagation of breast cancer-initiating cells from three breast cancer lesions and from an established breast carcinoma cell line. Our breast carcinoma-derived cultures encompassed undifferentiated cells capable of self-renewal, extensive proliferation as clonal nonadherent spherical clusters, and differentiation along different mammary epithelial lineages (ductal and myoepithelial). Interestingly, cultured cells were CD44+/CD24- and Cx43-, overexpressed neoangiogenic and cytoprotective factors, expressed the putative stem cell marker Oct-4, and gave rise to new tumors when as few as 10(3) cells were injected into the mammary fat pad of SCID mice. Long-term cultures of breast tumorigenic cells with stem/progenitor cell properties represent a suitable in vitro model to study breast cancer-initiating cells and to develop therapeutic strategies aimed at eradicating the tumorigenic subpopulation within breast cancer.

Human Bone Marrow–Derived Mesenchymal Stem Cells Do Not Undergo Transformation after Long-term In vitro Culture and Do Not Exhibit Telomere Maintenance Mechanisms

Significant improvement in the understanding of mesenchymal stem cell (MSC) biology has opened the way to their clinical use. However, concerns regarding the possibility that MSCs undergo malignant transformation have been raised. We investigated the susceptibility to transformation of human bone marrow (BM)-derived MSCs at different in vitro culture time points. MSCs were isolated from BM of 10 healthy donors and propagated in vitro until reaching either senescence or passage (P) 25. MSCs in the senescence phase were closely monitored for 8 to 12 weeks before interrupting the cultures. The genetic characterization of MSCs was investigated through array-comparative genomic hybridization (array-CGH), conventional karyotyping, and subtelomeric fluorescent in situ hybridization analysis both before and after prolonged culture. MSCs were tested for the expression of telomerase activity, human telomerase reverse transcriptase (hTERT) transcripts, and alternative lengthening of telomere (ALT) mechanism at different passages. A huge variability in terms of proliferative capacity and MSCs life span was noted between donors. In eight of 10 donors, MSCs displayed a progressive decrease in proliferative capacity until reaching senescence. In the remaining two MSC samples, the cultures were interrupted at P25 to pursue data analysis. Array-CGH and cytogenetic analyses showed that MSCs expanded in vitro did not show chromosomal abnormalities. Telomerase activity and hTERT transcripts were not expressed in any of the examined cultures and telomeres shortened during the culture period. ALT was not evidenced in the MSCs tested. BM-derived MSCs can be safely expanded in vitro and are not susceptible to malignant transformation, thus rendering these cells suitable for cell therapy approaches.

Predicting prognosis using molecular profiling in estrogen receptor-positive breast cancer treated with tamoxifen

BackgroundEstrogen receptor positive (ER+) breast cancers (BC) are heterogeneous with regard to their clinical behavior and response to therapies. The ER is currently the best predictor of response to the anti-estrogen agent tamoxifen, yet up to 30–40% of ER+BC will relapse despite tamoxifen treatment. New prognostic biomarkers and further biological understanding of tamoxifen resistance are required. We used gene expression profiling to develop an outcome-based predictor using a training set of 255 ER+ BC samples from women treated with adjuvant tamoxifen monotherapy. We used clusters of highly correlated genes to develop our predictor to facilitate both signature stability and biological interpretation. Independent validation was performed using 362 tamoxifen-treated ER+ BC samples obtained from multiple institutions and treated with tamoxifen only in the adjuvant and metastatic settings.ResultsWe developed a gene classifier consisting of 181 genes belonging to 13 biological clusters. In the independent set of adjuvantly-treated samples, it was able to define two distinct prognostic groups (HR 2.01 95%CI: 1.29–3.13; p = 0.002). Six of the 13 gene clusters represented pathways involved in cell cycle and proliferation. In 112 metastatic breast cancer patients treated with tamoxifen, one of the classifier components suggesting a cellular inflammatory mechanism was significantly predictive of response.ConclusionWe have developed a gene classifier that can predict clinical outcome in tamoxifen-treated ER+ BC patients. Whilst our study emphasizes the important role of proliferation genes in prognosis, our approach proposes other genes and pathways that may elucidate further mechanisms that influence clinical outcome and prediction of response to tamoxifen.

miR-205 Exerts Tumor-Suppressive Functions in Human Prostate through Down-regulation of Protein Kinase Cε

Limited information is available concerning the expression and role of microRNAs in prostate cancer. In this study, we investigated the involvement of miR-205 in prostate carcinogenesis. Significantly lower miR-205 expression levels were found in cancer than in normal prostate cell lines as well as in tumor compared with matched normal prostate tissues, with a particularly pronounced reduction in carcinomas from patients with local-regionally disseminated disease. Restoring the expression of miR-205 in prostate cancer cells resulted in cell rearrangements consistent with a mesenchymal-to-epithelial transition, such as up-regulation of E-cadherin and reduction of cell locomotion and invasion, and in the down-regulation of several oncogenes known to be involved in disease progression (i.e., interleukin 6, caveolin-1, EZH2). Our evidence suggests that these events are driven by the concurrent repression of specific predicted miR-205 targets, namely N-chimaerin, ErbB3, E2F1, E2F5, ZEB2, and protein kinase Cepsilon. Strikingly, the latter seemed to play a direct role in regulating epithelial-to-mesenchymal transition. In fact, its down-regulation led to a cell phenotype largely reminiscent of that of cells ectopically expressing miR-205. Overall, we showed for the first time that miR-205 exerts a tumor-suppressive effect in human prostate by counteracting epithelial-to-mesenchymal transition and reducing cell migration/invasion, at least in part through the down-regulation of protein kinase Cepsilon.

Expression of the anti-apoptotic gene survivin correlates with taxol resistance in human ovarian cancer

Abstract. Stable transfection of human ovarian carcinoma cells with survivin cDNA caused a four- to sixfold increase in cell resistance to taxotere and taxol (two-sided Students t test, p <0.05), with a concomitant reduction in the apoptotic response to taxol, but did not affect cell sensitivity to cisplatin or oxaliplatin. Such findings were indirectly supported by similar observations obtained with clinical tumours. In fact, high levels of survivin protein expression (>30% positive cells), detected by immunohistochemistry in 90/124 (73%) advanced ovarian carcinomas, were significantly associated with clinical resistance to a taxol/platinum-based regimen but unrelated to tumour shrinkage following cisplatin-including combinations (non-taxol based). In the 95 patients receiving a taxol/platinum-based regimen, survivin overexpression correlated with a lower clinical or pathologic complete remission rate than absent/low protein expression (43 vs 75%, p = 0.0058 by logistic regression adjusted for tumour stage, histological grade and p53 expression). Conversely, in the 29 cases treated with cisplatin-containing regimens (not taxol based), survivin expression was unrelated to tumour response. Cellular studies and clinical data suggest a direct link between survivin expression and tumour cell susceptibility to taxol.

30 years' follow up of randomised studies of adjuvant CMF in operable breast cancer: cohort study

Abstract Objective To assess the long term effectiveness of adjuvant treatment with cyclophosphamide, methotrexate, and fluorouracil (CMF) in patients with operable breast cancer at risk of relapse, on the basis of three successive randomised trials and one observational study conducted from June 1973 to December 1980. Design Cohort study. Setting Istituto Nazionale Tumori in Milan, Italy. Main outcome measures Relapse free and overall survival, measured by univariate and multivariate analyses. Results After a median follow up of 28.5 years for the initial study, adjuvant CMF was found to reduce the relative risk of relapse significantly (hazard ratio 0.71, 95% confidence interval 0.56 to 0.91, P = 0.005) and death (0.79, 0.63 to 0.98, P = 0.04). Administration of CMF for 12 cycles does not seem superior to a shorter administration of six cycles. In the node negative and oestrogen receptor negative trial, intravenous CMF significantly reduced the relative risk of relapse of disease (0.65, 0.47 to 0.90, P = 0.009) and death (0.65, 0.47 to 0.92, P = 0.01) at a median follow up of 20 years. Conclusions When delivered optimally, CMF benefits patients at risk of relapse of distant disease without evidence of detrimental effects in any of the examined subgroups.

Cell kinetics as a prognostic marker in node-negative breast cancer

The relevance of cell kinetics of the primary tumor as a marker of biologic aggressivity was verified on a series of 258 patients with operable breast cancer without nodal and distant metastases, who underwent radical mastectomy without any other treatment until relapse. The cell proliferative rate, evaluated in vitro on fresh tumor material and expressed as 3H‐thymidine labeling index, was found to be an important discriminant of metastatic potential. Patients with slowly proliferating tumors showed a higher probability of 6‐year relapse‐free survival in comparison to those with fast‐proliferating tumors (80.5% versus 59.6%, P ‐ 0.00004). This finding was true for premenopausal and paramenopausal (P ‐ 0.0005) as well as for postmenopausal patients (P ‐ 0.01). The kinetic variable was also a discriminant of 6‐year survival for the overall series (P ‐ 0.003) and for premenopausal and paramenopausal patients (P ‐ 0.003) regardless of the type of treatment after relapse. These findings show the relevance of the kinetic variable as an important prognostic marker in breast cancer. Cancer 56: 1982‐1987, 1985.

Survivin expression and resistance to anticancer treatments: perspectives for new therapeutic interventions

Survivin is a structurally unique member of the inhibitors of apoptosis protein (IAP) family that is involved in both control of cell division and inhibition of apoptosis. Its anti-apoptotic function seems to be related to its ability to directly or indirectly inhibit caspases, although the precise role of survivin in the modulation of the caspase cascade has not been fully elucidated. Survivin has been described to be selectively expressed in the most common human neoplasms and to be associated with clinical tumour progression. Moreover, the protein appears to be involved in tumour cell resistance to some anticancer agents and ionizing radiation. On the basis of these findings survivin has been proposed as a promising target for new anticancer interventions. In in vitro and in vivo studies targeting survivin with antisense oligonucleotides, dominant negative mutants or ribozymes have shown to induce apoptosis, reduce tumour-growth potential and sensitise tumour cells to chemotherapeutic drugs such as Taxol, cisplatin and etoposide, gamma-irradiation, and immunotherapy.

Different genetic features associated with colon and rectal carcinogenesis

Purpose: The issue of whether colon and rectal cancer should be considered as a single entity or two distinct entities is still debated, and there is a need to improve studies addressing the heterogeneity of the pathogenetic pathway leading to sporadic colorectal cancers (SCRCs) as well as to identify biological and/or molecular differences between colon and rectal cancers. Experimental Design: Specimens of SCRCs were analyzed for somatic mutations in APC, K-ras, and TP53 genes and loss-of-heterozygosity of chromosome 18. Results: Eleven SCRCs showed microsatellite instability. APC mutation frequency was significantly lower in microsatellite instability (MIN+) than in MIN− SCRCs. All MIN− SCRCs showed β-catenin overexpression. A combined analysis of the biomarkers revealed two pathways mainly represented by MIN− SCRCs and differently followed on the basis of tumor location, APC-K-ras-TP53-Ch18q and APC-TP53-Ch18q. Conclusions: The APC-β-catenin pathway is inactivated in MIN− SCRCs and represents the first hit of SCRC development. Two preferential pathways followed by SCRCs occur, one K-ras dependent, in agreement with the Fearon and Vogelstein model, and the other K-ras independent. Significant differences between colon and rectal tumors occur in our series of MIN− SCRCs. The different pathways observed and their distribution can be summarized as follows: (a) K-ras mutations were more commonly detected in colon than in rectum; (b) the number of mutations detected was significantly higher in colon than in rectal tumors; and (c) a mutational pattern restricted to the APC gene was more common in rectal than in colon tumors. This molecular characterization can be translated into a clinical setting to improve diagnosis and to direct a rationale pharmacological treatment.

p53 and bcl-2 expression correlates with clinical outcome in a series of node-positive breast cancer patients.

BACKGROUND AND PURPOSE The tumor-suppressor gene TP53 and the proto-oncogene bcl-2 encode, respectively, for a nuclear phosphoprotein and for a mitochondrial protein involved in multiple cellular functions. The proteins provide prognostic information in node-negative breast cancer and are supposed to influence treatment responsiveness. We analyzed the predictive role of p53 and bcl-2 expression, alone and in association with other variables, in postmenopausal women with node-positive, estrogen receptor-positive (ER+) breast cancers treated with radical or conservative surgery plus radiotherapy and adjuvant tamoxifen for at least 1 year. PATIENTS AND METHODS On 240 resectable cancers, we determined the expression of p53 and bcl-2, using immunohistochemistry, cell proliferation (3H-thymidine labeling index [3H-dT LI]), and ER and progesterone receptors (PgR). RESULTS p53 expression and 3H-dT LI were weakly related to one another and both were unrelated to bcl-2. Relapse-free and distant metastasis-free survival at 5 years were significantly lower for patients with tumors that highly expressed p53 (P = .0001) and for those that weakly expressed or did not express bcl-2 (P = .02). However, p53, but not bcl-2, provided prognostic information independent of tumor size, axillary node involvement, steroid receptors, and 3H-dT LI. Moreover, the simultaneous p53 overexpression and lack of PgR identified patients at maximum risk of relapse, whereas bcl-2 overexpression, associated with a low 3H-dT LI or the presence of PgR, improved the prognostic resolution for low-risk patients. CONCLUSION p53 expression appears to be indicative of clinical outcome in postmenopausal patients treated with tamoxifen. Whether p53 overexpression and weak bcl-2 expression are indicators of biologic aggressiveness, regardless of treatment, or of hormone resistance remains to be defined.