Maria Marone

Semiquantitative RT-PCR analysis to assess the expression levels of multiple transcripts from the same sample

We describe a semiquantitative RT-PCR protocol optimized in our laboratory to extract RNA from as little as 10,000 cells and to measure the expression levels of several target mRNAs from each sample. This procedure was optimized on the human erythroleukemia cell line TF-1 but was successfully used on primary cells and on different cell lines. We describe the detailed procedure for the analysis of Bcl-2 levels. Aldolase A was used as an internal control to normalize for sample to sample variations in total RNA amounts and for reaction efficiency. As for all quantitative techniques, great care must be taken in all optimization steps: the necessary controls to ensure a rough quantitative (semi-quantitative) analysis are described here, together with an example from a study on the effects of TGF-β1 in TF-1 cells.

Analysis of cyclin E and CDK2 in ovarian cancer: Gene amplification and RNA overexpression

Cyclins and their associated kinases (cdks) play a key role in controlling the cell cycle, a process whose disregulation can potentially lead to uncontrolled cell growth and hence to cancer. We have studied the role of both cyclin E and its associated kinase cdk2 in ovarian cancer. Primary, metastatic, recurrent and benign ovarian tumors were screened for cyclin E and cdk2 gene amplification. Cyclin E was shown to be amplified in 21% and cdk2 in 6.4% of the cases analyzed. Cyclin E and cdk2 RNA expression levels were determined by semi‐quantitative RT‐PCR analysis in a partially overlapping series of samples and compared to the expression levels of normal ovarian surface epithelial cells. Cyclin E RNA was overexpressed in 29.5% and cdk2 in 6.5% of ovarian tumors tested. We determined that in most cases gene amplification leads to higher RNA levels for cyclin E and that the overall levels of cyclin E and cdk2 RNA were correlated. We hypothesize that cyclin E and cdk2 are, in part co‐regulated and that they may concur to ovarian tumor development. Int. J. Cancer 75:34–39, 1998.© 1998 Wiley‐Liss, Inc.

Tamoxifen induces oxidative stress and apoptosis in oestrogen receptor-negative human cancer cell lines

SummaryRecent data have demonstrated that the anti-oestrogen tamoxifen (TAM) is able to facilitate apoptosis in cancer cells not expressing oestrogen receptor (ER). In an attempt to identify the biochemical pathway for this phenomenon, we investigated the role of TAM as an oxidative stress agent. In two ER-negative human cancer cell lines, namely T-leukaemic Jurkat and ovarian A2780 cancer cells, we have demonstrated that TAM is able to generate oxidative stress, thereby causing thiol depletion and activation of the transcriptional factor NF-κB. As described for other oxidative agents, TAM was able to induce either cell proliferation or apoptosis depending on the dose. When used at the lowest dose tested (0.1 μM), a slight proliferative effect of TAM was noticed in terms of cell counts and DNA synthesis rate, whereas at higher doses (10 μM) a consistent occurrence of apoptosis was detected. Importantly, the induction of apoptosis by TAM is not linked to down-regulation or functional inactivation by phosphorylation of the antiapoptotic bcl-2 protein.

Altered expression of cyclin D1 and CDK4 genes in ovarian carcinomas

We analyzed the expression and amplification of cyclin D1 and CDK4 genes in ovarian carcinomas. Northern blot analysis revealed overexpression of cyclin D1 in 12 of 65 (18%) ovarian carcinomas while CDK4 was overexpressed in 7 of 48 cases (14%). None of the tumors showed amplification of any of the 2 genes. Overexpression of cyclin D1 and CDK4 transcripts was correlated, suggesting a role of both genes in altered growth control of ovarian cancer cells. Elevated levels of cyclin D1 were significantly associated with a well‐moderately differentiated grade (G1‐G2) (p < 0.005). No significant association was found between cyclin D1 expression and estrogen receptor, progesterone and epidermal growth factor receptor content. Cyclin D1 expression does not appear to be associated with clinical outcome in human ovarian cancer, although a longer follow‐up period and screening of other molecules involved in the same pathway would be necessary to assess this hypothesis. Int. J. Cancer 74:390–395, 1997.

CD105 (Endoglin) Expression on Hematopoietic Stem/Progenitor Cells

Endoglin (CD105) is a component of the transforming growth factor-β (TGF-β) receptor (TGF-βR) complex. Together with betaglycan, CD105 is considered as a TGF-βR accessory molecule (also called TGF-βRIII), but its functions in the receptor-ligand interactions are still poorly understood. A small subset of human CD34+ hematopoietic stem/progenitor cells that has phenotypic and functional features suggestive of very primitive hematopoietic cells expresses the CD105 antigen. CD34+/CD105+ cells recirculate in the peripheral blood of mobilized subjects and can be purified by immunomagnetic isolation strategies. The hematopoietic potential of these CD34+/CD105+ cells appears to be sustained by a combination of hematopoietic and non-hematopoietic cytokines, which comprises Flt3 ligand, erythropoietin, interleukin-15 and vascular endothelial growth factor. Endogenous TGF-β1 is a crucial factor for the maintenance of CD34+/CD105+ immaturity acting through positive modulation of both CD105 and CD34 molecules in the absence of relevant effects on the cell cycle profile. CD105 is absent on very primitive CD34-/lineage-/CD45+ (CD34-Lin-) human hematopoietic cells isolated from cord blood. However, in vitro exposure of CD34-Lin-cells to exogenous TGF-β1 causes the appearance of a discrete population of CD34+/CD105+ cells. Collectively, available data on CD105 expression and function in primitive hematopoiesis indicate that this molecule could cooperate with the dissociation of TGF-β1 cell cycle effects from its other effects on cell survival and differentiation.

CD34+/CD105+ cells are enriched in primitive circulating progenitors residing in the G0 phase of the cell cycle and contain all bone marrow and cord blood CD34+/CD38low/− precursors

A subset of circulating CD34+ cells was found to express CD105 antigen. Sorting experiments showed that most granulocyte–macrophage colony‐forming units (GM‐CFU) and burst‐forming units — erythroid (BFU‐E) were retained in the CD34+/CD105− fraction, whereas rare GM‐CFU/BFU‐E were generated from CD34+/CD105+ cells. Megakaryocytic aggregates were entirely retained in the CD34+/CD105+ fraction. Neutralizing doses of an anti‐TGF‐β1 antibody demonstrated CD34+/CD105+ cells capable of colony‐forming activity without any significant effect on CD34+/CD105− cells. Cloning of secondary colonies revealed that CD34+/CD105+ cells had a significantly higher secondary cloning efficiency than CD34+/CD105− cells. CD34+/CD105+ cells had a significantly higher long‐term culture‐initiating cell (LTC‐IC) frequency than CD34+/CD105− cells. Kinetic analysis showed that 75% of CD34+/CD105+ cells consisted of DNA 2n G0Ki‐67− cells whereas 82% of CD34+/CD105− were DNA 2n G1Ki‐67+ cells, and this latter subset showed a RNA content consistently higher than CD34+/CD105+ cells. CD34+/CD105+ progenitors were CD25+, whereas CD34+/CD105− contained a small CD25+ subset. Three‐colour analysis of bone marrow and cord blood CD34+ cells demonstrated that all the CD34+/CD38low/− primitive precursors were contained in CD34+/CD105+ cells. Extensive characterization of these CD105+ precursors indicated that they have biological properties associated with primitive haematopoietic precursors.

nm23 in ovarian cancer: correlation with clinical outcome and other clinicopathologic and biochemical prognostic parameters

PURPOSE The aim of the study was to define the prognostic role of the metastasis suppressor gene, nm23, in 106 primary ovarian cancer patients. PATIENTS AND METHODS Northern and Western blotting analysis of nm23-H1 and nm23-H2 expression were performed in a subset of ovarian tumors. Immunohistochemical analysis was performed on formalin-fixed paraffin-embedded specimens from 106 primary ovarian carcinomas by the antihuman nm23 monoclonal antibody. RESULTS Northern and Western blotting analysis demonstrated a direct association between nm23-H1 and nm23-H2 levels. Moreover, an overall concordance of 86.7% between Northern blotting and immunohistochemical data was observed. Sixty-six specimens (68%) showed a positive nm23-H1 immunoreaction. The percentage of nm23-H1 positivity was higher in lymph node-negative (70%) than in lymph node-positive cases (44%) (P = .049). Moreover, the percentage of complete/partial responses to chemotherapy was higher in nm23-H1-positive (69%) than in nm23-H1-negative (44%) patients (P = .03). The percentage of epidermal growth factor receptor (EGFR) positive cases was lower in nm23-H1-positive (44%) than in nm23-H1-negative immunostained (72%) samples (P = .012). Lower ras/p21 levels (median, 1.77 absorbance units) were found in nm23-H1-positive than in nm23-H1-negative samples (median, 2.63 absorbance units) (P = .03). The 6-year progression-free survival (PFS) rate of nm23-H1-positive cases was 50% (95% confidence interval [CI], 33 to 67) versus 12% (95% CI, -2 to 26) for nm23-H1-negative patients (P = .0056). In multivariate analysis, only stage, ascites, and nm23-H1 content retained independent prognostic roles. CONCLUSION The assessment of nm23 content may provide useful information for prognostic characterization of ovarian cancer patients.

Nm23 expression in endometrial and cervical cancer : inverse correlation with lymph node involvement and myometrial invasion

The expression of nm23 has been shown to correlate in some solid tumours with their metastatic potential and to be associated with a favourable prognosis in human breast cancer and melanoma. In breast and ovarian cancer nm23 expression is also correlated with lymph node involvement. We analysed the expression of nm23-H1 and -H2 in normal endometrium and in endometrial and cervical cancer by both Northern and Western blotting. Cellular localisation of Nm23-H1 was visualised by immunohistochemistry mostly in the cytoplasm. Both isoforms of Nm23 were present in all the samples analysed, and a clear direct correlation between Nm23-H1 and -H2 levels was evident. Median nm23-H2 levels were higher than than -H1 levels in both tissues. Cervical cancer patients with lymph node involvement were shown to have significantly lower protein levels of Nm23 (P < 0.007 for H1 and P < 0.009 for H2), and a similar trend was also evident in endometrial cancer. Furthermore, the degree of myometrial invasion in endometrial cancer patients was also inversely correlated with Nm23-H1 levels of expression (P < 0.003). Nm23 level may therefore be taken into consideration as a new marker in the prognostic characterisation and in the treatment planning of uterine tumour patients.

Clinical isolation and functional characterization of cord blood CD133+ hematopoietic progenitor cells

BACKGROUND:  Human cord blood is a relevant source of CD133+ HPCs. Clinical‐scale isolation of human umbi‐lical cord blood (UCB) CD133+ HPCs using immunomag‐netic microbeads and the CliniMACS clinical cell isolator is reported. CD133+ HPCs isolated after large‐scale pro‐cessing were functionally characterized.

Identification of a Novel Subpopulation of Human Cord Blood CD34−CD133−CD7−CD45+Lineage− Cells Capable of Lymphoid/NK Cell Differentiation After In Vitro Exposure to IL-15

The hemopoietic stem cell (HSC) compartment encompasses cell subsets with heterogeneous proliferative and developmental potential. Numerous CD34− cell subsets that might reside at an earlier stage of differentiation than CD34+ HSCs have been described and characterized within human umbilical cord blood (UCB). We identified a novel subpopulation of CD34−CD133−CD7−CD45dimlineage (lin)− HSCs contained within human UCB that were endowed with low but measurable extended long-term culture-initiating cell activity. Exposure of CD34−CD133−CD7−CD45dimlin− HSCs to stem cell factor preserved cell viability and was associated with the following: 1) concordant expression of the stem cell-associated Ags CD34 and CD133, 2) generation of CFU-granulocyte-macrophage, burst-forming unit erythroid, and megakaryocytic aggregates, 3) significant extended long-term culture-initiating cell activity, and 4) up-regulation of mRNA signals for myeloperoxidase. At variance with CD34+lin− cells, CD34−CD133−CD7−CD45dimlin− HSCs maintained with IL-15, but not with IL-2 or IL-7, proliferated vigorously and differentiated into a homogeneous population of CD7+CD45brightCD25+CD44+ lymphoid progenitors with high expression of the T cell-associated transcription factor GATA-3. Although they harbored nonclonally rearranged TCRγ genes, IL-15-primed CD34−CD133−CD7−CD45dimlin− HSCs failed to achieve full maturation, as manifested in their CD3−TCRαβ−γδ− phenotype. Conversely, culture on stromal cells supplemented with IL-15 was associated with the acquisition of phenotypic and functional features of NK cells. Collectively, CD34−CD133−CD7−CD45dimlin− HSCs from human UCB displayed an exquisite sensitivity to IL-15 and differentiated into lymphoid/NK cells. Whether the transplantation of CD34−lin− HSCs possessing T/NK cell differentiation potential may impact on immunological reconstitution and control of minimal residual disease after HSC transplantation for autoimmune or malignant diseases remains to be determined.