Putative Role of Circulating Human Papillomavirus DNA in the Development of Primary Squamous Cell Carcinoma of the Middle Rectum: A Case Report.

Here we present the case of a patient affected by rectal squamous cell carcinoma in which we demonstrated the presence of Human Papillomavirus (HPV) by a variety of techniques. Collectively, the virus was detected not only in the tumor but also in some regional lymph nodes and in non-neoplastic mucosa of the upper tract of large bowel. By contrast, it was not identifiable in its common sites of entry, namely oral and ano-genital region. We also found HPV DNA in the plasma-derived exosome. Next, by in vitro studies, we confirmed the capability of HPV DNA-positive exosomes, isolated from the supernatant of a HPV DNA positive cell line (CaSki), to transfer its DNA to human colon cancer and normal cell lines. In the stroma nearby the tumor mass we were able to demonstrate the presence of virus DNA in the stromal compartment, supporting its potential to be transferred from epithelial cells to the stromal ones. Thus, this case report favors the notion that human papillomavirus DNA can be vehiculated by exosomes in the blood of neoplastic patients and that it can be transferred, at least in vitro, to normal and neoplastic cells. Furthermore, we showed the presence of viral DNA and RNA in pluripotent stem cells of non-tumor tissue, suggesting that after viral integration (as demonstrated by p16 and RNA in situ hybridization positivity), stem cells might have been activated into cancer stem cells inducing neoplastic transformation of normal tissue through the inactivation of p53, p21, and Rb. It is conceivable that the virus has elicited its oncogenic effect in this specific site and not elsewhere, despite its wide anatomical distribution in the patient, for a local condition of immune suppression, as demonstrated by the increase of T-regulatory (CD4/CD25/FOXP3 positive) and T-exhausted (CD8/PD-1positive) lymphocytes and the M2 polarization (high CD163/CD68 ratio) of macrophages in the neoplastic microenvironment. It is noteworthy that our findings depicted a static picture of a long-lasting dynamic process that might evolve in the development of tumors in other anatomical sites.

Expression of Translationally Controlled Tumor Protein in Human Kidney and in Renal Cell Carcinoma.

Translationally controlled tumor protein is a multifaceted protein involved in several physiological and biological functions. Its expression in normal kidney and in renal carcinomas, once corroborated by functional data, may add elements to elucidate renal physiology and carcinogenesis. In this study, translationally controlled tumor protein expression was evaluated by quantitative real time polymerase chain reaction and western blotting, and its localization was examined by immunohistochemistry on 84 nephrectomies for cancer. In normal kidney protein expression was found in the cytoplasm of proximal and distal tubular cells, in cells of the thick segment of the loop of Henle, and in urothelial cells of the pelvis. It was also detectable in cells of renal carcinoma with different pattern of localization (membranous and cytoplasmic) depending on tumor histotype. Our data may suggest an involvement of translationally controlled tumor protein in normal physiology and carcinogenesis. However, functional in vitro and in vivo studies are needed to verify this hypothesis.

Translationally controlled tumor protein in prostatic adenocarcinoma: correlation with tumor grading and treatment-related changes.

Prostate cancer is the second leading cause of cancer-related death. The androgen deprivation therapy is the standard treatment for advanced stages. Unfortunately, virtually all tumors become resistant to androgen withdrawal. The progression to castration-resistance is not fully understood, although a recent paper has suggested translationally controlled tumor protein to be implicated in the process. The present study was designed to investigate the role of this protein in prostate cancer, focusing on the correlation between its expression level with tumor differentiation and response to treatment. We retrieved 292 prostatic cancer specimens; of these 153 had been treated only by radical prostatectomy and 139 had undergone radical prostatectomy after neoadjuvant treatment with combined androgen blockade therapy. Non-neoplastic controls were represented by 102 prostatic peripheral zone specimens. In untreated patients, the expression of the protein, evaluated by RT-qPCR and immunohistochemistry, was significantly higher in tumor specimens than in non-neoplastic control, increasing as Gleason pattern and score progressed. In treated prostates, the staining was correlated with the response to treatment. An association between protein expression and the main clinicopathological factors involved in prostate cancer aggressiveness was identified. These findings suggest that the protein may be a promising prognostic factor and a target for therapy.

Is tissue inhibitor of metalloproteinase-1 a new prognosticator for breast cancer? An analysis of 266 cases.

Overexpression of tissue inhibitor of metalloproteinase-1 at either the messenger RNA or protein level has been related to a poorer prognosis in breast cancer. We investigated the role of tissue inhibitor of metalloproteinase-1 tissue expression, which was evaluated by immunohistochemistry staining of paraffin-embedded samples, as a possible prognostic indicator in breast cancer. The study included 266 patients treated by primary surgery. Tumors were scored tissue inhibitor of metalloproteinase-1 positive when at least 10% of the cells showed moderate or strong staining. Staining was observed in 76 (28.6%) patients; by multivariate analysis, factors independently associated with tissue inhibitor of metalloproteinase-1 positivity included more than 9 metastatic axillary nodes, high Mib-1 expression, and positivity for plasminogen activator inhibitor and CD44. With a median follow-up of 125 months, tissue inhibitor of metalloproteinase-1 expression showed a significant prognostic role in disease-free and overall survival by univariate analysis. Multivariate analysis confirmed an independent negative prognostic impact of tissue inhibitor of metalloproteinase-1 on overall but not disease-free together with high values of Mib-1. The number of involved axillary nodes, and triple negativity were independent predictors of either poorer disease-free or overall survival. In our study, tissue inhibitor of metalloproteinase-1 expression was significantly related to markers of tumor aggressiveness and was a powerful indicator of poorer prognosis, with a difference in 10-year disease-free and overall survival of 14% and 28%, respectively, between tissue inhibitor of metalloproteinase-1-negative and tissue inhibitor of metalloproteinase-1-positive cases. Expression of tissue inhibitor of metalloproteinase-1 also was an independent prognostic factor in node-positive cases, indicating a possible role of tissue inhibitor of metalloproteinase-1 as a marker of reduced chemosensitivity. Thus, tissue inhibitor of metalloproteinase-1 may have a role in clinical practice as a prognostic and predictive factor and a possible target for future therapies.

Patients with thymomas have an increased risk of developing additional malignancies: lack of immunological surveillance?

AIMS: To assess the risk, for patients with thymoma, of developing an additional malignancy (AM). METHODS AND RESULTS: We studied 68 patients with thymomas. Based on the World Health Organization classification, the tumours were categorised as A, AB or B (B1, B2, B3) thymomas. Control populations comprised 114 patients with colorectal cancer, 108 patients with lymphoma and 123 patients with thyroid carcinoma. Patients with thymomas showed a higher risk of developing an AM (22 of 68 patients versus 11 of 114, eight of 108, and eight of 123 patients, respectively; P = 0.0002). The association between thymomas and AMs was related to the thymoma histotype, with B1, B2, B3 and AB tumours showing a higher risk of developing an AM than A thymomas (P = 0.0474). CONCLUSIONS: Patients affected by thymomas showed a significantly higher risk of developing additional malignancies than those in the control groups, and cases that exhibited a predominantly cortical component were more likely to develop other neoplasms. This may be related to the functions of cortical thymic epithelial cells in providing for T lymphocyte maturation through interaction with major histocompatibility complexes.

ß-catenin and Gli1 are prognostic markers in glioblastoma.

Glioblastomas (GBMs), the most common primary malignancies of the central nervous system, are highly aggressive and heterogeneous, and remain a dramatic therapeutic challenge. Markers mirroring the complex molecular profile of GBMs that are predictive of patient outcomes are needed to define novel multi-targeted treatment strategies. Resistance to current GBM therapies is partly due to a subpopulation of stem-like and other self-renewing cells (hereafter called glioma stem-like cancer cells, GSCC), which are therefore of key interest as therapeutic entry points. Wnt and Hedgehog are among the main pathways involved in GSCC renewal. ß-catenin and Gli1 are markers of Wnt and Hedgehog activation respectively and both pathways are known to be altered in gliomas. To date, there are no investigations of Gli1 protein expression in GBM tissue, and recently a high expression of ß-catenin has been found to have a poor prognostic impact in GBM patients in a study. We have therefore quantified the positivity for ß-catenin, Gli1, as well as Ki-67, p53, and EGFR proteins on immunohistochemically-stained GBM sections from 106 patients in an investigation for potential predictive biomarkers. Correlation between these markers and survival was evaluated by pair-wise Pearson correlation coefficient and by bi-dimensional hierarchical clustering, followed by survival estimations using linear regression models and classification trees. We demonstrated that both ß-catenin and, for the first time, Gli1 proteins are highly predictive markers of short survival, being found in 75 and 90% of the highly predictive trees, respectively, whereas Ki-67, p53 and EGFR were under 30% and thus, not considered as predictive. Our results indicate a role of ß-catenin and Gli1 in GBM malignant behaviour, and suggest that inhibiting members of Wnt and Hedgehog pathways could be a valuable therapeutic strategy for GBM patients.

Rheumatoid nodule and combined pulmonary carcinoma: topographic correlations; a case report and review of the literature.

An association between rheumatoid arthritis (RA) and malignancies has been ascertained and patients with RA appear to be at higher risk of lymphoma and lung cancer. The higher risk of the latter malignancy may be related to rheumatoid interstitial lung disease and immunosuppressive therapies. Herein we illustrate the case of a 59-year-old male smoker affected by RA and treated with cortisone, methotrexate and TNF-α antagonists, who underwent right lower lobectomy for a nodular lesion. On microscopic examination, the lesion consisted of two distinct areas: a central area of fibrinoid necrosis, bordered by histiocytes in a palisaded arrangement, lymphocytes and a 0.4 cm thick peripheral area constituted by a combined small cell anaplastic carcinoma, adenocarcinoma and squamous cell carcinoma. The combination of three histotypes is very rare in such a small tumour. In our case, it may be hypothesized that synchronous, heterogeneous mutations occurred in different type of committed cells or in stem cells, due to the production of cytokines by RA nodule histiocytes and lymphocytes, which are contiguous to the carcinomatous area. Since few studies have evaluated the topographic correlation between tumors and rheumatoid lung lesions, further morphological and molecular studies are needed to clarify this association and the pathogenetic relationship between RA and cancer of the lung.

Lack of allelic exclusion by secondary rearrangements of tumour B-cell receptor light chains in hairy cell leukaemia.

Analyses of the tumour immunoglobulin (Ig) gene (IG) heavy (H) and light chains show heterogeneity of mutational status, but reveal common features of ongoing IGH isotype-switching with multiple IGH isotype expression and preference of IG lambda (IGL) light chain with selective use of IGLJ3. Phenotypic and immunogenetic analyses were performed in a series of 105 HCL patients to estimate prevalence of multiple IG light chain expression by the tumour cells. By phenotype, 3/105 HCL (2.9%) expressed double tumour-related Ig kappa (K) and L light chain proteins. By immunogenetic analysis, functional mutated double IGK(I) /IGK(II) , IGK(I) /IGL(I) and IGL(I) /IGL(II) transcripts were cloned and sequenced in 3/71 (4.2%) HCL. These latter three HCL expressed multiple IGH isotypes with mutated IGHVDJ rearrangements at the time of AID transcript expression. Most interestingly, the three cases had reinduced RAG1 transcript. In the double IGL expresser, single-cell analysis documented co-expression of the tumour-related IGLs in 5/6 cells (83%). In the IGK/IGL co-expresser, evidence of surface IgK/IgL isotype proteins confirmed functionality of the tumour-derived transcripts. The evidence of double light chain expression in single HCs and the new observation of RAG re-induction suggest ongoing selective influences on the BCR that may promote or maintain the HCL clone in the periphery.

Traditional and new prognosticators in breast cancer: Nottingham index, Mib-1 and estrogen receptor signaling remain the best predictors of relapse and survival in a series of 289 cases.

Histopathological and immunohistochemical findings on tissue microarrays, overall survival (OS), disease-free survival (DFS) and incidence of relapses (R) were recorded and statistically analyzed in 289 breast cancers. A higher R and a shorter DFS were significantly related to larger tumors, lymph node invasion, higher tumor grade, absence of estrogen receptors (ER), triple negative tumors, and presence of lymphovascular invasion (LVI). Longer OS was observed to be significantly associated with smaller tumor size (T), lymph node negativity, lower tumor grade, absence of LVI, lower Mib-1 expression and with the presence of ER. At multivariate analysis, only T for DFS and lymph node status and triple negativity either for DFS or OS had independent prognostic value. In the 194 lymph node-negative women DFS and OS were inversely related to tumor grade, absence of ER, Mib-1 expression in more than 15% of neoplastic cells and, only for DFS, presence of LVI. In the 95 lymph node-positive the number of involved nodes was the most discriminating parameter either for DFS or OS; T, Her-2 status and presence of LVI were significantly related to DFS. ER negativity was related to higher grade, progesterone receptors (PR) negativity, Her-2 negativity, hence to triple negativity, to basal-like type, Mib-1expression over 15% of neoplastic cells. Her-2 positivity was related to higher grade, ER positivity and PR positivity. Basal-like type was not an independent prognosticator, while triple negative type has a significant relation to shorter OS. The Nottingham prognostic index accurately identifies prognostic groupings and Mib-1 expression and ER signaling are the key biological predictors even in single cases.

Italy-Japan agreement and discrepancies in diagnosis of superficial gastric lesions.

The agreement between Italian and Japanese endoscopists and pathologists on endoscopic and histopathological diagnoses of superficial gastric lesions is verified with the use of Paris and Vienna classifications. The correlations between Paris endoscopic types and Vienna histopathological categories is high in both the independent Italian and Japanese evaluations. However, the agreement between Italian and Japanese endoscopists is moderate due to the difficult evaluation of the height of the lesions, in particular when they are mixed. The agreement on the size of the lesions is fairly good. The probability of the same allocation to the Vienna categories of a single case is 87 per cent, disagreements remaining in dysplasia grading, between dysplasia, not only high-grade but also low-grade, and in situ carcinoma, and on cancer invasion of the lamina propria. The results indicate that use of the Paris and Vienna classifications has reduced the discrepancies between Western and Japanese endoscopists and pathologists in the diagnosis of these lesions.

Rare lymphoid neoplasms coexpressing B- and T-cell antigens. The role of PAX-5 gene methylation in their pathogenesis.

We report 3 cases of lymphoid neoplasms with mixed lineage features of T-, NK-, or B-cell marker expression and clonal gene rearrangement for both T-cell receptor and immunoglobulin light chain IgK. A characteristic of our cases was the lack of expression of the specific B-cell transcription factor, Pax5, which is essential for maintaining the identity and function of mature B cells during late B lymphopoiesis. In the absence of Pax5, B cells in vitro can differentiate into macrophages, dendritic cells, granulocytes, and T/NK cells. Methylation analysis of the Pax5 gene in our cases suggests that its inactivation by this epigenetic event in a committed or mature B cell, before plasma cell differentiation, may well be a common pathogenetic mechanism in mature lymphoid neoplasms with expression of multilineage antigens. In particular, case 1 may represent a mixed NK- and B-cell lineage; and cases 2 and 3 may represent mixed T and B-cell lineage, respectively. Aberrations in the DNA methylation patterns are currently recognized as a hallmark of human cancer. Cases with aberrant phenotypes require molecular analysis for lineage assignment. Studies of such cases may be helpful to better elucidate whether they represent a distinct entity with clinical, immunophenotypic, and molecular characteristics or an incidental phenomenon during malignant transformation. Interestingly, these cases were all characterized by poor clinical outcome.

CD34+ cord blood cell-transplanted Rag2-/- gamma(c)-/- mice as a model for Epstein-Barr virus infection.

Recent studies suggest that Epstein-Barr virus (EBV) can infect naïve B cells, driving them to differentiate into resting memory B cells via the germinal center reaction. This hypothesis has been inferred from parallels with the biology of normal B cells but has never been proven experimentally. Rag2(-/-) gamma(c)(-/-) mice that were transplanted with human CD34(+) cord blood cells as newborns were recently shown to develop human B, T, and dendritic cells, constituting lymphoid organs in situ. Here we used this model to better define the strategy of EBV infection of human B cells in vivo and to compare this model system with different conditions of EBV infection in humans. Our results support the model of EBV persistence in vivo in cases that were characterized by follicular hyperplasia and a relatively normal CD4(+) and CD8(+) T-cell distribution. Intriguingly, in cases that were characterized by nodular and diffuse proliferation with a preponderance of CD8(+) T cells, similar to infectious mononucleosis, EBV still infects naïve B cells but also induces clonal expansion and ongoing somatic mutations without germinal center reactions. Our results reveal different strategies of EBV infection in B cells that possibly result from variations in the host immune response. Future experiments might allow understanding of the mechanisms responsible for persistent EBV infection and provide targets for more highly tailored therapeutic interventions.

Activated Akt as an indicator of prognosis in gastric cancer.

The immunohistochemical expression of phosphorylated (activated) Akt (pAkt) in 50 advanced gastric carcinomas has been analyzed and the results correlated with age, sex, location in the stomach, histotype, stage, survival, mitotic and apoptotic index, some cell cycle regulators (cyclin D1, cyclin E, p34/cdc2, p27/kip1), and cell proliferation. There was a statistically significant direct correlation between pAkt expression (both cytoplasmatic and nuclear) and depth of infiltration of the tumor, number of infiltrated lymph nodes and p34/cdc2 expression, and between prevalently nuclear pAkt and cyclin D1 and cyclin E. Conversely, there was a significant inverse correlation between nuclear pAkt and apoptotic index and between cytoplasmatic and nuclear pAkt and patient survival. No correlation was found between pAkt and sex, age, tumor location, histotype, mitotic index, and cell proliferation. These findings suggest that pAkt may be considered an indicator of tumor progression and patient survival in gastric cancer.

Age at menarche is not an independent risk factor for high-risk human papillomavirus infections and cervical intraepithelial neoplasia.

Data are controversial as to the role of menarche age as a risk factor of high-risk human papillomavirus (HR-HPV) infections. The objective of this study was to analyse the risk estimates for age at menarche as determinant of cervical intraepithelial neoplasia (CIN) and HR-HPV infections. A cohort of 3187 women were stratified into three groups according to their age at menarche: (i) women <13 years of age; (ii) those between 13 and 14 years and (iii) women >15 years of age. These groups were analysed for predictors of (a) HR-HPV, (b) high-grade CIN and (c) outcome of HR-HPV and cytological abnormalities during prospective follow-up. All the three groups had identical prevalence of HR-HPV, Papanicolaou smear abnormalities and CIN grades. In contrast to menarche age itself, the time from menarche to the first intercourse (TMI), to the first pregnancy (TMP) and to the first delivery (TMD) were all significant (P = 0.0001) predictors of HR-HPV (but not CIN2) in univariate analysis, but lost their significance in a multivariate model. Outcome of cervical disease and HR-HPV infection was unrelated to menarche age, the latter and the three intervals being not predictors of CIN2 in a multivariate model. In conclusion, age at menarche and the intervals between menarche and (i) onset of sexual activity, (ii) first pregnancy and iii) first delivery, are not independent predictors of HR-HPV infections and CIN2 in multivariate analysis.

Cdk9/Cyclin T1 complex: a key player during the activation/differentiation process of normal lymphoid B cells.

Cdk9/Cyclin T1 complex is very important in controlling specific differentiative pathways of several cell types. Limited data are available regarding the expression of Cdk9/Cyclin T1 in hematopoietic and lymphoid tissues. Cdk9/Cyclin T1 expression seems to be related to particular stages of lymphoid differentiation/activation. In this study, we observed that the expression level of Cdk9/Cyclin T1 in vivo increases in memory B cells compared to naïve B cells, and in activated B cells, compared to non-activated ones. The expression level of the Cdk9/Cyclin T1 complex does not increase in cells induced to differentiate in vitro. In addition, we showed that Cdk9 interacts with E12 and E47, specifically activated during Germinal Center (GC) reaction. Taken together this data suggests an active role for the Cdk9/Cyclin T1 complex during lymphoid differentiation through germinal center reaction.

Utility of tumour-infiltrating CD25+FOXP3+ regulatory T cell evaluation in predicting local recurrence in vertical growth phase cutaneous melanoma.

Tumour-infiltrating lymphocytes (TILs) represent the local immune response to cancer, however, their correlation with tumour behaviour is not unanimously considered in the literature. Most studies have not characterized TILs, that are known to comprise distinct subsets, bearing different roles in the complex tumour microenvironment. Characterization of patient lymphocytes has been mainly performed in peripheral blood, that is not always representative of the local immune status. Only few investigations have been performed at the tissue level in cancer, including melanoma. TILs encompass different populations of effector and regulatory T cells (Tregs), and the relevance of the latter in tumour progression is widely accepted. The transcription factor gene product FOXP3 is considered the most reliable marker of Tregs. However, it has not been extensively evaluated in primary cutaneous melanoma. We analyzed 66 vertical growth phase primary cutaneous melanomas, aiming at finding differences in TIL subsets between two groups of cases, that behaved differently in terms of local recurrence. In our study, the percentage of Tregs, as characterized by CD25 and FOXP3 expression, both among tumour cells, inside tumour parenchyma and at its periphery, and among TILs, at the tumour-stroma boundary, was significantly higher in cases that recurred than in those that did not (p=0.00065; p=0.00014; p<0.00001, respectively). TIL characterization by immunohistochemistry in melanoma diagnostic reports, could add further information. The analysis of a larger series of patients and correlation with other clinical parameters, such as distant metastases and/or patient survival, are mandatory for validating its use as a prognostic indicator.

VEGF-D is expressed in activated lymphoid cells and in tumors of hematopoietic and lymphoid tissues.

Vascular Endothelial Growth Factor (VEGF)-D is a member of the VEGF family of angiogenic growth factors that activate the Vascular Endothelial Growth Factor Receptor (VEGFR)-2 and VEGFR-3, which are mainly expressed in blood and lymphatic vessels. Here we have analyzed by using monoclonal antibodies, the expression of VEGF-D and its cognate receptor VEGFR-3 in normal and pathologic bone marrow and lymph node biopsies. This analysis revealed that VEGF-D is expressed in B cells of the germinal centers, scattered B and T blasts, myeloid progenitors, acute leukemia, several types of non Hodgkin lymphoma, and classical Hodgkin's lymphoma. In normal tissues VEGFR-3 was only expressed in fenestrated capillaries of bone marrow and in lymphatic vessels of lymph nodes, while in VEGF-D expressing tumors newly formed vessels, but not malignant cells, showed high VEGFR-3 expression. These data suggest that VEGF-D could contribute to leukemia and lymphoma growth via the induction of angiogenesis in bone marrow and lymphoid tissues.

Smoking is an independent risk factor for oncogenic human papillomavirus (HPV) infections but not for high-grade CIN.

BACKGROUND: Recent evidence implicates smoking as a risk factor for cervical cancer (CC), but the confounding from high-risk human papillomavirus (HPV) infections is not clear. OBJECTIVES: To analyse the role of smoking as an independent predictor of CIN2+ and HR-HPV infections in a population-based prospective (NIS, New Independent States of former Soviet Union) cohort study. STUDY DESIGN AND METHODS: A cohort of 3,187 women was stratified into three groups according to their smoking status: (i) women who never smoked; (ii) those smoking in the past; and (iii) women who are current smokers. These groups were analysed for predictors of (a) HR-HPV; (b) high-grade CIN, and (c) outcome of HR-HPV infections and cytological abnormalities during prospective follow-up (n = 854). RESULTS: The three groups were significantly different in all major indicators or risk sexual behaviour (or history) implicating strong confounding. There was no increase in HSIL/LSIL/ASC-US cytology or CIN1+/CIN2+/CIN3+ among current smokers. Only few predictors of HR-HPV and CIN2+ were common to all three groups, indicating strong interference of the smoking status. There was no difference in outcomes of cervical disease or HR-HPV infections between the three groups. In multivariate model, being current smoker was one of the five independent predictors of HR-HPV (P = 0.014), with adjusted OR = 1.52 (95%CI 1.09-2.14). In addition to age, HR-HPV was the only independent predictor of CIN2+ in multivariate model (OR = 14.8; 95%CI 1.72-127.31). CONCLUSIONS: These data indicate that cigarette smoking is not an independent risk factor of CIN2+, but the increased risk ascribed to smoking is mediated by acquisition of HR-HPV, of which current smoking was an independent predictor in multivariate model.

Gene-expression analysis identifies novel RBL2/p130 target genes in endemic Burkitt lymphoma cell lines and primary tumors.

Burkitt lymphoma (BL) is a B-cell tumor whose characteristic gene aberration is the translocation t(8;14), which determines c-myc overexpression. Several genetic and epigenetic alterations other than c-myc overexpression have also been described in BL. It has been demonstrated that the RBL2/p130 gene, a member of the retinoblastoma family (pRbs), is mutated in BL cell lines and primary tumors. The aim of this study was to investigate the biologic effect of RBL2/p130 in BL cells and its possible role in lymphomagenesis. Therefore, we reintroduced a functional RBL2/p130 in BL cell lines where this gene was mutated. Our results demonstrated that RBL2/p130-transfected cells regain growth control. This suggests that RBL2/p130 may control the expression of several genes, which may be important for cell growth and viability. Gene-expression analysis revealed a modulation of several genes, including CGRRF1, RGS1, BTG1, TIA1, and PCDHA2, upon RBL2/p130 reintroduction. We then monitored their expression in primary tumors of endemic BL as well, demonstrating that their expression resembled those of the BL cell lines. In conclusion, these data suggest that, as RBL2/p130 modulates the expression of target genes, which are important for cell growth and viability, its inactivation may be relevant for the occurrence of BL.

The role of the Cdk9/Cyclin T1 complex in T cell differentiation.

The Cdk9/Cyclin T1 complex is very important in controlling specific differentiative pathways of several cell types, including muscle cells and neurons. We recently demonstrated the involvement of this complex in B cell activation/differentiation. To check whether the Cdk9/Cyclin T1 complex is also involved in the T cell activation/differentiation process, we isolated different T cell populations by magnetic separation, based on their surface antigens. We observed that the expression level of Cdk9/Cyclin T1 increases in effector T cells (CD27(+)), as well as in activated T cells (CD25(+)) and memory T cells (CD45RA(-)), thus suggesting a specific upregulation of the Cdk9/Cyclin T1 complex following antigen encounter. We have previously demonstrated that in B cells, Cdk9 interacts in vivo with the E2A gene products E12/E47 (members of the basic helix-loop-helix family) which are involved in differentiation. In this article, we show that this interaction also occurs in T cells. This suggests an active role for the Cdk9/Cyclin T1 complex during lymphoid differentiation, through physical binding with E12 and E47. These preliminary results suggest that the Cdk9/Cyclin T1 complex may be important in the activation and differentiation program of lymphoid cells and that its upregulation, which is due to still unknown mechanisms, may contribute to malignant transformation.