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Biomedical subjects

A Giordano

Publications and source records attributed to A Giordano.

At least 19 recordsLinked to original sources
PubMed2006

A small molecule based on the pRb2/p130 spacer domain leads to inhibition of cdk2 activity, cell cycle arrest and tumor growth reduction in vivo.

One strategy in the development of anticancer therapeutics has been to arrest malignant proliferation through inhibition of the enzymatic activity of cyclin-dependent kinases (cdks), which are key regulatory molecules of the cell cycle. Over the past few years, numerous compounds with remarkable cdk inhibitory activity have been studied in cancer therapy, although it is very difficult to point out the best cdk to target. An excellent candidate appears to be cdk2, whose alteration is a pathogenic hallmark of tumorigenesis. The small molecule described in our study showed an inhibitory effect on the kinase activity of cdk2, a significant growth arrest observed in a colony formation assay and a reduction in the size of the tumor in nude mice, thus suggesting its potential role as a promising new type of mechanism-based antitumor drug, also for the treatment of hyperproliferative disorders.

3T3 Cells↗
PubMed2006

pRb2/p130: a new candidate for retinoblastoma tumor formation.

Retinoblastoma is the most common primary intraocular tumor in childhood. Mutations in both the alleles of the RB1 gene represent the causative agent for the tumor to occur. It is becoming evident that, although these alterations represent key events in the genesis of retinoblastoma, they are not sufficient per se for the tumor to develop, and other additional genetic or epigenetic alterations must occur. A supportive role in the genesis of retinoblastoma has recently been proposed for the RB1-related gene RB2/p130. Additionally, several other genetic alterations involving different chromosomes have been described as relevant in the tumorigenic process. In this review we will analyse current knowledge about the molecular mechanisms involved in retinoblastoma, paying particular attention to the mechanisms of inactivation of the biological function of the retinoblastoma family of proteins.

Cell Cycle↗
PubMed2006

RB and cell cycle progression.

The Rb protein is a tumor suppressor, which plays a pivotal role in the negative control of the cell cycle and in tumor progression. It has been shown that Rb protein (pRb) is responsible for a major G1 checkpoint, blocking S-phase entry and cell growth. The retinoblastoma family includes three members, Rb/p105, p107 and Rb2/p130, collectively referred to as 'pocket proteins'. The pRb protein represses gene transcription, required for transition from G1 to S phase, by directly binding to the transactivation domain of E2F and by binding to the promoter of these genes as a complex with E2F. pRb represses transcription also by remodeling chromatin structure through interaction with proteins such as hBRM, BRG1, HDAC1 and SUV39H1, which are involved in nucleosome remodeling, histone acetylation/deacetylation and methylation, respectively. Loss of pRb functions may induce cell cycle deregulation and so lead to a malignant phenotype. Gene inactivation of pRB through chromosomal mutations is one of the principal reasons for retinoblastoma tumor development. Functional inactivation of pRb by viral oncoprotein binding is also shown in many neoplasias such as cervical cancer, mesothelioma and AIDS-related Burkitt's lymphoma.

Cell Cycle↗
PubMed2006

Rb family proteins as modulators of gene expression and new aspects regarding the interaction with chromatin remodeling enzymes.

The pRb family proteins (pRb1/105, p107, pRb2/p130), collectively referred to as pocket proteins, are believed to function primarily as regulators of the mammalian cell cycle progression, and suppressors of cellular growth and proliferation. In addition, different studies suggest that these pocket proteins are also involved in development and differentiation of various tissues. Several lines of evidence indicate that generally pRb-family proteins function through their effect on the transcription of E2F-regulated genes. In fact, each of Rb family proteins binds to distinct members of the E2F transcription factors, which regulate the expression of genes whose protein products are necessary for cell proliferation and to drive cell-cycle progression. Nevertheless, pocket proteins can affect the G1/S transition through E2F-independent mechanisms. More recently, a broad range of evidences indicate that pRb-family proteins associate with a wide variety of transcription factors and chromatin remodeling enzymes forming transcriptional repressor complexes that control gene expression. This review focuses on the complex regulatory mechanisms by which pRb-family proteins tell genes when to switch on and off.

Animals↗
PubMed2006

Role of the interaction between large T antigen and Rb family members in the oncogenicity of JC virus.

Human polyomaviruses (JC virus, BK virus and simian virus 40) are causative agents of some human diseases and, interestingly, are involved in processes of cell transformation and oncogenesis. These viruses need the cell cycle machinery of the host cell to complete their replication; so they evolved mechanisms that can interfere with the growth control of infected cells and force them into DNA replication. The retinoblastoma family of proteins (pRb), which includes pRb/p105, p107 and pRb2/p130, acts as one of the most important regulators of the G1/S transition of the cell cycle. Rb proteins represent an important target for viral oncoproteins. Early viral T antigens can bind all members of the pRb family, promoting the activation of the E2F family of transcription factors, thus inducing the expression of genes required for the entry to the S phase. The interaction between early viral antigens and cell cycle regulators represents an important mechanism through which viruses deregulate cell cycle and lead to cell transformation. In this review, we will discuss the effects of the interaction between large T antigen and Rb proteins in JC virus-mediated oncogenesis.

Antigens, Polyomavirus Transforming↗
PubMed2006

The retinoblastoma gene is involved in multiple aspects of stem cell biology.

Genetic programs controlling self-renewal and multipotentiality of stem cells have overlapping pathways with cell cycle regulation. Components of cell cycle machinery can play a key role in regulating stem cell self-renewal, proliferation, differentiation and aging. Among the negative regulators of cell cycle progression, the RB family members play a prominent role in controlling several aspects of stem cell biology. Stem cells contribute to tissue homeostasis and must have molecular mechanisms that prevent senescence and hold 'stemness'. RB can induce senescence-associated changes in gene expression and its activity is downregulated in stem cells to preserve self-renewal. Several reports evidenced that RB could play a role in lineage specification of several types of stem cells. RB has a role in myogenesis as well as in cardiogenesis. These effects are not only related to its role in suppressing E2F-responsive genes but also to its ability to modulate the activity of tissue-specific transcription factors. RB is also involved in adipogenesis through a strict control of lineage commitment and differentiation of adipocytes as well in determining the switch between brown and white adipocytes. Also, hematopoietic progenitor cells utilize the RB pathway to modulate cell commitment and differentiation. In this review, we will also discuss the role of the other two RB family members: Rb2/p130 and p107 showing that they have both specific and overlapping functions with RB gene.

Animals↗
PubMed2006

The effects of HIV-1 Tat protein on cell cycle during cervical carcinogenesis.

The role of HPV in the carcinogenesis of intraepithelial and invasive anogenital lesions is currently well established. E6 and E7 oncoproteins of high-risk HPV genotypes are known to inactivate p53 and pRb pathways. Several studies have described an increased prevalence and recurrence of both cervical HPV infection and invasive cervical cancer among HIV-1 positive women compared to HIV-1 negative cases. For these reasons, cervical cancer is considered an AIDS-defining neoplasm. Unlike other AIDS-associated neoplasms, the occurrence of cervical cancer is independent of immune suppression. HIV-1 infection in patients with high grade precancerous lesions and invasive cervical cancers results in a therapy refractory and more aggressive disease phenotype, which is not yet well understood at the molecular level. An upregulation of HPV E6 and E7 gene expressions by HIV-1 proteins such as Tat has been documented by some authors. However, the role of HIV-1 in cervical carcinomas is still unclear. It is already known that HIV-1 Tat protein is able to influence cell cycle progression. Altogether, these facts led us to investigate the effects of Tat on the expression of cell cycle regulator genes. After transfection of HeLa cells with Tat, we analyzed the expression of cell cycle regulators from these cells by IHC and Real-time PCR. A significant reduction in the expression of cell cycle inhibitors of transcription and an increase in the levels of proliferation markers were observed. These results suggest that HIV-1 may enhance cervical carcinogenesis by promoting cell cycle progression. We also found that this HIV-1 Tat-induced cell proliferation was not dependent on the E2F family of transcription factors, and therefore postulate that Sp factors may be involved.

Cell Cycle↗
PubMed2006

Cytoplasmic and nuclear interaction between Rb family proteins and PAI-2: a physiological crosstalk in human corneal and conjunctival epithelial cells.

Extracellular plasminogen activator inhibitor type-2 (PAI-2) is a potent inhibitor of urokinase-type plasminogen activator (u-PA) and also acts as a multifunctional protein. However, the biological activity of intracellular PAI-2, as well as its intracellular targets, until now remain an enigma. Here, we show that pRb2/p130 and Rb1/p105, but not p107, interact with PAI-2 in both the cytoplasm and nucleus of normal primary human corneal and conjunctival epithelial cells. We provided the first in vivo evidence that a specific fragment of the PAI-2 promoter is bound simultaneously by pRb2/ p130, PAI-2, E2F5, histone deacetylase 1 (HDAC1), DNA methyltransferase 1 (DNMT1), and histone methyltransferase (SUV39H1), in normal primary human corneal epithelial cells, and by pRb2/p130, PAI-2, E2F5, HDAC1, and DNMT1, in normal primary human conjunctiva epithelial cells. Our results strongly indicate a physiological interaction between pRb family members and PAI-2, suggesting the hypothesis that pRb2/p130 and PAI-2 may cooperate in modulating PAI-2 gene expression by chromatin remodeling, in normal corneal and conjunctival cells.

Cell Nucleus↗
PubMed2006

Stem cells and brain cancer.

An increasing body of research is showing that cancers might contain their own stem cells. In fact, cancer cells, like stem cells, can proliferate indefinitely through a deregulated cellular self-renewal capacity. This raises the possibility that some features of tumor cells may be due to cancer stem cells. Stem cell-like cancer cells were isolated from several solid tumors. Now, evidence has shown that brain cancers, such as glioblastomas, medulloblastomas and astrocytomas, also contain cells that may be multipotent neural stem cell-like cells. In this review, we discuss the results of these studies, along with the molecular pathways that could be involved in cancer stem cell physiopathology.

Animals↗
PubMed2006

Nuclear and cytoplasmic interaction of pRb2/p130 and ER-beta in MCF-7 breast cancer cells.

Estrogens exhibit important biological functions and influence several pathological processes of hormone-dependent diseases. The biological actions of estrogens require their interaction with two estrogen receptors (ER-alpha and ER-beta), which are ligand-dependent transcription factors. ER-alpha and ER-beta exhibit distinct tissue expression patterns as well as show different patterns of gene regulation. In addition, it has been suggested that ER-beta works as a counter partner of ER-alpha through inhibition of the transactivating functions of ER-alpha. For instance, ER-beta seems to play a different role in breast tumorigenesis than ER-alpha, as ER-beta decreased expression in breast cancer has been correlated with bad prognosis. Biological activities of ER-alpha and ER-beta could be controlled by a number of interacting proteins such as activators/inhibitors, ligand binding and kinases. We have previously reported that pRb2/p130, retinoblastoma related protein, could be involved in the silencing of ER-alpha gene during breast tumorigenesis. Here, we report that ER-beta and pRb2/p130 proteins co-immunoprecipitate in both nucleus and cytoplasm of MCF-7 breast cancer cells. Our hypothesis is that the interaction of pRb2/130 with ER-beta may have a functional significance in regulating ER-beta activity.

Amino Acid Sequence↗
PubMed2006

A pilot study of nurse-led, home monitoring for patients with chronic respiratory failure and with mechanical ventilation assistance.

We assessed the feasibility of telemedicine for home monitoring of 45 patients with chronic respiratory failure (CRF) discharged from hospital. The patients transmitted pulsed arterial saturation (pSat) data via a telephone modem to a receiving station where a nurse was available for a teleconsultation. A respiratory physician was also available. Scheduled and ad hoc appointments were conducted. Thirty-five patients were on home mechanical ventilation, 13 with invasive and 22 with non-invasive devices. The main diagnosis was chronic obstructive pulmonary disease (COPD). The follow-up period was 176 days (SD 69). In all, 376 calls for scheduled consultations were received and 83 ad hoc consultations were requested by the patients. The actions taken were: 55 therapy modifications, 19 hospitalizations in a respiratory department for decompensated CRF, three hospitalizations in an intensive care unit (ICU), 22 requests for further investigations, 25 contacts with the general practitioner (GP), 66 demands for respiratory consultations and 10 calls for the emergency department. The mean time recorded for the 459 calls was 16 min/patient/week. In 82% of calls, a pSat recording was received successfully. The nurse time required to train the users in the operation of the pSat instrument was high (mean time 30 min). However, the results showed that home monitoring was feasible, and useful for titration of oxygen, mechanical ventilation setting and stabilization of relapses.

Chronic Disease↗
PubMed2005

Identification of respiratory isolates of Stenotrophomonas maltophilia by commercial biochemical systems and species-specific PCR.

One hundred strains of Stenotrophomonas maltophilia isolates from respiratory specimens were biochemically identified using the API 20NE strip and the VITEK2 ID-GNB card. The identification was confirmed by a species-specific PCR using two primers specific for the 23S rRNA gene. The API 20NE showed only 1 strain with "low discrimination" whereas the VITEK2 gave 12. In any case, the two biochemical systems showed good reliability compared to SS-PCR.

Bacteriological Techniques↗
PubMed2005

The human polyomavirus BK: Potential role in cancer.

In human cancer, a role has been suggested for the human polyomavirus BK, primarily associated with tubulointerstitial nephritis and ureteric stenosis in renal transplant recipients, and with hemorrhagic cystitis in bone marrow transplant (BMT) recipients. After the initial infection, primarily unapparent and without clinical signs, the virus disseminates and establishes a persistent infection in the urinary tract and lymphocytes. There is correlative evidence regarding potential role of polyomavirus BK in cancer. In fact, the BK virus (BKV) DNA (complete genome and/or subgenomic fragments containing the early region) is able to transform embryonic fibroblasts and cells cultured from kidney and brain of hamster, mouse, rat, rabbit, and monkey. Nevertheless, transformation of human cells by BKV is inefficient and often abortive. Evidence supporting a possible role for BKV in human cancer has accumulated slowly in recent years, after the advent of polymerase chain reaction (PCR). BKV is known to commonly establish persistent infections in people and to be excreted in the urine by individuals who are asymptomatic, complicating the evaluation of its potential role in development of human cancer. Therefore, there is no certain proof that human polyomavirus BK directly causes the cancer in humans or acts as a cofactor in the pathogenesis of some types of human cancer.

Animals↗
PubMed2005

Investigation on the role of cell transcriptional factor Sp1 and HIV-1 TAT protein in PML onset or development.

JC virus (JCV) causes progressive multifocal leukoencephalopathy (PML), characterized by multiple areas of demyelination and attendant loss of brain function. PML is often associated with immunodepression and it is significantly frequent in AIDS patients. The viral genome is divided into early and late genes, between which lies a non-coding control region (NCCR) that regulates JCV replication and presents a great genetic variability. The NCCR of JCV archetype (CY strain) is divided into six regions: A-F containing binding sites for cell factors involved in viral transcription. Deletions and enhancements of these binding sites characterize JCV variants, which could promote viral gene expression and could be more suitable for the onset or development of PML. Therefore, we evaluated by means of polymerase chain reaction (PCR) the presence of JCV genome in cerebrospinal fluid (CSF) of HIV positive and negative subjects both with PML and after sequencing, we analyzed the viral variants found focusing on Sp1 binding sites (box B and D) and up-TAR sequence (box C). It is known that Sp1 activates JCV early promoter and can contribute in maintaining methylation-free CpG islands in active genes, while up-TAR sequence is important for HIV-1 Tat stimulation of JCV late promoter. Our results showed that in HIV-positive subjects all NCCR structures presented enhancements of up-TAR element, whereas in HIV-negative subjects both Sp1 binding sites were always retained. Therefore, we can support the synergism HIV-1/JCV in CNS and we can hypothesize that both Sp1 binding sites could be important to complete JCV replication cycle in absence of HIV-coinfection.

Adult↗
PubMed2005

RB and RB2/p130 genes demonstrate both specific and overlapping functions during the early steps of in vitro neural differentiation of marrow stromal stem cells.

Marrow stromal stem cells (MSCs) are stem-like cells that are currently being tested for their potential use in cell therapy for a number of human diseases. MSCs can differentiate into both mesenchymal and nonmesenchymal lineages. In fact, in addition to bone, cartilage and fat, it has been demonstrated that MSCs are capable of differentiating into neurons and astrocytes. RB and RB2/p130 genes are involved in the differentiation of several systems. For this reason, we evaluated the role of RB and RB2/p130 in the differentiation and apoptosis of MSCs under experimental conditions that allow for MSC differentiation toward the neuron-like phenotype. To this end, we ectopically expressed either RB or RB2/p130 and monitored proliferation, differentiation and apoptosis in rat primary MSC cultures induced to differentiate toward the neuron-like phenotype. Both RB and RB2/P130 decreased cell proliferation rate. In pRb-overexpressing cells, the arrest of cell growth was also observed in the presence of the HDAC-inhibitor TSA, suggesting that its antiproliferative activity does not rely upon the HDAC pathway, while the addition of TSA to pRb2/p130-overexpressing cells relieved growth inhibition. TUNEL reactions and studies on the expression of genes belonging to the Bcl-2 family showed that while RB protected differentiating MSCs from apoptosis, RB2/p130 induced an increase of apoptosis compared to controls. The effects of both RB and RB2/p130 on programmed cell death appeared to be HDAC- independent. Molecular analysis of neural differentiation markers and immunocytochemistry revealed that RB2/p130 contributes mainly to the induction of generic neural properties and RB triggers cholinergic differentiation. Moreover, the differentiation potentials of RB2/p130 and RB appear to rely, at least in part, on the activity of HDACs.

Acetylcholinesterase↗