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Caterina Cinti

Publications and source records attributed to Caterina Cinti.

17 recordsLinked to original sources
PubMed2006

Multiple genetic and epigenetic interacting mechanisms contribute to clonally selection of drug-resistant tumors: current views and new therapeutic prospective.

Successful treatment of cancer requires a clear understanding of drug-resistance mechanism. Cancer patient are often treated with standard protocols without considering individual difference in chemosensitivity, whereas the efficacy of anticancer drug varies widely among individual patients. Since chemosensitivity involves multiple interacting factors, it is not sufficient to investigate a single gene or factor to fix chemoresistance. Along with affecting disease progression, the synergism between genetic and epigenetic abnormalities can contribute to convert a sensible tumor cell in a resistant one. Unlike genetic changes, epigenetic changes are potentially reversible. Therefore, treatment with DNA methylation inhibitors can reactivate the expression of genes improperly methylated and can reverse many aspect of cancer phenotype such as drug resistance. The demethylating agents are used in the treatment of several kind of tumor, but toxicity and the potential outcome on the normal methylation patterns have always been concern of researchers and clinicals. It is necessary to create individual chemosensitivity-chemoresistance maps in order to identify the combination of drugs for optimized treatments. An overview on genetic and epigenetic events contributing to clonally selection of chemotherapeutic-resistant tumors is discussed.

Animals↗
PubMed2006

Combined fluorescence in situ hybridization and PRINS for the analysis of the Dystrophin gene.

Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy are caused in most cases by deletions of the DMD gene. These rearrangements are detectable in affected boys and men by a simple multiplex polymerase chain reaction approach. However, this technique is not able to disclose DMD deletions in heterozygous female carriers, and different approaches must be used in these cases. Here, we describe an approach based on the combined use of primed in situ labeling and fluorescence in situ hybridization techniques for the detection of single DMD exons in fixed metaphase chromosomes and interphase nuclei of both male and female subjects, suggesting the usefulness of this tool in the detection of small intragenic deletions of the DMD gene.

Chromosomes, Human↗
PubMed2005

Genetic and epigenetic alterations of RB2/p130 tumor suppressor gene in human sporadic retinoblastoma: implications for pathogenesis and therapeutic approach.

Human retinoblastoma occurs in two forms (familial and sporadic) both due to biallelic mutation of the RB1/p105 gene even if its loss is insufficient for malignancy. We have recently reported that loss of expression of the retinoblastoma-related protein pRb2/p130 correlates with low apoptotic index, suggesting that RB2/p130 gene could be involved in retinoblastoma. Mutational analysis of RB2/p130 in primary tumors showed a tight correlation between Exon 1 mutations and pRb2/p130 expression level in sporadic retinoblastoma. These mutations are located within a CpG-enriched region prone to de novo methylation. Analysis of RB2/p130 methylation status revealed that epigenetic events, most probably consequent to the Exon 1 mutations, determined the observed phenotype. Treatment of Weri-Rb1 cell line by 5-Aza-dC induced an increase in expression level of pRb2/p130, E2F1, p73 and p53. Overall, our results highlight a crucial role of epigenetic events in sporadic retinoblastoma, which opens a perspective for new therapeutic approaches.

Azacitidine↗
PubMed2005

Tumor-specific exon 1 mutations could be the 'hit event' predisposing Rb2/p130 gene to epigenetic silencing in lung cancer.

Genetic alterations in Rb2/p130 gene have been reported in several tumors, but till now there are insufficient and conflicting data linking the loss of pRb2/p130 expression with the mutational status of this gene in lung cancer. We recently reported that loss or lowering of pRb2/p130 expression is mainly due to aberrant Rb2/p130 promoter methylation, in retinoblastoma tumors, and indicated that epigenetic silencing of Rb2/p130 can impair its function to negatively regulate cell cycle progression as well as apoptotic response. In order to clarify Rb2/p130 gene inactivation in lung cancer, we investigated whether epigenetic events could impair the expression of this gene in NSLC. Here, we show that specific Rb2-exon 1 homozygous mutations, occurring in an Rb2/p130, region, rich in CpG dinucleotides, could be the 'hit event' that predispose this gene to epigenetic changes, leading to Rb2/p130 gene silencing in lung cancer. Moreover, these homozygous mutations, found in different tumor histotypes, could represent tumor-specific markers.

Base Sequence↗
PubMed2005

Modulation of cell cycle components by epigenetic and genetic events.

Cell cycle progression is monitored by surveillance mechanisms, or cell cycle checkpoints, that ensure that initiation of a later event is coupled with the completion of an early cell cycle event. Deregulated proliferation is a characteristic feature of tumor cells. Moreover, defects in many of the molecules that regulate the cell cycle have been implicated in cancer formation and progression. Key among these are p53, the retinoblastoma protein (pRb) and its related proteins, p107 and pRb2/p130, and cdk inhibitors (p15, p16, p18, p19, p21, p27), all of which act to keep the cell cycle from progressing until all repairs to damaged DNA have been completed. The pRb (pRb/p16(INK4a)/cyclin D1) and p53 (p14(ARF)/mdm2/p53) pathways are the two main cell-cycle control pathways frequently targeted in tumorigenesis, and the alterations occurring in each pathway depend on the tumor type. Virtually all human tumors deregulate either the pRb or p53 pathway, and oftentimes both pathways simultaneously. This review focuses on the genetic and epigenetic alterations affecting the components of mechanisms regulating the progression of the cell cycle and leading to cancer formation and progression.

Animals↗
PubMed2004

Exposure to 900 MHz electromagnetic field induces an unbalance between pro-apoptotic and pro-survival signals in T-lymphoblastoid leukemia CCRF-CEM cells.

It has been recently established that low-frequency electromagnetic field (EMFs) exposure induces biological changes and could be associated with increased incidence of cancer, while the issue remains unresolved as to whether high-frequency EMFs can have hazardous effect on health. Epidemiological studies on association between childhood cancers, particularly leukemia and brain cancer, and exposure to low- and high-frequency EMF suggested an etiological role of EMFs in inducing adverse health effects. To investigate whether exposure to high-frequency EMFs could affect in vitro cell survival, we cultured acute T-lymphoblastoid leukemia cells (CCRF-CEM) in the presence of unmodulated 900 MHz EMF, generated by a transverse electromagnetic (TEM) cell, at various exposure times. We evaluated the effects of high-frequency EMF on cell growth rate and apoptosis induction, by cell viability (MTT) test, FACS analysis and DNA ladder, and we investigated pro-apoptotic and pro-survival signaling pathways possibly involved as a function of exposure time by Western blot analysis. At short exposure times (2-12 h), unmodulated 900 MHz EMF induced DNA breaks and early activation of both p53-dependent and -independent apoptotic pathways while longer continuous exposure (24-48 h) determined silencing of pro-apoptotic signals and activation of genes involved in both intracellular (Bcl-2) and extracellular (Ras and Akt1) pro-survival signaling. Overall our results indicate that exposure to 900 MHz continuous wave, after inducing an early self-defense response triggered by DNA damage, could confer to the survivor CCRF-CEM cells a further advantage to survive and proliferate.

Apoptosis↗
PubMed2003

Interaction between HIV-1 Tat and pRb2/p130: a possible mechanism in the pathogenesis of AIDS-related neoplasms.

Tat protein is an early nonstructural protein necessary for virus replication, which is secreted by infected cells and taken up by uninfected cells. Extensive evidence indicates that Tat may be a cofactor in the development of AIDS-related neoplasms. The molecular mechanism underlying Tat's oncogenic activity may include deregulation of cellular genes. Among these genes, it has recently been shown that pRb2/p130 oncosuppressor protein is one of the targets in the interaction between HIV gene product Tat and host proteins. However, whether the HIV-1 gene product Tat may inactivate the oncosuppressive function of pRb2/p130 has not yet been elucidated. Here, we show that mRNA levels of pRb2/p130 increase in the presence of Tat, whereas no change in the phosphorylation status of pRb2/p130 is observed. In addition, Tat can inhibit the growth control activity exerted by pRb2/p130 in the T98G cell line. Finally, Tat does not compete with E2F-4 in binding to pRb2/p130. The interaction between Tat and pRb2/p130 seems to result in the deregulation of the control exerted by pRb2/p130 on the cell cycle. Taken together, these results open a window on the role of pRb2/p130 in AIDS-related oncogenesis.

Cell Line↗
PubMed2003

Triggering of p73-dependent apoptosis in osteosarcoma is under the control of E2Fs-pRb2/p130 complexes.

Mechanisms underlying multidrug resistance (MDR), one of the major causes of cancer treatment failure, are still poorly understood. We selected the osteosarcoma MDR HosDXR150 cell line by culturing Hos cells in the presence of increasing doxorubicin doses and showed that it is crossresistant to vinblastine. Similarly to the Hos parental cell line, HosDXR150 cells present mutated p53, functionally inactivated pRb/p105 and wild-type pRb2/p130. Owing to p53 mutation, MDR-1 gene, codifying for P-glycoprotein, is upregulated. Evasion of apoptosis in HosDXR150 cells is only partially explained by drug extrusion because of P-glycoprotein overexpression. Analysis of gene expression level profiles showed that parental cell line undergoes apoptosis through an E2F1/p73-dependent pathway while its resistant variant evades it. This result can be explained by the presence of distinct E2Fs-pRb2/p130 complexes on the p73 promoter. Namely, in Hos p73 transcription is activated by E2F1-Rb2/p130-p300 complexes, while in HosDXR150 it is kept repressed by E2F4-Rb2/p130-HDAC1 complexes.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2003

pRb2/p130-E2F4/5-HDAC1-SUV39H1-p300 and pRb2/p130-E2F4/5-HDAC1-SUV39H1-DNMT1 multimolecular complexes mediate the transcription of estrogen receptor-alpha in breast cancer.

The estrogen receptor-alpha (ER) plays a crucial role in normal breast development and is also linked to development and progression of mammary carcinoma. The transcriptional repression of ER-alpha gene in breast cancer is an area of active investigation with potential clinical significance. However, the molecular mechanisms that regulate the ER-alpha gene expression are not fully understood. Here we show a new molecular mechanism of ER-alpha gene inactivation mediated by pRb2/p130 in ER-negative breast cancer cells. We investigated in vivo occupancy of ER-alpha promoter by pRb2/p130-E2F4/5-HDAC1-SUV39 H1-p300 and pRb2/p130-E2F4/5-HDAC1-SUV39H1-DNMT1 complexes, and provided a link between pRb2/p130 and chromatin-modifying enzymes in the regulation of ER-alpha transcription in a physiological setting. These findings suggest that pRb2/p130-multimolecular complexes can be key elements in the regulation of ER-alpha gene expression and may be viewed as promising targets for the development of novel therapeutic strategies in the treatment of breast cancer, especially for those tumors that are ER negative.

Acetylation↗
PubMed2002

Combined use of PRINS and FISH in the study of the dystrophin gene.

The efficacy of fluorescence in situ hybridization (FISH) may be limited in specific applications by low-resolution sensitivity. Primed in situ labeling (PRINS) is based on specific hybridization of an unlabeled oligonucleotide with a denatured template and synthesis of a single-strand DNA in situ. This method may represent a powerful alternative to FISH for gene mapping because of its ability to generate multiple independent signals within the same gene segment. We investigated the specificity of signals produced by a modified PRINS protocol combining a centromeric probe for the X-chromosome with specific primers for 3'- and 5'-terminal regions of the dystrophin gene. In approximately 70% of nuclei from male and female subjects, we detected one or two large signals (X-chromosome centromere) and two or four smaller signals (the two regions of the dystrophin gene). Specific hybridization of the oligonucleotides on Xp was demonstrated by localization of the smaller (dystrophin) and larger (X-centromere) signals on the same chromosome. Simultaneous hybridization with a centromeric probe and gene-specific oligonucleotides allowed localization of PRINS signals, and assessment of the specificity of the primers used for hybridization. This approach could facilitate identification of female carriers of small intragenic deletions in the dystrophin gene.

Base Sequence↗
PubMed2002

Expression of RB2/p130 tumor-suppressor gene in AIDS-related non-Hodgkin's lymphomas: implications for disease pathogenesis.

In this study we examined 21 cases of AIDS-related lymphomas for genomic organization and expression of RB2/p130 oncosuppressor gene and compared the results with the proliferative features of these neoplasms. We found no mutations in the RB2/p130 gene and unusually high percentages of cells expressing nuclear pRb2/p130 in tumors with a high proliferative activity, such as AIDS-related lymphomas. These findings might suggest that a molecular mechanism usually observed in viral-linked oncogenesis could be involved. We performed in vitro and in vivo binding assays to investigate whether the human immunodeficiency virus (HIV) gene product Tat and Rb2/p130 could interact. The results of these assays revealed that the HIV-1 Tat protein binds specifically to pRb2/p130. This may result in the inactivation of its oncosuppressive properties and the induction of genes needed to proceed through the cell cycle including p107, cyclin A, and cyclin B. Using single-cell polymerase chain reaction (PCR) assay, we found HIV-1 DNA in the neoplastic cells of only 2 of the 21 cases examined, whereas PCR on whole tissue revealed HIV-1 DNA in all of the cases. Furthermore, a diffuse and nuclear stain was observed in tissue sections with anti-Tat monoclonal antibody. These findings are in accordance with the notion that soluble Tat protein could function as a biologically active extracellular protein released by infected cells and taken up readily by uninfected B cells. In conclusion, our results seem to suggest that pRb2/p130 oncosuppressor protein may be a target in the interaction between the HIV-1 gene products and host proteins.

Adult↗
PubMed2002

Immunoglobulin gene rearrangement analysis in composite hodgkin disease and large B-cell lymphoma: evidence for receptor revision of immunoglobulin heavy chain variable region genes in Hodgkin-Reed-Sternberg cells?

Immunoglobulin heavy chain gene (IgH) rearrangement was studied in a patient showing the occurrence of classical Hodgkin disease and large B-cell lymphoma (LBCL) in the same lymph node. The VHDHJH region was amplified by polymerase chain reaction, the template being the DNA extracted from single Hodgkin and Reed-Sternberg and LBCL cells, microdissected on hematoxylin-eosin-stained sections by laser capture. A repeated VH4DH3JH4 segment was found in Reed-Sternberg cells, whereas a repeated VH3DH3JH4 segment was observed in LBCL cells. Rearranged VH genes carried somatic mutations in both populations, indicating a common germinal center cell origin. The IgH rearrangement found in clonally related Reed-Sternberg cells differed from the one of LBCL cells in the VH region but showed the same JH and DH segments with no variation from the respective germline sequence. The DH-JH junction is the first immunoglobulin gene segment rearranged in precursor B cells. Because the possibility of secondary Ig gene rearrangement in peripheral lymphoid organs has recently been reported, in the patient described here Reed-Sternberg and LBCL cells might originate from a common precursor in which secondary VH replacement took place during the germinal center reaction, giving rise to two different clonally related lymphomas.

Adult↗
PubMed2002

Missing expression of pRb2/p130 in human retinoblastomas is associated with reduced apoptosis and lesser differentiation.

PURPOSE: Although the retinoblastoma gene (RB/p105) has been intensely investigated as a prototype suppressor gene in humans, mutational data on the Rb family member pRb2/p130 (p130) has only recently been reported. A protective role against apoptosis has been suggested for pRb/p105, both in vitro and in vivo. However, only limited information is available on the role of pRb2/p130 in controlling apoptosis. The purpose of this study was to determine the extent of a role of this gene in the neoplasms that give the Rb family its name. METHODS: Forty-two human retinoblastomas were retrospectively examined by immunohistochemical labeling of the Rb-related proteins and the results compared with cellular kinetic characteristics: the apoptotic index (AI) and the mitotic index (MI). RESULTS: The retinoblastomas that did not express p130 showed a significantly lower AI than those that expressed p130. This result was also supported by flow cytometry on a human Saos-2 cell line that was transiently transfected with RB2/p130. The p130(-) tumors displayed a lesser degree of differentiation than the p130(+) ones. CONCLUSIONS: These observations give evidence that expression of p130 is inversely correlated with higher rates of apoptosis in human retinoblastomas and give an additional example of this regulator's role in cellular differentiation.

Apoptosis↗