Biomedical subjects

Teresa Druck

Publications and source records attributed to Teresa Druck.

11 recordsLinked to original sources

PubMed2007

Epigenetic modulation of endogenous tumor suppressor expression in lung cancer xenografts suppresses tumorigenicity.

Epigenetic changes involved in cancer development, unlike genetic changes, are reversible. DNA methyltransferase and histone deacetylase inhibitors show antiproliferative effects in vitro, through tumor suppressor reactivation and induction of apoptosis. Such inhibitors have shown activity in the treatment of hematologic disorders but there is little data concerning their effectiveness in treatment of solid tumors. FHIT, WWOX and other tumor suppressor genes are frequently epigenetically inactivated in lung cancers. Lung cancer cell clones carrying conditional FHIT or WWOX transgenes showed significant suppression of xenograft tumor growth after induction of expression of the FHIT or WWOX transgene, suggesting that treatments to restore endogenous Fhit and Wwox expression in lung cancers would result in decreased tumorigenicity. H1299 lung cancer cells, lacking Fhit, Wwox, p16(INK4a) and Rassf1a expression due to epigenetic modifications, were used to assess efficacy of epigenetically targeted protocols in suppressing growth of lung tumors, by injection of 5-aza-2-deoxycytidine (AZA) and trichostatin A (TSA) in nude mice with established H1299 tumors. High doses of intraperitoneal AZA/TSA suppressed growth of small tumors but did not affect large tumors (200 mm(3)); lower AZA doses, administered intraperitoneally or intratumorally, suppressed growth of small tumors without apparent toxicity. Responding tumors showed restoration of Fhit, Wwox, p16(INKa), Rassf1a expression, low mitotic activity, high apoptotic fraction and activation of caspase 3. These preclinical studies show the therapeutic potential of restoration of tumor suppressor expression through epigenetic modulation and the promise of re-expressed tumor suppressors as markers and effectors of the responses.

Acid Anhydride Hydrolases↗

PubMed2007

Inhibition of breast cancer cell growth in vitro and in vivo: effect of restoration of Wwox expression.

PURPOSE: The WWOX gene is down-regulated in breast cancer and loss of Wwox expression correlates with important clinical features of breast cancer. Thus, we have examined the effect of restoration of Wwox expression in breast cancer-derived cells. EXPERIMENTAL DESIGN: Wwox protein expression was restored by the following: (a) infection with a recombinant adenovirus carrying WWOX cDNA (Ad-WWOX) or (b) treatment with the DNA methyltransferase inhibitor, 5-aza-2'-deoxycytidine, to activate the endogenous WWOX gene, in breast cancer-derived cells in vitro and in vivo. RESULTS: Restoration of Wwox expression led to suppression of growth of Wwox-deficient breast cancer-derived cells, through activation of the intrinsic caspase pathway, but did not affect growth of Wwox-sufficient MCF7 cells. Intratumoral Wwox restoration, through Ad-WWOX infection or endogenous Wwox reactivation by 5-aza-2'-deoxycytidine injection, suppressed tumor growth in nude mice by inducing apoptosis. Alteration of global methylation levels was not observed. CONCLUSIONS: The results confirm that overexpression of exogenous Wwox inhibits breast cancer cell growth in vitro and in vivo and, perhaps more importantly, shows that restoration of endogenous Wwox expression, and likely other proteins, by treatment with a de novo methyltransferase inhibitor, also inhibits breast cancer cell growth and reverses breast cancer xenograft growth.

Adenoviridae↗

PubMed2006

Fhit modulates the DNA damage checkpoint response.

In preneoplastic lesions, the DNA damage checkpoint is induced and loss of heterozygosity at the FRA3B/FHIT common chromosome fragile region precedes or is coincident with activation of the checkpoint response in these early stages. Introduction of exogenous Fhit into cells in vitro led to modulation of expression of checkpoint proteins Hus1 and Chk1 at mid-S checkpoint, a modulation that led to induction of apoptosis in esophageal cancer cells but not in noncancerous primary cultures. Mutation of the conserved Fhit tyrosine 114 resulted in failure of this function, confirming the importance of this residue. The results suggest that the DNA damage-susceptible FRA3B/FHIT chromosome fragile region, paradoxically, encodes a protein that is necessary for protecting cells from accumulation of DNA damage through its role in modulation of checkpoint proteins, and inactivation of Fhit contributes to accumulation of abnormal checkpoint phenotypes in cancer development.

Acid Anhydride Hydrolases↗

PubMed2006

Biological functions of mammalian Nit1, the counterpart of the invertebrate NitFhit Rosetta stone protein, a possible tumor suppressor.

The "Rosetta Stone" hypothesis proposes that the existence of a fusion protein in some organisms predicts that the separate polypeptides function in the same biochemical pathway in other organisms and may physically interact. In Drosophila melanogaster and Caenorhabditis elegans, NitFhit protein is composed of two domains, a fragile histidine triad homolog and a bacterial and plant nitrilase homolog. We assessed the biological effects of mammalian Nit1 expression in comparison with Fhit and observed that: 1) Nit1 expression was observed in most normal tissues and overlapped partially with Fhit expression; 2) Nit1-deficient mouse kidney cells exhibited accelerated proliferation, resistance to DNA damage stress, and increased cyclin D1 expression; 3) cyclin D1 was up-regulated in Nit1 null mammary gland and skin; 4) Nit1 overexpression induced caspase-dependent apoptosis in vitro; and 5) Nit1 allele deficiency led to increased incidence of N-nitrosomethylbenzylamine-induced murine forestomach tumors. Thus, the biological effects of Nit1 expression are similar to Fhit effects. Adenoviruses carrying recombinant NIT1 and FHIT induced apoptosis in Fhit- and Nit1-deficient cells, respectively, suggesting that Nit1-Fhit interaction is not essential for function of either protein. The results suggest that Nit1 and Fhit share tumor suppressor signaling pathways, while localization of the NIT1 gene at a stable, rather than fragile, chromosome site explains the paucity of gene alterations and in frequent loss of expression of the NIT1 gene in human malignancies.

Acid Anhydride Hydrolases↗

PubMed2006

A role for the WWOX gene in prostate cancer.

Expression of the WWOX gene, encompassing the common chromosome fragile site FRA16D, is altered in a large fraction of cancers of various types, including prostate cancer. We have examined expression and biological functions of WWOX in prostate cancer. WWOX mRNA and protein expression were significantly reduced in prostate cancer-derived cells (LNCaP, DU145, and PC-3) compared with noncancer prostate cells (PWR-1E), and WWOX expression was reduced in 84% of prostate cancers, as assessed by immunohistochemical staining. Down-modulation of WWOX expression in the prostate cancer-derived cells is due to DNA hypermethylation in the WWOX regulatory region. Treatment with 5-aza-2'-deoxycytidine (AZA), a DNA methyltransferase inhibitor, and trichostatin A, a histone deacetylase inhibitor, led to increased WWOX mRNA and protein expression in prostate cancer-derived cells, most strikingly in DU145 cells. Transfection-mediated WWOX overexpression in DU145 cells suppressed colony growth (P = 0.0012), and WWOX overexpression by infection with Ad-WWOX virus induced apoptosis through a caspase-dependent mechanism and suppressed cell growth. Lastly, ectopic expression of WWOX by Ad-WWOX infection suppressed tumorigenicity of xenografts in nude mice, and intratumoral AZA treatment halted tumor growth. The data are consistent with a role for WWOX as a prostate cancer tumor suppressor and suggest that WWOX signal pathways should be further investigated in normal and cancerous prostate cells and tissues.

Adenoviridae↗

PubMed2005

Roles of FHIT and WWOX fragile genes in cancer.

It was hypothesized as early as 1986, that the recently discovered common fragile sites could facilitate recombination events, such as deletions and translocations, that result in clonally expanded cancer cell populations with specific chromosome alterations in specific cancer types. A natural extension of this hypothesis is that the clonal expansion must be driven by alteration of genes at recombination breakpoints whose altered functions actually drive clonal expansion. Nevertheless, when the FHIT gene was discovered at FRA3B, the most active common chromosome fragile region, and proposed as an example of a tumor suppressor gene altered by chromosome translocations and deletions, a wave of reports suggested that the FHIT gene was altered in cancer simply because it was in a fragile region and not because it had contributed to the clonal expansion, thus turning the original hypothesis upside down. Now, after nearly ten years and more than 500 FHIT reports, it is apparent that FHIT is an important tumor suppressor gene and that there are genes at other fragile regions that contribute significantly to development of cancer. A second fragile gene with a demonstrated role in cancer development is the WWOX gene on chromosome 16q; alterations to the WWOX gene contribute to development of hormone responsive and other cancers. Results of our recent studies of these two fragile tumor suppressor genes were summarized at the first Fragilome meeting in Heidelberg, Feb. 2005.

Acid Anhydride Hydrolases↗

PubMed2005

Fragile genes as biomarkers: epigenetic control of WWOX and FHIT in lung, breast and bladder cancer.

This study aimed to (a) determine if DNA methylation is a mechanism of WWOX (WW domain containing oxidoreductase) and FHIT (fragile histidine triad) inactivation in lung, breast and bladder cancers; (b) examine distinct methylation patterns in neoplastic and adjacent tissues and (c) seek correlation of methylation patterns with disease status. Protein expression was detected by immunohistochemistry, and methylation status by methylation-specific PCR (MSP) and sequencing, in lung squamous cell carcinomas and adjacent tissues, invasive breast carcinomas, adjacent tissues and normal mammary tissues and bladder transitional cell carcinomas. Wwox and Fhit expression was reduced in cancers in association with hypermethylation. Differential patterns of WWOX and FHIT methylation were observed in neoplastic vs adjacent non-neoplastic tissues, suggesting that targeted MSP amplification could be useful in following treatment or prevention protocols. WWOX promoter MSP differentiates DNA of lung cancer from DNA of adjacent lung tissue. WWOX and FHIT promoter methylation is detected in tissue adjacent to breast cancer and WWOX exon 1 MSP distinguishes breast cancer DNA from DNA of adjacent and normal tissue. Differential methylation in cancerous vs adjacent tissues suggests that WWOX and FHIT hypermethylation analyses could enrich a panel of DNA methylation markers.

Acid Anhydride Hydrolases↗

PubMed2004

CpG methylation in the Fhit regulatory region: relation to Fhit expression in murine tumors.

To determine if: (1) 5' CpG island methylation is related to Fhit inactivation; (2) there are tumor or carcinogen-specific methylation patterns, we examined 35 CpG sites in the promoter, exon and intron 1 of the mouse Fhit gene. In primary tumors of lung, urinary bladder and tongue, induced by different carcinogens, 15-35% of sites were methylated, with specific methylation patterns associated with each cancer type, suggesting cancer- or tissue-specific methylation patterns. The methylation patterns were associated with reduced Fhit expression, as determined by immunohistochemical analyses. Methylation of rat Fhit 5' CpGs in mammary adenocarcinomas, detected by methylation specific PCR amplification, also correlated with reduced gene expression. Thus, there was an overall association between promoter/exon 1 methylation and decreased Fhit expression. In contrast, in cancer-derived cell lines 70-95% of the CpG sites were methylated. This is the first detailed study of the relationship between Fhit 5' CpG island methylation and Fhit expression in murine tumors, our main models for preclinical cancer studies, and provides evidence that loss of Fhit expression and methylation are correlated in these mouse models and these models will be useful to examine the complex relationships among gene expression, methylation patterns and organ specificity.

Acid Anhydride Hydrolases↗

PubMed2004

Functional association between Wwox tumor suppressor protein and p73, a p53 homolog.

The WWOX gene is a recently cloned tumor suppressor gene that spans the FRA16D fragile region. Wwox protein contains two WW domains that are generally known to mediate protein-protein interaction. Here we show that Wwox physically interacts via its first WW domain with the p53 homolog, p73. The tyrosine kinase, Src, phosphorylates Wwox at tyrosine 33 in the first WW domain and enhances its binding to p73. Our results further demonstrate that Wwox expression triggers redistribution of nuclear p73 to the cytoplasm and, hence, suppresses its transcriptional activity. In addition, we show that cytoplasmic p73 contributes to the proapoptotic activity of Wwox. Our findings reveal a functional cross-talk between p73 and Wwox tumor suppressor protein.

Cell Line↗

PubMed2003

Candidate tumor suppressor genes at FRA7G are coamplified with MET and do not suppress malignancy in a gastric cancer.

Common fragile sites predispose to specific chromosomal breakage associated with deletion, amplification, and/or translocation in certain forms of cancer. Chromosomal fragile sites not only are susceptible to DNA instability in cancer cells, but may also be associated with genes that contribute to the neoplastic process. FRA7G is a common fragile site containing the candidate tumor suppressor genes CAV1, CAV2, and TESTIN (TES). The human gastric cancer cell line GTL-16 has an amplification of this genomic region and was used to seek evidence for the suppressor candidacy of one of these genes. Our results demonstrate that CAV1, CAV2, and TESTIN are coamplified with the MET oncogene and overexpressed in GTL-16. Somatic mutation was not detected in the coding regions of these genes, although they were each overexpressed. The results show that CAV1, CAV2, and TESTIN are not tumor suppressor genes in this gastric cancer.

Chromosome Fragility↗

PubMed2003

Expression of FRA16D/WWOX and FRA3B/FHIT genes in hematopoietic malignancies.

The WW domain containing oxidoreductase (WWOX) gene was recently identified as a candidate tumor suppressor gene at a common fragile site, FRA16D. Because the fragile histidine triad (FHIT) gene, a tumor suppressor gene encompassing the most active, common fragile site FRA3B, is frequently deleted in various cancers, we evaluated the expression of WWOX and FHIT in 74 cases of primary hematopoietic neoplasias and 20 leukemia cell lines. Aberration or absence of WWOX transcripts was detected in 51% of the primary cases and 55% of cell lines, and three WWOX nucleotide variants were detected among the leukemia cell lines. FHIT expression was absent or altered in 36% of the primary cases and 15% of cell lines. The occurrence of aberrant FHIT reverse transcription-PCR products correlated significantly with the occurrence of WWOX alterations. Wild-type transcripts of both genes were expressed in normal hematopoiesis along with a small fraction of short transcripts. A DNA blot study showed that WWOX and FHIT genes were deleted in 2 of 18 cases with primary acute leukemias; both genes were not expressed in the 2 cases. Furthermore, treatment of cells with a demethylating or histone acetylating agent in culture resulted in increased expression of WWOX and FHIT mRNA in leukemia cells. Conclusions are that WWOX expression is frequently altered or absent in hematopoietic disorders, often in association with FHIT alterations, and that alterations of these fragile genes may result not only from genomic deletions but also from epigenetic modifications associated with expression of fragility.

Acetylation↗