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Biomedical subjects

S A Stass

Publications and source records attributed to S A Stass.

At least 19 recordsLinked to original sources
PubMed2006

Identification of putative oncogenes in lung adenocarcinoma by a comprehensive functional genomic approach.

Amplification and overexpression of putative oncogenes confer growth advantages for tumor development. We used a functional genomic approach that integrated simultaneous genomic and transcript microarray, proteomics, and tissue microarray analyses to directly identify putative oncogenes in lung adenocarcinoma. We first identified 183 genes with increases in both genomic copy number and transcript in six lung adenocarcinoma cell lines. Next, we used two-dimensional polyacrylamide gel electrophoresis and mass spectrometry to identify 42 proteins that were overexpressed in the cancer cells relative to normal cells. Comparing the 183 genes with the 42 proteins, we identified four genes - PRDX1, EEF1A2, CALR, and KCIP-1 - in which elevated protein expression correlated with both increased DNA copy number and increased transcript levels (all r > 0.84, two-sided P < 0.05). These findings were validated by Southern, Northern, and Western blotting. Specific inhibition of EEF1A2 and KCIP-1 expression with siRNA in the four cell lines tested suppressed proliferation and induced apoptosis. Parallel fluorescence in situ hybridization and immunohistochemical analyses of EEF1A2 and KCIP-1 in tissue microarrays from patients with lung adenocarcinoma showed that gene amplification was associated with high protein expression for both genes and that protein overexpression was related to tumor grade, disease stage, Ki-67 expression, and a shorter survival of patients. The amplification of EEF1A2 and KCIP-1 and the presence of overexpressed protein in tumor samples strongly suggest that these genes could be oncogenes and hence potential targets for diagnosis and therapy in lung adenocarcinoma.

Adenocarcinoma↗
PubMed2001

Branched co-polymers of histidine and lysine are efficient carriers of plasmids.

We previously determined that a linear co-polymer of histidine and lysine (HK) in combination with liposomes enhanced the transfection efficiency of cationic liposomes. In the current study, we designed a series of HK polymers with increased branching and/or histidine/lysine ratio to determine if either variable affects transfection efficiency. In the presence of liposomes, the branched polymer with the highest number of histidines, HHK4b, was the most effective at enhancing gene expression. Furthermore, when serum was added to the medium during transfection, the combination of HHK4b and liposomes as a gene-delivery vehicle increased luciferase expression 400-fold compared to liposomes alone. In contrast to linear HK polymers, the higher branched HHK polymers were effective carriers of plasmids in the absence of liposomes. Without liposomes, the HHK4b carrier enhanced luciferase expression 15-fold in comparison with the lesser branched HHK2b carrier and increased expression by 5-logs in comparison with the HHK or HK carrier. The interplay of several parameters including increased condensation of DNA, buffering of acidic endosomes and differential binding affinities of polymer with DNA have a role in the enhancement of transfection by the HK polymers. In addition to suggesting that branched HK polymers are promising gene-delivery vehicles, this study provides a framework for the development of more efficient peptide-bond-based polymers of histidine and lysine.

Amino Acid Sequence↗
PubMed2000

Co-polymer of histidine and lysine markedly enhances transfection efficiency of liposomes.

Development of nonviral delivery systems is progressing toward a transfection efficiency sufficient to affect metabolic and neoplastic diseases in humans. Nevertheless, inadequate transfection efficiency of target cells with current nonviral systems still limits the utility of this therapy. In the current study, we have determined that a co-polymer of histidine and lysine (H-K) enhances the transfection efficiency of liposomes, a leading nonviral system. We found that in the absence of serum, the addition of this polymer increased transfection as much as 10-fold in comparison with the liposome:DNA complex alone. More impressively, the co-polymer in the presence of serum increased transfection efficiency up to 100-fold. Furthermore, in vivo expression of luciferase in a tumor increased 15-fold with the addition of H-K polymer to the liposome:plasmid DNA complexes. Without liposomes, the H-K polymer had little to no effect on transfection efficiency. We anticipate that further modifications of this co-polymer will yield molecules with both increased complexity and transfection efficiency.

3T3 Cells↗
PubMed1999

Developing dendritic cell polynucleotide vaccination for prostate cancer immunotherapy.

Immunotherapy has been successfully used to treat some human malignancies, principally melanoma and renal cell carcinoma. Genetic-based cancer immunotherapies were proposed which prime T lymphocyte recognition of unique neo-antigens arising from specific mutations. Genetic immunization (polynucleotide vaccination, DNA vaccines) is a process whereby gene therapy methods are used to create vaccines and immunotherapies. Recent findings indicate that genetic immunization works indirectly via a bone marrow derived cell, probably a type of dendritic antigen presenting cell (APC). Direct targeting of genetic vaccines to these cells may provide an efficient method for stimulating cellular and humoral immune responses to infectious agents and tumor antigens. Initial studies have provided monocytic-derived dendritic cell (DC) isolation and culture techniques, simple methods for delivering genes into these cells, and have also uncovered potential obstacles to effective cancer immunotherapy which may restrict the utility of this paradigm to a subset of patients.

Antigens, Neoplasm↗
PubMed1999

Liposomes complexed to plasmids encoding angiostatin and endostatin inhibit breast cancer in nude mice.

Gene therapy transfer of angiostatin and endostatin represents an alternative method of delivering angiogenic polypeptide inhibitors. We examined whether liposomes complexed to plasmids encoding angiostatin or endostatin inhibited angiogenesis and the growth of MDA-MB-435 tumors implanted in the mammary fat pads of nude mice. We determined that plasmids expressing angiostatin (PCI-Angio) or endostatin (PCI-Endo) effectively reduced angiogenesis using an in vivo Matrigel assay. We then investigated the efficacy of these plasmids in reducing the size of tumors implanted in the mammary fat pad of nude mice. Both PCI-Angio and PCI-Endo significantly reduced tumor size when injected intratumorally (P < 0.05). Compared to the untreated control group, the mice treated with PCI-Angio and PCI-Endo exhibited a reduction in tumor size of 36% and 49%, respectively. In addition, we found that i.v. injections of liposomes complexed to PCI-Endo reduced tumor growth in the nude mice by nearly 40% when compared to either empty vector (PCI) or untreated controls (P < 0.05). These findings provide a basis for the further development of nonviral delivery of antiangiogenic genes.

Angiostatins↗
PubMed1999

Recommended policies for uses of human tissue in research, education, and quality control. Ad Hoc Committee on Stored Tissue, College of American Pathologists.

As recipients of tissue and medical specimens, pathologists and other medical specialists regard themselves as stewards of patient tissues and consider it their duty to protect the best interests of both the individual patient and the public. The stewardship of slides, blocks, and other materials includes providing, under appropriate circumstances, patient materials for research, education, and quality control. The decision to provide human tissue for such purposes should be based on the specific (ie, direct patient care) and general (ie, furthering medical knowledge) interests of the patient and of society. The same standards of responsibility should apply to all medical professionals who receive and use specimens. This document proposes specific recommendations whereby both interests can be fostered safely, ethically, and reasonably.

Biological Specimen Banks↗
PubMed1998

Gene therapy with p53 and a fragment of thrombospondin I inhibits human breast cancer in vivo.

We recently reported that a p53 encoding plasmid (BAP-p53) complexed to liposomes administered intravenously markedly attenuates the growth of a malignant human breast tumor. We now have found that systemically delivered liposomes complexed to a plasmid expressing an established antiangiogenic peptide of thrombospondin I (BAP-TSPf) decreased the growth of MDA-MB-435 tumors compared to controls in nude mice. Compared to BAP-p53, the BAP-TSPf group had a similar antitumor efficacy. More importantly, liposomes complexed with BAP-TSPf and BAP-p53 synergistically decreased the growth of MDA-MB-435 tumors when compared to either BAP-p53 or BAP-TSPf alone. Furthermore, we also determined that the combination therapy of p53 and TSPf inhibited endothelial cells in vitro more than either p53 or TSPf alone. There was also a significant decrease of the blood vessel density in the combination p53 and TSPf treatment group compared to the control groups. These results suggest that liposomes complexed to a tumor suppressor and antiangiogenic genes may be effective in treating metastatic tumors.

Animals↗
PubMed1998

In vivo gene therapy with a cationic polymer markedly enhances the antitumor activity of antiangiogenic genes.

A cationic polymer, Superfect, when complexed to the therapeutic genes, p53 and a TSP fragment, displays a much greater antitumor activity compared to cationic liposomes. At the dosages used, this polymer did not demonstrate any nonspecific antitumor effects in contrast to the liposome carriers. These in vivo findings should further stimulate the development of carrier polymers as well as expedite the evaluation of several antiangiogenic genes.

Animals↗
PubMed1997

Downregulation of RAR alpha in mice by antisense transgene leads to a compensatory increase in RAR beta and RAR gamma and development of lymphoma.

Retinoic acid receptors (RARs) alpha, beta, and gamma contain retinoic acid response elements (RAREs) in their promoter regions and respond to their own activation, thus forming an autoregulatory loop. We generated transgenic mice that expressed an antisense construct of the RAR alpha. Homozygous transgenic mice demonstrated 30% to 80% reduction in RAR alpha protein expression in various tissues. Unlike RAR alpha null mice generated by knockout, our antisense mice demonstrated significant compensatory increases in the expression of RAR beta and RAR gamma proteins. Coarse fur, male sterility, and low body weight were other abnormalities observed in these mice. Most importantly, lymphoma developed in 44% of our homozygous transgenic mice at an early stage of life. These data suggest that RAR alpha is necessary for appropriate response of the RAR beta and RAR gamma genes to physiologic changes and deregulation of the RAR alpha in transgenic mice, which resulted in upregulation of RAR beta and RAR gamma, can be associated with lymphomagenesis. Thus, the data support the hypothesis that a balance among the RARs is necessary for appropriate response to various homeostatic needs.

Animals↗
PubMed1997

Parenteral gene therapy with p53 inhibits human breast tumors in vivo through a bystander mechanism without evidence of toxicity.

Mutations of the p53 tumor suppressor gene are the most frequently observed genetic lesion in human cancer. Previously, we found that multiple intravenous injections of a liposome:p53 complex inhibited the growth of a malignant human breast cancer cell line that was implanted into nude mice. In the present study, we evaluated the toxicity of the liposome:p53 complex and the mechanism of this in vivo treatment in reducing tumor growth. Intravenously delivered liposome:p53 complex at dosages sufficient to inhibit human breast cancer in nude mice showed no evidence of toxicity. Clinical chemistries, complete blood counts, and histopathologic examination of various organs from the p53-treated groups did not demonstrate any difference from the control groups. To elucidate the mechanism by which the liposome:p53 complex inhibits cancer, the transfection efficiency of a liposome:chloramphenicol acetyltransferase (CAT) complex into the tumor was determined. Interestingly, less than 5% of the tumor was transfected with a liposome:CAT complex. A mechanism that could account for p53 reduction of tumor size and a low transfection efficiency is inhibition of angiogenesis. After one treatment, we found that the liposome:p53 complex reduced the number of blood vessels in the p53-treated group by approximately 60% compared to the control group (p < 0.001). The close correlation between the antitumor effect of p53 and the reduction of blood vessel density in the tumor suggests that p53 effects are mediated, at least in part, by an antiangiogenesis mechanism.

Animals↗
PubMed1997

Isochromosome 7q: the primary cytogenetic abnormality in hepatosplenic gammadelta T cell lymphoma.

Malignant lymphomas often have complex, nonrandom chromosomal abnormalities. Hepatosplenic gammadelta T cell lymphoma (gammadelta TCL) is an unusual post-thymic T cell lymphoma that primarily involves liver and spleen, often in young adult males. Few cases have had cytogenetic analysis. We report a consistent isochromosome 7q [i(7q)] abnormality in three cases of hepatosplenic gammadelta TCL, one with i(7q) as the sole abnormality at presentation. Three patients, 15-, 37- and 65-year-old males, presented with hepatosplenomegaly and fevers. Histopathologic, immunophenotypic, and molecular genetic studies supported the diagnosis. Spleen, liver, and bone marrow contained sinusoidal infiltrates of atypical lymphoid cells of T cell immunophenotype. PCR performed on two cases demonstrated clonal T cell receptor gamma gene rearrangements. Cytogenetic analysis of bone marrow showed i(7q) as the sole abnormality at presentation in one case. The second case showed i(7q) in addition to two normal chromosomes 7, and other structural and numerical abnormalities. The third case showed i(7q) and a deletion in the long arm of chromosome 11. These findings support the proposal that i(7q) represents the primary nonrandom cytogenetic abnormality in hepatosplenic gammadelta TCL, and plays a role in its pathogenesis.

Adolescent↗
PubMed1997

Histologically discordant lymphomas with B-cell and T-cell components.

We describe the clinical, histologic, immunophenotypic, and genotypic features of five cases of histologically discordant lymphomas with B-cell and T-cell components. Three patients presented with B-cell lymphoma; T-cell lymphoma subsequently developed. One patient presented with T-cell lymphoma; B-cell lymphoma subsequently developed. One patient presented with synchronous B-cell and T-cell lymphomas. There were three men and two women. The median age at the initial diagnosis of lymphoma was 66 years. The mean interval between the development of the two lymphomas was 83 months. All patients died of disease. The mean survival was 96 months after the initial diagnosis of lymphoma and 14 months after the diagnosis of the histologically discordant lymphoma. Epstein-Barr virus was found in two cases--the B-cell lymphoma in the patient who presented with synchronous lymphomas, and the subsequent T-cell lymphoma in one of the patients who presented with B-cell lymphoma. Based on the results of immunophenotypic and genotypic analyses, these cases likely represent the occurrence of two distinct lymphoid neoplasms rather than histologic progression of the same neoplastic clone. Furthermore, a subset of these cases are Epstein-Barr virus-associated.

Adult↗
PubMed1997

Oncogenes and tumor suppressor genes: therapeutic implications.

Genetic instability is a hallmark of cancer. Alterations in DNA through mutations, deletions, and translocations affect genes that are fundamental to normal cell growth differentiation and programmed cell death. Here, we discuss these alterations as they relate to oncogenes and tumor suppressor genes. In addition, we describe the implications the changes in oncogenes and tumor suppressor genes have on designing new therapeutic strategies for the treatment of cancer.

Genes, Tumor Suppressor↗
PubMed1995

Adult acute lymphoblastic leukemia at relapse. Cytogenetic, immunophenotypic, and molecular changes.

BACKGROUND: There have been published reports on cytogenetic, immunophenotypic, and molecular changes at relapse in childhood acute lymphoblastic leukemia (ALL) including lineage switch and secondary leukemia. There are limited data, however, on the cytogenetic, immunophenotypic, and molecular parameters of adult ALL at relapse. Because, as in children, the cytogenetic and/or immunophenotypic changes observed in adult ALL at relapse may have prognostic significance, the authors investigated the significance of such changes. METHODS: Fifty-three patients with relapsed adult ALL for whom cytogenetic, immunophenotypic, and/or molecular analyses were performed at diagnosis and at relapse were studied. Changes in any of the parameters at relapse were correlated with total survival and survival from the time of relapse. RESULTS: Of the 32 patients for whom cytogenetic studies were performed at relapse, 21 (66%) showed clonal cytogenetic changes, 40% of which were clonal evolution. None of these cases, however, showed two entirely different abnormal karyotypes at diagnosis and at relapse. The immunophenotypes showed occasional gain or loss of one or two surface markers, and the molecular genetic configurations for JH, JK, and the T-cell receptor beta were stable throughout the evolution of the disease. Patients with clonal evolution had a shorter overall survival than the rest of the group (P = 0.02). This difference, however, was not significant with respect to survival measured from the time of relapse. CONCLUSIONS: The most frequent changes in the biologic profile of adult ALL at relapse are shifts in the karyotype, with or without clonal evolution. Clonal evolution detected at relapse is associated with a higher frequency of unfavorable karyotypes at diagnosis and with a worse overall prognosis. However, survival from the time of relapse is similar in patients with and without clonal evolution.

Adolescent↗
PubMed1995

The breakpoint cluster region site in patients with Philadelphia chromosome-positive chronic myelogenous leukemia. Clinical, laboratory, and prognostic correlations.

BACKGROUND: The breakpoint site of the breakpoint cluster region (bcr) has been correlated with patient characteristics, with the disease phase, and with the prognosis of patients with chronic myelogenous leukemia (CML), but the findings remain controversial. METHODS: Appropriate restriction enzymes and the 3' and universal probes were used to map the breakpoint site by Southern blot analysis into 5' and 3' breakpoints and a breakpoint in zone 3 (or fragment 2) in 362 patients in different phases of CML (238 in early chronic phase, 69 in late chronic phase, 31 in accelerated phase, and 24 in blastic phase). Standard statistical methods were used to evaluate differences in characteristics and in prognosis by the breakpoint site. RESULTS: No correlation was noted between CML phases and breakpoint site. Among patients in the early chronic phase, thrombocytosis was significantly associated with the 3' breakpoint site (P = 0.02), whereas peripheral basophilia occurred more frequently with the 5' breakpoint site (P = 0.05). Other patient and disease characteristics were similar in frequency among the breakpoint-site subgroups. There was no difference in response to alpha-interferon therapy (186 patients treated) by the breakpoint site. Survival, dated from either referral to the authors' institution or from diagnosis, was not significantly different among patients with early chronic phase CML by the breakpoint site. However, patients with a 3' deletion tended to have a shorter survival. CONCLUSION: Determination of the breakpoint site by Southern blot analysis does not help to predict prognosis of patients with CML.

Chromosomes, Human, Pair 22↗
PubMed1995

p53 gene mutations with chromosome 17 abnormalities in chronic myelogenous leukemia blast crisis patients persist in long-term cell lines but may be acquired in acute myeloid leukemia cells in vitro.

Altered p53 tumor suppressor genes have been described in various human malignancies, including in chronic myelogenous leukemias (CML) and acute myelogenous leukemias (AML), as well as their derivative cell lines. It has been proposed that this gene mutation may be less frequent in myeloid leukemia patients than in myeloid leukemia cells lines and that the latter acquire these mutations during growth in vitro. We investigated this possibility by studying p53 gene alterations in matched samples of fresh leukemic cells and their respective derivative cell lines obtained from two CML blast crisis and one AML patient. No gross structural abnormalities were detected in the p53 gene in any of the samples analyzed. Discrete mutations in the gene in the two CML blast crisis samples and in all three derivative cell lines were, however, detected by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analyses and DNA sequencing. Cytogenetic analyses revealed either numerical or structural, as well as numerical, abnormalities of chromosome 17 in their karyotypes. Cells from the two CML blast crisis patients had two different mutations which were maintained as the sole mutations in the cell lines. The mutation detected in the AML cell line was, however, not detectable in the parental fresh leukemic cells. Our findings demonstrate that p53 mutations and chromosome 17 abnormalities occurring in CML blast crisis patients persist in long-term cell lines but that mutations not detectable in AML patients may indeed be acquired in cell lines established from them in vitro.

Adult↗
PubMed1995

Quantification of the breakpoint cluster region rearrangement for clinical monitoring in Philadelphia chromosome-positive chronic myeloid leukemia.

The purpose of this report was to evaluate scintigraphy analysis of Southern blot hybridization as a method to quantify the breakpoint cluster region (BCR) rearrangement of Philadelphia chromosome (Ph)+ chronic myelogenous leukemia (CML). Cytogenetic and molecular studies performed simultaneously on 474 bone marrow and/or blood samples from 300 patients treated with alpha-interferon-based therapy were compared. Molecular results were expressed as the percentage of rearranged BCR bands versus the total scintigraphic signal. The percentage of Ph+ metaphases was calculated on 25 metaphases. The results of molecular studies obtained on both peripheral blood and bone marrow samples were identical. The rank correlation between the BCR quantification and the percentage of Ph positivity in 465 samples was excellent (r = .78). However, of 99 samples with a normal karyotype, 24% had a BCR rearrangement. Of 86 samples with no BCR rearrangement, 13% showed a Ph chromosome. Of 49 samples with partial cytogenetic remission (Ph+ metaphases, 1% to 34%), 23% had no BCR rearrangement. In samples with a minor or no cytogenetic response (Ph+ metaphases, > 34%), BCR analysis overestimated the degree of response in 73 of 326 samples (22%). Nevertheless, survival analysis by BCR quantification level showed statistically better outcome for patients in complete or partial molecular response (P < .01). Molecular quantification of BCR was useful in monitoring the course of Ph+ CML. This method, which can be used on peripheral blood, detected residual disease not shown by cytogenetic analysis and was prognostically relevant as a measure of disease suppression.

Adult↗