Retention of CD44 introns in bladder cancer: understanding the alternative splicing of pre-mRNA opens new insights into the pathogenesis of human cancers.
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Alternative Splicing↗
Biomedical subjects
D L Cooper
Publications and source records attributed to D L Cooper.
Applications of momentum-space similarity.
Momentum-space similarity indices were used in studies linking chemical structure to observed activity. These included (a) the biological activity of various molecules that are of interest due to their capacity for HIV inhibition; and (b) the hyperpolarisabilities of series of conjugated molecules. Study (a) included comparisons of the total valence densities of different molecules or the densities associated with particular molecular fragments. Study (b) involved, for each molecule, a comparison of the momentum-space densities of the highest occupied (HOMO) and lowest unoccupied (LUMO) molecular orbitals. The momentum-space approach, which is most sensitive to features of the long-range valence electron density, turned out to be particularly useful for cases such as these, in which the physical property or biological activity has no obvious dependence on the bonding topology of the molecules.
Antiviral Agents↗
Molecular mechanisms regulating the hyaluronan binding activity of the adhesion protein CD44.
In the present study, we describe the isolation and characterization of a cDNA clone designated B6F1.3, that appears to 'activate' the hyaluronan-binding capacity of CD44 upon transfection into the murine fibroblastoid cell line MOP8. Sequence analysis indicates that the putative regulatory molecule encoded by this clone is identical to the murine interleukin-2 receptor gamma chain (mIL-2R gamma), a recently described type 1 transmembrane protein that constitutes an integral component of the cell surface receptors that bind a number of cytokines including IL-2, IL-4, IL-7, IL-9, IL-15 and perhaps also IL-13. Mutations in this molecule have been shown to be responsible for X-linked severe combined immunodeficiency (XSCID) in humans. With the exception of bone marrow, the mIL-2R gamma chain was found to be expressed at high levels on all hemopoietic cell lines and tissue types examined. Non-hemopoietic tissues are generally negative. FACS analysis and Western blot analysis indicated respectively that B6F1.3 does not mediate its effects by upregulating the expression of CD44 or by altering the alternative splicing of the molecule. Removal of the cytoplasmic tail of the mIL-2R gamma chain, including a Src homology region 2 (SH2) subdomain, abolished its ability to enhance CD44-mediated binding to hyaluronan suggesting the involvement of signal transduction events triggered via the cytoplasmic domain in the 'activation' process. Determining whether activating molecules such as B6F1.3 are co-expressed within tumor cells may help improve the potential value of CD44 as a diagnostic marker of metastatic disease.
Alternative Splicing↗
Gene therapeutic approach to primary and metastatic brain tumors: I. CD44 variant pre-RNA alternative splicing as a CEPT control element.
Our laboratory and others have shown alternative splicing of up to ten exons at a discrete extracellular site to be primarily responsible for the generation of CD44 variant (CD44v) isoforms. Based on clear differences in the expression of these CD44v isoforms between normal and malignant tissues, we believe that elucidation of the mechanisms underlying the regulation of CD44 alternative splicing may provide a new gene therapeutic targeting approach based on CD44 pre-mRNA processing in vivo. This strategy incorporates utilization of CD44 alternative splicing control elements into a chimeric enzyme/prodrug therapy (CEPT), a novel modification of the virus-directed enzyme/prodrug therapy (VDEPT) approach for the treatment of brain metastases from tumors of systemic origin. As initial steps towards the development of a gene therapeutic approach based on targeting tumor cell expression of specific CD44v alternatively spliced isoforms, we have: (1) developed a novel in vivo assay system that allows the rapid analyses of potentially therapeutic CD44 alternative splicing minigene constructs; and (2) cloned the E. coli cytosine deaminase (CD) gene and fused its enzymatically active domain to alternatively spliced CD44 exons (CD44/CD). Deamination of cytosine by this CD44/CD chimeric fusion protein is demonstrated in E. coli cell lysates to be equal to that of wild type cytosine deaminase.
Alternative Splicing↗
Gene therapeutic approaches to primary and metastatic brain tumors: II. ribozyme-mediated suppression of CD44 expression.
Glioblastomas are highly invasive intracerebral tumors that are known to express the CD44 cell adhesion molecule. Human glioma cell adhesion and invasion in vitro may in part be mediated by the interaction of CD44 with extracellular matrix proteins. To suppress the growth and invasive effects of CD44 expression on primary brain tumors we have designed two hammerhead ribozymes as potential gene therapeutic agents. Both ribozymes designed to target exon 2 of CD44 exhibited in vitro cleavage of in vitro transcribed CD44s and CD44R1 RNAs. The anti-CD44 effect of these ribozymes results from directed RNA cleavage, requiring both a target sequence and an appropriate catalytic center. Further, following transient transfection of one of these ribozymes into the SNB-19 glioma cell line, significant in vivo cleavage activity against cellular CD44 transcripts was demonstrated by flow cytometrical analysis. These preliminary results suggest that CD44-directed hammerhead ribozymes may be useful as gene therapeutic agents.
Base Sequence↗
To metastasize or not? Selection of CD44 splice sites.
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Adenocarcinoma↗
Personal recollections of college health and the ACHA.
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Societies, Medical↗
Pseudoleukemia after granulocyte colony-stimulating factor therapy.
Therapy with myeloid colony-stimulating factors has been safely and effectively used in a wide variety of situations associated with neutropenia. We present a case of pseudoleukemia occurring in a patient with lymphoma and pancytopenia after 2 days of treatment with granulocyte colony-stimulating factor (G-CSF). Bone marrow aspirate and flow cytometry study results were consistent with acute myelomonocytic leukemia but were normal after G-CSF was discontinued for 4 days. As previous phase I studies of bone marrow morphology after G-CSF use have not described the extreme myeloid immaturity seen in this patient, it seems likely that the action of G-CSF was enhanced by factors associated with the patient's illness. We emphasize the clinical importance of this case in light of the widespread use of G-CSF.
Antineoplastic Combined Chemotherapy Protocols↗
DNA fingerprinting of crude bacterial lysates using degenerate RAPD primers.
Methods for identifying isolates of various pathogenic bacteria by DNA fingerprinting with random primers (RAPD) have been described recently. In these methods many primers are screened and the primers that generate the most informative DNA pattern are selected. A new strategy that simplifies the primer selection process for RAPD fingerprinting has been developed in our laboratory. In this approach, one or more degenerate nucleotides is introduced into the core RAPD primer sequence at various nucleotide positions. Results show that a single degenerate nucleotide in the primer sequence can significantly change the DNA profile obtained for the same template. The more removed the degenerate nucleotide is from the 3' end of the primer, the less dramatic is its effect on banding pattern. This method utilizing degenerate RAPD (D-RAPD) primers was tested on clinical isolates of Legionella pneumoniae, and results were confirmed with nondegenerate RAPD primers. Results obtained with D-RAPD primers were in total agreement with those obtained with nondegenerate RAPD primers. We propose that the use of a core RAPD primer sequence with one or more degenerate nucleotide(s) at various positions can expedite the generation of unique DNA fingerprints individual organisms. A general method for selecting the most useful fingerprinting RAPD primers is discussed.
Base Sequence↗
Prognostic significance of CD44 expression in adenocarcinoma of the lung.
Aims-To determine whether expression of CD44 in neoplasia is associated with tumour grade, stage and prognosis.Methods-The immunohistochemical expression of CD44 was evaluated using the mouse antihuman monoclonal antibody 3G12 which recognises regions shared by all CD44 isoforms to determine whether expression in formalin fixed, paraffin wax embedded tissue correlates with tumour grade, stage or survival in adenocarcinoma of the lung. Thirty one adenocarcinomas of the lung, 16 T2N0 and 15 T2N1, and their nodal metastases were studied.Results-Of the 31 tumours, 25 were positive for the CD44 antigen. CD44 expression correlated with tumour grade, in that intense staining was seen only in moderately and/or poorly differentiated tumours. CD44 did not correlate with nodal status, tumour size, pleural invasion, angiolymphatic invasion, or host inflammatory response, but did correlate with survival. A median survival of 46 months was observed in patients with moderate to strong CD44 expression compared with 24 months for those with no or weak expression. Nine patients were alive without evidence of disease at a median follow up of 61 months. Six (66%) of these nine patients had strong CD44 expression. This contrasts with strong expression in only three (17%) of the 17 patients dying with a median survival of 28 months.Conclusion-In primary adenocarcinoma of the lung loss of CD44 expression is associated with less favorable outcome and may indicate a more aggressive neoplasm. CD44 may be a useful prognostic marker in lung carcinoma.
Journal Article↗
Application of the Cotswolds Criteria for the assessment of disease response in patients treated for Hodgkin's disease.
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Diagnostic Imaging↗
Second solid malignancies after combined modality therapy for Hodgkin's disease.
PURPOSE: To determine the actuarial incidence (AI) and relative risk (RR) of second solid malignancies (SSM; solid tumors and non-Hodgkin's lymphoma) in patients with Hodgkin's disease who were treated with chemotherapy and adjuvant, low-dose radiation (combined modality therapy; CMT). PATIENTS AND METHODS: From 1969 to 1983, 102 patients with previously untreated advanced Hodgkin's disease (group A) and 81 patients with recurrent disease after radiation (group B) were treated with CMT. Patients were observed for the development of solid tumors (ST) and non-Hodgkin's lymphoma (NHL), and the AI and RR were calculated. RESULTS: Nearly half of the patients entering remission were observed for greater than 15 years. At 20 years, the AI for SSM was 12% in group A versus 41% in group B (P = .009). The overall RR for developing a ST in group A was 1.88 (not significant) versus 8.84 in group B (95% confidence interval, 5.3 to 15.4). The difference in the RR between groups A and B was significant (P < .001). The RR for developing NHL was significantly increased in both groups, but the difference between groups was not significant. CONCLUSION: Previously untreated patients with advanced disease who were treated with CMT (group A) had a modest but not significant increase in the RR of ST; however, patients treated with CMT for recurrent disease (group B) had a highly significant increase in the RR of ST. Possible explanations for the increase in ST in group B include more cumulative radiation or a greater carcinogenic effect of chemotherapy in previously irradiated patients, but it also is possible that the increase is due to a longer follow-up time.
Adolescent↗
Molecular diagnosis of cystic fibrosis.
The clinical and pathologic features of patients with cystic fibrosis are summarized, and generalized genotype or phenotype correlations are discussed in this article. Incorporation of modern molecular biologic techniques into a rapid, cost-efficient, and specific diagnostic laboratory test is outlined. The protocol for the multiplex polymerase chain reaction detection of five common cystic fibrosis transmembrane conductance regulator (CFTR) mutations by ASO hybridization is detailed. Neonatal screening and issues involved in the genetic counseling of families at risk for cystic fibrosis are presented. Recommendations for molecular diagnostic testing in cystic fibrosis are made.
Base Sequence↗
Enzymatic and molecular diagnosis of Gaucher disease.
Advances in the knowledge of the molecular genetics of Gaucher disease has made diagnosis more certain. Carrier detection in kindreds in which the responsible mutation has been defined is completely reliable now. Coupled with enzymatic assays, the diagnostic capabilities are greater than before. Use of these methods provides important information to individuals at risk and allows them to make critical decisions. The new, simplified methods reviewed in this article permit the molecular diagnosis of the disease and carrier stage of large numbers of samples within 1 week.
Base Sequence↗
Alternative splicing of CD44 pre-mRNA in human colorectal tumors.
Expression of the CD44 molecule has been linked to tumor growth and metastases in both human and rodent cancers. Alternatively spliced variants expressed in rat and mouse tumors have been shown to confer metastatic potential to non-metastatic carcinoma cell lines, and human homologues of rat variant mRNA sequences are expressed in human tumors. In the present study matched sets of RNA from adenocarcinomas of the colon and distant normal mucosa were assayed for CD44 expression by quantitative RT-PCR. Retrospective analysis revealed that colonic tumor cells had both quantitative and qualitative differences in CD44 expression when compared to normal mucosa. These were: 1) an increase in levels of CD44 transcripts, 2) an increase in levels of alternatively spliced transcripts, 3) the presence of larger alternatively spliced transcripts with inserts > 400 bases and 4) the primary alternatively spliced CD44 isoform in colonic adenocarcinomas in all cases is CD44R. Interestingly, two patterns of CD44 isoform expression termed "variant dominant" or "balanced" patterns of expression, based on the ratio of variant to standard CD44 transcripts (R+V's/H), could be differentiated. An unfavorable prognosis was suggested for tumors expressing increased levels of CD44 variant exons previously associated with tumor metastasis. Specifically, patients with tumors expressing the "variant dominant" pattern of expression irregardless of Dukes classification and Dukes C and D staged tumors of both patterns exhibited a poorer prognosis.
Adenocarcinoma↗
Ligand binding specificity of alternatively spliced CD44 isoforms. Recognition and binding of hyaluronan by CD44R1.
CD44 species of widely differing molecular mass have been identified on various normal and/or transformed cells. Recent studies have demonstrated that much of this heterogeneity is produced as a result of the alternative splicing of a series of 10 exons present within the CD44 gene generating a large number of CD44 isoforms containing additional peptide sequences of varying length inserted into a single site within the extracellular domain of the molecule. At present, the effect of such insertions on the ligand binding specificity of CD44 remains unclear. CD44H, the major CD44 isoform expressed by most resting cell types, has been shown to function as a receptor for the glycosaminoglycan hyaluronan. In contrast, CD44E, the major isoform expressed by the colon carcinoma cell line HT29, which contains a 132-amino acid insert, is unable to recognize and bind this ligand. In the present study we demonstrate that CD44R1, an isoform isolated from the myelomonocytic cell line KG1a, that differs from CD44E by just 3 amino acid substitutions, is fully capable of mediating the attachment of transfected COS7 cells to hyaluronan-coated plastic. In order to confirm that such binding was directly mediated by the introduced CD44 species, chimeric proteins containing the entire extracellular domain of CD44H or CD44R1 fused in-frame to human bone/liver/kidney alkaline phosphatase were prepared and tested for their ability to bind hyaluronan-coated plastic. Both fusion proteins bound equally well to hyaluronan and in each case their attachment could be readily inhibited by monoclonal antibodies directed against the hyaluronan-binding domain of CD44. These data indicate that the 132-amino acid insert present within the extracellular domain of CD44R1 does not interfere with the hyaluronan binding function of the molecule. Since CD44E contains an identically sized insert but is unable to bind hyaluronan, it is likely that mutation of one or more of the 3 amino acid residues that differ between CD44E and CD44R1 is responsible for the altered functional activity of this particular molecule.
Alternative Splicing↗
Impact of non-CTCL dermatologic diagnoses and adjuvant therapies on cutaneous T-cell lymphoma patients treated with total skin electron beam radiation therapy.
PURPOSE: To evaluate the impact of pre-cutaneous T-cell lymphoma dermatologic diagnoses and adjuvant therapies on the relapse-free and overall survivals of patients treated with total skin electron beam therapy. METHODS AND MATERIALS: Between 1974 and 1990, 164 patients were evaluated by members of Yale University School of Medicine departments of Dermatology and Therapeutic Radiology and treated with total skin electron beam therapy to a total dose of 3600 cGy. Patients who achieved a clinical complete response were offered doxorubicin/cyclophosphamide chemotherapy, extracorporeal photopheresis, or no systemic adjuvant therapy. The effects of TNM stage, antecedent non-T-cell lymphoma dermatologic diagnoses, and systemic adjuvant therapies were analyzed for their impact on relapse-free and overall survival. RESULTS: In this cohort of patients, an antecedent dermatologic diagnosis of follicular mucinosis or lymphomatoid papulosis was significantly associated with a shorter relapse-free survival for T1 and T2 patients, while antecedent "non-specific" dermatitides were associated with a somewhat better relapse-free survival. When the impact of systemic adjuvant therapies was analyzed, neither systemic doxorubicin/cyclophosphamide chemotherapy nor systemic extracorporeal photopheresis were found to delay cutaneous relapse. CONCLUSION: Our results suggest that antecedent follicular mucinosis and lymphomatoid papulosis may be associated with short relapse-free survival in T1 and T2 patients treated with total skin electron beam therapy. They also imply that neither adjuvant chemotherapy nor extracorporeal photopheresis delay cutaneous relapse after total skin electron beam therapy.
Adult↗
A phase II study of outpatient chemotherapy with cisplatin, 5-fluorouracil, and leucovorin in nasopharyngeal carcinoma.
BACKGROUND: Systemic disease progression occurs in the majority of patients with locally advanced nasopharyngeal carcinoma (NPC). Although a variety of chemotherapeutic drugs have had tumoricidal activity, the roles of chemotherapy and optimal regimens must be further defined. Based on high response rates of Cisplatin, 5-Fluororacil and Leucovorin (PFL) in patients with advanced squamous cell cancers of the head and neck, we tested a new outpatient PFL chemotherapy program in patients with advanced NPC. METHODS: Patients with NPC and 1) previously untreated, locally advanced disease; 2) local regional recurrence (LR) after radiotherapy; or 3) metastatic disease were eligible for study. Cisplatin 20 mg/m2/d, 5-FU 800 mg/m2/d and Leucovorin 90 mg/m2/d were administered simultaneously by continuous 96-hour intravenous infusion every three weeks. Patients were evaluated for response, survival, and toxicity. RESULTS: Thirty-five patients were studied. The response rates of PFL therapy were 100% (15% complete response [CR], 85% partial response [PR]) in 20 patients with locally advanced or locally recurrent disease, and 80% (13.3% CR, 67.7% PR) in 15 patients with metastatic disease. The overall median survival was 20 months after therapy (range, 2-21). The median survival rate for previously untreated, locally advanced patients was not reached. The median survival rate for previously treated, local recurrence was 34 months and for metastatic patients was 14 months. Mucositis and leukopenia were the dose-limiting toxicities (20-23%, grade III) and occurred more frequently in patients previously irradiated. No treatment-related deaths occurred. CONCLUSIONS: Outpatient PFL chemotherapy is active, safe, and convenient for advanced stage nasopharyngeal carcinoma patients, and the overall toxicities are tolerable.
Adolescent↗