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R Seshadri

Publications and source records attributed to R Seshadri.

At least 37 records · Page 2Linked to original sources
PubMed2000

Assessment of methods for tissue-based detection of the HER-2/neu alteration in human breast cancer: a direct comparison of fluorescence in situ hybridization and immunohistochemistry.

PURPOSE: To compare the efficacy of fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC) in detecting the HER-2/neu alteration in human breast cancer. PATIENTS AND METHODS: Unselected stage I, II, and III breast cancer patients (N = 900) were tested for HER-2/neu gene amplification by FISH in paraffin-embedded, formalin-fixed archival material. Of these samples, 856 were tested for HER-2/neu overexpression by non-antigen-retrieval IHC with the polyclonal antibody R60, the sensitivity and specificity of which was preliminarily compared with the United States Food and Drug Administration-approved HercepTest (Dako Corp, Carpinteria, CA). Patient survival was analyzed in relation to the presence of the HER-2/neu alteration as determined by these two methodologies. RESULTS: A total of 189 (21%) of 900 patients were positive by FISH and 147 (17.2%) of 856 were positive by IHC. This discrepancy is consistent with expected loss of IHC sensitivity associated with tissue fixation/embedding. The HercepTest did not improve sensitivity and introduced false positives. Comparison of R60-based IHC with FISH demonstrates that patient survival is associated progressively to gene amplification level as determined by FISH, whereas for IHC an association is found only in the highest (3+) immunostaining group. Among FISH-negative tumors, 45 (6.6%) of 678 were IHC-positive, with a survival probability similar to that of FISH-negative/IHC-negative cases; FISH-positive/IHC-negative patients have a survival probability similar to that of FISH-positive/IHC-positive cases. CONCLUSION: IHC does not consistently discriminate patients likely to have a poor prognosis, whereas FISH provides superior prognostic information in segregating high-risk from lower-risk beast cancers. HER-2/neu protein overexpression in the absence of gene amplification occurs infrequently in breast cancer, in which case, patient outcome is similar to that of patients without the alteration.

Adult↗
PubMed2000

High-dose chemotherapy as initial salvage chemotherapy in patients with relapsed testicular cancer.

PURPOSE: To assess the role of high-dose chemotherapy as initial salvage chemotherapy in patients with relapsed testicular cancer. PATIENTS AND METHODS: From August 1992 to April 1998, 65 patients with testicular cancer were treated with high-dose carboplatin and etoposide followed by peripheral-blood stem-cell transplantation or autologous bone marrow transplantation rescue as initial salvage chemotherapy at Indiana University. An identical course was given after hematopoietic reconstitution. Postchemotherapy resection of residual disease was performed in selected patients with incomplete radiographic response associated with normalization of markers. The median follow-up was 39 months (range, 16 to 91 months). RESULTS: Thirty-seven (57%) of the 65 patients are continuously disease-free. Three additional patients are disease-free with subsequent surgery. High-dose chemotherapy was associated with significant morbidity but no treatment-related mortality. CONCLUSION: High-dose chemotherapy as initial salvage chemotherapy achieved impressive long-term survival with acceptable toxicity in patients with relapsed testicular cancer.

Adolescent↗
PubMed2000

Direct reversal of DNA damage by mutant methyltransferase protein protects mice against dose-intensified chemotherapy and leads to in vivo selection of hematopoietic stem cells.

Direct reversal of O6 adducts caused by chemotherapy agents is accomplished in mammalian cells by the protein O6-methylguanine DNA methyltransferase (MGMT). Some tumors overexpress MGMT and are resistant to alkylator therapy. One future approach to treatment of these tumors may rely on concurrent pharmacological depletion of tumor MGMT with O6-benzylguanine (6-BG) and protection of sensitive tissues, such as hematopoietic stem and progenitor cells, using genetic modification with 6-BG-resistant MGMT mutants. We have used retroviral-mediated gene transfer to transduce murine hematopoietic bone marrow cells with MGMT point mutants showing resistance to 6-BG depletion in vitro. These mutants include proline to alanine and proline to lysine substitutions at the 140 position (P140A and P140K, respectively), which show 40- and 1000-fold resistance to 6-BG compared with wild-type (WT) MGMT. Lethally irradiated mice were reconstituted with murine stem cells transduced with murine stem cell virus retrovirus expressing each mutant, WT MGMT, or mock-infected cells and then treated with a combination of 30 mg/kg 6-BG and 10 mg/kg 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) or with 40 mg/kg BCNU alone. Compared with mice treated with BCNU alone, significant myeloid toxicity and death occurred in mice reconstituted with mock-infected or WT MGMT (<0.1 probability of survival) or the P140A mutant (0.13 probability of survival) MGMT cDNAs. In contrast, after an initial period of mild cytopenia, mice reconstituted with the P140K mutant (0.83 probability of survival) recovered nearly normal blood counts, even during continued treatment. Comparison of peripheral blood neutrophils after completion of 5 weekly treatments in these animals showed a direct correlation between the treatment and in vivo selection for progeny of transduced cells (pretreatment, approximately 8-12% transduced cells; no treatment, approximately 6% transduced cells; BCNU only, 51% transduced cells; 6-BG/BCNU, 93% transduced cells). To determine whether this selection occurred at the stem cell level, bone marrow from each treatment group was infused into secondary recipients. Whereas animals that received bone marrow from untreated animals reconstituted with 2% transduced cells, animals receiving marrow from 6-BG/BCNU-treated animals reconstituted with 94% transduced cells, demonstrating nearly complete selection for stem cells in the primary animals. Mice reconstituted with marrow from animals treated with BCNU only demonstrated 23% transduced cells, consistent with partial selection of stem cells in the primary mice. The levels of transduced cells also correlated with survival during a second round of intensive combination chemotherapy (probability of survival: 6-BG/BCNU, 1.0; BCNU alone, >0.70; no treatment, <0.1). These data demonstrate that mutant MGMT expressed in the bone marrow can protect mice from time- and dose-intensive chemotherapy and that the combination of 6-BG and BCNU leads to uniform selection of transduced stem cells in vivo in mice.

3T3 Cells↗
PubMed2000

Large-scale mobilization and isolation of CD34+ cells from normal donors.

We describe collection and purification of peripheral blood CD34+ cells from volunteer, normal donors and allogeneic stem cell donors. A total of 98 aphereses were performed on 68 volunteer donors using peripheral venous access. The mean number of nucleated cells collected was 4.6 x 10(10) which included 1.9 x 10(8) CD34+ cells corresponding to 2.7 x 10(6) CD34+ cells/kg. The number of CD34+ cells collected did not differ between males and females but did correlate with the donor's weight and the total number of nucleated cells collected. The Nexell Isolex 300i cell separator was used to isolate CD34+ cells from 30 of the collections. A mean of 0.36% of the total cells was recovered and included 43 +/- 18% of the CD34+ cells. CD34+ cells represented 85 +/- 11% of the recovered cells. The total number of CD34+ cells recovered was not influenced by the number of nucleated cells placed on the Isolex 300i. The percentage of CD34+ cells recovered was not related to the number of CD34+ cells placed on the Isolex 300i. The purity of the final product was influenced by the number of CD34+ cells but not the total number of nucleated cells. An additional 38 CD34+ cell isolations were performed on normal allogeneic stem cell donors with similar results. These observations further support the safety and feasibility of peripheral blood CD34+ cell collection and purification.

Adult↗
PubMed2000

Underutilization of breast-conserving therapy in a predominantly rural population: need for improved surgeon and public education.

Though breast-conserving therapy (BCT) was first recommended as the preferred treatment for women with early-stage breast cancer in 1990, little is known about the factors influencing or limiting the use of BCT in rural women. We retrospectively surveyed all surviving patients (227) referred to the Roger Maris Cancer Center over a 2-year period. Disease characteristics were verified by the tumor registry and random chart review. Responses were obtained from 171 patients (75%), a median of 26 months from diagnosis. The majority of patients were from rural areas; only 32% resided in towns with a population greater than or equal to 15,000. Thirty-five percent of those patients meeting published criteria had BCT. Patients who underwent BCT were younger (mean age 56.8 vs. 62.5, P = 0.01), more likely to have benign axillary lymph nodes (82% vs. 64%, P = 0.008), and more likely to be employed away from the home (66% vs. 44%, P = 0.01) than patients who underwent mastectomy (MRM). Distance from the nearest radiation facility did not affect treatment decisions (mean: 59.5 miles BCT vs. 52.6 miles MRM). Most patients (83%) ranked their surgeon as the most important source of information about treatment options. Perceived surgical recommendations were generally followed. Only three patients who felt their surgeon recommended MRM underwent BCT; eleven patients chose MRM though they believed their surgeon recommended BCT. The choice of local therapy is predominantly a surgeon-driven process; logistical barriers unique to a rural population had little impact. Unfortunately, many surgeons continue to apply much more stringent criteria when recommending BCT than those in published guidelines.

Adult↗
PubMed2000

Prognostic significance of mutations to different structural and functional regions of the p53 gene in breast cancer.

Alteration to the p53 tumor suppressor gene is associated with more aggressive disease in breast cancer, as evidenced by the shortened survival of patients with mutation. Data obtained from in vitro experiments suggest that mutations to different structural and functional domains of p53 may give rise to different effects on its biological activities, notably transactivational and apoptotic properties. We evaluated the prognostic significance of various types of p53 mutation in a series of 178 tumors identified by PCR-single-strand conformational polymorphism screening as containing a mutant gene. Mutations within exon 4 were associated with particularly poor prognosis, possibly relating to the importance of this region in apoptosis. Mutations that caused denaturation of the protein structure were also associated with poor survival, again perhaps because of effects on apoptosis. In contrast, patients with mutations in the DNA contact region showed similar survival to that of patients with normal p53, suggesting a less important role for p53-mediated transactivation in determining tumor aggressiveness. Other mutation groups associated with poor prognosis were single-base substitutions and transversion mutations. Mutations in exon 6, exon 7, or the "hotspot" codons (175, 245, 248, 273) were associated with only a small reduction in patient survival compared with normal p53. These results allow some insight to be gained into the functional importance of various p53 domains in terms of their influence on overall patient survival. Further work is required to determine whether these domains are also important in influencing the response of breast tumors to adjuvant therapies.

Amino Acid Substitution↗
PubMed1999

HRAS1 rare minisatellite alleles and breast cancer in Australian women under age forty years.

BACKGROUND: A recent meta-analysis of 23 studies supported the empirically derived hypothesis that women who lack one of the four common minisatellite alleles at the HRAS1 locus are at increased risk of breast cancer. These studies relied on visual sizing of alleles on electrophoretic gels and may have underreported rare alleles. We determined whether this hypothesis applied to early-onset breast cancer by using a new method to size minisatellite alleles. METHODS: We conducted a population-based, case-control-family study of 249 Australian women under 40 years old at diagnosis of a first primary breast cancer and 234 randomly selected women, frequency matched for age. We sized HRAS1 minisatellite alleles with an Applied Biosystems model 373 automated DNA sequencer and GENESCAN(TM) software. All P values are two-sided. RESULTS: We found no association of rare alleles with breast cancer, before or after adjustment for risk factors and irrespective of how their effects were modeled (crude odds ratio = 1.04; 95% confidence interval [CI] = 0.071-1.53; P =.8). The rare allele frequency was 0. 173 (95% CI = 0.149-0.197), three times the pooled estimate of 0.058 (95% CI = 0.050-0.066) from previous studies (P<.001), and was similar for case subjects, 0.177 (95% CI = 0.143-0.221), and control subjects, 0.169 (95% CI = 0.135-0.203) (P =.7). CONCLUSION: There was no support for an association between rare HRAS1 alleles and the risk of early-onset breast cancer, despite 80% power to detect effects of the magnitude of those associations (1.7-fold) previously suggested. IMPLICATIONS: The question of whether cancer risk is associated with rare minisatellite HRAS1 alleles needs to be revisited with the use of new methods that have a greater ability to distinguish rare alleles from similarly sized common alleles.

Adult↗
PubMed1999

A simple index using video image analysis to predict disease outcome in primary breast cancer.

Image analysis was used to investigate the prognostic significance of immunostaining for oestrogen receptor (ER), p53 tumour-suppressor protein and tumour cell proliferation (MIB-1) in a random cohort of 200 primary breast cancer patients with between 4 and 7 years of clinical follow-up. Image measurements of the percentage of immunopositive cancer cell nuclei (% positive nuclear area) were recorded for the above tumour features for each patient. Assessment of relative risk using Cox's univariate analysis indicated that tumour size, number of cancer-involved nodes, MIB-1 and ER % positive nuclear area were significantly associated with breast cancer disease outcome, i.e., relapse-free survival and overall survival. In multivariate analysis, tumour size, number of involved nodes, ER and MIB-1 % positive nuclear area were retained as independent predictors of prognosis, depending on the image measurement cut-point used. A prognostic model, which can be used without reference to nodal involvement, was constructed for tumour size, ER cut-point of 30% positive nuclear area and MIB-1 cut-point of 10% positive nuclear area. Kaplan-Meier analysis of this image-based prognostic index identified 4 risk groups with predicted 5-year overall survival rates of 93%, 83%, 76.7% and 61.5%. We conclude that image measurements of ER and proliferative rate can be combined with tumour size to construct a prognostic index which reliably predicts disease outcome in primary breast cancer without knowledge of the nodal status of the patient.

Adult↗
PubMed1999

The PISSLRE gene: structure, exon skipping, and exclusion as tumor suppressor in breast cancer.

In sporadic breast cancer, loss of heterozygosity (LOH) frequently occurs in three discrete regions of the long arm of chromosome 16q, the most telomeric of which is located at 16q24.3. Among the genes mapped to this region, PISSLRE is a plausible candidate tumor suppressor gene. It codes for a putative cyclin-dependent kinase that, as with other members of this family, is likely to be involved in regulating the cell cycle and therefore may have a role in oncogenesis. We characterized the genomic structure of PISSLRE and found that the splicing of this gene is complex. A variety of different transcripts were identified, including those due to cryptic splice sites, exon skipping, insertion of intronic sequences, and exon scrambling. The last phenomenon was observed in a rare PISSLRE transcript in which exons are joined at a nonconsensus splice site in an order different from that predicted by the genomic sequence. To screen the PISSLRE gene in breast tumors with ascertained LOH at 16q24.3, we have analyzed each exon by single-strand conformational polymorphism. No variation was found in the coding sequence, leading us to conclude that another tumor suppressor must be targeted by LOH in sporadic breast cancer.

Alternative Splicing↗
PubMed1999

Pharmacology of N-benzyladriamycin-14-valerate in the rat.

PURPOSE: N-Benzyladriamycin-14-valerate (AD 198) is a semisynthetic anthracycline analogue superior to doxorubicin (DOX) both in vitro and in experimental rodent tumor models, and with differing mechanistic properties from those of the parental antibiotic agent. In the present study, we examined the metabolic fate and hematotoxicity of AD 198 in rats, with a view to determining whether some of the therapeutic properties observed for this drug might be due to a DOX prodrug effect. METHODS: Samples of plasma, bile and urine were obtained at various times following intravenous (i.v.) [14C]-AD 198 administration to rats and were analyzed by reversed-phase HPLC with flow-fluorescence detection and complementary liquid scintillography. In other animals, red blood cell and white blood cell (WBC) counts were determined for blood obtained by retrobulbar sampling on selected days from groups of animals receiving either AD 198 or DOX at several dose levels, as well as from vehicle controls. RESULTS: Following a single iv dose of [14C]-AD 198 (5 mg/kg; equivalent to the optimal murine antitumor dose) in anesthetized rats, a triphasic plasma decay pattern for parental drug was evident with extremely rapid alpha and beta phases followed by a very long terminal elimination phase. Principal plasma products included N-benzyladriamycin (AD 288) and N-benzyladriamycinol (AD 298) together with very low levels of DOX and doxorubicinol (DOXOL). Analysis of bile from anesthetized and conscious animals receiving AD 198 revealed DOX to be the principal biliary fluorescent species together with low levels of AD 288, AD 298 and DOXOL; no parental drug was seen. By contrast, AD 288 was the principal urinary product, together with low levels of AD 298 and DOX; again, no parental drug was evident. Dose recovery (8 h) in the respective bile and urine of anesthetized rats was 12.4% and 13.2% based upon total fluorescence versus 1% and 15.3% of the administered radiolabel. In conscious animals, 13.4% of drug fluorescence was recovered in the bile (48 h), while in urine 16.6% and 77.1% of drug fluorescence and radiolabel, respectively, were eliminated over 72 h. The discrepancy between recovery of drug fluorescence and 14C was due to the production of nonfluorescent hippuric acid (benzoylglycine) and N-benzyl daunosamine as a consequence of hepatic and renal drug metabolism. In the separate hematotoxicity studies, AD 198 (24.6 mg/ kg i.v.; equivalent to the murine LD50 dose), produced a 45% reduction (nadir day 3-5) in WBC count, with recovery by day 10. By contrast, DOX (10 mg/kg i.v.; equivalent to the mouse highest nonlethal dose) produced an 80% decline in WBC with only partial recovery by day 17. CONCLUSIONS: By virtue of the low systemic DOX levels and low hematotoxicity observed in rats receiving AD 198, the in vivo therapeutic superiority of AD 198 cannot be attributed to substantial intracellular DOX generation. The conclusion that the therapeutic superiority of AD 198 compared to DOX results from the mechanistic differences between these two drugs is further supported by recent observations on their biochemical differences with regard to protein kinase C and topoisomerase II inhibition.

Animals↗
PubMed1999

DNA polymorphism analysis in transfusion-associated graft-versus-host disease.

During cardiac surgery for transposition of the great arteries at age 7 weeks, a female infant received blood, fresh frozen plasma and platelet transfusions. Eleven days postoperatively, she developed bloody diarrhoea, fever, an erythematous macular rash, hepatomegaly, seizures and pancytopaenia. A clinical diagnosis of transfusion related graft-versus-host disease (GVHD) was supported by skin histopathology. DNA polymorphism studies confirmed that circulating lymphocytes in peripheral blood and infiltrating cells in the skin were foreign in origin and were derived from transfused blood cells. No underlying immunodeficiency was identified. Treatment with steroids cyclosporin and antithymocyte globulin was unsuccessful and death occurred 2 months after surgery. The features of fever, rash, diarrhoea, liver dysfunction and pancytopaenia which characterize GVHD may mimic drug reactions or viral infection. In addition to histological features on skin biopsy. DNA polymorphism studies on skin and blood samples provide a unique and sensitive method to confirm GVHD. Irradiation of blood products should be considered for acutely compromised infants requiring urgent cardiac surgery.

DNA, Satellite↗
PubMed1999

Differential expression of translational elements by life cycle variants of Coxiella burnetii.

Coxiella burnetii replicates as distinct morphological forms, which may allow potential life cycle variants to survive the harsh environment of the phagolysosome. Monoclonal antibodies (MAbs) were compared by Western blotting for reactivity with large cell variant (LCV) and small cell variant (SCV) antigens to characterize proteins differentially expressed by C. burnetii. MAb NM7.3 reacted with a approximately 32-kDa LCV-upregulated antigen, and MAb NM183 reacted with a approximately 45-kDa LCV-specific antigen. MAb NM7.3 was used to screen a lambdaZapII C. burnetii DNA expression library, and an immunoreactive clone was identified with sequence similarity to the Escherichia coli tsf gene, which encodes elongation factor Ts (EF-Ts). Since a similar screen with MAb NM183 did not identify immunoreactive clones, an alternate strategy was devised to clone the reactive antigen based on observations of cross-reactivity with the 45-kDa elongation factor Tu (EF-Tu) protein from Chlamydia trachomatis. The highly conserved nature of EF-Tu among eubacteria allowed PCR amplification of a tuf gene fragment (encoding approximately 95% of the predicted EF-Tu open reading frame) from C. burnetii using degenerate primers. The product of the cloned tuf gene fragment reacted with MAb NM183 in Western blot analysis, confirming the identity of the 45-kDa LCV-specific antigen. Identification of two proteins differentially expressed by C. burnetii, EF-Tu and EF-Ts, both essential components of the translational machinery of the cell, supports the hypothesis that LCVs are metabolically more active than SCVs.

Amino Acid Sequence↗
PubMed1999

Combination versus sequential doxorubicin and docetaxel as primary chemotherapy for breast cancer: A randomized pilot trial of the Hoosier Oncology Group.

PURPOSE: To evaluate the efficacy and toxicity of combination and sequential dose-dense chemotherapy with doxorubicin and docetaxel (Taxotere; Rhône-Poulenc Rorer, Collegeville, PA) as primary chemotherapy of breast cancer. PATIENTS AND METHODS: Patients with newly diagnosed stage II or noninflammatory stage III breast cancer were randomly assigned to receive the same total doses of doxorubicin and docetaxel over a 12-week period before definitive surgery. Patients in arm A received sequential therapy with doxorubicin 75 mg/m(2) every 2 weeks for three cycles followed by docetaxel 100 mg/m(2) every 2 weeks for three cycles. Patients in arm B received combination therapy with doxorubicin 56 mg/m(2) plus docetaxel 75 mg/m(2) every 3 weeks for four cycles. Granulocyte colony-stimulating factor was administered on days 2 to 12 of each cycle in both groups. RESULTS: Forty patients were entered onto the trial. Pretreatment tumor size averaged 5.7 cm with clinically positive axillary lymph nodes in 23 patients (57%). As expected, myelosuppression was severe in both groups; however, >/= 80% of planned dose-intensity was delivered. Hand-foot syndrome was more common after sequential therapy. Clinical responses were similar in both groups, with an overall response rate of 87%, including 20% clinical complete remissions. Pathologic complete remission or residual in situ disease only was confirmed in five patients (12.8%). Patients who received sequential therapy had fewer positive lymph nodes (mean, 2.17 v 4.81; P <.037) at definitive surgery. CONCLUSION: Primary chemotherapy with doxorubicin and docetaxel is well tolerated and highly active. A sequential treatment schedule increases toxicity but may result in more substantial lymph node clearance than combination therapy.

Adult↗
PubMed1999

Osteometric analysis of sexual dimorphism in the sternal end of the rib in a west African population.

This study, and others, are being carried out in order to establish a Forensic Anthropology databank on age estimation and sex determination of skeletonized remains in Ghana. An osteometric study of sexual dimorphism in the sternal end of the right fourth rib on 346 consecutive coroner's autopsy cases (221 males, 125 females) of known age, sex, and race was conducted. The height and width of the sternal end of the rib were measured in each case. The sample was analyzed in three groups: young (< 30 years), old (> or = 30 years), and total sample (total group). Stepwise discriminant function analysis showed that the accuracy of sex determination varied from 80% in the young and 74% in the old groups to 78% for the total group. Statistical analysis of the results obtained when the functions derived from the study were tested using another batch of ribs showed the functions to be effective and reliable in determining sex. When functions derived from a previous study of American Whites were used to determine sex in our study sample, the vast majority of males were misclassified as females. This is the first time, to our knowledge, that a Black African population has been studied osteometrically to evaluate sexual dimorphism in the sternal end of the fourth rib.

Adult↗
PubMed1999

Quality of life of patients with perennial allergic rhinitis: preliminary validation of the Rhinoconjunctivitis Quality of Life Questionnaire in Singapore.

Though sufferers of perennial allergic rhinitis do not die from their ailment, they endure years of chronic nose disease that Interferes with many important aspects of their lives. A rhinitis-specific instrument to gauge the quality of life of patients with this disease was published in 1991. Here, we validated the Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ) for use in English-speaking patients with perennial allergic rhinitis. We established that the RQLQ distinguishes between patients and control, demonstrates internal consistency and is sensitive to change. This study suggests that the RQLQ can be used to assess the quality of life of patients with perennial allergic rhinitis in Singapore.

Adolescent↗
PubMed1998

Characterization and screening for mutations of the growth arrest-specific 11 (GAS11) and C16orf3 genes at 16q24.3 in breast cancer.

Loss of heterozygosity involving the long arm of chromosome 16 is a frequent event seen in a number of human carcinomas, including breast, prostate, hepatocellular, and ovarian cancers. A region found to be commonly deleted in breast and prostate carcinomas is located at 16q24.3, which suggests the presence of a tumor suppressor gene that may be altered in these two malignancies. A detailed physical and transcription map of this region that includes the loci defining the smallest region of deletion has been constructed. This report describes the characterization of a transcript located in this region, the growth arrest-specific 11 (GAS11) gene, which was viewed as a potential tumor suppressor gene due to the expression of its mouse homolog specifically during growth arrest. The gene consists of 11 exons spanning approximately 25 kb. Northern blot analysis identified two ubiquitously expressed mRNAs of 3.4 and 1.8 kb produced by the use of alternative polyadenylation sites. Another gene, C16orf3 (chromosome 16 open reading frame 3), was found to lie within intron 2 of GAS11. This gene appears intronless, is transcribed in the orientation opposite to that of GAS11, and is expressed at low levels. These genes were examined for mutations in breast tumor DNA, and both were excluded as tumor suppressor genes involved in breast cancer.

Alleles↗
PubMed1998

Construction of a high-resolution physical and transcription map of chromosome 16q24.3: a region of frequent loss of heterozygosity in sporadic breast cancer.

A breast cancer tumor suppressor gene has been localized to chromosome 16q24.3 by loss of heterozygosity (LOH) studies of breast tumor DNA. To identify candidate genes for this suppressor function, we have constructed a detailed physical map extending approximately 940 kb from the telomere of the long arm of chromosome 16 that encompasses the minimum LOH interval. This contig consists of a minimum overlapping set of 35 cosmids and a single PAC clone that were aligned by restriction enzyme site mapping. Cosmids were initially identified by screening filters with markers localized to the region by physical mapping using mouse/human somatic cell hybrids, and subsequently cosmid ends were used to complete the contig. A total of seven known genes, including PRSM1, PISSLRE, and the recently cloned Fanconi anemia A (FAA) gene, and potential transcripts from exon-trapping experiments have been located to this contig. A minimum of 14 new transcripts have been identified based on homology of trapped exons with database sequences. This contig and expressed sequence map will form the basis for the identification of the breast cancer tumor suppressor gene in this region.

Breast Neoplasms↗