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J Isola

Publications and source records attributed to J Isola.

At least 55 records · Page 3Linked to original sources
PubMed1999

CDKN2/p16 predicts survival in oligodendrogliomas: comparison with astrocytomas.

Cyclin-dependent kinase 4 inhibitor (CDKN2/p16) is a cell cycle regulatory protein that has been demonstrated to be inactivated by mutations, deletions or transcriptional silencing during pathogenesis of a variety of human malignancies. We studied the correlation of CDKN2/p16 expression with cell proliferation activity and patient survival in 42 oligodendrogliomas and 36 astrocytomas. CDKN2/p16 expression was frequently decreased in grade II and anaplastic oligodendrogliomas (17/42) where lack of CDKN2/p16 protein predicted poor survival (p = 0.0045). In astrocytomas low CDKN2/p16 expression was associated with high histologic malignancy grade (p = 0.002): CDKN2/p16 protein level was decreased in 9 out of 10 glioblastomas, in 5 out of 9 anaplastic astrocytomas, in 3 out of 10 grade II astrocytomas and in none of pilocytic astocytomas (0/7). Low CDKN2/p16 expression was also associated with high cell proliferation activity (MIB-1 immunocytochemistry: p = 0.004; mitotic index: p = 0.007) and poor patient survival (p = 0.025) in astrocytomas. Low CDKN2/p16 mRNA expression had the same topographic distribution as nuclear CDKN2/p16 immunoreactivity proving for reliability of the immunocytochemical findings. Our results are in agreement with earlier studies demonstrating CDKN2/p16 inactivation during tumorigenesis of astrocytic tumors. Furthermore, our findings suggest that loss of CDKN2/p16 expression may also play an important role in the progression of oligodendrogliomas. According to our findings CDKN2/p16 immunocytochemistry could be used as a tool to identify those oligodendrogliomas and low grade astrocytomas that are likely to progress and have poor outcome, and thus would need more aggressive therapy.

Adolescent↗
PubMed1999

Characterization of chromosomal abnormalities in prostate cancer cell lines by spectral karyotyping.

Human prostate cancer is characterized by multiple gross chromosome alterations involving several chromosome regions. However, the specific genes involved in the development of prostate tumors are still largely unknown. Here we have studied the chromosome composition of the three established prostate cancer cell lines, LNCaP, PC-3, and DU145, by spectral karyotyping (SKY). SKY analysis showed complex karyotypes for all three cell lines, with 87, 58/113, and 62 chromosomes, respectively. All cell lines were shown to carry structural alterations of chromosomes 1, 2, 4, 6, 10, 15, and 16; however, no recurrent breakpoints were detected. Compared to previously published findings on these cell lines using comparative genomic hybridization, SKY revealed several balanced translocations and pinpointed rearrangement breakpoints. The SKY analysis was validated by fluorescence in situ hybridization using chromosome-specific, as well as locus-specific, probes. Identification of chromosome alterations in these cell lines by SKY may prove to be helpful in attempts to clone the genes involved in prostate cancer tumorigenesis.

Aneuploidy↗
PubMed1999

Mechanical loading regulates tenascin-C expression in the osteotendinous junction.

Elastic extracellular matrix protein tenascin-C (TN) has very restricted expression in normal tissues, but is expressed in large quantities during embryogenesis and hyperplastic processes. To examine the importance of mechanical stress on the regulation of TN expression in vivo, the effects of various mechanical loading states (immobilization and three forms of subsequent remobilization) on the expression of TN were studied immunohistochemically at the bone-tendon attachment of the rat quadriceps muscle. This osteotendinous junction (OTJ) was selected as study site, since it receives its mechanical stimuli only from muscle contracting activity, which is easy to block by cast immobilization. TN was expressed abundantly in the normal OTJ. Following the removal of the mechanical stress from the junction by cast-immobilization of three weeks, the immunoreactivity of TN was almost completely absent. Normal mechanical stress in the form of free remobilization of eight weeks (free cage activity) resulted in a slight increase in TN expression, but could not restore the expression of TN to the level of the healthy contralateral leg. After the application of the increased mechanical stress (intensified remobilization of the eight weeks by low- or high-intensity treadmill running), the distribution and immunoreactivity of TN reached the level of the healthy contralateral limb in the low-intensity running group or even exceeded that in the high-intensity running group. High TN expression was seen around the chondrocytes and fibroblasts of the OTJ as well as around the collagen fibers of the tendon belly. We conclusively show that mechanical strain regulates the expression of TN in vivo, and propose that mechanical stress is a major regulator of TN expression in fibroblasts and chondrocytes. This may be an important aspect of the regulation of TN expression during embryogenesis, tendon degeneration, wound healing, bone formation, and in the other normal or regenerative morphogenetic processes TN is postulated to take part in.

Animals↗
PubMed1999

Chromosomal aberrations in breast cancer: a comparison between cytogenetics and comparative genomic hybridization.

The analysis of chromosomal imbalances in solid tumors using comparative genetic hybridization (CGH) has gained much attention. A survey of the literature suggests that CGH is more sensitive in detecting copy number aberrations than is karyotyping, although careful comparisons between CGH and cytogenetics have not been performed. Here, we compared cytogenetics and CGH in 29 invasive breast cancers after converting the karyotypes into net copy number gains and losses. We found 15 tumors (56%) with a significant agreement between the two methods and 12 tumors (44%) where the methods were in disagreement (two cases failed CGH analysis). Interestingly, in 13 of the 15 tumors where the two methods were concordant, there was also a strong correlation between chromosome index and DNA index by flow cytometry. In the opposite situation, i.e., when chromosome and DNA indices were not matching, there was disagreement between cytogenetics and CGH in 10 of the 12 tumors. Of the discordant cases, all except one had a "simple" abnormal karyotype. Unresolved chromosomal aberrations (marker chromosomes, homogeneously staining regions, double minutes) could not completely explain the differences between CGH and karyotyping. A likely explanation for the discrepancies is that the methods analyzed different cell populations. Gains and losses found by CGH represented the predominant (often aneuploid) clone, whereas the abnormal, near-diploid karyotypes represented minor cell clone(s), which, for unknown reasons, had a growth advantage in vitro.

Aneuploidy↗
PubMed1999

Characterization of topoisomerase II alpha gene amplification and deletion in breast cancer.

Topoisomerase IIalpha (TOP2A) is a key enzyme in DNA replication and a molecular target for many important anticancer drugs. TOP2A is amplified or deleted together with amplification of the closely located ERBB2/HER-2/neu oncogene in breast cancer. We characterized the copy number aberrations of TOP2A and ERBB2 in 136 primary breast tumors by FISH. Among the 70 primary tumors with ERBB2 amplification, amplification of TOP2A was found in 29 (41%); 30 tumors (43%) showed a physical deletion of TOP2A; and the copy number for TOP2A was not altered in 11 tumors with ERBB2 amplification (16%). No TOP2A gene aberrations were identified in 65 primary tumors without ERBB2 amplification. Fiber FISH revealed that simultaneously amplified ERBB2 and TOP2A were not present in the same amplicon, because repetitive tandem repeat-like signals of ERBB2 and TOP2A were in separate DNA fibers. The deletion of TOP2A (seen in the MDA-361 cell line and in 31 primary tumors) was interstitial, spanning less than two megabases of DNA. Mean copy numbers of TOP2A (2.4 +/- 0.6 for TOP2A vs. 4.9 +/- 1.1 for chromosome 17 centromere) suggest that the deletion of TOP2A occurs before polyploidization of the genome. Eight primary tumors with high-level ERBB2 amplification showed a new type of intratumoral heterogeneity; two different cell clones with either high-level amplification or deletion of TOP2A were found adjacent to each other in the same tumor. These results indicate that amplification of the ERBB2 oncogene is followed by complex secondary genetic aberrations, which lead to amplification or deletion of the TOP2A gene in a majority of tumors. Genes Chromosomes Cancer 26:142-150, 1999.

Antigens, Neoplasm↗
PubMed1999

Genetic alterations in ERBB2-amplified breast carcinomas.

Amplification of the ERBB2 oncogene has recently received attention as a target for antibody-based therapies and as a predictor of response to adjuvant chemotherapy. Modification of treatment strategies based on ERBB2 status has led to further interest in the genetic alterations that accompany ERBB2 gene amplification or overexpression. In this study, chromosome alterations that are associated with ERBB2 amplification were defined by comparative genomic hybridization (CGH). Additionally, fluorescence in situ hybridization (FISH) was used to validate gene amplification, and protein expression was detected immunohistochemically. ERBB2-amplified tumors as detected by FISH, immunohistochemistry (IHC), or CGH had twice as many CGH-defined chromosomal alterations (means of 11.8, 11.0, and 12.7, respectively) as the nonamplified tumors (means of 6.8, 7.0, and 5.6, respectively). ERBB2 positivity correlated with the total number of genetic events. A wide spectrum of copy number gains and losses was seen by CGH in all of the tumors. An increased number of losses of 18q and gains of 20q was found in ERBB2-positive tumors. Other common aberrations for all of the tumors were copy number gains of 1q (58%), 8q (52%), 20q (30%), and losses of 18q (39%), 13q (39%), and 3p (33%). A high degree of concordance was observed among the three methods in 33 primary breast cancers. The concurrence for ERBB2 detection between FISH and IHC was 90%, between FISH and CGH was 82%, and between IHC and CGH was 84%. This study shows that breast tumors showing erbB2 overexpression or gene amplification are genetically distinct from erbB2-negative tumors. These differences may relate to the mechanisms underlying altered response to adjuvant therapies and may define the responsiveness to erbB2-directed immunotherapy.

Breast Neoplasms↗
PubMed1999

Four-color CGH: a new method for quality control of comparative genomic hybridization.

Comparative genomic hybridization (CGH) has become a widely used method in molecular cytogenetics to screen for copy number aberrations in human malignancies. Although the hybridization protocol is relatively simple, the validation and quality control of CGH have remained difficult. We describe here a new modification of CGH, four-color CGH, which is based on conventional CGH with an added Cy5-labeled second reference DNA, that serves as an internal standard in every hybridization. The internal standard aids in identifying inconsistently hybridized chromosomal regions (such as 1pter, 19, 22). When using a special second reference DNA (from a sex-mismatched trisomy 13 cell line) for four-color CGH, it is possible to standardize the dynamic range of hybridization. The four-color CGH modification is simple to adopt, requiring only the addition of Cy5-labeled reference DNA to the existing hybridization protocol. The principles and the modifications of the CGH image analysis software are described in detail.

Breast Neoplasms↗
PubMed1998

Positional cloning of ZNF217 and NABC1: genes amplified at 20q13.2 and overexpressed in breast carcinoma.

We report here the molecular cloning of an approximately 1-Mb region of recurrent amplification at 20q13.2 in breast cancer and other tumors and the delineation of a 260-kb common region of amplification. Analysis of the 1-Mb region produced evidence for five genes, ZNF217, ZNF218, and NABC1, PIC1L (PIC1-like), CYP24, and a pseudogene CRP (Cyclophillin Related Pseudogene). ZNF217 and NABC1 emerged as strong candidate oncogenes and were characterized in detail. NABC1 is predicted to encode a 585-aa protein of unknown function and is overexpressed in most but not all breast cancer cell lines in which it was amplified. ZNF217 is centrally located in the 260-kb common region of amplification, transcribed in multiple normal tissues, and overexpressed in all cell lines and tumors in which it is amplified and in two in which it is not. ZNF217 is predicted to encode alternately spliced, Kruppel-like transcription factors of 1,062 and 1,108 aa, each having a DNA-binding domain (eight C2H2 zinc fingers) and a proline-rich transcription activation domain.

Amino Acid Sequence↗
PubMed1998

Effect of radiotherapy on the interpretation of routine follow-up mammography after conservative breast surgery: a randomized study.

Radiotherapy after conservative surgery causes fat necrosis, fibrosis, skin thickening and other parenchymal distortion of the breast. The interpretation of a mammogram of the irradiated breast may therefore be difficult. We studied the effect of radiotherapy on the interpretation of the routine mammography used in the follow-up of breast cancer patients. A total of 144 low-risk breast cancer patients were randomized to radiotherapy or to no further treatment after conservative surgery. The first routine follow-up mammography was performed 18 months after surgery and every 18 months after that. The number of mammography examinations was estimated per patient and per follow-up year. The number of extra diagnostic tests and the occurrence of positive findings were assessed per mammography session and per follow-up year. Further diagnostic tests prompted by difficulties in interpreting the mammogram were performed to an extent of 0.19 per mammography examination in the radiotherapy group and of 0.15 in the non-radiotherapy group, i.e. 1.3 times more often. Findings that turned out to be negative at confirmation were 2.0 times (P< 0.05) more common in the radiotherapy group. These false-positive findings were more common in the radiotherapy group than in the surgery group and only shortly after treatment. Mammography is more difficult to interpret after radiotherapy than after conservative surgery alone, especially shortly after treatment, and more often involves extra diagnostic tests and findings that will be negative at confirmation.

Breast Neoplasms↗
PubMed1998

Low biologic aggressiveness in breast cancer in women using hormone replacement therapy.

PURPOSE: Hormone replacement therapy (HRT) has been associated with an increased risk for breast cancer. Cancers in women who use HRT are often less advanced, and lower mortality has been reported in those who use HRT than in nonusers. We sought to explain this by a comparison of indicators of tumor aggressiveness in patients who received HRT with those in patients who did not. PATIENTS AND METHODS: A population-based cohort of 477 postmenopausal women with breast cancer were interviewed for the use, type, and duration of HRT. Clinical variables and indicators of tumor aggressiveness (histologic grade, hormone receptors, DNA ploidy, S-phase fraction, and c-erbB-2 oncoprotein overexpression) were analyzed. RESULTS: Breast tumors from HRT users were smaller (odds ratio, 0.47; P=.005), had better histologic differentiation (P=.04), and had a lower proliferation rate (S-phase fraction, P=.009) than tumors from nonusers. These differences persisted after adjustments for age and method of diagnosis (mammography screening v self-referral) by multiple logistic regression. No significant differences were observed in the estrogen (ER) or progesterone receptor content, c-erbB-2 oncogene overexpression, or axillary node involvement. A subgroup analysis showed that the tumor proliferation rates among HRT users were significantly lower only if HRT had been used at the time of diagnosis (P=.001). The type of HRT (estrogen v combination of estrogen and progesterone) was not associated with any clinical parameter or tumor phenotype. The association of HRT with lower proliferation rate and smaller tumor size was exclusively caused by ER-positive tumors (P=.0001 and P=.0035 v P > .1, respectively). CONCLUSION: The results indicate that breast cancer in women who receive HRT is biologically less aggressive than those without previous HRT. The lower cell-proliferation rate and smaller tumor size found in ER-positive tumors from current HRT users suggest a direct ER-mediated growth inhibitory effect of HRT on established breast tumors. This may at least partly explain why breast cancer in HRT users has a more favorable clinical course.

Aged↗
PubMed1998

Molecular cytogenetics of primary breast cancer by CGH.

Comparative genomic hybridization (CGH) reveals DNA sequence copy number changes that are shared among the different cell subpopulations present in a tumor and may help to delineate the average progression pathways of breast cancer. Previous CGH studies of breast cancer have concentrated on selected subgroups of breast cancer. Here, 55 unselected primary breast carcinomas were analyzed using optimized quality-controlled CGH procedures. Gains of 1q (67%) and 8q (49%) were the most frequent aberrations. Other recurrent gains were found at 33 chromosomal regions, with 16p, 5p12-14, 19q, 11q13-14, 17q12, 17q22-24, 19p, and 20q13 being most often (> 18%) involved. Losses found in > 18% of the tumors involved 8p, 16q, 13q, 17p, 9p, Xq, 6q, 11q, and 18q. The total number of aberrations per tumor was highest in poorly differentiated (P = 0.01) and in DNA aneuploid (P = 0.05) tumors. The high frequency of 1q gains and presence of +1q as the sole abnormality suggest that it is an early genetic event. In contrast, gains of 8q were most common in genetically and phenotypically advanced breast cancers. The vast majority of breast cancers (80%) have gains of 1q, 8q, or both, and 3 changes (+1q, +8q, or -13q) account for 91% of the tumors. In conclusion, CGH results indicate that certain chromosomal imbalances are very often selected for, sometimes in a preferential order, during the progression of breast cancer. Further studies of such common changes may form the basis for a molecular cytogenetic classification of breast cancer.

Adult↗
PubMed1997

Genetic alterations in lobular breast cancer by comparative genomic hybridization.

Infiltrating lobular carcinoma (ILC) and infiltrating ductal carcinoma (IDC) are distinguished by their histopathological appearance. However, little is known about the differences in genetic changes between lobular cancers and ductal cancers. We used comparative genomic hybridization (CGH) and compared aberrations in 19 ILCs and 46 IDCs. The total number of aberrations was lower in ILC than in IDC. While the average number of DNA copy number losses did not reach significance between them, copy number gains were significantly lower in ILCs. Fifteen of 19 ILCs (79%) showed increased copy number of 1q, and 12 cases (63%) revealed loss of 16q. The presence of these aberrations was independent of nodal status, histologic subtypes (pleomorphic or classic ILC), or BrdUrd-labeling index. ILCs had a higher frequency of 16q loss than did ductal cancers, and a lower frequency of 8q and 20q gains. Our data suggest that the altered growth pattern and clinical presentation which characterize infiltrating lobular cancers are correlated with distinct genetic alterations.

Adult↗
PubMed1997

Immunochemical characterization of a novel mitochondrially located protein encoded by a nuclear gene within the DFNB8/10 critical region on 21q22.3.

A novel protein encoded by the C210RF2 gene in chromosomal locus 21q22.3 was characterized by immunochemistry. This chromosomal region is known to contain genes for human diseases such as non-syndromic autosomal recessive deafness (DFNB8/10) and autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED). Polyclonal murine antisera were produced against the multivalent peptides deduced from the amino acid sequence of the polypeptide. Immunological reactivity of the obtained antisera was tested with primary cells or established cell lines. On western blotting, the polyclonal sera recognized a single protein product of 25 Kd expressed in cell lines of epithelial and lymphoid origin. Subsequent immunochemistry of several human tissues indicated the ubiquitous expression of the protein. Immunofluorescence studies and co-staining with a mitochondrial-specific dye suggest the subcellular localization of the protein to mitochondria. Mitochondrial localization is also predicted by computer analysis of the polypeptide sequence. As deafness is known to be caused in some instances by defects in mitochondrial function, C210RF2 is a plausible candidate gene for DFNB8/10.

Amino Acid Sequence↗
PubMed1997

Genetic heterogeneity and clonal evolution underlying development of asynchronous metastasis in human breast cancer.

To understand the genetic basis and clonal evolution underlying metastatic progression of human breast cancer in vivo, we analyzed the genetic composition of 29 primary breast carcinomas and their paired asynchronous metastases by comparative genomic hybridization and fluorescence in situ hybridization. The mean number of genetic changes by comparative genomic hybridization was 8.7 +/- 5.3 in primary tumors and 9.0 +/- 5.7 in their metastases. Although most of the genetic changes occurred equally often in the two groups, gains of the Xq12-q22 region were enriched in the metastases. According to a statistical analysis of shared genetic changes and breakpoints in paired specimens, 20 of the metastases (69%) showed a high degree of clonal relationship with the corresponding primary tumor, whereas the genetic composition of 9 metastases (31%) differed almost completely from that of the paired primary tumors. In both groups, however, chromosome X inactivation patterns suggested that the metastatic lesions originated from the same clone as the primary tumor. Fluorescence in situ hybridization analysis with probes specific to metastatic clones usually failed to find such cells in the primary tumor sample. In conclusion, detailed characterization of the in vivo progression pathways of metastatic breast cancer indicates that a linear progression model is unlikely to account for the progression of primary tumors to metastases. An early stem line clone apparently evolves independently in the primary tumor and its metastasis, eventually leading to multiple, genetically almost completely different, clones in the various tumor locations in a given patient. The resulting heterogeneity of metastatic breast cancer may underlie its poor responsiveness to therapy and explain why biomarkers of prognosis or therapy responsiveness measured exclusively from primary tumors give a restricted view of the biological properties of metastatic breast cancer.

Adenocarcinoma↗
PubMed1997

Distinct somatic genetic changes associated with tumor progression in carriers of BRCA1 and BRCA2 germ-line mutations.

BRCA1 and BRCA2 mutations confer increased risk for development of breast cancer, but a number of additional, currently largely unknown, somatic genetic defects must also accumulate in the breast epithelial cells before malignancy develops. To evaluate the nature of these additional somatic genetic defects, we performed a genome-wide survey by comparative genomic hybridization on breast cancers from 21 BRCA1 mutation carriers, 15 BRCA2 mutation carriers, and 55 unselected controls. The total number of genetic changes was almost two times higher in tumors from both BRCA1 and BRCA2 mutation carriers than in the control group. In BRCA1 tumors, losses of 5q (86%), 4q (81%), 4p (64%), 2q (40%), and 12q (40%) were significantly more common than in the control group (7-13%). BRCA2 tumors were characterized by a higher frequency of 13q (73%) and 6q (60%) losses and gains of 17q22-q24 (87%) and 20q13 (60%) as compared to the prevalence of these changes in the control group (12-18%). In conclusion, accumulation of somatic genetic changes during tumor progression may follow a unique pathway in individuals genetically predisposed to cancer, especially by the BRCA1 gene. Activation or loss of genes in the affected chromosomal regions may be selected for during tumor progression in cells lacking functional BRCA1 or BRCA2. Identification of such genes could provide targets for therapeutic intervention and early diagnosis.

Adult↗
PubMed1997

Androgen receptor gene amplification: a possible molecular mechanism for androgen deprivation therapy failure in prostate cancer.

Progression of prostate cancer during endocrine therapy is a major clinical problem, the molecular mechanisms of which remain poorly understood. Amplification of the androgen receptor (AR) gene was recently described in recurrent prostate carcinomas from patients who had failed androgen deprivation therapy. To evaluate the hypothesis that amplification of the AR gene is a cause for the failure of androgen deprivation therapy in prostate cancer, we studied whether AR amplification leads to gene overexpression, whether the amplified AR gene is structurally intact, and whether tumors with AR amplification have distinct biological and clinical characteristics. Tumor specimens were collected from 54 prostate cancer patients at the time of a local recurrence following therapy failure. In 26 cases, paired primary tumor specimens from the same patients prior to therapy were also available. Fifteen (28%) of the recurrent therapy-resistant tumors, but none of the untreated primary tumors, contained AR gene amplification as determined by fluorescence in situ hybridization. According to single-stranded conformation polymorphism analysis, the AR gene was wild type in all but one of the 13 AR amplified cases studied. In one tumor, a presumed mutation in the hormone-binding domain at codon 674 leading to a Gly --> Ala substitution was found, but functional studies indicated that this mutation did not change the transactivational properties of the receptor. AR amplification was associated with a substantially increased level of mRNA expression of the gene by in situ hybridization. Clinicopathological correlations indicated that AR amplification was most likely to occur in tumors that had initially responded well to endocrine therapy and whose response duration was more than 12 months. Tumors that recurred earlier or those that showed no initial therapy response did not contain AR amplification. The median survival time after recurrence was two times longer for patients with AR amplification in comparison to those with no amplification (P = 0.03, Willcoxon-Breslow test). In conclusion, failure of conventional androgen deprivation therapy in prostate cancer may be caused by a clonal expansion of tumor cells that are able to continue androgen-dependent growth despite of the low concentrations of serum androgens. Amplification and the increased expression of a wild-type AR gene may play a key role in this process.

Aged↗