Biomedical subjects

L Gorunova

Publications and source records attributed to L Gorunova.

At least 19 recordsLinked to original sources

PubMed2004

Telomere shortening and mitotic dysfunction generate cytogenetic heterogeneity in a subgroup of renal cell carcinomas.

Most renal cell carcinomas (RCC) show only simple chromosomal changes. However, a more complex cytogenetic pattern has been found in a subgroup of aggressive RCC, indicating that further accumulation of chromosome changes could play a role in tumour progression. To explore the possible mechanisms behind cytogenetic evolution in RCC, a parallel assessment of chromosome mutations and mitotic segregation pattern in eight tumours was performed. In the majority of cases, no abnormalities in the cell division machinery were found and the rate of alterations in chromosome copy number, as measured by interphase FISH, was similar to that in non-neoplastic cells. This was reflected by relatively simple karyotypes, with little cytogenetic intratumour heterogeneity. In contrast, another group of tumours exhibited several cytogenetically related clones with additional structural chromosomal changes at two or more ploidy levels and a frequency of copy number alterations that was higher than in normal cells. In these cases, the telomere repeat sequences were abnormally short and chromosomal breakage-fusion-bridge events were observed at cell division, as well as multipolar configurations and supernumerary centrosomes. Abnormalities of the cell division machinery may thus contribute to the evolution of complex karyotypes and genetic intratumour heterogeneity in a subgroup of RCC.

Adult↗

PubMed2001

Characterization of chromosomal abnormalities in uroepithelial carcinomas by G-banding, spectral karyotyping and FISH analysis.

Chromosome analysis by G-banding, spectral karyotyping (SKY) and fluorescence in situ hybridization (FISH) was performed on 24 short-term cultured transitional cell bladder carcinomas and 5 cell lines established from bladder carcinomas. Except for one tumor with an apparently normal chromosomal constitution, clonal chromosome abnormalities were detected in all examined cases by the combined approach. The application of SKY and FISH techniques improved the karyotypic descriptions, originally based on G-banding only, by identifying 32 additional numerical changes, by establishing the chromosomal origin of 27 markers and 2 ring chromosomes, by redefining 53 aberrations and by detecting 15 hidden chromosomal rearrangements. No recurrent translocation, however, was detected. The most prominent karyotypic feature was thus the occurrence of deletions and losses of whole chromosome copies indicating the importance of tumor suppressor genes in transitional cell carcinoma pathogenesis. Invasive carcinomas were karyotypically more complex than were low grade superficial tumors. Specific losses of material from chromosome 9 and from chromosome arms 11p and 8p, and gains of 8q and 1q seem to be early changes appearing in superficial tumors, whereas losses from 4p and 17p and the formation of an isochromosome for 5p were associated with more aggressive tumor phenotypes.

Aged↗

PubMed2001

Extensive cytogenetic heterogeneity in a benign retroperitoneal schwannoma.

A benign retroperitoneal schwannoma from a patient without prior exposure to radiotherapy or chemotherapy was analyzed by chromosome banding after short-term culture. An extensive intratumor heterogeneity in the form of 29 karyotypically related as well as unrelated clones was found. The aberrant clones were diploid or near-diploid and displayed both numerical and structural changes. All chromosomes, except 11, 16, and 20, were affected. Numerical changes included trisomies X, 7, 9, 17, and 18, and monosomies 13 and 18. No clonal loss of chromosome 22, the most characteristic abnormality in schwannomas of other locations, was, however, detected. The structural aberrations resulted in a total of 58 chromosomal breakpoints, with chromosomes 18, 1, and 15 participating in rearrangements most frequently, followed by chromosomes 14, 2, and 22. A striking finding was the clonal involvement of 18p11 in eight rearrangements affecting different chromosomes, suggesting alteration of telomeric function. The molecular mechanisms underlying the observed massive polyclonality in the schwannoma, particularly the presence of cytogenetically unrelated clones, are unknown and probably heterogeneous.

Aged↗

PubMed2001

Altered expression of TGFB receptors and mitogenic effects of TGFB in pancreatic carcinomas.

Alteration of the transforming growth factor beta (TGFB) signalling pathway is important in pancreatic carcinogenesis, as shown by the frequent inactivation of the downstream target SMAD4. We recently analysed a series of pancreatic carcinoma cell lines with respect to alterations of five SMAD genes involved in TGFB signalling, and showed that SMAD4 was structurally rearranged in 42% of these. This pathway may, however, also be affected by alterations of genes whose products regulate the activation of TGFB as well as of TGFB receptor genes. We therefore studied the expression of UPA, UPAR, IGF2R, ALK5 (TGFBR1), TGFBR2, TGFBR3, ENG, ALK1, TGFB1, TGFB2, and TGFB3 in a series of 14 pancreatic carcinoma cell lines. We also analysed ALK5 and TGFBR2 for mutations, cell surface localisation of TGFBR2 and ENG, and TGFB1 response. No mutations of ALK5 or TGFBR2 were found. However, 4 cell lines were methylated within the ALK5 promoter region. ALK5 expression was strongly reduced in 9 cases, whereas TGFBR2 expression was increased in 12 of the cell lines. The TGFB signalling associated receptors ENG and ALK1 were co-expressed in 4 of the cell lines. There was no evidence for disruption of the UPAR-IGF2R TGFB activating pathway. The response to TGFB1 was analysed in 12 cell lines, and 6 of these (50%) showed increased proliferation. The cell lines stimulated by TGFB showed frequent mutations of SMAD4, KRAS2, and TP53, as well as frequent absence of CDKN2B expression. These results suggest that the ALK5-SMAD4 part of the TGFB signalling pathway is a major target for inactivation in pancreatic carcinomas, that the expression of TGFBR2, TGFBR3, and receptors involved in TGFB activation are maintained, and that alterations of components of the TGFB signalling pathway may be accompanied by a positive effect of TGFB on cell growth.

Activin Receptors, Type I↗

PubMed2000

Chromosomal breakage-fusion-bridge events cause genetic intratumor heterogeneity.

It has long been known that rearrangements of chromosomes through breakage-fusion-bridge (BFB) cycles may cause variability of phenotypic and genetic traits within a cell population. Because intercellular heterogeneity is often found in neoplastic tissues, we investigated the occurrence of BFB events in human solid tumors. Evidence of frequent BFB events was found in malignancies that showed unspecific chromosome aberrations, including ring chromosomes, dicentric chromosomes, and telomeric associations, as well as extensive intratumor heterogeneity in the pattern of structural changes but not in tumors with tumor-specific aberrations and low variability. Fluorescence in situ hybridization analysis demonstrated that chromosomes participating in anaphase bridge formation were involved in a significantly higher number of structural aberrations than other chromosomes. Tumors with BFB events showed a decreased elimination rate of unstable chromosome aberrations after irradiation compared with normal cells and other tumor cells. This result suggests that a combination of mitotically unstable chromosomes and an elevated tolerance to chromosomal damage leads to constant genomic reorganization in many malignancies, thereby providing a flexible genetic system for clonal evolution and progression.

Chromosome Aberrations↗

PubMed2000

Locus-specific multifluor FISH analysis allows physical characterization of complex chromosome abnormalities in neoplasia.

Novel techniques in molecular cytogenetics have radically improved the ability to characterize genetic changes in neoplastic cells. In parallel, a rapid development in high-throughput genomics has resulted in detailed physical maps of the human genome. Combining these two fields, we have developed a method for the simultaneous visualization of several physically defined segments along a chromosome. Seven YAC clones and one subtelomeric cosmid clone from chromosome 12 were labeled with unique combinations of four fluors and hybridized to metaphase chromosomes from neoplastic cells. In a uterine leiomyoma and a myxoid liposarcoma with translocations 12;14 and 12;16, the breakpoints in chromosome 12 could be localized to the HMGIC and CHOP regions, respectively. In the other tumors, more complex aberrations were visualized, including two inversions in 12q with a common breakpoint between MDM2 and D12S332 in a pleomorphic adenoma, amplification of MDM2 and CDK4 in ring chromosomes from a malignant fibrous histiocytoma, and amplification of KRAS2 together with other unbalanced rearrangements in two pancreatic adenocarcinomas. Combinatorially labeled single-copy probes may thus simultaneously provide physical localization of breakpoints and an overview of complex structural rearrangements. Genes Chromosomes Cancer 28:347-352, 2000.

Chromosome Aberrations↗

PubMed2000

Characterization of genomically amplified segments using PCR: optimizing relative-PCR for reliable and simple gene expression and gene copy analyses.

Gene amplification is one of the mechanisms for oncogene activation in solid tumors. The size of the amplified regions may vary considerably among individual tumors, and more than one gene may be affected within the same amplicon. The main objective in analyzing genomic amplifications has therefore been to map the shortest region involved and to identify genes with increased expression as a result of the increased gene copy number. To facilitate such an analysis, we have developed simple polymerase chain reaction (PCR) procedures using the internal standards beta-actin (ACTB) and L1Hs for gene expression and gene copy number analyses, respectively. We used cDNA derived from pancreatic carcinoma cell lines, and genomic DNA extracted from the same cell lines, as templates in the gene expression and in the gene copy number analyses, respectively. To determine the optimal number of PCR cycles, dilution series of the templates were made. Furthermore, competing primers were used to adjust for differences in target sequence levels. We show that by these simple means it is possible to determine optimal conditions for expression analyses. In addition, the procedure was adapted for the analysis of gene copy number changes at the genomic level using L1Hs as the internal standard. This PCR method makes it possible to produce detailed gene copy number profiles of amplified genomic regions.

DNA Primers↗

PubMed2000

Karyotypic characterization of urinary bladder transitional cell carcinomas.

Samples from 34 primary transitional cell carcinomas (TCCs) of the bladder were short-term-cultured and processed for cytogenetic analysis after G-banding of the chromosomes. Clonal chromosome abnormalities were detected in 27 tumors and normal karyotypes in 3, and the cultures from 4 tumors failed to grow. Losses of genetic material were more common than gains, indicating that loss of tumor suppressor genes may be of major importance in TCC pathogenesis. There was no clonal heterogeneity within individual tumors, consonant with the view that TCCs are monoclonal in origin. The most striking finding was the involvement of chromosome 9 in 92% of the informative cases, as numerical loss of one chromosome copy in 15 cases, but as structural rearrangement in 8. The changes in chromosome 9 always led to loss of material; from 9p, from 9q, or of the entire chromosome. A total of 16 recurrent, unbalanced structural rearrangements were seen, of which del(1)(p11), add(3)(q21), add(5)(q11), del(6)(q13), add(7)(q11), add(11)(p11), i(13)(q10), del(14)(q24), and i(17)(q10) are described here for the first time. The karyotypic imbalances were dominated by losses of the entire or parts of chromosome arms 1p, 9p, 9q, 11p, 13p, and 17p, loss of an entire copy of chromosomes 9, 14, 16, 18, and the Y chromosome, and gains of chromosome arms 1q and 13q and of chromosomes 7 and 20. The chromosome bands and centomeric breakpoints preferentially involved in structural rearrangements were 1q12, 2q11, 5q11, 8q24, 9p13, 9q13, 9q22, 11p11, and 13p10. Rearrangements of 17p and the formation of an i(5)(p10) were associated with more aggressive tumor phenotypes. There was also a general correlation between the tumors' grade/stage and karyotypic complexity, indicating that progressive accumulation of acquired genetic alterations is the driving force behind multistep bladder TCC carcinogenesis.

Adult↗

PubMed1999

Molecular analyses of the 15q and 18q SMAD genes in pancreatic cancer.

SMAD4 (DPC4) is part of the TGFB signaling pathway and is frequently inactivated in pancreatic carcinomas. TGFB signals from the membrane to the nucleus via SMAD proteins. TGFB receptor activation results in SMAD2 and SMAD3 phosphorylation, which then form heteromeric complexes with SMAD4. Inhibitory SMADs, SMAD6 and SMAD7, can prevent TGFB signaling by interacting either with the receptor or with SMAD2 and SMAD3. The encoding sequences for these proteins are organized in two gene clusters, one at 18q21 (SMAD2, SMAD4, and SMAD7) and the other at 15q21-22 (SMAD3 and SMAD6). Losses of 15q and 18q material are frequent in pancreatic carcinomas, and in order to map the extent of 15q and 18q deletions and to investigate further the involvement of SMAD4 and the possible function of SMAD2 and SMAD3 as tumor suppressor genes in pancreatic carcinoma, we performed loss of heterozygosity studies as well as mutation and expression analyses of SMAD4, SMAD2, and SMAD3 in 13 low-passage cell lines from 12 pancreatic carcinoma patients. To investigate possible amplifications of SMAD6 and SMAD7, the genomic organization and the expression levels of these genes were analyzed. One tumor with homozygous loss of SMAD4 was detected, and mutations of this gene were found in four of the 12 carcinomas; no SMAD2 or SMAD3 inactivating genomic alterations were found. In none of the cases was transcriptional silencing seen. No genomic amplifications, mutations, or increased expression of SMAD6 and SMAD7 were detected. These results suggest that functional abrogation of SMAD2 or SMAD3 and increased expression of SMAD6 or SMAD7 are infrequent in pancreatic carcinomas and further stress the particular importance of SMAD4 inactivation in pancreatic carcinogenesis.

Aged↗

PubMed1999

Nonrandom chromosomal aberrations and cytogenetic heterogeneity in gallbladder carcinomas.

Chromosome banding analysis of 11 short-term cultured gallbladder carcinomas revealed acquired clonal aberrations in seven tumors (five primary and two metastases). Three of these had one clone, whereas the remaining four were cytogenetically heterogeneous, displaying two to seven aberrant clones. Of a total of 21 abnormal clones, 18 had highly complex karyotypes and three exhibited simple numerical deviations. Double minutes and homogeneously staining regions were observed in one and two carcinomas, respectively. To characterize the karyotypic profile of gallbladder cancer more precisely, we have combined the present findings with our three previously reported cases, thereby providing the largest cytogenetic database on this tumor type to date. A total of 287 chromosomal breakpoints were identified, 251 of which were found in the present study. Chromosome 7 was rearranged most frequently, followed by chromosomes 1, 3, 11, 6, 5, and 8. The bands preferentially involved were 1p32, 1p36, 1q32, 3p21, 6p21, 7p13, 7q11, 7q32, 19p13, 19q13, and 22q13. Nine recurrent abnormalities could, for the first time, be identified in gallbladder carcinoma: del(3)(p13), i(5)(p10), del(6)(q13), del(9)(p13), del(16)(q22), del(17)(p11), i(17)(q10), del(19)(p13), and i(21)(q10). The most common partial or whole-arm gains involved 3q, 5p, 7p, 7q, 8q, 11q, 13q, and 17q, and the most frequent partial or whole-arm losses affected 3p, 4q, 5q, 9p, 10p, 10q, 11p, 14p, 14q, 15p, 17p, 19p, 21p, 21q, and Xp. These chromosomal aberrations and imbalances provide some starting points for molecular analyses of genomic regions that may harbor genes of pathogenetic importance in gallbladder carcinogenesis. Genes Chromosomes Cancer 26:312-321, 1999.

Aged↗

PubMed1999

Cytogenetic analysis of upper urinary tract transitional cell carcinomas.

Ten primary (nine regular and one post-radiation) upper urinary tract transitional cell carcinomas (TCC), i.e., tumors of the renal pelvis and ureter, were obtained from 10 patients following nephroureterectomy and processed for cytogenetic analysis after short-term culturing. Clonal chromosomal aberrations were found in eight tumors. While 10 karyotypically related and/or unrelated clones were detected in the post-radiation tumor, cytogenetic monoclonality was seen in all other tumors. With the exception of two tumors with loss of the Y chromosome as the only change, chromosome 9 was invariably involved, either with loss of the entire chromosome or with partial loss from the short arm. Our findings indicate that the karyotypic profile of upper urinary tract TCC is identical to that of bladder TCC, an indication that the same pathogenetic mechanisms are at work in both regions.

Aged↗

PubMed1999

Cytogenetic monoclonality in multifocal uroepithelial carcinomas: evidence of intraluminal tumour seeding.

Twenty-one multifocal urinary tract transitional cell carcinomas, mostly bladder tumours, from a total of six patients were processed for cytogenetic analysis after short-term culturing of the tumour cells. Karyotypically related, often identical, cytogenetically complex clones were found in all informative tumours from each case, including the recurrent tumours. Rearrangement of chromosome 9, leading to loss of material from the short and/or the long arm, was seen in all cases, indicating that this is an early, pathogenetically important event in transitional cell carcinogenesis. The presence of related clones with great karyotypic similarity in anatomically distinct tumours from the same bladder indicates that multifocal uroepithelial tumours have a monoclonal origin and arise via intraluminal seeding of viable cancer cells shed from the original tumour. Later lesions may develop also from cells shed from the so called second primary tumours. The relatively complex karyotypes seen in all lesions from most cases argue that the seeding of tumour cells is a late event that succeeds the acquisition by them of multiple secondary genetic abnormalities.

Aged↗

PubMed1998

Chromosomal abnormalities in two bladder carcinomas with secondary squamous cell differentiation.

Two secondary squamous cell carcinomas of the bladder (i.e., tumors that originated from primary transitional cell carcinomas) were examined cytogenetically. Both tumors showed complex karyotypes with many of the same aberrations that have formerly been described in transitional cell carcinomas. Monosomy 9, trisomy 7, and rearrangements of chromosomes 3, 8, 10, 13, and 17 were common to both tumors. Among other changes that have been implicated in bladder carcinogenesis, an isochromosome for 5p was seen in one tumor and loss of 11p material in the other. Our findings indicate that secondary squamous cell carcinomas of the bladder are karyotypically indistinguishable from advanced transitional cell carcinomas of the same organ. The putative genetic changes that steer the differentiation of the neoplastic epithelium in the direction of squamous cells thus remain unknown.

Aged↗

PubMed1998

Cytogenetic analysis of pancreatic carcinomas: intratumor heterogeneity and nonrandom pattern of chromosome aberrations.

Twenty-nine nonendocrine pancreatic carcinomas (20 primary tumors and nine metastases) were studied by chromosome banding after short-term culture. Acquired clonal aberrations were found in 25 tumors and a detailed analysis of these revealed extensive cytogenetic intratumor heterogeneity. Apart from six carcinomas with one clone only, 19 tumors displayed from two to 58 clones, bringing the total number of clones to 230. Karyotypically related clones, signifying evolutionary variation, were found in 16 tumors, whereas unrelated clones were present in nine, the latter finding probably reflecting a distinct pathogenetic mechanism. The cytogenetic profile of pancreatic carcinoma was characterized by multiple numerical and structural changes. In total, more than 500 abnormal chromosomes, including rings, markers, homogeneously stained regions, and double minutes, altogether displaying 608 breakpoints, were detected. This complexity and heterogeneity notwithstanding, a nonrandom karyotypic pattern can be discerned in pancreatic cancer. Chromosomes 1, 3, 6, 7, 8, 11, 12, 17, and 19 and bands 1q12, 1q21, 3q11, 6p21, 6q21, 7q11, 7q22, 7q32, 11q13, 13cen, 14cen, 17q11, 17q21, and 19q13 were most frequently involved in structural rearrangements. A total of 19 recurrent unbalanced structural changes were identified, 11 of which were not reported previously: del(1)(q11), del(3)(p11), i(3)(q10), del(4)(q25), del(11)(p13), dup(11)(q13q23), i(12)(p10), der(13;15)(q10;q10), del(18)(q12), del(18)(q21), and i(19)(q10). The main karyotypic imbalances were entire-copy losses of chromosomes 18, Y, and 21, gains of chromosomes 7, 2, and 20, partial or whole-arm losses of 1p, 3p, 6q, 8p, 9p, 15q, 17p, 18q, 19p, and 20p, and partial or whole-arm gains of 1q, 3q, 5p, 6p, 7q, 8q, 11q, 12p, 17q, 19q, and 20q. In general, the karyotypic pattern of pancreatic carcinoma fits the multistep carcinogenesis concept. The observed cytogenetic heterogeneity appears to reflect a multitude of interchangeable but oncogenetically equivalent events, and the nonrandomness of the chromosomal alterations underscores the preferential pathways involved in tumor initiation and progression.

Abdominal Neoplasms↗

PubMed1998

Cytogenetic heterogeneity in a second primary radiation-induced bladder carcinoma: ten karyotypically unrelated clones.

Cytogenetic analysis of a transitional cell carcinoma (TCC) of the bladder, the tumor having developed 32 years after the patient received pelvic irradiation and interstitial radium implantation for an endometrial carcinoma, revealed the presence of 10 cytogenetically abnormal, unrelated clones. Although the tumor was poorly differentiated, all clones were pseudo- or near-diploid with rather simple balanced or unbalanced structural rearrangements or both. The chromosomes involved in structural changes more than once were chromosomes 8, 9, and 11, which were rearranged in three clones, and chromosomes 3 and 17, both rearranged in two clones. No previous TCC of the bladder with cytogenetically unrelated clones has been reported, nor has any such radiation-induced tumor with chromosomal abnormalities been described. The distinct karyotypic and clonal pattern of the case presented here is probably indicative of a carcinogenic field effect due to the previous pelvic irradiation. Postradiation bladder carcinomas thus seem to be distinct cytogenetically in addition to their known unique etiological and clinical features.

Aged↗

PubMed1998

Cytogenetic and FISH analyses of pancreatic carcinoma reveal breaks in 18q11 with consistent loss of 18q12-qter and frequent gain of 18p.

Chromosome 18 was analysed using a banding technique and fluorescence in situ hybridization (FISH) in 13 pancreatic carcinoma samples. The cytogenetic analysis revealed that chromosome 18 abnormalities were present in all cases and that several different rearrangements, such as translocations, deletions, dicentrics and ring chromosomes, were often found together. FISH mapping using 18q YAC probes showed that all tumours had lost at least one copy of 18q and that 18p was over-represented in 6 of the 13 cases. Furthermore, out of 13 identified deletion breakpoints on 18q, 11 were mapped to 18q11. The clustering of breaks close to the centromere indicates that loss of genes in bands 18q11 and 18q12, in addition to those located in 18q21, e.g. DPC4 and DCC, are important in the development of pancreatic tumours.

Aged↗

PubMed1998

Cytogenetic and fluorescence in situ hybridization analyses of chromosome 19 aberrations in pancreatic carcinomas: frequent loss of 19p13.3 and gain of 19q13.1-13.2.

Cytogenetic investigation of nine pancreatic carcinomas revealed structural rearrangements of chromosome 19 in eight cases, resulting in a high frequency of 19p losses and 19q gains. To characterize these imbalances further, we performed fluorescence in situ hybridization (FISH) analysis with 12 mapped and evenly distributed cosmids. The FISH study not only verified the cytogenetic findings but also disclosed additional chromosome 19 aberrations not detected by chromosome banding analysis. Seven carcinomas displayed 19p losses, always including 19p13.3, either through partial- or whole-arm deletions. Six cases showed gain of 19q, usually as one to two copies above the ploidy level. In one case, a high level of amplification in 19q13.1 was seen. The commonly overrepresented segment was 19q13.1-13.2. These results suggest that genes of importance in the development of pancreatic carcinomas are located in 19p13.3 and 19q13.1-13.2.

Aged↗

PubMed1998

Chromosome abnormalities in squamous cell carcinoma of the urethra.

Cytogenetic analysis of short-term cultured cells from a urethral squamous cell carcinoma showed the tumor to have an abnormal, karyotypically complex near-diploid clone as well as its near-tetraploid duplicate. This is the first urethral carcinoma with chromosomal abnormalities to be reported. Chromosomes Y, 2, 3, 4, 6, 7, 8, 11, and 20 were all involved in numerical and/or structural rearrangements. Of particular interest was the fact that no rearrangements of chromosomes 9 and 17, both almost ubiquitously involved in transitional cell carcinoma of the urinary tract, were seen.

Aged↗