Multiple sites of highly amplified DNA sequences detected by molecular cytogenetic analysis in HS-RMS-2, a new pleomorphic rhabdomyosarcoma cell line

A molecular cytogenetic analysis was performed on HS-RMS-2, a cell line established in this laboratory from a rare pleomorphic type of rhabdomyosarcoma. G-banding and multicolor-FISH analyses revealed that the cells have a complex chromosomal composition. Comparative genomic in situ hybridization (CGH) detected eight highly amplified regions at 1p36.1-p36.2, 1p31-p32, 1q21-q31, 8q12-q21, 8q24-qter, 11q12-q13, 12q13-q14 and 18q12-q22, suggesting the co-existence of multiple amplified oncogenes in these tumor cells. Reverse chromosome painting, using a probe regenerated by microdissection of a long marker chromosome, revealed the native location of three of eight possible genes to be on chromosomes 1p31-32, 12q14 and 18q21. FISH using BAC and cosmid probes revealed amplification of JUN (1p31), MYC (8q24), CCND1 (11q13), INT2 (11q13.3), MDM2 (12q14.3-q15) and MALT (18q21). These findings indicate that at least eight amplified oncogenes may contribute to the pathogenesis of a rare pleomorphic type of rhabdomyosarcoma. This new cell line should prove useful for in vitro preclinical studies of molecularly targeted therapies.     

Inactivation of MMAC1 in bladder transitional-cell carcinoma cell lines and specimens

We recently limited the location of a candidate tumor suppressor gene in invasive (T3a/b) bladder transitional-cell carcinoma (TCC) to a 2.5-cM region at chromosome 10q23.3. This region harbors the MMAC1/PTEN/TEP1 gene (referred to hereafter as MMAC1), a dual-phosphatase tumor-suppressor gene frequently inactivated in variety of malignant tumors. In the present study, we examined whether MMAC1 is a target for inactivation by mutations and deletions in bladder TCC cell lines and specimens. MMAC1 was inactivated by homozygous deletions and mutations in three (27%) of 11 bladder cancer cell lines. One cell line, UC-3, had homozygous deletions, and two other cell lines, T-24 and UC-9, had missense mutations. T-24 had also a nonsense mutation. However, none of the 33 bladder TCC specimens examined had a mutation or deletion in the coding region. These results suggest that MMAC1 is not the primary target for inactivation in bladder TCC and that another gene, in close proximity to the MMAC1 locus, within this region of frequent allelic losses, may be the target for inactivation.     

Delineation of the 6p22 amplification unit in urinary bladder carcinoma cell lines

Eight cell lines from transitional cell carcinoma of the urinary bladder were analyzed by comparative genomic hybridization. All tumor lines exhibited frequent chromosome gains (11.5/cell line) and losses (8.4/cell line). In six cell lines, gain of chromosome 5p was associated with gains of 6p and 20q. In five of these cell lines, amplification of parts of 6p was observed. Cytogenetic investigation combined with fluorescence in situ hybridization analysis revealed typical marker chromosomes with homogeneously staining regions (HSRs) containing material from 6p. By hybridizing individual yeast artificial chromosome probes from a chromosome 6p contig to these HSRs, a contig of three yeast artificial chromosomes common to all 6p HSRs was identified that spans less than 2 Mb. The genes SOX4 and PRL were shown to map to this region and to be coamplified in the cell lines. However, SOX4 was not overexpressed in any cell line and PRL was not expressed at all. Thus, the presumptive 6p oncogene remains to be conclusively identified.     

Establishment and characterization of a new human bladder cancer cell line showing features of squamous and glandular differentiation

Tumour-cell heterogeneity has been studied in a continuous cell line, UCRU-BL-17CL, established from a xenografted human primary bladder carcinoma. The cell line, grown in vitro for more than 30 generations, reflects the pathology of both the xenograft from which it was derived and the original human tumour. It comprises mainly adenocarcinoma cells which secrete mucin in vitro, as well as squamous and transitional carcinoma cells. Features of both adenocarcinomatous and squamous differentiation have been observed within the same cell. The line expresses ABH blood group isoantigens, binds to peanut lectin and reacts with monoclonal antibodies (MAbs) raised against keratin and against normal and malignant epithelial cells. It also reacts with MAbs against ras p21 proteins and the epidermal growth factor receptor (EGFR). It shows high levels of lactic acid dehydrogenase isozyme 5, consistent with a high-grade tumour, forms colonies in methylcellulose and is tumorigenic in nude mice. The karyotype (human) shows many marker chromosomes, consistent with expression of EGF receptors and ras p21 proteins, and an 11:13 translocation. DNA content, as studied by flow cytometry, reveals a shift from tetraploid to near triploid. This line may provide a useful model for studies of the histogenesis of bladder cancer and the relationship between transitional-cell carcinoma and the other histological subtypes of this disease.     

Assessment of microsatellite instability in urine in the detection of transitional-cell carcinoma of the bladder

Loss of heterozygosity (LOH) and alterations in microsatellite DNA markers have been reported in bladder-cancer tumors. We have studied, in a blinded fashion, using PCR-based microsatellite analysis, genetic alterations of cells exfoliated in urine of 59 Caucasian patients and control patients; 31 with initially confirmed bladder transitional-cell carcinoma (TCC), 17 with signs and symptoms suggestive of bladder cancer, 6 control patients who underwent renal transplantation, and 5 control patients with urolithiasis. Microsatellite analysis of cells exfoliated in the urine allowed the diagnosis of 83% (10/12) of patients with bladder TCC recurrence confirmed by cystoscopy, while 100% of patients followed up for transitional-cell carcinoma of the bladder for up to 12 months without evidence of tumor recurrence upon routine cystoscopy showed no microsatellite alterations. None of the patients without neoplasia (negative controls) had any microsatellite alterations, whereas all patients who underwent renal transplantation had additional new alleles corresponding to contamination with donor's renal and urothelial cells (positive controls). No control patients had any evidence of transitional-cell carcinoma by cystoscopy. Our results provide objective evidence that non-invasive molecular detection of bladder TCC by microsatellite analysis is reproducible with a sensitivity of 83% and a specificity of 100% in Caucasian patients. This non-invasive procedure represents a potential clinical tool for the detection and the screening of bladder TCC. Int. J. Cancer (Pred. Oncol.) 79:629–633, 1998. © 1998 Wiley-Liss, Inc.     

Microsatellite alterations in urinary sediments from patients with cystitis and bladder cancer

Microsatellite instability (MIN) and loss of heterozygosity (LOH) in bladder cancer have been suggested for diagnosis and follow-up of bladder cancer based on urinary sediments, reflecting tumor alterations. We have examined 6 microsatellites in urine sediments from 11 patients with transitional-cell carcinomas (TCC) and in 31 patients with benign prostatic hyperplasia (BPH), 22 of whom had cystitis. In the TCC patients, tumor tissue was available for comparison with urine. Microsatellites were amplified by PCR and compared with leukocyte DNA from the same individual in silver-stained gels. Altered mobility of bands, new bands and loss of bands were scored. We found MIN and LOH at relatively high frequency in markers from chromosomes 8 and 14 in urine from patients with TCC, but also in BPH patients who had cystitis. Even control patients with BPH without cystitis showed some instability and some losses. Novel bands in urine occurred significantly more often among TCC patients than among BPH patients with or without cystitis (p < 0.001). Band shifts in urine appeared to be more associated with BPH plus cystitis than with TCC. The alterations we found in urine from patients with bladder cancer did not always reflect those found in their tumors, the occurrence of novel bands being significantly higher (p < 0.008) in tumor tissue than in corresponding urine. In conclusion, microsatellite alterations in urine are indicators not only of malignancy but also of inflammatory conditions.     

Partial allelotype of schistosomiasis-associated bladder cancer

In Egypt and other regions of the Middle East where the trematode Schistosoma haematobium is endemic, bladder cancer is the most common adult cancer. Unlike bladder cancers in Western countries, which are predominantly transitional-cell carcinoma (TCC), these schistosomiasis-associated bladder cancers are predominantly squamous-cell carcinoma (SCC). Our aim was to assess a large series of schistosomiasis-associated bladder tumours for genetic alterations commonly found in TCC in the United Kingdom and the United States. We have carried out a partial allelotype of 70 tumours from patients with schistosomiasis. LOH was found on all chromosome arms studied (3p, 4p, 4q, 8p, 9p, 9q, 11p, 11q, 13q, 14q, 17p, 18q). The most frequent regions of LOH were 9p (65%), 17p (58%), 3p (40%), 9q (39%) and 8p (37%). LOH on 17p, where the TP53 gene is located, was more common in Egyptian TCC than in SCC. Similarly, 8p LOH was more common in TCC than SCC. The most striking difference between this group of tumours and TCCs from the United Kingdom and the United States was the high frequency of 9p LOH in the region of the CDKN2 gene (65%) and the relatively low frequency of 9q LOH (39%); 15 of 43 tumours with LOH of at least one marker on chromosome 9 showed LOH of 9p only. This suggests that a 9p gene, possibly CDKN2, may contribute to the development of the majority of schistosomiasis-associated bladder tumours but that genes on 9q play a much less important role.     

Loss of chromosome 11 and 11 P/Q imbalances in bladder cancer detected by fluorescence in situ hybridization

To identify chromosomal imbalances in non-diploid transitional-cell carcinoma (TCC) of the bladder we performed double-target in situ hybridization (FISH), using the centromeric probe for chromosome 11 together with 2 cosmid probes located on the 11p and 11q arm in the proximity of the telomere. The FISH protocol was optimized to ensure a highly efficient and reproducible detectability of all 3 targets. As a consequence, it was possible to calculate ratios between the number of spots obtained with cosmid and centromere probes. Furthermore, the number of chromosomes 11 present was compared with the DNA index and the chromosome ploidy as obtained with other chromosome centromere probes. In this study we found that: (i) in 54 diploid TCCs a monosomy for chromosome 11 was detected in only one case; (ii) chromosome 11 was completely lost in 9 of 16 non-diploid TCCs; (iii) in 8 of these 16 non-diploid tumors an imbalance was observed between the 11p and 11q arm, in 4 of these cases a complete loss of chromosome 11 being observed in addition; (iv) the copy number counted for 11q was always identical to the 11 centromere number, except in one case, indicating a loss of 11p in the cases with imbalances. In total, 13 of 16 non-diploid TCCs (81%) showed either a loss of a complete chromosome 11, of (part of) the 11p arm, or both. Therefore we concluded that during tetra- or aneuploidization in TCCs, (part of) chromosome 11 is lost. In addition, our results indicate that under-representation of chromosome 11p occurs in the majority of the tumor cells, supporting the idea that loss of these sequences is an important step in the development of TCC. © 1996 Wiley-Liss, Inc.     

Functional evidence for a nasopharyngeal carcinoma-related gene BCAT1 located at 12p12

Nasopharyngeal carcinoma (NPC) is a malignancy that is prevalent among populations from Southeast Asia. The carcinogenesis of NPC is thought to be a multistep process involving several genetic changes. Our previous study based on distance and branching-tree models for NPC carcinogenesis indicated +12p11-p12 was an early event and should play an important role in NPC development. To understand the role of +12p11-p12 as the tree model predicted and evaluate which gene located at 12p11-p12 might be involved in NPC development, semiquantitative RT-PCR was applied to examine the expression status of 18 genes selected from 12p11-p12 in 36 NPC and 8 normal nasopharynx (NP) biopsies. The results revealed that BCAT1, KCNJ8, PTX1, and KRAS2 genes were overexpressed in NPC tissues and BCAT1 was of particular interest based on its function reported in other tumors. To further elucidate the function of BCAT1 gene in NPC, BCAT1 expression was specifically suppressed in 5-8F NPC cell line by RNA interference (RNAi), confirmed by RT-PCR and Western blotting. As expected, the depletion of BCAT1 could effectively block the proliferation of NPC cells. The BCAT1 identified in the amplified 12p11-p12 region may play a certain role in NPC development.     

Lymphocyte-mediated lysis of tumor cells in vitro (ADCC), induced by serum antibodies from patients with urinary bladder carcinoma or from controls

IgG fractions from serum of patients with transitional-cell carcinoma of the urinary bladder (TCC), patients with carcinoma of the prostate (CC) and healthy donors (HD) were tested for their capacity to induce antibody-dependent lymphocyte-mediated cytotoxicity (ADCC) to tumor cells in vitro. Lymphocytes from healthy donors were selected for low natural cytotoxicity to the target cells from established cell lines of TCC or other origins. IgG was prepared by adsorption of serum to Sepharose-bound protein A from Staphylococcus aureus and subsequent acid elution. When tested against a panel of six different target cells, most individual IgG preparations from all three donor groups contained antibodies inducing ADCC to some of the target cells. When IgG preparations from 11 untreated TCC patients were studied for ADCC induction to the TCC target T24 and the colon carcinoma HT29, cytotoxicity to T24 was, on an average, significantly higher than that to HT29. For IgG preparations from 18 TCC patients, treated with radiotherapy, a similar difference was seen but was not statistically significant. IgG preparations from 11 patients with carcinoma of the prostate and from 12 healthy donors did not show this difference. Moreover, while individual IgG preparations from untreated TCC patients were, on the average, significantly more cytotoxic to T24 than those from either of the two control groups, no such differences were seen when HT29 was the target. On the contrary, IgG preparations from patients with prostatic carcinoma were significantly more cytotoxic to HT29 than those from healthy donors. The results suggest that TCC patients develop a disease-related humoral immune response, superimposed on a “natural” immunity to a variety of antigens on the target cells used. The nature of the antigens involved in these reactions remains to be established. However, the results are compatible with previous findings, in these patients, of a bladder-tumor-related cellular cytotoxicity, to a large extent caused by the patients' own antibodies.     

Metastatic bladder transitional cell carcinoma presenting as a vascularised cutaneous right arm lesion

A 65-year-old man presented to the emergency department with a 3-week history of a fast-growing and painful mass in his right antecubital fossa. He felt otherwise well. Four months earlier, he had undergone a radical cystectomy for transitional-cell carcinoma (TCC) of the bladder (grade 3, stage pT1). Two months after the cystectomy, at another hospital, he was diagnosed with, and treated for, a pseudoaneurysm in his right antecubital fossa. Duplex ultrasonography of the presenting lesion revealed a highly vascularised mass with no pseudoaneurysm. Histological and immunohistochemical analysis preceded a diagnosis of cutaneous metastatic TCC. Whole-body CT revealed widespread metastases. This is the first reported case of a highly vascularised cutaneous lesion being the presenting feature of metastatic bladder TCC.     

人膀胱移行细胞癌复发相关基因的筛选

目的：应用基因芯片技术筛选人膀胱移行细胞癌复发相关基因。方法：使用人肿瘤基因表达谱芯片检测11例膀胱移行细胞癌患者的正常膀胱粘膜组织、原发膀胱癌组织及复发膀胱癌组织的基因表达谱．筛选出在原发膀胱癌组织及复发膀胱癌组织中差异表达的基因，并用半定量RT—PCR对部分差异表达基因进行验证。结果：以正常膀胱粘膜组织为对照，11例膀胱肿瘤组织中有87个基因表达明显下调，102个基因表达明显上调．其中有15个基因的表达在原发膀胱癌组织及复发膀胱癌组织呈相反变化。结论：膀胱肿瘤与正常膀胱粘膜组织之间存在大量差异表达的基因，说明膀胱肿瘤的发生与发展是多种肿瘤相关基因表达失常或肿瘤抑制基因失活所致：在原发膀胱癌组织及复发膀胱癌组织中呈反向变化的15个基因可能与膀胱癌的复发有关。     

Different combinations of genetic/epigenetic alterations inactivate the p53 and pRb pathways in invasive human bladder cancers

Inactivation of both the pRb (pRb-cyclin D1/cyclin-dependent kinase 4/6-p16) and p53 (p53-p21(WAF1)-p14(ARF)) pathways is thought to be essential for immortalization in vitro and malignant transformation in vivo. We identified different combinations of pRb and p53 pathway alterations in 12 invasive transitional cell carcinomas (TCCs) and addressed the functional significance of the different combinations observed. Results showed four combinations of alterations including -pRb/-p53 (ie., pRb inactivated in the pRb pathway and p53 inactivated in the p53 pathway; four TCCs), -p16/-p53 (four TCCs), -p16/-p21(WAF1) (one TCC), and -p16/ -p14(ARF) (two TCCs). These groups include two new combinations (ie., -p16/-p53 and -p16/-p21(WAF1)) not reported previously for TCCs. An alteration in the key components of the p53 pathway was not detected in one invasive TCC that had inactivated p16. Note that all four TCCs with inactivated pRb had mutant p53; thus, the combinations of -pRb/ -p21(WAF1) and -pRb/-p14(ARF) were not observed. Only two of eight TCCs with altered p16 had concomitant p14(ARF) loss, demonstrating that simultaneous inactivation of these two 9p21INK4a tumor suppressor genes is not obligatory. To determine the biological phenotypes of TCCs with different combinations of pRb and p53 pathway alterations, their downstream responses to gamma radiation were studied in vitro. As expected, none of eight TCCs with mutant p53 responded to gamma radiation by elevation of p53, p21(WAF1), or mdm2 or by cell cycle arrest. Only two of four TCCs with wild-type p53 and wild-type pRb (the combination of -p16/-p14(ARF)) showed normal downstream responses to gamma radiation and underwent cell cycle arrest. Two TCCs with wild-type pRb and wild-type p53 (the combination of -pl6/-p21(WAF1) and one TCC with -p16) failed to show cell cycle arrest in response to radiation. This was attributed to the absence of p21(WAF1) in one TCC. In summary, these data support a model of invasive bladder cancer pathogenesis in which both the pRb and p53 pathways are usually inactivated and the biology of the tumor is impacted by the mechanism of their inactivations.     

Genomic and expression analysis of the 8p11-12 amplicon in human breast cancer cell lines

Gene amplification is an important mechanism of oncogene activation in breast and other cancers. Characterization of amplified regions of the genome in breast cancer has led to the identification of important oncogenes including erbB-2/HER-2, C-MYC, and fibroblast growth factor receptor (FGFR) 2. Chromosome 8p11-p12 is amplified in 10-15% of human breast cancers. The putative oncogene FGFR1 localizes to this region; however, we show evidence that FGFR inhibition fails to slow growth of three breast cancer cell lines with 8p11-p12 amplification. We present a detailed analysis of this amplicon in three human breast cancer cell lines using comparative genomic hybridization, traditional Southern and Northern analysis, and chromosome 8 cDNA microarray expression profiling. This study has identified new candidate oncogenes within the 8p11-p12 region, supporting the hypothesis that genes other than FGFR1 may contribute to oncogenesis in breast cancers with proximal 8p amplification.     

Point mutation in codons 12 and 61 of the Ha-ras gene in rat urinary bladder carcinomas induced by N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide

Male F344 rats were fed N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT) for up to 4 wk, then were given the basal diets (Prolab 3200 or AIN-76A) with or without 5% sodium saccharin for up to 100 wk. Eleven transitional cell carcinomas (TCCs), one undifferentiated carcinoma, and two sarcomas of the urinary bladder were examined for the expression of ras gene product, p21, by immunohistochemical staining and western blot analysis. Point mutation in codons 12 or 61 of the Ha-ras genes amplified by polymerase chain reaction was examined by a slot-blot screening procedure using allele-specific oligonucleotide probes. Immunohistochemical staining showed enhanced immunoreactivity with the antibody to ras p21 in seven TCCs and one undifferentiated carcinoma. Western blot analysis showed faster migration of the p21 band in 6 of 11 TCCs. Oligonucleotide hybridization revealed the point mutation in codon 12 of Ha-ras gene (GGA----GTA in 1 TCC) and in codon 61 (CAA----CGA in 5 TCCs and CAA----CTA in 1 TCC). Two mutations in codons 12 and 61 coexisted in one tumor, which were found to be present in different Ha-ras alleles. The incidence of Ha-ras gene mutations were similar in groups treated with (3 of 6) or without (3 of 8) sodium saccharin. These results suggest the involvement of activated Ha-ras gene in rat urinary bladder carcinogenesis induced by FANFT.     

Expression profile of genes from 12p in testicular germ cell tumors of adolescents and adults associated with i(12p) and amplification at 12p11.2-p12.1

Gain of 12p material is invariably associated with testicular germ cell tumors (TGCTs) of adolescents and adults, most usually as an isochromosome 12p. We analyzed TGCTs with i(12p) using a global approach to expression profiling targeting chromosomes (comparative expressed sequence hybridization, CESH). This indicated overexpression of genes from 12p11.2-p12.1 relative to testis tissue and fibroblasts. The nonseminoma subtype showed higher levels of expression than seminomas. Notably, 12p11.2-p12.1 is amplified in about 10% of TGCTs and CESH analysis of such amplicon cases showed high levels of overexpression from this region. Microarray analysis, including cDNA clones representing most UniGene clusters from 12p11.2-p12.1, was applied to DNA and RNA from 5 TGCTs with amplification of 12p11.2-p12.1 and seven TGCTs with gain of the entire short arm of chromosome 12. Expression profiles were consistent with the CESH data and overexpression of EST595078, MRPS35 and LDHB at 12p11.2-p12.1 was detected in most TGCTs. High-level overexpression of BCAT1 was specific to nonseminomas and overexpression of genes such as CMAS, EKI1, KRAS2, SURB7 and various ESTs correlated with their amplification. Genes such as CCND2, GLU3, LRP6 and HPH1 at 12p13 were also overexpressed. The overexpressed sequences identified, particularly those in the region amplified, represent candidate genes for involvement in TGCT development.     

Ultrastructure, karyology and immunology of a cell line originated from a human transitional-cell carcinoma.

A cell line (J82) was derived from a poorly differentiated, invasive, transitional-cell carcinoma, Stage T3. The cells have been propagated in vitro for 5 years and showed 100% aneuploidy and a mixed epithelial-fibroblastic morphology. The majority of cells contained 2Y chromosomes and several distinctive markers. Peripheral-blood lymphocytes from the donor of the J82 cells were tested sequentially for cytotoxicity toward autologous and allogeneic tumour cells. Autologous cytotoxicity was detected against J82 cells in early in vitro passage. Allogeneic lymphocytes from some patients with transitional-cell carcinoma were also cytotoxic to J82 cells in primary culture. However, selective cytotoxicity by lymphoid cells from bladder-carcinoma patients was not detected against J82 cells in long-term tissue culture.     

Co-overexpression of fibroblast growth factor 3 and epidermal growth factor receptor is correlated with the development of nonsmall cell lung carcinoma

BACKGROUND: Lung cancer is a prevalent cancer with a poor prognosis. To develop a useful in vitro cell model, a cell line of lung squamous cell carcinoma (SCC-35) was established. METHODS: The SCC-35 cell was characterized by comparative genomic hybridization (CGH) and spectral karyotyping (SKY). Chromosome microdissection, fluorescence in situ hybridization (FISH), and Southern and Northern blots analyses were used to study target genes. RESULTS: Two amplicons were found at chromosomes 7p12 and 11q13. Amplification and overexpression of epidermal growth factor receptor (EGFR) at 7p12 and fibroblast growth factor 3 (FGF3) at 11q13 were found. To understand the correlation between these two genes in nonsmall cell lung carcinoma (NSCLC) more comprehensively, overexpression of FGF3 and EGFR was investigated by immunohistochemistry with a tissue microarray containing 406 NSCLC samples. Cytoplasmic overexpression of FGF3 and EGFR was detected in 61% and 69% NSCLC cases, respectively. More interestingly, a significant correlation between overexpression of FGF3 and EGFR was found in NSCLC. CONCLUSION: These results suggest that co-overexpression of FGF3 and EGFR may play an important role in the pathogenesis of lung carcinoma.     

Expression of the multidrug resistance-associated protein (MRP) gene in urothelial carcinomas

The intrinsic or acquired resistance of urothelial cancer to chemotherapy is one major obstacle to successful treatment. Generally, the expression level of P-glycoprotein in urothelial cancer is low, so we accordingly investigated the expression of multidrug resistance-associated protein (MRP). We examined the expression of MRP mRNA by means of slot-blotting samples of 11 renal pelvic and/or ureteral tumors, 33 bladder tumors, one lung metastasis from a ureter tumor, 7 non-cancerous urothelia from patients with transitional-cell carcinoma (TCC) and one urothelium from a patient with renal-cell carcinoma (RCC). We also estimated, by Southern blotting, whether or not the MRP gene was amplified in clinical specimens that overexpressed MRP mRNA. MRP was detected immunohistochemically using a polyclonal antibody against MRP. In all, 5 of 11 renal pelvic and/or ureter tumors (45.5%), 17 of 33 bladder tumors (51.5%) and 4 of 7 non-cancerous urothelia of TCC patients (57.1%) expressed more than 2-fold the MRP mRNA levels of drug-sensitive human KB cells. There was no significant difference in the MRP mRNA level between primary and recurrent tumors. Low-grade urothelial carcinomas (G1 and G2 TCCs) expressed significantly higher levels of MRP mRNA than the high-grade G3 TCC. The MRP gene was not amplified in urothelial carcinomas, irrespective of their expression levels of MRP mRNA. Immunohistochemically, MRP was located mainly on the plasma membrane, but also detected on the cytoplasm of cancer cells. MRP may be one mechanism responsible for intrinsic drug resistance in low-grade urothelial cancer. © 1996 Wiley-Liss, Inc.     

Loss of heterozygosity at chromosome segments 8p22 and 8p11.2-21.1 in transitional-cell carcinoma of the urinary bladder

To identify the putative tumor-suppressor gene (TSG) involved in transitional-cell carcinoma (TCC) of the urinary bladder, we undertook an allelotyping analysis in 48 cases of TCC. Relatively high percentages of allelic loss were found in 2p (5 of 23, 21.7%), 8p (9 of 21, 42.9%), 9p (4 of 20, 20.0%), 12q (6 of 28, 21.4%), 15q (1 of 5, 20%; 4 of 20, 20%), 17p (7 of 26, 26.9%) and 22q (6 of 23, 26.1%). On the basis of these results, fine-deletion mapping was performed on chromosome 8 in 52 cases by PCR of 15 microsatellite markers. Two distinct regions of common deletion were found. A 10 cM telomeric region was located to 8p22, defined by D8S511 and D8S258. A 17 cM centromeric region was located to 8p11.2-21.1, flanked by D8S298 and D8S535. The distance between the telomeric and the centromeric regions of common deletion was 3 cM. Loss of heterozygosity of 8p22 was frequently observed in tumors of high grade or advanced stage.