Loss of heterozygosity on the short arm of chromosome 3 in renal cancer

3% of human cancers are renal cell carcinomas (RCC). The most common chromosome abnormality found in this tumor is loss of heterozygosity (LOH) on the short arm of chromosome 3, which suggests that there must be one or more tumor suppressor genes between 3p14 and 3p21 near the VHL gene which play a relevant role in renal cancer development. DNA from normal and tumor tissue from 40 patients at various stages of RCC was analyzed for LOH at three microsatellites mapped to 3p (3p14.1-14.3; 3p21.2-21.3 and 3p25) by polymerase chain reaction). 42.5% of the tumors studied showed LOH on at least one locus. 30% showed LOH on only one locus; 5% on two loci and 7.5% on the three loci tested. LOH occurred only on nonpapillary tumors (p = 0.03). Interestingly, all the tumors with LOH on 3p21 were >/=25 mm (p = 0.04; relative risk 1.76, confidence interval: 1.3-2.3).     

Molecular genetic evidence for the independent origin of multifocal papillary tumors in patients with papillary renal cell carcinomas.

PURPOSE: In patients with papillary renal cell carcinoma, it is not uncommon to find two or more anatomically distinct and histologically similar tumors at radical nephrectomy. Whether these multiple papillary lesions result from intrarenal metastasis or arise independently is unknown. Previous studies have shown that multifocal clear cell renal cell carcinomas express identical allelic loss and shift patterns in the different tumors within the same kidney, consistent with a clonal origin. However, similar clonality assays for multifocal papillary renal cell neoplasia have not been done. Molecular analysis of microsatellite and chromosome alterations and X-chromosome inactivation status in separate tumors in the same patient can be used to study the genetic relationships among the coexisting multiple tumors. EXPERIMENTAL DESIGN: We examined specimens from 21 patients who underwent radical nephrectomy for renal cell carcinoma. All patients had multiple separate papillary lesions (ranging from 2 to 5). Eighteen patients had multiple papillary renal cell carcinomas. Seven had one or more papillary renal cell carcinomas with coexisting papillary adenomas. Genomic DNA samples were prepared from formalin-fixed, paraffin-embedded tissue sections using laser-capture microdissection. Loss of heterozygosity assays were done for six microsatellite polymorphic markers for putative tumor suppressor genes on chromosomes 3p14 (D3S1285), 7q31 (D7S522), 9p21 (D9S171), 16q23 (D16S507), 17q21 (D17S1795), and 17p13 (TP53). X-chromosome inactivation analyses were done on the papillary kidney tumors from three female patients. Fluorescence in situ hybridization analysis was done on the tumors of selected patients showing allelic loss at loci on chromosome 7 and/or chromosome 17. RESULTS: Twenty of 21 (95%) cases showed allelic loss in one or more of the papillary lesions in at least one of the six polymorphic markers analyzed. A concordant allelic loss pattern between each coexisting kidney tumor was seen in only 1 of 21 (5%) cases. A concordant pattern of nonrandom X-chromosome inactivation in the coexisting multiple papillary lesions was seen in two of three female patients. A discordant pattern of X-chromosome inactivation was seen in the tumors of the other female patient. Fluorescence in situ hybridization showed that the majority of tumors analyzed had gains of chromosomes 7 and 17. Two patients had one tumor with chromosomal gain and another separate tumor that did not. CONCLUSION: Our data suggest that, unlike multifocal clear cell renal cell carcinomas, the multiple tumors in patients with papillary renal cell carcinoma arise independently. Thus, intrarenal metastasis does not seem to play an important role in the spread of papillary renal cell carcinoma, a finding that has surgical, therapeutic, and prognostic implications.     

Histopathological, cytogenetic, and molecular characterization of renal cortical tumors.

We used cytogenetic and restriction fragment length polymorphism (RFLP) analysis methods to define genetic alterations and also correlate the changes with histopathology in renal cortical tumors. The study series is comprised of 50 renal tumors in 4 histological categories: (a) clear cell, nonpapillary, renal cell carcinoma (RCC) (n = 32); (b) nonclear cell, nonpapillary RCC (n = 10); (c) papillary RCC (n = 3); and (d) oncocytic tumors (n = 5). Successful karyotypes were obtained from 28 tumors (56%), of which 17 (61%) were abnormal. Abnormalities of chromosome 3p were seen in 9 tumors, which included unbalanced translocations and terminal or interstitial deletions. Abnormalities of chromosome 5 were identified in 11 tumors, 8 of which were due to unbalanced translocations between 3p and 5q, resulting in an extra copy for the region 5q22----ter. In addition, trisomy or tetrasomy of chromosome 17 was seen in 6 (5 with normal chromosome 3 and one with 3p deletion), trisomy or more copies of chromosome 7 in 8 (4 with 3p deletion, 2 with trisomy or tetrasomy 17, and 2 with trisomy alone), and trisomy 12 in 3 (all with trisomy 17) tumors. Furthermore, relative deficiency of chromosome 17p was seen in 3 (all with deletion 3p) and chromosome 18 in 4 (all with deletion 3p) tumors. RFLP analysis with four chromosome 3 specific probes detected 3p deletions in 19 tumors with the most common breakpoint located between 3p14-21. The 19 3p deletions detected by RFLP included tumors that also showed rearrangement of 3p by cytogenetics (n = 4) and those that showed normal karyotypes (n = 3) in addition to cytogenetic failures (n = 12). Deletions of 17p were seen in 5 of 31 informative cases. Thus, deletions of 3p were seen in a total of 24 tumors by cytogenetic and/or RFLP analysis, 21 of which were clear cell, nonpapillary RCC, whereas 3 had a minor clear-cell component. Oncocytic and nonclear, nonpapillary tumors, on the other hand, did not demonstrate 3p deletions by either technique, whereas trisomy 17 was seen in 3 of the 3 papillary tumors. The loss of alleles from chromosome 17p and 18 and an increased dosage of gene or genes on chromosomes 5q and 7 as seen in high-stage tumors of various histological subtypes may be associated with progression of disease.     

消化道多原发癌组织中凋亡相关蛋白p53和bcl-2的表达

目的研究消化道多原发癌组织中的p53和bcl-2蛋白表达状况，探讨p53和bcl-2基因在多原发癌的发生发展中的意义。方法应用免疫组织化学方法检测17例消化道双原发癌组织中的p53和bcl-2蛋白表达。结果17例患者34个独立癌灶中p53阳性者21个(21／34)，bcl-2阳性者14个(14／34)。3例患者第一癌和第二癌的p53和bcl-2表达均为阴性，其它14例患者第一癌和第二癌则有p53或／和bcl-2表达；5例患者p53和bcl-2在第一癌和第二癌中的结果一致，其它12例患者则有不同程度的区别。结论p53和bcl-2基因在消化道多原发癌的发生发展中可能起重要作用，对这些发现的意义值得进一步研究。     

Contribution of Chromosome 9p21-22 Deletion to the Progression of Human Renal Cell Carcinoma

To investigate the possible role of genomic aberrations of chromosome 9p21-22 in the tumorigenesis of human renal cell carcinoma (RCC), 10 RCC cell lines, 55 primary RCCs and 5 metastatic lesions were studied by Southern blotting and polymerase chain reaction-based analysis. Nine of 10 RCC cell lines showed a homozygous deletion of MTS1/CDKN2/(p16) , while only 1 in 55 primary tumors had this deletion. Loss of heterozygosity on 9p21-22 was observed in 5 of 10 informative primary RCCs from patients with metastasis, but in only 4 of 31 informative tumors (13%) without metastasis ( P = 0.025). Furthermore, 3 of 5 metastatic tumors (60%) showed hemi- or homozygous deletion of MTS1/CDKN2 . These results indicate that the 9p21-22 deletion may be a relatively late event in RCC tumorigenesis and could be associated with RCC metastasis.     

Inactivation of the INK4a/ARF locus and p53 in sporadic extrahepatic bile duct cancers and bile tract cancer cell lines.

The tumor-suppressor genes p14(ARF), p16(INK4a) and Tp53 are commonly inactivated in many tumors. We investigated their role in the pathogenesis of 9 bile tract cancer cell lines and 21 primary sporadic extrahepatic bile duct carcinomas. p53 and p16 protein expression was examined by Western blot analysis and immunohistochemistry. Mutation screening of p53 was done by SSCP and direct sequencing. Inactivating mechanisms of p14 and p16 were addressed by screening for mutations, homozygous deletions, chromosomal loss of 9p21 (loss of heterozygosity [LOH] analysis) and promoter hypermethylation of the p14/p16 genes. p53 overexpression could be detected in 7 of 9 cell lines and 7 of 21 primary tumors, but mutations were found in 3 cell lines only. p16 expression was absent in all cell lines, due to homozygous deletion of the gene in 8 of 9 cell lines and hypermethylation of the p16 promoter in one cell line (CC-LP-1). p14 exon 1beta was homozygously deleted in 6 of 9 cell lines, while retained in CC-LP-1 and 2 additional lines. No p14 promoter hypermethylation could be detected. p16 expression was lost in 11 of 21 primary tumors. p16 promoter hypermethylation was present in 9 of 21 primary tumors, all with lost p16 expression. Allelic loss at 9p21 was detected in 13 of 21 primary tumors, 10 of 11 with lost p16 expression and 8 of 9 with methylated p16 promoter. No p14 promoter hypermethylation or p14/p16 mutations could be detected. Neither Tp53 nor p16 alterations showed obvious association with histopathologic or clinical characteristics. In conclusion, inactivation of the p16 gene is a frequent event in primary sporadic extrahepatic bile duct cancers, 9p21 LOH and promoter hypermethylation being the principal inactivating mechanisms. Therefore, p16, but not p14, seems to be the primary target of inactivation at the INK4a locus in bile duct cancers. Other mechanisms than Tp53 mutations seems to be predominantly responsible for stabilization of nuclear p53 protein in bile duct cancers.     

Cytogenetic profile of 109 lipomas

Cytogenetic analysis of short-term cultures was carried out on 109 lipomas from 92 patients. Clonal chromosomal abnormalities were present in 50% of the tumors analyzed. Based on the results, three main cytogenetic groups were identified and included: (a) tumors with normal karyotypes, (b) tumors with abnormalities involving region q13-15 on chromosome 12, and (c) tumors with other clonal aberrations. Within each of these groups, cytogenetic subgroups could be identified, each characterized by a specific anomaly. Tumors with abnormalities of 12q included specific subgroups with t/ins(1;12)(p32-33;q13-15), t(2;12)(p21-22;q13-14), t(3;12)(q28;q14), t(12;21)(q13;q21), complex, and nonrecurrent aberrations. The group containing heterogeneous clonal aberrations included subgroups with del(13)(q12q22), der(6)(p21-23), der(11)(q13), and nonspecific aberrations. Chromosome bands 1p36, 1p32-33, 2p21-22, 3q27-28, 6p21-23, 11q13, 12q13-15, 13q12, 13q22, 17p13, 17q21, and 21q21-22 were preferentially involved in structural rearrangements in lipomas. The identification of these sites of nonrandom rearrangements may serve to identify genes (at or near the junctions of chromosomal aberrations) involved in normal cellular growth control. Statistical analysis of the data revealed a correlation among karyotypic abnormalities and clinical data, such as age and sex of the patient, and tumor depth, site, and size.     

Cytogenetic findings in 14 benign cartilaginous neoplasms

Benign cartilaginous tumors represent a spectrum of neoplastic processes with variable clinical and pathologic presentations. These tumors are histologically characterized by the presence of chondrocytes surrounded by a cartilaginous matrix. Few studies describe karyotypic abnormalities in these benign lesions. We report a series of 14 chondromas from a single institution. Conventional cytogenetics was performed on short term cultures from all cases. Clonal chromosome aberrations were found in nine tumors. One soft tissue chondroma contained three clones with t(6;12)(q12;p11.2), t(3;7)(q13;p12), and der(2)t(2;18)(p11.2;q11.2). Three periosteal chondromas displayed random structural aberrations of chromosomes 2, 3, 6, 7, and 11 and loss of chromosome 13. Among the enchondromas, three tumors displayed chromosome losses, one contained a complex translocation involving chromosomes 12, 15, and 21 as well as an inv(2)(p21q31),t(12;15;21)(q13;q14;q22) and a separate enchondroma showed a translocation involving chromosomes 12 and 22. Our data suggest that considerable cytogenetic heterogeneity exists among benign chondromatous tumors.     

Fine mapping of chromosome 3 in uveal melanoma: identification of a minimal region of deletion on chromosomal arm 3p25.1-p25.2

To identify minimal common areas of allelic loss on chromosome 3, we have mapped both arms of the chromosome in 21 uveal melanomas that did not show monosomy 3 in our previous allelotype study. DNA was isolated from microdissected paraffin sections and amplified by PCR. In an initial screening, 14 microsatellite markers on chromosomal arm 3p and 13 on chromosomal arm 3q were used. Loss of heterozygosity for at least one marker was found in 9 of 21 tumors (43%) on 3p and 8 of 21 tumors (38%) on 3q. The initial analysis defined two common regions of allelic loss on 3p, a 7.3-Mb region between markers D3S1263 and D3S3510 spanning 3p25.3-24.3 and a larger region between markers D3S1578 and D3S1284. The two common regions of allelic loss were further mapped with an additional 14 microsatellite markers. A 1.4-Mb minimal region of allelic loss was identified between microsatellite markers D3S3610 and D3S1554 on 3p25.1-3p25.2. A total of 10 tumors had allelic loss in this region; 2 of these tumors had corresponding putative homozygous deletions. These homozygous deletions may further narrow the region of interest to 0.1 Mb. This 1.4-Mb minimum region of deletion includes several genes that might be involved in the carcinogenesis of uveal melanoma as well as other important tumor types.     

Chromosomal alterations during lymphatic and liver metastasis formation of colorectal cancer

Comparative genomic hybridization (CGH) was used to screen colorectal carcinomas for chromosomal aberrations that are associated with metastatic phenotype. In total, 63 tumor specimens from 40 patients were investigated, comprising 30 primary tumors, 22 systemic metastases (12 liver, 6 brain, and 4 abdominal wall metastases) and 11 lymph node tumors. Using statistical analysis and histograms to evaluate the chromosomal imbalances, overrepresentations were detected most frequently at 20q11.2-20q13.2, 7q11.1-7q12, 13q11.2-13q14, 16p12, 19p13, 9q34, and 19q13.1-19q13.2. Deletions were prominent at 18q12-18q23, 4q27-4q28, 4p14, 5q21, 1p21-1p22, 21q21, 6q16-6q21, 3p12, 8p22-8p23, 9p21, 11q22, and 14q13-14q21. Hematogenous metastases showed more alterations than lymph node tumors, particularly more deletions at 1p, 3, 4, 5q, 10q, 14, and 21q21 and gains at 1q, 7p, 12qter, 13, 16, and 22q. Comparing liver metastases with their corresponding primary tumors, particularly deletions at 2q, 5q, 8p, 9p, 10q, and 21q21 and gains at 1q, 11, 12qter, 17q12-q21, 19, and 22q were more often observed. The analysis suggested that the different pathways of tumor dissemination are reflected by a nonrandom accumulation of chromosomal alterations with specific changes being responsible for the different characteristics of the metastatic phenotype.     

Clonal divergence and genetic heterogeneity in clear cell renal cell carcinomas with sarcomatoid transformation

BACKGROUND: Approximately 5% of clear cell renal cell carcinomas contain components with sarcomatoid differentiation. It has been suggested that the sarcomatoid elements arise from the clear cell tumors as a consequence of clonal expansions of neoplastic cells with progressively more genetic alterations. Analysis of the pattern of allelic loss and X-chromosome inactivation in both the clear cell and sarcomatoid components of the same tumor allows assessment of the genetic relationship of these tumor elements. METHODS: The authors of the current study examined the pattern of allelic loss in clear cell and sarcomatoid components of renal cell carcinomas from 22 patients who had tumors with both components. DNA samples were prepared from formalin-fixed, paraffin-embedded renal tissue sections using laser-capture microdissection. Five microsatellite polymorphic markers for putative tumor suppressor genes on 5 different chromosomes were analyzed. These included D3S1300 (3p14), D7S522 (7q31), D8S261 (8p21), D9S171 (9p21), and TP53 (17p13). In addition, X-chromosome inactivation analysis was performed in 14 tumors from female patients. RESULTS: The clear cell components showed loss of heterozygosity (LOH) at the D3S1300, D7S522, D8S261, D9S171, and TP53 loci in 18% (4/22), 18% (4/22), 50% (10/20), 15% (3/20), and 20% (4/20) of informative cases, respectively. LOH in the sarcomatoid components was seen at the D3S1300, D7S522, D8S261, D9S171, and TP53 loci in 18% (4/22), 41% (9/22), 70% (14/20), 35% (7/20), and 20% (4/20) of informative cases, respectively. Six cases demonstrated an LOH pattern in the clear cell component that was not seen in the sarcomatoid component. Different patterns of allelic loss were seen in the clear cell and sarcomatoid components in 15 cases. Clonality analysis showed the same pattern of nonrandom X-chromosome inactivation in both clear cell and sarcomatoid components in 13 of the 14 cases studied. One case showed a random pattern of X-chromosome inactivation. CONCLUSION: X-chromosome inactivation analysis data suggest that both clear cell and sarcomatoid components of renal cell carcinomas are derived from the same progenitor cell. Different patterns of allelic loss in multiple chromosomal regions were observed in clear cell and sarcomatoid components from the same patient. This genetic heterogeneity indicates genetic divergence during the clonal evolution of renal cell carcinoma.     

Tumorigenic pathways in low-stage bladder cancer based on p53, MDM2 and p21 phenotypes

Our aim was to determine whether the pattern of expression of the interrelated proteins p53, MDM2 and p21 could shed light on the etiopathogenic mechanisms of superficial bladder tumors. Protein expression was detected by immunohistochemistry (IHC) using monoclonal antibodies (MAbs) Pab 1801 for p53, IF2 for MDM2 and EA10 for p21 on 269 newly diagnosed bladder tumors (214 pTa and 55 pT1; 93 grade I, 145 grade 2 and 31 grade 3). While no p21 immunoreactivity was found in normal urothelium, 85% of tumors were strongly p21-positive. MDM2 was overexpressed in 44% of tumors, almost all being also positive for p21. p53 was overexpressed in 20% of cases: 66% of p53-positive tumors were also MDM2 positive, compared with only 38% of p53-negative tumors. p53 mutations were studied by direct DNA sequencing in a subset of 24 high-grade tumors. Both MDM2 and p21 were less frequently expressed in p53 mutated tumors compared with tumors with a wild-type gene. Distinct phenotypes were correlated with the frequency of poorly differentiated (grade 3) tumors. The most common phenotypes were p21+/MDM2-/p53- and p21+/MDM2+/p53- observed in 38% and 29% of tumors, respectively. Grade 3 tumors were found in 4% and 8% of these 2 groups, in contrast with 30% frequency in p21+/p53+ tumors (p = 0.002) regardless of their MDM2 phenotype. Four of the 5 (80%) tumors that were p53-positive but negative for p21 were grade 3. Our data suggest that several tumorigenic pathways for superficial bladder tumors can be reflected by the expression pattern of these 3 proteins.     

Dysfunction of the p53 tumor suppressor pathway in head and neck cancer

It is important to examine the abnormality of the entire p53 tumor suppressor pathway in head and neck cancer. We examined the mRNA expressions of p53 regulatory factors, p33ING1 and p14ARF, and a p53-target gene, p21WAF1 in head and neck cancer. Nine of 14 benign pleomorphic adenomas (PAs) and 7 of 8 malignant salivary gland tumors (MSGTs) expressed p33ING1 mRNA. Thirteen of 14 PAs expressed p14ARF mRNA, however, only 1 of 8 MSGTs expressed p14ARF mRNA. Eight of 14 PAs and 7 of 8 MSGTs expressed p21WAF1 mRNA. In salivary gland tumors, there was clear correlation between the expression of p33ING1 and p21WAF1 (p<0.0001, r2=0.53). However, there was no correlation between the expression of p14ARF and p21WAF1 (p=0.6543, r2=0.009). Twenty-six of 28 oral squamous cell carcinomas (SCCs) expressed p33ING1 mRNA. Nineteen of 28 oral SCCs expressed p14ARF mRNA. All of the oral SCCs expressed p21WAF1 mRNA. In oral SCCs, the expressions of both p33ING1 (p=0.009, r2=0.181) and p14ARF (p=0.0009, r2=0.271) correlated with the expression of p21WAF1. Interestingly, 24 of 26 oral SCCs (92%) showed either abnormality of p53 itself or loss of expression of p53 regulatory factors, p33ING or p14ARF. These results suggest that head and neck cancer often involve the dysfunction of p53 tumor suppressor pathway.     

肾癌组织中ras基因产物p21表达和K－ras基因点突变分析

目的研究ｒａｓ基因激活在肾癌发生中的意义。方法应用聚合酶链反应－单链构象多态性分析（ＰＣＲ－ＳＳＣＰ）和免疫组织化学检测肾癌组织Ｋ－ｒａｓ基因第１２位密码子突变及其基因产物ｐ２１蛋白的表达水平。结果４２例肾癌中６例Ｋ－ｒａｓ基因第１２位密码子点突变，１９例ｐ２１蛋白阳性表达，正常肾组织和癌旁组织均阴性。ｐ２１表达与肿瘤分期和分级有关。ｐ２１阳性患者的手术后生存率明显低于ｐ２１阴性患者。结论肾癌Ｋ－ｒａｓ基因第１２位密码子点突变并不常见，ｐ２１表达可能成为肾癌恶性程度和预后评价的指标。     

Patterns of chromosomal imbalances in invasive breast cancer

Invasive breast carcinomas are characterized by a complex pattern of chromosomal alterations. We applied comparative genomic hybridization (CGH) to analyze 105 primary breast carcinomas using histograms to indicate the incidence of DNA imbalances of tumor subgroups and difference histograms to compare invasive ductal carcinomas (IDC) with lobular carcinomas (ILC), well and poorly differentiated carcinomas (G1/G3) and estrogen receptor-positive and -negative tumors (ER(+)/ER(-)). Only single imbalances showed a higher incidence in ILC compared with IDC, i.e., gains on chromosomes 4 and 5q13-q23 as well as deletions on chromosomes 6q, 11q14-qter, 12p12-pter, 16q, 17p, 18q, 19, and 22q. Of these, particularly gains of 4 and losses at 16q21-q23, and 18q12-q21 were statistically significant. For most loci, IDC showed more alterations providing a genetic correlate to the fact that ductal carcinoma overall is associated with a worse prognosis than ILC. Of these, many imbalances showing statistical significance were also observed in G3 and ER(-) tumors, i.e., deletions at 2q35-q37, 3p12-p14, 4p15-p16, 5q, 7p15, 8p22-p23, 10q, 11p, 14q21-q31, 15q, and gains at 2p, 3q21-qter, 6p, 8q21-qter, 10p, 18p11-q11, and 20q, suggesting that they contribute to a more aggressive tumor phenotype. By contrast, gains on chromosome 5q13-q23 as well as deletions at 6q, 16q and 22q were more prevalent in G1 and ER(+) tumors. The ratio profiles of all cases as well as histograms are accessible at our CGH online tumor database at http://amba.charite.de/cgh. Our results highlight distinct chromosomal subregions for cancer-associated genes. In addition, these imbalances may serve as markers for a genetic classification of invasive breast cancer.     

Mutational and nonmutational activation of p21ras in rat colonic azoxymethane-induced tumors: effects on mitogen-activated protein kinase, cyclooxygenase-2, and cyclin D1

Azoxymethane (AOM)-induced colonic carcinogenesis involves a number of mutations, including those in the K-ras gene and CTNNB1, that codes for beta-catenin. Prior in vitro studies have also demonstrated that wild type p21(K-ras) can be activated by epigenetic events. We identified 15 K-ras mutations in 14 of 84 AOM-induced colonic tumors by three independent methods. By single strand conformational polymorphism, we also observed mutations in 22 of 68 tumors in exon 3 of CTNNB1. A highly sensitive method was then used to measure p21ras activation levels. All tumors assayed possessing K-ras mutations had significantly higher p21ras activation levels (8.8 +/- 1.5%; n = 13) compared with that of control colon (3.7 +/- 0.4; n = 6; P < 0.05) or tumors without such mutations (4.2 +/- 0.4%; n = 70; P < 0.05). Among tumors with wild-type K-ras, there was a subset of tumors (18 of 70) that had significantly higher p21ras activation levels (8.0 +/- 0.9%; n = 18) compared with control colons. In three of four tumors examined with activated wild-type p21ras, we observed increased c-erbB-2 receptor expression and decreased Ras-GAP expression. In contrast, only one of eight tumors examined with wild-type ras and nonactivated p21ras demonstrated these alterations. Mitogen-activated protein kinase (MAPK) activation and cyclooxygenase-2 (COX-2) expression were increased in tumors with mutated or activated wild-type p21ras, compared with their nonactivated counterparts. Although beta-catenin mutations did not alter COX-2 expression or MAPK activity, mutations in either K-ras or beta-catenin significantly increased cyclin D1 expression. In contrast, in tumors with wild-type but activated p21-ras, cyclin D1 expression was not enhanced. Thus, the spectrum of changes in MAPK, COX-2, and cyclin D1 is distinct among tumors with ras or beta-catenin mutations or nonmutational activation of p21ras.     

人卵巢癌3号染色体短臂杂合性丢失的研究

目的探讨3号染色体短臂(3p14)等位基因杂合性丢失(10ss 0f heterozygosity,LOH)与人卵巢癌发生及发展之间的相关性研究.方法采用聚合酶链反应并结合二核苷酸重复序列多态性方法,分别对31例卵巢癌及24例卵巢良性肿瘤患者的组织标本DNA中3p14上3个微卫星位点(D3S1234、D3S1300、D3S1312)杂合性丢失(LOH)进行检测,同时还随机地检测31例卵巢癌中21例患者的血清DNA中3p14的LOH.结果31例卵巢癌组织DNA中21例(67.7%)至少在1个微卫星位点中出现杂合性丢失,11例卵巢癌患者(35.5%)有2个以上微卫星位点出现LOH.癌组织DNA中基因杂合性丢失频率与癌细胞分化程度呈正相关,与肿瘤病理类型及FIGO分期无关.24例卵巢良性肿瘤组织及血清DNA中均未出现3p位点上的杂合性丢失.21例卵巢癌血清DNA与肿瘤组织DNA 3p14基因3个微卫星位点杂合性丢失率之间存在明显的相关性(P＜0 05).结论鉴于人卵巢癌3p14出现杂合性丢失率与其癌细胞分化恶性程度相关以及卵巢癌患者血清DNA与癌组织DNA中3p14出现LOH相一致,故本文实验结果提示3p14 LOH的检测可能具有对卵巢癌患者的临床诊断潜在性价值.     

Presence of two members of c-erbA receptor gene family (c-erbA beta and c-erbA2) in smallest region of somatic homozygosity on chromosome 3p21-p25 in human breast carcinoma

The loss of heterozygosity of genes on the short arm of chromosome 3 (3p) in human breast carcinomas occurs in a region involved in other malignancies, including renal cell carcinoma, lung cancers, and von Hippel-Lindau disease. This finding suggests the presence of a gene(s) that plays a crucial role in multiple cancers. In our study of 84 informative (heterozygous) primary breast tumors, 30% showed losses of heterozygosity on chromosome 3. The shortest region of homozygosity in primary human breast tumor is located between the DNF15S2 and RAF1 loci in the 3p21-p25 region on the short arm of chromosome 3. This region includes at least two members of the c-erbA steroid/thyroid hormone receptor family (c-erbA beta and c-erbA2) that may be of special relevance to breast cancer. Furthermore, tumors with a loss of heterozygosity of genes on chromosome 3 were previously reported to have frequent allelic deletions on chromosome 11p and amplification of the c-myc proto-oncogene. These results highlight the occurrence of multiple genetic alterations in breast tumors.     

Cytogenetic and molecular findings in 75 clear cell renal cell carcinomas

Cytogenetic analysis of 75 clear cell renal cell carcinomas (RCC) from adult patients revealed abnormal karyotypes in 59 (79%) tumors. Among structural abnormalities, the most frequent were deletions and unbalanced translocations leading to loss of 3p (found in 68% of karyotypically abnormal tumors), followed by rearrangements of chromosomes 5 (in 37%) and 1 (in 20%). Fifteen unbalanced interchromosomal rearrangements and one reciprocal translocation have not been hitherto reported in clear cell RCC. The most common numerical aberrations were trisomy 7, seen in 44% of tumors, and loss of chromosome Y, detected in 48% of RCCs diagnosed in male patients. In 25 tumors, loss of heterozygosity (LOH) analysis was performed using five polymorphic markers spanning region 3p13-p25. LOH was identified in 10 RCCs with 3p loss detected cytogenetically and 4 karyotypically aberrant tumors without cytogenetic rearrangements of 3p; no LOH was found in 3 tumors with 3p loss seen at the cytogenetic level. Overall, 3p loss was detected by cytogenetic and/or LOH analyses in 75% of RCCs with abnormal karyotype studied. The presence or absence of 3p loss did not correlate with tumor size, nodal involvement, tumor grade or its ability to metastasize. However, karyotypes of metastasizing tumors contained more aberrations than those of non-metastasizing RCCs (5.5 versus 2.9 aberrations per tumor, respectively), and -14/14q-, -17 and -10 were significantly more frequent in metastasizing tumors, suggesting that these aberrations might contribute to the progression of RCC. One patient had t(X;1)(p11.2;p34) as a sole abnormality in the stemline. This is the sixth case with this translocation reported to date. Together with our case, all but 1 RCC with t(X;1)(p11.2;p34) had morphology with a clear cell component, which contrasts these RCCs from tumors harboring t(X;1)(p11.2;q21) that largely had papillary morphology.