Loss of heterozygosity and microsatellite instability at chromosomal sites 1Q and 10Q in morphologically distinct regions of late stage prostate lesions

PURPOSE: We investigated the incidence of loss of heterozygosity (LOH) and microsatellite instability in sporadic prostate cancer and surrounding tissue at loci encompassing the HPC1 and PTEN genes. MATERIALS AND METHODS: Surgical specimens from 63 patients with sporadic stage T3 or T4 prostatic adenocarcinoma were analyzed for LOH and microsatellite instability. Microdissected tissue included morphologically normal foci, benign prostatic hyperplasia (BPH) and prostatic adenocarcinoma. LOH analysis was performed using 4 microsatellite markers that map in the region of the 1q24 to 25 locus of the putative prostate cancer susceptibility gene HPC1 and 4 that map in the region of the 10q23 locus of the PTEN gene. RESULTS: The incidence of LOH on 10q was consistent with that previously reported in prostatic tumors. LOH associated with the PTEN locus was recorded in morphologically normal foci, BPH and adenocarcinoma. Sequence analysis of PTEN in a limited number of lesions revealed mutations in nontumor and tumor tissue. Analysis of the DS10215 locus showed significant LOH in tumor but not in benign tissue, suggestive of a tumor suppressor gene in this region associated with prostatic neoplastic progression. In contrast, no significant LOH was observed in the same tissues at 4 loci on chromosome 1q. In this study we recorded elevated levels of microsatellite instability in benign prostatic tissue with an additional increase associated with prostatic adenocarcinoma. CONCLUSIONS: The low incidence of LOH in the region of the HPC1 locus in all prostate lesions studied suggests that this putative hereditary prostate cancer susceptibility locus does not appear to have a role in sporadic prostate cancer, at least not in the context of LOH. In contrast, analysis of the same tissues for LOH at chromosome 10q confirmed frequent alterations in this region linked to late stage prostate cancer. PTEN mutations in microdissected morphologically normal and BPH tissue showed alterations in nontumor tissue surrounding adenocarcinoma. Microsatellite instability was increased in adenocarcinomas over an elevated background recorded in surrounding tissues.     

Loss of heterozygosity and lack of mutations of the XPG/ERCC5 DNA repair gene at 13q33 in prostate cancer.

BACKGROUND: Three regions of chromosome 13 were previously identified for having loss of heterozygosity (LOH) in human prostate cancer. One of them, at 13q33, was defined by LOH at markers D13S158 and D13S280. The XPG/ERCC5 gene, a DNA repair gene that when mutated in the germline leads to xeroderma pigmentosum, has been mapped to 13q33, within one megabase of D13S158 and D13S280. This paper describes LOH and mutational analysis of the XPG gene in human prostate cancers, in order to determine whether the XPG gene is involved in the development of prostate cancer. METHODS: LOH of the XPG gene was analyzed in 40 primary prostate cancers and 14 metastases by using the microsatellite assay, and its mutations were examined in 5 cell lines, 14 metastases, and 8 tumors with LOH at 13q33 by using the single-strand conformation polymorphism (SSCP)-direct DNA sequencing analysis. RESULTS: Four of the 29 (14%) informative primary tumors and 4 of 8 (50%) metastases showed LOH for the XPG gene. Analysis of the 8 tumors with LOH at the 13q33 region, 14 metastases, and 5 cell lines of prostate cancer revealed two polymorphisms but no mutation of the gene. The polymorphism in exon 2 did not change the amino-acid sequence of the XPG protein, but the exon 15 polymorphism altered codon 1104 from histidine to aspartic acid. The two polymorphisms also occurred in individuals without prostate cancer. CONCLUSIONS: LOH at XPG in prostate cancer supports the conclusion that the 13q33 region contains a gene important in the development of prostate cancer, while lack of mutations of the gene suggests that XPG is not the target gene involved.     

Loss of heterozygosity in chromosomal region 16q24.3 associated with progression of prostate cancer

BACKGROUND: The molecular mechanisms underlying the development and progression of prostate cancer have remained poorly understood. To find out potential genetic markers likely to underlie tumor progression, the pattern of allelic loss on chromosome arm 16q in matched primary, locally recurrent, and metastatic prostate cancer specimens was analyzed in the present study. METHODS: The frequency of loss of heterozygosity (LOH) in 74 tumor specimens (62 primary cancer foci and 12 metastatic tumors) collected from 33 prostate cancer patients was determined by fragment analysis using 17 polymorphic microsatellite markers. RESULTS: The overall frequency of patients showing allelic loss at one or more loci on 16q was 68% (21/31) in primary tumors and 90% (28/31) in recurrent tumors. Of the individual markers, D16S520, locating in region 16q24.3, exhibited a statistically significant development of LOH during disease recurrence (P < 0.01). Regarding distant metastases, instead, there seemed to be no allelic loss events exclusively typical of metastatic tumors at 16q. CONCLUSIONS: The data suggest the location of gene(s) related to prostate cancer progression at 16q24.3.     

Deletion at chromosome arms 6q16-22 and 10q22.3-23.1 associated with initiation of prostate cancer

Loss of heterozygosity (LOH) at 6q16-22 and 10q22.3-23.1 is common chromosomal alteration in advanced prostate cancer and suggests that one or more tumor suppressor genes may lie within these chromosome arms. However, the genetic changes in early stage prostate cancer and premalignant lesions remain to be investigated. We used 11 informative microsatellite markers at 6q16-22 and 10q22.3-23.1 in Japanese patients to compare the frequency of LOH in 53 lesions of high-grade prostatic intraepithelial neoplasia (HGPIN), 38 cases (38 lesions) of incidental prostate cancer (IPC) and 107 cases (168 lesions) of clinical prostate cancer (CPC). The frequency of LOH at 6q16-22 with at least one marker was 38 and 49% in IPC and CPC cases, respectively. Similarly, allelic loss at 10q22.3-23.1 was present in 35 and 39% of IPC and CPC, respectively. High-frequency LOH was detected in both the clinically insignificant and significant prostate cancers at 6q16-22 and 10q22.3-23.1 (P>0.05). However, no allelic loss was detected in any markers at the same regions in HGPIN (0%), which is usually considered a premalignant lesion to prostate cancer. Deletions of both the chromosome regions, 6q16-22 and 10q22.3-23.1, are more likely important events in the initiation and/or promotion of prostate cancer.     

Identification of a novel microsatellite marker tightly linked to the KAI-1 gene for predicting prostate cancer progression

BACKGROUND: We have mapped the human prostate-specific membrane antigen (PSM) gene to the chromosome 11p11.2 region at 62.5 cM, a region which also contains the prostatic cancer metastasis suppressor gene KAI-1. The genetic marker D11S1344 has been utilised for loss of heterozygosity (LOH) studies on the KAI-1 gene in a large series of prostate cancer specimens. The results were negative and it was concluded that deletions of the KAI-1 gene were not involved in the development of the metastatic phenotype in these tumours. One possible explanation for this result could be that D11S1344 is not sufficiently tightly linked to the KAI-1 gene to detect small deletions. OBJECTIVE: To attempt to identify a genetic marker more tightly linked to the KAI-1 gene than D11S1344. METHODS: Yeast artificial chromosome (YAC) clones containing the KAI-1 gene and the neighbouring marker D11S1344 were analysed by the fluorescent in situ hybridisation technique. The human genomic inserts in these novel clones were sized by pulsed field gel electrophoresis. For more accurate mapping of the KAI-1 gene, YACs containing it were screened for polymorphic markers (including D11S1344) from the 11p11.2 region. RESULTS: The novel YAC clones localised exclusively to the 11p11.2 region, with single hybridisation signals compared to the dual signals consistently obtained with nearby PSM-containing YACs. All the KAI-1 clones found had small inserts (<300 kb). The only known microsatellite which gave amplification products with these YACs was D11S986 which has been mapped at 61.3 cM on human chromosome 11. CONCLUSIONS: We have precisely localised KAI-1 at 61.3 cM on human chromosome 11. This is some 1.2 cM away from the previously utilised LOH microsatellite marker, D11S1344. We suggest that the very tightly linked microsatellite D11S986 may be a more accurate marker to assess LOH of the KAI-1 gene and thus predict progression of prostate cancer. The region of genetic duplication around the PSM gene does not extend as far distally on 11p as KAI-1.     

Loss of heterozygosity on chromosomes 10 and 17 in clinically localized prostate carcinoma

Loss of heterozygosity (LOH) at chromosomal loci has been associated with the presence of tumor suppressor genes at the deleted loci. Twenty-six clinically localized, Stage B prostate carcinomas were analyzed for LOH on chromosomes 10 and 17 using microsatellite markers. Two of 26 carcinomas showed LOH on 17p while one showed LOH on 17q. Chromosome 10 showed a complex pattern of LOH with monosomy (1 case), LOH on 10p (1 case), proximal 10q (1 case) and distal 10q (2 cases). Overall 29% of informative cases showed LOH on chromosome 10. These results are consistent with the presence of a tumor suppressor for prostate cancer on 17p and multiple tumor suppressor genes on chromosome 10. © 1996 Wiley-Liss, Inc.     

膀胱移行细胞癌9q的杂合性丢失及抑癌基因位点的定位

目的研究膀胱移行细胞癌的９号染色体长臂（９ｑ）杂合性丢失并对抑癌基因位点进行定位。方法通过应用２５对高密度多态性微小卫星标记经ＰＣＲ扩增，６％变性聚丙烯酰胺凝胶电泳，检测膀胱移行细胞癌的９ｑ杂合性丢失，寻找膀胱移行细胞癌相关抑癌基因的位点。结果２５例病人约有９２％的肿瘤至少有一个以上位点的杂合性丢失，最常见的丢失区域为９ｑ１２～９ｑ２１、９ｑ２２和９ｑ３４，最常见的丢失位点是ＤＢＨ４４．０％、Ｄ９Ｓ１５２２７％、Ｄ９Ｓ１８１５２２７％、Ｄ９Ｓ１７６１２．０％、Ｄ９Ｓ１８３１１６．０％。绘制出膀胱移行细胞癌９ｑ杂合性丢失的染色体图谱，９ｑ杂合性丢失与肿瘤的分级、分期无相关性。结论膀胱移行细胞癌９ｑ的杂合性丢失是肿瘤发生的早期事件之一，在９ｑ３４的ＤＢＨ位点及其附近可能有与膀胱肿瘤相关的抑癌基因存在，并与肿瘤的发生有关。     

Chromosome 22q a frequent site of allele loss in head and neck carcinoma

BACKGROUND: Loss of heterozygosity (LOH) correlates with inactivated tumor suppressor genes. LOH at chromosome arm 22q has been found in a variety of human neoplasms, suggesting that this region contains a tumor suppressor gene(s) other than NF2 important to tumorigenesis. The aim of this study was to evaluate the presence of LOH on chromosome 22q11.2-13 and determine whether there was a relationship between loss in this genomic region and tumor histologic parameters, anatomic site, and survival in patients with squamous cell carcinoma of the head and neck (HNSCC). METHODS: Fifty matched blood and HNSCC tumor samples taken at the time of surgical treatment were evaluated for LOH by use of four microsatellite markers mapping to 22q11.2-q13. Clinical information was available for all patients. The frequency and distribution of LOH was correlated with clinical (age, sex, use of tobacco and alcohol, site of primary tumor, clinical stage, adjuvant therapy and overall survival) and histologic parameters (histopathologic stage, tumor differentiation). RESULTS: LOH at 22q was found in 19 of 50 (38%) informative tumors. The respective incidence of allelic loss for the patients was as follows: 28% at D22S421, 10% at D22S277, 8% at D22S446, and 4% at D22S280. No statistical differences were apparent with a mean follow-up of 30 months. Laryngeal tumors showed a higher incidence of LOH compared with oral tumors. CONCLUSIONS: These results suggest that the D22S277 locus may be closely linked to a tumor suppressor gene (TSG) and involved in upper aerodigestive tract carcinogenesis. In particular, laryngeal tumors may harbor another putative TSG on 22q11.2-q12.3 that may play a role in aggressive stage III/IV disease.     

Allelotyping analysis at chromosome 13q of high-grade prostatic intraepithelial neoplasia and clinically insignificant and significant prostate cancers

BACKGROUND: Loss of heterozygosity (LOH) at 13q is one of the most common chromosomal alterations in high-stage prostate cancer, yet little is known about genetic changes in earlier-stage prostate cancer. METHODS: We used five microsatellite markers at 13q14, 21, and 33 to compare LOH frequencies in 51 lesions of high-grade prostatic intraepithelial neoplasia (HGPIN), 21 cases of incidental prostate cancers (IPCs), 31 cases of latent prostate cancers (LPCs), and 102 cases of clinical prostate cancers (CPCs). RESULTS: The frequency of LOH at 13q with at least 1 marker was 0%, 38%, 56%, and 49% in HGPIN, IPCs, LPCs, and CPCs, respectively. No statistically significant difference was found between the types of prostate cancer. Allelic loss at 13q14 was significantly more frequent in pT4 tumors than in earlier-stage tumors (P=0.011). CONCLUSIONS: Allelic loss at 13q is not only an important event in the metastasis of prostate cancer, but also associated with the initiation of the tumor.     

散发性结直肠癌染色体20q11-13区杂合性缺失精细定位

目的 研究散发性结直肠癌20号染色体杂合性缺失情况,并对20q11-13区进行精细定位.方法 收集1998年至1999年上海市第一人民医院83例结直肠癌患者的肿瘤组织和对应的正常黏膜组织,采用10个微卫星标记的引物对20号染色体进行杂合性缺失分析,在20q11-13区域另取10个微卫星标记的引物并对标本进行PCR分析.以Genescan 3.1和Genotyper 2.1软件进行基因分型和精确定位.结果 在20号染色体上发现一个高频杂合性缺失区即20q11-13区.进一步的精细定位,界定了两个高频杂合性缺失区:20q11.2、20q12,并在该杂合性缺失区发现了抑癌基因E2F1、PMP24和MAFB.结论 20号染色体有两个高频精细杂合性缺失区,该区很可能存在一个或多个与结直肠癌相关的新的抑癌基因.     

Loss of heterozygosity at 13q14 and 13q21 in high grade, high stage prostate cancer.

BACKGROUND: Loss of heterozygosity (LOH) at chromosome 13q has been frequently detected in prostate cancer, and three regions (i.e., 13q14, 13q21, and 13q33) may harbor tumor suppressor genes important in this neoplasm. In this study, we examined the frequency of 13q LOH in advanced prostate cancers, in order to determine the clinicopathologic relevance of 13q LOH. METHODS: LOH was determined by analyzing microsatellite markers in 41 cases of microdissected predominantly high grade prostate cancer tissues and their matched nonneoplastic cells. The results were compared with those generated previously for lower grade, asymptomatic cancers. RESULTS: The frequencies of LOH at 13q14, 13q21, and 13q33 were 62% (21/34), 57% (20/35), and 34% (11/32), respectively. In comparison to previous results, LOH at 13q14 and 13q21 but not 13q33 was more frequent in prostate cancers that produced local clinical symptoms (bladder outlet obstruction) than those that did not (P < 0.05). LOH at 13q14 was also significantly more frequent in high grade and high stage cancers than those that were lower grade and lower stage (P < 0.05). CONCLUSIONS: Although the target genes on 13q have not been identified in carcinomas of the prostate, LOH at 13q14 in particular is associated with clinically significant prostate cancers. Further fine mapping of these loci may lead to identification of tumor suppressor genes that are deleted in aggressive carcinomas of the prostate.     

Extensive analysis of the 13q14 region in human prostate tumors: DNA analysis and quantitative expression of genes lying in the interval of deletion

BACKGROUND: Loss of heterozygosity (LOH) on chromosome arm 13q14 is one of the most consistent genetic alterations in sporadic prostate cancer. This alteration may be involved in prostate oncogenesis through inactivation of one or more tumor suppressor genes (TSGs). Candidate gene expression is an approach to focus the search for TSGs in this region. METHODS: We tested 41 human sporadic prostate tumors for 13q14 LOH by using seven polymorphic markers overlapping the critical region and used a real-time quantitative RT-PCR assay to study the same tumors for expression of the 31 genes located in this genomic region (localized by the Human Genome Project Working Draft). RESULTS: Allelic loss on at least one locus was found in 18 (41%) of the 41 tumor DNAs. Only four genes (ITM2B, CHC1L, KIAA0970, and LOC51131), located in the region most frequently deleted in prostate carcinoma, showed a significant difference in expression between normal and neoplastic prostate tissues. CONCLUSIONS: Given their location in the LOH hotspot, as indicated by our genomic analysis, ITM2B, CHC1L, KIAA0970, and LOC51131 are candidate tumor suppressor genes in this region. ITM2B that showed a significant association (P < 0.005) between expression and LOH at the corresponding locus could, furthermore, be the main target of the observed LOH at 13q in prostate tumors.     

散发性结直肠癌1号染色体1q31.1-32.1区域等位基因杂合缺失精细定位研究

目的 对染色体1q31.1-32.1区域进行杂合缺失(LOH)精细定位分析,探讨更为精确的高频LOH区域并筛选可能与结直肠癌相关的抑癌基因.方法 在1q31.1-32.1区域选择6对微卫星引物与83例结直肠癌的肿瘤和正常组织进行聚合酶链反应(PCR).产物在ABI Prism 377自动荧光测序仪进行电泳,以GeneScan 3.1和Genotyper 2.1软件进行扫描以及LOH分析.LOH结果与临床病理参数之间的关系比较采用χ2检验.结果 1q 31.1-32.1区域平均LOH率是22.98%.以D1S2622位点最高,为36.73%(18/49),最低是D1S412,为16.42%(11/67).结果 显示,更精确的缺失范围定位应该在D1S413和D1S2622之间(1q 31.3-32.1),约2 cM的遗传距离范围内.该区域各位点的LOH率与性别、年龄、肿瘤大小、生长方式以及肿瘤Dukes分期无明显相关.结论 将1q31.1-32.1区域高频等位基因缺失精细定位于D1S413和D1S2622位点之间,遗传学距离约2cM的区域内,提示在该区域存在与结直肠癌发生发展相关的抑癌基因.     

Comprehensive loss of heterozygosity analysis and identification of a novel hotspot at 3p21 in salivary gland neoplasms.

OBJECTIVES: We sought to assess loss of heterozygosity (LOH) profiles of 3p, 6q, 8q, 10q, 12q, 13q, and 17p and to identify the tumor suppressor genes involved in salivary gland neoplasms. STUDY DESIGN: LOH analysis was performed using 26 microsatellite markers by polymerase chain reaction-polyacrylamide gel electrophoresis method in 20 benign and 6 malignant salivary gland tumors. RESULTS: Overall, LOH was detected in at least one informative locus in 18 of 20 (90%) of benign tumors and in all of 6 cases of malignant tumors. High LOH frequencies were revealed at the loci D3S1307 (22%, 3p26), D3S966 (41%, 3p21), D6S255 (27%, 6q25), D8S166 (25%, 8q12), D8S199 (21%, 8q24), and D10S1765 (28%, 10q23) in benign tumors, defining the hotspot regions for putative tumor suppressor genes. CONCLUSIONS AND SIGNIFICANCE: The hotspot regions defined by the present study suggest that new tumor suppressor genes related to the development of salivary gland tumors may reside at several chromosomal loci, including loci at 3p, 6q, 8q and 10q.     

Loss of heterozygosity at 7q31.1 and 12p13-12 in advanced prostate cancer

BACKGROUND: Allelic losses on chromosome arms 2q, 3p, 5q, 6q, 7q, 8p, 9p, 10p, 10q, 11p, 11q, 12p, 13q, 16q, 17p, 17q, 18q, and 21q are reportedly associated with progression and/or initiation of prostate cancer. In the present study, we performed a polymerase chain reaction (PCR) analysis of polymorphic microsatellite loci on the human chromosomes 7 and 12p13-12 in prostate cancer tissue to investigate the extent of involvement of these regions, which may contain putative tumor suppressor genes. METHODS: Tissue samples were obtained at autopsy from 17 men who died of hormone-refractory prostate cancer at Chiba University, Japan, and affiliated hospitals between June of 1992 and June of 1995. DNA from normal tumor or metastatic tissue was used as the template for PCR amplification of a set of 16 polymorphic microsatellite loci on human chromosome 7 and 6 loci on the human chromosome region 12p13-12. RESULTS: The frequencies of cases with loss of heterozygosity (LOH) at 7q31.1 were 8% in primary tumor tissue and 11% in metastatic tissue. The frequencies of cases with LOH at 12p13-12 were 12% in primary tumor tissue and 25% in metastatic tumor tissue. CONCLUSIONS: In the present study, the frequencies of LOH at 7q31.1 were lower than in Western patients, suggesting that LOH in this region is not related to progression of prostate cancer in Japanese patients. The frequency of LOH at 12p13-12 was similar to that reported in Western countries, indicating that 12p13-12 may contain a tumor suppressor gene of prostate cancer.     

Analysis of loss of heterozygosity on chromosome 10 in patients with malignant astrocytic tumors: correlation with patient age and survival

OBJECT: The most frequent genetic abnormality in human malignant gliomas is loss of heterozygosity (LOH) on chromosome 10. Candidate genes on chromosome 10 that are associated with the prognosis of patients with anaplastic astrocytoma (AA) and glioblastoma (GBM) were evaluated. METHODS: The authors used 12 fluorescent microsatellite markers on both arms of chromosome 10 to study LOH in 108 primary astrocytic tumors. The LOH on chromosome 10 was observed in 11 (32%) of 34 AAs and 34 (56%) of 61 GBMs. No LOH was detected in 13 low-grade gliomas. Loss of heterozygosity was not detected in any AA in the seven patients younger than 35 years, but it was discovered in 41% of the patients older than 35 years. The prognostic significance of LOH at each locus was evaluated in 89 patients older than 15 years; 33 (37%) had supratentorial AAs and 56 (63%) had supratentorial GBMs. The Cox proportional hazards model, adjusted for patient age at surgery, the preoperative Karnofsky Performance Scale score, and the extent of surgical resection revealed that LOH on marker D10S209 near the FGFR2 and DMBT1 genes was significantly associated with shorter survival in patients with AA. The LOH on markers D10S215 and D10S541, which contain the PTEN/MMAC1 gene between them, was significantly associated with shorter survival in patients with GBM. CONCLUSIONS: In the present study it is found that LOH on chromosome 10 is an age-dependent event for patients with AAs and that LOH on marker D10S209 near the FGFR2 and DMBT1 loci is a significantly unfavorable prognostic factor. It is also reported that LOH on the PTEN/MMAC1 gene is a significantly unfavorable prognostic factor in patients with GBM.     

Loss of heterozygosity on chromosome 2 in Japanese patients with prostate cancer

BACKGROUND: Loss of heterozygosity (LOH) on chromosome 2 is thought to occur only occasionally in prostate cancer (PCa), but allelic losses in this region are frequent in other types of human cancer, such as lung, thyroid, head and neck, and cervix. Here, we show a high-resolution deletion map of markers on chromosome 2 in Japanese patients with PCa. METHODS: Tissue samples were obtained from 66 patients with PCa. DNA from normal, tumor, or metastatic tissue was used as the template for polymerase chain reaction amplification for LOH using 24 microsatellite markers on human chromosome 2. RESULTS: Nineteen of the 66 cases (29%) showed LOH for at least one locus on chromosome 2. LOH on 2p was observed more frequently in cancer death cases than in organ confined and regional diseases (P < 0.001). Paired DNAs were available from both primary and metastatic tumors in the eight cases of cancer death; among those pairs, we detected LOH on 2p in four primary tumors, and in all metastatic foci (P < 0.05). Detailed deletion mapping in these tumors identified four distinct commonly deleted regions on 2p 16.3, 2p 12-cent, 2q 21.3, and 2q 23.1-2q 32.1. CONCLUSIONS: These results suggest that inactivation of putative tumor suppressor genes on chromosome 2 that may play an important role in the progression of Japanese patients with PCa.     

Microsatellite analysis of allelic imbalance in tumour and blood from patients with prostate cancer

OBJECTIVE

To investigate whether a high frequency of allelic imbalance (AI) is associated with clinicopathological variables of patients with prostate cancer.

PATIENTS AND METHODS

We analysed loss of heterozygosity (LOH) and microsatellite (MS) instability (MSI) on circulating plasma DNA in a polymerase chain reaction (PCR)‐based MS study of 230 patients with prostate cancer and 43 with benign prostatic hyperplasia (BPH) using a panel of 13 polymorphic MS markers.

RESULTS

The overall incidence of AI was significantly higher in primary tumours (34%) than in blood plasma samples from patients with prostate cancer (11%). Although LOH (2.0%) and MSI (1.5%) were also found in BPH plasma samples, their frequencies were low. AI identified in plasma samples from patients with prostate cancer could be retrieved in 63% of the paired tumour samples. The highest concordance of AI and retention of heterozygosity between tumour and plasma samples was 83% at the marker D8S360. There were high frequencies of LOH at the markers THRB, D7S522 and D8S137 in both types of specimens. The markers D11S898 and D11S1313 on the chromosome arm 11q showed frequent MSI. The comparison with established risk factors showed significant associations of an increase in prostate volume with AI at the combined markers D6S474/D7S522 in tumour tissues and at D7S522 in plasma samples (P < 0.04). In the primary tumours there was a further correlation of LOH at D11S1313 with increasing tPSA value (P = 0.005). The combination of total prostate‐specific antigen (PSA) and % free PSA was associated with LOH at THRB in plasma samples.

CONCLUSIONS

Plasma‐based MS analysis may have clinical value for the molecular staging of prostate cancer.     

Loss of heterozygosity analysis identifies genetic abnormalities in mycosis fungoides and specific loci associated with disease progression

Mycosis fungoides (MF) exhibits a variety of underlying molecular defects. Loss of heterozygosity (LOH) is a technique used to detect chromosomal imbalances in neoplastic disorders using archival tissue. We analyzed skin biopsies of MF in different stages for the presence of LOH at specific loci to evaluate underlying genetic aberrations involved in MF and its progression. Twenty-five skin biopsies (15 plaque stage and 10 tumor stage) from 19 patients were evaluated. LOH was examined at 1p22 (D1S2766), 9p21 [IFNA, p15 (D9S1748), p16 (D9S171)], 10q23 [PTEN (D10S185, D10S541, D10S2491)], and 17p13 [p53 (TP53)]. Abnormal lymphocytes were microdissected from formalin-fixed, paraffin-embedded tissue sections. Sixteen of the 25 (64%) specimens evaluated had at least one abnormal LOH locus and LOH was identified in 7 of 15 (47%) plaque and in 9 of 10 (90%) tumor stage lesions, respectively. All 3 patients with sequential biopsies (plaque followed by tumor lesions) had additional LOH abnormalities in tumor specimens compared with plaque stage lesions. LOH most frequently involved chromosome 10, including 7 of 10 (70%) tumor stage lesions. Loss of multiple alleles was only identified in tumor stage cases, with 3 tumors undergoing allelic losses at 3 separate loci. Our results suggest that LOH studies are a robust method for evaluating genetic abnormalities in MF. Tumor stage lesions manifest increasing allelic losses compared with plaque stage. Further, in this series, several loci associated with the tumor suppressor gene PTEN on chromosome 10 appear to be associated with progression from plaque to tumor stage.     

Chromosome 16 allelic loss analysis of a large set of microdissected prostate carcinomas.

PURPOSE: To perform loss of heterozygosity (LOH) analysis on chromosome 16 in 102 highly purified DNA samples isolated from one or more adenocarcinomas, prostatic intraepithelial neoplasia (PIN), and matched benign prostatic epithelium from 95 radical prostatectomy patients. MATERIALS AND METHODS: Specimens were procured by microdissection of frozen tissue samples, thus ensuring that highly select pure populations of cells were obtained for DNA extraction and LOH analysis. Multiple microsatellite markers were used to determine allelic loss on chromosome 16q. RESULTS: Overall loss on 16q was seen in 31% of the cancers, and occurred more frequently in high stage cancers than low stage cancers. In contrast, allelic loss in PIN failed to exceed 6% at any of the loci that were examined. CONCLUSIONS: These results suggest that inactivation of a putative tumor suppressor gene on 16q may be involved in the progression of some prostate cancers.