Mutations in BHD and TP53 genes, but not in HNF1beta gene, in a large series of sporadic chromophobe renal cell carcinoma

BHD, TP53, and HNF1beta on chromosome 17 were studied in 92 cases of renal cell carcinoma (46 chromophobe, 19 clear cell, 18 oncocytoma, and nine papillary). Six, thirteen, and zero cases had, respectively BHD, TP53, and HNF1beta mutations, (84% mutations involved chromophobe), suggesting a role for BHD and TP53 in chromophobe subtype.     

Chromosomal aberrations in sporadic pituitary tumors

Pituitary adenomas are common intracranial neoplasms that may be hormone-secreting or nonfunctional. Genetic defects associated with some pituitary tumors have been identified, although our understanding of the underlying molecular mechanisms remains incomplete. We have studied 75 sporadic pituitary tumors, representing the major clinical subtypes, by comparative genomic hybridization (CGH) with the aim of assessing for DNA copy number changes. CGH revealed chromosomal imbalances in 34 adenomas (45.3%), whereby gains were 4.9 times more frequently observed than losses. Most of the genetic alterations detected by CGH affected entire chromosomes (108/131, 82.4%). Gain of genetic material was observed predominantly on chromosomes X (24/75, 32%), 19 (12/75, 16%), 12 (6/75, 6.7%), 7 and 9 (5/75, 6.7%), whereas loss of DNA sequences most frequently affected chromosomes 11 (4/75, 5.3%), 13 and 10 (3/75, 4%). There were no significant differences in the CGH results for the individual clinical subtypes of pituitary tumors. These results reveal a nonrandom pattern of chromosomal alterations in pituitary tumors, in particular gains of entire chromosomes, and this may contribute to the development of such neoplasms.     

p53 Mutations in sporadic adrenocortical tumors

Non-familial human adrenocortical adenomas and carcinomas were screened for mutations in exons 5–8 of the p53 tumor suppressor gene by single-strand-conformation-polymorphism (SSCp) analysis, followed by direct sequencing of PCR-amplified DNA. point mutations in codons 12, 13 and 61 in H-ras, K-ras and N-ras proto-oncogenes were similarly assessed by direct DNA sequencing. Three out of 15 primary adrenocortical carcinomas (20%) contained a mis-sense point mutation in the conserved regions (exons 5 and 8) of the p53 gene. Mutations were located in codon 157 (GTC → TTC; Val → phe), codon 163 (TAC → AAC; Tyr → Asn), and codon 273 (CGT → TGT; Arg → Cys). The mutation in codon 157 was detected in the primary tumor as well as in brain and lymph-node metastases. Among 18 adrenocortical adenomas, there was only a single non-miscoding mutation in codon 295 (CCT → CCC; pro → pro). These data suggest that mutational inactivation of the p53 gene occurs in a minority (20%) of sporadic adrenocortical carcinomas and that these mutations constitute a late event in the multi-step process of malignant transformation. No ras mutations were detected in any of these tumors, suggesting that these genes are not involved in the development of tumors originating from the adrenal cortex.     

大肠肿瘤APC基因突变的研究

目的检测ＡＰＣ基因在国人散发性大肠肿瘤中的突变情况,并探讨ＡＰＣ基因突变与大肠肿瘤生物学行为的关系。方法采用ＰＣＲＳＳＣＰ、ＤＮＡ测序对２７例（３３份标本）大肠息肉,３６例大肠癌和相应正常粘膜及３例家族性腺瘤性息肉瘤（ＦＡＰ）标本中ＡＰＣ基因“突变密集区”（ｍｕｔａｔｉｏｎｃｌｕｓｔｅｒｒｅｇｉｏｎＭＣＲ）的突变进行了研究。结果大肠息肉和癌组织中,ＡＰＣ基因ＭＣＲ突变率分别为３０．３％（１０／３３）和３５．９％（１４／３９）,两者差异无显著性,而正常大肠粘膜、炎性息肉和增生性息肉均无突变。３例ＦＡＰ发现有２例突变,其中１例从正常粘膜到腺瘤、到癌变组织均有突变,另１例则在＞１．０ｃｍ的腺瘤和肝转移癌组织有突变,测序结果证实该例在１４２５号密码子存在相同点突变。ＡＰＣ突变与肿瘤的临床病理特征无明显的相关性。结论ＡＰＣ不仅在ＦＡＰ中存在突变,而且在散发性大肠肿瘤中亦存在突变;它的突变至少参与了部分大肠癌的发生发展过程,而且是这一过程中较早发生的事件。     

Immunoexpression of lactoferrin in human sporadic renal cell carcinomas

By immunohistochemistry, lactoferrin (Lf) expression was retrospectively investigated in 40 formalin-fixed paraffin-embedded kidney samples, obtained at surgery from an equal number of patients. Histologically, 28 cases were clear cell carcinomas (CCC), 7 papillary carcinomas (PC) and 5 chromophobe carcinomas (CC). Ten specimens of unaffected renal parenchyma were utilized as tissue control. On 4-microm thick sections, the Lf immunoreactivity was revealed either by a rabbit polyclonal or mouse monoclonal anti-human Lf antisera; the quantification of Lf immunoreactivity was performed using an intensity-distribution (ID) score. A positive immunoreaction by both anti-Lf antibodies was found in 62.5% (25/40) of RCC, mainly evident and diffuse by monoclonal antiserum. The immunoreactivity was observed in the cytoplasmic boundary of neoplastic cells in CCC and PC, while in CC Lf showed a diffuse granular cytoplasmic localization. Moreover, significant differences in Lf ID score were found among CCC and non-CCC variants (P<0.00001), the former showed a lower score; no relationships between immunohistochemical data and the sex or age of patients, grade of RCC, stage of the disease or degree of terminal anemia were encountered. Normal unaffected tubular structures were positive for Lf; glomeruli were unstained. The reduced Lf immunoexpression in some CCC may be because of the down-regulation of Lf gene due to the frequent deletion of 3p regions reported in this RCC variant.     

Inactivation of the ARF-MDM-2-p53 pathway in sporadic Burkitt's lymphoma in children.

Burkitt's lymphomas (BLs) are characterized by an activated MYC gene that provides a constitutive proliferative signal. However, activated myc can initiate ARF-dependent activation of p53 and apoptosis as well. Data derived from cell culture and animal models suggest that the inactivation of the ARF-MDM-2-p53 apoptotic signaling pathway may be a necessary secondary event for the development of BL. This has not been tested in freshly excised BL tissue. We investigated the ARF-MDM-2-p53 pathway in tumor specimen from 24 children with sporadic BL/B-ALL. Direct sequencing revealed a point mutation in the p53 gene in four BL. Overexpression of MDM-2 was evident in 10 of the BL samples analyzed by real-time quantitative PCR. Deletion of the CDKN2A locus that encodes ARF or reduced expression of ARF could not be detected in any BL by fluorescence in situ hybridization analysis or real-time quantitative PCR, respectively. Our results indicate that the ARF-MDM-2-p53 apoptotic pathway is disrupted in about 55% of the cases of childhood sporadic BL. We suggest that in addition to the inactivation of the ARF-MDM-2-p53 protective checkpoint function other antiapoptotic mutations may occur in a substantial part of children with sporadic BL.     

Molecular profiling of sporadic colorectal tumors by microsatellite analysis

To investigate the prognostic value of multiple genetic alterations, individual molecular tumor profiles were established in 79 sporadic colorectal carcinomas (41 stage II and 38 stage III). Tumors were analyzed for allelic loss (LOH) and genetic instability (MSI) using 14 microsatellites intragenic to or associated with tumor suppressor or DNA mismatch repair genes. Molecular profiling identified tumors with LOH at multiple loci without microsatellite instability (MSS), tumors with high levels of LOH and low level microsatellite marker instability (MSI-L), and tumors with high levels of MSI (MSI-H), but rare LOH. K-ras mutations occurred more frequently in MSS/MSI-L carcinomas (26%) than in MSI-H colorectal tumors (10%), the latter showing a high frequency of TGFbeta type II frameshift mutations (82%). Correlation of molecular and clinical data revealed a better prognosis for stage III tumor patients displaying 5q12 loss rather than retention of heterozygosity. Thus, molecular profiling allows the identification of new prognostic markers and might facilitate the stratification of colorectal cancer patients.     

Multiple primary malignancies in patients with sporadic pancreatic endocrine tumors

BACKGROUND: To investigate the appearance of multiple primary malignancies in patients with sporadic neuroendocrine pancreatic tumors (NEPTs). METHODS: One hundred forty-five patients with NEPTs were treated at the Department of Surgery, Philipps-University Marburg. Multiple primary malignancies included tumors that were not considered to be a metastasis, invasion, or recurrence of NEPTs. Data on sex, age at diagnosis of cancer, follow-up time after diagnosis, and death rate were collected. RESULTS: Of 115 patients with sporadic NEPTs, 15 (13.0%) patients were identified with at least one malignant tumor, other than a NEPT. The median age at diagnosis of the associated tumor(s) was 57 years (range, 10-72 years). Two of the 15 patients had insulinomas, 5 had gastrinomas and 8 had non-functioning NEPTs, respectively. The risk of developing multiple cancers was the highest for patients with gastrinoma (21.7%), followed by patients with non-functioning NFPTs (20.5%). CONCLUSIONS: In patients with NEPTs multiple primary malignancies are found more frequently than in the general population. The etiology of the increased risk of other primaries is not clearly defined, but it may be the result of accumulated growth stimulation by the secreted hormones or a genetic alteration that leads to tumorogenesis in these patients.     

Microsatellite instability occurs infrequently in sporadic renal cell carcinoma

Forty-nine sporadic renal cell carcinomas were screened for instability at nine different microsatellite loci. Three tumors (6.1%) showed alterations at more than one locus. One chromophobe-cell renal carcinoma showed microsatellite instability at 3 loci and was considered to exhibit a replication error-positive phenotype. Two of the tumors with clear-cell histology showed minor alterations at one of the nine loci examined, These data indicate that microsatellite instability occurs infrequently in sporadic RCC and that the mutator phenotype may be involved in rare instances such as the chromophobe-cell carcinoma.     

Frequent microsatellite instability in sporadic tumors of the upper urinary tract

Urothelial carcinoma of the renal pelvis and ureter may develop sporadically or as a manifestation of hereditary nonpolyposis colorectal cancer. The majority of hereditary nonpolyposis colorectal cancer is caused by mutation of the human DNA mismatch repair (MMR) genes and is detected by associated microsatellite instability (MSI). Seventy-three unselected urothelial carcinomas of the ureter and/or renal pelvis were screened for MSI using the National Cancer Institute-designated reference panel (plus BAT40). Instability of at least two microsatellite markers (MSI-high) was detected in 15 samples (21%). Immunohistochemical staining of the MMR proteins (hMSH2, hMLH1, or hMSH6) was absent in 13 of 15 (87%) MSI tumors, and alteration of coding sequence microsatellites (TGFbetaRII, Bax, hMSH3, and hMSH6) was found at frequencies of 7-33% in these samples. Tumors with MSI had significantly different clinical and histopathological features including higher prevalence in female patients, low tumor stage and grade, and a papillary and frequently inverted growth pattern. Our results suggest a molecular pathway of tumorigenesis that is similar to MMR-deficient colorectal cancers and consistent with the notion that the site distributions of hereditary or sporadic MSI-high tumors may reflect tissue-specific susceptibility to lesions processed by the MMR machinery.     

Hypercalcemia in childhood renal tumors

Hypercalcemia is an uncommon complication of childhood renal tumors. It is exclusively seen in infants 6 months of age or younger with malignant rhabdoid tumor of the kidney (MRTK) or congenital mesoblastic nephroma (CMN). Secretion of parathormone or prostaglandin E2 by the tumor cells is responsible for the hypercalcemia in most of these patients. Bone metastasis has been notably absent in these patients, and the hypercalcemia completely resolves with the removal of the tumor. Hypercalcemia in itself probably does not have any prognostic significance; however, it may serve as a tumor marker in some patients. Early recognition and effective management of this complication may prevent the acute life-threatening as well as the longstanding complications of this serious metabolic disorder.     

Analysis of molecular pathways in sporadic neuroendocrine tumors of the gastro-entero-pancreatic system

Little is known about the molecular pathogenesis of neuroendocrine tumors (NET) of the gastro-entero-pancreatic (GEP) system. We analyzed genetic and epigenetic alterations as well as the CpG island methylator phenotype (CIMP). The study comprised 118 well-differentiated fore- and mid-gut GEP-NET from 71 patients. In addition to loss of heterozygosity (LOH), microsatellite instability (MSI) and the methylation status of various tumor associated genes were examined. The expression profile of p16, APC and MENIN was investigated by immunohistochemistry. None of the tumors was highly microsatellite unstable, LOH was found in 22.2%. Significant differences in promoter hypermethylation were identified in the RUNX3 and the O(6)-MGMT genes. We found a significant loss of p16 expression in insulinomas (p = 0.05) and functional NET (p = 0.01), respectively. APC was expressed less in gastrinomas (p = 0.01) and functional GEP-NET (p = 0.05) vs. nonfunctional tumors. MENIN expression was reduced in pancreatic vs. extrapancreatic NET (p = 0.008) and in insulinomas vs. nonfunctional GEP-NET (p = 0.019) and NET associated with the carcinoid syndrome (p = 0.029). Further CIMP and a Ki-67 index >10% showed a close correlation. Outcome analysis of 19 patients showed a better survival for CIMP-negative patients. The analyses identified significant genetic and epigenetic alterations in well-differentiated fore- and mid-gut NET. CIMP, similar to Ki-67, might turn out to be of prognostic relevance.     

Somatic von Hippel-Lindau gene mutations detected in sporadic endolymphatic sac tumors

Endolymphatic sac tumors (ELSTs) occur sporadically or in association with an autosomal dominantly inherited tumor syndrome, von Hippel-Lindau (VHL) disease. In VHL disease, a germline mutation of the VHL tumor suppressor gene is inherited, and loss of function of the wild-type allele occurs through genetic deletion with subsequent development of neoplastic growth. Genetic alterations associated with sporadic ELSTs are less well understood. In this study, we used tissue microdissection to selectively analyze neoplastic cells from four sporadic ELSTs. In two cases, we detected somatic mutations involving VHL gene exons 1 and 2, respectively. Additionally, one of these cases revealed deletion of the VHL gene locus. Two cases did not reveal VHL gene mutation; one of these two cases showed VHL gene deletion. These results suggest that mutations and allelic deletions of the VHL tumor suppressor gene play a role in the tumorigenesis of sporadic ELSTs.     

Delayed intervention of sporadic renal masses undergoing active surveillance

BACKGROUND: Prompt surgical management remains the standard of care for renal cell carcinoma (RCC). Occasionally, it is necessary to postpone or delay surgical treatment. The authors of this report assessed whether delayed intervention following a period of active surveillance altered minimally invasive or nephron-sparing treatment plans, increased the risk of stage progression, and/or decreased recurrence-free survival rates. METHODS: The authors searched their institutional kidney cancer database to identify small (< or =4 cm in greatest dimension on presentation), enhancing renal masses for which treatment initially was delayed or refused. Clinical, radiographic, and pathologic records were reviewed to determine linear tumor growth kinetics, alterations in treatment plan, stage migration, and cancer-specific outcomes related to delayed intervention. RESULTS: Eighty-seven sporadic, localized, enhancing renal masses were identified in 82 patients who had management postponed for a median of 14 months (mean, 21 months; range, 6-97 months). Median tumor diameter was 2.0 cm on presentation. Treatment in 60 of 87 tumors (69%) was delayed for > or =12 months, and treatment was delayed for > or =24 months in 29 of 87 tumors (33%). Overall, 66 of 87 tumors (76%) underwent nephron-sparing approaches. In addition, 52 of 87 tumors (60%) were treated in a minimally invasive fashion. Pathology confirmed RCC in 73 of 87 treated tumors (84%). Fourteen of 54 tumors (26%) that were treated by surgical extirpation were high-risk tumors, and 3 of 54 tumors (6%) were upstaged on pathologic review. CONCLUSIONS: The majority of small, sporadic, clinically localized renal tumors demonstrated slow interval growth. The management of these lesions may be delayed cautiously without limiting or complicating the available treatment options or incurring a high risk of disease progression.     

Lack of mutation of the folliculin gene in sporadic chromophobe renal cell carcinoma and renal oncocytoma

Germline mutation of the folliculin gene (BHD) at chromosome 17p11.2 is associated with the development of multiplex hamartomas of the hair follicles, chromophobe renal cell carcinomas (RCC) and renal oncocytomas (RO). We have analyzed the folliculin gene with sequencing for mutations and the chromosome 17p11.2 with microsatellites for allelic changes in sporadic ROs and chromophobe RCCs. Allelic loss at chromosome 17 was seen in 8 of 8 chromophobe RCCs whereas none of the 8 RO showed alteration at this chromosomal region. Sequencing all exons from genomic DNA failed to disclose mutations of the folliculin gene in any of the tumors. We found a single nucleotide polymorphism (SNP) of G/A (nt 74) at the first exon in the untranslated region of the folliculin gene. We did not find a correlation between the SNP G/A or loss of the G allele and the expression level of either splice variants of the folliculin gene. Our data suggest the folliculin gene does not play a role in the tumorigenesis of sporadic chromophobe RCCs and renal oncocytomas.     

COL11A1 in FAP polyps and in sporadic colorectal tumors

Background  

We previously reported that the α-1 chain of type 11 collagen (COL11A1), not normally expressed in the colon, was up-regulated in stromal fibroblasts in most sporadic colorectal carcinomas. Patients with germline mutations in the APC gene show, besides colonic polyposis, symptoms of stromal fibroblast involvement, which could be related to COL11A1 expression. Most colorectal carcinomas are suggested to be a result of an activated Wnt- pathway, most often involving an inactivation of the APC gene or activation of β-catenin.     

Radiofrequency ablation of renal tumors

Development of cross-sectional imaging has led to a significant increase in diagnosis of small renal tumors. Nephron-sparing surgery has proven to be effective in the management of these small tumors. Could radiofrequency ablation be as effective in the management of these patients, after showing promising results in a selected group of patients? In this article we discuss the principles of radiofrequency ablation and present results in a selected group of patients. We also outline future perspectives of this noninvasive technique.