High frequency of RPL22 mutations in microsatellite-unstable colorectal and endometrial tumors.

Ribosomal Protein L22 (RPL22) encodes a protein that is a component of the 60S subunit of the ribosome. Variants in this gene have recently been linked to cancer development. Mutations in an A8 repeat in exon 2 were found in a recent study in 52% of microsatellite-unstable endometrial tumors. These tumors are particularly prone to mutations in repeats due to mismatch repair deficiency. We screened this coding repeat in our collection of microsatellite-unstable endometrial tumors (EC) and colorectal tumors (CRC). We found 50% mutation frequency for EC and 77% mutation frequency for CRC. These results confirm the previous study on the involvement of RPL22 in EC and, more importantly, reports for the first time such high mutation frequency in this gene in colorectal cancer. Furthermore, considering the high mutation frequency found, our data point toward an important role for RPL22 in microsatellite instability carcinogenesis.

New target genes in endometrial tumors show a role for the estrogen-receptor pathway in microsatellite-unstable cancers.

Microsatellite instability (MSI) in tumors results in an accumulation of mutations in (target) genes. Previous studies suggest that the profile of target genes differs according to tumor type. This paper describes the first genome-wide search for target genes for mismatch repair-deficient endometrial cancers. Genes expressed in normal endometrium containing coding repeats were analyzed for mutations in tumors. We identified 44 possible genes of which seven are highly mutated (>15%). Some candidates were also found mutated in colorectal and gastric tumors. The most frequently mutated gene, NRIP1 encoding nuclear receptor-interacting protein 1, was silenced in an endometrial tumor cell line and expression microarray experiments were performed. Silencing of NRIP1 was associated with differences in the expression of several genes in the estrogen-receptor network. Furthermore, an enrichment of genes related to cell cycle (regulation) and replication was observed. We present a new profile of target genes, some of them tissue specific, whereas others seem to play a more general role in MSI tumors. The high-mutation frequency combined with the expression data suggest, for the first time, an involvement of NRIP1 in endometrial cancer development.

KRAS mutation profile in colorectal carcinoma and novel mutation--internal tandem duplication in KRAS.

Oncogenic KRAS mutations are associated with resistance to anti-EGFR therapy in colorectal carcinoma. Since anti-EGFR monoclonal antibodies are employed in clinical practice in advanced colorectal cancer, KRAS mutations have become an important predictor of therapy outcome. Mutational analysis of KRAS was performed on 163 adenocarcinoma samples. Exons 1-3 of KRAS were analyzed using SSCP and sequencing. Fifty seven (35%) carcinomas had missense point mutations in one of codons 12, 13, 59, 61, 117. In accordance with the published data, missense mutations in codons 12 (66%) and 13 (22%) were the most frequent. Mutations in codons 59 and 117 occurred with the same frequency as in codon 61. The only detected insertion occurred in exon 2. 15-bp insertion resulted in tandem duplication of codons 62-66. Presumably, 5 additional amino acids affected switch II conformation and sustained Ras activity due to decreased GTP hydrolysis. We report this unusual new type mutation.

CDH1 gene promoter hypermethylation in gastric cancer: relationship to Goseki grading, microsatellite instability status, and EBV invasion.

Hypermethylation of the CDH1 promoter region seems to be the most common epigenetic mechanism in this gene silencing in gastric cancer. In this study, CDH1 promoter hypermethylation was observed in 54.8% (46/84) of the analyzed sporadic gastric carcinomas. We introduce a new relation: clustering of Goseki grading into 3 grade was determined by CDH1 promoter hypermethylation. The percentage of methylation in Goseki III cancers was significantly higher (83%) when compared with other grades; the lowest proportion was detected in IV (36%) and II (38%) groups, whereas grade I demonstrated typical percentage of promoter hypermethylation. A novel polymorphism R732R in exon 14 of the CDH1 gene was detected by mutational analysis. Additionally, all cases with the MSI-high phenotype revealed CDH1 promoter hypermethylation. In MSI-low and MSS gastric cancers, this percentage was lower, reaching 71% and 41%, respectively. Moreover, the methylation status was correlated with the LOH phenotype. We detected CDH1 promoter hypermethylation in all EBV-positive gastric cancers (5/5), whereas methylation in the EBV-negative group occurred in 58% of cases. We also report that "methylated" tumors were slightly larger than "nonmethylated," whereas the second group revealed a higher probability of longer patient survival, though these relationships were not statistically significant. These results suggest that downregulation of E-cadherin, caused by promoter hypermethylation, in sporadic gastric carcinomas may be associated with a worse prognosis and specific tumor phenotype.

Synchronous serrated adenoma of the appendix and high-grade ovarian carcinoma: a case demonstrating different origin of the two neoplasms.

Association of mucinous adenomas of the appendix and mucinous ovarian tumors is well known. The origin of the ovarian tumor (metastasis from the appendix vs independent primary) is still debated. Serrated adenoma is a rare neoplasm of the distal gastrointestinal tract, and its precancerous role in the colorectum was recently postulated. A 74-year-old patient was subjected to hysterectomy with routine appendectomy due to a 17-cm tumor of her right ovary. Histological examination revealed a high-grade ovarian adenocarcinoma with peritoneal involvement. The appendix, grossly unremarkable, harbored a serrated adenoma with no evidence of invasion or malignant transformation. Immunohistochemical examination revealed CD7+, CK20-phenotype of the ovarian and reverse (CK7-, CK20+) phenotype of the appendiceal tumor. Microsatellite analysis demonstrated microsatellite instability (MSI-high) within the serrated adenoma (4/5 markers with positive amplification) and no MSI (0/6 amplified markers) in the samples from the ovarian carcinoma, its metastases and the uninvolved uterine cervix. There were also differences in LOH pattern between the ovarian adenocarcinoma and the serrated adenoma. The findings suggest two independent primaries with profound differences in tumorigenetic pathways of both lesions. To the best of our knowledge this is the first report of synchronous serrated adenoma of the appendix and ovarian carcinoma.

CDX-2 expression is reduced in colorectal carcinomas with solid growth pattern and proximal location, but is largely independent of MSI status.

The homeobox genes are transcription factors that control the development of tissues and organs. In the colon one of such genes is CDX-2. In colorectal carcinomas, the CDX-2 expression is reduced. The aim of the present study was to investigate the presence of CDX-2 in colorectal carcinomas and to relate it to the histological features and microsatellite stability status. The material consisted of 20 carcinomas without microsatellite instability, 19 cases with low microsatellite instability and 19 cases with high microsatellite instability. CDX-2 expression was investigated using immunohistochemistry with CDX2-88 monoclonal antibody and assessed semiquantitatively. In 10 cases no expression of CDX-2 was observed, while in 6 the protein was present in less than 25% of tumor cells. It was noted that reduced expression of CDX-2 was more frequent in carcinomas situated proximally to the splenic flexure (p < 0.015) and in tumors with solid growth pattern (p < 0.03). On the other hand, no significant differences were encountered between groups differing in microsatellite stability. The results suggest that the major factors that determine the presence of CDX-2 in colorectal carcinomas at the protein product level may include cancer location and the solid phenotype of the tumor.

Fatal post-transplant lymphoproliferative disorder following allogeneic bone marrow transplantation for aplastic anemia.

Post-transplant lymphoproliferative disorder (PTLD) constitutes a serious complication of allogeneic bone marrow transplantation. We describe a case of PTLD in a twenty-six year-old male treated with bone marrow transplantation for aplastic anemia of unknown cause. The patient received unmanipulated marrow graft from his HLA-matched brother. Fifty-one days post transplant he developed progressive enlargement of cervical lymph nodes, followed by hepatosplenomegaly and generalized lymphadenopathy. Polymorphic PTLD was diagnosed basing on the lymph node histopathology, positive EBV detection, flow cytometry and IgH rearrangement studies proving monoclonality (capillary electrophoresis with ABI PRISM 310 Genetic Analyzer). There was no response to anti-CD20 antibody, cessation of immunosuppression, donor lymphocyte infusion and cytostatic therapy. The patient died on the 65th day of multiple organ failure. We discuss the diagnostics and management of PTLD in the setting of bone marrow transplantation.

Dose response and kinetics of foci disappearance following exposure to high- and low-LET ionizing radiation.

PURPOSE: The effect of different radiation qualities on (i) 53BP1 (p53 Binding Protein 1) and p-ATM (phosphorylated ataxia telangiectasia mutated) foci induction, and (ii) on the kinetics of foci disappearance was analysed. MATERIAL AND METHODS: Normal human skin fibroblasts were exposed to 240 kV broad-field X-rays or targeted with individually counted helium ((3)He) particles or protons ((1)H) from a Charged Particle Microbeam. Anti-p-ATM and anti-53BP1 antibodies were used for foci visualisation via immunocytochemistry. RESULTS: 1 Gy of X-rays yielded approximately 33 53BP1-positive foci/cell. The ratio between the number of delivered particles and yielded tracks was found to be 1:1 and 3:1 after targeted (3)He and (1)H irradiation, respectively. It was determined that approximately 50% of radiation-induced damage was repaired as measured by loss of foci during the first 2, 6, and 10 hours following X-ray, protons, and (3)He irradiation, respectively. CONCLUSIONS: There was significant radiation quality dependence for 53BP1- and p-ATM-positive foci induction observed. Foci disappearance was radiation dose-independent in the samples irradiated with X-rays. Our results confirm that kinetics of foci disappearance depends on radiation quality, even when individual ions are targeted to cells.

Colorectal carcinoma in Poland in 1975 and 1995: not only more, but also different.

BACKGROUND AND AIMS: We previously reported that the sole clinicopathological parameters of carcinomas diagnosed in a single institution in 1975 differed from those in patients diagnosed in 1995. The findings might be compatible with the loss of importance of the microsatellite instability of the carcinogenic pathway. MATERIALS AND METHODS: We examined the microsatellite status and selected immunomarkers (Ki-67, p53, BAX) in the archival material from 1975 (n=76) and 1995 (n=105). RESULTS AND CONCLUSION: The distribution of tumors showing no microsatellite instability, low microsatellite instability, and high microsatellite instability in the 2-yearly cohorts was similar (1975: 55.6%, 22.2%, 22.2%; 1995: 60.2%, 20.4%, 19.4%, respectively). The percentage of carcinomas showing microsatellite instability at the APC locus differed significantly (1975: 37.5%; 1995: 21.4%). The typical clinicopathological parameters of carcinomas exhibiting high microsatellite instability were largely shared by the carcinomas demonstrating instability at the APC locus. The carcinomas resected in 1995 more frequently demonstrated high expression of an antiapoptotic protein BAX and a different distribution of their Ki-67 proliferation fraction. The evolution of colorectal carcinoma in Poland also involves qualitative changes, including its genetic background.

Low-level microsatellite instability colorectal carcinomas: do they really belong to a "gray zone" between high-level microsatellite instability and microsatellite-stable cancers?

BACKGROUND AND AIMS: Colorectal carcinomas demonstrating low-level microsatellite instability (MSI-L) may form a distinct group differing both from high-level MSI (MSI-H) and microsatellite-stable (MSS) tumors. MATERIALS AND METHODS: In a retrospective series of 172 colorectal carcinomas the microsatellite status was examined based on DNA extracted from archival blocks. Three groups - MSS ( n=100), MSI-L ( n=37), MSI-H ( n=35) - were compared with respect to clinical data, stage, histology, and immunoexpression of Ki-67, and P53. RESULTS: Compared to MSS and MSI-H carcinomas the MSI-L tumors were exceptionally rarely right-sided, and demonstrated the lowest proliferation fraction. There was a trend for less frequent high-grade histology, more frequent intermediate P53 expression, and prominent mucinous histology. CONCLUSION: Features of MSI-L colorectal carcinomas are not necessarily located between their MSS and MSI-H counterparts. The MSI-L category may contain a group of tumors belonging to a distinct carcinogenetic pathway.