Promoter hypermethylation and expression of sprouty 2 in endometrial carcinoma

Sprouty 2 is a key antagonist regulator of receptor tyrosine kinases, and downstream signaling pathways, like fibroblastic growth factor (FGF) and Ras-mitogen-activated protein kinase (RAS-MAPK). By controlling these pathways, sprouty 2 is involved in regulation of cell proliferation, differentiation, and angiogenesis. Alterations in fibroblastic growth factor receptor (FGFR) and members of the RAS-MAPK pathway are frequent in endometrial carcinoma. The expression of sprouty 2 has been found to be decreased in several types of human cancer, by mechanisms of promoter methylation. In the present study, we have assessed the expression of sprouty 2 in endometrial carcinoma, in correlation with sprouty 2 promoter methylation. Sprouty 2 immunohistochemical expression was assessed using 3 different tissue microarrays: one constructed from paraffin blocks of 80 samples of normal endometrium and 2 tissue microarrays containing samples of 157 endometrial carcinoma (1 tissue microarray constructed with 95 endometrial carcinomas previously studied for microsatellite instability and alterations in phosphatase and tensin homolog (PTEN), k-ras, and b-catenin, and 1 tissue microarray containing 62 endometrial carcinoma, which were also subjected to sprouty 2 promoter methylation analysis). The immunohistochemical expression of sprouty 2 was correlated with cellular proliferation (Ki67) and clinicopathologic data. Sprouty 2 promoter methylation was assessed by methylation-specific polymerase chain reaction, with DNA obtained from fresh-frozen samples of endometrial carcinoma and corresponding normal tissues, and correlated with promoter methylation of RAS association domain family-1A (RASSF1A). A highly significant decrease in sprouty 2 immunoexpression was seen in the proliferative phase of normal endometrium (P < .001). Differences were detected between types I and II endometrial carcinoma, but they were not statistically significant. Reduced immunoexpression of sprouty 2 was seen in 19.85% of endometrial carcinoma and was strongly and inversely associated with increased cell proliferation (Ki67; r = -0.367; P = .001). Sprouty 2 promoter methylation was detected in 31 (53.4%) of 58 endometrial carcinomas. Results from our study show that alterations in sprouty 2 may be involved in endometrial carcinogenesis by controlling cell proliferation.     

Molecular pathology of endometrial hyperplasia and carcinoma.

Four different genetic abnormalities may occur in endometrioid adenocarcinomas of the endometrium (mircosatellite instability and mutations in the PTEN, k-RAS and beta-catenin genes), whereas nonendometrioid carcinomas of the endometrium often have p53 mutations and loss of heterozygosity on several chromosomes. Occasionally, a nonendometrioid carcinoma may develop as a result of dedifferentiation of a preexisting endometrioid carcinoma; in such a case, the tumor exhibits overlapping clinical, morphologic, immunohistochemical, and molecular features of the 2 types. The insaturation of microsatellite instability in endometrial carcinogenesis seems to occur late in the transition from complex hyperplasia to carcinoma, and it is preceded by progressive inactivation of MLH-1 by promoter hypermethylation. Moreover, the endometrioid adenocarcinomas that exhibit microsatellite instability show a stepwise progressive accumulation of secondary mutations in oncogenes and tumor suppressor genes that contain short-tandem repeats in their coding sequences. Mutations in the PTEN and k-RAS genes are also frequent in endometrioid adenocarcinomas of the endometrium, particularly in the tumors that exhibit microsatellite instability, whereas beta-catenin mutations do not seem to be associated with such a phenomenon.     

PIK3CA gene mutations in endometrial carcinoma: correlation with PTEN and K-RAS alterations

Alterations in the phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathway are common in endometrial carcinoma. Inactivation of the tumor suppressor gene PTEN leads to a constitutively active PI3K pathway, which plays a role in the early steps of endometrial tumorigenesis. Other alterations in the PI3K/AKT pathway are mutations in the PIK3CA gene, which encode the p110alpha catalytic subunit of PI3K. PIK3CA mutations cluster to the helical (exon 9) and the kinase (exon 20) domains of the gene. In endometrial carcinomas, PIK3CA mutations have been found to coexist frequently with PTEN mutations, but it is not clear whether they occur in cells with monoallelic or biallelic inactivation of PTEN. In the present study we have evaluated PIK3CA mutational status in a series of 33 endometrial carcinomas, previously screened for microsatellite instability and mutations in PTEN, K-RAS, and CTNNB-1. The tumors were also evaluated for loss of heterozygosity on 10q23 and hypermethylation of the promoter region of PTEN/psiPTEN to assess the monoallelic or biallelic inactivation status of PTEN. PIK3CA mutations were detected in 8 (24%) of the 33 cases. Seven mutations were located in exon 20 and 1 in exon 9. PTEN alterations were found in 19 cases (57%). Biallelic inactivation of PTEN was demonstrated in 11 tumors, whereas 8 tumors exhibited alteration in only 1 of the 2 alleles. PIK3CA mutations coexisted with monoallelic alterations of PTEN in 4 cases (2 mutations and 2 allelic imbalances), with biallelic PTEN inactivation in 1 case (mutation and promoter methylation), and 3 tumors showed PIK3CA mutations in association with wild-type PTEN. PIK3CA mutations did not correlate with microsatellite instability or mutations in CTNNB-1. However, PIK3CA and K-RAS mutations (8 cases) were mutually exclusive alterations. In summary, the results confirm that PIK3CA mutations are frequent in endometrial carcinoma and support the hypothesis that PIK3CA mutations may have an additive effect to PTEN monoallelic inactivation in endometrial carcinoma.     

Concerted promoter hypermethylation of hMLH1, p16INK4A,and E-cadherin in gastric carcinomas with microsatellite instability

In most sporadic gastric carcinomas, microsatellite instability (MSI) originates from inactivation of the hMLH1 gene by promoter hypermethylation. However, the methylation patterns of other genes and their consequences in high MSI (MSI-H) gastric carcinomas are not well characterized. To address the aberrant promoter methylation profiles of MSI-H gastric carcinomas, promoter methylation of six genes (hMLH1, p16(INK4A), E-cadherin, Rb, RASSF1A, and VHL) and CpG island methylator phenotype (CIMP) were explored in 36 MSI-H gastric carcinomas and the results were compared with those of 43 microsatellite-stable (MSS) gastric carcinomas. Frequent promoter hypermethylation was found in hMLH1, p16(INK4A), and E-cadherin and the frequency was significantly higher in MSI-H gastric carcinomas. Promoter hypermethylation of hMLH1, E-cadherin, and p16(INK4A) was found in 89%, 78%, and 33% of MSI-H gastric carcinomas and in 16%, 32%, and 11% of MSS carcinomas, respectively (p = 0.01). Selective absent or decreased expression of the gene product related to the hypermethylated promoter was found for hMLH1 and p16(INK4A) in MSI-H carcinoma, whereas the expression of E-cadherin was generally decreased both in the MSI-H and in the MSS carcinomas. MSI-H gastric carcinomas were also related to the high CIMP (CIMP-H, three or more of the five loci examined showing methylation). Twenty-two (61%) MSI-H gastric carcinomas were CIMP-H, compared with only seven (16%) MSS carcinomas (p = 0.001). These findings indicate that hMLH1 is one of the frequent methylation targets in CIMP-H gastric carcinomas and that inactivation of hMLH1 through promoter hypermethylation results in tumours following the MSI pathway.     

PIK3CA mutations in the kinase domain (exon 20) of uterine endometrial adenocarcinomas are associated with adverse prognostic parameters.

Mutations of the oncogene PIK3CA occur frequently in endometrial carcinomas, but their prognostic significance is unclear. To determine the clinicopathological and molecular implications of these mutations, PIK3CA status was investigated in 109 endometrial (102 endometrioid and 7 mixed) carcinomas and the results were compared with clinicopathological parameters associated with prognosis. Tumors were also investigated for microsatellite instability and PTEN, beta-catenin gene (CTNNB1), K-RAS, and B-RAF mutations. We found 35 PIK3CA somatic missense mutations in 32 (29%) endometrial carcinomas. Eighteen mutations occurred in exon 20 (kinase domain), and 17 in exon 9 (helical domain). Almost all mutated tumors were pure endometrioid adenocarcinomas. All tumors with PIK3CA mutations exhibited myometrial invasion (P=0.032). Lymphovascular invasion was found more frequently in mutated (28%) than nonmutated carcinomas (18%). Histological grade varied significantly according to the location of the PIK3CA mutations whether in exon 9 or exon 20 (P=0.033). The frequency of exon 9 mutations was higher in grade 1 carcinomas (57%) than in grade 2 (29%) or grade 3 (14%) tumors. Conversely, mutations in exon 20 were more common in grade 3 (60%) than in grade 2 (20%) or grade 1 (20%) carcinomas. None of the tumors confined to the endometrium (stage IA) had PIK3CA mutations. Furthermore, whereas 64% of adenocarcinomas with exon 9 mutations had invaded < or =(1/2) of the myometrial thickness (stage IB), 73% of tumors with exon 20 mutations had either deeper myometrial invasion (stage IC) or cervical involvement (stage II) (P=0.045). PIK3CA mutations coexisted with microsatellite instability and mutations in PTEN, CTNNB1, K-RAS, and B-RAF genes. These results favor that PIK3CA mutations are associated with myometrial invasion and, moreover, that tumors harboring PIK3CA mutations in exon 20 are frequently high-grade, deeply invasive endometrial carcinomas that tend to exhibit lymphovascular invasion.     

MSI-L gastric carcinomas share the hMLH1 methylation status of MSI-H carcinomas but not their clinicopathological profile

Sporadic gastric carcinomas (SGC) with microsatellite instability (MSI) exhibit mutations in target genes and display a particular clinicopathological profile. In SGC the MSI phenotype has been associated with hMLH1 promoter hypermethylation. Fifty-seven SGC, classified as high-frequency MSI (MSI-H), low-frequency MSI (MSI-L), and microsatellite stable (MSS), were analyzed for hMLH1 promoter methylation status and clinicopathological features. hMLH1 mutations and hMLH1 expression, as well as target gene mutations, were also evaluated. Our aims were to characterize the molecular and clinicopathological features of SGC, with and without hMLH1 promoter hypermethylation, and to compare the molecular and clinicopathological features of MSI-L, MSI-H, and MSS tumors in an attempt to clarify the place of MSI-L tumors in the mismatch repair (MMR) pathway. Hypermethylation of hMLH1 promoter occurred in 27 of 57 SGC (47.3%) and was significantly associated with MSI status, target gene mutations, and expansive pattern of growth of the tumors. Seventy-five percent of the MSI-H and 50% of MSI-L carcinomas showed hypermethylation (Met+) of hMLH1 in contrast to 0% in MSS carcinomas. No hMLH1 expression was observed in MSI-L/Met+ and MSI-H/Met+ cases. MSS and MSI-L tumors share the same clinicopathological profile regardless of the methylation status of the latter and are distinct from MSI-H tumors. We conclude that mutations in target genes, more than hypermethylation or absence of expression of hMLH1, are the link between MSI status and most of the clinicopathological features of SGC.     

High frequency of RASSF1A and RARb2 gene promoter methylation in morphologically normal endometrium adjacent to endometrioid adenocarcinoma

Aims: To identify a DNA methylation signature of endometrioid carcinoma of the endometrium (EEC) in the early stages of endometrial carcinogenesis. Methods and results: Archival biopsy specimens of 39 EECs, 14 cases of atypical hyperplasia (AH), 11 histologically normal endometrial tissues adjacent to EECs and 24 normal control endometrial samples were retrieved. The cases were tested by quantitative methylation‐specific polymerase chain reaction with primers hybridizing in the promoter regions of five genes frequently methylated in human cancer (RASSF1A, RARb2, P16, MGMT and GSTPi). Twenty‐nine of 39 (74%) EECs and 7/14 (50%) AHs were methylated for the RASSF1A gene, whereas 17/39 (44%) EECs and 6/14 (43%) AHs were positive for the methylation of the RARb2 gene. No significant results were obtained for the other genes (P16, MGMT and GSTPi). Interestingly, 4/11 (36%) and 6/11 (55%) histologically normal endometrial tissues adjacent to EEC showed, respectively, RASSF1A and RARb2 gene methylation. Furthermore, these 11 specimens were microsatellite stable and showed similar proliferative, cell cycle and apoptotic mean labelling indices as the normal endometrial control tissues. Conclusions: Promoter region methylation of RASSF1A and RARb2 genes is an early event in endometrial carcinogenesis.     

RASSF1A and NORE1A methylation and BRAFV600E mutations in thyroid tumors

We analyzed RASSF1A and NORE1A methylation and BRAF mutation in 89 thyroid tumors, 42 non-neoplastic thyroid tissues and three thyroid tumor cell lines using polymerase chain reaction (PCR), methylation-specific PCR, Western blotting and DNA sequencing in order to study thyroid tumor pathogenesis and progression. RASSF1A promoter methylation was present in all three thyroid cell lines and in 27/78 (35%) of benign and malignant thyroid tumors. We showed for the first time that there was generally good agreement between RASSF1A methylation status and RASSF1A protein expression. We also examined for the first time NORE1A promoter region methylation in thyroid cell lines and primary tumors and showed that two of three thyroid cell lines were methylated in the NORE1A promoter region, while all primary thyroid tumors analyzed (n=51) were unmethylated. BRAF mutation was present in 38% of papillary thyroid carcinomas (PTC), including 20% of PTC with a follicular variant pattern and 67% of the tall cell variant of PTC. Hyalinizing trabecular tumors (n=23), which had nuclear features similar to PTC, did not have BRAF mutations, indicating that the presence of BRAF mutations can help to separate these two tumor types. Phospho-MEK expression was increased in the NPA cell line, which had a BRAF mutation, supporting the importance of the BRAF pathway alterations in PTC pathogenesis. These results indicate that RASSF1A epigenetic changes are an early event in thyroid tumor pathogenesis and progression and that NORE1A methylation is uncommon in primary thyroid tumors. BRAF mutation occurs later in thyroid tumor progression and is restricted mainly to PTC and anaplastic thyroid carcinoma.     

hMLH1 Promoter Hypermethylation Is an Early Event in Human Endometrial Tumorigenesis

It has recently been suggested that silencing of the hMLH1 gene by promoter hypermethylation is the mechanism underlying the presence of the microsatellite instability (MSI) phenotype in sporadic colon and endometrial carcinomas. To determine whether hMLH1 promoter hypermethylation is a relatively early event in endometrial tumorigenesis we evaluated endometrial hyperplasia (EH) characterized as simple, complex, and atypical (the direct precursor of endometrial carcinoma) for hMLH1 aberrant methylation. In addition, we studied the hMLH1, hMSH2, hMSH3, and hMSH6 promoter methylation and MSI status of those endometrial carcinomas with synchronous hyperplasias and those without them. We found that 11 of 12 (91%) cases of endometrial carcinoma (EC) displaying MSI had hMLH1 promoter hypermethylation, whereas aberrant methylation of any of the other mismatch repair genes was not observed. All 15 cases of EC without MSI were unmethylated at hMLH1. Abnormal methylation of hMLH1 was also present in 8 of 116 (7%) cases of EH and was restricted primarily to the atypical endometrial hyperplasia (AEH) type with coexisting endometrial carcinoma. In this set, half of EH methylated at hMLH1 displayed MSI, whereas none of the unmethylated EH had MSI. Our data suggest that hypermethylation of hMLH1 can be an early event in the pathogenesis of EC, preceding the development of an apparent MSI phenotype in a subset of cases.     

Expression of multidrug resistance-associated protein in endometrial carcinomas: correlation with clinicopathology and prognosis

The objective of the study reported here was to investigate the expression of multidrug resistance-associated protein (MRP) in endometrial carcinomas and to evaluate the relationship between its expression and clinical data. Using immunohistochemistry, we examined MRP expression in 15 normal endometria, 10 cases of endometrial hyperplasia, and 64 cases of endometrial carcinoma. The normal endometrial glands were weakly immunopositive throughout the menstrual cycle. In addition, we found a progressive increase in the MRP expression of the endometrial hyperplasias. Of the 64 cases of endometrial carcinoma, 62 (97%) expressed MRP. Of these 62 cases, 34 (55%) showed strong immunostaining (>/=50%) and 28 (45%) showed weak immunostaining (<50%). In particular, the intensity of the immunostaining was very strong in 25 (71%) of the 35 grade 1 carcinomas. There was a significant difference in MRP expression between the grade 1 carcinomas and the more poorly differentiated carcinomas (grade 2 or grade 3) (P <.01), especially at stages 1a and 1b (P <.001). However, beyond stage 1c, there was no significant difference in MRP immunoreactivity between the histologic differentiations. Furthermore, beyond stage 1c, those patients with strongly MRP-positive carcinomas had a relatively poorer survival rate than those with weakly MRP-positive carcinomas (P <.05). We concluded that MRP immunoreactivity was already present in normal endometrium and showed a progressive increase from endometrial hyperplasia to well-differentiated carcinoma. Beyond stage 1c, strongly MRP-positive carcinoma indicated a poorer survival rate.     

肾细胞癌RASSF1A基因启动子区甲基化状况与表达水平研究

目的检测19例肾细胞癌患者癌组织及癌旁组织Ras相关区域家族蛋白1A（RASSFlA）基因启动子区甲基化情况并检测其mRNA表达水平，探索两者之间的联系。方法收集肾细胞癌患者癌组织及相应癌旁组织19份，分别提取其基因组DNA，以甲基化特异性PCR（Methylation special PCR，MSP）法检测RASSFlA基因启动子区甲基化情况。并以QPCR法检测了RASSFlA基因的mRNA表达水平。结果19例中有lO例肾细胞癌患者癌组织存在高甲基化，mRNA表达水平表达降低，二者之间存在显著负相关性（r=-0．8734，P〈0．01）。结论肾细胞癌中RASSFlA基因启动子区存在高甲基化，并抑制该基因的表达。     

Epigenetic instability is rare in fibrolamellar carcinomas but common in viral-associated hepatocellular carcinomas.

Fibrolamellar carcinomas have a unique predilection for younger individuals and arise in livers without recognizable liver disease. In contrast to typical hepatocellular carcinomas, fibrolamellar carcinomas show few chromosomal changes and lack mutation in key genes such as TP53 and CTNNB1. Epigenetic instability, manifesting as methylation of important tumor suppressor gene promoters, has not been investigated in fibrolamellar carcinomas. Thus, the methylation status of 11 tumor suppressor gene promoters was investigated using methylation-specific PCR: RASSF1, CDH1, CDKN2B, HPP1, CDKN2A, GSTP1, P16, RARA, FLJ13081, SOCS1, and TP53. Nine fibrolamellar carcinomas were studied including primary tumors (N=5) and metastatic deposits (N=4) along with control groups of typical hepatocellular carcinoma arising in livers with (N=21) and without cirrhosis (N=10). In fibrolamellar carcinomas, RASSF1A and CDH1 (e-cadherin) were the most commonly methylated genes with 80-100% of tumors methylated. However, overall fibrolamellar carcinomas showed low levels of methylation with no differences between fibrolamellar carcinomas and their paired normal livers. However, fibrolamellar carcinomas showed significantly less methylation than hepatocellular carcinomas that arose in the background of viral cirrhosis. Overall, methylation was most strongly linked to viral cirrhosis. In conclusion, fibrolamellar carcinoma shows low levels of methylation. In contrast, higher levels of promoter methylation are associated with hepatocellular carcinomas that arise in the setting of viral induced cirrhosis.     

Immunohistochemical expression of Retinoblastoma gene product in normal,hyperplastic and malignant endometrium. Correlation with p53 protein expression,c-erbB-2, hormone receptors' status and proliferative activity

Alterations of the retinoblastoma (Rb) gene have been described in several human neoplasms and recently, it has been suggested that these alterations may play a role in the development of endometrial carcinomas. Paraffin sections from 31 cases of normal endometrium (16 proliferative, 15 secretory), 35 hyperplastic lesions and 89 endometrial carcinomas were investigated immunohistochemically for Rb protein (pRb) expression. The results were compared with p53 and c-erbB-2 protein expression, estrogen (ER) and progesterone (PR) receptors' status and with clinicopathological prognostic factors. pRb was expressed in normal, hyperplastic and neoplastic epithelium. Proliferative endometrium showed more intense and extensive pRb staining than secretory endometrium. pRb reactivity was heterogeneous in the hyperplastic endometrial cells. Lack or focal (< 10% of endometrial cells) pRb immunostaining was noted in 56.2% and 27% of carcinomas, respectively. In the remaining cases (16.8%) pRb staining was heterogeneous or diffuse. The absence or presence of pRb expression was independent of grade and stage. In normal proliferative and secretory endometrium, pRb expression was correlated with PR (p = 0.006 and p = 0.001, respectively), PCNA (p = 0.04 and p = 0.01, respectively) and MIB1 (p = 0.02 and p<0.0001, respectively) expression. In hyperplasias, pRb was related to PR (p = 0.016) and MIB1 (p < 0.0001) expression. In carcinomas, a relationship of pRb expression with p53 (p = 0.0015), ER (p = 0.0002), PR (p = 0.0004) and PCNA (p = 0.013) status was detected. We suggest that the absence or presence of pRb expression does not seem to be associated with the progression of endometrioid carcinoma. In addition, pRb seems to be normally regulated in relation to the proliferative growth fraction of the tumours.     

CTNNB1 mutations and beta-catenin expression in endometrial carcinomas

Mutations in the beta-catenin gene (CTNNB 1) with abnormal nuclear accumulation of beta-catenin have recently been identified in endometrial carcinoma (EC). Their relationship with microsatellite instability (MI) is unclear. It has been suggested that matrix metalloproteinase-7 (MMP-7) and cyclin D1 (cD) genes are targets for beta-catenin activation. DNA from 73 patients with EC was obtained from tumor and normal tissue (59 endometrioid and 14 nonendometrioid). CTNNB 1 mutations in exon 3 were assessed by single-strand conformation polymorphism and DNA sequencing. The results were correlated with immunostaining for beta-catenin, MMP-7, and cD. Three (CA)n repeats and mononucleotide tracts BAT 25 and BAT 26 had been previously used for MI analysis. CTNNB1 mutations were identified in 15 ECs (20.5%), all of them endometrioid carcinomas (15 of 59; 25.4%). They occurred in 6 of 19 MI-positive ECs (31.5%) and in 9 of 54 MI-negative ECs (16.6%). Eleven of the 15 CTNNB 1-mutated ECs showed beta-catenin nuclear immunostaining (P <.05). MMP-7 expression (>50% cells) was observed in 23 ECs, with 7 of these showing CTNNB 1 mutations. Significant expression of cD (>50% cells) was detected in 8 ECs, with 5 of these exhibiting CTNNB 1 mutations (P <.05). The results confirm that beta-catenin plays a role in endometrial carcinogenesis, particularly in endometrioid carcinomas. The results also suggest that MMP-7 and particularly cD may be targets of beta-catenin activation in ECs.     

MLH1 promoter methylation and gene silencing is the primary cause of microsatellite instability in sporadic endometrial cancers

Defective DNA mismatch repair in human tumors leads to genome-wide instability of microsatellite repeats and a molecular phenotype referred to as microsatellite instability (MSI). MSI has been reported in a variety of cancers and is a consistent feature of tumors from patients with hereditary non-polyposis colorectal cancer. Approximately 20% of cancers of the uterine endometrium, the fifth most common cancer of women world-wide, exhibit MSI. Although the frequency of MSI is higher in endometrial cancers than in any other common malignancy, the genetic basis of MSI in these tumors has remained elusive. We investigated the role that methylation of the MLH1 DNA mismatch repair gene plays in the genesis of MSI in a large series of sporadic endometrial cancers. The MLH1 promoter was methylated in 41 of 53 (77%) MSI-positive cancers investigated. In MSI-negative tumors on the other hand, there was evidence for limited methylation in only one of 11 tumors studied. Immunohistochemical investigation of a subset of the tumors revealed that methylation of the MLH1 promoter in MSI-positive tumors was associated with loss of MLH1 expression. Immunohistochemistry proved that two MSI-positive tumors lacking MLH1 methylation failed to express the MSH2 mismatch repair gene. Both of these cancers came from women who had family and medical histories suggestive of inherited cancer susceptibility. These observations suggest that epigenetic changes in the MLH1 locus account for MSI in most cases of sporadic endometrial cancers and provide additional evidence that the MSH2 gene may contribute substantially to inherited forms of endometrial cancer.     

Impact of RASSF1A gene methylation on clinico-pathological features of tumor and non-tumor tissue of breast cancer

BackgroundBreast cancer is the most common malignancy in women caused by genetic and epigenetic changes. Promoter DNA methylation in tumor suppressor gene plays a major role in breast cancer. The study determined the association of promoter DNA methylation of RASSF1A gene with clinicopathological features in tumor and non-tumor tissue.Materials and methodsA cross sectional study was conducted in the Department of Pathology, Government Institute of Medical Sciences, Greater Noida and Molecular Pathology Laboratory, Department of Pathology, Jawaharlal Nehru Medical College, Datta Meghe Institute of Medical Sciences. Two sections, one from tumor and the other from non-tumor tissue, were obtained and processed for DNA extraction and bisulphite conversion. Methylation specific PCR was done and results of RASSF1A promoter methylation were statistically correlated with clinicopathological features.ResultsOf the 27 breast cancer tissue, 22 showed invasive ductal carcinoma, one showed invasive lobular carcinoma, another showed ductal carcinoma in situ and three cases showed malignant phyllodes tumor of breast. DNA promoter methylation was found in all the cases. 93% of tumor tissue samples and 67% of the non-tumor tissue samples were found to be aberrantly methylated. Tumor size and histological grade were found to be significantly (p-val <0.05) associated with the RASSF1A gene promoter methylation.ConclusionA significant association of higher tumor size and tumor histological grade with promoter methylation of RASSF1A gene exists suggestive of its being an important determinant of prognostic staging. This critical event in tumorigenesis may be of clinical utility in assessing breast cancer progression.Micro abstractThe study focuses on the RASSF1A gene promoter methylation and its impact on the clinicopathological features in Indian breast cancer patients highlighting the differences from other genetically different population. We found that RASFF1A gene methylation has significant impact on tumor size and tumor grade. The work carries high significance because it addresses the DNA methylation of tumor suppressor gene in relevance of breast cancer. It may also be the first such report on Indian patients with breast cancer.     

P16/MTS1 and pRB expression in endometrial carcinomas

 P16^MTS1/CDKN1 and the retinoblastoma protein Rb are both involved in negative regulation of G1/S progression in the mammalian cell cycle. Inactivation of one of these tumour suppressor genes is involved in many malignant tumours, and in some studies a negative correlation of p16 and Rb expression has been found. In order to study this interaction in endometrial carcinogenesis, we investigated 36 endometrial carcinomas, 11 cases of hyperplasia, 23 normal endometrial samples, and two uterine carcinoma cell lines by immunohistochemistry or RT-PCR. Rb was expressed in normal endometrial epithelium, hyperplasia, cell lines, and most carcinomas; negative immunostaining was only detected in 1 of 36 tumours. In contrast, p16 expression was weak in normal endometrium and increased in most cases of hyperplasia, but negative or minimally positive in 74% of the carcinomas and the Hec1B adenocarcinoma cell line, and there was no significant association with Rb immunostaining. Strikingly high p16 expression was found in foci of squamous metaplasia within hyperplastic or carcinomatous tissue. Deletion and mutation analysis of the p16 gene was performed in DNA from microdissected tumour samples and cell lines. No p16 deletion was found, and mutations were detected in only one tumour sample and Skut1B uterine mixed mesodermal tumour cells. Our data indicate that in spite of low or absent p16 expression, genetic alterations of the p16 and Rb tumour suppressor genes are rare in endometrial carcinogenesis. Received: 29 June 1998 / Accpeted: 31 July 1998     

Frameshift mutations in the bax gene are not involved in development of ovarian endometrioid carcinoma.

The purpose of this study was to determine whether mutations in the Bax gene play a role in the development of ovarian endometrioid carcinoma with a microsatellite instability phenotype. We analyzed a total of 60 tumor specimens, 49 ovarian endometrioid carcinomas and 11 concurrent endometrial endometrioid carcinomas from 49 patients. Fourteen ovarian endometrioid carcinomas and 6 endometrial endometrioid carcinomas showed a microsatellite instability-high phenotype. Tumor and normal-tissue specimens from eight patients with a microsatellite instability-high phenotype colorectal carcinoma were included in this study as controls. The presence or absence of a mutation in the poly (G) 8 tract of the Bax gene was determined by polymerase chain reaction followed by direct DNA sequence analysis. A 1-base pair deletion at the poly (G) 8 tract and no expression of Bax and Bcl-2 proteins were identified in one microsatellite instability-high endometrial endometrioid carcinoma. Immunohistochemical staining for Bax and Bcl-2 proteins was negative on the tumor specimen that had this 1-base pair deletion. No mutations were found in the synchronous microsatellite instability-high ovarian endometrioid carcinoma from the same patient. In contrast, four (50%) of the eight microsatellite instability-high sporadic colorectal carcinomas had a mutation in the poly (G) 8 tract. Although Bax plays an important role in carcinogenesis of the colorectum with microsatellite instability-high phenotype, Bax may not play a direct role in the genesis of ovarian endometrioid carcinoma, regardless of microsatellite instability status.     

Hypermethylation of the hMLH1 promoter with absent hMLH1 expression in medullary-type poorly differentiated colorectal adenocarcinoma in the elderly.

To clarify the significance of hMLH1 promoter hypermethylation in the development of medullary-type poorly differentiated colorectal adenocarcinoma, we studied the status of promoter methylation and hMLH1 expression in 23 medullary-type and 12 pleomorphic-type carcinomas, as well as the pathology and microsatellite status. In medullary-type carcinomas, the percentages of cases with promoter methylation (83%) and an absence of hMLH1 expression (91%) were significantly higher than in pleomorphic-type carcinomas (14 and 17%), respectively. The rate of microsatellite instability in the medullary type was significantly higher than that of the pleomorphic type (87 vs 40%, P<0.01). Compared with pleomorphic-type carcinomas, medullary-type carcinomas were significantly associated with hMLH1 promoter methylation, absent expression of hMLH1 protein, microsatellite instability, as well as a proximal location, a Crohn's-like lymphoid reaction, a low incidence of lymph node metastasis, and a favorable outcome. Medullary-type carcinomas accumulated with advancing age, especially in the female. These results indicated that hMLH1 hypermethylation, concurrent with a lack of its protein expression, may play an important role in the development of medullary-type poorly differentiated colorectal adenocarcinomas in the elderly.