KRAS mutation and microsatellite instability in endometrial adenocarcinomas showing MELF-type myometrial invasion.

BACKGROUND: Some uterine endometrioid adenocarcinomas exhibit a distinctive morphological phenotype characterised by the formation of microcystic, elongated and fragmented (MELF) glands. Immunohistochemical studies have suggested that MELF-type changes represent an epithelial-mesenchymal transition which has been associated with KRAS activation in various tumours. AIMS: To investigate the molecular characteristics of endometrial tumours showing MELF, with particular reference to the frequencies of KRAS and BRAF mutations and of microsatellite instability (MSI). METHODS: MSI, and KRAS and BRAF mutation status, were assessed in 33 low-grade endometrial adenocarcinomas showing MELF features and the results compared with 33 control cases exhibiting a 'conventional' pattern of myometrial invasion. Standard histological parameters were also reviewed. RESULTS: Tumours with a MELF pattern of myometrial invasion showed more frequent vascular invasion and focal mucinous differentiation. KRAS mutations were more frequent in MELF positive than MELF negative tumours (45% vs 30%), but this difference was not statistically significant. BRAF mutations were not identified in any of the cases. MSI was identified in 20% of cases overall but did not correlate with the MELF phenotype. CONCLUSIONS: Mutations in KRAS and BRAF genes are not directly implicated in the development of a MELF pattern of invasion in endometrial carcinoma. However, RAS-associated signalling pathways could be activated through other genetic or epigenetic mechanisms. The characterisation of such alterations may become increasingly important as novel therapies are developed that target mediators involved in tumour invasion.

DNA hypermethylation in the normal colonic mucosa of patients with colorectal cancer.

The CpG-island methylator phenotype (CIMP+) in colorectal cancer (CRC) is characterised by frequent hypermethylation of promoter regions in tumour suppressor genes. Low level methylation of some CpG islands is also seen in the normal colonic mucosa and increases with age; however, it is still unclear what other factors regulate this phenomenon. The first aim of our study was to determine whether the level of promoter methylation is elevated in the normal colonic mucosa of patients with CIMP+ tumours. The second aim was to investigate whether common, functional polymorphisms in genes involved in methyl group metabolism are associated with the level of methylation in this tissue. CpG islands within the ERalpha, MYOD, P16(INK4A), MLH1, APC, P14(ARF), DAPK and TIMP3 genes were quantitatively evaluated for methylation in normal colonic mucosa from a large series of CRC patients using the MethyLight assay. Genotyping was carried out for polymorphisms in the MTHFR, TS, MS, MTHFD1 and DNMT3b genes. Methylation of ERalpha and MYOD in normal colonic mucosa increased with age and was higher in female subjects. Methylation of P16(INK4A), MLH1, TIMP3 and DAPK in normal mucosa occurred at a lower level than ERalpha and MYOD but also increased with age and was significantly higher in patients with CIMP+ tumours. The DNMT3b C46359T polymorphism was associated with significantly less methylation of MYOD and MLH1 and with trends for lower methylation in each of the other CpG islands examined. Our results demonstrate that age, gender and genetic factors can influence the methylation level of CpG islands in gene promoter regions of normal colonic mucosa. Further work is required to determine whether such methylation is associated with the development of CIMP+ CRC.

The -174 G/C gene polymorphism in interleukin-6 is associated with an aggressive breast cancer phenotype.

Serum and tissue levels of interleukin-6 (IL-6) have been implicated in the biological phenotype of breast carcinoma. A common G/C polymorphism at position -174 of the IL-6 promoter can influence the expression level of this gene. We therefore investigated for associations between this polymorphism and various phenotypic features in a series of 256 breast cancers. Individuals who were homozygous for the C allele (n=55) were more likely to have higher-grade tumours (P=0.039) with ductal histology (P=0.030) compared to those harbouring at least one wild-type G allele (n=201). Homozygosity for the C allele was also associated with significantly worse overall survival (P=0.031). We conclude that the -174 C allele of IL-6 is associated with a more aggressive breast cancer phenotype.

Characterisation of colorectal cancers showing hypermethylation at multiple CpG islands.

BACKGROUND AND AIMS: A subgroup of colorectal cancers (CRC) referred to as the CpG island methylator phenotype (CIMP+) shows simultaneous methylation of multiple CpG islands. The clinicopathological and molecular characteristics of this phenotype remain uncertain however. METHODS: We analysed methylation of CpG islands in the p16 and MDR1 genes and MINT-2 clone in 275 stage II/III CRCs. RESULTS: Concurrent methylation of two or more CpG islands was observed in 32% of cases and was considered to represent CIMP+. These were often poorly differentiated, had less TP53 mutations, and originated frequently in the proximal or higher stage CRC compared with CIMP- tumours (p<0.05 for each). CIMP+ had no prognostic significance in stage II or stage III CRC treated by surgery alone. hMLH1 methylated tumours comprised the majority (81%) of cases with microsatellite instability, were frequently observed in older female patients, were often poorly differentiated or CIMP+, and contained wild-type K-ras (p<0.05 for each). Females who were heterozygous or homozygous for the C677T MTHFR polymorphism were at increased risk of developing CIMP+ CRC (odds ratio 2.17, 95% confidence interval 1.03-4.57; p=0.037). CONCLUSIONS: These observations made in a relatively large unselected series of CRC support the notion that CIMP+ characterises a subgroup of tumours with distinctive phenotypic features.

A polymorphism in the enhancer region of the thymidylate synthase promoter influences the survival of colorectal cancer patients treated with 5-fluorouracil.

High levels of thymidylate synthase (TS) expression have been associated with poor survival of colorectal cancer (CRC) patients to 5-fluorouracil (5-FU)-based chemotherapy. Recent evidence suggests that a polymorphism within the enhancer region of the TS gene promoter can influence TS expression, with the triple repeat homozygote (3R/3R) being associated with significantly higher tumour TS levels than either the double repeat homozygote (2R/2R) or heterozygotes (2R/3R). In the present study we investigated whether TS genotype was associated with the degree of survival benefit from chemotherapy in 221 Dukes' C stage CRC patients. Patients with the 3R/3R polymorphism (n = 58, 26%) showed no significant long-term survival benefit from chemotherapy (RR = 0.62, 95% CI: 0.30-1.25, P = 0.18), whereas those with the 2R/2R or 2R/3R genotype (n = 163, 74%) showed significant gains in survival from this treatment (RR = 0.52, 95% CI: 0.52-0.82, P = 0.005). These results demonstrate that a polymorphism within the TS gene, probably through its effect on TS expression levels, can influence the survival benefit obtained by CRC patients from 5-FU-based chemotherapy.

P53 alteration and microsatellite instability have predictive value for survival benefit from chemotherapy in stage III colorectal carcinoma.

PURPOSE: We recently presented evidence for tumor site and gender-specificity in the survival benefit from adjuvant chemotherapy in Stage III colorectal cancer (CRC). In the current study, we examined whether p53 alteration or the microsatellite instability (MSI) phenotype provide additional predictive information in CRC patients. EXPERIMENTAL DESIGN: A retrospective series of 891 Stage III CRC patients with negative surgical margins was investigated. Thirty percent (270 of 891) received postoperative adjuvant chemotherapy with curative intent and comprising of 5-fluorouracil/levamisole. Adjuvant treatment and nontreatment patient groups were well matched for tumor site, grade, p53 alterations, and MSI. Surgical tumor specimens were investigated for p53 overexpression using immunohistochemistry and for p53 mutation and MSI using single-strand conformation polymorphism analysis. The predictive value of these markers was evaluated by comparing the survival of adjuvant-treated and nonadjuvant treated patients. RESULTS: A strong inverse correlation was observed between p53 alteration and MSI (P < 0.0001). In univariate analysis, the factors of sex, site, p53 alteration, and MSI were each strong predictors of a survival benefit from chemotherapy. Multivariate analysis revealed that chemotherapy provided maximal survival benefit for female patients (P = 0.005) and for patients whose tumors contained normal p53 (P = 0.041). Males whose tumors contained a p53 alteration and were negative for MSI appeared not to benefit from chemotherapy. CONCLUSIONS: Our findings suggest that p53 alteration and MSI could be clinically useful molecular predictive markers for the identification of CRC patients who might benefit from 5-fluorouracil-based chemotherapy.

Prognostic value of TP53 gene mutation in adjuvant treated breast cancer patients.

We investigated the prognostic significance of mutation to the TP53 tumor suppressor gene in a series of 908 breast cancer patients treated with or without adjuvant therapies. The frequency of TP53 mutation detected by single strand conformation polymorphism (SSCP) was 19.4% (176/908) in the overall tumor series. In multivariate analysis, TP53 mutation was independently associated with worse survival in the overall (HR = 2.1, 95% CI [1.5-3.1], P<0.0001), non-adjuvant treated (HR=2.2, 95% CI [1.2-4.2], P=0.017) and adjuvant treated (HR= 2.0, 95% CI [1.3-3.1], P = 0.0009) patients.

Can p53 alterations be used to predict tumour response to pre-operative chemo-radiotherapy in locally advanced rectal cancer?

PURPOSE: To examine whether p53 tumour suppressor gene alterations can be used to predict tumour response to pre-operative chemo-radiation in locally advanced rectal cancer in terms of reduction in tumour size and local failure. METHODS: p53 alterations were studied in pre-treatment biopsy specimens of rectal carcinomas from 48 patients by immunohistochemistry (IHC) and polymerase chain reaction/single strand conformation polymorphism (PCR-SSCP) gene mutation analysis. Pre-operative pelvic radiotherapy was delivered with four fields, 45 Gy to the ICRU point in 25 fractions over 5 weeks. A radio-sensitising dose of 5-fluorouracil (500 mg/m(2)) was delivered concurrently for 6 days of the 5-week schedule (days 1, 2, 3 and days 22, 23 and 24). Total meso-rectal excision was planned 4 to 6 weeks from completion of pre-operative treatment. Response to therapy was assessed by macroscopic measurement of the surgical specimen by a pathologist who was unaware of the pre-treatment tumour size or of the p53 status. RESULTS: IHC evidence of p53 protein accumulation was found in 40% of tumours, p53 gene mutation in 35% and p53 alteration (either or both changes) in 46%. The average reduction in tumour size was 53% in the group with 'wild-type' p53 (IHC-/SSCP-) and 63% in the group with altered p53 (either IHC+ or SSCP+; P=0.18). No significant differences in tumour size reduction or local failure were observed in the groups with p53 overexpression or p53 mutation compared with normal. CONCLUSIONS: p53 alteration detected by IHC or SSCP analysis is not a clinically useful predictor of local response to pre-operative adjuvant therapy in advanced rectal carcinoma.

Association of tumour site and sex with survival benefit from adjuvant chemotherapy in colorectal cancer.

BACKGROUND: Adjuvant chemotherapy can improve 5-year survival in Dukes' C colorectal carcinoma. Improved selection of patients who will respond to adjuvant treatments is required. We investigated whether site of tumour origin, sex, and presence of microsatellite instability (MSI) phenotype were associated with a survival benefit from adjuvant chemotherapy. METHODS: We analysed data for 656 consecutive patients with Dukes' C colorectal carcinoma, with median follow-up of 54 months (range 7-104) and mean age 66.7 years (SD 12.9). We screened tumour samples by PCR for deletions in the BAT-26 mononucleotide repeat to establish MSI status. Details of chemotherapy and survival were obtained by review of hospital and health-department records. Adjuvant chemotherapy (fluorouracil and levamisole) was given with curative intent to 272 (42%) patients. FINDINGS: Striking survival benefits were seen for patients who had right-sided tumours and who received adjuvant chemotherapy compared with those who did not (48 vs 27% alive at end of study [95% CI 0.25-0.56], p<0.0001), for women (53 vs 33% [0.25-0.56], p<0.0001), and for patients with MSI tumours (90 vs 35% [0.01-0.53], p=0.0007). MSI-positive tumours were slightly more frequent in women than in men (10 vs 7%). Right-sided tumours were more frequently MSI positive than left-sided tumours (20 vs 1%). Men with right-sided tumours benefited from chemotherapy (37 vs 12% [0.24-0.69], p=0.0007) but men with left-sided tumours did not. INTERPRETATION: The survival benefits seen in patients treated with adjuvant chemotherapy suggest that data from previous trials of adjuvant chemotherapy should be reassessed and the predictive value of MSI status confirmed. Validation of our results will allow better selection of patients for chemotherapy.

Routine analysis of p53 mutation in clinical breast tumor specimens using fluorescence-based polymerase chain reaction and single strand conformation polymorphism.

Improved prognostic and predictive markers in breast cancer management would help considerably in therapeutic decision making, particularly in patients with early-stage breast cancer. Tumor factors currently used for prognostication and management decisions are tumor size, histologic type and grade, axillary lymph node status, and estrogen receptor content. The discovery of various somatic genetic alterations in breast cancer has raised the possibility that these may provide additional and independent prognostic and predictive information. Alterations of the p53 tumor suppressor gene in particular have received the most attention as potential prognostic and predictive factors. In multivariate analysis, p53 gene mutation is consistently associated with a two- to threefold increased risk of relapse and death from breast cancer. One of the major reasons preventing the introduction of p53 mutation as a routine marker to assist in therapeutic decision making is the lack of a simple, reproducible, and inexpensive assay. In the present study the authors optimized a polymerase chain reaction-based mutation screening method, fluorescence-single strand conformation polymorphism (F-SSCP), that allows p53 status to be assessed accurately and reproducibly in routinely handled, formalin-fixed and paraffin-embedded tumor specimens. The frequency of p53 mutation observed using F-SSCP in a consecutive series of invasive ductal breast carcinomas was 17% (28/164). The authors propose that the prognostic and predictive values of p53 mutation in breast cancer should be further evaluated in prospective, randomized studies using this standardized technique.

Routine detection of the replication error phenotype in clinical tumor specimens using fluorescence-SSCP.

Almost all tumors from patients with hereditary non-polyposis colon carcinoma and approximately 10%-15% of sporadic colon and gastric carcinomas contain widespread deletions within mono- and dinucleotide repeat sequences in their DNA. This is referred to as the replication error (RER+) phenotype and, in the case of colon carcinoma, is often associated with an improved tumor prognosis and possibly also with response to chemotherapy. The RER+ status of tumors is usually determined by examining several dinucleotide and mononucleotide repeats for size variations when compared with the matching normal DNA. Alternately, the identification of deletions within BAT-26, a quasi-monomorphic polyadenine tract within the hMSH2 gene, has been shown to establish the RER+ status of tumors with greater than 99% accuracy and without the need for normal DNA. Here, we use fluorescent PCR in combination with single strand conformation polymorphism analysis to detect deletions in BAT-26. This technique provides a sensitive, rapid, reproducible and inexpensive assay suitable for the routine identification of RER+ status in clinical tumor specimens.

P53 alterations have no prognostic or predictive significance in Dukes' C rectal carcinomas.

We investigated the prognostic significance of p53 alterations in a consecutive series of 122 Dukes' C rectal carcinomas with a median patient follow-up period of 56 months. One third of patients were treated with post-operative adjuvant chemotherapy. Overexpression of p53 protein was observed in 42% (50/118) of cases using immunohistochemical analysis and mutation of the p53 gene in 38% (47/122) using single strand conformation polymorphism technique. Neither p53 overexpression nor mutation were associated with significantly worse patient survival in the overall group or in the subgroup of 35 patients who received standard post-operative chemotherapy with 5-fluorouracil and levamisole. Our results do not support the use of p53 alteration as a clinically useful prognostic marker for the overall survival of rectal cancer patients or for predicting their response to chemotherapy.

p53 protein overexpression is a prognostic indicator of poor survival in stage I endometrial carcinoma.

The prognostic value of p53 protein overexpression was investigated in a large series of early stage endometrial carcinomas with long follow-up (n=179, median follow-up 147 months). P53 overexpression was detected in 10 cases (5.6%). At the end of the study period, 30% (3/10) of patients with p53 protein overexpression had died of their disease compared to 6.5% (11/169) of those without overexpression. Multivariate analysis revealed that only myometrial invasion (RR 2. 1; 95% CI=1.2-3.6; P=0.001) and p53 overexpression (RR 9.5; 95% CI=2. 5-36.8; P=0.007) were independent predictors of survival. These results suggest that immunohistochemical evaluation of p53 protein overexpression provides strong prognostic information for the outcome of endometrial carcinoma patients with early stage disease.

Analysis of p53 gene mutation by polymerase chain reaction-single strand conformation polymorphism provides independent prognostic information in node-negative breast cancer.

Controversy continues regarding the prognostic utility of detection of p53 gene abnormalities in node-negative breast cancer. To resolve this, we used a rapid and nonisotopic PCR-single strand conformation polymorphism method to screen for mutations in exons 4-8 of the p53 gene in primary tumors from 422 node-negative breast cancer patients. The prevalence of p53 mutation in the exons tested was 18%. p53 mutation was significantly associated with several markers of poor prognosis including larger tumor size, high tumor grade, low hormone receptor content, increased expression of MIB-1 (Ki-67), amplification of the HER-2/neu oncogene, and accumulation of the p53 protein. After a median duration follow-up period of 74 months, the parameters of tumor diameter > or =20 mm, HER-2/neu oncogene amplification, and p53 mutation were found to be associated with a statistically significant shortened duration of disease-free and overall survival, but not the parameters of tumor grade, hormone receptor levels, or p53 expression. The poor prognosis associated with p53 mutation was observed primarily in patients with a tumor diameter of > or =20 mm. In multivariate analysis, p53 mutation was a risk factor for increased risk of recurrence and death from breast cancer independent of tumor size, hormone receptor levels, HER-2/neu amplification, and MIB-1 expression. We conclude that a relatively simple and rapid single strand conformation polymorphism method of determining p53 mutation status in node-negative breast cancers can provide independent prognostic information.

p53 alterations are associated with improved prognosis in distal colonic carcinomas.

Alterations of the p53 gene and the p53 protein are common in a wide spectrum of human malignancies. In several tumor types, p53 gene mutation and/or p53 protein overexpression correlate with a more clinically aggressive phenotype as judged by worse patient survival. This has not been clearly demonstrated to be the case in colorectal cancer. Herein, we report results of the prognostic significance of p53 protein accumulation and gene mutation in a large series of colorectal cancers (n = 541) with long patient follow-up (mean, 87 months). The large majority of patients (95%) received no postoperative systemic adjuvant therapy. The incidence of p53 accumulation detected by immunohistochemistry with the monoclonal antibody DO-7 was 30%, whereas the incidence of p53 gene mutation in exons 5-8 detected using PCR-single strand conformation polymorphism was 36%. Accumulation of p53 protein was associated with improved patient survival independent of tumor stage or grade (hazard ratio, 0.66; 95% confidence interval, 0.47-0.93; P = 0.017). A marked difference was observed depending on the location of the tumor: tumors originating in the distal colon showed a strong association between the presence of p53 accumulation and improved patient survival (P = 0.003), but this was not the case for those located in the proximal colon. Dukes' stage C tumors, but not stage B, also showed an association between p53 accumulation and better outcome (P = 0.013). Mutation of the p53 gene was associated with a trend toward improved survival, particularly in the distal tumors. Our results demonstrate that in some tumor types, the presence of p53 abnormalities can correlate with better prognosis.

Concordance between p53 protein overexpression and gene mutation in a large series of common human carcinomas.

Immunohistochemical (IHC) detection of p53 protein was compared with the presence of p53 gene mutation in many colorectal (n = 100), breast (n = 92), endometrial (n = 122), and gastric (n = 116) carcinomas. Two commercially available antibodies, DO7 and CM1, were used for IHC analysis of paraffin-embedded tissue sections. Screening for gene mutations in frozen and paraffin-embedded tumor samples was carried out using polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP). The frequency of nuclear staining with DO7 or CM1 for each tumor type, respectively, was colorectal (36%, 23%); breast (15%, 19%); endometrial (21%, 33%); and gastric (23%,-). Overall correlation between the two antibodies for nuclear staining was 90% for the 314 tumors analyzed. Cytoplasmic staining was observed with DO7 in 7% of breast and 5% of gastric carcinomas and with CM1 in 17% of breast and 54% of endometrial carcinomas. p53 gene mutation was found in 39% of colorectal, 28% of breast, 13% of endometrial, and 25% of gastric cancers. The concordance between p53 nuclear overexpression and gene mutation (both positive or both negative) was 68% for colorectal, 79% for breast, 76% for endometrial, and 73% for gastric carcinomas. This study provides further evidence that IHC detection of p53 protein accumulation does not always indicate the presence of a gene mutation and vice versa. Discordant results were observed in approximately 20% to 30% of the tumors studied, highlighting the need for careful characterization of both p53 gene and protein alterations when assessing the relationship between p53 status and tumor behavior.

p53 accumulation and mutation are prognostic indicators of poor survival in human gastric carcinoma.

The aim of our study was to examine the prognostic significance of p53 protein accumulation and gene mutation in a series of 116 gastric carcinomas from a low incidence population. Formalin-fixed, paraffin-embedded tumour sections were used to investigate p53 protein accumulation by immunostaining with monoclonal antibody (MAb) DO-7 and p53 gene mutation by single-strand conformation polymorphism analysis of exons 5-8. Nuclear p53 accumulation was detected in 23% of tumours and mutation in 28%. Concordance between the 2 alterations was observed in 73% of cases. p53 protein accumulation was more frequent in tumours with lymph node metastasis, while p53 mutations were more frequent in tumours from older patients. The histopathological parameters of depth of invasion, grade and histological type showed no significant associations with either p53 alteration. In univariate analysis, both alterations were associated with significantly shortened patient survival. The 5-year survival rate for patients with a p53 mutation was 9% compared to 42% for those without a mutation. In multivariate analysis adjusted for the other histopathological parameters, p53 gene mutation but not immunohistochemically-detected p53 protein accumulation was an independent prognostic indicator of poor survival in gastric carcinoma.

Epidermal growth factor in human and bovine milk.

The concentration of epidermal growth factor in human and bovine milk was measured by radioreceptor assay. Both human placental plasma membranes and a human epidermoid carcinoma cell were used as the epidermal growth factor receptor source in the assay. The use of placental plasma membrane in the radioreceptor assay gave erroneous results for bovine milk and overestimated the concentration of epidermal growth factor in human milk. Intact cells appear to provide a more accurate measure of the concentration of epidermal growth factor in milk samples. Using A431 cells, we found very low concentrations of epidermal growth factor in bovine milk (less than 2 ng/ml) compared to human milk (30-40 ng/ml). No epidermal growth factor activity was found in several cows' milk-based infant formulas. These results highlight the caution which must be taken when measuring trace substances such as polypeptide growth factors in complex samples such as milk.

Characterization of 3-methylcholanthrene effects on the rat glucocorticoid receptor in vivo.

The effects of 3-methylcholanthrene and phenobarbital treatment on the adult rat hepatic cytosolic glucocorticoid (GRc) receptor were investigated. Analyses of sucrose gradient profiles and equilibrium binding data of [3H]dexamethasone bound to the GRc revealed that administration of 3-methylcholanthrene (20-40 mg/kg daily i.p. for 2 days) to adult female Fischer F344 rats led to a significant decrease in the maximal binding capacity of the 5-7S GRc [Bmax = 209 +/- 3 (SE) fmol/mg of protein] compared to the vehicle-treated controls (Bmax = 277 +/- 13 fmol/mg) but had no significant influence on the affinity of the GRc (Kd = 0.9 +/- 0.1 nM). This response was not dependent upon the sex or rat strain (female F344 versus Sprague-Dawley). Phenobarbital treatment (80 mg/kg daily i.p. for 4 days) decreased Bmax and Kd values compared to the vehicle treated controls (P less than 0.05). 3-Methylcholanthrene treatment did not significantly alter the equilibrium parameters of [3H]methyltrienolone bound to the hepatic androgen receptor indicating that the effect was specific to the hepatic GRc. Our data suggest that carcinogens and tumor promoters cause a functional decrease of the cytosolic glucocorticoid receptor in vivo.