Comparison of faecal M2-PK and FIT in a population-based bowel cancer screening cohort

BACKGROUND

Screening for colorectal cancer improves outcomes and is cost effective. Stool-based tests have the highest participation rates in screening programmes. Their efficacy is limited by the relatively low sensitivity and specificity compared with colonoscopy. Stool levels of M2-PK, a dimeric form of the enzyme pyruvate kinase, correlate with colorectal cancer and neoplasia. A combination of stool markers may enhance screening performance; however, it remains to be determined whether an additional test would affect participation rates negatively.

AIMS

The aim of this study was to assess the performance of faecal M2-PK and faecal immunochemical test (FIT) and their combined effect in a screening programme.

MATERIALS AND METHODS

Within round 2 of our biennial FIT-based pilot, all invitations additionally included an M2-PK kit. A FIT greater than 100 ngHb/ml and/or an M2-PK greater than 4 U/ml were considered positive. FIT-positive or M2-PK-positive patients were offered a colonoscopy.

RESULTS

In all, 1800 combined M2-PK and FIT invites were sent out, and 879 (49%) samples were analysed. Overall positivity was 27% (n=245). Only 23 (2.6%) patients were positive for both tests. In all, 186 (88%) screening colonoscopies were performed. The adenoma detection rate for M2-PK-positive patients (n=157) was significant at 25% (n=40), and 3% (n=5) had advanced lesions. In FIT-positive patients (n=51), the adenoma detection rate was 29% (n=15), with significantly more, 21% (n=11), having advanced lesions (P<0.001, confidence interval 0.117-0.156). Had FIT only been tested, 70% (n=35) fewer patients would have had polyps removed.

CONCLUSION

The addition of M2-PK in a biennial bowel screening programme is acceptable to patients, feasible and detects additional adenomas, potentially at an earlier stage.

Role of D2 dopamine receptor in adrenal cortical cell proliferation and aldosterone-producing adenoma tumorigenesis

Aldosterone-producing adenoma (APA) and bilateral adrenal hyperplasia are the two characteristic types of primary aldosteronism. Dysregulation of adrenal cortical cell proliferation contributes to both diseases. We previously demonstrated that APA expressed less dopamine D2 receptor than the respective non-tumor tissue and might contribute to the overproduction of aldosterone. As activation of D2 receptor inhibits the proliferation of various cells, downregulation of D2 receptor in APA may play a role in the tumorigenesis of APA. In this study, we demonstrate that D2 receptor plays a role in angiotensin II (AII)-stimulated adrenal cortical cell proliferation. The D2 receptor agonist, bromocriptine, inhibited AII-stimulated cell proliferation in primary cultures of the normal human adrenal cortex and APA through attenuating AII-induced phosphorylation of PK-stimulated cyclin D1 protein expression and cell proliferation. D2 receptor also inhibited AII-induced ERK1/2 phosphorylation. Our results demonstrate that, in addition to inhibiting aldosterone synthesis/production, D2 receptor exerts an anti-proliferative effect in adrenal cortical and APA cells by attenuating PKCμ and ERK phosphorylation. The lower level of expression of D2 receptor in APA may augment cell proliferation and plays a crucial role in the tumorigenesis of APA. Our novel finding suggests a new therapeutic target for primary aldosteronism.

Constitutive activation of PKA catalytic subunit in adrenal Cushing's syndrome

BACKGROUND

Corticotropin-independent Cushing's syndrome is caused by tumors or hyperplasia of the adrenal cortex. The molecular pathogenesis of cortisol-producing adrenal adenomas is not well understood.

METHODS

We performed exome sequencing of tumor-tissue specimens from 10 patients with cortisol-producing adrenal adenomas and evaluated recurrent mutations in candidate genes in an additional 171 patients with adrenocortical tumors. We also performed genomewide copy-number analysis in 35 patients with cortisol-secreting bilateral adrenal hyperplasias. We studied the effects of these genetic defects both clinically and in vitro.

RESULTS

Exome sequencing revealed somatic mutations in PRKACA, which encodes the catalytic subunit of cyclic AMP-dependent protein kinase (protein kinase A [PKA]), in 8 of 10 adenomas (c.617A→C in 7 and c.595_596insCAC in 1). Overall, PRKACA somatic mutations were identified in 22 of 59 unilateral adenomas (37%) from patients with overt Cushing's syndrome; these mutations were not detectable in 40 patients with subclinical hypercortisolism or in 82 patients with other adrenal tumors. Among 35 patients with cortisol-producing hyperplasias, 5 (including 2 first-degree relatives) carried a germline copy-number gain (duplication) of the genomic region on chromosome 19 that includes PRKACA. In vitro studies showed impaired inhibition of both PKA catalytic subunit mutants by the PKA regulatory subunit, whereas cells from patients with germline chromosomal gains showed increased protein levels of the PKA catalytic subunit; in both instances, basal PKA activity was increased.

CONCLUSIONS

Genetic alterations of the catalytic subunit of PKA were found to be associated with human disease. Germline duplications of this gene resulted in bilateral adrenal hyperplasias, whereas somatic PRKACA mutations resulted in unilateral cortisol-producing adrenal adenomas. (Funded by the European Commission Seventh Framework Program and others.).

Disparities of conjugating protective enzyme activities in the colon of patients with adenomas and carcinomas

AIM: To investigate the metabolic enzymatic capacity of the colon mucosa to detoxify noxious carcinogenic compounds.

METHODS: We investigated the activity of 2 conjugating enzymes-the microsomal uridine glucuronosyltransferase (UGT) and the cytosomal glutathione S-transferase (GST) in the uninvolved mucosa of the colon transversum and sigmoideum in patients with adenomatous polyps and colorectal cancer. Biopsies were taken from the mucosa during colonoscopies which were done for clinical (diagnostic) reasons. After storage, the biopsy material was homogenized and after differential centrifugation the enzyme assays were performed with 4-nitrophenol (UGT) and 1-chloro 2,4-dinitrobenzene (GST) as substrates.

RESULTS: About 48 patients were included of which 28 had adenomas and 20 had colorectal carcinomas confirmed by histopathology. Enzyme activities were expressed as nmol/mg per minute protein for the GST and as pmol/mg per minute protein for the UGT. Analysis of variance (F-test) indicated that both enzymes were more widely distributed in adenoma than in cancer patients. The means ± SD were smaller for cancer patients: GST for adenomas 268 ± 152 vs 241 ± 69 for carcinomas and UGT for adenomas 197 ± 200 vs 150 ± 86 for carcinomas.

CONCLUSION: Compared to patients with adenomatous colon polyps those with colorectal carcinoma exhibited a lower capacity of detoxifying enzyme metabolism and their activities clustered over a smaller range.

Deletion of glutathione peroxidase-2 inhibits azoxymethane-induced colon cancer development

The selenoprotein glutathione peroxidase-2 (GPx2) appears to have a dual role in carcinogenesis. While it protected mice from colon cancer in a model of inflammation-triggered carcinogenesis (azoxymethane and dextran sodium sulfate treatment), it promoted growth of xenografted tumor cells. Therefore, we analyzed the effect of GPx2 in a mouse model mimicking sporadic colorectal cancer (azoxymethane-treatment only). GPx2-knockout (KO) and wild-type (WT) mice were adjusted to an either marginally deficient (−Se), adequate (+Se), or supranutritional (++Se) selenium status and were treated six times with azoxymethane (AOM) to induce tumor development. In the −Se and ++Se groups, the number of tumors was significantly lower in GPx2-KO than in respective WT mice. On the +Se diet, the number of dysplastic crypts was reduced in GPx2-KO mice. This may be explained by more basal and AOM-induced apoptotic cell death in GPx2-KO mice that eliminates damaged or pre-malignant epithelial cells. In WT dysplastic crypts GPx2 was up-regulated in comparison to normal crypts which might be an attempt to suppress apoptosis. In contrast, in the +Se groups tumor numbers were similar in both genotypes but tumor size was larger in GPx2-KO mice. The latter was associated with an inflammatory and tumor-promoting environment as obvious from infiltrated inflammatory cells in the intestinal mucosa of GPx2-KO mice even without any treatment and characterized as low-grade inflammation. In WT mice the number of tumors tended to be lowest in +Se compared to −Se and ++Se feeding indicating that selenium might delay tumorigenesis only in the adequate status. In conclusion, the role of GPx2 and presumably also of selenium depends on the cancer stage and obviously on the involvement of inflammation.

Lkb1 loss promotes tumor progression of BRAF(V600E)-induced lung adenomas

Aberrant activation of MAP kinase signaling pathway and loss of tumor suppressor LKB1 have been implicated in lung cancer development and progression. Although oncogenic KRAS mutations are frequent, BRAF mutations (BRAF^V600E) are found in 3% of human non-small cell lung cancers. Contrary to KRAS mutant tumors, BRAF^V600E-induced tumors are benign adenomas that fail to progess. Interestingly, loss of tumor supressor LKB1 coexists with KRAS oncogenic mutations and synergizes in tumor formation and progression, however, its cooperation with BRAF^V600E oncogene is unknown. Our results describe a lung cell population in neonates mice where expression of BRAF^V600E leads to lung adenoma development. Importantly, expression of BRAF^V600E concomitant with the loss of only a single-copy of Lkb1, overcomes senencence–like features of BRAF^V600E-mutant adenomas leading malignization to carcinomas. These results posit LKB1 haploinsufficiency as a risk factor for tumor progression of BRAF^V600E mutated lung adenomas in human cancer patients.

[The expression of MGMT in pituitary adenomas and its association with tumour aggressiveness]

OBJECTIVE

To determine the expression of O6-methylguanine-DNA methyltransferase (MGMT) in pituitary adenomas and its association with tumour aggressiveness.

METHODS

From October 2011 to August 2012, all the patients with pathologically confirmed pituitary adenomas in our hospital were recruited for this study. The expression of MGMT in the tumor tissues was detected with immunohistochemistry.

RESULTS

A total of 138 (including 71 male) patients participated in this study. The majority of the participants had nonfunctional (71%) and macroadenomas (92.8%). Aggressive and relapsed pituitary adenomas accounted for 31.2% and 8.7% of the cases, respectively. Low MGMT expression was found in 79 cases. The MGMT expression had no significant associations with gender, age, aggressiveness and relapse of tumors. However, prolactinomas were more likely to have low MGMT expression than nonfunctional adenomas (P = 0.025) and growth hormone adenomas (P = 0.043).

CONCLUSION

The expression of MGMT has no associations with the aggressiveness and relapse of pituitary adenomas. Prolactinomas are more likely to have low expression of MGMT, which indicates that temozolomide might become an alternative treatment for aggressive and dopamine resistant prolactinomas.

Associations of oxidative balance-related exposures with incident, sporadic colorectal adenoma according to antioxidant enzyme genotypes

PURPOSE

Previous research found inverse associations between oxidative balance and risk of colorectal adenoma. However, these measures were limited to extrinsic (dietary and lifestyle) exposures and did not account for intrinsic factors, specifically antioxidant enzymes responsible for cellular defense against oxidative stress. We investigated whether the association between an oxidative balance score (OBS) and colorectal adenoma may vary according to polymorphisms in genes that encode three antioxidant enzymes: Manganese superoxide dismutase (SOD2), catalase (CAT), and glutathione-S-transferase P1 (GSTP1).

METHODS

Using data pooled from three colonoscopy-based case-control studies of incident, sporadic colorectal adenoma, we constructed an OBS reflecting pro- and antioxidant exposures. We used multivariable logistic regression to assess whether the association between the OBS and colorectal adenoma differed according to polymorphisms in the genes encoding the antioxidant enzymes.

RESULTS

OBS was inversely associated with colorectal adenoma; adenoma risk was not associated with the genetic polymorphisms, and there was no consistent pattern of effect modification by individual genotypes or combined gene scores.

CONCLUSIONS

Variations in the antioxidant enzyme genes SOD2, CAT, and GSTP1 do not seem to substantially modify associations of environmental exposures related to oxidative balance with risk for sporadic colorectal adenoma.

Evaluation of removable statistical interaction for binary traits

This paper is concerned with evaluating whether an interaction between two sets of risk factors for a binary trait is removable and, when it is removable, fitting a parsimonious additive model using a suitable link function to estimate the disease odds (on the natural logarithm scale). Statisticians define the term 'interaction' as a departure from additivity in a linear model on a specific scale on which the data are measured. Certain interactions may be eliminated via a transformation of the outcome such that the relationship between the risk factors and the outcome is additive on the transformed scale. Such interactions are known as removable interactions. We develop a novel test statistic for detecting the presence of a removable interaction in case-control studies. We consider the Guerrero and Johnson family of transformations and show that this family constitutes an appropriate link function for fitting an additive model when an interaction is removable. We use simulation studies to examine the type I error and power of the proposed test and to show that, when an interaction is removable, an additive model based on the Guerrero and Johnson link function leads to more precise estimates of the disease odds parameters and a better fit. We illustrate the proposed test and use of the transformation by using case-control data from three published studies. Finally, we indicate how one can check that, after transformation, no further interaction is significant.

Genetic variation in the lipoxygenase pathway and risk of colorectal neoplasia

Arachidonate lipoxygenase (ALOX) enzymes metabolize arachidonic acid to generate potent inflammatory mediators and play an important role in inflammation-associated diseases. We investigated associations between colorectal cancer risk and polymorphisms in ALOX5, FLAP, ALOX12, and ALOX15, and their interactions with nonsteroidal anti-inflammatory drug (NSAID) use. We genotyped fifty tagSNPs, one candidate SNP, and two functional promoter variable nucleotide tandem repeat (VNTR) polymorphisms in three US population-based case-control studies of colon cancer (1,424 cases/1,780 controls), rectal cancer (583 cases/775 controls), and colorectal adenomas (485 cases/578 controls). Individuals with variant genotypes of the ALOX5 VNTR had a decreased risk of rectal cancer, with the strongest association seen for individuals with one or more alleles of >5 repeats (wild type = 5, OR>5/≥5 = 0.42, 95% CI 0.20-0.92; P = 0.01). Four SNPs in FLAP (rs17239025), ALOX12 (rs2073438), and ALOX15 (rs4796535 and rs2619112) were associated with rectal cancer risk at P ≤ 0.05. One SNP in FLAP (rs12429692) was associated with adenoma risk. A false discovery rate (FDR) was applied to account for false positives due to multiple testing; the ALOX15 associations were noteworthy at 25% FDR. Colorectal neoplasia risk appeared to be modified by NSAID use in individuals with variant alleles in FLAP and ALOX15. One noteworthy interaction (25% FDR) was observed for rectal cancer. Genetic variability in ALOXs may affect risk of colorectal neoplasia, particularly for rectal cancer. Additionally, genetic variability in FLAP and ALOX15 may modify the protective effect of NSAID use against colorectal neoplasia.

Effects of AMPK activation and combined treatment with AMPK activators and somatostatin on hormone secretion and cell growth in cultured GH-secreting pituitary tumor cells

We investigated the effects of the AMPK activator AICAR as compared to somatostatin-14 on cell viability and GH secretion in human GH-secreting pituitary adenomas in vitro and in rat GH3 cells. Overnight treatment with AICAR increased phospho-(threonine-172) AMPK levels (activated AMPK) in cultured human adenomas. As to the effects on cell viability, four adenomas out of 15 were responsive to AICAR (0.4mM) and five adenomas were responsive to SS-14 (100 nM). One adenoma was responsive to both somatostatin and AICAR. The effects of cotreatment with SS-14 and AICAR were investigated in eight adenomas. In two adenomas, the effects of AICAR+SS-14 did not exceed the effect of AICAR. In two adenomas which were not responsive to either AICAR or SS-14, the cotreatment was able to reduce cell viability versus control. Two adenomas were not responsive to any treatment. As to the effects on GH secretion, nine adenomas out of 15 were responsive to AICAR. Twelve adenomas were responsive to SS-14. Eight adenomas were responsive to both AICAR and SS-14. Cotreatment exceeded the effect of single treatments in 4 out of 10 adenomas. In GH3 cells, AICAR reduced the activity of p70S6 kinase, which plays an important role in cell growth. SS-14 did not affect significantly AMPK phosphorylation and p70S6K activity but it was able to enhance the inhibitory effect of AICAR on phospho-S6 levels. Moreover, AICAR and SS-14 reduced ERK phosphorylation with a different time course. The combined treatment reduced phospho-ERK levels at any time point.

Characterization of steroidogenic enzyme expression in aldosterone-producing adenoma: a comparison with various human adrenal tumors

We analyzed the expression profiles of several steroidogenic enzymes in normal adrenals, aldosterone-producing adenomas (APA), cortisol-producing adenomas combined with Cushing's syndrome (CPA) or with subclinical Cushing's syndrome (SCPA), and nonfunctioning adrenal adenomas (NFA) to clarify the nature and characteristics of steroidogenesis in APA. Clinical data were collected for all subjects. In resected adrenal glands (normal adrenals, APA, CPA, SCPA, and NFA), the mRNA expression levels of the CYP17, HSD3B2, CYP11B1, and CYP11B2 genes were studied using real-time quantitative PCR and immunohistochemistry. The CYP11B2 mRNA level in APA was significantly higher than that in other groups. The CYP17/HSD3B2 ratio for mRNA in APA was significantly lower than those in the other groups. Low ratio of CYP17/HSD3B2 with high expression of CYP11B2 seems to explain steroidogenic characteristics of APA.

β-Catenin regulates deiodinase levels and thyroid hormone signaling in colon cancer cells

BACKGROUND & AIMS

Activation of the β-catenin/T-cell factor (TCF) complex occurs in most colon tumors, and its actions correlate with the neoplastic phenotype of intestinal epithelial cells. Type 3 deiodinase (D3), the selenoenzyme that inactivates thyroid hormone (3,5,3' triiodothyronine [T3]), is frequently expressed by tumor cells, but little is known about its role in the regulation of T3 signaling in cancer cells.

METHODS

We measured D3 expression in 6 colon cancer cell lines and human tumors and correlated it with the activity of the β-catenin/TCF complex. We also determined the effects of D3 loss on local thyroid hormone signaling and colon tumorigenesis.

RESULTS

We show that D3 is a direct transcriptional target of the β-catenin/TCF complex; its expression was higher in human intestinal adenomas and carcinomas than in healthy intestinal tissue. Experimental attenuation of β-catenin reduced D3 levels and induced type 2 deiodinase (the D3 antagonist that converts 3,5,3',5' tetraiodothyronine into active T3) thereby increasing T3-dependent transcription. In the absence of D3, excess T3 reduced cell proliferation and promoted differentiation in cultured cells and in xenograft mouse models. This occurred via induction of E-cadherin, which sequestered β-catenin at the plasma membrane and promoted cell differentiation.

CONCLUSIONS

Deiodinases are at the interface between the β-catenin and the thyroid hormone pathways. Their synchronized regulation of intracellular T3 concentration is a hitherto unrecognized route by which the multiple effects of β-catenin are generated and may be targeted to reduce the oncogenic effects of β-catenin in intestinal cells.

Deletion of p38-alpha mitogen-activated protein kinase within the intestinal epithelium promotes colon tumorigenesis

BACKGROUND

p38-Alpha mitogen-activated protein kinase (p38-MAPK) is a tumor suppressor often mutated in human cancers, but its specific role in colorectal cancer is not completely understood. Previous studies have found that p38-MAPK activity inhibits epithelial proliferation and promotes apoptosis in the intestine. Therefore, we sought to test the hypothesis that intestinal disruption of p38-MAPK would lead to increased tumorigenesis in the colon.

METHODS

p38-MAPK was deleted in mice within the intestinal epithelium using a tamoxifen-inducible Cre system under control of the villin promoter [villin-Cre ERT2(+), MAPK14(f/f)]. An azoxymethane and dextran sodium sulfate protocol was used to drive intestinal tumor development. Tumor measurements were made using computer software from photographs of excised colon specimens.

RESULTS

The number of mice that developed tumors was not statistically different when comparing wild-type mice (7/14) to inducible, intestine epithelial-deleted p38-MAPK (9/11) mice after azoxymethane/dextran sodium sulfate treatment (P = .21). However, the epithelial-deleted p38-MAPK mice developed significantly more tumors (3.7 vs 1.1; P = .008) and nearly 4 times the total tumor burden as wild-type mice (17.4 vs 4.8 mm(2); P = .03). Wild-type and epithelial-deleted p38-MAPK groups demonstrated a similar degree of colon inflammation.

CONCLUSION

Deletion of p38-MAPK within the colonic mucosa leads to a hyperplastic state promoting greater tumor development. Because the severity of colitis was not augmented in mice with p38-MAPK deficiency, tumor development is likely mediated by impaired cell cycle regulation within the colonic epithelium. Manipulation of p38-MAPK activity may provide a novel treatment and/or prevention strategy in the management of colorectal cancer, particularly in the setting of inflammatory bowel disease.

Progressive increase of matrix metalloprotease-9 and interleukin-8 serum levels during carcinogenic process in human colorectal tract

BACKGROUND

Inflammatory reactions, known to promote tumor growth and invasion, have been found associated with colorectal carcinoma (CRC). Macrophages are the chief component of the inflammatory infiltration that occurs early in the progression from non-invasive to malignant tumor, with a switch from the pro-inflammatory phenotype to the tumor-promoting phenotype. Tumor and stroma are additional sources of inflammation-related molecules. The study aimed to evaluate, during colorectal carcinogenesis from benign to malignant phases: i) the trend of serum levels of IL-8, IL-6, TGFβ1, VEGF and MMPs; ii) the parallel trend of CRP serum levels; iii) derangement of the principal TGFβ1 receptors (TGFβ1RI/RII) in tumor tissues.

METHODOLOGY/PRINCIPAL FINDINGS

96 patients with colon adenomas or CRC at different stages of progression, and 17 controls, were recruited. Serum IL-8, IL-6, TGFβ1, VEGF, MMPs and CRP levels were analyzed before endoscopy or surgery. TGFβ1 receptors were evaluated in adenoma biopsies and surgically-removed colorectal adenocarcinomas. Serum levels of IL-8 in adenocarcinoma patients were increased from stage II, when also the enzymatic activity of MMP-9 increased. Of note, the increasing trend of the two serum markers was found significantly correlated. Trend of serum CRP was also very similar to that of IL-8 and MMP-9, but just below statistical significance. TGFβ1 levels were lower at stage III CRC, while IL-6 and VEGF levels had no significant variations. In tissue specimens, TGFβ1 receptors were already absent in about 50% of adenomas, and this percentage of missing receptors markedly increased in CRC stages III and IV.

CONCLUSIONS

Combined quantification of serum IL-8, MMP-9 and CRP, appears a reliable and advanced index of inflammation-related processes during malignant phase of colorectal carcinogenesis, since these molecules remain within normal range in colorectal adenoma bearing patients, while consistently increase in the blood of CRC patients, even if from stage II only.

BRAF mutations in metanephric adenoma of the kidney

BACKGROUND

Metanephric adenoma (MA) of the kidney is a rare, indolent tumor that may be difficult to differentiate from other small renal masses (SRMs). Genetic alterations associated with MA remain largely unknown.

OBJECTIVE

We aimed at defining genetic events in MA of the kidney and determining their influence in the management of this disease.

DESIGN, SETTING, AND PARTICIPANTS

Multiplexed mass spectrometric genotyping was performed on 29 MA cases after tumor DNA extraction. We also conducted a mutational screen in an additional 129 renal neoplasms. Immunohistochemistry was performed on the MA cases to assess molecular markers of signaling pathway activation. Patients' baseline characteristics, as well as follow-up data, were captured.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

We used descriptive statistics for baseline clinical characteristics and incidence of mutations. The Wilcoxon rank-sum test was used to correlate patient characteristics with mutational status.

RESULTS AND LIMITATIONS

We identified the v-raf murine sarcoma viral oncogene homolog B1 (BRAF) V600E mutation in 26 of 29 MA cases. These results were validated in all cases using the commercially available BRAF Pyro Kit (QIAGEN). In contrast, BRAF mutations were rare in the other 129 non-MA renal neoplasms that were screened. We detected a BRAF mutation (V600E) in only one papillary renal cell carcinoma case. In all MA tumors, we documented expression of phosphorylated mitogen-activated protein kinase and phosphorylated extracellular signal-regulated kinase, accompanied by immunoreactivity for p16 (INK4a). All patients were treated with a partial or radical nephrectomy, and after a median follow-up of 26.5 mo, there were no local or distant recurrences. Limitations include the retrospective nature of this study.

CONCLUSIONS

BRAF V600E mutations are present in approximately 90% of all MA cases, serving as a potential valuable diagnostic tool in the differential diagnosis of SRMs undergoing a percutaneous biopsy. The presence of BRAF V600E and mitogen-activated protein kinase activation in a largely benign tumor supports the necessity for secondary events (e.g., p16 loss) in BRAF-driven oncogenesis.

Positive correlation between type 1 and 2 iodothyronine deiodinases activities in human goiters

Type 1 (D1) and 2 (D2) iodothyronine deiodinases are selenocysteine-containing enzymes that catalyze the deiodination of T4 to T3 in the thyroid and in peripheral tissues. Despite their importance to the plasma T3 pool in human beings, there are few studies about their behavior in human thyroids. In order to better understand iodothyronine deiodinase regulation in the thyroid gland, we studied thyroid tissue samples from follicular adenoma (AD, n = 5), toxic diffuse goiter (TDG, n = 6), nontoxic multinodular goiter (NMG, n = 40), papillary thyroid carcinoma (PTC, n = 8), and surrounding normal tissues (NT, n = 7) from 36 patients submitted to elective thyroidectomy. D1 and D2 activities were determined by quantification of the radioiodine released by ¹²⁵I-rT3 or ¹²⁵I-T4 under standardized conditions, and expressed as pmol rT3 deiodinated per minute and mg protein (pmol rT3 min⁻¹ mg⁻¹ ptn) and fmol T4 deiodinated per minute and mg protein (fmol T4 min⁻¹ mg⁻¹ ptn), respectively. D1 activity detected in TDG and AD tissues were significantly higher than in NT, PTC or NMG samples. D2 activity was also significantly higher in TDG and AD samples than in PTC, NMG, or NT. There was great variability in D1 and D2 enzymatic activities from distinct patients as well as from different areas from the same goiter. There was a positive correlation (P < 0,0001, r = 0.4942) between D1 and D2 activities when all samples were taken into account, suggesting that-in the thyroid-these two iodothyronine deiodinases may have related regulatory mechanisms, even if conditioned by other as yet unknown factors.

Intriguing location of myeloperoxidase in the prostate: a preliminary immunohistochemical study

BACKGROUND

Myeloperoxidase (MPO) is a member of the peroxidase-cyclooxygenase superfamily, which is secreted from stimulated leucocytes at inflammatory sites. It is well known that MPO catalyses oxidation reactions via the release of reactive halogenating and nitrating species and thus induces tissue damage. Several studies have already implicated MPO in the development of neoplasia. Chronic or recurrent prostatic inflammation has long been recognized as having the potential to initiate and promote the development of prostate cancer. The objective was to investigate whether MPO is present in the prostate.

METHODS

Human prostate material was obtained from biopsies, transurethral resections of the prostate (TURP), prostatic adenomectomies, and retropubic radical prostatectomies. Twenty-nine slides of normal prostate tissue, benign prostatic hyperplasia (BPH), and prostate cancer were reviewed by a pathologist. Immunohistochemical analysis using MPO-specific human antibody was performed to detect MPO in the prostate tissue.

RESULTS

Immunocytohistochemistry showed cellular colocalization of MPO in the secretory epithelial cells of the prostate with staining varying from light to strong intensity. Staining in the glandular apical snouts was often reinforced although staining of basal as well as of luminal glandular cells was also present.

CONCLUSIONS

We identified, for the first time, the presence of MPO at the surface of prostatic epithelial cells. In view of the pro-oxidant properties of this enzyme, further research is needed to define whether MPO contributes to the development of prostatic lesions.

Cyclooxygenase-2 expression in the normal human eye and its expression pattern in selected eye tumours

PURPOSE

Cyclooxygenase-2 (COX-2) is an enzyme involved in neoplastic processes. The purpose of the present study is to investigate COX-2 expression in the normal human eye and the expression pattern in selected eye tumours involving COX-2 expressing cells.

METHODS

Immunohistochemical staining using antibodies against COX-2 was performed on paraffin sections of normal human eyes and selected eye tumours arising from cells expressing COX-2.

RESULTS

Cyclooxygenase-2 expression was found in various structures of the normal eye. Abundant expression was seen in the cornea, iris, ciliary body and retina. The COX-2 expression was less in tumours deriving from the ciliary epithelium and also in retinoblastoma.

CONCLUSION

Cyclooxygenase-2 is constitutively expressed in normal human eyes. The expression of COX-2 is much lower in selected eye tumours involving COX-2 expressing cells.

Lack of influence of the ADH1B Arg47His genetic polymorphism on risk of colorectal adenoma in middle-aged Japanese men

Alcohol consumption is one of the risk factors for colorectal cancers and adenomas. Since alcohol dehydrogenase is a key enzyme in alcohol metabolism, it may thus play a role in colorectal carcinogenesis. The present study was conducted to assess the association of a functional ADH1B Arg47His polymorphism with colorectal adenomas in a case-control study of male officials in the Self-Defense Forces who received a pre-retirement health examination at two Self-Defense Forces hospitals. The study subjects comprised 455 with colorectal adenomas and 1,052 controls without polyps, all of whom underwent total colonoscopy. Statistical adjustment was made for age, hospital, Self-Defense Forces rank, body mass index, cigarette-years, and alcohol consumption. There was no measurable association between the ADH1B Arg47His polymorphism and colorectal adenoma development. The adjusted odds ratio for individuals with the 47His/His genotype compared to those with individuals with 47Arg alleles was 1.18 (95% confidence interval 0.94-1.49). There was no influence of the level of alcohol consumption (interaction P = 0.84). In addition, there were no clear interactions of the ADH1B with ALDH2 Glu487Lys and MTHFR C677T with regard to the risk of colorectal adenoma. In conclusion, the present study suggested that the ADH1B Arg47His polymorphism does not contribute to the risk of colorectal adenoma in any subgroup of middle-aged Japanese men defined by alcohol drinking, as well as the ALDH2 Glu487Lys and MTHFR C677T genotypes.

Salvage therapy with temozolomide in patients with aggressive or metastatic pituitary adenomas: experience in six cases

OBJECTIVE

The prognosis of either pituitary carcinoma or aggressive pituitary adenoma resistant to standard therapies is poor. We assessed the efficacy of treatment with temozolomide, an oral second-generation alkylating agent, in a consecutive series of six patients with aggressive pituitary adenomas.

DESIGN

This was a 1-year prospective study of temozolomide therapy in six consecutive patients with pituitary carcinoma (one case) or atypical pituitary adenoma (five cases) resistant to standard therapies. There were three males and three females. Age at enrollment ranged between 52 and 64 years. Temozolomide was given orally at a dose of 150-200 mg/m(2) per day for 5 days every 4 weeks for a maximum of 12 cycles.

METHODS

Response assessment was based on measurable change in tumor size, as assessed on magnetic resonance imaging, and hormone levels. Response was defined as reduction of at least 50% of tumor size and hormone levels.

RESULTS

Four patients completed the 12 cycles of temozolomide treatment, as planned. Two patients stopped the drug after 3 and 6 months respectively because of the progression of disease. Two patients responded to temozolomide, while the remaining two patients had stable disease. Immunohistochemistry for O(6)-methylguanine-DNA methyltransferase (MGMT) in tumor sample showed a partial association with treatment response.

CONCLUSIONS

Temozolomide treatment has a wide range of efficacy in patients with pituitary carcinoma or locally aggressive pituitary adenoma. Positive staining for MGMT seems likely to predict a lower chance of response.

Baseline plasma total homocysteine and adenoma recurrence: results from a double blind randomized clinical trial of aspirin and folate supplementation

BACKGROUND

Elevated plasma total homocysteine (tHcy) is an accepted marker of functional folate deficiency but may have independent effects on colorectal neoplasia risk. It is uncertain whether plasma tHcy is associated with risk at the low levels common in a folate-fortified population.

METHODS

Study subjects, about half of whom were recruited after fortification of grain products with folic acid in the United States and Canada, consisted of 871 individuals with a recent history of one or more colorectal adenomas who were randomized to receive either a 1 mg/day folic acid supplement or a placebo within one of three randomly assigned aspirin treatment groups (placebo, 81, or 325 mg/day). Nonfasting plasma tHcy was determined by a gas chromatograph mass chromatography method. We estimated adjusted risk ratios and 95% confidence intervals (95% CI) for one or more adenoma recurrences for each quartile of baseline plasma tHcy using generalized linear regression with an overdispersed Poisson approximation to the binomial.

RESULTS

The Q4/Q1 adjusted risk ratio for any adenoma was 0.98 (95% CI, 0.70-1.38; P trend = 0.17) in the placebo group, and 0.81 (95% CI, 0.58-1.12; P-trend = 0.17) in the folic acid group. Results were similar for adenomas with advanced features. There was no modification by sex, aspirin treatment group or MTHFR 677C>T genotype.

CONCLUSIONS

Plasma tHcy is not an independent marker for an increase in colorectal adenoma recurrence risk in postfortification populations in which plasma tHcy levels are in the lower range of values.

IMPACT

Controlling plasma tHcy levels is unlikely to favorably modify adenoma recurrence risk in folate-fortified populations.

The effect of polymorphisms in the promoter region of the MMP-1 gene on the occurrence and invasiveness of hypophyseal adenoma

BACKGROUND

The matrix metalloproteinase-1 enzyme (MMP-1, also called collagenase 1) plays a key role in turnover of collagen fibers in the intercellular matrix. Insertion of a guanine residue was found within the promoter region of the MMP-1 gene. We found that MMP-1 levels increased approximately twofold over normal when this insertion was present, enabling MMP-1 to facilitate tumor invasion and metastasis. MMP-1 is also believed to play a role in tumor development. The aim of our study is to investigate the effect of polymorphisms in the promoter region of the MMP-1 gene on the development of benign and invasive hypophyseal adenomas.

PATIENTS AND METHODS

Thirty patients with hypophyseal adenomas diagnosed by radiological examination underwent surgical removal, and the diagnosis was confirmed using immunohistochemical staining of the pathology specimens. We found that ten of these patients had invasive adenomas confirmed by radiological examination and immunohistochemical staining. DNA isolation was performed on all specimens, and 5-cc venous blood samples were obtained from all patients as well as 30 volunteers using the Qiagen QIAquick kit. Promoter regions of MMP-1 genes from the DNA samples were amplified using polymerase chain reaction (PCR) and primers designed for the site-directed mutation method. Following PCR, a guanine residue within the promoter region of the MMP-1 gene was identified using the restriction fragment length polymorphism method and the ALU I restriction enzyme. Three genotypes were detected in a genotyping assay: 2G/2G, 1G/2G, and 1G/1G.

RESULTS

Of the surgically treated patients, 36.6% had the 2G/2G genotype, 46.6% had the 1G/2G genotype, and 16.6% had the 1G/1G genotype. The 2G allele frequency was found to be 83.4%. In 90% of cases of invasive adenoma, a homozygous 2G/2G genotype was detected.

DISCUSSION

The risk for development of hypophyseal adenoma may be greater in patients with the 2G allele. In cases of existing hypophyseal adenoma, those with the homozygous 2G allele tend to be invasive.

Overexpression of 5-lipoxygenase in sporadic colonic adenomas and a possible new aspect of colon carcinogenesis

PURPOSE

We aimed to study the intracellular expression of 5-lipoxygenase (5-LOX), the primary competitor with cyclooxygenase-2 in arachidonic acid metabolism, as inflammatory enzymes may be involved in blocking apoptosis and promoting cancer growth by changing arachidonic acid metabolism within cells. Our purpose was to investigate the possible connection between 5-LOX expression and colon carcinogenesis by characterizing 5-LOX expression in histologically different colonic adenomas, determining the relationship between high expression of 5-LOX and various conventional clinicopathological features of adenomas, and finally characterizing the histological localization of cells with 5-LOX overexpression.

METHODS

A total of 111 patients were examined and 120 histologically different colonic adenomas analyzed (including four cases of intramucosal adenocarcinoma in a polyp). Immunohistochemical staining with polyclonal anti-5-LOX antibodies was performed.

RESULTS

There was a significant correlation between high 5-LOX expression and patient age, increased polyp size, high grade of intraepithelial neoplasia, villous and tubulovillous adenoma, and histological epithelial localization.

CONCLUSIONS

We observed a strong positive correlation between 5-LOX overexpression and the appearance of typical high-risk factors for malignant transformation in adenomatous polyps. The results support the role of 5-LOX in early stages of colon carcinogenesis.