Virus-like particle formation in Drosophila melanogaster germ cells suggests a complex translational regulation of the retrotransposon cycle and new mechanisms inhibiting transposition

Transposition of 1731, a Drosophila melanogaster LTR retrotransposon, was investigated in reproductive organs by RNA, protein and VLP distribution during its life cycle. We detected 1731 transcription in oogonia but not in spermatogonia; in all cells during oogenesis but only in primary spermatocytes; and in ovarian cytoplasm but both in nuclei and cytoplasm of primary spermatocytes. By confocal scanning, we showed that whereas Gag protein appeared in all cytoplasms during oogenesis, in testes Gag detection began in late premeiotic primary spermatocytes and increased in elongating spermatids suggesting distinct mechanisms of 1731 transcription and translation regulation. By electron microscopy, we did not detect 1731 VLPs in ovaries, suggesting a complex post-translational control blocking VLP assembly and transposition. Interestingly, in testes we discovered VLP aggregates in cystic cytoplasm of maturing partially individualized spermatids. In testes, we observed two delays in 1731 product expressions, suggesting a complex temporal control mechanism. Transcriptional/translational delay may be determined by accumulation of 1731 RNAs in primary spermatocyte nuclei. Translational/VLP assembly delay may be determined by post-transductional mechanisms controlling +1 frameshift and Pol-protein degradation. Our results indicated two differential mechanisms inhibiting 1731 transposition in Drosophila melanogaster ovaries and testes. In addition, we proposed a new mechanism for transposition control at the cell cycle level.

C21orf5, a human candidate gene for brain abnormalities and mental retardation in Down syndrome

Mental retardation represents the more invalidating pathological aspect of trisomy 21 and has a hard impact on public health. The dosage imbalance of chromosome 21 genes could be the cause of neurological alterations and mental retardation seen in Down syndrome. We studied C21orf5 that we have demonstrated to be overexpressed in Down syndrome tissues, as a candidate gene for trisomy 21. A new optical technology (Rachidi et al., 2000) was used to compare signal intensity and cell density in presumptive embryonic brain compartments, at their boundaries and in higher specialized brain centres during fetal lifespan. We showed a developmentally regulated transcriptional activity of C21orf5 and a regional and cellular specific distribution of gene transcripts during human embryonic and fetal development. A wide but differential expression was detected in the nervous system during embryogenesis with a relatively lower level in the forebrain than in the midbrain and hindbrain and the highest transcription intensity in the future cerebellum. This developmentally regulated expression is maintained during post-embryogenesis and evolves selectively in fetal cerebral, hippocampal and cerebellar areas. Differential and cellular specificity were detected in hippocampus with higher C21orf5 mRNA level in the pyramidal cells compared to granular cells of the dentate gyrus. The expression pattern detected in cortical and cerebellar structures correlates well to the altered cortical lamination and to the lower size of the cerebellum observed in Down syndrome patients. In addition, the patterned differential expression detected in the medial temporal-lobe system, including hippocampal formation and perirhinal cortex, working as control centres of the memory circuits and involved in cognitive processes and memory storage, also corresponds to abnormal brain regions seen in Down syndrome patients. The C21orf5 selective expression in the key brain structures for learning and memory suggests that C21orf5 overexpression could participate in mental retardation pathogenesis in Down syndrome patients.

Characterization of HPV genotype profile in squamous cervical lesions in Portugal, a southern European population at high risk of cervical cancer

A different prevalence of human papillomavirus (HPV) types has been reported in distinct populations. Although Portugal has a relatively high incidence of cervical cancer within the European Union, no studies have been reported in the Portuguese population. Recently, a clinical trial using a vaccine targeted against HPV-16 demonstrated a high efficacy in preventing HPV-16 cervical lesions. The aim of the present study was the characterization of HPV genotype profile in squamous intraepithelial lesions (SIL) and invasive cervical cancer (ICC) from 608 patients using polymerase chain reaction (PCR) methodology. We frequently detected HPV-6/11 and HPV-16 in low-grade SIL (HPV-6/11, 18.9%; HPV-16, 44.2%). In high-grade SIL, HPV-16 was demonstrated in 74.2% of those lesions and in 80.0% of the cases with ICC. HPV-18 was found in 3.1%, 0.8% and in 15.0% of low, high SIL and ICC, respectively. The overall prevalence of multiple infections with high-risk HPV was 7.2%. Other types of HPV were detected in 7.0% of all cases. Our results demonstrate a high prevalence of HPV-16 in SIL and ICC in Portuguese women. Therefore, a prophylactic HPV-16/18 vaccine may be effective in the prevention of cervical cancer in a significant number of women from this southern European population.

E-cadherin, CD44 and CD44v6 in squamous intraepithelial lesions and invasive carcinomas of the uterine cervix: an immunohistochemical study

OBJECTIVE

To evaluate the immunoexpression pattern of E-cadherin, CD44std and the variant isoform v6 in normal squamous epithelium, low and high squamous intraepithelial lesions (SILs) and invasive squamous cell carcinomas (ISCCs) of the uterine cervix. The purpose was to determine whether any distinctive change in antigenic expression could contribute to the recognition of the earliest commitment to neoplasia and/or the onset of the invasive phenotype.

METHODS

Immunohistochemistry using the avidin-biotin indirect immunoperoxidase method was used to study the protein expression of epithelial cadherin (E-cadherin), cluster differentiation 44 (CD44), and the isoform v6 (CD44v6) in 124 human cervical samples (5 normal, 39 low-grade, 54 high-grade and 26 ISCCS) in formalin-fixed, paraffin-embedded tissue blocks.

RESULTS

Membranous expression of E-cadherin, CD44 and CD44v6 was preserved in normal squamous epithelium and in low-grade squamous intraepithelial lesions. A significant association was observed with the histological grade of the SILs and the immunoreactivity (membranous versus cytoplasmic) pattern of E-cadherin (p < 0.001), CD44std (p = 0.027) and CD44v6 (p < 0.001). A loss of membranous staining and a progressive increase in cytoplasmic staining was observed from low to high grade SILs to ISCCs.

CONCLUSIONS

Our study demonstrates that during the development of cervical lesions substantial qualitative (subcellular localization-membrane to cytoplasmic) and quantitative alterations (changes in expression) occur in the protein expression of E-cadherin, CD44, and CD44v6 in cervical cancer. The most striking observation was the decrease in membranous immunoreactivity and the progressive increase in cytoplasmic staining of E-cadherin, CD44 and CD44v6, relating to loss of differentiation as a consequence of neoplastic transformation.

Role of steroid hormones and prolactin in canine mammary cancer

In several animal studies, prolactin has been found to be essential for mammary epithelial development, and its administration has been consistently shown to increase the rate of mammary tumours. High levels of steroid hormones have also been suggested to enhance mammary cancer development. The present study investigates the levels of the following hormones in serum and in tissue homogenates in dogs bearing canine mammary tumours: prolactin (PRL), progesterone (P4), dehydroepiandrosterone (DHEA), androstenedione (A4), testosterone (T), 17beta-estradiol (17beta-E2) and estrone sulfate (S04E1). Eighty mammary tumours (40 dysplasias and benign and 40 malignant tumours) from 32 female dogs, and 10 normal mammary glands from eight female dogs without history of mammary tumours, were analysed. Prolactin and steroid hormones in serum and tissue homogenates, were analysed by enzyme immunoassays (EIA) techniques, previously validated for this animal species. Levels of prolactin in tissue homogenates were significantly different between malignant and benign mammary tumours (p<0.01). Serum prolactin concentrations were lower in the control group as compared with the group of dogs with benign tumours and in dogs with malignant tumours (p=0.01). Serum prolactin levels in dogs with benign lesions were not significantly different than those obtained from dogs with malignant tumours. Levels of steroid hormones were significantly higher in malignant tumours compared with the benign tumours and normal mammary glands (p<0.01) both in serum and homogenate determinations. Our results suggest that the canine neoplastic mammary gland could be a source of prolactin. Our hypothesis is that both prolactin and steroid hormones are involved in the growth of canine mammary cancer, and that they might have an autocrine/paracrine role in the maintenance of this disease.

Leptin and prostate: implications for cancer prevention--overview of genetics and molecular interactions

Leptin's relation with obesity has been clearly demonstrated while its role in oncobiology is still largely unknown. Epidemiological studies on serum leptin provide valuable though controversial data, while in vitro studies consistently show leptin's angiogenic and proliferative potential in cancer. Leptin's activity is mediated by tissue-specific receptors, differentially expressed in organs such as the prostate. The molecular cascades triggered by leptin result in prostatic cell proliferation and angiogenic activity, thus linking the hormone mainly to prostate cancer prognosis. This review also addresses leptin's metabolic interactions with cytokines, growth factors or hormones, establishing perceptive pathways leading to carcinogenesis or prostate cancer progression and metastasis. Better understanding of these mechanisms may help in the development of new and more effective treatments for prostate cancer. The consolidation of leptin molecular genetics profile in prostate cancer patients may help to create susceptibility groups in normal individuals, facilitating a preventive dietary intervention or strategies for chemoprevention. We hypothesize that the balance between androgen and leptin levels may facilitate the increase in the ratio of androgen-independent prostate cancer cells to androgen-dependent cells in the tumour.

Evaluation of patient dose for mammography in Pernambuco, Brazil

The aim of this study is to evaluate the incident air kerma (INAK) and the mean glandular dose (MGD) during mammography in Recife, North-east Brazil. The study was performed in three institutions: a private clinic (A), a public hospital (B) and a private hospital (C). The incident air kerma to mammography procedures were estimated using a standard breast phantom and the patient MGD, evaluated in the units B and C, was performed using the calibration of output method. This method involves the recording of the patient exposure parameters (kVp, mAs, filter) and the measurement of these parameters of the incident air kerma using a calibrated ionisation chamber. The results obtained showed that INAK for the standard breast phantom, in the institutions A, B and C, were 18.2, 9.4 and 8.5 mGy, respectively. The results of patient MGD values ranged from 0.23 to 7.46 mGy per film, and the MGD values per woman were between 8.23 and 40.6 mGy for the C institution and between 1.50 and 18.78 mGy for the B institution.

Polymorphisms of the human OGG1 gene in laryngeal cancer: implications in radiotherapy response and survival

The human OGG1 (hOGG1) gene encodes a DNA glycosylase involved in the excision repair of 8-hydroxy-2'-deoxyguanine (8-OH-dG) from oxidatively-damaged DNA. Ser326Cys polymorphism in the hOGG1 gene is involved in the repair of 8-hydroxyguanine in oxidatively damaged DNA, and appears to be related to susceptibility to certain smoking and alcohol-related orolaryngeal cancers.

OBJECTIVE

To analyse if hOGG1 Ser326Cys (exon 7: m6) polymorphism is associated with tumour localization, T, stage and histologic differentiation, and if radiotherapy results were influenced by this polymorphism.

MATERIAL AND METHOD

Blood samples were obtained before treatment from seventy one patients with laryngeal cancer and screened by a PCR-RFLP method.

RESULTS

Although hOGG1 gene is important in DNA repair mechanisms, no significant association was observed between hOGG1 Ser326Cys (exon 7: m6) polymorphism, tumour characteristics and radiotherapy results.

CONCLUSION

So the analysis of this polymorphism is not important for treatment decision in laryngeal cancer patients.

Aberrant cellular retinol binding protein 1 (CRBP1) gene expression and promoter methylation in prostate cancer

AIMS

Retinoids are involved in cell growth, differentiation, and carcinogenesis. Their effects depend on cytosolic transport and binding to nuclear receptors. CRBP1 encodes a protein involved in this process. Because altered CRBP1 expression and promoter hypermethylation occur in several tumours, these changes were investigated in prostate tumorigenesis.

METHODS

The CRBP1 promoter was assessed by methylation specific polymerase chain reaction on tissue samples from 36 radical prostatectomy specimens (paired normal tissue, adenocarcinoma, and high grade prostatic intraepithelial neoplasia (HGPIN)), 32 benign prostatic hyperplasias (BPHs), and 13 normal prostate tissue samples from cystoprostatectomies. Methylation of DNA extracted from microdissected tissue was examined blindly. CRBP1 expression was assessed by immunohistochemistry on formalin fixed, paraffin wax embedded tissue.

RESULTS

Loss of CRBP1 expression was seen in 15 of 36 adenocarcinomas and 18 of 36 HGPINs. Fifteen adenocarcinomas and nine HGPINs showed overexpression, whereas the remainder showed normal expression. BPH displayed normal expression. No significant associations were found between CRBP1 expression and Gleason score or stage. CRBP1 promoter hypermethylation was found in 17 of 36 adenocarcinomas, three of 35 HGPINs, one of 36 normal prostate tissues from the same patients, none of 32 BPHs, and none of 13 normal prostate tissues from cystoprostatectomies. Loss of expression and hypermethylation of CRBP1 were not significantly associated.

CONCLUSIONS

Altered CRBP1 expression and hypermethylation are common in prostate carcinoma, although CRBP1 hypermethylation is not an early event in tumorigenesis. Moreover, both adenocarcinoma and HGPIN show frequent CRBP1 overexpression. The molecular mechanisms underlying altered CRBP1 expression in prostate cancer deserve further study.

HER2 polymorphism and breast cancer risk in Portugal

Breast cancer is a major public health problem around the world, and its carcinogenesis is not yet well understood. The human epidermal growth factor Receptor 2 (HER2) seems to play an important role in the development of this neoplasia, and genetic alterations in this gene, such as point mutations and polymorphisms have been detected in breast cancer patients. We analysed the frequency of a single nucleotide polymorphism in the HER2 gene in blood samples from 152 breast cancer patients and 146 healthy controls using the polymerase chain reaction methodology, followed by restriction fragment length polymorphism (PCR-RFLP). We found a twofold increase in risk of breast cancer in women who are carriers of a Val allele genotype-Ile/Val and Val/Val genotypes [odds ratio (OR)=2.00; 95% confidence interval (CI) 1.23-3.25; P=0.005]. Our results indicate an association between the presence of the Val allele in the HER2 polymorphism and the risk of breast cancer. Further studies are needed to evaluate the role of this polymorphism in the behaviour of breast cancer.

Food hypersensitivity in Portuguese adults

OBJECTIVE

To describe the frequency and epidemiological features of self-reported food hypersensitivity in Portuguese adults.

DESIGN

Cross-sectional.

SETTING

Participants were selected by random digit dialing among residents of Porto.

SUBJECTS

In total, 659 individuals over 39 y were asked to recall the occurrence of food hypersensitivity, and to describe the most serious episode. The adoption of eviction diets and previous medical diagnosis of food allergy were recorded, and recent dietary intake was evaluated using a validated food frequency questionnaire.

RESULTS

Self-reported food allergy was more frequent in women than men (7.3 vs 1.9%, P<0.01) and decreased with age. Age- and sex-standardized (European population > or =40 y) prevalence of food hypersensitivity was 4.8% (95% CI 3.4-6.9%). Most subjects (67.6%) referred allergy to a single food, fresh fruits being the more frequently incriminated (25%). Approximately 90% that reported food allergy declared the adoption of eviction diets, although 53% in fact ingested the incriminated foods during the previous year.

CONCLUSIONS

The adult prevalence of food hypersensitivity in Porto is one of the lowest observed worldwide, probably reflecting specificities of the genetic make-up and dietary patterns of our population.

Use of Helicobacter pylori-specific antibodies in the evaluation of intestinal metaplasia and gastric dysplasia

It is believed that Helicobacter pylori acts mainly during the initial phases of gastric carcinogenesis. Therefore, this study aims to assess the usefulness of H. pylori diagnosis in patients with chronic gastritis (CG), intestinal metaplasia (IM) and dysplasia--conditions that are associated with gastric cancer. A cross-sectional study of 94 patients was performed, which involved endoscopic biopsy and determination of specific serum anti-H. pylori antibodies (IgA, IgG and IgM) by enzyme-linked immunosorbent assay (ELISA). Biopsies were taken from the gastric antrum and corpus, and from endoscopic lesions. Two specimens per patient were used for bacterial culture. H. pylori infection status, used as the gold standard, was based on culture results. Validity measures were determined and receiver operating curve (ROC) was used to determine the best cut-off for serum antibody levels. Histopathological evaluation (n = 160) was performed independently by two pathologists. Lesions consistent with CG were found in 86 patients (91%), consistent with IM in 69 patients (73%) and with dysplasia in five patients (5%). In the 86 patients with CG, 38 (44%) were infected by H. pylori, as were 26 (38%) and one (20%) with IM and dysplasia, respectively (P=0.039). Area under the curve (AUC) was 0.40 (95% confidence interval [CI]: 0.28-0.51) for IgM, 0.69 (0.58-0.80) for IgA and 0.83 (0.74-0.92) for IgG for the diagnosis of H. pylori infection. Best cut-off was 41 u/mL for IgG, with a sensitivity (95% CI) of 90% (84-96%) and a negative predictive value (NPV) of 91% (85-97%). For IgA the results were 22 u/mL, 74% (65-83%) and 77% (68-86%), respectively. Prevalence of H. pylori appeared to decrease with increasing severity of the gastric lesion. In conclusion, it is suggested that non-invasive serological evaluation of anti-H. pylori (IgG) status after eradication therapy for peptic ulcer disease could be extended, after proper assessment of cut-off values and their validation, to the follow-up of patients with CG and IM.

Squamous cell carcinoma of the breast

Squamous carcinoma of the breast (SCB) is a rare entity. For its diagnosis, the exclusion of squamous cell carcinoma of local cutaneous structures and metastasis of distant squamous carcinoma are mandatory. The aim was to retrospectively evaluate the prevalence, epidemiological and clinical characteristics of the cases of SCB, studied in our institution, between January 1985 and December 1996. The diagnosis was histopathological. We studied the patients' demographic data and tumour characteristics. In the 11-year study period, 5791 patients with breast carcinoma were admitted to our Institution, seven (0.1%) of which were SCB. All seven patients were female and Caucasian. Their average age was 63 years (range 24-82). The presentation was always a breast lump. Five patients were in Stage II-A and two in Stage II-B. All tumours were hormone-receptor negative. The initial treatment was surgery and four patients received adjuvant radiotherapy. The median follow-up was 64 months. No relapses were diagnosed. SCB is a rare entity. The initial therapeutic approach should be surgical. There is still no consensus regarding adjuvant therapy. The prognosis of this type of breast cancer is still the subject of controversy with some series, including the present study, suggesting an indolent clinical course and a relatively good prognosis.

A follow up model for patients with atrophic chronic gastritis and intestinal metaplasia

AIM

To devise a follow up model for patients with gastric cancer associated lesions, such as atrophic chronic gastritis (ACG) and intestinal metaplasia (IM).

METHODS

Cohort study of 144 patients, followed for a minimum of one year, in whom at least two upper gastrointestinal endoscopic biopsies in flat gastric mucosa provided a diagnosis of ACG, IM, or low grade dysplasia (LGD).

RESULTS

Of those diagnosed with ACG at first endoscopic biopsy (entry biopsy), 12% progressed to LGD in outcome biopsy, as did 8% of those with type I IM, 38% with type II or III IM, and 32% with LGD. Type of IM at entry independently predicted progression to LGD and cancer. Type II and III IM had a higher rate of progression to LGD than type I IM, which showed an indolent behaviour similar to ACG. Patients with type II or III IM were at higher risk for development of dysplasia, and 7% of patients with type III IM at first biopsy progressed to high grade dysplasia (HGD), whereas no cases of ACG or type I/II IM progressed to HGD during the first three years.

CONCLUSION

Patients with ACG or IM could possibly be allocated to different management schedules, based on differences in rate and proportion of progression to LGD or HGD. Less intensive follow up (two/three yearly with "serological evaluation" (pepsinogen)) may suit those with ACG or type I IM. Patients with type III IM may benefit from six to 12 monthly improved endoscopic examination (magnification chromoendoscopy).

CYP1A1 and XRCC1 gene polymorphisms in SCC of the larynx

The present study was undertaken to examine CYP1A1 and XRCC1 polymorphisms as potential genetic susceptibility markers for laryngeal squamous cell carcinoma (SCC). Eighty-eight patients with laryngeal SCC and 178 randomly selected healthy blood donors from the same Caucasian population (Porto, Northern Portugal) were analysed for CYP1A1 (MspI and NcoI) and XRCC1 (Arg194Trp and Arg399Gln) polymorphisms, using PCR-RFLP techniques. CYP1A1 MspI MH (mutant homozygous) and CYP1A1 NcoI HT (heterozygous) genotypes were more frequent in patients than in controls, with those carrying a CYP1A1 NcoI HT genotype having a 2.3-fold higher risk for tumour development. On the other hand, polymorphisms in XRCC1 codon 399 and codon 194 do not seem to play a role in the aetiology of smoking-related laryngeal SCC, once its distribution was similar in both analysed groups. All the significant associations observed were exclusively due to differences between controls and larynx glottic cancer patient subgroup. Furthermore, lower lifetime tobacco consumption was observed in laryngeal SCC patients carrying the MspI and NcoI polymorphisms, than in those who did not show the polymorphic variants. This investigation seems to support the importance of CYP1A1 gene polymorphism as a potential genetic marker of laryngeal cancer development, specially concerning smokers who have inherited the at-risk genotypes CYP1A1 MspI MH or CYP1A1 NcoI HT, who do appear to be more susceptible to the development of SCC of the glottic larynx.

PAI-1 polymorphisms modulate phenotypes associated with the metabolic syndrome in obese and diabetic Caucasian population

AIM/HYPOTHESIS

Plasminogen activator inhibitor-1 (PAI-1) is a main regulator of the endogenous fibrinolytic system and modulates the thrombosis progression. We analyzed genetic contributions of PAI-1 mutations to the metabolic syndrome and to its complications.

METHODS

PAI-1 promoter and coding sequences were screened for mutations. Genotypes were determined for 1067 unrelated individuals of a French Caucasian cohort, selected for diabetes and obesity. Association between PAI-1 polymorphisms and phenotypes related to metabolic syndrome were statistically studied.

RESULTS

There were five variants identified: two common polymorphisms, -765 4G/5G and -844 A>G, in the promoter, and three new non-synonymous SNPs, Ala15Thr, Val17Ile and Asn195Ile. In obese non-diabetic subjects, the two promoter polymorphisms were associated with higher fasting glucose concentrations (p=0.006 and p=0.0004, for -765 4G/5G and -844 A>G, respectively) and insulin (p=0.05 and p=0.008, for -765 4G/5G and -844 A>G, respectively). Moreover, the -844 A>G SNP was associated with lower triglyceride (p=0.002) and higher HDL cholesterol concentrations (p=0.02) in lean subjects. In addition, the two promoter and Ala15Thr polymorphisms showed a trend towards association with CHD in diabetic subjects (-765 4G/5G: 0.56/0.51, p=0.05; -844 A>G: 0.63/0.57, p=0.02; Ala15Thr: 0.91/0.88, p=0.04). The SNPs Ala15Thr, located in the PAI-1 signal peptide, and rare the Asn195Ile, located in a beta-sheet structure, could influence conformation of these two structures.

CONCLUSIONS/INTERPRETATION

Our results support the hypothesis that PAI-1 polymorphisms probably interact with known environmental risk factors (chronic hyperglycaemia, obesity, etc.) to induce a more severe insulin-resistant metabolic profile in overweight subjects, and to further increase risk for CHD in diabetic subjects.