Genetics and Molecular Biology
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Open Access journal
ISSN (Print) 1415-4757
Published by SciELO [727 journals]
- Comparison of multiple genotyping methods for the identification of the
cancer predisposing founder mutation p.R337H in TP53
Abstract: Abstract Germline mutations in the TP53 gene are associated with Li-Fraumeni and Li-Fraumeni-Like Syndromes, characterized by increased predisposition to early-onset cancers. In Brazil, the prevalence of the TP53-p.R337H germline mutation is exceedingly high in the general population and in cancer-affected patients, probably as result of a founder effect. Several genotyping methods are used for the molecular diagnosis of LFS/LFL, however Sanger sequencing is still considered the gold standard. We compared performance, cost and turnaround time of Sanger sequencing, PCR-RFLP, TaqMan-PCR and HRM in the p.R337H genotyping. The performance was determined by analysis of 95 genomic DNA samples and results were 100% concordant for all methods. Sequencing was the most expensive method followed by TaqMan-PCR, PCR-RFLP and HRM. The overall cost of HRM increased with the prevalence of positive samples, since confirmatory sequencing must be performed when a sample shows an abnormal melting profile, but remained lower than all other methods when the mutation prevalence was less than 2.5%. Sequencing had the highest throughput and the longest turnaround time, while TaqMan-PCR showed the lowest turnaround and hands-on times. All methodologies studied are suitable for the detection of p.R337H and the choice will depend on the application and clinical scenario.
- Cardanol: toxicogenetic assessment and its effects when combined with
Abstract: Abstract Cardanol is an effective antioxidant and is a compound with antimutagenic and antitumoral activity. Here, we evaluated the genotoxic and mutagenic potential of saturated side chain cardanol and its effects in combination with cyclophosphamide in preventing DNA damage, apoptosis, and immunomodulation. Swiss mice were treated with cardanol (2.5, 5 and 10 mg/kg) alone or in combination with cyclophosphamide (100 mg/kg). The results showed that cardanol is an effective chemopreventive compound, with damage reduction percentages that ranged from 18.9 to 31.76% in the comet assay and from 45 to 97% in the micronucleus assay. Moreover, cardanol has the ability to reduce the frequency of apoptosis induced by cyclophosphamide. The compound did not show immunomodulatory activity. A final interpretation of the data showed that, despite its chemoprotective capacity, cardanol has a tendency to induce DNA damage. Hence, caution is needed if this compound is used as a chemopreventive agent. Also, this compound is likely not suitable as an adjuvant in chemotherapy treatments that use cyclophosphamide.
- Mesenchymal stem cell therapy promotes the improvement and recovery of
renal function in a preclinical model
Abstract: Abstract Acute renal failure (ARF) is an extremely important public health issue in need of novel therapies. The present study aimed to evaluate the capacity of mesenchymal stem cell (MSC) therapy to promote the improvement and recovery of renal function in a preclinical model. Wistar rats were used as the experimental model, and our results show that cisplatin (5mg/kg) can efficiently induce ARF, as measured by changes in biochemical (urea and creatinine) and histological parameters. MSC therapy performed 24h after the administration of chemotherapy resulted in normalized plasma urea and creatinine levels 30 and 45d after the onset of kidney disease. Furthermore, MSC therapy significantly reduced histological changes (intratubular cast formation in protein overload nephropathy and tubular hydropic degeneration) in this ARF model. Thus, considering that current therapies for ARF are merely palliative and that MSC therapy can promote the improvement and recovery of renal function in this model system, we suggest that innovative/alternative therapies involving MSCs should be considered for clinical studies in humans to treat ARF.
- LNO3 AND L3 Are Associated With Antiproliferative And Pro-Apoptotic Action
In Hepatoma Cells
Abstract: Abstract The identification of antitumoral substances is the focus of intense biomedical research. Two structural analogues of thalidomide, LNO3 and L3, are two synthetic compounds that might possess such antitumor properties. We evaluated the toxicological effects of these substances, including cytotoxicity, genotoxicity and induction of apoptosis in HTC cells. Additionally, the production of free radicals (nitric oxide and superoxide) was investigated, and the expression of caspases genes 3, 8, and 9 were determined by RT-qPCR. The compounds exhibited cytotoxic effects that resulted in inhibited cell proliferation. LNO3 showed to be more effective and toxic than L3 in all assays. LNO3 stimulated the release of NO and superoxide, which was accompanied by the formation of peroxynitrite. Apoptosis was induced in a dose-dependent manner by both compounds; however, the expression of caspases 3, 8 and 9 was unchanged. These results suggested that L3 and LNO3 possess antiproliferative and pro-apoptotic effects in HTC cells. Additionally, although they exhibited cytotoxicity, L3 and LNO3 might be useful coadjuvants in tumor treatment studies.
- Early-onset breast cancer patients in the South and Southeast of Brazil
should be tested for the TP53 p.R337H mutation
Abstract: Abstract Germline TP53 mutations are associated with Li-Fraumeni syndrome (LFS), a disease that predisposes carriers to a wide variety of early onset tumors. In southern and southeastern Brazil, a high frequency of a germline TP53 mutation, p.R337H, was diagnosed in 0,3% of the population due to a founder effect. Carriers are at risk for developing cancer but the penetrance is lower than in typical DNA binding domain mutations. To date, only a few families were detected and diagnosis of carriers remains a challenge. Therefore, the inclusion of additional criteria to detect p.R337H carriers is necessary for the Brazilian population. We assessed the A.C. Camargo Cancer Center Oncogenetics Department database in search of common characteristics associated with p.R337H families that did not fulfill LFS/LFL clinical criteria. Among 42 p.R337H families, three did not meet any LFS/LFL criteria. All cases were young female patients with breast cancer diagnosed before age 45 and with no family history of LFS linked-cancers. Our results suggest that screening for the germline TP53 p.R337H mutation should be indicated, along with BRCA1 and BRCA2 genetic testing, for this group of patients, especially in the South and Southeast of Brazil.
- CDH1 mutations in gastric cancer patients from northern Brazil
identified by Next- Generation Sequencing (NGS)
Abstract: Abstract Gastric cancer is considered to be the fifth highest incident tumor worldwide and the third leading cause of cancer deaths. Developing regions report a higher number of sporadic cases, but there are only a few local studies related to hereditary cases of gastric cancer in Brazil to confirm this fact. CDH1 germline mutations have been described both in familial and sporadic cases, but there is only one recent molecular description of individuals from Brazil. In this study we performed Next Generation Sequencing (NGS) to assess CDH1 germline mutations in individuals who match the clinical criteria for Hereditary Diffuse Gastric Cancer (HDGC), or who exhibit very early diagnosis of gastric cancer. Among five probands we detected CDH1 germline mutations in two cases (40%). The mutation c.1023T > G was found in a HDGC family and the mutation c.1849G > A, which is nearly exclusive to African populations, was found in an early-onset case of gastric adenocarcinoma. The mutations described highlight the existence of gastric cancer cases caused by CDH1 germline mutations in northern Brazil, although such information is frequently ignored due to the existence of a large number of environmental factors locally. Our report represent the first CDH1 mutations in HDGC described from Brazil by an NGS platform.
- Hereditary cancer risk assessment: insights and perspectives for the
Next-Generation Sequencing era
Abstract: Abstract Hereditary cancer risk assessment is a multidisciplinary and dynamic process, with the purpose of estimating probabilities of germline mutations in cancer susceptibility genes and assessing empiric risks of cancer based on personal and family histories, in order to offer clinical and molecular diagnoses and clinical management based on these risks. Genetic tests are available and most of them are reimbursed by insurance companies, although they are generally not covered by the public health systems of developing countries. More recently, molecular diagnosis of hereditary cancer is feasible through next-generation sequencing (NGS) panels. Here we review the benefits and limitations of NGS technologies in the clinical practice.
- Antigenotoxicity and antimutagenicity of ethanolic extracts of Brazilian
green propolis and its main botanical source determined by the Allium
cepa test system
Abstract: Abstract Brazilian green propolis is a resinous substance prepared by bees from parts of the plant Baccharis dracunculifolia. As it possess several biological properties, this work assessed the cytotoxic/anticytotoxic, genotoxic/antigenotoxic and mutagenic/antimutagenic potential of ethanolic extracts of Brazilian green propolis (EEGP) and of B. dracunculifolia (EEBD), by means of the Allium cepa test system. The effects were evaluated by assessing the chromosomal aberrations (CA) and micronuclei (MN) frequencies on meristematic and F1 generation cells from onion roots. Chemical analyses performed with the extracts showed differences in flavonoid quality and quantity. No genotoxic or mutagenic potential was detected, and both extracts were capable of inhibiting cellular damage caused by methyl methanesulfonate (MMS) treatment, reducing the frequencies of CA and MN. By these data, we can infer that, independent of their flavonoid content, the extracts presented a protective effect in A. cepa cells against the clastogenicity of MMS.
- The lipidome, genotoxicity, hematotoxicity and antioxidant properties of
andiroba oil from the Brazilian Amazon
Abstract: Abstract Andirobeira is an Amazonian tree, the seeds of which produce a commercially valuable oil that is used in folk medicine and in the cosmetic industry. Andiroba oil contains components with anti-inflammatory, cicatrizing and insect-repellant actions. However, virtually nothing is known of the safety of this oil for humans. The aim of this work was therefore to investigate the hematotoxicity, genotoxicity and mutagenicity of andiroba oil using the comet and micronucleus assays, and to assess its antioxidant properties and lipidome as a means of addressing safety issues. For the experiments, andiroba oil was administered by gavage for 14 consecutive days in nulliparous female Swiss mice randomly distributed in four groups: negative control and three doses of oil (500, 1000 and 2000 mg/kg/day). These doses were chosen based on recommendations of the OECD guideline no. 474 (1997). GC/MS was used to investigate the free fatty acid, cholesterol and triterpene content of andiroba oil in a lipidomic analysis. No clinical or behavioral alterations were observed throughout the period of treatment, and exposure to andiroba oil at the doses and conditions used here did not result in hematotoxic, genotoxic or mutagenic effects. Tests in vitro showed that oil sample 3 from southwestern of Brazilian Amazon had a high antioxidant capacity that may protect biological systems from oxidative stress, although this activity remains to be demonstrated in vivo.
- Screening for germline BRCA1, BRCA2, TP53 and
CHEK2 mutations in families at-risk for hereditary breast cancer
identified in a population-based study from Southern Brazil
Abstract: Abstract In Brazil, breast cancer is a public health care problem due to its high incidence and mortality rates. In this study, we investigated the prevalence of hereditary breast cancer syndromes (HBCS) in a population-based cohort in Brazils southernmost capital, Porto Alegre. All participants answered a questionnaire about family history (FH) of breast, ovarian and colorectal cancer and those with a positive FH were invited for genetic cancer risk assessment (GCRA). If pedigree analysis was suggestive of HBCS, genetic testing of the BRCA1, BRCA2, TP53, and CHEK2 genes was offered. Of 902 women submitted to GCRA, 214 had pedigrees suggestive of HBCS. Fifty of them underwent genetic testing: 18 and 40 for BRCA1/BRCA2 and TP53 mutation screening, respectively, and 7 for CHEK2 1100delC testing. A deleterious BRCA2 mutation was identified in one of the HBOC probands and the CHEK2 1100delC mutation occurred in one of the HBCC families. No deleterious germline alterations were identified in BRCA1 or TP53. Although strict inclusion criteria and a comprehensive testing approach were used, the suspected genetic risk in these families remains unexplained. Further studies in a larger cohort are necessary to better understand the genetic component of hereditary breast cancer in Southern Brazil.
- BRCA1 and BRCA2 rearrangements in Brazilian individuals
with Hereditary Breast and Ovarian Cancer Syndrome
Abstract: Abstract Approximately 5-10% of breast cancers are caused by germline mutations in high penetrance predisposition genes. Among these, BRCA1 and BRCA2, which are associated with the Hereditary Breast and Ovarian Cancer (HBOC) syndrome, are the most frequently affected genes. Recent studies confirm that gene rearrangements, especially in BRCA1, are responsible for a significant proportion of mutations in certain populations. In this study we determined the prevalence of BRCA rearrangements in 145 unrelated Brazilian individuals at risk for HBOC syndrome who had not been previously tested for BRCA mutations. Using Multiplex Ligation-dependent Probe Amplification (MLPA) and a specific PCR-based protocol to identify a Portuguese founder BRCA2 mutation, we identified two (1,4%) individuals with germline BRCA1 rearrangements (c.547+240_5193+178del and c.4675+467_5075-990del) and three probands with the c.156_157insAlu founder BRCA2 rearrangement. Furthermore, two families with false positive MLPA results were shown to carry a deleterious point mutation at the probe binding site. This study comprises the largest Brazilian series of HBOC families tested for BRCA1 and BRCA2 rearrangements to date and includes patients from three regions of the country. The overall observed rearrangement frequency of 3.44% indicates that rearrangements are relatively uncommon in the admixed population of Brazil.
- Proteomic analysis of halotolerant proteins under high and low salt stress
in Dunaliella salina using two-dimensional differential in-gel
Abstract: Abstract Dunaliella salina, a single-celled marine alga with extreme salt tolerance, is an important model organism for studying fundamental extremophile survival mechanisms and their potential practical applications. In this study, two-dimensional differential in-gel electrophoresis (2D-DIGE) was used to investigate the expression of halotolerant proteins under high (3 M NaCl) and low (0.75 M NaCl) salt concentrations. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/TOF MS) and bioinformatics were used to identify and characterize the differences among proteins. 2D-DIGE analysis revealed 141 protein spots that were significantly differentially expressed between the two salinities. Twenty-four differentially expressed protein spots were successfully identified by MALDI-TOF/TOF MS, including proteins in the following important categories: molecular chaperones, proteins involved in photosynthesis, proteins involved in respiration and proteins involved in amino acid synthesis. Expression levels of these proteins changed in response to the stress conditions, which suggests that they may be involved in the maintenance of intracellular osmotic pressure, cellular stress responses, physiological changes in metabolism, continuation of photosynthetic activity and other aspects of salt stress. The findings of this study enhance our understanding of the function and mechanisms of various proteins in salt stress.
- The Brazilian Hereditary Cancer Network: historical aspects and challenges
for clinical cancer genetics in the public health care system in Brazil
- The Development of the Study of Hereditary Cancer in South America
- Oncogenetics service and the Brazilian public health system: the
experience of a reference Cancer Hospital
Abstract: Abstract The identification of families at-risk for hereditary cancer is extremely important due to the prevention potential in those families. However, the number of Brazilian genetic services providing oncogenetic care is extremely low for the continental dimension of the country and its population. Therefore, at-risk patients do not receive appropriate assistance. This report describes the creation, structure and management of a cancer genetics service in a reference center for cancer prevention and treatment, the Barretos Cancer Hospital (BCH). The Oncogenetics Department (OD) of BCH offers, free of charge, to all patients/relatives with clinical criteria, the possibility to perform i) genetic counseling, ii) preventive examinations and iii) genetic testing with the best quality standards. The OD has a multidisciplinary team and is integrated with all specialties. The genetic counseling process consists (mostly) of two visits. In 2014, 614 individuals (371 families) were seen by the OD. To date, over 800 families were referred by the OD for genetic testing. The support provided by the Oncogenetics team is crucial to identify at-risk individuals and to develop preventive and personalized behaviors for each situation, not only to the upper-middle class population, but also to the people whose only possibility is the public health system.
- Self-reported cancer family history is a useful tool for identification of
individuals at risk of hereditary cancer predisposition syndrome at
primary care centers in middle-income settings: a longitudinal study
Abstract: Abstract Analysis of cancer family history (CFH) offers a low-cost genetic tool to identify familial cancer predisposition. In middle-income settings, the scarcity of individual records and database-linked records hinders the assessment of self-reported CFH consistency as an indicator of familial cancer predisposition. We used self-reported CFH to identify those families at risk for hereditary cancer syndromes in community-based primary care centers of a low-income Brazilian area. We also evaluated the consistency of the information collected by reassessing CFH five years later. We interviewed 390 families and constructed their pedigrees for genetic cancer risk assessment. We found 125 families affected by cancer, 35.2% with moderate to high risk of familial susceptibility to cancer, a number that represents a relatively high prevalence of potential hereditary cancer syndromes in the overall study sample. Upon reassessment of CFH in 14/20 families that were previously identified as having at least one first-degree and one second-degree relative affected by cancer, and presented moderate to high risk for developing cancer, 90% of initial pedigrees were confirmed. These results demonstrate the reliability of self-reports as a means of early identification of healthy individuals at risk, encouraging the wider use of this method in low- and middle-income primary care settings.
- Prevalence of Café-au-Lait Spots in children with solid tumors
Abstract: Abstract Cafe-au-lait maculae (CALM) are frequently observed in humans, and usually are present as a solitary spot. Multiple CALMs are present in a smaller fraction of the population and are usually associated with other congenital anomalies as part of many syndromes. Most of these syndromes carry an increased risk of cancer development. Previous studies have indicated that minor congenital anomalies may be more prevalent in children with cancer. We investigated the prevalence of CALMs in two samples of Brazilian patients with childhood solid tumors, totaling 307 individuals. Additionally, 176 school children without diagnosis of cancer, or of a cancer predisposing syndrome, were investigated for the presence of CALMs. The prevalence of solitary CALM was similar in both study groups (18% and 19%) and also in the group of children without cancer. Multiple CALMs were more frequently observed in one of the study groups (Z = 2.1). However, when both groups were analyzed together, the significance disappeared (Z = 1.5). The additional morphological abnormalities in children with multiple CALMs were analyzed and compared to the findings observed in the literature. The nosologic entities associated with CALMs are reviewed.