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Biomedical subjects

Pedro L Fernández

Publications and source records attributed to Pedro L Fernández.

10 recordsLinked to original sources
PubMed2007

Association of CDK4 and CCND1 mRNA overexpression in laryngeal squamous cell carcinomas occurs without CDK4 amplification.

CDK4 is involved in the control of G1-S phase transition as a part of the CCND1/CDK4 complexes. CCNDI and CDK4 gene alterations have been implicated in the development of different tumors. CCND1 has been associated with progression in laryngeal carcinomas. CDK4 protein overexpression was described associated to CCND 1 overexpression in these tumors. However, the mechanisms implicated were not known. We analyzed CDK4 gene alterations and mRNA expression in a series of carcinomas of the larynx, and the results were compared to CCND1 expression and clinicopathological characteristics of the patients. CDK4 mRNA was overexpressed in 42 out of 60 tumors (70%) associated with CCND1 mRNA overexpression because 15 out of 16 cases with high CCND1 levels showed simultaneous increased levels of CDK4 mRNA (p = 0.023) and 12 (87%) of the tumors overexpressing both genes were in stage 4. No CDK4 gene amplifications, rearrangements, or mutations were detected in any of the tumors, including 24 overexpressed cases. These findings confirm that CDK4 overexpression is a frequent phenomenon in laryngeal carcinomas, which occurs at the transcriptional level but is related neither to gene amplification nor to gene mutation, and suggest that cooperation with CCND1 may be involved in the progression of laryngeal tumors.

Cyclin D↗
PubMed2005

Paraffin-embedded cell line microarray (PECLIMA): development and validation of a high-throughput method for antigen profiling of cell lines.

The introduction of high-throughput techniques is increasingly providing abundant information on molecular alterations requiring validation at the posttranscriptional level. Protein expression is now efficiently evaluated in large series of tumors included in tissue microarrays. We propose, describe and validate a technique to elaborate paraffin-embedded cell line microarrays (PECLIMA) from fixed cell cultures, which can be processed like standard surgical pathology biopsies prior to immunophenotyping. Our results show a reliable protein immunoexpression profiling in six widely used cell lines under different fixation conditions. This technique permits the simultaneous analysis of multiple antigens in multiple cell lines under different experimental conditions. Additional features of these arrays are long-term storage, their suitability for a variety of techniques including immunocytochemistry and in situ hybridization and their low cost.

Antigens, Neoplasm↗
PubMed2004

Incidence of internal mammary node metastases after a sentinel lymph node technique in breast cancer and its implication in the radiotherapy plan.

PURPOSE: To analyze the frequency in determining pathologically proven metastatic involvement of internal mammary nodes (IMN) after sentinel lymph node (SLN) technique in breast cancer and to evaluate the implications for radiotherapy (RT) management of patients. METHODS AND MATERIALS: Two hundred and twenty-five patients who underwent lymphatic mapping for early breast cancer treated with breast-conserving surgery and radiation (80%) or mastectomy (20%) were evaluated. There were two phases in the study: the validation phase (105 patients, 52 T1, 53 T2 < or = 4 cm), and the application phase (120 patients, 70 T1, 50 T2 < or = 2.5 cm). In the validation, if a drainage pathway to the IMN was identified, no biopsy was performed in this phase. In the application, if the study showed metastases in the IMNs, biopsy was performed. When histologically proven IMN metastases were detected, RT was included on the IMN chain planned with a 3D treatment system using conformal techniques. At the beginning of the study the injection site was subdermal and subsequently, the injection site was changed to peritumoral and intratumoral to search for IMN. RESULTS: In 31 patients of 225 (14%) hot spots were observed in the internal mammary chain (11.5% and 17.2% in the validation and application phases, respectively). In the validation phase, in 11 cases (11.5%) IMN drainage was observed, and in the application phase, in 20 cases (17.2%). Sampling of the internal mammary basin based on lymphoscintigraphy results was successful in 69% of the cases (14 of 20) and revealed metastatic involvement in 14% (2 of 14). This represents incidence of only 1.7% (2 of 116) in early breast cancer patients with SLN study in the application phase. In both cases the axillary SLN was also positive. Both patients with metastatic involvement of the IMN area received RT on the IMN chain next to the remaining breast after conservative surgery. CONCLUSIONS: We can conclude that 14% of the patients with intraoperative drainage into the IMN surgical examination of the lymph nodes had pathologically positive metastases. The percentage in pathologically proven metastatic involvement of IMN after the SLN technique in early breast cancer is low, but it is not negligible. Moreover, it is expected to increase since the international recommendations have established a 3-cm cutoff for practicing the SLN technique. Although the real value of IMN irradiation in early breast cancer is not known, including this chain in postoperative radiotherapy is not recommended unless pathologically proven IMNs have been produced by the SLN technique. To avoid overdosage or underdosage in the joint between the medial tangential and IMN fields, an individualized 3D dosimetry study is mandatory to enhance dose distribution and reduce the heart volume to lessen side effects.

Axilla↗
PubMed2004

Alteration of the bioenergetic phenotype of mitochondria is a hallmark of breast, gastric, lung and oesophageal cancer.

Recent findings indicate that the expression of the beta-catalytic subunit of the mitochondrial H+-ATP synthase (beta-F1-ATPase) is depressed in liver, kidney and colon carcinomas, providing further a bioenergetic signature of cancer that is associated with patient survival. In the present study, we performed an analysis of mitochondrial and glycolytic protein markers in breast, gastric and prostate adenocarcinomas, and in squamous oesophageal and lung carcinomas. The expression of mitochondrial and glycolytic markers varied significantly in these carcinomas, when compared with paired normal tissues, with the exception of prostate cancer. Overall, the relative expression of beta-F1-ATPase was significantly reduced in breast and gastric adenocarcinomas, as well as in squamous oesophageal and lung carcinomas, strongly suggesting that alteration of the bioenergetic function of mitochondria is a hallmark of these types of cancer.

Adenocarcinoma↗
PubMed2003

PTOV-1, a novel protein overexpressed in prostate cancer, shuttles between the cytoplasm and the nucleus and promotes entry into the S phase of the cell division cycle.

PTOV1 was recently identified as a novel gene and protein during a differential display screening for genes overexpressed in prostate cancer. The PTOV1 protein consists of two novel protein domains arranged in tandem, without significant similarities to known protein motifs. By immunohistochemical analysis, we have found that PTOV1 is overexpressed in 71% of 38 prostate carcinomas and in 80% of samples with prostate intraepithelial neoplasia. High levels of PTOV1 in tumors correlated significantly with proliferative index, as assessed by Ki67 immunoreactivity, and associated with a nuclear localization of the protein, suggesting a functional relationship between PTOV1 overexpression, proliferative status, and nuclear localization. In quiescent cultured prostate tumor cells, PTOV1 localized to the cytoplasm, being excluded from nuclei. After serum stimulation, PTOV1 partially translocated to the nucleus at the beginning of the S phase. At the end of mitosis, PTOV1 exited the nucleus. Transient transfection of chimeric green fluorescent protein-PTOV1 forced the entry of cells into the S phase of the cell cycle, as shown by double fluorescent imaging for green fluorescent protein and for Ki67, and also by flow cytometry. This was accompanied by greatly increased levels of cyclin D1 protein in the transfected cells. These observations suggest that overexpression of PTOV1 can contribute to the proliferative status of prostate tumor cells and thus to their biological behavior.

Adenocarcinoma↗
PubMed2002

CHK2-decreased protein expression and infrequent genetic alterations mainly occur in aggressive types of non-Hodgkin lymphomas.

The CHK2 gene codifies for a serine/threonine kinase that plays a central role in DNA damage response pathways. To determine the potential role of CHK2 alterations in the pathogenesis of lymphoid neoplasms we have examined the gene status, protein, and mRNA expression in a series of tumors and nonneoplastic lymphoid samples. A heterozygous Ile157Thr substitution, also present in the germ line of the patient, was detected in a blastoid mantle cell lymphoma (MCL). CHK2 protein and mRNA expression levels were similar in all types of lymphomas and reactive samples, and these levels were independent of the proliferative activity of the tumors. However, 5 tumors, one typical MCL, 2 blastoid MCLs, and 2 large cell lymphomas, showed marked loss of protein expression, including 2 samples with complete absence of CHK2 protein. These 2 lymphomas showed the highest number of chromosomal imbalances detected by comparative genomic hybridization in the whole series of cases. However, no mutations, deletions, or hypermethylation of the promoter region were identified in any of these tumors. mRNA levels were similar in cases with low and normal protein expression, suggesting a posttranscriptional regulation of the protein in these tumors. CHK2 gene and protein alterations were not related to p53 and ATM gene status. In conclusion, CHK2 alterations are uncommon in malignant lymphomas but occur in a subset of aggressive tumors independently of p53 or ATM alterations. The high number of chromosomal imbalances in tumors with complete absence of CHK2 protein suggests a role of this gene in chromosomal instability in human lymphomas.

Amino Acid Substitution↗
PubMed2002

Study of catechin and xanthine tea profiles as geographical tracers.

The contents of gallic acid, epigallocatechin gallate, epigallocatechin, epicatechin, epicatechin gallate, catechin, caffeine, theophylline, and theobromine were determined in a set of 45 tea samples, including fermented (black and red) and nonfermented (green) teas of different geographical origins (i.e., China, Japan, Kenya, Sri Lanka, and India). A reversed-phase high performance liquid chromatographic method with gradient elution and photometric detection at 275 nm was used to carry out the analysis. Before the HPLC determination, an extraction step was developed using a mixture of acetonitrile and water (60:40, v/v). Pattern recognition techniques involving principal component analysis (PCA) and linear discriminant analysis (LDA) were applied to differentiate the tea samples according to their geographical origins. Catechins, gallic acid, and tea alkaloids are adequate chemical descriptors to distinguish between fermented and nonfermented tea samples cultivated in different geographical areas.

Caffeine↗
PubMed2002

ATM gene inactivation in mantle cell lymphoma mainly occurs by truncating mutations and missense mutations involving the phosphatidylinositol-3 kinase domain and is associated with increasing numbers of chromosomal imbalances.

The ataxia-telangiectasia mutated (ATM) gene codifies for a protein critically involved in the cellular response to DNA damage. ATM alterations have been observed in some sporadic lymphoproliferative disorders. The recurrent 11q22-23 deletions found in mantle cell lymphoma (MCL) suggest that ATM could be inactivated in these lymphomas. In this study, ATM gene alterations and protein expression were examined in 20 and 17 MCL tumor specimens, respectively. Previously, these patients had been examined for p53 and p14(ARF) gene status and analyzed by comparative genomic hybridization. Nine patients had 11q22-23 losses. Eight ATM gene mutations were detected in 7 patients. These alterations were 3 missense mutations in the phosphatidylinositol-3 kinase (PI-3K) domain and 5 truncating mutations, including 3 frameshifts, a nonsense mutation, and a substitution of the initial methionine. All truncating mutations were associated with lack of protein expression. Somatic origin was demonstrated in 3 mutations, whereas one mutation was carried heterozygously in the patient germ line. Chromosomal imbalances were significantly higher in typical MCL with ATM inactivation (7.8 +/- 1.3) than in tumors with the wild-type gene (3 +/- 1.1) (P =.001). Moreover, tumors with bi-allelic ATM alteration were associated with 3q gains (P =.015) and frequent extranodal involvement (P =.049). ATM gene alterations were not related to the histologic variant of the tumors, p53/p14(ARF) gene status, survival, or other clinicopathologic features of the patients. These findings indicate that ATM gene mutations in MCL are mainly truncating or missense mutations involving the PI-3K domain, and that may play a role in the pathogenesis of a subset of these tumors with increased numbers of chromosomal imbalances.

Alleles↗
PubMed2002

Alterations of cell cycle-regulatory genes in prostate cancer.

Deregulated proliferation is one of the main events in neoplastic transformation, and this has prompted increased attention being given to the understanding of the mechanisms involved in cell cycle regulation and its alterations. The 'retinoblastoma pathway', a key effector controlling G1-S phase transition, includes several oncogenes and tumour suppressor genes which display a wide range of abnormalities with potential usefulness as markers of evolution or treatment response in prostate cancer. Among these, the existence of p53 mutations seems to predict resistance to radiotherapy or systemic treatment, and p16 overexpression or p27 downregulation seems to serve as markers of poor evolution. The well-established existence of a critical hormonal role in prostate carcinogenesis coupled with the relationship of androgenic activity and regulation of several cell cycle modulators forces cell cycle control in the prostate to be envisioned as a highly complex steroid-influenced system, which will undoubtedly have critical implications in the future management of prostate cancer patients.

Carcinoma↗