Biomedical subjects

Xavier Matias-Guiu

Publications and source records attributed to Xavier Matias-Guiu.

At least 19 recordsLinked to original sources

PubMed2026

Tracing the molecular route to progression in miRNA-biogenesis-defective thyroid lesions.

Germline and somatic changes in DICER1 and DGCR8 microprocessors confer risk of developing benign and malignant thyroid lesions, yet the molecular events driving malignant transformation remain unclear. We trace the molecular trajectories from benignity to malignancy in DICER1- and DGCR8-mutated thyroid lesions using multiomic profiling on over 30 DICER1-/DGCR8-mutated samples. Our findings reveal a progressive, specific, and linear accumulation of genetic changes, which when combined with enhanced downregulation of miRNAs distinguished DICER1-/DGCR8-malignant lesions from their benign counterparts. Compensatory hypomethylation of miRNA-encoding genes characterized DICER1-/DGCR8-benign lesions, but as the tumors progressed to malignancy, methylation was partly reimposed, reversing the attempts to activate miRNA-encoded genes and further compromising miRNA production. Transcriptomic analyses revealed mutation-specific effects on the microenvironment, whereby DICER1 mutations activated canonical thyroid cancer progression pathways, whereas altered DGCR8 associated with immune-related changes. This work unveils specific molecular events underlying malignant progression of miRNA-biogenesis-related thyroid tumors and identifies potential biomarkers and disease etiology mechanisms.

MicroRNAs↗

PubMed2024

Tumor specimen cold ischemia time impacts molecular cancer drug target discovery.

Tumor tissue collections are used to uncover pathways associated with disease outcomes that can also serve as targets for cancer treatment, ideally by comparing the molecular properties of cancer tissues to matching normal tissues. The quality of such collections determines the value of the data and information generated from their analyses including expression and modifications of nucleic acids and proteins. These biomolecules are dysregulated upon ischemia and decompose once the living cells start to decay into inanimate matter. Therefore, ischemia time before final tissue preservation is the most important determinant of the quality of a tissue collection. Here we show the impact of ischemia time on tumor and matching adjacent normal tissue samples for mRNAs in 1664, proteins in 1818, and phosphosites in 1800 cases (tumor and matching normal samples) of four solid tumor types (CRC, HCC, LUAD, and LUSC NSCLC subtypes). In CRC, ischemia times exceeding 15 min impacted 12.5% (mRNA), 25% (protein), and 50% (phosphosites) of differentially expressed molecules in tumor versus normal tissues. This hypoxia- and decay-induced dysregulation increased with longer ischemia times and was observed across tumor types. Interestingly, the proteomics analysis revealed that specimen ischemia time above 15 min is mostly associated with a dysregulation of proteins in the immune-response pathway and less so with metabolic processes. We conclude that ischemia time is a crucial quality parameter for tissue collections used for target discovery and validation in cancer research.

Humans↗

PubMed2006

PIK3CA gene mutations in endometrial carcinoma: correlation with PTEN and K-RAS alterations.

Alterations in the phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathway are common in endometrial carcinoma. Inactivation of the tumor suppressor gene PTEN leads to a constitutively active PI3K pathway, which plays a role in the early steps of endometrial tumorigenesis. Other alterations in the PI3K/AKT pathway are mutations in the PIK3CA gene, which encode the p110alpha catalytic subunit of PI3K. PIK3CA mutations cluster to the helical (exon 9) and the kinase (exon 20) domains of the gene. In endometrial carcinomas, PIK3CA mutations have been found to coexist frequently with PTEN mutations, but it is not clear whether they occur in cells with monoallelic or biallelic inactivation of PTEN. In the present study we have evaluated PIK3CA mutational status in a series of 33 endometrial carcinomas, previously screened for microsatellite instability and mutations in PTEN, K-RAS, and CTNNB-1. The tumors were also evaluated for loss of heterozygosity on 10q23 and hypermethylation of the promoter region of PTEN/psiPTEN to assess the monoallelic or biallelic inactivation status of PTEN. PIK3CA mutations were detected in 8 (24%) of the 33 cases. Seven mutations were located in exon 20 and 1 in exon 9. PTEN alterations were found in 19 cases (57%). Biallelic inactivation of PTEN was demonstrated in 11 tumors, whereas 8 tumors exhibited alteration in only 1 of the 2 alleles. PIK3CA mutations coexisted with monoallelic alterations of PTEN in 4 cases (2 mutations and 2 allelic imbalances), with biallelic PTEN inactivation in 1 case (mutation and promoter methylation), and 3 tumors showed PIK3CA mutations in association with wild-type PTEN. PIK3CA mutations did not correlate with microsatellite instability or mutations in CTNNB-1. However, PIK3CA and K-RAS mutations (8 cases) were mutually exclusive alterations. In summary, the results confirm that PIK3CA mutations are frequent in endometrial carcinoma and support the hypothesis that PIK3CA mutations may have an additive effect to PTEN monoallelic inactivation in endometrial carcinoma.

Class I Phosphatidylinositol 3-Kinases↗

PubMed2006

Proteasome inhibitors induce death but activate NF-kappaB on endometrial carcinoma cell lines and primary culture explants.

Proteasome inhibitors are currently used as chemotherapeutic drugs because of their ability to block NF-kappaB, a transcription factor constitutively activated in many different types of human cancer. In the present study, we demonstrate that proteasome inhibitors induce cell death in endometrial carcinoma cell lines and primary explants but, instead of blocking NF-kappaB, they increase its transcriptional activity. Proteasome inhibitors induce phosphorylation of IKK alpha/beta, phosphorylation and degradation of IkappaB alpha, and phosphorylation of the p65 NF-kappaB subunit on serine 536. Proteasome inhibitor-induced NF-kappaB activity can be blocked by a non-degradable form of IkappaB alpha or dominant negative forms of either IKK alpha or IKK beta. Lentiviral delivery of shRNAs to either IKK alpha or IKK beta cause blockade of NF-kappaB transcriptional activity and inhibit phosphorylation of p65 on serine 536, but has no effect on IkappaB alpha degradation. These results suggest a role for p65 phosphorylation in proteasome inhibitor-induced NF-kappaB activation. Accordingly, siRNA knockdown of p65 inhibits proteasome inhibitor-induced NF-kappaB transcriptional activity. Our results demonstrate that proteasome inhibitors, including bortezomib, induce cell death on endometrial carcinoma cells and primary explants. However, they activate NF-kappaB instead of blocking its transcriptional potential. Therefore, the concept that proteasome inhibitors are blockers of NF-kappaB activation should be carefully examined in particular cell types.

Antineoplastic Agents↗

PubMed2006

PTEN promoter methylation in sporadic thyroid carcinomas.

The tumor-suppressor gene PTEN/MMAC1, on chromosome 10q23.3, has been implicated in an important number of human tumors, such as thyroid carcinomas. PTEN somatic mutations occur in sporadic tumors of the endometrium, brain, prostate, or melanomas, while germline mutations predispose to development of the multiple hamartoma syndromes (i.e., Cowden's disease and Bannayan-Zonana syndrome). Activation of the two alleles of PTEN is required for its tumor-suppression role. Because the frequency of PTEN suppression in thyroid tumors exceeds that of PTEN mutations or deletions, it is very likely that epigenetic mechanisms, such as promoter hypermethylation, may account for its inactivation in a subset of tumors. The main aim of this study was to assess the frequency of promoter hypermethylation of PTEN in thyroid tumors. We studied frozen tissue samples from 46 papillary carcinomas, 7 follicular carcinomas, 6 follicular adenomas as well as 39 normal thyroid tissue samples. Methylation-specific polymerase-chain reaction (PCR) with three different sets of primers was used. Two of the primer sets were designed to avoid any interference with PTEN pseudogene promoter. PTEN promoter hypermethylation was detected in 21 of 46 (45.7%) papillary carcinomas, 6 of 7 follicular carcinomas, and 5 of 6 follicular adenomas. It was negative in all normal tissues. Negative immunohistochemical staining for PTEN was significantly associated with the presence of promoter hypermethylation (p < 0.001). These results show a high frequency of PTEN promoter hypermethylation, especially in follicular tumors, suggesting its possible role in thyroid tumorigenesis.

Adenoma↗

PubMed2006

Antiproliferative effect of STI571 on cultured human cutaneous melanoma-derived cell lines.

Standard antineoplastic treatment for metastatic melanoma is ineffective in the large majority of patients. Therefore, alternative approaches need to be investigated. STI571 is a new antineoplastic compound, which selectively inhibits the tyrosine kinase activity of ABL, c-Kit and platelet-derived growth factor receptor (PDGFR). Melanoma may express all of these proteins. The aim of this study was to investigate whether STI571 inhibits the in-vitro growth of melanoma cells. Nineteen cell lines were obtained from four primary and 15 metastatic melanomas of cutaneous origin. The percentages of positive cells for the putative targets of STI571 were as follows: ABL, 41-100%; c-Kit, 8-97%; PDGFR-alpha, 41-98%; PDGFR-beta, 51-99%. 3-(4,5-Dimethylthiazol-yl)-2,5-diphenyltetrazolium (MTT) and viability assays showed that STI571 clearly inhibits the proliferation of eight of the 19 (42.1%) cell lines. No relationship could be established between the expression of c-Kit, ABL, PDGFR-alpha or PDGFR-beta and the response of cell lines to STI571. Our study shows, for the first time, an antiproliferative effect of STI571 on human melanoma cell lines of cutaneous origin, raising the possibility of the future clinical use of STI571. The identification of the target of STI571 in human cutaneous melanoma cells would allow the selection of patients who could benefit from this treatment.

Antineoplastic Agents↗

PubMed2005

NF-kB in development and progression of human cancer.

The nuclear factor kB (NF-kB) comprises a family of transcription factors involved in the regulation of a wide variety of biological responses. NF-kB plays a well-known function in the regulation of immune responses and inflammation, but growing evidences support a major role in oncogenesis. NF-kB regulates the expression of genes involved in many processes that play a key role in the development and progression of cancer such as proliferation, migration and apoptosis. Aberrant or constitutive NF-kB activation has been detected in many human malignancies. In recent years, numerous studies have focused on elucidating the functional consequences of NF-kB activation as well as its signaling mechanisms. NF-kB has turned out to be an interesting therapeutic target for treatment of cancer.

Apoptosis↗

PubMed2005

Synchronous endometrioid carcinomas of the uterine corpus and ovary: alterations in the beta-catenin (CTNNB1) pathway are associated with independent primary tumors and favorable prognosis.

Diagnosis of synchronous endometrioid carcinomas of the uterine corpus and ovary as either separate independent primary or as metastatic tumors requires careful consideration of a number of gross and histological features. Although such assessment is often sufficient, recent evidence has suggested that molecular analysis may facilitate the diagnosis in problematic cases. Furthermore, as independent synchronous tumors limited to the uterus and ovary are generally associated with favorable outcome, determination of genetic alterations associated with this group of neoplasms may indicate molecular markers of less aggressive behavior. We examined 12 cases of synchronous carcinomas of the uterus and ovary, correlating conventional gross and histological parameters with molecular genetic alterations common to single endometrioid carcinomas occurring in these sites. We identified a frequency of molecular alterations in both independent and metastatic tumors, including microsatellite instability (uterine tumors, 50% and 67%, respectively; ovarian tumors, 33% and 67%) and PTEN mutations (uterine tumors, 38% and 100%; ovarian tumors, 33% and 83%) that is higher than that observed in single sporadic tumors. Loss of heterozygosity for chromosome 17p and 10q was also frequently observed. Nuclear immunoreactivities for beta -catenin and CTNNB1 mutations were restricted to independent uterine and ovarian tumors and were absent in all of the metastatic tumors, providing direct evidence for a divergence of molecular oncogenetic mechanisms in the subset of synchronous endometrioid carcinomas. Furthermore, our data show that molecular genetic classification of synchronous independent versus metastatic tumors based on beta -catenin expression/mutation correlates with clinical outcome.

Adult↗

PubMed2005

FLIP is frequently expressed in endometrial carcinoma and has a role in resistance to TRAIL-induced apoptosis.

The FLICE-inhibitory protein (FLIP) plays a key role in the regulation of apoptosis triggered by death ligands. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has been shown to induce apoptosis in some types of tumor but not in others. To assess the possible role of FLIP in apoptosis resistance in endometrial carcinoma, we performed an immunohistochemical study on a tissue microarray composed of 95 endometrial carcinomas. We found positive signals in 43% of the cases, as well as a significant difference in FLIP expression between stage I and II tumors. Moreover, we observed that endometrial carcinoma cell lines Ishikawa and KLE did not undergo apoptosis after TRAIL treatment. Cotreatment of these cells with the inhibitor of transcription actinomycin D resulted in a dramatic decrease in cell viability and induced activation of caspase-8. These events coincided with downregulation of FLIP mRNA and protein. Inhibitors of caspase-8 or overexpression of FLIP completely blocked apoptosis induced by actinomycin D plus TRAIL cotreatment. More importantly, downregulation of endogenous FLIP expression by specific siRNAs sensitized endometrial carcinoma cells to TRAIL-induced apoptosis in the absence of actinomycin D. Taken together, our results suggest for the first time a critical role for FLIP in the regulation apoptosis triggered by TRAIL in endometrial carcinoma cells.

Adenocarcinoma↗

PubMed2005

Immunohistochemical analysis of PTEN in endometrial carcinoma: a tissue microarray study with a comparison of four commercial antibodies in correlation with molecular abnormalities.

The tumor suppressor gene PTEN/MMAC1 is located on chromosome 10q23.3. Inactivation of PTEN, either by mutations, deletions, or promoter hypermethylation, has been identified in a wide variety of tumors. Inactivation of the two alleles of PTEN is required, because it is a tumor suppressor gene. Immunohistochemical staining may be an effective screening method to demonstrate the absence of the protein in tumors exhibiting PTEN inactivation. We studied a tissue microarray, constructed from paraffin-embedded blocks of 95 endometrial carcinomas, 38 of them previously evaluated for alterations in PTEN. We also studied cell blocks obtained from one PTEN-defective endometrial cancer cell line, after transfection with either a plasmid encoding wild-type PTEN or the empty vector. The tumor samples were tested with four different anti-PTEN commercial antibodies: a polyclonal antibody, the monoclonal antibody 28H6, the monoclonal antibody 10P03, and the monoclonal antibody 6.H2.1. Results were correlated with the presence of abnormalities in PTEN, as well as with the immunohistochemical expression of phosphorylated AKT. Antibody 28H6 produced a predominant nuclear staining, while the other three antibodies produced a predominant cytoplasmic staining. There was no significant correlation between the results obtained with the four antibodies. The monoclonal antibody 6.H2.1 was the only one that exhibited a correlation with the presence of molecular alterations in PTEN, and a statistically significant association with immunostaining for phosphorylated AKT (r=-0.249, P=0.037). The monoclonal antibody 10P03 exhibited an association with phospho-AKT that did not have statistical significance. Both 6.H2.1 and 10P03 antibodies stained PTEN-transfected cells, and were negative in the PTEN-deficient cell line blocks. The polyclonal antibody and the monoclonal antibody 28H6 produced positive staining in PTEN-deficient cell line blocks, suggesting nonspecific staining. The results indicate that monoclonal antibody 6.H2.1 may be a suitable alternative for tumors with inactivation of PTEN.

Antibodies, Monoclonal↗

PubMed2005

Mutation analysis of the SDHD gene in four kindreds with familial paraganglioma: description of one novel germline mutation.

The familial paraganglioma syndrome is an autosomal dominant disorder characterized by the presence of carotid body paragangliomas and, less frequently, paragangliomas of the glomus jugulare, glomus vagale, and adrenal pheochromocytomas. Germline mutations of the genes for succinate dehydrogenase subunits D, B, or C (SDHD, SDHB, SDHC) have been identified in some kindreds with familial paraganglioma. In this study, we report the clinicopathologic features of four different kindreds with familial paraganglioma, which were screened for germline mutations in the SDHD gene. DNA was obtained from tumor and normal tissue, as well as from peripheral blood. Mutation analysis was performed by single-strand conformation polymorphism analysis and DNA sequencing. SDHD germline mutations were detected in the affected family members of the four families, as well as in several asymptomatic carriers. An identical mutation in exon 4 of SDHD (334-337delACTG) was identified in two apparently unrelated kindreds. The third family showed a germline mutation in exon 2 (W43X). The mutations present in these three families had been previously described in Spanish families, suggesting a founder effect. The fourth family exhibited a mutation in exon 2 of SDHD (170-171delTT), which had not been previously identified. The affected family members of the four kindreds showed paragangliomas, located in the head and neck region, and all of them were benign. These results confirm that genetic testing of SDHD may be a powerful tool for the identification of the syndrome in patients with multiple or bilateral paragangliomas.

DNA Mutational Analysis↗

PubMed2005

Survivin expression in endometrial carcinoma: a tissue microarray study with correlation with PTEN and STAT-3.

Evasion of apoptotic cell death plays a key role in cancer development. Survivin is a member of the inhibitor of apoptosis proteins, which also has a role in the control of cell division. Survivin may be overexpressed in some tumors and has been suggested to be related to PTEN, beta-catenin, p53 [all of them frequently abnormal in endometrial carcinomas (ECs)], and STAT-3. A tissue microarray was constructed from paraffin-embedded blocks of 95 ECs, previously studied for microsatellite instability and for alterations in PTEN, k-RAS, and CTNNB-1. Immunohistochemical evaluation included 1) survivin, 2) markers of cell proliferation and apoptosis (Ki67-MIB1 and M 30-neoepitope cytokeratin 18), and 3) proteins involved in cell signaling pathways (PTEN, phospho-AKT, beta-catenin, p53, and STAT-3). Survivin expression was frequent in ECs (75.95%) but did not show any statistical significant correlation with histological type and grade, stage, overall survival, or mitotic and apoptotic indexes. Survivin expression had a statistical significant correlation with decreased PTEN expression (r = -0.383, p = 0.001), increased phospho-AKT (r = 0.70, p < 0.001), and positive STAT-3 immunostaining (r = 0.6, p < 0.001). Survivin expression did not show statistical correlation with either beta-catenin or p53 alterations. The results suggest that increased survivin expression is frequent in ECs and may be dependent on STAT-3 and PI3 K/AKT activation. Because PTEN abnormalities are very frequent in ECs, the results from this study indicate that PTEN may interfere with the process of apoptosis and cell proliferation by promoting survivin expression.

Apoptosis↗

PubMed2004

Abnormalities in the NF-kappaB family and related proteins in endometrial carcinoma.

The NF-kappaB family of transcription factors regulates a wide variety of cellular processes including cell growth, differentiation, and apoptosis. A tissue microarray was constructed from paraffin wax-embedded blocks from 95 endometrial carcinomas (EC), previously studied for microsatellite instability, as well as for alterations in PTEN, k-RAS and beta-catenin. Immunohistochemical evaluation included members of the NF-kappaB (p50, p65, p52, c-Rel, Rel-B) and the IkappaB (IkappaBalpha, IkappaBbeta, IkappaBepsilon, Bcl-3) families, as well as putative targets of NF-kappaB such as Flip, Bcl-xL, Cyclin D1, and oestrogen and progesterone receptors. Results were correlated with the clinical and pathological data. Nuclear immunostaining for members of the NF-kappaB family was frequent in EC (p50, 20%; p65, 16.5-21.9%; p52, 9.3%; c-Rel, 48.9%; Rel-B, 15.7%); and it correlated with negativity for members of the IkappaB family in some cases. There was a statistically significant association between immunoreaction for p50 and p65 (p = 0.006), suggesting activation of the so-called 'classic form' of NF-kappaB, similar to that described in breast cancer. Bcl-3 nuclear immunostaining was detected in 60.7% of cases. The vast majority of p52-positive tumours showed Bcl-3 nuclear immunoreaction (p = 0.038). Immunostaining for putative targets of NF-kappaB was as follows: Bcl-xL, 76.2% (p = 0.001); Flip 43.0%; Cyclin D1, 64.79%. p65 immunostaining correlated with increased immunoreaction for steroid hormone receptors. No correlation was found between NF-kappaB nuclear pattern and the presence of microsatellite instability, or alterations in PTEN, k-RAS, or beta-catenin. These results suggest that the NF-kappaB and IkappaB families of genes may be important in endometrial carcinogenesis, by controlling apoptosis and cell proliferation.

Adenocarcinoma↗

PubMed2004

Malignant peripheral nerve sheath tumor of the thyroid: a clinicopathological and ultrastructural study of one case.

Thyroid malignant peripheral nerve sheath tumors (TMPNST) are very uncommon neoplasms that can be confused with anaplastic carcinoma, Riedel's thyroiditis, or other soft tissue tumors that may occur in the thyroid region. An example of TMPNST is presented in this report. The tumor occurred in a 56-yr-old woman. Fine needle aspiration did not provide adequate material. After thyroidectomy, the lesion posed important problems in differential diagnosis. Immunohistochemical, molecular, and electron microscopic features were taken into consideration to arrive at the correct diagnosis. Tumor cells were focally positive for keratins, a feature that has not been described in peripheral nerve sheath tumors of the thyroid, but that has been occasionally seen in tumors from other locations. After thyroidectomy, the patient received radiotherapy. She is well without evidence of recurrence 10 mo after surgery.

Diagnosis, Differential↗

PubMed2003

Differential gene expression profile in endometrioid and nonendometrioid endometrial carcinoma: STK15 is frequently overexpressed and amplified in nonendometrioid carcinomas.

Endometrial carcinoma (EC) comprises at least two types of cancer: endometrioid carcinomas (EECs) are estrogen-related tumors, which are frequently euploid and have a good prognosis. Nonendometrioid carcinomas (NEECs; serous and clear cell forms) are not estrogen related, are frequently aneuploid, and are clinically aggressive. We used cDNA microarrays containing 6386 different genes to analyze gene expression profiles in 24 EECs and 11 NEECs to identify differentially expressed genes that could help us to understand differences in the biology and clinical outcome between histotypes. After supervised analysis of the microarray data, there was at least a 2-fold difference in expression between EEC and NEEC in 66 genes. The 31 genes up-regulated in EECs included genes known to be hormonally regulated during the menstrual cycle and to be important in endometrial homeostasis, such as MGB2, LTF, END1, and MMP11, supporting the notion that EEC is a hormone-related neoplasm. Conversely, of the 35 genes overexpressed in NEECs, three genes, STK15, BUB1, and CCNB2, are involved in the regulation of the mitotic spindle checkpoint. Because STK15 amplification/overexpression is associated with aneuploidy and an aggressive phenotype in other human tumors, we used fluorescence in situ hybridization to investigate whether STK15 amplification occurred in ECs. We found that STK15 was amplified in 55.5% of NEECs but not in any EECs (P <or= 0.001). We confirmed this result in an independent series of ECs included in a tissue microarray in which breast and ovarian cancer samples showed an incidence of STK15 amplification of 15 and 18%, respectively (P <or= 0.001). This study demonstrated the usefulness of cDNA microarray technology for identifying differences in gene expression patterns between histological types of EC and implies that alteration of the mitotic checkpoint is a major mechanism of carcinogenesis in NEECs.

Aurora Kinase A↗

PubMed2003

Cyclin D1 gene (CCND1) mutations in endometrial cancer.

Cyclin D1 is frequently overexpressed in human neoplasias by gene rearrangement and amplification, but no mutations in the CCND1 gene have so far been reported. However, in vitro mutagenesis of CCND1 has shown that substitutions affecting threonine 286 residue produced cyclin D1 nuclear accumulation, by interfering with protein degradation and induced neoplastic transformation in murine fibroblasts. To test whether similar genetic changes may occur in vivo, we analysed a series of 60 endometrioid endometrial carcinomas (EECs) for cyclin D1 expression and gene amplification by immunohistochemistry and FISH, respectively. Two of 17 carcinomas showing cyclin D1 expression in more than 5% of neoplastic cells, but without gene amplification, were found to harbor single-base substitutions in CCND1 that changed proline 287 into threonine and serine, respectively. Both cases expressed cyclin D1 in more than 50% of neoplastic cells. Additionally, seven tumors with cyclin D1 overexpression of an independent series of 59 EECs were also analysed, and a 12-bp in-frame deletion that eliminated amino acids 289-292 was detected in one case with cylin D1 expression in more than 50% of neoplastic cells. In contrast, no mutations of the CCND1 gene were detected in a set of breast carcinomas with cyclin D1 overexpression without gene amplification. In summary, our data indicate that mutations of CCND1, which probably render the protein insensitive to degradation, represent a previously unreported mechanism of cyclin D1 overexpression in human tumors in vivo.

Breast Neoplasms↗

PubMed2003

Molecular pathology of atypical polypoid adenomyoma of the uterus.

Atypical polypoid adenomyoma (APA) is an uncommon and benign tumor of the uterus. In some patients, however, APA has been found to coexist with or to precede the development of an endometrioid adenocarcinoma similarly to complex endometrial hyperplasia. The molecular changes underlying the progression from APA to adenocarcinoma are unknown. DNA from paraffin-embedded tissue of 6 APAs was evaluated for microsatellite instability (MI), MLH-1 promoter hypermethylation, and CTNNB-1 mutations. Tissue sections were also subjected to MLH-1, MSH-2, and beta-catenin immunostaining. MI was not detected in any case. Two tumors exhibited MLH-1 promoter hypermethylation and showed focal negative MHL-1 immunostaining; 1 of these showed marked architectural complexity and cellular pleomorphism. Five cases presented beta-catenin nuclear immunoreactivity, but none of them had CTNNB-1 mutations. The results of this study suggest that APA and complex endometrial hyperplasia may share some molecular alterations. Some APAs exhibit MLH-1 promoter hypermethylation with focal lack of MLH-1 immunostaining, a molecular abnormality involved in the transition from complex atypical hyperplasia to endometrioid adenocarcinoma.

Adaptor Proteins, Signal Transducing↗

PubMed2002

Ultrastructural features of highly active antiretroviral therapy-associated partial lipodystrophy.

Chronic treatment with highly active antiretroviral therapy (HAART) results in a novel variety of partial lipodystrophy, combining lipoatrophic and hypertrophic areas. We have previously reported the histopathological features of this disease and have also shown that adipocyte apoptosis is involved in its origin. With the aim of further elucidating the mechanisms underlying this peculiar disorder, we performed an ultrastructural study of the adipocytes of ten HIV-1-infected patients treated with HAART for 20-42 months. In all ten cases, two main sets of ultrastructural changes were identified. Some adipocytes showed disruption of cell membranes, fragmented cytoplasmic rims, irregular cell outlines, and eventually fat droplets laying free in the connective tissue, with a histiocytic reaction around them. In addition, many adipocytes showed variable compartmentalization of fat droplets with decrease in cell size and abundant, mitochondria-rich cytoplasm. Often, a dual "white and brown" fat appearance was observed with a large unilocular vacuole surrounded by a rim of multilocular cytoplasm containing smaller isometric fat droplets and numerous mitochondria. These findings suggest that HAART-associated partial lipodystrophy is probably the result of a remodeling process of fat cells involving variable combinations of apoptosis, defective lipogenesis, and increased metabolic activity in different adipose areas of the body.

Acquired Immunodeficiency Syndrome↗