The Prognostic Significance of Tumor-Infiltrating Lymphocytes, PD-L1, BRCA Mutation Status and Tumor Mutational Burden in Early-Stage High-Grade Serous Ovarian Carcinoma-A Study by the Spanish Group for Ovarian Cancer Research (GEICO).

Early stages are under-represented in studies on the molecular and immune features of high-grade serous ovarian carcinoma (HGSOC), and specific studies focused on early-stage HGSOC are required for a better prognostic stratification and to personalize chemotherapy. The aim of this study was to determine the prognostic significance of CD8+ and CD4+ tumor-infiltrating lymphocytes (TILs), tumoral cell PD-L1 expression, BRCA mutational status and tumor mutation burden (TMB) in early-stage HGSOC. A retrospective study was performed on stage I and II HGSOC from the Molecular Reclassification of Early Stages of Ovarian Cancer (RECLAMO) cohort from the Spanish Group of Ovarian Cancer Research (GEICO). Centralized histological typing was performed based on morphological and immunohistochemical features. Intraepithelial (i) and stromal (s) CD8+ and CD4+ T cells and PD-L1 were evaluated on tissue microarrays by immunohistochemistry. BRCA1 and BRCA2 mutation status and TMB were analyzed in tumor DNA using next-generation sequencing. The study included 124 tumors. High iCD8+ (>20 TILs/core), low/intermediate CD4+ (<20 TILs/core) and high CD8+/CD4+ ratio (>35/core) were associated with favorable outcomes. Tumor cell PD-L1 expression (TPS ≥ 1) was present in only 8% of tumors. In total, 11 (16%) and 6 (9%) out of 69 HGSOC tested carried pathogenic or likely pathogenic BRCA1 or BRCA2 mutations, respectively. Median TMB of 40 tumors analyzed was 5.04 mutations/Mb and only 6 tumors had 10 or more mutations/Mb. BRCA status and TMB were not associated with TILs or prognosis. When compared with studies on advanced HGSOC, our results suggested that prognostic variables differed according to stage and that more studies focused on early stages of HGSOC are needed to better stratify these tumors.

Progression to lung fibrosis in severe COVID-19 patients: A morphological and transcriptomic study in postmortem samples.

The development of lung fibrosis is a major concern in patients recovered from severe COVID-19 pneumonia. This study aimed to document the evolution of diffuse alveolar damage (DAD) to the fibrosing pattern and define the transcriptional programs involved. Morphological, immunohistochemical and transcriptional analysis were performed in lung samples obtained from autopsy of 33 severe COVID-19 patients (median illness duration: 36 days). Normal lung and idiopathic pulmonary fibrosis (IPF) were used for comparison. Twenty-seven patients with DAD and disease evolution of more than 2 weeks had fibrosis. Pathways and genes related with collagen biosynthesis and extracellular matrix (ECM) biosynthesis and degradation, myofibroblastic differentiation and epithelial to mesenchymal transition (EMT) were overexpressed in COVID-19. This pattern had similarities with that observed in IPF. By immunohistochemistry, pathological fibroblasts (pFBs), with CTHRC1 and SPARC expression, increased in areas of proliferative DAD and decreased in areas of mature fibrosis. Immunohistochemical analysis demonstrated constitutive expression of cadherin-11 in normal epithelial cells and a similar pattern of cadherin and catenin expression in epithelial cells from both normal and COVID-19 samples. Transcriptomic analysis revealed downregulation of the Hippo pathway, concordant with the observation of YAP overexpression in hyperplastic alveolar epithelial cells. Progression to fibrosis in severe COVID-19 is associated with overexpression of fibrogenic pathways and increased in CTHRC1- and SPARC-positive pFBs. Whereas the Hippo pathway seemed to be implicated in the response to epithelial cell damage, EMT was not a major process implicated in COVID-19 mediated lung fibrosis.

The Clonal Relationship Between the Ductal and Lobular Components of Mixed Ductal-Lobular Carcinomas Suggested a Ductal Origin in Most Tumors.

The relationship between the ductal and lobular components of invasive ductolobular carcinomas (IDLC) has not been fully elucidated. In this study, the molecular alterations of both components were analyzed in a series of 20 IDLC that were selected, not only by morphologic criteria, but also by the loss of E-cadherin expression in the lobular component. We found that 80% of tumors shared alterations of driver genes in both components, being PIK3CA the most common alteration. In addition, 45% of IDLC carried CDH1 mutations in their lobular component that were absent in the ductal component. Fluorescent in situ hybridization analysis of the CDH1 gene excluded homozygous CDH1 loss as a frequent cause of E-cadherin loss in tumors without CDH1 mutations. In addition, no pathogenic mutations of catenin genes were detected in this series of tumors. In 25% of tumors, actionable mutations in PIK3CA , AKT1 , and ERBB2 were found in only 1 component. Altogether, our results confirm that most IDLC derive from invasive carcinoma of no special type, in which a population of cells lose E-cadherin and acquire a lobular phenotype. The frequency of CDH1 mutations in IDLC appears to be lower than in conventional invasive lobular carcinomas, suggesting the implication of alternative mechanisms of E-cadherin loss. Moreover, molecular heterogeneity between ductal and lobular areas suggests the need for molecular characterization of both components to guide targeted therapies.

Molecular Heterogeneity of High Grade Colorectal Adenocarcinoma.

High grade colorectal carcinomas (HG-CRCs), which comprise 15% of colorectal carcinomas, are underrepresented in reported molecular studies. Clinicopathological, immunohistochemical, and molecular features of 40 HG-CRCs are described. Moreover, glandular and solid areas of 25 tumors were separately analyzed. The expression of MLH1, PMS2, MSH2, MSH6, p53, E-cadherin, CDX2, CK20, CD8, PDL1, PAN-TRK, c-MET, SMARCB1, ARID1A, SMARCA2, and SMARCA4 was analyzed by immunohistochemistry. Promoter MLH1 methylation was analyzed in tumors with MLH1/PMS2 loss. Next-generation sequencing was used to screen 161 genes for hotspot mutations, copy number variations and gene fusions. In this series, 72.5% of HG-CRCs showed mismatch repair deficiency (MMRd). MMR deficient tumor and MMR proficient (MMRp) tumors showed striking molecular differences. Thus, whereas BRAF mutations were only observed in MMRd tumors, mutations in KRAS and TP53 were more frequent in MMR proficient tumors. Moreover, gene fusions (NTRK1 and MET) were detected only in MMRd tumors, whereas gene amplification (MYC, CCND1 and EGFR) predominated in MMRp/TP53-mutated tumors. Loss of expression of proteins involved in chromatin remodeling, such as ARID1A, was observed only in MMRd HG-CRCs, which also showed more frequently PD-L1 expression and a higher number of tumor infiltrating lymphocytes. The separate analysis of glandular and solid areas indicated that the clonal or subclonal nature of the molecular alterations also depended on MMR status. Mutations in genes such as TP53 and KRAS were always clonal in MMRp-CRCs but occurred as subclonal events in MMRd-CRCs. Gene amplification was implicated in the progression of MMRp tumors, but not in MMRd tumors, in which clonal diversity was due to accumulation of mutations in genes of different pathways such as NOTCH, MMR, or PIK3CA. In summary, intertumor and intratumor molecular heterogeneity in HG-CRCs is mainly due to MMR status.

Molecular Heterogeneity of Endometrioid Ovarian Carcinoma: An Analysis of 166 Cases Using the Endometrial Cancer Subrogate Molecular Classification.

Endometrioid ovarian carcinoma (EOC) has clinical and biological differences compared with other histologic types of ovarian carcinomas, but it shares morphologic and molecular features with endometrioid endometrial carcinoma. To analyze the molecular heterogeneity of EOC according to the new molecular classification of endometrial cancer and to evaluate the prognostic significance of this molecular classification, we have analyzed 166 early-stage EOC by immunohistochemistry for mismatch repair proteins and p53 expression, and by Sanger sequencing for the exonuclease domain of polymerase epsilon (POLE EDM). In addition, we have carried out next-generation sequencing analysis of tumors with POLE EDM mutations to confirm the ultramutated profile. Eight tumors carried POLE EDM mutations and were classified as ultramutated (5%), 29 showed mismatch repair deficiency and were classified as hypermutated (18%), 16 tumors had a mutated pattern of p53 expression and were classified as p53 abnormal (11%), and 114 tumors did not have any of the previous alterations and were classified as no specific type (66%). Five tumors showed >1 classification criteria. The frequencies of ultramutated and hypermutated tumors were lower in EOC compared with the frequency reported in endometrial cancer. Subrogate molecular groups differed in both morphologic features (histologic grade, squamous and morular metaplasia, and necrosis) and immunohistochemical expression of several biomarkers (ARID1A, nuclear ß-catenin, estrogen receptors, Napsin A, and HINF1B). In addition, the number of CD8 tumor-infiltrating lymphocytes was higher in ultramutated and hypermutated tumors. The most commonly mutated genes in the ultramutated group were ARID1A (100%), PIK3R1, PTEN, BCOR, and TP53 (67% each), whereas no mutations were detected in KRAS. Although the prognosis did not differ among subgroups in the multivariate analysis, a trend toward a better prognosis in POLE-mutated and a worse prognosis in p53 abnormal tumors was observed. In addition, this classification could have important therapeutic implications for the use of immunotherapy in tumors classified as ultramutated and hypermutated.

Mismatch Repair Deficiency in Ovarian Carcinoma: Frequency, Causes, and Consequences.

Mismatch repair deficiency (MMRD) is involved in the initiation of both hereditary and sporadic tumors. MMRD has been extensively studied in colorectal cancer and endometrial cancer, but not so in other tumors, such as ovarian carcinoma. We have determined the expression of mismatch repair proteins in a large cohort of 502 early-stage epithelial ovarian carcinoma entailing all the 5 main subtypes: high-grade serous carcinoma, endometrioid ovarian carcinoma (EOC), clear cell carcinoma (CCC), mucinous carcinoma, and low-grade serous carcinoma. We studied the association of MMRD with clinicopathologic and immunohistochemical features, including tumor-infiltrating lymphocytes in EOC, the histologic type in which MMRD is most frequent. In addition, MLH1 promoter methylation status and massive parallel sequencing were used to evaluate the proportion of sporadic and Lynch syndrome-associated tumors, and the most frequently mutated genes in MMRD EOCs. MMRD occurred only in endometriosis-associated histologic types, and it was much more frequent in EOC (18%) than in CCC (2%). The most frequent immunohistochemical pattern was loss of MLH1/PMS2, and in this group, 80% of the cases were sporadic and secondary to MLH1 promoter hypermethylation. The presence of somatic mutations in mismatch repair genes was the other mechanism of MMRD in sporadic tumors. In this series, the minimum estimated frequency of Lynch syndrome was 35% and it was due to germline mutations in MLH1, MSH2, and MSH6. ARID1A, PTEN, KTM2B, and PIK3CA were the most common mutated genes in this series. Interestingly, possible actionable mutations in ERRB2 were found in 5 tumors, but no TP53 mutations were detected. MMRD was associated with younger age and increased tumor-infiltrating lymphocytes. Universal screening in EOC and mixed EOC/CCC is recommended for the high frequency of MMRD detected; however, for CCC, additional clinical and pathologic criteria should be evaluated to help select cases for analysis.

The PALBONET Trial: A Phase II Study of Palbociclib in Metastatic Grade 1 and 2 Pancreatic Neuroendocrine Tumors (GETNE-1407).

LESSONS LEARNED: Palbociclib demonstrated no detectable activity in molecularly unselected and heavily pretreated patients with advanced grade 1/2 pancreatic neuroendocrine tumors. Predictive biomarkers that improve patient selection should be investigated in future studies of palbociclib. BACKGROUND: Palbociclib, a CDK4/6 inhibitor, has shown in vitro activity in pancreatic neuroendocrine tumor (pNET) cell lines. Here we prospectively assessed the activity and safety of palbociclib in monotherapy in metastatic refractory pNETs. METHODS: This was a nonrandomized, open-label, phase II study of patients with metastatic grade (G)1/2 pNETs recruited from 10 centers in Spain. Palbociclib 125 mg was orally administered once daily for 21 of 28 days until disease progression or unacceptable toxicity. RESULTS: Twenty-one patients were included; 52.4% were men, and median age was 57.4 years (range, 37.4-73.4). Patients had previously received a median of three prior lines of systemic therapy (range, 1-10) for advanced disease (somatostatin analogues, 71.4%; sunitinib, 81.0%; everolimus, 47.6%; chemotherapy, 47.6%). Nineteen patients were evaluated for objective response rate (ORR), with a median follow-up of 12.4 months (range, 7.53-19.33). No objective and confirmed responses were observed (0%); 11 (57.9%) patients had stable disease, and 6 of them lasted more than 6 months; 8 (42.1%) patients had disease progression as best response. Median progression-free survival (PFS) was 2.6 months (95% confidence interval [CI], 0-14.4) and median overall survival (OS) was 18.7 months (95% CI, 7.4-29.9; Fig. 1). Most frequent toxicities of any grade were asthenia (76.2%), neutropenia (42.9%), diarrhea (33.3%), and nausea (33.3%). Five (23.8%) patients developed G3-4 neutropenia and two (9.5%) patients developed G3-4 thrombocytopenia. CONCLUSION: Lack of activity was observed with palbociclib as a single agent in molecularly unselected and heavily pretreated patients with advanced G1/2 pNETs.

The Frequency and Prognostic Significance of the Histologic Type in Early-stage Ovarian Carcinoma: A Reclassification Study by the Spanish Group for Ovarian Cancer Research (GEICO).

The frequency and prognostic significance of the histologic type in early-stage ovarian cancer (OC) is not as well established as in advanced stages. In addition, histologic typing based only on morphologic features may be difficult, especially in high-grade tumors. In this study, we have analyzed a prospective cohort of 502 early-stage OCs to investigate their frequency, immunohistochemical characteristics, and survival of the 5 main histologic types. Histotype was assigned according to not only the morphologic features but also according to the expression pattern of WT1, p53, Napsin A, and progesterone receptors. In addition, an extended panel including p16, ß-catenin, HER2, Arid1A, HINF1B, CK7, CDX2, and CK20 was used to refine the diagnosis in difficult cases. In this series, the frequency of the 5 major histologic types was as follows: endometrioid carcinoma, 32.7%; clear cell carcinoma, 25.1%; high-grade serous carcinoma (HGSC), 24.7%; mucinous carcinoma, 10.2%; low-grade serous carcinoma, 4.6%; and others, 2.8%. The combination of morphology and immunohistochemistry allowed the reclassification of 23% of OCs. The lowest concordance was found between samples initially diagnosed as endometrioid, but finally classified as high-grade serous tumors (22% error rate). Endometrioid carcinoma was the most favorable histologic type, whereas HGSC and low-grade serous carcinoma had the worst prognosis. Clear cell carcinoma with abnormal p53 immunostaining pattern also had poor prognosis. Although histologic grade was not a prognostic factor among early-stage endometrioid OCs, distinction between grade 3 endometrioid OC and HGSC is recommended, taking into account differences in prognosis and molecular alterations that can guide different treatments.

Molecular Basis of Tumor Heterogeneity in Endometrial Carcinosarcoma.

Endometrial carcinosarcoma (ECS) represents one of the most extreme examples of tumor heterogeneity among human cancers. ECS is a clinically aggressive, high-grade, metaplastic carcinoma. At the morphological level, intratumor heterogeneity in ECS is due to an admixture of epithelial (carcinoma) and mesenchymal (sarcoma) components that can include heterologous tissues, such as skeletal muscle, cartilage, or bone. Most ECSs belong to the copy-number high serous-like molecular subtype of endometrial carcinoma, characterized by the TP53 mutation and the frequently accompanied by a large number of gene copy-number alterations, including the amplification of important oncogenes, such as CCNE1 and c-MYC. However, a proportion of cases (20%) probably represent the progression of tumors initially belonging to the copy-number low endometrioid-like molecular subtype (characterized by mutations in genes such as PTEN, PI3KCA, or ARID1A), after the acquisition of the TP53 mutations. Only a few ECS belong to the microsatellite-unstable hypermutated molecular type and the POLE-mutated, ultramutated molecular type. A common characteristic of all ECSs is the modulation of genes involved in the epithelial to mesenchymal process. Thus, the acquisition of a mesenchymal phenotype is associated with a switch from E- to N-cadherin, the up-regulation of transcriptional repressors of E-cadherin, such as Snail Family Transcriptional Repressor 1 and 2 (SNAI1 and SNAI2), Zinc Finger E-Box Binding Homeobox 1 and 2 (ZEB1 and ZEB2), and the down-regulation, among others, of members of the miR-200 family involved in the maintenance of an epithelial phenotype. Subsequent differentiation to different types of mesenchymal tissues increases tumor heterogeneity and probably modulates clinical behavior and therapy response.

High Frequency of ERBB2 Activating Mutations in Invasive Lobular Breast Carcinoma with Pleomorphic Features.

Background: Characterisation of molecular alterations of pleomorphic lobular carcinoma (PLC), an aggressive subtype of invasive lobular carcinoma (ILC), have not been yet completely accomplished. Methods: To investigate the molecular alterations of invasive lobular carcinoma with pleomorphic features, a total of 39 tumour samples (in situ and invasive lesions and lymph node metastases) from 27 patients with nuclear grade 3 invasive lobular carcinomas were subjected to morphological, immunohistochemical and massive parallel sequencing analyses. Results: Our observations indicated that invasive lobular carcinomas with pleomorphic features were morphologically and molecularly heterogeneous. All cases showed absence or aberrant expression of E-cadherin and abnormal expression of ß-catenin and p120. CDH1 (89%), PIK3CA (33%) and ERRB2 (26%) were the most common mutated genes. ERBB2 mutations preferentially affected the tyrosine-kinase activity domain, being the most frequent the targetable mutation p.L755S (57%). We also observed higher frequency of mutations in ARID1B, KMT2C, MAP3K1, TP53 and ARID1A in PLC than previously reported in classic ILC. Alterations related to progression from in situ to invasive carcinoma and/or to lymph node metastases included TP53 mutation, amplification of PIK3CA and CCND1 and loss of ARID1A expression. Conclusions: The high frequency of ERBB2 mutations observed suggests that ERBB2 mutation testing should be considered in all invasive lobular carcinomas with nuclear grade 3.

High frequency of co-infection by Epstein-Barr virus types 1 and 2 in patients with multiple sclerosis.

BACKGROUND: The existence of Epstein-Barr virus (EBV) strains specifically associated with multiple sclerosis (MS) is a matter of controversy. Little is also known about the prevalence of EBV types 1 and 2 in MS patients and the presence of co-infections by both strains. OBJECTIVE: To make EBV strain type assignment and compare the frequencies of types 1, 2 and co-infections by both in MS patients and healthy controls. METHODS: Blood samples from 75 consecutive MS patients and 186 controls were collected. EBV was simultaneously detected and typed using a polymerase chain reaction (PCR) which amplified a strain-specific sequence in the EBV nuclear antigen 2. RESULTS: EBV was detected in 70 out of 75 patients (93.3%) and in 123 of 186 controls (66.1%). Among positive cases, type 1 was found in 6 patients (8.6%) and 40 controls (32.5%), type 2 in 1 patient (1.4%) and 37 controls (30.1%), and dual-infections by both EBV types were detected in 63 patients (90%) and 46 controls (37.4%). Logistic regression models showed that MS was significantly associated with the presence of EBV (p < 0.001) and also with dual type infections (p < 0.001). CONCLUSION: This study provides molecular evidence associating co-infection of type 1 and 2 EBV with MS.

Expression of heat shock proteins in classical Hodgkin lymphoma: correlation with apoptotic pathways and prognostic significance.

AIMS: Heat shock proteins (HSPs), known to inhibit apoptosis and promote cellular survival, are overexpressed in many tumours. We analysed the expression of relevant HSPs and heat shock factor 1 (HSF1) in classical Hodgkin lymphoma (cHL) and their relationship with caspase signalling pathways and patient outcome. METHODS AND RESULTS: Using tissue microarrays (TMAs), most cases showed strong immunohistochemical expression of HSPs [10, 27, 40, 60, 70, 90, 110, HO1, cell division cycle 37 homolog (CDC37) and HSF1, which points to cHL as a potential candidate to stress-response inhibitors. Active caspases 3, 8 and 9 were detected in 55.1%, 55.4% and 96.2% of cases although cleaved poly (ADP-ribose) polymerase (PARP) was observed in only 16.1%, suggesting an improper functioning of apoptosis. Statistical analysis showed associations of HSP70 with active caspase 3 (P = 0.000); HSP40 with active caspase 9 (P = 0.031) and p53 (P = 0.003); HO1 with p53 (P = 0.006) and p21 (P = 0.005); and p53 with p21 (P = 0.015). CONCLUSIONS: Correlations between the expression of apoptotic markers and HSPs may suggest a role for the latter in modulating apoptosis in cHL, mainly through the HSP70-HSP40 system, and in the stabilization of p53. Survival analyses showed that absence of active caspase 8 and HO1 had a negative impact in patient outcome.

Persistent monoclonality after histological remission in gastric mucosa-associated lymphoid tissue lymphoma treated with chemotherapy and/or surgery: influence of t(11;18)(q21;q21).

The purpose of this work was to study retrospectively the molecular response and outcome of 19 gastric mucosa associated lymphoid tissue (MALT) lymphoma patients achieving histological remission after chemotherapy or surgery. Immunoglobulin heavy chain variable (IgV(H)) gene rearrangements were studied by PCR in biopsies obtained at diagnosis and follow-up. Presence of t(11;18)(q21;q21) was studied by FISH or RT-PCR. Sequencing analysis of three t(11;18)(q21;q21) positive and two negative lymphomas with persistent monoclonal IgV(H) rearrangements was also performed. Long-term IgV(H) monoclonality was demonstrated in 11/19 patients (58%); in five of them monoclonal rearrangements were present in all samples throughout the follow-up. Persistent IgV(H) monoclonality was detected a median of 49 months after the achievement of histological response and did not condition histological relapse in most cases. All three t(11;18)(q21;q21) positive patients had maintained IgV(H) monoclonality and sequencing analyses revealed the same mutated IgV(H) alleles in the diagnostic and the follow-up samples. Over half of the patients with gastric MALT lymphoma with histological response after chemotherapy and/or surgery have long-term persistent monoclonality. The presence of t(11;18)(q21;q21) seems to condition long-term persistence of the initial lymphoma clone.trade mark.

Analysis of Epstein-Barr virus strains and variants in classical Hodgkin's lymphoma by laser microdissection.

Epstein-Barr virus (EBV) seems to have an etiological role in the pathogenesis of classical Hodgkin's lymphoma (cHL). Studies of whole tissue DNA by polymerase-chain reaction (PCR) have shown a considerable number of cHL cases with co-infections by different EBV strains and variants, which apparently contradict the clonality of EBV in cHL previously demonstrated by Southern blot analysis. Due to the paucity of HRS cells in HL tissues, studies on single cell DNA are necessary to identify the specific cellular location (HRS cells and/or bystander B lymphocytes) of the EBV strains and variants present in tissue specimens. In the current study, the presence of EBV was determined by PCR of the 3' end of the LMP-1 gene and EBNA-3C gene in whole tissue and, consecutively, in isolated cells from 26 cases of cHL: 10 HIV-positive and 16 sporadic cHL cases. EBV EBERs were present in all but 2 sporadic cHL cases, which were used as negative controls. At isolated cell level, EBNA-3C gene PCR was more sensitive. Indeed, from the cHL cases in which dual-infection was present, it was observed that, in most of them, HRS cells were infected by type 1 virus, and B lymphocytes were co-infected by both types, which points towards EBV infection occurring early in cHL development. Moreover, the finding of 2 cases with dual-infection in HRS may suggest that, in a small percentage of cHL cases, HRS cells derive from different neoplastic clones, or that HRS cells are superinfected by other viral types after the establishment of the neoplastic clone.

Genetic analysis of RET, GFR alpha 1 and GDNF genes in Spanish families with multiple endocrine neoplasia type 2A.

Multiple endocrine neoplasia type 2A (MEN 2A) is associated with specific germline missense mutations in the RET proto-oncogene. This locus encodes a receptor tyrosine kinase whose activation requires the formation of a multimeric receptor complex including GDNF as a ligand and GFR alpha 1 as a coreceptor. In order to explore the role of RET, GFR alpha 1 and GDNF genes in the variation of phenotypes observed in MEN2A families, we analysed germline mutations of these genes in 4 unrelated Spanish MEN2A families (23 cases studied). We found 2 novel variants corresponding to a single change in position + 47 (intron 12) of RET and position +22 (intron 7) of GFR alpha 1. Furthermore, we observed strong co-segregation between 2 polymorphisms of RET [G691S (exon 11) and S904S (TCC-TCG, exon 15) (100%, Fisher's exact test, p< 0.001)]. More interestingly, we found that these polymorphisms occurred at a significantly high frequency in patients with age at onset < 20 years old (Kruskal-Wallis's and Fisher's exact test, p = 0.007). These findings suggest that the G691S and S904S variants of RET may somehow play a role on the age of onset of MEN 2A.

p53/MDM2 Pathway Aberrations in Parathyroid Tumors: p21(WAF-1) and MDM2 Are Frequently Overexpressed in Parathyroid Adenomas.

Parathyroid adenomas (PTAs) are the main cause of primary hyperparathyroidism. Cell cycle regulation in normal parathyroid tissue (NPT) and PTA remains largely unknown. We have systematically explored several components involved in the p53/MDM2/p19(ARF) pathway in PTA and compared the results were with NPT. Forty-six PTA and 12 NPT were immunostained with anti-p21(WAF-1), MDM2, p53, and p27(KP1) antibodies. The slides were processed by cytometry and the results were statistically analyzed using nonparametric methods (Mann-Whitney test). p2l(WAF-1) and MDM2 expression were significantly higher in PTA compared with NPT (p < 0.05). The opposite results were found for p27(KIP1) (p< 0.05). Occasional p53 staining was found in some PTA, albeit no significant difference was found in comparison with NPT. In conclusion, MDM2 and p2l(WAF-1) are the proteins more overexpressed in PTA. These findings are surprising taking into account the benign nature of PTA, making them suitable candidates for further molecular analysis.

Analysis of the Cycilin D1/p16/pRb Pathway in Parathyroid Adenomas.

Cyclin D1/p16/pRb pathway controlling G1-S cell cycle checkpoint is frequently altered in human tumors. Currently, scarce data are available for parathyroid tumors. We have studied 46 parathyroid adenomas (PTAs) and 12 normal parathyroid glands (PTGs) by immunohistochemistry with cyclin D1 (CD1), p16, pRb, and Ki-67 antibodies. We observed CD1 expression in 89%, p16 in 70%, and pRb in 100% of PTAs. Statistically significant differences with normal PTGs were found only concerning p16 expression (p <0.05). Proliferating rate (Ki-67) was always low, although significantly higher than in normal PTGs. Our findings demonstrate the presence of alterations in the CD1/p16/pRb pathway in PTAs, consisting in p16 overexpression apparently unrelated to pRb downregulation. On the other hand, we did not find significant differences in CD1 expression between PTAs and normal PTGs, suggesting CD1 overexpression could be a physiological event in parathyroid tissue.