Acute pancreatitis signals activation of apoptosis-associated and survival genes in mice

In experimental models of acute pancreatitis (AP), acinar cell death occurs by both necrosis and programmed cell death or apoptosis. Apoptosis is an active form of cell death associated with a tightly regulated expression of gene products that are either pro- or antiapoptotic. The aim of this study was to characterize pancreatic mRNA levels by Northern blotting analysis of apoptosis-associated genes used during the course of cerulein-induced AP in mice. Histone H3 mRNA levels were also examined as an indicator of cell proliferation. Acinar cell apoptosis was confirmed histologically. The findings show that AP modifies pancreatic mRNA levels of both pro- and antiapoptotic genes simultaneously. Pancreatic bclXL, bax, and p53 mRNA levels increased significantly in a temporal fashion during induction of AP. Pancreatic bcl-2 mRNA levels were unchanged during AP. Pancreatic mRNA levels of insulin-like growth factor-1 (IGF-1), a mitogen and cell survival factor, and its receptor (IGF-1R) also increased in a temporal fashion during induction of AP. In summary, this study indicates that acinar cell death during cerulein-induced AP in mice can occur by the apoptotic pathway. Since factors promoting and antagonistic for cell survival are activated simultaneously, regulation of acinar cell survival appears complex and dynamic during AP.

Regulation of tumor necrosis factor alpha-mediated apoptosis of rheumatoid arthritis synovial fibroblasts by the protein kinase Akt

OBJECTIVE

To determine if tumor necrosis factor alpha (TNFalpha)-driven proliferation of rheumatoid arthritis synovial fibroblasts (RASF) is associated with up-regulation of the activity of serine/threonine kinase B/Akt and with survival of RASF.

METHODS

Staining of phosphorylated Akt was done using anti-phosphorylated Thr308 Akt antibody. Levels of phosphorylated Akt were analyzed by Western blot and Akt activity was analyzed using a kinase assay. TUNEL staining was used to analyze the cytotoxicity of TNFalpha treatment or TNFalpha combined with either the Akt activity inhibitor wortmannin, an adenovirus expressing dominant-negative mutant (AdAkt-DN), or an adenovirus expressing phosphatase and tensin homolog deleted on chromosome 10 (AdPTEN).

RESULTS

The levels of phosphorylated Akt were higher in RASF than in osteoarthritis synovial fibroblasts (OASF), as demonstrated by immunohistochemical staining, immunoblot analysis, and an Akt kinase assay. The levels of phosphorylated Akt and Akt kinase activity were increased by stimulation of primary RASF with TNFalpha (10 ng/ml). Treatment of RASF with the phosphatidylinositol 3-kinase inhibitor wortmannin (50 nM) plus TNFalpha resulted in apoptosis of 60 +/- 8% (mean +/- SEM) of RASF within 24 hours. This proapoptosis effect was specific for Akt, since equivalent levels of apoptosis were observed upon TNFalpha treatment of RASF transfected with AdAkt-DN and with AdPTEN, which opposes the action of Akt.

CONCLUSION

These results indicate that phosphorylated Akt acts as a survival signal in RASF and contributes to the stimulatory effect of TNFalpha on these cells by inhibiting the apoptosis response. This effect was not observed in OASF and may reflect the pathophysiologic changes associated with the proliferating synovium in rheumatoid arthritis.

[Congenital amegakaryocytic thrombocytopenia (CAMT) - a defect of the thrombopoietin receptor c-Mpl]

Congenital amegakaryocytic thrombocytopenia (CAMT) is a very rare bone marrow failure syndrome presenting with isolated hypomegakaryocytic thrombocytopenia at birth developing into a pancytopenia during the first years of life. Bone marrow transplantation is the only curative therapy for this disease so far. Thrombopoietin (TPO) is the most important hematopoietic growth factor for the regulation of megakaryopoiesis and thrombopoiesis. We investigated TPO production and reactivity in CAMT patients. TPO plasma levels were high like in other forms of thrombocytopenia due to ineffective megakaryopoiesis. However, we found a defective reactivity to TPO: Neither hematopoietic progenitor cells in the bone marrow nor platelets from the peripheral blood did respond to TPO. Flow cytometric investigations demonstrated a lack of expression of the TPO receptor c-Mpl on the surface of platelets. Accordingly, we found mutations in the c-mpl gene, which are predicted to lead to a complete or at least partial loss of function of the TPO receptor. TPO is not only involved in the regulation of megakaryocytopoiesis but also in early hematopoiesis. This seems to be the reason for the general defect in hematopoiesis in CAMT leading to the development of pancytopenia.

Altered expression of TGFB receptors and mitogenic effects of TGFB in pancreatic carcinomas

Alteration of the transforming growth factor beta (TGFB) signalling pathway is important in pancreatic carcinogenesis, as shown by the frequent inactivation of the downstream target SMAD4. We recently analysed a series of pancreatic carcinoma cell lines with respect to alterations of five SMAD genes involved in TGFB signalling, and showed that SMAD4 was structurally rearranged in 42% of these. This pathway may, however, also be affected by alterations of genes whose products regulate the activation of TGFB as well as of TGFB receptor genes. We therefore studied the expression of UPA, UPAR, IGF2R, ALK5 (TGFBR1), TGFBR2, TGFBR3, ENG, ALK1, TGFB1, TGFB2, and TGFB3 in a series of 14 pancreatic carcinoma cell lines. We also analysed ALK5 and TGFBR2 for mutations, cell surface localisation of TGFBR2 and ENG, and TGFB1 response. No mutations of ALK5 or TGFBR2 were found. However, 4 cell lines were methylated within the ALK5 promoter region. ALK5 expression was strongly reduced in 9 cases, whereas TGFBR2 expression was increased in 12 of the cell lines. The TGFB signalling associated receptors ENG and ALK1 were co-expressed in 4 of the cell lines. There was no evidence for disruption of the UPAR-IGF2R TGFB activating pathway. The response to TGFB1 was analysed in 12 cell lines, and 6 of these (50%) showed increased proliferation. The cell lines stimulated by TGFB showed frequent mutations of SMAD4, KRAS2, and TP53, as well as frequent absence of CDKN2B expression. These results suggest that the ALK5-SMAD4 part of the TGFB signalling pathway is a major target for inactivation in pancreatic carcinomas, that the expression of TGFBR2, TGFBR3, and receptors involved in TGFB activation are maintained, and that alterations of components of the TGFB signalling pathway may be accompanied by a positive effect of TGFB on cell growth.

Flt-3 and its ligand are expressed in neural crest-derived tumors and promote survival and proliferation of their cell lines

Flt-3 ligand (FL) is a cytokine that promotes the survival, proliferation, and differentiation of hematopoietic progenitors in synergy with other growth factors, such as stem cell factor. Previously we have demonstrated that stem cell factor and its receptor c-kit are expressed in neural crest-derived tumor cells and that a c-kit block induces their apoptosis. Here we have evaluated the expression of flt-3 and its ligand in 12 neuroectodermal tumor cell lines from neuroblastoma (NB), neuroepithelioma (NE), Ewing sarcoma (ES), and peripheral neuroectodermal tumor (PNET) and in 38 biopsies: 19 from NB and 19 from ES and PNET. RT-PCR demonstrated the expression of flt-3 and FL in all lines. Coexpression was observed in 42% of NB and in 74% of ES and PNET biopsies. Flow cytometry confirmed the presence of membrane and cytoplasmic flt-3 and membrane FL in all lines, whereas soluble FL protein was not measurable in their supernatants. Microphysiometric demonstration of acidification of the medium provided evidence of the specific response of cell lines to FL stimulation. Specific flt-3 phosphorylation after FL treatment was also demonstrated by Western blotting analysis. In cells growing in RPMI plus 1% fetal calf serum, FL revealed a significant proliferating activity, more evident in NB and NE lines (mean increase of viable cells, 73 +/- 26% after 1 day). Treatment with flt-3 antisense oligonucleotides significantly inhibited cell growth. FL also displayed an antiapoptotic activity: after a 12-hour culture in the presence of 0.1% fetal calf serum, FL caused a 50% reduction of apoptotic cells. These results provide further evidence that neuroectodermal and hematopoietic cells share common regulatory pathways, and could be of interest in the clinical management of neuroectodermal tumors.

Advances in molecular genetics and pathology of cerebrovascular disorders

Progress in molecular genetics has enabled the dissection of several autosomal dominantly inherited forms of cerebrovascular disorders. Mutations in diverse genes might induce pathological changes in intracranial vessels, resulting in cerebral haemorrhages and ischaemic strokes. Such pathologies, however, might also result from systemic vascular disease caused by mutations or polymorphisms in genes that regulate cardiovascular physiology, blood coagulation, lipid metabolism and metabolic functions. Interestingly, several mutations that directly affect CNS vasculature involve genes that control inter- or intracellular signalling functions. Although highly variable phenotypes make it difficult to pinpoint the genotypes, genetic characterization of cerebrovascular disorders is valuable for understanding the pathogenesis and management of sporadic disease.

Nitric oxide induces murine thymocyte apoptosis by oxidative injury and a p53-dependent mechanism

Previously, we showed that NO induces thymocyte apoptosis via a caspase-1-dependent mechanism [(1) ]. In the present study, we investigated the role of heme oxygenase, catalase, bax, and p53 in this process. The NO donor, S-nitroso-N-acetyl penicillamine (SNAP), induced DNA fragmentation in thymocytes in a time- and concentration-dependent way. SNAP (100 microM) induced 50--60% apoptosis; higher doses did not increase the rate of apoptosis significantly. SNAP decreased catalase and heme iron (Fe) levels without affecting superoxide dismutase, glutathione, or total Fe stores in thymocytes. SNAP significantly increased the expression of heme oxygenase 1 (HSP-32), p53, and bax but not bcl-2. Treatment with the heme oxygenase inhibitor, tin protoporphyrin IX inhibited SNAP-induced thymocyte apoptosis. Furthermore, thymocytes from p53 null mice were resistant to NO-induced apoptosis. Our data suggest that NO may induce its cytotoxic effects on thymocytes by modulating heme oxygenase and catalase activity as well as up-regulating pro-apoptotic proteins p53 and bax.

Improved prognostic significance of cytokine-induced proliferation in vitro in patients with de novo acute myeloid leukemia of intermediate risk: impact of internal tandem duplications in the Flt3 gene

The heterogeneity of acute myeloid leukemia is reflected in many clinical, biological and genetic features that are used to predict the response to therapy. On the basis of chromosome aberrations patients can be stratified in groups reflecting either good or poor prognosis. However, the majority of patients fall in an 'intermediate risk' group. Internal tandem duplications in the hematopoietic growth factor receptor Flt3 have been shown to separate a subset of high risk patients from intermediate or low risk cases. In an attempt to further characterize the heterogeneity of prognosis among the cytogenetic intermediate risk group of AML, we investigated the overall survival, failure-free survival, initial therapy response and relapse rates of 103 patients with de novo AML in relation to autonomous proliferation and the proliferative response to a panel of 10 cytokines in a short-term thymidine incorporation assay. To exclude perturbation of the responses by other (known) risk factors our final intermediate risk population was comprised of patients with intermediate risk cytogenetics, having an age of 60 years of younger and not showing tandem duplications in the Flt3 gene. Among this intermediate risk group, only the responses to M-CSF and IL-1alpha were found to be predictive for therapy outcome. Results obtained by a 7-day culture with these cytokines revealed two subpopulations characterized by a good and a poor prognosis, respectively. The complete remission rates in these subpopulations were similar, but the relapse rates, failure-free survival and overall survival differed. If further study extends and supports our data, it should be considered to include these patients in the poor risk arms of treatment protocols and offer them intensified treatment or bone marrow transplantation.

Adenovirus-mediated soluble FLT-1 gene therapy for ovarian carcinoma

PURPOSE

We hypothesized that adenovirus-mediated soluble fms-like tyrosine kinase receptor (sFLT-1) gene therapy can inhibit the ovarian tumor growth and increase survival of mice in the context of ovarian carcinoma.

EXPERIMENTAL DESIGN

We constructed an infectivity-enhanced recombinant adenovirus (AdRGDGFPsFLT-1) expressing soluble FLT-1 and green fluorescent protein (GFP). An adenovirus AdRGDGFP expressing GFP alone was used as control. The functional validation of adenovirus-mediated sFLT-1 was determined by an in vitro human umbilical vein endothelial cell proliferation inhibition assay. To evaluate the therapeutic potential of adenovirus-expressed sFLT-1 to inhibit the growth of ovarian tumors and to increase the survival duration of mice with ovarian tumors, two tumor models were used. First, SKOV3.ip1 ovarian carcinoma cells were infected ex vivo with either AdRGDGFPsFLT-1 or AdRGDGFP or uninfected and then inoculated s.c. into BALB/c nude mice, and tumor growth was monitored. Second, SKOV3.ip1 cells were inoculated i.p. into CB17 SCID mice and then treated with two doses of either AdRGDGFPsFLT-1 or AdRGDGFP or with PBS on days 1 and 14 after inoculation of cells, and the survival duration was monitored.

RESULTS

Treatment with adenovirus-expressed sFLT-1 significantly inhibited the proliferation of human umbilical vein endothelial cells. The s.c. tumor nodules in mice derived from cells infected with AdRGDGFPsFLT-1 were significantly smaller than those infected with either AdRGDGFP or uninfected. In addition, i.p. administration of the AdRGDGFPsFLT-1 resulted in a significant increase in the survival times of mice compared with AdRGDGFP- or PBS-treated mice.

CONCLUSIONS

Our results suggest that adenovirus-mediated sFLT-1 gene therapy can effectively inhibit ovarian tumor growth and increase survival in a murine model of ovarian carcinoma.

RET/PTC rearrangements in thyroid nodules: studies in irradiated and not irradiated, malignant and benign thyroid lesions in children and adults

Rearrangements of the RET proto-oncogene may occur in both naturally occurring and radiation-induced papillary thyroid carcinomas. Conflicting results on the frequency and type of RET/PTC rearrangements have been reported in relation to age, radiation exposure, and histological tumor variant. We designed the present study to evaluate in a single laboratory, using the same methodologies, the pattern of RET/PTC activation in thyroid tumors from different groups of patients (exposed or not exposed to radiation, children or adults, with benign or malignant tumors) in relationship to the above mentioned variables. We studied 154 patients with benign nodules (n = 65) or papillary thyroid cancer (n = 89). In the last group, 25 were Belarus children exposed to the post-Chernobyl radioactive fallout, 17 were Italian adults exposed to external radiotherapy for benign diseases, and 47 were Italian subjects (25 children and 22 adults) with no history of radiation exposure. Among patients with benign thyroid nodules, 21 were Belarus subjects (18 children and 3 adults) exposed to the post-Chernobyl radioactive fallout, 8 were Italian adults exposed to external radiation on the head and neck, and 36 were Italian adults with naturally occurring benign nodules. The overall frequency of RET/PTC rearrangements in papillary thyroid cancer was 55%. The highest frequency was found in post-Chernobyl children and was significantly higher (P = 0.02) than that found in Italian children not exposed to radiation, but not significantly higher than that found in adults exposed to external radiation. No difference of RET/PTC rearrangements was found between samples from irradiated (external x-ray) or not irradiated adult patients, as well as between children and adults with naturally occurring, not irradiated, thyroid cancer. When analyzing the type of RET/PTC rearrangement (RET/PTC1 or RET/PTC3), no major difference was apparent. In addition, eight cases with an unknown RET/PTC rearrangement and three cases with the concomitant expression of RET/PTC1 and RET/PTC3 were found. No significant correlation was observed between the frequency and/or the type of RET/PTC rearrangement and clinical-epidemiological features of the patients such as age at diagnosis, age at exposure, histological variant, gender and tumor-node-metastasis (TNM) categories. RET/PTC rearrangements were also found in 52.4% of post-Chernobyl benign nodules, in 37.5% of benign nodules exposed to external radiation and in 13.9% of naturally occurring nodules (P = 0.005, between benign post-Chernobyl nodules and naturally occurring nodules). The relative frequency of RET/PTC1 and RET/PTC3 in rearranged benign tumors showed no major difference. In conclusion, our results indicate that the presence of RET/PTC rearrangements in thyroid tumors is not restricted to the malignant phenotype, is not higher in radiation-induced tumors compared with those naturally occurring, is not different after exposure to radioiodine or external radiation, and is not dependent from young age. Other factors, probably influenced by ethnic or genetic background, may act independently from or in cooperation with radiation, to trigger the DNA damage leading to RET proto-oncogene activation.

Alteration of the Bcl-2:Bax ratio in the placenta as pregnancy proceeds

The placenta is the primary site of nutrient and gas exchange between mother and foetus. During human placental development, proliferation, differentiation and apoptosis occur at different stages. In order to clarify some of the molecular mechanisms underlying these events, we investigated the pattern of expression of two members of the Bcl-2 family in human placenta samples and compared them to the level of apoptosis detected by the TUNEL method. In particular, we evaluated the expression of Bcl-2 and Bax and their ratio during the first and third trimester. We found that Bcl-2 was generally expressed at low levels during the entire gestational period. On the other hand, Bax was low during the first trimester but increased towards the end of gestation. In accordance with the change of ratio of these two molecules, the increase of apoptotic cells was observable in the third trimester. These data indicate that Bcl-2 and Bax are spatio-temporally regulated during placental development and that the different expression of the above mentioned genes is at least in part responsible for the delicate balance between cell proliferation and programmed cell death in the human placenta during pregnancy.

A TPR motif cofactor contributes to p300 activity in the p53 response

The transcription of p53 target genes involves p300/CBP coactivators, which are multiprotein complexes that interact with the p53 activation domain. We report a cofactor in the p300 coactivator complex, Strap, which has an unusual structure, being composed almost entirely of a tandem series of six tetratricopeptide repeat (TPR) motifs. The TPR motif functions as a protein interaction domain, and it is consistent with this property that Strap harbors distinct and dedicated domains that allow it to bind and augment the interaction between different components of the p300 complex. Strap facilitates p53 activity in response to stress, in part through the stress-responsive accumulation of Strap protein and interfering with the MDM2-dependent downregulation of p53.

Splice variants VEGF121 and VEGF165 of the angiogenic peptide vascular endothelial cell growth factor are expressed in the synovial tissue of patients with rheumatoid arthritis

OBJECTIVE

To determine the expression of the angiogenic peptide vascular endothelial growth factor (VEGF, also known as vascular permeability factor, VPF) in the synovium of patients with rheumatoid arthritis (RA).

METHODS

Expression of VEGF protein from the synovial tissue of 10 patients with RA was monitored by ELISA and visualized by immunocytochemistry, and by double-staining with the VEGFR-1/flt-1. VEGF mRNA and its splice variants were determined by reverse transcriptase polymerase chain reaction (RT-PCR).

RESULTS

VEGF protein was strongly increased in rheumatoid synovium and localized at the synovial surface, whereas the VEGF receptor flt-1 (VEGFR-1) was visualized on microvessels in close vicinity. In synovial tissues from all 10 patients with RA, VEGF121 and VEGF165 were identified at the mRNA level as the only VEGF splice forms expressed.

CONCLUSION

Since VEGF165 and VEGF121 are differently diffusible due to their opposite heparan sulfate-binding properties, they act at different distances. The presence of VEGF121 may explain induction of the VEGFR-1 on infiltrating blood vessels near the synovial surface.

Functional analysis of RET with Hirschsprung mutations affecting its kinase domain

BACKGROUND AND AIMS

Many missense mutations in the RET proto-oncogene were found in familial and sporadic cases of Hirschsprung disease (HSCR). The aim of this study was to make clear the mechanisms of RET dysfunction by HSCR mutations identified in its kinase domain.

METHODS

Ten kinase domain HSCR mutations were introduced into wild-type RET and constitutively activated RET with a multiple endocrine neoplasia 2A mutation, and the resulting mutant complementary DNAs were transfected into SK-N-MC primitive neuroectodermal tumor cells or NIH 3T3 fibroblast cells. The levels of activation of mutant RET and representative signaling molecules were investigated in the transfectants.

RESULTS

E762Q, S767R, R972G, and M980T mutations partially impaired the RET kinase activity and the representative signaling pathways. In particular, these mutations severely impaired the phospholipase C-gamma signaling pathway in SK-N-MC cells. S765P, R873Q, F893L, R897Q, and E921K mutations resulted in a complete loss of the RET kinase activity. The P973L mutation markedly decreased the expression of the RET protein with normal kinase activity.

CONCLUSIONS

Hirschsprung disease can result from these distant functional classes of kinase domain mutation of RET.

Caspase-9 transduction overrides the resistance mechanism against p53-mediated apoptosis in U-87MG glioma cells

OBJECTIVE

Conflicting reports have been published with regard to the relationship between the efficacy of p53 gene therapy and the p53 status of gliomas. In this study, we evaluated whether U-87MG glioma cells harboring wild-type p53 and U251 and U-373MG glioma cells harboring mutated p53 demonstrate different sensitivities to p53-induced apoptosis. In addition, we tested whether transduction of Bax or caspase-9, which are downstream components of p53-induced apoptosis, can override the resistance mechanism of U-87MG cells to apoptosis.

METHODS

We transduced U-87MG, U251, and U-373MG glioma cells with p53, Bax, or caspase-9 genes via adenovirus (Adv) vectors, to induce the same level of respective proteins, and evaluated the degree of apoptosis.

RESULTS

U-87MG cells were highly resistant to Adv for p53 (Adv-p53)-mediated apoptosis, whereas U251 and U-373 cells underwent extensive apoptosis after Adv-p53 infection. In U-87MG cells, the elevation of Bax and Fas was not as marked as that observed in U251 and U-373MG cells after Adv-p53 infection. Endogenous expression of Bcl-XL and Bcl-2 in U-87MG cells was greater than that in U251 and U-373MG cells. U-87MG cells were more resistant to Bax-mediated apoptosis than were U251 or U-373MG cells. In contrast, U-87MG cells were more sensitive to caspase-9-mediated apoptosis than were U251 or U-373MG cells, suggesting that transduction of caspase-9 may override the resistance mechanism of U-87MG to p53-mediated apoptosis.

CONCLUSION

These results demonstrate that proapoptotic function induced by p53 transduction in U-87MG cells was repressed at several steps and that induction of caspase-9 may circumvent this resistance mechanism.

[Atypical CADASIL phenotypes and pathological findings in two new French families]

Atypical phenotypes of CADASIL and corresponding anatomical data in two cases are described in 6 members of 2 new French families. In the first family, 4 cases in the same kindred were probably affected, two of them with a predominant psychiatric presentation, two others with dementia and a pseudo-bulbar syndrome of progressive evolution. No history of migraine or ischemic event were documented in any. In the propositus, the diagnosis was documented by skin biopsy, Notch 3 gene mutation and autopsy after the patient had died when 67 years old, 8 years after onset. Brain examination showed a widespread leukoencephalopathy with subcortical infarcts. Characteristic granular lesions of the small arteries of the brain and other organs were observed. In the second family, two cases are reported. One patient died when 63 years old after a subacute evolution mimicking intracranial hypertension. The anatomical diagnosis was retrospectively proven typical of CADASIL with Notch 3 immunostaining of arterial smooth muscle cells. The other case had a progressive evolution over 20 years of limb paresthesia with a mild spasticity diagnosed as a progressive form of multiple sclerosis. It was followed by a pseudo-bulbar syndrome and a mild subcortical dementia without acute ischemic attack. The diagnosis was confirmed by skin biopsy and mutation of the Notch 3 gene. This report illustrates

Candidate genes for nonsyndromic cleft lip and palate

The confirmation of supposed genes causing susceptibility to nonsyndromic cleft lip with or without a cleft palate (CL/P) and cleft palate alone (CP) would help to understand the molecular development of the lip, the palate and the jaw, and to predict more accurately the risk of recurrence of such defects. The purpose of this article is to present a brief review of the current state of knowledge regarding the search for genes responsible for the occurrence of CL/P and CP. After ten years of research, approximately twenty candidate genes have already been suggested for CL/P and CP. Some genes or chromosomal regions seem to be frequently associated with these defects and a specific nomenclature (orofacial cleft genes--OFC) has been suggested. Everything indicates that it will still take many years of research before the genes responsible for CL/P and CP are confirmed. These efforts are justified, however, because of the possibility of being able to predict more accurately the risk of such defects occurring.

RET/PTC rearrangements in thyroid nodules: studies in irradiated and not irradiated, malignant and benign thyroid lesions in children and adults

Rearrangements of the RET proto-oncogene may occur in both naturally occurring and radiation-induced papillary thyroid carcinomas. Conflicting results on the frequency and type of RET/PTC rearrangements have been reported in relation to age, radiation exposure, and histological tumor variant. We designed the present study to evaluate in a single laboratory, using the same methodologies, the pattern of RET/PTC activation in thyroid tumors from different groups of patients (exposed or not exposed to radiation, children or adults, with benign or malignant tumors) in relationship to the above mentioned variables. We studied 154 patients with benign nodules (n = 65) or papillary thyroid cancer (n = 89). In the last group, 25 were Belarus children exposed to the post-Chernobyl radioactive fallout, 17 were Italian adults exposed to external radiotherapy for benign diseases, and 47 were Italian subjects (25 children and 22 adults) with no history of radiation exposure. Among patients with benign thyroid nodules, 21 were Belarus subjects (18 children and 3 adults) exposed to the post-Chernobyl radioactive fallout, 8 were Italian adults exposed to external radiation on the head and neck, and 36 were Italian adults with naturally occurring benign nodules. The overall frequency of RET/PTC rearrangements in papillary thyroid cancer was 55%. The highest frequency was found in post-Chernobyl children and was significantly higher (P = 0.02) than that found in Italian children not exposed to radiation, but not significantly higher than that found in adults exposed to external radiation. No difference of RET/PTC rearrangements was found between samples from irradiated (external x-ray) or not irradiated adult patients, as well as between children and adults with naturally occurring, not irradiated, thyroid cancer. When analyzing the type of RET/PTC rearrangement (RET/PTC1 or RET/PTC3), no major difference was apparent. In addition, eight cases with an unknown RET/PTC rearrangement and three cases with the concomitant expression of RET/PTC1 and RET/PTC3 were found. No significant correlation was observed between the frequency and/or the type of RET/PTC rearrangement and clinical-epidemiological features of the patients such as age at diagnosis, age at exposure, histological variant, gender and tumor-node-metastasis (TNM) categories. RET/PTC rearrangements were also found in 52.4% of post-Chernobyl benign nodules, in 37.5% of benign nodules exposed to external radiation and in 13.9% of naturally occurring nodules (P = 0.005, between benign post-Chernobyl nodules and naturally occurring nodules). The relative frequency of RET/PTC1 and RET/PTC3 in rearranged benign tumors showed no major difference. In conclusion, our results indicate that the presence of RET/PTC rearrangements in thyroid tumors is not restricted to the malignant phenotype, is not higher in radiation-induced tumors compared with those naturally occurring, is not different after exposure to radioiodine or external radiation, and is not dependent from young age. Other factors, probably influenced by ethnic or genetic background, may act independently from or in cooperation with radiation, to trigger the DNA damage leading to RET proto-oncogene activation.

Pseudohypoparathyroidism Ia and hypercalcitoninemia

Pseudohypoparathyroidism Ia (PHP Ia) is characterized by resistance to PTH and many other stimuli because of deficiency of stimulatory G protein alpha-subunit. To determine the incidence, natural history, and mechanism of C cell dysfunction in PHP, calcitonin assays were performed in six patients with PHP Ia and four with pseudopseudohypoparathyroidism from three unrelated families. Controls included healthy subjects and patients with PHP Ib or hypoparathyroidism. The mean basal level of calcitonin was higher in PHP Ia patients than in controls (95.3 +/- 112.7 vs. 3.7 +/- 2.4 pg/mL; P = 0.005; n < 10). In PHP Ia patients, calcitonin levels rose over the normal range (30 pg/mL) after pentagastrin infusion in five patients and remained normal in one. Familial medullary thyroid carcinoma was clinically, biologically, and ultrasonographically ruled out over a mean follow-up exceeding 3 yr. Genomic screening for RET protooncogene mutations failed to reveal any anomaly. The calcitonin infusion test, which induced a significant increase in plasma cAMP in controls 30 and 60 min after infusion, failed to produce this response in PHP Ia patients, suggesting that the action of calcitonin was specifically impaired. PHP Ia may therefore be an independent etiology of hypercalcitoninemia and hyperresponsiveness to pentagastrin infusion.

Targeted disruption of the aromatase P450 gene (Cyp19) in mice and their ovarian and uterine responses to 17beta-oestradiol

Aromatase P450 (CYP19) is an enzyme catalysing the conversion of androgens into oestrogens. We generated mice lacking aromatase activity (ArKO) by targeted disruption of Cyp19 and report the characteristic features of the ArKO ovaries and uteri as revealed by histological and biochemical analyses. ArKO females were totally infertile but there were as many developing follicles in their ovaries at 8 weeks of age as in wild-type ovaries. Nevertheless, no typical corpus luteum was observed in the ArKO ovaries. Electron microscopy revealed the presence of well-developed smooth endoplasmic reticulum, few lipid droplets and mitochondria with less organized tubular structures in the ArKO luteinized interstitial cells. These ultrastructural features were different from those of the wild-type interstitial cells, where there are many lipid droplets and mitochondria with well-developed tubular structures, characteristic of steroid-producing cells. When ArKO mice were supplemented with 17beta-oestradiol (E(2); 15 microg/mouse) every fourth day from 4 weeks of age for 1 month, increased numbers of follicles were observed in the ovaries as compared with those of untreated ArKO mice, although no typical corpus luteum was detectable. Ultrastructural analysis revealed the disappearance of the accumulated smooth endoplasmic reticulum in the luteinized interstitial cells after E(2 )supplementation. Transcripts of pro-apoptotic genes such as p53 and Bax genes were markedly elevated in the ArKO ovaries as compared with those of wild-type mice. Although E(2) supplementation did not cause suppression of the elevated expression of p53 and Bax mRNAs, it caused marked enhancement of expression levels of lactoferrin and progesterone receptor mRNAs in the uteri as well as increases in uterine wet weight. At 8 months of age, ArKO mice developed haemorrhages in the ovaries, in which follicles were nearly depleted, while age-matched wild-type females still had many ovarian follicles. Furthermore, macrophage-like cells were occasionally observed in the ArKO ovarian follicles. These results suggested that targeted disruption of Cyp19 caused anovulation and precocious depletion of ovarian follicles. Additionally, analysis of mice supplemented with E(2) demonstrated that E(2) apparently supports development of ovarian follicles, although it did not restore the defect in ovulation.

Phosphorylation of MafA is essential for its transcriptional and biological properties

We previously described the identification of quail MafA, a novel transcription factor of the Maf bZIP (basic region leucine zipper) family, expressed in the differentiating neuroretina (NR). In the present study, we provide the first evidence that MafA is phosphorylated and that its biological properties strongly rely upon phosphorylation of serines 14 and 65, two residues located in the transcriptional activating domain within a consensus for phosphorylation by mitogen-activated protein kinases and which are conserved among Maf proteins. These residues are phosphorylated by ERK2 but not by p38, JNK, and ERK5 in vitro. However, the contribution of the MEK/ERK pathway to MafA phosphorylation in vivo appears to be moderate, implicating another kinase. The integrity of serine 14 and serine 65 residues is required for transcriptional activity, since their mutation into alanine severely impairs MafA capacity to activate transcription. Furthermore, we show that the MafA S14A/S65A mutant displays reduced capacity to induce expression of QR1, an NR-specific target of Maf proteins. Likewise, the integrity of serines 14 and 65 is essential for the MafA ability to stimulate expression of crystallin genes in NR cells and to induce NR-to-lens transdifferentiation. Thus, the MafA capacity to induce differentiation programs is dependent on its phosphorylation.

Investigation of G2-phase chromosomal radiosensitivity in hereditary non-polyposis colorectal cancer cells

PURPOSE

To investigate whether cells from hereditary nonpolyposis colorectal cancer (HNPCC) patients, a genetic condition characterized by constitutional mutations in DNA mismatch repair genes and associated with predisposition to colorectal carcinoma (CRC), could present a higher G2 chromosomal radiosensitivity. It is generally hypothesized that cancer predisposition in HNPCC is associated with the loss of the wild-type allele in somatic cells, resulting in defective DNA mismatch repair but, to date, no data on G2 radiosensitivity have been reported for HNPCC.

MATERIALS AND METHODS

Lymphoblastoid cell lines derived from six HNPCC patients heterozygous for MLH1, one HNPCC patient carrying a mutant MSH2 allele and three healthy controls were treated with 50 cGy of X-rays and sampled at various harvesting times, monitoring cell-cycle progression by 5-bromo-2-deoxyuridine (BrdUrd) incorporation in order to analyse chromosomal damage in the homogeneous G2 population.

RESULTS

There were no differences between lymphoblasts derived from patients in the frequency of G2 chromosomal aberrations induced by X-rays when compared with control cell lines. However, despite the absence of G2 radiosensitivity in HNPCC cells, lymphoblasts from patients heterozygous for MLH1 mutations showed a higher induction of chromatid exchanges.

CONCLUSIONS

The observed possible incorrect rejoining of double-strand breaks in MLH1 heterozygotes would be an additional and important factor contributing to loss of heterozygosity in HNPCC patients.

Mutations in apoptosis genes: a pathogenetic factor for human disease

Cell death by apoptosis is exerted by the coordinated action of many different gene products. Mutations in some of them, acting at different levels in the apoptosis process, have been identified as cause or contributing factor for human diseases. Defects in the transmembrane tumor necrosis factor receptor 1 (TNF-R1) lead to the development of familial periodic fever syndromes. Mutations in the homologous receptor Fas (also named CD95; Apo-1) are observed in malignant lymphomas, solid tumors and the autoimmune lymphoproliferative syndrome type I (ALPS I). A mutation in the ligand for Fas (Fas ligand; CD95 ligand, Apo-1 ligand), which induces apoptosis upon binding to Fas, was described in a patient with systemic lupus erythematodes and lymphadenopathy. Perforin, an other cytotoxic protein employed by T- and NK-cells for target cell killing, is mutated in chromosome 10 linked cases of familial hemophagocytic lymphohistiocytosis. Caspase 10, a representative of the caspase family of proteases, which plays a central role in the execution of apoptosis, is defect in autoimmune lymphoproliferative syndrome type II (ALPS II). The intracellular pro-apoptotic molecule bcl-10 is frequently mutated in mucosa-associated lymphoid tissue (MALT) lymphomas and various non-hematologic malignancies. The p53, an executioner of DNA damage triggered apoptosis, and Bax, a pro-apoptotic molecule with the ability to perturb mitochondrial membrane integrity, are frequently mutated in malignant neoplasms. Anti-apoptotic proteins like bcl-2, cellular-inhibitor of apoptosis protein 2 (c-IAP2) and neuronal apoptosis inhibitory protein 1 (NAIP1) are often altered in follicular lymphomas, MALT lymphomas and spinal muscular atrophy (SMA), respectively. This article reviews the current knowledge on mutations of apoptosis genes involved in the pathogenesis of human diseases and summarises the gradual transformation of discoveries in apoptosis research into benefits for the clinical management of diseases.