Anti-thyroglobulin antibodies do not significantly increase the risk of finding iodine avid metastases on post-radioactive iodine ablation scan in low-risk thyroid cancer patients.

OBJECTIVE: Post-operative thyroglobulin (Tg) levels can predict the likelihood of residual cancer, including distant metastases, thereby influencing postsurgical treatment strategies even in patients with low-risk disease. Circulating anti-thyroglobulin antibodies (anti-Tg Abs) interfere with Tg measurement preventing this clinical use. It is not known if the presence of anti-Tg Abs predicts metastatic disease on post-therapy scan in patients with low-risk disease or if they should influence the use or dose of I-131 therapy. In the present study, we compare post-therapy scans in low-risk patients with and without anti-Tg Abs. METHODS: This is a single-institution retrospective study. The study population (Group A) included all patients with low-risk differentiated thyroid cancer (DTC) who underwent total thyroidectomy and RAI between 1/1/2006 to 9/11/2015 with intrathyroidal T1-T2, Nx, N0 or N1a (≤5 nodes all measuring, when reported, <2 mm) that had anti-thyroglobulin antibodies. Patients were excluded if they had known distant metastases and/or extensive vascular invasion. A second group of patients (Group B) treated during the same period but without anti-Tg antibodies was selected to match group A by propensity core matching with a logistic regression model. RESULTS: Each group included 37 patients. In group A: Median age was 40 years, 86% female and 76% PTC. Median tumor size was 2 cm (0.2-3.8), 32% had multifocal disease, 16% were N1a and 4% had vascular invasion. Parameters in group B were not statistically different from Group A, as expected based on the selection criteria, except being less likely to have Hashimoto's thyroiditis on pathology (p < 0.001). Post-therapy scan results were compared by Chi-square test with 86% negative post therapy scan frequency in group A and 92% in group B without evidence of a difference (p = 0.45). CONCLUSION: In patients with low-risk DTC, anti-Tg Abs did not significantly predict metastatic disease on post-therapy scan. If confirmed, these data suggest that the presence of anti-Tg Abs alone should not influence initial therapy in patients with low-risk DTC.

Occlusion in the Flow of New Drugs for Cardiovascular Disease.

There is a large misalignment between unmet need and both private and public investment activity in cardiovascular disease. In this paper, we quantify the magnitude of the gap, analyze a range of potential root causes in two main categories (issues of feasibility and valuation), and propose steps toward solutions to close the gap.

Precision medicine in the age of big data: The present and future role of large-scale unbiased sequencing in drug discovery and development.

High throughput molecular and functional profiling of patients is a key driver of precision medicine. DNA and RNA characterization has been enabled at unprecedented cost and scale through rapid, disruptive progress in sequencing technology, but challenges persist in data management and interpretation. We analyze the state-of-the-art of large-scale unbiased sequencing in drug discovery and development, including technology, application, ethical, regulatory, policy and commercial considerations, and discuss issues of LUS implementation in clinical and regulatory practice.

Analysis of exosome release as a cellular response to MAPK pathway inhibition.

Exosome size distributions and numbers of exosomes released per cell are measured by asymmetric flow-field flow fractionation/multi-angle light scattering (A4F/MALS) for three thyroid cancer cell lines as a function of a treatment that inhibits MAPK signaling pathways in the cells. We show that these cell lines release exosomes with well-defined morphological features and size distributions that reflect a common biological process for their formation and release into the extracellular environment. We find that those cell lines with constitutive activation of the MAPK signaling pathway display MEK-dependent exosome release characterized by increased numbers of exosomes released per cell. Analysis of the measured exosome size distributions based on a generalized extreme value distribution model for exosome formation in intracellular multivesicular bodies highlights the importance of this experimental observable for delineating different mechanisms of vesicle formation and predicting how changes in exosome release can be modified by pathway inhibitors in a cell context-dependent manner.

Akt1 deficiency delays tumor progression, vascular invasion, and distant metastasis in a murine model of thyroid cancer.

Akt activation is common in progressive thyroid cancer. In breast cancer, Akt1 induces primary cancer growth, but is reported to inhibit metastasis in vivo in several model systems. In contrast, clinical and in vitro studies suggest a metastasis-promoting role for Akt1 in thyroid cancer. The goal of this study was to determine the functional role of Akt1 in thyroid cancer growth and metastatic progression in vivo using thyroid hormone receptor (TR) ß(PV/PV) knock-in (PV) mice, which develop metastatic thyroid cancer. We crossed Akt1(-/-) and PV mice and compared tumor development, local progression, metastasis and histology in TRß(PV/PV)/Akt1(+/+) (PVPV-Akt1WT) and TRß(PV/PV)/Akt1(-/-) (PVPV-Akt1KO) mice. Mice were killed at 3, 6, 9, 12 and 15 months; necropsy was performed and serum thyroid stimulating hormone (TSH) was measured. Thyroid hyperplasia occurred in both groups beginning at 3 months; the thyroid size was greater in the PVPV-Akt1WT mice (P<0.001). In comparison with PVPV-Akt1WT mice, thyroid cancer development was delayed in the PVPV-Akt1KO mice (P=0.003) and the degree of tumor invasiveness was reduced. The PVPV-Akt1WT mice displayed pulmonary metastases at 12 and 15 months of age, by contrast PVPV-Akt1KO mice did not develop distant metastases at 15 months of age. Despite continued expression of Akt2 or Akt3, pAkt levels were decreased and there was evidence of reduced Akt effect on p27 in the PVPV-Akt1KO thyroids. TSH levels were similarly elevated in PV mice regardless of Akt1 expression. In conclusion, thyroid cancer development and progression in TR ß(PV/PV) mice are Akt1-dependent, consistent with a tumor progression-promoting role in this murine thyroid cancer model.

Targeting BRAF in thyroid cancer.

Activating mutations in the gene encoding BRAF are the most commonly identified oncogenic abnormalities in papillary thyroid cancer. In vitro and in vivo models have demonstrated that overexpression of activated BRAF induces malignant transformation and aggressive tumour behaviour. BRAF and other RAF kinases are frequently activated by other thyroid oncogenes and are important mediators of their biological effects including dedifferentiation and proliferation. Because current therapeutic options for patients with thyroid cancers that are aggressive and/or do not respond to standard therapies are limited, BRAF and its downstream effectors represent attractive therapeutic targets. In this review, data supporting a role for BRAF activation in thyroid cancer development and establishing the potential therapeutic efficacy of BRAF-targeted agents in patients with thyroid cancer will be reviewed.

Beyond peroxisome proliferator-activated receptor gamma signaling: the multi-facets of the antitumor effect of thiazolidinediones.

Certain members of the thiazolidinedione (TZD) family of the peroxisome proliferator-activated receptor gamma (PPARgamma) agonists, such as troglitazone and ciglitazone, exhibit antitumor activities; however, the underlying mechanism remains inconclusive. Substantial evidence suggests that the antiproliferative effect of these TZD members in cancer cells is independent of PPARgamma activation. To discern the role of PPARgamma in the antitumor effects of TZDs, we have synthesized PPARgamma-inactive TZD analogs which, although devoid of PPARgamma activity, retain the ability to induce apoptosis with a potency equal to that of their parental TZDs in cancer cell lines with varying PPARgamma expression status. Mechanistic studies from this and other laboratories have further suggested that troglitazone and ciglitazone mediate antiproliferative effects through a complexity of PPARgamma-independent mechanisms. Evidence indicates that troglitazone and ciglitazone block BH3 domain-mediated interactions between the anti apoptotic Bcl-2 (B-cell leukemia/lymphoma 2) members Bcl-2/Bcl-xL and proapoptotic Bcl-2 members. Moreover, these TZDs facilitate the degradation of cyclin D1 and caspase-8-related FADD-like IL-l-converting enzyme (FLICE)-inhibitory protein through proteasome-mediated proteolysis, and down-regulate the gene expression of prostate-specific antigen gene expression by inhibiting androgen activation of the androgen response elements in the promoter region. More importantly, dissociation of the effects of TZDs on apoptosis from their original pharmacological activity (i.e. PPARgamma activation) provides a molecular basis for the exploitation of these compounds to develop different types of molecularly targeted anticancer agents. These TZD-derived novel therapeutic agents, alone or in combination with other anticancer drugs, have translational relevance in fostering effective strategies for cancer treatment.

ret/PTC1 and ret/PTC3 in thyroid tumors from Chernobyl liquidators: comparison with sporadic tumors from Ukrainian and French patients.

Like children exposed to Chernobyl fallout, the workers who cleaned up after the accident, also known as liquidators, have exhibited an increased incidence of thyroid cancer. A high prevalence of ret/PTC3 rearrangement has been found in pediatric post-Chernobyl thyroid tumors, but this feature has not been investigated in liquidator thyroid tumors. In this study we analyzed the prevalence of ret/PTC1 and ret/PTC3 in thyroid tumors from 21 liquidators, 31 nonirradiated adult Ukrainian patients, and 34 nonirradiated adult French patients. ret rearrangements in carcinomas were found in 83.3% of liquidators, 64.7% of Ukrainian patients, and 42.9% of French patients. The prevalence of ret/PTC1 was statistically similar in the three groups. The prevalence of ret/PTC3 was significantly higher in liquidators than in French patients (P = 0.03) but it was also high in nonirradiated Ukrainian patients who exhibited values intermediate between liquidators and French patients. In adenomas the prevalence of rearrangement was significantly higher in all Ukrainians than in French patients (P = 0.004). Like children exposed to Chernobyl fallout, liquidators showed a high prevalence of ret/PTC3. This finding suggests that irradiation had the same effect regardless of age. However, given the high rate of ret/PTC3 in nonirradiated adult Ukrainians, the possibility of genetic susceptibility or low-level exposure to radiation in that group cannot be excluded.

Hepatocytes cultured in alginate microspheres: an optimized technique to study enzyme induction.

An important application of hepatocyte cultures is identification of drugs acting as inducers of biotransformation enzymes that alter metabolic clearance of other therapeutic agents. In the present study we optimized an in vitro system with hepatocytes cultured in alginate microspheres that allow studies of enzyme induction with excellent sensitivity. Induction factors obtained with standard inducers, such as 3-methylcholanthrene or phenobarbital, were higher compared to those with conventional hepatocyte co-cultures on collagen coated dishes. This is illustrated by activities of 7-ethoxyresorufin-O-deethylase (EROD) after incubation with 5 microM 3-methylcholanthrene (3-MC), a standard inducer for cytochrome P4501A1 and 1A2. Mean activities for solvent controls and 3-MC exposed cells were 2.99 and 449 pmol/min/mg protein (induction factor: 150) for hepatocytes cultured in microspheres compared to 2.72 and 80.6 pmol/min/mg (induction factor: 29.6) for hepatocytes on collagen coated dishes. To compare these in vitro data to the in vivo situation male Sprague Dawley rats, the same strain that was used also for the in vitro studies, were exposed to 3-MC in vivo using a protocol that guarantees maximal induction. Activities were 29.2 and 1656 pmol/min/mg in liver homogenate of solvent and 3-MC treated animals (induction factor: 56.7). Thus, the absolute activities of 3-MC exposed hepatocytes in microspheres are lower compared to the in vivo situation. However, the induction factor in vitro was even higher compared to the in vivo situation (150-fold versus 56.7-fold). A similar scenario was observed using phenobarbital (0.75 mM) for induction of CYP2B and 3A isoenzymes: induction factors for testosterone hydroxylation in position 16beta were 127.5- and 50.4-fold for hepatocytes in microspheres and conventionally cultured hepatocytes, respectively. The new in vitro system with hepatocytes embedded in solid alginate microspheres offers several technical advantages: (i) the solid alginate microspheres can be liquefied within 60s, allowing a fast and complete harvest of hepatocytes; (ii) alginate capsules are stable allowing transport and mechanical stress; (iii) high numbers of hepatocytes can be encapsulated in short periods; (iv) defined cell numbers between 600 hepatocytes, the approximate number of cells in one capsule, and 18 x 10(6) hepatocytes, the number of hepatocytes in 6 ml alginate, can be transferred to a culture dish or flask. Thus, encapsulated hepatocytes allow a flexible organization of experiments with respect to cell number. In conclusion, we optimized a technique for encapsulation of hepatocytes in alginate microspheres that allows identification of enzyme induction with an improved sensitivity compared to existing systems.

Sida micrantha mosaic is associated with a complex infection of begomoviruses different from Abutilon mosaic virus.

We report on the nucleotide sequences of geminiviruses of the genus Bemogovirus infecting Sida micrantha Schr., a common weed in Brazil. For decades, the mosaic frequently associated with Sida plants was considered to be caused by a Brazilian strain of Abutilon mosaic virus (AbMV). By infection studies and sequence comparisons, we demonstrate that it is associated with a complex of at least two begomoviruses as different from AbMV as most South American geminiviruses. Two molecules of DNA A (A1, A2) and three of DNA B (B1, B2, B3) were cloned and sequenced. According to the high homology in their common regions, DNA A1 and DNA B3, as well as DNA A2 and DNA B2, are cognate components of two begomoviruses, which were infectious in Nicotiana benthamiana plants. No trans-replication was found for any other A/B combination. The intergenic region of DNA B2 appears to be the product of the recombination between DNA B1 and DNA A2. These results show that a coinfection of begomoviruses can persist over decades, producing a reservoir of partially recombined but distinct geminiviruses.

Controversies in the follow-up and management of well-differentiated thyroid cancer.

Thyroid cancer is a common malignancy with an apparent increasing incidence and a wide spectrum of clinical behavior and therapeutic responsiveness. Recent advances in diagnosis, primary treatment, and long-term monitoring have led to enhanced detection of primary and recurrent disease and improvements in therapy. Controversy still surrounds several issues: the most accurate predictive staging system and histological subclassification scheme, optimal preoperative assessment and surgical extent, appropriate use of radioiodine for remnant ablation, goal for thyrotropin-suppressive thyroid hormone therapy, best practices in immediate postoperative and long-term monitoring, and approach to the patient with thyroglobulin evidence of residual disease. In this paper, recent data related to these controversial issues are critically reviewed.

BRAF T1796A transversion mutation in various thyroid neoplasms.

A high prevalence of activating mutation of the B type Raf kinase (BRAF) gene was recently reported in papillary thyroid cancer (PTC). However, the frequency of this mutation in several other types of thyroid neoplasms was not thoroughly investigated. In the present study, in addition to PTC, we evaluated various thyroid tumor types for the most common BRAF T1796A mutation by direct genomic DNA sequencing. We found a high and similar frequency (45%) of the BRAF T1796A mutation in two geographically distinct PTC patient populations: one composed of sporadic cases from North America, and the other from Kiev, Ukraine, that included individuals who were exposed to the Chernobyl nuclear accident. In contrast, we found BRAF mutation in only 20% of anaplastic thyroid cancers and no mutation in medullary thyroid cancers and benign thyroid hyperplasia. We also confirmed previous reports that the BRAF T1796A mutation did not occur in benign thyroid adenomas and follicular thyroid cancers. Specific analysis of the Ukraine patients with confirmed history of radiation exposure failed to show a higher incidence of BRAF mutation. Our results suggest that frequent occurrence of BRAF mutation is inherently associated with PTC, irrespective of geographic origin, and is apparently not a radiation-susceptible mutation. The lack or low prevalence of BRAF mutation in other thyroid neoplasms is consistent with the notion that other previously defined genetic alterations on the same signaling pathway are sufficient to cause tumorigenesis in most thyroid neoplasms.

Metabolism of propafenone and verapamil by cryopreserved human, rat, mouse and dog hepatocytes: comparison with metabolism in vivo.

In the present study we examined the metabolism of [(14)C]propafenone (P) and [(14)C]verapamil (V) using cryopreserved human, dog (Beagle), rat (Sprague-Dawley) and mouse (NMRI) hepatocytes. The percentage ratios of the metabolites were identified after extraction by HPLC with UV and radioactivity detection. Phase-II metabolites were cleaved using beta-glucuronidase. Metabolism of the drugs by cryopreserved hepatocytes was compared with that in the respective species in vivo. All phase-I and -II metabolites known from in vivo experiments: 5-hydroxy-P (5-OH-P); 4'-hydroxy-P (4'-OH-P); N-despropyl-P (NdesP) and the respective glucuronides, were identified after incubation with cryopreserved hepatocytes. Interspecies differences were observed concerning the preferential position of propafenone hydroxylation: 5-OH-P made up 91, 51, 16 and 3% of the total metabolites after incubation with cryopreserved human ( n=4), dog ( n=3), rat ( n=3) and mouse ( n=4) hepatocytes respectively. These results are consistent with interspecies differences known from in vivo experiments. The metabolism of V is more complex than that of P. Nevertheless, all phase-I metabolites known from in vivo experiments and the expected glucuronides were identified after incubation with cryopreserved hepatocytes from all four species. As expected from the results of in vivo experiments, there were no major interspecies differences with respect to phase-I metabolites although the conjugation of verapamil phase-I metabolites by cryopreserved canine hepatocytes was much weaker than for the other species. In conclusion, phase-I and phase-II metabolism of P and V was evaluated using hepatocytes in vitro. All of the relevant interspecies differences known from in vivo experiments were identified after short-term incubation with cryopreserved hepatocytes in suspension.

Akt activation and localisation correlate with tumour invasion and oncogene expression in thyroid cancer.

INTRODUCTION: Akt activation is involved in the pathogenesis of inherited thyroid cancer in Cowden's syndrome and in sporadic thyroid cancers. In cell culture, Akt regulates thyroid cell growth and survival; but recent data suggest that Akt also regulates cell motility in non-thyroid cell lines. We therefore sought to evaluate the role of Akt in thyroid cancer progression. METHODS: We evaluated 46 thyroid cancer, 20 thyroid follicular adenoma, and adjacent normal tissues samples by immunohistochemistry for activated Akt (pAkt), Akt 1, 2, and 3, and p27 expression. Immunoblots were performed in 14 samples. RESULTS: Akt activation was identified in 10/10 follicular cancers, 26/26 papillary cancers, and 2/10 follicular variant of papillary cancers, but in only 4/66 normal tissue samples and 2/10 typical benign follicular adenomas. Immunoactive pAkt was greatest in regions of capsular invasion; and was localised to the nucleus in follicular cancers and the cytoplasm in papillary cancers, except for invasive regions of papillary cancers where it localised to both compartments. Immunoactive Akt 1, but not Akt 2 or Akt 3, correlated with pAkt localisation, and nuclear pAkt was associated with cytoplasmic expression of p27. In vitro studies using human thyroid cancer cells demonstrated that nuclear translocation of Akt 1 and pAkt were associated with cytoplasmic p27 and cell invasion and migration. Cell migration and the localisation of Akt 1, pAkt, and p27 were inhibited by PI3 kinase, but not MEK inhibition. DISCUSSION: These data suggest an important role for nuclear activation of Akt 1 in thyroid cancer progression.

Size of pancreatic islets of Langerhans: a key parameter for viability after cryopreservation.

Large amounts and excellent viabilities of pancreatic islets are prerequisites for recent advances in islet transplantation. Cryopreservation has been shown to enlarge transplanted cell mass, but has been accompanied by reduced viability. In this study rat pancreatic islets were differentiated into small (<200 micro m), medium (200-400 micrometers) and large (>400 micrometers) categories and their susceptibilities to different freezing conditions were evaluated: concentration of cryoprotectant (0.7-3.1 M), equilibration (15 vs. 45 min, 22 degrees C vs. on ice) and post-thaw removal of cryoprotectant (15 vs. 30 min, stepwise vs. one-step). The most prominent finding was a negative correlation between islet size and viability observed in non-frozen islets to a minor degree (r=-0.44) and significantly enhanced after cryopreservation (r<-0.8). The concentration of cryoprotectant showed the most significant influence on viability affecting small, medium and large islets. Different techniques of equilibration with the cryoprotectant resulted in significant changes of islet viability of medium islets, whereas small and large islets were unaffected. For different techniques of removal of the cryoprotectant, no significant influence on viabilities was found. We conclude that large islets represented a highly susceptible population concerning damage due to cryopreservation.

Measurement of thyroglobulin mRNA in peripheral blood as an adjunctive test for monitoring thyroid cancer.

AIMS: Monitoring treated patients with thyroid cancer for recurrent or metastatic disease is currently based upon the serial measurement of circulating plasma thyroglobulin (Tg) concentrations. However, the clinical usefulness of Tg immunoassays is limited by poor sensitivity and interference from anti-Tg antibodies. This study investigated whether the detection of Tg mRNA in peripheral blood, using reverse transcriptase polymerase chain reaction (RT-PCR), is of value in the biochemical surveillance of patients with thyroid cancer. METHODS: RNA was extracted from peripheral blood of five normal controls, six patients with abnormal thyroid function tests, and 28 patients who had undergone thyroidectomy for well differentiated thyroid cancer. From each, an 87 bp product from base pair 262 to 348 in the cDNA sequence of the thyroglobulin gene was amplified by RT-PCR. RESULTS: Tg mRNA was detected in normal individuals and patients with thyroid cancer. In the group of patients studied, identification of metastatic thyroid tissue by radioiodine scanning correlated better with Tg mRNA assay results than with serum Tg concentrations (accuracy 84% v 75%). No interference from circulating Tg antibodies was apparent. In patients studied prospectively over a 12 month period, there was a significant correlation between detectable Tg mRNA in peripheral blood and the presence or absence of metastatic disease, as demonstrated by radioiodine scanning. CONCLUSIONS: These results suggest that detection of Tg mRNA in blood is a more sensitive marker for metastatic thyroid disease than Tg immunoassay, and appears to be unaffected by the presence of circulating anti-Tg antibodies.

Permissive and suppressive effects of dexamethasone on enzyme induction in hepatocyte co-cultures.

1. Steroids are known to act as permissive factors in hepatocytes. This study shows that dexamethasone (DEX) is a permissive factor for induction of CYP2B1/2, CYP3A1, CYP2A1 and probably also CYP2C11 in cultures with primary rat hepatocytes. 2. The induction factor of phenobarbital (PB)-induced formation of 16beta-hydroxytestosterone (OHT), a testosterone biotransformation product predominantly formed by CYP2B1, is increased 18-fold by the addition of 32 nM DEX to the culture medium. Interestingly, higher concentrations of DEX up to 1000 nM led to a concentration-dependent maximally 5-fold decrease (p = 0.002) of phenobarbital-induced 16beta-OHT formation compared with the effect observed with 32 nM DEX. Thus, DEX shows permissive and suppressive effects on enzyme induction depending on the concentration of the glucocorticoid. 3. Qualitatively similar but smaller permissive and suppressive effects of DEX were observed for PB-induced CYP3A1 activity as evidenced by formation of 2beta-, 6beta- and 15beta-OHT. 4. DEX is a permissive factor for induction of CYP2A1 activity by 3-methylcholanthrene (3MC), as evidenced by the formation of 7alpha-OHT. Without addition of DEX, 3MC did not induce formation of 7alpha-OHT, whereas an almost 3-fold induction occurred in the presence of DEX. In contrast to CYP2B and CYP3A, concentrations up to 1000 nM DEX were not suppressive for the induction of CYP2A1. 5. We described recently a technique that allows preparation of cultures from cryopreserved hepatocytes. An almost identical influence of dexamethasone on enzyme induction was observed here in cultures from cryopreserved compared with freshly isolated hepatocytes. 6. Cultures with primary hepatocyte cultures represent a well-established technique for the study of drug-drug interactions. However, a large interlaboratory variation is known. Our study provides evidence that differences in glucocorticoid concentration in the culture medium contribute to this variation.

Downregulation of beta2-microglobulin in human cord blood somatic stem cells after transplantation into livers of SCID-mice: an escape mechanism of stem cells?

Adherently growing, non-hematopoietic somatic stem cells isolated from human cord blood were stained with the fluorescent dye PKH26 and transplanted into livers of SCID-mice to examine a possible cell fate transition. Already 7 days after transplantation stem cells were well integrated into the liver tissue. Human albumin that was not expressed by the stem cells before transplantation was detectable in the host's livers after injection of cord blood stem cells. Human alpha1-antitrypsin was detectable in stem cells already before transplantation and remained positive in the mouse liver. The most interesting observation in this study was the downregulation of human beta2-microglobulin (beta2M) in the stem cells after transplantation: beta2M is expressed constitutively in our cord blood stem cells. However, beta2M was no longer detectable by RT-PCR in all tissues where human albumin and alpha1-antitrypsin were expressed after stem cell transplantation. beta2M is known to participate as an integral part of the major histocompatibility complex. Absence of beta2M makes the residual heavy chain inactive as an antigen. Thus, downregulation of beta2M may represent an escape mechanism from killer-T cells and may be a molecular mechanism explaining the recently described "immunological blindness" [37] of stem cells. In contrast to the results obtained after direct injection of stem cells as a suspension, no consistent downregulation of beta2M was observed after transplantation of stem cells encapsulated in alginate beads to generate a compartment where stem cells are protected from the host's natural killer cells. No expression of human genes was observed after transplantation of human cord blood derived mononuclear cells (MNC) that were used as a negative control. In conclusion, we have shown that human cord blood somatic stem cells survive and are reprogrammed after transplantation into mouse livers, although a complete transdifferentiation to hepatocytes did not occur within 7 days, since some marker genes (GATA4 and alpha-fetoprotein) were still negative. Switching off expression of beta2M may be part of an intriguing and novel mechanism explaining why stem cells escape the host's immune system.

Sudden enlargement of local recurrent thyroid tumor after recombinant human TSH administration.

Chronic endogenous TSH stimulation of neoplastic tissue has been reported to stimulate tumor enlargement. However, little is known about changes in normal and neoplastic thyroid tissue after sudden rather than chronic stimulation with TSH. Acute thyroidal tissue reactions, reflected by rapid tumor expansion and/or possible vascular changes, have been reported to occur after bovine TSH stimulation and, more recently, after recombinant human TSH (rhTSH). In this report, we describe two patients with papillary thyroid carcinoma with local recurrent tumor. Both patients developed tumor growth 12-48 h after the second rhTSH injection, reflected by acute respiratory distress or a palpable, tender mass. In both situations, the enlargement was documented by imaging techniques, showing tumor expansion compared with previous examinations. Rapid improvement with glucocorticoid supports inflammation as the likely etiology. Based on these cases, and other reports of rapid tumor expansion after rhTSH injection, we recommend glucocorticoid coverage before rhTSH administration for patients with known or suspected neoplasia located in a limited space.

Overexpression and overactivation of Akt in thyroid carcinoma.

Enhanced activation of Akt occurs in Cowden's disease, an inherited syndrome of follicular thyroid, breast, colon, and skin tumors, via inactivation of its regulatory protein, PTEN. Whereas PTEN inactivation is uncommon in sporadic thyroid cancer, activation of growth factor pathways that signal through Akt is frequently identified. We hypothesized that Akt overactivation could be a common finding in sporadic thyroid cancer and might be important in thyroid cancer biology. We examined thyroid cancer cells lines and benign and malignant thyroid tissue for total Akt activation and isoform-specific Akt expression. In thyroid cancer cells, Akt 1, 2, and 3 proteins were expressed, total Akt was activated by insulin phosphatidylinositol 3'-kinase, and inhibition of phosphatidylinositol 3'-kinase reduced cell viability. In human thyroid tissue, increased levels of phosphorylated total Akt were identified in follicular but not papillary cancers compared with normal tissue. Levels of Akt 1 and 2 proteins and Akt 2 RNA were elevated only in the follicular cancers. In paired samples, Akt 1, 2, 3, and phospho-Akt levels were higher in five of six cancers, including three of three follicular cancers. These data suggest that Akt activation may play a role in the pathogenesis or progression of sporadic thyroid cancer.