Effect of PGE2 on TT cells viability and division

Previous studies have shown prostaglandin E2 (PGE2) produced a marked increase in calcitonin secretion in human C-cells derived from medullary thyroid carcinoma. However, it's unclear whether PGE2 can increase the growth of C cells. In this study, we use TT cells as a C cell model to investigate the effect of PGE2 on the growth of C cells. The results revealed that both PGE2 and arachidonic acid (AA) significantly increased the count of TT cells, whereas indomethacin and Dup697 reduced this count. Notably, an increase in the level of AA was associated with an increase in the number of proliferating TT cells, indicating a dose-response relationship. PGE2 and its receptor agonists (sulprostone and butaprost) enhanced the proliferation of TT cells. By contrast, 17-phenyl-trinor-PGE2 exerted no significant effect on TT cell proliferation, whereas L161982 suppressed it. The positive effect of AA on TT cell proliferation was inhibited by indomethacin, NS398, Dup697 (complete inhibition), and SC560. Both PGE2 and AA increased the level of p-STAT5a. The positive effect of AA on p-STAT5a was completely inhibited by Dup697 but not indomethacin, NS398, or SC560. Treatment with indomethacin or Dup697 alone reduced the level of STAT5a in TT cells. AA increased the level of STAT5a, but this effect was inhibited by indomethacin, NS398, and Dup697. Overall, this study confirms the effect of PGE2 on the proliferation of TT cells. This effect is likely mediated through EP2, EP3, and EP4 receptors and associated with an increase in p-STAT5a level within TT cells.

Integration of transcriptomic and proteomic analyses reveals protective mechanisms of N-acetylcysteine in indomethacin-stimulated enterocytes

Intestinal health is critical for the growth and development of humans and animals. Our previous study has demonstrated that indomethacin (IDMT) could induce intestinal injury in piglets, and N-acetylcysteine (NAC) supplementation contributed to alleviating intestinal injury induced by various stimuli. In this study, we investigated the mechanism of IDMT-induced cell death in IPEC-1 cell lines and explored the role of NAC by using transcriptomic and proteomic analyses. Results showed that cell viability was substantially reduced with the increasing concentrations of IDMT, whereas NAC significantly increased the survival rate of IPEC-1 cells regardless of its addition method. Transcriptomics and proteomics data indicated that terms, such as cell cycle, energy metabolism, and cell proliferation, were significantly enriched by Gene ontology and pathway analyses. Flow cytometer analysis showed that IDMT induced cell cycle arrest at G0/G1 phase. The expression of cell cycle regulatory proteins (CDK1, CCNA2, and CDC45) was decreased by IDMT stimulation. Importantly, NAC treatment repaired IDMT-induced mitochondrial dysfunction by increasing ATP production, decreasing oxygen consumption rate in non-mitochondrial O₂ consumption, and increasing the red/green fluorescence ratio. IDMT stimulation significantly increased caspase-3 expression, which was partially reversed by NAC treatment. These results suggest that IDMT-induced cell death may be attributable to disturbance of the cell cycle processes, mitochondria dysfunction and apoptosis, and NAC could confer a protective effect by restoring the mitochondrial function and inhibiting the apoptosis pathway. This study provides a theoretical basis for the pathogenesis of IDMT-induced intestinal injury and guides the clinic application of NAC.

No evidence for a decreased risk of thyroid cancer in association with use of metformin or other antidiabetic drugs: a case-control study

Background

Use of metformin has been associated with a decreased cancer risk. We aimed to explore whether use of metformin or other antidiabetic drugs is associated with a decreased risk for thyroid cancer.

Methods

We conducted a case-control analysis (1995 to 2014) using the U.K.-based Clinical Practice Research Datalink (CPRD). Cases had a first-time diagnosis of thyroid cancer, six controls per case were matched on age, sex, calendar time, general practice, and number of years of active history in the database prior to the index date. We assessed odds ratios (ORs) with 95 % confidence intervals (95 % CI), adjusted for body mass index (BMI), smoking, and diabetes mellitus.

Results

In 1229 cases and 7374 matched controls, the risk of thyroid cancer associated with ever use of metformin yielded an adjusted OR of 1.48, 95 % CI 0.86–2.54. The relative risk estimate was highest in long-term (≥30 prescriptions) users of metformin (adjusted OR 1.83, 95 % CI 0.92–3.65), based on a limited number of 26 exposed cases. No such association was found in users of sulfonylurea, insulin, or thiazolidinediones (TZD). Neither a diabetes diagnosis (adjusted OR 1.17, 95 % CI 0.89–1.54), nor diabetes duration >8 years (adjusted OR 1.22, 95 % CI 0.60–2.51) altered the risk of thyroid cancer.

Conclusion

In our observational study with limited statistical power, neither use of metformin nor of other antidiabetic drugs were associated with a decreased risk of thyroid cancer.

Apoptosis induction by combination of drugs or a conjugated molecule associating non-steroidal anti-inflammatory and nitric oxide donor effects in medullary thyroid cancer models: implication of the tumor suppressor p73

BACKGROUND

Medullary thyroid cancer (MTC) is a C-cell neoplasm. Surgery remains its main treatment. Promising therapies based on tyrosine kinase inhibitors demand careful patient selection. We previously observed that two non-steroidal anti-inflammatory drugs (NSAID), indomethacin, celecoxib, and nitric oxide (NO) prevented tumor growth in a model of human MTC cell line (TT) in nude mice.

METHODS

In the present study, we tested the NO donor: glyceryl trinitrate (GTN), at pharmacological dose, alone and in combination with each of the two NSAIDs on TT cells. We also assessed the anti-proliferative potential of NO-indomethacin, an indomethacin molecule chemically conjugated with a NO moiety (NCX 530, Nicox SA) on TT cells and indomethacin/GTN association in rMTC 6-23 cells. The anti-tumoral action of the combined sc. injections of GTN with oral delivery of indomethacin was also studied on subcutaneous TT tumors in nude mice. Apoptosis mechanisms were assessed by expression of caspase-3, TAp73α, TAp73α inhibition by siRNA or Annexin V externalisation.

RESULTS

The two NSAIDs and GTN reduced mitotic activity in TT cells versus control (cell number and PCNA protein expression). The combined treatments amplified the anti-tumor effect of single agents in the two tested cell lines and promoted cell death. Moreover, indomethacin/GTN association stopped the growth of established TT tumors in nude mice. We observed a significant cleavage of full length PARP, a caspase-3 substrate. The cell death appearance was correlated with a two-fold increase in TAp73α expression, with inhibition of apoptosis after TAp73α siRNA addition, demonstrating its crucial role in apoptosis.

CONCLUSION

Association of NO with NSAID exhibited amplified anti-tumoral effects on in vitro and in vivo MTC models by inducing p73-dependent apoptotic cell death.

Aspirin Induces platelet apoptosis

Aspirin is widely used in the treatment of a number of clinical conditions. Although aspirin is being thought to be a relatively "safe" medicine, it also has some side effects, particularly the risk of bleeding which may be severe and lead to death. The mechanisms, however, are not totally understood. It has been reported recently that aspirin induces apoptosis in many cell types. Thus, the aim of the current study is to explore whether aspirin induces platelet apoptosis. The data show that mitochondrial transmembrane potential (ΔΨm) depolarizations and phosphatidylserine (PS) exposures were dose-dependently induced by aspirin in platelets. To further confirm that aspirin incurs platelet apoptosis, caspase-3 activity was measured in platelets, and the result indicated that aspirin induced caspase-3 activation. Furthermore, the mean volume of platelets incubated with aspirin was obviously reduced. Caspase inhibitor z-VAD-fmk inhibited aspirin induced apoptotic platelet shrinkage and ΔΨm depolarization, but had no effect on PS exposure. In addition, platelets incubated with cyclooxygenase inhibitor indomethacin did not incur ΔΨm depolarazation and PS exposure. Taken together, the data indicate that aspirin induces platelet apoptosis via caspase-3 activation.

Novel treatment of medullary thyroid cancer

PURPOSE OF REVIEW

Metastatic medullary thyroid cancer (MTC) is an incurable disease once metastasis becomes unresectable. Many therapeutic drugs and methods have been tried to circumvent this difficulty. We review currently published treatments and hope for future developments of more effective treatment methods.

RECENT FINDINGS

Motesanib, vandetanib, axitinib (tyrosine kinase inhibitors), and XL184 (multikinase inhibitor) have been shown to achieve partial response or stable disease state of metastatic MTC. Sunitinib and sorafenib, currently available tyrosine kinase inhibitors, can also be tried for patients with MTC. However, these medications are not curative and do not improve survival rate. Only carcinoembryonic antigen-I-iodine-based radioimmunotherapy improved survival of a subset of patients with a very aggressive type of MTC. Drugs currently available for possible use of MTC treatment include bortezomib (proteasome inhibitor), valproic acid (histone deacetylase inhibitor), capecitabine (5-fluorouracil prodrug), and indomethacin (NSAID), although clinical studies have yet to be done. Cardiac natriuretic hormones and an extract of the plant Cautleya gracilis are new agents to be studied for MTC.

SUMMARY

Kinase inhibitors are the first drugs showing some efficacy in MTC. To improve survival, unconventional drugs or other therapies with or without kinase inhibitors need to be considered.

Multiple endocrine neoplasia type 2

Multiple endocrine neoplasia type 2 (MEN 2) is an autosomal dominantly inherited tumor syndrome subclassified into three distinct syndromes: MEN 2A, MEN 2B and familial medullary thyroid carcinoma. In MEN 2 families, medullary thyroid carcinoma, pheochromocytomas and parathyroid adenomas occur with a variable frequency, also depending on the specific genetic defect involved. In 1993, the responsible MEN2 gene was identified. The genetic defect in these disorders involves the RET proto-oncogene on chromosome 10. The germline RET mutations result in a gain-of-function of the RET protein. Extensive studies on large families revealed that there is a strong genotype-phenotype correlation. In this review, guidelines for early diagnosis, including MEN2 gene mutation analysis, and treatment, including preventive surgery, periodic and clinical monitoring, have been formulated, enabling improvement of life expectancy and quality of life. Identification of the RET protein has also provided new insights into its function, and the specific pathways it effects involved in cell proliferation, migration, differentiation and survival. In the near future, identification of biological tumor markers will enable target-directed intervention and may prevent and/or delay progression of both primary and residual tumor growth.

Rb Regulates DNA damage response and cellular senescence through E2F-dependent suppression of N-ras isoprenylation

Oncogene-induced cellular senescence is well documented, but little is known about how infinite cell proliferation induced by loss of tumor suppressor genes is antagonized by cellular functions. Rb heterozygous mice generate Rb-deficient C cell adenomas that progress to adenocarcinomas following biallelic loss of N-ras. Here, we demonstrate that pRb inactivation induces aberrant expression of farnesyl diphosphate synthase, many prenyltransferases, and their upstream regulators sterol regulatory element-binding proteins (SREBPs) in an E2F-dependent manner, leading to enhanced isoprenylation and activation of N-Ras. Consequently, elevated N-Ras activity induces DNA damage response and p130-dependent cellular senescence in Rb-deficient cells. Furthermore, Rb heterozygous mice additionally lacking any of Ink4a, Arf, or Suv39h1 generated C cell adenocarcinomas, suggesting that cellular senescence antagonizes Rb-deficient carcinogenesis.