Systemic and metabolic effects of PDE5-inhibitor drugs

A Review of Antidiabetic Medicinal Plants as a Novel Source of Phosphodiesterase Inhibitors: Future Perspective of New Challenges Against Diabetes Mellitus

Intracellular glucose concentration plays a crucial role in initiating the molecular secretory process of pancreatic β-cells through multiple messengers and signaling pathways. Cyclic nucleotides are key physiological regulators that modulate pathway interactions in β -cells. An increase of cyclic nucleotides is controled by hydrolysed phosphodiesterases (PDEs), which degrades cyclic nucleotides into inactive metabolites. Despite the undeniable therapeutic potential of PDE inhibitors, they are associated with several side effects. The treatment strategy for diabetes based on PDE inhibitors has been proposed for a long time. Hence, the world of natural antidiabetic medicinal plants represents an ideal source of phosphodiesterase inhibitors as a new strategy for developing novel agents to treat diabetes mellitus. This review highlights medicinal plants traditionally used in the treatment of diabetes mellitus that have been proven to have inhibitory effects on PDE activity. The contents of this review were sourced from electronic databases, including Science Direct, PubMed, Springer Link, Web of Science, Scopus, Wiley Online, Scifinder and Google Scholar. These databases were consulted to collect information without any limitation date. After comprehensive literature screening, this paper identified 27 medicinal plants that have been reported to exhibit anti-phosphodiesterase activities. The selection of these plants was based on their traditional uses in the treatment of diabetes mellitus. The review emphasizes the antiphosphodiesterase properties of 31 bioactive components derived from these plant extracts. Many phenolic compounds have been identified as PDE inhibitors: Brazilin, mesozygin, artonin I, chalcomaracin, norartocarpetin, moracin L, moracin M, moracin C, curcumin, gallic acid, caffeic acid, rutin, quercitrin, quercetin, catechin, kaempferol, chlorogenic acid, and ellagic acid. Moreover, smome lignans have reported as PDE inhibitors: (+)-Medioresinol di-O-β-d-glucopyranoside, (+)- Pinoresinol di-O-β-d-glucopyranoside, (+)-Pinoresinol-4-O-β-d-glucopyranosyl (1→6)-β-dglucopyranoside, Liriodendrin, (+)-Pinoresinol 4'-O-β-d-glucopyranoside, and forsythin. This review provides a promising starting point of medicinal plants, which could be further studied for the development of natural phosphodiesterase inhibitors to treat diabetes mellitus. Therefore, it is important to consider clinical studies for the identification of new targets for the treatment of diabetes.

Feasibility of high-dose tadalafil and effects on insulin resistance in well-controlled patients with type 2 diabetes (MAKROTAD): a single-centre, double-blind, randomised, placebo-controlled, cross-over phase 2 trial

Background

Phosphodiesterase-5 inhibitors exert positive vascular and metabolic effects in type 2 diabetes (T2D), but the effect on insulin resistance in T2D is unclear.

Methods

This randomised, double blind, placebo-controlled, two-period crossover trial was conducted at Sahlgrenska University Hospital (Gothenburg, Sweden). Men without apparent erectile dysfunction (age 40-70 years) and women (age 55-70 years, post-menopause) diagnosed with T2D between 3 months and 10 years, haemoglobin A1c (HbA1c) < 60 mmol/mol and a body mass index (BMI) 27-40 kg/m² were enrolled. Participants were randomly assigned to one period of oral tadalafil 20 mg once a day and one period of placebo for 6 weeks, separated by an 8-week wash-out period. Placebo and tadalafil tablets were made visually indistinguishable and delivered randomized in two separate boxes for each participant. Both treatment periods ended with a glucose clamp, and measurements of body composition and metabolic markers in blood, subcutaneous and muscular interstitial fluid. The primary aim was to assess difference in whole-body insulin resistance after 6-weeks of treatment, determined after completion of the two study arms, and secondary aims were to study effects of tadalafil on pathophysiology of T2D as well as tolerability of high-dose tadalafil in T2D. Primary analysis was performed in participants with full analysis set (FAS) and safety analysis in all participants who received at least one dose of study medication. This trial is registered with ClinicalTrials.gov (NCT02601989), and EudraCT (2015-000573).

Findings

Between January 22nd, 2016, and January 31st, 2019, 23 participants with T2D were enrolled, of whom 18 were included in the full analysis set. The effect of tadalafil on insulin resistance was neutral compared with placebo. However, tadalafil decreased glycaemia measured as HbA1c (mean difference -2.50 mmol/mol, 95% confidence interval (CI), -4.20; -0.78, p = 0.005), and, further, we observed amelioration of endothelial function and markers of liver steatosis and glycolysis, whereas no statistically significant differences of other clinical phenotyping were shown. Muscle pain, dyspepsia, and headache were more frequent in participants on high-dose tadalafil compared with placebo (p < 0.05) but no difference between treatments appeared for serious adverse events.

Interpretation

High-dose tadalafil does not decrease whole-body insulin resistance, but increases microcirculation, induces positive effects in the liver and in intermediate metabolites, in parallel with an improved metabolic control measured as HbA1c. High-dose tadalafil is moderately well tolerated, warranting larger trials to define the optimal treatment regimen in T2D.

Funding

The Swedish Research Council, Swedish Diabetes Foundation, Novo Nordisk Foundation, the Swedish state under the agreement between the Swedish government and the county councils, the ALF-agreement, Sahlgrenska University Hospital funds, Gothenburg Society of Medicine, Eli Lilly & Company, USA, and Eli Lilly & Company, Sweden AB.

Effect of low-dose tadalafil once daily on glycemic control in patients with type 2 diabetes and erectile dysfunction: a randomized, double-blind, placebo-controlled pilot study

BACKGROUND

Phosphodiesterase type 5 inhibitors restore nitric oxide signaling, that plays a significant role in erectile function, and appears to counteract insulin resistance in animal and human models. This study was aimed to evaluate the glycemic and metabolic effects of low-dose tadalafil once daily in patients with type 2 diabetes and erectile dysfunction.

METHODS

A 6-month, randomized, double-blind, placebo-controlled pilot trial was conducted. Eligible patients were randomly assigned in a ratio of 2:1 to the tadalafil 5 mg and placebo groups; all patients received either tadalafil or placebo once a day. The primary efficacy endpoint was the absolute change in glycated hemoglobin (HbA1c) levels during the 6-month study period. The secondary efficacy endpoints included metabolic parameters and erectile function.

RESULTS

Of the 68 patients who completed this study, 45 and 23 patients were allocated to the tadalafil and placebo groups, respectively. The mean HbA1c level was significantly different between the groups over the 6-month study period (P = 0.021). After 6 months of treatment, the HbA1c decrement in the tadalafil group was greater than that in the placebo group (- 0.14 ± 0.53% vs. 0.20 ± 0.69%, P = 0.030). The International Index of Erectile Function-5 scores improvement was significantly greater in the tadalafil group than in the placebo group at 6 months (P = 0.003).

CONCLUSION

This prospective pilot study showed that low-dose tadalafil administered once a day was effective in improving glycemic control and erectile function in patients with type 2 diabetes and erectile dysfunction. Trial registration KCT0005666.

PRMT5 regulates RNA m6A demethylation for doxorubicin sensitivity in breast cancer

Cancer cells respond to various stressful conditions through the dynamic regulation of RNA m6A modification. Doxorubicin is a widely used chemotherapeutic drug that induces DNA damage. It is interesting to know whether cancer cells regulate the DNA damage response and doxorubicin sensitivity through RNA m6A modification. Here, we found that doxorubicin treatment significantly induced RNA m6A methylation in breast cancer cells in both a dose- and time-dependent manner. However, protein arginine methyltransferase 5 (PRMT5) inhibited RNA m6A modification under doxorubicin treatment by enhancing the nuclear translocation of the RNA demethylase AlkB Homolog 5 (ALKBH5), which was previously believed to be exclusively localized in the nucleus. Then, ALKBH5 removed the m6A methylation of BRCA1 for mRNA stabilization and further enhanced DNA repair competency to decrease doxorubicin efficacy in breast cancer cells. Importantly, we identified the approved drug tadalafil as a novel PRMT5 inhibitor that could decrease RNA m6A methylation and increase doxorubicin sensitivity in breast cancer. The strategy that targeting PRMT5 with tadalafil is a promising approach to promote breast cancer sensitivity to doxorubicin through RNA methylation regulation.

Reno-protective effects of Phosphodiesterase 5 inhibitors

The kidneys are vital organs that play an important role in removing waste materials from the blood, electrolyte balance, blood pressure regulation, and red blood cell genesis. Kidney disease can be caused by various factors, including diabetes, ischemia/reperfusion injury, and nephrotoxic agents. Inflammation and oxidative stress play a key role in the progression and pathogenesis of kidney diseases. Acute kidney injury (AKI) and chronic kidney disease (CKD) are important health problems worldwide, as they are associated with a long-term hospital stay, and increased morbidity and mortality in high-risk patients. Current standard therapeutic options are not sufficient to delay or stop the loss of kidney function. Therefore, it is necessary to develop new therapeutic options. Phosphodiesterase 5 inhibitors (PDE5Is) are a currently available class of drugs that are used to treat erectile dysfunction and pulmonary hypertension in humans. However, recent evidence suggests that PDE5Is have beneficial renoprotective effects via a variety of mechanisms. In this review, the benefits of PDE5 inhibitors in clinical conditions associated with kidney disease, such as diabetic nephropathy, ischemia-reperfusion injury, and acute and chronic kidney injury, are summarized.

Role of Phosphodiesterase in the Biology and Pathology of Diabetes

Glucose metabolism is the initiator of a large number of molecular secretory processes in β cells. Cyclic nucleotides as a second messenger are the main physiological regulators of these processes and are functionally divided into compartments in pancreatic cells. Their intracellular concentration is limited by hydrolysis led by one or more phosphodiesterase (PDE) isoenzymes. Literature data confirmed multiple expressions of PDEs subtypes, but the specific roles of each in pancreatic β-cell function, particularly in humans, are still unclear. Isoforms present in the pancreas are also found in various tissues of the body. Normoglycemia and its strict control are supported by the appropriate release of insulin from the pancreas and the action of insulin in peripheral tissues, including processes related to homeostasis, the regulation of which is based on the PDE- cyclic AMP (cAMP) signaling pathway. The challenge in developing a therapeutic solution based on GSIS (glucose-stimulated insulin secretion) enhancers targeted at PDEs is the selective inhibition of their activity only within β cells. Undeniably, PDEs inhibitors have therapeutic potential, but some of them are burdened with certain adverse effects. Therefore, the chance to use knowledge in this field for diabetes treatment has been postulated for a long time.

Skeletal restoration by phosphodiesterase 5 inhibitors in osteopenic mice: Evidence of osteoanabolic and osteoangiogenic effects of the drugs

Phosphodiesterases (PDEs) hydrolyze cyclic nucleotides and thereby regulate diverse cellular functions. The reports on the skeletal effects of PDE inhibitors are conflicting. Here, we screened 17 clinically used non-xanthine PDE inhibitors (selective and non-selective) using mouse calvarial osteoblasts (MCO) where the readout was osteoblast differentiation. From this screen, we identified sildenafil and vardenafil (both PDE5 inhibitors) having the least osteogenic EC₅₀. Both drugs significantly increased vascular endothelial growth factor (VEGF) and VEGF receptor 2 (VEGFR2) expressions in MCO and the nitric oxide synthase inhibitor L-NAME completely blocked VEGF expression induced by these drugs. Sunitinib, a tyrosine receptor kinase inhibitor that also blocks VEGFR2 blocked sildenafil-/vardenafil-induced osteoblast differentiation. At half of their human equivalent doses, i.e. 6.0 mg/kg sildenafil and 2.5 mg/kg vardenafil, the maximum bone marrow level of sildenafil was 32% and vardenafil was 21% of their blood levels. At these doses, both drugs enhanced bone regeneration at the femur osteotomy site and completely restored bone mass, microarchitecture, and strength in OVX mice. Furthermore, both drugs increased surface referent bone formation and serum bone formation marker (P1NP) without affecting the resorption marker (CTX-1). Both drugs increased the expression of VEGF and VEGFR2 in bones and osteoblasts and increased skeletal vascularity. Sunitinib completely blocked the bone restorative and vascular effects of sildenafil and vardenafil in OVX mice. Taken together, our study suggested that sildenafil and vardenafil at half of their adult human doses completely reversed osteopenia in OVX mice by an osteogenic mechanism that was associated with enhanced skeletal vascularity.

Advantages of Phosphodiesterase Type 5 Inhibitors in the Management of Glucose Metabolism Disorders: A Clinical and Translational Issue

Among metabolic diseases, carbohydrate metabolism disorders are the most widespread. The most common glucose pathological conditions are acquired and may increase the risk of type 2 diabetes, obesity, heart diseases, stroke, and kidney insufficiency. Phosphodiesterase type 5 inhibitors (PDE5i) have long been used as an effective therapeutic option for the treatment of erectile dysfunction (ED). Different studies have demonstrated that PDE5i, by sensitizing insulin target tissues to insulin, play an important role in controlling the action of insulin and glucose metabolism, highlighting the protective action of these drugs against metabolic diseases. In this review, we report the latest knowledge about the role of PDE5i in the metabolic diseases of insulin resistance and type 2 diabetes, highlighting clinical aspects and potential treatment approaches. Although various encouraging data are available, further in vivo and in vitro studies are required to elucidate the mechanism of action and their clinical application in humans.

Biphasic Effect of Sildenafil on Energy Sensing is Mediated by Phosphodiesterases 2 and 3 in Adipocytes and Hepatocytes

Sirt1 (Sirtuin 1), AMPK (AMP-activated protein kinase), and eNOS (endothelial nitric oxide synthase) modulate hepatic energy metabolism and inflammation and play a major role in the development of NASH. Cyclic nucleotide phosphodiesterases (PDEs) play an important role in signal transduction by modulating intracellular levels of cyclic nucleotides. We previously found the PDE5 inhibitor sildenafil to synergize with leucine and leucine-metformin combinations in preclinical studies of NASH and obesity. However, efficacy is diminished at higher sildenafil concentrations. Herein, we have successfully modeled the U-shaped sildenafil dose-response in vitro and utilized this model to assess potential mechanisms of this dose-response relationship. Adipocytes and liver cells were treated with leucine (0.5 mM) and different concentrations of sildenafil (1 nM to 100 µM). cAMP, cGMP, and P-AMPK protein expression were used to demonstrate the biphasic response for increasing concentrations of sildenafil. The reversal with higher sildenafil levels was blunted by PDE2 inhibition. These data indicate that sildenafil-mediated increases in cGMP inhibits PDE3 at lower concentrations, which increases cAMP. However, further increases in cGMP from higher sildenafil concentrations activate PDE2 and consequently decrease cAMP, which demonstrates crosstalk between cAMP and cGMP via PDE2, PDE3, and PDE5. These changes in cAMP concentration are further reflected in downstream effects, including AMPK activation.

PDE5A Suppresses Proteasome Activity Leading to Insulin Resistance in C2C12 Myotubes

OBJECTIVE

The involvement of phosphodiesterase type 5 (PDE5) in the development of insulin resistance has been reported recently. However, the underlying molecular mechanism remains unclear. The present study aims at investigating the potential impacts of PDE5A on insulin signaling in C2C12 skeletal muscle myotubes and uncover the related mechanism.

METHODS

C2C12 myoblasts were differentiated into myotubes. Western blot was performed to detect the levels of proteins and phosphorylated proteins. Glucose uptake was determined by a colorimetric kit. The overexpression or knockdown of specific protein was carried out by infecting the myotubes with adenoviruses carrying cDNA or shRNA corresponding to the targeted protein, respectively.

RESULTS

PDE5A was demonstrated to negatively regulate insulin signaling, evidenced by the opposite effects on the suppression or enhancement of the insulin-stimulated Akt phosphorylation and 2-deoxy-D-glucose (2-DG) uptake in C2C12 myotubes, when PDE5A was overexpressed or knockdown, respectively. Interestingly, PDE5A overexpression led to significantly enhanced, while its knockdown resulted in markedly reduced, endoplasmic reticulum (ER) stress. Inhibition of ER stress improved PDE5A overexpression-induced insulin resistance. In addition, PDE5A was found to suppress proteasome activity. Inhibition of PDE5 by its selective inhibitor icariin restored PDE5A overexpression-reduced proteasome activity and mitigated PDE5A overexpression-induced ER stress. Consistently, icariin administration also markedly attenuated the detrimental impacts of PDE5A overexpression on insulin signaling.

CONCLUSIONS

These results suggest that PDE5A suppresses proteasome activity, which results in ER stress and subsequent insulin resistance in C2C12 myotubes.

The phosphodiesterase 5 inhibitor tadalafil regulates lipidic homeostasis in human skeletal muscle cell metabolism

PURPOSE

Tadalafil seems to ameliorate insulin resistance and glucose homeostasis in humans. We have previously reported that tadalafil targets human skeletal muscle cells with an insulin (I)-like effect. We aim to evaluate in human fetal skeletal muscle cells after tadalafil or I: (i) expression profile of I-regulated genes dedicated to cellular energy control, glycolitic activity or microtubule formation/vesicle transport, as GLUT4, PPARγ, HK2, IRS-1, KIF1C, and KIFAP3; (ii) GLUT4, Flotillin-1, and Caveolin-1 localization, all proteins involved in energy-dependent cell trafficking; (iii) activation of I-targeted paths, as IRS-1, PKB/AKT, mTOR, P70/S6K. Free fatty acids intracellular level was measured. Sildenafil or a cGMP synthetic analog were used for comparison; PDE5 and PDE11 gene expression was evaluated in human fetal skeletal muscle cells.

METHODS

RTq-PCR, PCR, western blot, free fatty acid assay commercial kit, and lipid stain non-fluorescent assay were used.

RESULTS

Tadalafil upregulated I-targeted investigated genes with the same temporal pattern as I (GLUT4, PPARγ, and IRS-1 at 3 h; HK2, KIF1C, KIFAP3 at 12 h), re-localized GLUT4 in cell sites positively immune-decorated for Caveolin-1 and Flotillin-1, suggesting the involvement of lipid rafts, induced specific residue phosphorylation of IRS-1/AKT/mTOR complex in association with free fatty acid de novo synthesis. Sildenafil or GMP analog did not affect GLUT4 trafficking or free fatty acid levels.

CONCLUSION

In human fetal skeletal muscle cells tadalafil likely favors energy storage by modulating lipid homeostasis via IRS-1-mediated mechanisms, involving activation of I-targeted genes and intracellular cascade related to metabolic control. Those data provide some biomolecular evidences explaining, in part, tadalafil-induced favorable control of human metabolism shown by clinical studies.

Effect of tadalafil administration on insulin secretion and insulin sensitivity in obese men

AIM

To evaluate the effect of tadalafil administration on insulin secretion and insulin sensitivity in obese men without diabetes.

METHODS

A randomized, double-blind, placebo-controlled clinical trial was carried out in obese male patients between 30 and 50 years of age. Eighteen subjects were randomly assigned to two groups of nine patients each. During a 28-day period, subjects received 5 mg orally of tadalafil or placebo each night. Patients were evaluated before and after the intervention. Total insulin secretion and first phase of insulin secretion were calculated by insulinogenic index and Stumvoll index, respectively, and insulin sensitivity was calculated using the Matsuda index. Tolerability and compliance were evaluated permanently throughout the study.

RESULTS

There were no significant differences after administration of tadalafil in total insulin secretion (0.82 ± 0.45 vs. 0.61 ± 0.27, p = 0.594), first phase of insulin secretion (1332 ± 487 vs. 1602 ± 800, p = 0.779) and insulin sensitivity (4.6 ± 1.2 vs. 4.9 ± 2.5, p = 0.779). No significant differences were shown in other measurements.

CONCLUSION

Tadalafil administration for 28 days did not modify insulin secretion or insulin sensitivity in obese men.

Influence of the PDE5 inhibitor tadalafil on redox status and antioxidant defense system in C2C12 skeletal muscle cells

Phosphodiesterase type 5 inhibitors (PDE5Is), widely known for their beneficial effects onto male erectile dysfunction, seem to exert favorable effects onto metabolism as well. Tadalafil exposure increases oxidative metabolism of C2C12 skeletal muscle cells. A rise in fatty acid (FA) metabolism, requiring more oxygen, could induce a larger reactive oxygen species (ROS) release as a byproduct thus leading to a redox imbalance. The aim of this study was to determine how PDE5I tadalafil influences redox status in skeletal muscle cells to match the increasing oxidative metabolism. To this purpose, differentiated C2C12 skeletal muscle cells were treated with tadalafil and analyzed for total antioxidant capacity (TAC) and glutathione levels as marker of redox status; enzyme activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) engaged in antioxidant defense; and lipid peroxidation (TBARS) and protein carbonyls (PrCar) as markers of oxidative damage. Tadalafil increased total intracellular glutathione (tGSH), CAT, SOD, and GPx enzymatic activities while no changes were found in TAC. A perturbation of redox status, as showed by the decrease in the ratio between reduced/oxidized glutathione (GSH/GSSG), was observed. Nevertheless, it did not cause any change in TBARS and PrCar levels probably due to the enhancement in the antioxidant enzymatic network. Taken together, these data indicate that tadalafil, besides improving oxidative metabolism, may be beneficial to skeletal muscle cells by enhancing the enzymatic antioxidant system capacity.

Phosphodiesterase Type 5 Inhibitor Sildenafil Decreases the Proinflammatory Chemokine CXCL10 in Human Cardiomyocytes and in Subjects with Diabetic Cardiomyopathy

T helper 1 (Th1) type cytokines and chemokines are bioactive mediators in inflammation underling several diseases and co-morbid conditions, such as cardiovascular and metabolic disorders. Th1 chemokine CXCL10 participates in heart damage initiation/progression; cardioprotection has been recently associated with sildenafil, a type 5 phosphodiesterase inhibitor. We aimed to evaluate the effect of sildenafil on CXCL10 in inflammatory conditions associated with diabetic cardiomyopathy. We analyzed: CXCL10 gene and protein in human cardiac, endothelial, and immune cells challenged by pro-inflammatory stimuli with and without sildenafil; serum CXCL10 in diabetic subjects at cardiomyopathy onset, before and after 3 months of treatment with sildenafil vs. placebo. Sildenafil significantly decreased CXCL10 protein secretion (IC₅₀ = 2.6 × 10⁻⁷) and gene expression in human cardiomyocytes and significantly decreased circulating CXCL10 in subjects with chemokine basal level ≥ 930 pg/ml, the cut-off value as assessed by ROC analysis. In conclusion, sildenafil could be a pharmacologic tool to control CXCL10-associated inflammation in diabetic cardiomyopathy.

Labelling, molecular modelling and biological evaluation of vardenafil: a potential agent for diagnostic evaluation of erectile dysfunction

^99mTc-tricarbonyl-vardenafil was specifically radiosynthesized for diagnostic evaluation of erectile dysfunction with a radiochemical yield ~97.2%. It was stable in saline up to 15h and in serum for more than 6h. The radiocomplex was lipophilic with a partition coefficient ~1.32 and plasma protein binding 72-76%. Its structure was determined using molecular mechanics and confirmed by NMR. In-silico docking to its target PDE₅ enzyme was performed. The radiocomplex inhibitory activity was assessed and its IC₅₀ was 0.7nM. Biodistribution in normal rats and biological evaluation in rat models of erectile dysfunction were performed. The results strongly suggested that ^99mTc-tricarbonyl-vardenafil is a good candidate to image erectile dysfunction in humans.

Acute effects of physical exercise and phosphodiesterase's type 5 inhibition on serum 11β-hydroxysteroid dehydrogenases related glucocorticoids metabolites: a pilot study

Endogenous glucocorticoids (GC) rapidly increase after acute exercise, and the phosphodiesterase's type 5 inhibitor (PDE5i) tadalafil influences this physiological adaptation. No data exist on acute effects of both acute exercise and PDE5i administration on 11β-hydroxysteroid dehydrogenases (11β-HSDs)-related GC metabolites. We aimed to investigate the rapid effects of exercise on serum GC metabolites, with and without tadalafil administration. A double blind crossover study was performed in eleven healthy male volunteers. After the volunteers randomly received a short-term administration of placebo or tadalafil (20 mg/die for 2 days), a maximal exercise test to exhaustion on cycle ergometer was performed. Then, after a 2-week washout period, the volunteers were crossed over. Blood samples were collected before starting exercise and at 5 and 30 min of recovery (+5-Rec, +30-Rec). Serum ACTH, corticosterone (Cn), cortisol (F), cortisone (E), tetrahydrocortisol (THF), tetrahydrocortisone (THE), cortols, cortolones and respective ratios were evaluated. Pre-Ex THF was higher after tadalafil. Exercise increased ACTH, Cn, F, E, THE, cortols and cortolones after both placebo and tadalafil, and THF after placebo. The F/E ratio increased at +5-Rec and decreased at +30-Rec after placebo. Compared to placebo, after tadalafil lower ACTH, F and Cn, higher THF/F and THE/E, and not E (at +5-Rec) and F/E modifications were observed. Acute exercise rapidly influences serum GC metabolites concentrations. Tadalafil influences both GC adaptation and 11β-HSDs activity during acute exercise. Additional researches on the effects of both exercise and PDE5i on tissue-specific 11β-HSDs activity at rest and during physiological adaptation are warranted.

Integrin α1 subunit is up-regulated in colorectal cancer

BACKGROUND

Colorectal cancer remains one of the leading causes of death from cancer in industrialized countries. Integrins are a family of heterodimeric glycoproteins involved in bidirectional cell signaling and participate in the regulation of cell shape, adhesion, migration, differentiation, gene transcription, survival and proliferation. The α1 subunit is known to be involved in RAS/ERK proliferative pathway activation and plays an important role in mammary carcinoma cell proliferation and migration. In the small intestine, α1 is present in the crypt proliferative compartment and absent in the villus, but nothing is known about its expression in the colon mucosa, or in colorectal cancer.

RESULTS

In the present study, we demonstrated that in the colon mucosa, α1 is present in the basolateral domain of the proliferative cells of the crypt, and in the surrounding myofibroblasts. We found higher levels of α1 mRNA in 86% of tumours compared to their corresponding matched margin tissues. Immunohistochemical analysis showed that α1 staining was moderate to high in 65% of tumour cells and 97% of the reactive cells surrounding the tumour cells vs 23% of normal epithelial cells.

CONCLUSION

Our findings suggest an active role for the α1β1 integrin in colorectal cancer progression.

Increased growth of colorectal liver metastasis following partial hepatectomy

Nearly 50 % of colorectal cancer (CRC) patients develop liver metastases with liver resection being the only option to cure patients. Residual micrometastases or circulating tumor cells are considered a cause of tumor relapse. This work investigates the influence of partial hepatectomy (PH) on the growth and molecular composition of CRC liver metastasis in a syngeneic rat model. One million CC531 colorectal tumor cells were implanted via the portal vein in WAG/Rij rats followed by a 30 % PH a day later. Control groups either received tumor cells followed by a sham-operation or were injected with a buffer solution followed by PH. Animals were examined with magnetic resonance imaging (MRI) and liver tissues were processed for immunolabeling and PCR analysis. One-third PH was associated with an almost threefold increase in relative tumor mass (MRI volumetry: 2.8-fold and transcript levels of CD44: 2.3-fold). Expression of molecular markers for invasiveness and aggressiveness (CD49f, CXCR4, Axin2 and c-met) was increased following PH, however with no significant differences when referring to the relative expression levels (relating to tumor mass). Liver metastases demonstrated a significantly higher proliferation rate (Ki67) 2 weeks following PH and cell divisions also increased in the surrounding liver tissue. Following PH, the stimulated growth of metastases clearly exceeded the compensation in liver volume with long-lasting proliferative effects. However, the distinct tumor composition was not influenced by liver regeneration. Future investigations should focus on the inhibition of cell cycle (i.e. systemic therapy strategies, irradiation) to hinder liver regeneration and therefore restrain tumor growth.