Proteasome inhibitors and their combination with antiandrogens: effects on apoptosis, cellular proliferation and viability of prostatic adenocarcinoma cell cultures

The 26S proteasome is a ubiquitin-dependent proteolytic system that has been implicated in the regulation of cell cycle progression and apoptosis. We investigated the effects of the proteasome inhibitors MG115 and PSI alone or in combination with different concentrations of the antiandrogen hydroxyflutamide on the cellular proliferation, apoptosis and viability of 10 prostatic adenocarcinoma cell cultures. Treatment with both proteasome inhibitors resulted in apoptosis induction, whereas the combinations with hydroxyflutamide generally did not, with the exception of MG115 combined with 10(-7) M hydroxyflutamide. MG115 caused a significant decrease in cellular proliferation, as did the combinations of both proteasome inhibitors with hydroxyflutamide, whereas hydroxyflutamide alone was only effective at a concentration of 10(-5) M. Cellular viability was significantly reduced when both proteasome inhibitors were combined with 10(-5) M hydroxyflutamide. Although the results varied among different cell lines, we conclude that proteasome inhibitors are able to induce apoptosis and reduce cellular proliferation. They might prove effective as antineoplastic substances in prostatic adenocarcinoma alone or in combination with antiandrogens.     

Immunoproteasom: drug development for xenotransplantation

The majority of cellular proteins are degraded by proteasomes within the ubiquitin‐proteasome ATP‐dependent degradation pathway. Products of proteasomal activity are short peptides which are further hydrolysed by proteases to single amino acid. Some peptides though can escape the degradation, being selected and uptaken by MHC class I molecules for presentation to the immune system on the cell surface. MHC class I molecules are highly selective and specific in terms of ligand binding. Variability of peptides produced in living cells is created by a variety of ways which allow ensuring fast and efficient immune response. Substitution of constitutive proteasomal subunits with immuno‐subunits leads to conformational changes in the substrate binding channels and result in modified protein cleavage patterns and consequently, in the generation of new antigenic peptides. The proteasome (core particle, CP) represents an attractive drug target due to its central functional role in biological processes. It has been extensively investigated during the last decade and validated with the approval of the drug bortezomib by the US Food and Drug Administration (FDA). Currently, several optimized second‐generation CP inhibitors are being explored as anti‐cancer drugs in clinical trials and most of them equally target constitutive proteasomes (cCPs) and immunoproteasomes (iCPs). However, selective inhibition of the iCP, a distinct class of proteasomes predominantly expressed in immune cells, appears to be a promising therapeutic rationale for the treatment of autoimmune disorders and organ rejection. Although few selective agents have already been identified, the recently determined crystal structure of the iCP [1] will further promote the development and optimization of iCP‐selective compounds [2,3]. References: 1. Huber EM, Basler M, Schwab R, Heinemeyer W, Kirk C, Groettrup M, Groll M. Constitutive and immunoproteasome crystal structures reveal differences in substrate and inhibitor specificity. Cell 2012; 148: 727–738. 2. Huber E, Groll M. Inhibitors for the immuno‐ and constitutive proteasome: current and future trends in drug development. Angew. Chem. Int. Ed. 2012; 51 (1): DOI: 10.1002/anie.201201616. 3. Gallastegui N, Beck P, Arciniega M, Huber R, Hillebrand S, Groll M. Hydroxyureas as noncovalent proteasome inhibitors. Angew. Chem. Int. Ed. 2012; 51 (1): 247–249.     

二氧化碳点阵激光治疗烧伤瘢痕的研究进展

This paper reviews the new progress in the research of fractional carbon dioxide laser in treating hypertrophic scar after bum injury,which remains a challenging problem for burn care surgeons.There have been many traditional therapeutic approaches,such as compression remedy,operation,and so on.However,a satisfactory method is lacking to date.In recent years,the newly developed fractional carbon dioxide laser has been employed to treat different kinds of scars,and it has been proved to be effective in terms of an improvement of scar color,texture,and rigidity.It seems to be a promising method for scar treatment in future.     

Rapamycin in transplantation: a review of the evidence

Rapamycin in transplantation: A review of the evidence. The calcineurin inhibitors have been the mainstays of immunosuppression for solid organ transplantation over the last two decades, but nephrotoxicity limits their therapeutic benefit. Rapamycin is a new drug with both immunosuppressant and antiproliferative properties that has a unique mechanism of action distinct from that of the calcineurin inhibitors. It has a role as a maintenance immunosuppressant either alone or in combination with a calcineurin inhibitor and can also be used to treat refractory acute rejection. Theoretical evidence suggests that it may limit the development and progression of chronic rejection in transplant recipients, but this has yet to be confirmed. This review examines the current in vitro animal and human work underlying the use of rapamycin and, in addition, comments on the pharmacokinetics and side-effect profile of this promising new agent.     

Interleukin-1 up-regulates the expression and activity of 26S proteasome in burned rat

Expression of IL-1 and proteasome are elevated in burned animals and patients. However, whether the increased level of IL-1 correlates with the increased activity and expression of 26S proteasome after burn has not been studied. In the present study, we investigated the role of single IL-1 factor on activation of the 26S proteasome first by injection of recombinant IL-1 into the normal rats. Results indicated that proteolytic activity and the expression of the 26S proteasome increased remarkably 24 and 48 h after-IL-1 injection, respectively. We then studied the potential role of IL-1 on activity and expression of the proteasome in the burned rat by using neutralizing monoclonal antibody against IL-1. Results demonstrated that activity and the expression of 26S proteasome were decreased partially but significantly 48 h after-burn when circulating IL-1 in injured animals was neutralized. These results indicate that IL-1 may play a key role on the activity and expression of 26S proteasome following burn. The proteasome has been verified as being deeply involved in the mechanism of accelerated muscle protein breakdown after burn, these results imply that IL-1 might be involved in the protein metabolism after-burn by activating the proteasome pathway, though protein metabolism directly affected by IL-1 had not been assessed in this study.     

Anti-angiogenesis in prostate cancer： knocked down but not out

Angiogenesis is a very complex physiological process, which involves multiple pathways that are dependent on the homeostatic balance between the growth factors （stimulators and inhibitors）. This tightly controlled process is stimulated by angiogenic factors, which are present within the tumor and surrounding tumor-associated stromal cells. The dependence of tumor propagation, invasion and metastasis on angiogenesis makes the inhibitors of new blood vessel formation attractive drugs for treating the malignancies. Angiogenesis can be disrupted by several distinct mechanisms： by inhibiting endothelial cells, by interrupting the signaling pathways or by inhibiting other activators of angiogenesis. This strategy has shown therapeutic benefit in several types of solid tumors, leading to Food and Drug Administration （FDA） approval of anti-angiogenic agents in the treatment of kidney, non-small cell lung, colon and brain cancers. Although no angiogenesis inhibitors have been approved for patients with metastatic prostate cancer, therapies that target new blood vessel formation are still an emerging and Dromising area of prostate cancer research.     

Targeted therapies in the treatment of urothelial cancers

Progress has been slow in systemic management of locally advanced and metastatic bladder cancer over the past 20 years. However, the recent approval of immunotherapy with atezolizumab and nivolumab for second-line salvage therapy may usher in an era of more rapid improvement. Systemic treatment is suboptimal and is an area of substantial unmet medical need. The recent findings from The Cancer Genome Atlas project revealed promising pathways that may be amenable to targeted therapies. Promising results with treatment using vascular endothelial growth factor inhibitors such as ramucirumab, sunitinib or bevacizumab, and human epidermal growth factor receptor 2 targeted therapies, epidermal growth factor receptor inhibitors, and fibroblast growth factor receptor inhibitors, are undergoing clinical trials and are discussed later.     

Relationship of the 20S Proteasome and the Proteasome Activator PA28 to Atherosclerosis and Intimal Hyperplasia in the Human Vascular System

Down-regulation of the proteasome activator PA28 results in abnormal proteasome activation and has been implicated in the development of intimal hyperplasia (IH) in animal models. Demonstration of proteasome and PA28 expression has not yet been documented in the human vascular system. This study sought to define the distribution of the 20S proteasome and its activator PA28 in human vessels and determine the relationship between the expression of the proteasome and PA28 and the development of atherosclerosis and IH. Vascular biopsies were obtained from 70 patients at the time of surgery, were snap frozen and sectioned in 5-micron sections, and prepared using standard histological techniques. The immunoperoxidase technique was used to identify 20S proteasome and PA28 expression in diseased and normal human arteries and veins as well as in patent bypass grafts with and without IH. Expression was graded by a blinded pathologist (scale: 1-4). Repeat quantification of the immunopositive cells was also performed. Expression of 20S proteasome and PA28 was identified in all vascular tissues examined. The proteins were identified predominately within the cytoplasm of vascular smooth muscle cells and endothelial cells. PA28 was more intensely expressed in quiescent regions of the vessel wall as compared to areas undergoing active proliferation and remodeling. PA28-mediated activation of the proteasome may be necessary to maintain normal cellular homeostasis and prevent excessive cellular proliferation in the human vascular system. Abnormalities of proteasome activation may have a significant role in the development of atherosclerosis and IH.     

SGLT2 inhibitors: molecular design and potential differences in effect

The physiological and pathological handling of glucose via sodium-glucose cotransporter-2 (SGLT2) in the kidneys has been evolving, and SGLT2 inhibitors have been focused upon as a novel drug for treating diabetes. SGLT2 inhibitors enhance renal glucose excretion by inhibiting renal glucose reabsorption. Consequently, SGLT2 inhibitors reduce plasma glucose insulin independently and improve insulin resistance in diabetes. To date, various SGLT2 inhibitors have been developed and evaluated in clinical studies. The potency and positioning of SGLT2 inhibitors as an antidiabetic drug are dependent on their characteristic profile, which induces selectivity, efficacy, pharmacokinetics, and safety. This profile decides which SGLT2 inhibitors can be expected for application of the theoretical concept of reducing renal glucose reabsorption for the treatment of diabetes. I review the structure and advancing profile of various SGLT2 inhibitors, comparing their similarities and differences, and discuss the expected SGLT2 inhibitors for an emerging category of antidiabetic drugs.     

芳香化酶抑制剂在诱导排卵中的应用

第三代芳香化酶抑制剂为高效、特殊的芳香化酶抑制剂。它通过抑制卵巢雌激素,引起促性腺激素释放激素的释放,增加卵泡刺激素分泌。以之诱导WHOII型无排卵患者排卵,半衰期短,且十分安全。在控制性促超排卵中,与促性腺激素联合应用可显著降低促性腺激素的剂量。此外,芳香化酶抑制剂可口服,对子宫内膜无不良影响。有可能替代克罗米芬成为第一线诱导排卵药物,在辅助生育中具有广阔的应用前景。     

Assessing the relative risk of cardiovascular disease among renal transplant patients receiving tacrolimus or cyclosporine

Calcineurin inhibitors potentially contribute to risk of cardiovascular events through the development of new-onset diabetes mellitus, hypertension and hyperlipidemia. The exact extent to which calcineurin inhibitors affect these risk factors is difficult to establish since pre-existing renal disease and concomitant immunosuppressive agents (such as steroids or TOR inhibitors) also exert an effect. Clinical trials have consistently shown a higher incidence of new-onset diabetes mellitus with tacrolimus, which has been borne out in large-scale registry analyses. However, the risk of hypertension is approximately 5% higher with cyclosporine than tacrolimus, as is the risk of hyperlipidemia. Statin therapy is effective in treating dyslipidemia and has significant benefits in renal transplant patients. An individualized approach to choice of calcineurin inhibitor, by which cyclosporine or tacrolimus are selected based on the patient's particular risk profile, may thus help to reduce the toll of cardiovascular mortality among renal transplant recipients in the future.     

Recent advances in the role of mammalian target of rapamycin inhibitors on cardiac allograft vasculopathy

Cardiac allograft vasculopathy (CAV) is a progressive fibroproliferative disease, which contributes to significant morbidity and mortality during long-term follow-up after heart transplantation. Mammalian target of rapamycin (mTOR) inhibitors have favorable effects on endothelial function and reduce intimal proliferation, and their early use after transplantation has been associated with a reduction in the risk of development and progression of CAV. However, there are conflicting reports on the efficacy of these agents in treating established CAV. Most of the data until recently have been based on short-term follow-up, and CAV was assessed by changes in intravascular ultrasound. In this study, we review the mechanism of action of mTOR inhibitors and their protective role in CAV and summarize some of the recent literature, which include long-term follow-up using this class of medications.     

Effects of the proteasome inhibitor bortezomib on osteolytic human prostate cancer cell metastases

Prostate adenocarcinoma is the most common malignancy diagnosed in males, and bone metastases remain a significant source of morbidity and mortality in this population. The ubiquitin-proteasome cascade is responsible for the degradation of intracellular proteins, and this pathway is thought to play an essential role in the development of malignancies by altering the levels of various proteins involved in the regulation of cell division. Proteasome inhibitors represent a class of chemotherapeutic agents that have been shown to inhibit tumor growth by a number of different mechanisms. Using a murine intratibial injection model, we examined the effects of the proteasome inhibitor bortezomib on the establishment and progression of osteolytic bone lesions induced by human CaP cells (PC-3 cell line). In this study, the intravenous administration of bortezomib (1 mg/kg) did not prevent the initial formation of osteolytic lesions but did appear to inhibit their growth in a time-dependent fashion. In contrast, bortezomib therapy effectively inhibited the establishment and progression of subcutaneous PC-3 tumors, which served as a positive control. These results suggest that proteasome inhibitors such as bortezomib may represent a novel adjunctive therapy for the treatment of osteolytic skeletal metastases, especially when treatment is initiated early during the disease process.     

Future drugs for the treatment of benign prostatic hyperplasia

For at least a decade, no new drug principles have been added to the therapeutic armamentarium for the treatment of lower urinary tract symptoms (LUTS) associated with or suggestive of benign prostatic hyperplasia (BPH). Theoretically, there seem to be several possibilities to improve the current treatment, which is based mainly on alpha1-adrenoceptor (AR) antagonists, 5alpha-reductase inhibitors and phytotherapy. It cannot be dismissed that subtype selective alpha1-AR antagonists can further improve treatment, but convincing evidence is still lacking. Muscarinic receptor antagonists are currently evaluated in BPH patients, but their eventual place in therapy, as a single treatment or in combination with alpha1-AR antagonists, has to be established. Endothelin receptor antagonists, alone or together with alpha1-AR antagonists, seem to offer a new attractive approach; however, proof of concept studies are lacking. The L-arginine/NO/cGMP pathway awaits further exploration; nitric oxide (NO) donors or phosphodiesterase (PDE) inhibitors may be clinically useful. Purinoceptors are currently the focus of interest as treatment targets in the lower urinary tract and inhibitors of P2X3 (and P2X1) subtypes may offer new opportunities. If a treatment based on desensitising C-fibres in the bladder and urethra is effective, not only in neurogenic bladders, but also for treating LUTS, it would be a viable option. For new treatments of LUTS, targets within the central nervous system (CNS) may offer exciting opportunities.     

Antibody therapy in renal cell carcinoma

The treatment of metastasized renal cell carcinoma (RCC) still represents a formidable challenge, despite the development of small molecule, tyrosine kinase inhibitors (TKI) that have made a major impact on the disease. Although the percentage of patients achieving a partial response or stabilization of disease has been impressive, these effects are mostly non-durable. Additionally, drug-related side effects can be quite severe. Alternative treatment modalities might be monoclonal antibodies (mAbs). mAbs against RCC-associated antigens have been developed and have shown promise. Additionally, current efforts focus on Bevacizumab that recognizes vascular endothelial growth factor (VEGF). VEGF overexpression in RCC provides the opportunity to inhibit this proangiogenic pathway. Also with Bevacizumab, promising results have been obtained, particularly in combination with other treatment modalities. It is likely that mAbs, either as single agents or in combination with other agents, may become useful additions to the armamentarium to diagnose and treat RCC.