Feng Kong

Inhibitory effect of acetyl-11-keto-β-boswellic acid on androgen receptor by interference of Sp1 binding activity in prostate cancer cells

Androgen receptor (AR)-mediated signaling is crucial for the development and progression of prostate cancer (PCa). Naturally occurring phytochemicals that target the AR signaling offer significant protection against this disease. Acetyl-11-keto-beta-boswellic acid (AKBA), a compound isolated from the gum-resin of Boswellia carterii, caused G1-phase cell cycle arrest with an induction of p21(WAF1/CIP1), and a reduction of cyclin D1 as well in prostate cancer cells. AKBA-mediated cellular proliferation inhibition was associated with a decrease of AR expression at mRNA and protein levels. Furthermore, the functional biomarkers used in evaluation of AR transactivity showed suppressions of prostate-specific antigen promoter-dependent and androgen responsive element-dependent luciferase activities. Additionally, down-regulation of an AR short promoter mainly containing a Sp1 binding site suggested the essential role of Sp1 for the reduction of AR expression in cells exposed to AKBA. Interruption effect of AKBA on Sp1 binding activity but not Sp1 protein levels was further confirmed by EMSA and transient transfection with a luciferase reporter driven by three copies of the Sp1 binding site of the AR promoter. Therefore, anti-AR properties ascribed to AKBA suggested that AKBA-containing drugs could be used for the development of novel therapeutic chemicals.

Bisbibenzyl derivatives sensitize vincristine-resistant KB/VCR cells to chemotherapeutic agents by retarding P-gp activity

P-glycoprotein (P-gp) is known to mediate multidrug resistance (MDR) by acting as an efflux pump to actively transport chemotherapeutic agents out of carcinoma cells. Inhibition of P-gp function may represent one of the strategies to reverse MDR. We have previously reported that marchantin C (MC), a macrocyclic bisbibenzyl compound from liverworts, exerts anti-tumor activity as an antimitotic agent. This study was designed to evaluate the possible modulatory effect of MC and its three synthetic derivatives (MC1, MC2 and MC3) on P-gp in VCR-resistant KB/VCR cells. Results of the cytotoxicity assay revealed that MC was the most potent inhibitor of cell proliferation in both KB and KB/VCR cells among these four compounds, while the three MC-derived chemicals had little anti-proliferative activity under the same condition. However, in P-gp-expressing MDR cells, analysis of potency of these compounds in enhancing cytotoxicity of VCR led to the identification of MC2 as a more effective chemical on reversal of resistance. Further study showed that MC2 was able to reduce efflux of rhodamine-123, and in turn, increase the accumulation of rhodamine-123 and adriamycin in KB/VCR cells, indicating that MC2 re-sensitized cells to VCR by inhibition of the P-gp transport activity. In addition, the combination of MC2 and VCR at a concentration that does not inhibit cell growth resulted in an induction of apoptosis in KB/VCR cells. These results suggest that MC2, as a novel and effective inhibitor of P-gp, may find potential application as an adjunctive agent with conventional chemotherapeutic drugs to reverse MDR in P-gp overexpressing cancer cells.

PAR1‐stimulated platelet releasate promotes angiogenic activities of endothelial progenitor cells more potently than PAR4‐stimulated platelet releasate

Endothelial progenitor cells (EPCs) are important for endothelial regeneration and angiogenesis. Thrombin protease‐activated receptor 1 (PAR1) PAR1 and PAR4 stimulation induces selective release of platelet proangiogenic and antiangiogenic regulators.

Telomerase as a “stemness” enzyme

Pluripotent or multipotent stem cells are involved in development and tissue homeostasis; they have the ability to self-renew and differentiate into various types of functional cells. To maintain these properties, stem cells must undergo sustained or unlimited proliferation that requires the stabilization of telomeres, which are essential for chromosome end protection. Telomerase, an RNA-dependent DNA polymerase, synthesizes telomeric DNA. Through the lengthening of telomeres the lifespans of cells are extended, or indefinite proliferation is conferred; this is intimately associated with stem cell phenotype. This review highlights our current understanding of telomerase as a “stemness” enzyme and discusses the underlying implications.

Ursolic Acid Induces Apoptosis of Prostate Cancer Cells via the PI3K/Akt/mTOR Pathway

Ursolic acid (UA), a pentacyclic triterpenoid, is known to exert antitumor activity in breast, lung, liver and colon cancers. Nonetheless, the underlying mechanism of ursolic acid in prostate cancer cells still remains unclear. In the present study, we report the chemotherapeutic effects of ursolic acid as assessed using in vitro and in vivo models. Treatment of human prostate cancer cells (LNCaP and PC-3) with UA inhibited the proliferation and induced apoptosis in both cell lines as characterized by the increased Annexin V-binding. The induction of apoptosis by UA was associated with a decrease in the levels of Bcl-2, Bcl-xl, survivin, and activated caspase-3. Treatment with UA also inhibited the expression of phosphatidylinositol-3-kinase (PI3K), phosphorylation of Akt and mTOR signaling proteins. Further, administration of UA significantly inhibited the growth of LNCaP prostate tumor xenografts in athymic nude mice, which was associated with inhibition of cell proliferation, induction of apoptosis of tumor cells and decreased expression of PI3K downstream factors, such as p-Akt and p-mTOR in tumor xenograft tissues. Our study demonstrates that UA not only inhibits cell growth but also induces apoptosis through modulation of the PI3K/Akt/mTOR pathway in human prostate cancer cells. We suggest that UA may be a new chemotherapeutic candidate against prostate cancer.

The effective bioengineering method of implantation decellularized renal extracellular matrix scaffolds

End stage renal disease (ESRD) is a progressive loss of kidney function with a high rate of morbidity and mortality. Transplantable organs are hard to come by and hold a high risk of recipient immune rejection. We intended to establish a more effective and faster method to decellularize and recellularize the kidney scaffold for transplant and regeneration. We successfully produced renal scaffolds by decellularizing rat kidneys with 0.5% sodium dodecyl sulfate (SDS), while still preserving the extracellular matrix (ECM) 3D architecture, an intact vascular tree and biochemical components. We recellularized the kidney scaffolds with mouse embryonic stem (ES) cells that then populated and proliferated within the glomerular, vascular, and tubular structures. After in vivo implantation, these recellularized scaffolds were easily reperfused, tolerated blood pressure and produced urine with no blood leakage. Our methods can successfully decellularize and recellularize rat kidneys to produce functional renal ECM scaffolds. These scaffolds maintain their basic components, retain intact vasculature and show promise for kidney regeneration.

Laminin 411 acts as a potent inducer of umbilical cord mesenchymal stem cell differentiation into insulin-producing cells

BackgroundDiabetes mellitus (DM) is an incurable metabolic disease constituting a major threat to human health. Insulin-producing cells (IPCs) differentiated from mesenchymal stem cells (MSCs) hold great promise in the treatment of DM. The development of an efficient IPC induction system is a crucial step for the clinical application of IPCs for DM. Laminin 411 is a key component of the basement membrane and is involved in the regulation of cell differentiation; however, little is known about a role of laminin 411 in the regulation of IPC differentiation from human MSCs.MethodsMSCs were isolated from human umbilical cord (UC-MSCs) and expanded in an in vitro culture system. UC-MSCs were then cultured in the IPC induction and differentiation medium in the presence of laminin 411. Flow cytometry, Quantitative realtime PCR, immunofluorescence staining, ELISA, Western blotting and other techniques were applied to determine IPC generation, insulin expression and related mechanisms. To evaluate potential therapeutic efficacy of IPCs induced from UC-MSCs, a type-1 diabetes (T1DM) rat model was generated using streptozotocin. Blood glucose, insulin levels, and survival of rats were monitored periodically following intravenous injection of the tested cells.ResultsLaminin 411 markedly induced the expression of the genes Foxa2 and Sox17, markers for pancreatic precursor cells, efficiently induced IPC differentiation from MSCs, and up-regulated insulin expression at both mRNA and protein levels. Furthermore, the expression of the genes known to govern insulin expression including Pdx1 and Ngn3 was markedly induced by laminin 411, which suggests that Pdx 1 and Ngn 3 signaling pathways are involved in laminin 411 induced-insulin expression machinery. More importantly, administration of laminin 411-induced IPCs rapidly and significantly down-regulated fasting blood glucose levels, significantly reduced the HbA1c concentration and markedly improved the symptoms and survival of T1DM rats.ConclusionsOur results demonstrate that laminin 411 acts as a potent differentiation inducer of IPCs from UC-MSCs via the Pdx1 and Ngn3 signaling pathways. Moreover, transfusion of laminin 411 induced-IPCs more efficiently improves symptoms and survival of T1DM rats. These novel finding highlights a potential clinical application of laminin 411 induced-IPCs in the treatment of T1DM, which calls for further studies.

Bortezomib-mediated down-regulation of telomerase and disruption of telomere homeostasis contributes to apoptosis of malignant cells

Bortezomib inhibits the ubiquitin/proteasome pathway to achieve its anti-cancer effect and its well characterized activity is the NF-κB inhibition through which the anti-apoptotic bcl-2 expression is down-regulated and apoptosis is subsequently induced. However, the downstream molecular targets of bortezomib are still incompletely defined. Because telomere stabilization via activation of telomerase, induction of telomerase reverse transcriptase (hTERT) and appropriate expression of shelterin proteins is essential to cancer development and progression, we investigated the effect of bortezomib on telomere homeostasis/function in malignant cells. The bortezomib treatment of leukemic (HEL) and gastric cancer cells (BGC-823) led to significant inhibition of hTERT and telomerase expression, widespread dysregulation of shelterin protein expression, and telomere shortening, thereby triggering telomere dysfunction and DNA damage. hTERT over-expression attenuated bortezomib-induced telomere shortening, abnormal shelterin expression and telomere dysfunction. Importantly, bortezomib-mediated apoptosis of malignant cells was partially prevented by hTERT over-expression. Mechanistically, hTERT first robustly enhances bcl2 expression and maintains significantly high residual levels of bcl2 even in bortezomib-treated HEL cells. Second, hTERT protects against bortezomib-induced DNA damage. Our findings collectively reveal a profound impact of bortezomib on telomere homeostasis/function. Down-regulation of hTERT expression and telomere dysfunction induced by bortezomib both contribute to its cancer cell killing actions. It is evident from the present study that hTERT can confer resistance of malignant cells to bortezomib-based target cancer therapy, which may have important clinical implications.

Therapeutic effects of baicalin on monocrotaline-induced pulmonary arterial hypertension by inhibiting inflammatory response

BACKGROUND Baicalin has been shown to possess various pharmacological actions, a recent study revealed that baicalin can attenuate pulmonary hypertension and pulmonary vascular remodeling through the inhibition of pulmonary artery smooth muscle cell proliferation, however, the potential mechanism remains unexplored. In this study, we investigated the therapeutic effect of baicalin on a rat model of monocrotaline (MCT)-induced pulmonary arterial hypertension (PAH) and attempted to further clarify the possible mechanisms underlying the anti-inflammatory. METHODS AND RESULTS: Our research showed that compared with MCT-induced PAH model rats, rats administered intragrastically with 100mg/kg baicalin showed the following after two weeks: the right ventricular systolic pressure (RVSP) and the right ventricle/left ventricle plus septum (RV/LV+S) ratio were lower (P<0.05); the intima thickening and luminal stenosis were improved (P<0.05); the mRNA levels of tumor necrosis factor alpha (TNF-α), interleukin-11β (IL-1β), IL-6, and endothelin-1 (ET-1) were obviously reduced by quantitative reverse transcription-polymerase chain reaction (qRT-PCR); the protein expression of transforming growth factor-β1 (TGF-β1), intercellular cell adhesion molecule-1 (ICAM-1) and nuclear factor-κB (NF-κB) were significantly decreased (P<0.05); and the expression of inhibitor of NF-κB (I-κB) was increased (P<0.05) through immunohistochemical and western blot. CONCLUSION We studied the protective effects of baicalin against the lung and heart damage in experimental PAH rats; the therapeutic effects maybe through inhibiting vascular endothelial inflammatory response.

Baicalin protects the myocardium from reperfusion‑induced damage in isolated rat hearts via the antioxidant and paracrine effect

The aim of the present study was to investigate the protective effect of baicalin (BA) against ischemia-reperfusion (I/R) injury in isolated rat hearts. Sprague-Dawley rat hearts were rapidly removed, mounted on a Langendorff apparatus and subjected to 30 min ischemia followed by 30 min reperfusion with Krebs-Henseleit (K-H) solution at 37°C to establish the isolated I/R injury model. All animals (n=50) were randomly divided into five groups (n=10 in each): I, normal control; II, I/R; III, I/R plus 20 mg/kg BA; IV, I/R plus 40 mg/kg BA; and V, I/R plus 80 mg/kg BA. The degree of heart injury caused by the I/R was assessed by evaluating left ventricular function and by detecting the levels of lactate dehydrogenase (LDH) and creatine kinase (CK) in the coronary effluent and the myocardial superoxide dismutase (SOD) and malondialdehyde (MDA) levels in the isolated rat hearts. Myocardial infarct size and vascular density were assessed using histology and immunohistochemistry. The apoptotic cardiomyocytes were determined using flow cytometry (FCM). Compared with group II, the BA groups demonstrated improved left ventricular function, reduced CK and LDH release in the coronary effluent and increased SOD and MDA activity (P<0.05). Furthermore, histology and immunohistochemistry results showed that the infarct size was reduced and vessel density was augmented in the BA groups (P<0.01) compared with group II. The FCM results indicated that apoptosis was significantly lower in the BA groups than in group II (P<0.05) and that the protective effect was dose-dependent. In conclusion, these results demonstrated that BA exerts a dose-dependent protective effect on I/R injury in isolated rat hearts, the mechanisms of which may be associated with antioxidant and anti-apoptosis properties. To the best of our knowledge, this study is the first evaluation of the efficacy of BA in isolated rat hearts using histology and immunohistochemistry, providing a foundation for the use of BA in the treatment of acute myocardial infarction.