Effect of osthole on advanced glycation end products-induced renal tubular hypertrophy and role of klotho in its mechanism of action.

BACKGROUND: Osthole has been widely reported to have pharmacological activities such as anti-cancer, anti-inflammation and anti-hyperlipidemic effects. Klotho was identified as an anti-senescence protein in a variety of tissues. Loss of klotho has been associated with chronic kidney disease. However, potential roles and molecular events for osthole and klotho in diabetic nephropathy remain unclear. PURPOSE: In the current study, we undertook to study the effect of osthole on klotho expression in advanced glycation end products (AGE)-cultured human renal proximal tubular cells, and to investigate the molecular mechanisms of osthole and exogenous klotho against AGE-induced renal tubular hypertrophy. METHODS: Cell viability was elucidated by MTT assay. Protein expression was measured by Western blotting. mRNA level was analyzed by real-time PCR. Cellular hypertrophy growth was evaluated by hypertrophy index. Relative cell size was detected by flow cytometry. RESULTS: We found that raising the ambient AGE concentration causes a dose-dependent decrease in klotho synthesis. Osthole significantly increased AGE-inhibited klotho mRNA and protein expression. Osthole and exogenous klotho treatments significantly attenuated AGE-induced Janus kinase 2 (JAK2)-signal transducers and activators of transcription 1 (STAT1) and STAT3 activation. Moreover, protein levels of suppressor of cytokine signaling 1 (SOCS1) and SOCS3 were augmented by osthole and exogenous klotho. The abilities of osthole and exogenous klotho to reverse AGE-induced cellular hypertrophy were verified by the observation that osthole and exogenous klotho inhibited p21Waf1/Cip1/collagen IV/RAGE expression, total protein content, and cell size. CONCLUSION: Consequently, we found that osthole attenuated AGE-induced renal tubular hypertrophy via induction of klotho expression and suppression of the JAK2-STAT1/STAT3 signaling. These results also showed that klotho might be used as a unique molecular target for the treatment of diabetic nephropathy.

Dioscorea alata attenuates renal interstitial cellular fibrosis by regulating Smad- and epithelial-mesenchymal transition signaling pathways.

Renal interstitial fibrosis is characterized by increased extracellular matrix (ECM) synthesis. Epithelial-mesenchymal transition (EMT) in kidneys is driven by regulated expression of fibrogenic cytokines such as transforming growth factor-beta (TGF-ß). Yam, or Dioscorea alata (DA) is an important herb in Chinese medicine widely used for the treatment of clinical diabetes mellitus. However, the fibrosis regulatory effect of DA is unclear. Thus, we examined TGF-ß signaling mechanisms against EMT in rat fibroblast cells (NRK-49F). The characterization of DA water-extracts used various methods; after inducing cellular fibrosis in NRK-49F cells by treatment with ß-hydroxybutyrate (ß-HB) (10 mM), we used Western blotting to examine the protein expression in the TGF-ß-related signal protein type I and type II TGF-ß receptors, Smads2 and Smad3 (Smad2/3), pSmad2 and Smad3 (pSmad2/3), Smads4, Smads7, and EMT markers. These markers included E-cadherin, alpha-smooth muscle actin (α-SMA), and matrix metalloproteinase-2 (MMP-2). Bioactive TGF-ß and fibronectin levels in the culture media were determined using ELISA. Expressions of fibronectin and Snail transcription factor, an EMT-regulatory transcription factor, were assessed by immunofluorescence staining. DA extract dose-dependently (50-200 µg/mL) suppressed ß-HB-induced expression of fibronectin in NRK-49F cells concomitantly with the inhibition of Smad2/3, pSmad2/3, and Smad4. By contrast, Smad7 expression was significantly increased. DA extract caused a decrease in α-SMA (α-smooth muscle actin) and MMP-2 levels, and an increase in E-cadherin expression. We propose that DA extract might act as a novel fibrosis antagonist, which acts partly by down regulating the TGF-ß/smad signaling pathway and modulating EMT expression.

Annonacin induces cell cycle-dependent growth arrest and apoptosis in estrogen receptor-α-related pathways in MCF-7 cells.

ETHNOPHARMACOLOGICAL RELEVANCE: Tamoxifen resistance is common in estrogen receptor-α (ERα)-positive breast cancers. Pawpaw and soursop are anticancer annonaceous plants in complementary medicine. Thus, we studied the effects of annonacin, an annonaceous acetogenin, in breast cancer cells. MATERIALS AND METHODS: Cell growth and ERα-related pathways were studied. The effects of annonacin were tested in MCF-7 xenografts in nude mice. RESULTS: In ERα-positive MCF-7 cells, annonacin (half-effective dose ED(50) = 0.31 µM) and 4-hydroxytamoxifen (ED(50) = 1.13 µM) decreased cell survival whereas annonacin (0.5-1 µM) increased cell death at 48 h. Annonacin and 4-hydroxytamoxifen were additive in inhibiting cell survival. Annonacin (0.1 µM) induced G(0)/G(1) growth arrest while increasing p21(WAF1) and p27(kip1) and decreasing cyclin D1 protein expression. Annonacin (0.1µM) decreased cyclin D1 protein expression more than 4-hydroxytamoxifen (1 µM). Annonacin (0.1 µM) increased apoptosis while decreasing Bcl-2 protein expression. The combination of annonacin (0.1 µM) and 4-hydroxytamoxifen (1 µM) decreased Bcl-2 protein expression and ERα transcriptional activity more than annonacin (0.1 µM) did alone. Annonacin, but not 4-hydroxytamoxifen, decreased ERα protein expression. Moreover, annonacin decreased phosphorylation of ERK1/2, JNK and STAT3. In nude mice, annonacin decreased MCF-7 xenograft tumor size at 7-22 days. Moreover, annonacin decreased ERα, cyclin D1 and Bcl-2 protein expression in the xenograft at 22 days. CONCLUSIONS: Annonacin induced growth arrest and apoptosis in ERα-related pathways in MCF-7 cells. Annonacin and 4-hydroxytamoxifen were additive in inhibiting cell survival and ERα transcriptional activity. Moreover, annonacin attenuated MCF-7 xenograft tumor growth while inhibiting ERα, cyclin D1 and Bcl-2 protein expressions in nude mice.

Safflower extract: a novel renal fibrosis antagonist that functions by suppressing autocrine TGF-beta.

Progressive renal disease is characterized by the accumulation of extracellular matrix proteins in the renal interstitium. Hence, developing agents that antagonize fibrogenic signals is a critical issue facing researchers. The present study investigated the blood-circulation-promoting Chinese herb, safflower, on fibrosis status in NRK-49F cells, a normal rat kidney interstitial fibroblast, to evaluate the underlying signal transduction mechanism of transforming growth factor-beta (TGF-beta), a potent fibrogenic growth factor. Safflower was characterized and extracted using water. Renal fibrosis model was established both in vitro with fibroblast cells treated with beta-hydroxybutyrate and in vivo using rats undergone unilateral ureteral obstruction (UUO). Western blotting was used to examine protein expression in TGF-beta-related signal proteins such as type I and type II TGF-beta receptor, Smads2/3, pSmad2/3, Smads4, and Smads7. ELISA was used to analyze bioactive TGF-beta1 and fibronectin levels in the culture media. Safflower extract (SE) significantly inhibited beta-HB-induced fibrosis in NRK cells concomitantly with dose-dependent inhibition of the type I TGF-beta1 receptor and its down-stream signals (i.e., Smad). Moreover, SE dose-dependently enhanced inhibitory Smad7. Thus, SE can suppress renal cellular fibrosis by inhibiting the TGF-beta autocrine loop. Moreover, remarkably lower levels of tissue collagen were noted in the nephron and serum TGF-beta1 of UUO rats receiving oral SE (0.15 g/3 ml/0.25 kg/day) compared with the untreated controls. Hence, SE is a potential inhibitor of renal fibrosis. We suggest that safflower is a novel renal fibrosis antagonist that functions by down-regulating TGF-beta signals.

Herbal therapy is associated with the risk of CKD in adults not using analgesics in Taiwan.

BACKGROUND: Taiwan has the greatest incidence rate of end-stage renal disease in the world. Several cases of Chinese herb nephropathy were reported in Taiwan. Therefore, we studied the association between herbal therapy and chronic kidney disease (CKD) in Taiwan. STUDY DESIGN: Cross-sectional survey. SETTING & PARTICIPANTS: 1,740 adults in the Nutrition and Health Survey in Taiwan (1993 to 1996). PREDICTOR: Herbal and analgesic therapy. OUTCOMES & MEASUREMENTS: CKD after adjustment for potential confounding variables. RESULTS: Among medication users, prevalences of herbal therapy and analgesic use were 21.6% and 13.2%, respectively. The prevalence of CKD was 9.9%. Participants with CKD were older and had more analgesic use, diabetes, hypertension, and cardiovascular disease. Analgesic use was associated independently and positively with CKD (odds ratio, 2.2; 95% confidence interval, 1.4 to 3.5; P = 0.003) and CKD stage (odds ratio, 2.3; 95% confidence interval, 1.4 to 3.6; P = 0.003). Conversely, herbal therapy was associated independently and positively with CKD (odds ratio, 1.39; 95% confidence interval, 1.2 to 1.7; P = 0.002) and CKD stage (odds ratio, 1.38; 95% confidence interval, 1.1 to 1.7; P = 0.004) only in participants who did not use analgesics. LIMITATIONS: Because this was a cross-sectional study, cause and effect could not be ascertained. CONCLUSIONS: Herbal therapy was associated with CKD in adults in Taiwan who did not use analgesics.