Transforming growth factor-Beta inhibits heme oxygenase-1 expression in lung fibroblast through nuclear factor-kappa-B-dependent pathway

Heme Oxygenase 1 in Schwann Cells Regulates Peripheral Nerve Degeneration Against Oxidative Stress

During Wallerian degeneration, Schwann cells lose their characteristic of myelinating axons and shift into the state of developmental promyelinating cells. This recharacterized Schwann cell guides newly regrowing axons to their destination and remyelinates reinnervated axons. This Schwann cell dynamics during Wallerian degeneration is associated with oxidative events. Heme oxygenases (HOs) are involved in the oxidative degradation of heme into biliverdin/bilirubin, ferrous iron, and carbon monoxide. Overproduction of ferrous iron by HOs increases reactive oxygen species, which have deleterious effects on living cells. Thus, the key molecule for understanding the exact mechanism of Wallerian degeneration in the peripheral nervous system is likely related to oxidative stress-mediated HOs in Schwann cells. In this study, we demonstrate that demyelinating Schwann cells during Wallerian degeneration highly express HO1, not HO2, and remyelinating Schwann cells during nerve regeneration decrease HO1 activation to levels similar to those in normal myelinating Schwann cells. In addition, HO1 activation during Wallerian degeneration regulates several critical phenotypes of recharacterized repair Schwann cells, such as demyelination, transdedifferentiation, and proliferation. Thus, these results suggest that oxidative stress in Schwann cells after peripheral nerve injury may be regulated by HO1 activation during Wallerian degeneration and oxidative-stress-related HO1 activation in Schwann cells may be helpful to study deeply molecular mechanism of Wallerian degeneration.

Chalcone flavokawain A attenuates TGF-β1-induced fibrotic pathology via inhibition of ROS/Smad3 signaling pathways and induction of Nrf2/ARE-mediated antioxidant genes in vascular smooth muscle cells

TGF‐β1 plays a crucial role in the pathogenesis of vascular fibrotic diseases. Chalcones are reportedly cancer chemo‐preventive food components that are rich in fruits and vegetables. In this study, flavokawain A (FKA, 2‐30 μM), a naturally occurring chalcone in kava extracts, was evaluated for its anti‐fibrotic and antioxidant properties in TGF‐β1‐stimulated vascular smooth muscle (A7r5) cells, as well as its underlying molecular mechanism of action. Immunofluorescence data showed down‐regulated F‐actin expression with FKA treatment in TGF‐β1‐stimulated A7r5 cells. Western blotting demonstrated that FKA treatment suppressed the expression of α‐SMA and fibronectin proteins under TGF‐β1 stimulation. Findings from wound‐healing and invasion experiments showed that FKA inhibits TGF‐β1‐mediated migration and invasion. Western blotting demonstrated that treatment with FKA down‐regulated MMP‐9 and MMP‐2 and up‐regulated TIMP‐1 expression. Further evidence showed that FKA decreased TGF‐β1‐mediated phosphorylation and the transcriptional activity of Smad3. TGF‐β1‐induced excessive ROS production was remarkably reversed by FKA treatment in A7r5 cells, and inhibition by FKA or N‐acetylcysteine (NAC) substantially diminished TGF‐β1‐induced p‐Smad3 activation and wound‐healing migration. Interestingly, FKA‐mediated antioxidant properties were associated with increased nuclear translocation of Nrf2 and elevated antioxidant response element (ARE) luciferase activity. Activation of Nrf2/ARE signaling was accompanied by the induction of HO‐1, NQO‐1 and γ‐GCLC genes in FKA‐treated A7r5 cells. Notably, silencing of Nrf2 (siRNA transfection) significantly diminished the FKA‐mediated antioxidant effects, indicating that FKA may inhibit TGF‐β1‐induced fibrosis through suppressing ROS generation in A7r5 cells. Our results suggested that anti‐fibrotic and antioxidant activities of the chalcone flavokawain A may contribute to the development of food‐based chemo‐preventive drugs for fibrotic diseases.

The role of NFκB in spheroid formation of human breast cancer cells cultured on the Random Positioning Machine

Human MCF-7 breast cancer cells were exposed to a Random Positioning Machine (RPM). After 24 hours (h) the cells grew either adherently within a monolayer (AD) or within multicellular spheroids (MCS). AD and MCS populations were separately harvested, their cellular differences were determined performing qPCR on genes, which were differently expressed in AD and MCS cells. Gene array technology was applied to detect RPM-sensitive genes in MCF-7 cells after 24 h. Furthermore, the capability to form multicellular spheroids in vitro was compared with the intracellular distribution of NF-kappaB (NFκB) p65. NFκB was equally distributed in static control cells, but predominantly localized in the cytoplasm in AD cells and nucleus in MCS cells exposed to the RPM. Gene array analyses revealed a more than 2-fold change of only 23 genes including some whose products are affected by oxygen levels or regulate glycolysis. Significant upregulations of the mRNAs of enzymes degrading heme, of ANXA1, ANXA2, CTGF, CAV2 and ICAM1, as well as of FAS, Casp8, BAX, p53, CYC1 and PARP1 were observed in MCS cells as compared with 1g-control and AD cells. An interaction analysis of 47 investigated genes suggested that HMOX-1 and NFκB variants are activated, when multicellular spheroids are formed.

Galunisertib (LY2157299), a transforming growth factor-β receptor I kinase inhibitor, attenuates acute pancreatitis in rats

Galunisertib (LY2157299), a selective ATP-mimetic inhibitor of TGF-β receptor I (TGF-βRI), is the only known TGF-β pathway inhibitor. In the present study, we investigated the effect of galunisertib on taurocholate (TAC)-induced acute pancreatitis (AP) in rats, and the role of TGF-β and NF-κB signaling pathways. AP was induced by infusion of TAC into the pancreatic duct of Sprague-Dawley male rats (n=30). The rats (220±50 g) were administered galunisertib intragastrically [75 mg·kg^-1·day^-1 for 2 days (0 and 24 h)]. Serum IL-1β, IL-6, TNF-α, amylase (AMY), lipase (LIP), and myeloperoxidase (MPO) levels were measured by ELISA. NF-κB activity was detected by electrophoretic mobility shift assay (EMSA); NF-κBp65 and TGF-β1 proteins, as well as TGF-βRI and p-Smad2/3 proteins, were detected by western blot assay. Cell apoptosis was detected by TUNEL assay. H&E staining was used to evaluate the histopathological alterations of the pancreas. Galunisertib treatment attenuated the severity of AP and decreased the pancreatic histological score. In addition, number of apoptotic cells were significantly increased in the galunisertib-treated group (16.38±2.26) than in the AP group (8.14±1.27) and sham-operated group (1.82±0.73; P<0.05 and P<0.01, respectively). Galunisertib decreased the expression levels of TGF-βRI and p-Smad2/3 and inhibited NF-κB activation and p65 translocation compared with the sham-operated group. Furthermore, serum IL-1β, IL-6, TNF-α, AMY and LIP levels and tissue MPO activity were significantly decreased in the galunisertib-treated group. Our data demonstrate that galunisertib attenuates the severity of TAC-induced experimental AP in rats by inducing apoptosis in the pancreas, inhibiting the activation of TGF-β signals and NF-κB as well as the secretion of pro-inflammatory cytokines.