Betulinic acid exerts potent antitumor effects on paclitaxel-resistant human lung carcinoma cells (H460) via G2/M phase cell cycle arrest and induction of mitochondrial apoptosis.

Betulinic acid is a pentacyclic plant compound obtained from the bark of white birch trees and has been demonstrated to exhibit notable pharmacological properties. In the present study, the anticancer potential of betulinic acid on paclitaxel-resistant lung cancer cell line (H460) was evaluated. Cell viability was evaluated by an MTT assay, and a clonogenic assay was performed to assess the effects on cancer cell colony formation. DAPI staining using fluorescence microscopy and flow cytometry were employed to evaluate the effects of betulinic acid on apoptosis. The effects of betulinic acid on the cell cycle and mitochondrial membrane potential were also evaluated by flow cytometry. The effects of betulinic acid on the protein expression of B-cell lymphoma-2 (Bcl-2)/Bcl-2-associated X (Bax) were evaluated by western blot analysis. The results of the present study indicated that the half-maximal inhibitory concentration value of betulinic acid on paclitaxel-resistant H460 lung cancer cells was 50 µM. The treatment with betulinic acid was able to inhibit the colony formation potential in a dose-dependent manner. A lower cytoxicity by betulinic acid against normal human epithelial FR2 cells was observed compared with H460 cells. The betulinic acid exerted anticancer activity via the induction of apoptosis by regulating the Bcl-2/Bax signaling pathway. Additionally, treatment with betulinic acid resulted in cell cycle arrest of paclitaxel-resistant lung cancer H460 cells at the G2/M phase. Betulinic acid was also reported to cause reductions in the mitochondrial membrane potential in a dose-dependent manner. In conclusion, the results of the present study indicated that betulinic acid may be a useful drug candidate for the management of drug-resistant lung cancer.

Inhibition of YAP/TAZ Activity in Spinal Cord Suppresses Neuropathic Pain.

UNLABELLED: Neuropathic pain, often caused by nerve injury, is a major clinical challenge. Mechanisms that underlie neuropathic pain remain elusive and effective medications are limited. Numerous investigations of pain mechanisms have focused on alterations and phenotypic switches of the nociceptive transmitters and modulators, as well as on their receptors and downstream signaling pathways that have already exerted roles in the pain processes of mature nervous systems. We have demonstrated recently that nerve injury may elicit neuronal alterations that recapitulate events occurring during development. Signaling of the representative activated molecule Wnt thus becomes a trigger for the development of neuropathic pain and is a potential therapeutic target. We report that the transcriptional regulators YAP and TAZ, which orchestrate Wnt response via incorporation in the ß-catenin destruction complex, are key in the pathogenesis of neuropathic pain and may serve as an "ON-OFF" switch for neuropathic pain status in rats. Peripheral nerve injury causes rapid-onset and long-lasting nuclear accumulation of YAP/TAZ/ß-catenin in the spinal dorsal horn. Spinal inhibition or knock-down of either YAP or TAZ suppresses mechanical allodynia induced by nerve injury or the pain initiators lysophosphatidic acid and Wnt3a. Promoting the nuclear accumulation of YAP/TAZ leads to mechanical hypersensitivity in naive animals. Further, we discovered a new small molecule, dCTB, which targets YAP/TAZ/ß-catenin and can greatly suppress neuropathic pain and the associated neurochemical alterations. Our study reveals that YAP and TAZ are core mechanisms underlying the pathogenesis of neuropathic pain and are targets in the screening for potent analgesics for the treatment of neuropathic pain. SIGNIFICANCE STATEMENT: Mechanisms that underlie neuropathic pain remain elusive. We have demonstrated recently that nerve injury can activate Wnt signaling, which becomes a trigger for the development of neuropathic pain. We report that the transcriptional regulators YAP and TAZ, which orchestrate Wnt response via incorporation in the ß-catenin destruction complex, are key in the pathogenesis of neuropathic pain and may serve as an "ON-OFF" switch for neuropathic pain status. Further, we discovered a new small molecule, dCTB, which targets YAP/TAZ/ß-catenin and can greatly suppress neuropathic pain. Our study reveals that YAP and TAZ are core mechanisms underlying the pathogenesis of neuropathic pain and are targets in the screening of potent analgesics for the treatment of neuropathic pain.

Requirements for activation of the signal-transduction network that leads to regulatory phosphorylation of leaf guard-cell phosphoenolpyruvate carboxylase during fusicoccin-stimulated stomatal opening.

Leaves regulate gas exchange through control of stomata in the epidermis. Stomatal aperture increases when the flanking guard cells accumulate K+ or other osmolytes. K+ accumulation is stoichiometric with H+ extrusion, which is compensated for by phosphoenolpyruvate carboxylase (PEPC, EC 4.1.1.31)-mediated malate synthesis. Plant PEPCs are regulated allosterically and by phosphorylation. Aspects of the signal-transduction network that control the PEPC phosphorylation state in guard cells are reported here. Guard cells were preloaded with [32P]orthophosphate (32Pi); then stomata were incubated with fusicoccin (FC), which activates the guard-cell plasma membrane H+-ATPase. [32P]PEPC was assessed by immunoprecipitation, electrophoresis, immunoblotting, and autoradiography. In -FC controls, stomatal size, guard-cell malate, and [32P]PEPC were low; maximum values for these parameters were observed in the presence of FC after a 90-min incubation and persisted for an additional 90 min. This high steady-state phosphorylation status resulted from continuous phosphorylation and dephosphorylation, even after the malate-accumulation phase. PEPC phosphorylation was diminished by approximately 80% when K+ uptake was associated with Cl- uptake and was essentially abolished when stomatal opening was sucrose--rather than K+--dependent. Finally, alkalinization by NH4+ in the presence of K+ did not cause PEPC phosphorylation (as it does in C4 plants). As discussed, a role for cytoplasmic protons cannot be completely excluded by this result. In summary, activation of the plasma membrane H+-ATPase was essential, but not sufficient, to cause phosphorylation of guard-cell PEPC. Network components downstream of the H+-ATPase influence the phosphorylation state of this PEPC isoform.