Echinatin induces reactive oxygen species-mediated apoptosis via JNK/p38 MAPK signaling pathway in colorectal cancer cells.

Colorectal cancer (CRC) is a very common and deadly cancer worldwide, and oxaliplatin is used as first-line chemotherapy. However, resistance usually develops, limiting treatment. Echinatin (Ech) is the main component of licorice and exhibits various therapeutic effects on inflammation-mediated diseases and cancer, ischemia/reperfusion, and liver injuries. The present study elucidated the underlying molecular mechanism of Ech-induced apoptosis in both oxaliplatin-sensitive (HT116 and HT29) and -resistant (HCT116-OxR and HT29-OxR) CRC cells. To evaluate the antiproliferative activities of Ech, we performed MTT and soft agar assays. Ech reduced viability, colony size, and numbers of CRC cells. The underlying molecular mechanisms were explored by various flow cytometry analyses. Ech-induced annexin-V stained cells, reactive oxygen species (ROS) generation, cell cycle arrest, JNK/p38 MAPK activation, endoplasmic reticulum (ER) stress, mitochondrial membrane potential depolarization, and multi-caspase activity. In addition apoptosis-, cell cycle-, and ER stress-related protein levels were confirmed by western blotting. Moreover, we verified ROS-mediated cell death by treatment with inhibitors such as N-acetyl-L-cysteine, SP600125, and SB203580. Taken together, Ech exhibits anticancer activity in oxaliplatin-sensitive and -resistant CRCs by inducing ROS-mediated apoptosis through the JNK/p38 MAPK signaling pathway. This is the first study to show that Ech has the potential to treat drug-resistant CRC, providing new directions for therapeutic strategies targeting drug-resistant CRC.

Licochalcone C Inhibits the Growth of Human Colorectal Cancer HCT116 Cells Resistant to Oxaliplatin.

Licochalcone C (LCC; PubChem CID:9840805), a chalcone compound originating from the root of Glycyrrhiza inflata, has shown anticancer activity against skin cancer, esophageal squamous cell carcinoma, and oral squamous cell carcinoma. However, the therapeutic potential of LCC in treating colorectal cancer (CRC) and its underlying molecular mechanisms remain unclear. Chemotherapy for CRC is challenging because of the development of drug resistance. In this study, we examined the antiproliferative activity of LCC in human colorectal carcinoma HCT116 cells, oxaliplatin (Ox) sensitive and Ox-resistant HCT116 cells (HCT116-OxR). LCC significantly and selectively inhibited the growth of HCT116 and HCT116-OxR cells. An in vitro kinase assay showed that LCC inhibited the kinase activities of EGFR and AKT. Molecular docking simulations using AutoDock Vina indicated that LCC could be in ATP-binding pockets. Decreased phosphorylation of EGFR and AKT was observed in the LCC-treated cells. In addition, LCC induced cell cycle arrest by modulating the expression of cell cycle regulators p21, p27, cyclin B1, and cdc2. LCC treatment induced ROS generation in CRC cells, and the ROS induction was accompanied by the phosphorylation of JNK and p38 kinases. Moreover, LCC dysregulated mitochondrial membrane potential (MMP), and the disruption of MMP resulted in the release of cytochrome c into the cytoplasm and activation of caspases to execute apoptosis. Overall, LCC showed anticancer activity against both Ox-sensitive and Ox-resistant CRC cells by targeting EGFR and AKT, inducing ROS generation and disrupting MMP. Thus, LCC may be potential therapeutic agents for the treatment of Ox-resistant CRC cells.

Activation of Heme Oxygenase-1 by Mangiferin in Human Retinal Pigment Epithelial Cells Contributes to Blocking Oxidative Damage.

Mangiferin is a kind of natural xanthone glycosides and is known to have various pharmacological activities. However, since the beneficial efficacy of this compound has not been reported in retinal pigment epithelial (RPE) cells, this study aimed to evaluate whether mangiferin could protect human RPE ARPE-19 cells from oxidative injury mimicked by hydrogen peroxide (H2O2). The results showed that mangiferin attenuated H2O2-induced cell viability reduction and DNA damage, while inhibiting reactive oxygen species (ROS) production and preserving diminished glutathione (GSH). Mangiferin also antagonized H2O2-induced inhibition of the expression and activity of antioxidant enzymes such as manganese superoxide dismutase and GSH peroxidase, which was associated with inhibition of mitochondrial ROS production. In addition, mangiferin protected ARPE-19 cells from H2O2-induced apoptosis by increasing the Bcl-2/Bax ratio, decreasing caspase-3 activation, and blocking poly(ADP-ribose) polymerase cleavage. Moreover, mangiferin suppressed the release of cytochrome c into the cytosol, which was achieved by interfering with mitochondrial membrane disruption. Furthermore, mangiferin increased the expression and activity of heme oxygenase-1 (HO-1) and nuclear factor-erythroid-2 related factor 2 (Nrf2). However, the inhibition of ROS production, cytoprotective and anti-apoptotic effects of mangiferin were significantly attenuated by the HO-1 inhibitor, indicating that mangiferin promoted Nrf2-mediated HO-1 activity to prevent ARPE-19 cells from oxidative injury. The results of this study suggest that mangiferin, as an Nrf2 activator, has potent ROS scavenging activity and may have the potential to protect oxidative stress-mediated ocular diseases.

Picropodophyllotoxin Inhibits Cell Growth and Induces Apoptosis in Gefitinib-Resistant Non-Small Lung Cancer Cells by Dual-Targeting EGFR and MET.

Patients with non-small-cell lung cancer (NSCLC) with epidermal growth factor receptor (EGFR) amplification or sensitive mutations initially respond to the tyrosine kinase inhibitor gefitinib, however, the treatment becomes less effective over time by resistance mechanism including mesenchymal-epithelial transition (MET) overexpression. A therapeutic strategy targeting MET and EGFR may be a means to overcoming resistance to gefitinib. In the present study, we found that picropodophyllotoxin (PPT), derived from the roots of Podophyllum hexandrum, inhibited both EGFR and MET in NSCLC cells. The antitumor efficacy of PPT in gefitinib-resistant NSCLC cells (HCC827GR), was confirmed by suppression of cell proliferation and anchorage-independent colony growth. In the targeting of EGFR and MET, PPT bound with EGFR and MET, ex vivo, and blocked both kinases activity. The binding sites between PPT and EGFR or MET in the computational docking model were predicted at Gly772/Met769 and Arg1086/Tyr1230 of each ATP-binding pocket, respectively. PPT treatment of HCC827GR cells increased the number of annexin V-positive and subG1 cells. PPT also caused G2/M cell-cycle arrest together with related protein regulation. The inhibition of EGFR and MET by PPT treatment led to decreases in the phosphorylation of the downstream-proteins, AKT and ERK. In addition, PPT induced reactive oxygen species (ROS) production and GRP78, CHOP, DR5, and DR4 expression, mitochondrial dysfunction, and regulated involving signal-proteins. Taken together, PPT alleviated gefitinib-resistant NSCLC cell growth and induced apoptosis by reducing EGFR and MET activity. Therefore, our results suggest that PPT can be a promising therapeutic agent for gefitinib-resistant NSCLC.

3-Deoxysappanchalcone Inhibits Cell Growth of Gefitinib-Resistant Lung Cancer Cells by Simultaneous Targeting of EGFR and MET Kinases.

The mechanistic functions of 3-deoxysappanchalcone (3-DSC), a chalcone compound known to have many pharmacological effects on lung cancer, have not yet been elucidated. In this study, we identified the comprehensive anti-cancer mechanism of 3-DSC, which targets EGFR and MET kinase in drug-resistant lung cancer cells. 3-DSC directly targets both EGFR and MET, thereby inhibiting the growth of drug-resistant lung cancer cells. Mechanistically, 3-DSC induced cell cycle arrest by modulating cell cycle regulatory proteins, including cyclin B1, cdc2, and p27. In addition, concomitant EGFR downstream signaling proteins such as MET, AKT, and ERK were affected by 3-DSC and contributed to the inhibition of cancer cell growth. Furthermore, our results show that 3-DSC increased redox homeostasis disruption, ER stress, mitochondrial depolarization, and caspase activation in gefitinib-resistant lung cancer cells, thereby abrogating cancer cell growth. 3-DSC induced apoptotic cell death which is regulated by Mcl-1, Bax, Apaf-1, and PARP in gefitinib-resistant lung cancer cells. 3-DSC also initiated the activation of caspases, and the pan-caspase inhibitor, Z-VAD-FMK, abrogated 3-DSC induced-apoptosis in lung cancer cells. These data imply that 3-DSC mainly increased mitochondria-associated intrinsic apoptosis in lung cancer cells to reduce lung cancer cell growth. Overall, 3-DSC inhibited the growth of drug-resistant lung cancer cells by simultaneously targeting EGFR and MET, which exerted anti-cancer effects through cell cycle arrest, mitochondrial homeostasis collapse, and increased ROS generation, eventually triggering anticancer mechanisms. 3-DSC could potentially be used as an effective anti-cancer strategy to overcome EGFR and MET target drug-resistant lung cancer.

Licochalcone B Induces ROS-Dependent Apoptosis in Oxaliplatin-Resistant Colorectal Cancer Cells via p38/JNK MAPK Signaling.

Licochalcone B (LCB) exhibits anticancer activity in oral cancer, lung cancer, and hepatocellular carcinoma cells. However, little is known about its antitumor mechanisms in human oxaliplatin-sensitive and -resistant colorectal cancer (CRC) cells. The purpose of the present study was to investigate the antitumor potential of LCB against human colorectal cancer in vitro and analyze its molecular mechanism of action. The viability of CRC cell lines was evaluated using the MTT assay. Flow cytometric analyses were performed to investigate the effects of LCB on apoptosis, cell cycle distribution, reactive oxygen species (ROS), mitochondrial membrane potential (MMP) dysfunction, and multi-caspase activity in CRC cells. The results demonstrated that LCB induced a reduction in cell viability, apoptosis, G2/M cell cycle arrest, ROS generation, MMP depolarization, activation of multi-caspase, and JNK/p38 MAPK. However, p38 (SB203580) and JNK (SP600125) inhibitors prevented the LCB-induced reduction in cell viability. The ROS scavenger N-acetylcysteine (NAC) inhibited LCB-induced reduction in cell viability, apoptosis, cell cycle arrest, ROS generation, MMP depolarization, and multi-caspase and JNK/p38 MAPK activities. Taken together, LCB has a potential therapeutic effect against CRC cells through the ROS-mediated JNK/p38 MAPK signaling pathway. Therefore, we expect LCB to have promising potential as an anticancer therapeutic and prophylactic agent.

Licochalcone H Targets EGFR and AKT to Suppress the Growth of Oxaliplatin -Sensitive and -Resistant Colorectal Cancer Cells.

Treatment of colorectal cancer (CRC) has always been challenged by the development of resistance. We investigated the antiproliferative activity of licochalcone H (LCH), a regioisomer of licochalcone C derived from the root of Glycyrrhiza inflata, in oxaliplatin (Ox)-sensitive and -resistant CRC cells. LCH significantly inhibited cell viability and colony growth in both Ox-sensitive and Ox-resistant CRC cells. We found that LCH decreased epidermal growth factor receptor (EGFR) and AKT kinase activities and related activating signaling proteins including pEGFR and pAKT. A computational docking model indicated that LCH may interact with EGFR, AKT1, and AKT2 at the ATP-binding sites. LCH induced ROS generation and increased the expression of the ER stress markers. LCH treatment of CRC cells induced depolarization of MMP. Multi-caspase activity was induced by LCH treatment and confirmed by Z-VAD-FMK treatment. LCH increased the number of sub-G1 cells and arrested the cell cycle at the G1 phase. Taken together LCH inhibits the growth of Ox-sensitive and Ox-resistant CRC cells by targeting EGFR and AKT, and inducing ROS generation and ER stress-mediated apoptosis. Therefore, LCH could be a potential therapeutic agent for improving not only Ox-sensitive but also Ox-resistant CRC treatment.

Isolinderalactone sensitizes oxaliplatin-resistance colorectal cancer cells through JNK/p38 MAPK signaling pathways.

BACKGROUND: Isolinderalactone (ILL), a sesquiterpene lactone compound, can be extracted from the root of Lindera aggregate. Physiological activities of ILL, including anti-inflammatory and anti-proliferative effects, have been investigated in multiple diseases. Nevertheless, little is known regarding its anti-cancer activities and the mechanism of action of ILL in targeting human CRC cells. PURPOSE: To determine ILL-mediated anti-proliferative effects on oxaliplatin (Ox)-sensitive and resistant colorectal cancer (CRC) cells and underlying mechanisms involved in its effects focusing on signal transduction. METHODS: Inhibitory effect of ILL on CRC cells was evaluated by analyzing mitochondrial membrane potential (MMP) dysfunction and multi-caspase activity. Apoptosis-regulating proteins and JNK/p38 signaling molecules were monitored by Western blotting. ROS-dependent physiological modifications by ILL were confirmed by pretreatment with N-acetylcysteine (NAC). Moreover, the involvement of JNK/p38 signaling in ROS-mediated apoptosis was verified by treatment with SP600125 (JNK inhibitor) and SB203580 (p38 inhibitor). RESULTS: ILL decreased cell viability and colony formation in both CRC Ox-sensitive (HCT116 and HT29) and Ox-resistant (OxR) (HCT116-OxR and HT29-OxR) cells. ILL induced G2/M phase cell cycle arrest, ROS generation, phosphorylated (p)JNK/p38 MAPK activation, mitochondrial membrane potential (MMP) depolarization, and multi-caspase activation, which eventually triggered apoptotic cell death of CRC cells. In addition, combined treatment with ILL and SP600125, SB203580, or pan-caspase inhibitor (Z-VAD-FMK) prevented decreases in cell viability seen after treatment with ILL alone. Pretreatment with NAC attenuated ILL-mediated apoptosis, ROS production, and p-JNK/p38 expression. CONCLUSION: Taken together, our results suggest that ILL can exert its anticancer effect in CRC Ox-sensitive and OxR cells by inducing ROS-mediated apoptosis through JNK/p38 MAPK signaling pathways. This is the first study demonstrating that ILL has a potential to improve drug efficacy against resistance mechanisms, providing a new insight into therapeutic strategies targeting drug-resistant CRC.

Podophyllotoxin Induces ROS-Mediated Apoptosis and Cell Cycle Arrest in Human Colorectal Cancer Cells via p38 MAPK Signaling.

Podophyllotoxin (PT), a lignan compound from the roots and rhizomes of Podophyllum peltatum, has diverse pharmacological activities including anticancer effect in several types of cancer. The molecular mechanism of the anticancer effects of PT on colorectal cancer cells has not been reported yet. In this study, we sought to evaluate the anticancer effect of PT on human colorectal cancer HCT116 cells and identify the detailed molecular mechanism. PT inhibited the growth of cells and colony formation in a concentration-dependent manner and induced apoptosis as determined by the annexin V/7-aminoactinomycin D double staining assay. PT-induced apoptosis was accompanied by cell cycle arrest in the G2/M phase and an increase in the generation of reactive oxygen species (ROS). The effects of PT on the induction of ROS and apoptosis were prevented by pretreatment with N-acetyl-L-cysteine (NAC), indicating that an increase in ROS generation mediates the apoptosis of HCT116 cells induced by PT. Furthermore, Western blot analysis showed that PT upregulated the level of phospho (p)-p38 mitogen-activated protein kinase (MAPK). The treatment of SB203580, a p38 inhibitor, strongly prevented the apoptosis induced by PT, suggesting that PT-induced apoptosis involved the p38 MAPK signaling pathway. In addition, PT induced the loss of mitochondrial membrane potential and multi-caspase activation. The results suggested that PT induced cell cycle arrest in the G2/M phase and apoptosis through the p38 MAPK signaling pathway by upregulating ROS in HCT116 cells.

Picropodophyllotoxin Induces G1 Cell Cycle Arrest and Apoptosis in Human Colorectal Cancer Cells via ROS Generation and Activation of p38 MAPK Signaling Pathway.

Picropodophyllotoxin (PPT), an epimer of podophyllotoxin, is derived from the roots of Podophyllum hexandrum and exerts various biological effects, including anti-proliferation activity. However, the effect of PPT on colorectal cancer cells and the associated cellular mechanisms have not been studied. In the present study, we explored the anticancer activity of PPT and its underlying mechanisms in HCT116 cells. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to monitor cell viability. Flow cytometry was used to evaluate cell cycle distribution, the induction of apoptosis, the level of reactive oxygen species (ROS), assess the mitochondrial membrane potential (Δψm), and multi-caspase activity. Western blot assays were performed to detect the expression of cell cycle regulatory proteins, apoptosis-related proteins, and p38 MAPK (mitogen-activated protein kinase). We found that PPT induced apoptosis, cell cycle arrest at the G1 phase, and ROS in the HCT116 cell line. In addition, PPT enhanced the phosphorylation of p38 MAPK, which regulates apoptosis and PPT-induced apoptosis. The phosphorylation of p38 MAPK was inhibited by an antioxidant agent (N-acetyl-L-cysteine, NAC) and a p38 inhibitor (SB203580). PPT induced depolarization of the mitochondrial inner membrane and caspase-dependent apoptosis, which was attenuated by exposure to Z-VAD-FMK. Overall, these data indicate that PPT induced G1 arrest and apoptosis via ROS generation and activation of the p38 MAPK signaling pathway.

Vasorelaxant Effect of Boesenbergia rotunda and Its Active Ingredients on an Isolated Coronary Artery.

Cardiovascular diseases are a major cause of death in developed countries. The regulation of vascular tone is a major approach to prevent and ameliorate vascular diseases. As part of our ongoing screening for cardioprotective natural compounds, we investigated the vasorelaxant effect of rhizomes from Boesenbergia rotunda (L.) Mansf. [Boesenbergia pandurata (Roxb.) Schltr.] used as a spice and herbal medicine in Asian countries. The methanol extract of B. rotunda rhizomes (BRE) exhibited significant vasorelaxation effects ex vivo at EC50 values of 13.4 ± 6.1 µg/mL and 40.9 ± 7.9 µg/mL, respectively, with and without endothelium in the porcine coronary artery ring. The intrinsic mechanism was evaluated by treating with specific inhibitors or activators that typically affect vascular reactivity. The results suggested that BRE induced relaxation in the coronary artery rings via an endothelium-dependent pathway involving NO-cGMP, and also via an endothelium-independent pathway involving the blockade of Ca2+ channels. Vasorelaxant principles in BRE were identified by subsequent chromatographic methods, which revealed that flavonoids regulate vasorelaxant activity in BRE. One of the flavonoids was a Diels-Alder type adduct, 4-hydroxypanduratin A, which showed the most potent vasorelaxant effect on porcine coronary artery with an EC50 of 17.8 ± 2.5 µM. Our results suggest that rhizomes of B. rotunda might be of interest as herbal medicine against cardiovascular diseases.