Novel CDK9 inhibitor oroxylin A promotes wild-type P53 stability and prevents hepatocellular carcinoma progression by disrupting both MDM2 and SIRT1 signaling.

Hepatocellular carcinoma (HCC) is one of the most lethal tumours worldwide. However, the effects of first-line sorafenib treatment in advanced HCC fail to prolong patients' survival due to the highly heterogeneous characteristics of HCC etiology. Cyclin-dependent kinase 9 (CDK9) is an important target in the continuous development of cancer therapy. Here, we demonstrate that CDK9 is closely associated with the progression of HCC and can serve as an HCC therapeutic target by modulating the recovery of wild-type p53 (wt-p53) function. We prove that mouse double minute 2 homologue (MDM2) and Sirtuin 1 (SIRT1) are phosphorylated by CDK9 at Ser166 and Ser47, respectively. Inhibition of CDK9 not only reduces the MDM2-mediated ubiquitination and degradation of wt-p53 but also increases wt-p53 stability by suppressing deacetylase activity of SIRT1. Thus, inhibition of CDK9 promotes the wt-p53 stabilization and prevents HCC progression. However, excessive inhibition by high concentrations of specific CDK9 inhibitors counteracts the promotion of p53 stability and reduces their anti-HCC activity because of extreme general transcription repression. The effects of a novel CDK9 inhibitor named oroxylin A (OA) from Scutellaria baicalensis are explored, with the results indicating that OA shows moderate and controlled inhibition of CDK9 activity and expression, and stabilizes wt-p53 by inhibiting CDK9-regulated MDM2 and SIRT1 signaling. These outcomes indicate the high therapeutic potential of OA against HCC and its low toxicity in normal tissue. This study demonstrates a novel mechanism for the regulation of wt-p53 by CDK9 and indicates that OA is a potential candidate for HCC therapy.

Oroxylin A inhibits the migration of hepatocellular carcinoma cells by inducing NAG-1 expression.

Hepatocellular carcinoma (HCC), the most prevalent liver cancer, is considered one of the most lethal malignancies with a dismal outcome mainly due to frequent intrahepatic and distant metastasis. In the present study, we demonstrated that oroxylin A, a natural product extracted from Scutellaria radix, significantly inhibits transforming growth factor-beta1 (TGF-ß1)-induced epithelial-mesenchymal transition (EMT) and metastasis in HCC. Oroxylin A blocked the TGF-ß1/Smad signaling via upregulating the non-steroidal anti-inflammatory drug-activated gene-1 (NAG-1) expression. Oroxylin A promoted NAG-1 transcription by regulating the acetylation of CCAAT/enhancer binding protein ß (C/EBPß), a transcription factor that binds to the NAG-1 promoter. In terms of the underlying mechanism, oroxylin A may interact with histone deacetylase 1 (HDAC1) by forming hydrogen bonds with GLY149 residue and induce proteasome-mediated degradation of HDAC1 subsequently impairing HDAC1-mediated deacetylation of C/EBPß and promoting the expression of NAG-1. Taken together, our findings revealed a previously unknown tumor-suppressive mechanism of oroxylin A. Oroxylin A should be further investigated as a potential clinical candidate for inhibiting HCC metastasis.

LW-213 induces cell apoptosis in human cutaneous T-cell lymphomas by activating PERK-eIF2α-ATF4-CHOP axis.

Cutaneous T-cell lymphoma (CTCL) is characterized by a heterogeneous group of extranodal non-Hodgkin lymphomas, in which monoclonal T lymphocytes infiltrate the skin. LW-213, a derivative of wogonin, was found to induce cell apoptosis in chronic myeloid leukemia (CML). In this study, we investigated the effects of LW-213 on CTCL cells and the underlying mechanisms. We showed that LW-213 (1-25 µM) dose-dependently inhibited human CTCL cell lines (Hut-102, Hut-78, MyLa, and HH) with IC50 values of around 10 µM, meanwhile it potently inhibited primary leukemia cells derived from peripheral blood of T-cell lymphoma patients. We revealed that LW-213-induced apoptosis was accompanied by ROS formation and the release of calcium from endoplasmic reticulum (ER) through IP3R-1channel. LW-213 selectively activated CHOP and induced apoptosis in Hut-102 cells via activating PERK-eIF2α-ATF4 pathway. Interestingly, the degree of apoptosis and expression of ER stress-related proteins were alleviated in the presence of either N-acetyl cysteine (NAC), an ROS scavenger, or 2-aminoethyl diphenylborinate (2-APB), an IP3R-1 inhibitor, implicating ROS/calcium-dependent ER stress in LW-213-induced apoptosis. In NOD/SCID mice bearing Hut-102 cell line xenografts, administration of LW-213 (10 mg/kg, ip, every other day for 4 weeks) markedly inhibited the growth of Hut-102 derived xenografts and prolonged survival. In conclusion, our study provides a new insight into the mechanism of LW-213-induced apoptosis, suggesting the potential of LW-213 as a promising agent against CTCL.

LW-213, a newly synthesized flavonoid, induces G2/M phase arrest and apoptosis in chronic myeloid leukemia.

Chronic myeloid leukemia (CML) is a clonal hematopoietic stem cell neoplasm characterized by an uncontrolled proliferation of moderately and well differentiated cells of the granulocytic lineage. LW-213, a newly synthesized flavonoid compound, was found to exert antitumor effects against breast cancer through inducing G2/M phase arrest. We investigated whether LW-213 exerted anti-CML effects and the underlying mechanisms. We showed that LW-213 inhibited the growth of human CML cell lines K562 and imatinid-resistant K562 (K562r) in dose- and time-dependent manners with IC50 values at the low µmol/L levels. LW-213 (5, 10, 15 µM) caused G2/M phase arrest of K562 and K562r cells via reducing the activity of G2/M phase transition-related proteins Cyclin B1/CDC2 complex. LW-213 treatment induced apoptosis of K562 and K562r cells via inhibiting the expression of CDK9 through lysosome degradation, thus leading to the suppression of RNAPII phosphorylation, down-regulation of a short-lived anti-apoptic protein MCL-1. The lysosome inhibitor, NH4Cl, could reverse the anti-CML effects of LW-213 including CDK9 degradation and apoptosis. LW-213 treatment also degraded the downstream proteins of BCR-ABL1, such as oncoproteins AKT, STAT3/5 in CML cells, which was blocked by NH4Cl. In primary CML cells and CD34+ stem cells, LW-213 maintained its pro-apoptotic activity. In a K562 cells-bearing mice model, administration of LW-213 (2.5, 5.0 mg/kg, ip, every other day for 4 weeks) dose-dependently prolonged the survival duration, and significantly suppressed huCD45+ cell infiltration and expression of MCL-1 in spleens. Taken together, our results demonstrate that LW-213 may be an efficient agent for CML treatment.

LW-213 induces G2/M cell cycle arrest through AKT/GSK3ß/ß-catenin signaling pathway in human breast cancer cells.

LW-213 is a derivative of Wogonin and the anticancer activities of Wogonin have been reported. To study whether LW-213 inhibits cancer cells and explore a possible mechanism, we investigate the compound in several cancer cell lines. We found LW-213 arrests G2/M cycle in breast cancer cells by suppression of Akt/Gsk3ß/ß-catenin signaling pathway. In compound treated cells, cell cycle-related proteins cyclin A, cyclin B1, p-CDK1, p-Cdc25C, and p-Chk2 (Thr68) were upregulated, and ß-catenin nuclear translocation was inhibited. Electrophoretic mobility shift assay revealed LW-213 inhibits binding of ß-catenin/LEF complex to DNA. GSK3ß inhibitor LiCl and siRNA against GSK3ß partially reversed G2/M arrest in breast cancer MCF-7 cells. These results suggest LW-213 triggered G2/M cell cycle arrest through suppression of ß-catenin signaling. In BALB/c mice, growth of xenotransplanted MCF-7 tumor was also inhibited after treatment of LW-213. Regulation of cyclin A, cyclin B1, and ß-catenin by LW-213 in vivo was the same as in vitro study. In conclusion, we found LW-213 exerts its anticancer effect on cell proliferation and cell cycle through repression of Akt/Gsk3ß/ß-catenin signaling pathway. LW-213 could be a potential candidate for anticancer drug development.

Aspafilioside B induces G2/M cell cycle arrest and apoptosis by up-regulating H-Ras and N-Ras via ERK and p38 MAPK signaling pathways in human hepatoma HepG2 cells.

We recently establish that aspafilioside B, a steroidal saponin extracted from Asparagus filicinus, is an active cytotoxic component. However, its antitumor activity is till unknown. In this study, the anticancer effect of aspafilioside B against HCC cells and the underlying mechanisms were investigated. Our results showed that aspafilioside B inhibited the growth and proliferation of HCC cell lines. Further study revealed that aspafilioside B could significantly induce G2 phase cell cycle arrest and apoptosis, accompanying the accumulation of reactive oxygen species (ROS), but blocking ROS generation with N-acetyl-l-cysteine (NAC) could not prevent G2/M arrest and apoptosis. Additionally, treatment with aspafilioside B induced phosphorylation of extracellular signal-regulated kinase (ERK) and p38 MAP kinase. Moreover, both ERK inhibitor PD98059 and p38 inhibitor SB203580 almost abolished the G2/M phase arrest and apoptosis induced by aspafilioside B, and reversed the expression of cell cycle- and apoptosis-related proteins. We also found that aspafilioside B treatment increased both Ras and Raf activation, and transfection of cells with H-Ras and N-Ras shRNA almost attenuated aspafilioside B-induced G2 phase arrest and apoptosis as well as the ERK and p38 activation. Finally, in vivo, aspafilioside B suppressed tumor growth in mouse xenograft models, and the mechanism was the same as in vitro study. Collectively, these findings indicated that aspafilioside B may up-regulate H-Ras and N-Ras, causing c-Raf phosphorylation, and lead to ERK and p38 activation, which consequently induced the G2 phase arrest and apoptosis. This study provides the evidence that aspafilioside B is a promising therapeutic agent against HCC.

Gambogic acid potentiates clopidogrel-induced apoptosis and attenuates irinotecan-induced apoptosis through down-regulating human carboxylesterase 1 and -2.

1. In this study, we report that gambogic acid (GA), a promising anticancer agent, potentiates clopidogrel-induced apoptosis and attenuates CPT-11-induced apoptosis by down-regulating human carboxylesterase (CES) 1 and -2 via ERK and p38 MAPK pathway activation, which provides a molecular explanation linking the effect of drug combination directly to the decreased capacity of hydrolytic biotransformation. 2. The expression levels of CES1 and CES2 decreased significantly in a concentration- and time-dependent manner in response to GA in Huh7 and HepG2 cells; hydrolytic activity was also reduced. 3. The results showed that pretreatment with GA potentiated clopidogrel-induced apoptosis by down-regulating CES1. Moreover, the GA-mediated repression of CES2 attenuated CPT-11-induced apoptosis. 4. Furthermore, the ERK and p38 MAPK pathways were involved in the GA-mediated down-regulation of CES1 and CES2. 5. Taken together, our data suggest that GA is a potent repressor of CES1 and CES2 and that combination with GA will affect the metabolism of drugs containing ester bonds.

Wogonin suppresses human alveolar adenocarcinoma cell A549 migration in inflammatory microenvironment by modulating the IL-6/STAT3 signaling pathway.

Increasing evidence from various clinical and experimental studies has demonstrated that the inflammatory microenvironment facilitates tumor metastasis. Clinically, it will be a promising choice to suppress tumor metastasis by targeting inflammatory microenvironment. Our previous studies have demonstrated that wogonin (a bioflavonoid isolated from the traditional Chinese medicine of Huang-Qin) possesses the anti-metastatic and anti-inflammatory activity, but we have little idea about its efficacy on inflammatory-induced tumor metastasis and the mechanism underlying it. In this study, we focused on epithelial mesenchymal transition (EMT), the first step of tumor metastasis, to evaluate the effects of wogonin on tumor metastasis in inflammatory microenvironment. We found that wogonin inhibited THP-1 conditioned-medium- (CM-) and IL-6-induced EMT by inactivating STAT3 signal. And in wogonin-treated A549 cells which pretreated with THP-1 CM or IL-6, the expression level of E-cadherin, an EMT negative biomarker, increased while that of N-cadherin, Vimentin, and EMT-related transcription factors including Snail and Twist decreased. Moreover, wogonin inhibited IL-6-induced phosphorylation of STAT3, prevented p-STAT3 dimer translocation into the nucleus, and suppressed the DNA-binding activity of p-STAT3. Interestingly, similar results were obtained in the tumor xenografts mice, including downregulation of p-STAT3, N-cadherin, and Vimentin while up-regulation of E-cadherin. Wogonin also inhibit the metastasis of A549 cells in vivo. Taken all data together, we concluded that wogonin suppresses tumor cells migration in inflammatory microenvironment by inactivating STAT3 signal.

Wogonin prevents lipopolysaccharide-induced acute lung injury and inflammation in mice via peroxisome proliferator-activated receptor gamma-mediated attenuation of the nuclear factor-kappaB pathway.

Acute lung injury (ALI) from a variety of clinical disorders, characterized by diffuse inflammation, is a cause of acute respiratory failure that develops in patients of all ages. Previous studies reported that wogonin, a flavonoid-like chemical compound which was found in Scutellaria baicalensis, has anti-inflammatory effects in several inflammation models, but not in ALI. Here, the in vivo protective effect of wogonin in the amelioration of lipopolysaccharide (LPS) -induced lung injury and inflammation was assessed. In addition, the in vitro effects and mechanisms of wogonin were studied in the mouse macrophage cell lines Ana-1 and RAW264.7. In vivo results indicated that wogonin attenuated LPS-induced histological alterations. Peripheral blood leucocytes decreased in the LPS-induced group, which was ameliorated by wogonin. In addition, wogonin inhibited the production of several inflammatory cytokines, including tumour necrosis factor-α, interleukin-1ß (IL-1ß) and IL-6, in the bronchoalveolar lavage fluid and lung tissues after LPS challenge, while the peroxisome proliferator-activated receptor γ (PPARγ) inhibitor GW9662 reversed these effects. In vitro results indicated that wogonin significantly decreased the secretion of IL-6, IL-1ß and tumour necrosis factor-α in Ana-1 and RAW264.7 cells, which was suppressed by transfection of PPARγ small interfering RNA and GW9662 treatment. Moreover, wogonin activated PPARγ, induced PPARγ-mediated attenuation of the nuclear translocation and the DNA-binding activity of nuclear factor-κB in vivo and in vitro. In conclusion, all of these results showed that wogonin may serve as a promising agent for the attenuation of ALI-associated inflammation and pathology by regulating the PPARγ-involved nuclear factor-κB pathway.

Wogonin reverses hypoxia resistance of human colon cancer HCT116 cells via downregulation of HIF-1α and glycolysis, by inhibiting PI3K/Akt signaling pathway.

Hypoxia induced drug resistance is a major obstacle in the development of effective cancer therapy. In the present study, the reversal abilities of wogonin on the hypoxia resistance and the underlying mechanisms were discovered. MTT assay revealed that hypoxia increased maximal 1.71-, 2.08-, and 2.15-fold of IC50 toward paclitaxel, ADM, and DDP in human colon cancer cell lines HCT116, respectively. Furthermore, wogonin showed strong reversal potency in HCT116 cells in hypoxia and the RF reached 2.05. hypoxia-inducible factor-1α (HIF-1α) can activate the expression of target genes involved in glycolysis. Wogonin decreased the expression of glycolysis-related proteins (HKII, PDHK1, LDHA), glucose uptake, and lactate generation in a dose-dependent manner. Further, Western blot experiments exhibited that wogonin could down regulate HIF-1α expression and glycolysis through inhibiting PI3K/Akt signaling pathway, which might be the mechanism of reversal resistance of wogonin. Also, wogonin could inhibit the growth of transplantable tumors and the expression of HIF-1α, glycolysis-related proteins and PI3K/Akt in vivo. In summary, wogonin could be a good candidate for the development of new multidrug resistance (MDR) reversal agent and its reversal mechanism probably is due to the suppression of HIF-1α expression via inhibiting PI3K/Akt signaling pathway.

Oroxylin A prevents inflammation-related tumor through down-regulation of inflammatory gene expression by inhibiting NF-κB signaling.

Increasing evidence suggests that inflammatory microenvironment plays a critical role at different stages of tumor development. However, the molecular mechanisms of the interaction between inflammation and proliferation of cancer cells remain poorly defined. Here we reported the inhibitory effects of oroxylin A on the inflammation-stimulated proliferation of tumor cells and delineated the mechanism of its action. The results indicated that treatment with oroxylin A inhibited NF-κB p65 nuclear translocation and phosphorylation of IκBα and IKKα/ß in both human colon tumor HCT116 cells and human monocytes THP-1 cells. In addition, in THP-1 cells, oroxylin A significantly suppressed lipopolysaccharide (LPS)-induced secretion of prototypical proinflammatory cytokine IL-6 but not IL-1ß, and it was confirmed at the transcription level. Moreover, oroxylin A inhibited the proliferation of HCT116 cells stimulated by LPS-induced THP-1 cells in co-culture microenvironment. In summary, oroxylin A modulated NF-κB signaling pathway involved in inflammation-induced cancer initiation and progression and therefore could be a potential cancer chemoprevention agent for inflammation-related cancer.

Enhanced 5-fluorouracil cytotoxicity in high COX-2 expressing hepatocellular carcinoma cells by wogonin via the PI3K/Akt pathway.

Combination therapies may increase the antitumor effects and reduce the adverse effects for the treatment of hepatocellular carcinoma. In this study, we determined the effects of 5-fluorouracil alone or in combination with wogonin in vitro and in vivo, and we investigated the possible mechanisms. The combination of these 2 drugs led to a decrease in survival and a significant synergistic inhibitory effect on high COX-2 expression in SMMC-7721 hepatocellular carcinoma (HCC) cells. Furthermore, the results show that this combination inhibits COX-2 expression and increases sensitivity to chemotherapeutic agents partly through regulating the PI3K/Akt signaling pathway. Moreover, the combination treatment caused a significant growth inhibition of human tumor xenografts in vivo. In conclusion, wogonin may increase the cytotoxicity of some antineoplastic agents and it can be used in combination with these agents as a novel therapeutic regimen for HCC treatment.

Drug resistance associates with activation of Nrf2 in MCF-7/DOX cells, and wogonin reverses it by down-regulating Nrf2-mediated cellular defense response.

Acquired resistance to doxorubicin (DOX) is a serious therapeutic problem in breast cancer patients. In this study, we investigated whether nuclear factor erythroid 2-related factor 2 (Nrf2) was associated with drug resistant in DOX resistant MCF-7 (MCF-7/DOX) cells, and if wogonin, a flavonoid isolated from the root of Scutellaria baicalensis Georgi, could reverse drug resistance in MCF-7/DOX cells. We found that the endogenous expression of Nrf2 as well as its target proteins heme oxygenase-1 (HO-1), NADP(H):quinone oxidoreductase (NQO) in MCF-7/DOX cells was higher than that in MCF-7 cells. Tert-butylhydroquinone treatment increased the expression Nrf2, HO-1, and NQO-1, and enhanced resistance of MCF-7 cells to DOX. Similarly, intracellular Nrf2 protein level was significantly decreased in MCF-7/DOX cells and DOX resistance was partially reversed by Nrf2 siRNA. Wogonin downregulated the Nrf2-dependent response and partly reversed DOX resistance in MCF-7/DOX cells. These results suggested that activation of Nrf2 was associated with drug resistance in MCF-7/DOX cells. Wogonin reversed drug resistance and its reversal mechanism might be due to the suppression of Nrf2 signaling pathway, indicating the feasibility of using Nrf2 inhibitors to increase efficacy of chemotherapeutic drugs.

Norisoboldine alleviates joint destruction in rats with adjuvant-induced arthritis by reducing RANKL, IL-6, PGE(2), and MMP-13 expression.

AIM: To explore the effects of norisoboldine (NOR), a major isoquinoline alkaloid in Radix Linderae, on joint destruction in rats with adjuvant-induced arthritis (AIA) and its underlying mechanisms. METHODS: AIA was induced in adult male SD rats by intradermal injection of Mycobacterium butyricum in Freund's complete adjuvant at the base of the right hind paw and tail. From d 14 after immunization, the rats were orally given NOR (7.5, 15, or 30 mg/kg) or dexamethasone (0.5 mg/kg) daily for 10 consecutive days. Joint destruction was evaluated with radiological scanning and H&E staining. Fibroblast-like synoviocytes (FLS) were prepared from fresh synovial tissues in the AIA rats. The expression of related proteins and mRNAs were detected by ELISA, Western blotting and RT-PCR. RESULTS: In AIA rats, NOR (15 and 30 mg/kg) significantly decreased the swelling of paws and arthritis index scores, and elevated the mean body weight. NOR (30 mg/kg) prevented both the infiltration of inflammatory cells and destruction of bone and cartilage in joints. However, NOR (15 mg/kg) only suppressed the destruction of bone and cartilage, but did not obviously ameliorate synovial inflammation. NOR (15 and 30 mg/kg) significantly decreased the serum levels of receptor activator of nuclear factor κB ligand (RANKL), IL-6, PGE2, and MMP-13, but not the osteoprotegerin and MMP-1 levels. The mRNA levels of RANKL, IL-6, COX-2, and MMP-13 in synovium were also suppressed. Dexamethasone produced similar effects in AIA rats as NOR did, but without elevating the mean body weight. In the cultured FLS, treatment with NOR (10 and 30 mmol/L) significantly decreased the secretion of RANKL, IL-6, PGE2, and MMP-13 proteins. Furthermore, the treatment selectively prevented the activation of MAPKs, AKT and transcription factor AP-1 component c-Jun, but not the recruitment of TRAF6 or the activation of JAK2/STAT3. Treatment of the cultured FLS with the specific inhibitors of p38, ERK, AKT, and AP-1 significantly decreased the secretion of RANKL, IL-6, PGE2, and MMP-13 proteins. CONCLUSION: NOR can alleviate joint destruction in AIA rats by reducing RANKL, IL-6, PGE2, and MMP-13 expression via the p38/ERK/AKT/AP-1 pathway.

Synthesis and evaluation of gambogic acid derivatives as antitumor agents. Part III.

Gambogic acid (GA) has been reported as a potent apoptosis inducer. Previously, we have reported chemical modification at C(34) and C(39) of GA, leading to some agents with improved activity. To investigate the further structure-activity relationship (SAR) and preliminary mechanism of GA activity, a series of derivatives with modified prenyl side chains of GA were synthesized and evaluated. Most of the derivatives showed potent inhibitory activities against the proliferation of HepG2 and A549 cell lines. Compound 4 was selected for further mechanistic studies due to its outstanding activity. It was established that 4 induces the apoptosis of HepG2 cells by using Annexin-V/PI double staining and Western blot assay, thus, compound 4 can serve as a promising lead compound for the development of novel apoptosis in anticancer treatment.

[Study on directional separation of picroside II from extract of traditional Chinese medicine by molecularly imprinted technology].

Picroside II, separated from Chinese herbal medicine, is an active compound with neroprotective activity. Molecularly imprinted polymers (MIPs) have high affinity toward template molecules synthesized by molecularly imprinted technology for its specific combined sites, which can overcome the shortcomings of traditional separation methods, such as complex operation and low efficiency. In this paper, MIPs were prepared by precipitation polymerization with picroside II as the template molecule, 1-vinylimidazole (1-Vinyl) as functional monomer, ethylene glycol dimethacrylate (EDMA) as cross-linker. The morphology of MIPs was characterized by scanning electronmicroscope (SEM) and its static adsorption capacity was measured by the scatchard equation. The results showed that picroside II MIPs have spherical shape, and most of them are uniform in size. Furthermore, the maximum binding capacity (Q(max)) of MIPs is 3.02 mg x g(-1), higher than that of non-imprinted polymers (NIPs). This result indicated that picroside II MIPs with good morphology and high targeted affinity toward the template molecules can be prepared by precipitation polymerization, which can be used to separate picroside II and its analogies from extract of Chinese herbal medicine. In addition, this method has the advantages of good environment and simple operation, which might offer a novel method for the efficient separation of picroside II in the traditional herbal medicines.

[Recent advances in chemistry and biology of gamboge].

Gamboge, the resin of Garcinia hanburyi has had a long history of use as the traditional dye as well as a complementary and alternative medicine. The antitumor activities of gamboge have been well demonstrated by inhibiting the growth and progression of cancer cells both in vitro and in vivo. In order to further clarify the mode of action of gamboge, there are three key questions needed to be answered, including what's in gamboge? How do the chemical components from gamboge work on cancer cells? How do biological systems work on the chemical components from gamboge after administration? In this review, we summarize the explorations of the answers toward these questions according to the recent progress in both of chemistry and biology research of gamboge. In addition, the implication in the future research and discovery of the caged G. xanthones as anticancer agents is also discussed.

LYG-202 augments tumor necrosis factor-α-induced apoptosis via attenuating casein kinase 2-dependent nuclear factor-κB pathway in HepG2 cells.

Tumor necrosis factor-α (TNF-α) is being used as an antineoplastic agent in treatment regimens of patients with locally advanced solid tumors, but TNF-α alone is only marginally active. In clinical use, it is usually combined with other chemical agents to increase its tumor response rate. Our previous studies reported that LYG-202 (5-hydroxy-8-methoxy-7-(4-(4-methylpiperazin-1-yl)butoxy)-2-phenyl-4H-chromen-4-one), a synthesized flavonoid with a piperazine substitution, has antiproliferative, antiangiogenic, and proapoptotic activities in multiple cancer cell lines. Here we evaluated the antineoplastic effect of TNF-α and analyzed the mechanism underlying its combination with LYG-202. Our results indicated that LYG-202 significantly increased the cytostatic and proapoptotic activity of TNF-α in HepG2 cells and heightened the protein level of apoptosis-related genes including caspase-3, caspase-8/9, cleaved poly(ADP-ribose) polymerase, and Bid. The fact that LYG-202 had a fitness score similar to that of the casein kinase 2 (CK2) inhibitor naphthyridine-8-carboxylate (CX-4945) implied to us that it may serve as a potential candidate for CK2 inhibitor, and the kinase activity assay suggested that LYG-202 significantly inhibited CK2 activity. Moreover, the electrophoretic mobility shift assay and luciferase assay showed that LYG-202 blocked the TNF-α-induced nuclear factor-κB (NF-κB) survival signaling pathway primarily by inactivating protein kinase CK2. In murine xenograft models, we also found that LYG-202 enhanced TNF-α antineoplastic activity and inhibited CK2 activity and NF-κB-regulated antiapoptotic gene expression. All these results showed that LYG-202 enhanced TNF-α-induced apoptosis by attenuating the CK2-dependent NF-κB pathway and probably is a promising agent in combination with TNF-α.

Oroxylin A improves the sensitivity of HT-29 human colon cancer cells to 5-FU through modulation of the COX-2 signaling pathway.

5-Fluorouracil (5-FU) is a principal drug for the treatment of colorectal cancer. Due to its low response and high toxicity, synergistic effects of 5-FU in combination with other drugs have been widely researched. This study investigated whether oroxylin A improved the sensitivity of HT-29 human colon cancer cells to 5-FU. A correlation between COX-2 inhibition by oroxylin A and a synergistic effect of 5-FU on the growth of HT-29 cells was observed, and a COX-2 pathway for this effect was recognized; oroxylin A evidently elevated the level of reactive oxygen species in HT-29 cells, which subsequently inhibited COX-2 expression and enhanced the susceptibility of HT-29 cells to 5-FU. Likely also related to COX-2 inhibition, oroxylin A decreased PGE(2) levels in HT-29 cells. The synergistic effect of 5-FU induced by oroxylin A was also found in the suppression of Bcl-2 and in the activation of P53, Bax, PARP, and procaspase-3 proteins in HT-29 cells. Ultimately, a combination of 5-FU with oroxylin A significantly reduced the growth of HT-29 tumors in nude mice compared with treatment with 5-FU or oroxylin A alone. In conclusion, a combination of 5-FU and oroxylin A has a significant synergistic effect in the inhibition of HT-29 cell proliferation in vitro and controls HT-29 tumor growth in vivo. This synergistic effect may be mainly related to COX-2 inhibition by oroxylin A in HT-29 cells.

Oroxylin A reverses multi-drug resistance of human hepatoma BEL7402/5-FU cells via downregulation of P-glycoprotein expression by inhibiting NF-κB signaling pathway.

In this study, oroxylin A showed strong reversal potency in BEL7402/5-FU cells and the reversal fold (RF) reached 4.69. Simultaneously, rhodamine-123 accumulation assay and flow cytometry analysis demonstrated oroxylin A could increase drug accumulation. When combined with oroxylin A, 5-FU showed inducing apoptosis effect more seriously in DAPI staining experiment. Moreover, the mRNA and protein expression of multi-drug resistance gene (MDR1) were also decreased by oroxylin A. Further experiments exhibited that oroxylin A can downregulate P-gp expression through inhibiting nuclear factor-κB (NF-κB) signaling pathway, which might be the mechanism of reversal resistance of oroxylin A. In summary, oroxylin A could be a good candidate for the development of new MDR reversal agent and its reversal mechanism probably due to the suppression of P-gp expression via inhibiting NF-κB signaling pathway.