Concurrent inhibition of pBADS99 synergistically improves MEK inhibitor efficacy in KRASG12D-mutant pancreatic ductal adenocarcinoma.

Therapeutic targeting of KRAS-mutant pancreatic ductal adenocarcinoma (PDAC) has remained a significant challenge in clinical oncology. Direct targeting of KRAS has proven difficult, and inhibition of the KRAS effectors have shown limited success due to compensatory activation of survival pathways. Being a core downstream effector of the KRAS-driven p44/42 MAPK and PI3K/AKT pathways governing intrinsic apoptosis, BAD phosphorylation emerges as a promising therapeutic target. Herein, a positive association of the pBADS99/BAD ratio with higher disease stage and worse overall survival of PDAC was observed. Homology-directed repair of BAD to BADS99A or small molecule inhibition of BADS99 phosphorylation by NCK significantly reduced PDAC cell viability by promoting cell cycle arrest and apoptosis. NCK also abrogated the growth of preformed colonies of PDAC cells in 3D culture. Furthermore, high-throughput screening with an oncology drug library to identify potential combinations revealed a strong synergistic effect between NCK and MEK inhibitors in PDAC cells harboring either wild-type or mutant-KRAS. Mechanistically, both mutant-KRAS and MEK inhibition increased the phosphorylation of BADS99 in PDAC cells, an effect abrogated by NCK. Combined pBADS99-MEK inhibition demonstrated strong synergy in reducing cell viability, enhancing apoptosis, and achieving xenograft stasis in KRAS-mutant PDAC. In conclusion, the inhibition of BADS99 phosphorylation enhances the efficacy of MEK inhibition, and their combined inhibition represents a mechanistically based and potentially effective therapeutic strategy for the treatment of KRAS-mutant PDAC.

Vertical pathway inhibition of receptor tyrosine kinases and BAD with synergistic efficacy in triple negative breast cancer.

Aberrant activation of the PI3K/AKT signaling axis along with the sustained phosphorylation of downstream BAD is associated with a poor outcome of TNBC. Herein, the phosphorylated to non-phosphorylated ratio of BAD, an effector of PI3K/AKT promoting cell survival, was observed to be correlated with worse clinicopathologic indicators of outcome, including higher grade, higher proliferative index and lymph node metastasis. The structural optimization of a previously reported inhibitor of BAD-Ser99 phosphorylation was therefore achieved to generate a small molecule inhibiting the phosphorylation of BAD at Ser99 with enhanced potency and improved oral bioavailability. The molecule 2-((4-(2,3-dichlorophenyl)piperazin-1-yl)(pyridin-3-yl)methyl) phenol (NCK) displayed no toxicity at supra-therapeutic doses and was therefore assessed for utility in TNBC. NCK promoted apoptosis and G0/G1 cell cycle arrest of TNBC cell lines in vitro, concordant with gene expression analyses, and reduced in vivo xenograft growth and metastatic burden, demonstrating efficacy as a single agent. Additionally, combinatorial oncology compound library screening demonstrated that NCK synergized with tyrosine kinase inhibitors (TKIs), specifically OSI-930 or Crizotinib in reducing cell viability and promoting apoptosis of TNBC cells. The synergistic effects of NCK and TKIs were also observed in vivo with complete regression of a percentage of TNBC cell line derived xenografts and prevention of metastatic spread. In patient-derived TNBC xenograft models, NCK prolonged survival times of host animals, and in combination with TKIs generated superior survival outcomes to single agent treatment. Hence, this study provides proof of concept to further develop rational and mechanistic based therapeutic strategies to ameliorate the outcome of TNBC.

Small molecule inhibition of TFF3 overcomes tamoxifen resistance and enhances taxane efficacy in ER+ mammary carcinoma.

Even though tamoxifen has significantly improved the survival of estrogen receptor positive (ER+) mammary carcinoma (MC) patients, the development of drug resistance with consequent disease recurrence has limited its therapeutic efficacy. Trefoil factor-3 (TFF3) has been previously reported to mediate anti-estrogen resistance in ER+MC. Herein, the efficacy of a small molecule inhibitor of TFF3 (AMPC) in enhancing sensitivity and mitigating acquired resistance to tamoxifen in ER+MC cells was investigated. AMPC induced apoptosis of tamoxifen-sensitive and resistant ER+MC cells and significantly reduced cell survival in 2D and 3D culture in vitro. In addition, AMPC reduced cancer stem cell (CSC)-like behavior in ER+MC cells in a BCL2-dependent manner. Synergistic effects of AMPC and tamoxifen were demonstrated in ER+MC cells and AMPC was observed to improve tamoxifen efficacy in tamoxifen-sensitive cells and to re-sensitize cells to tamoxifen in tamoxifen-resistant ER+MC in vitro and in vivo. Additionally, tamoxifen-resistant ER+MC cells were concomitantly resistant to anthracycline, platinum and fluoropyrimidine drugs, but not to Taxanes. Taxane treatment of tamoxifen-sensitive and resistant ER+MC cells increased TFF3 expression indicating a combination vulnerability for tamoxifen-resistant ER+MC cells. Taxanes increased CSC-like behavior of tamoxifen-sensitive and resistant ER+MC cells which was reduced by AMPC treatment. Taxanes synergized with AMPC to promote apoptosis and reduce CSC-like behavior in vitro and in vivo. Hence, AMPC restored the sensitivity of tamoxifen and enhanced the efficacy of Taxanes in tamoxifen-resistant ER+MC. In conclusion, pharmacological inhibition of TFF3 may serve as an effective combinatorial therapeutic strategy for the treatment of tamoxifen-resistant ER+MC.

CXC Chemokine Signaling in Progression of Epithelial Ovarian Cancer: Theranostic Perspectives.

Patients with epithelial ovarian cancer (EOC) are often diagnosed at an advanced stage due to nonspecific symptoms and ineffective screening approaches. Although chemotherapy has been available and widely used for the treatment of advanced EOC, the overall prognosis remains dismal. As part of the intrinsic defense mechanisms against cancer development and progression, immune cells are recruited into the tumor microenvironment (TME), and this process is directed by the interactions between different chemokines and their receptors. In this review, the functional significance of CXC chemokine ligands/chemokine receptors (CXCL/CXCR) and their roles in modulating EOC progression are summarized. The status and prospects of CXCR/CXCL-based theranostic strategies in EOC management are also discussed.

Trefoil factor 3 promotes pancreatic carcinoma progression via WNT pathway activation mediated by enhanced WNT ligand expression.

Pancreatic ductal adenocarcinoma (PDAC) is a major cause of cancer-related mortality with a dismal prognosis that has changed little over the past few decades. Further understanding of the molecular pathology of PDAC progression is urgently required in order to improve the prognosis of patients with PDAC. Herein, it was observed that trefoil factor 3 (TFF3) expression was elevated in PDAC, and was positively correlated with a worse overall patient survival outcome. Forced expression of TFF3 promoted oncogenic functions of PDAC cells in vitro including cell proliferation, survival, foci formation, cancer stem cell-like behavior and invasion, ex vivo colony growth in 3D-Matrigel, and xenograft growth in vivo. Depletion or pharmacological inhibition of TFF3 inhibited these same processes. RNA-Seq analysis and subsequent mechanistic analyses demonstrated that TFF3 increased the expression of various WNT ligands to mediate WNT pathway activation required for TFF3-stimulated PDAC progression. Combined pharmacological inhibition of TFF3 and WNT signaling significantly attenuated PDAC xenograft growth and potentiated the therapeutic efficacy of gemcitabine in both ex vivo and in vivo models. Hence, a mechanistic basis for combined inhibition of pathways enhancing PDAC progression is provided and suggests that inhibition of TFF3 may assist to ameliorate outcomes in PDAC.

Mitochondria: The metabolic switch of cellular oncogenic transformation.

Mitochondria, well recognized as the "powerhouse" of cells, are maternally inherited organelles with bacterial ancestry that play essential roles in a myriad of cellular functions. It has become profoundly evident that mitochondria regulate a wide array of cellular and metabolic functions, including biosynthetic metabolism, cell signaling, redox homeostasis, and cell survival. Correspondingly, defects in normal mitochondrial functioning have been implicated in various human malignancies. Cancer development involves the activation of oncogenes, inactivation of tumor suppressor genes, and impairment of apoptotic programs in cells. Mitochondria have been recognized as the site of key metabolic switches for normal cells to acquire a malignant phenotype. This review outlines the role of mitochondria in human malignancies and highlights potential aspects of mitochondrial metabolism that could be targeted for therapeutic development.

The mycoestrogen zeranol at high dosage antagonizes transient receptor potential channel activities in 3T3 L1 cells.

Recent findings have revealed that exposure to environmental contaminants may result in obesity and pose a health threat to the general public. As the activity of transient receptor potential channels (TRPs) plays a permissive role in adipogenesis, the interactions between TRPs and some food pollutants, i.e. bisphenol A, di (2-ethylhexyl) phthalate, zearalenone, and zeranol at 10 µM were investigated in the present study. TRP-V1,-V3, -C4 and -C6 are reported to be differentially expressed in the adipocyte differentiation, and immunoblotting was performed to quantify changes in these TRPs affected by the pollutants. Our result indicated that the mycoestrogen zeranol or α-zearalanol suppressed the expression of the V1 and C6 isoforms. Subsequently, confocal microscopy was used to measure the calcium inflow repressed by zeranol from 0.1 µM to 10 µM. Oil Red O staining was used to determine the differentiation of 3T3 L1 preadipocytes. Zeranol could suppress the expression of TRP-V1 and -C6 protein and inhibit the associated flow of calcium into the cytosol of 3T3 L1 cells. Its IC50 value for inhibiting calcium inflow stimulated by 40 µM capsaicin or 10 µM GSK1702934A was estimated to be around 6 µM. Reduced TRP-V1 or -C6 activity might result in promoting adipogenesis. In conclusion, this study demonstrated that zeranol could potentiate fat cell differentiation through antagonizing TRP-V1 and -C6 activities.

Long non-coding RNAs in recurrent ovarian cancer: Theranostic perspectives.

Nearly 70% of ovarian cancer (OC) patients experience recurrence within the first 2 years after initial treatment. Emerging evidence indicates that long non-coding RNAs (lncRNAs) play a pivotal role in the pathogenesis of OC progression, resistance to therapy and recurrent OC (ROC). Transcriptome profiling studies have reported differential expression patterns of lncRNAs in OC which are related to increased cell invasion, metastasis and drug resistance. In this review, we highlighted the roles of lncRNAs in OC progression and outlined the potential molecular mechanisms by which lncRNAs impact on ROC. Recent advances using lncRNAs as potential biomarkers for screening, detection, prediction, response to therapy and as therapeutic targets are discussed.

The livestock growth-promoter zeranol facilitates GLUT4 translocation in 3T3 L1 adipocytes.

Zeranol is an approved but controversial growth-promoting agent for livestock in North America. It is a mycotoxin metabolite secreted by the Fusarium family fungi. The regulatory bodies in this region have established the acceptable daily intake and exposure below the level would not significantly increase the health risk for humans. However, their European counterparts have yet to establish an acceptable level and do not permit the use of this agent in farm animals. Given the growth-promoting ability of zeranol, its effect on energy metabolism was investigated in the current study. Our results indicated that zeranol could induce glucose transporter type 4 (GLUT4) expression in 3T3 L1 cells at 10 µM and initiate the translocation of the glucose transporter to the membrane as assayed by confocal microscopy. The translocation was likely triggered by the increase of GLUT4 and p-Akt. The insulin signal transduction pathway of glucose translocation was analyzed by Western blot analysis. Since no increase in the phosphorylated insulin receptor substrate in zeranol-treated cells was evidenced, the increased p-Akt and GLUT4 amount should be the mechanism dictating the GLUT4 translocation. In summary, this study showed that zeranol could perturb glucose metabolism in differentiated 3T3 L1 adipocytes. Determining the growth-promoting mechanism is crucial to uncover an accepted alternative to the general public.

The activity of transient receptor potential channel C-6 modulates the differentiation of fat cells.

Previously, the V1-3 isoforms of the transient receptor potential channel (TRP) have been shown to promote or prevent adipocyte differentiation. In the current study, the C isoforms were screened for blocking adipogenesis. The hypothesis that the TRP classic or canonical (TRPC) deters adipocyte differentiation was investigated in 3T3-L1 cells employing the channel-specific activator and antagonist, silencing, and overexpression techniques. Fat accumulation in cells was visualized by Oil Red O staining. Intracellular calcium inflow was estimated by confocal microscopy. A high-fat (HF) feeding study was also performed on C57BL/6J mice to verify the findings in the cell model. Among the 6 C isoforms tested, only TRPC-6 inhibited the differentiation of fat cells. The phytochemical quercetin induced the channel protein expression. Calcium-imaging results also revealed that the flavonoid could trigger calcium inflow. Coadministration of quercetin (1 or 20 mg/kg body weight) in an HF diet prevented TRPC-6 from declining and attenuated phosphorylated (p)-PKB and PI3k, as well as the proliferation of visceral fat cells. The present study illustrated that TRPC-6 activation could perturb adipocyte differentiation. The food flavonoid quercetin was a TRPC-6 inducer and activator and it could prevent adipogenesis in mice.-Tan, Y. Q., Kwan, H. Y., Yao, X., Leung, L. K. The activity of transient receptor potential channel C-6 modulates the differentiation of fat cells.

PCP4/PEP19 upregulates aromatase gene expression via CYP19A1 promoter I.1 in human breast cancer SK-BR-3 cells.

The Purkinje cell protein 4/peptide 19 (PCP4/PEP19) is a novel breast cancer cell expressing peptide, originally found in the neural cells as an anti-apoptotic factor, could inhibit cell apoptosis and enhance cell migration and invasion in human breast cancer cell lines. The expression of PCP4/PEP19 is induced by estrogens in estrogen receptor-positive (ER+) MCF-7 cells but also highly expressed in ER- SK-BR-3 cells. In this study, we investigated the effects of PCP4/PEP19 on aromatase gene expression in MCF-7 and SK-BR-3 human breast cancer cells. In SK-BR-3 cells but not in MCF-7 cells, PCP4/PEP19 knockdown by siRNA silencing decreased the aromatase expression in gene transcriptional level. When PCP4/PEP19 was overexpressed by CMV promoter-driven PCP4/PEP19 expressing plasmid transfection, aromatase gene transcription increased in SK-BR-3 cells. This aromatase gene transcription is mainly mediated through promoter region PI.1, which is usually active in the placental tissue but not in the breast cancer tissue. These results indicate a new function of PCP4/PEP19 that would enhance aromatase gene upregulation to supply estrogens in heterogeneous cancer microenvironment.

Co-administrating apigenin in a high-cholesterol diet prevents hypercholesterolaemia in golden hamsters.

OBJECTIVES: Hypercholesterolaemia is a major risk factor for developing atherosclerosis. Increased consumption of fruits and vegetables is recommended to hypercholesterolaemic patients. In this study, the hypocholesterolaemic effect of apigenin and luteolin was evaluated in a hamster model. METHODS: Hamsters were put on a high-cholesterol diet for 9 weeks, and apigenin or luteolin was administered in the diet at 60 and 300 ppm. KEY FINDINGS: Both apigenin and luteolin supplementations could attenuate the aorta plaque formation by 30% and 20%, respectively. Apigenin-fed hamsters at both dosages displayed a 1.5-fold increase in hepatic Ldlr expression and a 40% reduction in non-HDL cholesterol level as compared with those in the control fed a high-cholesterol (HC) diet. Besides, faecal elimination of cholesterol was facilitated by 20% in the hamsters with high apigenin consumption. Suppressing the expression of the cholesterol transporter ncp1l1 in the intestinal mucosa could block the cholesterol absorption and promote its elimination. The differential regulations of ncp1l1 and Ldlr appeared to be the underlying hypocholesterolaemic mechanism of apigenin in this model system. Luteolin supplementation, on the other hand, had no effect on the blood cholesterol. CONCLUSIONS: This study illustrated that dietary administration of apigenin attenuated HC feeding-induced hypercholesterolemia in hamsters.

The citrus flavonone hesperetin attenuates the nuclear translocation of aryl hydrocarbon receptor.

The environmental polycyclic aromatic hydrocarbons (PAH) and dioxins are carcinogens and their adverse effects have been largely attributed to the activation of AhR. Hesperetin is a flavonone found abundantly in citrus fruits and has been shown to be a biologically active agent. In the present study, the effect of hesperetin on the nuclear translocation of AhR and the downstream gene expression was investigated in MCF-7 cells. Confocal microscopy indicated that 7, 12-dimethylbenz[α]anthracene (DMBA) or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) -induced nuclear translocation of AhR was deterred by hesperetin treatment. The reduced nuclear translocation could also be observed in Western analysis. Reporter-gene assay further illustrated that the induced XRE transactivation was weakened by the treatment of hesperetin. Quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) assay demonstrated that the gene expressions of CYP1A1, 1A2, and 1B1 followed the same pattern of AhR translocation. These results suggested that hesperetin counteracted AhR transactivation and suppressed the downstream gene expression.

Apigenin and luteolin display differential hypocholesterolemic mechanisms in mice fed a high-fat diet.

Hypercholesterolemia is a major risk factor in the development of atherosclerosis. High blood cholesterol can be the result of increased biosynthesis or reduced elimination of cholesterol in the system. Increased consumption of fruits and vegetables is recommended for patients suffering from hypercholesterolemia. The plant food flavones apigenin and luteolin have previously been shown to suppress the synthesis of cholesterol in human hepatocytes. The effectiveness of these two flavones in controlling blood cholesterol was examined in a mouse model in the present study. Mice were fed a high-fat diet and apigenin or luteolin at 50 and 250 ppm was mixed in the diet. After 8 weeks of treatment, the administration of 250 ppm apigenin or 250 ppm luteolin could modulate the total and serum non-HDL cholesterol. The expressions of srebf-2 mRNA, Srebp-2 protein and Hmgcr protein were decreased in the livers of apigenin-treated mice; meanwhile, AMPK was activated in this group of mice. In contrast, suppressed ncp1l1 and induced abcg-5/8 mRNA expressions were seen in the intestinal mucosa of luteolin-fed animals. Increased fecal cholesterol content was also observed in the luteolin-treated mice. These results revealed that apigenin suppressed the biosynthesis of cholesterol, whereas luteolin promoted the elimination of cholesterol. In summary, this study illustrated that the two flavones could attenuate high-fat feeding-induced hypercholesterolemia in two different mechanisms.

Exposure to 2,2',4,4'-tetrabromodiphenyl ether at late gestation modulates placental signaling molecules in the mouse model.

Polybrominated diphenyl ethers (PBDEs) are flame retardants generally employed in manufacturing household items. Surface water may remove and carry these chemicals to the drainage upon disposal of the items, and ultimately the chemicals enter our food chain. 2,2',4,4'-Tetrabromodiphenyl ether (BDE-47) is a PBDE congener commonly found in contaminated seafood. The placenta is the site of nutrient exchange and is responsible for reproductive hormone secretion during pregnancy. In the present study, pregnant ICR mice were given p.o. daily doses of BDE-47 at 0, 0.36, 3.6, 36 mg/kg for 4 days (from E13.5 to E16.5). Compared to the control group, increased rates of stillborn and low birth weight were observed in mice treated with 36 mg BDE-47/kg. Plasma testosterone and progesterone levels were reduced in mice treated with 36 mg BDE-47/kg. In addition, the group treated with 3.6 mg/kg of BDE-47 displayed decreased growth hormone (Gh) peptide expression in the placental tissue extracted at E17.5. As this peptide stimulates growth, the expression pattern might suggest compromised fetal development. Further analysis indicated that mitogen-activated protein kinases (MAPK) were activated in the placental tissue of the BDE-47-treatment groups. The activation of these signaling molecules might affect the hormonal and other physiological functions in the tissue.

The flame retardant 2,2',4,4'-Tetrabromodiphenyl ether enhances the expression of corticotropin-releasing hormone in the placental cell model JEG-3.

Polybrominated diphenyl ethers (PBDEs) are chemicals used as flame retardants in household products. After disposing of these items, PBDEs leach from the products by surface water. BDE-47 is a PBDE congener commonly isolated from contaminated food and is the most studied isomer. The placenta is the major source of hormones during pregnancy, and an elevated level of corticotrophin-releasing hormone (CRH) is associated with premature delivery. In the present study, we examined changes in the placental CRH expression under BDE-47 exposure in the JEG-3 cell model system. These placental cells are derived from human choriocarcinoma. Our result showed that this pollutant induced the CRH mRNA expression at 0.5 nM or above in the cells. A similar trend was observed when CRH peptide was determined by Western analysis in the cell lysates. As previous studies have shown the importance of signal transduction pathways in the gene regulation, the status of some protein kinases in the present study was investigated. The phosphorylated PKCα, JNK, and P38 were increased by the toxicant treatment, and administering the specific inhibitors could counteract the induced CRH expression. It appeared that the signaling transduction pathway of PKC was a significant contributor in the transcriptional regulation. Further study by using Electrophoretic Mobility Shift Assay suggested that AP-2 was the ultimate DNA-binding element for the initiation of gene transcription. Because an untimely increased CRH may compromise fetal development and induce preterm birth, the present study suggested that endocrine changes in pregnancy should be taken into consideration in the next assessment.

Dietary flavones counteract phorbol 12-myristate 13-acetate-induced SREBP-2 processing in hepatic cells.

Consumption of fruits and vegetables is generally regarded as beneficial to plasma lipid profile. The mechanism by which the plant foods induce desirable lipid changes remains unclear. SREBP-2 is crucial in cholesterol metabolism, and it is a major regulator of the cholesterol biosynthesis enzyme HMGCR. Our lab has previously illustrated that apigenin and luteolin could attenuate the nuclear translocation of SREBP-2 through an AMPK-dependent pathway. In the present study, these two flavones were studied for their ability to deter the same in an AMPK-independent signaling route. The processing of SREBP-2 protein was promoted by phorbol 12-myristate 13-acetate (PMA) in the hepatic cells WRL and HepG2, and the increased processing was reversed by apigenin or luteolin co-administration. EMSA results demonstrated that the PMA-induced DNA-binding activity was weakened by the flavones. The increased amount of nuclear SREBP-2 in cells was attenuated by the flavonoid as shown by immunocytochemical imaging. Quantitative reverse transcriptase-polymerase chain reaction assay demonstrated that the transcription of HMGCR under both flavone treatments was reduced. However, apigenin appeared to be stronger than luteolin in restraining PMA-induced HMGCR mRNA expression. Since PMA is a diacylglycerol analog, these findings might have some physiological implications.

Aflatoxin B1 disrupts transient receptor potential channel activity and increases COX-2 expression in JEG-3 placental cells.

Aflatoxins are fungal metabolites which pose a major threat to food safety. Although these mycotoxins are established hepatocarcinogens, their effect on the reproductive organ is unknown. Transient Receptor Potential Channels (TRPs) are ubiquitously expressed in human tissues, including the placenta. These channels are associated with various functions in the placenta. The fetus and the placenta are especially sensitive to xenobiotic assault; therefore, exposure to the aflatoxins during gestation might lead to the undesirable outcome. Previously we have shown that aflatoxin B1 administered in late gestation may increase cox-2 expression in mouse placentae. In the present study, we examined the effect of aflatoxin B1 on COX-2 by using the placental cell model JEG-3 and the respective signaling pathway. In our result, COX-2 expression was induced by the mycotoxin administration. The intracellular calcium levels were also increased in cells by aflatoxin B1 treatment as little as 1 nM. Immunoblot result showed that some TRP expressions were elevated. As inflated intracellular calcium might activate MAPKs, the underlying signaling pathway was investigated. With the help of TRP-specific inhibitors, the mycotoxin appeared to increase the expression of TRPC-3 and activate PKCß and ERK. The significance of COX-2 in pregnancy has been well established. Exposure to this mycotoxin may perturb the physiological processes dictated by COX-2 in pregnancy.

Phorbol 12-myristate 13-acetate promotes nuclear translocation of hepatic steroid response element binding protein-2.

Sterol regulatory element-binding protein (SREBP)-2 is a pivotal transcriptional factor in cholesterol metabolism. Factors interfering with the proper functioning of SREBP-2 potentially alter plasma lipid profiles. Phorbol 12-myristate 13-acetate (PMA), which is a common protein kinase C (PKC) activator, was shown to promote the post-translational processing and nuclear translocation of SREBP-2 in hepatic cells in the current study. Following SREBP-2 translocation, the transcripts of its target genes HMGCR and LDLR were upregulated as demonstrated by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) assay. Electrophoretic mobility shift assays (EMSA) also demonstrated an induced DNA-binding activity on the sterol response element (SRE) domain under PMA treatment. The increase of activated Srebp-2 without the concurrent induced mRNA expression was also observed in an animal model. As the expression of SREBP-2 was not increased by PMA, the activation of PKC was the focus of investigation. Specific PKC isozyme inhibition and overexpression supported that PKCß was responsible for the promoting effect. Further studies showed that the mitogen-activated protein kinases (MAPKs) extracellular signal-regulated kinases (ERK) and c-Jun N-terminal kinases (JNK), but not 5' adenosine monophosphate-activated protein kinase (AMPK), were the possible downstream signaling proteins of PKCß. In conclusion, this study illustrated that PKCß increased SREBP-2 nuclear translocation in a pathway mediated by MEK/ERK and JNK, rather than the one dictated by AMPK. These results revealed a novel signaling target of PKCß in the liver cells.