Fangchinoline inhibits rat aortic vascular smooth muscle cell proliferation and cell cycle progression through inhibition of ERK1/2 activation and c-fos expression

Coptisine inhibits neointimal hyperplasia through attenuating Pak1/Pak2 signaling in vascular smooth muscle cells without retardation of re-endothelialization

BACKGROUND AND AIMS

Vascular injury-induced endothelium-denudation and profound vascular smooth muscle cells (VSMCs) proliferation and dis-regulated apoptosis lead to post-angioplasty restenosis. Coptisine (CTS), an isoquinoline alkaloid, has multiple beneficial effects on the cardiovascular system. Recent studies identified it selectively inhibits VSMCs proliferation. However, its effects on neointimal hyperplasia, re-endothelialization, and the underlying mechanisms are still unclear.

METHODS

Cell viability was assayed by 3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide (MTT) and cell counting kit-8 (CCK-8). Cell proliferation and apoptosis were measured by flow cytometry and immunofluorescence of Ki67 and TUNEL. Quantitative phosphoproteomics (QPP) was employed to screen CTS-responsive phosphor-sites in the key regulators of cell proliferation and apoptosis. Neointimal hyperplasia was induced by balloon injury of rat left carotid artery (LCA). Adenoviral gene transfer was conducted in both cultured cells and LCA. Re-endothelialization was evaluated by Evan's blue staining of LCA.

RESULTS

1) CTS had strong anti-proliferative and pro-apoptotic effects in cultured rat VSMCs, with the EC50 4∼10-folds lower than that in endothelial cells (ECs). 2) Rats administered with CTS, either locally to LCA's periadventitial space or orally, demonstrated a potently inhibited balloon injury-induced neointimal hyperplasia, but had no delaying effect on re-endothelialization. 3) The QPP results revealed that the phosphorylation levels of Pak1S144/S203, Pak2S20/S197, Erk1T202/Y204, Erk2T185/Y187, and BadS136 were significantly decreased in VSMCs by CTS. 4) Adenoviral expression of phosphomimetic mutants Pak1D144/D203/Pak2D20/D197 enhanced Pak1/2 activities, stimulated the downstream pErk1T202/Y204/pErk2T185/Y187/pErk3S189/pBadS136, attenuated CTS-mediated inhibition of VSMCs proliferation and promotion of apoptosis in vitro, and potentiated neointimal hyperplasia in vivo. 5) Adenoviral expression of phosphoresistant mutants Pak1A144/A203/Pak2A20/A197 inactivated Pak1/2 and totally simulated the inhibitory effects of CTS on platelet-derived growth factor (PDGF)-stimulated VSMCs proliferation and PDGF-inhibited apoptosis in vitro and neointimal hyperplasia in vivo. 6) LCA injury significantly enhanced the endogenous phosphorylation levels of all but pBadS136. CTS markedly attenuated all the enhanced levels.

CONCLUSIONS

These results indicate that CTS is a promising medicine for prevention of post-angioplasty restenosis without adverse impact on re-endothelialization. CTS-directed suppression of pPak1S144/S203/pPak2S20/S197 and the subsequent effects on downstream pErk1T202/Y204/pErk2T185/Y187/pErk3S189 and pBadS136 underline its mechanisms of inhibition of VSMCs proliferation and stimulation of apoptosis. Therefore, the phosphor-sites of Pak1S144/S203/Pak2S20/S197 constitute a potential drug-screening target for fighting neointimal hyperplasia restenosis.

Study on spectrum-effect correlation for screening the effective components in Fangji Huangqi Tang basing on ultra-high performance liquid chromatography-mass spectrometry

BACKGROUD

Fangji Huangqi Tang (FHT) is a traditional Chinese medicine formula. Our previous work found that FHT could improve glomerular filtration function. The research on the effective materials basis of FHT was rarely reported.

PURPOSE

The effect indicators of glomerular filtration function were determined. The components in serum of FHT was detected and identified. The relationships between chemical spectra of serum and effect indicators were elucidated.

STUDY DESIGN

The paper was to study the underlying correlations between the chemical spectra and the protective effect of FHT on glomerulus to reveal the potential effective compounds in FHT.

METHODS

For the serum pharmacochemistry study, the biological samples were collected according to a time schedule designed carefully in advance. The fingerprint chromatograms of rat serum after oral administration of FHT were established by UHPLC-ESI-Q-TOF-MS technique. Meanwhile, in the pharmacodynamics research, the protective effects of FHT on glomerulonephritis were evaluated by detecting the contents of cystatin C (Cys C), blood urea nitrogen (BUN) and serum creatinine (Scr). Then, the spectrum-effect relationships between UHPLC fingerprints and anti-adriamycin nephrosis activities were evaluated using canonical correlation analysis (CCA) statistical method.

RESULTS

As a result, 105 peaks were identified from rat serum samples, which turned out to be 26 original compounds of FHT as well as 79 metabolites. According to the CCA results, eleven components were finally found to be the main anti-adriamycin nephrosis components.

CONCLUSIONS

The model successfully discovered the spectrum-effect relationships of FHT, which showed a representative way to discover the primary active ingredients from the complex herbal medicine system.

Fangchinoline inhibits the proliferation of SPC-A-1 lung cancer cells by blocking cell cycle progression

Fangchinoline (Fan) is a bioactive compound isolated from the Chinese herb Stephania tetrandra S. Moore (Fen Fang Ji). The aim of the present study was to investigate the effect of Fan on the proliferation of SPC-A-1 lung cancer cells, and to define the associated molecular mechanisms. Following treatment with Fan, Cell Counting Kit-8, phase contrast imaging and Giemsa staining assays were used to detect cell viability; flow cytometry was performed to analyze the cell cycle distribution; and reverse transcription-quantitative polymerase chain reaction and western blot assays were used to investigate changes in the expression levels of cell cycle-associated genes and proteins. In the present study, treatment with Fan markedly inhibited the proliferation of SPC-A-1 lung cancer cells and significantly increased the percentage of cells in the G₀/G₁ phase of the cell cycle in a dose-dependent manner (P<0.05 for 2.5-5 µm; P<0.01 for 10 µm), whereas the percentage of cells in the S and G₂/M phases were significantly reduced following treatment (P<0.05 for 5 µm; P<0.01 for 10 µm). Mechanistically, Fan significantly reduced the mRNA expression levels of cyclin D1, cyclin-dependent kinase 4 (CDK4) and CDK6 (P<0.05 for 2.5-5 µm; P<0.01 for 10 µm), which are key genes in the regulation of the G₀/G₁ phase of the cell cycle. Furthermore, treatment with Fan also decreased the expression of phosphorylated retinoblastoma (Rb) and E2F transcription factor-1 (E2F-1) proteins (P<0.05 for 5 µm; P<0.01 for 10 µm). In summary, the present study demonstrated that Fan inhibited the proliferation of SPC-A-1 lung cancer cells and induced cell cycle arrest at the G₀/G₁ phase. These effects may be mediated by the downregulation of cellular CDK4, CDK6 and cyclin D1 levels, thus leading to hypophosphorylation of Rb and subsequent suppression of E2F-1 activity. Therefore, the present results suggest that Fan may be a potential drug candidate for the prevention of lung cancer.

Pitavastatin Regulates Ang II Induced Proliferation and Migration via IGFBP-5 in VSMC

Angiotensin II (Ang II), a key mediator of hypertensive, causes structural changes in the arteries (vascular remodeling), which involve alterations in cell growth, vascular smooth muscle cell (VSMC) hypertrophy. Ang II promotes fibrotic factor like IGFBP5, which mediates the profibrotic effects of Ang II in the heart and kidneys, lung and so on. The purpose of this study was to identify the signaling pathway of IGFBP5 on cell proliferation and migration of Ang II-stimulated VSMC. We have been interested in Ang II-induced IGFBP5 and were curious to determine whether a Pitavastatin would ameliorate the effects. Herein, we investigated the question of whether Ang II induced the levels of IGFBP5 protein followed by proliferation and migration in VSMC. Pretreatment with the specific Angiotensin receptor type 1 (AT1) inhibitor (Losartan), Angiotensin receptor type 2 (AT2) inhibitor (PD123319), MAPK inhibitor (U0126), ERK1/2 inhibitor (PD98059), P38 inhibitor (SB600125) and PI3K inhibitor (LY294002) resulted in significantly inhibited IGFBP5 production, proliferation, and migration in Ang II-stimulated VSMC. In addition, IGFBP5 knockdown resulted in modulation of Ang II induced proliferation and migration via IGFBP5 induction. In addition, Pitavastatin modulated Ang II induced proliferation and migration in VSMC. Taken together, our results indicated that Ang II induces IGFBP5 through AT1, ERK1/2, P38, and PI3K signaling pathways, which were inhibited by Pitavastatin. These findings may suggest that Pitavastatin has an effect on vascular disease including hypertension.

Fangchinoline suppresses the growth and invasion of human glioblastoma cells by inhibiting the kinase activity of Akt and Akt-mediated signaling cascades

Glioblastoma multiforme (GBM) is one of the most palindromic and malignant central nervous system neoplasms, and the current treatment is not effectual for GBM. Research of specific medicine for GBM is significant. Fangchinoline possesses a wide range of pharmacological activities and attracts more attentions due to its anti-tumor effects. In this study, two WHO grade IV human GBM cell lines (U87 MG and U118 MG) were exposed to fangchinoline, and we found that fangchinoline specifically inhibits the kinase activity of Akt and markedly suppresses the phosphorylation of Thr308 and Ser473 of Akt in human GBM cells. We also observed that fangchinoline inhibits tumor cell proliferation and invasiveness and induces apoptosis through suppressing the Akt-mediated signaling cascades, including Akt/p21, Akt/Bad, and Akt/matrix metalloproteinases (MMPs). These data demonstrated that fangchinoline exerts its anti-tumor effects in human glioblastoma cells, at least partly by inhibiting the kinase activity of Akt and suppressing Akt-mediated signaling cascades.

Fangchinoline targets PI3K and suppresses PI3K/AKT signaling pathway in SGC7901 cells

Fangchinoline, an important compound in Stephania tetrandra S. Moore, as a novel antitumor agent, has been implicated in several types of cancers cells except gastric cancer. To investigate whether fangchinoline affects gastric cancer cells, we detected the signaling pathway by which fangchinoline plays a role in different human gastric cancer cells lines. We found that fangchinoline effectively suppressed proliferation and invasion of SGC7901 cell lines, but not MKN45 cell lines by inhibiting the expression of PI3K and its downstream pathway. All of the Akt/MMP2/MMP9 pathway, Akt/Bad pathway, and Akt/Gsk3β/CDK2 pathway could be inhibited by fangchinoline through inhibition of PI3K. Taken together, these results suggest that fangchinoline targets PI3K in tumor cells that express PI3K abundantly and inhibits the growth and invasive ability of the tumor cells.

Fangchinoline as a kinase inhibitor targets FAK and suppresses FAK-mediated signaling pathway in A549

BACKGROUND

Fangchinoline as a novel anti-tumor agent has been paid attention in several types of cancers cells except lung cancer. Here we have investigated the effect of fangchinoline on A549 cells and its underlying mechanism.

PURPOSE

The purpose of this work was to study the effect of fangchinoline on A549 cells.

METHODS

Four lung cancer cell lines (A549, NCI-H292, NCI-H446, and NCI-H460) were exposed to varying concentrations (10-40 μmol/l) of fangchinoline to observe the effect of fangchinoline on the four lung cancer cell lines and to observe the changes of the lung cancer cell on proliferation, apoptosis, and invasion.

RESULTS

Fangchinoline effectively suppressed proliferation and invasion of A549 cell line but not NCI-H292, NCI-H446, and NCI-H460 cell lines by inhibiting the phosphorylation of FAK (Tyr397) and its downstream pathways, due to the significant differences of Fak expression between A549 and the other three cell lines. And all FAK-paxillin/MMP2/MMP9 pathway, FAK-Akt pathway, and FAK-MEK-ERK1/2 pathway could be inhibited by fangchinoline.

DISCUSSION

Fangchinoline effectively suppressed proliferation and invasion of A549 cell line by inhibiting the phosphorylation of FAK (Tyr397) and its downstream pathways.

CONCLUSION

Fangchinoline could inhibit the phosphorylation of FAK(p-Tyr397), at least partially. Fangchinoline as a kinase inhibitor targets FAK and suppresses FAK-mediated signaling pathway and inhibits the growth and the invasion in tumor cells which highly expressed FAK such as A549 cell line.

Fangchinoline inhibits cell proliferation via Akt/GSK-3beta/ cyclin D1 signaling and induces apoptosis in MDA-MB-231 breast cancer cells

Fangchinoline (Fan) inhibits cell proliferation and induces apoptosis in several cancer cell lines. The effects of Fan on cell growth and proliferation in breast cancer cells remain to be elucidated. Here, we show that Fan inhibited cell proliferation in the MDA-MB-231 breast cancer cell line through suppression of the AKT/Gsk- 3beta/cyclin D1 signaling pathway. Furthermore, Fan induced apoptosis by increasing the expression of Bax (relative to Bcl-2), active caspase 3 and cytochrome-c. Fan significantly inhibited cell proliferation of MDA- MB-231 cells in a concentration and time dependent manner as determined by MTT assay. Flow cytometry analysis demonstrated that Fan treatment of MDA-MB-231 cells resulted in cell cycle arrest at the G1 phase, which correlated with apparent downregulation of both mRNA and protein levels of both PCNA and cyclin D1. Further analysis demonstrated that Fan decreased the phosphorylation of AKT and GSK-3beta. In addition, Fan up-regulated active caspase3, cytochrome-c protein levels and the ratio of Bax/Bcl-2, accompanied by apoptosis. Taken together, these results suggest that Fan is a potential natural product for the treatment of breast cancer.

Effect of fangchinoline on root resorption during rat orthodontic tooth movement

Objective

To evaluate the short-term effect of fangchinoline, an antiinflammatory drug widely used in Asia, on root resorption that is associated with orthodontic tooth movement.

Methods

Twenty-four Wistar rats were randomly divided into 6 groups. Mesial forces of 0, 50, or 100 g were applied to the maxillary first molar of the rats in each group for 14 days by activating nickel-titanium closed-coil springs. One-half of the rats receiving each of these treatments also received injections of 200 µL fangchinoline every 2 days. Finally, movement of the maxillary first molars was measured using digitized radiographs. The molars were extracted and the surfaces of the root resorption craters were recorded using a scanning electron microscope. The distance the molars moved and resorptionarea ratio was measured, and results were analyzed using 2-way ANOVA tests.

Results

There were no statistical differences in the distances the first molars moved under 50 or 100 g force, regardless of treatment with fangchinoline. However, the resorption area ratios were significantly smaller in those rats that were treated with both tension and fangchinoline than in those rats treated by tension alone.

Conclusions

Fangchinoline reduced the resorption area ratio in rats and is therefore an important means of alleviating root resorption.

Fangchinoline induces autophagic cell death via p53/sestrin2/AMPK signalling in human hepatocellular carcinoma cells

BACKGROUND AND PURPOSE

Fangchinoline is a novel anti-tumour agent with little known of its cellular and molecular mechanisms of action. Here we have investigated the mode of cell death induced by fangchinoline and its underlying mechanism in two human hepatocellular carcinoma cell lines, HepG2 and PLC/PRF/5.

EXPERIMENTAL APPROACH

Apoptosis and autophagy were monitored in fangchinoline-treated HepG2 and PLC/PRF/5 cells by histological methods. The signal transduction pathways involved in activation of autophagy were examined, using immunoblotting, real-time PCR and siRNA techniques.

KEY RESULTS

Fangchinoline did not induce apoptosis in HepG2 and PLC/PRF/5 cells but triggered, dose-dependently, autophagy, an alternative mode of cell death which may contribute to fangchinoline's anti-tumour action. Nuclear translocation of p53 was involved in induction of autophagy by fangchinoline, followed by selective transactivation of the autophagy-related gene sestrin2 and initiation of the autophagic process. Signalling by the AMP-activated protein kinase was also involved as a downstream target of sestrin2 and induced mTOR-independent autophagic cell death in both cell lines. siRNA for Atg 5 or pharmacological block of p53 abolished fangchinoline-induced autophagy and inhibition of autophagy switched cell death to apoptosis in these cells, suggesting that cell death is irreversible once autophagy is induced by fangchinoline.

CONCLUSIONS AND IMPLICATIONS

Fangchinoline is a highly specific agent inducing autophagic cell death in hepatocellular carcinoma cells with a novel mechanism, which elucidates the potential of fangchinoline to potentiate programmed cell death in cancer cells.

Crocetin suppresses angiotensin II-induced vascular smooth-muscle cell proliferation through inhibition of ERK1/2 activation and cell-cycle progression

Excessive proliferation of vascular smooth cells (VSMCs) plays a critical role in the development of atherosclerosis, and inhibition of VSMCs proliferation has been proved to be beneficial to this disease. In the present study, we investigated the antiproliferative effect of crocetin, a carotinoid (Fig. 1, >98%, HPLC) with potent antioxidant capacity, on bovine aortic VSMCs (BASMCs), and the possible mechanisms involved. The results indicate that crocetin potently inhibited AngII-induced BASMC proliferation, as evaluated by MTT assay and [3H]-thymidine incorporation assay. Flow cytometry analysis showed that crocetin markedly blocked AngII-induced cell-cycle progression by arresting the cells in the G0/G1 phase. Consistently, crocetin markedly suppressed AngII-induced activation of extracellular signal-regulated kinase1/2 (ERK1/2) and its downstream effector c-fos expression, which is a prerequisite for cell-cycle progression. In addition, crocetin significantly decreased AngII-induced intracellular reactive oxygen species and increased the activity of superoxide dismutase. Taken together, these results indicate that crocetin was capable of inhibiting BASMC proliferation by blocking cell-cycle progression, which might be associated with the suppression of ERK1/2 activation and c-fos expression. These results might be related, at least partly, to the antioxidant property of crocetin.

Selective inhibition of vascular smooth muscle cell proliferation by coptisine isolated from Coptis rhizoma, one of the crude drugs composing Kampo medicines Unsei-in

Acceleration of vascular smooth muscle cell (VSMC) proliferation is closely linked to the pathogenesis of vascular diseases. We, therefore, focused on traditional Japanese herbal medicines (Kampo medicines) used to ameliorate the impairment of microcirculation or blood stasis and screened them for their ability to inhibit rat VSMC proliferation. Among them, Unsei-in was found to effectively suppress VSMC proliferation, and Coptis rhizome was the responsible constituent crude drug. The extract of Coptis rhizome inhibited VSMC proliferation with the GI(50) value of 4.4 microg/ml, which was much lower than those against the proliferation of 3Y1, dRLh-84, B16, and HeLa cells. The Coptis rhizome extract inhibited the progression of VSMC arrested at G(0)/G(1) phase from G(0)/G(1) to S phase, but not that of 3Y1 cells. Biological assay-guided fractionation revealed that an alkaloid of Coptis rhizome, coptisine, was the active ingredient in selectively preventing VSMC proliferation with GI(50) of 3.3 microM (1.2 microg/ml). When the structurally-related isoquinoline alkaloids of protoberberine class were studied for their inhibitory activities, berberine decreased the VSMC proliferation with GI(50) of 95.1 microM (35.4 microg/ml), about 30 times higher concentration than coptisine, while palmatine failed to show any activity. This study provides evidence that coptisine, an ingredient of Unsei-in, prevents VSMC proliferation selectively at lower concentrations compared with various cells or other structurally related alkaloids.

Berberine suppresses MEK/ERK-dependent Egr-1 signaling pathway and inhibits vascular smooth muscle cell regrowth after in vitro mechanical injury

Vascular smooth muscle cell (SMC) proliferation plays an important role in the pathogenesis of atherosclerosis and post-angioplasty restenosis. Berberine is a well-known component of the Chinese herb medicine Huanglian (Coptis chinensis), and is capable of inhibiting SMC contraction and proliferation, yet the exact mechanism is unknown. We therefore investigated the effect of berberine on SMC growth after mechanic injury in vitro. DNA synthesis and cell proliferation assay were performed to show that berberine inhibited serum-stimulated rat aortic SMC growth in a concentration-dependent manner. Mechanical injury with sterile pipette tip stimulated the regrowth of SMCs. Treatment with berberine prevented the regrowth and migration of SMCs into the denuded trauma zone. Western blot analysis showed that activation of the MEK1/2 (mitogen-activated protein kinase kinase 1/2), extracellular signal-regulated kinase (ERK), and up-regulation of early growth response gene (Egr-1), c-Fos and Cyclin D1 were observed sequentially after mechanic injury in vitro. Semi-quantitative reverse-transcription PCR assay further confirmed the increase of Egr-1, c-Fos, platelet-derived growth factor (PDGF) and Cyclin D1 expression in a transcriptional level. However, berberine significantly attenuated MEK/ERK activation and downstream target (Egr-1, c-Fos, Cyclin D1 and PDGF-A) expression after mechanic injury in vitro. Our study showed that berberine blocked injury-induced SMC regrowth by inactivation of ERK/Egr-1 signaling pathway thereby preventing early signaling induced by injury in vitro. The anti-proliferative properties of berberine may be useful in treating disorders due to inappropriate SMC growth.

Double blockade of cell cycle progression by coptisine in vascular smooth muscle cells

Coptisine, an isoquinoline alkaloid isolated from rhizome of Coptis japonica, inhibits proliferation of vascular smooth muscle cells (VSMCs). The aim of this study was to evaluate the action of coptisine, along with berberine (a structurally similar isoquinoline alkaloid), on progression of the cell cycle in VSMCs. Coptisine displayed antiproliferative action against VSMCs by blocking the cell cycle at G(1) and G(2)/M phases. The G(1) block was shown by inhibition of [(3)H]thymidine incorporation into VSMCs at coptisine concentrations higher than 15 microM. The mechanism underlying the G(1) arrest involved a decrease in cyclin D1 protein, although cyclin E, A, and B were not affected by coptisine treatment. The selective reduction in cyclin D1 protein was mainly attributable to accelerated proteolysis via proteasome-dependent pathway, since it was inhibited by a proteasome inhibitor, N-carbobenzoxy-L-leucinyl-L-leucinyl-L-norleucinal (MG132) and further the mRNA level of cyclin D1, protein synthesis, and mitogen-activated protein kinase (MAPK) activity remained unaltered. The mechanism underlying the G(2)/M arrest involved partial inhibition of tubulin polymerization, which was apparent at coptisine concentration of 3 microM. Berberine arrested the cell cycle at G(1) phase via a mechanism identical with coptisine, but did not cause block at G(2)/M phase. The results demonstrate that a small difference in the structure between isoquinoline alkaloids produces a big difference in activity, and that coptisine has a unique double action in arresting the cell cycle of VSMCs.

The use of temperature-composition combinatorial libraries to study the effects of biodegradable polymer blend surfaces on vascular cells

Controlling cellular and physiological responses such as adhesion, proliferation and migration is a highly desirable feature of engineered scaffolds. One important application would be the design of tissue engineered vascular grafts that regulate cell adhesion and growth. We utilized temperature-composition combinatorial polymer libraries to investigate the effects of surfaces of blended poly(D,L-lactic-co-glycolic acid) (PLGA) and poly(epsilon-caprolactone) (PCL) on murine vascular smooth muscle cells (SMC). In this manner, SMCs were exposed to approximately 1000 distinguishable surfaces in a single experiment, allowing the discovery of optimal polymer compositions and processing conditions. SMC adhesion, aggregation, proliferation, and protein production were highest in regions with mid- to high-PCL concentrations and high annealing temperatures. These regions exhibited increased surface roughness, increased microscale PLGA-rich matrix stiffness, and significant change of bulk PCL-rich crystallinity relative to other library regions. This study revealed a previously unknown processing temperature and blending composition for two well-known polymers that optimized SMC interactions.

Inhibition of Mitogen-Mediated Proliferation of Rat Vascular Smooth Muscle Cells by Labedipinedilol-A through PKC and ERK 1/2 Pathway

Labedipinedilol-A is a novel 1, 4-dihydropyridine type calcium antagonist with alpha-receptor blocking activity. This study investigates the effects of labedipinedilol-A on mitogen-induced proliferation of rat vascular smooth muscle cells (VSMCs). Labedipinedilol-A's inhibition on cell proliferation was measured by the tetrazolium salt (XTT) test. Labedipinedilol-A dose-dependently inhibited mitogen-induced DNA synthesis, determined by the incorporation of 5-bromo-2'-deoxyuridine (BrdU). Labedipinedilol-A was also found capable of inhibiting the migration of VSMCs induced by PDGF-BB with an IC50 value of 5.6 microM. In accordance with these findings, labedipinedilol-A revealed blocking of the FBS-inducible progression through G0/G1 to S phase of the cell cycle in synchronized cells. Labedipinedilol-A appeared to cause inhibition of mitogens-induced PKC translocation, suggesting the probable involvement of protein kinase C (PKC) in this cellular response. Labedipinedilol-A reduced both intracellular Ca and the phosphorylation of extracellular signal-regulated protein kinase 1/2 in PDGF-BB-stimulated VSMCs. It also suppressed the levels of proliferative cell nuclear antigen (PCNA) in VSMCs both time- and dose-dependently. These results indicate that labedipinedilol-A may inhibit cell proliferation by attenuating activation of the ERK 1/2 pathway, which is regulated by PKC and Ca, suggesting that it may have great potential in the prevention of progressive atherosclerosis.