• The Korean Journal of Physiology and Pharmacology
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• v.14 no.5
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• pp.299-304
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• 2010

Losartan is a selective angiotensin II (Ang II) type 1 ($AT_1$) receptor antagonist which inhibits vascular smooth muscle cells (VSMCs) contraction and proliferation. We hypothesized that losartan may prevent cell proliferation by activating AMP-activated protein kinase (AMPK) in VSMCs. VSMCs were treated with various concentrations of losartan. AMPK activation was measured by Western blot analysis and cell proliferation was measured by MTT assay and flowcytometry. Losartan dose- and time-dependently increased the phosphorylation of AMPK and its downstream target, acetyl-CoA carboxylase (ACC) in VSMCs. Losartan also significantly decreased the Ang II- or 15% FBS-induced VSMC proliferation by inhibiting the expression of cell cycle associated proteins, such as p-Rb, cyclin D, and cyclin E. Compound C, a specific inhibitor of AMPK, or AMPK siRNA blocked the losartan-induced inhibition of cell proliferation and the $G_0/G_1$ cell cycle arrest. These data suggest that losartan-induced AMPK activation might attenuate Ang II-induced VSMC proliferation through the inhibition of cell cycle progression.

• Animal Bioscience
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• v.36 no.11
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• pp.1757-1768
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• 2023

Objective: The number of bovine mammary epithelial cells (BMECs) is closely associated with the quantity of milk production in dairy cows; however, the optimal levels and the combined effects of hormones and essential amino acids (EAAs) on cell proliferation are not completely understood. Thus, the purpose of this study was to determine the optimal combination of individual hormones and EAAs for cell proliferation and related signaling pathways in BMECs. Methods: Immortalized BMECs (MAC-T) were treated with six hormones (insulin, cortisol, progesterone, estrone, 17β-estradiol, and epidermal growth factor) and ten EAAs (arginine, histidine, leucine, isoleucine, threonine, tryptophan, lysine, methionine, phenylalanine, and valine) for 24 h. Results: Cells were cultured in a medium containing 10% fetal bovine serum (FBS) as FBS supplemented at a concentration of 10% to 50% showed a comparable increase in cell proliferation rate. The optimized combination of four hormones (insulin, cortisol, progesterone, and 17β-estradiol) and 20% of a mixture of ten EAAs led to the highest cell proliferation rate, which led to a significant increase in cell cycle progression at the S and G2/M phases, in the protein levels of proliferating cell nuclear antigen and cyclin B1, cell nucleus staining, and in cell numbers. Conclusion: The optimal combination of hormones and EAAs increased BMEC proliferation by enhancing cell cycle progression in the S and G/2M phases. Our findings indicate that optimizing hormone and amino acid levels has the potential to enhance milk production, both in cell culture settings by promoting increased cell numbers, and in dairy cows by regulating feed intake.

• Nutritional Sciences
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• v.5 no.4
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• pp.175-183
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• 2002

To compare the effects of various types of dietary fiber on microbial production of short-chain fatty acids (SCFA) and on colon cell proliferation which is used as an intermediate biomarker for colon carcinogenesis, groups of 10 male Sprague-Dawley rats were fed one of four fiber-supplemented diets (6% cellulose, 6% pectin, 6% polydextrose, and a mixture of 3% cellulose and 3% polydextrose) for three weeks. As a control, a fiber-free diet was fed to a separate group of 10 rats. Cell proliferation was measured by in vivo incorporation of bromodeoxyuridine into DNA in the proximal and distal colon, respectively. Luminal concentrations of SCFA were measured by gas chromatography. Dietary fiber significantly influenced microbial production of SCFA in the colon; pectin supplementation produced the highest concentrations of luminal SCFA in both the proximal and distal colon (p<0.05). The degree of individual SCFA production was characterized by a relatively higher increase in butyrate production by the pectin-supplemented diet, and in propionate production by the polydextrose-supplemented diet, resulting in alterations of the molar ratios of acetate, propionate and butyrate. There were significant differences in colon cell proliferation among the diet groups; the pectin-supplemented diet produced a significantly higher effect on cell proliferation of distal colonic epithelial cells (p＜0.05), and the polydextrose-supplemented diet produced an intermediate effect compared to the fiber-free or cellulose-supplemented diet. Increased cell proliferation was correlated to increased luminal concentrations of butyrate in the proximal colon and to increased luminal concentrations of propionate and butyrate in the distal colon (p<0.05). Therefore, these data suggest that dietary fiber may modulate colon cell proliferation by altering luminal SCFA concentrations, particularly butyrate and perhaps propionate. In addition, the present study is the first finding that has demonstrated a relative increase in colon cell proliferation due to supplementation with polydextrose, suggesting that the overuse of this artificially synthesized polysaccharide in food processing technology needs to be carefully evaluated from the public health point of view.

• The Korean Journal of Physiology and Pharmacology
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• v.13 no.4
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• pp.309-313
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• 2009

Spontaneous hypertensive rats (SHR) are an established model of genetic hypertension. Vascular smooth muscle cells (VSMC) from SHR proliferate faster than those of control rats (Wistar-Kyoto rats; WKY). We tested the hypothesis that induction of heme oxygenase (HO)-1 induced by aprotinin inhibits VSMC proliferation through cell cycle arrest in hypertensive rats. Aprotinin treatment inhibited VSMC proliferation in SHR more than in normotensive rats. These inhibitory effects were associated with cell cycle arrest in the G1 phase. Tin protoporphyrin IX (SnPPIX) reversed the anti-proliferative effect of aprotinin in VSMC from SHR. The level of cyclin D was higher in VSMC of SHR than those of WKY. Aprotinin treatment downregulated the cell cycle regulator, cyclin D, but upregulated the cyclin-dependent kinase inhibitor, p21, in VSMC of SHR. Aprotinin induced HO-1 in VSMC of SHR, but not in those of control rats. Furthermore, aprotinin-induced HO-1 inhibited VSMC proliferation of SHR. Consistently, VSMC proliferation in SHR was significantly inhibited by transfection with the HO-1 gene. These results indicate that induction of HO-1 by aprotinin inhibits VSMC proliferation through cell cycle arrest in hypertensive rats.

• The Korean Journal of Physiology and Pharmacology
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• v.7 no.2
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• pp.103-109
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• 2003

The cellular mechanisms that contribute to the acceleration of atherosclerosis in diabetes are poorly understood. Therefore, the potential mechanisms involved in the diabetes-dependent increase in vascular smooth muscle cell (VSMC) proliferation was investigated. Using primary culture of VSMC from streptozotocin-induced diabetic rat aorta, cell proliferation assay showed two-fold increase in cell number accompanied with enhanced superoxide generation compared to normal VSMC, 2 days after plating. Both the increased superoxide production and cell proliferation in diabetic VSMC were significantly attenuated by not only tiron (1 mM), a superoxide scavenger, but also by diphenyleneiodonium (DPI; $10{\mu}M$), an NAD(P)H oxidase inhibitor. NAD(P)H oxidase activity in diabetic VSMC was significantly higher than that in control cell, accompanied with increased mRNA expression of p22phox, a membrane subunit of oxidase. Furthermore, inhibition of p22phox expression by transfection of antisense p22phox oligonucleotides into diabetic VSMC resulted in a decrease in superoxide production, which was accompanied by a significant inhibition of cell proliferation. Based on these results, it is suggested that diabetes-associated increase in NAD(P)H oxidase activity via enhanced expression of p22phox contributes to augmented VSMC proliferation in diabetic rats.

• Molecules and Cells
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• v.37 no.12
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• pp.881-887
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• 2014

Cell proliferation is tightly controlled by the cell-cycle regulatory proteins, primarily by cyclins and cyclin-dependent kinases (CDKs) in the $G_1$ phase. The ankyrin repeat-rich membrane spanning (ARMS) scaffold protein, also known as kinase D-interacting substrate of 220 kDa (Kidins 220), has been previously identified as a prominent downstream target of neurotrophin and ephrin receptors. Many studies have reported that ARMS/Kidins220 acts as a major signaling platform in organizing the signaling complex to regulate various cellular responses in the nervous and vascular systems. However, the role of ARMS/Kidins220 in cell proliferation and cell-cycle progression has never been investigated. Here we report that knockdown of ARMS/Kidins220 inhibits mouse neuroblastoma cell proliferation by inducing slowdown of cell cycle in the $G_1$ phase. This effect is mediated by the upregulation of a CDK inhibitor p21, which causes the decrease in cyclin D1 and CDK4 protein levels and subsequent reduction of pRb hyperphosphorylation. Our results suggest a new role of ARMS/Kidins220 as a signaling platform to regulate tumor cell proliferation in response to the extracellular stimuli.

• Preventive Nutrition and Food Science
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• v.4 no.3
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• pp.203-208
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• 1999

The effect of the polyunsaterated fatty acids, linoleic acid(LA), arachidonic acid(AA) and conjugated dienoic linoleic acid(CLA) on IEC-6 cells (rat intestinal cell)proliferation and cell transduction have been determined in vitro. IEC-6 cells proliferation was assessed by cell growth and [3H]-thymidine incroporation analysis. At 10 μM concentration , the proliferationof cells supplemented with AA or LA was significantly higher than that of CLA. [3H]-thymidine uptake showed the same results. LA and AA increased [3H]-thymidine uptake more than CLA. The stimulatory effect of LA or AA was even more pronounced in the presence of IGF. Both cell number analysis and [3H]-thymidine incorporation revealed that IEC-6 cell proliferation was influenced differently by exogenous free fatty acids, in which AA or LA stimulated IEC-6 cell proliferation and CLA inhibited it. Tyorosine phosphorylation provides a key switch to regulate celluar acitivity in response to extracellular stimuli. At 20 μM and 10μM, AA with IGF-1 stimulated protein tyrosine phophorylation in IEC-6 cells, but LA's impact was less than that of AA. CLA and CLA with IGF-1 inhibited protein tyrosine phosphorylation in IEC-6 cells. These results suggest there is a possible correlation between cell proliferation and IGF receptor tyrosine knase activity driven by AA.

• BMB Reports
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• v.41 no.11
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• pp.803-807
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• 2008

We investigated the expression of muscarinic acetylcholine receptors (mAChRs) and their possible involvement in the regulation of cell proliferation in four colon cancer cell lines (SNU-61, SNU-81, SNU-407, and SNU-1033) derived from Korean colon carcinoma patients. A ligand binding assay showed that all four cell lines expressed mAChRs. Treatment of the four cell lines with the cholinergic agonist carbachol led to the activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2). In SNU-407 cells, carbachol significantly stimulated cell proliferation, which could be abolished by the muscarinic antagonist atropine and the ERK1/2 kinase inhibitor PD98059. These results indicate that mAChRs specifically mediate the proliferation of SNU-407 colon cancer cells via the ERK1/2 pathway.

• Development and Reproduction
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• v.16 no.4
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• pp.329-338
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• 2012

The proliferation of embryonic cells or adult stem cells in tissue is critically regulated during development and repair. How limited the proliferation of cells, so far, is not much explored. Cell-cell contact proliferation inhibition is known as a crucial mechanism regulating cell proliferation in vitro and in vivo. In this study we examined the characters of mouse subcutaneous adipose derived stem cells (msADSC) whether they lost or get contact inhibition during in vitro culture. The characters of msADSC growth after confluence were analyzed using confocal microscope and the expression profiles of contact inhibition related genes were analyzed according to the morphological changes using real-time PCR method. msADSC showed overlapping growth between them but not after passage 14. The cell shapes were also changed after passage 14. The expression profiles of genes which are involved in contact inhibition were modified in the msADSC after passage 14. The differentiation ability of msADSCs to adipocyte, chondrocyte and osteocyte was not changed by such changes of gene expression profiles. Based on these results, it is revealed that smADSC were characterized by getting of strong cell-cell contact inhibition after passage 14 but the proliferation and developmental ability were not blocked by the change of cell-cell contact proliferation inhibition. These finding will help to understand the growth of adipose tissue, although further studies are needed to evaluate the physiological meaning of the cell-cell contact proliferation inhibition during in vitro culture of msADSC.

• IMMUNE NETWORK
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• v.3 no.4
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• pp.276-280
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• 2003

Background: Peroxidases (Prx) of the peroxiredoxin family reduce hydrogen peroxide and alkyl hydroperoxides to water and alcohol respectively. Hydrogen peroxide is implicated as an intracellular messenger in various cellular responses such as proliferation and differentiation. And Prx I activity is regulated by Cdc-2 mediated phosphorylation. This work was undertaken to investigate the proliferation role of peroxiredoxin III as a member of Prx family in Prx III overexpressed HeLa cell line. Methods: To provide further evidence of proliferation, we selected Prx III stably expressed HeLa Tet-off cell lines. Cell proliferation was examined by using proliferation reagent WST-1 in the presence or absence of doxycycline. Prx III, 2-cys Prx enzymes exist as homodimer. The activation of Prx III heterodimer with induced and endogenous Prx III was examined by immunoprecipitation. Results: Immunoprecipitation analysis of the induced and endogenous Prx III with anti-myc showed that the induced wild type (WT) and dominant negative (DN) Prx III from HeLa Prx III Tet-off stable cell heterodimerized with endogenous Prx III each other. And the expression level of induced Prx III was examined after addition of doxycycline. By 72 hr, the expression level of induced Prx III was diminished gradually and the half-life of the induced wild type Prx III was approximately 17 hr. The proliferation experiment demonstrated that the relative proliferation value of induced and endogenous WT Prx III stable cell has no changes but the DN Prx III induced HeLa Tet-off stable cells were lower than endogenous Prx III. Conclusion: In conclusion, the HeLa dominant negative Prx III Tet-off stable cells were decreased the proliferation.