Pro-apoptotic actions of exisulind and CP461 in SW480 colon tumor cells involve beta-catenin and cyclin D1 down-regulation

Exisulind and its analogues are inhibitors of cyclic GMP phosphodiesterases (PDEs) that have been shown to activate and induce protein kinase G, resulting in the induction of apoptosis in colon cancer cells. These drugs also reduce beta-catenin protein levels and decrease cyclin D1 mRNA levels in SW480 cells. Herein we report on studies pertaining to exisulind regulation of beta-catenin levels and activity in colon tumor cells. Exisulind and its higher-affinity PDE analogues, (Z)-5-fluoro-2-methyl-(4-pyridylidene)-3-(N-benzyl)-indenylacetamide hydrochloride (CP461) and (Z)-1H-indene-3-acetamide, 5-fluoro-2-methyl-N-(phenylmethyl)-1-[(3,4,5-trimethoxyphenyl)methylene] (CP248), reduced beta-catenin, including the nuclear beta-catenin in SW480 cells (EC(50) approximately 200 microM, 1 microM, and <1 microM, respectively). The 50% reduction of beta-catenin was seen in 8-14 hr. There was no change in beta-catenin mRNA. Exisulind-induced beta-catenin reduction was blocked by the proteasomal inhibitor MG132 (Z-leu-Leu-Leu-CHO), indicating that the effect of exisulind involved ubiquitin-proteasomal degradation. A consequence of reduced beta-catenin in SW480 cells was that exisulind, CP461, and CP248 caused a concentration- and time-dependent decrease in cyclin D1 levels (EC(50) approximately 300 microM, 1 microM, and <1 microM, respectively) in 4 hr. The effect was via decreased cyclin D1 mRNA levels. Exisulind-induced degradation of beta-catenin was not blocked by the inhibition of caspase-3 activity and/or apoptosis, and some SW480 cells showed a reduction in beta-catenin levels before the appearance of early apoptosis indicators. Expression of the N-terminal 170 amino acid fragment of beta-catenin reduced the effects of beta-catenin degradation, cyclin D1 reduction, and the apoptosis response to exisulind. These results indicate that exisulind-induced beta-catenin degradation precedes the induction of apoptosis and that the down-regulation of inappropriate beta-catenin-activated genes accounts in part for the pro-apoptotic effects of exisulind and CP461 in colon tumor cells.     

长链非编码RNA OPA相互作用蛋白5反向转录序列1靶向调控微RNA-128-3p对结直肠癌细胞增殖、侵袭和转移的影响

目的 探究长链非编码RNA OPA相互作用蛋白5反向转录序列1(lncRNA OIP5-AS1)在结直肠癌中的表达情况及靶向调控微RNA-128-3p(miR-128-3p)对结直肠癌细胞增殖、侵袭和转移的影响。方法 采用实时荧光定量PCR(qPCR)定量分析2017年1月至2018年12月在郑州大学人民医院住院并进行手术治疗的38例结直肠癌病人癌组织及相应癌旁组织、结直肠癌细胞系（SW480、SW620、HT-29和LoVo）及人正常结直肠黏膜细胞FHC中lncRNA OIP5-AS1和miR-128-3p的表达。将SW620细胞设为si-OIP5-AS1组、si-NC组、miR-128-3p mimic组、mimic-NC组、miR-128-3p inhibitor+si-OIP5-AS1组和inhibitor-NC+siOIP5-AS1组,采用细胞计数试剂盒（CCK-8）实验和克隆形成实验检测细胞增殖能力,采用划痕实验和transwell实验检测细胞侵袭与迁移能力,采用蛋白质印迹法检测E2F1、细胞周期蛋白D1(Cyclin D1)、波形蛋白（Vimentin）、N-钙黏蛋白（N...     

Antioxidant and cytotoxic isoprenylated coumarins from Mammea americana

Antioxidant-guided fractionation of Mammea americana L. seeds resulted in the identification of three new isoprenylated coumarins, mammea B/BA hydroxycyclo F (1), mammea E/BC (2), and mammea E/BD (3). In addition, twelve known isoprenylated coumarins, mammea A/AA (4), mammea A/AA cyclo D (5), mammea A/AA cyclo F (6), mammea A/AC cyclo D (7), mammea A/AD cyclo D (8), mammea B/BA (9), mammea B/BA cyclo F (10), mammea B/BB (11), mammea B/BC (12), mammea B/BD (13), mammea E/BA (14), and mammea E/BB (15), as well as two known flavanols, (+)-catechin (16) and (-)-epicatechin (17) were identified. The fifteen isoprenylated coumarins were screened for their cytotoxicity in the SW-480, HT-29, and HCT-116 human colon cancer cell lines and antioxidant capacities in the DPPH (1,1-diphenyl-2-picrylhydrazyl) free-radical assay. Compounds 1 - 15 exhibited significant cytotoxic activities in the SW-480, HT-29, and HCT-116 human colon cancer cell lines (IC50 ranges 13.9 - 88.1, 11.2 - 85.3, and 10.7 - 76.7 microM, in the three cell lines, respectively) at concentrations comparable to 5-fluorouracil (IC50 = 53.0, 46.1, and 45.1 microM), a drug frequently used for human colon cancer treatment. Compounds 2 - 4, 9, and 11 - 15 displayed high antioxidant activity in the DPPH assay (IC50 range 86 - 135 microM), compounds 1, 5 - 8, and 10, however, had no antioxidant activity (IC50 > 200 microg/mL) in the DPPH assay. The results of these assays were used to study the structure-activity relationships for this class of compounds. In the SW-480 cell line, the three new coumarins, 1 - 3, also exhibited dose-dependent increases in sub-diploid cells by flow cytometry, indicating that they induce apoptosis.     

Destruxin E, a cyclodepsipeptide antibiotic, reduces cyclin D1 levels and inhibits anchorage-independent growth of v-Ki-ras-expressed pMAM-ras-REF cells

Destruxin E (DE), a cyclodepsipeptide isolated from fermentation broths of Metarhizium sp. MA324, inhibited the growth of v-Ki-ras-expressed pMAM-ras-REF (rasREF) cells in the suspension (anchorage-independent) culture (a) more strongly than that in the substratum-attached (anchorage-dependent) culture (b) or that of v-Ki-ras-unexpressed pMAM-ras-REF (REF) cells in the substratum-attached culture (c); the IC(50) values of DE were 0.07 microM (a), 0.4 microM (b), and 1.2 microM (c). DE arrested G1 phase cell cycle progression of rasREF cells in the substratum-attached culture (b). In rasREF cells treated with DE for 72 h in suspension culture (a), the levels of cyclin D1, cyclin A, p27(Kip1), and hyperphosphorylated Rb were decreased, but the levels of cdk4, cdk6, cdk2, p16(INK4a), and p21(Cip1) were not affected. Among these effects, the decrease in cyclin D1 was prominent. DE decreased the level of cyclin D1 in rasREF cells in the suspension culture (a) at 0.1 microM and in the substratum-attached culture (b) at 1 microM, while the level of cyclin D1 in REF cells in the substratum-attached culture (c) was not decreased at 1 microM. The extent of growth inhibition correlated with the decrease in cyclin D1. The level of cyclin D1 mRNA of rasREF cells in the suspension culture (a) was also decreased by DE. DE decreased cyclin D1 mRNA, resulting in inhibition of anchorage-independent growth of rasREF cells.     

A glycoprotein from Laminaria japonica induces apoptosis in HT-29 colon cancer cells

We isolated a novel glycoprotein from the brown alga Laminaria japonica that has antiproliferative effects on HT-29 colon cancer cells. We also identified the mechanism by which this glycoprotein, named LJGP, induces apoptosis. MTS assays showed that LJGP inhibited the proliferation of several cancer cell lines (AGS, HepG2, HT-29) in a dose-dependent manner. Especially in HT-29 cells, proliferation was significantly decreased. LJGP treatment on HT-29 displayed several apoptotic features, such as DNA fragmentation, sub-G1 arrest, caspase-3 activation, and PARP degradation. Consistent with sub-G1 arrest, LJGP decreased the expression of Cdk2, cyclin E, cyclin D1, PCNA, E2F-1, and phosphorylated pRb. Furthermore, the increase of p27 expression was observed. We also determined that LJGP-induced apoptosis leads to the formation of a death-induced signaling complex of Fas, FADD, and procaspase-8. LJGP induced the reduction of mitochondrial membrane potential with activation of the Bcl-2 family of proteins and caspase-9. These findings suggest that LJGP inhibits HT-29 cell proliferation by inducing apoptosis, which may be mediated via multiple pathways, including the Fas signaling pathway, the mitochondrial pathway, and cell cycle arrest. Therefore, LJGP can be a useful treatment option for colon cancer in humans.     

Inhibition of colon cancer (HT-29) cell proliferation by a triterpenoid isolated from Azadirachta indica is accompanied by cell cycle arrest and up-regulation of p21

Nimbolide, a natural triterpenoid present in the edible parts of the neem tree ( Azadirachta indica), was found to be growth-inhibitory in human colon carcinoma HT-29 cells. Nimbolide treatment of cells at 2.5 - 10 microM resulted in moderate to very strong growth inhibition. Flow cytometric analysis of HT-29 cells showed that nimbolide treatment (2.5 microM, 12 h) caused a 6.5-fold increase in the number of cells (55.6 %) in the G2/M phase compared with the control cells (8.8 %). At 48 h, the cell population in the G2/M phase decreased to 18 %, while that in the G0/G1 phase increased to 52.3 %. Western blot analysis revealed that nimbolide-mediated G2/M arrest was accompanied by the up-regulation of p21, cyclin D2, Chk2; and down-regulation of cyclin A, cyclin E, Cdk2, Rad17. At G0/G1 cell cycle arrest, modulation in the expression of the cell cycle regulatory molecules was also observed. We found that nimbolide-induced growth inhibition and cell cycle arrest were not associated with cellular differentiation. Quantification of cells with respect to the expression of phosphatidylserine in the outer cell membrane showed an increase in apoptotic cells by about 13 % after 48 h of nimbolide treatment.     

Induction of urothelial proliferation in rats by aristolochic acid through cell cycle progression via activation of cyclin D1/cdk4 and cyclin E/cdk2.

Aristolochic acid (AA) has been implicated in urothelial carcinoma in humans. However, the mechanism by which AA induces this cancer has not been completely established. To evaluate the effects of AA on the urinary bladder of rats, a histopathological study of three-month intragastric feeding with mixture of AA (41% AA I, 56% AA II) was carried out. A total of 18 experimental rats were divided into three feeding regimens, with six rats in each group (group I, normal basal diet; groups II and III received intragastric 5 mg and 10 mg isolated AA mixture/kg/day for 5 days/week for 12 weeks). Dosage-dependent urothelial proliferation, but not carcinoma, was found in the urothelium of the bladder of the rats administered with AA mixture. Immunoprecipitation showed elevations of cyclin D(1)/cdk4 (increased induction by 1.57- and 1.95-fold in the groups II and III) and/or cyclin E/cdk2 complex (increased induction by 1.46- and 1.62-fold in the groups II and III), which promote the increasing phosphorylation of Rb (increased induction by 1.75- and 2.07-fold in the groups II and III) and result in decrease of the Rb/E2F complex (decreased expression by 0.65- and 0.24-fold in the groups II and III). Our results provide evidence to suggest that exposure to AA results in urothelial proliferation in rats through cell cycle progression via activation of cyclin D(1)/cdk4 and cyclin E/cdk2.     

Induction of cyclin E and inhibition of DNA synthesis by the novel acronycine derivative S23906-1 precede the irreversible arrest of tumor cells in S phase leading to apoptosis.

S23906-1 is a diester derivative of 1,2-dihydrobenzo[b]acronycine with an unknown mechanism of action. This cytotoxic compound was 20-fold more potent than acronycine in inhibiting the proliferation of six tumor cell lines. Using a clonogenic assay of cell survival, the HT29 human colon carcinoma cell line was 100-fold more sensitive to S23906-1 than acronycine. Cell cycle analysis, by flow cytometry, showed that S23906-1 induced a partially reversible arrest of HT29 cells in G2+M at 1 microM and below and an irreversible arrest in S phase at 2.5 microM and above. These cell cycle effects were followed by cell death through apoptosis, quantified by annexin-V labeling. Inhibition of DNA synthesis was observed by complete prevention of bromodeoxyuridine (BrdU) incorporation after only 4 h of incubation with 5 microM S23906-1. Interestingly, under the same experimental conditions, a significant increase of cyclin E protein level was observed without any modification of cyclins D1, D2, D3, or A. This overexpressed cyclin E protein was not complexed with Cdk2, as shown by western blotting for Cdk2 in immunoprecipitates of cyclin E. Similar inhibition of BrdU incorporation and elevation of cyclin E protein were observed after treatment with cytosine arabinoside, which reversibly inhibited progression into S phase, but not after DNA damage induced by cisplatin. S23906-1 thus has a novel mechanism of action. A cell line resistant to S23906-1 showed that overexpression of cyclin E was implicated in the novel cytotoxic activity of this compound.     

微小RNA-152-3p 对结肠癌细胞增殖、迁移和侵袭的影响及其作用机制研究

目的探讨微小RNA(miR)-152-3p对结肠癌细胞的增殖、迁移和侵袭的影响及机制。方法2019年2月至2020年4月,将结肠癌SW480细胞分为miR-152-3p模拟物阴性对照(miR-NC)组、miR-152-3p模拟物(miR-152-3p)组、抑制物(anti-miRNC)组、miR-152-3p抑制物(anti-miR-152-3p)组、阴性对照(si-NC)组、沉默转移相关蛋白2(si-MTA2)组、miR-152-3p模拟物+空载体(miR-152-3p+pcDNA3.1)组、miR-152-3p模拟物+过表达MTA2(miR-152-3p+pcDNA3.1-MTA2)组,均用脂质体法转染至结直肠癌SW480细胞中,另取未转染结直肠癌SW480细胞记为Control组。采用实时荧光定量逆转录聚合酶链反应(qRT-PCR)检测miR-152-3p和MTA2 mRNA的表达水平;蛋白质印迹法测定蛋白的表达;MTT法检测细胞活性;Transwell检测细胞迁移和侵袭;双荧光素酶报告基因检测实验检测荧光活性。结果结肠癌HCT116、SW480及LoVo细胞中miR-152-3p表达分别为0.72±0.04、0.29±0.02、0.49±0.01,人正常结肠上皮细胞NCM460中miR-152-3p表达为1.06±0.12,与正常结肠上皮细胞NCM460相比,结肠癌细胞HCT116、LoVo、SW480中MTA2 mRNA和蛋白较高,miR-152-3p较低(P<0.05);Control组、miR-NC组、miR-152-3p组、si-NC组及si-MTA2组结肠癌SW480细胞吸光度分别为0.92±0.22、0.96±0.17、0.31±0.07、0.99±0.17及0.32±0.09,细胞迁移数分别为(172.00±23.52)个、(169.00±20.66)个、(53.67±12.22)个、(155.67±16.8)个及(54.33±8.74)个,细胞侵袭数分别为(124.67±10.02)个、(122.33±9.45)个、(26.00±5.00)个、(108.33±10.02)个及(42.00±4.00)个,与miR-NC 组相比,miR-152-3p 组SW480细胞中细胞周期蛋白D1(cyclin D1)、基质金属蛋白酶(MMP)-2及SW480细胞活性、迁移和侵袭数量均较低,周期素依赖激酶抑制剂p21(P21)及上皮钙黏素(E-cadherin)较高(P<0.05);与si-NC组相比,si-MTA2组SW480细胞中cyclin D1、MMP-2及SW480细胞活性、迁移和侵袭数量均较低,P21及E-cadherin较高(P<0.05)。转染miR-152-3p和MTA2野生型表达载体的结肠癌SW480细胞荧光素酶活性显著降低(P<0.05)。相比miR-152-3p+pcDNA3.1组,miR-152-3p+pcDNA3.1-MTA2组SW480细胞中P21、E-cadherin的表达较低,MTA2、cyclin D1、MMP-2蛋白的表达较高,SW480细胞活性、迁移、侵袭数量较高(P<0.05)。结论miR-152-3p可能通过下调MTA2抑制结肠癌细胞的增殖、迁移和侵袭。     

The inhibitory effect of CIL-102 on the growth of human astrocytoma cells is mediated by the generation of reactive oxygen species and induction of ERK1/2 MAPK

CIL-102 (1-[4-(furo[2,3-b]quinolin-4-ylamino)phenyl]ethanone) is the major active agent of the alkaloid derivative of Camptotheca acuminata, with multiple pharmacological activities, including anticancer effects and promotion of apoptosis. The mechanism by which CIL-102 inhibits growth remains poorly understood in human astrocytoma cells. Herein, we investigated the molecular mechanisms by which CIL-102 affects the generation of reactive oxygen species (ROS) and cell cycle G2/M arrest in glioma cells. Treatment of U87 cells with 1.0 μM CIL-102 resulted in phosphorylation of extracellular signal-related kinase (ERK1/2), downregulation of cell cycle-related proteins (cyclin A, cyclin B, cyclin D1, and cdk1), and phosphorylation of cdk1Tyr¹⁵ and Cdc25cSer²¹⁶. Furthermore, treatment with the ERK1/2 inhibitor PD98059 abolished CIL-102-induced Cdc25cSer²¹⁶ expression and reversed CIL-102-inhibited cdk1 activation. In addition, N-acetyl cysteine (NAC), an ROS scavenger, blocked cell cycle G2/M arrest and phosphorylation of ERK1/2 and Cdc25cSer²¹⁶ in U87 cells. CIL-102-mediated ERK1/2 and ROS production, and cell cycle arrest were blocked by treatment with specific inhibitors. In conclusion, we have identified a novel CIL-102-inhibited proliferation in U87 cells by activating the ERK1/2 and Cdc25cSer²¹⁶ cell cycle-related proteins and inducing ROS production; this might be a new mechanism in human astrocytoma cells.     

Molecular mechanism of gossypol-induced cell growth inhibition and cell death of HT-29 human colon carcinoma cells

Gossypol, a male contraceptive drug, has been demonstrated to have antiproliferative and antimetastatic effects on many kinds of cancer cells in vitro. HT-29 human carcinoma cell line is one of the most susceptible cell lines to gossypol-induced cell death. Here, it is shown that treatment of HT-29 cells with gossypol not only induces cell cycle arrest on the G0/G1 phase, but also induces apoptosis. With a serial of Western blot analysis, it is revealed that gossypol-induced cell cycle arrest is involved in P21 up-regulation and cyclin D1 down-regulation; gossypol-induced apoptosis triggers down-regulation of anti-apoptosis Bcl-2 members: Bcl-X(L), Bag-1 and Mcl-1, up-regulation of pro-apoptosis Bcl-2 member Bak, activation of caspase-3, -6, -7, -8, and -9, up-regulation of Apaf-1, release of cytochrome c (cyto-c) from mitochondria, and activation of both DFF45 and PARP. Taken together, gossypol-induced cell death initiates extensive alterations of cell cycle and apoptosis proteins. Gossypol-induced apoptosis of HT-29 cells is through first the mitochondrial pathway, then the death receptor pathway, and the mitochondria pathway is, at least in part, involved in cyto-c release.     

Quantitative effects on c-Jun N-terminal protein kinase signaling determine synergistic interaction of cisplatin and 17-allylamino-17-demethoxygeldanamycin in colon cancer cell lines

We investigated the effects of cisplatin and the hsp90 inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG) in combination in a panel of human colon adenocarcinoma cell lines that differ in their p53 and mismatch repair status. Analysis of cytotoxicity after combined treatment revealed additive effects of cisplatin and 17-AAG in the HCT 116, DLD1, and SW480 cell lines and antagonism in HT-29 cells. Clonogenic assays demonstrated antagonism in HT-29, an additive effect in SW480, and synergism in HCT 116 and DLD1 cell lines. Analysis of signaling pathways revealed that cisplatin-induced activation of c-Jun N-terminal kinase (JNK) was fully blocked by 17-AAG in HT-29 and SW480 cells, whereas in HCT 116 and DLD1 cells it was inhibited only partially. The activation of caspases was also more pronounced in DLD1 and HCT 116 cell lines. These data suggested that a minimal level of apoptotic signaling through JNK was required for synergism with this combination. To test this hypothesis, we used the specific JNK inhibitor SP600125; when JNK was inhibited pharmacologically in HCT 116 and DLD1 cells, they demonstrated increased survival in clonogenic assays. Alternatively, sustained activation of JNK pathway led to an increase of the cytotoxicity of the cisplatin/17-AAG combination in HT-29 cells. Taken together, these data suggest that the synergistic interaction of this combination in colon cancer cell lines depends on the effect exerted by 17-AAG on cisplatin-induced signaling through JNK and associated pathways leading to cell death. An implication of that finding is that quantitative effects of signaling inhibitors may be critical for their ability to reverse cisplatin resistance.     

MK801对结肠癌细胞增殖、凋亡和迁移的影响

摘要： 目的 探究 N-甲基-D-天冬氨酸受体亚型 1（NMDAR1）在结肠癌细胞 HT29 和 SW116 中的表达, 以及 NMDAR1 拮抗剂 MK801 对 HT-29 和 SW116 细胞生长抑制、 凋亡和迁移的影响。方法 采用免疫组织化学法检测 结肠癌细胞 HT-29 和 SW116 细胞表面 NMDAR1 的表达; 应用噻唑蓝（MTT）比色法测定 62.5、 125.0、 250.0、 500.0、 1 000.0、 2 000.0 μmol/L 的 MK801 对于 HT-29 和 SW116 细胞增殖作用的影响; 应用流式细胞术检测 2 000 μmol/L 的 MK801 对 HT29 和 SW116 细胞凋亡的影响; 应用细胞划痕实验检测 50 μmol/L MK801 对于结肠癌细胞 HT-29 和 SW116 迁移能力的影响。结果 结肠癌细胞 HT-29 和 SW116 均表达 NMDAR1, 且主要表达于细胞质中; 各浓度的 MK801 对 HT-29 细胞, 以及浓度为 500.0、 1 000.0、 2 000.0 μmol/L 的 MK801 对 SW116 细胞的生长抑制作用具有时 间效应关系, 24、 48 及 72 h 各 MK801 浓度组对 HT-29 和 SW116 细胞的抑制率随浓度升高整体呈增强趋势, 但抑制 率不呈明显的剂量效应关系; MK801 具有促进 HT-29 和 SW116 细胞凋亡的作用, 且主要表现诱导细胞早期凋亡; MK801 可抑制 HT-29 和 SW116 细胞迁移。结论 NMDAR1 在结肠癌细胞胞质中表达, 且 NMDAR1 拮抗剂 MK801 具有抑制肿瘤细胞生长、 迁移, 促进其早期凋亡的作用, 有望成为新一代抗肿瘤药物。     

Involvement of cyclin D1/CDK4 and pRb mediated by PI3K/AKT pathway activation in Pb2+ -induced neuronal death in cultured hippocampal neurons

Lead (Pb) is widely recognized as a neurotoxicant. One of the suggested mechanisms of lead neurotoxicity is apoptotic cell death. And the mechanism by which Pb(2+) causes neuronal death is not well understood. The present study sought to examine the obligate nature of cyclin D1/cyclin-dependent kinase 4 (CDK4), phosphorylation of its substrate retinoblastoma protein (pRb) and its select upstream signal phosphoinositide 3-kinase (PI3K)/AKT pathway in the death of primary cultured rat hippocampal neurons evoked by Pb(2+). Our data showed that lead treatment of primary hippocampal cultures results in dose-dependent cell death. Inhibition of CDK4 prevented Pb(2+)-induced neuronal death significantly but was incomplete. In addition, we demonstrated that the levels of cyclin D1 and pRb/p107 were increased during Pb(2+) treatment. These elevated expression persisted up to 48 h, returning to control levels after 72 h. We also presented pharmacological and morphological evidences that cyclin D1/CDK4 and pRb/p107 were required for such kind of neuronal death. Addition of the PI3K inhibitor LY294002 (30 microM) or wortmannin (100 nM) significantly rescued the cultured hippocampal neurons from death caused by Pb(2+). And that Pb(2+)-elicited phospho-AKT (Ser473) participated in the induction of cyclin D1 and partial pRb/p107 expression. These results provide evidences that cell cycle elements play a required role in the death of neurons evoked by Pb(2+) and suggest that certain signaling elements upstream of cyclin D1/CDK4 are modified and/or required for this form of neuronal death.     

Anti-Proliferative Effect of Naringenin through p38-Dependent Downregulation of Cyclin D1 in Human Colorectal Cancer Cells

Naringenin (NAR) as one of the flavonoids observed in grapefruit has been reported to exhibit an anti-cancer activity. However, more detailed mechanism by which NAR exerts anti-cancer properties still remains unanswered. Thus, in this study, we have shown that NAR down-regulates the level of cyclin D1 in human colorectal cancer cell lines, HCT116 and SW480. NAR inhibited the cell proliferation in HCT116 and SW480 cells and decreased the level of cyclin D1 protein. Inhibition of proteasomal degradation by MG132 blocked NAR-mediated cyclin D1 downregulation and the half-life of cyclin D1 was decreased in the cells treated with NAR. In addition, NAR increased the phosphorylation of cyclin D1 at threonine-286 and a point mutation of threonine-286 to alanine blocked cyclin D1 downregulation by NAR. p38 inactivation attenuated cyclin D1 downregulation by NAR. From these results, we suggest that NAR-mediated cyclin D1 downregulation may result from proteasomal degradation through p38 activation. The current study provides new mechanistic link between NAR, cyclin D1 downregulation and cell growth in human colorectal cancer cells.     

化合物209对人结直肠癌细胞HT-29的体内和体外作用(英文)

化合物209是一个新合成的氨基二硫代甲酸酯类化合物,它在体外水平可以抑制肿瘤细胞的增殖,但是化合物209的体内抗肿瘤作用及其抗肿瘤机制并不明确。本文探究了化合物209对人结直肠癌细胞HT-29的作用并初步探讨了相关机制。体外研究表明,化合物209可以显著抑制HT-29细胞的增殖;体内研究结果表明,化合物209可以显著抑制裸鼠HT-29移植瘤的生长,但是对裸鼠体重和白细胞无影响。流式细胞分析实验结果表明,化合物209可将HT-29细胞阻滞于细胞周期的G1期。同时,化合物209能上调体外培养HT-29细胞中p27,cyclin E,CDK2,cyclin D1和CDK4的表达。在体内瘤组织中上述蛋白表达情况与体外实验结果一致。这些结果说明,化合物209具有较好的抗肿瘤活性,其抗肿瘤作用与细胞周期阻滞及其相关蛋白的表达变化有关。