nmhaFGF对人乳腺癌细胞增殖的影响及相关机制

目的比较nmhaFGF和haFGF对恶性肿瘤细胞的促增殖作用及其机制，探讨nmhaFGF临床应用的安全性。方法以haFGF和nmhaFGF分别处理人乳腺癌细胞(MCF-7)，用MTT法检测其细胞增殖活性；用流式细胞技术分析细胞周期；用蛋白免疫印迹法半定量检测MAPK通路中的信号蛋白Grb2和ERK1/2在MCF-7中的表达。结果nmhaFGF对MCF-7细胞的促增殖作用明显低于haFGF；haFGF组G₁/G₀和G₂/M期细胞比例均低于nmhaFGF组和对照组，S期细胞比例显著高于nmhaFGF组和对照组；nmhaFGF组的Grb2和ERK1/2信号蛋白表达水平均低于haFGF组，亦接近对照组。结论nmhaFGF的促增殖活性显著下降，其机制是通过下调MAPK信号通路中的Grb2和ERK1/2信号分子的表达来实现的。     

大黄素可能通过抑制Akt信号通路诱导HL-60细胞凋亡

为研究大黄素(emodin)对人髓系白血病细胞株HL-60细胞增殖、凋亡的影响及Akt信号通路在其中的作用, 应用MTT法检测大黄素对HL-60细胞增殖的影响；细胞周期分析、线粒体细胞凋亡流式检测法分析细胞周期变化及细胞凋亡；Western blotting检测Akt信号通路蛋白表达水平的变化。结果显示，大黄素能有效抑制HL-60细胞的增殖，作用48 h的IC₅₀约为20 μmol·L^-1， 并能诱导其凋亡, 随药物作用浓度的增加， 凋亡率也逐渐上升； 大黄素作用后， HL-60细胞G_0/G1期细胞增多， 而S期及G₂期的细胞减少； Western blotting检测结果显示， 大黄素下调HL-60细胞Akt、p-Akt、IκB-α、p-IκB-α、p65、p-p65、mTOR及p-mTOR蛋白的表达。因此,大黄素能有效抑制HL-60细胞增殖，将细胞阻滞于G_0/G1期，诱导其凋亡；Akt信号通路可能参与了大黄素抑制HL-60细胞增殖、诱导凋亡的过程。     

Jatamanvaltrate P对乳腺癌细胞T47D增殖的影响及机制研究

目的 考察蜘蛛香中环烯醚萜类化合物Jatamanvaltrate P对乳腺癌细胞T47D的增殖影响及作用机制。方法 MTT法检测Jatamanvaltrate P对乳腺癌细胞T47D和BT-20增殖的影响;DAPI染色和流式细胞术检测Jatamanvaltrate P对T47D细胞凋亡和周期的影响;Western blot检测与细胞周期、凋亡相关蛋白的变化。结果 Jatamanvaltrate P能明显抑制乳腺癌细胞增殖,并且呈时间-剂量依赖性;Jatamanvaltrate P能明显将T47D细胞阻滞于G₂/M期,下调周期相关蛋白cdc-2和Cyclin B1,上调p-cdc-2;Jatamanvaltrate P能诱导T47D细胞产生凋亡小体,显著性增加T47D细胞凋亡比例,呈现剂量依赖性;Jatamanvaltrate P处理后的蛋白PARP和Caspase 3/8/9出现了活化形式。结论 Jatamanvaltrate P通过阻滞细胞周期、诱导细胞凋亡来抑制乳腺癌细胞T47D的增殖,有望成为一种潜在的治疗乳腺癌的药物。     

冬凌草甲素对K562细胞端粒酶活性调控及细胞周期的影响

目的研究冬凌草甲素(ORI)对K562细胞端粒酶活性及其细胞周期的影响。方法免疫细胞化学法测定K562细胞中hTERT和C-myc蛋白的表达；TRAP-PCR-ELISA法检测了端粒酶活性变化；流式细胞仪测定细胞周期各时相百分比。结果用3.43 μmol·L^-1 ORI作用于Ｋ562细胞48 h后，hTERT和C-myc蛋白的表达降低；在一定的浓度范围内，ORI可下调K562细胞端粒酶活性。同时细胞周期各时相分布发生变化，G₀/G₁期或G₂/M期细胞增多，S期细胞减少。结论ORI可下调K562细胞的端粒酶活性，其机制可能与其细胞周期阻滞作用及抑制hTERT和C-myc蛋白的表达有关。     

3-取代芳基氧化吲哚(PH II-7)对肿瘤细胞周期的影响

目的观察3-取代芳基氧化吲哚(PH II-7)对肿瘤细胞周期分布的影响，明确PH II-7的抗敏感肿瘤和耐药肿瘤的共同机制。方法用流式细胞仪检测细胞周期分布，Western印迹分析细胞周期相关蛋白的表达，³H-TdR参入法检测细胞DNA合成，ELISA测定酪氨酸激酶的活性。结果PH II-7对多种肿瘤细胞（包括耐药细胞）的周期分布均有影响，阻滞细胞G₁期至S期的移行，细胞周期相关蛋白CDK2，Rb和c-myc的表达被抑制，Cyclin E的表达升高。PH II-7还可抑制³H-TdR的参入，抑制EGFR的酪氨酸激酶的活性。结论抗耐药肿瘤新药PH II-7是一种细胞周期阻滞剂，可能是通过抑制CDK2而使肿瘤细胞阻滞在G₁期，同时也说明细胞周期阻滞可能是抗耐药肿瘤的新方向。     

苯并呋喃类木脂素衍生物通过抑制细胞周期蛋白质活性诱导MCF-7细胞G2/M期阻滞及凋亡

研究全新合成的苯并呋喃类木脂素化合物2-(3-甲氧基-4-羟基苯基)-4-甲酰基-5-(2-甲氧基羰基乙基)-7-甲氧基苯并［b］呋喃(ERJT-12)的体外抗肿瘤细胞增殖作用及其分子机制。MTT法测定ERJT-12对人肿瘤细胞的抗增殖活性，流式细胞术检测细胞周期分布的改变及细胞凋亡，琼脂糖凝胶电泳检测DNA梯状条带，比色法测定Caspase-3/7和Caspase-6的活性，Western blotting检测细胞周期蛋白质Cdc25c(cell divide cycle 25c)、CDK1(cyclin dependent kinase 1)和CyclinB1的改变以及凋亡相关蛋白Bax和Bcl-2的变化。结果显示，ERJT-12对包括多药耐药细胞在内的多种人肿瘤细胞呈现出明显的细胞毒作用。ERJT-12可诱导MCF-7细胞出现明显的G₂/M期阻滞及细胞凋亡，细胞中Caspase-3/7和Caspase-6的活性显著升高； CyclinB1蛋白表达下调，Cdc25c和CDK1的活性下降，Bcl-2蛋白被磷酸化。ERJT-12具有显著的抗肿瘤细胞增殖活性，通过抑制细胞周期相关蛋白活性诱导细胞周期阻滞从而触发凋亡，可能成为新的抗肿瘤药物。     

大蒜素联合顺铂对人宫颈癌细胞增殖的抑制作用

目的探讨大蒜素联合顺铂对人宫颈癌HeLa细胞增殖的抑制作用并探讨其机制。方法取对数生长期HeLa细胞，设对照组、大蒜素（50 μg/mL）组、顺铂（5 μg/mL）组、联合给药组（大蒜素50 μg/mL+顺铂5 μg/mL）。药物干预48 h后，通过MTT法检测细胞增殖抑制率，运用CompuSyn软件计算大蒜素与顺铂联合指数（CI），流式细胞术检测细胞周期分布和细胞凋亡水平，Western blotting法检测Cyclin D1、CDK2、P27、Cleaved Caspase-3、Bcl-2、Bax蛋白表达。结果与大蒜素组和顺铂组比较，联合给药组HeLa细胞增殖抑制率显著升高（P<0.05、0.01），CI为0.69（提示大蒜素与顺铂具有中度协同效应）。与对照组比较，大蒜素组和顺铂组G₀/G₁期细胞比例和细胞凋亡率显著升高（P<0.05、0.01），Cyclin D1、CDK2、Bcl-2表达显著下调且P27、Cleaved Caspase-3、Bax表达显著上调（P<0.05、0.01），Bax/Bcl-2比值显著升高（P<0.01）。与大蒜素组和顺铂组比较，联合给药组G₀/G₁期细胞比例和细胞凋亡率显著升高（P<0.05、0.01），Cyclin D1表达显著下调且P27、Cleaved Caspase-3、Bax表达显著上调（P<0.05、0.01），Bax/Bcl-2值显著升高（P<0.01）。结论大蒜素联合顺铂具有协同抑制人宫颈癌HeLa细胞增殖的作用，可能与调节细胞周期和凋亡相关蛋白表达，进而阻滞细胞周期进程并促进细胞凋亡有关。     

黄芪抑制血管平滑肌细胞增殖及其作用机制

目的　观察黄芪(AS)对血管平滑肌细胞(VSMC)增殖的抑制作用,了解黄芪是否通过刺激VSMC产生一氧化氮(nitricoxide,NO) ,使细胞周期停滞于G₀/G₁期,从而抑制平滑肌细胞增殖。方法　[³H] 胸腺嘧啶核苷酸([³H] TdR)掺入测定VSMCDNA合成,流式细胞仪检测细胞周期情况,硝酸还原酶法测定细胞培养上清中NO水平。结果　黄芪以剂量依赖关系抑制血清诱导的VSMC[³H] 胸腺嘧啶核苷酸掺入,使G₀/G₁期细胞比例明显增多,S期细胞比例显著减少,黄芪刺激VSMC后,细胞培养上清中NO水平呈剂量依赖上升。结论　黄芪能抑制VSMC增殖,使细胞周期停滞于G₀/G₁期,这一过程可能与黄芪刺激VSMC产生NO有关     

大黄素对人胃癌MNK-45和MGC8-03细胞增殖的影响

目的 观察大黄素对人胃癌MNK-45和MGC8-03细胞增殖的影响。方法 采用MTT法测定MNK-45细胞和MGC8-03细胞增殖抑制率;采用AO/EB双染观察细胞形态学变化;采用流式细胞仪测定细胞周期。结果 大黄素（5～80 μg/mL）对MNK-45和MGC8-03细胞增殖均具有显著抑制作用。P＜0.01或0.05）,且药物剂量越大,作用时间越长,其抑制作用越强（P＜0.01）;大黄素作用于两种细胞后荧光显微镜下观察均显示细胞凋亡特征;大黄素使MNK-45和MGC8-03细胞增殖被阻滞于G₀/G₁期。结论 大黄素能抑制人胃癌MNK-45和MGC8-03细胞增殖,诱导其凋亡,影响其细胞周期时相的分布。     

杠柳毒苷体外抑制肝癌细胞和乳腺癌细胞增殖的实验研究

目的 探讨杠柳毒苷在体外对人乳腺癌MDA-MB-468细胞和人肝癌HepG2细胞增殖的影响。方法 MTT法观察杠柳毒苷对人乳腺癌MDA-MB-468细胞和人肝癌HepG2细胞增殖的抑制作用,流式细胞术观察杠柳毒苷对两种肿瘤细胞的细胞增殖周期作用。结果 与对照组比较,杠柳毒苷能明显抑制两种肿瘤细胞的增殖,其抑制率与药物浓度和作用时间呈正相关。流式细胞仪检测发现,杠柳毒苷对乳腺癌MDA-MB-468细胞和肝癌HepG2细胞持续作用24 h后,可以使G₀/G₁期细胞增多,G₂/M期细胞减少。结论 杠柳毒苷具有抑制乳腺癌MDA-MB-468细胞和肝癌HepG2细胞增殖的作用,并可将乳腺癌MDA-MB-468细胞和肝癌HepG2细胞的细胞生长周期阻滞在G₀/G₁期。     

Dexamethasone inhibits basic fibroblast growth factor-stimulated gastric epithelial cell proliferation

Basic fibroblast growth factor (bFGF) is essential for gastric ulcer healing, whereas glucocorticoids delay gastric ulcer healing. We found that dexamethasone inhibited bFGF-stimulated rat gastric epithelial RGM-1 cells proliferation and attempted to elucidate the possible mechanistic pathway. Flowcytometry was used to determine cell proliferation. Western blot and RT-PCR were performed to evaluate changes in signaling pathways. Results showed that bFGF significantly increased mRNA expression of FGF receptor (FGFR)1 and FGFR2 at 10 min and increased expression of phosphorylated extracellular signal-regulated kinase (pERK1/pERK2) but not phosphorylated p38 mitogen-activated protein kinase (MAPK) or phosphorylated phosphatidylinositol 3-kinase (PI3K) within 30 min. This was followed by an increase of cyclooxygenase (COX)-2 mRNA and protein expression at 30 and 240 min, respectively. Mitogen-activated protein kinase kinase (MEK) inhibitor-PD98059 (10(-5) M) markedly suppressed bFGF-stimulated COX-2 expression and cell proliferation, but neither p38 MAPK inhibitor-SB203580 nor PI3K inhibitor-Wortmannin had any effect. Dexamethasone (10(-6)M) substantially reduced bFGF-stimulated ERK activation at 10 min, COX-2 mRNA and protein expression at 30 and 240 min, respectively, and prostaglandin E(2) synthesis at 8 h. Dexamethasone (10(-6) M) also significantly decreased mRNA expression of FGFR1 and FGFR2 at basal and bFGF-stimulated conditions at 10 min. This study indicated that bFGF-stimulated gastric epithelial RGM-1 cells proliferation via up-regulating FGFR1 and FGFR2, activating ERK1/ERK2 signal transduction pathway and COX-2 pathway. Dexamethasone significantly suppresses bFGF-stimulated RGM-1 cells proliferation in part via down-regulation of FGFR1/FGFR2, then decreasing bFGF-stimulated activation of ERK1/ERK2, followed by inhibition of COX-2 activation, and finally DNA synthesis.     

氨氯地平抑制人血管平滑肌细胞增殖机制的研究

目的　观察氨氯地平对人血管平滑肌细胞（VSMC）丝裂素活化蛋白激酶（MAPK）活性的影响。方法　取人乳腺下动脉培养VSMC,用bFGF刺激细胞增殖,观察氨氯地平对bFGF激活的MAPK活性的影响,用p42/p44磷酸化抗体蛋白免疫印迹法测定MAPK活性。 结果　bFGF对MAPK有显著激活作用,激活峰值出现在5～15 min,维持至3 h; 此活化作用被MAPK激酶的特异抑制剂PD98059抑制; 无论瞬时或持久的bFGF激活的MAPK活性均被氨氯地平抑制。 结论　氨氯地平通过MAPK信号转导途径抑制bFGF所致的细胞增殖。     

人参皂苷Rg3对乳腺癌MCF-7细胞增殖和侵袭的影响

目的 观察人参皂苷Rg3对雌激素受体阳性的乳腺癌细胞MCF-7增殖和侵袭的影响,并探讨其可能的作用机制。方法 采用MTT法检测细胞的增殖能力,流式细胞仪分析细胞周期分布以及凋亡比率,通过Transwell小室观察细胞侵袭力,RT-PCR法检测细胞中的MMP-9 mRNA的表达。结果 与对照组相比,人参皂苷Rg3能显著抑制MCF-7细胞的增殖;G₀/G₁期及S期细胞比例减少,而G₂/M期细胞比例显著增加;同时细胞凋亡比率亦明显提升,而细胞侵袭指数降低,且呈现良好的剂量、时间依赖性。同时人参皂苷Rg3还能显著抑制细胞中MMP-9 mRNA的表达水平(P<0.05)。结论 人参皂苷Rg3能抑制MCF-7细胞的增殖和侵袭,其作用机制可能与其能降低MMP-9基因的表达有关。     

Distinct MAPK signaling pathways, p21 up-regulation and caspase-mediated p21 cleavage establishes the fate of U937 cells exposed to 3-hydrogenkwadaphnin: differentiation versus apoptosis

Despite the depth of knowledge concerning the pathogenesis of acute myeloblastic leukemia (AML), long-term survival remains unresolved. Therefore, new agents that act more selectively and more potently are required. In that line, we have recently characterized a novel diterpene ester, called 3-hydrogenkwadaphnin (3-HK), with capability to induce both differentiation and apoptosis in various leukemia cell lines. These effects of 3-HK were mediated through inhibition of inosine 5′-monophosphate dehydrogenase, a selective up-regulated enzyme in cancerous cells, especially leukemia. However, it remains elusive to understand how cells display different fates in response to 3-HK. Here, we report the distinct molecular signaling pathways involved in forcing of 3-HK-treated U937 cells to undergo differentiation and apoptosis. After 3-HK (15 nM) treatment, a portion of U937 cells adhered to the culture plates and showed macrophage criteria while others remained in suspension and underwent apoptosis. The differentiated cells arrested in G₀/G₁ phase of cell cycle and showed early activation of ERK1/2 pathway (3 h) along with ERK-dependent p21^Cip/WAF1 (p21) up-regulation and expression of p27^Kip1 and Bcl-2. In contrast, the suspension cells underwent apoptosis through Fas/FasL and mitochondrial pathways. The occurrence of apoptosis in these cells were accompanied with caspase-8-mediated p21 cleavage and delayed activation (24 h) of JNK1/2 and p38 MAPK. Taken together, these results suggest that distinct signaling pathways play a pivotal role in fates of drug-treated leukemia cells, thus this may pave some novel therapeutical utilities.     

Mitogen-activated protein kinase (MAPK) pathway mediates the oestrogen-like activities of ginsenoside Rg1 in human breast cancer (MCF-7) cells

Background and purpose:

The present study was designed to determine how ginsenoside Rg1, an active ingredient in ginseng root, exerts its oestrogenic effects. We hypothesize that Rg1 may exert oestrogen-like actions in MCF-7 cells by activating the mitogen-activated protein kinase (MAPK) pathway in a ligand-independent manner.

Experimental approach:

MCF-7 cells were co-incubated with the MAPK inhibitor PD98059 to determine whether the stimulant effects of Rg1 on cell proliferation, the induction of IGF-IR and pS2, the functional transactivation of oestrogen receptor-α (ERα), as well as ERα phosphorylation are dependent on MAPK. The time-dependent responses of mitogen-activated protein kinase kinase (MEK) and extracellular signal-regulated protein kinase (ERK) to Rg1 in MCF-7 cells were studied. The responses of MEK phosphorylation to Rg1 in oestrogen receptor (ER)-negative HEK293 cells were also determined. The effects of Rg1 on cell proliferation and IGF-IR protein expression were studied in the presence of tyrosine kinase inhibitor genistein to elucidate the involvement of tyrosine kinase in mediating these effects.

Key results:

The oestrogenic effects of Rg1 in MCF-7 cells were abolished in the presence of PD98059. Rg1 could induce MEK protein expression and the phosphorylation level of MEK and ERK significantly in a time- and dose-dependent manner. Rg1 activated MEK phosphorylation in ER-negative HEK293 cells in a time- and dose-dependent manner. Rg1 induction of cell proliferation and IGF-IR protein expression was abolished by co-treatment with genistein.

Conclusions and implications:

Taken together, these results show that the MAPK pathway is involved in mediating the oestrogen-like actions of Rg1 in MCF-7 cells and suggest that Rg1 may activate ERα via MEK/ERK in a ligand-independent manner.     

Somatostatin sst5 inhibition of receptor mediated regeneration of rat aortic vascular smooth muscle cells

1. The aim of the present study was to determine the effect of somatostatin (SRIF) on mitogen-induced regeneration of rat aortic vascular smooth muscle cells (VSMC) and for comparison Chinese hamster ovary (CHO)-K1 cells expressing human recombinant sst₅ receptors (CHOsst₅), following partial denudation of a confluent cell monolayer. Regeneration was assessed by measuring areas of recovery into the denuded area and by counting total cell numbers.
2. In VSMC, SRIF (0.1 nM–1 μM) had no effect on the basal levels of regeneration but caused a concentration-dependent inhibition (pIC₅₀ 8.0–8.6) of the stimulated regeneration induced by sub-maximal concentrations of basic fibroblast growth factor (bFGF, 10 ng ml⁻¹), platelet-derived growth factor-BB (PDGF, 5 ng ml⁻¹) or endothelin-1 (ET-1, 100 nM). SRIF (pIC₅₀ 8.8) also inhibited bFGF-induced regeneration of CHOsst₅ cells.
3. In VSMC, the inhibitory action of SRIF on the regeneration induced by bFGF (10 ng ml⁻¹) was due to an anti-proliferative effect, rather than an effect on cell migration, as SRIF (0.1 nM–1 μM) abolished bFGF-induced increases in total cell numbers. The bFGF-induced increase in cell numbers was also abolished by actinomycin D (0.1 μg ml⁻¹).
4. The sst₅ receptor-selective agonist, L-362,855 (pIC₅₀ 10.5), was about 100 times more potent than SRIF at inhibiting bFGF-induced regeneration of both VSMC and CHOsst₅ cells whilst the sst₂ receptor-selective agonist, BIM-23027 (pIC₅₀ 6.8), was approximately 20 times weaker than SRIF.
5. The sst₅ receptor antagonist, BIM-23056 (100 nM), antagonized SRIF-induced inhibition of bFGF-induced regeneration in both VSMC and CHOsst₅ cells (estimated pK_B values 8.8 and 8.3, respectively).
6. SRIF-induced inhibition of bFGF-induced regeneration of VSMC and CHOsst₅ cells was abolished by pretreating cells with pertussis toxin (100 ng ml⁻¹) for 20 h.
7. These findings suggest that SRIF-induced inhibition of the proliferation of rat aortic VSMC is mediated via activation of receptors which are similar to human sst₅ receptors. Furthermore this inhibitory effect is transduced via pertussis toxin-sensitive G_i/G_o proteins.

     

Paris saponin VII inhibits growth of colorectal cancer cells through Ras signaling pathway

Dysregulation of the Ras signaling pathway plays a key role in the progression of colorectal cancer. When bound to GTP, Ras is activated and stimulates several downstream effectors’ pathways, including the Raf/MEK/ERK kinase cascade, the PI3-kinase/AKT/mTor pathway, and the Ral GTPase pathway. Saponins extracted from Liliaceae family herbs have strong antitumor activities with low toxicity. In this study, Paris saponin VII (PSVII), isolated from Trillium tschonoskii Maxim., was evaluated on human colorectal cancer cells (HT-29 and SW-620), a mouse model of colitis associated colorectal cancer (CACC) and a murine model of xenograft tumor. It was found that PSVII inhibited colorectal cancer cell growth in a concentration-dependent manner. The IC₅₀ values of PSVII for growth inhibition of HT-29 and SW-620 cells were 1.02 ± 0.05 μM and 4.90 ± 0.23 μM. It could induce cell apoptosis, together with cell cycle arrest in G₁ phase, and trigger apoptosis in a caspase-3-dependent manner. PSVII-induced growth inhibitory effect was associated with disturbance of MAPK pathway by down-regulating MEK1/2, ERK1/2 phosphorylation, and suppression of AKT pathway by reducing AKT and GSK-3β phosphorylation. In the CACC mouse model, PSVII protected mice from intestinal toxicities and carcinogenesis induced by 1,2-dimethylhydrazine (DMH) and dextran sodium sulfate (DSS). In the model of xenograft tumor, PSVII remarkably decreased the xenograft tumor size and triggered the apoptosis of tumor cells. Both in vitro and in vivo study showed that PSVII inhibited Ras activity. Taken together, PSVII might be a potential therapeutic reagent for colorectal cancer through targeting Ras signaling pathway.     

Nicotine and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone induce cyclooxygenase-2 activity in human gastric cancer cells: Involvement of nicotinic acetylcholine receptor (nAChR) and beta-adrenergic receptor signaling pathways

Induction of cyclooxygenase-2 (COX-2) associates with cigarette smoke exposure in many malignancies. Nicotine and its derivative, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), are the two important components in cigarette smoke that contributes to cancer development. However, the molecular mechanism(s) by which nicotine or NNK promotes gastric carcinogenesis remains largely unknown. We found that nicotine and NNK significantly enhanced cell proliferation in AGS cells that expressed both alpha7 nicotinic acetylcholine receptor (α7 nAChR) and β-adrenergic receptors. Treatment of cells with α-bungarotoxin (α-BTX, α7nAChR antagonist) or propranolol (β-adrenergic receptor antagonist) blocked NNK-induced COX-2/PGE₂ and cell proliferation, while nicotine-mediated cell growth and COX-2/PGE₂ induction can only be suppressed by propranolol, but not α-BTX. Moreover, in contrast to the dependence of growth promoting effect of nicotine on Erk activation, inhibitor of p38 mitogen-activated protein kinase (MAPK) repressed NNK-induced COX-2 upregulation and resulted in suppression of cell growth. In addition, nicotine and NNK mediated COX-2 induction via different receptors to modulate several G1/S transition regulatory proteins and promote gastric cancer cell growth. Selective COX-2 inhibitor (SC-236) caused G1 arrest and abrogated nicotine/NNK-induced cell proliferation. Aberrant expression of cyclin D1 and other G1 regulatory proteins are reversed by blockade of COX-2. These results pointed to the importance of adrenergic and nicotinic receptors in gastric tumor growth through MAPK/COX-2 activation, which may perhaps provide a chemoprevention strategy for cigarette smoke-related gastric carcinogenesis.