FHIT、p21waf1/cip1基因在膀胱移行细胞癌中的表达与意义

目的:通过测定脆性组氨酸三联体基因(FHIT)及p21waf1/cip1基因在膀胱移行细胞癌组织、正常膀胱组织中的表达,探讨FHIT基因以及p21waf1/cip1基因与膀胱癌的关系及其临床意义。方法:采用免疫组织化学SP法对43例膀胱移行细胞癌(BTCC)组织及14例正常膀胱组织中的FHIT基因及p21waf1/cip1基因的蛋白表达进行检测。结果:FHIT蛋白表达与肿瘤的分期、分级无相关性(P>0.05)而p21waf1/cip1蛋白的表达与之有相关性(P<0.05);FHIT蛋白的表达在GI肿瘤、浅表性肿瘤中明显低于在正常膀胱组织中的表达(P<0.05)而p21waf1/cip1蛋白的表达在上述组织比较中无差别(P>0.05);FHIT蛋白的表达在初发肿瘤中与复发肿瘤中无明显差别(P>0.05)而p21waf1/cip1蛋白的表达在上述两种组织比较有明显差别(P<0.05)。FHIT蛋白与p21waf1/cip1蛋白的表达没有相关性(P>0.05)。结论:FHIT基因可能成为早期诊断膀胱移行细胞癌的指标。p21waf1/cip1基因可能成为估计膀胱移行细胞癌的恶性程度及肿瘤侵袭性、预后的指标。FHIT基因在膀胱移行细胞癌中的作用机制可能与p21waf1/cip1基因没有关系。     

Protease inhibitor-induced stabilization of p21(waf1/cip1) and cell-cycle arrest in chemical carcinogen-exposed mammary and lung cells.

In previous studies, we have shown that human breast and lung carcinoma cells and mouse nontransformed type II lung cells fail to undergo cell-cycle arrest in G(1) phase in response to treatment with hydrocarbon carcinogens but rather accumulate in the S phase with damaged DNA. This situation may lead to replication of DNA on a damaged template and enhance frequency of mutations. The mechanism of this G(1) arrest failure was examined. Western immunoblot analyses of MCF7 human mammary cancer cells exposed to actinomycin D (used as a positive control for G(1) cell-cycle arrest) or hydrocarbon carcinogens revealed that while all of these chemicals caused an increase in p53, only trace levels of p21(waf1/cip1) protein were observed in the hydrocarbon carcinogen-treated samples. Similarly, in murine lung E10 type II cells, p53 but not p21(waf1/cip1) protein increased in response to benzo[a]pyrene dihydrodiol epoxide. Treatment of either MCF7 mammary or E10 lung cells with the protease inhibitor calpain I resulted in increased levels of p21(waf1/cip1) protein and enhancement of arrest of the cells in early phases of the cell cycle (G(1) and early S phase). The results suggest that failure of cell-cycle arrest in carcinogen-treated mammary and lung cells is related to increased protease-mediated degradation of p21(waf1/cip1) and/or related regulatory proteins.     

p21~(waf1)基因转染对乳腺癌细胞增殖活性的影响

目的 探讨p21waf1基因转染对人乳腺癌细胞增殖活性影响及意义.方法 应用脂质体介导法将pIRES-p21waf1真核表达载体转染入人乳腺癌MCF-7细胞系,并得到稳定的表达.通过荧光定量PCR、Western blot法分别检测p21waf1基因表达及蛋白表达情况, MTT法检测细胞增殖,流式细胞仪检测细胞周期分布.结果 p21waf1基因转染后乳腺癌细胞生长显著受抑制,细胞周期停滞于G1期,转染组G1期、S期和G2/M期细胞比例分别为(70.52±3.21)%、(16.38±1.17)%、(9.42±0.98)%,未转染组则为(49.84±1.58)%、(36.83±1.36)%、(15.64±1.09)%,二者相比差异有统计学意义.结论 p21waf1基因转染能够抑制人乳腺癌细胞周期演进和增殖活性,进而阻止乳腺癌的发生、发展,为乳腺癌治疗的一种新手段.     

槲皮素通过调控p21/cip1和p27/kip1蛋白的稳定性抑制口腔鳞状细胞癌细胞增殖

目的:探究槲皮素通过调控p21/cip1和p27/kip1蛋白的稳定性对口腔鳞状细胞癌细胞增殖的影响.方法:CCK-8试剂盒检测口腔鳞状细胞癌细胞(SCC-15)增殖情况;流式细胞术检测SCC-15细胞周期分布;Western blot检测CyclinD1/CDK复合体、p21/cip1、p27/kip1、p-GSK3...     

Artepillin C in Brazilian propolis induces G(0)/G(1) arrest via stimulation of Cip1/p21 expression in human colon cancer cells

Potential chemopreventive agents exist in foods. Artepillin C in Brazilian propolis was investigated for its effects on colon carcinogenesis. We had found that artepillin C was a bioavailable antioxidant, which could be incorporated into intestinal Caco-2 and hepatic HepG2 cells without any conjugation and inhibited the oxidation of intracellular DNA. Artepillin C was then added to human colon cancer WiDr cells. It dose-dependently inhibited cell growth, inducing G(0)/G(1) arrest. The events involved a decrease in the kinase activity of a complex of cyclin D/cyclin-dependent kinase 4 and in the levels of retinoblastoma protein phosphorylated at Ser 780 and 807/811. The inhibitors of the complex, Cip1/p21 and Kip1/p27, increased at the protein level. On the other hand, Northern blotting showed that artepillin C did not affect the expression of Kip1/p27 mRNA. According to the experiments using isogenic human colorectal carcinoma cell lines, artepillin C failed to induce G(0)/G(1) arrest in the Cip1/p21-deleted HCT116 cells, but not in the wild-type HCT116 cells. Artepillin C appears to prevent colon cancer through the induction of cell-cycle arrest by stimulating the expression of Cip1/p21 and to be a useful chemopreventing factor in colon carcinogenesis.     

冷休克对 PG、HeLa细胞周期调控及p21WAF1/cip1蛋白表达的影响

目的　研究冷休克对p5 3基因突变的PG细胞、p5 3野生型的HeLa细胞的周期调控及 p2 1WAF1/cip1蛋白表达的影响。方法　将PG、HeLa细胞置 4℃冷冻 4h ,使细胞发生冷休克 ,用流式细胞仪分析细胞DNA含量及凋亡细胞百分率 ,Westernblot检测 p2 1WAF/cip1蛋白的表达。 结果　冷休克诱导PG、HeLa细胞发生G2 /M期周期阻滞及凋亡 ,p2 1WAF/cip1蛋白表达增高 (PG以 12h、HeLa以 18h最为显著 )。冷休克诱导PG、HeLa细胞发生G2 /M期周期阻滞及凋亡与 p2 1WAF/cip1蛋白表达增高同步。结论　冷休克诱导PG、HeLa细胞发生G2 /M期阻滞及凋亡、p2 1WAF/cip1表达的增高与细胞的 p5 3状态无关。     

Expression of cyclins A and D and p21(waf1/cip1) proteins in renal cell cancer and their relation to clinicopathological variables and patient survival.

We have studied 118 renal cell carcinomas to analyse the expressions of cyclins A and D1 and p21(waf1/cip1), and their relationship to clinical and histopathological parameters as well as to clinical outcome. Cyclins A and D1 and cyclin-dependent kinase inhibitor p21 (waf1/cip1) were not expressed in normal renal tissue. Staining signals of cyclin D1 and p21(waf1/cip1) were always nuclear but cyclin A was also expressed in the cytoplasm of the tumour cells. The mean (range) fractions of cyclin A, cyclin D1 and p21(waf1/cip1)-positive tumour cells were 2.2% (range 0-20%), 23.3% (range 0-90%) and 6.8% (range 0-70%) respectively. The expression of cyclin A was related to venous invasion, high nuclear grade, high mitotic rate, high Ki-67 and high PCNA expressions (P < or = 0.006 for all). The expression of cyclin D1 was linked with age over 65 years, low nuclear grade and high p53 expression (P < or = 0.05 for all). An inverse correlation was present between p21(waf1/cip1) and cyclin D1 (P = 0.011). Cyclin A predicted survival in the entire study group (P = 0.0014), in T1-4/N0-2/M0 (P = 0.0007) and in T1-2/N0/M0 tumours (P = 0.0007). Cyclin A was also a powerful predictor of disease-free survival in T1-4/N0/M0 (P = 0.0027) tumours (P = 0.0007). Cyclin D1 and p21(waf1/cip1) were not significantly related to survival or disease-free survival in any of the groups. In the entire material the independent prognostic factors were the presence of distant metastases (relative risk (RR) 5.16, P < 0.001), T category (RR 2.68, P < 0.001), Ki-67 expression (RR 1.02, P = 0.026) and cyclin A expression (RR 1.12, P = 0.001). The independent predictors in T1-4/N0/M0 tumours were T-category (RR 2.67, P = 0.001) and cyclin A (RR 1.21, P < 0.001), and in T1-2/N0/M0 tumours the only significant predictor was cyclin A (RR 1.19, P = 0.0002). In renal cell carcinoma, cyclin A is a powerful and independent prognostic factor in all clinical stages of the disease, whereas cyclin D1 and p21(waf1/cip1) have no prognostic value.     

Molecular mechanisms of G0/G1 cell-cycle arrest and apoptosis induced by terfenadine in human cancer cells

Terfenadine (TF), a highly potent histamine H1 receptor antagonist, has been shown to exert no significant central nervous system side effects in clinically effective doses. In this study, we demonstrated that TF induced significant growth inhibition of human cancer cells, including Hep G2, HT 29, and COLO 205 cells, through induction of G(0)/G(1) phase cell-cycle arrest. The minimal dose of TF induced significant G(0)/G(1) arrest in these cells was 1-3 microM. The protein levels of p53, p21/Cip1, and p27/Kip1 were significantly elevated, whereas the kinase activities of cyclin-dependent kinase 2 (CDK2) and CDK4 were inhibited simultaneously in the TF-treated cells. On the other hand, significant apoptosis, but not G(0)/G(1) arrest, was induced in the HL 60 (p53-null) or Hep 3B (with deleted p53) cells when treated with TF (3-5 microM). To clarify the roles of p21/Cip1 and p27/Kip1 protein expression, which was involved in G(0)/G(1) arrest and apoptosis induced by TF in human cancer cells, antisense oligodeoxynucleotides (ODNs) specific to p21/Cip1 and p27/Kip1 were used, and the expression of the p21/Cip1 and p27/Kip1 were monitored by immunoblotting analysis. Our data demonstrated that the percentage of the apoptotic cells detected by annexin V/PI analysis in the TF-treated group was clearly attenuated by pretreatment with p27/Kip1-specific ODNs. These results indicated that p27/Kip1 (but not p21/Cip1) protein indeed played a critical role in the TF-induced apoptosis. We also demonstrated that the TF-induced G(0)/G(1) cell-cycle arrest effect was not reversed by TF removal, and this growth inhibition lasted for at least 7 d. Importantly, the occurrence of apoptosis and cell growth arrest was not observed in the TF-treated normal human fibroblast, even at a dose as high as 25 microM. Our study showed the molecular mechanisms for TF-induced cell growth inhibition and the occurrence of apoptosis in human cancer cells.     

A p21(waf1)-independent pathway for inhibitory phosphorylation of cyclin-dependent kinase p34(cdc2) and concomitant G(2)/M arrest by the chemopreventive flavonoid apigenin.

Apigenin, a nonmutagenic flavonoid, has been shown to inhibit ultraviolet light-induced skin tumorigenesis when topically applied to mouse skin. Our previous studies have shown that apigenin treatment of cultured mouse keratinocytes induces G(2)/M arrest accompanied by an increase in p53 protein stability and expression of p21(waf1). In this study, we determined whether the G(2)/M arrest induced by apigenin was dependent upon the presence of the cyclin dependent kinase inhibitor p21(waf1). We exposed WWT.8 (p21(waf1) wild-type) and WKO.16 (p21(waf1) null) mouse keratinocytes to various doses of apigenin for 24 h and observed G(2)/M arrest in both cell lines, thereby establishing that the apigenin-induced G(2)/M arrest was p21(waf1) independent. A 4-h treatment with apigenin induced increases in p53 protein level by sixfold and tenfold in the WWT.8 p21(waf1) wild-type cells and WKO.16 p21(waf1) null cells, respectively. After 24 h in WWT.8 cells, p21(waf1) protein also was induced in a dose-dependent manner, but it was not expressed in WKO.16 keratinocytes. We then measured the effect of apigenin treatment on the mammalian homologue of the yeast cdc2 gene (p34(cdc2)) cyclin-dependent kinase and cyclin B1 (cycB1), because these proteins complex to regulate G(2)/M progression. Apigenin treatment decreased the protein level of p34(cdc2), and p34(cdc2) kinase activity was inhibited in both p21(waf1)(+/+) and p21(waf1)(-/-) cell lines by approximately 40%. The inhibition of p34(cdc2) kinase activity by apigenin treatment correlated with increasing levels of p34(cdc2) phosphorylation at Tyr15, a site in the p34(cdc2) kinase that undergoes inhibitory phosphorylation by Wee1 kinase. Apigenin treatment also had no effect on the protein level or activity of the competing phosphatase, cdc25c, which dephosphorylates p34(cdc2) kinase at Tyr15. Apigenin had little effect on the accumulation of cycB1 protein. These results supported the conclusion that G(2)/M arrest induced by apigenin was accompanied by inhibition of the p34(cdc2) cyclin-dependent kinase protein level and activity in a p21(waf1)-independent manner.     

贝母素乙通过诱导G0/G1期阻滞抑制结肠癌细胞的增殖

目的：探讨贝母素乙对结肠癌HCT116细胞增殖的抑制作用及其分子机制。方法：利用不同浓度的贝母素乙处理人结肠癌细胞HCT116和正常结肠上皮细胞CCD841 CON,通过CCK-8法和结晶紫染色法检测贝母素乙对HCT116和CCD841CON细胞增殖活力的影响,流式细胞术和WB法检测贝母素乙对HCT116细胞周期及其细胞周期相关蛋白表达的影响。构建HCT116移植瘤裸鼠模型和AOM/DSS结肠癌小鼠模型,观察贝母素乙对小鼠模型肿瘤生长和OS的影响,免疫组化法和WB法检测对移植瘤或肿瘤组织中细胞周期相关蛋白CDK4、CDK6和cyclin D1表达的影响。结果：贝母素乙可显著抑制结肠癌HCT116细胞的增殖能力（P<0.01）,诱导HCT116细胞周期G0/G1期阻滞（P<0.01）,降低CDK4、CDK6和cyclin D1的蛋白表达水平（均P<0.01）。荷瘤小鼠实验结果显示,贝母素乙（0.75 mg/kg）显著抑制HCT116细胞移植瘤的生长并延长荷瘤裸鼠的OS(P<0.05或P<0.01),降低AOM/DSS模型小鼠的体质量、延长OS、减少癌变肠组织...     

Relative non-steroidal anti-inflammatory drug (NSAID) antiproliferative activity is mediated through p21-induced G1 arrest and E2F inhibition

This study was performed to compare the relative antineoplastic activity of 10 different non-steroidal anti-inflammatory drugs (NSAIDs) in clinical use, and to investigate the underlying mechanisms of this activity in a squamous cell carcinoma of the head and neck model (SCCHN). A standard 5-day MTT assay was used to calculate IC(50) values in UM-SCC-1 cells for 10 NSAIDs, including celecoxib, rofecoxib, sulindac sulfide, sulindac sulfone, indomethacin, ketoprofen, flurbiprofen, naproxen, piroxicam, and aspirin. Celecoxib, a COX-2 specific inhibitor, was by far the most potent NSAID, with an IC(50) of 39.9 +/- 1.1 microM, followed by sulindac sulfide (116.5 +/- 2.34 microM). Celecoxib and sulindac sulfide also induced more activation of caspase-3 than any other NSAID. Cell cycle analysis showed that celecoxib and sulindac sulfide both induced a 3-fold increase in G(1) phase distribution, and this correlated with strong induction of p21(waf1/cip1), inhibition of cyclin D1, and hypophosphorylation of Rb. Celecoxib and sulindac sulfide treatment induced strong downstream inhibition of E2F transactivating activity as determined by a luciferase reporter assay. These data demonstrate the wide range of activity of various NSAID agents, and reveal a mechanism of action through cell cycle inhibition and induction of apoptosis.     

Widdrol induces cell cycle arrest,associated with MCM down-regulation,in human colon adenocarcinoma cells

Widdrol, an odorous compound extracted from Juniperus chinensis, has been shown to inhibit the in vitro growth of in human cancer cells. This study was conducted on cultured human colon adenocarcinoma HT29 cells to elucidate the possible mechanisms by which widdrol exerts its anti-proliferative activity, which until now has remained poorly understood. It was found that widdrol induces accumulation of sub-G1 phase and arrests in the G1 phase of the cell cycle. Induction of G1 arrest by widdrol was correlated with induction of Chk2, p53 phosphorylation and CDK inhibitor p21 expression as well as inhibition of cyclin E, cyclin-dependent kinase (CDK2) and retinoblastoma protein (pRB). Moreover, mini-chromosome maintenance (MCM) proteins were markedly down-regulated in HT29 cells treated with widdrol. Altogether, these results show widdrol possesses potential anti-cancer activity against colon adenocarcinoma cells by inhibiting their proliferation and inducing cell cycle G1 arrest.     

p53-independent G1 cell cycle arrest of human colon carcinoma cells HT-29 by sulforaphane is associated with induction of p21CIP1 and inhibition of expression of cyclin D1

Isothiocyanate sulforaphane (SFN) is a potent cancer chemopreventive agent. We investigated the mechanisms underlying the anti-proliferative effects of SFN in the human colon carcinoma cell line, HT-29. We demonstrate that SFN inhibits the growth of HT-29 cells in a dose- and time-dependent manner. Treatment of serum-stimulated HT-29 cells with SFN suppressed the re-initiation of cell cycle by inducing a G₁ phase cell cycle arrest. At high doses (>25 μM), SFN dramatically induces the expression of p21^CIP1 while significantly inhibits the expression of the G₁ phase cell cycle regulatory genes such as cyclin D1, cyclin A, and c-myc. This regulation can be detected at both the mRNA and protein levels as early as 4 h post-treatment of SFN at 50 μM. Additionally, SFN activates MAPKs pathways, including ERK, JNK and p38. Exposure of HT-29 cells with both SFN and an antioxidant, either NAC or GSH, completely blocked the SFN-mediated activation of these MAPK signaling cascades, regulation of cyclin D1and p21^CIP1 gene expression, and G₁phase cell cycle arrest. This finding suggests that SFN-induced oxidative stress plays a role in these observed effects. Furthermore, the activation of the ERK and p38 pathways by SFN is involved in the upregulation of p21^CIP1 and cyclin D1, whereas the activation of the JNK pathway plays a contradictory role and may be partially involved in the downregulation of cyclin D1. Because cyclin D1 and p21^CIP1 play opposing roles in G₁ phase cell cycle progression regulation, blocking the activation of each MAPK pathway with specific MAPK inhibitors, is unable to rescue the SFN-induced G₁ phase cell cycle arrest in HT-29 cells.     

N-myc downstream regulated gene1/Cap43 overexpression suppresses tumor growth by hepatic cancer cells through cell cycle arrest at the G0/G1 phase

N-myc downstream regulated gene-1 (NDRG1)/Cap43 regulates tumor growth and metastasis in various carcinomas. In this study we examined whether and how NDRG1/Cap43 modulates tumor growth by human hepatocellular carcinoma (HCC) cells. NDRG1/Cap43 cDNA was used to transfect HCC cell lines (KIM-1), and stable transfectants overexpressing NDRG1/Cap43 (KIM-1/Cap43) were obtained. Cell cycle analysis showed that KIM-1/Cap43 cells were arrested in the G0/G1 phase. Western blot analysis demonstrated an increase in p21 in KIM-1/Cap43 cells in culture under full confluency as compared with KIM-1/Mock. When KIM-1 cells, which are very low in NDRG1/Cap43 expression, were treated with mimosine, a G0/G1 cell cycle blocker, expression of NDRG1/Cap43 was induced in a dose dependent manner, together with p21 induction and CDK4 reduction. In vivo, KIM-1/Cap43 cells showed markedly decreased tumor growth rates compared with those of KIM-1/Mock. Immunohistochemical staining demonstrated markedly higher p21 labeling index in the KIM-1/Cap43 tumor than KIM-1/Mock tumor, and lower CDK4 and Ki-67 labeling index in the KIM-1/Cap43 than KIM-1/Mock. In order to confirm suppressive effects of NDRG1/Cap43, we further established a stable transfectant expressing NDRG1/Cap43 (HAK-1B/Cap43) using another HCC cell line, HAK-1B. Western blot analysis demonstrated an increase in p21 and a decrease in CDK4 in HAK-1B/Cap43 cells in culture under full confluency as compared with HAK-1B/Mock. HAK-1B/Cap43 also showed decreased tumor growth rates as compared with its control counterpart in vivo. NDRG1/Cap43 overexpression thus induced cell cycle arrest at the G0/G1 phase accompanied by increased p21 and decreased CDK4 expression in HCC cells. NDRG1/Cap43 might play a key role in the cell cycle control of G0/G1 in HCC cells.     

In vitro and in vivo studies of the anticancer action of terbinafine in human cancer cell lines: G0/G1 p53-associated cell cycle arrest

Terbinafine (TB) (Lamisil), a promising oral antifungal agent used worldwide, has been used in the treatment of superficial mycosis. In our study, we demonstrated that TB dose-dependently decreased cell number in various cultured human malignant cells. Flow cytometry analysis revealed that TB interrupts the cell cycle at the G0/G1 transition. The TB-induced cell cycle arrest in colon cancer cell line (COLO 205) occurred when the cyclin-dependent kinase (cdk) system was inhibited just as the levels of p53, p21/Cip1 and p27/Kip1 proteins were augmented. In the TB-treated COLO 205, the binding between p53 protein and p53 consensus binding site in p21/Cip1 promoter DNA probe was increased. Pretreatment of COLO 205 with p53-specific antisense oligodeoxynucleotide decreased the TB-induced elevations of p53 and p21/Cip1 proteins, which in turn led to arrest in the cell cycle at the G0/G1 phase. Moreover, in the p53 null cells, HL60, TB treatment did not induce cell cycle arrest. Taken together, these results suggest an involvement of the p53-associated signaling pathway in the TB-induced antiproliferation in COLO 205. We further examined whether administration of TB could affect the growth of tumors derived from human colon cancer cells in an in vivo setting. COLO 205 cells implanted subcutaneously in nude mice formed solid tumor; subsequent intraperitoneal injections of TB (50 mg/kg) led to obvious decline in tumor size, up to 50-60%. In these tumors, increases in the p21/Cip1, p27/Kip1 and p53 proteins and the occurrence of apoptosis were observed. Combined treatment with TB and nocodazole (ND), a clinically used anticancer agent, potentiated the apoptotic effect in COLO 205. These findings demonstrate for the first time that TB can inhibit the proliferation of tumor cells in vitro and in vivo.     

siRNA-mediated silencing of Notch-1 enhances docetaxel induced mitotic arrest and apoptosis in prostate cancer cells

Purpose: Notch is an important signaling pathway that regulates cell fate, stem cell maintenance and theinitiation of differentiation in many tissues. It has been reported that activation of Notch-1 contributes totumorigenesis. However, whether Notch signaling might have a role in chemoresistance of prostate cancer isunclear. This study aimed to investigate the effects of Notch-1 silencing on the sensitivity of prostate cancercells to docetaxel treatment. Methods: siRNA against Notch-1 was transfected into PC-3 prostate cancer cells.Proliferation, apoptosis and cell cycle distribution were examined in the presence or absence of docetaxel byMTT and flow cytometry. Expression of p21waf1/cip1 and Akt as well as activation of Akt in PC-3 cells were detectedby Western blot and Real-time PCR. Results: Silencing of Notch-1 promoted docetaxel induced cell growthinhibition, apoptosis and cell cycle arrest in PC-3 cells. In addition, these effects were associated with increasedp21waf1/cip1 expression and decreased Akt expression and activation in PC-3 cells. Conclusion: Notch-1 promoteschemoresistance of prostate cancer and could be a potential therapeutic target.     

胃癌细胞周期不同时相MTS1/p16、p21、p53的表达

进一步明明确不同周期时相肿瘤细胞Ｐ１６基因的表达水平及在细胞周期调控中的作用。方法改进并建立了一个高同步率,高收获率的细胞周期同步化的方法,通过此方法把细胞同步在不同的时期,对ＲＮＡ及蛋白的表达进行研究,确定地不同同量丰中Ｐ１６的表达有何变化,同时分析其它几个重要的抑癌基因如Ｐ５３、Ｐ２１,研究它们在细胞周期中的表达以及与Ｐ１６基因相经关系。结果确定在不同周期时相的胃癌细胞系ＭＧｃ８０－３Ｇ