人乳腺癌细胞株WAF1／GIP1／p21基因的表达及其与细胞生物学特性的关系

OBJECTIVE: To study the WAF1/CIP1 gene DNA status, mRNA and protein expressions in human breast cancer cell line and its significance. METHODS: Using cell culture, molecular biological techniques such as Southern blot, Northern blot and immunocytochemical methods, the WAF1/CIP1 gene DNA status, mRNA and protein expression levels in MCF-7 expressing wild type p53(wtp53) and MDA-MB-231 expressing mutant p53 (mtp53) human breast cancer cell lines were detected respectively. The p53 and mdm-2 protein expression levels and cytobiological features of the 2 cell lines were compared and correlated to their WAF1/CIP1 gene expression levels. RESULTS: (1) There was no difference in WAF1/CIP1 gene DNA status in the two breast cancer cell lines. Neither of them showed gene amplificatian or deletion. However, the WAF1/CIP1 mRNA and p21WAF1/CIP1 protein expression levels of MCF-7 cells were higer than those of MDA-MB-231 cells (P < 0.05). (2) The character and cellular distribution of p53 protein in the two cell lines were clearly different. The expression level of mdm-2 proteion was significantly higher in MCE-7 than in MDA-MB-231 cells (P < 0.05). (3) Compered to the other breast cancer cell line, MCF-7 cells were better differentiated, grew more slowly and adhered more closely with each other. CONCLUSION: The WAF1/CIP1 gene expression at mRNA and protein levels is associated with p53 phenotype and some cytobiological features of human breast cancer.     

AMPK Activation of Apoptotic Markers in Human Breast Cancer Cell Lines with Different p53 Backgrounds: MCF-7, MDA-MB-231 and T47D Cells

Background: Downregulation of AMPK has been established as a major contributor to carcinogenesis in many types of human cancer. We sought to investigate the influence of activated AMPK on apoptotic markers in human breast cancer cells differing in their p53 status, as well as estrogen receptor status (MCF-7 (p53+ and ER+), MDA-MB-231 (p53 mutant and ER-) and T47D (p53 mutant and ER+)). Methods: We examined the effect of AICAR-activated AMPK on PARP cleavage, Bax redistribution, the involvement of intrinsic and extrinsic pathways of apoptosis using selective caspase inhibitors and cell cycle progression and p21 levels. Results: PARP cleavage occurred to a greater extent in MCF-7 and MDA-MB-231 cells, whereas Bax translocation was slower in MDA-MB-231 cells. Although there were quantitative differences in the effect of caspase inhibitors, it was clear that AMPK activation predominately affected the intrinsic pathway of apoptosis. Although, p21 was increased in all 3 cell types, there were quantitative and time differences. Apoptosis, as measured by fluorimetry, was increased in all three cell types. Conclusion: The impact of AMPK activation was cell type dependent resulting in differential activation of apoptotic markers, confirming that the genetic background of breast cancer may have an influence on the mode of action of AMPK. Thus, different anti-tumour mechanisms may be elicited depending on the cellular genotype.     

Novel bile acid derivatives induce apoptosis via a p53-independent pathway in human breast carcinoma cells

We have compared the anti-proliferative effects of ursodeoxycholic acid (UDCA), chenodeoxycholic acid (CDCA) and their derivatives, HS-1183, HS-1199 and HS-1200, on MCF-7 (wild-type p53) and MDA-MB-231 (mutant p53) cells. While UDCA and CDCA exhibited no significant effect, their novel derivatives inhibited the proliferation of both cell lines in a concentration-dependent manner, concomitant with apoptotic nuclear changes and the increase of a sub-G1 population and DNA fragmentation. Furthermore, we also observed an increase in the ratio of pro-apoptotic protein Bax to anti-apoptotic protein Bcl-2 and cleavages of lamin B and poly(ADP-ribose) polymerase (PARP) in MCF-7 and MDA-MB-231 cells. Cell cycle related proteins, cyclin D1 and D3, as well as retinoblastoma protein (pRb) were down-regulated, while the level of cyclin-dependent kinase inhibitor p21(WAF1/CIP1) was increased in both cancer cells after treatment with novel bile acids. These findings suggest that these cytotoxic effects of novel bile acid derivatives on human breast carcinoma cells were mediated via apoptosis through a p53-independent pathway.     

Induction of apoptosis in breast cancer cells MDA-MB-231 by genistein.

Breast cancer is the most common cancer among American women, whereas Asian women, who consume a traditional diet high in soy products, have a relatively low incidence. Genistein is a prominent isoflavonoid in soy products and has been proposed as the agent responsible for lowering the rate of breast cancer in Asian women. We investigated the effects of genistein on cell growth and apoptosis-related gene expression in breast cancer cells MDA-MB-231. We found up-regulation of Bax and p21WAF1 expressions and down-regulation of Bcl-2 and p53 expression in genistein-treated cells. Furthermore, DNA ladder formation, CPP32 activation, and PARP cleavage were observed after treatment with genistein, indicating apoptotic cell deaths. Flow cytometry with 7-amino actinomycin D staining showed that the number of apoptotic cells increased with longer treatment of genistein. From these results, we conclude that genistein inhibits the growth of MDA-MB-231 breast cancer cells, regulates the expression of apoptosis-related genes, and induces apoptosis through a p53-independent pathway. The up-regulation of Bax and p21WAF1 may be the molecular mechanisms by which genistein induces apoptosis, however, further definitive studies are needed. These results suggest that genistein may be a potentially effective chemopreventive or therapeutic agent against breast cancer.     

人乳腺癌细胞株WAF1/CIP1/p21基因的表达及其与细胞生物学特性的关系

目的研究人乳腺癌细胞株ＷＡＦ１／ＣＩＰ１基因的ＤＮＡ状况、ｍＲＮＡ和蛋白的表达水平及其意义。方法应用细胞培养、分子生物学Ｓｏｕｔｈｅｒｎｂｌｏｔ和Ｎｏｒｔｈｅｒｎｂｌｏｔ杂交以及免疫组化染色等技术，检测人乳腺癌表达野生型ｐ５３（ｗｔｐ５３）的ＭＣＦ７细胞和表达突变型ｐ５３（ｍｔｐ５３）的ＭＤＡＭＢ２３１细胞中ＷＡＦ１／ＣＩＰ１基因ＤＮＡ状况、ｍＲＮＡ和蛋白质的表达水平，研究其与ｍｄｍ２、ｐ５３蛋白的表达和细胞生物学特性的关系。结果比较ＭＣＦ７细胞与ＭＤＡＭＢ２３１细胞：（１）两者ＷＡＦ１／ＣＩＰ１基因ＤＮＡ状况无明显差异，前者ｍＲＮＡ和蛋白质的表达水平明显高于后者（Ｐ＜０．０５）；（２）两者ｐ５３蛋白的性质和分布不同，前者ｍｄｍ２蛋白的表达水平明显高于后者（Ｐ＜０．０５）；（３）前者生物学特性好于后者。结论人乳腺癌细胞株ＷＡＦ１／ＣＩＰ１基因ｍＲＮＡ和蛋白质的表达水平与ｐ５３基因表型和细胞生物学特性有关。     

TPA-induced p21 expression augments G2/M arrest through a p53-independent mechanism in human breast cancer cells

The tumor promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA), has a differential role on the regulation of the cell cycle in a variety of tumor cells. The mechanism between TPA and the cell cycle in breast cancer is not fully understood. Therefore, we investigated the regulatory mechanism of TPA on control of the cell cycle of breast cancer cells. Our results showed that TPA increased the level of p21 expression in MCF-7 cells with wild-type p53 and MDA-MB-231 cells with mutant p53 in a dose-dependent manner. In contrast, TPA decreased the expression of p53 in MCF-7 cells, but did not affect MDA-MB-231 cells. We next examined the regulatory mechanism of TPA on p21 and p53 expression. Our results showed that the TPA-induced up-regulation of p21 and down-regulation of p53 was reversed by UO126 (a MEK1/2 inhibitor), but not by SP600125 (a JNK inhibitor) or SB203580 (a p38 inhibitor), although TPA increased the phosphorylation of ERK and JNK in MCF-7 cells. In addition, the TPA-induced arrest of the G2/M phase was also recovered by UO126 treatment. To confirm the expression of p21 through the MEK/ERK pathway, cells were transfected with constitutively active (CA)-MEK adenovirus. Our results showed that the expression of p21 was significantly increased by CA-MEK overexpression. Taken together, we suggest that TPA reciprocally regulates the level of p21 and p53 expression via a MEK/ERK-dependent pathway. The up-regulation of p21 in response to TPA is mediated through a p53-independent mechanism in breast cancer cells.     

Differential anti-tumor activity of coriolus versicolor (Yunzhi) extract through p53- and/or Bcl-2-dependent apoptotic pathway in human breast cancer cells

Coriolus versicolor (CV), also called Yunzhi, has been demonstrated to exert anti-tumor effects on various types of cancer cells, but the underlying mechanism has not been fully elucidated. The present study aimed to evaluate the in vitro anti-tumor activity of a standardized aqueous ethanol extract prepared from CV on four breast cancer cell lines using MTT assay, and test whether the mechanism involves apoptosis induction and modulation of p53 and Bcl-2 protein expressions using cell death detection ELISA, p53 and Bcl-2 ELISAs respectively. Our results demonstrated that the CV extract dose-dependently suppressed the proliferation of three breast tumor cell lines, with ascending order of IC50 values: T-47D, MCF-7, MDA-MB-231, while BT-20 cells were not significantly affected. Tumoricidal activity of the CV extract was found to be comparable to a chemotherapeutic anti-cancer drug, mitomycin C. Nucleosome productions in apoptotic MDA-MB-231, MCF-7 and T-47D cells were significantly augmented in a time-dependent manner and paralleled the anti-proliferative activity of CV extract. Expression of p53 protein was significantly upregulated only in T-47D cells treated with the CV extract in a dose- and time-dependent fashion, but not in MCF-7 (except at 400 mug/ml after 16 h) and MDA-MB-231 cells. The CV extract significantly induced a dose-dependent downregulation of Bcl-2 protein expression in MCF-7 and T-47D cells, but not in MDA-MB-231 cells. These results suggested that apoptosis induction, differentially dependent of p53 and Bcl-2 expressions, might be the possible mechanism of CV extract-mediated cytotoxicity in human breast cancer cells in vitro.     

International cancer research grants

Ahderrant cyclin expression has been implicated in oncogenesis in a number of human cancers. Since alterehd function of regulators of cyclin-dependent kinase (CDK) activity other than cyclins, in particular CDK inhibitors, might play a similar role in oncogenesis, we examined the expression and regulation of the CDK inhibitors p16^INk4 p15^INK4B and p21^WAF1/CIP1 in human breast cancer cell lines. Both the INK4 and INK4B genes were homozygously deleted in 3 cell lines, while INK4 alone was deleted in 2 cell lines. A further 2 cell lines displayed loss of an allele at this locus, and in 1 of these the remaining allele contained a mis-sense mutation within the coding region of the p16^INK4 protein. The majority of cell lines examined, including 2 normal mammary epithelial cell strains, expressed low levels of INK4 mRNA and low or undetectable levels of INK4B mRNA. However, INK4 mRNA was expressed at high levels in 5 cell lines, and this was associated with deletion or inactivation of the retinoblastoma susceptibility gene product pRB but not with mutation of TP53. No deletions of the WAF1/CIP1 gene were observed, but WAF1/CIP1 mRNA levels were reduced in cell lines with TP53 mutation. Transfection of a p16^INK4 expression vector into MDA-MB-231 cells lacking the INK4 gene failed to produce any p16^INK4-expressing cell lines, suggesting that such cells were selected against in continuous culture. Despite the frequent deletion of INK4 in breast cancer cell lines, no evidence was obtained for INK4 deletions in DNA from 45 primary breast carcinomas. Thus, homozygous deletion of the INK4 gene appears to be a rare event in primary breast cancer.     

Zerumbone causes Bax- and Bak-mediated apoptosis in human breast cancer cells and inhibits orthotopic xenograft growth in vivo

The present study was undertaken to determine the anticancer efficacy of zerumbone (ZER), a sesquiterpene from subtropical ginger, against human breast cancer cells in vitro and in vivo. ZER treatment caused a dose-dependent decrease in viability of MCF-7 and MDA-MB-231 human breast cancer cells in association with G₂/M phase cell cycle arrest and apoptosis induction. ZER-mediated cell cycle arrest was associated with downregulation of cyclin B1, cyclin-dependent kinase 1, Cdc25C, and Cdc25B. Even though ZER treatment caused stabilization of p53 and induction of PUMA, these proteins were dispensable for ZER-induced cell cycle arrest and/or apoptosis. Exposure of MDA-MB-231 and MCF-7 cells to ZER resulted in downregulation of Bcl-2 but its ectopic expression failed to confer protection against ZER-induced apoptosis. On the other hand, the SV40 immortalized mouse embryonic fibroblasts derived from Bax and Bak double knockout mice were significantly more resistant to ZER-induced apoptosis. ZER-treated MDA-MB-231 and MCF-7 cells exhibited a robust activation of both Bax and Bak. In vivo growth of orthotopic MDA-MB-231 xenografts was significantly retarded by ZER administration in association with apoptosis induction and suppression of cell proliferation (Ki-67 expression). These results indicate that ZER causes G₂/M phase cell cycle arrest and Bax/Bak-mediated apoptosis in human breast cancer cells, and retards growth of MDA-MB-231 xenografts in vivo.     

Potent in vivo anti-breast cancer activity of IN-2001, a novel inhibitor of histone deacetylase, in MMTV/c-Neu mice

A novel synthetic inhibitor of histone deacetylase (HDAC), 3-(4-dimethylaminophenyl)-N-hydroxy-2-propenamide (IN-2001), was examined for its antitumor activity and for the underlying molecular mechanisms of any such activity. IN-2001 effectively inhibited cellular HDAC activity (IC(50), 5.42 nmol/L) in MCF-7 human breast cancer cells. Based on the Western blot analysis, this HDAC inhibitory effect of IN-2001 was confirmed by an increase in histone H4 acetylation from the IN-2001-treated breast cancer cells. IN-2001 suppressed mammary tumor growth in MMTV/c-Neu transgenic mice and also showed higher apoptotic index and lower lymphatic invasion compared with controls. In human breast cancer cells (MCF-7, T47D, MDA-MB-231, and MDA-MB-468), IN-2001 induced cell cycle arrest at G(2)-M phase through up-regulation of p21(WAF1) and p27(KIP1) and eventually caused apoptosis. IN-2001-induced apoptosis was caspase dependent and seems mediated through an increase in Bax/Bcl-2 ratio. Taken together, our data indicate that this novel HDAC inhibitor is a promising therapeutic agent against human breast cancer.     

Quinacrine has anticancer activity in breast cancer cells through inhibition of topoisomerase activity

The small molecule Quinacrine (QC, a derivative of 9-aminoacridine), an anti-malaria drug, displays activity against cancer cell lines and can simultaneously suppress nuclear factor-κB (NF-κB) and activate p53 signaling. In this study, we investigated the anticancer mechanism underlying these drug activities in breast cancer cell lines. QC caused a dose-dependent decrease of both anchorage dependent and independent growth of breast cancer cells (MCF-7 and MDA-MB-231) without affecting normal breast epithelial cells (MCF-10A), as evident from clonogenic cell survival, [3-(4,5-dimethylthiazol-2yl-)-2,5-diphenyl tetrazolium bromide] viability, wound healing and soft agar growth. QC activated the proapoptotic marker Bax, PARP cleavage, p53 and its downstream target, p21 (Cip1/Waf1) and downregulated the antiapoptotic marker Bcl-xL and relative luciferase activity of NF-κB in MCF-7 cells. Results of DAPI nuclear staining and FACS analysis show that QC increased apoptosis in a dose-dependent manner. QC caused apoptosis by increasing the cell population in S-phase and simultaneously decreasing the G1 and G2/M populations. A dose-dependent increase of DNA damage as measured by the comet assay was seen in MCF-7 cells after exposure to QC. With regards to the mechanism of DNA damage, we found that QC inhibited topoisomerase activity in MCF-7 cells by increasing the unwinding of supercoiled DNA. Collectively, the results demonstrate that QC has efficient anticancer potential against breast cancer cells via not only an induction of p53 and p21 but also an induction of S phase arrest, DNA damage and inhibition of topoisomerase activity.     

Differential sensitivity of normal and malignant breast epithelial cells to genistein is partly mediated by p21(WAF1).

Genistein, a soy metabolite, is a potential chemopreventive agent against various types of cancer. There are several studies documenting molecular alterations leading to cell cycle arrest and induction of apoptosis in a variety of cancer cells; however, no studies, to date, have shown the effect of genistein in isogenic normal and malignant breast epithelial cells. In this study, we investigated whether genistein shows any differential sensitivity to normal (MCF10A and MCF12A) and malignant (MCF10CA1a and MDA-MB-231) breast epithelial cells. We found that genistein causes a greater degree of G(2)-M arrest and induces apoptosis in malignant cell lines compared with normal breast epithelial cells. After genistein treatment, flow cytometric analysis revealed a hyperdiploid population in malignant cells that was not observed in normal cells. Cell cycle regulator p21(WAF1), which is known to be up-regulated by genistein treatment, was greatly induced at RNA and protein levels in normal cells, whereas its level was only slightly induced in malignant MDA-MB-231 cells and not detectable in malignant MCF10CA1a cells. Therefore, we investigated the causal role of p21(WAF1) in the differential sensitivity of genistein among these cell lines. We examined the effects of genistein on p21(WAF1) -/- and p21(WAF1) +/+ HCT116 cells, which were used as controls prior to studies on breast cancer cells. We found that there was a greater degree of cell cycle arrest and apoptosis in p21(WAF1) -/- cells compared with p21(WAF1) +/+ HCT116 cells after genistein treatment. Flow cytometric analysis after genistein treatment showed a significant number of p21(WAF1) -/- cells in the hyperdiploid population, which are probably programmed to die through apoptotic processes. To further confirm the causal role of p21(WAF1) in genistein-mediated cell cycle arrest and apoptosis, we down-regulated p21(WAF1) by antisense p21(WAF1) cDNA transfection experiments. We found that both normal and malignant p21(WAF1) antisense (AS)-expressing clones became more sensitive to G(2)-M arrest after genistein treatment. Flow cytometric analysis showed an increase in the hyperdiploid population in the AS clones. Further evaluation showed an increase in apoptosis in malignant AS clones but not in normal breast epithelial AS clones. These results suggest that p21(WAF1) may play an important role in determining the sensitivity of normal and malignant breast epithelial cells to genistein.     

Involvement of p53 in insulin-like growth factor binding protein-3 regulation in the breast cancer cell response to DNA damage

Chemotherapy drugs that induce apoptosis by causing DNA double-strand breaks, upregulate the tumor suppressor p53. This study investigated the regulation of the growth-regulatory protein insulin-like growth factor binding protein-3 (IGFBP-3), a p53 target, by DNA-damaging agents in breast cancer cells. IGFBP-3 was upregulated 1.4- to 13-fold in response to doxorubicin and etoposide in MCF-10A, Hs578T, MCF-7 and T47D cells, which express low to moderate basal levels of IGFBP-3. In contrast, IGFBP-3 was strongly downregulated by these agents in cells with high basal levels of IGFBP-3 (MDA-MB-231, MDA-MB-436 and MDA-MB-468). In MDA-MB-468 cells containing the R273H p53 mutation, reported to display gain-of-function properties, chemotherapy-induced suppression of IGFBP-3 was not reversed by the p53 reactivating drug, PRIMA-1, or by p53 silencing, suggesting that the decrease in IGFBP-3 following DNA damage is not a mutant p53 gain-of-function response. SiRNA-mediated downregulation of endogenous IGFBP-3 modestly attenuated doxorubicin-induced apoptosis in MDA-MB-468 and Hs578T cells. IGFBP-3 downregulation in some breast cancer cell lines in response to DNA-damaging chemotherapy may have clinical implications because suppression of IGFBP-3 may modulate the apoptotic response. These observations provide further evidence that endogenous IGFBP-3 plays a role in breast cancer cell responsiveness to DNA damaging therapy.     

miR-4728-3p通过PI3K/AKT信号通路调控DOT1L基因抑制乳腺癌细胞增殖、侵袭和迁移

目的:探讨miR-4728-3p通过调控类端粒沉默干扰体-1(disruptor of telomeric silencing 1-like,DOT1L)基因对乳腺癌细胞增殖、侵袭和迁移的影响。方法:使用乳腺癌细胞MCF-7、MDA-MB-231及人正常乳腺细胞MCF-10A。转染MCF-7和MDA-MB-231细胞随机分为NC组(转染miR-4728-3p-NC)和敲低组(转染miR-4728-3p-inhibitor)。利用RT-qPCR技术检测不同的细胞中miR-4728-3p和DOT1L的表达量改变情况。集落克隆形成实验和EDU实验可以同时检测体内各个细胞异常增殖的情况;TUNEL荧光标记检测法和流式细胞术实验可以同时检测不同组癌细胞的凋亡变化;划痕实验和Transwell实验可以同时检测到在各个细胞内因不同处理而可能产生的细胞迁移率和侵袭力的改变;Western blot检测与细胞凋亡状态相关细胞蛋白以及与细胞通路凋亡相关细胞蛋白p-AKT和p-PI3K相对表达的含量。结果:在乳腺癌细胞MCF-7、MDA-MB-231以及SKBR3中发现miR-4728-3p和DOT1L的表达高于人正常乳腺细胞MCF-10A(P＜0.05)。转染细胞miR-4728-3p后,与NC组细胞进行实验比较,发现敲低组细胞中miR-4728-3p和DOT1L的表达量明显降低,且敲低组细胞的增殖能力明显减弱,细胞凋亡率明显升高,细胞迁移能力大大降低。敲低组的细胞凋亡活性蛋白相对表达明显发生变化。其中p-AKT与p-PI3K蛋白均被抑制激活。RT-qPCR和Western blot实验验证DOT1L是miR-4728-3p的下游靶向基因。结论:敲低miR-4728-3p可以下调DOT1L的表达从而促进乳腺癌细胞凋亡,抑制乳腺癌细胞增殖,同时使乳腺癌细胞侵袭和迁移能力减弱。     

Transfer of p14ARF gene in drug-resistant human breast cancer MCF-7/Adr cells inhibits proliferation and reduces doxorubicin resistance

The INK4a/ARF locus on human chromosome 9p21 encodes two tumor suppressors, p16INK4a and p14ARF, that restrain cell growth by affecting the functions of the retinoblastoma protein and p53, respectively. Overexpression of ARF results in cell cycle arrest in both G1 and G2. To elucidate the effect of p14ARF gene on multidrug-resistant tumor cells, we transferred a p14ARF cDNA into p53-mutated MCF-7/Adr human breast cancer cells. In this report we demonstrated for the first time that p14ARF expression was able to greatly inhibit the MCF-7/Adr cell proliferation. Furthermore, p14ARF expression resulted in decrease of MDR-1 mRNA and P-glycoprotein production, which linked to the reducing resistance of MCF-7/Adr cells to doxorubicin. These results imply that drug resistance might be effectively reversed by the wild-type p14ARF expression in human breast cancer cells.     

miRNA-34a抑制乳腺癌细胞MCF-7、MDA-MB-231的增殖与侵袭

目的:研究miRNA-34a(miR-34a)对乳腺癌细胞MCF-7、MDA-MB-231的生物调控作用。方法:采用定量PCR检测人乳腺上皮细胞MCF-10A,乳腺癌细胞株MCF-7、T47D、MDA-MB-231、MDA-MB-453、Hs578T中miR-34a的表达水平。通过miR-34a mimics分别上调MCF-7、MDA-MB-231细胞中miR-34a的表达水平,MTT和Transwell检测肿瘤细胞增殖能力、侵袭力等生物学行为的变化。结果:乳腺癌细胞MCF-7、T47D、MDA-MB-231、MDA-MB-453、Hs578T中miR-34a处于低表达水平。通过miR-34a mimics上调MCF-7、MDA-MB-231细胞中miR-34a的表达后,细胞的增殖能力被miR-34a抑制（P＜0.05）,miR-34a对细胞侵袭有显著抑制作用（P＜0.05）。结论:miR－34a在乳腺癌细胞MCF-7、T47D、MDA-MB-231、MDA-MB-453及Hs578T中低表达,miR-34a抑制乳腺癌细胞MCF-7、MDA-MB-231的细胞增殖和侵袭能力。     

genistein多途径抑制乳腺癌细胞生长和侵袭

目的 研究ｇｅｎｉｓｔｅｉｎ在乳腺癌细胞生长和侵袭中的作用。方法 应用体外细胞培养和体内乳腺癌细胞移植裸鼠模型以及酶谱分析、Ｎｏｒｔｈｅｎ和Ｗｅｓｔｅｒｎ ｂｌｏｔ方法。结果 在体外实验中,ｇｅｎｉｓｔｅｉｎ不仅具有抑制乳腺癌细胞生长的作用,还具有抑制乳腺癌细胞侵袭的功能,这种抑制功能是伴ｇｅｎｉｓｔｅｉｎ能明显抑制蛋白金属酶ＭＭＰ－９的表达和增加组织金属蛋白酶抑制剂ＴＩＭＰ１的表达。ｇｅｎｉｓｔ     

Sensitization of human breast cancer cells to gemcitabine by the protein kinase C modulator bryostatin 1

PURPOSE: Protein kinase C (PKC) plays an important role in cell proliferation, differentiation, and apoptosis. The interaction between the PKC modulator bryostatin 1 (BRYO), and gemcitabine in human breast cancer MCF-7 and MDA-MB-231 cells and in the non-transformed MCF-10A human breast epithelial cells was investigated. METHODS: Immunoblotting was used to determine the expression of PKC isoenzymes and proteins involved in the cell cycle and apoptosis. MTT, ELISA and flow cytometry assays were used to determine cell survival. RESULTS: Treatment of cells with BRYO 200 n M resulted in a significant downregulation of cytoplasmic PKC in all three cell lines. However, the expression of membranous PKC was differentially affected in these cells. BRYO (1-200 n M) had no significant effects on cell viability in any of the cell lines. Nevertheless, BRYO significantly enhanced the antiproliferative and apoptotic effects of gemcitabine in the MCF-7 and MDA-MB-231 cells, but not in the MCF-10A cells. This was associated with significant reduction in the bcl-2/bax ratio. There was a significant upregulation of p53, p21(waf1), and p27 in MCF7 and MCF-10A cells treated with the combination of gemcitabine and BRYO compared to gemcitabine-treated cells. CONCLUSIONS: The potentiation of the effect of gemcitabine by BRYO was demonstrated in MCF-7 and MDA-MB-231 cells and was associated with a specific pattern of PKC modulation. Further investigation of the role of specific isoforms of PKC in the downstream molecular events of gemcitabine-induced cytotoxicity is warranted.