不同人结直肠肿瘤细胞系对常用抗肿瘤药物体外化疗敏感性的比较

 目的：观察5种常用抗肿瘤药物对这些人结直肠肿瘤细胞系的生长抑制作用,探讨5种常用抗肿瘤药物对11株人结直肠肿瘤细胞系的作用强度以及比较其体外敏感性,研究不同抗肿瘤药物对人结直肠癌细胞系HCT116和SW480热休克蛋白27（HSP27）和HSP70表达水平的影响。方法：采用CCK-8（Cell Counting Kit-8）法检测5种常用抗肿瘤药物分别对11株人结直肠肿瘤细胞系的生长抑制效应,计算50%抑制浓度（50% inhibitory concentration, IC50）及敏感指数,并比较不同人结直肠肿瘤细胞系对5种抗肿瘤药物的敏感性,Western blotting检测HSP27和HSP70蛋白表达水平。结果：11株人结直肠肿瘤细胞系对5-氟尿嘧啶(5-FU)和奥沙利铂(OHP)均比较敏感,没有明显耐药性;5株人结直肠肿瘤细胞系对丝裂霉素(MMC)敏感,6株中度敏感;除SW1116 外的10株人结直肠肿瘤细胞系都对多西紫杉醇(DXL)敏感,而SW1116细胞对DXL表现出明显耐药性;除LS174T和SW1116外的9株人结直肠肿瘤细胞系都对伊立替康(IFL)表现出中度敏感,LS174T细胞对IFL表现敏感,而SW1116细胞对IFL表现出明显耐药性。抗肿瘤药物作用于人结直肠癌细胞系HCT116和SW480使HSP27的表达上调,但HSP70的表达水平变化不明显。结论：LS174T是多药敏感细胞株,SW1116是多药耐药细胞株,5-FU和OHP为广谱抗结直肠肿瘤药物;化疗药物的敏感性及HSP27表达量检测对临床选择化疗药物具有一定的提示意义。     

非甾体类抗炎药对结肠癌细胞NAG-1 基因表达的诱导

研究非甾体类抗炎药(Non-steroidal anti-inflammatory drug,NSAID)对结肠癌细胞生长的影响及NSAID活化基因-1(NAG-1)的诱导作用。体外培养HT-29、SW480及LS174-T三种结肠癌细胞,分别加入不同浓度的aspirin、celecoxib及meloxicam作用于HT-29及SW480细胞,采用MTT法检测结肠癌细胞增殖;蛋白质印迹技术检测三种结肠癌细胞COX-2的表达;采用半定量RT-PCR技术分析NSAID对三种结肠癌细胞NAG-1基因表达的影响。aspirin、celecoxib及meloxicam均能有效抑制体外培养的HT-29、SW480结肠癌细胞生长,并具有良好的量-效关系。Western blot表明,HT-29细胞表达COX-2,而SW480细胞不表达COX-2。三种结肠癌细胞均表达NAG-1基因mRNA,其中LS174-T细胞NAG-1基础水平较低;NSAID能不同程度上调结肠癌细胞NAG-1基因表达。NSAID能有效抑制结肠癌细胞生长,这种作用可能部分通过诱导结肠癌细胞NAG-1基因表达实现,NAG-1基因表达不受肿瘤细胞是否表达COX-2的影响。     

Alterations in the cellular distribution of bcl-2, bcl-x and bax in the adult rat substantia nigra following striatal 6-hydroxydopamine lesions

The proteins of the bcl-2 family play an important role during apoptosis and may also regulate cell death in response to oxidative stress, which has been implicated in Parkinson's disease. In this study we examined the localization of the pro-apoptotic protein bax, and the anti-apoptotic proteins bcl-2 and bcl-x(L) in the substantia nigra (SN) of the adult rat and their response to oxidative stress caused by striatal injections of 6-hydroxydopamine (6-OHDA). Our data show that bcl-2, bcl-x and bax proteins are present in the SN. Bcl-2 and bax are localized primarily in neurons including all those positive for tyrosine hydroxylase (TH). The intraneuronal distribution of bcl-2 and bax were different. Bcl-2 was diffuse throughout the cell while bax was localized in well-defined structures around the nucleus and within processes. Bcl-x staining in neurons was weak, though it was strongly expressed in GFAP-positive astrocytes. 6-OHDA injections, which resulted in loss of dopamine neurons between 7-14 days post-lesion, altered the distribution of bax, bcl-2 and bcl-x proteins in the SN. Bcl-2 and bax were decreased in the TH-positive cells of the SN from 3 to 14 days post-lesion and many TH-positive neurons were bcl-2 negative. Neuronal bcl-x was initially unchanged after lesion, but increased in astrocytes between 3-7 days post-lesion before the increase in GFAP immunoreactivity, which was detectable at days 10-14. While the neuronal distribution of bcl-2 and bcl-x does not change following lesion, bax became evenly distributed thought the soma. Morphological features of apoptosis, including TUNEL labeling and chromatin condensation was not observed. These data suggest that striatal 6-OHDA lesions do not result in classical apoptosis in the SN of the adult rat, even though there are changes in the content and distribution of members of the bcl-2 family of proteins.     

不同增殖能力结肠癌细胞株iNOSmRNA表达的比较研究

目的:探讨iNOSmRNA在结肠癌不同增殖能力细胞株中的表达和作用,研究ATRA对于结肠癌不同增殖能力细胞株iNOSmRNA表达的影响。方法:采用MTT方法确定结肠癌细胞株CW-2和LS174T的生长增殖状况,用RT-PCR和Northernblot方法检测结肠癌中iNOSmRNA的表达量。结果:MTT生长曲线显示结肠癌细胞株LS174T的生长增殖比CW-2快;RT-PCR显示CW-2细胞株有较强的iNOSmRNA表达,而LS174T细胞株iNOSmRNA的表达较弱;Northernblot检测在CW-2中有明显的iNOSmRNA表达,但在细胞株LS174T中表达相对较弱;ATRA对结肠癌CW-2和LS174T细胞株iNOSmRNA的表达量无明显影响。结论:iNOSmRNA对结肠癌细胞株生长有双重作用,即在低增殖结肠癌CW-2呈高表达,可以通过细胞毒或诱导细胞凋亡等作用发挥抗肿瘤效应;在高增殖结肠癌LS174T呈低表达,产生NO作为信号转导的重要分子,增加血供和血管生成,促进肿瘤生长、侵袭和转移。ATRA可以抑制结肠癌细胞株的生长。     

Practicable recovery of plasmids carrying cDNAs encoding anti-apoptotic factors that had been introduced by particle bombardment into 5-week old rat hippocampal slices.

In the central nervous system, neuronal cells interact with glial cells and functionally differentiate, a process which can not be reproduced in cell culture. Identification of the novel factors involved in the growth and/or rescue of the differentiated neuronal cells has been impeded by a lack of methods for selecting the genes. In this study, hippocampal slices of a 5-week old rat were transiently introduced with plasmid DNA carrying anti-apoptotic rat bcl-2 or bcl-x cDNA by a particle-bombardment transfection procedure. The plasmid DNAs were expected not to be digested in living cells. Intact plasmid DNAs were recovered by PCR amplification from the slices with bcl-2 or bcl-x cDNAs but not from slices with empty vector or bax cDNA that promotes cell death. This study proposed that a technical combination of organotypic culture and particle-bombardment transfection is profitable for identifying novel genes that promote the survival of neuronal cells.     

不同化疗药物对结肠癌细胞获得性TRAIL基因耐药的逆转作用

目的：探讨不同化疗药物对结肠癌DLD1细胞获得性TRAIL基因耐药的逆转作用及其可能的机制。 方法：将不同化疗药物联合重组腺病毒载体（Ad）介导的TRAIL基因处理对Ad/gTRAIL耐药的结肠癌DLD1-TRAIL/R细胞，通过MTT法检测治疗后肿瘤细胞的存活率，以评价化疗药物对TRAIL基因耐药的逆转作用；然后进一步在体内评价该逆转策略的有效性；接着通过Western免疫印迹等方法探讨逆转耐药的可能机制。结果：在体外检测了5-氟脲嘧啶、丝裂霉素、阿霉素、氟脲苷、依立替康以及顺铂6种化疗药物对DLD1-TRAIL/R细胞TRAIL基因耐药的逆转作用，结果发现只有5-氟脲嘧啶和丝裂霉素能够使DLD1-TRAIL/R细胞对Ad/gTRAIL重新敏感。进一步的结果表明联合5-氟脲嘧啶和Ad/gTRAIL能在体内有效地抑制DLD1-TRAIL/R细胞来源的肿瘤生长，且该抑制作用明显强于其它对照组。结论：联合使用Ad/gTRAIL和5-氟脲嘧啶或丝裂霉素能在体内外有效地逆转DLD1-TRAIL/R细胞对TRAIL基因的获得性耐药，其中丝裂霉素的逆转作用可能与其诱导的Bax过度表达有关。     

Netrin-4 delays colorectal cancer carcinomatosis by inhibiting tumor angiogenesis

A close relationship between tumor angiogenesis, growth, and carcinomatosis has been observed. Netrin-4 (NT-4) has been shown to regulate angiogenic responses. We aimed to examine the effects of NT-4 on colon tumor angiogenesis, growth, and carcinomatosis. We showed that NT-4 was expressed in human colon cancer cells (LS174). A 20-fold increase in NT-4 expression was stably induced by NT-4 pcDNA in LS174 cells. In vivo, a Matrigel angiogenesis assay showed that NT-4 overexpression altered vascular endothelial growth factor (VEGF)/basic fibroblast growth factor-induced angiogenesis. In nude mice with LS174 xenografts, NT-4 overexpression inhibited tumor angiogenesis and growth. In addition, these NT-4-involved inhibitory effects were associated with decreased tumor cell proliferation and increased tumor cell apoptosis. Using an orthotopic peritoneal carcinomatosis model, we demonstrated that NT-4 overexpression decreased colorectal cancer carcinomatosis. Moreover, carcinomatosis-related ascites formation was significantly decreased in mice transplanted with NT-4 LS174 cells versus control LS174 cells. The antiangiogenic activity of NT-4 was probably mediated by binding to its receptor neogenin. Netrin-4 had a direct effect on neither in vitro apoptosis and proliferation of cultured LS174 cells nor the VEGF-induced acute increase in vascular permeability in vivo. We propose that NT-4 overexpression decreases tumor growth and carcinomatosis, probably via an antiangiogenic effect, underlying the potential therapeutic interest in NT-4 in the treatment of colorectal cancer growth and carcinomatosis.     

HER2介导乳腺癌细胞多药耐药的作用及机制

目的筛选HER2高表达乳腺癌细胞化疗耐受的药物种类,探讨HER2介导的乳腺癌多药耐药的机制。方法构建HER2稳定高表达的乳腺癌细胞MCF-7/HER2模型;MTT法检测该细胞对多种临床常用的抗乳腺癌药物的敏感性;Hochest33258染色观察药物诱导的MCF-7/HER2的凋亡率,并采用聚合酶链式反应(RT-PCR)检测细胞中bcl-2和survivin基因的mRNA表达。结果MCF-7/HER2细胞对Taxol,MMC,5-FU,VP-16及TSPA的耐药指数分别为对照细胞的74,22,2.5,3.5和2.8倍,出现了明显的药物抗性(P<0.05);而对CDDP,ADM,VBL,VCR,NBV和MTX等的耐药指数与对照组相比,差异无统计学意义(P>0.05);由Taxol,MMC,5-FU,VP-16诱导的MCF-7/HER2细胞凋亡率明显低于对照细胞;MCF-7/HER2细胞survivin基因表达明显高于对照组,而bcl-2基因表达与对照组比较,差异无统计学意义。结论HER2可介导乳腺癌细胞对Taxol,MMC,5-FU,VP-16和TSPA等的多药抗性,这种多药抗性的产生可能与HER2上调survivin表达所致的凋亡抗性有关。     

四环素调控表达的反义bcl-2对人神经母细胞瘤细胞系SK-N-MC生长和凋亡的作用

目的 研究由四环素调控的反义bcl-2的表达对人神经母细胞瘤细胞系SK－N－MC细胞的生长和凋亡的作用并初步探讨其相关机制。方法 非定向克隆构建携带反义bcl-2 cDNA片段的由四环素调控表达的真核细胞表达载体PUCCOMB1^CMV/Asbcl-2;应用脂质体Lipofectamine^TM介导转染SK－N－MC细胞,同时以空载体转染细胞作为对照。MTT法研究细胞的生长和增殖状况,提取DNA梯带和应用流式细胞术检测凋亡细胞。逆转录－聚合酶链反应（RT－PCR）研究细胞凋亡中bcl-xL/bcl-xS基因在mRNA水平上表达的变化。Western杂交检测bcl-2及其上下游相关基因caspase-3、PARP的变化。结果 转染反义bcl-2的细胞生长增殖缓慢,在去血清培养的相同的时间内其凋亡细胞数也明显多于对照组细胞,提前出现DNA梯带。在细胞的凋亡过程中检测到非活性caspase-3酶原蛋白减少并检测到bcl-2、PARP蛋白的降解产物条带。但bcl-xL/bcl-xS基因在mRNA水平上表达无明显变化。结论 反义bcl-2 mRNA可抑制SK－N－MC细胞的生长和增殖,促进去血清培养所诱导的SK－N－MC细胞的凋亡。大细胞凋亡过程中caspase-3被激活,bcl-2和PARP蛋白被裂解,但bcl-xL/bcl-xS在反义bcl-2 mRNA诱导的SK－N－MC细胞的凋亡过程中无变化。     

Expression of bcl-x during mouse B cell differentiation and following activation by various stimuli

We have studied the expression of the novel anti-apoptotic protein bcl-x during mouse B cell differentiation and activation. We find that bcl-x is expressed throughout all stages of B cell differentiation in the bone marrow, and is only down-regulated in mature (sIgD⁺) B cells. Immature peripheral B cells express low levels of bcl-x even in adult animals, whereas mature resting B cells do not. Mature B cells re-express the protein following activation, achieving maximal levels after 36–48 h. The highest levels of bcl-x are observed with potent comitogenic stimuli (such as anti-CD40 + anti-Ig): B cells first express bcl-x in the G1 phase of the cell cycle and contain maximal levels in S phase. In addition, B cells from CBA/N mice, which do not proliferate when stimulated with anti-Ig, anti-CD40, or both, exhibited only low levels of the protein following culture with these stimuli. To investigate the functional significance of bcl-x in activated B cells, we tested their sensitivity to apoptosis induced by the Ca²⁺ ATPase inhibitor thapsigargin: B cell blasts activated with anti-CD40 and anti-Ig were resistant to this agent. The available data therefore suggest that bcl-x fulfils two roles in B cells: it promotes survival of immature B cells (which lack bcl-2) and secondly, it apparently plays an additional role in protecting activated mature B cells (perhaps those in germinal centers) from apoptotic stimuli.     

Survivin expression in ovarian carcinoma: correlation with apoptotic markers and prognosis.

Survivin is a novel inhibitor of apoptosis commonly detected in tissues during fetal development and in cancer, but not usually in normal tissues. Expression of this protein may be of prognostic significance and therapeutically relevant in many cancers. We assessed survivin expression in ovarian carcinoma, correlating results with expression of other anti-apoptotic (bcl-2, bcl-x, mutant p53) and pro-apoptotic (bax) markers, with prognostic parameters, and prognosis. Paraffin-embedded sections of 49 ovarian carcinoma were immunostained for survivin, bcl-2, bcl-x, bax, and p53. Expression was evaluated in nuclei and cytoplasm, as intensity (0-3+), and percentage of positive cells was scored on a four-tiered system with <10% as negative. Frequency of survivin, bcl-2, bcl-x, bax, and p53 was 73.5%, 36.7%, 93.9%, 77.6%, and 60.4%, respectively. There was significant correlation between nuclear survivin expression and grade (P =.0014), histologic type (P =.0376), and mutant p53 (P =.0414). Survivin expression did not correlate with bcl-2, bcl-x, or bax expression, stage, or overall or disease-free survival. The majority (74%) of ovarian carcinoma show survivin expression, which correlates with poor prognostic parameters (high grade, histologic type, p53 mutation) but not with survival. Therapeutic targeting of survivin in ovarian carcinoma is a future possibility.     

结肠癌干细胞样细胞的体外培养、鉴定及n-3多不饱和脂肪酸对结肠癌干细胞样细胞的抗增殖作用

 目的:采取无血清培养法培养出SW620细胞球,并对细胞球细胞进行干细胞鉴定;在细胞水平研究n-3多不饱和脂肪酸（n-3 PUFAs）对结肠癌干细胞样细胞的作用。 方法: 正常培养人结肠癌细胞株SW620并使其逐步适应无血清培养条件,经无血清培养1周后收集SW620细胞球。用免疫荧光法检测胚胎干细胞标志物SSEA-1和TRA-1-81;采用real-time PCR的方法检测干细胞相关基因Sox-2和Oct-4的表达情况;对比SW620贴壁细胞和干细胞样细胞（CSCLC）在软琼脂上的克隆形成能力;采用裸鼠移植瘤模型比较2种细胞的成瘤能力;用MTS法对比2种细胞在递增浓度的5-氟尿嘧啶（5-FU）或mitomycin C处理下的生长抑制情况;用MTS法、Annexin V/PI染色和台盼蓝染色分别观察递增浓度二十二碳六烯酸（DHA）和二十碳五烯酸（EPA）作用于SW620 CSCLC后细胞生长抑制情况、凋亡情况和死亡情况;MTS法检测5-FU或mitomycin C联合n-3 PUFAs对结肠癌CSCLC增殖的影响。 结果: 无血清培养法成功从SW620中培养出细胞球。细胞球细胞高表达SSEA-1和TRA-1-81并一过性表达Sox-2和Oct-4基因;对5-FU及mitomycin C相对抵抗;在软琼脂上克隆形成率及在裸鼠皮下的成瘤率均显著高于贴壁细胞,表明这些细胞具有干细胞特性,即为来自于SW620的CSCLC。DHA和（或）EPA作用于SW620 CSCLC能抑制细胞生长、诱导细胞凋亡,并能增强5-FU及mitomycin C对其抑制作用。 结论: 无血清培养法能够从SW620细胞中培养出具有干细胞特性的细胞,它们具有高克隆形成能力及高致瘤性,对化疗药物相对抗拒;DHA和EPA能够诱导SW620来源CSCLC发生凋亡并增强化疗药物的抗肿瘤活性。     

Correlation between chemosensitivity to anticancer drugs and Bcl-2 expression in gastric cancer

Objective: To investigate chemoresistance of human gastric cancer to chemotherapeutic drugs in vitro and explore the relationship with Bcl-2 protein expression. Methods: Single-cell suspensions were prepared from freshly excised samples of primary gastric cancer, and were separately exposed to taxol (TAX), cisplatin (CDDP), 5-fluorouracil (5-FU), adriamycin (ADM) and mitomycin (MMC) for 48 h. The induction of cell death was confirmed by microscopic analysis of cell morphology. Metabolic activity and the inhibitory rate (IR) of cells were evaluated by MTT assay. Expression of Bcl-2 was determined by immunohistochemistry of gastric cancer tissue samples. Results: The IRs of cancer cells exposed to different chemotherapeutic drugs varied as follows: the IRs for TAX, CDDP and 5-FU were significantly higher than those for ADM and MMC (P < 0.01). Poorly differentiated gastric cancer cells were more sensitive than well-differentiated cells (P = 0.021). The positive rate of Bcl-2 expression was 80%, and Bcl-2 expression was significantly associated with chemoresistance to 5-FU (r_s = 0.265, P = 0.041), ADM (r_s = 0.425, P = 0.001) and MMC (r_s = 0.40, P = 0.002). Furthermore, Bcl-2 expression was strongly associated with lymph node metastasis in gastric cancer (P = 0.009). Conclusion: Overexpression of Bcl-2 may predict a loss of the efficacy of the chemotherapy drugs 5-FU, ADM and MMC in patients with gastric cancer.     

Rho proteins and cell-matrix interactions in cancer

Dynamic interactions and dissolution of cell-extracellular matrix contacts are required steps to support cell growth and survival during cancer cell metastasis. Malignant cells acquire the ability to remodel extracellular matrix (ECM) and to modulate the expression of ECM receptors. Integrins are cellular receptors for molecules in the extracellular matrix. Integrin signaling is known to regulate metastatic cancer phenotypes by interacting synergistically with several signaling pathways, including the growth factor receptor pathway, the Ras-MAP kinase (Ras-MAPK) pathway and the Rho-effector pathway. In this mini-review, we discuss the functions of the Rho proteins and their relationship with other signaling pathways in matrix remodeling and integrin signaling of highly motile and invasive cancer cells.     

Resistance to apoptosis is increased during metastatic dissemination of colon cancer

Apoptosis dysfunction in metastases has been suggested to participate in their poor response to conventional anticancer treatments. To address this question, we have analyzed the sensitivity to cell death induced by non-steroid anti-inflammatory drug, Sulindac, the most common drug used in colon cancer chemotherapy, 5-fluorouracil (5-FU) and the short chain fatty acid, butyrate (Bu) in cell lines derived from a primary colorectal tumor (ALT-I) as well as the liver (ALT-F) and the lymph-node (ALT-G) metastases. We have previously shown both in vitro by analyzing anchorage-independent cell proliferation and in vivo by subcutaneous injection into athymic nude mice that the ALT-F and ALT-G cells were more tumorigenic than the primary ALT-I cells. All these cell lines, derived from an untreated patient, were highly resistant to apoptosis induced by 5-FU and Sulindac but were sensitive to Bu-induced apoptosis. The resistance to apoptosis was, as quantified by the induction of caspase activity and the relative percentage of apoptotic cells, higher in the metastatic cell lines, than in the ALT cell line. When compared to the primary tumor, more anti-apoptotic bcl-2 and less pro-apoptotic bax were expressed in the liver and lymph node metastatic cell lines. Quite remarkably, the expression of bax was up-regulated during Bu-treatment, a feature that could explain its powerful pro-apoptotic activity. This revised version was published online in July 2006 with corrections to the Cover Date.     

Activation of human mast cells through stem cell factor receptor (KIT) is associated with expression of bcl-2

BACKGROUND: Mast cells (MCs) are multifunctional effector cells of the immune system. These cells originate from pluripotent hemopoietic progenitors. In contrast to basophils and other leukocytes, MCs exhibit a remarkably long life span (years) in vivo. Although a role for stem cell factor (SCF) and SCF receptor (KIT) in long-term survival of MCs has been proposed, the underlying biochemical mechanisms remain unknown. MATERIALS AND METHODS: We have examined expression of 'survival-related' molecules of the bcl-2 family including bcl-2 and bcl-x(L), in primary human MCs and the human MC line HMC-1. Primary MCs were isolated from dispersed lung tissue by cell sorting using an antibody against KIT. mRNA expression was analyzed by RT-PCR and Northern blotting. Results: As assessed by RT-PCR, purified unstimulated lung MCs (>98% pure) exhibited KIT- and bcl-x(L) mRNA, but did not express bcl-2 mRNA. However, exposure of lung MCS to SCF (100 ng/ml) for 8 h resulted in expression of bcl-2 mRNA. Corresponding results were obtained by immunocytochemistry. In fact, exposure of MC to SCF resulted in expression of the bcl-2 protein whereas unstimulated MCs displayed only the bcl-x(L) protein without expressing the bcl-2 protein. The human MC leukemia cell line HMC-1, which contains a mutated and intrinsically activated SCF receptor, showed constitutive expression of both bcl-2 and bcl-x(L) at the mRNA and protein level. CONCLUSION: Our data show that human MCs can express members of the bcl-2 family. It is hypothesized that bcl-x(L) plays a role in KIT-independent growth of MCs, whereas bcl-2 may be involved in KIT-dependent functions of MCs.     

Knockdown of MMP-7 inhibits cell proliferation and enhances sensitivity to 5-fluorouracil and X-ray irradiation in colon cancer cells

The role of matrix metalloproteinase-7 (MMP-7) in the pathogenesis of colon cancer is not understood thoroughly. Previous studies from our group have shown that the expression levels of MMP-7 were highly elevated in colorectal cancer patient specimens and were correlated with Dukes Staging, histological differentiation grade and CEA level. The goal of this study was to investigate the cellular impact of MMP-7 in colon cancer. In this study, we used the SW480 colon cancer cell lines of MMP-7 knockdown by lentivirus-mediated RNA interference as a model system to investigate the impact of MMP-7 on cell proliferation and sensitivity to 5-Fluorouracil (5-FU) and X-ray irradiation (IR). Cell proliferation and sensitivity to 5-FU and IR were measured by MTT assay and colony formation assay. Cell cycle was evaluated by flow cytometry. We showed that the down regulation of MMP-7 inhibits colon cancer cell proliferation and sensitizes tumour cells to 5-FU and IR (P < 0.05). Decreased MMP-7 expression in SW480 cells by RNA interference triggered cell cycle arrest at G1 phase (P < 0.05). Down regulation of MMP-7 may inhibit the cell proliferation of colon cancer cells and increase tumour cells sensitivity to radiotherapy and chemotherapy. RNAi-mediated silencing of MMP-7 may represent a powerful therapeutic approach for controlling human colorectal cancer growth.     

Cytotoxicity of combinations of IFN-beta and chemotherapeutic drugs.

Interferon-beta (IFN-beta) induces various antiproliferative activities. In solid tumor cells, IFN-beta inhibits cell cycle progression, which mainly occurs as S phase accumulation. The IFN-beta-induced cell cycle effect has been implicated in the antitumor effect of combinations of IFN-beta and chemotherapeutic drugs. In this report, we characterized the viability of various human tumor cells in vitro after combination treatment with IFN-beta protein and the chemotherapeutic drugs, cis-platinum (II) diamine dichloride (cisplatin), 5-fluorouracil (5-FU), paclitaxel (Taxol) and gemcitabine. IFN-beta could significantly potentiate the cytotoxicity of these chemotherapeutic drugs. The potentiating effect was observed after pretreatment of tumor cells with IFN-beta but did not require the constant presence of IFN-beta. The potentiating effect correlated with the sensitivity of the tumor cells to the IFN-beta-induced cytotoxicity. Furthermore, chemotherapeutic drugs also potentiated the cytotoxicity of IFN-beta. We conclude that the cell cycle effect per se did not determine the ability of IFN-beta to potentiate the cytotoxicity of chemotherapeutic drugs. We suggest that the combination of local IFN-beta gene therapy with chemotherapy could be an effective cancer treatment.