Infliximab induces potent anti-inflammatory responses by outside-to-inside signals through transmembrane TNF-alpha

BACKGROUND AND AIMS: Both infliximab (chimeric anti-tumor necrosis factor [TNF]-alpha antibody) and etanercept (p75 TNF-alpha receptor/immunoglobulin G fusion protein) are effective against rheumatoid arthritis, but only infliximab induces clinical remission in Crohn's disease. To clarify this difference in clinical efficacy, we investigated reverse signaling through transmembrane TNF-alpha (mTNF) by these 2 anti-TNF agents. METHODS: We stably transfected wild-type and cytoplasmic serine-replaced mutant forms of mTNF in human Jurkat T cells. Cells were stimulated with infliximab and etanercept and then analyzed for E-selectin expression, reactive oxygen species accumulation, apoptosis, and cell cycle distribution by flow cytometry. Interleukin-10 and interferon-gamma were measured by enzyme-linked immunosorbent assay. Phospho-c-Jun NH2-terminal kinase, Bax, Bak, p21(WAF1/CIP1), caspase-8, and caspase-3 were examined by immunoblotting. RESULTS: Both anti-TNF agents induced E-selectin expression, but only infliximab induced interleukin-10 production, apoptosis, and G0/G1 cell cycle arrest. Apoptosis and cell cycle arrest were abolished by substitution of all 3 cytoplasmic serine residues of mTNF by alanine residues. Infliximab induced accumulation of reactive oxygen species and up-regulation of Bax, Bak, and p21(WAF1/CIP1) proteins, suggesting the involvement of p53 activation. Moreover, phosphorylation of c-Jun NH2-terminal kinase was necessary for infliximab-induced apoptosis and cell cycle arrest. CONCLUSIONS: We revealed the mTNF motifs and the downstream intracellular molecular events essential for reverse signaling through mTNF. The biologic effects of mTNF elicited by infliximab should be important action mechanisms of this potent anti-inflammatory agent in addition to the neutralization of soluble TNF-alpha. These observations will provide insight into the novel role of mTNF in inflammation.     

p21<Superscript>WAF1/CIP1</Superscript> is more effective than p53 in growth suppression of mouse renal carcinoma cell line Renca in vitro and in vivo

Purpose Although there are many controversial reports about the effect of p53 and p21^WAF1/CIP1 overexpression in different human tumor cells, the p53 gene is shown to be a more effective candidate for cancer gene therapy because of its more pronounced ability to induce apoptosis. In the present study, we present the effect of p53 and p21^WAF1/CIP1 overexpression on mouse renal carcinoma cells in vitro and in vivo.Methods p53 and p21^WAF1/CIP1 genes were introduced into Renca cells using adenoviral vectors (Ad5CMV-p53 and Ad5CMV-p21). The induction of apoptosis was measured using Annexin V assay and DNA fragmentation analysis. The expression of proteins was examined using immunocytochemistry and Western blot methods. The ability of adenoviral vectors to inhibit tumorigenicity of Renca cells, as well as the growth of pre-established tumors was measured.Results In vitro growth assays revealed higher growth suppression after Ad5CMV-p21 infection. Although both vectors induced apoptosis, Ad5CMV-p53 was slightly more efficient. In vivo studies in Balb/c mice, demonstrated that tumorigenicity was completely suppressed by Ad5CMV-p21. Besides this, Ad5CMV-p21 significantly inhibited the growth of established tumors, while Ad5CMV-p53 did not.Conclusions These data suggest that p21^WAF1/CIP1 is a more potent growth suppressor than p53 of mouse tumor cells Renca. The divergent responses of tumor cells to p21^WAF1/CIP1 overexpression could be due to various networks that differ between species.     

Relationship between K-ras mutation and the expression of p21WAF1/CIP1 and p53 in chronic pancreatitis and pancreatic adenocarcinoma

Overexpression of p21WAF1/CIP1 was recently described as an early event in the development of pancreatic intraepithelial neoplasia. Since activating K-ras mutations are described in more than 80% of pancreatic cancers and are known to increase intracellular levels of p21WAF1/CIP1 in experimental models, the possible role of activating K-ras mutations in an induction of the p21WAF1/CIP1 expression was investigated in our study. We examined 71 surgical specimens, 29 of chronic pancreatitis and 42 of invasive ductal adenocarcinoma both having a large spectrum of PanIN (pancreatic intraepithelial neoplasia) lesions. Expression of p53 and p21WAF1/CIP1 was examined immunohistochemically and codon 12 K-ras mutational analysis was performed using the very sensitive mutant-enriched PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) analysis. Our study demonstrated the overexpression of p21WAF1/CIP1 as an early event in the development of pancreatic intraepithelial neoplasia in the group of chronic pancreatitis and invasive adenocarcinoma as well. Overexpression of p21WAF1/CIP1 increased progressively from normal ducts through the spectrum of PanIN lesions to invasive carcinomas. The p53 overexpression increased again progressively according to the severity of the lesion and seems to be a later event in the development of pancreatic intraepithelial neoplasia if compared to p21WAF1/CIP1 expression. Our results confirmed also the possible p53 independent p21WAF1/CIP1 expression in some PanIN2, PanIN3 lesions and invasive carcinomas. K-ras mutations were not revealed in samples with only low grade PanIN lesions (PanIN1a and PanIN1b). K-ras mutations were detected in 69,4% adenocarcinomas and in only one case of chronic pancreatitis. Two codon 12 K-ras positive pancreatic carcinomas showed K-ras mutations in the surrounding normal pancreatic tissue. In adenocarcinomas, no statistically significant correlation was found between K-ras mutational status and p21WAF1/CIP1 and p53 expression, respectively. The possible role of activating K-ras mutations in an induction of p21WAF1/CIP1 expression was not confirmed in this study.     

Status of p53 phosphorylation and function in sensitive and resistant human cancer models exposed to platinum-based DNA damaging agents

Purpose Resistance to chemotherapeutic drugs is a hallmark of many human cancers, which can occur independent of p53 gene status; however, the presence of wild-type p53 in chemorefractory tumors confers greater resistance to cisplatin, but such tumors do not display complete cross-resistance to the platinum analog (1R,2R-diaminocyclohexane)(trans-diacetato)(dichloro)platinum^IV (DACH-Ac-Pt). In this article we examine DNA damage-induced phosphorylation of p53 and downstream p53-dependent transactivation events in cisplatin-sensitive and cisplatin-resistant human cancer cell lines possessing wild-type p53.Methods Western-blot analysis was utilized to study the effect of cisplatin and the analog on p53 phosphorylation and p53-dependent target genes.Results In response to CDDP and DACH-Ac-Pt, both CDDP-sensitive and CDDP-resistant models demonstrated time- and dose-dependent inductions of total p53 protein and an increase in Ser-15 phosphorylation, which was more pronounced with CDDP. Although phosphorylation of p53 at Ser-392 was also observed in CDDP-treated sensitive and resistant cells, it was weak or absent in response to DACH-Ac-Pt. Lack of Ser-392 phosphorylation by DACH-Ac-Pt, however, did not affect the induction of p21^WAF1/CIP1 or Mdm2. Similarly, inductions of p21^WAF1/CIP1 and Mdm2 were observed in sensitive cells exposed to cisplatin. In marked contrast, cisplatin-mediated induction of p21^WAF1/CIP1 was minimal or absent in resistant cells, but that of Mdm2 was unaffected. Wortmannin, a PI3-kinase (PI3-K) inhibitor, caused a dose-dependent inhibition of total p53 accumulation, Ser-15 phosphorylation and p21^WAF1/CIP1 transactivation in response to both CDDP and DACH-Ac-Pt, indicating that members of the PI3-K family are involved in phosphorylation of p53 and that transactivation of p21^WAF1/CIP1 is p53 dependent.Conclusion These studies demonstrate that cisplatin and DACH-Ac-Pt differentially phosphorylate p53 through independent DNA damage-induced pathways, and that the kinase-mediated phosphorylation of p53 at Ser-15 or Ser-392 is unaltered in resistance. Moreover, the phosphorylation status of Ser-392 on its own does not appear to correlate with p21^WAF1/CIP1 or Mdm2 induction in these studies; however, a lack of increase in p21^WAF1/CIP1 by cisplatin, but not DACH-Ac-Pt, provides a correlation with resistance and its circumvention, and implicates the role for cyclin-dependent kinase inhibitor in the differential cytotoxic effects of the two platinum agents against resistant cells.     

肝胆管癌丙型肝炎病毒感染与p53和p21WAFD/CIP1异常表达的关系

为探讨丙型肝炎病毒（ＨＣＶ）感染与Ｐ５３和Ｐ２１ＴＷＡＦ－／ＣＩＰ１基因的关系。采用 化技术对２９例原发性肝胆管癌中ＨＣＶ抗原（ＮＳ５－Ａｇ）、ｐ５３和ｐ２１＾ＷＡＦＩ＝／ＣＩＰ１蛋白表达进行研究。结果：２９例胆管癌中ＮＳ５－Ａｇ、ｐ５３及Ｐ２１ＴＷＡＦＩ／ＣＩＰＩ蛋白表达进行研究。结果：２９例胆管癌中ＮＳ５－Ａｇ、Ｐ５３display structure     

Induction of the WAF1/CIP1 protein and apoptosis in human T-cell leukemia virus type I-transformed lymphocytes after treatment with adriamycin by using a p53-independent pathway.

The WAF1/CIP1 protein has been identified as a downstream mediator of the tumor suppressor p53 in regulating cell cycle progression through a G1-phase check-point. Recent work has implicated the functional status of p53 as a critical determinant in the apoptotic response of certain cell lines to DNA damaging agents. By using human T-cell leukemia virus type I-transformed lymphoid cell lines that differ in their level and function of wild-type p53, we investigated the induction of WAF1/CIP1 and apoptosis after exposure to Adriamycin, a genotoxic agent. We found that regardless of the p53 status in these cell lines, WAF1/CIP1 RNA was rapidly induced in response to Adriamycin treatment. An elevated level of WAF1/CIP1 protein was observed as well. Additionally, we demonstrated that apoptosis was induced in all cell lines analyzed despite some having functionally inactive p53 protein. Our data suggest that a p53-independent pathway may play a role in the apoptotic response observed in some cell lines after exposure to DNA damaging agents.     

Expression of p53 and p21WAF1/CIP1 Proteins in Gastric and Esophageal Cancers (Comparison with Mutations of the p53 Gene)

The p53 gene has been shown to be commonlymutated in various human cancers, and mutant p53 can actas a dominant oncogene. The intact p53 protein is alsoknown to induce the cyclin-dependent kinase inhibitor p21^WAF1/CIP1 and is implicated incell cycle arrest. We investigated p53 gene alterationsin gastric adenocarcinoma and esophageal squamous cellcarcinoma to elucidate the association of the nuclearaccumulation of the p53 protein and/orp21^WAF1/CIP1 protein. Abnormalities of thetumor suppressor gene p53 protein and the expression ofp21^WAF1/CIP1 protein were analyzed byimmunohistochemical techniques in 32 cases of gastric adenocarcinoma and 15 cases ofesophageal squamous cell carcinoma. Twenty cases ofgastric cancer and five cases of esophageal cancer werealso analyzed for p53 gene mutation by polymerase chain reaction and direct nucleotide sequencing.Overexpression of p53 protein was found in 13/32 (41%)of gastric cancers and 5/15 (33%) of esophageal cancers.We found immunodetectable p53 in 10/14 cases with mutations and in none of 11 cases withoutmutations in gastric and esophageal cancers. Hence,immunohistochemical and genetic analyses gave concordantresults in 84% of 25 cases, revealing a good correlation between immunostaining of p53 and missensemutation of the p53 gene. p53 immunostaining was notobserved in cases with frameshift or splicing mutation.The expression of p21^WAF1/CIP1 protein wasfound in 9/32 (29%) of gastric cancers and 4/15 (27%) ofesophageal cancers and in 2/14 (14%) cases withalteration of the p53 gene and in 5/11 (45%) without.These results suggest that abnormalities of p53 may be closely associated with the pathogenesisof gastric adenocarcinoma and esophageal squamous cellcarcinoma and that the immunoreactivity of p53 proteinis a general indicator of the tumors with altered p53 function. The expression ofp21^WAF1/CIP1 protein was suppressed in theneoplastic tissues with and without p53 genealteration.     

Cell cycle inhibition by the anti-angiogenic agent TNP-470 is mediated by p53 and p21WAF1/CIP1

Angiogenesis has been demonstrated to be essential for tumor growth and metastasis, and inhibition of angiogenesis is emerging as a promising strategy for treating cancer. Among the most potent inhibitors of angiogenesis is the fumagillin family of natural products. An analog of fumagillin, known as TNP-470 or AGM-1470, has been undergoing clinical trials for treating a variety of cancers. TNP-470 has been shown to block endothelial cell cycle progression in the late G(1) phase. Although the direct molecular target for TNP-470 has been identified as the type 2 methionine aminopeptidase (MetAP2), how inhibition of this enzyme leads to cell cycle arrest has remained unclear. We report that treatment of endothelial and other drug-sensitive cell types leads to the activation of the p53 pathway, causing an accumulation of the G(1) cyclin-dependent kinase inhibitor p21(WAF1/CIP1). The requirement of p53 and p21(WAF1/CIP1) for the cell cycle inhibition by TNP-470 is underscored by the observation that cells deficient in p53 and p21(WAF1/CIP1) are resistant to TNP-470. These results shed significant light on the mechanism of cell cycle inhibition by TNP-470 and suggest an alternative method of activating p53 in endothelial cells to halt angiogenesis and tumor progression.     

Proteasome inhibitors induced caspase-dependent apoptosis and accumulation of p21WAF1/Cip1 in human immature leukemic cells

The 26S proteasome is a non-lysosomal multicatalytic protease complex for degrading intracellular proteins by ATP/ubiquitin-dependent proteolysis. Tightly ordered proteasomal degradation of proteins critical for cell cycle control implies a role of the proteasome in maintaining cell proliferation and cell survival. In this study, we demonstrate that cell-permeable proteasome inhibitors, lactacystin, benzyloxycarbonyl(Z)-leucyl-leucyl-leucinal (ZLLLal; MG-132) and 4-hydroxy-5-iodo-3-nitrophenylacetyl-leucyl-leucyl-leucine vinyl sulfone (NLVS), induce apoptosis abundantly in p53-defective leukemic cell lines CCRF-CEM, U937 and K562 as well as in myelogenic and lymphatic leukemic cells obtained from adult individuals with relapsed acute leukemias. Leukemic cell apoptosis induced by the proteasome inhibitors was dependent on activation of caspase-3 and related caspase family proteases, because caspase-3 inhibitor N-acetyl-L-aspartyl-L-glutamyl-L-valyl-L-aspartal (Ac-DEVD-cho) and, more effectively, the general caspase-inhibitor N-benzyloxycarbonyl-L-valyl-L-alanyl-L-aspartate fluoromethylketone (Z-VAD-fmk) were capable of blocking apoptosis induced by lactacystin, ZLLLal or NLVS. Induction of apoptosis by lactacystin or ZLLLal was accompanied by cell cycle arrest at G2/M phase and by accumulation and stabilization of cyclin-dependent kinase inhibitor p21WAF1/Cip and tumor suppressor protein p53. A role of p53 in mediating apoptosis or induction of p21WAF1/Cip1 was ruled out since CCRF-CEM and U937 cells express non-functional mutant p53, and K562 cells lack expression of p53. Viability and hematopoietic outgrowth of human CD34+ progenitor cells treated with lactacystin were slightly reduced, whereas treatment of CD34 + cells with ZLLLal or the cytostatic drugs doxorubicin and gemcitabine resulted in markedly reduced viability and hematopoietic outgrowth. These results demonstrate a basic role of the proteasome in maintaining survival of human leukemic cells, and may define cell-permeable proteasome inhibitors as potently anti-leukemic agents which exhibit a moderate hematopoietic toxicity in vitro.     

HCC和HepG2细胞表达HCV C蛋白、p14ARF、p21WAF1的意义探讨

目的检测HCVC蛋白、p14、p21在HCC和表达野生p53HepG2中的表达，初步探讨C蛋白在HCC和HepG2中对p14-p53-p21凋亡通路的作用。方法收集42例HCC石蜡组织，采用免疫组织化学EnVision法检测HCC组织中核心蛋白、p14和p21的表达，用统计学方法及临床联系分析它们之间的关系；用细胞化学EnVision法和免疫荧光法检测核心蛋白、p53、p14和p21在HepG2细胞中的表达。结果C蛋白、p14和p21的阳性表达主要定位于细胞核膜和细胞核中；HCC组织中C蛋白、p14和p21阳性率分别为40．5％、45．24％、19．05％；3组间的Kruskal-Wallis检验P=0．03，差异显著；C蛋白与p14、p21间及p14与D21间蛋白阳性强度相关性分析显示，P值分别为0．000、0．43、-0．34，相关系数rs分别为0．64、-0．29、-0．33。HepG2细胞有较高的C蛋白和p53表达及少量的p14、p21蛋白表达。结论在C蛋白阳性的HCC中p14的表达与C蛋白有关，HCC中D21表达缺陷是十分常见的；C蛋白在HCC中可能影响p53通路，下调p21的表达，阻止其凋亡作用；HepG2细胞永生化特性可能与HCV或HCVC蛋白有关。     

Inhibitory effect of tumor suppressor p33(ING1b) and its synergy with p53 gene in hepatocellular carcinoma

AIM: To investigate the inhibitory effect of tumor suppressor p33ING1b and its synergy with p53 gene in hepatocellular carcinoma (HCC). METHODS: Recombinant sense and antisense p33ING1b plasmids were transfected into hepatoma cell line HepG2 with lipofectamine. Apoptosis, G0/G1 arrest, cell growth rate and cloning efficiency in soft agar of HepG2 were analyzed after transfection. In three hepatoma cell lines with different endogenous p53 gene expressions, the synergistic effect of p33ING1b with p53 was analyzed by flow cytometry and luciferase assay was performed to detect the activation of p53 downstream gene p21WAF1/CIP1. In addition, the expression and mutation rates of p33ING1b in HCC tissues were measured by immunohistochemistry and polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP). RESULTS: Overexpression of p33ING1b inhibited cell growth of HepG2, induced more apoptosis and protected cells from growth in soft agar. Combined transfer of p33ING1b and p53 gene promoted hepatoma cell apoptosis, G0/G1 arrest and elevated expression of p21WAF1/CIP1. Immunostaining results showed co-localized P33ING1b with P53 protein in HCC tissues and there was a significant relation between protein expression rates of these two genes (P<0.01). Among 28 HCC samples, p33ING1b presented a low gene mutation rate (7.1%). CONCLUSION: p33ING1b collaborates with p53 in cell growth inhibition, cell cycle arrest and apoptosis in HCC. Loss or inactivation of p33ING1b normal function may be an important mechanism for the development of HCC retaining wildtype p53.     

Induction of a retinoblastoma phosphatase activity by anticancer drugs accompanies p53-independent G1 arrest and apoptosis.

DNA-damaging agents induce accumulation of the tumor suppressor and G1 checkpoint protein p53, leading cells to either growth arrest in G1 or apoptosis (programmed cell death). The p53-dependent G1 arrest involves induction of p21 (also called WAF1/CIP1/SDI1), which prevents cyclin kinase-mediated phosphorylation of retinoblastoma protein (RB). Recent studies suggest a p53-independent G1 checkpoint as well; however, little is known about its molecular mechanisms. We report that induction of a protein-serine/threonine phosphatase activity by DNA damage signals is at least one of the mechanisms responsible for p53-independent, RB-mediated G1 arrest and consequent apoptosis. When two p53-null human leukemic cell lines (HL-60 and U-937) were treated with a variety of anticancer agents, RB became hypophosphorylated, accompanied with G1 arrest. This was followed immediately (in less than 30 min) by apoptosis, as determined by the accumulation of pre-G1 apoptotic cells and the internucleosomal fragmentation of DNA. Addition of calyculin A or okadaic acid (specific serine/threonine phosphatase inhibitors) or zinc chloride (apoptosis inhibitor) prevented the G1 arrest- and apoptosis-specific RB dephosphorylation. The levels of cyclin E- and cyclin A-associated kinase activities remained high during RB dephosphorylation, supporting the involvement of a chemotherapy-induced serine/threonine phosphatase(s) rather than p21. Furthermore, the induced phosphatase activity coimmunoprecipitated with the hyperphosphorylated RB and was active in a cell-free system that reproduced the growth arrest- and apoptosis-specific RB dephosphorylation, which was inhibitable by calyculin A but not zinc. We propose that the RB phosphatase(s) might be one of the p53-independent G1 checkpoint regulators.     

P21WAF1/CIP1 expression in colorectal carcinomas is related to Kras mutations and prognosis

BACKGROUND/AIM: P21WAF1/CIP1 is a cyclin-dependent kinase inhibitor activated by p53 to produce cell cycle arrest. A consensus has not been reached concerning the prognostic value of p21WAF1/CIP1 expression in colorectal cancers. PATIENTS/METHODS: P21WAF1/CIP1 expression was determined immunohistochemically in a series of 211 cases of colorectal carcinomas, together with its relation to p53, bcl-2, cell turnover (as assessed by Ki67 expression and apoptotic counts) and the Kras gene status. The expression of p21WAF1/CIP1 was also compared with reference to clinicopathological parameters and patient survival. RESULTS: The median value for nuclear p21WAF1/CIP1 expression was 31% (interquartile range, 13-47%) and the fraction of cases considered to be high expressers (>20%) was 66%. Expression of p21WAF1/CIP1 was not associated with immunoreactivity for p53 or bcl-2, or cell turnover. P21WAF1/CIP1 high-expressing tumors were more often well differentiated (P<0.001), node-negative (P=0.037), Dukes' B (P=0.027) and Kras gene-mutated cases (P=0.04). On univariate analysis, low p21WAF1/CIP1 expressers (相似文献