Augmented antitumor activity of 5-fluorouracil by double knockdown of MDM4 and MDM2 in colon and gastric cancer cells.

Inactivation of the TP53 tumor suppressor gene is essential during cancer development and progression. Mutations of TP53 are often missense and occur in various human cancers. In some fraction of wild-type (wt) TP53 tumors, p53 is inactivated by upregulated murine double minute homolog 2 (MDM2) and MDM4. We previously reported that simultaneous knockdown of MDM4 and MDM2 using synthetic DNA-modified siRNAs revived p53 activity and synergistically inhibited in vitro cell growth in cancer cells with wt TP53 and high MDM4 expression (wtTP53/highMDM4). In the present study, MDM4/MDM2 double knockdown with the siRNAs enhanced 5-fluorouracil (5-FU)-induced p53 activation, arrested the cell cycle at G1 phase, and potentiated the antitumor effect of 5-FU in wtTP53/highMDM4 human colon (HCT116 and LoVo) and gastric (SNU-1 and NUGC-4) cancer cells. Exposure to 5-FU alone induced MDM2 as well as p21 and PUMA by p53 activation. As p53-MDM2 forms a negative feedback loop, enhancement of the antitumor effect of 5-FU by MDM4/MDM2 double knockdown could be attributed to blocking of the feedback mechanism in addition to direct suppression of these p53 antagonists. Intratumor injection of the MDM4/MDM2 siRNAs suppressed in vivo tumor growth and boosted the antitumor effect of 5-FU in an athymic mouse xenograft model using HCT116 cells. These results suggest that a combination of MDM4/MDM2 knockdown and conventional cytotoxic drugs could be a promising treatment strategy for wtTP53/highMDM4 gastrointestinal cancers.

The E1 protein of human papillomavirus type 16 is dispensable for maintenance replication of the viral genome.

Papillomavirus genomes are thought to be amplified to about 100 copies per cell soon after infection, maintained constant at this level in basal cells, and amplified for viral production upon keratinocyte differentiation. To determine the requirement for E1 in viral DNA replication at different stages, an E1-defective mutant of the human papillomavirus 16 (HPV16) genome featuring a translation termination mutation in the E1 gene was used. The ability of the mutant HPV16 genome to replicate as nuclear episomes was monitored with or without exogenous expression of E1. Unlike the wild-type genome, the E1-defective HPV16 genome became established in human keratinocytes only as episomes in the presence of exogenous E1 expression. Once established, it could replicate with the same efficiency as the wild-type genome, even after the exogenous E1 was removed. However, upon calcium-induced keratinocyte differentiation, once again amplification was dependent on exogenous E1. These results demonstrate that the E1 protein is dispensable for maintenance replication but not for initial and productive replication of HPV16.

Potent in vitro and in vivo antitumor effects of MDM2 inhibitor nutlin-3 in gastric cancer cells.

The tumor suppressor gene p53 is the most frequently mutated gene in human cancers. However, its mutation rate is relatively low in gastric cancer compared with other cancers. In this study, we investigated the mechanisms underlying the antitumor effects of nutlin-3, an inhibitor of human homolog of murine double minute 2 (MDM2). MDM2 is a negative regulator of p53. Four gastric cancer cell lines with wild-type p53 (wt p53) and three with mutant-type p53 (mt p53) were analyzed for MDM2 and MDM4 expression by immunoblotting, and for their gene amplification by quantitative real-time PCR. Moreover, the viability of cells exposed to nutlin-3 was examined by WST-8 assay, and the expression of p53 and its downstream genes was analyzed by immunoblotting. Nutlin-3 stabilized p53 and increased the expression of p21(WAF1) and Noxa, and cleaved poly (ADP)-ribose polymerase regardless of the pre-expression levels of MDM2 and MDM4 in gastric cancer cells with wt p53. Flow cytometry revealed that nutlin-3 arrested the cell cycle in G(1) phase and induced apoptosis in the cell lines. These nutlin-3 effects were not observed in the cell lines with mt p53. Nutlin-3 exerted additive or synergistic cytotoxicity in combination with 5-fluorouracil or cisplatin in most cell lines with wt p53. An in vivo antitumor effect of nutlin-3 alone and its additive augmentation by 5-fluorouracil were confirmed in an MDM2 overexpressed xenograft tumor model. Nutlin-3 showed potent antitumor activity against human gastric cancer cells with wt p53 and shows promise as a single agent and in combination with conventional anticancer drugs.

MDM4 as a Prognostic Factor for Patients With Gastric Cancer With Low Expression of p53.

BACKGROUND/AIM: The oncoproteins murine double minute (MDM) 2 and MDM4 inactivate tumor-suppressor protein p53. Their mutual relationship with the prognosis of gastric cancer (GC) remains unknown. PATIENTS AND METHODS: Expression of MDM2, MDM4, and p53 in tumors of 241 patients with GC were evaluated immunohistochemically. Effects of overexpression of MDM4 on tumor-growth properties and sensitivity to cytotoxic drugs were investigated using NUGC4 human GC cell line. RESULTS: High expression of p53 was associated with poor overall survival in the whole population. Among 173 patients with low expression of p53 (implying nonmutation), high expression of MDM4 was an independent factor of poor prognosis in both stage I-III and IV, but of MDM2 was not. MDM4-transduced NUGC4 cells formed twice as many colonies and had a higher 50% inhibitory concentration for 5-fluorouracil and oxaliplatin than did the control cells. CONCLUSION: MDM4 expression is a factor conferring poor prognosis in patients with GC with low expression of p53 and may confer drug resistance.

Enhanced G1 arrest and apoptosis via MDM4/MDM2 double knockdown and MEK inhibition in wild-type TP53 colon and gastric cancer cells with aberrant KRAS signaling.

Murine double minute homolog 2 (MDM2) is an oncoprotein that induces p53 degradation via ubiquitin-ligase activity. MDM4 cooperates with MDM2-mediated p53 degradation, directly inhibiting p53 transcription by binding to its transactivation domain. Our previous study reported that the simultaneous inhibition of MDM2 and MDM4 using nutlin-3 (an inhibitor of the MDM2-p53 interaction) and chimeric small interfering RNA with DNA-substituted seed arms (named chiMDM2 and chiMDM4) more potently activated p53 than the MDM2 or MDM4 inhibitor alone and synergistically augmented antitumor effects in various types of cancer cells with the wild-type (wt) TP53. Recently, the synergism of MDM2 and mitogen-activated protein kinase kinase (MEK) inhibitors has been demonstrated in wt TP53 colorectal and non-small cell lung cancer cells harboring mutant-type (mt) KRAS. The current study examined whether chiMDM4 augmented the synergistic antitumor effects of MDM2 and MEK inhibition using chiMDM2 or nutlin-3 and trametinib, respectively. ChiMDM2 and trametinib used in combination demonstrated a synergistic antitumor activity in HCT116 and LoVo colon cancer cells, and SNU-1 gastric cancer cells harboring wt TP53 and mt KRAS. Furthermore, chiMDM4 synergistically enhanced this combinational effect. Similar results were observed when nutlin-3 was used instead of chiMDM2. MDM4/MDM2 double knockdown combined with trametinib treatment enhanced G1 arrest and apoptosis induction. This was associated with the accumulation of p53, suppression of phosphorylated-extracellular signal-regulated kinase 2, inhibition of retinoblastoma phosphorylation, suppression of E2F1-activated proteins, and potent activation of pro-apoptotic proteins, such as Fas and p53 upregulated modulator of apoptosis. The results inidcated that the triple inhibition of MDM4, MDM2 and MEK exerted a potent antitumor effect in wt TP53 colon and gastric cancer cells with mt KRAS. Simultaneous activation of p53 and inhibition of aberrant KRAS signaling may be a rational treatment strategy for gastrointestinal tumors.

Functional dissection of siRNA sequence by systematic DNA substitution: modified siRNA with a DNA seed arm is a powerful tool for mammalian gene silencing with significantly reduced off-target effect.

Short interfering RNA (siRNA)-based RNA interference (RNAi) is widely used for target gene knockdown in mammalian cells. To clarify the position-dependent functions of ribonucleotides in siRNA, siRNAs with various DNA substitutions were constructed. The following could be simultaneously replaced with DNA without substantial loss of gene-silencing activity: the seed arm, which occupies positions 2-8 from the 5'end of the guide strand; its complementary sequence; the 5'end of the guide strand and the 3'overhang of the passenger strand. However, most part of the 3' two-thirds of the guide strand could not be replaced with DNA, possibly due to binding of RNA-recognition proteins such as TRBP2 and Ago2. The passenger strand with DNA in the 3'end proximal region was incapable of inducing off-target effect. Owing to lesser stability of DNA-RNA hybrid than RNA duplex, modified siRNAs with DNA substitution in the seed region were, in most cases, incapable to exert unintended gene silencing due to seed sequence homology. Thus, it may be possible to design DNA-RNA chimeras which effectively silence mammalian target genes without silencing unintended genes.

Myeloperoxidase is a key regulator of oxidative stress mediated apoptosis in myeloid leukemic cells.

PURPOSE: We reported previously that reactive oxygen species (ROS) are key mediators of apoptosis induced by a polyphenol, (-)-epigallocatechin-3-gallate (EGCG), in myeloid leukemic cells. This study aimed to further examine the mechanism of ROS-mediated apoptosis induced by EGCG and its relationship to the heme enzyme myeloperoxidase (MPO). EXPERIMENTAL DESIGN: We established stably transfected K562 cells expressing wild-type and mutant MPO. Then, sensitivity against EGCG and other ROS-inducing agent was examined and further investigated the detailed molecular mechanism of ROS-inducing apoptosis in MPO-positive leukemic cells. RESULTS: EGCG rapidly induced apoptosis in MPO-positive leukemia cells. Preincubation of myeloid leukemic cells with the MPO-specific inhibitor, 4-aminobenzoic acid hydrazide, and the heme biosynthesis inhibitor, succinylacetone, resulted in inhibition of the intracellular MPO activity, ROS production, and induction of apoptosis following addition of EGCG. Overexpression of MPO sensitized EGCG-resistant K562 cells to apoptosis induced by EGCG. In contrast, an enzymatically inactive MPO mutant-expressing K562 cell could not respond to EGCG, suggesting that MPO is important for determining the sensitivity to EGCG-induced oxidative stress. Hypochlorous acid scavengers and the hydroxyl radical (.OH) scavenger inhibited EGCG-induced apoptosis in myeloid leukemic cells. The fluorescence intensity of both aminophenyl fluorescein- and hydroxyphenyl fluorescein-loaded myeloid leukemic cells significantly increased on stimulation with EGCG, indicating that EGCG generated highly toxic ROS in myeloid leukemic cells. CONCLUSIONS: These results indicated that highly toxic ROS such as .OH generated via the hydrogen peroxide/MPO/halide system induce apoptosis and that ROS may be the direct mediators of EGCG-induced apoptosis in MPO-positive leukemic cells.

[Q fever in hospital-acquired pneumonia].

We studied the effects of Q fever in hospital-acquired pneumonia. The subjects consisted of 121 cases with hospital-acquired pneumonia treated during the period from December 2004 till June 2007. Q fever was diagnosed using a PanBio Coxiella burnetii ELISA test kit. There were no patients with acute infection by Coxiella burnetii. It is concluded that C. burnetii cannot induce onset of hospital-acquired pneumonia.

[Clinical effects of intravenous ciprofloxacin on community-acquired pneumonia with positive Immunocard Mycoplasma test results].

We studied the clinical effects of intravenous ciprofloxacin (CPFX) on community-acquired pneumonia in patients with positive Immunocard Mycoplasma test results. The subjects were 35 patients (59.4 +/- 24.8 years old) with community-acquired pneumonia with positive Immunocard Mycoplasma test results. We infused CPFX 300mg copy intravenously twice daily for 3-14 days. It was effective in 33 of 35 patients, with an efficacy rate of 94.3%. Adverse reactions consisted of itching in 2 patients, malaise in 2 patients, drug eruption in 1 patient, elevation of GPT in 1 patient and elevation of BUN in 1 patient, but all were mild. We conclude that intravenous CPFX is useful for community-acquired pneumonia in case with positive Immunocard Mycoplasma test results.

[Positive phase periods of ImmunoCard Mycoplasma tests].

We evaluated the positive phase period of ImmunoCard Mycoplasma tests. The subjects were 74 penumonia patients (male : 38, female : 36, 17-94 years old) with positive ImmunoCard Mycoplasma tests. ImmunoCard Mycoplasma tests were performed every week for 8 weeks later, then every 4 weeks until negative conversion. The positive phase period was within a week in 30 of 74 patients (40.5%) and within 4 weeks in 52 patients (70.3%). In each generation the positive phase period of the most patients was within a week. The positive phase period of the elderly had no tendency to be longer than that of the young patients. These results indicated that about half of the patients with positive ImmunoCard Mycoplasma tests showed Mycoplasma infection which occurred within the past 1 week.

[Study of the cases with multidrug-resistant Pseudomonas aeruginosa by sputum culture].

We evaluated the clinical features of multidrug-resistant Pseudomonas aeruginosa cases determined by sputum culture between April, 2005 and December, 2006. The clinical features of most cases were: (1) pneumonia in the elderly with cerebrovascular diseases, (2) previous administration of carbapenems and antipseudomonal cephems, (3) PIPC, CAZ and ISP sensitve MDRP, (4) MRSA was isolated concurrently, (5) not necessary of therapy against MDRP, (6) good outcome.

[Case of multiple intrapulmonary lymph nodes].

A 45-year-old man who had hypertension, hyperthyroidism, and bronchial asthma was admitted to our hospital because of a low-grade fever and chest pain. The physical findings and laboratory data were almost all within normal limits except for evidence of mild inflammation and liver dysfunction. The chest X-ray findings seemed normal, but a computed tomography (CT) scan showed multiple nodules in both lower lung fields. We suspected the cryptococcosis or lung cancer. Biopsy by video-assisted thoracoscopic surgery (VATS) yielded a diagnosis of multiple intrapulmonary lymph nodes. In cases with the above radiologic findings, careful attention should be paid to making the differential diagnosis between intrapulmonary lymph nodes and primary lung cancer. The promotion of diagnostic imaging and advances in techniques have made it easier to identify small peripheral nodules in the lungs, and we now know of their existence. Solitary intrapulmonary lymph nodes are encountered frequently, but multiple or increasing numbers of nodes, as in our case, are very rare. Moreover, because cases with elevated CEA levels have been reported, differentiation from lung cancer appears to be important.

[Testing for Mycoplasma pneumonia using the ImmunoCard Mycoplasma rapid test].

We evaluated the effectiveness of ImmunoCard Mycoplasma rapid tests in all patients admitted with community-acquired pneumonia (CAP) between January, 2004 and December, 2005. ImmunoCard Mycoplasma rapid tests were performed on the 1st day of admission and we analyzed the frequency of positive cases among CAP cases according to month and age. A total of 82 of 270 (33.7%) and 41 of 257 (16.0%) were positive among CAP cases in 2004 and 2005, respectively. More positive cases were seen between spring and early summer and in cases aged 70 years or more, especially those over 80 years old. These results indicated that further evaluation is required among positive cases in elder group.

p27KIP1 and GATA-1 are potential downstream molecules in activin A-induced differentiation and apoptosis pathways in CML cells.

p27KIP1 is known as a regulator of cellular differentiation and apoptosis in human cancer cells. We have previously reported that human chronic myeloid leukemia (CML) KU812 and K562 cells show inhibited cellular proliferation in response to treatment with activin A, a member of TGF-beta superfamily. Apoptosis and erythroid differentiation can be induced in KU812 and K562 cells, respectively. We report herein that activin A induced the expression of p27KIP1 in CML cells along with the induction of cellular differentiation and apoptosis. There are putative binding sequences of erythroid-related transcription factor GATA-1 in the promoter region of the human p27KIP1 gene. Expression of GATA-1 protein in activin A-treated KU812 and K562 cells showed dissimilar regulation in these two cell lines. Induction of p27KIP1 was commonly observed, but it did not correspond to the expression levels of GATA-1 in either line of activin A-treated CML cells. In addition, ERK protein was rapidly and transiently activated with activin A in both types of CML cells, suggesting that phosphorylation of ERK is required for activin A signaling in CML cells. These results indicate that both p27KIP1 induction and regulation of GATA-1 play essential roles in activin A-induced erythroid differentiation and apoptosis.

Induction of apoptosis in leukemic cells by homovanillic acid derivative, capsaicin, through oxidative stress: implication of phosphorylation of p53 at Ser-15 residue by reactive oxygen species.

Capsaicin (N-vanillyl-8-methyl-1-nonenamide) is a homovanillic acid derivative found in pungent fruits. Several investigators have reported the ability of capsaicin to inhibit events associated with the promotion of cancer. However, the effects of capsaicin on human leukemic cells have never been investigated. We investigated the effects of capsaicin on leukemic cells in vitro and in vivo and further examined the molecular mechanisms of capsaicin-induced apoptosis in myeloid leukemic cells. Capsaicin suppressed the growth of leukemic cells, but not normal bone marrow mononuclear cells, via induction of G(0)-G(1) phase cell cycle arrest and apoptosis. Capsaicin-induced apoptosis was in association with the elevation of intracellular reactive oxygen species production. Interestingly, capsaicin-sensitive leukemic cells were possessed of wild-type p53, resulting in the phosphorylation of p53 at the Ser-15 residue by the treatment of capsaicin. Abrogation of p53 expression by the antisense oligonucleotides significantly attenuated capsaicin-induced cell cycle arrest and apoptosis. Pretreatment with the antioxidant N-acetyl-L-cystein and catalase, but not superoxide dismutase, completely inhibited capsaicin-induced apoptosis by inhibiting phosphorylation of Ser-15 residue of p53. Moreover, capsaicin effectively inhibited tumor growth and induced apoptosis in vivo using NOD/SCID mice with no toxic effects. We conclude that capsaicin has potential as a novel therapeutic agent for the treatment of leukemia.

[Clinical effect of continuous infusion of meropenem on bacterial pneumonia in the elderly].

We studied the clinical effect of continuous infusion over 24 hours of meropenem (MEPM) on bacterial pneumonia in the elderly (over 65). The subjects were 26 patients (community-acquired pneumonia: moderate, n = 9; severe, n= 4; hospital-acquired pneumonia: group III, n = 13) whose performance status was 3 or 4. MEPM 1.0g/day was infused continuously for 7-14 days, and its clinical efficacy, bacteriological efficacy, and side effects were examined prospectively. It was effective in 23 of the 26 patients (community-acquired pneumonia: moderate, 8/9; severe, 3/4; hospital-acquired pneumonia: group III, 12/13; efficacy rate: 88.5%). Bactericidal effects were obtained in 3 strains of Klebsiella pneumoniae, 2 strains of Streptococcus pneumoniae, 2 strains of methicillin-sensitive Staphlococcus aureus, 1 strain of Streptococcus agalactiae and 1 strain of Proteus mirabilis, but not in 2 strains of methicillin-resistant S. aureus, 1 strain of Pseudomonas aeruginosa and 1 strain of Serratia marcescens. Mild abnormal laboratory findings were observed in 2 patients: elevation of GPT, gamma-GTP, BUN and elevation of ALP. Based on the above, continuous infusion of MEPM on bacterial pneumonia in the elderly obtained excellent clinical effects. Further study is needed to compare the efficacy of continuous versus intermittent administration of MEPM.

Role of TGF-beta family in osteoclastogenesis induced by RANKL.

Recent studies have revealed that both transforming growth factor-beta (TGF-beta) and activin A play pivotal roles in osteoclastogenesis. In this report, we show that the effect of TGF-beta family members, TGF-beta1 and activin A, but not BMP-2, enhance multinucleated osteoclast-like cell (OCL) formation induced by receptor activator of NF-kappaB ligand (RANKL) in isolated bone marrow macrophages and monocytic cell line, RAW264.7. TGF-beta1 and activin A caused the growth suppression and concomitant expression of tartrate-resistant acid phosphatase (TRAP) and c-Src, without inducing syncytium formation or increasing the survival rate in RAW264.7 cells. Although TGF-beta1 and activin A had no effect on NF-kappaB and JNK activities, these factors enhanced the expression of JunB, a component of the AP-1 transcriptional complex. These results suggest that TGF-beta1 and activin A may function as commitment factors in osteoclastic differentiation, not as a crucial component for terminal differentiation to form multinucleated OCLs nor in OCL survival.

Growth/differentiation factor-5 induces growth arrest and apoptosis in mouse B lineage cells with modulation by Smad.

Bone morphogenetic proteins, including growth/differentiation factor-5 (GDF-5), are multifunctional cytokines. Recent studies of intracellular signal transduction mechanisms for the transforming growth factor-beta superfamily have focused on Smad proteins. However, scant attention has been given to the mechanism by which GDF-5 exerts its negative growth effect on immunological competent cells. In the present study, we demonstrated that GDF-5 induced cell cycle arrest in the G1 phase before the appearance of apoptosis in mouse B cell hybridoma HS-72 cells, while the ectopic expression of Smad6 and Smad7 in HS-72 cells suppressed the GDF-5-induced G1 cell cycle arrest by abolishing the expression of p21(CIP-1/WAF-1) and hypophosphorylation of retinoblastoma protein. Moreover, we found that Smad6 and Smad7 suppressed GDF-5-induced apoptosis in HS-72 cells. These findings indicated that Smad6 and Smad7 exhibit inhibitory effects toward GDF-5-mediated signaling in B lineage cells.

Induction of apoptosis in human myeloid leukemic cells by 1'-acetoxychavicol acetate through a mitochondrial- and Fas-mediated dual mechanism.

PURPOSE: The purpose of this investigation was to determine the antileukemic effects of 1'-acetoxychavicol acetate (ACA) obtained from rhizomes of the commonly used ethno-medicinal plant Languas galanga (Zingiberaceae). EXPERIMENTAL DESIGN: We evaluated the effects of ACA on various myeloid leukemic cells in vitro and in vivo. We further examined the molecular mechanisms of ACA-induced apoptosis in myeloid leukemic cells. RESULTS: Low-dose ACA dramatically inhibited cellular growth of leukemic cells by inducing apoptosis. Because NB4 promyelocytic leukemic cells were most sensitive to ACA, we used NB4 cells for further analyses. Production of reactive oxygen species triggered ACA-induced apoptosis. ACA-induced apoptosis in NB4 cells was in association with the loss of mitochondrial transmembrane potential (DeltaPsim) and activation of caspase-9, suggesting that ACA-induced death signaling is mediated through a mitochondrial oxygen stress pathway. In addition, ACA activated Fas-mediated apoptosis by inducing of casapse-8 activity. Pretreatment with the thiol antioxidant N-acetyl-L-cysteine (NAC) did not inhibit caspase-8 activation, and the antagonistic anti-Fas antibody ZB4 did not block generation of reactive oxygen species, indicating that both pathways were involved independently in ACA-induced apoptosis. Furthermore, ACA had a survival advantage in vivo in a nonobese diabetic/severe combined immunodeficient mice leukemia model without any toxic effects. CONCLUSIONS: We conclude that ACA induces apoptosis in myeloid leukemic cells via independent dual pathways. In addition, ACA has potential as a novel therapeutic agent for the treatment of myeloid leukemia.

[Q fever in acute exacerbation of chronic lower respiratory tract infection].

We studied the effect of Q fever in acute exacerbation of chronic lower respiratory tract infection. The subjects consisted of 80 cases with acute exacerbation of chronic lower respiratory tract infection treated during the period from March 2002 till October 2004. Q fever was diagnosed using a PanBio Coxiella burnetii ELISA test kit. Two cases (2.5%) were positive for IgM in the acute stage, and were diagnosed as having acute infection by C. burnetii. They were elderly women with bronchiectasis, aged 76 and 82. They had no history of keeping cats or dogs, but the onset of acute exacerbation of chronic lower respiratory tract infection was June and March which is the breeding seasons for cats and dogs. Acute exacerbation of chronic lower respiratory tract infection were considerd to be a mixed infection with Pseudomonas aeruginosa (the 76-year-case) and Haemophilus influenzae (the 82-year-case). It is concluded that C. burnetii can induce exacerbation of chronic lower respiratory tract infection, their cases were considerd to be mixed infection with C. burnetii and other bacteria.