Anti-VEGF and anti-EGFR monoclonal antibodies (Mabs) in the first-line therapy for metastatic colorectal cancer: A meta-analysis

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Background: Anti-VEGF (VEGFi) and anti-EGFR (EGFRi) Mabs have increased options for patients with metastatic colorectal cancers (mCRC). The optimal class of antibody to combine with chemotherapy (Ctx) in the first-line treatment for mCRC remains less well defined. Results from randomized controlled trials (RCTs) are variable. Methods: Systematic review and meta-analysis were performed on the basis of previously released RCTs results. We searched the MEDLINE, Cochrane registry, proceedings from ASCO, ECCO, ESMO until 12/ 2008 for RCTs of Mabs in first-line mCRC. Summary statistics were pooled hazard ratio (HR) of progression-free survival (PFS), overall survival (OS) and odds ratio (OR) of Response rate (RR) and 60 day mortality (60d-M). Effect of k-ras wild type and mutation were stratified in trials involving EGFRi. Results: 7 trials with complete data were identified, including 3 Ctx ± VEGFi (AVF2107g, NO16966, JCO2005.05.122), n=2422; 2 Ctx±EGFRi (CRYSTAL, OPUS), n=1554; 2 Ctx/VEGFi ± EGFRi (PACCE, CAIRO-2), n=1789. Addition of VEGFi to Ctx offered 20–30% risk reduction in disease progression and overall mortality, a 30% higher RR and nonsignificant 60d-M. Benefit of EGFRi in addition to Ctx was seen only in k-ras wild type patients with 36% reduction in disease progression and doubling in RR. However, addition of EGFRi to Ctx+VEGFi caused increased risk of progression and death with no significant increase in RR and 60d-M. Conclusions: Benefit of VEGFi in addition to Ctx in first-line mCRC is well pronounced and persistent. In k-ras wild type patients, addition of EGFRi to Ctx results in significant increase in RR and PFS. Addition of EGFRi to Ctx+VEGFi appeared harmful regardless of k- ras status.

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Decreased methionine sulphoxide reductase A expression renders melanocytes more sensitive to oxidative stress: a possible cause for melanocyte loss in vitiligo

BACKGROUND

Methionine is one of the major targets of reactive oxygen species (ROS). It is readily oxidized to methionine-S-sulphoxide and methionine-R-sulphoxide, which can be reduced by methionine sulphoxide reductase (MSR) A and B, respectively. MSR represents a unique repair mechanism in the skin antioxidant network. It functions both as a protein repairer and as a ROS scavenger. However, the expression and activity of MSR are significantly reduced in vitiligo.

OBJECTIVES

To investigate whether the decreased expression of MSRA is one of the reasons why melanocytes are especially vulnerable to oxidative stress in vitiligo. Methods We downregulated MSRA expression in immortalized human epidermal melanocyte cell line PIG1 by using the short interfering RNA (siRNA)-targeted gene silencing method. We checked the changes in MSRA transcript and protein level by using reverse transcriptase-polymerase chain reaction and Western blot, respectively. Then we monitored the viability of MSRA-silenced melanocytes under oxidative stress. All statistical analysis was performed by unpaired two-tailed Student's t-test.

RESULTS

The siRNA specific for MSRA successfully suppressed MSRA expression in melanocytes. The lower MSRA expression in melanocytes led to an increased sensitivity to oxidative stress, resulting in more cell death. Furthermore, a remarkable loss of viable cells was found in MSRA-silenced melanocytes even in the absence of exogenously added oxidative stress.

CONCLUSIONS

MSRA is crucial for melanocytes to fight against oxidative stress in vitiligo. In addition, it is also important for normal cell survival. Any means to enhance MSRA appears to have therapeutic potential for the treatment of vitiligo.

[Two outbreaks of eosinophilic meningitis in Yunann (China) clinical, epidemiological and therapeutical issues]

Eosinophilic meningitis is an uncommon clinical entity, which is mostly caused by Angiostrongylus cantonensis, a nematode which parasitizes rat's lungs. Humans represent a dead-end in the parasite's lifecycle and become infected by ingesting snails, slugs or transport hosts. Due to uncontrolled proliferation and circulation of snails and rats, human angiostrongyliasis has emerged in new foci in continental China. The treatment, which relies upon a combination of albendazole and corticosteroids, is still a matter of debate. In order to assess the epidemiological features of two outbreaks which occurred in Kunming, capital of the Yunnan province, 2003 and 2005, along with the clinical and treatment issues, a retro-prospective study was carried out among thirty-four clinical cases of eosinophilic meningitis. Furthermore, a parasitological survey was carried out on randomized samples of snails sold in the markets of the city On admission, all cases were found to have acute headaches and an eosinophilic pleocytosis rate > 5% in the cerebro spinal fluid (CSF). All patients reported the consumption of raw snails Pomacea canaliculata, 14 days on average before the onset of headaches (range 1-30 days). Hyperesthesia due to radiculitis was observed in 68% of the cases and the meningitis syndrome was present in 41%. The average value of blood eosinophil count in CSF and in peripheral blood was 38% and 900/ml, respectively. Two treatment schedules were used (without randomization): one with progressive doses over 4 weeks; the other with immediate high doses for 10 days with 3 sessions separated by 14-day intervals. The results were compared by the Kaplan Meier log rank test. All the cases had a favorable evolution. The analysis suggested better effectiveness and tolerance of the albendazole - dexamethasone combination used at the highest dosage, namely 20mglkg daily and 10mg daily respectively. Eosinophilic meningitis appeared to be recently emerging or re-emerging in Kunming. Deep-rooted culinary habits of eating raw food, and large amount of snails sold on local markets (about one ton per day) provide ideal conditions for the outbreak, or occurrence of this disease. According to the resdjlts of this study Chinese local authorities should be urged to improve information to the population about the risks of eating raw snails, in order to strengthen the control of both rat and snail populations and reinforce the supervision of local food markets.

A sperm GPI-anchored protein elicits sperm-cumulus cross-talk leading to the acrosome reaction

The acrosome reaction has long been thought to be induced by the zona pellucida. Here we report the identification and function of a novel human sperm glycosylphosphatidylinositol (GPI)-anchored membrane protein, NYD-SP8. The release of the protein during sperm-egg interaction and its binding to the cumulus, the first layer of egg investment, elicits cross-talk between the gametes and produces calcium dependant release of progesterone, which lead to the acrosome reaction. An in vivo mouse model of NYD-SP8 immunization is also established showing a reduced fertility rate. Thus, contrary to accepted dogma, our study demonstrates for the first time that, prior to reaching the zona pellucida, sperm may release a surface protein that acts on the cumulus cells leading to the acrosome reaction, which may be important for determining the outcome of fertilization.

Kruppel-like transcription factor 5 promotes breast cell survival through pERK-mediated MKP-1 protein stabilization

Abstract #3019

Kruppel-like Factor 5 (KLF5) is a transcription factor promoting cell survival and tumorigenesis in multiple cancers. High level of KLF5 mRNA is associated with a shorter survival for breast cancer patients. However, the role of KLF5 and mechanism of KLF5 actions in breast cancer remain unclear. In this study, we found that KLF5 knockdown by siRNA in two basal type breast cell lines MCF10A and BT20 induces apoptosis, as indicated by loss of cell viability and cleaved PARP and caspase 3. Interestingly, a survival phosphotase, MKP-1, is downregulated at protein level by KLF5 ablation. Consistently, KLF5 over-expression increases the MKP-1 protein expression. However, MKP-1 is not a KLF5 direct target gene because the MKP-1 mRNA level is not regulated by KLF5. By the cycloheximide chase assays, we found that KLF5 decreases the MKP-1 protein degradation. However, KLF5 does not decrease the MKP-1 E3 ubiquitin ligase SKP2 expression. The ERK inhibitor U0126 specifically blocks the KLF5 induced MKP-1, suggesting that KLF5 up-regulates MKP-1 through activating ERK signaling. Finally, we demonstrated that MKP-1 over-expression blocks KLF5 knockdown induced apoptosis in MCF10A cells. These findings suggest that KLF5 is a survival factor which promotes breast cell survival partially through pERK-mediated MKP-1 stabilization. The KLF5-pERK-MKP-1 signaling axis may provide new therapeutic targets for invasive breast cancer.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 3019.

Krupple-like factor 5 promotes breast cancer proliferation through activating fibroblast growth factor-binding protein transcription

Abstract #4071

Breast cancer is the second leading cause of cancer death in U.S. women. The estrogen receptor negative basal breast cancer is usually invasive and the prognosis is poor. Kruppel-like Factor 5 (KLF5) is a zinc-finger transcription factor promoting cell proliferation, survival, cell cycle, and angiogenesis. High expression level of KLF5 has been shown to be associated with shorter breast cancer patient survival time. In our previous microarray studies, fibroblast growth factor binding protein (FGF-BP) is suggested to be one of the KLF5's downstream target genes in the TSU-Pr1 bladder cancer cell line. FGF-BP has been appreciated to be overexpressed in breast tumors and promotes tumorigenesis. To test whether KLF5 promotes cell proliferation through inducing FGF-BP gene transcription in breast cells, we first examined the KLF5 and FGF-BP protein levels in a panel of breast cell lines and found that KLF5 and FGF-BP are co-expressed in ER-negative basal breast cell lines. Over-expression of KLF5 by adenovirus dramatically increased the FGF-BP mRNA and protein expression in MCF7 and BT474. In contrast, KLF5 knockdown decreased the FGF-BP mRNA and protein expression in HCC1937, BT20, and SW527. Importantly, we found that FGF-BP, like KLF5, promotes cell proliferation in MCF10A, SW527 and TSU-Pr1 cells by H3-thymidine incorporation assay. Furthermore, we demonstrated that KLF5 activates the FGF-BP promoter through a putative KLF5 binding site by luciferase reporter assays. We further showed that KLF5 binds to the FGF-BP promoter in vitro by oligo pull down assays and in vivo by chromatin immunoprecipetation (CHIP) assays. These findings suggest that KLF5 may promote breast cancer cell proliferation through directly activating the FGF-BP mRNA transcription. This study will yield valuable insights into the mechanism of KLF5 induced cancer pathogenesis, and will result in useful diagnostic and therapeutic targets.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 4071.

Sensitive biomarker of polycyclic aromatic hydrocarbons (PAHs): urinary 1-hydroxyprene glucuronide in relation to smoking and low ambient levels of exposure

The study was conducted in a Chinese population with occupational or environmental exposures to polycyclic aromatic hydrocarbons (PAHs). A total of 106 subjects were recruited from coke-oven workers (workers), residents in a metropolitan area (residents) and suburban gardeners (gardeners). All subjects were monitored twice for their personal exposures to PAHs. The biological samples were collected for measurements of 1-hydroxypyrene (1-OHP) and cotinine in urine. The geometric means of personal exposure levels of pyrene, benz(a)anthracene (BaA) and benzo(a)pyrene (BaP) in workers were 1.470, 0.978 and 0.805 microg m-3, respectively. The corresponding levels in residents were 0.050, 0.034 and 0.025 microg m-3; and those in gardeners were 0.011, 0.020 and 0.008 microg m-3, respectively. The conjugate of 1-OHP with glucuronide (1-OHP-G) is the predominant form of pyrene metabolite in urine and it showed strong associations with exposures not only to pyrene, but also to BaA, BaP and total PAHs. Most importantly, a significant difference in 1-OHP-G was even detected between the subgroups with exposures to BaP at < 0.010 and > 0.010 but < 0.020 microg m-3, suggesting that 1-OHP-G is a good marker that can be used for the risk assessment of BaP exposure at levels currently encountered in ambient air. Furthermore, multiple regression analyses of 1-OHP-G on PAHs exposure indicated that cigarette smoke was a major confounding factor and should be considered and adjusted for while using 1-OHP to estimate PAHs exposure.

cGMP-independent anti-tumour actions of the inhibitor of soluble guanylyl cyclase, ODQ, in prostate cancer cell lines

BACKGROUND AND PURPOSE

Soluble guanylyl cyclase (sGC) is a receptor for nitric oxide that generates cGMP. This second messenger molecule has established roles in cellular physiology; however, less is known about its effects in tumour cells.

EXPERIMENTAL APPROACH

The effects of 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) and 4H-8-bromo-1,2,4-oxadiazolo(3,4-d)benz(b)(1,4)oxazin-1-one (NS2028), both selective sGC inhibitors on proliferation, death and migration were determined in prostate cancer cell lines.

KEY RESULTS

Western blot analysis confirmed the presence of alpha1 and beta1 subunits of sGC in LNCaP and PC-3 cells. Sodium nitroprusside (SNP) increased cGMP accumulation in LNCaP and PC-3, but not DU-145 cells. SNP-stimulated cGMP production in LNCaP cells was dose-dependently reduced by ODQ, with more than 90% inhibition being observed at 0.1 microM. ODQ activated caspase-3 in all three cell lines, but not in normal prostate epithelial cells, at concentrations over 10 muM. High concentrations of ODQ also promoted DNA fragmentation and nucleosome accumulation in the cytosol of LNCaP cells. Interestingly, the chemically related inhibitor, NS2028 was without effect on caspase-3. In addition, ODQ inhibited LNCaP, Du145 and PC-3 cell growth. Finally, although fibroblast growth factor-2 did not enhance cGMP levels in LNCaP cells, its ability to stimulate LNCaP motility was abolished by ODQ.

CONCLUSIONS AND IMPLICATIONS

These observations taken together suggest that the action of ODQ in LNCaP cells did not reflect sGC inhibition. We conclude that ODQ promotes cell death and inhibits growth and migration of prostate cancer cells and that these actions are independent of its effects on GMP levels.

Charge form factor of the neutron at low momentum transfer from the 2H-->(e-->,e'n)1H reaction

We report new measurements of the neutron charge form factor at low momentum transfer using quasielastic electrodisintegration of the deuteron. Longitudinally polarized electrons at an energy of 850 MeV were scattered from an isotopically pure, highly polarized deuterium gas target. The scattered electrons and coincident neutrons were measured by the Bates Large Acceptance Spectrometer Toroid (BLAST) detector. The neutron form factor ratio GEn/GMn was extracted from the beam-target vector asymmetry AedV at four-momentum transfers Q2=0.14, 0.20, 0.29, and 0.42 (GeV/c)2.

Design of annular photonic crystal slabs

We present the design of realistic annular photonic-crystal (APC) structures of finite thickness aiming to obtain a complete photonic bandgap (PBG). The APC is composed of dielectric rods and circular air holes in a triangular lattice such that each rod is centered within each hole. The optical and geometrical values of the structure are studied, and the interplay between various design parameters is highlighted. The coupled role of the inner-dielectric-rod radius, material types, and slab thickness is investigated. It is shown that the slab thickness is vital to obtain a complete photonic bandgap below the light line, and the specific value of the inner-dielectric-rod radius to sustain the maximum PBG if the hole radius is fixed at proper value is found.