Targeting Wnt signaling for improved glioma immunotherapy

Introduction

Despite aggressive standard-of-care therapy, including surgery, radiation, and chemotherapy, glioblastoma recurrence is almost inevitable and uniformly lethal. Activation of glioma-intrinsic Wnt/β-catenin signaling is associated with a poor prognosis and the proliferation of glioma stem-like cells, leading to malignant transformation and tumor progression. Impressive results in a subset of cancers have been obtained using immunotherapies including anti-CTLA4, anti-PD-1, and anti-PD-L1 or chimeric antigen receptor (CAR) T cell therapies. However, the heterogeneity of tumors, low mutational burden, single antigen targeting, and associated antigen escape contribute to non-responsiveness and potential tumor recurrence despite these therapeutic efforts. In the current study, we determined the effects of the small molecule, highly specific Wnt/CBP (CREB Binding Protein)/β-catenin antagonist ICG-001, on glioma tumor cells and the tumor microenvironment (TME)-including its effect on immune cell infiltration, blood vessel decompression, and metabolic changes.

Methods

Using multiple glioma patient-derived xenografts cell lines and murine tumors (GL261, K-Luc), we demonstrated in vitro cytostatic effects and a switch from proliferation to differentiation after treatment with ICG-001.

Results

In these glioma cell lines, we further demonstrated that ICG-001 downregulated the CBP/β-catenin target gene Survivin/BIRC5-a hallmark of Wnt/CBP/β-catenin inhibition. We found that in a syngeneic mouse model of glioma (K-luc), ICG-001 treatment enhanced tumor infiltration by CD3+ and CD8+ cells with increased expression of the vascular endothelial marker CD31 (PECAM-1). We also observed differential gene expression and induced immune cell infiltration in tumors pretreated with ICG-001 and then treated with CAR T cells as compared with single treatment groups or when ICG-001 treatment was administered after CAR T cell therapy.

Discussion

We conclude that specific Wnt/CBP/β-catenin antagonism results in pleotropic changes in the glioma TME, including glioma stem cell differentiation, modulation of the stroma, and immune cell activation and recruitment, thereby suggesting a possible role for enhancing immunotherapy in glioma patients.

Differential Kat3 Coactivator Usage Regulates Brain Metabolism and Neuronal Differentiation

INTRODUCTION

Our previous work has demonstrated significant effects on the oxidative stress response, mitochondrial function, and oxidative phosphorylation in the livers and intestines of p300 S89A knockin (S89AKI) mice. We now show that this mutation is also associated with brain metabolic defects and neuronal differentiation.

METHODS

p300 S89A edited P19 cells, and S89AKI mice demonstrated metabolic and neuronal differentiation defects based on proteomic, cell biological and PET imaging studies.

RESULTS

The metabolic and differentiation defects associated with the p300 S89A knockin mutation could be corrected both in vitro and in vivo utilizing the small molecule CBP/beta-catenin antagonist ICG-001.

CONCLUSION

Rebalancing the equilibrium between CBP/β-catenin versus p300/β-catenin associated transcription, utilizing the small molecule CBP/beta-catenin antagonist ICG-001, enhances mitochondrial oxidative phosphorylation, metabolic function, and neuronal differentiation and may be able to ameliorate the cognitive decline seen in neurodegenerative disorders, including Alzheimer's Disease.

Differential Kat3 Usage Orchestrates the Integration of Cellular Metabolism with Differentiation

Simple Summary

The coupling of metabolism with cellular status is critically important and highly evolutionarily conserved. However, how cells coordinate metabolism with transcription as they change their status is not clear. Utilizing multiomic and functional studies, we now demonstrate the dichotomous roles of the Kat3 coactivators CBP and p300 and, in particular, their extreme N-termini, in coordinating cellular metabolism with cell differentiation. Using multiple in vitro and in vivo systems, our study sheds new light on metabolic regulation in homeostasis and disease, including cancer.

Abstract

The integration of cellular status with metabolism is critically important and the coupling of energy production and cellular function is highly evolutionarily conserved. This has been demonstrated in stem cell biology, organismal, cellular and tissue differentiation and in immune cell biology. However, a molecular mechanism delineating how cells coordinate and couple metabolism with transcription as they navigate quiescence, growth, proliferation, differentiation and migration remains in its infancy. The extreme N-termini of the Kat3 coactivator family members, CBP and p300, by far the least homologous regions with only 66% identity, interact with members of the nuclear receptor family, interferon activated Stat1 and transcriptionally competent β-catenin, a critical component of the Wnt signaling pathway. We now wish to report based on multiomic and functional investigations, utilizing p300 knockdown, N-terminal p300 edited and p300 S89A edited cell lines and p300 S89A knockin mice, that the N-termini of the Kat3 coactivators provide a highly evolutionarily conserved hub to integrate multiple signaling cascades to coordinate cellular metabolism with the regulation of cellular status and function.

p300 Serine 89: A Critical Signaling Integrator and Its Effects on Intestinal Homeostasis and Repair

Simple Summary

Given their high degree of identity and even greater similarity at the amino acid level, Kat3 coactivators, CBP (Kat3A) and p300 (Kat3B), have long been considered redundant. We describe the generation of novel p300 S89A knock-in mice carrying a single site directed amino acid mutation in p300, changing the highly evolutionarily conserved serine 89 to alanine, thus enhancing Wnt/CBP/catenin signaling (at the expense of Wnt/p300/catenin signaling). p300 S89A knock-in mice exhibit multiple organ system, immunologic and metabolic differences, compared with their wild type counterparts. In particular, these p300 S89A knock-in mice are highly sensitive to intestinal injury resulting in colitis which is known to significantly predispose to colorectal cancer. Our results highlight the critical role of this region in p300 as a signaling nexus and provide further evidence that p300 and CBP are non-redundant, playing definite and distinctive roles in development and disease.

Abstract

Differential usage of Kat3 coactivators, CBP and p300, by β-catenin is a fundamental regulatory mechanism in stem cell maintenance and initiation of differentiation and repair. Based upon our earlier pharmacologic studies, p300 serine 89 (S89) is critical for controlling differential coactivator usage by β-catenin via post-translational phosphorylation in stem/progenitor populations, and appears to be a target for a number of kinase cascades. To further investigate mechanisms of signal integration effected by this domain, we generated p300 S89A knock-in mice. We show that S89A mice are extremely sensitive to intestinal insult resulting in colitis, which is known to significantly increase the risk of developing colorectal cancer. We demonstrate cell intrinsic differences, and microbiome compositional differences and differential immune responses, in intestine of S89A versus wild type mice. Genomic and proteomic analyses reveal pathway differences, including lipid metabolism, oxidative stress response, mitochondrial function and oxidative phosphorylation. The diverse effects on fundamental processes including epithelial differentiation, metabolism, immune response and microbiome colonization, all brought about by a single amino acid modification S89A, highlights the critical role of this region in p300 as a signaling nexus and the rationale for conservation of this residue and surrounding region for hundreds of million years of vertebrate evolution.

The Mode of Stem Cell Division Is Dependent on the Differential Interaction of β-Catenin with the Kat3 Coactivators CBP or p300

Normal long-term repopulating somatic stem cells (SSCs) preferentially divide asymmetrically, with one daughter cell remaining in the niche and the other going on to be a transient amplifying cell required for generating new tissue in homeostatic maintenance and repair processes, whereas cancer stem cells (CSCs) favor symmetric divisions. We have previously proposed that differential β-catenin modulation of transcriptional activity via selective interaction with either the Kat3 coactivator CBP or its closely related paralog p300, regulates symmetric versus asymmetric division in SSCs and CSCs. We have previously demonstrated that SSCs that divide asymmetrically per force retain one of the dividing daughter cells in the stem cell niche, even when treated with specific CBP/β-catenin antagonists, whereas CSCs can be removed from their niche via forced stochastic symmetric differentiative divisions. We now demonstrate that loss of p73 in early corticogenesis biases β-catenin Kat3 coactivator usage and enhances β-catenin/CBP transcription at the expense of β-catenin/p300 transcription. Biased β-catenin coactivator usage has dramatic consequences on the mode of division of neural stem cells (NSCs), but not neurogenic progenitors. The observed increase in symmetric divisions due to enhanced β-catenin/CBP interaction and transcription leads to an immediate increase in NSC symmetric differentiative divisions. Moreover, we demonstrate for the first time that the complex phenotype caused by the loss of p73 can be rescued in utero by treatment with the small-molecule-specific CBP/β-catenin antagonist ICG-001. Taken together, our results demonstrate the causal relationship between the choice of β-catenin Kat3 coactivator and the mode of stem cell division.

Characterization of Imatinib Resistant CML Leukemic Stem/Initiating Cells and Their Sensitivity to CBP/Catenin Antagonists

BACKGROUND AND OBJECTIVE

The development of the tyrosine kinase inhibitor Imatinib (IM) represents a milestone in CML (Chronic Myeloid Leukemia) treatment. However, it is not curative and patients develop IM resistance. IM resistance has been previously correlated with the emergence of drug-resistant LIC/LSC (Leukemia Initiating Cell/Leukemia Stem Cell) and increased nuclear catenin levels and enhanced Wnt signaling. It has been demonstrated previously that drug resistant CML LIC/LSC can be safely eliminated both in vitro and in vivo via disruption of the CBP/catenin interaction, utilizing the highly biochemically selective small molecule CBP/catenin antagonist ICG- 001.

METHODS

Here, we utilized an in vitro IM selection of primary CML patients' samples to identify drug-resistant LIC/LSC populations. In this report, we characterized the drug-resistant CML LIC/LSC population using FACS, Smartchip qPCR and colony assays to analyze cell surface markers, transcriptomics and function.

RESULTS

As opposed to previous characterization of the CML leukemic stem cell population as being either CD34+CD38- or CD34+CD38+, the in vitro selected Imatinib resistant (IM-R) CML LSC population was consistently CD34-CD38-. In Long-Term Culture Initiating Cell assay (LTC-IC, a surrogate assay for long term repopulating stem cells), our results suggest that the CBP/catenin antagonist ICG- 001 sensitizes LIC/LSC to IM treatment by forced differentiative elimination of the CML LIC/LSC population.

CONCLUSION

In vitro selected IM resistant cells are negative for both CD34 and CD38 by FACS analysis. These cells acquire CD34/CD38 expression after co-culture with stromal cells. CBP/catenin antagonist ICG-001 facilitates IM function in eliminating these cells.

Abstract 2614: Macrophage erythroblast attacher (MAEA) polymorphisms are associated with clinical outcome in TRIBE study mCRC patients treated with 5-fluorouracil/bevacizumab-based therapy

Background: Macrophage erythroblast attacher (MAEA) also known as Emp (Erythroblast macrophage protein) plays indispensable role in erythroblast and macrophage development and targeted disruption of Emp is embryonically lethal (Soni et al., JBC 2006). Recently, down-regulation of Emp was implicated in abnormal cell motility and higher expression of mitogen-activated protein kinase 1 (MAPK 1) and thymoma viral proto-oncogene 1 (Akt 1) (Gulnaz et. al., BCMD 2016). Our preliminary studies, shows that higher expression of MAEA is associated with longer colorectal cancer (CRC) patient survival. We tested two MAEA polymorphisms (rs13149952 and rs1128427), whether these are correlated with clinical outcome in mCRC treated with 5-Fluorouracil / Bevacizumab based therapy. Methods: Genomic DNA was isolated from blood samples of two cohorts of mCRC patients. Cohort 1 included 227 patients treated with FOLFIRI/BEV (TRIBE trial Arm A, RAS wildtype/mutant=55/116, median age=60 years old, median follow-up period=49.3 months). Cohort 2 had 229 patients treated with FOLFOXIRI/BEV (TRIBE trial Arm B, RAS wildtype/mutant=60/115, median age=60 years old, median follow-up period=46.6 months). PCR-based direct Sanger sequencing was used to determine polymorphism. Results: Our results showed that MAEA rs1128427 in TRIBE arm A patients with RAS mutant tumors having any C genotype was significantly associated with longer overall survival as compared to TT genotype in univariate analysis {25.9 vs 18.8 months, HR(95% CI)=0.61(0.38,0.98), p=0.036}. In TRIBE arm B cohort, MAEA rs1128427 in patients with RAS mutant tumors carrying CC genotype showed significantly longer overall survival than patients with any T allele in both univariate and multivariable analyses {33.4 vs 25 months, uni: HR(95% CI)=0.57(0.34,0.95), p=0.028; multi: HR(95% CI)=0.56(0.32,0.96), p=0.034}. Conclusion: Our findings suggest for the first time, that polymorphisms in MAEA may predict the clinical outcome in Bevacizumab based therapies. Further prospective studies are warranted.

Citation Format: Shivani Soni, Yuji Miyamoto, Wu Zhang, Martin D. Berger, Shu Cao, Elizabeth Melendez, Alberto Puccini, Madiha Naseem, Ryuma Tokunaga, Francesca Battaglin, Michelle Mcskane, Chiara Cremolini, Alfredo Falcone, Fotios Loupakis, Heinz-Josef Lenz. Macrophage erythroblast attacher (MAEA) polymorphisms are associated with clinical outcome in TRIBE study mCRC patients treated with 5-fluorouracil/bevacizumab-based therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2614.

Genetic polymorphisms of CCL5 and CCR5 to predict efficacy of cetuximab-based treatment in metastatic colorectal cancer patients depending on primary tumor location

3594

Background: EGFR signaling blockade increases CCL5 expression, which attracts with tumor-infiltrating leukocytes regulating either the host-derived anti-tumor immunity or tumor progression. We tested whether genetic polymorphisms in the CCL5/CCR5 axis could predict efficacy of cetuximab (CET)-based first-line treatment in metastatic colorectal cancer (mCRC) patients (pts). Methods: Genomic DNA was extracted from 491 samples of two different cohorts with KRAS wild-type mCRC in the FIRE-3 study: an evaluation cohort of 244 pts receiving CET plus FOLFIRI (median age 64 yrs; median follow-up 34.1 mos); and a control cohort of 247 pts receiving bevacizumab plus FOLFIRI (median age 65 yrs; median follow-up 39.4 mos); Single nucleotide polymorphisms (SNPs) of CCL5 and CCR5 genes were analyzed by PCR-based direct sequencing. Results: Pts in the evaluation cohort with any CCL5 rs2280789 G allele had shorter OS compared to those with the A/A variant (19.9 vs. 33.4 mos, HR 1.56, 95%CI: 1.05–2.30, P= 0.024), which was confirmed in multivariable analysis (HR 1.64, P= 0.015). Pts carrying any CCR5 rs1799988 T allele had a trend lower response rate than those with the C/C variant (68 vs. 81%, P= 0.078). Statistically significant differences in efficacy were shown between the groups consisting SNPs and tumor location (Table). The findings were not confirmed in the control cohort. Conclusions: Genetic variants of CCL5 and CCR5 SNPs may predict outcomes in mCRC pts receiving CET-based first-line treatment depending on tumor location. [Table: see text]

Genetic variants in CCL5 and CCR5 genes and serum VEGF-A levels to predict efficacy of bevacizumab in metastatic colorectal cancer patients receiving first-line chemotherapy

11564

Background: Early VEGF-A reduction by targeting abundant VEGF-A is a potential predictive marker of bevacizumab (BV). CCL5/CCR5 axis modulates VEGF-A production via endothelial progenitor cells migration. We tested whether genetic polymorphisms in CCL5/CCR5 pathway will predict outcomes in metastatic colorectal cancer (mCRC) patients (pts) receiving BV in first-line setting. Methods: Genomic DNA was extracted from 215 samples of three independent cohorts: 61 pts receiving FOLFOX+BV (median age 60 yrs, median follow-up 39.2 mos); 83 pts receiving FOLFOX (median age 61 yrs, median follow-up 57.6 mos); 71 pts receiving FOLFOX/XELOX+BV as exploratory for serum biochemistry assay (median age 60 yrs, median follow-up 28.9 mos). Single nucleotide polymorphisms of genes in CCL5/CCR5 pathway were analyzed by PCR-based direct sequencing. Serum VEGF-A levels at baseline and day 14 were measured using ELISA. Results: In univariate analysis for the FOLFOX cohort, pts with the CCL5 rs2280789 G/G variant or any CCR5 rs1799988 T allele had shorter overall survival (OS) compared to the those with any A allele or the C/C variant (18.7 vs. 29.4 mos, HR 1.93, 95%CI: 1.05−3.53 P= 0.025; 22.0 vs. 31.2 mos, HR 1.74, 95%CI: 0.98-3.90, P= 0.055). The trend remained in multivariable analysis ( P= 0.090 and P= 0.026). The differences were not confirmed in the FOLFOX+BV cohort. Pts with any CCL5 rs2280789 G allele had longer progression-free survival (PFS) and OS when receiving FOLFOX+BV than FOLFOX (PFS: 19.8 vs. 11.0 mos, HR: 0.44, 95%CI: 0.25-0.78, P= 0.002; OS: 41.8 vs. 21.1 mos, HR: 0.43, 95%CI: 0.24-0.77, P= 0.002); pts carrying any CCR5 rs1799988 T allele had longer PFS and OS ( P= 0.025 and P= 0.008, respectively). No significant difference was shown in pts with either A/A or C/C variant. In the exploratory cohort, any CCL5 rs2280789 G allele was associated with higher VEGF-A levels at baseline and greater decrease of VEGF-A levels at day 14 compared with the A/A variant. Conclusions: CCL5 and CCR5 impact the angiogenic environment. Our data suggest the genotypes may identify specific populations who benefit from BV-based chemotherapy in first-line treatment for mCRC.

Genetic variations in semaphorin/neuropilin signaling to predict clinical outcome in patients (pts) with metastatic colorectal cancer (mCRC) receiving bevacizumab-based chemotherapy

11608

Background: Neuropilin ( NRP) is known to be an important VEGF co-receptor that acts as a key mediator of angiogenesis. Its ligands, semaphorins ( SEMA), compete with VEGF for NRP binding and can themselves have angiogenic activity. Plexins are also receptors of SEMAs, and have the GTPase activating proteins (GAPs) domain for RAS. NRPs are shown to signal through RAS pathways. We aimed to evaluate whether single nucleotide polymorphisms (SNPs) of genes involved in the SEMA/NRPpathways predict clinical outcome in bevacizumab-treated mCRC pts. Methods: Associations between nine SNPs in 7 genes ( SEMA3A, SEMA3D, SEMA3F, NRP1, NRP2, PLXNA1 and PLXND1) and clinical outcomes were evaluated in mCRC patients receiving first-line FOLFIRI-bevacizumab in a phase III trial: TRIBE ( N= 228). Associations between genotype and RAS mutation status with clinical outcomes was also examined. Main characteristics were the following: male/female = 138/90; median age = 60; RAS-wildtype/mutant = 55/116; median PFS = 9.7 months; median OS = 26.1 months, median follow-up time = 49.3 months. Results: NRP1 rs2228638 Any A ( N= 40) showed a significantly longer PFS compared to G/G variant ( N= 188) in the univariate (11.6 months (M) vs. 9.5 M, HR = 0.64, 95%CI = 0.43-0.95, p = 0.022) and the multivariate analysis (HR = 0.59, 95%CI = 0.38-0.90, p = 0.016). SEMA3F rs12632110 A/A ( N= 20) showed a significantly shorter PFS compared to any G variant (N = 205) in the multivariate analysis (HR = 1.89, 95%CI = 1.02-3.49, p = 0.043). Among RAS-mutant pts, SEMA3F rs12632110, SEMA3F rs1046956, SEMA3D rs7800072, NRP1 rs228638, PLXNA1 rs4679323 and PLXND1 rs2255703 polymorphisms were significantly associated with PFS in the univariate and multivariate analysis. PLXNA1 rs4679323 was also significantly associated with OS in the univariate and multivariate analysis. There was no association between these polymorphisms and outcome in patients with RASwildtype tumors. Conclusions: Genetic variants within SEMA/NRP pathways may be prognostic markers in RAS mutant mCRC patients treated with bevacizumab-based chemotherapy.

Genetic variations within the vitamin C transporter genes to predict outcome in metastatic colorectal cancer patients treated with first-line FOLFIRI and bevacizumab: Data from FIRE-3 trial

11507

Background: Vitamin C is involved in many critical metabolic processes. Beside its major role as an antioxidant and free radical scavenger vitamin C exerts a regulatory influence on angiogenesis. Additionally, epidemiologic studies show an association between vitamin C levels and incidence of cancer.We therefore hypothesize that variations in genes encoding for vitamin C transporter proteins may predict outcome in patients (pts) with metastatic colorectal cancer (mCRC) treated with FOLFIRI and bevacizumab (bev). Methods: Theimpact of 3 functional SNPs within the SVCT1, SVCT2 and Glut1 genes on outcome was evaluated in 292 pts with mCRC treated with first-line FOLFIRI/bev in the randomized phase III FIRE-3 trial. 294 pts receiving FOLFIRI and cetuximab (cet) (FIRE-3) served as a negative control. Genomic DNA was extracted from formalin fixed paraffin embedded tissue and SNPs were analyzed by PCR-based direct sequencing. Results: Baseline characteristics in the FOLFIRI/bev arm were as follows: female/male 99/193; median age = 65y andmedian PFS/OS = 10.1/24.2 months (mts). The SVCT1 rs11242462 SNP showed significant association with PFS. T allele carriers had a longer median PFS compared to those with a C/C genotype (10.7 vs 9.7 mts) in both univariate (HR 0.77, p = 0.046) and multivariate analysis (HR 0.73, p = 0.028). The effect on outcome was most significant among KRAS mutant pts. Here, T allele carriers showed a markedly prolonged PFS and OS compared to pts with a C/C genotype (12.5 vs 7.0 mts, HR 0.50, p = 0.018 and 32.8 vs 14.7 mts, HR 0.45, p = 0.009). These associations remained significant in multivariate analyses (p = 0.009 and p = 0.021, respectively). However, the favorable impact on outcome was not observed among T allele carriers treated with FOLFIRI/cet. Conclusions: Our results provide the first evidence that the SVCT1 polymorphism rs11242462 might serve as a predictive marker in pts with mCRC treated with FOLFIRI/bev in the first-line setting. Targeting vitamin C transporter proteins might be a promising approach to further improve treatment options against mCRC and to overcome resistance to anti-angiogenic therapy.

Association of genetic variations in genes implicated in the axis with outcome in patients (pts) with metastatic colorectal cancer (mCRC) treated with cetuximab plus chemotherapy

3585

Background: Accumulating evidence suggests that right- and left-sided CRCs have different prognoses and different sensitivities to EGFR inhibitors in several phase3 trials. These differences might be related to different embryological origins, which are reflected in different molecular profiles of tumors. LEFTY, Nodal and ACVR2B, which are TGF-betasuperfamily, are key regulators of left-right axis during embryogenesis; these expressions control sidedness. Our aim was to evaluate whether SNPs in these genes are associated with clinical outcomes in mCRC pts enrolled in the FIRE3 trial. Methods: Genomic DNA was obtained from mCRC pts receiving cetuximab plus FOLFIRI as first-line treatment and analyzed by using PCR-based direct sequencing. Four functional SNPs in 4 genes ( LEFTY1, LEFTY2, Nodal, and ACVR2B) were tested in 305 pts in FIRE3 trial cetuximab cohort (NCT00433927). Main characteristics were the following: male/female = 207/98; median age = 64; RAS-wildtype/mutant = 195/95; median PFS = 9.6 months; median OS = 26.5 months, median follow-up time = 41.8 months. Results: In patients with left sided tumor ( N= 237), LEFTY2 rs3007716 G/G variants ( N= 14) showed shorter PFS than any A variants ( N= 222) in univariate (8.0 months (M) vs. 10.3 M, HR = 2.24, 95%CI = 1.27-3.94, P < 0.01) and multivariate analyses (HR = 2.12, 95%CI = 1.20-3.75, P < 0.01). Nodal rs1904589 T/T ( N= 36) showed longer OS than any C variants ( N= 196) in univariate analysis (50.1 m vs. 29.8 M, HR = 0.61, 95% = 0.37-1.01, P = 0.048) and multivariate analyses (HR = 0.59, 95%CI = 0.35-0.99, P = 0.046). In patients with right sided tumors ( N= 58), ACVR2B rs2268753 C/C ( N= 12) showed shorter PFS than any T variants ( N= 43) in univariate analysis (3.7 m vs. 7.7 M, HR = 1.93, 95% = 0.99-3.77, P = 0.038) and multivariate analysis (HR = 2.24, 95%CI = 1.12-4.51, P = 0.023). Conclusions: Our study showed for the first time that genetic variations in sidedness related genes are associated with PFS and OS in patients receiving cetuximab based chemotherapy, which may dependent on location.

New evidence of a dihydropyridine-activated cationic channel in the MDCK cell line

Newborn rat distal cells express an apical Ca2+ channel activated by dihydropyridine drugs. Similarly, in Madin-Darby canine kidney (MDCK) cells, nifedipine increased Ca2+i in a concentration-dependent manner (IC50=4 μM) in fura-2-loaded cells. Response to nifedipine was abolished by EGTA, suggesting that it depends on extracellular calcium. Ca2+ channel antagonist isradipine and agonist BayK8644 increased Ca2+i indicating that this effect is related to the dihydropyridine group. Diltiazem (20 μM) and gadolinium (200 μM) decreased the nifedipine effect (62 and 43%, respectively). Lanthanum (100 μM) did not change the response. Valinomycin clamping of the membrane potential did not modify nifedipine-induced increment, indicating that it was unrelated to potassium fluxes. We performed whole cell clamp experiments in MDCK cells maintained at -50 mV with perfusion solution containing 10 mM CaCl2. Nifedipine (20 μM) induced an increase in current (1.2±0.3 nA), which was partially inhibited by Gd3+. No significant current was induced by nifedipine in the presence of 0.5 mM EGTA. To determine the effects of nifedipine on the membrane potential, we performed oxonol fluorescence experiments. The addition of nifedipine or Bay K8644 induced depolarization, highly dependent on external sodium. Nifedipine (20 μM) induced depolarization of 6.9±0.8 mV (n=21). EC50 to nifedipine was in the 10 μM range. We conclude that MDCK cells exhibit a dihydropyridine-activated cationic channel.

Metabolism of orthotopic mouse brain tumor models

We used magnetic resonance spectroscopy to determine whether orthotopic mouse brain tumors grown as xenografts in immunocompromised mice either from human brain tumor cells implanted immediately after surgery or from cultured human tumor lines show metabolic profiles comparable to those of the original tumors. Using a 7 T scanner, spectra were acquired from mice with a human atypical teratoid/rhabdoid tumor (AT/RT) either implanted directly from the surgical specimen or first grown in culture, directly implanted choroid plexus carcinoma (CPC), and two medulloblastoma cell lines. The results were compared with spectra from these same tumors or tumor types in patients and with controls. Metabolic variability of tumors from a single cell line was also evaluated using the medulloblastoma lines. The main metabolic features of human tumors were qualitatively replicated in xenografts. AT/RTs in mice exhibited choline, creatine, and myo-inositol levels comparable to those observed in the patient. As in patients, choline was prominent in experimental CPC. Tumors from a single cell line were comparable. Significant correlations were found with key metabolites in humans and mice; however, differences including lower lipids in the implanted AT/RTs than in patient spectra and taurine observed in all animal spectra were also noted. The causes of these dissimilarities warrant further investigation.

Nifedipine-activated Ca(2+) permeability in newborn rat cortical collecting duct cells in primary culture

To characterize Ca(2+) transport in newborn rat cortical collecting duct (CCD) cells, we used nifedipine, which in adult rat distal tubules inhibits the intracellular Ca(2+) concentration ([Ca(2+)](i)) increase in response to hormonal activation. We found that the dihydropyridine (DHP) nifedipine (20 microM) produced an increase in [Ca(2+)](i) from 87.6 +/- 3.3 nM to 389.9 +/- 29.0 nM in 65% of the cells. Similar effects of other DHP (BAY K 8644, isradipine) were also observed. Conversely, DHPs did not induce any increase in [Ca(2+)](i) in cells obtained from proximal convoluted tubule. In CCD cells, neither verapamil nor diltiazem induced any rise in [Ca(2+)](i). Experiments in the presence of EGTA showed that external Ca(2+) was required for the nifedipine effect, while lanthanum (20 microM), gadolinium (100 microM), and diltiazem (20 microM) inhibited the effect. Experiments done in the presence of valinomycin resulted in the same nifedipine effect, showing that K(+) channels were not involved in the nifedipine-induced [Ca(2+)](i) rise. H(2)O(2) also triggered [Ca(2+)](i) rise. However, nifedipine-induced [Ca(2+)](i) increase was not affected by protamine. In conclusion, the present results indicate that 1) primary cultures of cells from terminal nephron of newborn rats are a useful tool for investigating Ca(2+) transport mechanisms during growth, and 2) newborn rat CCD cells in primary culture exhibit a new apical nifedipine-activated Ca(2+) channel of capacitive type (either transient receptor potential or leak channel).

Effects of thrombin on intracellular calcium and pH in human and murine platelets

The aim of this study was to compare the effect of thrombin (Thr) on cytosolic calcium [Ca2]+i and intracellular pH [pH]i in human and murine platelets. Rich-platelet suspensions from both species were loaded with Fura-2 (2 microM) or BCECF (0.75 microM) by incubation with their respective acetoxymethyl esters to measure cytosolic calcium [Ca2+]i or intracellular pH [pH]i, respectively. Suspensions were challenged with increasing concentrations of Thr, from 0.1 to 10 IU/ml. Basal [Ca2+]i in human platelets was 98 +/- 6 and 99.1 +/- 9 nM in rat platelets (n = 20). Thr increased [Ca2+]i, EC50 was 1.1 +/- 0.04 in human and 0.97 +/- 0.06 IU/ml in rat platelets (n = 7). Extracellular Mg2+ (4 or 8 mM) abolished Thr response on [Ca2+]i. [pH]i in human was 7.09 +/- 0.08 and 7.11 +/- 0.04 in rat platelets. Thr induced alkalinization of platelets in both species. Our results indicate that the potency of Thr to change [Ca2+]i and [pH]i was similar in both species, allowing for comparisons between human and murine platelets and to extrapolate results from an animal model to human pathology.

Specificity of circulating and tissue-bound autoantibodies in Goodpasture syndrome

Goodpasture syndrome is an often fatal autoimmune disease associated with glomerulonephritis and/or pulmonary hemorrhage. The clinical manifestations of this disease correlate well with the presence of circulating antiglomerular basement membrane (GBM) autoantibodies. The primary target antigen in glomerular and alveolar basement membranes is thought to be the alpha 3 chain of type IV collagen. Nearly all that is known about anti-GBM antibodies in humans comes from work on unbound circulating antibody. We recently had the unique and rare opportunity to obtain early postmortem antibody and tissues from a patient who died with catastrophic Goodpasture syndrome. The specificity of circulating, kidney-bound and lung-bound autoantibodies from this patient was evaluated against a variety of purified basement membrane constituents. The results indicate that the primary target for the circulating and tissue-bound autoantibodies is the NC1 domain of the alpha 3(IV) chain of type IV collagen. Additionally, all the antibodies recognize a cryptic epitope/s on the alpha 3(IV)NC1 hexamer. Furthermore, tissue-bound and circulating antibodies compete with one another for overlapping epitopes on the antigen. These findings demonstrate that circulating autoantibodies in Goodpasture syndrome are highly representative of those bound to organ tissues, strengthening the notion that pathogenic autoantibodies are targeted to the alpha 3(IV)NC1 collagen, and that previous reports of findings in the circulation may be applicable to tissue injury.

Endocytosis inhibition protects the isolated guinea pig heart against ouabain toxicity

We have tested whether toxicity and uptake of ouabain are linked phenomena in isolated guinea-pig heart. We perfused toxic dose of either ouabain, dihydroouabain (hydrophilic cardiac steroids), ouabagenin or digitoxin (hydrophobic steroids) in conditions of endocytosis inhibited. We used two schemes of inhibition of endocytosis. First, we cooled the heart at 0-4 degrees C and exposed it 60 min to either 1 X 10(-6) M ouabain or 3 X 10(-7)M digitoxin. Upon rewarming, the heart exposed to ouabain relaxed with a shorter time constant than those exposed to digitoxin. Second, we perfused four receptor mediated endocytosis (RME) inhibitors at the same time that the cardiac glycosides. RME inhibitors significantly delayed the cardiac arrest caused by ouabain and dihydroouabain but they did not modify the toxicity of 3 X 10(-7)M digitoxin or 5 X 10(-6)M ouabagenin. None of RME inhibitors modified the toxicity of 0.5 mM K+ or zero Na+ saline solution. We suggest that the protection against ouabain toxicity brought by endocytosis inhibition, is related to the Na-pump recycling. We infer that besides the sarcolemmal exposed Na-pumps, the intracellular Na-pumps pool may be of importance for the pharmacological effects of digitalis steroids.

AIDS in the elderly: New York City vital statistics

The HIV infection primarily affects young adults, but older adults are also susceptible. The number of AIDS cases among persons aged 50 or greater is growing and is of major concern. As our awareness of the prevalence of HIV-related illnesses presenting to the emergency department improves in the younger population, we must not ignore the disease in older patients. Early recognition of HIV infection will ensure the greatest opportunity for treatment and prevention of many of the consequences of opportunistic infections. We present a case of HIV in an elderly patient in order to heighten awareness of the possibility of HIV infection in older patients presenting to the emergency department. We also review the epidemiological, diagnostic, and therapeutic aspects of AIDS in older adults.

Puerto Rican migration and occupational selectivity, 1982-1988

"This study examines whether or not the likelihood of Puerto Rican workers choosing to migrate to the United States depends on their occupations or skills. The study determined that the occupational composition among those migrating from the island to the United States generally corresponds to the occupational distribution in Puerto Rico. The exception is that, after controlling for labor market conditions in Puerto Rico and in the United States and for other characteristics of the migrants, farm workers, laborers, and craft and kindred workers are overrepresented in the flow of migrants. The two most important factors contributing to the occupational distribution of migrants are whether or not they already have job offers in the United States and whether they are currently employed in Puerto Rico."

Phase I study of recombinant human interleukin-2 for pediatric malignancies: feasibility of outpatient therapy. A Pediatric Oncology Group Study

Published data indicate that when recombinant interleukin-2 (rIL-2) is administered to children as a 15-min i.v. bolus, doses of 18 x 10(6) IU/m2 are poorly tolerated, requiring intensive care unit (ICU) management of IL-2-induced hypotension. We administered rIL-2 as a 1- or 2-h i.v. infusion to 11 children with malignancies refractory to conventional therapy. IL-2 was given every Monday/Wednesday/Friday for 3 weeks. Four children received 12 x 10(6) IU/m2/dose, four received 18 x 10(6) IU/m2/dose, and three received 24 x 10(6) IU/m2/dose (1 Cetus Unit = 6 IU). Fever, chills, flushing, nausea, vomiting, transient weight gain, and oliguria were observed at all three dose levels (not dose-limiting toxicities). Cardiovascular toxicity was significantly reduced compared to the bolus regimen. Mild hypotension was observed at all three dose levels; however, there was no severe dose-limiting hypotension. Because of reduced cardiovascular toxicity, IL-2 was safely administered on an outpatient basis. This regimen induced marginal transient increases in natural killer cell activity and lymphokine-activated killer cell activity. No measurable clinical tumor response was observed in any of the 11 children. The maximum-tolerated dose has not been reached. This regimen allows for a considerable cost reduction (outpatient care instead of ICU care) and safety, making further clinical trials on the use of IL-2 in children more feasible.

Solitary osseous sarcoidosis in a finger

Sarcoidosis confined to a single bone in a patient with chronic systemic sarcoidosis and seen as a soft tissue mass is exceedingly rare. The combination of lytic and sclerotic changes within one bone has not been previously reported.

Effects of furosemide on the renal functions of the unanesthetized newborn rat

In neonates pharmacokinetics of furosemide is very slow, as compared to adult individuals, because it is eliminated through glomerular filtration and tubular secretion, mechanisms that are not fully developed in the newborn mammal. In addition, Henle's loop, the main site of action of this diuretic, is shorter in the neonate than in the adult animal. The aim of this study was to measure the response to furosemide in the unanesthetized newborn rat and to compare it with that of the adult. Furosemide (0.5, 1, 1.5, 2, 5 or 10 mg/kg body weight, i.p.) or vehicle were administered to newborn and adult rats and the effects on sodium, potassium and water balance were assessed. Despite the physiological characteristics of the neonatal kidney, furosemide induced a more marked sodium excretion and decrease in free water clearance in the newborn than in the adult rat. In contrast, urinary potassium losses elicited by furosemide were higher in the adult than in the newborn rat at similar doses. At both ages, the effects of the diuretic were dose-dependent. Plasma sodium decreased, whereas plasma potassium and hematocrit increased in the newborn rats, after the highest doses of furosemide. In the adult rat changes were less marked. Our results suggest that the neonatal kidney is more sensitive to equivalent doses of furosemide than the adult kidney.

Effects of eicosanoids on the water and sodium balance of the neonate

Experimental and clinical evidence support the assumption that eicosanoids affect the morphological development and the functional behaviour of the kidney during the intra-uterine and newborn periods. Inhibition of prostaglandin (PG) synthesis in the pregnant rhesus monkey resulted in renal hypoplasia in the offspring. The plasma levels of PGs are high in the newborn. Production of PGE2 by the cortical collecting duct was found to be similar in newborn and adult rabbit but the affinity of the renal tissue of the newborn for this eicosanoid was higher than that of the renal tissue of the adult rat. Based on findings in adult animals this would be expected to blunt the effect of antidiuretic hormone and account, in part, for the limited ability of the newborn to concentrate the urine. Yet, administration to unanaesthetized newborn rats of acetaminophen, a drug that inhibits the synthesis of PGE2 and thromboxane B2, blocked, rather than enhanced, the increment in urine osmolality produced by 1 h of water deprivation. The effect was absent in weaning and adult rats. A similar experimental manoeuvre increased sodium excretion in newborn but not in weaning or adult rats. Age-related differences are also evident with regard to side effects of PG synthesis inhibition.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of levamisole on experimental infections by Plasmodium berghei in mice

Levamisole (phenylimidothiazol), considered a strong immunostimulant, when administered to healthy Swiss mice did not cause a significant increase in -the weight of their thymus, liver and spleen, even though the drug was used at different times before removing such organs. High doses ofdrug used in the 4-day prophylactic scheme had no antimalarial effect. However, when given to malaria infected mice 24 hours before, at the same time, and 24 hours after the inoculation of a chloroquine-sensitive or a chloroquine-resistant strain of Plasmodium berghei small doses of the drug induced a somewhat decreased parasitemia, the dose of 1 mg/kg body weight before the inoculum being the best scheme. The mortality rates by malaria in the levamisole treated groups were also delayed although all mice finally died. The data suggest that levamisole may display a stimulant effect on the depressed immune response caused by malaria.

Renal handling of indomethacin and its relationship with the secretory pathway of prostaglandins

The uptake of prostaglandin E2, one of the main renal prostaglandins and of p-aminohippurate, an indicator of the anion organic transport, by slices of kidney cortex from adult female rats was studied in the presence and in the absence of indomethacin. The drug's inhibitory effect on the uptake of prostaglandin E2 was observed both after in vivo administration as well as when it was present in the bathing media. The effect was more pronounced when the drug was given in vivo and in addition, was present in the bath. [14C] PAH uptake was inhibited by indomethacin in a dose-related pattern and the kinetic analysis of this effect is indicative of a competitive inhibition. As expected, uptake of PAH by medullary slices was not affected by the presence of either indomethacin of PGE2. Indomethacin was more potent in inhibiting PGE2 uptake than PAH uptake.