Deoxypyrimidine-induced inhibition of the cytokinetic effects of 1-β-d-arabinofuranosyluracil

Summary Ara-U-induced S-phase accumulation and the interaction between high concentrations of ara-U (HiCAU) and ara-C were investigated in L1210 leukemia cells in vitro. Treatment of exponentially growing L1210 murine leukemia cells with ara-U (200–1000 m) for 48 h caused a dose-dependent accumulation of cells in the S-phase. The extent of this ara-U-induced S-phase accumulation correlated with ara-U incorporation into DNA and with increases of up to 172% and 464% in the specific activities of deoxycytidine kinase and thymidine kinase, respectively, over control values. Metabolism of 1 m ara-C following the exposure of cells to ara-U (1mm) resulted in 4.5 pmol ara-C DNA/mg protein vs 2.1 pmol/mg protein in control cells. Although 48-h exposure of cells to 200 and 400 m ara-U is not cytotoxic, it enhances the cytotoxicity of ara-C (10–100 m) 4- to 10-fold. Ara-U-induced S-phase accumulation is inhibited by deoxypyrimidine nucleosides but not by pyrimidine or deoxypurine nucleosides. Some of the ara-U and ara-C concentrations used in this study are achievable in clinical practice, and ara-U/ara-C interactions may explain in part the unique therapeutic utility of high-dose ara-C.Abbreviations ara-C 1--d-arabinofuranosylcytosine - ara-U 1--d-arabinofuranosyluracil - ara-CTP 1--d-arabinofuranosylcytidine triphosphate - HiDAC high-dose ara-C - HiCAU high concentrations of ara-U - dCTP deoxycytidine triphosphate - HiDAU high-dose ara-U - FiTC Fluoroisothiocyanate - dUDP deoxyuridine diphosphate - dUTP deoxyuridine triphosphate - dTTP thymidine triphosphate - BrdUrd bromodeoxyuridine - dCyd kinase deoxycytidine kinase Supported in part by grant CH-35H from the American Cancer Society, by Public Health Service grant CA-12197 from the National Cancer Institute, National Institutes of Health, and by the Gaston Cancer Society     

Antitumor mechanisms and metabolism of the novel antitumor nucleoside analogues, 1-(3-C-ethynyl-β-D-ribo-pentofuranosyl)cytosine and 1-(3-C-ethynyl-β-D-ribo-pentofuranosyl)uracil

The antitumor ribonucleoside analogues 1-(3-C-ethynyl-β-d-ribo-pentofuranosyl)cytosine (ECyd) and 1-(3-C-ethynyl-β-d-ribo-pentofuranosyl)uracil (EUrd), first synthesized in 1995, have strong antitumor activity against human cancer xenografts without severe side effects. Here, we studied the antitumor mechanisms of ECyd and EUrd using mouse mammary tumor FM3A cells in vitro and the mechanism of selective cytotoxicity of ECyd using human tumor xenografts in nude rats in vivo. In FM3A cells, ECyd and EUrd were rapidly phosphorylated to ECyd 5′-triphosphate (ECTP) and EUrd 5′-triphosphate (EUTP), which strongly inhibiting RNA synthesis. Cells treated with EUrd were later found to contain both EUTP and ECTP, and ECTP accumulated as the final product. Probably the uracil moieties of EUrd derivatives were efficiently converted to cytosine moieties in the cells. EUrd and its derivatives were minor metabolites in the cells treated with ECyd, so cytidine forms probably were not converted to uridine forms at the nucleoside or nucleotide stage. The ultimate metabolite of ECyd and EUrd, ECTP, is stable in cultured cells with a half-life of at least 3 days, so ECyd and EUrd are on a “closed” metabolic pathway to ECTP. These characteristics of ECyd and EUrd may be important for their antitumor activity. ECyd had strong and selective antitumor activity against the human tumor xenografts. ECyd-phosphorylating activity (uridine/cytidine kinase) in the xenografts was higher than that in the organs of the rats. This finding may account for the strong activity with mild side effects. ECyd and EUrd may be a new kind of antitumor nucleoside analogue for clinical use. Received: 8 June 1998 / Accepted: 5 November 1998     

Hydroxyurea potentiation of the antineoplastic activity of cyclophosphamide and 4′-(9-acridinylamino)methanesulfon-M-anisidide (AMSA) in the brown Norway rat myelocytic leukemia model

Summary The activities of hydroxyurea (HU), 4-(9-acridinylamino) methanesulfon-M-anisidide (AMSA) and cyclophosphamide (CY) were examined in the brown Norway rat myelocytic leukemia model in experiments designed to determine the synergy, optimal drug sequencing, and therapeutic index of combinations of these agents. A single dose of CY or four consecutive daily doses of AMSA produced increased survival in leukemic rats, with a positive-slope dose-response curve up to the maximum tolerated dose (MTD). HU at 1/2 MTD produced a minimal antileukemic effect but significantly potentiated the antineoplastic activity of 1/2 MTD of CY or AMSA with no significant toxic death rate. Drug-sequence experiments demonstrated that maximal synergy was achieved when HU was given immediately after CY but immediately before or during AMSA administration. No significant cure rate was seen with any CY/HU or HU/AMSA sequence. The three drugs given in the sequence of CY followed 3 days later by HU and AMSA simultaneously, however, was curative in the majority of rats with advanced leukemia, whereas other sequences were more toxic or less effective. Each of the drugs in these experiments was given at 1/2 of its single-agent MTD. HU significantly potentiates the antineoplastic effect of CY and AMSA in a drug-sequence-dependent manner in this model, apparently with an improved therapeutic index.Supported by the State of Nebraska Cancer and Smoking Disease Research Program Grant #87-10R     

Neuregulins 1–4 are expressed in the cytoplasm or nuclei of ductal carcinoma (in situ) of the human breast

Summary A new family of epidermal growth factor-like proteins, the Neuregulins (NRGs), have recently been identified and are expressed in a range of normal tissues and in some forms of cancer including breast cancer. In this study we examined using immunohistochemical staining expression of NRG1alpha, NRG1beta, NRG2alpha, NRG2beta, NRG3 and NRG4 in sixty cases of pre-invasive ductal carcinoma in situ of the breast representing different degrees of differentiation. Each protein was expressed in a high proportion of these cases showing a predominantly homogenous cytoplasmic staining pattern. Nuclear expression of NRG1alpha, NRG1beta, and NRG3 was however also observed in a significant fraction of cases. High levels of expression of NRG2beta and NRG4 were associated with high-grade tumours (p≤0.005), NRG2beta staining was associated with tumour size >25 mm (p=0.005) while NRG3 nuclear staining was present more often in low-grade tumours (p=0.039). This data demonstrates that each member of the NRG family of ligands is present in pre-invasive ductal breast cancer and that they may be involved in regulating cell behaviour. The significance of intranuclear expression remains to be determined but suggests a novel mechanism of action for some of these proteins.     

Tolerability of the synthetic retinoid fenretinide® (HPR)

Fenretinide®, N-(4-hydroxyphenyl)retinamide (HPR), is a synthetic retinoid which has been proven effective in inducing cell differentiation and in inhibiting carcinogen induced mammary tumors in rodents. Because of its efficacy and low toxicity in animals, HPR has been proposed for chemopreventive evaluation in humans. Thus, a randomized trial has been conducted to select a dose which can be administered over a lengthy period of time and with acceptable toxicity. The retinoid was administered orally to patients already operated on for breast cancer in daily doses of 100, 200 and 300 mg for 6 months and subsequently at 200 mg for another 6 months. No acute toxicity was found. Dermatological toxicity was minimal and no liver function abnormalities were observed. Nausea and headaches were infrequent and always mild. Menstrual irregularities were recorded with similar frequency in the treatment and placebo groups and appeared to be more age related than drug dependent. After 6 months of treatment one of 25 patients taking 300 mg HPR daily experienced impaired night vision, confirmed by the electroretinogram, and resolved by interruption of treatment. Because the 300 mg daily dose is possibly associated with impaired dark adaptation, the recommended dose for chemoprevention trials of HPR is 200 mg per day.     

Instability of a dinucleotide repeat in the 3′‐untranslated region (UTR) of the microsomal prostaglandin E synthase‐1 (mPGES‐1) gene in microsatellite instability‐high (MSI‐H) colorectal carcinoma

DNA mismatch‐repair gene mutations, with consequent loss of functional protein expression, result in microsatellite instability (MSI). Microsatellite sequences are found in coding regions and in regulatory regions of genes (i.e., 5′‐UTRs and 3′‐UTRs). In addition to being a surrogate marker of defective mismatch repair, deletion or insertion microsatellite sequences can dysregulate gene expression in MSI‐H (microsatellite instability‐high) tumors. The microsomal prostaglandin E synthase‐1 (mPGES‐1) gene product, mPGES‐1, participates in prostaglandin E2 (PGE2) production. Moreover, mPGES‐1 is often overexpressed in human colorectal tumors, and is thought to contribute to progression of these tumors. Here we identified a dinucleotide repeat, (GT)24, in the mPGES‐1 gene 3′ untranslated region (3′‐UTR), and analyzed its mutation frequencies in MSI‐H and microsatellite stable (MSS) tumors. The (GT)24 repeat exhibited instability in all MSI‐H tumors examined (14), but not in any of the MSS tumors (13). In most cases, (GT)24 repeat instability resulted in insertion of additional GT units. We also determined mPGES‐1 mRNA levels in MSI‐H and MSS colorectal cancer cell lines. Three of four previously designated “MSI‐H” cell lines showed higher mPGES‐1 mRNA levels compared to MSS cell lines; correlations between elevated mPGES‐1 mRNA levels and microsatellite (GT)24 repeat characteristics are present for all six cell lines. Our results demonstrate that mPGES‐1 is a target gene of defective mismatch repair in human colorectal cancer, with functional consequence.     

Comprehensive Genomic Sequencing of Urothelial Tumors Identifies Rare SMARCB1 (INI-1)–Deficient Carcinomas of the Urinary System

Purpose

Tumor genomic profiling helps direct therapy for advanced urothelial carcinoma (UC). In the course of clinical care, we encountered a patient with a complete loss of SMARCB1 (switch/sucrose nonfermentable-related matrix-associated actin-dependent regulator of chromatin subfamily B member 1), which encodes INI-1 (integrase interactor 1), as the sole detected driver of their urinary tract tumor. Our objective was the identification and genomic characterization of urinary tract neoplasia with complete SMARCB1 loss.

Influence of Vegetables on the Expression of GSTP1 in Humans — a Pilot Intervention Study (Sweden)

Background: There are indications that a diet rich in vegetables and/or fruit has a protective effect against se types of diseases, including cancer. Data from experimental and epidemiological studies suggest that antioxidant constituents may provide protection against environmental carcinogens. Aims: This study investigated the effect of additional vegetables in the diet on the expression of the endogenous antioxidant enzyme GSTP1 in human lymphocytes. Methods: Six subjects were given an addition of mixed vegetables to their normal diet for a period of three weeks. The expression of GSTP1 protein and mRNA in lymphocytes was measured by Western blot and RT competitive PCR. Results: After the intervention all six subjects had lower levels of GSTP1 mRNA, and five of the six subjects had lower GSTP1 protein levels. This suggests that increased vegetable intake decreases GSTP1 expression, possibly through the supply of additional antioxidants.     

Eight-year (2002-2009) Summary of the Linezolid (Zyvox® Annual Appraisal of potency and Spectrum; ZAAPS) Program in European Countries

Abstract

The linezolid surveillance network (ZAAPS program) has been monitoring linezolid activity and susceptibility rates for eight years (2002-2009) in European medical centers. Samples from 12-24 sites annually in 11 countries were monitored by a central laboratory design using reference MIC methods with international and regional interpretations (EUCAST). A total of 13,404 Gram-positive pathogens were tested from 6 pathogen groups. Linezolid remained without documented resistance from 2002 through 2005, but beginning in 2006 resistant strains emerged at very low rates among Staphylococcus aureus (G2576T mutant in ireland, 2007), coagulase-negative staphylococci (CoNS; usually Staphylococcus epidermidis, France and italy in 2006-2009) and enterococci (Enterococcus faecium in Germany [2006, 2008, 2009] and E. faecalis in Sweden [2008], United Kingdom [2008] and Germany [2009]); all but one strain having a target mutation. A mobile cfr was detected in an italian CoNS strain (2008 and 2009), and clonal spread was noted for linezolid-resistant strains (pfGe results). Overall the linezolid susceptibility rates were >99.9, 99.7 and 99.6% for S. aureus, CoNS and enterococci, respectively; and all streptococcal strains were susceptible (MIC₉₀, 1 mg/L). In conclusion, the ZAAPS program surveillance confirmed high, sustained levels of linezolid activity from 2002-2009 and without evidence of MIC creep or escalating resistance in Gram-positive pathogens across monitored European nations.     

A new nitrosourea derivative TA-077, 1-(2-Chloroethyl)-3-isobutyl-3-(β-maltosyl)-1-nitrosourea

Summary A new water-soluble nitrosourea derivative, 1-(2-chloroethyl)-3-isobutyl-3-(-maltosyl)-1-nitrosourea (TA-077), was tested for antitumor activity against murine tumors and a human mammary carcinoma (MX-1) implanted in athymic mice, and the results were compared with those obtained with five other nitrosourea derivatives currently in clinical use: 1-(2-chloroethyl)-3-(methyl--d-glucopoyranos-6-yl)-1-nitrosourea (MCNU), 1-(2-chloroethyl)-3-(-d-glucopyranosyl)-1-nitrosourea (GANU), 3-[(4-amino-2-methyl-5-pyrimidinyl)methyl]-1-(2-chloroethyl)-1-nitrosourea hydrochloride (ACNU), chlorozotocin, and 1-(2-chloroethyl)-3-(4-methylcyclohexyl)-1-nitrosourea (Me-CCNU).The results indicated that TA-077 had a unique optimal treatment schedule different from other nitrosoureas. With daily IV treatments for 5 days, TA-077 showed the highest antitumor activity of all against the advanced Lewis lung carcinoma, defined by tumor weight and the survival of tumor-bearing mice. Furthermore, TA-077 given according to this treatment schedule was successful in inducing an apparent cure (complete regression and no recurrence) in all the athymic mice bearing MX-1, which the other five nitrosoureas could not. In addition, TA-077 possessed higher therapeutic indices (optimal dose/ILS₂₅) against L1210 and P388 leukemias than MCNU, which possessed the highest therapeutic index against L1210 leukemia among the five nitrosourea derivatives.     

Eight-year (2002-2009) summary of the linezolid (Zyvox® Annual Appraisal of Potency and Spectrum; ZAAPS) program in European countries

The linezolid surveillance network (ZAAPS program) has been monitoring linezolid activity and susceptibility rates for eight years (2002-2009) in european medical centers. Samples from 12-24 sites annually in 11 countries were monitored by a central laboratory design using reference MIC methods with international and regional interpretations (EUCAST). A total of 13,404 gram-positive pathogens were tested from 6 pathogen groups. Linezolid remained without documented resistance from 2002 through 2005, but beginning in 2006 resistant strains emerged at very low rates among Staphylococcus aureus (G2576T mutant in ireland, 2007), coagulase-negative staphylococci (CoNS; usually Staphylococcus epidermidis, France and Italy in 2006-2009) and enterococci (Enterococcus faecium in Germany [2006, 2008, 2009] and E. faecalis in Sweden [2008], United Kingdom [2008] and Germany [2009]); all but one strain having a target mutation. A mobile cfr was detected in an italian CoNS strain (2008 and 2009), and clonal spread was noted for linezolid-resistant strains (PFGE results). Overall the linezolid susceptibility rates were >99.9, 99.7 and 99.6% for S. aureus, CoNS and enterococci, respectively; and all streptococcal strains were susceptible (MIC(90), 1 mg/l). In conclusion, the ZAAPS program surveillance confirmed high, sustained levels of linezolid activity from 2002-2009 and without evidence of MIC creep or escalating resistance in gram-positive pathogens across monitored european nations.     

Phase I study of the cytotoxic agent N -[2-(dimethylamino)ethyl]acridine-4-carboxamide

N-[2-(Dimethylamino)ethyl]acridine-4-carboxamide (DACA) is a new DNA-intercalating drug with a dual mode of cytotoxic action that is thought to involve topoisomerases I and II. On the basis of novelty of action and promising preclinical activity against solid tumours in mice, DACA was selected for clinical trial under the auspices of the Cancer Research Campaign, United Kingdom. We report the phase I findings of a 3-h infusion regimen, repeated 3-weekly, of escalating doses through 18–1000 mg/m² given to 31 patients with solid malignancies. A maximum tolerated dose (MTD) of 750 mg/m² was identified, with 3 of 6 cycles being abandoned at 1000 mg/m². Dose-limiting toxicity took the form of infusional arm pain, in some cases associated with facial discomfort, that was of rapid onset and subsided quickly on the cessation of infusion. The mechanism is unclear but is modulated to some extent by the rate of drug delivery, and it was unaffected in this study by concurrent anti-inflammatory or opiate medication. No host or tumour anti-proliferative activity was observed at these doses, and only minimal toxicity of any other kind was evident. Animal data suggest that the MTD achieved with this schedule may be sub-therapeutic in humans. It is therefore important that efforts be continued to explore methods of giving higher doses of DACA. Received: 21 August 1998 / Accepted: 10 December 1998     

Activity of proximal promoter of the human beta(1)-integrin gene was increased in Sézary syndrome

Changes in beta1-integrin expression have been involved in abnormal cellular interactions between malignant lymphocytes from Sézary (Sz) patients and keratinocytes. In this paper, we compare the activity of both distal and proximal promoters of the beta1-integrin gene in malignant lymphocytes from Sz patients with human normal lymphocytes. Activity of both beta1-integrin promoters was also analysed in human normal keratinocytes. Northern blot analysis shows that beta1-integrin mRNA expression is higher in malignant Sz lymphocytes than in normal lymphocytes. CAT assays show that the activity of proximal beta1-integrin promoter is markedly increased (up to 6-fold) in malignant lymphocytes from Sz patients, in comparison to normal lymphocytes. These results suggest that changes in activity of the proximal promoter of beta1-integrin subunit could be, in part, responsible for the abnormal cellular interactions between malignant lymphocytes and keratinocytes observed in Sz syndrome.     

Progress Report of a Phase I Study of the Intracerebral Microinfusion of a Recombinant Chimeric Protein Composed of Transforming Growth Factor (TGF)-α and a Mutated form of the Pseudomonas Exotoxin Termed PE-38 (TP-38) for the Treatment of Malignant Brain Tumors

TP-38 is a recombinant chimeric targeted toxin composed of the EGFR binding ligand TGF- and a genetically engineered form of the Pseudomonas exotoxin, PE-38. After in vitro and in vivo animal studies that showed specific activity and defined the maximum tolerated dose (MTD), we investigated this agent in a Phase I trial. The primary objective of this study was to define the MTD and dose limiting toxicity of TP-38 delivered by convection-enhanced delivery in patients with recurrent malignant brain tumors. Twenty patients were enrolled in the study and doses were escalated from 25ng/mL to 100 with a 40mL infusion volume delivered by two catheters. One patient developed Grade IV fatigue at the 100ng/mL dose, but the MTD has not been established. The overall median survival after TP-38 for all patients was 23 weeks whereas for those without radiographic evidence of residual disease at the time of therapy, the median survival was 31.9 weeks. Overall, 3 of 15 patients, with residual disease at the time of therapy, have demonstrated radiographic responses and one patient with a complete response and has survived greater than 83 weeks.     

An Alternative Approach to Study the Changes in the Cancer Pattern of Women in India (1988-2005)

Background: The changes in the cancer pattern are often studied with the help of changes in the rank ofleading sites, changes in the Age Adjusted Rates of the sites over the time or with the help of time trends. However,these methods do not quantify the changes in relation to overall changes that occurred in the total cancer casesover the period of time. An alternative approach was therefore used to assess the changes in cancer pattern inrelation to overall changes in time and also an attempt was made to identify the most emerging new cancers inIndia. Methods: The cancer incidence data of various sites for women, over the periods 1988-90 and 2003-05 inIndia, for five urban registries namely Bangalore, Bhopal, Chennai, Delhi and Mumbai, functioning under thenetwork of National Cancer Registry Programme (ICMR), formed the sources of data for the present analysis.The changes in incidence cases by various cancer sites for women were assessed by calculating the differences inincidence cases over the two period of time. Based on the contribution of each site to total change, the ten mostleading sites were identified separately for each registry. The relative changes in the sites with time were takento identify the most emerging new cancer cases over the period of time. Results: The pooled cancer cases forwomen among five urban registries increased from 29447 cases in 1988-90 to 48472 cases in 2003-05 registeringan increased of about 63.3%. The lowest percentage of increase was observed in the registry of Chennai (41.5%)and the maximum in Bhopal (102.0%). Based on the pooled figures, the breast cancer contributed to the maximum% change (38%), followed by ovarian (8.0%), gallbladder (5.1%), corpus uteri (4.9%) and cervix uteri (4.1%).Based on the pooled data and relative changes, the emerging new cancers were corpus uteri (187%), gallbladder(162.1%) and lung cancer (136.1%). The % change by sites and the emerging new cancers varied between theregistries.     

Loss of p53 enhances the function of the endoplasmic reticulum through activation of the IRE1α/XBP1 pathway

Altered regulation of ER stress response has been implicated in a variety of human diseases, such as cancer and metabolic diseases. Excessive ER function contributes to malignant phenotypes, such as chemoresistance and metastasis. Here we report that the tumor suppressor p53 regulates ER function in response to stress. We found that loss of p53 function activates the IRE1α/XBP1 pathway to enhance protein folding and secretion through upregulation of IRE1α and subsequent activation of its target XBP1. We also show that wild-type p53 interacts with synoviolin (SYVN1)/HRD1/DER3, a transmembrane E3 ubiquitin ligase localized to ER during ER stress and removes unfolded proteins by reversing transport to the cytosol from the ER, and its interaction stimulates IRE1α degradation. Moreover, IRE1α inhibitor suppressed protein secretion, induced cell death in p53-deficient cells, and strongly suppressed the formation of tumors by p53-deficient human tumor cells in vivo compared with those that expressed wild-type p53. Therefore, our data imply that the IRE1α/XBP1 pathway serves as a target for therapy of chemoresistant tumors that express mutant p53.