Cancer stem cell biomarkers SOX2 and Oct4 in cervical cancer patients undergoing chemoradiotherapy.

BACKGROUND: Cancer stem cell biomarkers SRY (sex-determining region Y)-box 2 (SOX2) and octamer-binding transcription factor 4 (Oct4) account for radioresistance in cervical squamous cell cancers (CSCCs). Their clinical implications are limited and contradictory. METHODS: In this prospective cohort study, we recruited patients with FIGO IB2-IVA CSCC treated with primary chemoradiotherapy on regular follow-up. Tissue biopsy specimens were evaluated for SOX2 and Oct4 expression by immunohistochemistry, quantified by a product of proportion and intensity scores. RESULTS: A total of 59 patients were included. Most had a moderately differentiated (81%), keratinizing (59%) CSCC, and ≥FIGO stage IIB disease (95%). SOX2 expression (high:low 21:38 patients) and Oct4 expression (high:low 4:55 patients) had a significant interrelation (p = 0.005, odds ratio (95% CI) - 1.23 (1.004-1.520)). At a median follow-up of 36 months, the 3-year overall survival (OS) was 60% and 53% for low and high SOX2 expression (p = 0.856), and 54% and 100% for low and high Oct4 expression (p = 0.114). The 3-year disease-frese survival (DFS) was 65% and 50% in the low and high SOX2 expression (p = 0.259), and 59% and 75% for low and high Oct4 expression (p = 0.598). SOX2 expression was the only variable significantly associated with a lower OS and DFS on regression analysis. CONCLUSION: Our study demonstrated a trend toward improved OS and DFS with low SOX2 and high Oct4 expression in CSCC patients undergoing chemoradiotherapy.

Serum Tumor Necrosis Factor-Alpha Levels in Acute Leukemia and Its Prognostic Significance.

Introduction Tumor necrosis factor-alpha (TNF-α) is a pleiotropic cytokine that facilitates malignant cells in immune evasion, survival, and treatment resistance by generating a favorable milieu for them. It is shown to be ectopically produced by malignant/leukemic and immune cells in the tumor microenvironment, providing a tumor-supportive environment and playing an important part in the establishment and progression of malignant cells. It is linked to hyperleukocytosis, high blast count, and poor clinical outcomes in acute leukemia (AL). Considering the varied role and different expression patterns of tumor necrosis factor-alpha in acute leukemia and its clinical relevance, the present study was planned to monitor the level of tumor necrosis factor-alpha in patients with acute leukemia and its correlation with disease outcome. The aim of this study was to monitor the level of tumor necrosis factor-alpha in patients with acute leukemia at the time of diagnosis and after induction chemotherapy. Material and methods The study included cases classified as acute leukemia based on morphological examination, bone marrow analysis, and flow cytometry. In all patients with acute leukemia (n = 90) and controls (n = 10), the serum tumor necrosis factor-alpha level was measured using a Diaclone Human ELISA kit (Diaclone, Besancon, France) (solid phase sandwich ELISA) at diagnosis and after induction chemotherapy. Results Tumor necrosis factor-alpha levels were substantially higher in T-acute lymphoblastic leukemia (T-ALL) cases, followed by acute myeloid leukemia (AML) and B-acute lymphoblastic leukemia (B-ALL), at the time of diagnosis, compared to the control. A significant reduction in serum tumor necrosis factor-alpha level was seen in patients with acute leukemia after induction phase chemotherapy (P < 0.05). Tumor necrosis factor-alpha levels were considerably reduced (P < 0.001) in the majority of acute leukemia cases after the induction phase, while high tumor necrosis factor-alpha levels were positively correlated with incomplete remission status in the remaining cases. Conclusion Tumor necrosis factor-alpha is involved in the progression of acute leukemia and its relapse. High levels of tumor necrosis factor-alpha are linked to leukocytosis, high blast counts, and worse survival in patients with acute leukemia. Monitoring of tumor necrosis factor-alpha may be helpful in patients with acute leukemia in view of available antitumor necrosis factor-alpha therapy.

Bleeding Versus Thrombotic Tendency in Young Children With Beta-Thalassemia Major.

Introduction Bleeding and thrombotic events are known to occur in beta-thalassemia major (BTM) patients and have been attributed to hepatic iron overload associated with multiple blood transfusions. We evaluated hemostatic parameters in children with BTM who had no previous history of bleeding or thrombotic episodes. Materials and Methods Hemostatic parameters including prothrombin time (PT), activated partial thromboplastin time (APTT), platelet aggregation, protein C and S, iron profile, and liver function tests were evaluated in 54 children (median age = 12 months, age range = 4-144 months) with BTM and 15 age and sex-matched controls. Results The mean PT and APTT of patients were significantly higher (P=0.016 and P <.001) than that of controls. Mean protein C, protein S activity and platelet aggregability with adenosine 5-diphosphate (ADP) as an agonist in patients were significantly lower (P <.001, P <.001 and P=0.007, respectively) than that in controls. Mean serum ferritin in BTM children was not significantly elevated to be associated with hepatic dysfunction. Conclusion Deranged hemostatic parameters indicative of bleeding and thrombotic tendencies are observed in BTM children from an early age and may not be solely due to hyperferritinemia-associated hepatic dysfunction. Despite the presence of deranged hemostatic parameters, a state of balance exists between bleeding and thrombosis, and an imbalance may lead to bleeding or thrombotic events at a later age.

Correlation of Hormone Receptor and Human Epidermal Growth Factor Receptor-2/neu Expression in Breast Cancer with Various Clinicopathologic Factors.

BACKGROUND: A significant development in the breast carcinoma management is the correlation between the presence of hormone receptors in the tumor and response to hormonal therapy and chemotherapy. Human epidermal growth factor receptor-2/neu (Her-2/neu) overexpression also serves as a very useful parameter to predict response to herceptin. AIM OF STUDY: The study was conducted to correlate immunohistochemical expression of markers such as estrogen receptor (ER), progesterone receptor (PR), and Her-2/neu with various clinicopathologic parameters. MATERIALS AND METHODS: The study included 509 cases of breast carcinoma over a period of 5 years (from May 2009 to May 2014). Immunohistochemistry (IHC) for ER, PR, and her-2/neu was performed. RESULTS: ER positivity was observed in 42.8% (218/509) cases, PR positivity in 31.8% (194/509) cases whereas her-2 neu positivity was seen in 40.7% (203/509) cases. Triple marker (ER, PR, and Her-2/neu) negative cases were 23.6% (120/509) cases. ER and PR expression was found to have a statistically significant correlation with tumor grade. Statistically significant correlation was observed between tumor size and tumor grade and her-2/neu expression. Her-2/neu expression showed statistically significant association with tumor stage. As the tumor grade increased, the proportion of triple-negative cases went on increasing, which was statistically significant. CONCLUSION: IHC has an increasingly important prognostic role in determination of factors that affect clinicopathologic features. Nevertheless, the results of this large series showed different patterns of findings with respect to clinicopathologic features.

Circulating Tumor Cells in Breast Cancer: Correlation with Clinicopathological Parameters, Hormone Profile and MicroRNA Polymorphisms.

OBJECTIVE: Circulating tumor cells are isolated tumor cells in the peripheral blood that serve as important prognostic indicators for many kind of tumors. The study was conducted to know the rate of detection of circulating tumor cells among breast cancer patients in comparison with benign breast diseases and control subjects and to know the association between CTC positivity and various clinicopathological parameters, hormonal profile and microRNA polymorphisms. MATERIAL AND METHOD: In the present case control study, we included 182 healthy controls, 108 cases of benign breast disease and 114 breast carcinoma cases. Various clinicopathological details of cases were recorded. Immunohistochemistry was performed for estrogen (ER) and progesterone receptors (PR) and Her-2 neu. Circulating tumor cells were analyzed using flow cytometry (EpCAM, CK, CD45). Genotypic frequency of micro RNA polymorphisms was determined by PCR-RFLP assay. RESULTS: Circulating tumor cell positivity was observed in 11/114 (9.64%) breast cancer cases but absent in benign and control groups, and was significantly associated with tumor size, histologic type, tumor grade, metastasis and skin infiltration (p < 0.05). Circulating tumor cell positivity did not show any correlation with the immunohistochemical profile. No significant associations between pre-miRNA genetic variations miR-196a2 C/T (rs11614913), miR-146a G/C (rs2910164) and miR-499 T > C (rs3746444) polymorphisms and circulating tumor cell positivity were observed. CONCLUSION: The flow cytometry protocol for detection and molecular characterization of circulating tumor cells is a time and cost-effective technique, suitable for routine clinical use. However, more elaborate studies are needed to establish the findings as our study was limited by small sample size.

Immunoprotective effect of lentinan in combination with miltefosine on Leishmania-infected J-774A.1 macrophages.

Rejuvenation of deteriorated host immune functions is imperative for successful annihilation of Leishmania parasites. The use of immunomodulatory agents may have several advantages as they conquer immunosuppression and, when given in combination, improve current therapeutic regimens. We herein investigated the immunostimulatory potency of a ß-glucan, lentinan either alone or in combination with short dose of standard drug, miltefosine on Leishmania-infected J-774A.1 macrophages. Our study shows that infected macrophages when stimulated with 2.5 µg/mL and above concentrations of lentinan secreted significant amount of host-protective molecules. The in vitro interaction between lentinan and miltefosine showed some synergy (mean sum of fractional inhibitory concentration [mean ∑FIC] 0.87) at IC50 level. Lentinan (2.5 µg/mL) plus low-dose miltefosine (2 µM) displayed heightened level of pro-inflammatory cytokines, IL-12 (13.6-fold) and TNF-α (6.8-fold) along with nitric oxide (7.2-fold higher) when compared with infected control. In combination group, we also observed remarkably (P<.001) suppressed levels of anti-inflammatory cytokines, IL-10 and TGF-ß, than that of untreated macrophages. Additionally, in comparison with infected group, we observed significant induction in phagocytic activity of macrophages in combination with treated group. Collectively, these findings emphasize the immunostimulatory effect of lentinan alone and in combination with low dose of miltefosine against Leishmania donovani.

Haemostatic Profile in Patients of Myeloproliferative Neoplasms-A Tertiary Care Centre Experience.

INTRODUCTION: Patients of MPN commonly present with abnormalities in laboratory coagulation tests that are consistent with hypercoagulable state. Some individuals with MPN exhibit a pattern of exclusive bleeding or thrombotic events; many others have both bleeding and thrombosis during the course of the disease. AIM: This study was undertaken to assess the haemostatic defects and platelet functions in patients of MPN. MATERIALS AND METHODS: One year prospective study was conducted at a tertiary care centre in North India in Department of Pathology in collaboration with Department of Clinical Haematology. All recently diagnosed cases of MPN along with 30 age and sex matched controls were included. Patients on antiplatelet drugs, antimyeloproliferative treatment, vitamin K agonists or antagonists, OCPs, Platelet count <1,00,000/µl, high grade fever, liver disease, pregnancy were excluded from this study. All the patients underwent screening investigations like CBC, peripheral smear evaluation, BT, PT, aPTT, Protein C and S measurement (clot based assay) and aggregation studies with ADP (5µM) (Optical Aggregometry with AGGRO/LINK 8 software and CHRONOLOG 700 aggregometer). RESULTS: In present study, 50 cases were included. There was an occult prothrombotic state, suggested by significantly (p<0.001) reduced levels of Protein C and Protein S, but no patient presented with frank thrombosis while 8 out of 50 patients had haemorrhagic manifestations ranging from subdural haematoma to pin point petechial haemorrhages. Patients of CML-CP, ET, PV, PMF, MPN-NOS showed significantly reduced maximal aggregation with ADP (5µM) when compared to control (p<0.001). MPV also showed a statistically significant increase in these patients. CONCLUSION: Thrombohaemorrhagic complications significantly affect the morbidity and mortality of MPN patients. This can be assessed by the use of platelet aggregation studies, Protein C and S activities and other coagulation studies. Timely diagnosis of these prothrombotic/haemorrhagic states can decrease the morbidity in these patients.

Common genetic variants in pre-microRNAs and risk of breast cancer in the North Indian population.

OBJECTIVE: MicroRNAs (miRNAs) are short regulatory RNAs that can modulate gene expression and function as negative regulators. Common genetic variants like single nucleotide polymorphisms (SNPs) in miRNA genes may alter their expression or maturation resulting in varied functional consequences in carcinogenesis. Therefore, we evaluated the genetic variants in pre-miRNAs: hsa-miR-146a G/C (rs2910164), hsa-miR-196a2 C/T (rs11614913), and hsa-miR-499 T>C (rs3746444) for their role in breast cancer susceptibility. STUDY DESIGN: The study comprised 121 breast cancer patients, 115 with benign breast disease, and 164 controls. The genotypic frequency of miRNA polymorphisms was determined by PCR-RFLP assay. Logistic regression was used for statistical analysis using SPSS Software version 15.0. In silico analysis was done using various bioinformatics tools (F-SNP, FAST-SNP). RESULTS: The heterozygous variant of miR-146a G/C (rs2910164) is associated with the reduced risk of breast cancer at the genotype level as well as at the allele level (p < 0.05, OR = 0.5) as compared to controls. On the contrary, no significant difference was observed in the distribution of miR-196a2 C/T (rs11614913) and miR-499 T>C (rs3746444) polymorphisms in any groups both at genotype and allele levels. On the other hand, in multivariate analysis, we found that the miR-196a2 (rs11614913) C>T was associated with an increased risk of breast cancer risk in postmenopausal females (p = 0.02, OR = 3.2). We also attempted to find out the risk of malignant breast disease in relation to each of the above SNPs on dividing our data on the basis of benign and malignant status, but no significant difference was observed. In silico analysis using F-SNP showed change in transcriptional regulation by miR-146a G/C (rs2910164), miR-196a2 C/T (rs11614913) and miR-499 T>C (rs3746444) variations; the functional score was 0.100, 0.065 and 0.277, respectively. CONCLUSION: The results of the present study demonstrate that miR-146a G/C (rs2910164) polymorphism is associated with reduced genetic susceptibility to breast cancer. However, multivariate analysis showed as miR-196a2 (rs11614913) C>T to be associated with increased risk of breast cancer risk in postmenopausal females. Further multicentric studies involving a large number of cases need to be carried out to strengthen the present results.

Grading systems in the cytological diagnosis of breast cancer: a review.

In developing countries, diagnosis of breast carcinoma is still made on fine-needle aspiration cytology (FNAC). For the resource-poor settings, FNAC is cheaper, less invasive and can sample different areas of the lesion compared with core needle biopsy. The role of breast FNA is usually limited to just categorize the lesion as benign or malignant. Prognostic information from cytomorphology, conveyed to the clinician depends upon the cytopathologist's way of formatting the report. PubMed-based literature search collated the information from articles describing the architectural and cytological features studied on breast aspiration smears. This review focuses on cytomorphological features and the different grading systems with their strengths, short-comings, and practical applicability. Eight worldwide articles proposing new methods of grading the cytological smears from breast cancers were published between 1980 and 2006. All the grading methods were developed for the most common type of breast cancer, that is, infiltrating duct carcinoma (not otherwise specified) type, and most of the workers used Papanicolaou-stained smears for the purpose of grading. Moreover, if interpreted carefully FNAC smears can convey information on most of the histological features. Hence, in developing countries, the focus should be on extracting the maximum information from cytological smears, so that a more precise "surgical pathology" type diagnosis can be given, instead of merely reporting as benign or malignant. Among all the discussed grading systems, we suggest grading system by Howell would be most appropriate and closest to the accepted histologic grading system as it applies Scarff-Bloom-Richardson histological grading system with modifications on FNA smears. We recommend it to be followed by all cytopathologists, in order to bring uniformity in the reporting of breast FNAs for grading the malignant lesions.

Comparative evaluation of the modified Scarff-Bloom-Richardson grading system on breast carcinoma aspirates and histopathology.

BACKGROUND: Fine needle aspiration (FNA) is a quick, minimally invasive procedure for evaluation of breast tumors. The Scarff-Bloom-Richardson (SBR) grade on histological sections is a well-established tool to guide selection of adjuvant systemic therapy. Grade evaluation is possible on cytology smears to avoid and minimize the morbidity associated with overtreatment of lower grade tumors. AIM: The aim was to test the hypothesis whether breast FNA from the peripheral portion of the lesion is representative of Scarff-Bloom-Richardson grade on histopathology as compared to FNA from the central portion. MATERIALS AND METHODS: Fine-needle aspirates and subsequent tissue specimens from 45 women with ductal carcinoma (not otherwise specified) were studied. FNAs were performed under ultrasound guidance from the central as well as the peripheral third of the lesion for each case avoiding areas of necrosis/calcification. The SBR grading was compared on alcohol fixed aspirates and tissue sections for each case. RESULTS: Comparative analysis of SBR grade on aspirates from the peripheral portion and histopathology by the Pearson chi-square test (χ(2) =78.00) showed that it was statistically significant (P<0.001) with 93% concordance. Lower mitotic score on aspirates from the peripheral portion was observed in only 4 out of 45 (9%) cases. The results of the Pearson chi-square test (χ(2) = 75.824) with statistically significant (P=0.000). CONCLUSION: This prospective study shows that FNA smears from the peripheral portion of the lesion are representative of the grading performed on the corresponding histopathological sections. It is possible to score and grade by SBR system on FNA smears.

Basal expression studies of cystatins during specific growth stages of wheat spikes for defining their possible role in differential and stage dependent immunity against Karnal bunt (Tilletia indica).

Two genotypes showing differential immunity against Karnal bunt (Tilletia indica) were used to investigate the role of three members of cystatin gene family in growth stage dependent immunity in wheat (Triticum aestivum L.). Three members of cystatin gene family (WC1, WC2, and WC4) were cloned and sequenced. Analysis of sequenced data showed that there was 76-99% nucleotide and protein sequence identity between different genes of the wheat cystatin. In silico amino acid sequence analysis revealed the presence of a conserved signature pattern of residues and also the functional domains were presumed to be actively involved in imparting cysteine protease inhibition capability. The semi-quantitative and quantitative levels of these members were measured by means of RT-PCR, northern blotting, western blotting, and by ELISA techniques. The members of cystatin gene family were expressed in both resistant (HD 29) and susceptible genotypes (WH 542); however, the expression level was significantly (P < 0.001) higher in resistant compared to susceptible genotype at all the stages of wheat spikes. The patterns of expression of WC2, WC4 were similar except in the levels in S(1) and S(2) stages as it remained constant (P > 0.05) in contrary to WC1 family whose expression gradually increased from S(v) to S(2) stage. According to the intensity of the detected band in RT PCR, northern blot and western blot, WC1 family seems to be expressed more than the other gene families. The immunoassay results further showed that WC1 protein was abundantly expressed in resistant genotype and high expression was observed at the S2 stage as compared to susceptible genotype (P < 0.001) suggesting that low level of expression of WC1 in S2 stage is responsible for KB infection. The results of the present study clearly indicate the role of cystatin gene family in differential and stage dependent immunity against KB.

Retinoic acid receptors and tissue-transglutaminase mediate short-term effect of retinoic acid on migration and invasion of neuroblastoma SH-SY5Y cells.

Long-term treatment with all trans-retinoic acid (RA) induces neuronal differentiation and apoptosis. However, the effect of short-term RA treatment on cell proliferation, migration and invasion of neuroblastoma cell lines (SH-SY5Y and IMR-32) remains unclear. RA induces expression of tissue-transglutaminase (TGase) and promotes migration and invasion after 24 h of treatment in SH-SY5Y cells, but not in IMR-32 cells. RA receptor (RAR) agonist (4-(E-2-[5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthalenyl]-1-propenyl) benzoic acid) and RAR/retinoid X receptor (RXR) agonist (9-cis-RA) promote expression of TGase, migration and invasion of SH-SY5Y cells, while RXR agonist has no significant effect. RAR antagonist blocks RA effect on migration and invasion, indicating that RAR receptors are required. Retinoid receptors are expressed and activated by RA in both cell lines. However, only transient activation of RAR is observed in IMR-32 cells. These findings suggest that different responses observed in SH-SY5Y and IMR-32 cells could be due to differential activation of retinoid receptors. Overexpression of TGase has no effect on migration or invasion, while overexpression of antisense TGase blocks RA-induced migration and invasion, indicating that other molecules along with TGase mediate RA effects. In addition to the long-term effects of RA that are coupled with cell differentiation, short-term effects involve migration and invasion of neuroblastoma SH-SY5Y cells.

Effects of tissue transglutaminase on retinoic acid-induced cellular differentiation and protection against apoptosis.

Retinoic acid (RA) and its various synthetic analogs affect mammalian cell growth, differentiation, and apoptosis. Whereas treatment of the human leukemia cell line HL60 with RA results in cellular differentiation, addition of the synthetic retinoid, N-(4-hydroxyphenyl) retinamide (HPR), induces HL60 cells to undergo apoptosis. Moreover, pretreatment of HL60 cells as well as other cell lines (i.e. NIH3T3 cells) with RA blocks HPR-induced cell death. In attempting to discover the underlying biochemical activities that might account for these cellular effects, we found that monodansylcadaverine (MDC), which binds to the enzyme (transamidase) active site of tissue transglutaminase (TGase), eliminated RA protection against cell death and in fact caused RA to become an apoptotic factor, suggesting that the ability of RA to protect against apoptosis is linked to the expression of active TGase. Furthermore, it was determined that expression of exogenous TGase in cells exhibited enhanced GTP binding and transamidation activities and mimicked the survival advantage imparted by RA. We tested whether the ability of this dual function enzyme to limit HPR-mediated apoptosis was a result of the ability of TGase to bind GTP and/or catalyze transamidation and found that GTP binding was sufficient for the protective effect. Moreover, excessive transamidation activity did not appear to be detrimental to cell viability. These findings, taken together with observations that the TGase is frequently up-regulated by environmental stresses, suggest that TGase may function to ensure cell survival under conditions of differentiation and cell stress.

The nuclear cap-binding complex is a novel target of growth factor receptor-coupled signal transduction.

In an attempt to further understand how nuclear events (such as gene expression, nuclear import/export, and cell cycle checkpoint control) might be subject to regulation by extracellular stimuli, we sought to identify nuclear activities under growth factor control. Using a sensitive photoaffinity labeling assay that measured [alpha-32P]GTP incorporation into nuclear proteins, we identified the 20-kDa subunit of the nuclear cap-binding complex (CBC) as a protein whose binding activity is greatly enhanced by the extracellular stimulation of serum-arrested cells. The CBC represents a 20- and 80-kDa heterodimer (the subunits independently referred to as CBP20 and CBP80, respectively) that binds the 7-methylguanosine cap on RNAs transcribed by RNA polymerase II. This binding facilitates precursor messenger RNA splicing and export. We have demonstrated that the [alpha-32P]GTP incorporation into CBP20 was correlated with an increased ability of the CBC to bind capped RNA and have used the [alpha-32P]GTP photoaffinity assay to characterize the activation of the CBC in response to growth factors. We show that the CBC is activated by heregulin in HeLa cells and by nerve growth factor in PC12 cells as well as during the G1/S phase of the cell cycle and when cells are stressed with UV irradiation. Additionally, we show that cap-dependent splicing of precursor mRNA, a functional outcome of CBC activation, can be catalyzed by growth factor addition to serum-arrested cells. Taken together, these data identify the CBC as a nuclear target for growth factor-coupled signal transduction and suggest novel mechanisms by which growth factors can influence gene expression and cell growth.

Identification of the eukaryotic initiation factor 5A as a retinoic acid-stimulated cellular binding partner for tissue transglutaminase II.

GTP-binding protein/transglutaminases (tissue transglutaminases or TGases) have been implicated in a variety of cellular processes including retinoic acid (RA)-induced apoptosis. Recently, we have shown that RA activates TGases as reflected by stimulated GTP binding, increased membrane association, and stimulated phosphoinositide lipid turnover. This prompted us to search for cellular proteins that bind TGases in a RA-stimulated manner. In this report, we show that the eukaryotic initiation factor (eIF-5A), a protein that is essential for cell viability, perhaps through effects on protein synthesis and/or RNA export, associates with the TGase in vivo. The interaction between eIF-5A and TGase is specific for the GDP-bound form of the TGase and is not detected when the TGase is pre-loaded with GTP gamma S. The TGase-eIF-5A interaction also is promoted by Ca2+, Mg2+, and RA treatment of HeLa cells. In the presence of retinoic acid, millimolar levels of Ca2+ are no longer required for the TGase-eIF-5A interaction. Nocodazole treatment, which blocks the cell cycle at mitosis (M phase), strongly inhibits the interaction between eIF-5A and cytosolic TGase. The interaction between TGase and eIF-5A and its sensitivity to the nucleotide-occupied state of the TGase provides a potentially interesting connection between RA signaling and protein synthesis and/or RNA trafficking activities.

The role of 3-hydroxyethyldeoxyuridine in mutagenesis by ethylene oxide.

Ethylene oxide, a direct-acting mutagen and carcinogen, produces 3-hydroxyethyldeoxyuridine (3-HE-dU) after initial alkylation at N3 of dC, followed by rapid hydrolytic deamination. The significance of formation of 3-HE-dU in DNA was investigated by in vitro DNA replication of 3-HE-dU. A 55-nucleotide DNA template, containing 3-HE-dU at a single site, was constructed. DNA products, synthesized on the site-modified template, were analyzed and mutagenic bypass at 3-HE-dU estimated. The 3-HE-dU lesion blocked DNA replication by the Klenow fragment of Escherichia coli polymerase I (Kf Pol I) and bacteriophage T7 polymerase (T7 Pol) 3' to 3-HE-dU and after incorporating a nucleotide opposite 3-HE-dU. DNA synthesis past 3-HE-dU was negligible (< 3%). Substitution of Kf Pol I (exo-) and T7 Pol (exo-), polymerases lacking 3'-->5' exonuclease proofreading activity, for Kf Pol I and T7 Pol, respectively, facilitated DNA synthesis past 3-HE-dU. The bypass synthesis by Kf Pol I (exo-) was 60% and 90% by T7 Pol (exo-). These results suggest that the 3-HE-dU lesion could be bypassed, but that the extension at 3-HE-dU is rate-limiting. In the absence of proofreading, the nucleotide incorporated opposite 3-HE-dU is not excised and remains in position long enough for extension to occur. During post-lesion synthesis, both dA and dT were incorporated opposite 3-HE-dU. Since 3-HE-dU is derived from dC alkylation by ethylene oxide, incorporation of dA and dT opposite 3-HE-dU implicates this lesion in G.C-->A.T and G.C-->T.A mutagenesis.

In vitro reactions of 2-cyanoethylene oxide with calf thymus DNA.

2-cyanoethylene oxide (CEO) is a direct-acting mutagen and the postulated proximate carcinogenic form of acrylonitrile (AN). We have studied the reactions of CEO with 2'-deoxyribonucleosides and in vitro with calf thymus DNA at pH 7.0-7.5 and 37 degrees C for 3 h. Reaction of CEO with dAdo gave 2 adducts, N6-(2-hydroxy-2-carboxyethyl)-dAdo (N6-HOCE-dAdo) (2% yield) and 1,N6-etheno-dAdo (epsilon-dAdo) (11%); reaction with dCyd resulted in the isolation of 3-HOCE-dUrd (22%); reaction with dGuo gave 7-(2-oxoethyl)-Gua (7-OXE-Gua) (31%) and reaction with dThd yielded 3-OXE-dThd (3%). Structural elucidation of adducts was accomplished by ultraviolet spectroscopy, high-field proton NMR spectroscopy and mass spectrometry. Structural confirmation was provided by an accurate mass measurement technique where diagnostic ions in the electron impact mass spectra of trimethylsilyl derivatives were measured to within 0.0007 atomic mass units. The facile Dimroth rearrangement of 1-HOCE-dAdo to N6-HOCE-dAdo and hydrolytic deamination of a dCyd adduct to 3-HOCE-dUrd is postulated to be catalyzed by the hydroxyl group on the 3-carbon side chain of the adduct. Reaction of CEO with calf thymus DNA yielded (nmol/mg DNA) N6-HOCE-dAdo (2); epsilon-dAdo (11); 3-HOCE-dUrd (80); 7-OXE-Gua (110) and 3-OXE-dThd (1). Thus CEO, like its metabolic precursor AN, directly alkylates DNA in vitro but at a much more rapid rate.

Lead-induced fetal nephrotoxicity in iron-deficient rats.

Lead administration (250, 500, 1000, and 2000 ppm, as lead acetate) in drinking water during fetal development (from 15 to 20 days of gestation), in normal and iron-deficient pregnant rats, revealed dose-dependent increases in the lead content of maternal blood that was more marked in iron-deficient animals. The placentae and fetuses did not show a dose-dependent increase in lead content. Lead administration revealed dose-dependent hydropic degeneration of renal proximal cells in the fetuses. The highest dose (2000 ppm lead) and iron deficiency exhibited more lead accumulation in maternal blood, placentae, and fetuses, and maximum pathologic changes in the fetal kidney when compared with the other doses and also with the fetuses of dams not deficient in iron.