Unprocessed genomic uracil as a source of DNA replication stress in cancer cells

Alterations of bases in DNA constitute a major source of genomic instability. It is believed that base alterations trigger base excision repair (BER), generating DNA repair intermediates interfering with DNA replication. Here, we show that genomic uracil, a common type of base alteration, induces DNA replication stress (RS) without being processed by BER. In the absence of uracil DNA glycosylase (UNG), genomic uracil accumulates to high levels, DNA replication forks slow down, and PrimPol-mediated repriming is enhanced, generating single-stranded gaps in nascent DNA. ATR inhibition in UNG-deficient cells blocks the repair of uracil-induced gaps, increasing replication fork collapse and cell death. Notably, a subset of cancer cells upregulates UNG2 to suppress genomic uracil and limit RS, and these cancer cells are hypersensitive to co-treatment with ATR inhibitors and drugs increasing genomic uracil. These results reveal unprocessed genomic uracil as an unexpected source of RS and a targetable vulnerability of cancer cells.

APOBEC3A induces DNA gaps through PRIMPOL and confers gap-associated therapeutic vulnerability

Mutation signatures associated with apolipoprotein B mRNA editing catalytic polypeptide-like 3A/B (APOBEC3A/B) cytidine deaminases are prevalent across cancers, implying their roles as mutagenic drivers during tumorigenesis and tumor evolution. APOBEC3A (A3A) expression induces DNA replication stress and increases the cellular dependency on the ataxia telangiectasia and Rad3-related (ATR) kinase for survival. Nonetheless, how A3A induces DNA replication stress remains unclear. We show that A3A induces replication stress without slowing replication forks. We find that A3A induces single-stranded DNA (ssDNA) gaps through PrimPol-mediated repriming. A3A-induced ssDNA gaps are repaired by multiple pathways involving ATR, RAD51, and translesion synthesis. Both ATR inhibition and trapping of poly(ADP-ribose) polymerase (PARP) on DNA by PARP inhibitor impair the repair of A3A-induced gaps, preferentially killing A3A-expressing cells. When used in combination, PARP and ATR inhibitors selectively kill A3A-expressing cells synergistically in a manner dependent on PrimPol-generated gaps. Thus, A3A-induced replication stress arises from PrimPol-generated ssDNA gaps, which confer a therapeutic vulnerability to gap-targeted DNA repair inhibitors.

ATR inhibition induces synthetic lethality in mismatch repair-deficient cells and augments immunotherapy

The mismatch repair (MMR) deficiency of cancer cells drives mutagenesis and offers a useful biomarker for immunotherapy. However, many MMR-deficient (MMR-d) tumors do not respond to immunotherapy, highlighting the need for alternative approaches to target MMR-d cancer cells. Here, we show that inhibition of the ATR kinase preferentially kills MMR-d cancer cells. Mechanistically, ATR inhibitor (ATRi) imposes synthetic lethality on MMR-d cells by inducing DNA damage in a replication- and MUS81 nuclease-dependent manner. The DNA damage induced by ATRi is colocalized with both MSH2 and PCNA, suggesting that it arises from DNA structures recognized by MMR proteins during replication. In syngeneic mouse models, ATRi effectively reduces the growth of MMR-d tumors. Interestingly, the antitumor effects of ATRi are partially due to CD8+ T cells. In MMR-d cells, ATRi stimulates the accumulation of nascent DNA fragments in the cytoplasm, activating the cGAS-mediated interferon response. The combination of ATRi and anti-PD-1 antibody reduces the growth of MMR-d tumors more efficiently than ATRi or anti-PD-1 alone, showing the ability of ATRi to augment the immunotherapy of MMR-d tumors. Thus, ATRi selectively targets MMR-d tumor cells by inducing synthetic lethality and enhancing antitumor immunity, providing a promising strategy to complement and augment MMR deficiency-guided immunotherapy.

The RNA m5C modification in R-loops as an off switch of Alt-NHEJ

The roles of R-loops and RNA modifications in homologous recombination (HR) and other DNA double-stranded break (DSB) repair pathways remain poorly understood. Here, we find that DNA damage-induced RNA methyl-5-cytosine (m5C) modification in R-loops plays a crucial role to regulate PARP1-mediated poly ADP-ribosylation (PARylation) and the choice of DSB repair pathways at sites of R-loops. Through bisulfite sequencing, we discover that the methyltransferase TRDMT1 preferentially generates m5C after DNA damage in R-loops across the genome. In the absence of m5C, R-loops activate PARP1-mediated PARylation both in vitro and in cells. Concurrently, m5C promotes transcription-coupled HR (TC-HR) while suppressing PARP1-dependent alternative non-homologous end joining (Alt-NHEJ), favoring TC-HR over Alt-NHEJ in transcribed regions as the preferred repair pathway. Importantly, simultaneous disruption of both TC-HR and Alt-NHEJ with TRDMT1 and PARP or Polymerase θ inhibitors prevents alternative DSB repair and exhibits synergistic cytotoxic effects on cancer cells, suggesting an effective strategy to exploit genomic instability in cancer therapy.

ATR protects ongoing and newly assembled DNA replication forks through distinct mechanisms

The ATR kinase safeguards genomic integrity during S phase, but how ATR protects DNA replication forks remains incompletely understood. Here, we combine four distinct assays to analyze ATR functions at ongoing and newly assembled replication forks upon replication inhibition by hydroxyurea. At ongoing forks, ATR inhibitor (ATRi) increases MRE11- and EXO1-mediated nascent DNA degradation from PrimPol-generated, single-stranded DNA (ssDNA) gaps. ATRi also exposes template ssDNA through fork uncoupling and nascent DNA degradation. Electron microscopy reveals that ATRi reduces reversed forks by increasing gap-dependent nascent DNA degradation. At new forks, ATRi triggers MRE11- and CtIP-initiated template DNA degradation by EXO1, exposing nascent ssDNA. Upon PARP inhibition, ATRi preferentially exacerbates gap-dependent nascent DNA degradation at ongoing forks in BRCA1/2-deficient cells and disrupts the restored gap protection in BRCA1-deficient, PARP-inhibitor-resistant cells. Thus, ATR protects ongoing and new forks through distinct mechanisms, providing an extended view of ATR's functions in stabilizing replication forks.

Excessive transcription-replication conflicts are a vulnerability of BRCA1-mutant cancers

BRCA1 mutations are associated with increased breast and ovarian cancer risk. BRCA1-mutant tumors are high-grade, recurrent, and often become resistant to standard therapies. Herein, we performed a targeted CRISPR-Cas9 screen and identified MEPCE, a methylphosphate capping enzyme, as a synthetic lethal interactor of BRCA1. Mechanistically, we demonstrate that depletion of MEPCE in a BRCA1-deficient setting led to dysregulated RNA polymerase II (RNAPII) promoter-proximal pausing, R-loop accumulation, and replication stress, contributing to transcription-replication collisions. These collisions compromise genomic integrity resulting in loss of viability of BRCA1-deficient cells. We also extend these findings to another RNAPII-regulating factor, PAF1. This study identifies a new class of synthetic lethal partners of BRCA1 that exploit the RNAPII pausing regulation and highlight the untapped potential of transcription-replication collision-inducing factors as unique potential therapeutic targets for treating cancers associated with BRCA1 mutations.

The metabolic enzyme hexokinase 2 localizes to the nucleus in AML and normal haematopoietic stem and progenitor cells to maintain stemness

Mitochondrial metabolites regulate leukaemic and normal stem cells by affecting epigenetic marks. How mitochondrial enzymes localize to the nucleus to control stem cell function is less understood. We discovered that the mitochondrial metabolic enzyme hexokinase 2 (HK2) localizes to the nucleus in leukaemic and normal haematopoietic stem cells. Overexpression of nuclear HK2 increases leukaemic stem cell properties and decreases differentiation, whereas selective nuclear HK2 knockdown promotes differentiation and decreases stem cell function. Nuclear HK2 localization is phosphorylation-dependent, requires active import and export, and regulates differentiation independently of its enzymatic activity. HK2 interacts with nuclear proteins regulating chromatin openness, increasing chromatin accessibilities at leukaemic stem cell-positive signature and DNA-repair sites. Nuclear HK2 overexpression decreases double-strand breaks and confers chemoresistance, which may contribute to the mechanism by which leukaemic stem cells resist DNA-damaging agents. Thus, we describe a non-canonical mechanism by which mitochondrial enzymes influence stem cell function independently of their metabolic function.

Thomas, Egan et al. report that hexokinase 2 localizes to the nucleus of leukaemic and normal haematopoietic cells to maintain stemness by interacting with nuclear proteins and modulating chromatin accessibility independently of its kinase activity.

Emerging roles of DNA topoisomerases in the regulation of R-loops

R-loops are comprised of a DNA:RNA hybrid and a displaced single-strand DNA (ssDNA) that reinvades the DNA duplex behind the moving RNA polymerase. Because they have several physiological functions within the cell, including gene expression, chromosomal segregation, and mitochondrial DNA replication, among others, R-loop homeostasis is tightly regulated to ensure normal functioning of cellular processes. Thus, several classes of enzymes including RNases, helicases, topoisomerases, as well as proteins involved in splicing and the biogenesis of messenger ribonucleoproteins, have been implicated in R-loop prevention, suppression, and resolution. There exist six topoisomerase enzymes encoded by the human genome that function to introduce transient DNA breaks to relax supercoiled DNA. In this mini-review, we discuss functions of DNA topoisomerases and their emerging role in transcription, replication, and regulation of R-loops, and we highlight how their role in maintaining genome stability can be exploited for cancer therapy.

BRCA1 and Metastasis: Outcome of Defective DNA Repair

Simple Summary

BRCA1 has critical functions in accurately repairing double stand breaks in the DNA through a process known as homologous recombination. BRCA1 also has various functions in other cellular processes that safeguard the genome. Thus, mutations or silencing of this tumor suppressor significantly increases the risk of developing breast, ovarian, and other cancers. Metastasis refers to the spread of cancer to other parts of the body and is the leading cause of cancer-related deaths. In this review, we discuss the mechanisms by which BRCA1 mutations contribute to the metastatic and aggressive nature of the tumor cells.

Abstract

Heritable mutations in BRCA1 and BRCA2 genes are a major risk factor for breast and ovarian cancer. Inherited mutations in BRCA1 increase the risk of developing breast cancers by up to 72% and ovarian cancers by up to 69%, when compared to individuals with wild-type BRCA1. BRCA1 and BRCA2 (BRCA1/2) are both important for homologous recombination-mediated DNA repair. The link between BRCA1/2 mutations and high susceptibility to breast cancer is well established. However, the potential impact of BRCA1 mutation on the individual cell populations within a tumor microenvironment, and its relation to increased aggressiveness of cancer is not well understood. The objective of this review is to provide significant insights into the mechanisms by which BRCA1 mutations contribute to the metastatic and aggressive nature of the tumor cells.

Exploiting synthetic lethality to target BRCA1/2-deficient tumors: where we stand

The principle of synthetic lethality, which refers to the loss of viability resulting from the disruption of two genes, which, individually, do not cause lethality, has become an attractive target approach due to the development and clinical success of Poly (ADP-ribose) polymerase (PARP) inhibitors (PARPi). In this review, we present the most recent findings on the use of PARPi in the clinic, which are currently approved for second-line therapy for advanced ovarian and breast cancer associated with mutations of BRCA1 or BRCA2 (BRCA1/2) genes. PARPi efficacy, however, appears to be limited by acquired and inherent resistance, highlighting the need for alternative and synergistic targets to eliminate these tumors. Here, we explore other identified synthetic lethal interactors of BRCA1/2, including DNA polymerase theta (POLQ), Fanconi anemia complementation group D2 (FANDC2), radiation sensitive 52 (RAD52), Flap structure-specific endonuclease 1 (FEN1), and apurinic/apyrimidinic endodeoxyribonuclease 2 (APE2), as well as other protein and nonprotein targets, for BRCA1/2-mutated cancers and their implications for future therapies. A wealth of information now exists for phenotypic and functional characterization of these novel synthetic lethal interactors of BRCA1/2, and leveraging these findings can pave the way for the development of new targeted therapies for patients suffering from these cancers.

RNF168 regulates R-loop resolution and genomic stability in BRCA1/2-deficient tumors

Germline mutations in BRCA1 and BRCA2 (BRCA1/2) genes considerably increase breast and ovarian cancer risk. Given that tumors with these mutations have elevated genomic instability, they exhibit relative vulnerability to certain chemotherapies and targeted treatments based on poly (ADP-ribose) polymerase (PARP) inhibition. However, the molecular mechanisms that influence cancer risk and therapeutic benefit or resistance remain only partially understood. BRCA1 and BRCA2 have also been implicated in the suppression of R-loops, triple-stranded nucleic acid structures composed of a DNA:RNA hybrid and a displaced ssDNA strand. Here, we report that loss of RNF168, an E3 ubiquitin ligase and DNA double-strand break (DSB) responder, remarkably protected Brca1-mutant mice against mammary tumorigenesis. We demonstrate that RNF168 deficiency resulted in accumulation of R-loops in BRCA1/2-mutant breast and ovarian cancer cells, leading to DSBs, senescence, and subsequent cell death. Using interactome assays, we identified RNF168 interaction with DHX9, a helicase involved in the resolution and removal of R-loops. Mechanistically, RNF168 directly ubiquitylated DHX9 to facilitate its recruitment to R-loop-prone genomic loci. Consequently, loss of RNF168 impaired DHX9 recruitment to R-loops, thereby abrogating its ability to resolve R-loops. The data presented in this study highlight a dependence of BRCA1/2-defective tumors on factors that suppress R-loops and reveal a fundamental RNF168-mediated molecular mechanism that governs cancer development and vulnerability.

Strategic Training in Transdisciplinary Radiation Science for the 21st Century (STARS21): 15-Year Evaluation of an Innovative Research Training Program

PURPOSE

To evaluate the 15-year impact of a transdisciplinary research training program for graduate students, postdoctoral fellows, and clinical trainees focused on radiation science, entitled Strategic Training in Transdisciplinary Radiation Science for the 21st Century (STARS21) with a primary objective to build capacity in radiation research.

METHODS AND MATERIALS

Alumni (n = 128) and mentors (n = 41) who participated in STARS21 between 2003 and 2018 were sent an anonymized online survey designed to evaluate the program. Twelve alumni and 7 mentors also volunteered to participate in semistructured interviews. The transcribed interviews were coded and analyzed using NVivo12-Pro software. Alumni employment and publications were assessed from program records and by web-based search queries.

RESULTS

Alumni are located in 11 countries, and nearly 90% are employed in a research-oriented career and continue to publish in radiation medicine- or cancer-related fields. Of those invited, 46 alumni (36%) and 12 mentors (29%) completed the online survey. Approximately 87% of alumni valued interdisciplinary collaboration, and 80% indicated that STARS21 had encouraged them to pursue such collaborations. Alumni emphasized that STARS21 assisted their career development, and the majority of alumni and mentors would recommend STARS21 to other trainees (4.48 and 4.58, respectively; 5 = strongly agree). The time invested in the program was perceived by mentors as worthwhile for the knowledge and skills gained by trainees (4.67; 5 = strongly agree), and 64% of mentors indicated that these benefits were associated with improved trainee research productivity. From the alumni and mentor perspectives, the valuable skills acquired from STARS21 included scientific communication (85% and 83%, respectively) and networking (83% and 92%, respectively).

CONCLUSIONS

STARS21 is an innovative research training program that promotes interdisciplinary collaboration in radiation medicine research, which is valued by alumni and mentor respondents. Alumni can acquire important skill sets for career development, with a large proportion of alumni currently engaged in radiation research around the world.

Nucleolar RNA polymerase II drives ribosome biogenesis

Proteins are manufactured by ribosomes-macromolecular complexes of protein and RNA molecules that are assembled within major nuclear compartments called nucleoli1,2. Existing models suggest that RNA polymerases I and III (Pol I and Pol III) are the only enzymes that directly mediate the expression of the ribosomal RNA (rRNA) components of ribosomes. Here we show, however, that RNA polymerase II (Pol II) inside human nucleoli operates near genes encoding rRNAs to drive their expression. Pol II, assisted by the neurodegeneration-associated enzyme senataxin, generates a shield comprising triplex nucleic acid structures known as R-loops at intergenic spacers flanking nucleolar rRNA genes. The shield prevents Pol I from producing sense intergenic noncoding RNAs (sincRNAs) that can disrupt nucleolar organization and rRNA expression. These disruptive sincRNAs can be unleashed by Pol II inhibition, senataxin loss, Ewing sarcoma or locus-associated R-loop repression through an experimental system involving the proteins RNaseH1, eGFP and dCas9 (which we refer to as 'red laser'). We reveal a nucleolar Pol-II-dependent mechanism that drives ribosome biogenesis, identify disease-associated disruption of nucleoli by noncoding RNAs, and establish locus-targeted R-loop modulation. Our findings revise theories of labour division between the major RNA polymerases, and identify nucleolar Pol II as a major factor in protein synthesis and nuclear organization, with potential implications for health and disease.

Abstract 3784: The metabolic enzyme Hexokinase 2 localizes to the nucleus and regulates stemness in AML through a kinase independent mechanism

Leukemia stem cells are responsible for the initiation and recurrence of AML. Cell differentiation requires the coordination of metabolic state and gene expression programs. It is known that metabolic intermediates can serve as cofactors in epigenetic modifications in the nucleus. Whether metabolic enzymes can directly localize to the nucleus, influence gene expression and regulate stemness in AML is unknown. To identify mitochondrial metabolic enzymes that localize to the nucleus of stem cells we analyzed stem and bulk fractions of 8227 leukemia cells, which are arranged in a hierarchy with functionally defined stem cells in the CD34+CD38- fraction. Hexokinase 2 (HK2) was detected in the nuclear fraction of 8227 cells and nuclear HK2 was increased in 8227 stem cells compared to bulk cells. Conversely, the metabolic enzymes aconitase, citrate synthesase, enolase, fumarase, GAPDH, glucose-6-phosphate isomerase, phosphofructokinase, pyruvate kinase and succinate dehydrogenase A were not detectable in the nuclear fraction of either stem or bulk cells. We confirmed that HK2 was present in the nuclear fraction of OCI-AML2, NB4, HL60 and TEX AML cell lines and 7/9 primary patient samples. To determine whether nuclear HK2 was functionally important for AML stem cells, we overexpressed HK2 tagged with a nuclear localizing sequence (PAAKRVKLD). Over-expression of nuclear localized HK2 enhanced clonogenic growth and engraftment into immune deficient mice. Likewise, over-expression of nuclear localized HK2 blocked differentiation after treatment with all-trans retinoic acid (ATRA). Next, we investigated whether the kinase activity of HK2 was necessary for its nuclear effects on AML stemness and differentiation. We generated a kinase dead mutant of HK2 (D209A, D657A) tagged with a nuclear localizing signal (PAAKRVKLD). Over-expression of nuclear-localized kinase dead HK2 exerted a similar phenotype to overexpressed nuclear HK2 without manipulation of the kinase domain as it enhanced clonogenic growth and blocked cell differentiation after ATRA treatment. To understand the mechanism by which nuclear HK2 influenced AML stemness, we identified proteins that interacted with nuclear HK2 using proximity-dependent biotin labeling (BioID) and mass spectrometry. Proteins involved in DNA damage repair and chromatin remodeling were identified, including exonuclease 3′-5′ domain-containing 2 (EXD2), sirtuin 1 (SIRT1), E3 ubiquitin-protein ligase (URB5) and tyrosyl-DNA phosphodiesterase 2 (TDP2). Thus, our data suggest that nuclear HK2 influences DNA repair, which has been linked to stemness and differentiation. In support of this hypothesis, we identified a PAR binding motif in HK2 and over-expression of nuclear HK2 conferred resistance to the PARP inhibitor, olaparib. In summary, HK2 localizes to the nucleus in AML stem cells and maintains stemness. These effects are independent of its kinase activity. Rather, HK2 may regulate DNA damage repair through a PAR dependent mechanism. Thus, we have identified a new role for metabolic enzymes in the regulation of stemness and differentiation.

Citation Format: Grace Egan, Geethu E. Thomas, Parasvi S. Patel, Jordan Chin, Aaron Botham, Rose Hurren, Neil MacLean, Razq Hakem, Aaron D. Schimmer. The metabolic enzyme Hexokinase 2 localizes to the nucleus and regulates stemness in AML through a kinase independent mechanism [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3784.

Ubiquitin ligase RNF8 suppresses Notch signaling to regulate mammary development and tumorigenesis

The E3 ubiquitin ligase RNF8 plays critical roles in maintaining genomic stability by promoting the repair of DNA double-strand breaks (DSBs) through ubiquitin signaling. Abnormal activation of Notch signaling and defective repair of DSBs promote breast cancer risk. Here, we found that low expression of the full-length RNF8 correlated with poor prognosis for breast cancer patients. Our data revealed that in addition to its role in the repair of DSBs, RNF8 regulated Notch1 signaling and cell-fate determination of mammary luminal progenitors. Mechanistically, RNF8 acted as a negative regulator of Notch signaling by ubiquitylating the active NOTCH1 protein (N1ICD), leading to its degradation. Consistent with abnormal activation of Notch signaling and impaired repair of DSBs in Rnf8-mutant mammary epithelial cells, we observed increased risk of mammary tumorigenesis in mouse models for RNF8 deficiency. Notably, deficiency of RNF8 sensitized breast cancer cells to combination of pharmacological inhibitors of Notch signaling and poly(ADP-ribose) polymerase (PARP), suggesting implications for treatment of breast cancer associated with impaired RNF8 expression or function.

Serum Glycoconjugates in Patients with Anemia and Myeloid Leukemia

Because of carbohydrate alterations in malignant cells, serum glycoproteins have drawn considerable attention. In the current investigation we determined total sialic acid (TSA), lipid bound sialic acid (LSA), protein bound hexoses (galactose+mannose), fucose, hexosamines (galactosamine+glucosamine) and mucoid protein concentrations in the serum of patients with anemia and myeloid leukemia. The results were compared with those obtained in healthy individuals. In the leukemia patients we observed significant increases in glycoconjugates compared with the controls (P < 0.001), and in TSA and fucose levels compared with the anemia patients (P < 0.001). LSA and hexosamine levels were significantly lower in anemia patients with respect to the leukemia patients (P < 0.01 and P < 0.05 respectively), whereas levels of mucoid proteins and hexoses did not show significant differences. Except for hexosamines, all the markers tested were significantly elevated in the anemia patients compared with the controls. The present study suggests that the glycoconjugates investigated might be useful biochemical markers for differentiating anemic from leukemic conditions.

Role of Sialic Acid and Alkaline Dnase in Breast Cancer

Serum levels of sialic acid and alkaline DNase (ADA) were analysed in 495 blood samples collected from 170 breast cancer patients before and during/after anticancer treatment. Fifty-six healthy females were included in the study to define the cutoff values. The markers were analysed by highly sensitive spectrophotometric methods. Statistical evaluation of the data was done using Student's ‘t’ test, paired ‘t’ test and ROC curve analysis. The total sialic acid (TSA), lipid bound sialic acid (LSA) and ADA in sera of untreated breast cancer patients were significantly higher than in controls. ROC curve analysis revealed TSA and LSA to be useful markers for diagnosis of breast cancer. Serum levels of TSA and LSA were significantly decreased in complete responders as compared to their pretreatment values. The pretreatment ADA values showed much individual variation. However, responders showed higher levels of ADA than untreated patients. In nonresponders the values of the biomarkers were comparable with pretreatment levels. The study suggested that TSA and LSA can be helpful in the diagnosis of breast cancer. All three markers can be used for assessment of response to anticancer treatment in breast cancer patients.

Tumor Markers in Leukemia: Evaluation of Serum Levels of Different Forms of Sialic Acid, Regan Isoenzyme and Lactate Dehydrogenase

A sensitive and specific serum marker can greatly help in the early diagnosis of malignancy as well as in monitoring the treatment of cancer patients. The present work was initiated for determining serum levels of Total Sialic Acid (TSA), Lipid Bound Sialic Acid (LSA), Free Sialic Acid (FSA), Regan Isoenzyme (RI) and Lactate Dehydrogenase (LDH), so as to evaluate their value as potential tumor markers. Fifty patients with anemia and 78 patients with leukemia were studied. The leukemia group consisted of 32 cases of Acute Myeloid Leukemia (AML), 29 cases of Chronic Myeloid Leukemia (CML) and 17 cases of Acute Lymphatic Leukemia (ALL). The levels were compared with the values obtained from 88 healthy individuals. Compared to the healthy controls, all the biomarkers were significantly elevated in patients with anemia as well as in those with leukemia. However, in leukemia patients significantly higher levels of TSA, LSA, FSA and LDH were observed compared to anemia patients. TSA levels were significantly higher in AML patients compared to CML and ALL patients. LSA levels were also significantly higher in AML patients compared to ALL patients. LSA was the most sensitive (84.6%) while FSA and RI levels were the most specific (78.0%) markers for leukemia. The combined use of the markers showed increased sensitivity and specificity (100.0% and 98.0%, respectively). The study suggested that the biomarkers investigated might be used for differentiating anemic from leukemic conditions, however, more in-depth studies are indicated to assess their utility in classifying various leukemias.

Clinical implications of p53 alterations in oral cancer progression: a review from India

p53 plays a central role in prevention of normal cell from the development of the malignant phenotype. Somatic alterations (mutations, loss of heterozygosity, deletions) in p53 are a hallmark of most human cancers and cause defects in normal p53 function. However, in the tumors harboring wild-type p53, there are alterations in the regulation of the p53. Thus, understanding why p53 is unable to perform its role as a tumor suppressor in these wild-type tumors is very crucial. Germ-line polymorphisms in p53 are also anticipated to cause measurable disturbance in p53 function. Over-expression as well as polymorphic variants of MDM2 might have effects on cancer development. In addition, degradation of p53 by E6 protein of high risk human papillomavirus is also suggested as one of the mechanisms which attenuate p53 responses in oral carcinogenesis. p53 has also been demonstrated to mediate cellular responses upon various DNA damaging cancer therapies, importantly, apoptosis. These responses have been implicated in an individual's ability to respond to these cancer therapies. Thus, exploring mechanisms by which normal function of p53 is affected in the comprehensive way in oral cancer might aid in the identification of tumor characteristics, prognosis and thus in the development of a new approach to treat the oral cancer.

An evaluation of the feasibility and validity of a patient-administered malnutrition universal screening tool ('MUST') compared to healthcare professional screening in an inflammatory bowel disease (IBD) outpatient clinic

BACKGROUND

Malnutrition is common in inflammatory bowel disease (IBD) and is associated with poor health outcomes. Despite this, screening for malnutrition in the outpatient-setting is not routine and research in the area is limited. The present study aimed to evaluate whether agreement between malnutrition screening completed by patients and healthcare professionals (HCPs) could be achieved by comparing patient self-administered 'MUST' ('MUST'-P) with HCP administered 'MUST' ('MUST'-HCP) in a single tertiary IBD outpatient clinic.

METHODS

We conducted a feasibility and validity study on adult outpatients with IBD. We collected anthropometric, nutritional and clinical data from patients. All patients completed 'MUST'-P using a self-administered questionnaire, followed by 'MUST'-HCP. 'MUST'-P was timed and feedback on ease-of-use was obtained. The risk of malnutrition was classified as low (score = 0), medium (score = 1) and high (score ≥ 2) and agreement was tested using kappa statistics (κ).

RESULTS

Eighty patients were recruited (Crohn's disease: n = 49, ulcerative colitis: n = 29, unclassified: n = 2), with a mean (SD) age of 39.9 (15.1) years (51.2% were males). Seventy-one (92%) of patients found 'MUST'-P either easy or very easy. The mean (SD) time to complete 'MUST'-P was 3.1  (1.8) min (range 1-10 min). Sixty-eight (85%) of patients were at low risk of malnutrition when screened by the HCP. There was moderate agreement (κ = 0.486, P < 0.001) between 'MUST'-P and 'MUST'-HCP, with 100% agreement in scoring for medium- and high-risk categories.

CONCLUSIONS

The results of the present study suggests that self-screening using 'MUST' could be effectively used in an IBD outpatient clinic to identify those at medium and high risk of malnutrition. The patient friendly version of 'MUST' ('MUST'-P) was considered quick and easy to use by patients. Implementation of self-screening with 'MUST' could improve the nutritional management of IBD patients.

Synthesis and Physico-Chemical Properties of 2-Morpholino-4,6-Dichloro-S-Triazine with Various Aromatic Diols

Several homopolycyanurates were synthesized by stirred interfacial polycondensation of 2-morpholino-4,6-dichloro- s-triazine with various aromatic diols such as 1,5- dihydroxynaphthalene,(DHN-1,5),1,7-dihydroxynapthalene(DHN-1,7),2,7-dihydroxynapthalene resorcinol (R), catechol (C), hydroquinone (H) and phenolphthalein (Ph). They were characterized by density, viscosity measurements, IR spectra, solubility tests and thermogravimetric analysis. The polymer had reduced viscosities in the range 0.468 to 0.829 dl g−1 in chromoform at 30 °C. All the polymers were amorphous and soluble in chlorinated solvents. The thermal stability of polycyanurates decreases in the following matter:

PCDHN-1,5 > PCDHN-1,7 > PCPh > PCR ≃ PCDHN-2,7 > PCHQ > PCC.

Arylene Azo p-Hydroxy Benzoic Acid–Formaldehyde Oligomer Dyes

A series of oligomeric azo dyes has been synthesized by coupling various aromatic diazonium salts to p-hydroxy benzoic acid–formaldehyde ( p-HBAF) oligomer. They were evaluated in terms of their softening points, yields, colour, UV–visible spectra, IR spectra and PMR spectra. Dyeing on wool and nylon resulted in yellow to red shades having moderate to good fastness to light and good to very good fastness to washing.

Mycophenolate and nephrology

Several large, randomized trials have established mycophenolate mofetil (MMF) as an effective immunosuppressant for kidney transplantation. Inhibition of inosine 5′-monophospate dehydrogenase (IMPDH) by MMF appears to have pleiotropic effects on both immune and non-immune cells. In addition to B- and T-cell inhibition, in vitro and in vivo data suggest that MMF also has inhibitory effects on smooth muscle cells, endothelial cells, and myofibroblasts, findings that may be relevant in considering treatment of primary immune mediated kidney diseases. Clinical trials have established the efficacy of MMF for the treatment of lupus nephritis, as discussed in detail elsewhere in this supplement. Although animal studies have provided the rationale for human trials of MMF in primary glomerular diseases, most of the evidence thus far is conflicting or based largely on pilot studies. Data from larger, controlled trials will soon emerge and may clarify the role of MMF in the treatment of these disorders.

Clinical significance of matrix metalloproteinase 2 and 9 in breast cancer

BACKGROUND

Invasion and metastasis are the most strenuous problems in the management of breast cancer. These events require diverse proteolytic enzymes, among which MMP-2 and MMP-9 play a significant role in degradation of type IV collagen, the major component of the basement membrane. Therefore, the major objective of the study is to evaluate the clinical usefulness of MMP-2 and MMP-9 with respect to malignant tumor growth, invasion, and metastasis in breast cancer.

MATERIALS AND METHODS

Gelatin zymography was performed on 157 tissue extracts of malignant and adjacent normal breast tissues as well as negative and positive lymph nodes from 49 breast cancer patients. Statistical analysis was carried out using SPSS statistical software (version 10).

RESULTS

ProMMP-2 levels were significantly higher in adjacent normal tissues. Active MMP-2 and MMP-9 levels were higher in malignant breast tissues. Activation ratios of MMP-2 and MMP-9 were significantly higher in malignant breast tissues and in patients with lymph node metastasis. ProMMP-2, active MMP-2, and active MMP-9 could significantly discriminate between malignant and adjacent normal breast tissues. The MMP-2 activation ratio showed significant discriminatory efficacy between patients with and without lymph node metastasis and significant association with increased risk of lymph node metastasis in node-negative patients.

CONCLUSION

The results indicate significant clinical utility of these proteolytic enzymes in malignant tumor growth, invasion, and metastasis in breast cancer.

A new recurring chromosome 13 abnormality in two older patients with de novo acute myeloid leukemia: An Indian experience

We report here two cases of trisomy 13 in acute myeloid leukemia M1 subtype. short-term unstimulated bone marrow and peripheral blood lymphocyte culture showed 47, XY, +13 in all metaphase plates and trisomy 13 was confirmed with whole chromosome paint probes. Trisomy 13 in AML-M1 is a rare numerical abnormality. This is the first Indian report of sole trisomy 13 in AML-M1. Here, we present two cases of elder male patients, which may constitute a distinct subtype.

E-Cadherin truncation and sialyl Lewis-X overexpression in oral squamous cell carcinoma and oral precancerous conditions

The present study aimed to determine significance of E-cadherin, a cell adhesion molecule, and sialyl Lewis-X (sLeX), a cell surface antigen, in oral carcinogenesis. Expressions of E-cadherin and sLeX were detected using western blot analysis from oral malignant (n=25), and oral precancerous tissues (OPC, n=20) and their adjacent normal tissues. An altered expression of E-cadherin (E-cad) and sLeX was observed in malignant and precancerous tissues. E-cad western blot revealed presence of two bands, a 120 kDa (native, E-cad120) and a 97 kDa (known as truncated E-cad97). The accumulation of truncated E-cad97 and sLeX in malignant and OPC tissues compared to their adjacent normal tissues was observed. Receiver's Operating Characteristics (ROC) curve analysis showed good discriminatory efficacy of E-cad97, E-cad97:120 ratio and sLeX between the malignant and adjacent. normal tissues. Further, a positive correlation of E-cad97 and sLeX overexpression with advanced stage of the disease and lymphnode metastasis was observed. The data suggest that E-cadherin truncation and sLeX overexpression are early events which may facilitate the tumor cells to metastasize. Also, overexpression E-cad97 and sLeX in OPC tissues may be useful to predict metastatic potentials of tumors at an early stage of oral carcinogenesis. Key words: Oral cancer, oral precancerous conditions, E-cadherin, sialyl Lewis-X, metastasis.

A case of acute myeloid leukemia-M2 with trisomy 4 in addition to t(8;21)

t(8;21)(q22;q22) is the most frequently observed karyotypic abnormality associated with acute myeloid leukemia (AML), specifically in FAB-M2. Short-term unstimulated bone marrow (BM) and peripheral blood lymphocyte culture showed 47,XX, +4,t(8;21) in all metaphase plates; and interphase and metaphase results of AML-ETO fusion was positive and trisomy of 4 was confirmed with WCP probes. Trisomy 4 in AML with t(8;21) is a rare numerical abnormality. Here we present such case of patient which may constitute a distinctive subtype.

Alterations in plasma lipid profile patterns in head and neck cancer and oral precancerous conditions

BACKGROUND

The changes in lipid profile have long been associated with cancer because lipids play a key role in maintenance of cell integrity.

AIMS

The present study evaluated alterations in plasma lipid profile in untreated head and neck cancer patients as well as patients with oral precancerous conditions (OPC) and its association with habit of tobacco consumption.

MATERIAL AND METHODS

This hospital-based case control study included 184 head and neck cancer patients, 153 patients with OPC and 52 controls. Plasma lipids including: (i) Total cholesterol, (ii) LDL cholesterol (LDLC), (iii) HDL cholesterol (HDLC) (iv) VLDL cholesterol (VLDLC) and (v) triglycerides were analysed by spectrophotometric kits.

STATISTICAL ANALYSIS USED

Student's t-test was performed to compare mean values of the parameters.

RESULTS

A significant decrease in plasma total cholesterol and HDLC was observed in cancer patients (P=0.008 and P=0.000 respectively) as well as in patients with OPC (P=0.014 and P=0.000, respectively) as compared to the controls. The plasma VLDL and triglycerides levels were significantly lower in cancer patients as compared to the patients with OPC (P=0.04) and controls (P=0.059). The tobacco habituates showed lower plasma lipid levels than the non-habituates. Our data strengthen the evidence of an inverse relationship between plasma lipid levels and head and neck malignancies as well as OPC.

CONCLUSION

The lower levels of plasma cholesterol and other lipid constituents in patients might be due to their increased utilization by neoplastic cells for new membrane biogenesis. The findings strongly warrant an in-depth study of alterations in plasma lipid profile in head neck cancer patients.

Evaluation of serum sialic acid, sialyltransferase and sialoproteins in oral cavity cancer

OBJECTIVE

Altered glycosylation of glycoconjugates is among the important molecular changes that accompany malignant transformation. The aim of our study was to investigate clinical usefulness of circulatory levels of sialic acid, sialoproteins and sialyltransferase for early diagnosis and management of oral cavity cancer (OC) patients.

MATERIALS AND METHODS

Blood samples collected from 210 untreated OC patients, 100 patients with oral precancerous conditions (OPC) and 100 healthy males. OC patients were followed after initiation of anticancer treatment and 394 follow-up samples were also collected. Serum sialic acid levels were measured spectrophotometrically. Sialyltransferase activity was analysed using radioassay. Alpha 2-6 sialoproteins were isolated using lectin affinity chromatography.

RESULTS

Serum levels of free, protein bound and total sialic acid as well as their ratio with total proteins were significantly elevated in untreated OC patients compared with healthy individuals, patients with OPC as well as complete responders (CR). Levels of the markers were comparable between untreated OC patients and non-responders. We observed positive correlation between serum levels of the markers and extent of malignant disease. Serum sialyltransferase activity showed significant elevations in OC patients compared with the controls (P<0.001), patients with OPC (P<0.05) and CR (P<0.05). Higher sialic acid levels in OC patients at the time of diagnosis showed poor survival. The changes in serum proteins with terminal alpha 2-6 sialic acid correlated well with the alterations in the levels of sialic acid forms and sialyltransferase activity.

CONCLUSION

Our results confirmed the elevations in sialic acid and sialyltransferase levels in OC patients and suggested potential utility of these parameters in prognostication and treatment monitoring of this neoplasm. The alterations in these parameters in circulation were in accordance with the changes in alpha 2-6 sialylated proteins.

Serum glutathione-S-transferase and glutathione reductase activity in head and neck cancer patients

Glutathione, an antioxidant plays an important role in phase-II detoxification of carcinogens. The levels of reduced glutathione are maintained by glutathione-depleting as well as replenishing enzymes such as glutathione-s-transferase (GST) and glutathione reductase (GR), respectively. Pre and post treatment changes in GST and GR activities in head and neck cancer patients were analysed. Serum GST and GR were analysed from untreated head and neck cancer patients (PT) (n=146), controls with habit of tobacco (VHT) (n=25) as well as without (no) habit of tobacco (NHT) (n=25) and patients with oral precancerous conditions (OPC) (n=50). The cancer patients were followed-up after initiation of anticancer therapy. Follow-up blood samples were collected. Serum GST and GR activities were estimated by highly sensitive and specific spectrophotometric methods. Untreated cancer patients showed elevated mean serum GST and GR activities as compared to NHT. Patients with OPC had declined mean GST activity as compared to WHT and untreated cancer patients. Paired t-test revealed that complete responders (CR) showed significantly elevated GST levels and declined GR activities (p < 0.001) as compared to those in PT. No correlation was found between stage of the disease and GST, GR activity. Paired t-test showed significant decreased in GR activity in nonresponders (NR) treated with radiotherapy (p=0.01). The study suggested that analysis of glutathione and glutathione-depleting enzymes can be helpful for treatment monitoring of head and neck cancer patients.

Role of pretherapeutic biomarkers in predicting postoperative radiotherapy response in patients with advanced squamous cell carcinoma

PURPOSE

To assess the role of biomarker levels in predicting radiotherapy (RT) response in patients with squamous cell carcinoma of buccal mucosa treated with postoperative RT.

MATERIALS AND METHODS

Thirty-one patients with squamous cell carcinoma of buccal mucosa who received postoperative RT were enrolled for the study. Glutathione S-transferase (GST), glutathione reductase (GR), superoxide dismutase (SOD) and catalase activity were analysed from primary tumour and adjacent normal mucosa of the same patients before RT. p53 and p21ras were localized immunohistochemically.

RESULTS

Enzyme activation was predicted by comparing the levels of these enzymes in tumour and adjacent normal mucosa. Deactivation of GST, activation of GR, SOD and catalase were associated with poor response to RT. p53 immunoreactivity was associated with failure to respond to RT.

CONCLUSIONS

These markers may be useful in predicting treatment outcome in patients receiving postoperative RT, although this conclusion requires confirmation in a larger group of patients.

Xerostomic complaints induced by an anti-sialogogue in healthy young vs. older adults

Complaints of xerostomia and salivary hypofunction are common in older adults. However, recent studies reported that dehydration-induced salivary hypofunction caused fewer xerostomic complaints in older compared with young adults. This may predispose older adults to developing oral problems that will subsequently not receive attention from health care providers. Since many medications are known to inhibit salivation, this study attempted to determine if an anticholinergic drug (glycopyrrolate) had a differential effect on xerostomic complaints in young vs. older adults. Eighteen young (age 20-38 yrs) and 18 older (age 60-77 yrs) healthy adults were given a 4.0 micrograms/kg dose of i.v. glycopyrrolate. For 6 hrs after drug administration, stimulated parotid salivary flow was collected, and an eight-item Visual Analogue Scale (VAS) subjective xerostomia test was given. At several time points post-i.v. glycopyrrolate, salivary flow rates were consistently lower in older compared with young adults. For some measures of xerostomic complaint (time to first complaint; time to maximum complaint; mean maximum complaint), there were no age-related differences for all VAS items. However, a trend for increased xerostomic complaints in older adults was demonstrated (time to recovery; total duration of complaint; number xerostomic at 6 hrs). These findings suggest that, given equal doses of an anti-sialogogue, salivary hypofunction is greater in healthy older adults, while increased complaints of xerostomia are not as consistent.

Evaluation of serum alkaline DNase activity in treatment monitoring of head and neck cancer patients

Our previously published data on breast cancer suggest that serum alkaline DNase, a known circulating tumour marker, can be used for treatment monitoring of cancer patients. Serum alkaline DNase activities were analyzed in 215 untreated head and neck cancer patients. The enzyme activity ranged from 0.17 to 97.97 IKU/l in untreated cancer patients. Responders (n = 314) showed significantly elevated activity of alkaline DNase as compared to untreated cancer patients (p < 0.001). While non-responders (n = 168) showed comparable activity with untreated cancer patients. Serum alkaline DNase activities were significantly elevated in responders as compared to non-responders (p < 0.001). Our clinical studies during follow-up of patients indicated that the variations in serum alkaline DNase activities in individual patients correlate closely with response to therapy. Serum alkaline DNase also appeared to be useful in predicting treatment response in the long-term follow-up of patients. Serum alkaline DNase was systematically examined as a possible indicator for recurrence in patients under complete remission. In conclusion, serum alkaline DNase may be useful as a treatment monitoring in patients with head and neck malignancies.

Assessment of glutathione-S-transferase and glutathione reductase in patients with squamous-cell carcinoma of buccal mucosa

Serum and tumor cytosolic levels of glutathione-S-transferase (GST) and glutathione-reductase (GR) activity were determined spectrophotometrically. The levels were correlated with clinicopathological criteria and a tobacco-associated protein band (T band) found in serum. The results showed significantly decreased mean serum GST levels (p < 0.02) in cancer patients as compared with controls. However, mean serum GR levels were significantly higher in patients than in controls (p < 0.01). T-band-positive patients showed low GST and low GR activity as compared with T-band-negative patients. Tumor cytosolic-enzyme levels of GST and GR activity were significantly higher (p < 0.0003 and p < 0.0001, respectively) than in corresponding adjacent noncancerous mucosa. Tumour cytosolic GST and GR activity showed significant association with clinicopathologic criteria, e.g., stage, histologic grade and nodal involvement. T-band-negative patients showed significantly higher levels of GST (p < 0.0001) than did T-band-positive patients. Low levels of cytosolic GST may be associated with increased susceptibility towards carcinogen-induced damage. The results suggest that the presence of T band in the sera may be associated with a high-risk phenotype due to decreased detoxification ability.

Evaluation of telomerase activation in head and neck cancer

During replication of the linear chromosomes, telomeres, i.e. the ends of the chromosomes, are not replicated completely by the conventional DNA polymerases. Therefore, normal somatic cells senesce after certain number of cell divisions. Telomerase is a special reverse transcriptase used by most eukaryotes to achieve immortalization. Telomerase activity has been determined in a variety of cancers. However, there are few reports on telomerase activity in head and neck cancer. The etiology of the disease in India is completely different from Western countries. Tobacco consumption is more prevalent in India and the mode of tobacco consumption (e.g. chewing, snuffing, bidi smoking, reverse smoking) is also different. The present study determined telomerase activity in 32 malignant tumour samples of head and neck cancer patients, 11 samples from patients with precancerous/benign lesions and 30 samples of adjacent normal tissues. Telomerase was found to be activated in 80% of the patients with head and neck cancer, 100% of the patients with precancerous/benign lesions and 74% of the adjacent normal tissues. According to the theory of field cancerization, carcinogenic insults (e.g. tobacco) may result into multiple malignant foci. This fact may explain the reason for high telomerase positivity in adjacent normal as well as precancerous/benign tissues. Telomerase activation and the clinical or histopathological characteristics of the head and neck cancer patients were observed to be independent features. This is a preliminary report which has generated a greater interest for in-depth elucidation of the role of telomerase and telomeres in head and neck carcinogenesis in India.

Evaluation of glycoprotein constituents in head and neck cancer patients undergoing radiotherapy

BACKGROUND

Alterations in serum levels of several glycoprotein constituents are reported to be useful for treatment monitoring of cancer patients. The purpose of this study was to determine efficacy of sialic acid and seromucoid fraction as treatment monitors for head and neck (H&N) cancer patients undergoing radiotherapy (RT).

METHODS

Serum levels of total sialic acid (TSA), lipid-bound sialic acid (LSA), and seromucoid fraction (measured as Mucoid protein [MP] and hexose) were studied in age matched controls and in patients with H&N cancer at diagnosis and during/after completion of RT. The markers were estimated by spectrophotometric methods.

RESULTS

Serum levels of sialic acid forms and seromucoid fraction were significantly elevated (p<.001) in untreated H&N cancer patients (n = 32) as compared with controls (n = 50). The marker levels were significantly declined (p<.001) in H&N cancer patients who responded to RT as compared with their levels at diagnosis, whereas the levels were persistently elevated in nonresponders.

CONCLUSION

Evaluation of sialic acid forms and seromucoid fraction could be used for monitoring the treatment of H&N cancer patients undergoing RT.

Seromucoid fraction: a useful biomarker for patients with breast cancer

Seromucoid fraction was measured in terms of mucoid proteins (MP) and hexose content from sera of 1) 47 healthy women, 2) 48 women who had benign breast diseases, 3) 151 untreated patients with breast cancer, and 4) 245 follow-up samples collected from the same breast cancer patients. Mucoid proteins and hexose levels were found to be significantly elevated in untreated patients with breast cancer when compared with the healthy participants (p < 0.001) and patients who had benign breast diseases (p < 0.02 and p < 0.05, respectively). Receiver operating characteristic (ROC) curve analysis revealed potential diagnostic application of both markers for breast cancer. A good correlation was observed between favorable treatment response and decline in serum-marker levels. The markers in patients who did not respond to anticancer therapy remained stable or increased during follow-up. These data indicate that seromucoid fraction can be an useful biochemical marker for breast cancer patients.

Glycoprotein electrophoretic pattern in sera of patients with oral precancerous conditions and upper aerodigestive tract cancer

Cancer of the upper aerodigestive tract is one of the leading sites of human malignancies in India. Various glycoproteins have been claimed to be specifically associated with cancer. Serum glycoprotein electrophoresis was carried out in sera obtained from 23 healthy individuals [10 without habit of tobacco consumption (NHT) 13 with habit of tobacco consumption (WHT)], 46 patients with oral precancerous conditions (OPC) and 110 untreated patients with upper aerodigestive tract cancer. Eighty-six samples from the cancer patients were also collected after initiation of anticancer therapy. The albumin, alpha, beta and gamma region glycoproteins were quantitated by densitometric scanning after separation by polyacrylamide disc gel (PADG) electrophoresis. Mean values of albumin and alpha region glycoproteins were significantly lower in WHT and patients with OPC as compared to NHT. The gamma region glycoproteins were significantly elevated in WHT, patients with OPC and untreated cancer patients as compared to the NHT. The albumin region glycoproteins were significantly low, whereas, gamma region glycoproteins were significantly elevated in nonresponders as compared to their pretreatment levels. The glycoprotein values in complete responders were comparable with NHT. An extra glycoprotein band was found in the post beta region, in most of the individuals (>50%) with habit of tobacco consumption in all the groups. There was a decrease in the albumin/gamma, alpha/gamma and beta/gamma values in patients with OPC as well as untreated cancer patients as compared to NHT. Albumin/gamma, alpha/gamma and beta/gamma values were lower in nonresponders as compared to their pretreatment value. The results indicate that the alterations in glycoprotein electrophoresis pattern may be useful for early detection of cancer of the upper aerodigestive tract. It may also be helpful in treatment monitoring of cancer patients.

Importance of glycoproteins in human cancer

Usefulness of cell surface glycoprotein components as markers in early detection of cancer and in monitoring progress during treatment has been evaluated. Total sialic acid (TSA), lipid bound sialic acid (LSA) and seromucoid fractions (SF) have been compared in the sera of healthy human volunteers and patients at different stages of diagnosis and treatment of leukemia, cancer of breast, cervix, and oral cavity. The levels of TSA, LSA and SF are found to be increased in cancer and is proportionate with malignancy. Their levels show decline in patients who respond well to treatment and show increase in patients with recurrence of cancer even before any clinical evidence of recurrence is available. Changes have also been noted in the glycoprotein fractions and their ratios.

Electrophoretic pattern of serum glycoproteins on polyacrylamide disc gel in patients with breast cancer

Numerous investigators have identified, isolated and characterized serum glycoproteins that are claimed to be specifically associated with malignancy. We have carried out serum glycoprotein electrophoresis on polyacrylamide disc gel in 53 breast cancer patients, at diagnosis as well as during and after therapy. Follow-up samples were divided into complete responders (CR) (n = 138) and nonresponders (NR) (n = 44). Glycoprotein electrophoresis showed multiple bands for each sample which were categorized into four groups: albumin, alpha, beta and gamma. The results revealed a decreasing number of CR and increasing number of NR with elevated (as compared to pretreatment levels) albumin fraction glycoproteins. Gamma region glycoproteins showed the reverse pattern to that of albumin region glycoproteins. The alpha and beta region glycoproteins revealed an increasing number of CR having higher values with increase in follow-up duration. In comparison with their pretreatment values CR showed significantly increased (Paired "t" test) values of albumin, alpha and beta region glycoproteins (p < 0.01, p < 0.001 and p < 0.001, respectively) and decreased gamma region glycoproteins (p < 0.001). The albumin, alpha, beta and gamma region glycoprotein levels were comparable between NR and untreated cancer patients. The variations in albumin, alpha, beta and gamma region glycoproteins correlate with treatment response, which might be useful in the treatment monitoring, and prediction of recurrence in breast cancer patients.

Type characterisation and antibiotic susceptibility of Burkholderia (Pseudomonas) cepacia isolates from patients with cystic fibrosis in the United Kingdom and the Republic of Ireland

The spread of Burkholderia cepacia among cystic fibrosis (CF) patients in the UK prompted an investigation into whether an epidemic strain was responsible. A total of 366 B. cepacia isolates from 178 CF patients in 17 centres was examined by ribotyping and pulsed-field gel electrophoresis (PFGE). Associations were also sought between antibiotic resistance and strain type. More than 50 ribotype patterns were found but one, termed ribotype 1, was identified from 68 patients in eight centres. One centre had a single patient with this type while, in others, most or all patients harboured this organism. Small clusters of apparent cross-colonisation within centres were also evident for some other ribotypes. PFGE confirmed that ribotype 1 isolates were genetically similar. Ribotype 1 isolates were not markedly more resistant to antimicrobial agents than were other isolates, and the MICs of individual antibiotics were no more tightly clustered for ribotype 1 isolates than for others. Most isolates were resistant to ciprofloxacin, amikacin, gentamicin, tobramycin, carbenicillin, cefuroxime, cefotaxime, imipenem, biapenem, chloramphenicol, tetracycline, trimethoprim and sulphamethoxazole, but > or = 77% were susceptible to ceftazidime, piperacillin, piperacillin/ tazobactam and meropenem. We conclude that numerous strains of B. cepacia colonise CF patients in the UK and Ireland but that one epidemic strain has spread in at least eight centres. Isolates of this strain appear homogenous in total genomic profile but very variable in antibiotic susceptibility.

Mutational analysis of the endothelin type A receptor (ETA): interactions and model of selective ETA antagonist BMS-182874 with putative ETA receptor binding cavity

Endothelin (ET) receptor antagonism is a potential therapeutic intervention in the treatment of vascular diseases. To elucidate the mechanism of antagonist-ET receptor complex formation, the interactions of four chemically distinct antagonists were investigated using a combination of genetic and biochemical approaches. By site-specific mutagenesis we previously demonstrated that Tyr129 in the second transmembrane domain was critical for high-affinity, subtype-selective binding to the A subtype of ET (ETA) receptors [Krystek et al. (1994) J. Biol. Chem. 269, 12383-12386]. Affinities of the constrained cyclic pentapeptide BQ-123, the pyrimidinylbenzenesulfonamide bosentan, the indancarboxlic acid SB 209670, and the naphthalenesulfonamide BMS-182874 were decreased 20-1000-fold in Tyr129Ala, Tyr129Ser, and Tyr129His ETA receptor mutants. Substitution of Tyr129 with Phe or Trp did not alter the high-affinity binding of BQ-123, bosentan, or SB 209670. BMS-182874 binding affinity was decreased 10-fold in Tyr129Phe and Tyr129trp ET receptors. These data indicate a role of aromatic interactions in the binding of these antagonists to ETA receptors an, in the case of BMS-182874, also suggested a hydrogen bond with the tyrosine hydroxyl. This hypothesis was supported by structure-activity data with analogs of BMS-182874 that varied the C-5 dimethylamino substituent on the naphthalene ring. Mutation of Asp126 and Asp133 also altered binding of BMS-182874 and C-5 analogs. In all cases, naphthalenesulfonamide binding was more severely affected by mutation of Asp133 than by mutation of Asp126. Phosphoinositide hydrolysis and extracellular acidification rate studies demonstrated the importance of Tyr129 to ETA-mediated signal transduction. On the basis of these data, two plausible models of the docked conformation of BMS-182874 in the ETA receptor are proposed as a starting point for further delineation of interactions that underlie antagonist-ETA receptor complex formation.

Bacillaene, a novel inhibitor of procaryotic protein synthesis produced by Bacillus subtilis: production, taxonomy, isolation, physico-chemical characterization and biological activity

Bacillaene, a novel polyene antibiotic, was discovered and isolated from fermentation broths of a strain of Bacillus subtilis. The novel antibiotic has a nominal molecular weight of 580 and an empirical formula of C35H48O7. Bacillaene is active against a broad spectrum of bacteria in agar-plate diffusion assays. Studies in vitro indicate that the antibiotic inhibits prokaryotic protein synthesis but not eukaryotic protein synthesis. Cell survival studies performed with strains of Escherichia coli indicate that the antibiotic is a bacteriostatic agent.