Thèse (Ph. D.)--Université Laval, 2003. / Bibliogr.: f. 237-255. Publié aussi en version électronique.

Steroid sulfatase (STS) catalyzes the desulfation of biologically inactive sulfated steroids to yield biologically active desulfated steroids and is currently being examined as a target for therapeutic intervention for the treatment of breast and other steroid-dependent cancers. A series of 17-arylsulfonamides of 17-aminoestra-1,3,5(10)-trien-3-ol were prepared and evaluated as inhibitors of STS. Introducing n-alkyl groups into the 4´-position of the 17-benzenesulfonamide derivative resulted in an increase in potency with the n-butyl derivative exhibiting the best potency with an IC50 of 26 nM. A further increase in carbon units (to n-pentyl) resulted in a decrease in potency. Branching of the 4´-n-propyl group resulted in a decrease in potency while branching of the 4´-n-butyl group (to a tert-butyl group) resulted in a slight increase in potency (IC50 = 18 nM). Studies with 17-benzenesulfonamides substituted at the 3´- and 4´-positions with small electron donating and electron withdrawing groups revealed the 3´-bromo and 3´-trifluoromethyl derivatives to be excellent inhibitors with IC50’s of 30 and 23 nM respectively. The 17-2´-naphthalenesulfonamide was also an excellent inhibitor (IC50 = 20 nM) while the 17-4´-phenylbenzenesulfonamide derivative was the most potent inhibitor with an IC50 of 9 nM. Kinetic studies with 3´-bromo derivative revealed it to be a non-competitive inhibitor and so these types of inhibitors might be capable of binding at the active site and also at a secondary site outside the active site. The amide analogs of some of these compounds were found not to be as potent inhibitors as the sulfonamides. Introducing a nitro group or fluorine atom into the 4-position of the 17-arylsulfonamide inhibitors resulted in an increase in potency. Some of these compounds are the most potent reversible STS inhibitors ever reported with apparent Ki’s as low as 1 nM. 3-O-Sulfation of these compounds did not significantly alter their potency. It is not known if 3-O-sulfated derivatives were acting as inhibitors or reversible suicide inhibitors. Docking studies were performed on selected inhibitors to gain insight into how they might interact with STS. Selected 17-arylsulfonamide inhibitors were sent to the NCI (USA) for in vitro screening with a panel of 60 human tumor cell lines (NCI-60 panel). Almost all of the compounds exhibited GI50’s in the 1 to 10 M range with all 60 cell lines and so were only moderately potent in terms of their ability to inhibit the growth. None of the compounds stood out in terms of their ability to inhibit the growth of any breast cancer, prostate cancer or any other cancer cell line studied. The thiadiazolidinedione group was proposed as a sulfate mimic for obtaining STS inhibitors. A new approach to the synthesis of 3-aminoestrone was achieved as part of an attempt to prepare the thiadiazolidinedione target. 3-O-Sulfamoylation of one of the 17-arylsulfonamide inhibitors was attempted using a variety of reaction conditions but was unsucce

Steroid sulfatase (STS) is considered to be one of the key enzymes contributing to the development of breast cancer. It catalyzes the hydrolysis of inactive sulfated steroids such as estrone sulfate (ES) to inorganic sulfate active steroids such as estrone (E1), a precursor to estradiol (E2), a key stimulator for breast cancer development. Inhibitors of STS are currently being pursued in both academia and industry as potential drugs for treating breast cancer. A series of 4-substituted estrone and estradiol derivatives were examined as inhibitors of STS. Inhibition of STS with 4-FE1, an irreversible inhibitor of STS previously studied in the Taylor group, can be enhanced by introducing a hydrophobic benzyl group at the 17-positon of 4-FE1. As with 4-FE1, the inhibition was concentration and time-dependent. Only 14% of the activity could be recovered after extensive dialysis. Introducing substituents at the 2-position of 4-formyl estrogen derivatives resulted in loss of concentration and time-dependent inhibition and a considerable decrease in inhibitor affinity. Studies with estrogen derivatives substituted at the 4-position with groups other than a formyl revealed that a relatively good reversible inhibitor can be obtained simply by introducing an electron withdrawing group at this position. These types of inhibitors are non-competitive inhibitors suggesting an alternative steroid binding site. A series of estrone derivatives were examined as photoaffinity labels of STS. 4-azidoestrone suflate and 4-azidoestrone phosphate exhibited properties that are suitable for photoaffinity labeling studies with STS. These labels may be useful for ascertaining pathways of substrate entry into the STS active site. 16-diazoestrone phosphate was not a photoaffinity label of STS. 2- and 4-azido estrone and 16-diazoestrone all acted as photoaffinity labels of STS. These compounds may be useful for ascertaining pathways of product release from the STS active site.

Steroid sulfatase (STS) is considered to be one of the key enzymes contributing to the development of breast cancer. It catalyzes the hydrolysis of inactive sulfated steroids such as estrone sulfate (ES) to inorganic sulfate active steroids such as estrone (E1), a precursor to estradiol (E2), a key stimulator for breast cancer development. Inhibitors of STS are currently being pursued in both academia and industry as potential drugs for treating breast cancer. A series of 4-substituted estrone and estradiol derivatives were examined as inhibitors of STS. Inhibition of STS with 4-FE1, an irreversible inhibitor of STS previously studied in the Taylor group, can be enhanced by introducing a hydrophobic benzyl group at the 17-positon of 4-FE1. As with 4-FE1, the inhibition was concentration and time-dependent. Only 14% of the activity could be recovered after extensive dialysis. Introducing substituents at the 2-position of 4-formyl estrogen derivatives resulted in loss of concentration and time-dependent inhibition and a considerable decrease in inhibitor affinity. Studies with estrogen derivatives substituted at the 4-position with groups other than a formyl revealed that a relatively good reversible inhibitor can be obtained simply by introducing an electron withdrawing group at this position. These types of inhibitors are non-competitive inhibitors suggesting an alternative steroid binding site. A series of estrone derivatives were examined as photoaffinity labels of STS. 4-azidoestrone suflate and 4-azidoestrone phosphate exhibited properties that are suitable for photoaffinity labeling studies with STS. These labels may be useful for ascertaining pathways of substrate entry into the STS active site. 16-diazoestrone phosphate was not a photoaffinity label of STS. 2- and 4-azido estrone and 16-diazoestrone all acted as photoaffinity labels of STS. These compounds may be useful for ascertaining pathways of product release from the STS active site.

Carrageenans are sulfated polysaccharides found in the cell walls of red algae with 20 – 30 % of the dry weight coming from sulfate esters. The understanding of how heterotrophic bacteria desulfate and depolymerize carrageenan has become a rather arduous endeavor as there are 15 different classes of carrageenan distinguished by the degree of sulfation and the presence or absence of a unique galactose derivative, the 3,6-anhydro-D-galactose. The depolymerization of carrageenan requires the removal of the sulfate substituents, a role fulfilled by sulfatases, which hydrolyze sulfate esters playing a key role in the regulation of sulfation states that determine the function of sulfated biomolecules. Through structural, mechanistic, and sequence-based studies a highly conserved sulfate-binding motif has been identified among sulfatases; however, the molecular determinants for substrate specificity remain largely speculative. Additionally, the largest sulfatase family S1, requires a unique catalytic residue resulting from a post-translationally modified cysteine in order to be functional thus making them difficult to study in vitro. Using a strain of Pseudoalteromonas sp. PS47 isolated in the Boraston Lab I show that the depolymerization of carrageenan is dependent on the degree of sulfation and that recognition of the leaving group is the driving force behind S1 specificity. With little information on the recognition of sulfated biomolecules, the X-ray crystal structures of the three sulfatases from PS47; PsS1_19A, PsS1_19B, and PsS1_NC in complex with their biological substrates provides a deeper understanding of how carbohydrate specific sulfatases recognize their cognate substrate and how this recognition of the leaving group can be extended to other S1 sulfatase families. Furthermore, I show that an exo-acting glycoside hydrolase (PsGH42) requires desulfation of carrageenan oligosaccharides before it can hydrolyze the β-glycosidic linkage, a new specificity of family 42. This research demonstrates how carrageenan depolymerization is entirely dependent on the functionality and specificity of the sulfatases found within the carrageenan utilization locus. / Graduate / 2019-12-07

Steroid sulfatase (STS) catalyzes the desulfation of sulfated steroids such as estrone sulfate to the corresponding steroid such as estrone. Inhibitors of STS are believed to have potential for treating estrogen-dependent breast cancer. A new class of potential irreversible suicide inhibitors of STS, based on aryl sulfates bearing a monofluoromethyl or difluoromethyl group ortho to the sulfate group, was synthesized. Key to the success of these syntheses was the use of new sulfation methodology recently developed in the Taylor group. A new and efficient route to 4-formyl estrone, a time-dependent, irreversible STS inhibitor, is also reported. Several new classes of potential, reversible STS inhibitors were synthesized. These compounds are analogs of known STS substrates in which the sulfate group is replaced with an ???,??????-difluoromethylenesulfonamide group, a boronic acid group or a sulfinic acid group. We also report the synthesis of estrone sulfate analogs that bear a carboxylate moiety at the 17-position and a sulfate surrogate at the 3-position. It is anticipated that these compounds will inhibit STS by interacting with Arg98 which lies at the periphery of the active site. Key to the success of this synthesis was the use of the t-butyl group as a protecting group for the 2-position of estrone. Finally, our preliminary investigations into the synthesis of a new class of chiral electrophilic fluorinating agents are presented. These reagents are based on a chiral binaphthyl sulfonimide scaffold and are expected to be capable of performing enantioselective electrophilic fluorinations. Such reagents may be useful in synthesizing organofluorines of biological significance including STS inhibitors.

Thèse (M.Sc.)--Université Laval, 2009. / Bibliogr.: f. 84-93. Publié aussi en version électronique dans la Collection Mémoires et thèses électroniques.

Mucopolissacaridose tipo VI é uma doença lisossômica causada pela deficiência de arilsulfatase B. A incidência de MPS VI é muito baixa, geralmente menos de 1 caso para cada 1.000.000 recém-nascidos. Até o presente momento, 133 mutações e 13 polimorfismos foram identificados no gene da arilsulfatase B. Entretanto, a maioria dos alelos mutantes ou está presente somente em um indivíduo ou em poucos pacientes, o que demonstra a grande heterogeneidade alélica da MPS VI. No município de Monte Santo, Nordeste do Brasil, foram identificados treze pacientes com MPS VI. O objetivo deste trabalho foi identificar a(s) mutação(ões) presente(s) nos pacientes com MPS VI de Monte Santo/BA e os heterozigotos nas famílias; definir haplótipos utilizando SNPs para identificação de uma possível origem comum do alelo mutado nesta população e permitir aconselhamento genético eficiente, bem como orientações sobre a doença aos familiares com indivíduos afetados. Os 13 pacientes com MPS VI apresentavam a mutação p.H178L em homozigose e o mesmo haplótipo para os SNPs intragênicos. Nas viagens realizadas até o município durante este trabalho foram coletadas 236 amostras de sangue dos familiares, a mutação p.H178L foi detectada em 98 (20,8%) alelos, sendo 41,5% da amostra composta por indivíduos heterozigotos. Com base em dados atuais, a prevalência de MPS VI nesta região é estimada em 1:5.000 recémnascidos. As análises dos heredogramas indicam a presença de vários indivíduos com chance de 25% ou até 50% de serem heterozigotos. Monte Santo é uma região pequena e isolada e, os altos índices de endogamia fazem com que o alelo p.H178L permaneça frequente nesta região. Estes resultados, juntamente com a análise dos heredogramas, sugerem um efeito fundador, o que reforça a necessidade de um programa abrangente de genética comunitária para esta área, incluindo uma triagem neonatal e estudos com os membros das famílias para promover um aconselhamento genético. / Mucopolysaccharidosis type VI is a lysosomal disease caused by deficiency of arylsulfatase B. The incidence of MPS VI is very low, usually less than 1 case for every 1,000,000 newborns. To date, 133 mutations and 13 polymorphisms were identified in the arylsulfatase B gene. However, the majority of mutant alleles are present only in one individual or in a few patients, demonstrating the allelic heterogeneity of MPS VI. In the county of Monte Santo, northeast Brazil, thirteen patients with MPS VI were identified. The objective of this study was to characterize the mutation(s) present(s) in MPS VI patients from Monte Santo/BA and to detect heterozygous within the families. We also aimed to define haplotypes using SNPs to identify a possible common origin of the mutant allele in this population and allow efficient genetic counseling and assistance regarding the disease to families with affected individuals. The 13 MPS VI patients showed the p.H178L mutation in homozygosis and the same haplotype for intragenic SNPs. During field trips to Monte Santo along this study we collected 236 blood samples from family members, p.H178L mutation was detected in 98 (20.8%) alleles, and 41.5% of the samples were heterozygous individuals. Based on current data, the prevalence of MPS VI in this region is estimated at 1:5,000 newborns. Pedigree analysis indicates the presence of many individuals with a 50% and 25% chance of being heterozygous. Monte Santo is a small, isolated region and the high levels of inbreeding allows for p.H178L allele to remain common in this region. These results, together with the analysis of pedigrees suggest a founder effect, which reinforces the need for a comprehensive program of community genetics in this area, including a neonatal screening and studies of family members to promote a genetic counseling.

Mucopolissacaridose tipo VI é uma doença lisossômica causada pela deficiência de arilsulfatase B. A incidência de MPS VI é muito baixa, geralmente menos de 1 caso para cada 1.000.000 recém-nascidos. Até o presente momento, 133 mutações e 13 polimorfismos foram identificados no gene da arilsulfatase B. Entretanto, a maioria dos alelos mutantes ou está presente somente em um indivíduo ou em poucos pacientes, o que demonstra a grande heterogeneidade alélica da MPS VI. No município de Monte Santo, Nordeste do Brasil, foram identificados treze pacientes com MPS VI. O objetivo deste trabalho foi identificar a(s) mutação(ões) presente(s) nos pacientes com MPS VI de Monte Santo/BA e os heterozigotos nas famílias; definir haplótipos utilizando SNPs para identificação de uma possível origem comum do alelo mutado nesta população e permitir aconselhamento genético eficiente, bem como orientações sobre a doença aos familiares com indivíduos afetados. Os 13 pacientes com MPS VI apresentavam a mutação p.H178L em homozigose e o mesmo haplótipo para os SNPs intragênicos. Nas viagens realizadas até o município durante este trabalho foram coletadas 236 amostras de sangue dos familiares, a mutação p.H178L foi detectada em 98 (20,8%) alelos, sendo 41,5% da amostra composta por indivíduos heterozigotos. Com base em dados atuais, a prevalência de MPS VI nesta região é estimada em 1:5.000 recémnascidos. As análises dos heredogramas indicam a presença de vários indivíduos com chance de 25% ou até 50% de serem heterozigotos. Monte Santo é uma região pequena e isolada e, os altos índices de endogamia fazem com que o alelo p.H178L permaneça frequente nesta região. Estes resultados, juntamente com a análise dos heredogramas, sugerem um efeito fundador, o que reforça a necessidade de um programa abrangente de genética comunitária para esta área, incluindo uma triagem neonatal e estudos com os membros das famílias para promover um aconselhamento genético. / Mucopolysaccharidosis type VI is a lysosomal disease caused by deficiency of arylsulfatase B. The incidence of MPS VI is very low, usually less than 1 case for every 1,000,000 newborns. To date, 133 mutations and 13 polymorphisms were identified in the arylsulfatase B gene. However, the majority of mutant alleles are present only in one individual or in a few patients, demonstrating the allelic heterogeneity of MPS VI. In the county of Monte Santo, northeast Brazil, thirteen patients with MPS VI were identified. The objective of this study was to characterize the mutation(s) present(s) in MPS VI patients from Monte Santo/BA and to detect heterozygous within the families. We also aimed to define haplotypes using SNPs to identify a possible common origin of the mutant allele in this population and allow efficient genetic counseling and assistance regarding the disease to families with affected individuals. The 13 MPS VI patients showed the p.H178L mutation in homozygosis and the same haplotype for intragenic SNPs. During field trips to Monte Santo along this study we collected 236 blood samples from family members, p.H178L mutation was detected in 98 (20.8%) alleles, and 41.5% of the samples were heterozygous individuals. Based on current data, the prevalence of MPS VI in this region is estimated at 1:5,000 newborns. Pedigree analysis indicates the presence of many individuals with a 50% and 25% chance of being heterozygous. Monte Santo is a small, isolated region and the high levels of inbreeding allows for p.H178L allele to remain common in this region. These results, together with the analysis of pedigrees suggest a founder effect, which reinforces the need for a comprehensive program of community genetics in this area, including a neonatal screening and studies of family members to promote a genetic counseling.

Mucopolissacaridose tipo VI é uma doença lisossômica causada pela deficiência de arilsulfatase B. A incidência de MPS VI é muito baixa, geralmente menos de 1 caso para cada 1.000.000 recém-nascidos. Até o presente momento, 133 mutações e 13 polimorfismos foram identificados no gene da arilsulfatase B. Entretanto, a maioria dos alelos mutantes ou está presente somente em um indivíduo ou em poucos pacientes, o que demonstra a grande heterogeneidade alélica da MPS VI. No município de Monte Santo, Nordeste do Brasil, foram identificados treze pacientes com MPS VI. O objetivo deste trabalho foi identificar a(s) mutação(ões) presente(s) nos pacientes com MPS VI de Monte Santo/BA e os heterozigotos nas famílias; definir haplótipos utilizando SNPs para identificação de uma possível origem comum do alelo mutado nesta população e permitir aconselhamento genético eficiente, bem como orientações sobre a doença aos familiares com indivíduos afetados. Os 13 pacientes com MPS VI apresentavam a mutação p.H178L em homozigose e o mesmo haplótipo para os SNPs intragênicos. Nas viagens realizadas até o município durante este trabalho foram coletadas 236 amostras de sangue dos familiares, a mutação p.H178L foi detectada em 98 (20,8%) alelos, sendo 41,5% da amostra composta por indivíduos heterozigotos. Com base em dados atuais, a prevalência de MPS VI nesta região é estimada em 1:5.000 recémnascidos. As análises dos heredogramas indicam a presença de vários indivíduos com chance de 25% ou até 50% de serem heterozigotos. Monte Santo é uma região pequena e isolada e, os altos índices de endogamia fazem com que o alelo p.H178L permaneça frequente nesta região. Estes resultados, juntamente com a análise dos heredogramas, sugerem um efeito fundador, o que reforça a necessidade de um programa abrangente de genética comunitária para esta área, incluindo uma triagem neonatal e estudos com os membros das famílias para promover um aconselhamento genético. / Mucopolysaccharidosis type VI is a lysosomal disease caused by deficiency of arylsulfatase B. The incidence of MPS VI is very low, usually less than 1 case for every 1,000,000 newborns. To date, 133 mutations and 13 polymorphisms were identified in the arylsulfatase B gene. However, the majority of mutant alleles are present only in one individual or in a few patients, demonstrating the allelic heterogeneity of MPS VI. In the county of Monte Santo, northeast Brazil, thirteen patients with MPS VI were identified. The objective of this study was to characterize the mutation(s) present(s) in MPS VI patients from Monte Santo/BA and to detect heterozygous within the families. We also aimed to define haplotypes using SNPs to identify a possible common origin of the mutant allele in this population and allow efficient genetic counseling and assistance regarding the disease to families with affected individuals. The 13 MPS VI patients showed the p.H178L mutation in homozygosis and the same haplotype for intragenic SNPs. During field trips to Monte Santo along this study we collected 236 blood samples from family members, p.H178L mutation was detected in 98 (20.8%) alleles, and 41.5% of the samples were heterozygous individuals. Based on current data, the prevalence of MPS VI in this region is estimated at 1:5,000 newborns. Pedigree analysis indicates the presence of many individuals with a 50% and 25% chance of being heterozygous. Monte Santo is a small, isolated region and the high levels of inbreeding allows for p.H178L allele to remain common in this region. These results, together with the analysis of pedigrees suggest a founder effect, which reinforces the need for a comprehensive program of community genetics in this area, including a neonatal screening and studies of family members to promote a genetic counseling.