Correlation between integration of high-risk HPV genome into human DNA detected by molecular combing and the severity of cervical lesions: first results of the EXPL-HPV-002 study.

OBJECTIVES: The aim of the EXPL-HPV-002 study is to evaluate the integration of 14 high-risk HPV as a biomarker of the severity and the progression of cervical lesions. Such a „triage biomarker“ would help to reduce the number of unnecessary colposcopies, to avoid over-treatment of lesions that spontaneously regress and to better target the lesions requiring treatment. DESIGN: EXPL-HPV-002 is a prospective, open-label, single arm, GCP study conducted at 2 clinical sites in the Czech Republic. SETTINGS: Investigations centers: Private Gynecology Center, Brno; Gynecological and Obstetrical Clinic, Brno; Genotyping central lab: NRL for Papillomaviruses and polyomaviruses, IHBT, Prague; Histology Central reading: Aeskulab Pathology, Prague; Molecular combing HPV test: Genomic Vision, Bagneux. METHODS: From June 2016 to May 2018, 688 patients aged 25-65, referred to colposcopy after an abnormal Pap-smear, were enrolled in the study. Among them 60% were found HPV high-risk. The study is divided in two phases: 1. a cross-sectional phase using data collected at first visit (colposcopy images ± histology, pap-smear for HPV genotyping and molecular combing) to study the association between HPV integration status versus colposcopy and histology grades; 2. a longitudinal phase using data collected in follow-up visits: cytology at 6, 18 and 30 months and colposcopy ± histology at 12, 24 and 36 months. A pap-smear collected at 12, 24 and 36 months allows to perform genotyping and molecular combing. HPV integration status is analyzed in comparison with the evolution of lesions, viral clearance and HPV genotype. HPV genotyping and molecular combing were performed on pap-smear samples in central laboratories. Histology data were reviewed by central reading. RESULTS: The transversal phase of the study is achieved and shows that the HPV integration into the human DNA, monitored by molecular combing, can significantly differentiate normal subjects from women with cervical lesions or cancer. CONCLUSION: HPV integration into the host genome, monitored by Genomic Visions technology, is a reliable diagnostic biomarker that will greatly help clinicians to improve their medical decision tree.

Purification by affinity chromatography and some properties of microsomal galactosyltransferase from pig thyroid.

Membrane-bound 4-beta-galactosyltransferase (lactose synthase; UDP galactose: D-glucose 4-beta-galactosyltransferase, EC 2.4.1.22) was purified 1500-fold to near homogeneity from pig thyroid microsomes with about 30% yield. The purified enzyme behaved as a lipophilic protein, rapidly losing activity and aggregating if not supplemented with either Triton X-100 or serum albumin (both of these were equally effective for long-term stabilization). The enzyme preparation showed an absolute requirement for Mn2+, which could not be replaced by other cations. Catalytic properties were very similar to those reported for soluble forms of the enzyme in biological fluids. The purified galactosyltransferase showed a major protein band of approx. 74,000 daltons on sodium dodecyl sulfate gel electrophoresis. On gel filtration, enzyme activity was eluted at approx. 70,000 daltons. It is concluded that the membrane-bound thyroid galactosyltransferase is a monomeric protein significantly larger than the soluble forms of this enzyme described earlier; but it resembles recently reported galactosyltransferases from sheep mammary Golgi membranes and liver microsomes.

Cell-free labeling in thyroid rough microsomes of lipid-linked and protein-linked oligosaccharides. I. Mannosylated units.

In order to evaluate the possibility in a pig thyroid rough microsomal system of a transfer of pre-assembled sugar cores from sugar-lipids to protein, we have examined after incubation with GDP-[14C]Man the compounds bearing labeled saccharides and have determined some properties of their released saccharide moieties. The [14C]Man material specifically soluble in CHCl3/CH3OH/H2O, 10:10:3, behaved on DEAE-cellulose and when treated with hot alkali and alkaline phosphatase as a lipid pyrophosphate (sometimes accompanied by some dolichol-P-[14C]Man). Its saccharide moiety, released by mild acid, exhibited properties (molecular size, sensitivity to alpha-mannosidase, affinity for concanavalin A and charge modification introduced by a strong reductive alkaline treatment) pointing to a polymannosylated N,N'-diacetylchitobiose containing an average of nine monosaccharide units (from six to twelve). The [14C]mannosylated glycoproteins have represented all the polymeric label remaining after lipid extraction. From the susceptibility of their pronase glycopeptides to a differential reductive alkaline hydrolysis, it was concluded that their label belonged mainly to N-glycosidically linked units. Released saccharides exhibited the same properties as those from lipids, a result substantiating the possibility raised from previous studies of a transfer of pre-assembled moieties.

Evidence for mannolipids as intermediates in mannose transfer to thyroid rough microsomal glycoproteins.

Thyroid rough microsomes catalyzed the transfer of mannose from GDP-mannose to endogeneous glycoprotein(s) and to glycolipids comprising a recently described dolichol phosphomannose extractable with usual organic solvents and a material tentatively identified as an oligosaccharide lipid. The labeling of the two lipids was consistent with a role in mannose transfer to glycoprotein(s). When partially purified dolichol phospho[14C] mannose was incubated with rough microsomes, a part of the label appeared in the second lipid, suggesting a role as intermediate, and less rapidly in glycoprotein(s). Sodium dodecyl sulfate/polyacrylamide gel electrophoresis did not allow to ascertain whether or not the glycoproteins receiving label from these sugar lipids comprised thyroglobulin precursors.

Transfer of glucose in the biosynthesis of thyroid glycoproteins. I. Inhibition of glucose transfer to oligosaccharide lipids by GDP-mannose.

Thyroid rough microsomes catalyzed the synthesis of glucose-containing oligosaccharide lipids which were compared to those extracted from labeled thyroid cells and were found to be largely similar. Glucose transfer to these oligosaccharide lipids in the microsomal system was shown to be markedly depressed by an addition of GDPmannose. This sugar nucleotide, already at 1 microM, blocked dolichol-P-glucose synthesis, thus restraining further glucosylation of oligosaccharide lipids. Using this concentration of radioactive GDPmannose in the incubation medium lead to the detection of three glucose containing mannose-labeled oligosaccharide lipids. Double labeling experiments suggested a precursor-product relationship between them. Previously labeled oligosaccharide lipids, containing glucose or not were compared in their efficiency to act as donors of their oligosaccharide chain to an exogenous synthetic Asn-X-Thr containing peptide. It was found that the presence of glucose did not significantly influence the transfer. Free glucose was released during the reaction when using the glucose-labeled oligosaccharide lipid.

Phosphatidylcholine requirement for the N-glycosylation of synthetic peptides by detergent-solubilized oligosaccharyltransferase.

The ability of dolichyl-P-P-oligosaccharide:peptide oligosaccharyltransferase to use exogenous substrates (a previously labeled oligosaccharide lipid and an Asn-X-Thr containing heptapeptide) is shown to require phospholipid. The enzyme was extracted from porcine thyroid rough microsomes using NaCl-Nonidet P-40. When measured at low concentration, in a neutral detergent-containing medium, it undergoes a rapid loss of activity, which renders impossible quantitative estimates in the range of 0-50 micrograms microsomal protein/50 microliters assay. We observed that inactivation could be prevented by supplementing the assay with a previously heat-treated suspension of microsomes in neutral detergent, or with the corresponding extract. Further investigation revealed that phospholipids are responsible for this enzyme stabilization, since phospholipase A2 and phospholipase C treatments were both able to abolish this effect. When individual phospholipids were compared for their protective efficiency, egg yolk phosphatidylcholine was found to be by far the most efficient. Phosphatidylglycerol, phosphatidylinositol and phosphatidylserine were only slightly effective, while phosphatidylethanolamine and lysophosphatidylcholine had no effect at all. Of those tested, partly unsaturated phosphatidylcholines with 16-18 carbon atom acyl chains were the most active, at an optimal concentration of 1-2 mM. Under these conditions a Km of 15 microM was measured for the acceptor, a synthetic ribonuclease heptapeptide, and a Km of 0.55 microM for the donor, dolichyl-P-P-GlcNAc2-Man9-Glc2-3. These findings were confirmed by subjecting a sodium deoxycholate extract to depletion of endogenous lipids by gel filtration. Enzyme activity was totally abolished and then restored (up to now only partially) by addition of phosphatidylcholine.

Responsiveness of glycosyltransferases to thyrotropin in a serum-free culture of porcine thyroid cells.

Administration of thyrotropin to porcine thyroid follicles, obtained in a serum-free chemically defined medium, provoked marked increases in the activities of several glycosyltransferases involved in protein N-glycosylation. The coincidence of these effects with a previously demonstrated enhancement of thyroglobulin production renders a relationship between these events likely. The most important stimulation was for peptide oligosaccharyltransferase (3-fold). Among the enzymes involved in the synthesis of the lipid oligosaccharide donor, Dol-P glycosyl- and mannosyltransferases were increased 1.5-fold, and Dol-P N-acetylglucosaminylphosphotransferase only 1.15-fold. As regards terminal glycosyltransferases, asialofetuin sialyltransferase was increased 2-fold and ovomucoid galactosyltransferase only 1.2-fold. There was a continuous release of the latter two enzymes into the culture medium.

Thyrotropin increases 5'-nucleotidase activity in primary cultures of porcine thyroid cells.

Thyrotropin given to support-anchored cultures of porcine thyroid cells, either in a serum-containing or in a serum-free system, produced an increase of about 50% in the total activity of 5'-nucleotidase. In the serum-free culture, in which TSH was administered to well-reformed follicles, this increase in 5'-nucleotidase activity concerns both the ecto-enzymic and intracellular forms of the enzyme and it coincides with the period of several days during which several glycosyltransferase activities are elevated and thyroglobulin production increased. Taken together, and in view of a recent in vitro study (Brandan and Fleisher, 1982) documenting the fate of uridine diphosphate in Golgi vesicles, these results suggest that there might be a functional correlation between the stimulation of 5'-nucleotidase and an increased production of nucleoside mono- and diphosphates when the activity of a number of glycosyltransferases is increased.

Effect of thyrotropin on glycosaminoglycans synthesized by primocultured thyroid cells.

The synthesis of glycosaminoglycans (GAGs) was investigated in porcine thyroid cells under the influence or not of thyrotropin. After labelling with [3H] glucosamine and [35S] SO4(2-), enriched GAG-fractions prepared from culture media, cells, and eventually substrate adhering materials, were analyzed by cellulose acetate electrophoresis combined with specific degradations. They comprised heparan sulfate and hyaluronic acid together with an unknown sulfated component labile to endo-beta-galactosidase. Whereas global labellings of newly made GAGs were not significantly modified by thyrotropin, we reproducibly observed with the hormone a substantial increase in the proportion of hyaluronic acid [3H] label and, when cells organized into follicles, of the proportion of cell-associated [3H] GAGs. This system thus offers an interesting model to study how the responsiveness to an hormone and the reorganization that follows might implicate specific glycoconjugates.

Inhibition of N-linked oligosaccharide processing does not prevent the secretion of thyroglobulin. A study with swainsonine and deoxynojirimycin.

The effects of two drugs, swainsonine (SW) and deoxynojirimycin (dNM), on synthesis and export of thyroglobulin were studied in folliculized porcine thyroid cells cultured in a serum-free medium. These drugs were expected to alter N-linked glycans in thyroglobulin. Newly synthesized thyroglobulin labeled with [2-3H]mannose or [4,5-3H]leucine was obtained by immunoprecipitation from the follicular contents, culture media and cell extracts; the first two compartments, containing secreted thyroglobulin, were sometimes analyzed together. Leucine incorporation was not inhibited by SW and only slightly by dNM. In contrast dNM strongly decreased mannose incorporation (by up to 50-75% at 1-3 mM). However after 16-h mannose labelings, SW and/or dNM at 2.5 microM and 3 mM respectively did not significantly modify the relative proportions of radioactive thyroglobulin in the above-mentioned compartments. Pronase glycopeptides prepared from these thyroglobulins were examined with respect to behaviour on concanavalin-A-Sepharose and position on Bio-Gel P-4. Oligosaccharides released by endoglucosaminidase H and with high affinity for the lectin, i.e. high-mannose and certain hybrids, were further characterized by various exoglycosidase treatments. Thyroglobulin from control cells displayed complex and high-mannose glycans comparable in size and proportion to those attributed to tissue-extracted porcine thyroglobulin. After treatment with SW (an inhibitor of alpha-mannosidase II), complex glycans were almost totally replaced by sialylated hybrid glycans. In contrast to this nearly total suppression, dNM (an inhibitor of the trimming glucosidases) caused only a 30% decrease in labeling of complex units and an about 50% increase in high-mannose glycans, covered to some degree by glucose. Finally a [3H]leucine pulse-chase study was performed on thyroglobulin secretion in the absence or presence of both SW and dNM. Though a slowdown was detectable in the first few hours, this study revealed no change in the long-term export of thyroglobulin.