Novel plasma extraction procedure and development of a specific enzyme immunoassay of oxytocin: application to biological and clinical investigations of small-cell carcinoma of the lung

Paraneoplastic secretion of the lactation-inducing hormone oxytocin (OT) has been reported in about 30% of cases of small cell carcinoma of the lung (SCCL). In order to investigate the role of OT in the biology of SCCL tumours, a specific enzyme-immunoassay(EIA) for OT, which can be applied to both human plasma and culturemedium, has been developed. OT EIA is performed on 96-well microtiter plates coated with a rabbit polyclonal antibody (Ab) anti-OT (O4). This antibody does not exhibit any significant cross-reactivity either with vasopressin (VP) or with vasotocin (VT). The immunological reaction involving Ab anti-OT is a competition between the tracer (biotinylatedOT) and syntheticOT (standard curve) or OT present in biological samples. In order to limit interference induced by plasma proteins, plasma samples are titrated by a one-step centrifugation on centricon YM-3 (cut-oOE 3000 Da). After plasma filtration, 90.7 ± 5.1 (SD) % (n = 22) immunoreactive ( IR) OT is recovered. The sensitivity of OT EIA is 1 pmol/L, while intra- and inter-assay coefficients of variation (CV) are around 3.41% and 2.84%, respectively. In healthy volunteers, plasma IR OT is 7.28 ± 4.49 (SD) pmol/L (n = 32) with no gender diOEerence. As shown by the data both from plasma of SCCL patients and from supernatants and cell contents of SCCL cell lines, this EIA procedure offers a novel, reproducible, specific and sensitive method for the measurement of IR OT

Oxytocin synthesis and oxytocin receptor expression by cell lines of human small cell carcinoma of the lung stimulate tumor growth through autocrine/paracrine signaling

The objective of the present work was to investigate the existence of an oxytocin (OT)-mediated autocrine/paracrine signaling upon small cell carcinoma of the lung (SCCL) cell growth. In that view, OT receptor (OTR) expression, concomitant with OT synthesis and secretion, was evidenced on three different SCCL cell lines (DMS79, H146, and H345) and related to the vasopressin (VP) system. Specific OT, VP, OTR, Via VP receptor (V1aR), and V1b/V3 VP receptor (V1bR/V3R) transcripts were identified by reverse transcription-.PCR in all cell lines studied. Binding of I-125-(d(CH2)(5)(1),Tyr(Me)(2), Thr(4), Orn(3),Tyr(9)-NH2)-vasotocin (OVTA) was observed on all SCCL cell lines, with a K-d (dissociation constant) ranging from 0.025-0.089 nm, depending; on the cell line and the analytical method. Selectivity of I-125-OVTA binding was confirmed by displacement curves obtained with various OTR and VP receptor agonists and antagonists (OT, OVTA, L-371,257, VP, F180). Immunocytochemistry identified cellular OT and VP, and peptide secretion was measured in supernatants of SCCL cultures. [H-3]Thymidine incorporations, applied on H345 cells, demonstrated a dose-dependent mitogenic effect of exogenous OT (1 and 100 nM) that was abolished by the OTR antagonist OVTA. A decrease of proliferation was also observed with OVTA alone, showing a functional mitogenic effect of tumor-derived OT. Taken together, these observations demonstrate the existence of a functional OT-mediated autocrine/paracrine signaling actively implicated in growth and development of SCCL tumors. Furthermore, these findings point to the potential of OT antagonists for development as therapeutic agents for the treatment of SCCL

Antisteroid immune complexes and vascular thrombosis during steroid hormone therapy

To test an immunological hypothesis proposed to explain the pathogenesis of cerebrovascular thrombosis in steroid users, circulating immune complexes were assayed in the sera from 6 control subjects, 14 ever users of oral contraceptive having developed a neurological ischaemic accident, and 7 patients with the same clinical history during use of other sex steroid not containing ethinylestradiol. Beaumont's ammonium sulfate and polyethylene glycol precipitation methods, together with a specific method of isolation of circulating immune complexes using affinity chromatography on Protein A, were used. Radioactivity from labeled ethinylestradiol added to the sera before precipitation was monitored in the precipitates to detect anti-ethinylestradiol antibodies. There were no significant differences for these parameters in the three groups. However, protein content and 3H-EE activity in the precipitates were equally and dramatically reduced after affinity chromatography in the three groups. These latter results do not support the presence of antibodies against ethinyl-estradiol in steroid users with cerebrovascular thrombosis. Moreover, our data suggest a lack of specificity of Beaumont's method for the isolation of immune complexes containing anti-ethinylestradiol antibodies. © 1994.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Décoder la radiosensibilité des cancers infectés par le papillomavirus humain

The increased radiosensitivity of HPV positive tumors (compared to HPV negative ones) is widely known in clinical settings. However, the mechanisms by which this phenomenon occurs are still to be elucidated. A few hypotheses have been suggested regarding this differential radiosensitivity like, for example, an altered microtumoral environment or virus-host protein interactions. In this study, we focused on interactions between DNA repair proteins and virus oncoproteins. A large panel of 147 proteins implicated in DNA repair pathways was tested for potential interaction with HPV16 E6 and/or E7 oncoproteins using the GPCA method (Gaussia Princeps Complementation Assay). The proteins highlighted by the screening were validated by co-IP. The functional experiments, realized on HPV negative head and neck cancer (UPCI-SCC-111, FaDu, UPCI-SCC-40), vulva cancer (C33a) and control keratinocytes (HaCaT) stably transduced with E6 and/or E7, are in progress.Deciphering the radiosensitivity og HPV positive tumor

Décoder la radiosensibilité des cancers infectés par le papillomavirus humain

The increased radiosensitivity of HPV positive tumors (compared to HPV negative ones) is widely known in clinical settings. However, the mechanisms by which this phenomenon occurs are still to be elucidated. A few hypotheses have been suggested regarding this differential radiosensitivity like, for example, an altered microtumoral environment or virus-host protein interactions. In this study, we focused on interactions between DNA repair proteins and virus oncoproteins. A large panel of 147 proteins implicated in DNA repair pathways was tested for potential interaction with HPV16 E6 and/or E7 oncoproteins using the GPCA method (Gaussia Princeps Complementation Assay). The proteins highlighted by the screening were validated by co-IP. The functional experiments, realized on HPV negative head and neck cancer (UPCI-SCC-111, FaDu, UPCI-SCC-40), vulva cancer (C33a) and control keratinocytes (HaCaT) stably transduced with E6 and/or E7, are in progress.Deciphering the radiosensitivity og HPV positive tumor