Modulation of fibroblast-induced clot retraction by calcium channel blocking drugs and the monoclonal antibody ALB6

Suspensions of living human fibroblast induce fibrin clot retractile activity (FCR). The efficiency is dependent on the growth phase; it is maximal during active growth and reduced in post-confluent cultures. In contrast human osteosarcoma cells constantly exhibit very low FCR efficiency. Two different calcium channel-blocking drugs Diltiazem and Verapamil inhibit, depending on the concentrations employed, FCR, and spreading within the clots of the normal cells. Intermediate FCR levels are associated with intermediate degrees of spreading. A similar dose dependent inhibition is also obtained by treating the normal cells with the calmodulin inhibitor trifluoperazine (TFP). On the other hand, treatment of the normal cells with the monoclonal antibody ALB6 which is directed at the human leukocyte differentiation antigen CD9 (p24) causes a significant increase in the FCR efficiency in post-confluent normal cells, but it has no effect on the Te85 osteosarcoma cells. Moreover ALB6 IgG reverses the FCR inhibitory effect of the calcium-channel blocking drugs but not that of TFP. This means that the ALB6 IgG target on the cellular membrane is probably the same as that of the two drugs and that ALB6 IgG is active in the regulation of the calcium flux which controls fibrin clot retractile activity of normal human fibroblasts.

The platelet protein phosphorylation induced by a monoclonal antibody against human platelets (TP82)

In human platelets, a monoclonal anti-human platelet antibody (TP82) induced platelet aggregation and release of granules (i.e., serotonin, platelet factor 4, N-acetyl-beta-D-glucosaminidase). The release reaction occurred even in the absence of aggregation and was preceded by not only the protein phosphorylation, but the transient formation of endogenous diacylglycerol (DG). These results suggest that polyphosphoinositide breakdown plays an essential role in antibody-induced release of platelet granules.

S-antigen is coded by [poly A+] mRNA from bovine retina

Total RNA, [poly (A)-] mRNA and [poly (A)+] mRNA purified from bovine retina were translated in vitro in a rabbit reticulocyte lysate system. Immunoprecipitation of translation products with antibodies to the retinal S-antigen (a photoreceptor specific protein involved in autoimmune retinal disease) revealed this protein as a 50,000 daltons band comigrating with purified S-antigen. This indicates that the S-antigen is synthesized in the retina and is not a maturation or degradation product of a larger protein. Its messenger RNA is the polyadenylated RNA, as for some other proteins expressed in nervous tissue.

Inhibition of experimental autoimmune uveoretinitis in rats by S-antigen-specific monoclonal antibodies

Mouse monoclonal antibodies (mAb), of either IgG2a or IgG2b isotypes, specific for the retinal S-autoantigen (S-Ag) or a pool of rat anti-S-Ag sera prevented experimental autoimmune uveoretinitis in Lewis rats when injected i.p. at the time of immunization. Control mAb of the same isotypes, irrelevant to S-Ag, had no inhibitory effect. The humoral response to S-Ag, as studied by enzyme-linked immunosorbent assay using a mouse mAb specific for rat kappa chain, was moderately but significantly reduced in suppressed animals. The rapid disappearance of the injected mAb from rat sera, as measured using a rat mAb specific for mouse kappa chain, could be explained by its complexing with either autologous antigen released from the retina at the site of inflammation, or anti-idiotypic antibodies.

Expression in brain of a messenger RNA encoding a novel neuropeptide homologous to calcitonin gene-related peptide

As a consequence of alternative RNA processing events, a single rat gene can generate messenger RNA's (mRNA's) encoding either calcitonin or a neuropeptide referred to as alpha-type calcitonin gene-related peptide (alpha-CGRP). An mRNA product of a related gene has been identified in rat brain and thyroid encoding the protein precursor of a peptide differing from alpha-CGRP by only a single amino acid. The RNA encoding this peptide, which is referred to as beta-CGRP, appears to be the only mature transcript of the beta-CGRP gene. Hybridization histochemistry reveals a similar distribution of alpha- and beta-CGRP mRNA's, but their relative levels of expression vary in different cranial nerve nuclei. Thus beta-CGRP is a new member of a family of related genes with potential functions in regulating the transduction of sensory and motor information.

Anti-retinal auto-antibodies in Vogt-Koyanagi-Harada syndrome, Behcet's disease, and sympathetic ophthalmia

Sera of patients diagnosed as having the active Vogt-Koyanagi-Harada (VKH) syndrome, Behcet's syndrome or sympathetic ophthalmia as well as normal controls were evaluated by ELISA and by staining of normal human retinal tissue using the avidin-biotin-peroxidase complex (ABC) technique for anti-retinal antibodies. No anti-retinal S-antigen antibodies were detected by ELISA. However, autoimmune antibodies were found against the outer segments of photoreceptors and Müller cells in patients with the VKH syndrome, with lower titers in some patients with Behcet's syndrome, and in a few patients with sympathetic ophthalmia. These results suggested anti-retinal antibodies were present and that retinal autoimmunity may play a role in pathogenesis in varieties of posterior uveitis. In addition, the indirect immunoperoxidase staining technique may facilitate the diagnosis of VKH in uncertain cases.

Heterogeneity of chicken photoreceptors as defined by hybridoma supernatants. An immunocytochemical study

Immune cells producing antibodies to chicken photoreceptor membranes were fused with myeloma cells and supernatants of the resulting hybridoma cells were used to test various types of photoreceptor cells in the chicken retina by means of immunocytochemistry. A polyclonal antibody raised against the protein component of bovine rhodopsin was also used. Outer segments of various photoreceptor cells were labelled by the following antibodies: rods were positive with the anti-rhodopsin antibody, both members of the double cones were stained by supernatant A1, while one type of single cones (designated as type A) was specifically labelled by supernatants A5, B3 and D6. The other type of single cones (type B) reacted with anti-rhodopsin and supernatant A1. The results indicate that there are distinct differences in the molecular structure of various photoreceptor outer segments.

Photoreceptor cell-specific localization of S-antigen in retina

Retinal S-antigen has been found to be localized in a specific photoreceptor cell population of squirrel (Tamias striatus) and rhesus monkey retina. In these cone-rich retinas S-antigen seems only to be present in the rods. Differential immunofluorescent staining of the photoreceptor cells was accomplished by using monospecific rabbit-anti bovine S-antigen antiserum, which exhibits very limited species specificity. In view of its co-localization with rhodopsin in rods and considering data from literature, we suggest that S-antigen is a major component of the phototransduction system in these cells.

Retinal S antigen identified as the 48K protein regulating light-dependent phosphodiesterase in rods

Retinal S antigen chromatographically purified from whole retina, induces experimental autoimmune uveoretinitis in laboratory animals. The 48K protein, a soluble protein found in rod outer segments, is purified through its specific binding to photoexcited rhodopsin and is involved in the quenching of light-induced guanosine 3',5'-monophosphate-phosphodiesterase activity. Biochemical, immunological, functional, and pathological tests showed that retinal S antigen and the 48K protein are identical.

Light induced shift and binding of S-antigen in retinal rods

S-antigen has been quantitated in bovine and rat retina by electroimmunoassay. The molar ratios S-antigen to rhodops in in photoreceptor cells were close to 1:1. Immunofluorescence studies show that light induces a shift of S-antigen towards the rod outer segments where it concentrates. Assays indicate that S-antigen becomes largely water insoluble but detergent soluble under these conditions. On basis of previous ultrastructural and present results, this has been interpreted as a light induced binding of S-antigen to the rod outer segment membranes. The data support evidence from literature that S-antigen interacts with (rhod) ops in and we conclude that S-antigen plays a major role in the phototransduction process.

Possible involvement of two proteins (phosphoprotein and CD9 (p24)) in regulation of platelet calcium fluxes

The monoclonal antibody ALB6 directed against the leukocyte differentiation antigen CD9 (p24) increases the calcium incorporation into isolated platelet membrane vesicles enriched in internal membranes. The similarities of the effects of both the monoclonal antibody and the catalytic subunit of the cAMP-dependent protein kinase (C, subunit), which phosphorylates a protein of an apparent molecular mass of 23 kDa, led us to investigate the relationship between CD9 (p24) and the 23-kDa phosphoprotein (p23). ALB6IgG does not inhibit the C.subunit-induced phosphorylation of p23 and the immunoadsorption by ALB6IgG of p24 associated to membrane vesicles does not alter the phosphorylation pattern. Thus, proteins of similar molecular mass appear to be involved in calcium fluxes: one is recognized by the ALB6 antibody while the other can be phosphorylated by the C-subunit.

A new set of monoclonal antibodies against acute lymphoblastic leukemia

Six monoclonal antibodies produced by immunization of Balb/c mice with common acute lymphoblastic leukemia (cALL) cells were tested against various types of normal and malignant tissues. ALB1 and ALB2 are directed to the cALL antigen (CALLA gp100); ALB6 recognizes a determinant of p24; ALB7, ALB8 and ALB9 have a pattern of reactivity similar to Ba1. None of these antibodies specifically identify cALL but they should be useful tools for diagnosis or depletion of bone marrow in autologous therapy in transplantation. In addition, the example of ALB6 which acts as a platelet aggregating agent, suggests that the study of other cell systems expressing the antigens associated with cALL may shed light on the function of these antigens and subsequently on the physiopathology of the leukemic cells.

No evidence for structural or functional identity between p24/CD9 and p21/ras

Experiments were undertaken to test the hypothesis that the p24/CD9 cell surface molecule (originally detected on acute lymphoblastic leukemia cells) and the p21 protein encoded by the ras gene family are related. Immunoprecipitation and guanine nucleotide binding assays conducted with BA-2 and anti-p21/ras monoclonal antibodies showed no evidence that p24/CD9 is structurally or functionally related to p21/ras.

A monoclonal antibody GR2110 reactive with a P24 antigen present in a subgroup of acute lymphoid leukemias

A monoclonal antibody IgG1K against a P24 antigen has been obtained. This antigen is present on a subgroup of non-T-ALL and platelets. GR2110 monoclonal antibody was produced by immunizing with a CALL (CALLA+, Ia+, IgS-, E-, T3-) This P24 antigen is absent in normal T-lymphocytes, monocytes, mitogen-activated T-cells; weakly expressed on B-cells and granulocytes and negative with several cell lines, except with KM3. GR2110 monoclonal antibody was tested with chronic and acute human leukemias. It was positive only with some CALL, NULL ALL, B-ALL and negative with B-CLL, T-CLL, T-cell lymphoma, Hairy cell leukemia, AML, T-ALL. The immunoprecipitation of 125I-labeled cell membrane with the monoclonal antibody and SDS-PAGE analysis revealed a 24 kD molecular weight polypeptide. The comparison of GR2110 and FMC 8 in capping experiments and cellular reaction patterns, showed that both antibodies react with the same molecule but probably with different epitopes.

Characteristics of platelet aggregation induced by the monoclonal antibody ALB6 (acute lymphoblastic leukemia antigen p 24). Inhibition of aggregation by ALB6Fab

The leukemia-associated cell surface antigen p 24 is found on normal platelets as well as on Bernard Soulier syndrome and thrombasthenia type I platelets. ALB6 IgG (a monoclonal antibody against p 24) induces the aggregation of platelets from normal donors but not from thrombasthenia. In contrast, ALB6 Fab inhibits platelet aggregation induced by collagen, ADP, thrombin, ionophore A 23187 and ALB6 IgG. The results suggest that ALB6 interferes with a mechanism common to all aggregation pathways; the possible mechanisms are discussed.

Isolation and characterization of Pseudomonas aeruginosa PAO mutant that produces altered elastase

Triple-negative breast cancer (TNBC) is cancer that tested as negative for estrogen receptors (ER), progesterone receptors (PR), and excess human epidermal growth factor receptor 2 (HER2) protein which accounts for 15%–20% of all breast cancer cases. TNBC is considered to be a poorer prognosis than other types of breast cancer, mainly because it involves more aggressive phenotypes that are similar to stem cell–like cancer cells (cancer stem cell, CSC). Thus, targeted treatment of TNBC remains a major challenge in clinical practice. This review article surveys the latest evidence concerning the role of genomic alteration in current TNBC treatment responses, current clinical trials and potential targeting sites, CSC and drug resistance, and potential strategies targeting CSCs in TNBC. Furthermore, the role of insulin-like growth factor 1 receptor (IGF-1R) and nicotinic acetylcholine receptors (nAChR) in stemness expression, chemoresistance, and metastasis in TNBC and their relevance to potential treatments are also discussed and highlighted.

[On the physiological roles of fibrinogen and fibrin]

Cancer is now viewed as a stem cell disease. There is still no consensus on the metabolic characteristics of cancer stem cells, with several studies indicating that they are mainly glycolytic and others pointing instead to mitochondrial metabolism as their principal source of energy. Cancer stem cells also seem to adapt their metabolism to microenvironmental changes by conveniently shifting energy production from one pathway to another, or by acquiring intermediate metabolic phenotypes. Determining the role of cancer stem cell metabolism in carcinogenesis has become a major focus in cancer research, and substantial efforts are conducted towards discovering clinical targets.