HSP27 as a mediator of confluence-dependent resistance to cell death induced by anticancer drugs.

Resistance of colorectal cancer cells to chemotherapeutic drugs increases as cells reach confluence. Here we show that the small stress protein HSP27, which has been described to block necrotic and apoptotic cell death, accumulates in confluent human colorectal cancer cell lines HT-29 and Caco2. Cell confluence also induces HSP27 phosphorylation and changes in its intracellular distribution.

[Prevalence of monosymptomatic celiac disease in patients with iron deficiency anemia].

A prospective study of the prevalence of monosymptomatic celiac disease presented as ferropenic anemia in patients admitted for study such complication of was carried out. All the patients were evaluated by gastroscopy and biopsy of the distal duodenal segment, regardless of endoscopic appearance. Patients presenting an endoscopic lesion clearly suggestive as the origin of the chronic bleeding were excluded from the study.

Hybrid nucleoprotein particles containing a subset of male and female histone variants form during male pronucleus formation in sea urchins.

To determine the changes in chromatin organization during male pronucleus remodeling, we have compared the composition of nucleoprotein particles (NP-ps) resulting from digestion with endogenous nuclease (ENase) and with micrococcal nuclease (MNase). Whole nuclei were isolated from sea urchin gametes and zygotes containing partially decondensed (15 min postinsemination, p.i.

Inconstant association between 27-kDa heat-shock protein (Hsp27) content and doxorubicin resistance in human colon cancer cells. The doxorubicin-protecting effect of Hsp27.

To investigate the role of the small 27-kDa heat-shock protein (Hsp27) in the intrinsic resistance of colon cancer cells to doxorubicin, we modified Hsp27 expression either genetically by transfection or pharmacologically by cisplatin treatment. HT-29 cells were transfected with a full-length Hsp27 construct in the sense or antisense orientation. We found a good correlation between cell survival after doxorubicin treatment and Hsp27 content.

Back-mutation of the V-Ets to the C-Ets carboxy-terminal amino acids in the P135gag-myb-ets results in chicken neuroretina cells transformation and loss of basic fibroblast growth factor responsiveness.

The v-Myb, v-Ets containing E26 retrovirus (called in this work E26ABC) induces the proliferation of chicken neuroretina (CNR) cells in minimal medium, strongly stimulated by basic Fibroblast Growth Factor (bFGF) which confers on them the ability to form colonies in soft agar. V-Ets differs from its cellular counterpart c-Ets-1 by two point mutations and by the replacement of the 13 last C-terminal amino acids by 16 unrelated residues as a consequence of DNA segment inversion in the viral sequence. It has been documented that this different C-terminal sequence influences DNA binding activity and specificity.

Kinetics of an autocatalytic zymogen reaction in the presence of an inhibitor coupled to a monitoring reaction.

A global kinetic analysis of a model consisting of an autocatalytic zymogen-activation process, in which an irreversible inhibitor competes with the zymogen for the active site of the proteinase, and a monitoring coupled reaction, in which the enzyme acts upon one of its substrates, is presented. This analysis is based on the progress curves of any of the two products released in the monitoring reaction. The general solution is applied to an important particular case in which rapid equilibrium conditions prevail.

Circumvention of confluence-dependent resistance in a human multi-drug-resistant colon-cancer cell line.

Colorectal adenocarcinomas are inherently resistant to anthracyclines and other topoisomerase-II inhibitors. Resistance to doxorubicin of colon cancer cells (Caco2) depends on 2 main mechanisms. The first is typical multi-drug resistance, characterized by the mdr1 gene and its product the P170 membrane glycoprotein.

Deleterious effect of serum proteins on the amphotericin B-induced potentiation of cisplatin in human colon cancer cells.

Inherent resistance of colon cancer cells to cis-diamminedichloroplatinum(II) (CDDP) is partly attributed to reduced drug penetration through plasma membrane. Amphotericin B (AmB), a polyene antifungal antibiotic, has been shown to increase CDDP penetration and cytotoxicity on several non-digestive cancer cell lines. We demonstrated here that AmB dramatically increases the penetration of CDDP, and to a lesser extent that of carboplatin (Carbo-P) and oxaloplatin (L-OHP), in the primary resistant HT 29 human colon cancer cells when drug incubation is performed in serum-free medium.

Fos expression induces growth arrest in tumorigenic neuroretina cells.

E26-infected chicken neuroretina (CNR) cells expressing P135gag-myb-ets are non-transformed and growth can be stimulated by basic fibroblast growth factor (bFGF). In contrast, MHE226-infected CNR cells, which express p61/63myc in addition to the P135gag-myb-ets of E26, are transformed, tumorigenic cells and are growth inhibited by bFGF. We looked for differences in both cells types which could help to understand the molecular basis of the bFGF response.

v-erbA cooperates with bFGF in neuroretina cell transformation.

We have studied the transforming ability of the oncogenes erbA and/or erbB in chicken neuroretina (CNR) cells and the effect of basic fibroblast growth factor (bFGF) on the transformed phenotype. The erbA oncogene alone was only transforming in the presence of bFGF. In contrast, cells expressing erbB as well as erbA + erbB were transformed in a bFGF-independent manner and were unresponsive to the growth factor.

Transcriptional regulation of vascular endothelial growth factor gene expression in ovarian bovine granulosa cells.

The expression of vascular endothelial growth factor (VEGF) in cultured bovine granulosa cells has been studied. As shown by northern blot analysis, granulosa cells express the VEGF gene. Analysis of the VEGF transcripts by the polymerase chain reaction technique shows that granulosa cells express predominantly the smallest VEGF coding forms (VEGF121 and VEGF164).

Kinetic resistance to anticancer agents.

Adherent epithelial cancer cells, such as colon cancer cells, are much more resistant to anthracyclines and to many other major anticancer agents when the cell population reaches confluence. Our purpose is to analyze the mechanisms of this confluence dependent resistance (CDR) that is probably the major cause of the natural resistance of solid tumors to chemotherapy. Some drugs (anthracyclines, etoposide and vincristine) but not others (cisplatin, melphalan and 5-fluorouracil) accumulate less in confluent than in nonconfluent cells.

Protein truncation is not required for c-myb proto-oncogene activity in neuroretina cells.

The v-myb oncogene of avian myeloblastosis virus (AMV) differs from its normal cellular counterpart by a truncation at both its amino and carboxyl termini and by a substitution of 11 amino acid residues. We had previously shown that v-myb-containing AMV, in the presence of basic fibroblast growth factor, transformed chicken neuroretina (CNR) cells. To understand the mechanism of c-myb activation, we have tested whether avian retroviruses that express the full-length c-Myb are also active on CNR cells.

X-ray studies on phospholipid bilayers. XII. Interactions of pentachlorophenol with myelin.

Pentachlorophenol (PCP) is a widely used pesticide, particularly for the preservation of wood. Given its high toxicity and resistance to degradation it has become a dangerous environmental pollulant. Due to its high lipophilicity, PCP is able to partition into the lipid bilayer of cell membranes disrupting several vital functions.

Definition of functional domains in P135gag-myb-ets and p48v-myb proteins required to maintain the response of neuroretina cells to basic fibroblast growth factor.

The v-myb- and v-ets-containing E26 retrovirus induces the proliferation of chicken neuroretina (CNR) cells in minimal medium. Proliferation of E26 CNR cells is strongly stimulated by basic fibroblast growth factor (bFGF). The v-myb-containing avian myeloblastosis virus also induces the proliferation of infected CNR cells stimulated by bFGF.

[Prognostic markers in transitional carcinoma of the bladder].

Due to the diversity of the biologic behaviour of the low-grade and low-stage superficial bladder carcinomas, particularly those that present a high recurrence rate, most of the research has been oriented towards finding prognostic markers of recurrence and future invasion of the tumor. Among these markers there are two that have demonstrated their usefulness: the study of the contents of the cellular DNA by flow cytometry and the study of blood group antigens. The latter are carbohydrate structures that form a complex, genetically-regulated signal code which intervenes in the cellular growth and maturation processes.

Peripheral pigmented neuroectodermal tumor of infancy with rhabdomyoblastic differentiation.

A case of a 6-month-old male with a peripheral pigmented neuroectodermal tumor of the right popliteal region is presented. The tumor disclosed neuroblast-like and melanoblast-like cells and on electron microscopy tumor cells with rhabdomyoblastic differentiation. The patient is well and alive and without evidence of disease three years after the initial diagnosis.

Value of the S100 protein in the study of nevus and ocular melanomas.

Ten cases of melanoma and 5 ocular nevus were studied with the peroxidase-antiperoxidase method with S100 protein. All the cases showed positivity for this protein, this is why we can advise its use in the diagnosis of these entities.

Immunohistochemical study of embryonic rhabdomyosarcomas.

11 orbital embryonic rhabdomyosarcomas were studied immunohistochemically from patients under 4 years of age. One out of these cases, undifferentiated, showed to be myoglobin negative, and desmin positive. We point out the importance of this fact in immunohistochemical determination of the specificity of this entity.