Bryostatin 1 protects protein kinase C-delta from down-regulation in mouse keratinocytes in parallel with its inhibition of phorbol ester-induced differentiation.

Bryostatin 1 and phorbol-12-myristate-13-acetate (PMA) are both potent activators of protein kinase C (PKC), although in primary mouse keratinocytes bryostatin 1 does not induce differentiation and blocks PMA-induced differentiation. We report here that in primary mouse keratinocytes PMA caused translocation of PKC-epsilon to the Triton X-100-soluble fraction with an approximately 2-order of magnitude higher potency, compared with translocation of PKC-alpha and PKC-delta. The kinetics of translocation were fastest for PKC-epsilon, slower for PKC-alpha, and slowest for PKC-delta.

Role of oncogenes and tumor suppressor genes in multistage carcinogenesis.

The introduction of the techniques of molecular biology as tools to study skin carcinogenesis has provided more precise localization of biochemical pathways that regulate the tumor phenotype. This approach has identified genetic changes that are characteristic of each of the specific stages of squamous cancer pathogenesis: initiation, exogenous promotion, premalignant progression, and malignant conversion. Initiation can result from mutations in a single gene, and the Harvey allele of the ras gene family has been identified as a frequent site for initiating mutations.

Protein kinase C regulates keratinocyte transglutaminase (TGK) gene expression in cultured primary mouse epidermal keratinocytes induced to terminally differentiate by calcium.

During the final stage of epidermal differentiation, activation of keratinocyte transglutaminase results in covalent crosslinking of a variety of proteins to form highly protective cornified cell envelopes. We have studied the regulation of keratinocyte transglutaminase (TGK) gene expression in murine epidermal keratinocytes induced to terminally differentiate in vitro by increasing the level of extracellular Ca++ or treatment with the protein kinase C (PKC) activator 12-O-tetradecanoylphorbol-13-acetate (TPA). Raising extracellular Ca++ induces squamous differentiation of cultured keratinocytes and elicits a concentration-dependent increase in expression of TGK mRNA; keratinocytes grown for 24 h in 0.

Expression of an oncogenic rasHa gene in murine keratinocytes induces tyrosine phosphorylation and reduced activity of protein kinase C delta.

Murine keratinocytes expressing an oncogenic rasHa gene produce benign tumors in vivo and demonstrate altered responses to phorbol esters in vitro. Cultured keratinocytes transduced with the v-rasHa gene (v-rasHa keratinocytes) are resistant to Ca(2+)-induced terminal differentiation, a process that is dependent on protein kinase C (PKC) activation in normal keratinocytes. Five PKC isoforms expressed in keratinocytes (alpha, delta, epsilon, zeta, and eta) were examined for quantitative or qualitative changes in v-rasHa-transformed cells.

Plasma prekallikrein levels in patients with hepatocellular carcinoma and liver cirrhosis: a pilot study.

The concentration of plasma prekallikrein (PK) in five patients with hepatocellular carcinoma (HCC) has been measured and related to levels in 18 patients with liver cirrhosis (LC) and 30 healthy subjects. It was found that the mean PK level was significantly increased in patients with HCC, while patients with LC demonstrated lower concentrations, as compared with healthy subjects. The results indicate that PK might be useful in screening cirrhotic patients for HCC.

Epidermal growth factor receptor ligands regulate keratin 8 expression in keratinocytes, and transforming growth factor alpha mediates the induction of keratin 8 by the v-rasHa oncogene.

Cytokeratins 8 and 18 (Endo A and B) are among the earliest expressed embryonic genes and the major components of the cytoskeleton in simple epithelia of the adult. Recent data indicate that these cytokeratins are aberrantly expressed in several epithelial tumor types and that expression in cultured mouse keratinocytes is linked to activation of the rasHa oncogene. Furthermore, up-regulation of K8/K18 in keratinocytes is associated with reciprocal suppression of K1.

Inhibition of tumor formation from grafted murine papilloma cells by treatment of grafts with staurosporine, an inducer of squamous differentiation.

The microbial alkaloid staurosporine induces responses associated with protein kinase C activation, resulting in terminal differentiation in cultures of both normal and neoplastic mouse epidermal cells. As a cancer chemotherapy model, we treated grafts of mouse epidermal tumor cell lines 308 and SP-1 repeatedly with staurosporine. A dose-dependent inhibition of tumor formation, maximal at 0.

Coordinate changes in gene expression which mark the spinous to granular cell transition in epidermis are regulated by protein kinase C.

The protective function of skin depends on successful completion of a tightly regulated multi-step differentiation program, during which the induction of markers for a specific stage in epidermal differentiation is coupled to repression of markers expressed at the preceding stage. We have explored the role of protein kinase C (PKC) in this process using an in vitro model system, in which cultures of primary mouse epidermal keratinocytes are induced to terminally differentiate by raising the Ca2+ concentration in the medium from 0.05 to 0.

Analysis of phospholipid metabolism in murine keratinocytes transformed by the v-ras oncogene: relationship of phosphatidylinositol turnover and cytokine stimulation to the transformed phenotype.

Introduction of a v-rasHa oncogene into cultured mouse keratinocytes by transduction with a defective retrovirus is sufficient to transform keratinocytes to the benign phenotype. Transduced keratinocytes overexpress TGF alpha and hyperproliferate in culture medium with 0.05 mM Ca2+.

Transcripts encoding protein kinase C-alpha, -delta, -epsilon, -zeta, and -eta are expressed in basal and differentiating mouse keratinocytes in vitro and exhibit quantitative changes in neoplastic cells.

The protein kinase C (PKC) family of phospholipid-dependent serine-threonine kinases has been implicated in keratinocyte differentiation and neoplastic transformation. To determine if Ca(2+)-mediated keratinocyte differentiation is associated with changes in PKC isozyme gene expression, RNA was isolated from primary mouse keratinocytes grown in medium with 0.05, 0.

Staurosporine induces protein kinase C agonist effects and maturation of normal and neoplastic mouse keratinocytes in vitro.

Staurosporine is a potent but nonselective inhibitor of protein kinase C (PKC) and blocks responses to 12-O-tetradecanoylphorbol-13-acetate (TPA) in several cell types in vitro. In cultured primary mouse keratinocytes, however, staurosporine fails to inhibit TPA-mediated keratinocyte maturation and itself elicits responses that are similar to TPA (T. Sako et al.

Pyrimidobenzodiazepines. Synthesis of pirenzepine analog.

The synthesis of Pyrimido[4,5-b][1,5]benzodiazepine derivatives from 4-(o-aminophenylene)amino-5-ethoxy-carbonyl-1,2-dihydro-6-methyl-2 - oxopyrimidine has been described. Pyrimidobenzodiazepine 5 alkylated with N-methyl-N'-chloroacetyl-piperazine gives a product related to pirenzepine. Compound 5 shows weak antianxiety and antidepressive action.

[Imidazopyrimidodiazepines--new heterocyclic system; synthesis and properties].

The synthesis of the new tricyclic system ring 6-methyl-2,3,10,11-tetrahydroimidazo (1',2',3'-CD) pyrimido (5,4-b) (1,4) diazepinediones-5,8 is described. The 4-aryl- and 5-amino-imidazopyrimidodiazepines have also been obtained. The synthesis started from derivatives of 2-hydroxy-6-methyl-5-pyrimidine carboxylic acids.

Synthesis and biological properties of novel triazolopyrimido-pyrimidine-5,8-diones.

The synthesis of novel 1,2,4 triazolo[2,3,4-c,d]pyrimido[4,5-d]pyrimidine derivatives has been described from N-substituted amides of 1,2,3,4-tetrahydro-6-methyl-2-oxo-4-thio-5-pyrimidinecarboxylic acid 1. Amides 1 treated with 80% hydrazine hydrate, followed by aqueous-ethanolic formaldehyde form substituted triazolo[4,3-c]pyrimidines which cyclize in pyridine to triazolopyrimidopyrimidine derivatives 4. Attention has been paid to the synthesis of the 4-arylidenehydrazinopyrimidines 3.

Synthesis and properties of 7-methyl-5-oxo-1,5-dihydro-8-[1,2,4]-triazolo [4,3-c]pyrimidinecarboxylic acid derivatives.

The synthesis of the new triazolo[4,3-c]pyrimidines is described, starting from derivatives of 5-carboxy-2-hydroxy-4-hydrazino-6-methylpyrimidine. The 4-methyl-2,3-dihydropyrazolo[3,4-d]pyrimidine-3,6-dione was also obtained. Some of triazolo[4,3-c]pyrimidines tested for biological activity were found inactive.

Activation of human squamous cell carcinoma ornithine decarboxylase activity by guanosine triphosphate.

Previous studies have demonstrated the presence in mouse epidermal tumors of a structurally and functionally altered ornithine decarboxylase (ODC). In this report, the enzymatic properties of ODC from normal human skin and squamous cell carcinomas are examined. Some tumors contained a more heat stable ODC than the enzyme found in normal skin.

Hepatocanalicular injury associated with vitamin A derivative etretinate. An idiosyncratic hypersensitivity reaction.

A patient with pustular psoriasis developed jaundice, peripheral blood eosinophilia, and biochemical evidence of hepatocanalicular dysfunction four weeks after the initiation of etretinate therapy. A liver biopsy specimen showed bile duct damage, a periportal inflammatory infiltrate composed of neutrophils, eosinophils and lymphocytes, canalicular cholestasis, and focal hepatocyte necrosis. Clinical exclusion of other possible etiologic factors coupled with near resolution of the biochemical abnormalities within six weeks after complete discontinuation of the drug indicates that etretinate may induce an idiosyncratic hypersensitivity reaction.

Syntheses and biological properties of 8-carbamoylimidazo[1,2-c]pyrimidines and their heterocyclic analogs.

N-substituted 8-carbamoylimidazo[1,2-c]pyrimidines, 9-carbamoylpyrimido[1,2-c]pyrimidines and 8-carbamoyloxazolo[2,3-c]pyrimidines were obtained by the reaction of N-substituted 5-carbamoyl-2-hydroxy-4-mercapto-6-methylpyrimidines with aminoalcohols or ethylene chlorohydrin. Some of the described compounds exhibit weak antiinflammatory and analgetic effects.