Neuroblastoma may arise from the blockage of differentiation of neuroblast along the neuronal pathway. In previous studies, we were able to induce differentiation of certain neuroblastoma cell lines with NGF. In order to study the gene regulation during differentiation, we hybridized several cDNA probes with RNA extracted from different cell lines before and after NGF treatment, and found that c-myc oncogene was down-regulated in NGF-induced differentiated cells in comparison with the control samples. The time course of c-myc down-regulation was concordant with the appearance of morphological changes of differentiation. No significant change was found in the expression of other oncogenes like K-ras and N-ras in the neuroblastoma cell lines before and after NGF treatment. The results indicate that down-regulation of c-myc oncogene may be one of the important events during NGF-induced differentiation and over expression of c-myc oncogene may, at least partly, be responsible for the development of neuroblastoma.

Activation of oncogenes in human fetal esophageal epithelium by alternariol monomethyl ether (AME) is reported. AME is a main metabolite of Alternaria alternata which is considered to be a dominant pollutant in the harvested grain in Linxian County (a high risk area of esophageal cancer). It was found that NIH/3T3 cells were transformed via transfection of DNA extracted from human fetal esophageal epithelium having been treated with AME in short term in vitro. The transformed cells formed clony when inoculated in 0.3% soft agar, and developed solid tumor after inoculated subcutaneously into BALB/C nude mice. Molecular hybridization experiment proved in the genome of transformed cells that there were sequences which hybridized with Alu probe. When hybridized with oncogene probes by means of Southern hybridization, samples of human fetal esophageal epithelium treated with AME showed marked amplification of c-H-ras and c-myc genes; DNA from transformed NIH/3T3 cells via transfection of genes of tissues mentioned above showed also significant amplification of c-H-ras gene. It demonstrated that c-H-ras and c-myc oncogenes in normal human fetal esophagus could be activated by a short-term treatment of AME in vitro. These results are considered to be the direct evidence of the view that AME may be one of the etiologic factors of human esophageal cancer.

We investigated the levels of atrial natriuretic peptide (r-ANP) gene expression in the atria of rats aged 2-3 months and 14-18 months. In the meantime, we studied the effects of ginsenosides on r-ANP gene expression by determining the content of ANP messenger ribonucleic acid (r-ANP-mRNA). Male and female rats were abdominally injected aqueous solution of ginsenoside (prepared from ginseng stems and leaves (G-SL) and ginseng roots (G-R) 50 mg/kg body weight, once a day, for 7 days. Atrial total RNA was extracted by cold phenol method. The specificity and relative contents of r-ANP-mRNA were determined by using Northern blot and Dot blot hybridization respectively with alpha-32P-labeled r-ANP-cDNA probe. The results showed that the r-ANF-mRNA levels in male and female rats at the age of 14-18 months were about 15% and 60% of those in male and female rats at the age of 2-3 months. G-SL and G-R increased r-ANP-mRNA contents in male rats at the age of 14-18 months by 1 fold and 1.7 folds respectively; whereas they decreased r-ANP-mRNA contents in male rats at the age of 2-3 months. No apparent effects of ginsenosides on ANP gene expression was observed in female rats. These results showed that ANP gene expression is more declined in elder rats and ginseng has certain effects in the aspect of heart endocrine to combat decrepitude.

The expression of tumor necrosis factor-alpha (TNF-alpha) mRNA in murine inflammatory peritoneal macrophages (M phi) was studied with a sensitive liquid hybridization method. Upon exposure to 10-1000 ng/ml of lipopolysaccharide (LPS), M phi were induced to express TNF-alpha mRNA in a dose-dependent manner. mRNA was detectable within 1 h after stimulation, peaked at about 2 h and then gradually declined. A 10 min treatment with LPS was enough to stimulate the maximal level of TNF-alpha mRNA, as determined in a 2 h period. Although calcium ionophore A23187 and macrophage activating factor (MAF) (both can activate M phi to mediate tumoricidal activity) did not induce TNF-alpha mRNA expression by themselves, they did act synergistically with LPS. Treatment of M phi with retinoic acid strongly inhibited LPS-induced TNF-alpha mRNA expression, whereas trifluoperazine had an opposite effect. Cycloheximide not only synergized with LPS but also induced TNF-alpha mRNA expression by itself. In contrast, actinomycin D completely blocked LPS-induced TNF-alpha gene activation. These findings indicate that LPS-induced TNF-alpha mRNA expression is not solely due to an increase in intracellular free calcium ion and is independent of the protein kinase C pathway of signal transduction. In addition, TNF gene activity may be regulated by short-lived protein repressor(s).

With dot blot and cytoplasmic hybridization techniques we found that the c-Ha-ras, c-Ki-ras, c-N-ras, c-myc and c-fos oncogenes were over-expressed in human hepatocellular carcinoma cell line BEL 7402 cells. The mRNA expression of c-Ha-ras, c-Ki-ras, c-N-ras and c-myc oncogenes could be inhibited by 2 mmol/L sodium butyrate treatment, but this had no effect on the expression of c-fos. However, the mRNA expression of c-Ha-ras, c-N-Ras and c-myc oncogenes was enhanced by 4 mmol/L sodium butyrate treatment, while the expression of c-Ki-ras and c-fos remained unchanged. No significant effect on the expression of carbamyl phosphate synthetase I, a tissue-specific enzyme associated with the differentiation of liver cells, was observed by 2 mmol/L or 4 mmol/L sodium butyrate treatment of the hepatoma cells.

Chuangxinmycin (CXM) and L-trp cause repression of trp-operon in wild strain of E. coli and indolepropanic acid (IPA) causes derepression of this strain. In CXM-resistant mutant strain, CXM and IPA both cause derepression, and interaction of CXM and IPA is competitive. However, L-trp results in neither repression nor derepression in the mutant, but it can counteract the activity of CXM or IPA. These results suggest that there are repression and derepression sites on repressor of E. coli. CXM can bind to both sites, but mainly to repression site. The structure of repression site of the CXM-resistant mutant is altered, so that CXM can not bind to the repression site and binds mainly to the derepression site, thus leading to the derepression of trp-operon.

Using radioligand receptor binding methods, the affinities (Ki) of amoxapine and loxapine for various receptors (adrenergic alpha 1, alpha 2, beta; dopaminergic D1, D2; serotoninergic 5-HT1, 5-HT2; Muscarinic, GABA, BZ) were investigated. The two compounds showed high affinities for 5-HT2, D2 and alpha 1 receptors (Ki less than 10(-7) mol/L), moderate affinity for alpha 2 receptor (Ki less than 10(-6) mol/L), and low affinities for M and 5-HT1 receptor (Ki less than 10(-5) mol/L). In addition, amoxapine appeared to have low affinities for D1 and GABA receptors. For D1 receptor, loxapine was found to have moderate affinity which was nearly 20 fold greater than amoxapine, but amoxapine exhibited more potent inhibitory effects on serotonin receptors and weaker inhibitory affects on dopamine receptors. Neither amoxapine nor loxapine showed significant affinity for BZ and beta-adrenergic receptors. These differences in the affinities may be responsible for their different psychopharmacological effects in the clinical treatment of patients. The regulation of 5-HT2 and beta receptors were examined in chronic experiments on rats given amoxapine 8 mg/kg or loxapine 1 mg/kg orally once daily for one to three weeks. The 5-HT2 receptor density was time-dependently reduced but no effect on beta receptors was observed. The down-regulation of 5-HT2 receptors might be associated with antidepressant action of the two drugs.

The aim of the present study was to explore whether the expression of angiotensinogen (Ang) gene was accelerated during the development of morphine tolerance or electroacupuncture tolerance. The total rat brain RNA was extracted by phenol, and dot blot hybridization with synthetic Ang oligo-DNA was adopted for measuring Ang mRNA. Autoradiographic examination revealed a marked increase in Ang mRNA in rats receiving multiple injections of morphine or continuous electroacupuncture (EA) stimulation for several hours. The integrated O.D. (I.O.D.) of the hybridized dots revealed a 1-fold and 8-fold increase in Ang mNRA in rats receiving morphine injection for 1 and 4 days, respectively, and a 5-fold and 13-fold increase in rats receiving 3 and 6h EA stimulation, respectively. The results suggest that transcription of Ang gene in rat brain can be accelerated within 3-4h by continuous morphine or EA stimulation and that a longer lasting stimulation resulted in a stronger gene expression.

Chinese medicinal herbs with Jian Pi Li Qi action were tested for their effects in inhibiting the precancerous lesions, gamma-GT positive hepatocellular foci and the expression of oncogenes (N-ras, Ha-ras) in male SD rats. The rats were given one i.p. dose of initiator DEN within 24 hours after 2/3 partial hepatectomy. The livers of sacrificed rats were processed to gamma-GT histochemical staining and measuring of oncogenic expression. The results of these two parameters showed that Chinese medicinal herbs with Jian Pi Li Qi action are effective in inhibiting the precursory lesions of liver cancer in rats.