Relevance of E-cadherin expression to EGFR-TKI molecular targeted therapy sensitivity/resistance and its clinical significance

We examined the effect of E-cadherin expression on epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) molecular targeted therapy sensitivity/resistance. We treated MCF-7, MDA-MB-231, T24, SiHa, H460, SK-HEP-1, MHCC97-H, and THP-1 cells with the EGFR-TKIs PD153035 and gefitinib, and then tested the drug-resistance and sensitivity using the MTT method, calculated IC50 values for each cell line, and compared the results to E-cadherin content. The MTT assay was used to determine the survival rates of MCF-7, MDA-MB-231, T24, SiHa, H460, SK-HEP-1, MHCC97-H, and THP-1 cells upon the action of EGFR-TKI (PD153035, gefitinib). For PD153035, the IC50 in MCF-7, MDA-MB-231, T24, and SiHa cells differed from that of H460, SK-HEP-1, MHCC97-H, and THP-1 (P < 0.05). Following gefitinib treatment, the IC50 values of MCF-7, MDA-MB-231, T24, and SiHa cells differed from those of H460, SK-HEP-1, MHCC97-H, and THP-1 cells (P < 0.01). The survival rate of MCF-7, MDA-MB-231, T24, and SiHa cells clearly decreased with increasing drug concentration, indicating the cells were sensitive to the drugs and that E-cadherin expression was positive; however, H460, SK-HEP-1, MHCC97-H, and THP-1 cells showed no significant decreased with increasing drug concentration, indicating that they were resistant to the drugs and that E-cadherin expression was negative. The survival rate of epithelial tumor cells through the action of EGFR-TKI is related to E-cadherin expression. E-cadherin may play a significant role in the sensitivity regulation of EGFR molecular targeting treatment. E-cadherin may provide important clues for selecting proper EGFR-TKI molecular targeting treatment.

LY191704 inhibits type I steroid 5 alpha-reductase in human scalp

Conversion of testosterone to dihydrotestosterone (DHT) has been demonstrated to be catalyzed by two isoforms of steroid 5 alpha-reductase, designated types I and II. Although several classes of steroid-based inhibitors of the type II isoform have been identified, these agents have not demonstrated highly selective pharmacological activity against human type I 5 alpha-reductase. LY191704 is representative of a series of nonsteroidal agents that have potent [apparent inhibitory constant (Ki) = 11.3 nM] inhibitory activity in human scalp skin homogenates (pH 7.5), a source of type I 5 alpha-reductase. [3H]-DHT production in the presence and absence of LY191704 is consistent with a noncompetitive mode of inhibition. In human prostatic homogenates (pH 5.5), a source of type II 5 alpha-reductase, LY191704 is virtually inactive as an inhibitor [concentration of inhibitor producing 50% inhibition of enzymatic activity (IC50) > 1,000 nM] of [3H]-DHT formation. LY191704 does not inhibit the type I or type II isoforms of rat 5 alpha-reductase, nor does the compound compete for binding to the murine androgen receptor expressed in SF9 cells using a baculo virus expression system. The benzoquinolinones, as exemplified by LY191704, possess exquisite pharmacological selectivity and provide a tool to understand the role of human type I 5 alpha-reductase in normal and pathophysiological states. These agents may also find clinical utility in treating androgen-dependent dermatological conditions.

Amycolatopsis alba sp. nov., isolated from soil

A new Amycolatopsis species isolated from soil produces a new glycopeptide antibiotic related to vancomycin. Traditional taxonomic methods and contemporary fatty acid analysis techniques were used to establish the position of this species. The hyphae fragment extensively when the organism is cultured in liquid media. The organism is characterized by white aerial hyphae that bear long chains of cylindrical conidia. The reverse side is yellowish brown; a faint light brown soluble pigment is occasionally produced. The organism has a type IV cell wall (meso-diaminopimelic acid), a type A whole-cell sugar pattern, and a type PII phospholipid pattern. Mycolic acids are not present in whole-cell hydrolysates. The major menaquinone is MK-9(H4); there is also a minor amount of MK-8(H4). The name proposed for this new species is Amycolatopsis alba. The type strain is strain A83850 (= NRRL 18532).

A83016F, a new member of the aurodox family

A new member of the aurodox family of antibiotics, A83016F, has been isolated from an unidentified actionmycete designated A83016. The structure and relative stereochemistry of A83016F were elucidated by NMR examination of the parent compound and its diacetate derivative. A83016F exhibits only weak antimicrobial activity.

A80915, a new antibiotic complex produced by Streptomyces aculeolatus. Discovery, taxonomy, fermentation, isolation, characterization, and antibacterial evaluation

New semi-naphthaquinone antibiotics A80915A, B, C, and D were isolated from the fermented broth of Streptomyces aculeolatus A80915 (NRRL 18422). Factors A and C, present in both the broth filtrate and mycelial methanol extract, and factors B and D, found predominantly in the broth filtrate, were recovered by extraction with ethyl acetate. Purification of the individual factors was accomplished by preparative reverse phase high performance liquid chromatograph on C18 bonded silica supports. Factors A through D show antimicrobial activity against Gram-positive aerobic and anaerobic organisms in vitro. Mechanism of action studies demonstrated nearly complete inhibition of macromolecular biosynthesis (protein, RNA, DNA, and cell wall) by A80915 factors A through D. A less highly cyclized semi-naphthaquinone, A80915 factor G, was isolated from the broth of the strain fermented in an alternate medium.

Actinomadura fibrosa sp. nov. isolated from soil

A new species of the genus Actinomadura which belongs to the Actinomadura madurae group of Goodfellow et al. was isolated from soil collected in Togo, West Africa. Traditional taxonomic methods plus contemporary fatty acid analysis techniques were used to establish the position of this species. Both physiological characteristics and fatty acid composition differentiate this strain from previously described species. This culture produces a new polyether antibiotic. It is characterized by the production of white to pink aerial hyphae on a limited number of media. The aerial hyphae appear asporogenous, forming thick fibers and projections instead of true spores. The reverse side is a distinctive reddish orange. This organism is resistant to 5% NaCl and grows at temperatures between 20 and 45 degrees C. Whole cells contain meso-diaminopimelic acid, galactose, glucose, mannose, madurose, phosphatidylinositol, and diphosphatidylglycerol. The menaquinones detected were MK-9(H6) and minor amounts of MK-9(H8). The name proposed for this new species is Actinomadura fibrosa; the type strain is strain NRRL 18348.

Enzyme immunoassay for macrolide antibiotics: characterization of an antibody to 23-amino-O-mycaminosyltylonolide

An enzyme-linked immunosorbent assay was developed for the detection of macrolide antibiotics by using a polyclonal antibody generated in rabbits immunized with 23-amino-O-mycaminosyltylonolide (23-amino-OMT) covalently linked to keyhole limpet hemocyanin. The specificity and sensitivity of this antibody were characterized by using 23-amino-OMT coupled to alkaline phosphatase as an enzyme-linked label in a direct competitive enzyme-linked immunosorbent assay. The assay sensitivity was as low as 0.3 ng/ml for 23-amino-OMT, with a 50% inhibitory concentration of 8 ng/ml. This antibody exhibited good reactivity with 12-, 14- or 16-membered macrolides possessing amino-substituted sugar moieties, regardless of the presence of neutral sugar residues. Little or no cross-reactivity was observed with the macrocyclic lactone ring structure (tylactone) or macrolides containing only neutral sugars. No cross-reaction was observed with polyenes or nonmacrolide antibiotics. Known macrolide-producing cultures grown in fermentation broth also showed good reactivity, indicating that this assay is useful in detecting this class of metabolites in fermentation.

A83586C, a new depsipeptide antibiotic

A culture identified as Streptomyces karnatakensis was found to produce a novel cyclic hexadepsipeptide antibiotic designated A83586C. The structure was elucidated by X-ray crystallography, and full 1H and 13C NMR assignments are reported. The absolute configuration was confirmed by the detection of D-threonine in the acid hydrolysate of A83586C. A83586C had potent Gram-positive activity in vitro but lacked in vivo efficacy in mice.

Method for the detection and quantitation of chitinase inhibitors in fermentation broths; isolation and insect life cycle effect of A82516

A new method of screening for chitinase inhibitors in crude fermentation broths as a means of discovering new insecticidal leads has been developed. In this procedure soluble Remazol brilliant violet 5R dye-coupled chitin degradation products released from insoluble chitin azure substrate by hydrolysis with Streptomyces griseus chitinase are filtered in 0.45 micron Millititer HA 96 well filtration plates and collected in 96 well microtiter plates. Inhibitors of this reaction are detected by a decrease in absorbance (570 nm) of the filtrate. A chitinase inhibitor, designated A82516, produced by culture A82516 was discovered using this screen. Purified A82516 was found to have an IC50 of 3.7 X 10(-6) M for S. griseus chitinase. At a test concentration of 0.27 mg/ml, A82516 was 100% effective in preventing development of house fly larvae to pupae. Allosamidin, a recently reported chitinase inhibitor in vitro, has spectral properties identical to A82516.

Enzyme-linked immunosorbent assay for the detection of fermentation metabolites: aminoglycoside antibiotics

A heterogeneous microplate enzyme immunoassay with a sensitivity of 10 pg/ml (1 pg/assay) toward gentamicin has been developed for the detection of aminoglycoside antibiotics in fermentation broths. Purified gentamicin antibody was coated onto the surface of the wells of microtiter plates and incubated with gentamicin-alkaline phosphatase conjugate. The amount of enzyme bound to the antibody was quantified by measuring the change in absorbance at 410 nm after the addition of the substrate, p-nitrophenylphosphate. Competitive assays performed by incubating the antibody and enzyme conjugate with various aminoglycosides showed that the antibody probe cross-reacted with all aminoglycosides tested, except neomycins B and C. No cross-reaction was detected with non-aminoglycoside antibiotics. Complex fermentation broths did not interfere with this assay. Cultures known to produce aminoglycosides were detected at levels well below the concentrations required for antimicrobial activity. This technique is useful in the identification, quantification and screening of fermentation metabolites.

Anthraquinones in the biosynthesis of sterigmatocystin by Aspergillus versicolor

14C-labeled averufin, versiconal hemiacetal acetate, and versicolorin A were efficiently converted to sterigmatocystin by Aspergillus versicolor, thus providing experimental evidence that these anthraquinones are biosynthetic precursors of sterigmatocystin, a xanthone.

Step of dichlorvos inhibition in the pathway of aflatoxin biosynthesis

Dichlorvos (dimethyl 2,2-dichlorovinyl phosphate) inhibits the biosynthesis of aflatoxin by Aspergillus parasiticus. Cultures treated with dichlorvos excrete an orange pigment which can be converted into aflatoxin B(1) by the untreated mycelia. The orange pigment was partially identified as an acetyl derivative of versiconol-type compound. In the presence of dichlorvos, sterigmatocystin is converted into aflatoxin B(1) without being interfered, but averufin is converted into the orange pigment instead of aflatoxin B(1). Therefore, dichlorvos appears to block an enzymatic step in the aflatoxin biosynthetic pathway, which lies beyond averufin but before sterigmatocystin, at the formation of the orange pigment.