Association between gain-of-function mutations in PIK3CA and resistance to HER2-targeted agents in HER2-amplified breast cancer cell lines.

BACKGROUND: The mechanism of resistance to human epidermal growth factor receptor 2 (HER2)-targeted agents has not been fully understood. We investigated the influence of PIK3CA mutations on sensitivity to HER2-targeted agents in naturally derived breast cancer cells. MATERIALS AND METHODS: We examined the effects of Calbiochem (CL)-387,785, HER2 tyrosine kinase inhibitor, and trastuzumab on cell growth and HER2 signaling in eight breast cancer cell lines showing HER2 amplification and trastuzumab-conditioned BT474 (BT474-TR). RESULTS: Four cell lines with PIK3CA mutations (E545K and H1047R) were more resistant to trastuzumab than the remaining four without mutations (mean percentage of control with 10 microg/ml trastuzumab: 58% versus 92%; P = 0.010). While PIK3CA-mutant cells were more resistant to CL-387,785 than PIK3CA-wild-type cells (mean percentage of control with 1 microM CL-387,785: 21% versus 77%; P = 0.001), CL-387,785 retained activity against BT474-TR. Growth inhibition by trastuzumab and CL-387,785 was more closely correlated with changes in phosphorylation of S6K (correlation coefficient, 0.811) than those of HER2, Akt, or ERK1/2. Growth of most HER2-amplified cells was inhibited by LY294002, regardless of PIK3CA genotype. CONCLUSIONS: PIK3CA mutations are associated with resistance to HER2-targeted agents. PI3K inhibitors are potentially effective in overcoming trastuzumab resistance caused by PIK3CA mutations. S6K phosphorylation is a possibly useful pharmacodynamic marker in HER2-targeted therapy.

Direct determination of silicon in powdered aluminium oxide by use of slurry sampling with in situ fusion graphite-furnace atomic-absorption spectrometry.

A direct method for determination of silicon in powdered high-purity aluminium oxide samples, by slurry sampling with in situ fusion graphite-furnace atomic-absorption spectrometry (GF-AAS), has been established. A slurry sample was prepared by 10-min ultrasonication of a powdered sample in an aqueous solution containing both sodium carbonate and boric acid as a mixed flux. An appropriate portion of the slurry was introduced into a pyrolytic graphite furnace equipped with a platform. Silicon compounds to be determined and aluminium oxide were fused by the in situ fusion process with the flux in the furnace under optimized heating conditions, and the silicon absorbance was then measured directly. The calibration curve was prepared by use of a silicon standard solution containing the same concentration of the flux as the slurry sample. The accuracy of the proposed method was confirmed by analysis of certified reference materials. The proposed method gave statistically accurate values at the 95% confidence level. The detection limit was 3.3 microg g(-1) in solid samples, when 300 mg/20 mL slurry was prepared and a 10 microL portion of the slurry was measured. The precision of the determination (RSD for more than four separate determinations) was 14% and 2%, respectively, for levels of 10 and 100 microg g(-1) silicon in aluminium oxide.

Three new sesquiterpene lactones from the pericarps of Illicium merrillianum.

Structures of three new sesquiterpene lactones 1-3, isolated from the pericarps of Illicium merrillianum, have been assigned as 14-O-benzoylfloridanolide, 2,10-epoxy-3-dehydroxypseudoanisatin and 7-O-methylpseudomajucin on the basis of spectroscopic data and chemical transformation. The structure of 2, having an ether linkage between C-2 and C-10, has been confirmed by X-ray crystallographic analysis.

Two new meliacarpinins from the roots of Melia azedarach.

Two new azadirachtin-type limonoids, 1-methacrylyl-3-acetyl-11-methoxymeliacarpinin (1) and 1-(2-methylpropanoyl)-3-acetyl-11-methoxymeliacarpinin (2), together with the known compounds, meliacarpinin D (3), melianin B (4) and 2 beta,3 beta-dihydroxy-5 alpha-pregn-17(20)-(Z)-en-16-one (5), were isolated from the roots of Melia azedarach. The structures of 1 and 2 were elucidated by analysis of spectroscopic data and comparison of their NMR data with those of 3. Compounds 1 and 5 exhibited significant activity in the brine shrimp lethality test (BST).

A preliminary report of the treatment of blue nevus with dermal injection of riboflavin and exposure to near-ultraviolet/visible radiation (ribophototherapy).

Dye lasers are useful for treating pigmented skin lesions, but their equipment is expensive and bulky. A simple and cheap phototherapy would be acceptable to dermatologists for treating pigmented skin lesions such as nevus of Ota. We investigated as a pilot study whether dermal injection of riboflavin and exposure to near-ultraviolet/visible radiation (ribophototherapy) decreases the dermal pigment of blue nevi which are recalcitrant to laser therapy. The therapeutic efficacy was assessed by comparison of the amount of dermal pigment in hematoxylin-eosin specimens taken before and after treatment. Pigmentation of the nevus became faint to the depth of 1 mm with little noticeable epidermal change after 21 treatments. At the deeper dermis somewhere between 3 and 4 mm from the epidermis, ballooning degeneration of the dermal cells was observed in hematoxylin-eosin specimens. Ribophototherapy is hopeful for treating pigmented skin lesions.

[Predonation and transfusion in open heart surgery].

The efficacy of predonation of autologous blood in reducing the use homologous blood during open heart surgery was investigated. Between January 1997, and February 1998, predonation and transfusion was studied in 100 consecutive open heart operations (CABG, 77; valve surgery, 17; ASD, 5; myxoma, 1). The guidelines for autologous predonation were as follows: an age < 70 years, a weight > 40 kg and a hemoglobin > 12 g/dl. Patients in NYHA class IV or undergoing emergency operation were excluded. The blood loss during operation ranged from 195 to 1,850 ml (mean; 670 ml), being from 305 to 1,850 ml (723 ml) for CABG, from 260 to 1,020 ml (493.5 ml) for valve surgery and from 195 to 570 ml (342 ml) for ASD. The blood loss was not significantly dependent on sex or age and did not differ elective and emergent operations. Only 36.6% of patients with autologous predonation needed homologous transfusion versus 63.4% of those without predonation. Homologous transfusion was done in only 5% of the those with predonation of 800 ml versus 69% at 400 ml and 71% at 200 ml. In conclusion, autologous blood transfusion is effective for reducing the homologous blood requirement. It also seems that predonation of 800 ml may be sufficient to allow open heart surgery without blood transfusion.

Garsubellin A, a novel polyprenylated phloroglucin derivative, increasing choline acetyltransferase (ChAT) activity in postnatal rat septal neuron cultures.

Garsubellin A (1), a novel polyprenylated phloroglucin derivative, has been isolated from the wood of Garcinia subelliptica and its structure has been elucidated by spectroscopic analyses. Compound 1 could increase the ChAT activity at 10 microM in P10 rat septal neuron cultures.

Novel xanthones with superoxide scavenging activity from Garcinia subelliptica.

Two new xanthones, garciniaxanthone D (1) containing a dihydrobenzofuran ring and 1,4,5-trihydroxyxanthone (2), have been isolated from Garcinia subelliptica as superoxide anion scavengers. Their structures have been determined mainly by spectroscopic methods and some chemical reactions.

Cloning and functional expression of a Na(+)-dependent phosphate co-transporter from human kidney: cDNA cloning and functional expression.

A cDNA clone encoding a protein 69% identical in amino acid sequence with that of the Na/P(i) co-transporter NaP(i)-1 was isolated from a human kidney cDNA library. The DNA sequence was identical with that of NPT-1 cDNA published by Chong, Kristjansson, Zoghbi and Hughe (1993) (Genomics, 18, 355-359). In the present study, we have characterized the function of the encoded protein and the tissue distribution of its mRNA. Injection of RNA transcribed from NPT-1 into Xenopus oocytes resulted in expression of Na/P(i) co-transport activity showing a high affinity for P(i) transport (Km 0.29 mM). Kinetic characterization ([P(i)], [Na+]) demonstrated that the expressed transport activity has properties similar to those displayed by oocytes injected with human kidney poly(A)+ RNA. Northern blotting demonstrated that NPT-1 mRNA is expressed in renal cortex, liver and brain but not in other tissues. Hybrid depletion with antisense oligonucleotides to NaP(i)-3 and NPT-1 completely inhibited poly(A)+ RNA-induced Na(+)-dependent P(i) uptake in oocytes. These findings indicate that two high-affinity Na/P(i) cotransporters (NaP(i)-3 and NPT-1) are present in human kidney cortex.

Circadian rhythm of brain susceptibility to haloperidol during chronic administration.

Circadian fluctuation has been reported to exist to the effects of haloperidol after acute administration. In an attempt to clarify the viability of chronotherapy with haloperidol, the antiapomorphine effect of haloperidol after chronic administration was investigated in the present paper. Haloperidol was administered once daily at the same time for 21 consecutive days to rats which were kept under 12 hr lighting conditions with light onset at 19:30. Then the chronology of the antiapomorphine effect was investigated. The antiapomorphine effect was significantly stronger in the group treated at 19:30 than that treated at 13:30. These data agreed with the results found after the acute administration of the drug. After chronic administration, no difference was found in the plasma and brain level of haloperidol due to the time of administration. These experimental results seem to suggest that a circadian rhythm in the brain susceptibility to haloperidol exists even during chronic administration.