FHL2, a novel tissue-specific coactivator of the androgen receptor.

The control of target gene expression by nuclear receptors requires the recruitment of multiple cofactors. However, the exact mechanisms by which nuclear receptor-cofactor interactions result in tissue-specific gene regulation are unclear. Here we characterize a novel tissue-specific coactivator for the androgen receptor (AR), which is identical to a previously reported protein FHL2/DRAL with unknown function. In the adult, FHL2 is expressed in the myocardium of the heart and in the epithelial cells of the prostate, where it colocalizes with the AR in the nucleus. FHL2 contains a strong, autonomous transactivation function and binds specifically to the AR in vitro and in vivo. In an agonist- and AF-2-dependent manner FHL2 selectively increases the transcriptional activity of the AR, but not that of any other nuclear receptor. In addition, the transcription of the prostate-specific AR target gene probasin is coactivated by FHL2. Taken together, our data demonstrate that FHL2 is the first LIM-only coactivator of the AR with a unique tissue-specific expression pattern.

Pharmacokinetics and body distribution of liposomal zinc phthalocyanine in tumor-bearing mice: influence of aggregation state, particle size, and composition.

The pharmacokinetics and body distribution of zinc phthalocyanine (ZnPc) intravenously administered in liposomes composed of ZnPc, 1-palmitoyl-2-oleoylphosphatidylcholine (POPC), and 1,2-dioleoylphosphatidylserine (OOPS) (1:90:10 or 1:70:30 w/w) to tumor (Meth A sarcoma) bearing mice were studied. It was found that aggregation of ZnPc in the liposomes (i) increases the clearance rate of the dye from plasma, (ii) lowers the maximal dye concentration in tumor tissue, and (iii) increases the maximal dye concentration in the liver. In addition, aggregated dye is hardly eliminated from the liver and monomeric dye is eventually completely eliminated from this organ. Liposomes in the size range of 48-123 nm, containing the dye with the same aggregation state, showed the same pharmacokinetics and body distribution of the dye. The PS-content of the ZnPc liposomes (POPC alone versus POPC/OOPS 7:3) did not influence tumor, liver, and plasma pharmacokinetics during the studied time intervals. Free flow electrophoretic analysis showed in lyophilisates of ZnPc liposomes containing aggregated ZnPc the presence of two distinct populations differing in size, aggregation state of the dye, and PC/PS and ZnPc/phospholipid ratio. The liposomal formulation with monomeric ZnPc has a compositional homogeneity and demonstrated selectivity and reached high uptake in tumors, 48 h after intravenous administration and appears promising for photodynamic therapy.

Large-scale production of liposomes containing monomeric zinc phthalocyanine by controlled dilution of organic solvents.

This work describes the development of an organic solvent dilution method suitable for the large scale manufacturing of small unilamellar liposomes containing the water-insoluble photosensitizer zinc phthalocyanine in the monomeric state. N-Methyl pyrrolidone (NMP)/tert-butyl alcohol was selected as water miscible organic phase in which the phospholipids 1-palmitoyl, 2-oleoylphosphatidylcholine (POPC), and 1,2-dioeloylphosphatidylserine (OOPS) and the dye were dissolved. This organic phase was mixed with an excess of a water phase using a dynamic mixing device, yielding reproducibly unilamellar liposomes with a mean size of 50-150 nm as measured with quasielastic light scattering. After concentration, the organic solvents were efficiently removed by cross-flow filtration. The liposomes were then sterile filtered and freeze-dried. A method to measure the aggregation state of the dye in the liposomes was developed. A stable lyophilized formulation containing monomeric liposomal ZnPc could be obtained by using a solution of ZnPc in NMP (2 mg/mL) and ZnPc/phospholipid (1:100 w/w ratio) and performing concentration and dialysis at 4 degrees C and lyophilization in presence of a mixture of lactose and phospholipid (5:1 w/w ratio).

CGP 55398, a liposomal Ge(IV) phthalocyanine bearing two axially ligated cholesterol moieties: a new potential agent for photodynamic therapy of tumours.

Ge(IV) phthalocyanine (GePc) with two axially ligated cholesterol moieties was prepared by chemical synthesis and incorporated in a monomeric state into small unilamellar liposomes (CGP 55398). Upon photoexcitation with light wavelengths around its intense absorption peak at 680 nm, GePc shows an efficient photosensitising activity towards biological substrates through a mechanism which largely involves the intermediacy of singlet oxygen. GePc injected systemically into mice bearing an intramuscularly implanted MS-2 fibrosarcoma is quantitatively transferred to serum lipoproteins and localises in the tumour tissue with good efficiency: at 24 h post injection the GePc content in the tumour is 0.74 and 1.87 micrograms per g of tissue with a tumour/peritumoral ratio of 4.35 and 5.67 for injected doses of 0.76 and 1.52 mg kg-1 respectively. At this time the red-light irradiation of the GePc-loaded fibrosarcoma causes a fast and massive tumour necrosis involving both malignant cells and blood vessels.