Additional activation of the AR gene may be involved in the development of the castration resistance phenotype in prostate cancer.

INTRODUCTION: Several studies have already shown that changes in the AR gene may be associated with a more aggressive disease phenotype and even castration-resistant prostate cancer. Thus, we investigated cytogenetic and molecular alterations linked to AR. MATERIALS AND METHODS: To evaluate AR methylation, we performed a cytogenetic-molecular analysis using fluorescence in situ hybridization that uses specific probes for the AR gene (Xq11.12) and the X chromosome centromere. For AR activity, we performed a qualitative analysis of human androgen receptor activity. To analyze the expression of AR in PC3 and LNCaP cell lines, we used qPCR assays. RESULTS: In the qPCR assay, we found downregulation of AR in the PC3 cell line compared with the LNCaP. We found the presence of X chromosome polysomy in PC-3 and LNCaP cell lines by FISH assay. In the HUMARA-Q assay, we found two X chromosomes/cell and the activity of both AR in the PC-3 cell line. In LNCaP cells, we found two X chromosomes/cell and methylation of only one AR. CONCLUSION: Castration-resistant prostate cancer phenotype represents a significant challenge in the setting of urological management. The X chromosomes and AR-linked alterations may contribute to a better understanding of the disease. However, further studies should be performed in an attempt to elucidate as much as possible the role of AR in the castration-resistant prostate cancer phenotype.

Disrupting membrane raft domains by alkylphospholipids.

Using phase contrast and fluorescence microscopy we study the influence of the alkylphospholipid, ALP, 10-(octyloxy) decyl-2-(trimethylammonium) ethyl phosphate, ODPC, in giant unilamellar vesicles, GUVs, composed of DOPC (1,2-dioleoyl-sn-glycero-3-phosphocholine), brain sphingomyelin (SM) and cholesterol (Chol). The results show that adding 100µM ODPC (below CMC) to the outer solution of GUVs promotes DOPC membrane disruption over a period of 1h of continuous observation. On the other hand, the presence of SM and Chol in homogeneous fluid lipid bilayers protects the membrane from disruption. Interestingly, by adding 100µM ODPC to GUVs containing DOPC:SM:Chol (1:1:1), which display liquid ordered (Lo)-liquid disordered (Ld) phase coexistence, the domains rapidly disappear in less than 1min of ODPC contact with the membrane. The lipids are subsequently redistributed to liquid domains within a time course of 14-18min, reflecting that the homogenous phase was not thermodynamically stable, followed by rupture of the GUVs. A similar mechanism of action is also observed for perifosine, although to a larger extent. Therefore, the initial stage of lipid raft disruption by both ODPC and perifosine, and maybe other ALPS, by promoting lipid mixing, may be correlated with their toxicity upon neoplastic cells, since selective (dis)association of essential proteins within lipid raft microdomains must take place in the plasma membrane.

(+)α-Tocopheryl succinate inhibits the mitochondrial respiratory chain complex I and is as effective as arsenic trioxide or ATRA against acute promyelocytic leukemia in vivo.

The vitamin E derivative (+)α-tocopheryl succinate (α-TOS) exerts pro-apoptotic effects in a wide range of tumors and is well tolerated by normal tissues. Previous studies point to a mitochondrial involvement in the action mechanism; however, the early steps have not been fully elucidated. In a model of acute promyelocytic leukemia (APL) derived from hCG-PML-RARα transgenic mice, we demonstrated that α-TOS is as effective as arsenic trioxide or all-trans retinoic acid, the current gold standards of therapy. We also demonstrated that α-TOS induces an early dissipation of the mitochondrial membrane potential in APL cells and studies with isolated mitochondria revealed that this action may result from the inhibition of mitochondrial respiratory chain complex I. Moreover, α-TOS promoted accumulation of reactive oxygen species hours before mitochondrial cytochrome c release and caspases activation. Therefore, an in vivo antileukemic action and a novel mitochondrial target were revealed for α-TOS, as well as mitochondrial respiratory complex I was highlighted as potential target for anticancer therapy.

Interaction of 10-(octyloxy) decyl-2-(trimethylammonium) ethyl phosphate with mimetic membranes and cytotoxic effect on leukemic cells.

10-(Octyloxy) decyl-2-(trimethylammonium) ethyl phosphate (ODPC) is an alkylphospholipid that can interact with cell membranes because of its amphiphilic character. We describe here the interaction of ODPC with liposomes and its toxicity to leukemic cells with an ED-50 of 5.4, 5.6 and 2.9 microM for 72 h of treatment for inhibition of proliferation of NB4, U937 and K562 cell lines, respectively, and lack of toxicity to normal hematopoietic progenitor cells at concentrations up to 25 microM. The ED-50 for the non-malignant HEK-293 and primary human umbilical vein endothelial cells (HUVEC) was 63.4 and 60.7 microM, respectively. The critical micellar concentration (CMC) of ODPC was 200 microM. Dynamic light scattering indicated that dipalmitoylphosphatidylcholine (DPPC) liposome size was affected only above the CMC of ODPC. Differential calorimetric scanning (DCS) of liposomes indicated a critical transition temperature (T(c)) of 41.5 degrees C and an enthalpy (H) variation of 7.3 kcal mol(-1). The presence of 25 microM ODPC decreased T(c) and H to 39.3 degrees C and 4.7 kcal mol(-1), respectively. ODPC at 250 microM destabilized the liposomes (36.3 degrees C, 0.46 kcal mol(-1)). Kinetics of 5(6)-carboxyfluorescein (CF) leakage from different liposome systems indicated that the rate and extent of CF release depended on liposome composition and ODPC concentration and that above the CMC it was instantaneous. Overall, the data indicate that ODPC acts on in vitro membrane systems and leukemia cell lines at concentrations below its CMC, suggesting that it does not act as a detergent and that this effect is dependent on membrane composition.