Changes in ovarian function in premenopausal women with breast cancer undergoing adjuvant TC (docetaxel and cyclophosphamide) chemotherapy during a brief period of amenorrhea around the last chemotherapy cycle.

PURPOSE: Docetaxel, a chemotherapeutic agent, induces high rates of transient chemotherapy-induced amenorrhea (CIA) when used as adjuvant chemotherapy for premenopausal women with breast cancer. Clinical laboratory data to assess the hormonal environment implicated in inducing transient CIA was assessed. METHODS: An observational study was conducted in 35 premenopausal women with hormone-responsive breast cancer who were receiving adjuvant docetaxel/cyclophosphamide (TC) chemotherapy. Serum estradiol and follicular stimulating hormone (FSH) levels were measured at one (n = 6) or two (n = 29) time point(s) around the completion of chemotherapy. RESULTS: As early as week 6 after the start of chemotherapy, just before the third TC cycle, serum estradiol levels were invariably suppressed (median of 5.5 pg/ml, n = 15, range <5-18.7 pg/ml) and FSH levels increased (median of 63.9 mIU/ml, range 24.5-127.4 mIU/ml), indicative of ovarian suppression to the menopausal levels. Subsequently, at 9 and 12 weeks, serum estradiol levels were suppressed to a median of 6.6 pg/ml (n = 49, range <5-17.3 pg/ml), while FSH levels were high (median of 66.8 mIU/ml, range 29.2-134.5 mIU/ml). There was a significant Spearman's correlation (ρ = 0.95, n = 29, p < 0.01) of high serum FSH levels (24.5-134.5 mIU/ml) between two time points of repeated measurements in 29 patients. TC chemotherapy induced rapid ovarian suppression with the formation of a high and stable plateau in serum FSH levels from week 6 to week 12. CONCLUSIONS: Recovery from transient CIA post-therapy may be partially attributed to high, stable FSH levels that occurred as early as after completion of the second TC chemotherapy cycle.

Prognostic value of matrix Gla protein in breast cancer.

To assess the prognostic value of matrix Gla protein (MGP) expression in cases of breast cancer, 9 samples from patients diagnosed with breast cancer who were followed up for more than 10 years were microdissected and then analyzed using Affymetrix U133 Plus 2.0 Arrays. Genes that exhibited significant differences in expression between patients with a good prognosis and those with a poor prognosis were identified. The MGP gene was among the genes up-regulated in cases where the prognosis was poor, indicating that the mRNA levels of MGP are a potential prognostic indicator of breast cancer. However, immunohistostaining of breast tissue microarrays (n=207) did not reveal a correlation between the protein expression of MGP and overall survival, neither was there a correlation between the protein expression of MGP and ER status or bone metastasis. In breast cancer cases, the mRNA level of MGP may be a marker indicating poor prognosis; however, protein expression determined by immunohistostaining is not.

Effect of xenon binding to a hydrophobic cavity on the proton pumping cycle in bacteriorhodopsin.

To understand the functional role of apolar cavities in bacteriorhodopsin, a light-driven proton pump found in Halobacterium salinarum, we investigated the crystal structure in pressurized xenon or krypton. Diffraction data from the P622 crystal showed that one Xe or Kr atom binds to a preexisting hydrophobic cavity buried between helices C and D, located at the same depth from the membrane surface as Asp96, a key residue in the proton uptake pathway. The occupation fraction of Xe or Kr was calculated as approximately 0.32 at a pressure of 1 MPa. In the unphotolyzed state, the binding of Xe or Kr caused no large deformation of the cavity. However, the proton pumping cycle was greatly perturbed when an aqueous suspension of purple membrane was pressurized with xenon gas; that is, the decay of the M state was accelerated significantly (~5 times at full occupancy), while the decay of an equilibrium state of N and O was slightly decelerated. A similar but much smaller perturbation in the reaction kinetics was observed upon pressurization with krypton gas. In a glycerol/water mixture, xenon-induced acceleration of M decay became less significant in proportion to the water activity. Together with the structure of the xenon-bound protein, these observations suggest that xenon binding helps water molecules permeate into apolar cavities in the proton uptake pathway, thereby accelerating the water-mediated proton transfer from Asp96 to the Schiff base.

Structural role of bacterioruberin in the trimeric structure of archaerhodopsin-2.

Archaerhodopsin-2 (aR2), a retinal protein-carotenoid complex found in the claret membrane of Halorubrum sp. aus-2, functions as a light-driven proton pump. In this study, the membrane fusion method was utilized to prepare trigonal P321 crystals (a=b=98.2 A, c=56.2 A) and hexagonal P6(3) crystals (a=b=108.8 A, c=220.7 A). The trigonal crystal is made up of stacked membranes in which the aR2 trimers are arranged on a honeycomb lattice. Similar membranous structures are found in the hexagonal crystal, but four membrane layers with different orientations are contained in the unit cell. In these crystals, the carotenoid bacterioruberin [5,32-bis(2-hydroxypropan-2-yl)-2,8,12,16,21,25,29,35-octamethylhexatriaconta-6,8,10,12,14,16,18,20,22,24,26,28,30-tridecaene-2,35-diol] binds to crevices between the subunits of the trimer. Its polyene chain is inclined from the membrane normal by an angle of about 20 degrees and, on the cytoplasmic side, it is surrounded by helices AB and DE of neighbouring subunits. This peculiar binding mode suggests that bacterioruberin plays a striking structural role for the trimerization of aR2. When compared with the aR2 structure in another crystal form containing no bacterioruberin, the proton release channel takes a more closed conformation in the P321 or P6(3) crystal; i.e., the native conformation of protein is stabilized in the trimeric protein-bacterioruberin complex. Interestingly, most residues participating in the trimerization are not conserved in bacteriorhodopsin, a homologous protein capable of forming a trimeric structure in the absence of bacterioruberin. Despite a large alteration in the amino acid sequence, the shape of the intratrimer hydrophobic space filled by lipids is highly conserved between aR2 and bacteriorhodopsin. Since a transmembrane helix facing this space undergoes a large conformational change during the proton pumping cycle, it is feasible that trimerization is an important strategy to capture special lipid components that are relevant to the protein activity.

Crystal structures of archaerhodopsin-1 and -2: Common structural motif in archaeal light-driven proton pumps.

Archaerhodopsin-1 and -2 (aR-1 and aR-2) are light-driven proton pumps found in Halorubrum sp. aus-1 and -2, which share 55-58% sequence identity with bacteriorhodopsin (bR), a proton pump found in Halobacterium salinarum. In this study, aR-1 and aR-2 were crystallized into 3D crystals belonging to P4(3)2(1)2 (a = b = 128.1 A, c = 117.6 A) and C222(1) (a = 122.9 A, b = 139.5 A, c = 108.1 A), respectively. In both the crystals, the asymmetric unit contains two protein molecules with slightly different conformations. Each subunit is composed of seven helical segments as seen in bR but, unlike bR, aR-1 as well as aR-2 has a unique omega loop near the N terminus. It is found that the proton pathway in the extracellular half (i.e. the proton release channel) is more opened in aR-2 than in aR-1 or bR. This structural difference accounts for a large variation in the pKa of the acid purple-to-blue transition among the three proton pumps. All the aromatic residues surrounding the retinal polyene chain are conserved among the three proton pumps, confirming a previous argument that these residues are required for the stereo-specificity of the retinal isomerization. In the cytoplasmic half, the region surrounded by helices B, C and G is highly conserved, while the structural conservation is very low for residues extruded from helices E and F. Structural conservation of the hydrophobic residues located on the proton uptake pathway suggests that their precise arrangement is necessary to prevent a backward flow of proton in the presence of a large pH gradient and membrane potential. An empty cavity is commonly seen in the vicinity of Leu93 contacting the retinal C13 methyl. Existence of such a cavity is required to allow a large rotation of the side-chain of Leu93 at the early stage of the photocycle, which has been shown to accompany water translocation across the Schiff base.

De novo insG619 mutation in PAX2 gene in a Japanese patient with papillorenal syndrome.

PURPOSE: To describe a Japanese patient with papillorenal syndrome (PRS) and to identify the genetic defect responsible for the disease. DESIGN: Interventional case report. METHODS: Complete ophthalmologic and systemic examinations were performed, and direct genomic sequencing of the PAX2 gene. RESULTS: Fundus examination of a 3-year-old Japanese girl showed atypical coloboma bilaterally. At 6 years of age, she presented with proteinuria, and renal ultrasonography showed hypoplastic kidneys bilaterally. Molecular genetic analysis of the PAX2 gene revealed a de novo heterozygous insertion of a G at position 619. CONCLUSIONS: Our findings suggest that an abnormal development of the optic stalk led to the optic disk dysplasia in PAX2-associated PRS. This indicates that we should consider renal abnormalities when an atypical round coloboma is present. Molecular genetic analysis of the PAX2 gene in combination with renal ultrasonography can help in making an earlier diagnosis of the disease.