Protein synthesis through the PI3k‐Akt pathway is reduced in aged skeletal muscle, leading to a decrease in fiber size and number. Phytoecdysteroids, in particular 20‐hydroxyecdysone (20E), from the plant Ajuga turkestanica increases protein synthesis in C2C12 skeletal muscle cells and muscle strength in young rats. The objective of this study was to determine if an extract from A. turkestanica (ATE), enriched in phytoecdysteroids, affects muscle fiber size and PI3k‐Akt signaling in skeletal muscle of aged mice. Aged male C57BL/6 mice (20 mo) received ATE, 20E, or vehicle (CT) only for 28 days. H&E staining revealed 41% and 30% larger fiber cross‐sectional area (CSA) in the triceps brachii (p=0.014) and plantaris (p=0.018) muscles of 20E‐treated sedentary mice, respectively, compared to CT. ATE treatment resulted in larger, but non‐significant differences in CSA of the triceps brachii (26%; p=0.088) and plantaris (8%; p=0.497) muscles, compared to CT. Western blotting performed on gastrocnemius muscles showed a significant increase in phosphorylation of Akt in 20E‐treated sedentary aged skeletal muscle, compared to CT (p=0.013). In conclusion, these data suggest that 20E rescues the loss of muscle fiber size and increases activation of the PI3k‐Akt pathway in sedentary aged skeletal muscle. Supported in part by a USDA Kannapolis Scholars Fellowship.

e14577 Background: The purpose of this study was to perform a meta-analysis of literature data and see if [F-18]FDG and PET imaging can be used to predict the early response to chemotherapy based upon the measure of standard uptake value (SUV) or drug uptake ratio (DUR; a measure of glycolytic index) in breast cancer patients. This intervention may identify the responders for continued therapy or identify the non- responders for change of therapy. Methods: A literature search determined the number of studies that used PET-FDG imaging to monitor the response of various chemotherapies in breast cancer patients. A total of nine studies have been reviewed that used SUV/DUR as a measure of glycolytic activity of the primary tumors. The percent decrease of SUV over baseline was determined for chemotherapy cycle 1 and for subsequent cycles. A paired t-test was performed to see the statistical significance of the SUV decrease. Results: Five (n=158) studies presented the data in % mean reduction in SUV and four (n=59) studies presented SUV values for the individual patient. The average decrease in SUV in responders were 29% and 51% after first and second cycle, respectively. The non responders did not show significant change in SUV as compared to responders. Conclusion: The preliminary data mining and analysis strongly implies that PET imaging using [F-18]FDG may be used to monitor the progress of chemotherapy in breast cancer patients. This study was supported by a grant from OWH, FDA. The results do not represent official FDA position. No significant financial relationships to disclose.

UNLABELLED:The aim of this study was to investigate the potential of a new iodobenzamide, N-[2-(1'-piperidinyl)ethyl]-3-(123)I-iodo-4-methoxybenzamide (P-(123)I-MBA), to visualize primary breast tumor in humans in vivo. Tumor accumulation of benzamides is based on a preferential binding to sigma receptors that are overexpressed on breast cancer cells.METHODS:P-(123)I-MBA (148-185 MBq) was administered to 12 patients with a mammographically suspicious breast mass. Two hours after administration, whole-body and spot images of the healthy and the diseased breast were obtained.RESULTS:A focal increased tracer accumulation was observed in 8 of 10 patients with histologically confirmed breast cancer (mean tumor-to-background ratio, 2.04). No uptake was seen in a case of lymphatic adenitis.CONCLUSION:This preliminary patient study shows that P-(123)I-MBA accumulates in most breast tumors in vivo. Future work should focus on the relationship between P-(123)I-MBA uptake and the proliferative activity of cells to anticipate use of this technique as a tool to noninvasively assess the degree of tumor proliferation.

The goal of this study was to investigate the potential use of a radioiodinated benzamide, N-[2-(1′-piperidinyl)ethyl]-3-iodo[125I]-4-methoxybenzamide (P[125I]MBA), a sigma receptor binding radioligand for imaging breast cancer. The chemical and radiochemical syntheses of PIMBA are described. The pharmacological evaluation of PIMBA was carried out for sigma-1 and sigma-2 receptor sites. The in vivo pharmacokinetics of the radioiodinated benzamide were determined in rats and comparison of P[125I]MBA with Tc-99m sestamibi were made in a rat mammary tumor model. Sigma-1 affinity (Ki) for PIMBA in guinea pig brain membranes using [3H](+)pentazocine was found to be 11.82 ± 0.68 nM, whereas sigma-2 affinity in rat liver using [3H]DTG (1,3-o-di-tolylguanidine) was 206 ± 11 nM. Sites in guinea pig brain membranes labeled by P[125I]MBA showed high affinity for haloperidol, (+)-pentazocine, BD1008, and PIMBA ( Ki=4.87±1.49,8.81±1.97,0.057±0.005,46.9±1.8 nM, respectively). Competition binding studies were carried out in human ductal breast carcinoma cells (T47D). A dose-dependent inhibition of specific binding was observed with several sigma ligands. Ki values for the inhibition of P[125I]MBA binding in T47D cells for haloperidol, N-[2-(1′-piperidinyl)]ethyl]4-iodobenzamide (IPAB), N-(N-benzylpiperidin-4-yl)-4-iodobenzamide (4-IBP), and PIMBA were found to be 1.30 ± 0.07, 13 ± 1.5, 5.19 ± 2.3, 1.06 ± 0.5 nM, respectively. The in vitro binding data in guinea pig brain membranes and breast cancer cells confirmed binding to sigma sites. The saturation binding of P[125I]MBA in T47D cells as studied by Scatchard analysis showed saturable binding, with a Kd=94±7 nM and a Bmax=2035±305 fmol/mg of proteins. Biodistribution studies in Sprague–Dawley rats showed a rapid clearance of P[125I]MBA from the normal organs. The potential of PIMBA in imaging breast cancer was evaluated in Lewis rats bearing syngeneic RMT breast cancers, a cancer that closely mimics human breast cancer histology. At 1 h postinjection, tumor uptake for P[125I]MBA and Tc-99m sestamibi were found to be 0.35 ± 0.01 and 0.32 ± 0.01 % injected dose/organ (%ID/g), respectively. The %ID/g for liver, kidneys, and heart were 2, 11, and 20 times lower, respectively, for P[125I]MBA as compared with Tc-sestamibi. Slightly higher uptake of P[125I]MBA in tumors (than Tc-sestamibi) and a low nontarget organ uptake warrants further studies of this and other sigma receptor ligands for their use as breast cancer imaging agents.

Sigma receptors are known to be expressed in a variety of human tumor cells, including breast, neural, and melanoma tumors. A very high density (1.0-1.5 million receptors/cell) of sigma receptors was also reported in a human androgen-dependent prostate tumor cell line (LNCaP). In this study, we show that a very high density of sigma receptors is also expressed in an androgen-independent human prostate tumor cell line (DU-145). Pharmacological binding studies using the sigma-1-selective ligand [3H](+)-pentazocine showed a high-affinity binding (Kd = 5.80 nM, Bmax = 1800 fmol/mg protein). Similarly, binding studies with [3H]1,3-di-o-tolylguanidine in the presence of dextrallorphan also showed a high-affinity binding (Kd = 15.71 nM, Bmax = 1930 fmol/mg protein). Radioiodinated benzamide N-[2-(1'-piperidinyl)ethyl]-3-[125I]iodo-4-methoxybenzamide ([125I]PIMBA) was also shown to bind DU-145 cells in a dose-dependent manner. Three different radioiodinated benzamides, [125I]PIMBA, 4-[125I]iodo-N-[2-(1'-piperidinyl)ethyl]benzamide, and 2-[125I]-N-(N-benzylpiperidin-4-yl)-2-iodobenzamide, were screened for their potential to image human prostate tumors in nude mice bearing human prostate cells (DU-145) xenografts. All three compounds showed a fast clearance from the blood pool and a high uptake and retention in the tumor. Therapeutic potential of nonradioactive PIMBA was studied using in vitro colonogenic assays. A dose-dependent inhibition of cell colony formation was found in two different human prostate cells. These results demonstrate the potential use of sigma receptor binding ligands in non-invasive diagnostic imaging of prostate cancer and its treatment.

The discovery of a series of novel halogenated arylsulfonamides (HAS) as new sigma receptor binding tumor imaging agents is described. Several substituted halogenated sulfonamides have been prepared and characterized. Target compounds were examined for their affinity for sigma1 and sigma2 receptor subtypes using guinea pig brain membranes and rat liver membranes, respectively. A number of substituted halogenated sulfonamides displayed subnanomolar affinities for sigma1 sites and low nanomolar affinities for sigma2 subtype receptors. A limited structure-activity relationship study of this chemical series is discussed. The radioiodination (I-125) of one congener member (4-[125I]iodo-N-[2-(1'-piperidinyl)ethyl]benzenesulfonamide, 4-[125I]IPBS) was accomplished in high yields. The in vitro competition binding studies of 4-[125I]IPBS in guinea pig brain membranes with sigma receptor binding ligands confirmed its sigma pharmacology. The rank order of potency was BD1008 (N-[2-(3, 4-dichlorophenyl)ethyl]-N-methyl-2-(1-pyrrolidinyl)ethylamine) > 4-IPBS > haloperidol > (+)-pentazocine > DTG (1, 3-di-o-tolylguanidine) > (-)-pentazocine. The inhibition constants (IC50) were 0.70, 1.46, 6.28, 10.4, 87.2, and 152 nM, respectively, and are consistent with labeling of sigma1 receptors. The tumor imaging potential of 4-[125I]IPBS was studied in C57 black mice bearing B16 melanoma xenograft. A high tumor uptake of 4-[125I]IPBS was observed (7.40% ID/g) at 1 h postinjection. The wash out of activity from the tumor was slow at 6 h postinjection (7.22% ID/g). The tumor also had the highest amount of radioactivity (1.54% ID/g) at 24 h postinjection. These results demonstrate that radiohalogenated benzenesulfonamides could be a potentially useful class of compounds in nuclear oncologic scintigraphy.