Inorganic phosphorus fractionation and its translocation dynamics in a low-P soil

The translocation of different inorganic phosphorus (Pi) forms in a low-P soil (Langfang experimental station, Hebei province, China) over time was investigated using P fractionation extraction and a (32)P tracer technique. The L-value and P availability of the soil was assessed using 5 different maize genotype (Zea mays L.) cultivars. The results showed that the different Pi fractions in the soil increased in the order of H(2)SO(4)-extractable P (Ca(10)-P) > Na(3)C(6)H(5)O(7)-Na(2)S(2)O(4)-extractable P (O-P) > NH(4)Ac-extractable P (Ca(8)-P) > NaHCO(3)-extractable P (Ca(2)-P), NH(4)F-extractable P (Al-P), NaOH-Na(2)CO(3)-extractable P (Fe-P), and the content of plant-unavailable P (Ca(10)-P + O-P) was high, up to 79.1%, which might be an important reason for P deficiency in this low-P soil. The (32)P tracer results showed that after the addition of (32)P-Pi to the soil with no P fertilizer applied for 25 d, 29.0% of (32)P was quickly transformed into Ca(2)-P (rapidly available P), and 66.1% of (32)P was transformed into Al-P, Fe-P and Ca(8)-P (slowly available P). Only 5.0% of (32)P was transformed into O-P and Ca(10)-P (plant-unavailable P). Moreover, in the soil with P fertilizer applied, (32)P transformation into Ca(2)-P increased, and the transformation into Ca(8)-P + Fe-P + AL-P and O-P, Ca(10)-P significantly decreased compared to the soil with no P fertilizer applied (p < 0.05). This result suggested a higher rate for water-soluble P transformation to slowly available and plant-unavailable P in P deficient soil than in soil with sufficient P. The results of maize L-value determination showed that different genotype maize cultivars had different soil P-use efficiency and low-P tolerance mechanisms. Low-P tolerant cultivar DSY-32 regulated soil P-use efficiency and plant P content according to exogenous P fertilizer application. However, another low-P tolerant cultivar, DSY-2, used soil P more efficiently, regardless of the application of exogenous P.

Mass measurements of the neutron-deficient 41Ti, 45Cr, 49Fe, and 53Ni nuclides: first test of the isobaric multiplet mass equation in f p-shell nuclei

Isochronous mass spectrometry has been applied to neutron-deficient 58Ni projectile fragments at the HIRFL-CSR facility in Lanzhou, China. Masses of a series of short-lived T(z)=-3/2 nuclides including 41Ti, 45Cr, 49Fe, and 53Ni have been measured with a precision of 20-40 keV. The new data enable us to test for the first time the isobaric multiplet mass equation (IMME) in fp-shell nuclei. We observe that the IMME is inconsistent with the generally accepted quadratic form for the A=53, T=3/2 quartet. We perform full space shell model calculations and compare them with the new experimental results.

Do cultural and linguistic competence matter in Latinos' completion of mandated substance abuse treatment?

BACKGROUND

Increasing evidence suggests that culturally and linguistically responsive programs may improve substance abuse treatment outcomes among Latinos. However, little is known about whether individual practices or culturally and linguistically responsive contexts support efforts by first-time Latino clients to successfully complete mandated treatment.

METHODS

We analyzed client and program data from publicly funded treatment programs contracted through the criminal justice system in California. A sample of 5,150 first-time Latino clients nested within 48 treatment programs was analyzed using multilevel logistic regressions.

RESULTS

Outpatient treatment, homelessness, and a high frequency of drug use at intake were associated with decreased odds of treatment completion among Latinos. Programs that routinely offered a culturally and linguistically responsive practice-namely, Spanish-language translation-were associated with increased odds of completion of mandated treatment.

CONCLUSIONS

These preliminary findings suggest that concrete practices such as offering Spanish translation improve treatment adherence within a population that is at high risk of treatment dropout.

Abstract 1800: Targeted therapy using saracatinib adjunctive to castration inhibits progression to castration-resistant prostate cancer in a murine model

Introduction: Prostate cancer treatment with androgen deprivation is typically efficacious for two years prior to the development of castration resistant disease (CRPC). The Src family kinases (SFK) are upregulated with androgen deprivation and have been implicated in the progression to CRPC. Saracatinib is a specific SFK inhibitor that inhibits castration resistant growth and metastases in an animal model using LNCaP cells overexpressing the neuropeptide gastrin-releasing peptide. We test the hypothesis that saracatinib given immediately after androgen deprivation inhibits castration resistant tumor recurrence using a CWR22 xenograft model. Materials and Methods: CWR22 prostate cancer xenografts were injected subcutaneously into nude mice primed with testosterone pellets (21-day release). Twenty-six mice were castrated after adequate tumor development (day 0). Mice in the treatment arm were administered saracatinib from day 7 to day 150. Mice were sacrificed at days 0, 3, 30 and 150. Tumors and sera were collected for analysis including tumor weight, serum testosterone, serum PSA and gene-profile studies. The data was analyzed using the t-test and analysis of variance. Results: CRPC recurrence was significantly inhibited with the administration of saracatinib. The mean weight of tumor recurrence was 0.18 grams with saracatinib compared to 3.20 grams in the control group (p=0.015). Saracatinib was associated with a reduction in serum PSA (1.6 versus 14.7 ng/dl) and testosterone (21.1 versus 24.1 pg/ml) compared to controls, though statistical significance was not reached (p=0.08 and p=0.63, respectively). Gene expression of signaling kinases and their downstream olecules including Src, Etk, FAK, JAK, Stat3, c-myc, β-catenin, NF-κB, Akt, and mTOR is being compared between time points. Conclusions: Saracatinib significantly inhibits castration resistant tumor recurrence when started with androgen deprivation. Additional investigation into the genetic and molecular changes induced by saracatinib with gene microarray and polymerase chain reaction is ongoing. Saracatinib may have a role in combination with androgen deprivation to delay the onset of castration resistant disease.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1800. doi:1538-7445.AM2012-1800

Autophagy Blockade Sensitizes Prostate Cancer Cells towards Src Family Kinase Inhibitors

There is overwhelming evidence that tyrosine kinases play an important role in cancer development. As a prototype of targeted therapy, tyrosine kinase inhibitors are now successfully applied to cancer treatment. However, as single agents, tyrosine kinase inhibitors have not achieved satisfactory results in the treatment of prostate cancer, principally due to their inability to efficiently kill tumor cells. The authors' laboratory has been interested in the role of the Src complex in prostate cancer progression, including the induction of androgen independence and metastasis. Previously, the authors reported that Src inhibitors such as saracatinib and PP2 caused G1 growth arrest and diminished invasiveness in prostate cancer cells but rarely apoptosis. Here, they have shown that Src family kinase (SFK) inhibitors can induce a high level of autophagy, which protects treated cells from undergoing apoptosis. Src siRNA knockdown experiments confirmed that autophagy was indeed caused by the lack of Src activity. The SFK inhibitor-induced autophagy is accompanied by the inhibition of the PI3K (type I)/Akt/mTOR signaling pathway. To test whether autophagy blockade could lead to enhanced cell death, pharmacological inhibitors (3-methyladenine and chloroquine) and a genetic inhibitor (siRNA targeting Atg7) were used in combination with SFK inhibitors. The results showed that autophagy inhibition effectively enhanced cell killing induced by SFK inhibitors. Importantly, the authors showed that a combination of saracatinib with chloroquine in mice significantly reduced prostate cancer (PC3) xenograft growth compared with the control group. Taken together, these data suggest that (1) autophagy serves a protective role in SFK inhibitor-mediated cell killing, and (2) clinically acceptable autophagy modulators may be used beneficially as adjunctive therapeutic agents for SFK inhibitors.

Simultaneous targeting of Src kinase and receptor tyrosine kinase results in synergistic inhibition of renal cell carcinoma proliferation and migration

There have been recent improvements in the treatment for metastatic renal cell carcinoma (RCC) with receptor tyrosine kinase (RTK) inhibitors being one of newer treatment options. We hypothesized that simultaneous targeting of Src kinase and the RTK may have synergistic effects to further improve therapies on metastatic RCC. The effects of Src kinase inhibitor saracatinib and multiple RTK inhibitor sunitinib on RCC cell line (ACHN) and Caki-1 were studied. Saracatinib alone or in combination with sunitinib inhibited the migration of ACHN and Caki-1 cells in vitro. Activation of migration related components FAK, P130Cas and Paxillin were blocked by saracatinib at 0.05- to 3-μM concentrations. Combined treatment resulted in improved growth inhibition, greater loss of the S phase cell population and decreased clonogenic colony formation compared to sunitinib alone in the metastatic Caki-1 line. Molecular studies in Caki-1 showed that saracatinib alone and in combination with sunitinib inhibited phosphorylation of the cell progression regulator c-Myc in a dose-dependent manner. Sunitinib alone or in combination suppressed cyclin-D1 expression with the combination showing greater dose-dependent effect. Sunitinib inhibited vascular endothelial growth factor (VEGF) secretion through the inhibition of STAT3 signaling and VEGF biosynthesis. HIF1-α expression in normoxic and hypoxic conditions in Caki-1 cells was inhibited by either saracatinib or sunitinib when administered alone, however, a greater reduction occurred when these compounds were given in combination. Targeting Src kinase and RTK simultaneously with saracatinib and sunitinib resulted in 70-80% blockade of RCC cell migration, synergistic inhibition of cell growth and reduction of acquired drug resistance in Caki-1 cells. The results show promise for combination targeted therapy of RCC.

Abstract 359: Neuropeptides promote castration-resistant prostate cancer through intracrine androgen biosynthesis

Introduction and Objectives: Neuroendocrine differentiation is associated with castration resistant prostate cancer (CRPC) with detectable increased serum levels of chromogranin A in patients. Neuropeptides secreted from the neuroendocrine cells are believed to activate androgen receptor (AR) in low or no androgen environments. We hypothesize that neuropeptides sustain CRPC by promoting intracrine androgen synthesis.

Methods: We engineered LNCaP cells overexpressing gastrin-releasing peptide (GRP) and examined the level of androgen biosynthetic enzymes by RT-PCR and Western blots. Inhibition of androgen-free growth of LNCaP-GRP cells was performed with siRNA to AKR1C3 or CYP17A1 with or without Src inhibitor saracatinib. PSA and total testosterone levels were assessed in LNCaP-GRP cells, serum from tumor-bearing animals and xenografts.

Results: The androgen biosynthetic enzymes were up-regulated in LNCaP-GRP cells, with AKR1C3, CYP17A1 and HSD17B2 displaying over 40 fold increase compared to the control line by real-time RT-PCR analysis. Transfection of siRNA against AKR1C3 and CYP17A1 inhibited LNCaP-GRP cell growth in androgen-free medium. Specific Src family kinase inhibitor saracatinib inhibits androgen-independent LNCaP-GRP cell growth in vitro and tumor metastasis in vivo. Saracatinib also reduced the expression of AKR1C3, AKR1C1/2 and HSD3B1/2 in GRP cells at both RNA and protein levels. When combined with siRNA for AKR1C3 and CYP17A1, saracatinib further inhibited androgen-independent LNCaP-GRP cell growth. Testosterone was detectable by EIA assay in LNCaP-GRP cell lysates (109.1 and 44.5 pg/mg protein vs. 18.3 in control), serum from castrated mice bearing GRP tumors (2235.5 pg/ml serum) and xenograft tissue (59.2 pg/mg tumor). These enhanced T levels were greatly reduced when treated with saracatinib, to 594 pg/ml serum and 12 pg/mg tumor, respectively.

Conclusions: Secretion of neuropeptides promotes CRPC through up-regulation of intracrine androgen biosynthesis. Saracatinib not only targets neuropeptide-mediated AR activation but also blocks steroidogenesis in CRPC.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 359. doi:10.1158/1538-7445.AM2011-359

Direct mass measurements of short-lived A=2Z-1 nuclides (63)Ge, (65)As, (67)Se, and (71)Kr and their impact on nucleosynthesis in the rp process

Mass excesses of short-lived A=2Z-1 nuclei (63)Ge, (65)As, (67)Se, and (71)Kr have been directly measured to be -46,921(37), -46,937(85), -46,580(67), and -46,320(141)  keV, respectively. The deduced proton separation energy of -90(85)  keV for (65)As shows that this nucleus is only slightly proton unbound. X-ray burst model calculations with the new mass excess of (65)As suggest that the majority of the reaction flow passes through (64)Ge via proton capture, indicating that (64)Ge is not a significant rp-process waiting point.

Assessment of soil contamination with Cd, Pb and Zn and source identification in the area around the Huludao Zinc Plant

The distribution characteristics of heavy metals (cadmium (Cd), lead (Pb) and zinc (Zn)) in the natural soil profiles around the Huludao Zinc Plant (HZP), an old industrial base in Northeast China, were analyzed. The pollutant source was identified using (210)Pb isotope technique to evaluate the geochemical characteristics of Pb and the historical production records of HZP. The results indicated: dust precipitation from HZP was the primary source of the pollutants. The average deposition rates of Cd, Pb and Zn were 0.33, 1.75, and 30.97 g/m(2)year, respectively at 1 km away after HZP, and 0.0048, 0.035, and 0.20 g/m(2) year, respectively at 10 km away after HZP. There is a risk of secondary pollution to the environment as well as the food chain in seriously polluted areas used for cultivation.

Effect of the specific Src family kinase inhibitor saracatinib on osteolytic lesions using the PC-3 bone model

The hematogenous metastatic spread of prostate cancer is preferentially to bone and can result in significant patient morbidity. Although these metastatic lesions are typically osteoblastic, bone resorption is believed to have a prerequisite role in their development. Src kinase has been identified to contribute to prostate cancer tumor growth and metastasis. In addition, Src is also essential in bone metabolism, especially in bone resorption. We hypothesized that inhibiting Src activity with the specific Src family kinase inhibitor saracatinib (AZD0530) would inhibit tumor cell growth and osteoclast differentiation in the tumor-bone interface, thus providing a new approach for advanced prostate cancer. We found that saracatinib inhibited PC-3 cell growth and invasion in a dose-dependent manner. Phosphorylation of Src, focal adhesion kinase, and P38 kinases was inhibited by saracatinib at the submicromolar range. Saracatinib also inhibited the expression and secretion of invasion-related molecules interlukin-8, urokinase-type plasminogen activator, and matrix metalloprotease-9. Receptor activator of NF-kappaB ligand (RANKL)-induced osteoclastogenesis and signaling were inhibited by saracatinib in both macrophages and PC-3 cells. In in vivo studies, control mice developed more severe osteolytic lesions compared with the treatment group. Immunohistochemical and biochemical assays of bone metabolites confirmed that saracatinib preserved bone architecture in the presence of prostate cancer tumor cells. In summary, we have shown the inhibition of PC3 cell growth and invasion by saracatinib. Src inhibition also blocked the RANKL stimulatory pathway in osteoclasts and PC3 cells. The inhibition of Src thus targets multiple sites involved in prostate cancer bone metastasis, which may offer a therapeutic advantage in treating advanced prostate cancer.

Abstract 4684: Autophagy blockade sensitizes prostate cancer cells towards Src family kinase inhibitors

There is overwhelming evidence that tyrosine kinases play an important role in cancer development. As a prototype of targeted therapy, tyrosine kinase inhibitors are now successfully applied to cancer treatment. However, as single agents, tyrosine kinase inhibitors have not achieved satisfactory results in the treatment of prostate cancer, principally due to their inability to efficiently kill tumor cells. Our lab has been interested in the role of the Src complex in prostate cancer progression including the induction of androgen independence and metastasis. Previously, we reported that Src inhibitors such as saracatinib and PP2 caused G1 growth arrest and diminished invasiveness in prostate cancer cells, but rarely apoptosis. Here, we have shown that Src family kinase (SFK) inhibitors can induce a high level of autophagy, which protects treated cells from undergoing apoptosis. Src siRNA knockdown experiments confirmed that autophagy was indeed caused by the lack of Src activity. The SFK inhibitor-induced autophagy is accompanied by the inhibition of PI3K (type I)/Akt/mTOR signaling pathway. To test whether autophagy blockade could lead to enhanced cell death, pharmacological inhibitors (3-methyladenine and chloroquine) and a genetic inhibitor (siRNA targeting Atg7) were used in combination with SFK inhibitors. The results showed that autophagy inhibition effectively enhanced cell killing induced by SFK inhibitors. Importantly, we showed a combination of saracatinib with chloroquine in mice significantly reduced prostate cancer (PC3) xenograft growth, compared with the control group. Taken together, these data suggest that 1) autophagy serves a protective role in SFK inhibitor-mediated cell killing; 2) clinically acceptable autophagy modulators may be used beneficially as adjunctive therapeutic agents for SFK inhibitors.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4684.

A single nucleotide polymorphism and sequence analysis of CSN1S1 gene promoter region in Chinese Bos grunniens (yak)

The aim of this study was to investigate the polymorphism of the CSN1S1 gene promoter region in 4 Chinese yak breeds, and compare the yak CSN1S1 gene promoter region sequences with other ruminants. A Polymerase Chain Reaction-Single Strand Conformation Polymorphism protocol was developed for rapid genotyping of the yak CSN1S1 gene. One hundred fifty-eight animals from 4 Chinese yak breeds were genotyped at the CSN1S1 locus using the protocol developed. A single nucleotide polymorphism of the CSN1S1 gene promoter region has been identified in all yak breeds investigated. The polymorphism consists of a single nucleotide substitution G-->A at position 386 of the CSN1S1 gene promoter region, resulting in two alleles named, respectively, G(386) and A(386), based on the nucleotide at position 386. The allele G(386) was found to be more common in the animals investigated. The corresponding nucleotide sequences in GenBank of yak (having the same nucleotides as allele G(386) in this study), bovine, water buffalo, sheep, and goat had similarity of 99.68%, 99.35%, 97.42%, 95.14%, and 94.19%, respectively, with the yak allele A(386.).

Interleukin-6 regulates androgen synthesis in prostate cancer cells

PURPOSE

The standard systemic treatment for prostate cancer patients is androgen deprivation therapy. Although serum testosterone concentrations were significantly reduced after androgen deprivation therapy, levels of intraprostatic androgens are reproducibly measured at concentrations sufficient to activate androgen receptor and stimulate tumor growth, suggesting that prostate cancer cells may survive androgen deprivation therapies by increasing intracrine androgen synthesis within the prostate. However, factors that regulate de novo intracrine androgen synthesis have not been identified. Interleukin-6 (IL-6) has been implicated in the modulation of androgen receptor activation and growth and differentiation in prostate cancer. In this study, we investigate whether IL-6 regulates intraprostatic androgen synthesis in prostate cancer cells.

EXPERIMENTAL DESIGN

Quantitative reverse transcription-PCR and Western blotting were done to detect expression levels of steroidogenic enzymes. AKR1C3 promoter reporter was constructed and analyzed for IL-6-mediated AKR1C3 transcriptional activity. IL-6-mediated signaling was knocked down using small interfering RNA specific to IL-6 receptor and gp130, and the effect on AKR1C3 expression was examined. Intraprostatic androgen levels in prostate cancer cells in culture and in tumors were measured by an enzyme immunoassay (Testosterone EIA kit).

RESULTS

We found that IL-6 increases the expression of genes encoding many steroidogenic enzymes, including HSD3B2 and AKR1C3, involved in androgen biosynthesis. Down-regulation of IL-6 receptor and gp130 expression using specific small interfering RNA abolished IL-6-mediated AKR1C3 expression, suggesting that IL-6 signaling is responsible for AKR1C3 expression. IL-6 increases AKR1C3 promoter activity, indicating that the increase in IL-6-mediated AKR1C3 expression is in part at the transcriptional level. Treatment of IL-6 increased testosterone level in LNCaP cells. The tumor testosterone levels were detected at 378 pg/g in tumors generated from IL-6-overexpressing LNCaP-IL6(+) cells inoculated orthotopically into the prostates of castrated male nude mice.

CONCLUSIONS

These results suggest that IL-6 increases levels of intracrine androgens through enhanced expression of genes mediating androgen metabolism in prostate cancer cells.

Rapid detection of bovine milk in yak milk using a polymerase chain reaction technique

Yak milk contains a greater percentage of protein and has better quality than bovine milk. There has been an increasing focus on yak milk and milk products during the last few years. In the present study, a PCR-based assay was developed for the specific identification of bovine milk in yak milk by designing 3 primers targeting the mitochondrial ND1 gene. The use of 3 primers in a single PCR reaction set yielded 2 amplification fragments of 293 and 190 bp from bovine milk DNA, whereas only 1 amplification fragment of 293 bp was obtained in yak milk DNA. The technique was applied to raw and heat-treated binary mixtures of yak and bovine milks and enabled the specific detection of bovine milk with a detection limit of 0.1%. The assay developed is sensitive, fast, and straightforward, and it might be useful in the quality control of yak milk and milk products.

Aberrant activation of androgen receptor in a new neuropeptide-autocrine model of androgen-insensitive prostate cancer

Treatment of advanced prostate cancer with androgen deprivation therapy inevitably renders the tumors castration-resistant and incurable. Under these conditions, neuroendocrine differentiation of prostate cancer (CaP) cells is often detected and neuropeptides released by these cells may facilitate the development of androgen independence. Exemplified by gastrin-releasing peptide (GRP), these neuropeptides transmit their signals through G protein-coupled receptors, which are often overexpressed in prostate cancer, and aberrantly activate androgen receptor (AR) in the absence of androgen. We developed an autocrine neuropeptide model by overexpressing GRP in LNCaP cells and the resultant cell line, LNCaP-GRP, exhibited androgen-independent growth with enhanced motility in vitro. When orthotopically implanted in castrated nude mice, LNCaP-GRP produced aggressive tumors, which express GRP, prostate-specific antigen, and nuclear-localized AR. Chromatin immunoprecipitation studies of LNCaP-GRP clones suggest that GRP activates and recruits AR to the cognate promoter in the absence of androgen. A Src family kinase (SFK) inhibitor, AZD0530, inhibits androgen-independent growth and migration of the GRP-expressing cell lines, and blocks the nuclear translocation of AR, indicating the involvement of SFK in the aberrant activation of AR and demonstrating the potential use of SFK inhibitor in the treatment of castration-resistant CaP. In vivo studies have shown that AZD0530 profoundly inhibits tumor metastasis in severe combined immunodeficient mice implanted with GRP-autocrine LNCaP cells. This xenograft model shows autocrine, neuropeptide- and Src kinase-mediated progression of androgen-independent CaP postcastration, and is potentially useful for testing novel therapeutic agents.

N-ethoxybenzylimidazoles: a novel acid-sensitive linker for controlled release of therapeutics from drug delivery systems

Abstract #2156

Background:&#x2028; Drug delivery systems (DDS) are useful for cancer therapies because they can target tumors and cancer cells more specifically than cancer therapeutics alone. An important component of a DDS is the triggering mechanism for drug release. This presentation will highlight a new class of N-linked imidazoles as potential acid-sensitive cleavable linkers for use in cancer DDSs. These acid-sensitive linkers are designed to exploit the lower extracellular pH of some tumors and the endosomes and lysosomes within cells to trigger the controlled release of therapeutic agents from drug delivery vessels. Cleavage of N-ethoxybenzylimidazoles (NEBIs) exhibit a 10-fold increase in the rate of hydrolysis in mild aqueous acidic solutions (at pH = 5.5) compared to solutions at normal, physiological pH. The rate of hydrolysis can be tuned to range from minutes to months through the addition of electron donating or withdrawing groups.&#x2028; The NEBI linker can be used to conjugate a cytotoxic agent to a carrier. Carriers for this DDS include molecules such as tumor specific antibodies, polymers/nanoparticles, peptides, and ligands, that can target cancer cells or accumulate around tumors. Cytotoxic agents include FDA approved small molecules and chemotherapeutics.&#x2028; Methods and Materials:&#x2028; The NEBI was developed into a bifunctional crosslinker containing a carboxylic acid and an azide for conjugation of cancer therapeutics to carriers. For simplicity, we used Human Serum Albumin (HSA) as our model carrier and doxorubicin as our model cytotoxic agent. The NEBI was conjugated to doxorubicin through a simple amide coupling. The NEBI was then conjugated to an alkyne containing HSA via “Click Chemistry.”&#x2028; Results:&#x2028; We were able to load approximately 1-2 doxorubicin molecules per HSA. Imaging studies have shown that our HSA conjugates to doxorubicin via a NEBI linker (HSA-NEBI-dox) localize in lysosomes. Cytotoxicity studies show HSA-NEBI-dox is cytotoxic while HSA conjugates to doxorubicin via a stable linkage is not.&#x2028; Discussion:&#x2028; We were able to develop methods for conjugating doxorubicin to HSA. The techniques used here can be applied to conjugate other carriers and other cancer therapeutics. We will continue to develop the NEBI linker and demonstrate how the linker can be used to conjugate trastuzumab to doxorubicin. We chose use trastuzumab, a monoclonal antibody, as a carrier because it is known to bind to the HER2 receptor. HER2 is over expressed in 25%-30% of breast cancers. Trastuzumab not only targets cancer cells that are over expressing the HER2 receptor, but binding of trastuzumab to the HER2 receptor can trigger receptor mediated endocytosis, which can lead to controlled release of doxorubicin within the cell.&#x2028; &#x2028;

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 2156.

Src family kinase oncogenic potential and pathways in prostate cancer as revealed by AZD0530

Prostate cancer is the most frequently diagnosed cancer in American men. We have previously demonstrated that Src mediates androgen-independent proliferation in prostate cancer. We sought to investigate the Src-mediated oncogenic pathways and tumor biology using AZD0530, a novel Src family kinase/Abl dual-kinase inhibitor that is entering phase II clinical trials. We show that while both Src and Abl are expressed in all prostate cancer cell lines, Src but not Abl is activated in the prostate. Furthermore, Src activation is inhibited by AZD0530 in a rapid and dose-dependent manner. We show that Src mediates cell proliferation in DU145 and PC3 cells at the G1 phase of cell cycle. Src inhibition resulted in decreased binding of beta-catenin to the promoters of G1 phase cell cycle regulators cyclin D1 and c-Myc. C-Myc may also be regulated at the protein level by extracellular signal-regulated kinase 1/2 and GSK3beta. Cell motility factors focal adhesion kinase, p130CAS and paxillin activation in DU145 and PC3 cells were also inhibited. Administration of AZD0530 in mice reduced orthotopic DU145 xenograft growth by 45%. We have further delineated the Src-mediated oncogenic growth and migration pathways in prostate cancer and established mechanistic rationale for Src inhibition as novel therapy in the treatment of prostate cancer.

Effects of external phosphorus on the cell ultrastructure and the chlorophyll content of maize under cadmium and zinc stress

Using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis, it was found that the ultrastructure of chloroplasts were changed, the shape of the chloroplasts altered and the numbers of grana that were asymmetrical increased; the numbers of grana and thylakoids decreased under the stress of Cd and Zn. The results indicated that the complex pollution involving Cd and Zn resulted in the membrane system of chloroplasts being damaged. When external phosphorus was applied, the numbers of damaged chloroplasts were significantly reduced and the nucleoli were better formed than those that did not receive phosphorus treatment. Moreover, many phosphate deposits were found in the vacuoles and on the surface of the roots, which were formed by phosphorus complexing with Cd (K(sp)=2.53x10(-33)) and Zn (K(sp)=9.00x10(-33)), respectively. Treatment with phosphorus conduced an increased chlorophyll content in plants compared with those that did not receive external phosphorus.