Engineering dynamics of growth factors and other therapeutic ligands

Peptide growth factors and other receptor-binding cytokine ligands are of interest in contemporary molecular health care approaches in applications such as wound healing, tissue regeneration, and gene therapy. Development of effective technologies based on operation of these regulatory molecules requires an ability to deliver the ligands to target cells in a reliable and well-characterizable manner. Quantitative information concerning the fate of peptide ligands within tissues is necessary for adequate interpretation of experimental observations at the tissue level and for truly rational engineering design of ligand-based therapies. To address this need, we are undertaking efforts to elucidate effects of key molecular and cellular parameters on temporal and spatial distribution of cytokines in cell population and cell/matrix systems. In this article we summarize some of our recent findings on dynamics of growth factor depletion by cellular endocytic trafficking, growth factor transport through cellular matrices, and growth factor production and release by autocrine cell systems. (c) 1996 John Wiley & Sons, Inc.

OT1-02-05: A Phase III Clinical Trial Comparing Trastuzumab Given Concurrently with Radiation Therapy to Radiation Therapy (RT) Alone for Women with HER2−Positive DCIS Resected by Lumpectomy: NSABP B-43

Background

Because a substantial portion of DCIS is ER negative and overexpresses HER2, therapy targeting this protein is a promising strategy for HER2−overexpressing DCIS.

Preclinical studies have shown that trastuzumab (T) boosts the effectiveness of RT in xenograft models and in cell lines with no detrimental effect on irradiated HER2−normal cells. Studies correlating clinical response with molecular markers in T-treated patients show that apoptosis occurs within 1 wk of starting singleagent T, with little effect on proliferation. Shorter duration treatments with this agent require investigation. Adjuvant trials using T during breast irradiation have already provided ample safety evidence. Will T administered during WBI improve lumpectomy + WBI results in women with HER2−positive DCIS? This trial will allow us to better understand the biology of breast cancer and its prevention and will extend the benefits of breast-conserving surgery for women with DCIS.

Trial Design: Post lumpectomy for DCIS without evidence of an invasive component, a central review of each patient's pure DCIS lesion is carried out for HER2 by IHC analysis. If the HER2 is 2+, FISH analysis is done, and patients whose tumors are HER2 3+ or FISH positive can be randomly assigned to receive 2 doses of T 3 wk apart during WBI or to receive WBI alone.

Eligibility criteria: Women 18 years or older with an ECOG status of 0 or 1 who have undergone a margin-clear lumpectomy for DCIS and whose tumors are clinically or pathologically node negative are eligible. DCIS must be HER2 positive by central testing. ER and/or PR status must be known before random assignment.

Specific aims: The primary aim is to determine if T given concurrently with WBI is more beneficial in preventing IBC recurrence, ipsilateral skin cancer recurrence, or ipsilateral DCIS compared with WBI alone for HER2−positive DCIS resected by lumpectomy. Secondary aims are to compare the possible benefit of T given during WBI to that of WBI alone in preventing regional or distant recurrence and contralateral invasive or DCIS breast cancer. B-43 will determine if invasive or DCIS DFS, recurrence-free interval, and OS can be improved with the addition of T to WBI. The effects of T on ovarian function in premenopausal women will also be assessed.

Statistical methods and accrual: Our design calls for accrual of 2000 patients during a 7.9-year period. As of May 31, 2011, 578 patients have been entered. A definitive analysis of primary endpoints will be performed when 163 ipsilateral breast cancer events occur (7.5 and 8 years after protocol initiation). This number of events affords 80% power to detect a hazard reduction of 36%, from 1.73 ipsilateral breast cancer events per 100 patient-years to 1.11 events per 100 patient-years. The 36% observed reduction in the hazard of IIBCR-SCR-DCIS on the T arm is based on a projection of 40% hazard reduction if the compliance were perfect, with a 10% noncompliance rate.

Supported by PHS grants NCI-U10-CA-69651, NCI-U10-CA-12027, and NCI P30-CA-14599 from the US NCI and Genentech, Inc.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr OT1-02-05.

Endocytic Relay as a Potential Means for Enhancing Ligand Transport through Cellular Tissue Matrices: Analysis and Possible Implications for Drug Delivery

The transport of peptide ligands, such as cytokines, through tissue is complicated by resistances due to cell multilayers and holdup in extracellular matrix. To determine whether it is possible for receptor-mediated endocytic trafficking to enhance ligand transport, we have developed a mathematical model of ligand flux through tissue containing cells possessing complementary receptors. Tissue is considered as two phases: the cell phase and the matrix phase; thus tissue is modeled as analogous to a packed bed reactor. This model allows calculation of steady-state flux of intact and degraded peptide through a one-dimensional cell/tissue matrix. Both environmental and molecular parameters were considered in this study. Results predict that three quantities should have a major influence on growth factor flux: the ratio of matrix diffusivity to intracellular "diffusivity" (D(m)/D(i)), the extracellular matrix proteolysis rate constant (k (prot)), and the fraction of internalized growth factor degraded (f(1)). For basal levels of intracellular degradation (0 < f(1) >/= 0.05) but no extracellular proteolysis, significant enhancement is possible only for D(m)/D(i) >/=1. f(1) increases, enhancement is only possible up to f(1)= 0.07 even for D(m)/D(i) < 1. For significant levels of extracellular proteolysis (k (prot) > 0), the requirements for D(m)/D(i) and f(1) to permit transport enhancement encompass a broader range with the exact values dependent on k (prot). These insights may be helpful for delivery of ligands generated from controlled-release devices or genetically modified autocrine cells, and may also provide better understanding of cytokine transport in embryonic development.

Systemic inflammatory responses in progressing periodontitis during pregnancy in a baboon model

This study tested the hypothesis that pregnant female baboons exhibit increased levels of various inflammatory mediators in serum resulting from ligature-induced periodontitis, and that these profiles would relate to periodontal disease severity/extent in the animals. The animals were sampled at baseline (B), mid-pregnancy (MP; two quadrants ligated) and at delivery (D; four quadrants ligated). All baboons developed increased plaque, gingival inflammation and bleeding, pocket depths and attachment loss following placement of the ligatures. By MP, both prostaglandin E(2) (PGE(2)) and bactericidal permeability inducing factor (BPI) were greater than baseline, while increased levels of interleukin (IL)-6 occurred in the experimental animals by the time of delivery. IL-8, MCP-1 and LBP all decreased from baseline through the ligation phase of the study. Stratification of the animals by baseline clinical presentation demonstrated that PGE(2), LBP, IL-8 and MCP-1 levels were altered throughout the ligation interval, irrespective of baseline clinical values. IL-6, IL-8 and LBP were significantly lower in the subset of animals that demonstrated the least clinical response to ligation, indicative of progressing periodontal disease. PGE(2), macrophage chemotactic protein (MCP)-1, regulated upon activation, normal T cell expressed and secreted (RANTES) and LBP were decreased in the most diseased subset of animals at delivery. Systemic antibody responses to Fusobacterium nucleatum, Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans and Campylobacter rectus were associated most frequently with variations in inflammatory mediator levels. These results provide a profile of systemic inflammatory mediators during ligature-induced periodontitis in pregnant baboons. The relationship of the oral clinical parameters to systemic inflammatory responses is consistent with a contribution to adverse pregnancy outcomes in a subset of the animals.

Micrqporous Silica Gels from Alkylsilicate-Water Two Phase Hydrolysis

Microporous silica gels have been synthesized through a nano-particulate sol-gel route. These gels have uniformly distributed and extremely small pores(< 15Â in diameter). Hydrolysis and condensation reactions leading to these gels were carried out in an alkyl silicate-water (ammonia) two phase system. These reactions took place at the alkyl silicate droplet-water interfacial boundary. No alcohol was added. A clear, stable and uniformly distributed colloidal silica suspension having an average particle size less than 6 nm was prepared by this method. Fast hydrolysis, slow condensation and low solubility all contribute to a high supersaturation level and result in the formation of small particles. This process is consistent with classic nucleation theory. When the particles are produced under acidic rather than under basic reaction conditions, smaller particles are formed due to the slower condensation rate and lower solubility of these silica particles in acidic conditions. At the same pH, alkylsilicates having smaller alkyl groups react faster with water leading to smaller primary particles. Homogeneous nucleation conditions are achieved when the water/alkylsilicate ratio is high.

Survival by anatomic site, histologic type, and tumor stage in stomach and esophageal cancer patients from the U.S. SEER Cancer Registry

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Background: Data on the association of tumor characteristics and survival for stomach cancer (SC) and esophageal cancer (EC) patients (pts) are limited. The objective of this study was to describe survival in United States. SC and EC pts by anatomic site, histologic type, and tumor stage.

Methods: SC and EC pts were identified in the Surveillance, Epidemiology and End Results (SEER) Cancer Registry. SC was classified by anatomic site (cardia and non-cardia/other) and histologic type (intestinal, diffuse, other per Lauren criteria). EC was classified into anatomic site (middle/upper third, abdominal/lower third, overlapping lesions, NOS) and histologic type (adenocarcinoma (AC), squamous cell carcinoma (SQ), other). Frequency distribution and median survival were examined in these subgroups.

Results: From 2004-2006, >15,500 SC and > 9,800 EC cases were diagnosed. SC: (29% cardia) and (24% diffuse, 66% intestinal, 10% other). Compared with non-cardia/other pts, cardia pts tended to be male (77% vs 56%), white (88% vs 66%), intestinal type (77% vs 61%) and present with earlier stage disease (stage I-IIIa: 48% vs 42%). With the exception of stage I/II pts, survival was longer in cardia than non-cardia/other pts. The difference was most striking in stage IIIb/IV pts (7 months (mos) cardia vs 4 mos non-cardia/other). Compared to intestinal type, diffuse type tended to be younger (median age: 64 vs 72 yrs), more female (49% vs 34%), and present with more stage IIIb/IV disease (50% vs 39%). No difference in survival by histologic type was observed when accounting for stage. EC: (26% middle/upper, 58% lower, 5% overlapping, 11% NOS) and (57% AC, 34% SQ, 9% other). Among pts with AC histology 78% occurred in the lower third; in SQ most occurred in upper/middle third (56%). Compared to SQ, AC tended to be male (85% vs 63%), white (95% vs 67%), and present with stage IV disease (34% vs 25%). For all stages combined, survival was longer for AC pts (11 mos AC, 9 mos SQ, 4 mos other). This difference was most apparent among early stage (I-III) pts.

Conclusions: Survival in SC and EC was associated with staging, anatomic and histologic subtypes. Quantifying this provides insights for the design and interpretation of clinical development programs.

[Table: see text]

Immunotherapy of melanoma by GPI-anchored IL-21 tumour vaccine involves down-regulating regulatory T cells in mouse model

In this study, we developed a tumour cell vaccine expressing a glycosylphosphatidylinositol (GPI)-anchored IL-21 to test the effect of immunotherapy of melanoma in mouse model. The results indicated that the tumour vaccine was functional, exhibiting delayed tumour growth and prolonging longevity of tumour bearing mice. The immunotherapeutic effect was associated with decreasing the numbers of CD4(+) CD25(+) Foxp3(+) Treg (Tregs) cells, increasing IFN-γ level and promoting lymphocyte-infiltration in tumour tissues. Overall, our data demonstrate that the GPI-anchored IL-21 tumour vaccine regulates immune responses at least in part by down-regulating Tregs and reveals enhanced efficacy of tumour vaccine therapy of melanoma.

Identification of tumor stem-like cells in a mouse myeloma cell line

We used colony formation assay in the soft agar media or the serum-free media, the methods of identifying BrdU-label-retaining cells and the SP cells as well as the tumorigenicity test in BALB/c mice, respectively, to analyze tumor stem like cells in the SP2/0 cell line. The results showed that a few SP2/0 cells were capable of forming colonies in the soft agar media, contained BrdU-label-immortal strand in the SP2/0 cell line. The SP2/0 cells in the serum-free media gained higher tumorigenicity in the BALB/c mice than the SP2/0 cells cultivated in the complete media did. Overall, only a few of the SP2/0 cells were found to possess the characteristics of tumor stem-like cells, such as high proliferative potency, more self-renewal and stronger tumorigenesis, or greater similarity to the tumor stem cells (TSCs) traits. The biology of tumor stem-like cells contributes to the identification of molecular targets important for future tumor therapy.

Role of Aggregatibacter actinomycetemcomitans in glutathione catabolism

INTRODUCTION

Our previous studies demonstrated that three enzymes, gamma-glutamyltransferase (GGT), cysteinylglycinase (CGase) and cystalysin, are required for the catabolism of glutathione to produce hydrogen sulfide (H(2)S) in Treponema denticola. In this study, we examined glutathione catabolism in Aggregatibacter actinomycetemcomitans.

METHODS

The GGT and CGase of A. actinomycetemcomitans were determined by biological methods and GGT was characterized using a molecular biological approach.

RESULTS

A. actinomycetemcomitans showed GGT and CGase activity, but could not produce H(2)S from glutathione. The addition of recombinant T. denticola cystalysin, an l-cysteine desulfhydrase, to whole cells of A. actinomycetemcomitans resulted in the production of H(2)S from glutathione. Subsequently, we cloned A. actinomycetemcomitans GGT gene (ggt) and overexpressed the 63 kDa GGT protein. The recombinant A. actinomycetemcomitans GGT was purified and identified. The K(cat)/K(m) of the recombinant GGT from N-gamma-l-glutamyl-4-nitroaniline as substrate was 31/microm/min. The activity of GGT was optimum at pH 6.9-7.1 and enhanced by thiol-containing compounds.

CONCLUSION

The results demonstrated that A. actinomycetemcomitans had GGT and CGase activities and that the GGT was characterized. The possible role of A. actinomycetemcomitans in glutathione metabolism and H(2)S production from oral bacteria was discussed.

Circulating natriuretic peptides in cats with heart disease

BACKGROUND

Circulating natriuretic peptide concentrations are increased in cats with myocardial dysfunction.

HYPOTHESIS

Serum N-terminal fragment of proatrial natriuretic peptide (NT-proANP) and NT-probrain natriuretic peptide (proBNP) concentrations may predict the presence of heart disease (HD) and congestive heart failure (CHF). A positive relationship is also predicted among natriuretic peptide (NP) concentrations, a noninvasive estimate of left ventricular filling pressure (E/E(a)), and an echocardiographic measure of left atrial (LA) size (LA/aortic diameter [Ao]).

METHODS

Serum NP concentrations were measured in 28 healthy control and 50 study cats using sandwich enzyme immunoassays. The study group comprised cats, with HD but no CHF (HD - CHF, n = 17) and cats with CHF (HD + CHF, n = 33). The relationship among NP concentrations, LA size, and E/E(a) was examined. The ability of NP to distinguish control from study cats, and HD - CHF from HD + CHF cats, was explored using receiver operator curve analysis.

RESULTS

NP concentrations were significantly lower in control than in study cats (P= .0001). The NT-proBNP concentrations were positively correlated with LA/Ao ratio (rho= 0.34; P= .02) and with E/E(a) ratio (rho= 0.68; P < .05). An NT-proBNP concentration of 49 fmol/mL gave a sensitivity and specificity of 100 and 89.3%, respectively, for correctly distinguishing 96.2% of control from study cats. Pairwise comparisons of the areas under the curve identified a statistically significant difference (P= .011) between NT-proANP and NT-proBNP to distinguish control from study cats. NT-proANP and NT-proBNP concentrations were significantly higher in HD + CHF cats than in HD - CHF cats (P= .0023 and .0001, respectively).

CONCLUSIONS

Serum concentrations of NT-proANP and particularly NT-proBNP were different in healthy control cats, asymptomatic cats with HD, and cats with CHF, suggesting that measurement of NP concentrations may prove clinically useful as an initial screening test for cats with suspected cardiac disease.