Glycogen Synthase Kinase 3β in Pancreatic Cancer and its Implications in Chemotherapy and Radiation Therapy.

Pancreatic cancer is a highly lethal disease with a poor prognosis characterized by local and systemic disease progression. Both radiation and chemotherapy play important roles in the management of this disease. However, in order to improve standard therapy many molecularly targeted agents are being developed.

DCE and DW-MRI monitoring of vascular disruption following VEGF-Trap treatment of a rat glioma model.

Vascular-targeted therapies have shown promise as adjuvant cancer treatment. As these agents undergo clinical evaluation, sensitive imaging biomarkers are needed to assess drug target interaction and treatment response. In this study, dynamic contrast enhanced MRI (DCE-MRI) and diffusion-weighted MRI (DW-MRI) were evaluated for detecting response of intracerebral 9 L gliosarcomas to the antivascular agent VEGF-Trap, a fusion protein designed to bind all forms of Vascular Endothelial Growth Factor-A (VEGF-A) and Placental Growth Factor (PGF).

Synthesis and investigation of a radioiodinated F3 peptide analog as a SPECT tumor imaging radioligand.

A radioiodinated derivative of the tumor-homing F3 peptide, (N-(2-{3-[(125)I]Iodobenzoyl}aminoethyl)maleimide-F3Cys peptide, [(125)I]IBMF3 was developed for investigation as a SPECT tumor imaging radioligand. For this purpose, we custom synthesized a modified F3 peptide analog (F3Cys) incorporating a C-terminal cysteine residue for site-specific attachment of a radioiodinated maleimide conjugating group. Initial proof-of-concept Fluorescence studies conducted with AlexaFluor 532 C(5) maleimide-labeled F3Cys showed distinct membrane and nuclear localization of F3Cys in MDA-MB-435 cells.

Molecular imaging of akt enables early prediction of response to molecular targeted therapy.

Development of noninvasive, real-time molecular imaging tools to assess responsiveness of a given therapy may be a critical component of the success of individualized therapy approach for patients. Toward this, we have previously developed and validated molecular sensors for Akt and caspase-3 activity, and in this report, we have explored the utility of these reporters in assessing the responsiveness of tumors to a combination of gemcitabine (Gem) and cetuximab (Cet) delivered in two opposite schedules. We found that human head and neck cancer (UMSCC1) xenografts responded significantly better in a schedule where cetuximab was administered after gemcitabine when compared with the schedule of cetuximab followed by gemcitabine.

Molecular imaging of c-Met tyrosine kinase activity.

The receptor tyrosine kinase c-Met and its ligand, hepatocyte growth factor/scatter factor (HGF/SF), modulate signaling cascades implicated in cellular proliferation, survival, migration, invasion, and angiogenesis. Therefore, dysregulation of HGF/c-Met signaling can compromise the cellular capacity to moderate these activities and can lead to tumorigenesis, metastasis, and therapeutic resistance in various human malignancies. To facilitate studies investigating HGF/c-Met receptor coupling or c-Met signaling events in real time and in living cells and animals, here we describe a genetically engineered reporter where bioluminescence can be used as a surrogate for c-Met tyrosine kinase activity.

Applications of molecular imaging.

Today molecular imaging technologies play a central role in clinical oncology. The use of imaging techniques in early cancer detection, treatment response, and new therapy development is steadily growing and has already significantly impacted on clinical management of cancer. In this chapter, we overview three different molecular imaging technologies used for the understanding of disease biomarkers, drug development, or monitoring therapeutic outcome.

Targeted imaging and therapy of brain cancer using theranostic nanoparticles.

The past decade has seen momentous development in brain cancer research in terms of novel imaging-assisted surgeries, molecularly targeted drug-based treatment regimens or adjuvant therapies and in our understanding of molecular footprints of initiation and progression of malignancy. However, mortality due to brain cancer has essentially remained unchanged in the last three decades. Thus, paradigm-changing diagnostic and therapeutic reagents are urgently needed.

Assessment of multiexponential diffusion features as MRI cancer therapy response metrics.

The aim of this study was to empirically test the effect of chemotherapy-induced tissue changes in a glioma model as measured by several diffusion indices calculated from nonmonoexponential formalisms over a wide range of b-values. We also compared these results to the conventional two-point apparent diffusion coefficient calculation using nominal b-values. Diffusion-weighted imaging was performed over an extended range of b-values (120-4000 sec/mm(2) ) on intracerebral rat 9L gliomas before and after a single dose of 1,3-bis(2-chloroethyl)-1-nitrosourea.

High-throughput molecular imaging for the identification of FADD kinase inhibitors.

Fas-associated protein with death domain (FADD) was originally reported as a proapoptotic adaptor molecule that mediates receptor-induced apoptosis. Recent studies have revealed a potential role of FADD in NF-κB activation, embryogenesis, and cell cycle regulation and proliferation. Overexpression of FADD and its phosphorylation have been associated with the transformed phenotype in many cancers and is therefore a potential target for therapeutic intervention.

Growth hormone (GH)-dependent expression of a natural antisense transcript induces zinc finger E-box-binding homeobox 2 (ZEB2) in the glomerular podocyte: a novel action of gh with implications for the pathogenesis of diabetic nephropathy.

Growth hormone (GH) excess results in structural and functional changes in the kidney and is implicated as a causative factor in the development of diabetic nephropathy (DN). Glomerular podocytes are the major barrier to the filtration of serum proteins, and altered podocyte function and/or reduced podocyte number is a key event in the pathogenesis of DN. We have previously shown that podocytes are a target for GH action.

Novel molecular imaging platform for monitoring oncological kinases.

Recent advances in oncology have lead to identification of a plethora of alterations in signaling pathways that are critical to oncogenesis and propagation of malignancy. Among the biomarkers identified, dysregulated kinases and associated changes in signaling cascade received the lion's share of scientific attention and have been under extensive investigations with goal of targeting them for anti-cancer therapy. Discovery of new drugs is immensely facilitated by molecular imaging technology which enables non-invasive, real time, dynamic imaging and quantification of kinase activity.

Molecular imaging of glycogen synthase kinase-3beta and casein kinase-1alpha kinases.

Glycogen synthase kinase-3beta (GSK3beta) and casein kinase-1alpha (CK1alpha) are multifunctional kinases that play critical roles in the regulation of a number of cellular processes. In spite of their importance, molecular imaging tools for noninvasive and real-time monitoring of their kinase activities have not been devised. Here we report development of the bioluminescent GSK3beta and CK1alpha reporter (BGCR) based on firefly luciferase complementation.

Molecular imaging of N-linked glycosylation suggests glycan biosynthesis is a novel target for cancer therapy.

Purpose: Redundant receptor tyrosine kinase (RTK) signaling is a mechanism for therapeutic resistance to epidermal growth factor receptor (EGFR) inhibition. A strategy to reduce parallel signaling by coexpressed RTKs is inhibition of N-linked glycosylation (NLG), an endoplasmic reticulum (ER) cotranslational protein modification required for receptor maturation and cell surface expression. We therefore investigated the feasibility of blocking NLG in vivo to reduce overexpression of RTKs.

Curcumin promotes apoptosis, increases chemosensitivity, and inhibits nuclear factor kappaB in esophageal adenocarcinoma.

The transcription factor, nuclear factor kappaB (NF-kappaB), plays a central role as a key mediator of cell survival and proliferation, and its activation may confer increased tumor chemoresistance. Curcumin, an orally available naturally occurring compound, has been shown to inhibit NF-kappaB and has a potential role in cancer chemoprevention. We investigated the effects of curcumin on NF-kappaB activity, on cell viability, and as a chemosensitizing agent with 5-fluorouracil (5-FU) or cisplatin (CDDP) in esophageal adenocarcinoma (EAC).

A transgenic mouse for imaging caspase-dependent apoptosis within the skin.

Apoptosis is an essential process for the maintenance of normal physiology. The ability to noninvasively image apoptosis in living animals would provide unique insights into its role in normal and disease processes. Herein, a recombinant reporter consisting of beta-galactosidase gene flanked by two estrogen receptor regulatory domains and intervening Asp-Glu-Val-Glu sequences was constructed to serve as a tool for in vivo assessment of apoptotic activity.

Role of epidermal growth factor receptor degradation in cisplatin-induced cytotoxicity in head and neck cancer.

Cisplatin and its analogues are the most commonly used agents in the treatment of head and neck squamous cell carcinoma. In this study, we investigated a possible role of epidermal growth factor (EGF) receptor (EGFR) phosphorylation and degradation in cisplatin-induced cytotoxicity. Cisplatin treatment led to an increase in initial EGFR phosphorylation at Y1045, the binding site of ubiquitin ligase, Casitas B-lineage lymphoma (c-Cbl), followed by ubiquitination in the relatively cisplatin-sensitive cell lines.

Evaluation of treatment-associated inflammatory response on diffusion-weighted magnetic resonance imaging and 2-[18F]-fluoro-2-deoxy-D-glucose-positron emission tomography imaging biomarkers.

Purpose: Functional imaging biomarkers of cancer treatment response offer the potential for early determination of outcome through the assessment of biochemical, physiologic, and microenvironmental readouts. Cell death may result in an immunologic response, thus complicating the interpretation of biomarker readouts. This study evaluated the temporal effect of treatment-associated inflammatory activity on diffusion magnetic resonance imaging and 2-[(18)F]-fluoro-2-deoxy-D-glucose-positron emission tomography imaging (FDG-PET) biomarkers to delineate the effects of the inflammatory response on imaging readouts.

AGTR1 overexpression defines a subset of breast cancer and confers sensitivity to losartan, an AGTR1 antagonist.

Breast cancer patients have benefited from the use of targeted therapies directed at specific molecular alterations. To identify additional opportunities for targeted therapy, we searched for genes with marked overexpression in subsets of tumors across a panel of breast cancer profiling studies comprising 3,200 microarray experiments. In addition to prioritizing ERBB2, we found AGTR1, the angiotensin II receptor type I, to be markedly overexpressed in 10-20% of breast cancer cases across multiple independent patient cohorts.

Enhancing Akt imaging through targeted reporter expression.

The serine/threonine kinase PKB/Akt is a key mediator of survival and resistance to cancer therapy. Pharmacologic inhibition of Akt and its biologic sequelae may significantly impact the treatment of cancer. The use of molecular imaging technologies has contributed significantly to drug discovery research with an emphasis on drug efficacy, the mechanism of action, and target validation studies.

Inhibition of N-linked glycosylation disrupts receptor tyrosine kinase signaling in tumor cells.

Receptor tyrosine kinases (RTK) are therapeutic targets for the treatment of malignancy. However, tumor cells develop resistance to targeted therapies through the activation of parallel signaling cascades. Recent evidence has shown that redundant or compensatory survival signals responsible for resistance are initiated by nontargeted glycoprotein RTKs coexpressed by the cell.

A small-molecule furin inhibitor inhibits cancer cell motility and invasiveness.

Furin, a member the proprotein convertase (PC) family, processes inactive precursor proteins to functional proteins within the Golgi/trans-Golgi network secretory pathway. Furin and other PC family members (furin/PCs) activate proteins vital to proper physiological functioning, including growth factors and hormones, receptors, plasma proteins, and matrix metalloproteases (MMPs). Additionally, the expression and activity of furin/PC are necessary for processing substrates important for cell transformation and tumor progression, metastasis, and angiogenesis.

Molecular imaging of protein kinases.

Protein kinases are important regulators of signal-transduction pathways. Dysregulated kinase activity is observed in a variety of human diseases such as cancer, making them targets for the development of molecular therapies. Identification of new drugs is greatly aided by molecular imaging tools which enable real time, non-invasive, dynamic and quantitative imaging of kinase activity in vivo.

CXCR7 (RDC1) promotes breast and lung tumor growth in vivo and is expressed on tumor-associated vasculature.

Chemokines and chemokine receptors have been posited to have important roles in several common malignancies, including breast and lung cancer. Here, we demonstrate that CXCR7 (RDC1, CCX-CKR2), recently deorphanized as a chemokine receptor that binds chemokines CXCL11 and CXCL12, can regulate these two common malignancies. Using a combination of overexpression and RNA interference, we establish that CXCR7 promotes growth of tumors formed from breast and lung cancer cells and enhances experimental lung metastases in immunodeficient as well as immunocompetent mouse models of cancer.

Molecular imaging of Akt kinase activity.

The serine/threonine kinase Akt mediates mitogenic and anti-apoptotic responses that result from activation of multiple signaling cascades. It is considered a key determinant of tumor aggressiveness and is a major target for anticancer drug development. Here, we describe a new reporter molecule whose bioluminescence activity within live cells and in mice can be used to measure Akt activity.

Noninvasive molecular imaging sheds light on the synergy between 5-fluorouracil and TRAIL/Apo2L for cancer therapy.

Purpose: In a previous report, a recombinant luciferase reporter, activated during apoptosis via caspase-3 cleavage, was developed for imaging of apoptosis using bioluminescence. The ability to noninvasively image apoptosis in vivo could dramatically benefit the preclinical development of therapeutics targeting the apoptotic pathway. In this study, we examined the use of 5-fluorouracil (5-FU) for sensitizing D54 tumors to tumor necrosis factor alpha-related apoptosis-inducing ligand (TRAIL) therapy by monitoring apoptotic activity in vivo using bioluminescence imaging.