Protein synthesis rate measured with L-[1-11C]tyrosine positron emission tomography correlates with mitotic activity and MIB-1 antibody-detected proliferation in human soft tissue sarcomas

Metabolomics in cancer research and emerging applications in clinical oncology

Cancer has myriad effects on metabolism that include both rewiring of intracellular metabolism to enable cancer cells to proliferate inappropriately and adapt to the tumor microenvironment, and changes in normal tissue metabolism. With the recognition that fluorodeoxyglucose-positron emission tomography imaging is an important tool for the management of many cancers, other metabolites in biological samples have been in the spotlight for cancer diagnosis, monitoring, and therapy. Metabolomics is the global analysis of small molecule metabolites that like other -omics technologies can provide critical information about the cancer state that are otherwise not apparent. Here, the authors review how cancer and cancer therapies interact with metabolism at the cellular and systemic levels. An overview of metabolomics is provided with a focus on currently available technologies and how they have been applied in the clinical and translational research setting. The authors also discuss how metabolomics could be further leveraged in the future to improve the management of patients with cancer.

Carbon-11: Radiochemistry and Target-Based PET Molecular Imaging Applications in Oncology, Cardiology, and Neurology

The positron emission tomography (PET) molecular imaging technique has gained its universal value as a remarkable tool for medical diagnosis and biomedical research. Carbon-11 is one of the promising radiotracers that can report target-specific information related to its pharmacology and physiology to understand the disease status. Currently, many of the available carbon-11 (t_1/2 = 20.4 min) PET radiotracers are heterocyclic derivatives that have been synthesized using carbon-11 inserted different functional groups obtained from primary and secondary carbon-11 precursors. A spectrum of carbon-11 PET radiotracers has been developed against many of the upregulated and emerging targets for the diagnosis, prognosis, prediction, and therapy in the fields of oncology, cardiology, and neurology. This review focuses on the carbon-11 radiochemistry and various target-specific PET molecular imaging agents used in tumor, heart, brain, and neuroinflammatory disease imaging along with its associated pathology.

The role of exogenous epidermal growth factor on Ki-67 proliferation marker expression in the submandibular salivary gland of albino rats receiving doxorubicin

Background: This study was conducted to evaluate the role of exogenous epidermal growth factor (EGF) injection on the Ki-67 immuno-expression in submandibular salivary gland tissue of rats receiving doxorubicin (DXR). Methods: A total of 21 two-month-old male albino rats, of 200 g body weight, were divided into three groups: control group; DXR group, the rats received 20 mg/kg body weight DXR as a single intra peritoneal injection; DXR+EGF group, the rats received the same dose of DXR and on the next day they were injected intraperitoneally with 10 µg/kg body weight of EGF daily for one week. Histological sections and immunohistochemical expression of Ki67 sections were examined using a ZEISS Primo Star light microscopy and images taken using Tucsen IS 1000 10.0MP Camera. Results: Ki-67 expression was significantly increased in submandibular salivary glands of rats after DXR injection. However, Ki-67 expression in the glandular tissue was restored to normal levels after EGF injection. Conclusions: EGF preserved glandular architecture after DXR injection and maintained Ki-67 immune-expression within the glandular tissue near to the normal level.

Exploring Metabolism In Vivo Using Endogenous 11C Metabolic Tracers

Cancer and other diseases are increasingly understood in terms of their metabolic disturbances. This thinking has revolutionized the field of ex vivo metabolomics and motivated new approaches to detect metabolites in living systems, including proton magnetic resonance spectroscopy (1H-MRS), hyperpolarized 13C MRS, and PET. For PET, imaging abnormal metabolism in vivo is hardly new. Positron-labeled small-molecule metabolites have been used for decades in humans, including 18F-FDG, which is used frequently to detect upregulated glycolysis in tumors. Many current 18F metabolic tracers including 18F-FDG have evolved from their 11C counterparts, chemically identical to endogenous substrates and thus approximating intrinsic biochemical pathways. This mimicry has stimulated the development of new radiochemical methods to incorporate 11C and inspired the synthesis of a large number of 11C endogenous radiotracers. This is in spite of the 20-minute half-life of 11C, which generally limits its use in patients to centers with an on-site cyclotron. Innovation in 11C chemistry has persisted in the face of this limitation, because (1) the radiochemists involved are inspired, (2) the methods of 11C incorporation are diverse, and (3) 11C compounds often show more predictable in vivo behavior, thus representing an important first step in the validation of new tracer concepts. In this mini-review we will discuss some of the general motivations behind PET tracers, rationales for the use of 11C, and some of the special challenges encountered in the synthesis of 11C endogenous compounds. Most importantly, we will try to highlight the exceptional creativity used in early 11C tracer syntheses, which used enzyme-catalyzed and other "green" methods before these concepts were commonplace.

(11)C[double bond, length as m-dash]O bonds made easily for positron emission tomography radiopharmaceuticals

The positron-emitting radionuclide carbon-11 ((11)C, t1/2 = 20.3 min) possesses the unique potential for radiolabeling of any biological, naturally occurring, or synthetic organic molecule for in vivo positron emission tomography (PET) imaging. Carbon-11 is most often incorporated into small molecules by methylation of alcohol, thiol, amine or carboxylic acid precursors using [(11)C]methyl iodide or [(11)C]methyl triflate (generated from [(11)C]carbon dioxide or [(11)C]methane). Consequently, small molecules that lack an easily substituted (11)C-methyl group are often considered to have non-obvious strategies for radiolabeling and require a more customized approach. [(11)C]Carbon dioxide itself, [(11)C]carbon monoxide, [(11)C]cyanide, and [(11)C]phosgene represent alternative reactants to enable (11)C-carbonylation. Methodologies developed for preparation of (11)C-carbonyl groups have had a tremendous impact on the development of novel PET tracers and provided key tools for clinical research. (11)C-Carbonyl radiopharmaceuticals based on labeled carboxylic acids, amides, carbamates and ureas now account for a substantial number of important imaging agents that have seen translation to higher species and clinical research of previously inaccessible targets, which is a testament to the creativity, utility and practicality of the underlying radiochemistry.

Imaging tumor metabolism using positron emission tomography

Positron emission tomography (PET) is an extraordinarily sensitive clinical imaging modality for interrogating tumor metabolism. Radiolabeled PET substrates can be traced at subphysiological concentrations, allowing noninvasive imaging of metabolism and intratumoral heterogeneity in systems ranging from advanced cancer models to patients in the clinic. There are a wide range of novel and more established PET radiotracers, which can be used to investigate various aspects of the tumor, including carbohydrate, amino acid, and fatty acid metabolism. In this review, we briefly discuss the more established metabolic tracers and describe recent work on the development of new tracers. Some of the unanswered questions in tumor metabolism are considered alongside new technical developments, such as combined PET/magnetic resonance imaging scanners, which could provide new imaging solutions to some of the outstanding diagnostic challenges facing modern cancer medicine.

Design and development of molecular imaging probes

Molecular imaging, the visualization, characterization and measurement of biological processes at the cellular, subcellular level, or even molecular level in living subjects, has rapidly gained importance in the dawning era of personalized medicine. Molecular imaging takes advantage of the traditional diagnostic imaging techniques and introduces molecular imaging probes to determine the expression of indicative molecular markers at different stages of diseases and disorders. As a key component of molecular imaging, molecular imaging probe must be able to specifically reach the target of interest in vivo while retaining long enough to be detected. A desirable molecular imaging probe with clinical translation potential is expected to have unique characteristics. Therefore, design and development of molecular imaging probe is frequently a challenging endeavor for medicinal chemists. This review summarizes the general principles of molecular imaging probe design and some fundamental strategies of molecular imaging probe development with a number of illustrative examples.

FDG PET imaging of childhood sarcomas

BACKGROUND

Positron-emission tomography (PET) imaging using [(18)F]fluorodeoxyglucose (FDG) is useful for detection, staging, and monitoring a variety of malignancies, including lymphoma, in adults, but its utility in sarcomas, especially soft tissue sarcomas (STS), in children and young adults is not clear.

PROCEDURE

To evaluate the potential utility of FDG PET in the care of STS in children and young adults, we analyzed 46 PET scans in 25 patients acquired over 12 years. Scans were interpreted by two imaging physicians blinded to findings from other imaging studies and clinical information. Results were compared with computed tomography and magnetic resonance imaging, biopsy results, where available, and clinical follow-up of at least 12 months.

RESULTS

For a total of 46 scans in 25 patients, there were 25 true-positive scans, 3 false-positive scans, 12 true-negative scans, and 6 false-negative scans. The sensitivity of the PET scan was 86%, specificity was 80%, positive predictive value was 89%, and negative predictive value was 67%.

CONCLUSION

FDG PET may be a useful imaging modality in the management of children and young adults with STS, although prospective studies are needed to establish its true utility.

Ki67 and salivary cancer

We examined Ki67 expression in salivary malignancies of 75 patients with a follow-up period of up to 20 years. Correlations between enhanced Ki67 and enhanced p53 and TUNEL and heparanase staining levels were significant. Median survival for reduced-stained-tumor patients (< or = 5%) was 163 months, dropping significantly to 39 months (p = 0.0005) for enhanced stained tumors (> 5%); 5 year survival probability was 93% and 33%, respectively, 45% and 16%, respectively, (p = 0.0005) at 20 years. Significant correlation between poor survival and concurrently altered expression rates of Ki67 and p53, p27 Skp2, TUNEL and heparanase in the salivary malignancies indicates a biological role in salivary cancer pathogenesis.

No induction of structural chromosomal aberrations in cylindrospermopsin-treated CHO-K1 cells without and with metabolic activation

Cylindrospermopsin (CYN) is a cyanobacterial alkaloid that has been implicated in outbreaks of human morbidity and animal mortality. The principal mode of action for CYN is inhibition of protein and glutathione synthesis, and its toxicity seems to be mediated by cytochrome P-450-generated metabolites. It was also shown that CYN might be responsible for tumor initiation in animals; nevertheless, mechanisms leading to CYN-induced carcinogenesis are scarce and equivocal. The aim of the present study was to investigate the impact of metabolic activation on CYN-induced DNA damage. The effect of different doses of CYN (0.05-2mug/ml) on DNA damage was determined in CHO-K1 cells after 3, 16 and 21h of the treatment. The chromosome aberration assay with and without metabolic activation was applied to evaluate the clastogenic activity of CYN and its metabolite(s). In addition, the occurrence of apoptosis and necrosis was estimated by the annexin method using flow cytometry. The results revealed that CYN is not clastogenic in CHO-K1 cells irrespective of S9 fraction-induced metabolic activation. However, CYN significantly decreases the frequencies of mitotic indices and decreases proliferation irrespective of metabolic activation system. CYN increases the frequency of necrotic cells in a dose- and time-dependent manner, whereas it has a very slight impact on apoptosis. Moreover, the presence of metabolic activation influences a susceptibility to necrotic cell death but not an apoptotic one.

Role of PET/PET-CT in the management of sarcomas

Positron emission tomography (PET) is a functional diagnostic imaging technique that provides very different information from that obtainable with other imaging modalities. The most widely used radiotracer is F-18 fluoro-2-deoxy-D-glucose (FDG), which is an analog of glucose. The FDG uptake in cells is directly proportional to glucose metabolism, which is increased many times in malignant cells. FDG-PET is now the standard of care in initial staging, monitoring the response to therapy and management of various cancers (e.g., breast cancer, lung cancer and lymphoma). However, the paucity of anatomical landmarks on PET images makes a consistent hardware fusion to anatomical cross-sectional data extremely useful. The introduction of combined PET-computer tomography (CT) scanners, which provide not only functional, but also structural information leading to a detection of subcentimeter lesions, made this technique useful in the early detection of the disease process and decreasing false-positive lesions. The aim of this article is to review the clinical applications (i.e., diagnosis, staging, evaluation of treatment response and restaging) using PET in patients with bone and soft-tissue sarcoma.

Detection and Grading of Soft Tissue Sarcomas of the Extremities with18F-3′-Fluoro-3′-Deoxy-l-Thymidine

PURPOSE

The aim of the study was to investigate the feasibility of (18)F-3'-fluoro-3'-deoxy-L-thymidine positron emission tomography (FLT-PET) for the detection and grading of soft tissue sarcoma (STS).

EXPERIMENTAL DESIGN

Nineteen patients with 20 STSs of the extremities were scanned, using attenuation corrected whole-body FLT-PET. Standardized uptake values (SUVs) and tumor:nontumor ratios (TNTs) were compared with histopathological parameters using French and Japanese grading systems.

RESULTS

Mean SUV, maximal SUV, and TNT could differentiate between low-grade (grade 1; n = 6) STS and high-grade (grade 2 and 3; n = 14) STS according to the French grading system (P = 0.001). Mean SUV, max SUV, and TNT correlated with mitotic score, MIB-1 score, the French and Japanese grading system (* = 0.550-0.747).

CONCLUSIONS

FLT-PET is able to visualize STS and differentiate between low-grade and high-grade STS. The uptake of FLT correlates with the proliferation of STS.

Ki67 protein: the immaculate deception?

This article updates our previous review of Ki67 published in Histopathology 10 years ago. In this period the numbers of papers published featuring this antibody has increased 10-fold from 338 to 3489 indicating the considerable enthusiasm with which this antibody has been studied. This review attempts to provide an update on the characterization of the Ki67 protein, its function and its use as a prognostic or diagnostic tool.

The role of radionuclides in primary musculoskeletal tumors beyond the 'bone scan'

Radionuclides represent a means of functional imaging, which is able to reflect the metabolic state of tissues. Recently developed radiotracers and older radiotracers with newer applications, imaged through single photon emission computed tomography (SPECT) and positron emission tomography (PET), can provide significant information in the diagnosis, grading, therapy response or recurrence of primary musculoskeletal tumors. The unique ability of these radiotracers to demonstrate non-invasively the efflux pump rate, which is a common reason of therapy failure, as well as the metabolic and proliferative rates of the tumors should be a powerful tool in the orthopaedic oncology in the evaluation of musculoskeletal tumors.

The location of pKi67 in the outer dense fibrillary compartment of the nucleolus points to a role in ribosome biogenesis during the cell division cycle

Although widely used as a marker of cell proliferation, the biochemical properties and function of the Ki67 antigen remain poorly understood. Recent data indicate that it can interact with RNA, DNA, and a number of cellular proteins including elements of the ubiquitin proteolytic pathway and a novel kinase. The evidence for its expression only in cycling cells is extensive and it is not regulated by stress, apoptosis or DNA damage. It was reasoned that a detailed characterization of the localization of pKi67 and analysis of its spatial relationship to other nucleolar proteins may provide insights into its function. Using high-resolution laser scanning confocal microscopy with double and triple labelling, pKi67 expression in MCF7 cells has been defined in relation to the distribution of nucleolin, fibrillarin, p130 (human Nopp 140 homologue), p120 (Nol 1), RH-II/Gu helicase, and topoisomerase II beta. All of these molecules are perichromosomal during mitosis and all but fibrillarin and p130 show extra-nucleolar distribution in early G1. The majority of p120 (Nol 1) and RH-II/Gu helicase co-localize in the diffuse fibrillar centre (DFC) of nucleoli, while there is only partial overlap with nucleolin and fibrillarin. There is no co-localization between p130 and pKi67. These data refine current understanding of the distribution of pKi67 and its physical relationship with functional domains of the nucleolus and place pKi67 in a zone of the DFC associated with late rRNA processing. Taken together with recent biochemical data, these observations allow the proposal of a model of pKi67 function in which it acts as an 'efficiency factor' in ribosome biogenesis during the heavy metabolic demands placed on a cell during the cell division cycle.