Progress Report No. 3

Progress report of the Biomedical Computer Laboratory, covering period 1 July 1966 to 30 June 1967

[¹⁸F]fluorination of biorelevant arylboronic acid pinacol ester scaffolds synthesized by convergence techniques

Aim: The development of small molecules through convergent multicomponent reactions (MCR) has been boosted during the last decade due to the ability to synthesize, virtually without any side-products, numerous small drug-like molecules with several degrees of structural diversity.(1) The association of positron emission tomography (PET) labeling techniques in line with the “one-pot” development of biologically active compounds has the potential to become relevant not only for the evaluation and characterization of those MCR products through molecular imaging, but also to increase the library of radiotracers available. Therefore, since the [18F]fluorination of arylboronic acid pinacol ester derivatives tolerates electron-poor and electro-rich arenes and various functional groups,(2) the main goal of this research work was to achieve the 18F-radiolabeling of several different molecules synthesized through MCR. Materials and Methods: [18F]Fluorination of boronic acid pinacol esters was first extensively optimized using a benzaldehyde derivative in relation to the ideal amount of Cu(II) catalyst and precursor to be used, as well as the reaction solvent. Radiochemical conversion (RCC) yields were assessed by TLC-SG. The optimized radiolabeling conditions were subsequently applied to several structurally different MCR scaffolds comprising biologically relevant pharmacophores (e.g. β-lactam, morpholine, tetrazole, oxazole) that were synthesized to specifically contain a boronic acid pinacol ester group. Results: Radiolabeling with fluorine-18 was achieved with volumes (800 μl) and activities (≤ 2 GBq) compatible with most radiochemistry techniques and modules. In summary, an increase in the quantities of precursor or Cu(II) catalyst lead to higher conversion yields. An optimal amount of precursor (0.06 mmol) and Cu(OTf)2(py)4 (0.04 mmol) was defined for further reactions, with DMA being a preferential solvent over DMF. RCC yields from 15% to 76%, depending on the scaffold, were reproducibly achieved. Interestingly, it was noticed that the structure of the scaffolds, beyond the arylboronic acid, exerts some influence in the final RCC, with electron-withdrawing groups in the para position apparently enhancing the radiolabeling yield. Conclusion: The developed method with high RCC and reproducibility has the potential to be applied in line with MCR and also has a possibility to be incorporated in a later stage of this convergent “one-pot” synthesis strategy. Further studies are currently ongoing to apply this radiolabeling concept to fluorine-containing approved drugs whose boronic acid pinacol ester precursors can be synthesized through MCR (e.g. atorvastatin)

Mammography

In this volume, the topics are constructed from a variety of contents: the bases of mammography systems, optimization of screening mammography with reference to evidence-based research, new technologies of image acquisition and its surrounding systems, and case reports with reference to up-to-date multimodality images of breast cancer. Mammography has been lagged in the transition to digital imaging systems because of the necessity of high resolution for diagnosis. However, in the past ten years, technical improvement has resolved the difficulties and boosted new diagnostic systems. We hope that the reader will learn the essentials of mammography and will be forward-looking for the new technologies. We want to express our sincere gratitude and appreciation?to all the co-authors who have contributed their work to this volume

Oncogene and Cancer

This book describes a course of cancer growth starting from normal cells to cancerous form and the genomic instability, the cancer treatment as well as its prevention in form of the invention of a vaccine. Some diseases are also discussed in detail, such as breast cancer, leucaemia, cervical cancer, and glioma. Understanding cancer through its molecular mechanism is needed to reduce the cancer incidence. How to treat cancer more effectively and the problems like drug resistance and metastasis are very clearly illustrated in this publication as well as some research result that could be used to treat the cancer patients in the very near future. The book was divided into six main sections: 1. HER2 Carcinogenesis: Etiology, Treatment and Prevention; 2. DNA Repair Mechanism and Cancer; 3. New Approach to Cancer Mechanism; 4. New Role of Oncogenes and Tumor Suppressor Genes; 5. Non Coding RNA and Micro RNA in Tumorigenesis; 6. Oncogenes for Transcription Factor

Colorectal Cancer

Colorectal cancer is one of the commonest cancers affecting individuals across the world. An improvement in survival has been attributed to multidisciplinary management, better diagnostics, improved surgical options for the primary and metastatic disease and advances in adjuvant therapy. In this book, international experts share their experience and knowledge on these different aspects in the management of colorectal cancer. An in depth analysis of screening for colorectal cancer, detailed evaluation of diagnostic modalities in staging colorectal cancer, recent advances in adjuvant therapy and principles and trends in the surgical management of colorectal cancer is provided. This will certainly prove to be an interesting and informative read for any clinician involved in the management of patients with colorectal cancer

Osteogenetic differentiation: a novel role of Slug protein

The regeneration of bone tissue depends on the concerted actions of a plethora of signals that recruit mesenchymal stem cells for lineage-specific differentiation. The signals are conveyed in hormones, growth factors and transcription factors. These molecules are crucial for the osteoblast commitment, differentiation, functions and, consequently, ensure the proper bone modelling and remodelling. Among these factors, Wnt proteins have a critical role in bone development and homeostasis. Accumulated evidences have shown that lymphocyte enhancer binding factor 1/T cell factor (Lef1/Tcf) transcription factors, the nuclear effectors of the Wnt/β-catenin signaling pathway, influence osteoblast proliferation, function, and regeneration. Nevertheless, most downstream bone-specific target genes of this pathway are only partially known. Among these, Slug has been recently implicated in osteosarcoma progression as a Wnt-responsive molecule strongly correlated with a loss of tumor suppressors such as E-cadherin. Slug, also named Snail2, belongs to the Snail family of genes encoding zinc-finger transcription factors. It is expressed at different stages of development in different tissues, mediates epithelial–mesenchymal transition and directs cell motility during embriogenesis. Slug is also expressed in most normal adult human tissues, but little is known about its potential functions. In order to identify new potential osteoblast-specific proteins, in this study we analysed the expression, regulation and role of Slug in human normal primary osteoblasts (hOBs) and in their mesenchymal precursors (hMSCs), in relation to the expression of Wnt/β-catenin signalling mediators and genes which are required in the control of osteochondroprogenitors differentiation. The experiments were performed on hOBs and hMSCs, obtained from bone marrow iliac crest, bone marrow tibial plateau and Wharton’s jelly umbilical cord. Using several molecular analysis including siRNA strategy and Chromatin Immunoprecipitation (ChIP) assay, we demonstrated that: - Slug is expressed in hOBs as well as their mesenchymal precursors; - In hOBs, Slug is regulated by β-catenin and Lef1 that, together with Tcf-1, Tcf-4 and Runx2 are recruited to the Slug gene promoter in vivo; - In hOBs, Slug is positively correlated with osteoblastic markers, such as Runx2, osteopontin, osteocalcin, collagen type I, CXCL12, Wnt/β-catenin signalling and mineral deposition. At the same time, it negatively correlated with Sox9, a factor indispensable for chondrogenic development; - In hMSCs, Slug acts as a negative regulator of Sox9 and Sox5 expression and a positive regulator of Sox6 and STAT1 genes. Regarding Runx2, the role of Slug seems influenced by cell type; - Slug interacts in vivo with Runx2 and Sox9 promoters in hOBs and hMSCs. Our results support the hypothesis that Slug functions as a novel regulator of osteoblast activity, even if with a different role in mature committed osteoblasts and in their undifferentiated progenitors. Furthermore, these findings suggest Slug as a new potential therapeutic target for bone tissue repair and regeneration