Kolon kanseri teşhisine yönelik benzotiyazol türevlerinin geliştirilmesi ve sentezi
Development and synthesis of benzothiazole derivatives for colon cancer diagnosis
Yazar: ESRA UYSAL
Danışman: DR. ÖĞR. ÜYESİ ONUR ALPTÜRK ; DR. ÖZGÜR YILMAZ
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Kimya Ana Bilim Dalı / Kimya Bilim Dalı
Derece: Yüksek Lisans, 2020
Konu: Kimya = Chemistry

Özet:
Başta kanser olmak üzere birçok hastalığın teşhis edilebilmesi ve sonrasında izlenecek tedavi yönteminin oluşturulması için kullanılan yöntemlerden biri moleküler görüntülemedir. Moleküler görüntüleme yöntemleri hastaya en uygun kişiselleştirilmiş tedavi yaklaşımını tasarlamak ve uygulamak için kullanılmaktadır. Moleküler görüntüleme ile etkili tedaviyi sağlamak için hastalığın olası nedeni ve ilerlemesi hakkında mümkün olan en iyi ayrıntıyı elde etmek ve analiz etmek önemlidir. Bu nedenle vücuttaki hastalığın teşhis edilerek tedavi sürecini izlemek ve değerlendirmek uygun biyobelirteçlerin seçilmesi ile mümkündür. Vücutta meydana gelen moleküler değişiklikler ile hastalığın tespit edilmesi, tanımlanması, hastalık hakkında biyolojik, kimyasal ve fizyolojik aktiviteleri hakkında bilgi elde edilmesi moleküler görüntüleme probları ile sağlanır. Hastalıklı hücrenin ve vücutta meydana gelen süreçlerin en etkili şekilde tanımlanabilmesi için görüntüleme problarının uygun biyobelirteçlere yüksek seçicilik ve afinite ile bağlanması gerekmektedir. 
Bu tez çalışması kapsamında amaç kolon kanserinin pozitron emisyon tomografisi-bilgisayar tomografisi (PET-BT) moleküler görüntüleme cihazında kullanılmak üzere görüntüleme problarının taşıyıcı fragmanlarını tasarlamak ve sentezlemektir. Tümör hücrelerinin mikro çevresinde yer alan PD-L1 immün noktası hedef olarak seçilmiş olup görüntüleme problarının spesifik olarak tümör hücrelerine ulaşabilmesi ve etkileşebilmeleri sayesinde görüntülerin elde edilebilmesi hedeflenmektedir. 
Vücutta bağışıklığın düzenlenmesi, olası tehditlere karşı yanıtlarının verilmesi ve harekete geçebilmeleri immün kontrol noktaları denilen mekanizmaların çeşitli yapılar ve etkenler ile uyarılması ile mümkündür. T-hücreleri yapısında bulundurduğu reseptörler ve bağlanıcı moleküller aracılığı ile vücut içinde hastalıkların tespit edilerek bağışıklık sistemini harekete geçirir. Bu sayede vücut içerisinde gözlenen tümör gibi anormal hücre ve yapıların yok edilmesi sağlanır.  İmmün yanıtlarını kontrol edebilen bu hücreler üzerinde etkinliğini göstermesi veya engellenmesini sağlayan uyarıcı ve inhibe edici moleküller bulunmaktadır. İmmün sisteminin dengelenmesinde rol alan PD-L1 proteini birçok kanser hücresinin yapısında bulunmaktadır. T-hücresi üzerinde yer alan PD-1 proteini ile bağlanmasıyla T-hücrelerinin deaktive olmasına neden olarak etkinliğini gösterememesine neden olmaktadır.
Tümör mikro çevrelerinin incelenmesi sonucu immün noktası PD-L1 proteini biyobelirteç olarak belirlenmiş olup PD-L1 protein yapısına yüksek seçicilik ile bağlanabilmesi açısından aktif bölgeleri tespit edilmiş ve bu proteine bağlanabilecek uygun moleküller modellenmiştir. Modelleme aşamasında GVIA peptit yapısının yüksek bağlanma özelliği dolayısıyla biyokimyasal prob olarak kullanılması, bu yapıdan esinlenerek molekül ve peptidomimetiklerin oluşturulmasına zemin hazırlamıştır. GVIA peptit yapılarında uygun farmakoforların baz alınması ile tasarlanmış moleküllerin ve peptidomimetiklerin biyobelirteç olarak belirlenmiş PD-L1 ligandı ile uygun etkileşimler sağlayabileceği görülmüştür. in silico çalışmalar sonucunda hedef biyobelirteçlere spesifik olarak bağlanabilecek moleküller modellenmiş olup tez çalışması kapsamında uygun bulunan moleküllerin sentezleri gerçekleştirilmiştir.
Elde edilen moleküller daha sonra DOTA yapısı ile birleştirilecek ve 68Ga radyonüklid atomu ile işaretlenerecektir. Oluşturulan yapı PET-BT görüntülemede kullanılan görüntüleme ajanı ile birleştirilmesi sonucunda tümör hücrelerini tespit ederek işaretlenmesini ve görüntülenmesini sağlayarak PET-BT görüntüleme cihazında yüksek verimde ve hassasiyette görüntüler elde edilmesi sağlanacaktır.

Abstract:
Various methods have been found and applied to reach the information to be obtained about the disease or many abnormal conditions occurring in the body. However, since the information and data to be obtained are desired to be accurate and can be measured at the same time, they have searched for a measurable characteristic factor that meets these criteria. As a result of researches and studies, it is now possible to diagnose diseases and abnormal conditions correctly, to apply appropriate treatment methods according to the course of the disease, and to monitor its response to treatment. Biomarkers, which play a role in the external detection and observation of biochemical or molecular changes and processes occurring in metabolic environments such as tissues, cells or fluids in humans, provide information about the patient by examining the images obtained with imaging devices to detect the disease in the clinical areas and to obtain information about the course of the disease.
In order to detect the disease and to get information about the course of the disease in the clinical areas, it is possible to provide information about the patient by examining the images obtained with the imaging devices in the clinical environment through biomarkers. They have many applications, including the diagnosis of any disease in the body, its prediction for its treatment, the condition of whether the disease has progressed, or the appropriate tool and method for understanding and measuring the outcome of the treatment.
With the aim of molecular imaging, it is important to obtain and analyze the disease to the finest details about the potential cause and progression of the disease in order to achieve effective treatment. Molecular imaging methods are used to design and apply the most appropriate personalized treatment method for the patient. One of the reasons for getting more precise results with molecular imaging compared to other clinical methods is that it can provide detailed information by simultaneously displaying the metabolic and biological events occurring in the body. Another advantage of molecular imaging is that it does not require an invasive procedure such as biopsy and open surgeries. Without the need for surgical operations, the diagnosis can be made and information about the pathology of the disease can be obtained. Based on the information and images acquired, specific treatment methods are created and whether these treatments are effective can be monitored by simultaneously measuring them quantitatively.
Various molecular imaging techniques have been developed to examine many diseases, especially cancer, and to obtain the most effective images of diseased tissues. Molecular imaging methods commonly used today include magnetic resonance imaging (MRI), optical imaging, ultrasound imaging, computed tomography (CT) imaging and radionuclide imaging.
Within the scope of pathological researches of many diseases, especially cancer, molecular imaging agents that can make precise measurements specific to different diseases have been developed, and thus, various agents have been developed and developed for molecular imaging. It is possible to monitor the disease process and carry out the treatment process in the best way by detecting the diseased cell or tissue by using various agents in molecular imaging, which is used to characterize, monitor, and measure the biological processes in cells and tissues. When molecular imaging agents are taken into the body, they should have the characteristics that will not cause the problem and also perform the target imaging process in the best way. In line with these applications, specific imaging agents suitable for imaging techniques have been developed in order to achieve better results, to diagnose early and to access information about the disease and treatment course in the focused area.
To date, many types of cancer have been discovered and efficient diagnosis and treatment methods have been developed for these cancer types. Among the methods, it is more preferred than other methods due to the fact that it does not require invasive procedures, and it can obtain efficient and fast results, molecular imaging devices that enable the imaging of cells and tissues in the body, along with many diseases, are involved in the detection of cancer and the monitoring of the disease process. As a result of researches progressing towards the structure and features of cancer, the most effective execution of the early diagnosis and treatment process has revealed that the derivation and development of agents that can direct to specific cancer cells.
Molecular imaging uses molecular imaging agents that can be directed to the targeted cell or tissue in the body. These imaging agents are made possible by contrast agents or radiotracers, which are probes developed to direct the receptors and targets identified by the investigation of the microenvironment of the region to be examined in the body. In addition to the probes developed by defining the tumor microenvironment, immune control points, which are understood by studies in the field of immunotherapy, have started to be used in medical imaging. Imaging agents reach tumor cells when introduced into the body, and the density of the probes increases at these points. By determining the location by the molecular imaging device, images and information about the tumor are obtained. In this way, cancer can be diagnosed early. The most appropriate treatment method is determined by examining the stage and course of the disease. 
Appropriate molecular imaging probes should be designed and applied in appropriate imaging methods in order to reach the most effective and accurate information about the disease. In order to design and develop a good molecular imaging probe, the biological processes and microenvironment of the identified disease must be well understood. Appropriate imaging probes have been developed by making use of the research and data obtained about tumor expressions and microenvironments. When developing molecular imaging probes, it is desired to have high precision and affinity for fast binding to the specific target. Depending on the characteristics of the structure or element to be targeted in the tumor, appropriate imaging probes are selected and images are obtained to examine the location and effectiveness of the tumor. It is desirable that the molecular imaging probes are not subjected by tumor cells and also have high structural stability. By reaching the tumor cells successfully, it should be ensured that the tumor is detected in that region and the image produced by the tumor is detected.
It is possible to regulate immunity in the body, to respond to possible threats and to act, by stimulating mechanisms called immune control points with various structures and factors. T-cells activate the immune system by detecting diseases in the body through the receptors and binding molecules it contains. In this way, abnormal cells and structures such as tumors observed in the body are destroyed. There are stimulating and inhibitory molecules on these cells that can control the immune responses, enabling them to act or block their effectiveness. PD-L1 protein, which plays a role in balancing the immune system, is also found in the structure of cancer cells. By binding with the PD-1 protein located on the T-cell, it causes the T-cells to be deactivated and ineffective.
The aim of the project is to develop an alternative imaging agent that can be used in the PET-CT imaging device by synthesizing radionuclide labeled carrier molecules that can recognize and bind tumor associated cells with high interest and selectivity. In this project, the PD-L1 protein usually found in tumor cell membranes are selected as targets for imaging probes. In order for the imaging probes to bind to the PD-L1 protein with high selectivity, active regions of the PD-L1 protein have been identified and suitable molecules that can bind to this protein have been modeled. In the modeling phase, the use of the GVIA peptide structure as a biochemical probe due to its high binding property paved the way for the formation of molecules and peptidomimetics, inspired by this structure. It has been found that molecules and peptidomimetics designed by basing appropriate pharmacophores in GVIA peptide structures can provide appropriate interactions with the PD-L1 ligand. As a result of in silico studies, the molecules that can be specifically bound to the target biomarkers are modeled and the syntheses of the molecules that are found appropriate are carried out in the thesis.
The synthesized molecules will then be combined with the DOTA complex molecule and labeled with the 68Ga radionuclide atom. As a result of combining the synthesized structure with the imaging agent used in PET-CT imaging, high efficiency and high-resolution images can be obtained in the PET-CT imaging device by detecting and displaying tumor cells.