Research Projects

The nucleus of the cell plays a crucial role in protecting genetic information and regulating cellular activities. Therefore, targeting the nucleus is a promising strategy for cancer therapy. While several drugs are known to target nuclear DNA or enzymes, only a small fraction of these drugs can enter the nucleus. This limitation is partly due to a lack of understanding of the nuclear transport mechanism. Recent findings suggest that the nuclear protein complex, an assembly of nucleoporins (NUPs), is responsible for the transport of small molecules into and out of the nucleus. To enhance the nucleus uptake, drugs must demonstrate a strong affinity for these proteins. We designed hybrid molecules by integrating active pharmacophores from two classes of drugs. To target nuclear enzyme TopoIIα, pharmacophores derived from Doxorubicin and Pixantrone were tethered with thiosemicarbazones. Similarly, the pharmacophores of Olaparib and Veliparib were fused with thiosemicarbazone or benzothiazoles, respectively, for targeting another nuclear enzyme, PARP-1. Theoretically, we generated four series of compounds with various substituents, producing approximately 20,000 compounds. These compounds were initially docked with the nucleoporin NUP98, along with ~ 500 nucleus-targeted drugs that are either in clinical use or in clinical trials, which served as positive controls. Those compounds that demonstrated binding affinities similar to the positive controls were further scrutinized for additional docking studies with either TopoIIα or PARP-1. This study revealed that nearly 100 compounds exhibited better binding affinities than their parent compounds. Here, we propose to synthesize and characterize in-silico screened top 20 compounds in each class for synergetic anticancer activity with minimal side effects. All synthesized compounds will be tested for their cytotoxicity against various cancer cell lines. The PARP-1-targeted compounds will be tested against cancer cell lines with varying levels of PARP-1 and BRCA-1 gene mutations. Similarly, TopoIIα-targeted compounds will be tested on TopoIIα (+/-) cancer cell lines. This study will be performed at ACTREC, Mumbai, on a payment basis. We will perform in vitro assays for TopoIIα and PARP-1 inhibition on the most active compounds at IISc Bangalore. Additionally, DNA damage and relaxation assay for active compounds in the presence of PARP-1 and TopoIIα will be carried out in our lab. We will also investigate the mode of DNA binding and ROS generation, if any, in our laboratory. The mode of cell death and inhibition of PARP-1 and TopoIIα at the cellular level will be evaluated by a collaborator at South Asian University, Delhi. We will also synthesize selenium analogues of the lead compounds and conduct similar biological studies. Overall, this research proposal would result in a series of novel thiosemicarbazone/benzothiazole hybrids for effective nuclear uptake and selective targeting of TopoIIα or PARP-1.