Pancreatic cancer (PCa) is one of the most lethal malignancies in humans. Gemcitabine is the current standard chemotherapy of advanced PCa but it is still far from optimam and novel therapeutic strategies are urgently needed. Accumulating clinical-trial results are showing that most tumors, particularly solid tumors are multifactorial and are frequently linked to defects in more than one signaling pathway. Therefore, a dual targeting or multi-targeting therapy might be more rational, not only to efficiently eliminate cancer cells, but also to limit the emergence of drug resistance. A method of identifying novel targeting ligands is much warranted. High throughput screening (HTS) of compound collections, derived from natural as well as synthetic sources have been used by the pharmaceutical industry for the identification of drug leads. To make HTS more efficient we used """"""""one-bead one-compound"""""""" (OBOC) combinatorial library method by which up to 75,000 compounds can be screened in 10 cm petri dish in parallel. OBOC library is generated in a unique way of having only one type of compounds on each bead of ~ 100 micron size. It is derived by random split-mix synthesis by coupling various building blocks such as L-amino acids, D-amino acids, unnatural amino acids and small molecules or mixture of all. The generated OBOC libraries can be screened against a variety of biological targets, including live cancer cells. In the past year, we have used three pancreatic cancer cell lines to screen several OBOC combinatorial libraries and identified several D-amino acid containing cyclic peptides that bind preferentially to pancreatic cancer cells but not to immortalized normal hepatocytes. These targeting ligands showed specific binding in ?M range and not inducing apoptosis in cancer cells. However these targeting ligands can be an excellent lead compounds to derive more structure assisted combinatorial libraries to identify high affinity ligands that bind pancreatic cancer cells specifically. These high affinity ligands can be used for imaging and to trap circulating cancer cells in the biological fluids such as blood, pancreatic ascites and stool. In this proposal, we plan to exploit these ligands by developing more focused OBOC libraries, in which low passage pancreatic cancer cell lines and normal immortalized pancreatic ductal cells will be used to screen for high affinity ligands in an ultra-high-throughput manner. The over all aim of this proposal is to identify novel pancreatic cancer-specific targeting ligands that can be used as effective imaging and as drugs delivery agents to treat pancreatic cancer.
The specific aims of this proposal are as follows:
Aim 1. To design and synthesize six focused OBOC libraries, from the lead compound cKMIMRA and cVVKMHKc Aim 2.To identify high affinity pancreatic cancer specific ligands by high-throughput screening OBOC libraries from aim 1.
Aim 3. To evaluate specificity and high affinity binding of selected ligands by tissue microarray and flowcytometry analysis. Time line 12 months 24 months Aim1 To synthesize several OBTC libraries Aim2 HTS stringent screening of high affinity ligands Aim3 Evaluation of specificity and high affinity of selected ligands The out come of this study will generate pancreatic cancer specific high affinity ligands that will be used to write a R21-grants for imaging pancreatic cancer for early detection in collaboration Dr. Maitra, john Hopkins University (letter attached) and identification circulating cancer cells in pancreatic cancer patients in collaboration with Dr. Shiro Uriyama, gasteroenterologist at UC Davis Medical Center at Sacramento. There will be enough data generated through this grant to write an R01-grant to evaluate therapeutic potential of these high-affinity ligands in combination with or without radiometal/ chemotoxin in mouse model and characterization of targeting receptors in pancreatic cancer cells. Currently available conventional chemotherapy and radiotherapy will not differentiate in a great way between normal cells and cancer cells thereby lot of side effects to the body. Scientists are looking various ways to kill cancer cells without harming normal cells. In this research study our goal is to identify targeting ligands (Magic bullets) that are specifically target pancreatic cancer cells and not the normal cells. This is achieved by screening few thousand to million compounds at the same time against the cancer cells by recently developed one-bead-one-compound technolology. These targeting ligands can be used to deliver drugs, toxins or radiometal specifically to cancer cells and not the normal cells. ? ? ?
| Kumaresan, Pappanaicken R; Wang, Yan; Saunders, Mary et al. (2011) Rapid discovery of death ligands with one-bead-two-compound combinatorial library methods. ACS Comb Sci 13:259-64 |
