Our Research
|
Role of Ferritinophagy in Pancreatic Cancer
Recent work has shown that pancreatic cancers have a distinct dependence on autophagy (a cellular catabolic pathways) and that inhibition leads to DNA damage and metabolic defects leading to growth suppression. The unique importance of autophagy in pancreatic cancer suggests that there may be a subset of proteins that are specifically targeted by autophagy for degradation, which would promote proliferation and survival. To identify novel proteins degraded by autophagy in pancreatic cancer, we purified autophagosomes from pancreatic cancer cell lines and employed quantitative mass spectrometry-based proteomics. One of the most highly enriched autophagosomal proteins was NCOA4. Importantly, interaction proteomics revealed ferritin heavy and light chains (FTH1, FTL) as high confidence interacting proteins. Ferritin forms a complex of 24 subunits of light and heavy chains that is capable of storing up to 4,500 iron atoms. When iron levels in the cell are low, ferritin is degraded allowing the release of iron for use by the cell. Ferritin is degraded in the lysosome and recent evidence implicated autophagy in the process; however, the mechanism underlying this activity remained unclear. Our work identified NCOA4 as the selective autophagy receptor for ferritin autophagy (ferritinophagy) revealing the mechanism of how ferritin is degraded to regulate bioavailable iron levels (Mancias et al., Nature 2014) (Mancias et al., Elife 2015). Given the reliance of multiple cancers, including pancreatic cancer, on both high levels of autophagy as well as iron, understanding the role of NCOA4 in pancreatic cancer may reveal a new therapeutic approach. However, the role of ferritinophagy in the larger context of organismal iron metabolism may limit the therapeutic index of such a therapy; therefore, understanding the physiologic role of NCOA4 will be equally important. We will take an integrated biochemical, cell biologic, and in vivo approach in order to answer fundamental questions of the role of NCOA4-mediated ferritinophagy in pancreatic cancer and in systemic iron homeostasis (Santana-Codina et al. Cancer Discovery 2022). |
Selective Autophagy in Pancreatic Cancer
Using our quantitative autophagosomal proteomics methodology, we determined the most robust list of autophagosome proteins to date (Mancias et al., Nature 2014). Investigating pancreatic cancer specific autophagosomal candidates may reveal insights into how pancreatic cancer utilizes autophagy. Candidates will be characterized using an integrated proteomic, biochemical, and cell biologic approach. Furthermore, as we know little about the autophagosome machinery for selective autophagy (mitophagy, etc.), we will perform quantitative autophagosomal proteomics after various selective autophagy stimuli. These studies will yield further insights into autophagy biology (Mancias et al., JMB 2016). |
Quantitative Temporal Proteomics to identify targetable adaptations and resistance to (K)RAS inhibitors
While considered undruggable for 40 years, recent advances have led to the development of mutant allele-specific KRAS and pan-RAS inhibitors (KRASi) that demonstrate activity in PDAC patients in early clinical trials. However, resistance will prevent KRASi monotherapies from producing durable responses. There is an urgent need to understand how to effectively implement KRASi in combinations to prevent or circumvent resistance. To identify pathways of adaptation to KRASi and predict drug combinations that circumvent resistance, we are using mass-spectrometry-based quantitative temporal proteomics (Santana-Codina et al. Cell Reports 2020) to profile the proteomic response to KRASi in pancreatic cellular, organoid, and in vivo models. Based on these proteomic data, we will identify KRASi combinatorial regimens with potential therapeutic utility. |
Identifying the pancreatic tumor MHC-I ligandome in response to ionizing radiation for combination radiation-immunotherapy approaches
Radiation therapy has known stimulatory effects on anti-tumor CD8+ T cell immunity against both primary tumors and metastatic tumors distant from the primary irradiation site when combined with checkpoint blockade immunotherapy (abscopal effect). Here we aim to answer major questions regarding radiation-induced immune remodeling in pancreatic cancer: what are the MHC-I ligands pancreatic tumor cells present in response to ionizing radiation that stimulate CD8+ T cell mediated killing? To answer this question, we will use an innovative and cutting-edge combination of mass spectrometry-based quantitative peptidomics and proteomics, mouse models of PDAC, next-generation sequencing, bioinformatics, and targeted immune stimulation experiments. To that end, we have already developed an innovative multiplexed quantitative mass spectrometry-based approach towards identifying MHC-I ligands (Murphy, Yu et al, Analytical Chemistry 2019). |