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Biology subjects

Oni, T. E.

Publications and source records attributed to Oni, T. E..

2 recordsLinked to original sources
bioRxiv2020

Oncogenic KRAS engages an RSK1/NF1 complex in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a lethal malignancy with limited treatment options. Although activating mutations of the KRAS GTPase are the predominant dependency present in >90% of PDAC patients, targeting KRAS mutants directly has been challenging in PDAC. Similarly, strategies targeting known KRAS downstream effectors have had limited clinical success due to feedback mechanisms, alternate pathways and toxicity due to the targeting of normal tissues. Therefore, identifying additional functionally relevant KRAS interactions in PDAC may allow for a better understanding of feedback mechanisms and unveil new potential therapeutic targets. Here, we used proximity labelling to identify protein interactors of active KRAS in PDAC cells. Fusions of wildtype (BirA-KRAS4B), mutant (BirA-KRAS4BG12D) and non-transforming and cytosolic double mutant (BirA-KRAS4BG12D/C185S) KRAS with the BirA biotin ligase were expressed in murine PDAC cells. Mass spectrometry analysis revealed that RSK1 was enriched among proteins that selectively interacted with membrane-bound KRASG12D. RSK1 required the NF1 and SPRED proteins to interact with KRAS-GTP at the membrane. In both murine and human PDAC lines, membrane-targeted RSK1 was tolerated but inhibited cell proliferation following oncogenic KRAS abrogation to reveal a negative feedback role for membrane-localized RSK1 on wild-type KRAS. Inhibition of the wild-type KRAS, which has been previously proposed to suppress KRAS oncogenesis, may partially explain how RSK1 has been identified as a dependency in some KRAS mutant cells and may provide an additional function for NF1 in tumorigenesis. Significance StatementFor decades, KRAS interactors have been sought after as potential therapeutic targets in KRAS mutant cancers, especially pancreatic adenocarcinoma (PDAC). Our proximity labeling screen with KRAS in PDAC cells highlight RSK1 as a notable mutant-specific interactor. Functionally, we show that RSK1 mediates negative feedback on wild-type KRAS in PDAC cells.

cancer biology↗
bioRxiv2020

DETECTION OF INCIPIENT PANCREATIC CANCER WITH NOVEL TUMOR-SPECIFIC ANTIBODIES IN MOUSE MODELS

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignancy, as 90% of patients do not survive beyond five years from diagnosis. This dismal prognosis is largely due to the advanced stage of the disease at diagnosis, which precludes potentially curative surgical resection. Although early detection strategies hold significant promise for improving patient outcomes, there is still no accurate diagnostic tool to detect incipient PDAC. Here, we sought to develop antibodies for the early detection of PDAC by positron-emission tomography (PET) imaging. Accordingly, we establish a pipeline to generate novel tumor-specific monoclonal antibodies (mAbs) against cell-surface proteins of PDAC patient-derived organoids (PDOs). We identify a panel of 16 tumor organoid-binding antibodies (TOBi-bodies) that display high reactivity to human PDAC tissues but not to matched adjacent normal pancreas. We then employ biochemical, flow cytometric, mass spectrometric, and CRISPR/Cas9-mediated knockout methods to determine the cognate antigens of these TOBi-bodies. We identify two mAbs that bind to tumor-specific variants of the surface protein CEACAM6 and show minimal binding to normal tissues. PET imaging in mouse models using these TOBi-bodies enables the detection of incipient human organoid-derived PDAC tumors that are rather undetectable by palpation or high-resolution ultrasound imaging techniques. We propose that further development of these mAbs as PET radiotracers could facilitate the early detection and accurate staging of PDAC.

cancer biology↗