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dc.contributor.advisorSingh, Anuragen_US
dc.contributor.authorHua, Kevin Leeen_US
dc.date.accessioned2019-11-20T20:06:14Z
dc.date.available2019-11-20T20:06:14Z
dc.date.issued2019
dc.identifier.urihttps://hdl.handle.net/2144/38527
dc.description.abstractSpleen tyrosine kinase (SYK) regulates mitogenic signaling, inflammatory responses and cell fate in a number of diverse cell types. KRAS is a proto-oncogene that controls cell growth and proliferation through several mitogenic pathways. In pancreatic cancer, KRAS is frequently mutated, resulting in constitutive activation in 90% of pancreatic cancer cell lines. We previously showed that SYK is highly expressed in a subset of KRAS-mutant pancreatic ductal adenocarcinoma (PDAC) cell lines. We demonstrated that SYK kinase inhibition with PRT062607 (SYKi) causes decreased cell proliferation of PDAC cell lines. Furthermore, combined SYKi and MEK inhibitor (MEKi) treatment promotes additive effects on suppression of PDAC cell proliferation and clonogenic growth. Mechanistically, SYK activates the mTORC1 kinase complex as shown by reduced phosphorylation of ribosomal S6 protein and its upstream kinase p70 S6 kinase (p70S6K) following SYKi treatment in PDAC cell lines. SYK-mediated mTORC1 activation occurs independently of MEK/ERK and PI3K/AKT effector signaling pathways. The mTORC1 complex suppresses lysosome biogenesis and macroautophagy (autophagy). Consequently, mTORC1 suppression via SYK inhibition or shRNA-mediated depletion causes accumulation of autolysosomes. These effects are mediated by the enhanced nuclear localization of MITF, a key transcriptional regulator of genes involved in lysosome biogenesis and autophagy pathway activation. In summary, SYK positively regulates mTORC1 activation in a subset of PDAC cell lines to suppress hyperactivation of autophagy. These findings open new avenues for further exploration of SYK as a critical regulator of the autophagy pathway in KRAS/mTORC1-dependent PDAC, and how this may be exploited for therapeutic benefit.en_US
dc.language.isoen_US
dc.subjectMolecular biologyen_US
dc.subjectAutophagyen_US
dc.subjectMITFen_US
dc.subjectmTORen_US
dc.subjectPancreatic canceren_US
dc.subjectSYKen_US
dc.titleThe SYK tyrosine kinase suppresses autolysosome biogenesis via activation of mTORC1 in pancreatic cancer cell linesen_US
dc.typeThesis/Dissertationen_US
dc.date.updated2019-10-07T19:01:28Z
etd.degree.nameDoctor of Philosophyen_US
etd.degree.leveldoctoralen_US
etd.degree.disciplinePharmacologyen_US
etd.degree.grantorBoston Universityen_US
dc.identifier.orcid0000-0003-2186-6674


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