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- All Subjects: small molecule inhibitor
- Creators: Lake, Douglas
Description
Acute Myeloid Leukemia (AML) is a disease that occurs when genomic changes alter expression of key genes in myeloid blood cells. These changes cause them to resume an undifferentiated state, proliferate, and maintain growth throughout the body. AML is commonly treated with chemotherapy, but recent efforts to reduce therapy toxicity have focused on drugs that specifically target and inhibit protein products of the cancer’s aberrantly expressed genes. This method has proved difficult for some proteins because of structural challenges or mutations that confer resistance to therapy. One potential method of targeted therapy that circumvents these issues is the use of small molecules that stabilize DNA secondary structures called G-quadruplexes. G-quadruplexes are present in the promoter region of many potential oncogenes and have regulatory roles in their transcription. This study analyzes the therapeutic potential of the compound GQC-05 in AML. This compound was shown in vitro to bind and stabilize the regulatory G-quadruplex in the MYC oncogene, which is commonly misregulated in AML. Through qPCR and western blot analysis, a GQC-05 mediated downregulation of MYC mRNA and protein was observed in AML cell lines with high MYC expression. In addition, GQC-05 is able to reduce cell viability through induction of apoptosis in sensitive AML cell lines. Concurrent treatment of AML cell lines with GQC-05 and the MYC inhibitor (+)JQ1 showed an antagonistic effect, indicating potential competition in the silencing of MYC. However, GQC-05 is not able to reduce MYC expression significantly enough to induce apoptosis in less sensitive AML cell lines. This resistance may be due to the cells’ lack of dependence on other potential GQC-05 targets that may help upregulate MYC or stabilize its protein product. Three such genes identified by RNA-seq analysis of GQC-05 treated cells are NOTCH1, PIM1, and RHOU. These results indicate that the use of small molecules to target the MYC promoter G-quadruplex is a viable potential therapy for AML. They also support a novel mechanism for targeting other potentially key genetic drivers in AML and lay the groundwork for advances in treatment of other cancers driven by G-quadruplex regulated oncogenes.
ContributorsTurnidge, Megan (Author) / Lake, Douglas (Thesis advisor) / Kim, Suwon (Committee member) / Azorsa, David (Committee member) / Arizona State University (Publisher)
Created2017
Description
Quiescin Sulfhydryl Oxidase 1 (QSOX1) generates disulfide bonds in its client substrates via oxidation of free thiols. Localized to the Golgi and secreted, QSOX1 helps to fold proteins into their active form. Early work with QSOX1 in cancer began with the identification of a peptide from the long form of QSOX1 in plasma from patients with pancreatic ductal adenocarcinoma. Subsequent work confirmed the overexpression of QSOX1 in numerous cancers in addition to pancreatic, including those originating in the breast, lung, brain, and kidney. For my work, I decided to answer the question, “How does inhibition of QSOX1 effect the cancer phenotype?” To answer this I sought to fulfill the following goals A) determine the overexpression parameters of QSOX1 in cancer, B) identify QSOX1 small molecule inhibitors and their effect on the cancer phenotype, and C) determine potential biological effects of QSOX1 in cancer. Antibodies raised against rQSOX1 or a peptide from QSOX1-L were used to probe cancer cells of various origins for QSOX1 expression. High-throughput screening was utilized to identify 3-methoxy-n-[4(1pyrrolidinyl)phenyl]benzamide (SBI-183) as a lead inhibitor of QSOX1 enzymatic activity. Characterization of SBI-183 activity on various tumor cell lines revealed inhibition of viability and invasion in vitro, and inhibition of growth, invasion, and metastasis in vivo, a phenotype that was consistent with QSOX1 shKnockdown cells. Subsequent work identified 3,4,5-trimethoxy-N-[4-(1-pyrrolidinyl)phenyl]benzamide (SPX-009) as an SBI-183 analog with stronger inhibition of QSOX1 enzymatic activity, resulting in a more potent reduction in tumor invasion in vitro. Additional work with QSOX1 shKnockdown and Knockout (KO) cell lines confirmed current literature that QSOX1 is biologically active in modulation of the ECM. These results provide evidence for the master regulatory role of QSOX1 in cancer, making it an attractive chemotherapeutic target. Additionally, the small molecules identified here may prove to be useful probes in further elucidation of QSOX1 tumor biology and biomarker discovery.
ContributorsFifield, Amber (Author) / Lake, Douglas (Thesis advisor) / Ho, Thai (Committee member) / Rawls, Jeffery (Committee member) / Borges, Chad (Committee member) / Arizona State University (Publisher)
Created2020