Browsing by Author "Nwani, Nkechiyere G."

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    A Novel ALDH1A1 Inhibitor Targets Cells with Stem Cell Characteristics in Ovarian Cancer.
    (MDPI, 2019-04-08) Nwani, Nkechiyere G.; Condello, Salvatore; Wang, Yinu; Swetzig, Wendy M.; Barber, Emma; Matei, Daniela; Biochemistry and Molecular Biology, School of Medicine
    A small of population of slow cycling and chemo-resistant cells referred to as cancer stem cells (CSC) have been implicated in cancer recurrence. There is emerging interest in developing targeted therapeutics to eradicate CSCs. Aldehyde-dehydrogenase (ALDH) activity was shown to be a functional marker of CSCs in ovarian cancer (OC). ALDH activity is increased in cells grown as spheres versus monolayer cultures under differentiating conditions and in OC cells after treatment with platinum. Here, we describe the activity of CM37, a newly identified small molecule with inhibitory activity against ALDH1A1, in OC models enriched in CSCs. Treatment with CM37 reduced OC cells' proliferation as spheroids under low attachment growth conditions and the expression of stemness-associated markers (OCT4 and SOX2) in ALDH+ cells fluorescence-activated cell sorting (FACS)-sorted from cell lines and malignant OC ascites. Likewise, siRNA-mediated ALDH1A1 knockdown reduced OC cells' proliferation as spheres, expression of stemness markers, and delayed tumor initiation capacity in vivo. Treatment with CM37 promoted DNA damage in OC cells, as evidenced by induction of γH2AX. This corresponded to increased expression of genes involved in DNA damage response, such as NEIL3, as measured in ALDH+ cells treated with CM37 or in cells where ALDH1A1 was knocked down. By inhibiting ALDH1A1, CM37 augmented intracellular ROS accumulation, which in turn led to increased DNA damage and reduced OC cell viability. Cumulatively, our findings demonstrate that a novel ALDH1A1 small molecule inhibitor is active in OC models enriched in CSCs. Further optimization of this new class of small molecules could provide a novel strategy for targeting treatment-resistant OC.
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    Small Molecules Target the Interaction between Tissue Transglutaminase and Fibronectin
    (American Association for Cancer Research, 2019-06-01) Sima, Livia Elena; Yakubov, Bakhtiyor; Zhang, Sheng; Condello, Salvatore; Grigorescu, Arabela A.; Nwani, Nkechiyere G.; Chen, Lan; Schiltz, Gary E.; Arvanitis, Constandina; Zhang, Zhong-Yin; Matei, Daniela; Medicine, School of Medicine
    Tissue transglutaminase (TG2) is a multi-functional protein, with enzymatic, GTP-ase and scaffold properties. TG2 interacts with fibronectin (FN) through its N-terminus domain, stabilizing integrin complexes, which regulate cell adhesion to the matrix. Through this mechanism, TG2 participates in key steps involved in metastasis in ovarian and other cancers. High throughput screening identified several small molecule inhibitors (SMIs) for the TG2/FN complex. Rational medicinal chemistry optimization of the hit compound (TG53) led to second generation analogues (MT1–6). ELISA demonstrated that these analogues blocked TG2/FN interaction and bio-layer interferometry (BLI) showed that the SMIs bound to TG2. The compounds also potently inhibited cancer cell adhesion to FN and decreased outside-in signaling mediated through the focal adhesion kinase (FAK). Blockade of TG2/FN interaction by the small molecules caused membrane ruffling, delaying the formation of stable focal contacts and mature adhesions points and disrupted organization of the actin cytoskeleton. In an in vivo model measuring intraperitoneal (ip) dissemination, MT4 and MT6 inhibited the adhesion of ovarian cancer (OC) cells to the peritoneum. Pre-treatment with MT4 also sensitized OC cells to paclitaxel. The data support continued optimization of the new class of SMIs that block the TG2/FN complex at the interface between cancer cells and the tumor niche.