Background: Nuclear import of proteins is typically mediated by their physical interaction with soluble cytosolic receptor proteins via a nuclear localization signal (NLS). A simple genetic assay to detect active NLSs based on their function in the yeast Saccharomyces cerevisiae has been previously described. In that system, a chimera consisting of a modified bacterial LexA DNA binding domain and the transcriptional activation domain of the yeast Gal4 protein is fused to a candidate NLS. A functional NLS will redirect the chimeric fusion to the yeast cell nucleus and activate transcription of a reporter gene.
Pancreatic cancer has an abysmal 5-year survival rate of 8%, making it a deadly disease with a need for novel therapies. Here we describe a multitargeting heparin-based mimetic, necuparanib, and its antitumor activity in both in vitro and in vivo models of pancreatic cancer. Necuparanib reduced tumor cell proliferation and invasion in a three-dimensional (3D) culture model; in vivo, it extended survival and reduced metastasis. Furthermore, proteomic analysis demonstrated that necuparanib altered the expression levels of multiple proteins involved in cancer-driving pathways including organ development, angiogenesis, proliferation, genomic stability, cellular energetics, and invasion and metastasis. One protein family known to be involved in invasion and metastasis and altered by necuparanib treatment was the matrix metalloprotease (MMP) family. Necuparanib reduced metalloproteinase 1 (MMP1) and increased tissue inhibitor of metalloproteinase 3 (TIMP3) protein levels and was found to increase RNA expression of TIMP3. MMP enzymatic activity was also found to be reduced in the 3D model. Finally, we confirmed necuparanib's in vivo activity by analyzing plasma samples of patients enrolled in a phase I/II study in patients with metastatic pancreatic cancer; treatment with necuparanib plus standard of care significantly increased TIMP3 plasma protein levels. Together, these results demonstrate necuparanib acts as a broad multitargeting therapeutic with in vitro and in vivo antiinvasive and antimetastatic activity.
BoNT/B light chain is a zinc-dependent endopeptidase. After entering its target, the neuronal cell, BoNT/B is responsible for synaptobrevin-2 (VAMP-2) cleavage. This results in reduced neurotransmitter (acetylcholine) release from synaptic vesicles, yielding muscular paralysis. Since the toxin persists in neuronal cells for an extended period, regeneration of VAMP-2 is prevented. We evaluated therapeutic targets to overcome botulinum persistence because early removal would rescue the neuronal cell. The ubiquitination/proteasome cellular pathway is responsible for removing "old" or undesirable proteins. Therefore, we assessed ubiquitination of BoNT/B light chain in vitro, and characterized the effects of ubiquitination modulating drugs, PMA (phorbol 12-myristate 13-acetate) and expoxomicin, on ubiquitination of BoNT/B light chain in neuronal cells. Both drugs altered BoNT/B light chain ubiquitination. Ubiquitination in vitro and in cells decreased the biological activity of BoNT/B light chain. These results further elucidate BoNT protein degradation pathways in intoxicated neuronal cells and mechanisms to enhance toxin removal.
Pancreatic cancer is one of the most aggressive types of cancer, with only about 5% of patients surviving 5 years past the initial diagnosis. Despite advances with new chemotherapy combinations, overall survival outcomes are still dismal due to the cancer's complex pathology. Novel multi-targeted agents or therapeutic combinations able to disrupt the aggressive fibrotic microenvironment and restrict tumor proliferation are a current focus in the field. Necuparanib (formerly M402) is a heparan sulfate-like molecule that binds and inhibits multiple heparin-binding growth factors, chemokines, and adhesion molecules in cancer progression and metastasis and as such has been shown to modulate multiple pathways in tumors. In order to further explore how necuparanib affects the tumor and its microenvironment, a 3-dimensional (3D) culture system mimicking pancreatic cancer was developed containing a co-culture of human pancreatic tumor cells and pancreatic stellate cells, the most abundant stromal cell in the pancreas. Morphological and histological assessment of the 3D tumor spheroids demonstrated that necuparanib inhibits a) pancreatic tumor cell growth, b) pancreatic tumor cell invasion, and c) pancreatic stellate cell growth. Necuparanib's activity in these assays was shown to be dose-dependent. Moreover, using a negative control for necuparanib engineered to lack the ability to bind growth factors, we established that necuparanib's activity is growth factor binding dependent. The ability to inhibit both tumor and stromal cells demonstrates that necuparanib is a very promising multi-targeting agent for difficult-to-treat cancers such as desmoplastic pancreatic tumors. These studies aid in our understanding of the key biological targets and pathways responsible for necuparanib's anti-tumor effects and support the current Phase 2 safety and efficacy study being performed in patients with metastatic pancreatic cancer. Citation Format: Amanda MacDonald, Michelle Priess, Jennifer Curran, Silva Krause. Necuparanib inhibits pancreatic cancer progression and invasion in a 3D tumor and stromal cell co-culture system. [abstract]. In: Proceedings of the AACR Special Conference: Function of Tumor Microenvironment in Cancer Progression; 2016 Jan 7–10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2016;76(15 Suppl):Abstract nr B22.
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