Dube, John R.

Abstract Glycogen synthase kinase-3 (GSK3) is a ubiquitously expressed serine-threonine protein kinase involved in multiple cellular functions ranging from the control of glycogen metabolism to transcriptional regulation. We have previously demonstrated that GSK-3β is overexpressed in human pancreatic ductal adenocarcinoma (PDAC) and aberrant nuclear accumulation of GSK-3β serves as a hallmark of poorly differentiated PDAC. Moreover, genetic ablation of GSK-3β or GSK-3 inhibition led to PDAC tumor cell killing, identifying GSK-3β as a therapeutic target in PDAC. Herein, we describe a novel GSK-3 inhibitor, 9-ING-41. The effect of 9-ING-41 on tumor cell growth was tested using several PDAC and patient-derived xenograft (PDX) cell lines in vitro and in vivo using an orthotopic pancreatic cancer animal model. Interestingly, 9-ING-41 treatment resulted in the stabilization of cyclin B levels as well as enhanced serine-10 phosphorylated histone H3 (pS10HH3) and consequently M phase arrest and blocked mitotic exit. The prolonged M phase arrest induced mitotic catastrophe in pancreatic cancer cell lines and inhibited in vitro colony formation. An in vivo orthotopic pancreatic cancer animal model study using PDX-derived cell lines demonstrated that 9-ING-41 hindered tumor growth in combination with several standard chemotherapeutic agents. Significantly, we found that 9-ING-41 treatment impaired the DNA damage response pathway activated by Gemcitabine in pancreatic cancer cell lines. In conclusion, our study indicates that GSK-3 plays an important role in pancreatic cancer progression and 9-ING-41 in combination with existing gemcitabine or irinotecan could be a new strategy for treating patients with PDAC. Citation Format: Li Ding, Jin-san Zhang, John R. Dube, Vijay S. Madamsetty, Daniel M. Schmitt, Debabrata Mukhopadhyay, Daniel D. Billadeau. The glycogen synthase kinase-3 inhibitor, 9-ING-41, synergizes with chemotherapy to inhibit pancreatic tumor growth in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2926.

OBJECT Despite a promising outlook, existing intraspinal microstimulation (ISMS) techniques for restoring functional motor control after spinal cord injury are not yet suitable for use outside a controlled laboratory environment. Thus, successful application of ISMS therapy in humans will require the use of versatile chronic neurostimulation systems. The objective of this study was to establish proof of principle for wireless control of ISMS to evoke controlled motor function in a rodent model of complete spinal cord injury. METHODS The lumbar spinal cord in each of 17 fully anesthetized Sprague-Dawley rats was stimulated via ISMS electrodes to evoke hindlimb function. Nine subjects underwent complete surgical transection of the spinal cord at the T-4 level 7 days before stimulation. Targeting for both groups (spinalized and control) was performed under visual inspection via dorsal spinal cord landmarks such as the dorsal root entry zone and the dorsal median fissure. Teflon-insulated stimulating platinum-iridium microwire electrodes (50 μm in diameter, with a 30- to 60-μm exposed tip) were implanted within the ventral gray matter to an approximate depth of 1.8 mm. Electrode implantation was performed using a free-hand delivery technique (n = 12) or a Kopf spinal frame system (n = 5) to compare the efficacy of these 2 commonly used targeting techniques. Stimulation was controlled remotely using a wireless neurostimulation control system. Hindlimb movements evoked by stimulation were tracked via kinematic markers placed on the hips, knees, ankles, and paws. Postmortem fixation and staining of the spinal cord tissue were conducted to determine the final positions of the stimulating electrodes within the spinal cord tissue. RESULTS The results show that wireless ISMS was capable of evoking controlled and sustained activation of ankle, knee, and hip muscles in 90% of the spinalized rats (n = 9) and 100% of the healthy control rats (n = 8). No functional differences between movements evoked by either of the 2 targeting techniques were revealed. However, frame-based targeting required fewer electrode penetrations to evoke target movements. CONCLUSIONS Clinical restoration of functional movement via ISMS remains a distant goal. However, the technology presented herein represents the first step toward restoring functional independence for individuals with chronic spinal cord injury.