Induction of pancreatic neoplasia in the KRAS/TP53 Oncopig: preliminary report

ABSTRACTIntroductionFive-year survival (all patients) from pancreatic cancer (PC) is in the range of 10%, and has not changed substantially in decades. Current murine models may not adequately mimic human PC, and can be inadequate for device development, which all may contribute to the lack of progress in PC survival. We attempted PC induction in transgenic swine (expressing KRAS and TP53 mutants) with the ultimate goal of creating a more accurate model of PC.MethodsTransgenic Oncopigs (n = 16, malensrrc.missouri.edu; somatic LSL cassette with TP53R167H and KRASG12D) were injected via laparotomy with AdCre (1010 vp/mL) ± IL-8 (0.5-2 ng; a tumor induction adjunct facilitating adenoviral entry into epithelia and promoting local inflammation) into the main pancreatic duct (MPD; via duodenotomy) or duct to the isolated pancreatic connecting lobe (CL). Subjects were necropsied after ≤10 wk, followed by histology.ResultsA total of 16 OCM subjects underwent an induction procedure. Of these, 14 received pancreatic AdCre injection, and nine of these (64%) developed pancreatic tumor (10 if the very first subject which died prematurely is counted). All of these subjects expired within 2-4 weeks after the tumor induction procedure. All had a similar terminal course: failure to thrive, which was secondary to gastric outlet obstruction, which was secondary to a peripancreatic phlegmon, which was secondary to pancreatitis, which appeared to be secondary to tumor. One additional OCM (no. 1088) had a small amount of extrapancreatic tumor at necropsy when it was euthanized for pneumonia at day 113. None of the OCM subjects that underwent a control injection procedure (no AdCre) nor any of the WT littermates that underwent AdCre injection with or without IL-8 developed pancreatitis.ConclusionThis proof of principle study demonstrated that PC can be induced in the Oncopig, which has inducible expression of activated KRAS and inactive p53 under control of a floxed stop codon. However, induced subjects will need to live longer to yield a useable PC model. Addition of IL-8 may have contributed to the severe pancreatitis and early mortality. Future studies will focus on modulation of pancreatitis and optimization of the survival period.

219 Use of a genetically-engineered swine line to elucidate the role of GnRH-II and its receptor in gilts

The second form of GnRH (GnRH-II) and its receptor (GnRHR-II) are produced in only one livestock species, the pig. Paradoxically, their interaction does not stimulate gonadotropin secretion. Instead, both have been implicated in autocrine/paracrine regulation of steroidogenesis. To elucidate their role in ovarian function, our laboratory generated transgenic swine with ubiquitous knockdown (KD) of GnRHR-II. Blood samples were collected from GnRHR-II KD (n = 8) and littermate control (n = 7) gilts at the onset of estrus (follicular) and 10 d later (luteal). Serum samples were subjected to HPLC-MS/MS to quantify concentrations of 16 steroid hormones. At euthanasia, ovarian weight, ovulation rate and weight of each excised corpus luteum (CL) were recorded; HPLC-MS/MS was also performed on CL tissue. A line (GnRHR-II KD versus control) x phase (follicular versus luteal) interaction was detected for serum progesterone concentrations; levels were reduced in transgenic compared with control gilts during the luteal phase (P = 0.0329). A tendency for a line effect was observed for 11-deoxycorticosterone and 11-deoxycortisol; transgenic females tended to produce less of these corticosteroids (P < 0.10). A phase effect was detected for cortisone, 11-deoxycortisol, cortisol, corticosterone, androstenedione, androsterone, testosterone, estrone and 17β-estradiol (P < 0.05); concentrations were greater in follicular versus luteal samples (P < 0.05). Conversely, 17α-hydroxyprogesterone concentrations were elevated in luteal samples (P < 0.05). Ovarian weight did not differ between lines, although ovulation rate was reduced in GnRHR-II KD versus control gilts (P = 0.0123). However, average CL weight was greater in GnRHR-II KD compared with control females (P < 0.0001); therefore, total CL weight tended to be reduced in transgenic gilts (P = 0.0958). In tissue samples, concentrations of progesterone and estrone tended to be reduced in transgenics females (P ≤ 0.10). Ultimately, these data suggest that GnRH-II and its receptor may help regulate ovulation rate, CL development and progesterone production in gilts. Supported by USDA/NIFA AFRI-ELI predoctoral fellowship (2017-67011-26036; ATD) and AFRI (2017-67015-26508; BRW) funds.