Supplementary Tables 1-4, Figures 1-2 from Identification of Susceptibility Loci in a Mouse Model of KRASG12D-Driven Pancreatic Cancer

Estrogen protects females from hepatocellular carcinoma (HCC). To determine whether this protection is mediated by classic estrogen receptors, we tested HCC susceptibility in estrogen receptor-deficient mice. In contrast to a previous study, we found that diethylnitrosamine induces hepatocarcinogenesis to a significantly greater extent when females lack Esr1, which encodes Estrogen Receptor-α. Relative to wild-type littermates, Esr1 knockout females developed 9-fold more tumors. Deficiency of Esr2, which encodes Estrogen Receptor-β, did not affect liver carcinogenesis in females. Using microarrays and QPCR to examine estrogen receptor effects on hepatic gene expression patterns, we found that germline Esr1 deficiency resulted in the masculinization of gene expression in the female liver. Six of the most dysregulated genes have previously been implicated in HCC. In contrast, Esr1 deletion specifically in hepatocytes of Esr1 conditional null female mice (in which Cre was expressed from the albumin promoter) resulted in the maintenance of female-specific liver gene expression. Wild-type adult females lacking ovarian estrogen due to ovariectomy, which is known to make females susceptible to HCC, also maintained female-specific expression in the liver of females. These studies indicate that Esr1 mediates liver cancer risk, and its control of sex-specific liver gene expression involves cells other than hepatocytes.

We have previously described a mouse model of human posterior polymorphous corneal dystrophy (PPCD) and localized the causative mutation to a 6.2 Mbp region of chromosome 2, termed Ppcd1. We now show that the gene rearrangement linked to mouse Ppcd1 is a 3.9 Mbp chromosomal inversion flanked by 81 Kbp and 542 bp deletions. This recombination event leads to deletion of Csrp2bp Exons 8 through 11, Dzank1 Exons 20 and 21, and the pseudogene Znf133. In addition, we identified translocation of novel downstream sequences to positions adjacent to Csrp2bp Exon 7 and Dzank1 Exon 20. Twelve novel fusion transcripts involving Csrp2bp or Dzank1 linked to downstream sequences have been identified. Eight are expressed at detectable levels in PPCD1 but not wildtype eyes. Upregulation of two Csrp2bp fusion transcripts, as well as upregulation of the adjacent gene, Ovol2, was observed. Absence of the PPCD1 phenotype in animals haploinsufficient for Csrp2bp or both Csrp2bp and Dzank1 rules out haploinsufficiency of these genes as a cause of mouse PPCD1. Complementation experiments confirm that PPCD1 embryonic lethality is due to disruption of Csrp2bp expression. The ocular expression pattern of Csrp2bp is consistent with a role for this protein in corneal development and pathogenesis of PPCD1.

Robert G. McKinnell, The Understanding, Prevention and Control of Human Cancer: The Historic Work and Lives of Elizabeth Cavert Miller and James A. Miller (Leiden and Boston: Brill, 2016), pp. xvi, 196, $50, hardback, ISBN: 9789004286795. - Volume 61 Issue 1

Hepatocellular carcinoma is increasingly important in the United States as the incidence rate rose over the last 30 years. C3HeB/FeJ mice serve as a unique model to study hepatocellular carcinoma tumorigenesis because they mimic human hepatocellular carcinoma with delayed onset, male gender bias, approximately 50% incidence, and susceptibility to tumorigenesis is mediated through multiple genetic loci. Because a human O6-methylguanine-DNA methyltransferase (hMGMT) transgene reduces spontaneous tumorigenesis in this model, we hypothesized that hMGMT would also protect from methylation-induced hepatocarcinogenesis. To test this hypothesis, wild-type and hMGMT transgenic C3HeB/FeJ male mice were treated with two monofunctional alkylating agents: diethylnitrosamine (DEN; 0.025 μmol/g body weight) on day 12 of life with evaluation for glucose-6-phosphatase-deficient (G6PD) foci at 16, 24, and 32 weeks or N-methyl-N-nitrosurea (MNU; 25 mg MNU/kg body weight) once monthly for 7 months starting at 3 months of age with evaluation for liver tumors at 12 to 15 months of age. No difference in abundance or size of G6PD foci was measured with DEN treatment. In contrast, it was unexpectedly found that MNU reduces liver tumor prevalence in wild-type and hMGMT transgenic mice despite increased tumor prevalence in other tissues. hMGMT and MNU protections were additive, suggesting that MNU protects through a different mechanism, perhaps through the cytotoxic N7-alkylguanine and N3-alkyladenine lesions which have low mutagenic potential compared with O6-alkylguanine lesions. Together, these results suggest that targeting the repair of cytotoxic lesions may be a good preventative for patients at high risk of developing hepatocellular carcinoma. Cancer Prev Res; 9(3); 245–52. ©2015 AACR.

A cross-campus, cross-career stage and cross-disciplinary series of discussions at a large public university has produced a series of recommendations for addressing the problems confronting the biomedical research community in the US.

The circadian clock plays a significant role in many aspects of female reproductive biology, including estrous cycling, ovulation, embryonic implantation, onset of puberty, and parturition. In an effort to link cell-specific circadian clocks to their specific roles in female reproduction, we used the promoter that controls expression of Steroidogenic Factor-1 (SF1) to drive Cre-recombinase-mediated deletion of the brain muscle arnt-like 1 (Bmal1) gene, known to encode an essential component of the circadian clock (SF1-Bmal1(-/-)). The resultant SF1-Bmal1(-/-) females display embryonic implantation failure, which is rescued by progesterone supplementation, or bilateral or unilateral transplantation of wild-type ovaries into SF1-Bmal1(-/-) dams. The observation that the central clock, and many other peripheral clocks, are fully functional in this model allows the assignment of the implantation phenotype to the clock in ovarian steroidogenic cells and distinguishes it from more general circadian related systemic pathology (e.g., early onset arthropathy, premature aging, ovulation, late onset of puberty, and abnormal estrous cycle). Our ovarian transcriptome analysis reveals that deletion of ovarian Bmal1 disrupts expression of transcripts associated with the circadian machinery and also genes critical for regulation of progesterone production, such as steroidogenic acute regulatory factor (Star). Overall, these data provide a powerful model to probe the interlocking and synergistic network of the circadian clock and reproductive systems.

Murine hepatocarcinogenesis requires growth hormone (GH). To determine if the GH‐responsive transcription factor STAT5b (signal transducer and activator of transcription 5b) is also required, we compared the hepatic gene expression profiles of global Stat5b null mice to cancer‐resistant mice mutant in the GH pathway—GH‐deficient little and androgen receptor‐null Tfm males. We found a high degree of overlap among Tfm, little, and Stat5b null males. The liver cancer susceptibility of global Stat5b null mice was assessed on three distinct genetic backgrounds: BALB/cJ (BALB), C57BL/6J (B6), and C3H/HeJ (C3H). The effect of Stat5b on hepatocarcinogenesis depended on the genetic background. B6 Stat5b null congenic males and females developed 2.4 times as many tumors as wild‐type (WT) controls (P < 0.002) and the tumors were larger (P < 0.003). In BALB/c congenics, loss of STAT5b had no effect on either sex. C3H Stat5b null congenic males and females were resistant to liver cancer, developing 2.7‐ and 6‐fold fewer tumors, respectively (P < 0.02, 0.01). These results provide the first example of a single gene behaving as both oncogene and tumor suppressor in a given tissue, depending only on the endogenous modifier alleles carried by different genetic backgrounds. © 2014 Wiley Periodicals, Inc.

We set out to better understand the signal transduction pathways that mediate liver tumor promotion by 2,3,7,8-tetrachlorodibenzo-p-dioxn ("dioxin"). To this end, we first employed congenic mice homozygous for either the Ahrb1 or Ahrd alleles (encoding an aryl hydrocarbon receptor (AHR) with high or low binding affinity for dioxin, respectively) and demonstrated that hepatocellular tumor promotion in response to dioxin segregated with the Ahr locus. Once we had genetic evidence for the importance of AHR signaling, we then asked if tumor promotion by dioxin was influenced by "interleukin-1 (IL-1)-like" inflammatory cytokines. The importance of this question arose from our earlier observation that aspects of the acute hepatocellular toxicity of dioxin are dependent upon IL1-like cytokine signaling. To address this issue, we employed a triple knock-out (TKO) mouse model with null alleles at the loci encoding the three relevant receptors for tumor necrosis factors α and β and IL-1α and IL-1β (i.e., null alleles at the Tnfrsf1a, Tnfrsf1b, and Il-1r1 loci). The observation that TKO mice were resistant to the tumor promoting effects of dioxin in liver suggests that inflammatory cytokines play an important step in dioxin mediated liver tumor promotion in the mouse. Collectively, these data support the idea that the mechanism of dioxin acute hepatotoxicity and its activity as a promoter in a mouse two stage liver cancer model may be similar, i.e., tumor promotion by dioxin, like acute hepatotoxicity, are mediated by the linked action of two receptor systems, the AHR and the receptors for the "IL-1-like" cytokines.

Genes that affect a person's chance of developing hepatocellular carcinoma (HCC), as BRCA1 and BRCA2 affect a person's chance of developing breast or ovarian cancer, have been difficult to detect. The vast majority of liver cancers can be attributed to Hepatitis B or C virus infection, aflatoxin exposure, or alcoholic cirrhosis, alone or in combination (Montalto et al., 2002). This high background of predisposing environmental factors makes identifying less penetrant genetic contributors more difficult. Familial patterns of susceptibility to liver cancer independent of environmental factors have helped identify a few monogenic metabolic syndromes (e.g., hemochromatosis; Dragani, 2010). However, the analysis of liver tumors points to a variety of other genes that affect liver tumor development. The patterns of chromosome gain and loss in liver cancers worldwide reveal several regions that are gained or lost in up to 86% of tumors, including gains of 1q, 6p, 8q, and 20q, and losses of 1p, 4q, 6q, 8p, 13q, 16q, and 17p (Lau and Guan, 2005; Chochi et al., 2009; Zhang et al., 2010). Chromosome analyses combined with genome-wide association studies have revealed candidate HCC modifier genes for some of these regions, such as PAPSS1 on chromosome 4q and HCAP1 on chromosome 17p (Wan et al., 2004; Shih et al., 2009).

The construction in the 1990s of high density genetic maps of the mouse and rat based on simple sequence length polymorphisms led to an explosion of activity directed toward the identification of quantitative trait loci (QTLs) that control a broad array of normal and abnormal biology. More than 3,900 mouse and nearly 1,000 rat QTLs have been mapped by linkage analysis in studies of, among others, behavior, bone morphogenesis, cardiovascular function, and metabolism, as well as diseases including arthritis, diabetes, and cancer [1], [2]. The development of cancer is a complex, multi-step process that begins with a genetic or epigenetic event in a normal cell (initiation), followed by expansion and evolution of the initiated cells during the promotion stage, and culminating with the acquisition of malignant phenotypes, including invasiveness and metastatic potential, during tumor progression [3]. That complexity has prompted many investigators, including Hunter and colleagues (whose work is presented in this issue, [4]), to pursue the identification of cancer modifier genes, QTLs that alter cancer development in rodents. Compelling motivations for this work include the expectation that the genes underlying the QTLs will provide paradigms for understanding genetic variation in human cancer risk, that identification of the relevant genes will yield insights into pathways critical for carcinogenesis, and that these genes and the pathways they represent will provide novel targets for intervention to prevent or treat cancer. Nearly 250 QTLs that modify cancer risk or pathogenesis have been mapped in mice or rats [1], [2], [5]. However, despite this wealth of genetic information, only a small handful of these QTLs have been identified at the molecular level, as specific genes or non-coding elements. The paucity of molecular identifications applies more broadly, and Flint et al. estimated that, by 2005, less than 1% of rodent QTLs had been carried to the level of the gene [6]. The slow accrual of gene identifications is a consequence of the long path from QTL to gene (Figure 1). The starting point for most cancer QTL studies is the observation of significant variation in cancer risk among inbred strains. For virtually any tissue site, large (up to 100-fold) differences in the incidence or multiplicity of spontaneous or induced tumors may be found in the literature going back to the development of inbred strains early in the last century. Linkage analysis of segregating backcrosses or intercrosses between a pair of inbred strains with divergent cancer phenotypes may lead to the identification of one or more QTLs that control, for example, tumor incidence, multiplicity, latency [7], [8], or, as in the work by Hunter and colleagues (Faraji et al., this issue [4]), metastatic potential. Other experimental designs, including crosses between congenic or chromosome substitution strains, may be used to increase the power to detect QTLs. An intrinsic limitation of this approach is that, owing to the quantitative, variable phenotype, the precision for mapping QTLs is typically low; even with large crosses and a high density of genetic markers, the resulting 1.5 LOD support interval may be 20 cM (around 40 Mb) and contain hundreds of genes. Mapping QTLs to higher resolution requires the time and resources to produce congenic lines that carry a limited interval of the high (or low) risk donor strain's genome on the genetic background of the other strain, followed by phenotypic analysis of recombinant lines derived from that congenic. This fine mapping may yield intervals of the order of one to a few megabases, with one to 40 potential candidate genes. A caveat to this approach is that genetic complexity, with multiple sub-intervals contributing to the phenotype, has been observed for cancer QTLs more often than not, expanding the hunt for the causative genes. Prioritization of candidates within the interval may be based on sequence analysis, taking advantage of the high density SNP maps available for a large number of strains or the recent whole-genome assemblies available for a handful of strains [9], [10]. Depending on knowledge of the site of action of the QTL (e.g., whether it is cell-autonomous or acts indirectly), gene expression analysis by microarray may also be used to prioritize candidates. The “gold standard” for proof that a particular candidate is the causative gene by transgenesis or allelic substitution by homologous recombination has been achieved in only a few cases, but analysis of gene knockout strains or demonstration of specific genetic or epigenetic alterations in the orthologue in human tumors has more often provided a weight of evidence in favor of a particular candidate. Figure 1 From QTL to causative gene. The fact that metastases account for most cancer-related deaths led Hunter and colleagues to pursue QTLs that controlled the risk for metastasis in a transgenic, Polyoma-middle T (PyMT) model for breast cancer in mice, largely following the path depicted in Figure 1. More than a decade ago, they demonstrated the presence of a metastasis susceptibility gene on chromosome 9 in crosses between NZB and PyMT-FVB mice [7] and validated the existence of this modifier in chromosome substitution strains [8]. Faraji et al. [4] now describe the development and analysis of congenic mouse lines carrying various segments of proximal chromosome 9 from NZB mice on an FVB genetic background, allowing them to narrow the interval for the susceptibility QTL to a 21 megabase region. They used haplotype, DNA sequence, and gene expression data to prioritize the list of candidates and describe biological studies of one of them, Cadm1, in the present paper. Cadm1, also known as Tslc1 (Tumor suppressor in lung cancer 1), is an immunoglobulin superfamily cell adhesion molecule. Based on their studies, the authors hypothesize that Cadm1 expression suppresses metastasis by sensitizing tumor cells to elimination via immune surveillance. Their studies also demonstrate the complexities of identifying QTL genes. Despite the over-expression of Cadm1 in NZB relative to FVB mice and the fact that the NZB chromosome 9 interval enhances metastasis, they found that ectopic expression of this candidate gene suppresses metastasis and that high expression of Cadm1 in tumors is associated with improved survival in women with breast cancer. Thus, one or more additional modifier genes within the interval likely lead to the phenotype of enhanced metastasis in the congenic mice and remain unidentified. The work by Hunter and colleagues represents a substantial investment in time and financial resources, much of which involves mouse breeding and maintenance. The current economic climate makes the launching of projects using similar approaches difficult. Fortunately, over the decade since the inception of the project, new rodent resources and methods have been developed making future analysis of complex traits in rodents more efficient in both time and resources. The Faraji et al. [4] study began with extensive mapping of loci associated with susceptibility to metastasis, which took many years. In the near future, similar work could be done in a single series of phenotyping experiments using new mouse resources such as the Collaborative Cross (CC) [11] or the Diversity Outbred (DO) populations of mice [12]. In addition, once a QTL is fine-mapped, finding the causative genetic element will be facilitated by open access to mouse/rat whole genome sequences for multiple strains [10]. Likewise, validation of candidate genes will no longer require time-consuming production of knockout (KO) mice from engineered embryonic stem cells but can be obtained from various repositories generated from the mouse KOMP project [13], [14]. While the KOMP resources provide a wide variety of mutants, most are on a C57BL/6 background. Often phenotypes must be evaluated on other genetic backgrounds, which requires six to ten generations of backcrossing over a period of one or more years. Alternative approaches are now available for mice and rats that use Zn finger nucleases or TALENS to knockout or replace genes [15]. These technologies are able to produce mouse or rat KO founders in less than 3 months on almost any genetic background. The future for the use of rodent models to unravel the genetic complexity of common disease is expanding due to the intriguing published studies in this area, such as that by Hunter and colleagues, coupled with emerging new powerful genomic technologies and animal resources.

BACKGROUND:Hub proteins are connected through binding interactions to many other proteins. Smad3, a mediator of signal transduction induced by transforming growth factor beta (TGF-β), serves as a hub protein for over 50 protein-protein interactions. Different cellular responses mediated by Smad3 are the product of cell-type and context dependent Smad3-nucleated protein complexes acting in concert. Our hypothesis is that perturbation of this spectrum of protein complexes by mutation of single protein-binding hot-spots on Smad3 will have distinct consequences on Smad3-mediated responses.METHODOLOGY/PRINCIPAL FINDINGS:We mutated 28 amino acids on the surface of the Smad3 MH2 domain and identified 22 Smad3 variants with reduced binding to subsets of 17 Smad3-binding proteins including Smad4, SARA, Ski, Smurf2 and SIP1. Mutations defective in binding to Smad4, e.g., D408H, or defective in nucleocytoplasmic shuttling, e.g., W406A, were compromised in modulating the expression levels of a Smad3-dependent reporter gene or six endogenous Smad3-responsive genes: Mmp9, IL11, Tnfaip6, Fermt1, Olfm2 and Wnt11. However, the Smad3 mutants Y226A, Y297A, W326A, K341A, and E267A had distinct differences on TGF-β signaling. For example, K341A and Y226A both reduced the Smad3-mediated activation of the reporter gene by ∼50% but K341A only reduced the TGF-β inducibilty of Olfm2 in contrast to Y226A which reduced the TGF-β inducibility of all six endogenous genes as severely as the W406A mutation. E267A had increased protein binding but reduced TGF-β inducibility because it caused higher basal levels of expression. Y297A had increased TGF-β inducibility because it caused lower Smad3-induced basal levels of gene expression.CONCLUSIONS/SIGNIFICANCE:Mutations in protein binding hot-spots on Smad3 reduced the binding to different subsets of interacting proteins and caused a range of quantitative changes in the expression of genes induced by Smad3. This approach should be useful for unraveling which Smad3 protein complexes are critical for specific biological responses.

Epidemiological studies indicate that sunlight exposure and vitamin D are each associated with a lower risk of colon cancer. The few controlled supplementation trials testing vitamin D in humans reported to date show conflicting results. We have used two genetic models of familial colon cancer, the ApcPirc/+ (Pirc) rat and the ApcMin/+ (Min) mouse, to investigate the effect of 25-hydroxyvitamin D3 [25(OH)D3] and two analogs of vitamin D hormone on colonic tumors. Longitudinal endoscopic monitoring allowed us to test the efficacy of these compounds in preventing newly arising colonic tumors and in affecting established colonic tumors. 25(OH)D3 and two analogs of vitamin D hormone each failed to reduce tumor multiplicities or alter the growth patterns of colonic tumors in the Pirc rat or the Min mouse.

Abstract Genetic background affects susceptibility to pancreatic ductal adenocarcinoma in the Ela-KRASG12D mouse model. In this model, KRAS oncogene expression is driven by an elastase promoter in acinar cells of the pancreas on an FVB/NTac (FVB) background [FVB-Tg(Ela-KRASG12D)] with the transgene carried on the Y chromosome. Through linkage analysis of crosses between the C57BL/6J (B6), BALB/cJ (BALB), and DBA/2J (D2) inbred strains of mice and resistant FVB-Tg(Ela-KRASG12D), we have identified six susceptibility loci that affect mean preinvasive lesion multiplicity. Markers on chromosome 2 segregated with high tumor multiplicity in all three strains; these loci were designated Prsq1-3 (pancreatic ras susceptibility quantitative trait loci 1-3; combined F2 and N2 LODW, 6.0, 4.1, and 2.7, respectively). Susceptibility loci on chromosome 4, designated Prsq4 and Prsq5, were identified in crosses between FVB transgenic mice and B6 or BALB mice (combined F2 and N2 LODW, 3.6 and 2.9, respectively). A marker on chromosome 12 segregated with tumor multiplicity in a BALB × FVB-Tg(Ela-KRASG12D) cross and was designated Prsq6 (LODW, ∼2.5). B6-Chr YFVB-Tg(Ela-KRASG12D) and BALB-Chr YFVB-Tg(Ela-KRASG12D) consomics, which carry the KRAS transgene on the FVB Y chromosome on an otherwise inbred B6 or BALB background, developed ∼4-fold (B6) and ∼10-fold (BALB) more lesions than FVB-Tg(Ela-KRASG12D) mice. By 12 months of age, 10% of BALB-Chr YFVB-Tg(Ela-KRASG12D) mice developed invasive carcinomas. Our findings provide evidence that regions of chromosomes 2, 4, and 12 influence the development and progression of pancreatic neoplasms initiated by an oncogenic allele of KRAS in mice. Cancer Res; 70(21); 8398–406. ©2010 AACR.

The PPCD1 mouse, a spontaneous mutant that arose in our mouse colony, is characterized by an enlarged anterior chamber resulting from metaplasia of the corneal endothelium and blockage of the iridocorneal angle by epithelialized corneal endothelial cells. The presence of stratified multilayered corneal endothelial cells with abnormal patterns of cytokeratin expression are remarkably similar to those observed in human posterior polymorphous corneal dystrophy (PPCD) and the sporadic condition, iridocorneal endothelial syndrome. Affected eyes exhibit epithelialized corneal endothelial cells, with inappropriate cytokeratin expression and proliferation over the iridocorneal angle and posterior cornea. We have termed this the "mouse PPCD1" phenotype and mapped the mouse locus for this phenotype, designated "Ppcd1", to a 6.1 Mbp interval on Chromosome 2, which is syntenic to the human Chromosome 20 PPCD1 interval. Inheritance of the mouse PPCD1 phenotype is autosomal dominant, with complete penetrance on the sensitive DBA/2J background and decreased penetrance on the C57BL/6J background. Comparative genome hybridization has identified a hemizygous 78 Kbp duplication in the mapped interval. The endpoints of the duplication are located in positions that disrupt the genes Csrp2bp and 6330439K17Rik and lead to duplication of the pseudogene LOC100043552. Quantitative reverse transcriptase-PCR indicates that expression levels of Csrp2bp and 6330439K17Rik are decreased in eyes of PPCD1 mice. Based on the observations of decreased gene expression levels, association with ZEB1-related pathways, and the report of corneal opacities in Csrp2bp(tm1a(KOMP)Wtsi) heterozygotes and embryonic lethality in nulls, we postulate that duplication of the 78 Kbp segment leading to haploinsufficiency of Csrp2bp is responsible for the mouse PPCD1 phenotype. Similarly, CSRP2BP haploinsufficiency may lead to human PPCD.

Downloa etic background affects susceptibility to pancreatic ductal adenocarcinoma in the Ela-KRAS mouse . In this model, KRAS oncogene expression is driven by an elastase promoter in acinar cells of the panon an FVB/NTac (FVB) background [FVB-Tg(Ela-KRAS)] with the transgene carried on the Y chroe. Through linkage analysis of crosses between the C57BL/6J (B6), BALB/cJ (BALB), and DBA/2J (D2) strains of mice and resistant FVB-Tg(Ela-KRAS), we have identified six susceptibility loci that affect preinvasive lesion multiplicity. Markers on chromosome 2 segregated with high tumor multiplicity in all strains; these loci were designated Prsq1-3 (pancreatic ras susceptibility quantitative trait loci 1-3; comF2 and N2 LODW, 6.0, 4.1, and 2.7, respectively). Susceptibility loci on chromosome 4, designated and Prsq5, were identified in crosses between FVB transgenic mice and B6 or BALB mice (combined N2 LODW, 3.6 and 2.9, respectively). A marker on chromosome 12 segregated with tumor multiplicity in B × FVB-Tg(Ela-KRAS) cross and was designated Prsq6 (LODW, ∼2.5). B6-Chr Y and Chr Y consomics, which carry the KRAS transgene on the FVB Y chromosome on an ise inbred B6 or BALB background, developed ∼4-fold (B6) and ∼10-fold (BALB) more lesions than g(Ela-KRAS) mice. By 12 months of age, 10% of BALB-Chr Y mice developed invarcinomas. Our findings provide evidence that regions of chromosomes 2, 4, and 12 influence the develsive ca opment and progression of pancreatic neoplasms initiated by an oncogenic allele of KRAS in mice. Cancer Res; 70(21); 8398–406. ©2010 AACR.

nloaded etic background affects susceptibility to pancreatic ductal adenocarcinoma in the Ela-KRAS mouse . In this model, KRAS oncogene expression is driven by an elastase promoter in acinar cells of the panon an FVB/NTac (FVB) background [FVB-Tg(Ela-KRAS)] with the transgene carried on the Y chroe. Through linkage analysis of crosses between the C57BL/6J (B6), BALB/cJ (BALB), and DBA/2J (D2) strains of mice and resistant FVB-Tg(Ela-KRAS), we have identified six susceptibility loci that affect preinvasive lesion multiplicity. Markers on chromosome 2 segregated with high tumor multiplicity in all strains; these loci were designated Prsq1-3 (pancreatic ras susceptibility quantitative trait loci 1-3; comF2 and N2 LODW, 6.0, 4.1, and 2.7, respectively). Susceptibility loci on chromosome 4, designated and Prsq5, were identified in crosses between FVB transgenic mice and B6 or BALB mice (combined N2 LODW, 3.6 and 2.9, respectively). A marker on chromosome 12 segregated with tumor multiplicity in B × FVB-Tg(Ela-KRAS) cross and was designated Prsq6 (LODW, ∼2.5). B6-Chr Y and Chr Y consomics, which carry the KRAS transgene on the FVB Y chromosome on an ise inbred B6 or BALB background, developed ∼4-fold (B6) and ∼10-fold (BALB) more lesions than g(Ela-KRAS) mice. By 12 months of age, 10% of BALB-Chr Y mice developed invarcinomas. Our findings provide evidence that regions of chromosomes 2, 4, and 12 influence the develsive ca opment and progression of pancreatic neoplasms initiated by an oncogenic allele of KRAS in mice. Cancer Res; 70(21); 8398–406. ©2010 AACR.