Abstract 1645: A new TGF-b pathway reporter mouse for analysis of TGF-β signaling in normal homeostasis and cancer

TGF-βs play a central regulatory role in maintaining homeostasis and coordinating response to injury in the adult animal. Consequently, dysregulation of TGF-β signaling has been implicated in many pathological states, including cancer. Several TGF-β pathway antagonists are now in early phase clinical oncology trials. However, surprisingly little is known about when and where the TGF-β pathway is activated in the adult animal. To address this need, we have generated a TGF-β pathway reporter mouse in which the expression of eGFP is driven by an artificial enhancer element consisting of 6 repeats of a strong Smad3 binding element from the distal region of the JunB promoter (S3 × 6>GFP reporter). This reporter was >10x more sensitive in vitro than the commonly used CAGA12-based reporter. The reporter construct was knocked into the mouse ROSA26 locus using CRISPR technology and a founder line was derived. Whole body fluorescent imaging of an adult female mouse highlighted TGF-β pathway activation in the gastrointestinal tract, lymph nodes, costal cartilage, brown adipose tissue, brain ventricles and choroid plexi, among other tissues. Since high dose pharmacologic inhibition of the TGF-β pathway has previously been associated with cardiac valvulopathy in preclinical toxicology studies, we immunostained heart sections from the reporter mouse for GFP and observed high endogenous TGF-β pathway activation in the atrioventricular valve leaflets. Quantitative IVIS fluorescent imaging of isolated organs confirmed TGF-β pathway activation in many different tissues in the normal adult mouse, with the pancreas showing the highest level of endogenous activation. Interestingly, the level of TGF-β pathway activation in different tissues was highly correlated with the frequency of inactivating mutations in TGF-β pathway components in tumors from the corresponding tissue in humans. This observation suggests that a high level of TGF-β pathway activation in normal tissues may reflect a non-redundant tumor suppressor role for the TGF-β pathway in maintaining homeostasis in those tissues. To specifically address the activation state of the TGF-β pathway during tumorigenesis, we intercrossed the S3 × 6>GFP reporter mouse with the MMTV-PyVT mouse model of metastatic breast cancer. Reporter activity was strongly upregulated in mammary tumors when compared with the surrounding mammary gland. Using cells cultured from the primary tumors, we confirmed that the reporter signal in the tumor cells can be blocked by small molecule antagonists of the TGF-β pathway. This reporter mouse should be a useful tool to assess the cellular location and extent of TGF-β pathway activation during tumor development, and the impact of TGF-β antagonists on TGF-β signaling in tumors and normal tissues.

Citation Format: Yu-an Yang, Christina Stuelten, Youngjae Bahn, Ji-Hyeon Lee, Madhu Gargesha, Hibret Adissu, Mark Simpson, Caroline S. Hill, Sushil G. Rane, Lalage M. Wakefield. A new TGF-b pathway reporter mouse for analysis of TGF-β signaling in normal homeostasis and cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1645.

Genome-wide screening of mouse knockouts reveals novel genes required for normal integumentary and oculocutaneous structure and function

Oculocutaneous syndromes are often due to mutations in single genes. In some cases, mouse models for these diseases exist in spontaneously occurring mutations, or in mice resulting from forward mutatagenesis screens. Here we present novel genes that may be causative for oculocutaneous disease in humans, discovered as part of a genome-wide screen of knockout-mice in a targeted single-gene deletion project. The International Mouse Phenotyping Consortium (IMPC) database (data release 10.0) was interrogated for all mouse strains with integument abnormalities, which were then cross-referenced individually to identify knockouts with concomitant ocular abnormalities attributed to the same targeted gene deletion. The search yielded 307 knockout strains from unique genes with integument abnormalities, 226 of which have not been previously associated with oculocutaneous conditions. Of the 307 knockout strains with integument abnormalities, 52 were determined to have ocular changes attributed to the targeted deletion, 35 of which represent novel oculocutaneous genes. Some examples of various integument abnormalities are shown, as well as two examples of knockout strains with oculocutaneous phenotypes. Each of the novel genes provided here are potentially relevant to the pathophysiology of human integumentary, or oculocutaneous conditions, such as albinism, phakomatoses, or other multi-system syndromes. The novel genes reported here may implicate molecular pathways relevant to these human diseases and may contribute to the discovery of novel therapeutic targets.

Identification of genes required for eye development by high-throughput screening of mouse knockouts

Despite advances in next generation sequencing technologies, determining the genetic basis of ocular disease remains a major challenge due to the limited access and prohibitive cost of human forward genetics. Thus, less than 4,000 genes currently have available phenotype information for any organ system. Here we report the ophthalmic findings from the International Mouse Phenotyping Consortium, a large-scale functional genetic screen with the goal of generating and phenotyping a null mutant for every mouse gene. Of 4364 genes evaluated, 347 were identified to influence ocular phenotypes, 75% of which are entirely novel in ocular pathology. This discovery greatly increases the current number of genes known to contribute to ophthalmic disease, and it is likely that many of the genes will subsequently prove to be important in human ocular development and disease.

Bret Moore et al. from the International Mouse Phenotyping Consortium report the identification of 347 mouse genes that influence ocular phenotypes when knocked out. 75% of the identified genes have not previously been associated with any ocular pathology.

Topical Application of Culture-Expanded CD34+ Umbilical Cord Blood Cells from Frozen Units Accelerates Healing of Diabetic Skin Wounds in Mice

Chronic and nonhealing wounds are constant health issues facing patients with type 2 diabetes. As the incidence of type 2 diabetes mellitus (T2DM) increases, the incidence of chronic wounds and amputations will rise. T2DM is associated with peripheral arterial occlusive disease, which leads to the development of nonhealing skin ulcers after minor trauma. Patients develop severe pain limiting their mobility and ability to work and take care of themselves, thus putting a significant burden on the family and society. CD34+ cells from umbilical cord blood (UCB) grown in fibroblast growth factor-4 (FGF-4), stem cell factor, and Flt3-ligand produced a population of cells that have the ability to proliferate and develop properties enabling them to enhance tissue regeneration. The goal of this study was to assess in vitro cultured CD34+ cells in a setting where they would eventually be rejected so we could isolate paracrine signaling mediated therapeutic effect from the therapeutic effect due to engraftment and differentiation. To achieve this, we used db/db mice as a model for diabetic skin ulcers. Here, we report that in vitro cultured UCB CD34+ cells from frozen units can accelerate wound healing and resulted in the regeneration of full thickness skin. This study demonstrates a new indication for banked UCB units in the area of tissue regeneration. Stem Cells Translational Medicine 2018;7:591-601.

Corrigendum: High-throughput discovery of novel developmental phenotypes

This corrects the article DOI: 10.1038/nature19356.

Cancer incidence profile in sub-Saharan African-born blacks in the United States: Similarities and differences with US-born non-Hispanic blacks

BACKGROUND

Sub-Saharan African-born blacks (ABs) are one of the fastest-growing populations in the United States. However, to the authors' knowledge, data regarding the cancer burden in this group are lacking, which would inform targeted cancer prevention and control.

METHODS

The authors calculated age-standardized proportional incidence ratios (PIRs) comparing the frequency of the top 15 cancers in ABs with that of US-born non-Hispanic blacks (USBs) by sex and region of birth using incidence data for 2000 through 2012 from the Surveillance, Epidemiology, and End Results (SEER 17) program.

RESULTS

Compared with USBs, ABs had significantly higher PIRs of infection-related cancers (liver, stomach, and Kaposi sarcoma), blood cancers (leukemia and non-Hodgkin lymphoma), prostate cancer, and thyroid cancers (females only). For example, the PIR for Kaposi sarcoma in AB versus USB women was 12.06 (95% confidence interval [95% CI], 5.23-18.90). In contrast, ABs had lower PIRs for smoking-related and colorectal cancers (eg, for lung cancer among men, the PIR was 0.30 [95% CI, 0.27-0.34]). Furthermore, cancer occurrence in ABs versus USBs varied by region of birth. For example, the higher PIRs for liver cancer noted among male ABs (PIR, 3.57; 95% CI, 1.79-5.35) and for thyroid cancer in female ABs (PIR, 3.03; 95% CI, 2.03-4.02) were confined to Eastern African-born blacks, whereas the higher PIR for prostate cancer (PIR, 1.90; 95% CI, 1.78, 2.02) was confined to Western African-born blacks.

CONCLUSIONS

The cancer incidence profile of ABs is different from that of USBs and varies by region of birth, suggesting differences in environmental, cultural, social, and genetic factors. The findings of the current study could stimulate etiologic research and help to inform targeted interventions. Cancer 2017;123:3116-24. © 2017 American Cancer Society.

The role of sphingosine-1-phosphate transporter Spns2 in immune system function

Sphingosine-1-phosphate (S1P) is lipid messenger involved in the regulation of embryonic development, immune system functions, and many other physiological processes. However, the mechanisms of S1P transport across cellular membranes remain poorly understood, with several ATP-binding cassette family members and the spinster 2 (Spns2) member of the major facilitator superfamily known to mediate S1P transport in cell culture. Spns2 was also shown to control S1P activities in zebrafish in vivo and to play a critical role in zebrafish cardiovascular development. However, the in vivo roles of Spns2 in mammals and its involvement in the different S1P-dependent physiological processes have not been investigated. In this study, we characterized Spns2-null mouse line carrying the Spns2(tm1a(KOMP)Wtsi) allele (Spns2(tm1a)). The Spns2(tm1a/tm1a) animals were viable, indicating a divergence in Spns2 function from its zebrafish ortholog. However, the immunological phenotype of the Spns2(tm1a/tm1a) mice closely mimicked the phenotypes of partial S1P deficiency and impaired S1P-dependent lymphocyte trafficking, with a depletion of lymphocytes in circulation, an increase in mature single-positive T cells in the thymus, and a selective reduction in mature B cells in the spleen and bone marrow. Spns2 activity in the nonhematopoietic cells was critical for normal lymphocyte development and localization. Overall, Spns2(tm1a/tm1a) resulted in impaired humoral immune responses to immunization. This study thus demonstrated a physiological role for Spns2 in mammalian immune system functions but not in cardiovascular development. Other components of the S1P signaling network are investigated as drug targets for immunosuppressive therapy, but the selective action of Spns2 may present an advantage in this regard.