Effects of Cripto-1 (Cr-1) deletion in NOTCH4/INT3-induced mammary tumorigenesis

• Grant number: 15/20483-1
• Support Opportunities: Scholarships abroad - Research
• Start date: October 27, 2015
• End date: July 26, 2016
• Field of knowledge: Biological Sciences - Biochemistry - Molecular Biology
• Principal Investigator: Maria Cristina Rodrigues Rangel
• Grantee: Maria Cristina Rodrigues Rangel
• Host Investigator: David Scott Salomon
• Host Institution: Instituto do Câncer do Estado de São Paulo Octavio Frias de Oliveira (ICESP). Coordenadoria de Serviços de Saúde (CSS). Secretaria da Saúde (São Paulo - Estado). São Paulo , SP, Brazil
• Institution abroad: National Cancer Institute (NCI), United States

Abstract

Transgenic mice overexpressing Notch4 intracellular domain (Int3) in the mammary gland under the control of the WAP (whey acidic protein) promoter do not lactate and rapidly develop mammary hyperplasias and undifferentiated mammary adenocarcinomas. Considering that the embryonic gene Cripto-1 facilitates the proteolytic intracellular processing of Notch receptors, we sought to investigate the contribution of Cripto-1 in the hyperplasias and tumors that arise in WAP-Int3+/- mice, which carries the activated Notch4-Int3 transgene. We initially created a Cripto-1 haploinsufficient mouse model, WAP-Int3+/-/Cr-1+/LacZ, in which one allele of Cripto-1 was deleted and replaced by a LacZ reporter gene. Preliminary results showed considerable tumor suppressor effects in the Cripto-1 haploinsufficient mice, and the association of the tumor suppressive phenotype with a putative mammary epithelial stem or progenitor cells subpopulation. To address the role of Cripto-1 in the development of Notch4-induced tumorigenesis and more fully identify the population of mammary tumor cells that express endogenous Cripto-1 or lack it, we developed in this project a Cripto-1 complete knockout WAP-Int3+/- mouse model, the WAP-Int3+/-/MMTV-Cre+/-/Cr-1flox/flox, which conditionally lacks the two alleles of Cripto-1 in the mammary gland, by a MMTV-Cre (mouse mammary tumor virus, cre recombinase) mediated deletion of the gene. Considering that Int3 is activated in the mid-pregnant mammary gland, females will be exposed to multiple cycles of pregnancy and monitored for tumor growth and possible rescue of lactation. The frequency of tumors and the latency period for their formation will be analyzed, and the tumors will be collected for histological and molecular analysis to characterize and quantify the differences observed between WAP-Int3+/-/MMTV-Cre+/-/Cr-1flox/flox and WAP-Int3+/- control females. Furthermore, we will test an anticancer agent that targets Cripto-1 and its binding partner, the heat shock protein GRP78, to investigate potential mechanisms to impair Cripto-1 contribution to Notch4-Int3 induced tumorigenesis and the maintenance of a mammary luminal progenitor cells population that is the target for Notch4 transformation.