Haploinsufficiency in the Prometastasis Kiss1 Receptor Gpr54 Delays Breast Tumor Initiation, Progression, and Lung Metastasis

Abstract

Activation of KISS1 receptor (KISS1R or GPR54) by its ligands (kisspeptins) regulates a diverse function both in normal physiology and pathophysiology. In cancer, KISS1-induced KISS1R signaling is known to inhibit tumor angiogenesis and metastasis. However, roles of KISS1 and KISS1R in earlier stages of tumor progression and metastasis in vivo are still unknown. In this study, we demonstrate a critical role for Kiss1r in early stages of tumor progression using mouse tumor models. PyMT/Kiss1r mice with different Kiss1r genotypes were obtained by crossing MMTV-PyMT transgenic mouse with Kiss1r heterozygous mouse (Kiss1r+/−). Kiss1r heterozygosity attenuated breast tumor initiation, growth, latency, multiplicity and metastasis in MMTV-PyMT/Kiss1r+/− mouse models. To confirm the effects of Kiss1r in tumor progression and limit any effect of endogenous hormones, we isolated primary tumor cells from PyMT/Kiss1r+/+ or PyMT/Kiss1r+/− mice and performed in vitro and in vivo tumorigenesis assays. Kiss1r heterozygosity inhibited PyMT-induced in vitro tumorigeneity and in vivo tumor growth in NOD.SCID/NCr mice. To understand the underlying mechanism, we showed that activation of KISS1R by kisspeptin-10 led to RhoA activation and RhoA-dependent gene expression through Gαq-p63RhoGEF signaling pathway. Furthermore, anchorage-independent growth was tightly linked to the dosage-dependent regulation of RhoA by KISS1R. When MCF10A cells overexpressing H-RasV12 were subjected to in vitro tumorigenesis assays, knockdown of KISS1R or inactivation of RhoA in MCF10A cells reduced Ras-induced anchorage-independent growth, similar to our data obtained from PyMT-Kiss1r+/− mouse models. Altogether, we conclude that Kiss1r haploinsufficiency delays breast tumor initiation, progression and metastasis through its downstream Gαq-p63RhoGEF-RhoA signaling pathway.

KISS1R Induces Invasiveness of Estrogen Receptor-Negative Human Mammary Epithelial and Breast Cancer Cells

“…In 3D Matrigel cultures of MCF10A cells, we found that exogenous and endogenous KISS1R in exhibited a similar localization pattern at the cell surface membranes and intracellularly ( Figure 1D). This localization was consistent with what was previously reported for KISS1R in MCF10A cells (30).…”

“…Using a Kiss1r heterozygous (Kiss1r ϩ/Ϫ ) mouse model and mouse mammary tumor virus-polyoma virus middle T antigen (murine mammary tumor virus-polyoma middle T-antigen)-induced breast cancer, this study revealed that a loss of KISS1R attenuated breast tumor initiation, growth, and metastasis compared with the polyoma middle T-antigen/ Kiss1r ϩ/ϩ mice (30). Additionally, KISS1R was depleted in H-RasV12-transformed MCF10A cells, a nonmalignant human mammary epithelial cell model that endogenously expresses KISS1R.…”

“…Additionally, KISS1R was depleted in H-RasV12-transformed MCF10A cells, a nonmalignant human mammary epithelial cell model that endogenously expresses KISS1R. This resulted in a reduction in anchorage-independent colony formation, suggesting that human KISS1R plays a key role in Ras-induced MCF10A cell tumorigenesis (30). However, whether KISS1R signaling alone induces an oncogenic phenotype in the nontransformed MCF10A cells or stimulates breast cancer cell invasion in vivo is unknown.…”

GPR116, an Adhesion G-Protein–Coupled Receptor, Promotes Breast Cancer Metastasis via the Gαq-p63RhoGEF-Rho GTPase Pathway

“…The PCR product was cloned into the lentiviral vector pLVX-IRESZsGreen1. The constitutively active mutants of RhoA, Rac1, and Gq were cloned as previously described (21). Full-length RGS2 and the RGS domain of p115RhoGEF (including amino acid residues 1-252) were amplified by PCR and cloned into the EcoR1/BamH1 site of p3ÂFLAG-CMVÔ-10.…”

Kisspeptin/KISS1R System in Breast Cancer

“…A recent landmark study established a role for KP/KISS1R signaling in regulating breast cancer metastasis using a mouse mammary tumor virus-polyoma virus middle T antigen (MMTV-PyMT) model63. In this model, the transformation of the mammary epithelium leads to the development of multifocal mammary adenocarcinomas and metastatic lesions in the lymph nodes and in the lungs.…”