In vivo functional studies of tumor-specific retrogene NanogP8 in transgenic animals

Abstract

The current study was undertaken to investigate potential oncogenic functions of NanogP8, a tumor-specific retrogene homolog of Nanog (expressed in pluripotent cells), in transgenic animal models. To this end, human primary prostate tumor-derived NanogP8 was targeted to the cytokeratin 14 (K14) cellular compartment, and two lines of K14-NanogP8 mice were derived. The line 1 animals, expressing high levels of NanogP8, experienced perinatal lethality and developmental abnormalities in multiple organs, including the skin, tongue, eye, and thymus in surviving animals. On postnatal day 5 transgenic skin, for example, there was increased c-Myc expression and Ki-67+ cells accompanied by profound abnormalities in skin development such as thickened interfollicular epidermis and dermis and lack of hypodermis and sebaceous glands. The line 3 mice, expressing low levels of NanogP8, were grossly normal except cataract development by 4–6 mo of age. Surprisingly, both lines of mice do not develop spontaneous tumors related to transgene expression. Even more unexpectedly, high levels of NanogP8 expression in L1 mice actually inhibited tumor development in a two-stage chemical carcinogenesis model. Mechanistic studies revealed that constitutive NanogP8 overexpression in adult L1 mice reduced CD34+α6+ and Lrig-1+ bulge stem cells, impaired keratinocyte migration, and repressed the expression of many stem cell-associated genes, including Bmp5, Fgfr2, Jmjd1a, and Jun. Our study, for the first time, indicates that transgenically expressed human NanogP8 is biologically functional, but suggests that high levels of NanogP8 may disrupt normal developmental programs and inhibit tumor development by depleting stem cells.

Pluripotency factor Nanog is tumorigenic by deregulating DNA damage response in somatic cells

“…23 By expressing a Nanog pseudogene NANOGP8 in the mouse skin, it inhibits the skin tumorigenesis induced by chemical carcinogen, suggesting that Nanog might be a tumor suppressor. 33 Our findings that Nanog activates p53 in the skin cells to induce the differentiation of progenitor cells could explain this apparent discrepancy. In this context, when compared with other tissues, skin has a distinct response to the ectopic expression of oncogene, namely oncogene-induced differentiation response for avoiding tumorigenesis.…”

Development of a Fluorescent Reporter System to Delineate Cancer Stem Cells in Triple-Negative Breast Cancer

“…The ability of GFP+ cells to form tumorspheres demonstrated that enriching for GFP+ cells more specifically isolated self‐renewing TNBC CSCs than the use of other paradigms, including enrichment by CD24 − /CD44+, CD49f hi , and ALDH + . We also show that our model based on the promoter activity of the embryonic stem cell transcription factor NANOG has the conceptual advantage of being able to define and functionally characterize CSCs in a more rigorous manner compared with the other established paradigms . The reporter system that we have developed tracks NANOG promoter activity.…”

NANOG reprograms prostate cancer cells to castration resistance via dynamically repressing and engaging the AR/FOXA1 signaling axis

“…A causal role of NANOG in tumorigenesis has been demonstrated not only by loss- and gain-of-function studies in cancer cells [1, 3, 9] but also by, recently, CRISPR/Cas9-mediated knockout [31] and genetic mouse model [28, 32, 33,34] studies. In addition to constitutive expression of NANOG in a small subset of cancer cells, NANOG may also be induced by tumor microenvironments such as inflammatory cytokines and hypoxia [27, 30, 35].…”