Piwil2-transfected human fibroblasts are cancer stem cell-like and genetically unstable

Abstract

Uncontrolled cell proliferation and inhibition of apoptosis are considered to be vital for cancer initiation, maintenance, infiltration, metastasis and recurrence after anti-cancer therapy. Here we report the generation of a novel cell line by reprogramming child foreskin fibroblast with the full length apoptosis inhibitor gene PIWIL2. The fibroblasts transfected with PIWIL2 expressed the stem cell markers OCT-4, NANOG, SOX-2, KLF-4 and C-MYC; endoderm marker AFP and GATA6; mesoderm markers ACTA2 and BRACHYURY; and ectoderm markers NESTIN and TUBB3. The karyotype was found to be hyperdiploid. The PIWIL2 transfected fibroblast cells grew into tumorous masses within 5 weeks of subcutaneous injection into adult nude mice. Although the injected cell expressed markers for all three germlines, ectoderm, mesoderm, and endoderm, they did not form teratomas in vivo. This study indicates that the PIWIL2 gene could play a key role in cancer induction and maintenance. This method for generating induced tumorigenic cells (ITGC) provides a new research tool to study oncogenesis that in turn may lead to a better understanding of cancer etiology and the development of novel anti-cancer therapies.

PIWIL-2 and piRNAs are regularly expressed in epithelia of the skin and their expression is related to differentiation

“…PIWIL-2 expression has been shown to be associated with stem cell properties and has been regarded as a potential neoplasia biomarker [41,42,53]. Intriguingly, we could demonstrate that in adult skin, PIWIL-2 is not predominantly expressed in compartments with possible stem cell populations in the epidermis.…”

“…An essential role of miRNAs and long non-coding RNAs in skin wound healing [ 17 ] and differentiation [ 30 , 51 ] has been revealed recently, but a possible role of piRNAs in the skin has not yet been shown. Since PIWIL-2 is known to play a role in the maintenance of germline stem cells as well as in the development of carcinomas [ 27 , 53 ], we set out to look for a possible role of this protein and piRNAs in the skin. We investigated the expression pattern and possible association of PIWIL-2 with epithelial stem cell compartments and neoplasias.…”

Exosomes derived from Piwil2‑induced cancer stem cells transform fibroblasts into cancer‑associated fibroblasts

“…FBs, fibroblasts; Piwil2-iCSC-Exo, exosomes derived from Piwil2-induced cancer stem cells. transfected with the self-renewing gene Piwil2 (36), that served as a CSC model for in vitro experiments. Using this model, it was demonstrated that Piwil2-iCSC-Exo enhance the proliferation, migration and invasion of FBs in vitro.…”

“…Cell lines and cell culture. Piwil2-iCSCs and FBs were obtained from the Chongqing Key Laboratory of Child Urogenital Development and Tissue Engineering (36). The Piwil2-iCSCs were cultured in Dulbecco's modified Eagle's medium (DMEM) supplemented with penicillin/streptomycin and 10% fetal bovine serum (FBS; Gibco; Thermo Fisher Scientific) depleted of bovine exosomes by overnight ultracentrifugation at 100,000 x g, followed by filtration through a 0.2-µm filter (Millipore).…”

“…It has been reported that the expression of Piwil2 in malignant tumors may be related to the incidence, development and prognosis of tumors (33)(34)(35). In a previous study by the authors, a Piwil2 GFP lentiviral vector was used to transduce fibroblasts, and the successfully constructed Piwil2-induced tumor stem cells (Piwil2-iCSC) characterized by self-renewal, multiple differentiation capabilities, cell atypia and tumorigenic properties (36). In this study, to elucidate the role of exosomes derived from CSCs in tumorigenesis and cancer progression, these induced tumor stem cells were used to generate Piwil2-iCSC-Exo and investigate their role in the proliferation, migration and invasion of FBs.…”