Creation of tumorigenic human endometrial epithelial cells with intact chromosomes by introducing defined genetic elements

Clinical Cancer Research

Kiyono

et al. 2011

Purpose: Although the KRAS mutation is one of critical genetic alterations in endometrial carcinogenesis, the downstream targets are not known.Experimental Design: In this study, we investigated the molecular targets of KRAS signals, using tumorigenic cells with oncogenic KRAS mutation established from telomerase reverse transcriptase (TERT)-immortalized endometrial epithelial cells.Results: We first confirmed that the RAF-ERK pathway, but not the PI3K-Akt pathway, was activated in KRAS tumorigenic cells. However, the introduction of constitutively active MAP/ERK kinase into immortalized cells to mimic RAF-ERK activation failed to obtain tumorigenic phenotypes, indicating the existence of other carcinogenic pathways triggered by KRAS. Recent evidence suggestive of linkage with KRAS signals prompted us to examine the involvement of NF-kB in endometrial carcinogenesis. We found that the DNAbinding activity of NF-kB was markedly elevated in KRAS tumorigenic cells compared with TERTimmortalized cells. Furthermore, the ability of NF-kB to activate the target gene promoters significantly increased in KRAS tumorigenic cells. Introduction of a mutant IkB that is resistant to degradation and thereby enhances the inhibitory effect on NF-kB largely abrogated the transformed phenotypes of KRAS tumorigenic cells. Thus, oncogenic KRAS signals contributed to the tumorigenic phenotypes of endometrial cells by activating the transcription function of NF-kB.Conclusions: These findings clearly show that NF-kB activation is a novel target of oncogenic KRAS in endometrial carcinogenesis, implying the potential utility of NF-kB inhibitors for endometrial cancer chemoprevention, especially with KRAS mutation.

Section: Cell Culture and In Vitro Growth Assaymentioning

confidence: 99%

Section: Translational Relevancementioning

confidence: 99%

See 1 more Smart Citation

Activation of NF-κB Is a Novel Target of KRAS-Induced Endometrial Carcinogenesis

Mizumoto

Clinical Cancer Research

Kiyono

et al. 2011

“…EM-E6/E7/TERT/RAS cells are transformed cells with tumorigenicity in mice established by the additional introduction of oncogenic mutant K-ras alleles into EM-E6/E7/TERT cells (12). Although parental EM-E6/E7/TERT cells constitutively express weak levels of PR, EM-E6/E7/TERT or EM-E6/E7/TERT/RAS cells were further transfected with retroviral progesterone receptor B (PRB) expression vector (MSCVbsd-PRB) so that these transfectants, named EM-E6/E7/TERT/PR or EM-E6/E7/ TERT/RAS/PR cells, strongly and stably expressed PRB (Fig.…”

Section: Methodsmentioning

confidence: 99%

Forkhead Transcription Factor FOXO1 is a Direct Target of Progestin to Inhibit Endometrial Epithelial Cell Growth

Clinical Cancer Research

Sakaguchi

Kiyono

et al. 2011

Purpose and experimental design: Despite the therapeutic utility of progestin in invasive and preinvasive endometrial neoplasias, the molecular mechanisms through which it exerts inhibitory effects on endometrial epithelial growth are largely unknown. The aim of the study was to clarify the molecular mechanisms of progestin action to endometrial epithelial cells using originally established in vitro and in vivo treatment models for immortalized and transformed endometrial epithelial cell lines that express progesterone receptor.Results: In this model, progestin effectively inhibited the cell growth, inducing G0/G1 arrest rather than apoptosis without p21/WAF-1 induction. Using DNA microarray analysis, we identified 24 genes whose expression increased more than 10-fold on progestin treatment. Of these genes, we paid special attention to forkhead box transcription factor FOXO1, known as a key gene for endometrial decidualization. Progestin markedly induced FOXO1 gene expression mainly in the nuclei in vitro and in vivo. This induction was not due to the canonical activation of FOXO1 via protein dephosphorylation but due to FOXO1 promoter activation and mRNA induction. siRNA inhibition of FOXO1 significantly attenuated the effects of progestin to inhibit endometrial epithelial cell growth. Disrupting Akt activity by the introduction of the dominant negative form of Akt increased nuclear FOXO1 accumulation and enhanced the effect of progestin.Conclusion: These findings suggest that FOXO1 is a direct target of progestin, implicating novel molecular mechanisms of progestin to eradicate endometrial neoplasia.

“…Comparing the cancer predisposition between both fractions is interesting. We have established an in vitro model of endometrial carcinogenesis in which normal endometrial cells can be transformed by introducing defined genetic elements [60], leading to development of cancerous phenotypes [61]. Additionally, some interesting concepts on the origin of CSCs have recently emerged.…”

Section: Where Do Endometrial Cscs Originate?mentioning

confidence: 99%

Endometrial Cancer Stem Cells: Are They a Possible Therapeutic Target?

Curr Obstet Gynecol Rep

2012

The dynamic regeneration of the human endometrium during the menstrual cycle is thought to be supported by a specialized cell population, probably residing in the basal layer, which continues to provide daughter cells with high proliferative potential. This cell population is assumed to have stem cell characteristics. Recent molecular studies have revealed the presence of putative epithelial and stromal stem cells in the endometrium. A cell population with stem cell characteristics also has been identified in malignant tumors and is known as cancer stem cells (CSC). Putative CSCs are prospectively isolated using methods based on either a surface marker or intracellular enzyme activity and then assessed by serial transplantation of sorted subpopulations of tumor cells into immunocompromised mice. Unlike many other tumor types, little information on the characteristics of CSCs in endometrial cancer is available. We and others have demonstrated that prospectively isolated CD133 + cells and/or side population cells in endometrial cancer are capable of initiating tumor formation in immunocompromised mice and recapitulating the phenotype of the original tumor and, therefore, are potential endometrial CSCs. This review summarizes key elements of our understanding of the normal endometrial stem cells and endometrial CSCs and further discusses a potential strategy to target endometrial CSCs in cancer therapy.