Differentially expressed genes of reprogrammed human pluripotent stem cells in breast cancer

Pluripotent Conversion of Muscle Stem Cells Without Reprogramming Factors or Small Molecules

Muscle derived stem cells (MDSCs) are multipotent stem cells that can differentiate into several lineages including skeletal muscle precursor cells. Here, we show that MDSCs from myostatin null mice (Mstn (-/-) ) can be readily induced into pluripotent stem cells without using reprogramming factors. Microarray studies revealed a strong upregulation of markers like Leukemia Inhibitory factor (LIF) and Leukemia Inhibitory factor receptor (LIFR) in Mstn (-/-) MDSCs as compared to wild type MDSCs (WT-MDSCs). Furthermore when cultured in mouse embryonic stem cell media with LIF for 95 days, Mstn (-/-) MDSCs formed embryonic stem cell (ES) like colonies. We termed such ES like cells as the culture-induced pluripotent stem cells (CiPSC). CiPSCs from Mstn (-/-) MDSCs were phenotypically similar to ESCs, expressed high levels of Oct4, Nanog, Sox2 and SSEA-1, maintained a normal karyotype. Furthermore, CiPSCs formed embryoid bodies and teratomas when injected into immunocompromised mice. In addition, CiPSCs differentiated into somatic cells of all three lineages. We further show that culturing in ES cell media, resulted in hypermethylation and downregulation of BMP2 in Mstn(-/-) MDSCs. Western blot further confirmed a down regulation of BMP2 signaling in Mstn (-/-) MDSCs in supportive of pluripotent reprogramming. Given that down regulation of BMP2 has been shown to induce pluripotency in cells, we propose that lack of myostatin epigenetically reprograms the MDSCs to become pluripotent stem cells. Thus, here we report the successful establishment of ES-like cells from adult stem cells of the non-germline origin under culture-induced conditions without introducing reprogramming genes.

A signature for induced pluripotent stem cell-associated genes in colorectal cancer

Genes associated with induced pluripotent stem cells (iPS genes) are several pivotal transcriptional factors, which are used to induce pluripotent stem cells from some adult somatic cells. The roles of these iPS genes and especially the signature for these iPS genes in colorectal cancer (CRC) are still unclear. Overexpressed Oct4 and Lin28 but down-regulated Nanog were found in tumor tissues compared with that in their paired normal counterparts of CRC patients. Interestingly, we found that Oct4, Lin28 and Nanog were highly overexpressed in some patients. And the signature for iPS genes was correlated with tumor site (P = 0.012), lymph node status (P = 0.033), Dukes classification (P = 0.033) of CRC patients. Moreover, an independent public expression profiling data showed signature for the four iPS genes could successfully be used to predict the survival of CRC patients with Dukes stages B and C. Immunofluorescent staining of fresh CRC tissues from patients showed that strong co-expressions of Oct4 and Nanog proteins or Sox2 and Lin28 were present in some CRC cells. Then, CRC cell subclone with four iPS genes overexpression were establish by a mixed retroviral system. We found that iPS genes promote sphere-formation, proliferation, colony formation, migration of human CRC cells in vitro and tumor growth in vivo. Our study first shows the clinical significance of iPS signature in CRC patients.

Coexpression of Oct4 and Nanog enhances malignancy in lung adenocarcinoma by inducing cancer stem cell-like properties and epithelial-mesenchymal transdifferentiation

Epithelial-mesenchymal transition (EMT), a critical process of cancer invasion and metastasis, is associated with stemness property of cancer cells. Though Oct4 and Nanog are homebox transcription factors essential to the self-renewal of stem cells and are expressed in several cancers, the role of Oct4/Nanog signaling in tumorigenesis is still elusive. Here microarray and quantitative real-time PCR analysis showed a parallel, elevated expression of Oct4 and Nanog in lung adenocarcinoma (LAC). Ectopic expressions of Oct4 and Nanog in LACs increased the percentage of CD133-expressing subpopulation and sphere formation, enhanced drug resistance, and promoted EMT. Ectopic expressions of Oct4 and Nanog activated Slug and enhanced the tumor-initiating capability of LAC. Furthermore, double knockdown of Oct4 and Nanog suppressed the expression of Slug, reversed the EMT process, blocked the tumorigenic and metastatic ability, and greatly improved the mean survival time of transplanted immunocompromised mice. The immunohistochemical analysis demonstrated that expressions of Oct4, Nanog, and Slug were present in high-grade LAC, and triple positivity of Oct4/Nanog/Slug indicated a worse prognostic value of LAC patients. Our results support the notion that the Oct4/Nanog signaling controls epithelial-mesenchymal transdifferentiation, regulates tumor-initiating ability, and promotes metastasis of LAC.

Comprehensive analysis of the clinical significance of inducing pluripotent stemness-related gene expression in colorectal cancer cells

BACKGROUND

We previously determined that cancer stem-like cells may influence the susceptibility of colorectal cancer (CRC) cells to chemotherapeutic agents. Although Takahashi and Park identified a set of induced pluripotent stem cell (iPS)-related genes required for normal stem cell maintenance, the precise role of iPS-related gene expression in CRC pathogenesis remains to be determined. The purpose of this study was to clarify the clinical relevance of "stemness"-regulating gene expression in CRC cases.

MATERIALS AND METHODS

Cancer cells were excised from tissues of 79 CRC cases by laser microdissection (LMD), and quantitative RT-PCR was used to evaluate expression levels of the iPS-related genes c-MYC, SOX2, OCT3/4, LIN28, KLF4, and NANOG, and to identify any associations between their expression and clinicopathological CRC progression.

RESULTS

We found that LIN28 expression is significantly associated with lymph node metastasis (p = 0.018) and Dukes stage (p = 0.0319). SOX2expression is also correlated with lymph node metastasis. Furthermore, the ten cases with Dukes D disease expressed significantly higher levels of SOX2transcript than the other 69 cases (p = 0.0136). In contrast, KLF4 expression was inversely related to Dukes stage. Expression of c-MYC, OCT3/4, and NANOG did not appear to have clinical relevance in CRC cases.

CONCLUSION

The present analysis strongly suggests that altered expression of several iPS-related genes plays a role in CRC pathogenesis.