Oct‐4 Expression in Adult Human Differentiated Cells Challenges Its Role as a Pure Stem Cell Marker

Abstract

The Oct-4 transcription factor, a member of the POU family that is also known as Oct-3 and Oct3/4, is expressed in totipotent embryonic stem cells (ES) and germ cells, and it has a unique role in development and in the determination of pluripotency. ES may have their postnatal counterpart in the adult stem cells, recently described in various mammalian tissues, and Oct-4 expression in putative stem cells purified from adult tissues has been considered a real marker of stemness. In this context, normal mature adult cells would not be expected to show Oct-4 expression. On the contrary, we demonstrated, using reverse transcription-polymerase chain reaction (PCR) (total RNA, Poly A؉), real-time PCR, immunoprecipitation, Western blotting, band shift, and immunofluorescence, that human peripheral blood mononuclear cells, genetically stable and mainly terminally differentiated cells with well defined functions and a limited lifespan, express Oct-4. These observations raise the question as to whether the role of Oct-4 as a marker of pluripotency should be challenged. Our findings suggest that the presence of Oct-4 is not sufficient to define a cell as pluripotent, and that additional measures should be used to avoid misleading results in the case of an embryonic-specific gene with a large number of pseudogenes that may contribute to false identification of Oct-4 in adult stem cells. These unexpected findings may provide new insights into the role of Oct-4 in fully differentiated cells.

In Vivo Osteoprogenitor Potency of Human Stromal Cells from Different Tissues Does Not Correlate with Expression of POU5F1 or Its Pseudogenes

“…Primer pairs designed to amplify only true POU5F1A and not its pseudogenes confirmed the expression of POU5F1A in embryonic carcinoma cells but failed to amplify PCR products from peripheral blood mononuclear cells (PBMNC), suggesting POU5F1A is not transcribed in these cells [20]. Indeed, we demonstrated that, like human PBMNC [21], human tumor cell lines [22], and murine mesenchymal stromal cells [23], neither the multipotent BM-MSC nor the non-UVSC in fact expressed detectable levels of POU5F1A protein.…”

Comparative Analysis of Oct4 in Different Histological Subtypes of Esophageal Squamous Cell Carcinomas in Different Clinical Conditions

“…There are two studies (Tai et al, 2005;He et al, 2012) who had reported Oct4 expression by dysplastic and hyperplastic esophageal mucosa confining to the proliferative zone, and not expressed by the normal mucosa. Oct4 positivity is reported in certain adult tissue including benign endometrial stromal cells (Atlasi et al, 2006;Cauffman et al, 2006;Mathai et al, 2006;Katona et al, 2007;Zangrossi et al, 2007;Atlasi et al, 2008;Forte et al, 2009). We observed slightly higher sensitivity by PCR technique than by the conventional immunohistochemistry method in detecting Oct4 expression, which is similar to other reported data (Atlasi et al, 2006;Xi et al, 2011;.…”

Perivascular Ancestors of Adult Multipotent Stem Cells

“…65 Umbilical cord pericytes express the same surface markers as in other tissues 15 ; they also express SSEA-4, a glycolipid antigen that is commonly used as a marker of human embryonic stem cells and embryos at cleavage to blastocyst stages was also recently identified in bone marrow MSCs. 66 Umbilical cord pericytes also express Oct-4, 65 an embryonic cell marker arguably considered an indicator of stemness, 67,68 underlining the multipotency of these cells. In the perspective of cell therapies, the migratory potential of human perivascular cells is an important parameter in seeking to ensure homing to injured tissues.…”