Phosphofructokinase and pyruvate kinase in mouse embryonal carcinoma P19 cells in relation to growth and differentiation

Mechanisms Regulating Stemness and Differentiation in Embryonal Carcinoma Cells

Just over ten years have passed since the seminal Takahashi-Yamanaka paper, and while most attention nowadays is on induced, embryonic, and cancer stem cells, much of the pioneering work arose from studies with embryonal carcinoma cells (ECCs) derived from teratocarcinomas. This original work was broad in scope, but eventually led the way for us to focus on the components involved in the gene regulation of stemness and differentiation. As the name implies, ECCs are malignant in nature, yet maintain the ability to differentiate into the 3 germ layers and extraembryonic tissues, as well as behave normally when reintroduced into a healthy blastocyst. Retinoic acid signaling has been thoroughly interrogated in ECCs, especially in the F9 and P19 murine cell models, and while we have touched on this aspect, this review purposely highlights how some key transcription factors regulate pluripotency and cell stemness prior to this signaling. Another major focus is on the epigenetic regulation of ECCs and stem cells, and, towards that end, this review closes on what we see as a new frontier in combating aging and human disease, namely, how cellular metabolism shapes the epigenetic landscape and hence the pluripotency of all stem cells.

A study of PKM2, PFK-1, and ANT1 expressions in cervical biopsy tissues in China

This present study explored the association of Pyruvate Kinase isozyme M2 (PKM2), Phosphofructokinase 1 (PFK-1) and Adenine nucleotide translocator 1 (ANT1) with cervical carcinoma. A case-control method was designed by the collected 95 cervical biopsy samples, which were divided into 30 controls and 60 cases. Cases were subdivided into mild cervical carcinoma (MCC-25), intermediate cervical carcinoma (ICC-20), and severe cervical carcinoma (SCC-20) by method of cervical pathology. The expression of PKM2, PFK-1, and ANT1 was examined by methods of immunohistochemistry and western blotting (WB). The results showed that the positive proportions of PKM2 and PFK-1 in case group were higher than that of control, and the increased positive proportions of PKM2 and PFK-1 were also revealed with the order of Control, MCC, ICC, SCC (P<0.05). Further, the results of WB confirmed the enhanced expressions of PKM2 and PFK-1 in case group and the increasing trend of PKM2 and PFK-1 expressions in Control, MCC, ICC, and SCC groups. In addition, the WB result of ANT1 showed a lower level of expression in SCC group, while the positive proportion of ANT1 was not significant between cases group and control. In conclusion, PKM2 and PFK-1 genes are associated closely with cervical carcinoma. The enhanced expressions of PKM2 and PFK-1 indicate one developing signal of cervical carcinoma.

Characterization of genes which exhibit reduced expression during the retinoic acid-induced differentiation of F9 teratocarcinoma cells: involvement of cyclin D3 in RA-mediated growth arrest

In the presence of retinoic acid (RA), F9 murine teratocarcinoma cells differentiate into cells resembling the extra-embryonic endoderm of the early mouse embryo. Using differential hybridization, we have cloned and characterized six cDNAs corresponding to mRNAs that exhibit reduced expression in F9 cells following RA treatment. Two of these cDNAs encode novel genes (REX-2 and REX-3). The other isolated cDNAs encode genes that have been previously described in other contexts: 1-4 (cyclin D3); 2-10 (pyruvate kinase); 2-12 (glutathione S-transferase); and 2-17 (GLUT 3). The mRNA levels of these genes are reduced by RA or RA plus theophylline and cAMP (RACT) only after 48 h of treatment, and continue to decrease at 96 h. The half-lives of these mRNAs are not changed by RA treatment, indicating that these mRNAs may be regulated through a transcriptional mechanism. In isoleucine-deprived cells, which are growth arrested but do not differentiate, the steady state mRNA levels of genes Rex 2, Rex 3, pyruvate kinase and GLUT 3 are not reduced, in contrast to cyclin D3 and glutathione S-transferase. The expression of the REX-2, REX-3, pyruvate kinase, glutathione S-transferase and GLUT 3 genes is reduced by RACT to the same extent in F9 RARgamma-/- and RARalpha-/- lines as in F9-Wt. In contrast, cyclin D3 exhibits lower mRNA expression in F9 RARgamma-/- and RARalpha-/- stem cells, and this mRNA is not decreased by RACT treatment. Overexpression of cyclin D3 blocks the RA-induced growth arrest of F9 cells, indicating that the downregulation of this gene following RA treatment may constitute a necessary step in the cascade of events leading to growth inhibition by RA.

Retinoic acid induces a shift in the energetic state of hypertrophic chondrocytes

In the epiphyseal growth plate, chondrocyte maturation is accompanied by dramatic alterations in energy metabolism. To explore the relationship between these two events, we used retinoic acid (RA) to promote chondrocyte maturation in culture. The specific question that was addressed was, does RA treatment of cultured chondrocytes in vitro induce a change in energy status similar to that seen in hypertrophic chondrocytes in vivo. Maturing chondrocytes isolated from the cephalic region of day 18 chick embryo sterna were allowed to grow for 7-14 days in monolayer until confluent and then treated with 10-300 nM RA. Immature chondrocytes from the caudal region of sternum were grown in parallel and served as control cells for the study. We found that in maturing cephalic cell cultures, RA had a rapid and profound effect on oxidative metabolism. The retinoid caused a reduction in the energy charge ratio (ECR) and the ATP/ADP ratio and a sharp decrease in cell ATP levels. Maximum inhibition was observed when the RA concentration was 10-35 nM. Compared with the adenine nucleotides, creatine phosphate levels were decreased to a lesser extent by RA, although there was substantial inhibition of creatine kinase activity. We expected to find a compensatory elevation in glycolytic activities; however, the lactate levels in the medium of the treated cells indicated that anaerobic glycolysis was depressed. In contrast to the cephalic chondrocytes, when caudal cell cultures were treated with RA, lactate formation was stimulated and there were minimal effects on oxidative metabolism. To determine the mechanism of inhibition of glycolysis, we measured the activity of pyruvate kinase in RA-treated cephalic cells.(ABSTRACT TRUNCATED AT 250 WORDS)