Type 2 Fibroblast Growth Factor Receptor Signaling Preserves Stemness and Prevents Differentiation of Prostate Stem Cells from the Basal Compartment.

Prostate stem cells (P-SCs) are capable of giving rise to all three lineages of prostate epithelial cells, which include basal, luminal, and neuroendocrine cells. Two types of P-SCs have been identified in both human and mouse adult prostates based on prostasphere or organoid cultures, cell lineage tracing, renal capsule implantation, and expression of luminal- and basal-specific proteins. The sphere-forming P-SCs are from the basal cell compartment that express P63, and are therefore designated as basal P-SCs (P-bSCs). Luminal P-SCs (P-lSCs) express luminal cytokeratins and Nkx3.1. Herein, we report that the type 2 FGF receptor (FGFR2) signaling axis is crucial for preserving stemness and preventing differentiation of P-bSCs. FGFR2 signaling mediated by FGFR substrate 2α (FRS2α) is indispensable for formation and maintenance of prostaspheres derived from P63(+) P-bSCs. Ablation of Fgfr2 in P63(+) cells in vitro causes the disintegration of prostaspheres. Ablation of Fgfr2 in vivo reduces the number of P63-expressing basal cells and enriches luminal cells. This suggests a basal stem cell-to-luminal cell differentiation. In addition, ablation of Fgfr2 in P63(+) cells causes defective postnatal development of the prostate. Therefore, the data indicate that FGFR2 signaling is critical for preserving stemness and preventing differentiation of P-bSCs.

Prostate Sphere-forming Stem Cells Are Derived from the P63-expressing Basal Compartment.

Prostate stem cells (P-SCs) are capable of giving rise to all three lineages of prostate epithelial cells, including basal, luminal, and neuroendocrine cells. Multiple methods have been used to identify P-SCs in adult prostates. These include in vivo renal capsule implantation of a single epithelial cell with urogenital mesenchymal cells, in vitro prostasphere and organoid cultures, and lineage tracing with castration-resistant Nkx3.1 expression (CARN), in conjunction with expression of cell type-specific markers. Both organoid culture and CARN tracing show the existence of P-SCs in the luminal compartment. Although prostasphere cells predominantly express basal cell-specific cytokeratin and P63, the lineage of prostasphere-forming cells in the P-SC hierarchy remains to be determined. Using lineage tracing with P63(CreERT2), we show here that the sphere-forming P-SCs are P63-expressing cells and reside in the basal compartment. Therefore we designate them as basal P-SCs (P-bSCs). P-bSCs are capable of differentiating into AR(+) and CK18(+) organoid cells, but organoid cells cannot form spheres. We also report that prostaspheres contain quiescent stem cells. Therefore, the results show that P-bSCs represent stem cells that are early in the hierarchy of overall prostate tissue stem cells. Understanding the contribution of the two types of P-SCs to prostate development and prostate cancer stem cells and how to manipulate them may open new avenues for control of prostate cancer progression and relapse.

Do all the patients with vitamin B12 deficiency have pernicious anemia?

BACKGROUND: Vitamin B12 deficiency may result in pernicious anemia (PA). This study evaluated whether all the patients with vitamin B12 deficiency had PA. METHODS: The blood hemoglobin (Hb), iron, vitamin B12, folic acid, and homocysteine concentrations and mean corpuscular volume (MCV) in 90 vitamin B12-deficient patients were measured and compared with the corresponding data in 180 age- and sex-matched healthy control subjects. PA was defined by World Health Organization (WHO) as having an Hb concentration <13 g/dl for men and <12 g/dl for women, an MCV ≧ 100 fl, a serum vitamin B12 level <200 pg/ml, and serum gastric parietal cell antibody (GPCA) positivity. RESULTS: We found that 35 (38.9%) and 20 (22.2%) patients with vitamin B12 deficiency had deficiencies of Hb (men <13 g/dl, women <12 g/dl) and iron (<60 µg/dl), respectively. Moreover, 65 (72.2%) and 37 (41.1%) patients with vitamin B12 deficiency had abnormally high blood homocysteine level (>12.7 µM) and high MCV (≧100 fl), respectively. In addition, 43 (47.8%) vitamin B12-deficient patients with had GPCA positivity. Patients with vitamin B12 deficiency had a significantly higher frequency of Hb or iron deficiency, of abnormally elevated blood homocysteine level or high MCV, and of GPCA positivity than healthy control subjects (all P-values < 0.001). However, only 17 (18.9%) of 90 vitamin B12-deficient patients were diagnosed as having PA by the WHO definition. CONCLUSION: Only 18.9% of patients with vitamin B12 deficiency are discovered to have PA by the WHO definition.

Anemia and hematinic deficiencies in gastric parietal cell antibody-positive and antibody-negative erosive oral lichen planus patients with thyroid antibody positivity.

BACKGROUND/PURPOSE: Serum gastric parietal cell antibody (GPCA), thyroglobulin antibody (TGA), and thyroid microsomal antibody (TMA) are found in some erosive oral lichen planus (EOLP) patients. This study assessed whether serum GPCA, TGA and TMA and EOLP itself played significant roles in causing anemia and hematinic deficiencies in TGA/TMA-positive EOLP patients with GPCA positivity (GPCA+/TGA/TMA/EOLP patients) or negativity (GPCA-/TGA/TMA/EOLP patients). METHODS: The mean corpuscular volume (MCV) and mean blood hemoglobin (Hb), iron, vitamin B12, and folic acid levels were measured and compared between any two of the four groups of 29 GPCA+/TGA/TMA/EOLP patients, 80 GPCA-/TGA/TMA/EOLP patients, 198 all antibodies-negative EOLP patients (Abs-/EOLP patients), and 218 healthy control individuals. RESULTS: GPCA+/TGA/TMA/EOLP patients had significantly lower mean Hb and vitamin B12 levels as well as significantly greater frequencies of Hb, iron, and vitamin B12 deficiencies than healthy controls. GPCA+/TGA/TMA/EOLP patients had significantly lower serum vitamin B12 level and higher MCV as well as a significantly greater frequency of vitamin B12 deficiency than GPCA-/TGA/TMA/EOLP patients. Furthermore, both GPCA-/TGA/TMA/EOLP and Abs-/EOLP patients did have significantly lower mean Hb, MCV, and iron (for women only) levels, as well as significantly greater frequencies of Hb and iron deficiencies than healthy controls. However, there were no significant differences in measured blood data between GPCA-/TGA/TMA/EOLP and Abs-/EOLP patients. CONCLUSION: We conclude that serum GPCA is the major factor causing vitamin B12 deficiency, macrocytosis and pernicious anemia in GPCA+/TGA/TMA/EOLP patients. ELOP itself but not TGA/TMA positivity plays a significant role in causing anemia and hematinic deficiencies in GPCA-/TGA/TMA/EOLP patients.

FRS2α-mediated FGF signals suppress premature differentiation of cardiac stem cells through regulating autophagy activity.

RATIONALE: Although the fibroblast growth factor (FGF) signaling axis plays important roles in heart development, the molecular mechanism by which the FGF regulates cardiogenesis is not fully understood. OBJECTIVE: To investigate the mechanism by which FGF signaling regulates cardiac progenitor cell differentiation. METHODS AND RESULTS: Using mice with tissue-specific ablation of FGF receptors and FGF receptor substrate 2α (Frs2α) in heart progenitor cells, we demonstrate that disruption of FGF signaling leads to premature differentiation of cardiac progenitor cells in mice. Using embryoid body cultures of mouse embryonic stem cells, we reveal that FGF signaling promotes mesoderm differentiation in embryonic stem cells but inhibits cardiomyocyte differentiation of the mesoderm cells at later stages. Furthermore, we also report that inhibiting FRS2α-mediated signals increases autophagy and that activating autophagy promotes myocardial differentiation and vice versa. CONCLUSIONS: The results indicate that the FGF/FRS2α-mediated signals prevent premature differentiation of heart progenitor cells through suppressing autophagy. The findings provide the first evidence that autophagy plays a role in heart progenitor differentiation.

The FGF-BMP signaling axis regulates outflow tract valve primordium formation by promoting cushion neural crest cell differentiation.

RATIONALE: Heart valves develop from precursor structures called cardiac cushions, an endothelial-lined cardiac jelly that resides in the inner side of the heart tube. The cushions are then invaded by cells from different sources, undergo a series of complicated and poorly understood remodeling processes, and give rise to valves. Disruption of the fibroblast growth factor (FGF) signaling axis impairs morphogenesis of the outflow tract (OFT). Yet, whether FGF signaling regulates OFT valve formation is unknown. OBJECTIVE: To study how OFT valve formation is regulated and how aberrant cell signaling causes valve defects. METHODS AND RESULTS: By using mouse genetic manipulation, cell lineage tracing, ex vivo heart culture, and molecular biology approaches, we demonstrated that FGF signaling in the OFT myocardium upregulated Bmp4 expression, which then enhanced smooth muscle differentiation of neural crest cells (NCCs) in the cushion. FGF signaling also promoted OFT myocardial cell invasion to the cushion. Disrupting FGF signaling interrupted cushion remodeling with reduced NCCs differentiation into smooth muscle and less cardiomyocyte invasion and resulted in malformed OFT valves. CONCLUSIONS: The results demonstrate a novel mechanism by which the FGF-BMP signaling axis regulates formation of OFT valve primordia by controlling smooth muscle differentiation of cushion NCCs.