CD133 prevents colon cancer cell death induced by serum deprivation through activation of Akt-mediated protein synthesis and inhibition of apoptosis.

During the early phase of tumorigenesis, primary malignant cells survive within a low nutrition environment caused by a poorly organized vascular system. Here, we sought to determine the functional significance of CD133 in the survival of cancer cells under nutrient-poor conditions. Knockdown and overexpression experiments demonstrated that CD133 suppresses colon cancer cell death induced by serum deprivation through activation of Akt-mediated anti-apoptosis and protein synthesis pathways. Furthermore, serum deprivation increased the amount of endogenous CD133 protein, which was regulated at least in part by phosphoinositide 3-kinase. Thus, it is highly likely that CD133 contributes to the acquisition/maintenance of the resistance to stress arising from nutrient deficiency in early avascular tumor tissues.

Characteristics of CD133-Sustained Chemoresistant Cancer Stem-Like Cells in Human Ovarian Carcinoma.

Cancer stem cells (CSCs) are considered to be the origin of ovarian cancer (OC) development, recurrence, and chemoresistance. We investigated changes in expression levels of the CSC biomarker, cluster of differentiation 133 (CD133), from primary OC cell lines to induction of CSC-spheres in an attempt to explore the mechanisms related to modulation of stemness, drug resistance, and tumorigenesis in CSCs, thus facilitating the search for new therapeutics for OC. The effect of CD133 overexpression on the induction of CSC properties was evaluated by sphere-forming assays, RT-qPCR, flow cytometry, cell viability assays, and in vivo xenograft experiments. Moreover, the potential signaling molecules that participate in CD133 maintenance of stemness were screened by RNA-sequencing. CD133 expression was upregulated during OCSC induction and chemotherapeutic drug treatment over time, which increased the expressions of stemness-related markers (SOX2, OCT4, and Nanog). CD133 overexpression also promoted tumorigenesis in NOD/SCID mice. Several signalings were controlled by CD133 spheres, including extracellular matrix receptor interactions, chemokine signaling, and Wnt signaling, all of which promote cell survival and cell cycle progression. Our findings suggest that CD133 possesses the ability to maintain functional stemness and tumorigenesis of OCSCs by promoting cell survival signaling and may serve as a potential target for stem cell-targeted therapy of OC.

P38 expression in colorectal adenomas: relationships to cell proliferation, stem phenotype and AKT pathway proteins.

BACKGROUND: The P38-protein is known to be expressed in colorectal adenomas (CRA). Expression in low- and high-grade tubular adenomas is decreased when compared to adenocarcinomas and increased with regard to normal mucosa. We aimed to study P38 expression in human CRAs and the relationships to cell proliferation Ki67-protein, stem-phenotype CD133-protein and, to mTOR-protein (AKT pathway). METHODS: The immunohistochemical expression of P38 was evaluated in CRAs on tissue microarrays. Data were analyzed with the Kendall-rank-correlation test. RESULTS: Nuclear P38 correlated to low-grade dysplasia (Kendall P<0.01/tau=-0.254) and to decreased adenoma size (P<0.01/tau=-0.267). Nuclear P38 also correlated to cytoplasmic or membrane mTOR (P<0.01/tau=-0.223 and P<0.01/tau=-0.340) and to cytoplasmic CD133 (P<0.01/0.293). An inverse relationship was observed to Ki67 (P<0.00/ tau=-0.110). CONCLUSIONS: Our results suggest an interference of P38 with initial steps of colorectal adenomagenesis. The correlation to mTOR suggests a biological crosstalk between the MAPK- and AKT-signaling-pathways in colorectal adenomagenesis at P38 level.

Investigation of CD133 and CD24 as candidate azoospermia markers and their relationship with spermatogenesis defects.

Spermatogenesis is initiated when spermatogonial stem cells (SSCs) in the mature testes enter mitosis and trigger differentiation. Thus, spermatogenesis and the ability to maintain a continuous source of spermatogonia relies on the ability to differentiate SSCs. Many studies around the world have been performed to investigate the etiology of male infertility and recent studies have focused on the presence and identification of biomarkers. CD133 and CD24 are stem cell markers locating in the testis and spermatogonia. The aim of this study was to investigate the relationship of the CD133 and CD24 genes with spermatogenesis defects and examine them as a candidate a useful biomarker for azoospermia men. The association of CD133 and CD24 with spermatogenesis defects was investigated in patients with obstructive (O) and non-obstructive azoospermia (NOA). NOA cases were histopathologically classified into Hypospermatogenesis (HS), Maturation Arrest (MA), and Sertoli Cell Only Syndrome (SCO) groups. A qRT-PCR analysis of these genes was performed and protein expression levels were measured by Western blot analysis. CD133 expression in NOA group was found to be significantly different from OA and this was confirmed by immunohistochemistry and immunocytochemical assays. The qRT-PCR analysis revealed that gene expression of CD133 and CD24 had fold changes of 0.80 ±â€¯0.34 and 1.59 ±â€¯0.31 compared to controls, respectively in the HS group (p > 0.05) and 0.04 ±â€¯0.01 and 0.54 ±â€¯0.08 in the MA group (p < 0.05). In the SCO group, CD24 showed a 1.55 ±â€¯0.35-fold increase (p > 0.05). CD133 gene expression was not detected at the transcriptional level in the SCO group. Western blot analysis of CD133 protein expression revealed 1.83, 4.11, and 11.4-fold decreases in the HS, MA and SCO groups, respectively, compared to controls (p < 0.05). CD24 showed fold changes of 1.18, 0.38, (p < 0.05), and 0.89 in the HS, MA, and SCO groups, respectively. Immunohistochemical analysis of CD133 revealed moderate, partial staining in the HS group, compared to substantial, wide-spread staining in the OA group. No staining was detected in either the MA or SCO groups. The localization of CD133 in healthy sperm was determined to be prominent in the tail and partly expressed in the head by confocal laser scanning microscopy analysis. It was also found that the expression of CD133 protein was high in healthy commercially-sourced Sertoli cells as well as in the Sertoli cells of OA individuals. Data from this study show that CD133 exhibits different profiles in infertile patient groups and thus may be considered as a candidate biomarker. CD24 can be associated with blockage of germ cell maturation in the MA group. Curative protocols for spermatogenesis defects may be possible with the use of these markers and thus their identification is extremely valuable in terms of human reproductive health.

Prominin-like Regulates Longevity and Glucose Metabolism via Insulin Signaling in Drosophila.

CD133, also called Prominin-1, is a biomarker for mammalian stem cells. It is involved in cell growth, development, and tumor biology. However, the function of CD133 at the organismal level has not been investigated. In this study, we found that prominin-like (promL) loss-of-function mutant flies show an extended life span and metabolic defects such as increased circulating carbohydrates, lipid storage, and starvation resistance. The messenger RNA expression levels of Drosophila insulin-like peptides (Dilps) were reduced in loss-of-function promL mutants. Furthermore, the level of phosphorylated AKT, a downstream component of insulin signaling, was lower in promL loss-of-function mutants than in the w- control flies. Importantly, the PromL protein is predominantly expressed in the pars intercerebralis region with insulin-producing cells of the adult brain. When we inhibited promL in insulin-producing cells, these flies showed an extended life span, metabolic defects, and reduced insulin signaling. These results indicate that the promL gene regulates longevity and glucose metabolism by controlling insulin signaling in Drosophila.

Hypomyelination and cognitive impairment in mice lacking CD133 (Prominin-1).

The CD133 antigen, also known as prominin-1, is a glycoprotein that specifically localizes to plasma membrane protrusions. The precise function of CD133 remains unknown, but it is expressed in various progenitor cells including those derived from the neural and hematopoietic system, as well as different tissues. In the adult mouse brain, CD133 is highly expressed in white matter. Here, we performed immunohistochemical staining and electron microscopy to demonstrate that mice lacking CD133 (CD133-/-) exhibit decreased myelin in the corpus callosum, the largest white matter tract in the brain. Hypomyelination in CD133-/- mice was associated with fewer oligodendrocyte progenitor cells and mature oligodendrocytes. Behavioral analyses revealed that significantly impaired object recognition memory and altered Y-maze performance by CD133-/- mice compared with wild-type mice, suggesting perturbed cognitive performance. These results suggest that CD133 regulates myelination and understanding the underlying molecular mechanisms may guide the development of novel therapeutic strategies for diseases characterized by myelin deficiency.

Differentiation potential of human CD133 positive hematopoietic stem cells into motor neuron- like cells, in vitro.

Spinal cord injuries and motor neuron-related disorders impact on life of many patients around the world. Since pharmacotherapy and surgical approaches were not efficient to regenerate these types of defects; stem cell therapy as a good strategy to restore the lost cells has become the focus of interest among the scientists. Umbilical cord blood CD133+ hematopoietic stem cells (UCB- CD133+ HSCs) with self- renewal property and neural lineage differentiation capacity are ethically approved cell candidate for use in regenerative medicine. In this regard the aim of this study was to quantitatively evaluate the capability of these cells to differentiate into motor neuron-like cells (MNL), in vitro. CD133+ HSCs were isolated from human UCB using MACS system. After cell characterization using flow cytometry, the cells were treated with a combination of Retinoic acid, Sonic hedgehog, Brain derived neurotrophic factor, and B27 through a 2- step procedure for two weeks. The expression of MN-specific markers was examined using qRT- PCR, flow cytometry and immunocytochemistry. By the end of the two-week differentiation protocol, CD133+ cells acquired unipolar MNL morphology with thin and long neurites. The expression of Isl-1(62.15%), AChE (41.83%), SMI-32 (21.55%) and Nestin (17.46%) was detected using flow cytometry and immunocytochemistry. The analysis of the expression of PAX6, ISL-1, ACHE, CHAT and SMI-32 revealed that MNLs present these neural markers at levels comparable with undifferentiated cells. In Conclusion Human UCB- CD133+ HSCs are remarkably potent cell candidates to transdifferentiate into motor neuron-like cells, in vitro.

Ectopic overexpression of CD133 in HNSCC makes it resistant to commonly used chemotherapeutics.

Head and neck squamous cell carcinoma (HNSCC) is one of the most common cancers in the world. Resistance to cytotoxic chemotherapy is a major cause of mortality in patients with HNSCC. A small subset of cancer cells called cancer stem cells (CSCs) may be key contributors to drug resistance and tumor recurrence in HNSCC. The aim of this study was to determine whether CD133, which maintains properties of CSCs, promotes chemoresistance by arresting cell cycle transition and reducing apoptosis in HNSCC cells. CD133 overexpression was examined in KB cells, and colony forming and aldehyde dehydrogenase activity assays were performed. To investigate the role of CD133 in chemoresistance, cell death was analyzed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), Diff-Quick, flow cytometry, and western blot of apoptosis-related protein expression in fluorouracil (5-FU)- or cisplatin-treated cells. In addition, microarray and related protein expression assessments were performed to investigate the mechanism of chemoresistance against 5-FU and cisplatin in KB cells. Moreover, chemoresistance against 5-FU or cisplatin in a KB-inoculated mouse model was analyzed by hematoxylin and eosin staining, immunohistochemical study of CD133, and immunofluorescence of tumor tissue. In this study, we demonstrate that ectopic overexpression of CD133 significantly promotes properties of stemness in KB cell lines. Furthermore, CD133 promotes chemoresistance by arresting transition of the cell cycle and reducing apoptosis, which results in inhibition of tumor growth in 5-FU- or cisplatin-injected mouse tumor model. Taken together, our findings show that elevated levels of CD133 lead to HNSCC chemoresistance through increased stemness and cell cycle arrest.

CD133 confers cancer stem-like cell properties by stabilizing EGFR-AKT signaling in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is the seventh most common malignant tumor and the third leading cause of cancer-related death in the world. Cancer stem cells (CSCs) are small subpopulation of cells within tumors that drive chemoresistance and tumor recurrence in various cancers. We characterized CSCs in primary HCC and identified CD133 as a CSC surface marker. CD133+ HCC cells displayed more stem cell-like properties, tumor spheroid-forming ability, chemoresistance, migration ability, and tumorigenic capacity than CD133- HCC cells. The biological function and molecular mechanism of CD133 remain unclear. HCC cell lines with a high level of CD133 expression overexpressed EGFR, which is overexpressed in approximately 70% of conventional HCCs. CD133 depletion destabilized EGFR by augmenting EGFR internalization and thus inhibited EGFR-AKT signaling. CD133 would therefore serve to sustain aberrant EGFR-mediated oncogenic signaling. Furthermore, EGFR-deficient CD133+ HCC cells manifested greater sensitivity to anticancer drugs and less spheroid-formation capacity than control CD133+ HCC cells. Our results strongly indicate that CD133 facilitates CSC-like properties by stabilizing EGFR-AKT signaling in HCC. It might therefore be feasible to use CD133 as a novel target to sensitize HCC cells that manifest resistance to EGFR-targeted therapy.