The expressions of stem cell markers: Oct4, Nanog, Sox2, nucleostemin, Bmi, Zfx, Tcl1, Tbx3, Dppa4, and Esrrb in bladder, colon, and prostate cancer, and certain cancer cell lines

Hyperglycemic Stress Impairs the Stemness Capacity of Kidney Stem Cells in Rats

The incidence of acute kidney injury in patients with diabetes is significantly higher than that of patients without diabetes, and may be associated with the poor stemness capacity of kidney stem cells (KSCs) and limited recovery of injured renal tubules. To investigate the effects of hyperglycemic stress on KSC stemness, KSCs were isolated from the rat renal papilla and analyzed for their self-renewal and differentiation abilities. Our results showed that isolated KSCs expressed the mesenchymal stem cell markers N-cadherin, Nestin, CD133, CD29, CD90, and CD73. Moreover, KSCs co-cultured with hypoxia-injured renal tubular epithelial cell (RTECs) induced the expression of the mature epithelial cell marker CK18, suggesting that the KSCs could differentiate into RTECs in vitro. However, KSC proliferation, differentiation ability and tolerance to hypoxia were decreased in high-glucose cultures. Taken together, these results suggest the high-glucose microenvironment can damage the reparative ability of KSCs. It may result in a decreased of recovery capability of renal tubules from injury.

E-selectin ligand-1 controls circulating prostate cancer cell rolling/adhesion and metastasis

Circulating prostate cancer (PCa) cells preferentially roll and adhere on bone marrow vascular endothelial cells, where abundant E-selectin and stromal cell-derived factor 1 (SDF-1) are expressed, subsequently initiating a cascade of activation events that eventually lead to the development of metastases. To elucidate the roles of circulating PCa cells' rolling and adhesion behaviors in cancer metastases, we applied a dynamic cylindrical flow-based microchannel device that is coated with E-selectin and SDF-1, mimicking capillary endothelium. Using this device we captured a small fraction of rolling PCa cells. These rolling cells display higher static adhesion ability, more aggressive cancer phenotypes and stem-like properties. Importantly, mice received rolling PCa cells, but not floating PCa cells, developed cancer metastases. Genes coding for E-selectin ligands and genes associated with cancer stem cells and metastasis were elevated in rolling PCa cells. Knock down of E-selectin ligand 1(ESL-1), significantly impaired PCa cells' rolling capacity and reduced cancer aggressiveness. Moreover, ESL-1 activates RAS and MAP kinase signal cascade, consequently inducing the downstream targets. In summary, circulating PCa cells' rolling capacity contributes to PCa metastasis, and that is in part controlled by ESL-1.

Depletion of B cell CLL/Lymphoma 11B Gene Expression Represses Glioma Cell Growth

B cell CLL/lymphoma 11B (Bcl11b), a C2H2 zinc finger transcription factor, not only serves as a critical regulator in development but also plays the controversial role in T cell acute lymphoblastic leukemia (T-ALL). We previously found that the enriched expression of Bcl11b was detected in high tumorigenic C6 glioma cells. However, the role of Bcl11b in glioma malignancy and its mechanisms remains to be uncovered. In this study, using the lentivirus-mediated knockdown (KD) approach, we found that Bcl11b KD in tumorigenic C6 cells reduced the cell proliferation, colony formation, and migratory ability. The results were further verified using two human malignant glioma cell lines, U87 and U251 cells. A cyclin-dependent kinase inhibitor p21, a known Bcl11b target, was significantly upregulated in tumorigenic C6, U87, and U251 cells after Bcl11b KD. Cellular senescence was observed by examination of the β-galactosidase activity in U87 and U251 cells with Bcl11b KD. Reduced expression of stemness gene Sox-2 and its downstream effector Bmi-1 was also observed in U87 and U251 cells with Bcl11b KD. These results suggest that the ablation of Bcl11b gene expression induced glioma cell senescence. Propidium iodide (PI) staining combined with flow cytometry analysis also showed that Bcl11b KD led to the cell cycle arrest of U87 and U251 cells at the G0/G1 or at the S phase, indicating that Bcl11b is required for glioma cell cycle progression. Together, this is the first study to show that the inhibition of Bcl11b suppresses glioma cell growth by regulating the expression of the cell cycle regulator p21 and stemness-associated genes (Sox-2/Bmi-1).

Developmental pluripotency-associated 4: a novel predictor for prognosis and a potential therapeutic target for colon cancer

Backgrounds

Developmental pluripotency-associated 4 (Dppa4) gene plays an important role in self-renewal and pluripotency sustainability in embryonic stem cells. It is re-expressed in several malignant tumors and is identified as a new pluripotency-related oncogene. The present study investigates the expression and clinical significance of Dppa4 in colon cancer.

Methods

Real-time polymerase chain reaction and Western blotting were used to evaluate Dppa4 mRNA and protein expression in 39 pairs of fresh-frozzen colon cancer samples, which were compared with adjacent normal mucosa. The Dppa4 protein was evaluated by immunohistochemical techniques using colon tissue microarrays (TMA). The sample included 185 cancer specimens and corresponding normal colorectal mucosa. The effect of Dppa4 knockdown on colorectal cancer cell proliferation was investigated using Cell Counting Kit-8 (CCK8) assays and colony-formation assays.

Results

Both the mRNA and protein level expression of Dppa4 gene was found to be upregulated in colon cancer tissues. Furthermore, the upregulated expression of Dppa4 was significantly correlated with the results of American Joint Committee on Cancer (AJCC) stage (P = 0.01), invasion depth (P = 0.028), nodal involvement (P = 0.012), distant metastasis (P = 0.003), and differentiation (P = 0.002). Dppa4 was also shown to be an independent prognostic indicator of disease-free survival (HR 6.118, 95 % CI 3.004–12.462) and overall survival (HR 6.348, 95 % CI 2.875–14.014) for patients with colon cancer. Knockdown of Dppa4 expression inhibited the proliferation of colorectal cancer cell lines through G1/S transition regulation.

Conclusion

The results indicate that Dppa4 might play an important role in colon cancer progression and function as a novel prognostic indicator and a potential therapeutic target.

Zinc finger protein X-linked is overexpressed in colorectal cancer and is associated with poor prognosis

Zinc finger protein X-linked (ZFX) is a zinc finger transcription factor and plays a significant role in the self-renewal ability of embryonic stem cells and various cancers. However, its expression and function in colorectal cancer (CRC) remain unclear. In the present study, we evaluated the expression of ZFX in CRC using quantitative polymerase chain reaction (qPCR), western blot analysis and immunohistochemistry (IHC), and further explored its potential functions in CRC cell lines using cell counting kit-8 and Transwell invasion assays. qPCR and western blot analysis revealed that ZFX was significantly upregulated in CRC tissues; IHC further confirmed this finding, revealing that higher expression of ZFX was significantly associated with larger tumor size (P=0.01), higher pathological stage (P=0.02), depth of invasion (P=0.047), lymph node invasion (P=0.02) and higher American Joint Committee on Cancer (AJCC) stage (P=0.04). CRC patients with higher ZFX expression also exhibited significantly shorter survival times (P=0.019). Moreover, knockdown of ZFX significantly suppressed proliferation and invasion in CRC cell lines HCT116 and LoVo. These results suggest that ZFX plays a notable role in CRC tumorigenicity and may serve as a novel marker and therapeutic target for CRC.

Direct lineage conversion of astrocytes to induced neural stem cells or neurons

Since the generation of induced pluripotent stem cells in 2006, cellular reprogramming has attracted increasing attention as a revolutionary strategy for cell replacement therapy. Recent advances have revealed that somatic cells can be directly converted into other mature cell types, which eliminates the risk of neoplasia and the generation of undesired cell types. Astrocytes become reactive and undergo proliferation, which hampers axon regeneration following injury, stroke, and neurodegenerative diseases. An emerging technique to directly reprogram astrocytes into induced neural stem cells (iNSCs) and induced neurons (iNs) by neural fate determinants brings potential hope to cell replacement therapy for the above neurological problems. Here, we discuss the development of direct reprogramming of various cell types into iNs and iNSCs, then detail astrocyte-derived iNSCs and iNs in vivo and in vitro. Finally, we highlight the unsolved challenges and opportunities for improvement.

High expression of Zinc-finger protein X-linked is associated with reduced E-cadherin expression and unfavorable prognosis in nasopharyngeal carcinoma

Zinc-finger protein X-linked (ZFX), a novel transcription factor required for self-renewal of embryonic stem cells, has recently been implicated in the initiation and progression of various human malignancies. However, its clinical significance in cancer patients remains largely inconclusive and its role in nasopharyngeal carcinoma (NPC) has never been reported. In this study, quantitative real-time polymerase chain reaction, Western blot and Immunohistochemistry were performed to detect ZFX expression in NPC and normal nasopharyngeal tissues. As a result, we found ZFX expression was significantly elevated in NPC tissues compared with that in normal nasopharyngeal tissues. The statistical analysis based on immunohistochemical staining demonstrated that ZFX expression was significantly correlated with lymph node stage and clinical stage. Furthermore, we found NPC patients with high ZFX expression had lower 5-year overall survival rates, progression-free survival rates, loco-regional relapse-free survival rates and distant metastasis-free survival rates than those with low ZFX expression (all P<0.05). The multivariate analysis indicated that ZFX expression was an independent prognostic factor for patients with NPC. More importantly, we also detected E-cadherin expression in NPC tissues and found it was inversely correlated with ZFX expression in NPC tissues, suggesting a potential involvement of ZFX in Epithelial-mesenchymal transition (EMT). Therefore, it is speculated that ZFX may promote NPC progression partly by regulating EMT. In summary, our study not only for the first time identified that ZFX could serve as an effective prognostic biomarker for NPC patients, but also suggested that targeting ZFX might be a novel therapeutic strategy for preventing NPC progression and metastasis.

Isolation of colorectal cancer stem-like cells

This study is aimed at isolating colorectal cancer stem-like cells in vitro using a neurosphere assay method employed in isolating gliobastoma multiforme tumor cells. This was followed with confirmation of the isolated cells by flow cytometry, pluripotent genes expression and in vivo tumorigenicity assay. Using this culture assay, stem-like and non-stem-like CRC cells were isolated and expanded in vitro from purchased Balb/c mice induced with CT26 colorectal cancer (CRC) cell line. The procedure includes an initial mechanical dissociation and chemical digestion of tumor tissue and subsequently plating the resulting single cell suspension in serum-free medium (SFM) or serum-containing medium (SCM). This selectively permits growth of cancer stem-like cells in SFM and eliminates non-stem-like cancer cells through the process of anoikis or apoptosis. CRC stem cells derived cultures proliferated as non-adherent spheres in vitro in different shapes and sizes. These cells expressed cell surface markers previously reported for tumor stem cells, including CD44, CD133, CD166 and CD26 and formed tumors when implanted in severe combined immunodeficient mice in a concentration dependent manner. Importantly, the stem-like cells had self-renewal properties with significantly higher expression of the pluripotent stem cell genes NANOG, OCT4, and SOX2 compared to the adherent non-stem cells. Collectively, the results of this study indicate that SFM is a defined culture medium that enriches for CRC stem-like cells and represents a suitable in vitro model for the study of CRC stem-like cells. This finding may be useful in developing therapeutic strategies aimed at eradicating the tumorigenic subpopulation within colorectal cancer.

Overexpression of Tbx3 is correlated with Epithelial-Mesenchymal Transition phenotype and predicts poor prognosis of colorectal cancer

AIMS

To investigate the clinical significance of Tbx3 in colorectal cancer (CRC) and the possible association between Tbx3 expression and Epithelial- Transition Mesenchymal (EMT) phenotype.

METHODS

Quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) and western blotting were employed to evaluate the expression of Tbx3 in 30 fresh CRC and matched normal tissues. Using immunochemistry, protein level of Tbx3 and EMT markers (E-cadherin and N-cadherin) were identified in 150 pairs of paraffin-embedded specimen.

RESULTS

The results of qRT-PCR and western blotting showed that Tbx3 expression was higher in CRC tissues than in corresponding normal tissues. The statistical analysis based on immunohistochemical evaluation suggested that Tbx3 aberrant expression was significantly associated with tumor size (P=0.049), differentiation (P=0.032), invasion (P=0.019), lymph node metastasis (P=0.049) and TNM stage (P=0.018). Patients who displayed high expression of Tbx3 may achieve a poorer overall survival (OS) and disease-free survival (DFS), compared to those with low expression of Tbx3. This tendency was also observed in patients with intermediate levels of disease (II and III stage). The multivariate analysis indicated Tbx3 expression could independently predict the outcome of CRC patients. Interestingly, correlation analysis suggested Tbx3 expression was negatively correlated with E-cadherin expression, but positively correlated with N-cadherin expression.

CONCLUSION

Tbx3 may promote CRC progression by involving EMT program and has the potential to be an effective prognostic predictor for CRC patients.

Dedifferentiation of cancer cells following recovery from a potentially lethal damage is mediated by H2S-Nampt

Recently, we reported that cancer cells that recover from a potentially lethal damage gain new phenotypic features comprised of mitochondrial structural remodeling associated with increased glycolytic dependency and drug resistance. Here, we demonstrate that a subset of cancer cells, upon recovery from a potentially lethal damage, undergo dedifferentiation and express genes, which are characteristic of undifferentiated stem cells. While these cells are competent in maintaining differentiated progeny of tumor, they also exhibit transdifferentiation potential. Dedifferentiation is characterized by accumulation of hydrogen sulfide (H2S), which triggers up-regulation of nicotinamide phosphoribosyltransferase (Nampt) accompanied by changes in the redox state. The molecular events triggered by Nampt include elevated production of NAD(+) and up-regulation of H2S producing enzymes, cystathionine beta synthase (CBS) and cystathionase (CTH) with 3-mercaptopyruvate sulfurtransferase (MST) being detectable only in 3D spheroids. Suppression of Nampt, or inactivation of H2S producing enzymes, all reduce H2S production and reverse the ability of cells to dedifferentiate. Moreover, H2S induced stem cell markers in parental cancer cells in a manner similar to that observed in damage recovered cells. These data suggest of existence of a positive feedback loop between H2S and Nampt that controls dedifferentiation in cancer cells that recover from a potentially lethal damage.

Are hematopoietic stem cells involved in hepatocarcinogenesis?

THE LIVER HAS THREE CELL LINEAGES ABLE TO PROLIFERATE AFTER A HEPATIC INJURY: the mature hepatocyte, the ductular "bipolar" progenitor cell termed "oval cell" and the putative periductular stem cell. Hepatocytes can only produce other hepatocytes whereas ductular progenitor cells are considerate bipolar since they can give rise to biliary cells or hepatocytes. Periductular stem cells are rare in the liver, have a very long proliferation potential and may be multipotent, being this aspect still under investigation. They originate in the bone marrow since their progeny express genetic markers of donor hematopoietic cells after bone marrow transplantation. Since the liver is the hematopoietic organ of the fetus, it is possible that hematopoietic stem cells may reside in the liver of the adult. This assumption is proved by the finding that oval cells express hematopoietic markers like CD34, CD45, CD 109, Thy-1, c-kit, and others, which are also expressed by bone marrow-derived hematopoietic stem cells (BMSCs). Few and discordant studies have evaluated the role of BMSC in hepatocarcinogenesis so far and further studies in vitro and in vivo are warranted in order to definitively clarify such an issue.