Competing endogenous RNAs regulatory crosstalk networks: The messages from the RNA world to signaling pathways directing cancer stem cell development.

Cancer stem cells (CSCs) are one of the cell types that account for cancer heterogeneity. The cancer cells arrest in G0 and generate non-CSC progeny through self-renewal and pluripotency, resulting in tumor recurrence, metastasis, and resistance to chemotherapy. They can stimulate tumor relapse and re-grow a metastatic tumor. So, CSCs is a promising target for eradicating tumors, and developing an anti-CSCs therapy has been considered. In recent years competing endogenous RNA (ceRNA) has emerged as a significant class of post-transcriptional regulators that affect gene expression via competition for microRNA (miRNA) binding. Furthermore, aberrant ceRNA expression is associated with tumor progression. Recent findings show that ceRNA network can cause tumor progression through the effect on CSCs. To overcome therapeutic resistance due to CSCs, we need to improve our current understanding of the mechanisms by which ceRNAs are implicated in CSC-related relapse. Thus, this review was designed to discuss the role of ceRNAs in CSCs' function. Targeting ceRNAs may open the path for new cancer therapeutic targets and can be used in clinical research.

Differential expression levels of ß-catenin are associated with invasive behavior of both functional and non-functional pituitary neuroendocrine tumor (PitNET).

BACKGROUND: Although research continues to elucidate the molecular mechanism underlying pituitary tumor pathogenesis, limited information is available on the potential role and expression profile of ß-catenin in functional and non-functional pituitary neuroendocrine tumors (PitNETs). METHODS AND RESULTS: In the current study, 104 pituitary samples (tumors and cadaveric healthy pituitary tissues) were included and the gene and protein expression levels of ß-catenin were assessed by Real-Time PCR and immunohistochemistry, respectively. The correlation between expression level of ß-catenin and tumor invasive feature and size as well as patient age, gender, and hormonal level was measured. The data showed that PitNET samples expressed higher levels of the ß-catenin gene and protein compared to healthy pituitary tissues. Although there was no difference in ß-catenin expression level between non-functioning (NF-PitNETs) and growth hormone-producing tumors (GH-PitNETs), both tumor types showed significantly elevated ß-catenin levels compared to healthy pituitary tissues. The high level of ß-catenin in the invasive functional and non-functional tumors is indicative of the association of ß-catenin with PitNETs invasion. The expression pattern of the ß-catenin gene and protein was consistently and significantly associated with these tumor types. The correlation between ß-catenin and insulin-like growth factor 1 (IGF-1) in GH-PitNETs indicates the potential relevance of ß-catenin and IGF-1 for GH-PitNETs. CONCLUSIONS: The simultaneous increase in the expression of ß-catenin gene and protein level in PitNET tissues and their relationship to the tumor severity indicates the possible contributing role of ß-catenin and its underlying signaling mediators in PitNET pathogenesis.

Purinergic receptors are a key bottleneck in tumor metabolic reprogramming: The prime suspect in cancer therapeutic resistance.

ATP and other nucleoside phosphates have specific receptors named purinergic receptors. Purinergic receptors and ectonucleotidases regulate various signaling pathways that play a role in physiological and pathological processes. Extracellular ATP in the tumor microenvironment (TME) has a higher level than in normal tissues and plays a role in cancer cell growth, survival, angiogenesis, metastasis, and drug resistance. In this review, we investigated the role of purinergic receptors in the development of resistance to therapy through changes in tumor cell metabolism. When a cell transforms to neoplasia, its metabolic processes change. The metabolic reprogramming modified metabolic feature of the TME, that can cause impeding immune surveillance and promote cancer growth. The purinergic receptors contribute to therapy resistance by modifying cancer cells' glucose, lipid, and amino acid metabolism. Limiting the energy supply of cancer cells is one approach to overcoming resistance. Glycolysis inhibitors which reduce intracellular ATP levels may make cancer cells more susceptible to anti-cancer therapies. The loss of the P2X7R through glucose intolerance and decreased fatty acid metabolism reduces therapeutic resistance. Potential metabolic blockers that can be employed in combination with other therapies will aid in the discovery of new anti-cancer immunotherapy to overcome therapy resistance. Therefore, therapeutic interventions that are considered to inhibit cancer cell metabolism and purinergic receptors simultaneously can potentially reduce resistance to treatment.

Up-regulation of matrix metalloproteinase-9 in primary bone tumors and its association with tumor aggressiveness.

BACKGROUND: Understanding the molecular mechanism underlying the pathophysiology of primary skeletal tumors is crucial due to the tumor-related complications, incidence at a young age, and tumor recurrence. METHODS AND RESULTS: The local expression pattern of MMP-9 as an active matrix-degrading protease was detected in 180 bone tissues, including 90 tumors and 90 noncancerous tissues, utilizing real-time qRT-PCR at the mRNA level and immunohistochemistry at the protein level. The correlation of the MMP-9 expression level with the patient's clinical pathological characteristics and the aggressiveness of the tumor was evaluated. The diagnostic significance of MMP-9 and the model of association of variables and MMP-9 expression and their predictive values were determined. Mean mRNA expression was higher in all types of primary bone tumors than their paired non-cancerous tissues. Osteosarcoma and Ewing's sarcoma expressed higher levels of MMP-9 compared to benign giant cell tumors, and the MMP-9 expression level was significantly correlated with the size, metastasis, and recurrence of the malignant tumor. A consistent expression pattern was demonstrated for MMP-9 protein levels in tissues. In addition, the MMP-9 gene and protein levels significantly discriminate between bone tumors and normal tissue, as well as benign and malignant tumors, and could predict potentially malignant traits such as tumor grade and metastasis. CONCLUSIONS: The data propose that MMP-9 may be involved in the proliferation and invasion of primary bone tumors and has the potential to monitor and treat the progression of malignant tumors.

Expression pattern and clinical significance of ß-catenin gene and protein in patients with primary malignant and benign bone tumors.

This study is aimed to unravel the status of local and circulating ß-catenin in different primary bone tumors and its relevance to tumor types, severity, and chemotherapy. The ß-catenin mRNA expression level and the expression of the protein (intensity level) were evaluated in tumor tissue and peripheral blood mononuclear cells of 150 patients with different types of primary bone tumors (78 malignant and 72 benign tumors) using Real-Time PCR and immunohistochemistry. The ß-catenin mRNA expression level and the expression of the protein were increased in bone tumors which was positively correlated with the tumor malignancy. Amongst osteosarcoma, Ewing's Sarcoma, chondrosarcoma, osteochondroma, Giant Cell Tumor, and exostosis tumors, the osteosarcoma, and Giant Cell Tumor groups showed the highest level of ß-catenin expression. The ß-catenin expression in malignant bone tumors was significantly correlated with tumor grade, size, metastasis, tumor recurrent, and the level of response to chemotherapy. A similar pattern of ß-catenin gene expression and its association with tumor characteristics was detected in the patient's peripheral blood cells. The simultaneous increase in the expression of the ß-catenin gene and protein in tumor tissue and in circulating blood cells and its relationship with tumor severity indicates the possible promoting role of ß-catenin in primary bone tumor pathogenesis.

Evaluation of the expression of necroptosis pathway mediators and its association with tumor characteristics in functional and non-functional pituitary adenomas.

BACKGROUND: Pituitary adenomas impose a burden of morbidity on patients and characterizing the molecular mechanisms underlying its pathogenesis received remarkable attention. Despite the appealing role of necroptosis as an alternative cell death pathway in cancer pathogenesis, its relevance to pituitary adenoma pathogenesis has yet to be determined that is perused in the current study. METHODS: The total number of 109 specimens including pituitary adenomas and cadaveric healthy pituitary tissues were enrolled in the current study. Tumor and healthy pituitary tissues were subjected to RNA extraction and gene analysis using Real-Time PCR. The expression levels of necroptosis markers (RIP1K, RIP3K and, MLKL) and their association with the patient's demographic features were evaluated, also the protein level of MLKL was assessed using immunohistochemistry in tissues. RESULTS: Based on our data, the remarkable reduction in RIP3K and MLKL expression were detected in nonfunctional and GH-secreting pituitary tumors compared to pituitary normal tissues. Invasive tumors revealed lower expression of RIP3K and MLKL compared to non-invasive tumors, also the attenuated level of MLKL was associated with the tumor size in invasive NFPA. The simultaneous down-regulation of MLKL protein in pituitary adenoma tissues was observed which was in line with its gene expression. While, RIP1K over-expressed significantly in both types of pituitary tumors which showed no significant correlation with patient's age, gender and tumor size in GHPPA and NFPA group. Notably, MLKL and RIP3K gene expression was significantly correlated in the GHPPA group. CONCLUSIONS: According to our data, the reduced expression of necroptosis mediators (RIP3K, MLKL) in pituitary adenoma reinforces the hypothesis that the necroptosis pathway can be effective in regulating the proliferation and growth of pituitary tumor cells and tumor recurrence.

Fndc5 knockdown induced suppression of mitochondrial integrity and significantly decreased cardiac differentiation of mouse embryonic stem cells.

Fibronectin type III domain-containing 5 protein (Fndc5) is a glycosylated protein with elevated expression in high energy demanded tissues as heart, brain, and muscle. It has been shown that upregulation of Fndc5 is regulated by peroxisome proliferator-activated receptor-γ coactivator-1 alpha (PGC-1α), which is known as a master regulator of mitochondrial function and biogenesis. Also, our group indicated that Fndc5 expression increases gradually during cardiac differentiation of mouse embryonic stem cells (mESCs). In this paper, to clarify the importance of Fndc5 in cardiac differentiation, we south to knock down Fndc5 expression by generation a stably transduced mESC line that derives the expression of a short hairpin RNA (shRNA) against Fndc5 gene following doxycycline (Dox) induction. Knock-down of Fndc5 demonstrated a considerable decrease in expression of cardiac progenitor and cardiomyocyte markers. Considering the fact that mitochondria play a crucial role in cardiac differentiation of ESCs, we investigated the role of Fndc5, as a downstream target of PGC1-α, on mitochondrial indices. Results showed that expression of nuclear encoded mitochondrial genes including PGC1-α, Atp5b, Ndufb5, and SOD2 significantly decreased. Moreover, mitochondrial membrane potential (ΔΨm) and relative ATP content of cardiomyocytes decreased markedly with relative ROS level increase. Together, our results suggest that Fndc5 attenuates process of cardiac differentiation of mESCs which is associated with modulation of mitochondrial function and gene expression.

How benzene and its metabolites affect human marrow derived mesenchymal stem cells.

Benzene is a known environmental pollutant with demonstrated leukemogenic activity. Marrow mesenchymal stem cells (MSCs), contribute to skeletal remodeling and repair. They also support haematopoiesis constructing important elements of haematopoietic niche. In the present study, the effects of a range of benzene concentrations along with those of its reactive metabolites, p-benzoquinone (BQ) and hydroquinone (HQ) on the viability of MSCs, apoptosis induction and caspase3/7 activity in these cells were analyzed. Our findings revealed that low concentrations of these chemicals (10µM of benzene, 5µM of either of BQ or HQ) significantly increase the number of chemically treated cells. Moreover, applied BQ/HQ concentrations were shown to be able to considerably inhibit caspase3/7 activity. While in benzene exposure experiments, the lowest concentration triggered the greatest increase in caspase3/7 activity during the initial hours of exposure. On the other hand, MSCs exposure to higher concentrations of benzene (100µM) and its metabolites, BQ/HQ (10µM and 50µM), can induce cell death after 24h of exposure mainly through apoptotic pathways. In addition, changes in the expression of six mRNAs due to being subjected to 10µM of BQ or HQ and 50µM of benzene were assessed. The genes under investigation were RUNX2, WNT5A, DKK1, JAG1, KITLG and CXCL12 which are expressed by MSCs playing roles in adipo-osteogenic differentiation of MSCs and the regulation of haematopoiesis. The analysis exhibited a great augmentation in RUNX2 expression associated with DKK1 and KITLG up-regulation. The results also indicated that treatment of cells with all three chemicals gives rise to down-regulation of JAG1 and treatment with both HQ and BQ triggers WNT5A over-expression. With regard to CXCL12, treatment with BQ caused slight up-regulation and treatment with HQ led to down-regulation. The alterations observed in the expression profile of genes could affect/modify the process of differentiation of MSCs into osteoblast. Other expected outcomes involve augmented canonical Wnt signaling activity in exposed cells with RUNX2 overexpression as the indicator which is probably forced to decrease to the normal level via DKK1 and WNT5A up-regulation. RUNX2 overexpression in MSCs can also be indicative of the RUNX2 up-regulation in myeloid progenitors thereby its involvement in AML development due to benzene exposure. Observed changes in the expression of WNT5A, DKK1, KITLG, CXCL12 and JAG1 can lead to the disturbance of HSC niche resulting in haematopoietic failure and leukemia development. It is obvious that increased viability together with caspase3/7 inhibition could aggravate the adverse effects of exposure to these chemicals.