PTEN expression and function in adult cancer stem cells and prospects for therapeutic targeting

The cellular signaling and regulatory role of protein phosphatase in tumor diagnosis: Upstream miRNAs of PTEN

Protein phosphatases have demonstrated considerable promise in the realm of early tumor diagnosis across various malignancies. These enzymes play a critical role in modulating the PI3K-Akt signaling pathway, which is integral to cellular processes such as proliferation, survival, and migration. When the activity of protein phosphatases becomes abnormal, it can disrupt these essential signaling pathways, potentially leading to the initiation and progression of tumors. Consequently, monitoring for abnormal expression and activity levels of protein phosphatases could serve as a vital biomarker for early cancer detection. By identifying these alterations, clinicians may be better equipped to diagnose tumors at an earlier stage, significantly improving patient outcomes.In summary, our study highlights the multifaceted and significant role of PTEN in various forms of cancer, including esophageal squamous cell carcinoma (ESCA). Further analysis showed that the expression levels of protein phosphatase and PTEN protein were significantly associated with the early diagnosis of tumors, especially in the early stage of tumors, and their detection sensitivity and specificity were high. Therefore, by detecting the expression of protein phosphatase and PTEN protein, the early diagnosis of tumor can be achieved, and the therapeutic effect and prognosis of patients can be improved.

Coexpression of TP53, BIM, and PTEN Enhances the Therapeutic Efficacy of Non-Small-Cell Lung Cancer

For non-small-cell lung cancer (NSCLC), the ubiquitous occurrence of concurrent multiple genomic alterations poses challenges to single-gene therapy. To increase therapeutic efficacy, we used the branch-PCR method to develop a multigene nanovector, NP-TP53-BIM-PTEN, that carried three therapeutic gene expression cassettes for coexpression. NP-TP53-BIM-PTEN exhibited a uniform size of 104.8 ± 24.2 nm and high serum stability. In cell transfection tests, NP-TP53-BIM-PTEN could coexpress TP53, BIM, and PTEN in NCI-H1299 cells and induce cell apoptosis with a ratio of up to 94.9%. Furthermore, NP-TP53-BIM-PTEN also inhibited cell proliferation with a ratio of up to 42%. In a mouse model bearing an NCI-H1299 xenograft tumor, NP-TP53-BIM-PTEN exhibited a stronger inhibitory effect on the NCI-H1299 xenograft tumor than the other test vectors without any detectable side effects. These results exhibited the potential of NP-TP53-BIM-PTEN as an effective and safe multigene nanovector to enhance NSCLC therapy efficacy, which will provide a framework for genome therapy with multigene combinations.

Danlou Tablet Protects Against Cardiac Remodeling and Dysfunction after Myocardial Ischemia/Reperfusion Injury through Activating AKT/FoxO3a Pathway

Myocardial ischemia/reperfusion injury (I/RI) and ventricular remodeling are the critical pathological basis of heart failure. Danlou tablet (Dan) is a kind of Chinese patent medicine used in angina pectoris treatment in China. However, it remains unclear whether and how Dan could protect against cardiac remodeling after myocardial I/RI. In this study, both preventive and therapeutic administration of Dan attenuated ventricular remodeling and cardiac dysfunction at 3 weeks after myocardial I/RI. Dan inhibited Bax/Bcl2 ratio and Caspase3 cleavage in heart tissues and also inhibited apoptosis of human AC16 cells and neonatal rat cardiomyocytes stressed by oxygen and glucose deprivation/reperfusion. Mechanistically, Dan inhibited myocardial apoptosis through phosphorylating AKT and FoxO3a, thereby inhibiting downstream BIM and PUMA expressions. Collectively, these results demonstrate that Dan treatment is effective to protect against cardiac remodeling and dysfunction after myocardial I/RI and provide theoretical basis for its cardioprotection and clinical application in treating ischemic cardiac diseases.

Inhibitory Effects of Ursolic Acid on the Stemness and Progression of Human Breast Cancer Cells by Modulating Argonaute-2

The stemness and metastasis of cancer cells are crucial features in determining cancer progression. Argonaute-2 (AGO2) overexpression was reported to be associated with microRNA (miRNA) biogenesis, supporting the self-renewal and differentiation characteristics of cancer stem cells (CSCs). Ursolic acid (UA), a triterpene compound, has multiple biological functions, including anticancer activity. In this study, we find that UA inhibits the proliferation of MDA-MB-231 and MCF-7 breast cancer cell lines using the CCK-8 assay. UA induced a significant decrease in the fraction of CSC in which it was examined by changes in the expression of stemness biomarkers, including the Nanog and Oct4 genes. UA altered invasion and migration capacities by significant decreases in the levels of epithelial-to-mesenchymal transition (EMT) proteins of slug and vimentin. Furthermore, the co-reduction in oncogenic miRNA levels (miR-9 and miR-221) was a result of the down-modulation in AGO2 in breast cancer cells in vitro. Mechanically, UA increases PTEN expression to inactivate the FAK/PI3K/Akt/mTOR signaling pathway and the decreased level of c-Myc in quantitative RT-PCR and Western blot imaging analyses. Our current understanding of the anticancer potential of UA in interrupting between EMT programming and the state of CSC suggests that UA can contribute to improvements in the clinical practice of breast cancer.

Fibroblast-Induced Paradoxical PI3K Pathway Activation in PTEN-Competent Colorectal Cancer: Implications for Therapeutic PI3K/mTOR Inhibition

Purpose

Tumor-microenvironment interactions are important determinants of drug resistance in colorectal cancer (CRC). We, therefore, set out to understand how interactions between genetically characterized CRC cells and stromal fibroblasts might influence response to molecularly targeted inhibitors.

Techniques

Sensitivity to PI3K/AKT/mTOR pathway inhibitors of CRC cell lines, with known genetic background, was investigated under different culture conditions [serum-free medium, fibroblasts’ conditioned medium (CM), direct co-culture]. Molecular pathway activation was monitored using Western Blot analysis. Immunoprecipitation was used to detect specific mTOR complex activation. Immunofluorescence was used to analyze cellular PTEN distribution, while different mutant PTEN plasmids were used to map the observed function to specific PTEN protein domains.

Results

Exposure to fibroblast-CM resulted in increased growth-inhibitory response to double PI3K/mTOR inhibitors in PTEN-competent CRC cell lines harboring KRAS and PI3K mutations. Such functional effect was attributable to fibroblast-CM induced paradoxical PI3K/mTORC1 pathway activation, occurring in the presence of a functional PTEN protein. At a molecular level, fibroblast-CM induced C-tail phosphorylation and cytoplasmic redistribution of the PTEN protein, thereby impairing its lipid phosphatase function and favored the formation of active, RAPTOR-containing, mTORC1 complexes. However, PTEN’s lipid phosphatase function appeared to be dispensable, while complex protein-protein interactions, also involving PTEN/mTOR co-localization and subcellular distribution, were crucial for both mTORC1 activation and sensitivity to double PI3K/mTOR inhibitors.

Data Interpretation

Microenvironmental cues, in particular soluble factors produced by stromal fibroblasts, profoundly influence PI3K pathway signaling and functional response to specific inhibitors in CRC cells, depending on their mutational background and PTEN status.

USP22-mediated deubiquitination of PTEN inhibits pancreatic cancer progression by inducing p21 expression

Phosphatase and tensin homolog deleted on chromosome ten (PTEN) is a dual lipid and protein phosphatase. Multiple mechanisms contributing to the regulation of PTEN levels have been identified thus far, including post-translational modifications, epigenetic mechanisms, and transcriptional mechanisms. In the present study, we identified ubiquitin-specific peptidase 22 (USP22) as a novel deubiquitination-modifying enzyme of PTEN. Furthermore, by inducing deubiquitination and inhibiting the degradation of PTEN, USP22 could induce cyclin-dependent kinase inhibitor 1A (CDKN1A, also symboled as p21) expression in pancreatic cancer. Besides, MDM2 proto-oncogene (MDM2) inhibitor enhanced the antipancreatic cancer effects of USP22 overexpression. In addition to its regulation of MDM2-tumor protein p53 (p53) signaling, we found that PTEN could induce p21 expression by interacting with ankyrin repeat and KH domain containing 1 (ANKHD1) and inhibiting ANKHD1 binding to the p21 promoter. Taken together, our results indicate that ANKHD1 and MDM2 might be novel therapeutic targets in pancreatic cancer.

[Effects of lentivirus-mediated RNA interference of HIF-1α and PTEN on oxygen-glucose deprivation injury in primary cultured rat neurons]

OBJECTIVE

To observe the effects of lentivirus-mediated RNA interference (RNAi) of hypoxia-inducible factor 1α (HIF-1α) and phosphatase and tensin homolog on chromosome ten (PTEN) on oxygen-glucose deprivation (OGD) injury in primary cultured rat neurons.

METHODS

Primary cultures of neonatal SD rat neurons were infected by lentiviral vectors carrying short hairpin RNA (shRNA) targeting HIF-1α or PTEN followed 4 days later by hypoxic exposure, and the control neurons were infected with the empty virus only with or without subsequent hypoxic exposure. Twenty-four hours after hypoxia, the interference efficiency was assessed with qRT-PCR, and lactate dehydrogenase (LDH) assay and AnnexinV-FITC/ PI assay were performed to detect neuronal damage and apoptosis. The expressions of the related proteins were determined with Western blotting.

RESULTS

Lentivirus-mediated RNAi effectively silenced the mRNA expression of the target genes. HIF-1α silencing obviously aggravated the hypoxia-induced damage and apoptosis of the neurons, enhanced the expression of PTEN protein and significantly lowered the expressions of p-PTEN, p-AKT, NR2A and VEGFa (P < 0.05). PTEN silencing significantly alleviated hypoxia-induced damage and apoptosis of the neurons and increased the cellular expressions of p-PTEN and p-AKT (P < 0.05) without obviously affecting the expressions of HIF-1α, NR2A or VEGFa (P>0.05).

CONCLUSION

An up-regulated expression of HIF-1α causes down-regulation of PTEN expression to protect primary cultured rat neurons against OGD injury.

MicroRNAs and exosomes: Cardiac stem cells in heart diseases

Treating cardiovascular diseases with cardiac stem cells (CSCs) is a valid treatment among various stem cell-based therapies. With supplying the physiological need for cardiovascular cells as their main function, under pathological circumstances, CSCs can also reproduce the myocardial cells. Although studies have identified many of CSCs' functions, our knowledge of molecular pathways that regulate these functions is not complete enough. Either physiological or pathological studies have shown, stem cells proliferation and differentiation could be regulated by microRNAs (miRNAs). How miRNAs regulate CSC behavior is an interesting area of research that can help us study and control the function of these cells in vitro; an achievement that may be beneficial for patients with cardiovascular diseases. The secretome of stem and progenitor cells has been studied and it has been determined that exosomes are the main source of their secretion which are very small vesicles at the nanoscale and originate from endosomes, which are secreted into the extracellular space and act as key signaling organelles in intercellular communication. Mesenchymal stem cells, cardiac-derived progenitor cells, embryonic stem cells, induced pluripotent stem cells (iPSCs), and iPSC-derived cardiomyocytes release exosomes that have been shown to have cardioprotective, immunomodulatory, and reparative effects. Herein, we summarize the regulation roles of miRNAs and exosomes in cardiac stem cells.

Long non-coding RNAs as new players in bladder cancer: Lessons from pre-clinical and clinical studies

The clinical management of bladder cancer (BC) has become an increasing challenge due to high incidence rate of BC, malignant behavior of cancer cells and drug resistance. The non-coding RNAs are considered as key factors involved in BC progression. The long non-coding RNAs (lncRNAs) are RNA molecules and do not encode proteins. They have more than 200 nucleotides in length and affect gene expression at epigenetic, transcriptional and post-transcriptional phases. The lncRNAs demonstrate abnormal expression in BC cells and tissues. The present aims to identifying lncRNAs with tumor-suppressor and tumor-promoting roles, and evaluating their roles as regulatory of growth and migration. Apoptosis, glycolysis and EMT are tightly regulated by lncRNAs in BC. Response of BC cells to cisplatin, doxorubicin and gemcitabine chemotherapy is modulated by lncRNAs. LncRNAs regulate immune cell infiltration in tumor microenvironment and affect response of BC cells to immunotherapy. Besides, lncRNAs are able to regulate microRNAs, STAT3, Wnt, PTEN and PI3K/Akt pathways in affecting both proliferation and migration of BC cells. Noteworthy, anti-tumor compounds and genetic tools such as siRNA, shRNA and CRISPR/Cas systems can regulate lncRNA expression in BC. Finally, lncRNAs and exosomal lncRNAs can be considered as potential diagnostic and prognostic tools in BC.

Tissue distribution and developmental changes of PTEN in the immune organs of chicken and effect of IBDV infection on it

Phosphatase and tensin homolog (PTEN), a tumor suppressor gene, functions in antiviral innate immunity and regulates the development and function of T cells and B cells. However, limited information about PTEN is available in poultry. In the present study, quantitative real-time polymerase chain reaction and immunohistochemistry staining were used to study the tissue distribution and developmental changes of PTEN in the main immune organs of chicken. The effects of infectious bursal disease virus (IBDV) infection on PTEN mRNA expression in the bursa of Fabricius (BF) of chickens were also investigated. The results are as follows. 1) The order of PTEN mRNA expression levels at the 18th d of hatching (E18) was: muscle and immune organs (spleen and thymus) > visceral organs (heart, lung, kidney, and liver) > hypothalamus and digestive tracts (duodenum, jejunum, ileum, cecum, proventriculus, BF [originates from cloaca], and cecum tonsil [locates at the lamina propria of cecum]). However, at the 15th d of raising (D15), the PTEN mRNA expression in the heart was the highest among all the tissues, followed by those in the liver, proventriculus, and kidney. The PTEN mRNA expression levels in the rest tissues were very low and were only 1.20 to 19.47% as much as that in the heart (P < 0.05). 2) The changes in the expression of PTEN mRNA in the BF, spleen, and thymus from E15 to D15 had no obvious regularity. PTEN-immunopositive (PTEN-ip) cells in the BF were distributed in epithelium mucosa, bursal follicles and interfollicles before hatching, but only in bursal follicles after hatching. PTEN-ip cells in the spleen were expressed in the periarterial lymphatic sheath from E18 to D15. Most of PTEN-ip cells distributed in the thymic medulla and only a few distributed in the thymic cortex during the whole experiment. 3) Chicken with IBDV infection had a remarkable decrease in PTEN mRNA expression from 1 d postinfection (dpi) to 7 dpi. Although PTEN mRNA level was reversed at 7 dpi, it was still significantly lower than that at 0 dpi (P < 0.05). These findings suggest that the PTEN of chicken might play important roles in the development of embryos and T/B lymphocytes, and the downregulation of PTEN in chickens infected with IBDV might be a mechanism of IBDV evasion from host immunity. Strategies designed to restore PTEN expression may be a therapy for preventing chickens from IBDV infection.

miR‑130b regulates PTEN to activate the PI3K/Akt signaling pathway and attenuate oxidative stress‑induced injury in diabetic encephalopathy

Diabetic encephalopathy (DE) is one of the main chronic complications of diabetes, and is characterized by cognitive defects. MicroRNAs (miRNAs/miRs) are widely involved in the development of diabetes-related complications. The present study evaluated the role of miR-130b in DE and investigated its mechanisms of action. PC12 cells and hippocampal cells were exposed to a high glucose environment to induce cell injuries to mimic the in vitro model of DE. Cells were transfected with miR-130b mimic, miR-130b inhibitor and small interfering RNA (si)-phosphatase and tensin homolog (PTEN) to evaluate the protective effect of the miR-130b/PTEN axis against oxidative stress in high glucose-stimulated cells involving Akt activity. Furthermore, the effect of agomir-130b was also assessed on rats with DE. The expression of miR-130b was reduced in the DE models in vivo and in vitro. The administration of miR-130b mimic increased the viability of high glucose-stimulated cells, prevented apoptosis, increased the activity of superoxide dismutase (SOD), decreased the malondialdehyde (MDA) content, activated Akt protein levels and inhibited the mitochondria-mediated apoptotic pathway. The administration of miR-130b inhibitor exerted opposite effects, while si-PTEN reversed the effects of miR-130b inhibitor. In vivo, the administration of agomir-130b attenuated cognitive disorders and neuronal damage, increased SOD activity, reduced the MDA content, activated Akt protein levels and inhibited the mitochondria-mediated apoptosis pathway in rats with DE. On the whole, these results suggest that miR-130b activates the PI3K/Akt signaling pathway to exert protective effects against oxidative stress injury via the regulation of PTEN in rats with DE.

LncRNA PlncRNA-1 accelerates the progression of prostate cancer by regulating PTEN/Akt axis

Long non-coding RNAs are key regulators of tumor development and progression, with the potential to be biomarkers of tumors. This study aimed to explore the role of PlncRNA-1 in the progression of prostate cancer (PCa). We found that PlncRNA-1 was up-regulated in 85.29% of PCa tissues and could predict the T stage of PCa patients to a certain extent. Results showed that inhibition of PlncRNA-1 expression potentially promoted cell apoptosis, suppressed the proliferation, migration, and invasion of cells, and triggered G2/M cycle arrest in vitro and in vivo. PlncRNA-1 was mainly localized in the nucleus and PlncRNA-1 expression and phosphatase and tensin homologue (PTEN) expression were negatively correlated. Mechanistically, knockdown of PlncRNA-1 increased expression levels of PTEN protein and phosphorylated PTEN protein, and decreased expression levels of Akt protein and phosphorylated Akt protein. Rescue experiments demonstrated that PTEN inhibitors abolished the changes in PTEN/Akt pathway caused by PlncRNA-1 interference. PlncRNA-1 can promote the occurrence and development of PCa via the PTEN/Akt pathway. PlncRNA-1 may, therefore, be a new candidate target for the treatment of PCa.

Inhibition of breast cancer stem-like cells by a triterpenoid, ursolic acid, via activation of Wnt antagonist, sFRP4 and suppression of miRNA-499a-5p

Breast cancer, one of the leading causes of death in the world, has been largely considered to be drug resistant because of a small population of drug refractory cells, the cancer stem cells (CSCs). The CSCs are tightly regulated by self-renewal pathways such as the Wnt pathway, which is further regulated by a gamut of microRNAs. In this study, we investigated the effect of ursolic acid (UA), a natural triterpene, on breast CSCs enriched from breast cancer cell lines, MCF7, MDA-MB-231 and T47D and analysed the interplay of the Wnt inhibitor, sFRP4 and an miRNA, miR-499a-5p, in mediating the effect of UA. By using caspase 3/7, ROS, migration, TCF/LEF and CAM assays, overexpressing and inhibiting miR-499a-5p and NanoString PanCancer analysis, we observed that UA had significant anti-CSC ability. There was a link between UA and Wnt/β-catenin pathway wherein, Wnt was suppressed by upregulation of the antagonist, sFRP4. Furthermore, expression of the oncogenic miR-499a-5p was substantially diminished in CSCs after UA treatment. Notably, the axis by which miR-499a-5p acts is via the TCF/LEF machinery of the Wnt/β-catenin pathway. Our findings indicate for the first time that UA can target breast CSCs via Wnt by suppressing miR-499a-5p and upregulating the Wnt antagonist, sFRP4.

BRAF status modulates Interelukin-8 expression through a CHOP-dependent mechanism in colorectal cancer

Inflammation might substantially contribute to the limited therapeutic success of current systemic therapies in colorectal cancer (CRC). Amongst cytokines involved in CRC biology, the proinflammatory chemokine IL-8 has recently emerged as a potential prognostic/predictive biomarker. Here, we show that BRAF mutations and PTEN-loss are associated with high IL-8 levels in CRC models in vitro and that BRAF/MEK/ERK, but not PI3K/mTOR, targeting controls its production in different genetic contexts. In particular, we identified a BRAF/ERK2/CHOP axis affecting IL-8 transcription, through regulation of CHOP subcellular localization, and response to targeted inhibitors. Moreover, RNA Pol II and an open chromatin status in the CHOP-binding region of the IL-8 gene promoter cooperate towards increased IL-8 expression, after a selective BRAF inhibition. Overall, our data show that IL-8 production is finely and differentially regulated depending on the tumor genetic context and might be targeted for therapeutic purposes in molecularly defined subgroups of CRC patients.

Conciatori et al find that BRAF mutations and PTEN-loss promote IL-8 production in colorectal cancer cell (CRC) lines and identify a genetic-context-dependent BRAF/ERK2/CHOP molecular axis that controls IL-8 transcription. These data may assist in the identification of drugs to target CRC.

PTEN Function at the Interface between Cancer and Tumor Microenvironment: Implications for Response to Immunotherapy

Mounting preclinical and clinical evidence indicates that rewiring the host immune system in favor of an antitumor microenvironment achieves remarkable clinical efficacy in the treatment of many hematological and solid cancer patients. Nevertheless, despite the promising development of many new and interesting therapeutic strategies, many of these still fail from a clinical point of view, probably due to the lack of prognostic and predictive biomarkers. In that respect, several data shed new light on the role of the tumor suppressor phosphatase and tensin homolog on chromosome 10 (PTEN) in affecting the composition and function of the tumor microenvironment (TME) as well as resistance/sensitivity to immunotherapy. In this review, we summarize current knowledge on PTEN functions in different TME compartments (immune and stromal cells) and how they can modulate sensitivity/resistance to different immunological manipulations and ultimately influence clinical response to cancer immunotherapy.

miRNA-186 Improves Sepsis Induced Renal Injury Via PTEN/PI3K/AKT/P53 Pathway

Aim

The aim of this study is to explain the effects of miRNA-186 in renal injury induced by sepsis.

Methods

The Wistar rats were divided into 3 groups: the Sham group, Sepsis model group and the miRNA-186 group based on the model group; there were 9 rats in every group. The rat sepsis model was reproduced by cecal ligation and puncture (CLP). The rats of the miRNA-186 group were injected miRNA-186 from caudal vein. The rats of the difference group were killed after operation 24 h. The kidneys of the difference groups were taken for histopathological and cell apoptosis analysis by H&E and TUNEL assay. The relative protein expressions were measured by WB assay. miRNA-186 target to Phosphatase and tensin homologous protein (PTEN).

Results

Compared with the Sham group, the kidney histopathological and cell apoptosis rates of the model group were significantly damaged (P<0.05, respectively), however, the kidney histopathological and cell apoptosis rate of miRNA-186 group were significantly improved compared with the model group (P<0.05, respectively). The relative protein expressions were significantly different among 3 groups (P<0.05, respectively). The PTEN was the target of the miRNA-186.

Conclusion

miRNA-186 over-expression has effects that improve renal injury induced by sepsis via PTEN pathway.

MicroRNA-18a induces epithelial-mesenchymal transition like cancer stem cell phenotype via regulating RKIP pathway in pancreatic cancer

Background

Pancreatic cancer is a devastating invasive disease. Understanding the molecular mechanism of metastasis of this cancer is basis for its treatment and prevention.

Methods

Pancreatic cancer tissues and normal adjacent tissues were collected from patients tour hospital. Western blotting and a sphere growth and invasion assay were performed to conduct analysis. Pancreatic ductal adenocarcinoma cell Line PANC-1 were cultured. To test the level of Raf-1 kinase inhibitor protein (RKIP), immunofluorescence analyses were performed.

Results

In this study, we showed that expression of RKIP was downregulated in pancreatic cancer. RKIP can inhibit epithelial to mesenchymal transition (EMT) in PANC-1 cells. MicroRNA-181a (miR-181a) has a high expression in pancreatic cancer and can induce EMT phenotype by directly degrading RKIP in pancreatic cancer PANC-1 cells.

Conclusions

We concluded that miR-181a induces EMT phenotype through its regulation of RKIP in pancreatic cancer. MicroRNA-18a may be a novel target in the treatment of pancreatic cancer in future.

Modern Perspective on Metabolic Reprogramming in Malignant Neoplasms

Metabolic reprogramming is one of the central features of transformed cells. Elucidation of interactions between oncogenic signaling and cell metabolic processes has become the basis for extensive studies of metabolism reprogramming in tumor tissue. The review summarizes the key results of studies on the catabolic and anabolic rearrangements in tumor cells with special emphasis on carbohydrate, lipid, amino acid, and acetate metabolism determining the cancer phenotype of cells.

Molecular Alterations Associated with DNA Repair in Pancreatic Adenocarcinoma Are Associated with Sites of Recurrence

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) remains one of the deadliest malignancies with a rising incidence. Mutational analysis of PDAC has provided valuable information but has not yet dramatically changed the therapeutic landscape due to the number of variations detected in any one individual. The pattern of molecular alterations-gene mutations, variations in copy number, and changes in gene expression-has been described in the literature. The purpose of this study is to further investigate the molecular alterations in recurrent or metastatic PDAC based on the site of disease.

METHODS

Molecular alterations in patients with recurrent or metastatic PDAC from 2007 to 2015 were analyzed. The most common molecular alterations found in PDAC tumors from the pancreas were compared to metastatic PDAC specimens from the liver, lung, peritoneum, and other locations. Means were compared with a two-tailed Student's t test or ANOVA as appropriate. Rates of molecular alterations among the different groups were compared with Pearson's χ².

RESULTS

Two thousand five hundred fifty-two patients with PDAC were identified in a retrospective database, and the 15 most common molecular alterations were utilized for analysis. The most common alterations among all patients were mutations in KRAS and PTEN (59 and 62%, respectively), with differences in prevalence by site of metastasis (p = 0.042 and p = 0.037, respectively). KRAS mutations were more commonly found in metastasis in the lung (72%) than in other sites (59%, p = 0.042). Low expression of ERCC1 was found in 49% of lung metastases from PDAC but only 15% in PDAC in the pancreas (p < 0.001). Five of the 8 molecular alterations significantly associated with site of metastatic disease were involved in DNA maintenance, repair, replication, or transcription (each p < 0.001).

CONCLUSIONS

Aberrant expression or mutation in genes involved in DNA maintenance is found in association with specific sites of metastatic PDAC. Personalizing therapy for metastatic PDAC based on site of disease and their associated molecular alterations warrants further investigation.

PTEN Tumor-Suppressor: The Dam of Stemness in Cancer

PTEN is one of the most frequently inactivated tumor suppressor genes in cancer. Loss or variation in PTEN gene/protein levels is commonly observed in a broad spectrum of human cancers, while germline PTEN mutations cause inherited syndromes that lead to increased risk of tumors. PTEN restrains tumorigenesis through different mechanisms ranging from phosphatase-dependent and independent activities, subcellular localization and protein interaction, modulating a broad array of cellular functions including growth, proliferation, survival, DNA repair, and cell motility. The main target of PTEN phosphatase activity is one of the most significant cell growth and pro-survival signaling pathway in cancer: PI3K/AKT/mTOR. Several shreds of evidence shed light on the critical role of PTEN in normal and cancer stem cells (CSCs) homeostasis, with its loss fostering the CSC compartment in both solid and hematologic malignancies. CSCs are responsible for tumor propagation, metastatic spread, resistance to therapy, and relapse. Thus, understanding how alterations of PTEN levels affect CSC hallmarks could be crucial for the development of successful therapeutic approaches. Here, we discuss the most significant findings on PTEN-mediated control of CSC state. We aim to unravel the role of PTEN in the regulation of key mechanisms specific for CSCs, such as self-renewal, quiescence/cell cycle, Epithelial-to-Mesenchymal-Transition (EMT), with a particular focus on PTEN-based therapy resistance mechanisms and their exploitation for novel therapeutic approaches in cancer treatment.

miR-19b-3p promotes human pancreatic cancer Capan-2 cells proliferation by targeting phosphatase and tension homolog

Background

Pancreatic cancer is a common cancer with a poor prognosis and an increasing morbidity. miR-19b-3p has been implicated in some cancers, however, its role in pancreatic cancer is unclear.

Methods

Human pancreatic cancer cell line Capan-2 cells were transfected with miR-19b-3p mimic and inhibitor. Cell proliferation was measured by 5-Ethynyl-2'-deoxyuridine (EdU) staining assays. Cell cycle of Capan-2 cells was examined by flow cytometry. The expression of phosphatase and tension homolog (PTEN) was determined by real-time quantitative polymerase chain reaction (PCR) and western blotting analysis. Functional rescue experiments were performed through PTEN overexpression and miR-19b-3p mimic by using EdU staining assays.

Results

miR-19b-3p mimic significantly increased miR-19b-3p while miR-19b-3p inhibitor decreased that. EdU staining showed that miR-19b-3p overexpression promoted Capan-2 cells proliferation while miR-19b-3p inhibition decreased that. Flow cytometry analysis of cell cycle indicated that miR-19b-3p overexpression increased the percentage of Capan-2 cells in S phase while miR-19b-3p inhibition decreased that. PTEN was confirmed to be a target gene of miR-19b-3p and PTEN overexpression eliminated the pro-proliferation effects of miR-19b-3p in Capan-2 cells.

Conclusions

Our study demonstrates that miR-19b-3p promotes Capan-2 cells proliferation by targeting PTEN.

miR-140-3p Knockdown Suppresses Cell Proliferation and Fibrogenesis in Hepatic Stellate Cells via PTEN-Mediated AKT/mTOR Signaling

PURPOSE

Liver fibrosis is a major cause of morbidity and mortality and the outcome of various chronic liver diseases. Activation of hepatic stellate cells (HSCs) is the key event in liver fibrosis. Studies have confirmed that miR-140-3p plays a potential regulatory effect on HSC activation. However, whether miR-140-3p mediates the liver fibrosis remains unknown.

MATERIALS AND METHODS

Expression of miR-140-3p was detected by real-time quantitative PCR (qPCR). Cell proliferation was measured by MTT, while cell apoptosis rate was determined via flow cytometry. Western blot assay was used to detect the expression of cleaved PARP. The fibrogenic effect was evaluated by expression of α-smooth muscle actin and desmin. Functional experiments were performed in transforming growth factor β1 (TGF-β1)-induced HSC-T6 cells with transfection of anti-miR-140-3p and/or siPTEN. Target binding between miR-140-3p and PTEN was predicted by the TargetScan database and identified using luciferase reporter assay and RNA immunoprecipitation.

RESULTS

TGF-β1 induced the activation of HSC-T6 cells, and miR-140-3p expression varied according to HSC-T6 cell activation status. Knockdown of miR-140-3p reduced cell proliferation and the expressions of α-SMA and desmin, as well as increased apoptosis, in TGF-β1-induced HSC-T6 cells, which could be blocked by PTEN silencing. Additionally, inactivation of the AKT/mTOR signaling pathway stimulated by miR-140-3p knockdown was abolished when silencing PTEN expression. PTEN was negatively regulated by miR-140-3p via direct binding in HSC-T6 cells.

CONCLUSION

miR-140-3p is an important mediator in HSC-T6 cell activation, and miR-140-3p knockdown suppresses cell proliferation and fibrogenesis in TGF-β1-induced HSC-T6 cells, indicating that miR-140-3p may be a potential novel molecular target for liver fibrosis.

Acrylamide induces HepG2 cell proliferation through upregulation of miR-21 expression

Acrylamide, a potential carcinogen, exists in carbohydrate-rich foods cooked at a high temperature. It has been reported that acrylamide can cause DNA damage and cytotoxicity. The present study aimed to investigate the potential mechanism of human hepatocarcinoma HepG2 cell proliferation induced by acrylamide and to explore the antagonistic effects of a natural polyphenol curcumin against acrylamide via miR-21. The results indicated that acrylamide (≤100 μmol/L) significantly increased HepG2 cell proliferation and miR-21 expression. In addition, acrylamide reduced the PTEN expression in protein level, while induced the expressions of p-AKT, EGFR and cyclin D1. The PI3K/AKT inhibitor decreased p-AKT protein expression and inhibited the proliferation of HepG2 cells. In addition, curcumin effectively reduced acrylamide-induced HepG2 cell proliferation and induced apoptosis through the expression of miR-21. In conclusion, the results showed that acrylamide increased HepG2 cell proliferation via upregulating miR-21 expression, which may be a new target for the treatment and prevention of cancer.

Oncosuppressor-Mutated Cells as a Liquid Biopsy Test for Cancer-Screening

We reported on the ability of immortalized or oncosuppressor-mutated cells (OMCs) to uptake circulating cancer-factors and give tumors when transplanted into mice. This led to the first biological based liquid biopsy test, which we called MATER-D platform. In the present study, we showed for the first time that a different type of OMCs (PTEN-deficient human epithelial MCF10A cells) turn malignant when exposed to cancer patient’s sera, confirming the concept that different cells with diverse oncosuppressor mutations can uptake cancer factors and be used in biological based liquid biopsy tests. Our observations were confirmed in a large variety of solid and haematological malignancies. This test was able to detect dysplasia and carcinomas in situ lesions in different organs and circulating factors in cancer patients years after the removal of their lesions. To our knowledge, this ability is unique and not shared by other liquid biopsy platforms. Immunohistochemistry analysis of the xenotransplants revealed identical patterns of differentiation regardless of the cancer type, showing that differentiation through horizontal transfer might be dependent on the nature of the target cells rather than the type of cancer factors. These data strengthen the notion that OMC-based liquid biopsy tests might be promising platforms for cancer screening.

Naringin sensitizes human prostate cancer cells to paclitaxel therapy

BACKGROUND

The aim of the study was to evaluate whether the use of chemotherapy in combination with naringin, a dietary plant polyphenolic flavonoid, could enhance the therapeutic efficacy of paclitaxel treatment in human prostate cancer (PCa) cells.

MATERIALS AND METHODS

DU145, PC3, and LNCaP cells were treated with various concentrations of paclitaxel, naringin, and their combinations. Methylthiazolyldiphenyl-tetrazolium bromide (MTT), image-based cytometer, quantitative reverse transcription PCR (RT-qPCR), Western blot, and transwell assay were used to evaluate cell viability, apoptosis and cell cycle, the mRNA expression, protein expression, and cell migration, respectively.

RESULTS

Naringin treatment inhibited cell survival in a dose- and time-dependent manner by inducing apoptosis and cell cycle arrest in G1 phase. Among the pathways evaluated, naringin (150 μM) significantly induced the mRNA expressions of BAX, BID, caspase 3, cytochrome c, p53, p21 Cip1 , and p27 Kip1  and downregulated the expressions of survivin and livin in DU145 cells. The combination of naringin and paclitaxel treatments synergistically increased the cytotoxic effects of paclitaxel in androgen-independent DU145 and PC3 cells, as well as in androgen-sensitive LNCaP cells. The combination of naringin with docetaxel has almost the same inhibitory effect on cell proliferation as the paclitaxel combination in androgen-independent cells, whereas there is no similar effect in LNCaP cells. Naringin exhibits significant inhibitory effects on the cell migration ability. The flavonoid either alone or in combination with paclitaxel therapy resulted in an increase in tumor suppressor PTEN (phosphatase and tensin homolog deleted on chromosome 10) protein expression and decrease in nuclear factor-κB p50 protein level in DU145 cells.

CONCLUSION

In conclusion, naringin acts as a chemosensitizer which synergistically strengths the cytotoxic effect of paclitaxel in PCa cells. Therefore, naringin therapy alone or in combination with paclitaxel may be useful in the treatment of PCa. However, there is a need for more detailed in vivo studies of the mechanism of action.

Molecular iodine inhibits the expression of stemness markers on cancer stem-like cells of established cell lines derived from cervical cancer

BACKGROUND

Cancer stem cells (CSC) are characterized by deregulated self-renewal, tumorigenicity, metastatic potential, aberrant stemness signaling pathways, resistance to conventional therapy, and the ability to give rise to a progeny of proliferating cells that constitute the bulk of tumors. Targeting CSC will provide novel treatments for cancer. Different investigations have focused on developing complementary approaches that involve natural compounds that decrease chemo-resistance and reduce the side effects of conventional therapies. Since, it has been reported that molecular iodine (I₂) exhibits antineoplastic effects and decreases tumor progression in some cancer models, we evaluated the potential effect of I₂ on cell cultures enriched in cervical cancer stem-like cells.

METHODS

HeLa and SiHa cervical cancer cells were treated with 200uM I₂ for 24 h. After time, cells were cultured in CSC-conditioned medium (cervospheres) and viability assays were performed. Following, tumorigenic capabilities in cervospheres treated with I₂ were evaluated in NOD/SCID mice. HeLa monolayer cells untreated and their respective cervosphere cells treated or untreated with 200 μM of I₂ for 24 h were xenotransplanted subcutaneously at different amounts and mice were monitored for at least 2 months.

RESULTS

In the present study, monolayer and CSC-enriched cultures (cervospheres) from cervical cancer-derived cell lines, HeLa and SiHa, showed that 200uM I₂ supplementation inhibits proliferation of both and decreased their tumorigenic capacity, in vivo. This antineoplastic effect of I₂ was accompanied by diminished expression of stemness markers including CD49f, CK17, OCT-4, NANOG, SOX2, and KLF4, as well as increased expression and activation of PPARγ receptors.

CONCLUSIONS

All this data led us to suggest a clinical potential use of I₂ for targeting CSC and improve current treatments against cervical cancer.

PI3K/Akt and HIF‑1 signaling pathway in hypoxia‑ischemia (Review)

Hypoxia-ischemia (H-I) is frequently observed in perinatal asphyxia and other diseases. It can lead to serious cardiac injury, cerebral damage, neurological disability and mortality. Previous studies have demonstrated that the phosphatidylinositol-3 kinase (PI3K)/protein kinase B (Akt) signaling pathway, which regulates a wide range of cellular functions, is involved in the resistance response to H-I through the activation of proteins associated with survival and inactivation of apoptosis-associated proteins. It can also regulate the expression of hypoxia-induced factor-1α (HIF-1α). HIF-1α can further regulate the expression of downstream proteins involved in glucose metabolism and angiogenesis, such as vascular endothelial growth factor and erythropoietin, to facilitate ischemic adaptation. Notably, HIF-1α may also induce detrimental effects. The effects of HIF-1 on ischemic outcomes may be dependent on the H-I duration, animal age and species. Thus, further investigation of the PI3K/Akt signaling pathway may provide further insights of the potential targets for treating diseases accompanied by H-I.

Emerging functional markers for cancer stem cell-based therapies: Understanding signaling networks for targeting metastasis

Metastasis is one of the most challenging issues in cancer patient management, and effective therapies to specifically target disease progression are missing, emphasizing the urgent need for developing novel anti-metastatic therapeutics. Cancer stem cells (CSCs) gained fast attention as a minor population of highly malignant cells within liquid and solid tumors that are responsible for tumor onset, self-renewal, resistance to radio- and chemotherapies, and evasion of immune surveillance accelerating recurrence and metastasis. Recent progress in the identification of their phenotypic and molecular characteristics and interactions with the tumor microenvironment provides great potential for the development of CSC-based targeted therapies and radical improvement in metastasis prevention and cancer patient prognosis. Here, we report on newly uncovered signaling mechanisms controlling CSC's aggressiveness and treatment resistance, and CSC-specific agents and molecular therapeutics, some of which are currently under investigation in clinical trials, gearing towards decisive functional CSC intrinsic or surface markers. One special research focus rests upon subverted regulatory pathways such as insulin-like growth factor 1 receptor signaling and its interactors in metastasis-initiating cell populations directly related to the gain of stem cell- and EMT-associated properties, as well as key components of the E2F transcription factor network regulating metastatic progression, microenvironmental changes, and chemoresistance. In addition, the study provides insight into systems biology tools to establish complex molecular relationships behind the emergence of aggressive phenotypes from high-throughput data that rely on network-based analysis and their use to investigate immune escape mechanisms or predict clinical outcome-relevant CSC receptor signaling signatures. We further propose that customized vector technologies could drastically enhance systemic drug delivery to target sites, and summarize recent progress and remaining challenges. This review integrates available knowledge on CSC biology, computational modeling approaches, molecular targeting strategies, and delivery techniques to envision future clinical therapies designed to conquer metastasis-initiating cells.

The PLGF/c-MYC/miR-19a axis promotes metastasis and stemness in gallbladder cancer

Gallbladder cancer (GBC) is the most common malignant tumor of the biliary tract system. Epithelial-mesenchymal transition (EMT) plays a vital role in the process of tumor metastasis. Mesenchymal-like cells can serve as a source of cancer stem cells, which can confer the EMT phenotype. Placental growth factor (PLGF) belongs to the vascular endothelial growth factor family and plays a vital role in cancer. However, the underlying molecular mechanisms about the influence of PLGF on EMT in GBC remain unknown. Here we show that PLGF expression levels were higher in GBC tissues than in normal adjacent tissues and were associated with poor prognosis in GBC patients. Exogenous PLGF enhanced the migration, invasion, and tumorsphere formation of GBC cells. Conversely, knockdown of PLGF decreased the aggressive phenotype of GBC cells. Mechanistically, exogenous PLGF upregulated microRNA-19a (miR-19a) expression through the activation of c-MYC. Moreover, Spearman's correlation analysis showed a positive pairwise correlation among PLGF, c-MYC, and miR-19a expression in GBC tissues. Taken together, these results suggest that PLGF promotes EMT and tumorsphere formation through inducing miR-19a expression by upregulating c-MYC. Thus, PLGF could be a promising molecular therapeutic target for GBC.

Overexpressing TPTE2 (TPIP), a homolog of the human tumor suppressor gene PTEN, rescues the abnormal phenotype of the PTEN-/- mutant

One possible approach to normalize mutant cells that are metastatic and tumorigenic, is to upregulate a functionally similar homolog of the mutated gene. Here we have explored this hypothesis by generating an overexpressor of TPTE2 (TPIP), a homolog of PTEN, in PTEN-/- mutants, the latter generated by targeted mutagenesis of a human epithelial cell line. Overexpression of TPTE2 normalized phenotypic changes associated with the PTEN mutation. The PTEN-/- -associated changes rescued by overexpressing TPTE2 included 1) accelerated wound healing in the presence or absence of added growth factors (GFs), 2) increased division rates on a 2D substrate in the presence of GFs, 3) adhesion and viability on a 2D substrate in the absence of GFs, 4) viability in a 3D Matrigel model in the absence of GFs and substrate adhesion 5) loss of apoptosis-associated annexin V cell surface binding sites. The results justify further exploration into the possibility that upregulating TPTE2 by a drug may reverse metastatic and tumorigenic phenotypes mediated in part by a mutation in PTEN. This strategy may also be applicable to other tumorigenic mutations in which a homolog to the mutated gene is present and can substitute functionally.

Esculetin Inhibits the Survival of Human Prostate Cancer Cells by Inducing Apoptosis and Arresting the Cell Cycle

Background

Prostate cancer (PCa) is one of the most important causes of death in men and thus new therapeutic approaches are needed. In this study, antiproliferative and anti-migration properties of a coumarin derivative esculetin were evaluated.

Methods

Human PCa cell lines PC3, DU145, and LNCaP were treated with various concentrations of esculetin for 24 to 72 hours, and cell viability was determined by the MTT test. Cell cycle and apoptosis were analyzed by using cell-based cytometer. Gene expression levels were assessed by reverse transcription and quantitative real-time PCR, cell migration was determined by the wound healing assay. The protein expression was measured by Western blotting.

Results

Esculetin inhibited cell proliferation in a dose- and time-dependent manner. Cell migration was inhibited by esculetin treatment. Administration of esculetin significantly reduced the cells survival, induced apoptosis and caused the G1 phase cell cycle arrest shown by image-based cytometer. The induced expression of cytochrome c, p53, p21 and p27, and down-regulated CDK2 and CDK4 may be the underlying molecular mechanisms of esculetin effect. Esculetin suppressed phosphorylation of Akt and enhanced protein expression of tumor-suppressor phosphatase and tensin homologue.

Conclusions

Our findings showed that the coumarin derivative esculetin could be used in the management of PCa. However, further in vivo research is needed.

Dual inhibition of PI3K/mTOR signaling in chemoresistant AML primary cells

A main cause of treatment failure for AML patients is resistance to chemotherapy. Survival of AML cells may depend on mechanisms that elude conventional drugs action and/or on the presence of leukemia initiating cells at diagnosis, and their persistence after therapy. MDR1 gene is an ATP-dependent drug efflux pump known to be a risk factor for the emergence of resistance, when combined to unstable cytogenetic profile of AML patients. In the present study, we analyzed the sensitivity to conventional chemotherapeutic drugs of 26 samples of primary blasts collected from AML patients at diagnosis. Detection of cell viability and apoptosis allowed to identify two group of samples, one resistant and one sensitive to in vitro treatment. The cells were then analyzed for the presence and the activity of P-glycoprotein. A comparative analysis showed that resistant samples exhibited a high level of MDR1 mRNA as well as of P-glycoprotein content and activity. Moreover, they also displayed high PI3K signaling. Therefore, we checked whether the association with signaling inhibitors might resensitize resistant samples to chemo-drugs. The combination showed a very potent cytotoxic effect, possibly through down modulation of MDR1, which was maintained also when primary blasts were co-cultured with human stromal cells. Remarkably, dual PI3K/mTOR inactivation was cytotoxic also to leukemia initiating cells. All together, our findings indicate that signaling activation profiling associated to gene expression can be very useful to stratify patients and improve therapy.

Bone marrow mesenchymal stem cell-derived exosomal miR-21 protects C-kit+ cardiac stem cells from oxidative injury through the PTEN/PI3K/Akt axis

Stem cell (SC) therapy for ischemic cardiomyopathy is hampered by poor survival of the implanted cells. Recently, SC-derived exosomes have been shown to facilitate cell proliferation and survival by transporting various proteins and non-coding RNAs (such as microRNAs and lncRNAs). In this study, miR-21 was highly enriched in exosomes derived from bone marrow mesenchymal stem cells (MSCs). Interestingly, exosomes collected from hydrogen peroxide (H₂O₂)-treated MSCs (H-Exo) contained higher levels of miR-21 than exosomes released from MSCs under normal conditions (N-Exo). The pre-treatment of C-kit⁺ cardiac stem cells (CSCs) with H-Exos resulted in significantly increased levels of miR-21 and phosphor-Akt (pAkt) and decreased levels of PTEN, which is a known target of miR-21. AnnexinV-FITC/PI analysis further demonstrated that the degree of oxidative stress-induced apoptosis was markedly lower in H-Exo-treated C-kit⁺ CSCs than that in N-Exo-treated cells. These protective effects could be blocked by both a miR-21 inhibitor and the PI3K/Akt inhibitor LY294002. Therefore, exosomal miR-21 derived from H₂O₂-treated MSCs could be transported to C-kit⁺ cardiac stem cells to functionally inhibit PTEN expression, thereby activating PI3K/AKT signaling and leading to protection against oxidative stress-triggered cell death. Thus, exosomes derived from MSCs could be used as a new therapeutic vehicle to facilitate C-kit⁺ CSC therapies in the ischemic myocardium.

PTEN Inhibition in Human Disease Therapy

The tumor suppressor PTEN is a major homeostatic regulator, by virtue of its lipid phosphatase activity against phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P3], which downregulates the PI3K/AKT/mTOR prosurvival signaling, as well as by its protein phosphatase activity towards specific protein targets. PTEN catalytic activity is crucial to control cell growth under physiologic and pathologic situations, and it impacts not only in preventing tumor cell survival and proliferation, but also in restraining several cellular regeneration processes, such as those associated with nerve injury recovery, cardiac ischemia, or wound healing. In these conditions, inhibition of PTEN catalysis is being explored as a potentially beneficial therapeutic intervention. Here, an overview of human diseases and conditions in which PTEN inhibition could be beneficial is presented, together with an update on the current status of specific small molecule inhibitors of PTEN enzymatic activity, their use in experimental models, and their limitations as research or therapeutic drugs.

miR-106b-5p promotes stem cell-like properties of hepatocellular carcinoma cells by targeting PTEN via PI3K/Akt pathway

Background

The miRNA miR-106b-5p has been previously reported to be increased in hepatocellular carcinoma (HCC) tissues compared to cirrhotic tissues. The purpose of this study was to detect its expression in HCC cell lines with distinct metastatic potentials and to explore the molecular mechanisms underlying HCC stemness and migration.

Methods

miR-106b-5p expression was studied in HCC tissues and cell lines. In vitro cancer stem cell (CSC)-like properties, cell migration and invasion were compared between HCC cell lines with upregulation or downregulation of miR-106b-5p. In vivo tail vein injection models were established to evaluate the role of miR-106b-5p in lung metastasis. Bioinformatics programs, luciferase reporter assay and rescue experiments were used to validate the downstream targets of miR-106b-5p. The relationship between the expression of the targeted gene and clinicopathological parameters was also analyzed.

Results

miR-106b-5p expression was higher in HCC tissues and cell lines than that in non-tumor tissues and hepatocyte Chang liver, respectively. Upregulation of miR-106b-5p exhibited a promoting role in CSC properties, cell migration and activation of phosphatidylinositol-3 kinase (PI3K)/Akt signaling in vitro, as well as in lung metastasis in vivo. However, downregulation of miR-106b-5p exhibited the opposite effect. Furthermore, PTEN was verified as a direct target of miR-106b-5p. Upon clinicopathological analysis, lower level of PTEN was significantly associated with more aggressive characteristics. Patients with high PTEN expression had longer overall survival and disease-free survival.

Conclusion

miR-106b-5p promotes HCC stemness maintenance and metastasis by targeting PTEN via PI3K/Akt pathway. Inhibition of miR-106b-5p might be effective therapeutic strategies to treat advanced HCC.

mTOR Cross-Talk in Cancer and Potential for Combination Therapy

The mammalian Target of Rapamycin (mTOR) pathway plays an essential role in sensing and integrating a variety of exogenous cues to regulate cellular growth and metabolism, in both physiological and pathological conditions. mTOR functions through two functionally and structurally distinct multi-component complexes, mTORC1 and mTORC2, which interact with each other and with several elements of other signaling pathways. In the past few years, many new insights into mTOR function and regulation have been gained and extensive genetic and pharmacological studies in mice have enhanced our understanding of how mTOR dysfunction contributes to several diseases, including cancer. Single-agent mTOR targeting, mostly using rapalogs, has so far met limited clinical success; however, due to the extensive cross-talk between mTOR and other pathways, combined approaches are the most promising avenues to improve clinical efficacy of available therapeutics and overcome drug resistance. This review provides a brief and up-to-date narrative on the regulation of mTOR function, the relative contributions of mTORC1 and mTORC2 complexes to cancer development and progression, and prospects for mTOR inhibition as a therapeutic strategy.

EYA2 promotes lung cancer cell proliferation by downregulating the expression of PTEN

Lung cancer is the leading cause of cancer-related death worldwide. Despite advances have been made in diagnosis and therapeutic strategies, the prognosis of lung cancer is still very poor. Eyes absent transcriptional cofactor EYA2 has been shown to promote lung cancer cell growth, however, the underlying molecular mechanism is still not fully understood. In the present study, we found that EYA2 was up-regulated in lung cancer, and EYA2 led to increased cell proliferation by inhibiting Phosphatase and tensin homologue (PTEN) expression via modulation of miR-93. Additionally, survival analysis showed that lung cancer patients with higher EYA2 expression predicted a worse prognosis. Therefore, these findings demonstrate that EYA2 may play an important role in lung cancer occurrence and progression. Targeting EYA2 may provide a feasible approach in developing novel anticancer therapeutics.

PTEN Is Fundamental for Elimination of Leukemia Stem Cells Mediated by GSK126 Targeting EZH2 in Chronic Myelogenous Leukemia

Purpose: Leukemia stem cells (LSCs) are an important source of tyrosine kinase inhibitor resistance and disease relapse in patients with chronic myelogenous leukemia (CML). Targeting LSCs may be an attractive strategy to override this thorny problem. Given that EZH2 was overexpressed in primary CML CD34⁺ cells, our purpose in this study was to evaluate the effects of targeting EZH2 on CML LSCs and clarify its underlying mechanism.Experimental Design: Human primary CML CD34⁺ cells and retrovirally BCR-ABL-driven CML mouse models were employed to evaluate the effects of suppression of EZH2 by GSK126- or EZH2-specific shRNA in vitro and in vivo Recruitment of EZH2 and H3K27me3 on the promoter of tumor-suppressor gene PTEN in CML cells was measured by chromatin immunoprecipitation assay.Results: Our results showed that pharmacologic inhibition of EZH2 by GSK126 not only elicited apoptosis and restricted cell growth in CML bulk leukemia cells, but also decreased LSCs in CML CD34⁺ cells while sparing those from normal bone marrow CD34⁺ cells. Suppression of EZH2 by GSK126 or specific shRNA prolonged survival of CML mice and reduced the number of LSCs in mice. EZH2 knockdown resulted in elevation of PTEN and led to impaired recruitment of EZH2 and H3K27me3 on the promoter of PTEN gene. The effect of EZH2 knockdown in the CML mice was at least partially reversed by PTEN knockdown.Conclusions: These findings improve the understanding of the epigenetic regulation of stemness in CML LSCs and warrant clinical trial of GSK126 in refractory patients with CML. Clin Cancer Res; 24(1); 145-57. ©2017 AACR.

MicroRNA-142-5p induces cancer stem cell-like properties of cutaneous squamous cell carcinoma via inhibiting PTEN

Cutaneous squamous cell carcinoma (cSCC) is a malignancy of keratinocyte-derived skin tumor, which is regarded as the second most common skin cancer worldwide. Accumulating evidence has established that microRNAs (miRNAs) can play a critical role in tumor initiation, progression, and metastasis including cSCC. Abnormal expression of hsa-miR-142-5p has been elaborated in various tumors. Nevertheless, its expression and function in the development of cSCC remain unclear. In our study, we found that the expression of hsa-miR-142-5p in cSCC cells were greatly overexpressed compared to human benign epidermal keratinocyte cells. Moreover, inhibited hsa-miR-142-5p can repress cSCC cell growth and induce apoptosis while upregulated hsa-miR-142-5p exhibited a reverse phenomenon. Recently, cancer stem cells (CSCs) which possess the ability of self-renewal and proliferation and are able to produce cancer cells have been widely reported. However, the correlation between hsa-miR-142-5p and CSCs in cSCC is still unknown. Interestingly, we observed that overexpressing hsa-miR-142-5p can induce CSC-like properties in cSCC via activating Wnt signaling. In addition, the luciferase reporter assay data and bioinformatics analysis demonstrated that hsa-miR-142-5p can target the 3'UTR of PTEN mRNA. Taken these together, we draw a conclusion that hsa-miR-142-5p can trigger cancer stem cell-like properties of cSCC through inhibition of PTEN. Our findings may provide hsa-miR-142-5p as a new therapeutic target for cSCC.

Advances in cancer stem cell targeting: How to strike the evil at its root

Cancer progression to metastatic stages is still unmanageable and the promise of effective anti-metastatic therapy remains largely unmet, emphasizing the need to develop novel therapeutics. The special focus here is on cancer stem cells (CSC) as the seed of tumor initiation, epithelial-mesenchymal transition, chemoresistance and, as a consequence, drivers of metastatic dissemination. We report on targeted therapies gearing towards the CSC's internal and membrane-anchored markers using agents such as antibody derivatives, nucleic therapeutics, small molecules and genetic payloads. Another emphasis lies on novel proceedings envisaged to deliver current and prospective therapies to the target sites using newest viral and non-viral vector technologies. In this review, we summarize recent progress and remaining challenges in therapeutic strategies to combat CSC.

The prognostic value and potential drug target of phosphatase and tensin homolog in breast cancer patients: A meta-analysis

BACKGROUND

The prognostic significance of phosphatase and tensin homolog (PTEN) in patients with breast cancer (BC) remains controversial. The aims of our meta-analysis are to evaluate its association with clinicopathological characteristics and prognostic value in patients with breast cancer.

METHODS

PubMed, EMBASE, Web of Science, and China National Knowledge Infrastructure (CNKI) were systematically searched up to December 2016. The meta-analysis was performed using hazard ratio (HR), odds ratio (OR), and 95% confidence intervals (CI) as effect measures. A fixed or random effect model was used depending on the heterogeneity analysis. Statistical analysis was performed using Review manager software version 5.3.

RESULTS

Seventeen studies including 4343 patients with breast cancer were analyzed. The meta-analysis indicated that breast cancers with PTEN loss were significantly associated with the tumor size ≥2 cm group (ORFEM = 1.68, 95%CIFEM [1.34, 2.10]), negative expression of estrogen receptor (ORREM = 1.95, 95%CIREM [1.09, 3.49]), negative expression of progesterone receptor (ORFEM = 1.72, 95%CIFEM [1.43, 2.08]), the advanced stage (ORREM = 1.94, 95%CIREM [1.35, 2.80]), positive axillary lymph node metastasis (ORREM = 1.80, 95%CIREM [1.30, 2.50]), and the local recurrence (ORFEM = 1.70, 95%CIFEM [1.26, 2.28]). None of other clinicopathological parameters such as the HER2 status and distant metastasis were associated with PTEN loss. The decreased PTEN expression was significantly correlated with the overall survival (OS) of patients (HRREM = 1.83, 95%CIREM [1.32, 2.53]) and the disease-free survival (DFS) of patients (HRREM = 2.43, 95%CIREM [1.31, 4.53]).

CONCLUSION

Our meta-analysis demonstrates that PTEN loss is of particular importance for predicting breast cancer aggressiveness and poor prognosis. PTEN is a potential drug target for the development of individualized treatment in BC patients.

Radiation-resistant cancer stem-like cell properties are regulated by PTEN through the activity of nuclear β-catenin in nasopharyngeal carcinoma

Radiotherapy is the primary and most important treatment for nasopharyngeal carcinoma (NPC). Cancer stem-like cells (CSCs) have been shown to be resistant to radiation. The phosphatase and tensin homolog deleted on chromosome 10 (PTEN) tumor suppressor gene has been suggested to play a role in stem cell self-renewal. In the present study, we sorted PTEN−/+ cells using a flow cytometer. The clone formation assay showed that PTEN− cells were more radioresistant than PTEN+ NPC cells. We found that PTEN− cells demonstrated a significant increase in tumorsphere formation and CSCs markers compared with PTEN+ cells. Silencing the expression of PTEN with siRNA resulted in increased expression of p-AKT, active β-catenin and Nanog. siPTEN cells irradiated showed more radioresistant and DNA damage than parental cells. We also confirmed that down-regulation of β-catenin expression with shRNA resulted in a reduced percentage of side population cells and expression of Nanog. shβ-catenin cells significantly decreased survivin expression at 4 Gy irradiation in PTEN− cells compared with PTEN+ cells. In siPTEN cells, β-catenin staining shifted from the cytoplasmic membrane to the nucleus. Furthermore, immunofluorescence showed that following irradiation of PTEN− cells, at 4 Gy, active β-catenin was mainly found in the nucleus. Immunohistochemistry analysis also demonstrated that the PTEN−/p-AKT+/β-catenin+/Nanog+ axis may indicate poor prognosis and radioresistance in clinical NPC specimens. Thus, our findings strongly suggest that PTEN− cells have CSCs properties that are resistant to radiation in NPC. PTEN exerts these effects through the downstream effector PI3K/AKT/β-catenin/Nanog axis which depends on nuclear β-catenin accumulation.

Phosphatases and solid tumors: focus on glioblastoma initiation, progression and recurrences

Phosphatases and cancer have been related for many years now, as these enzymes regulate key cellular functions, including cell survival, migration, differentiation and proliferation. Dysfunctions or mutations affecting these enzymes have been demonstrated to be key factors for oncogenesis. The aim of this review is to shed light on the role of four different phosphatases (PTEN, PP2A, CDC25 and DUSP1) in five different solid tumors (breast cancer, lung cancer, pancreatic cancer, prostate cancer and ovarian cancer), in order to better understand the most frequent and aggressive primary cancer of the central nervous system, glioblastoma.

GSK-3 as a novel prognostic indicator in leukemia

While leukemias represent a diverse set of diseases with malignant cells derived from myeloid or lymphoid origin, a common feature is the dysregulation of signal transduction pathways that influence leukemogeneisis, promote drug resistance, and favor leukemia stem cells. Mutations in PI3K, PTEN, RAS, or other upstream regulators can activate the AKT kinase which has central roles in supporting cell proliferation and survival. A major target of AKT is Glycogen Synthase Kinase 3 (GSK3). GSK3 has two isoforms (alpha and beta) that were studied as regulators of metabolism but emerged as central players in cancer in the early 1990s. GSK3 is unique in that the isoforms are constitutively active. Active GSK3 promotes destruction of oncogenic proteins such as beta Catenin, c-MYC, and MCL-1 and thus has tumor suppressor properties. In AML, inactivation of GSK3 is associated with poor overall survival. Interestingly in some leukemias GSK3 targets a tumor suppressor and thus the kinases can act as tumor promoters in those instances. An example is GSK3 targeting p27Kip1 in AML with MLL translocation. This review will cover the role of GSK3 in various leukemias both as tumor suppressor and tumor promoter. We will also briefly cover current state of GSK3 inhibitors for leukemia therapy.

VSV based virotherapy in ovarian cancer: the past, the present and …future?

The standard approach to treating patients with advanced epithelial ovarian cancer (EOC) after primary debulking surgery remains taxane and platinum-based chemotherapy. Despite treatment with this strategy, the vast majority of patients relapse and develop drug-resistant metastatic disease that may be driven by cancer stem cells (CSCs) or cancer initiating cells (CICs). Oncolytic viruses circumvent typical drug-resistance mechanisms, therefore they may provide a safe and effective alternative treatment for chemotherapy-resistant CSCs/CICs. Among oncolytic viruses vesicular stomatitis virus (VSV) has demonstrated oncolysis and preferential replication in cancer cells. In this review, we summarize the recent findings regarding existing knowledge on biology of the ovarian cancer and the role of ovarian CSCs (OCSCs) in tumor dissemination and chemoresistance. In addition we also present an overview of recent advances in ovarian cancer therapies with oncolytic viruses (OV). We focus particularly on key genetic or immune response pathways involved in tumorigenesis in ovarian cancer which facilitate oncolytic activity of vesicular stomatitis virus (VSV). We highlight the prospects of targeting OCSCs with VSV. The importance of testing an emerging ovarian cancer animal models and ovarian cancer cell culture conditions influencing oncolytic efficacy of VSV is also addressed.

Unravelling the complexity of signalling networks in cancer: A review of the increasing role for computational modelling

Cancer induction is a highly complex process involving hundreds of different inducers but whose eventual outcome is the same. Clearly, it is essential to understand how signalling pathways and networks generated by these inducers interact to regulate cell behaviour and create the cancer phenotype. While enormous strides have been made in identifying key networking profiles, the amount of data generated far exceeds our ability to understand how it all "fits together". The number of potential interactions is astronomically large and requires novel approaches and extreme computation methods to dissect them out. However, such methodologies have high intrinsic mathematical and conceptual content which is difficult to follow. This review explains how computation modelling is progressively finding solutions and also revealing unexpected and unpredictable nano-scale molecular behaviours extremely relevant to how signalling and networking are coherently integrated. It is divided into linked sections illustrated by numerous figures from the literature describing different approaches and offering visual portrayals of networking and major conceptual advances in the field. First, the problem of signalling complexity and data collection is illustrated for only a small selection of known oncogenes. Next, new concepts from biophysics, molecular behaviours, kinetics, organisation at the nano level and predictive models are presented. These areas include: visual representations of networking, Energy Landscapes and energy transfer/dissemination (entropy); diffusion, percolation; molecular crowding; protein allostery; quinary structure and fractal distributions; energy management, metabolism and re-examination of the Warburg effect. The importance of unravelling complex network interactions is then illustrated for some widely-used drugs in cancer therapy whose interactions are very extensive. Finally, use of computational modelling to develop micro- and nano- functional models ("bottom-up" research) is highlighted. The review concludes that computational modelling is an essential part of cancer research and is vital to understanding network formation and molecular behaviours that are associated with it. Its role is increasingly essential because it is unravelling the huge complexity of cancer induction otherwise unattainable by any other approach.