PTEN modulates cell cycle progression and cell survival by regulating phosphatidylinositol 3,4,5,-trisphosphate and Akt/protein kinase B signaling pathway

Phosphatidylinositol-3 kinase signaling controls survival and stemness of hematopoietic stem and progenitor cells

Hematopoietic stem and progenitor cells (HSPCs) are multipotent cells giving rise to all blood lineages during life. HSPCs emerge from the ventral wall of the dorsal aorta (VDA) during a specific timespan in embryonic development through endothelial hematopoietic transition (EHT). We investigated the ontogeny of HSPCs in mutant zebrafish embryos lacking functional pten, an important tumor suppressor with a central role in cell signaling. Through in vivo live imaging, we discovered that in pten mutant embryos a proportion of the HSPCs died upon emergence from the VDA, an effect rescued by inhibition of phosphatidylinositol-3 kinase (PI3K). Surprisingly, inhibition of PI3K in wild-type embryos also induced HSPC death. Surviving HSPCs colonized the caudal hematopoietic tissue (CHT) normally and committed to all blood lineages. Single-cell RNA sequencing indicated that inhibition of PI3K enhanced survival of multipotent progenitors, whereas the number of HSPCs with more stem-like properties was reduced. At the end of the definitive wave, loss of Pten caused a shift to more restricted progenitors at the expense of HSPCs. We conclude that PI3K signaling tightly controls HSPCs survival and both up- and downregulation of PI3K signaling reduces stemness of HSPCs.

Sensitive detection of Cre-mediated recombination using droplet digital PCR reveals Tg(BGLAP-Cre) and Tg(DMP1-Cre) are active in multiple non-skeletal tissues

In humans, somatic activating mutations in PIK3CA are associated with skeletal overgrowth. In order to determine if activated PI3K signaling in bone cells causes overgrowth, we used Tg(BGLAP-Cre) and Tg(DMP1-Cre) mouse strains to somatically activate a disease-causing conditional Pik3ca allele (Pik3ca^H1047R) in osteoblasts and osteocytes. We observed Tg(BGLAP-Cre);Pik3ca^H1047R/+ offspring were born at the expected Mendelian frequency. However, these mice developed cutaneous lymphatic malformations and died before 7 weeks of age. In contrast, Tg(DMP1-Cre);Pik3ca^H1047R/+ offspring survived and had no cutaneous lymphatic malformations. Assuming that Cre-activity outside of the skeletal system accounted for the difference in phenotype between Tg(BGLAP-Cre);Pik3ca^H1047R/+ and Tg(DMP1-Cre);Pik3ca^H1047R/+ mice, we developed sensitive and specific droplet digital PCR (ddPCR) assays to search for and quantify rates of Tg(BGLAP-Cre)- and Tg(DMP1-Cre)-mediated recombination in non-skeletal tissues. We observed Tg(BGLAP-Cre)-mediated recombination in several tissues including skin, muscle, artery, and brain; two CNS locations, hippocampus and cerebellum, exhibited Cre-mediated recombination in >5% of cells. Tg(DMP1-Cre)-mediated recombination was also observed in muscle, artery, and brain. Although we cannot preclude that differences in phenotype between mice with Tg(BGLAP-Cre)- and Tg(DMP1-Cre)-mediated PIK3CA activation are due to Cre-recombination being induced at different stages of osteoblast differentiation, differences in recombination at non-skeletal sites are the more likely explanation. Since unanticipated sites of recombination can affect the interpretation of data from experiments involving conditional alleles, we recommend ddPCR as a good first step for assessing efficiency, leakiness, and off-targeting in experiments that employ Cre-mediated or Flp-mediated recombination.

ATM Kinase Inhibition Preferentially Sensitises PTEN-Deficient Prostate Tumour Cells to Ionising Radiation

Simple Summary

Prostate cancer is the most frequently diagnosed cancer in men. Despite the importance of radical radiotherapy for the management of this disease, recurrence remains a challenge. PTEN is a tumour suppressor that is frequently inactivated in advanced prostate cancer and has been associated with relapse following radiotherapy. The present study shows that the role of PTEN in response to ionizing radiation is complex. Furthermore, it demonstrates that in the absence of PTEN, an increased response to combined treatment using radiotherapy and the ATM inhibitor KU-60019 can be observed. Our findings provide a strong rationale for evaluating loss of PTEN in prostate cancer as a therapeutic target for ATM inhibitor in combination with radiotherapy in the clinical setting.

Abstract

Radical radiotherapy, often in combination with hormone ablation, is a safe and effective treatment option for localised or locally-advanced prostate cancer. However, up to 30% of patients with locally advanced PCa will go on to develop biochemical failure, within 5 years, following initial radiotherapy. Improving radiotherapy response is clinically important since patients exhibiting biochemical failure develop castrate-resistant metastatic disease for which there is no curative therapy and median survival is 8–18 months. The aim of this research was to determine if loss of PTEN (highly prevalent in advanced prostate cancer) is a novel therapeutic target in the treatment of advanced prostate cancer. Previous work has demonstrated PTEN-deficient cells are sensitised to inhibitors of ATM, a key regulator in the response to DSBs. Here, we have shown the role of PTEN in cellular response to IR was both complex and context-dependent. Secondly, we have confirmed ATM inhibition in PTEN-depleted cell models, enhances ionising radiation-induced cell killing with minimal toxicity to normal prostate RWPE-1 cells. Furthermore, combined treatment significantly inhibited PTEN-deficient tumour growth compared to PTEN-expressing counterparts, with minimal toxicity observed. We have further shown PTEN loss is accompanied by increased endogenous levels of ROS and DNA damage. Taken together, these findings provide pre-clinical data for future clinical evaluation of ATM inhibitors as a neoadjuvant/adjuvant in combination with radiation therapy in prostate cancer patients harbouring PTEN mutations.

miR-301a-PTEN-AKT Signaling Induces Cardiomyocyte Proliferation and Promotes Cardiac Repair Post-MI

Adult hearts are hard to recover after cardiac injury due to the limited proliferative ability of cardiomyocytes. Emerging evidence indicates the induction of cell cycle reentry of cardiomyocytes by special treatment or stimulation, which offers adult heart regenerative potential. Herein, a microRNA (miRNA) screening in cardiomyocytes identified miR-301a enriched specially in the neonatal cardiomyocytes from rats and mice. Overexpression of miR-301a in primary neonatal cardiomyocytes and H9C2 cells induced G1/S transition of the cell cycle, promoted cellular proliferation, and protected cardiomyocytes against hypoxia-induced apoptosis. Adeno-associated virus (AAV)9-mediated cardiac delivery of miR-301a to the mice model with myocardial infarction (MI) dramatically promoted cardiac repair post-MI in vivo. Phosphatase and tensin homolog (PTEN)/phosphatidylinositol 3-kinase (PI3K)/AKT signaling pathway was confirmed to mediate miR-301a-induced cell proliferation in cardiomyocytes. Loss of function of PTEN mimicked the miR-301a-induced phenotype, while gain of function of PTEN attenuated the miR-301a-induced cell proliferation in cardiomyocytes. Application of RG7440, a small molecule inhibitor of AKT, blocked the function of miR-301a in cardiomyocytes. The current study revealed a miRNA signaling in inducing the cell cycle reentry of cardiomyocytes in the injured heart, and it demonstrated the miR-301a/PTEN/AKT signaling as a potential therapeutic target to reconstitute lost cardiomyocytes in mammals.

The Role of Autophagy in Gastric Cancer Chemoresistance: Friend or Foe?

Gastric cancer is the third most common cause of cancer-related death worldwide. Drug resistance is the main inevitable and vital factor leading to a low 5-year survival rate for patients with gastric cancer. Autophagy, as a highly conserved homeostatic pathway, is mainly regulated by different proteins and non-coding RNAs (ncRNAs) and plays dual roles in drug resistance of gastric cancer. Thus, targeting key regulatory nodes in the process of autophagy by small molecule inhibitors or activators has become one of the most promising strategies for the treatment of gastric cancer in recent years. In this review, we provide a systematic summary focusing on the relationship between autophagy and chemotherapy resistance in gastric cancer. We comprehensively discuss the roles and molecular mechanisms of multiple proteins and the emerging ncRNAs including miRNAs and lncRNAs in the regulation of autophagy pathways and gastric cancer chemoresistance. We also summarize the regulatory effects of autophagy inhibitor and activators on gastric cancer chemoresistance. Understanding the vital roles of autophagy in gastric cancer chemoresistance will provide novel opportunities to develop promising therapeutic strategies for gastric cancer.

miR-29 Sustains B Cell Survival and Controls Terminal Differentiation via Regulation of PI3K Signaling

The phosphatidylinositol 3-kinase (PI3K) signaling cascade downstream of the B cell receptor (BCR) signalosome is essential for B cell maturation. Proper signaling strength is maintained through the PI3K negative regulator phosphatase and tensin homolog (PTEN). Although a role for microRNA (miRNA)-dependent control of the PTEN-PI3K axis has been described, the contribution of individual miRNAs to the regulation of this crucial signaling modality in mature B lymphocytes remains to be elucidated. Our analyses reveal that ablation of miR-29 specifically in B lymphocytes results in an increase in PTEN expression and dampening of the PI3K pathway in mature B cells. This dysregulation has a profound impact on the survival of B lymphocytes and results in increased class switch recombination and decreased plasma cell differentiation. Furthermore, we demonstrate that ablation of one copy of Pten is sufficient to ameliorate the phenotypes associated with miR-29 loss. Our data suggest a critical role for the miR-29-PTEN-PI3K regulatory axis in mature B lymphocytes.

Molecular dynamic study on PTEN frameshift mutations in breast cancer provide c2 domain as a potential biomarker

PTEN is a tumour suppressor gene known for regulating apoptosis, cell growth, and many other pathways. It is one of the most frequently mutated genes comprising the phosphatase domain (PD) and C terminal domain (C2). Direct therapeutic methods are not applicable for targeting PTEN because once gets mutated, it needs restoration. For mutant detection and restoration using PTEN mRNA there is a need to explore various mutations taking place in PTEN, identify their particular domains, and study their interactions within the cellular system. Here, we have tried to highlight a few such regions in the mutated PTEN of breast cancer patients. In this study, we have selected the top-most-occurring PTEN mutation in breast cancer and compared them to determine the specific properties of each mutation and its effect on functionality. Molecular dynamic simulation for 50 ns was performed on five structures to compare the structural behaviour of mutated PTEN in the system. Our finding suggests that frameshift mutations are more damaging and affect the c2 domain. Frameshift mutant fs_ACTT is the highest occurring as well as the most damaging mutation in all the compared structures. Docking study shows that substitution mutations D92H and R130Q causes loss of binding ability towards PIP2 in normal PTEN, interfering the dephosphorylation process. Overall, the C2 domain is more frequently mutated, and the amino acid residues in the C2 domain show more fluctuations compared to the other regions. Our study can provide the basis for selecting frequently mutated C2 domain as a potential therapeutic marker.Communicated by Ramaswamy H. Sarma.

YTHDC1 mitigates ischemic stroke by promoting Akt phosphorylation through destabilizing PTEN mRNA

YTH Domain Containing 1 (YTHDC1) is one of the m⁶A readers that is essential for oocyte development and tumor progression. The role of YTHDC1 in neuronal survival and ischemic stroke is unknown. Here, we found that YTHDC1 was unregulated in the early phase of ischemic stroke. Knockdown of YTHDC1 exacerbated ischemic brain injury and overexpression of YTHDC1 protected rats against brain injury. Mechanistically, YTHDC1 promoted PTEN mRNA degradation to increase Akt phosphorylation, thus facilitating neuronal survival in particular after ischemia. These data identify YTHDC1 as a novel regulator of neuronal survival and modulating m⁶A reader YTHDC1 may provide a potential therapeutic target for ischemic stroke.

RAD51-Mediated DNA Homologous Recombination Is Independent of PTEN Mutational Status

Simple Summary

PTEN is an important tumor suppressor that is frequently mutated in malignancy. PTEN mutational loss has been associated with reduced RAD51 expression and homologous recombination deficiency (HRD), however; recent studies have failed to recapitulate these findings. Here, we show that RAD51 expression, foci formation and homologous recombination repair activity are unaltered in normal and tumorigenic PTEN-deficient cells and patient samples. Furthermore, we show that PTEN-deficient tumor cell lines do not synergize with the clinical PARP inhibitor olaparib, underscoring a need to discontinue its use in treating patients with PTEN-deficient tumors that do not otherwise exhibit HRD.

Abstract

PTEN mutation occurs in a variety of aggressive cancers and is associated with poor patient outcomes. Recent studies have linked mutational loss of PTEN to reduced RAD51 expression and function, a key factor involved in the homologous recombination (HR) pathway. However, these studies remain controversial, as they fail to establish a definitive causal link to RAD51 expression that is PTEN-dependent, while other studies have not been able to recapitulate the relationship between the PTEN expression and the RAD51/HR function. Resolution of this apparent conundrum is essential due to the clinically-significant implication that PTEN-deficient tumors may be sensitive to poly (ADP-ribose) polymerase (PARP) inhibitors (PARPi) commonly used in the clinical management of BRCA-mutated and other HR-deficient (HRD) tumors. Methods: Primary Pten-deficient (and corresponding wild-type) mouse embryonic fibroblasts (MEFs) and astrocytes and PTEN-null human tumor cell lines and primary cells were assessed for RAD51 expression (via the Western blot analysis) and DNA damage repair analyses (via alkali comet and γH2AX foci assays). RAD51 foci analysis was used to measure HR-dependent DNA repair. Xrcc2-deficient MEFs served as an HR-deficient control, while the stable knockdown of RAD51 (shRAD51) served to control for the relative RAD51/HR-mediated repair and the phospho-53BP1 foci analysis served to confirm and measure non-homologous end joining (NHEJ) activity in PTEN-deficient and shRAD51-expressing (HRD) lines. Cell proliferation studies were used to measure any potential added sensitivity of PTEN-null cells to the clinically-relevant PARPi, olaparib. RAD51 levels and DNA damage response signaling were assessed in PTEN-mutant brain tumor initiating cells (BTICs) derived from primary and recurrent glioblastoma multiforme (GBM) patients, while expression of RAD51 and its paralogs were examined as a function of the PTEN status in the RNA expression datasets isolated from primary GBM tumor specimens and BTICs. Results: Pten knockout primary murine cells display unaltered RAD51 expression, endogenous and DNA strand break-induced RAD51 foci and robust DNA repair activity. Defective HR was only observed in the cells lacking Xrcc2. Likewise, human glioblastoma multiforme (GBM) cell lines with known PTEN deficiency (U87, PTEN-mutated; U251 and U373, PTEN-null) show apparent expression of RAD51 and display efficient DNA repair activity. Only GBM cells stably expressing shRNAs against RAD51 (shRAD51) display dysfunctional DNA repair activity and reduced proliferative capacity, which is exacerbated by PARPi treatment. Furthermore, GBM patient-derived BTICs displayed robust RAD51 expression and intact DNA damage response signaling in spite of PTEN-inactivating mutations. RNA expression analysis of primary GBM tissue specimens and BTICs demonstrate stable levels of RAD51 and its paralogs (RAD51B, RAD51C, RAD51D, XRCC2, XRCC3, and DMC1), regardless of the PTEN mutational status. Conclusions: Our findings demonstrate definitively that PTEN loss does not alter the RAD51 expression, its paralogs, or the HR activity. Furthermore, deficiency in PTEN alone is not sufficient to impart enhanced sensitivity to PARPi associated with HRD. This study is the first to unequivocally demonstrate that PTEN deficiency is not linked to the RAD51 expression or the HR activity amongst primary neural and non-neural Pten-null cells, PTEN-deficient tumor cell lines, and primary PTEN-mutant GBM patient-derived tissue specimens and BTICs.

Effects of rapamycin and AZD3463 combination on apoptosis, autophagy, and cell cycle for resistance control in breast cancer

Breast cancer is the most common cancer in women and the leading cause of cancer mortality in women over 40 it's the year. The existence of the PI3K/AKT/mTOR pathway aberrations in more than 70% of breast cancer has caused to become a therapeutic target. AZD3463 is an anti-cancer agent used as a potential inhibitor of ALK/IGF1R. It also induces apoptosis and autophagy of the PI3K/AKT/mTOR pathway in cancer cells. Although the mTOR signaling might be inhibited by rapamycin treatment, signals transmitted from the upstream pathway supports cell survival and proliferation. The WST-1 assay test was performed to evaluate the anti-proliferative effects of rapamycin and AZD3463. Besides, the effects of them on apoptosis, autophagy, cytostatic, and metabolism in MCF7 breast cancer cells were investigated. Also, changes in the expression of apoptotic regulatory genes, cell cycle, and metabolism in the PI3K/AKT/mTOR Pathway were determined by Quantitative RT-PCR. The results showed that rapamycin and AZD3463 treatments significantly reduced survival in MCF7 cells. Also, apoptosis, autophagy, and cell population in the G0/G1 stage in the MCF7 cell category in the treatment group showed an increase compared to the control group. The combination of rapamycin and AZD3463 (AZD-RAPA) was determined as an additive according to isobologram analysis. In the combination of rapamycin with AZD3463, the expression of CDKN1B, PTEN, FOXO3, and APC genes increases, and the expression of PRKCB and PIK3CG genes decreases. Our results showed that the use of AZD-RAPA reduced the resistance of cancer cells to treatment and it leads cancer cells to apoptosis.

Deletion of NKX3.1 via CRISPR/Cas9 Induces Prostatic Intraepithelial Neoplasia in C57BL/6 Mice

Several techniques have been employed for deletion of the NKX3.1 gene, resulting in developmental defects of the prostate, including alterations in ductal branching morphogenesis and prostatic secretions as well as epithelial hyperplasia and dysplasia. To investigate whether the CRISPR/Cas9-mediated technique can be applied to study prostate carcinogenesis through exon I deletion of NKX3.1 gene, alterations in the prostatic intraepithelial neoplasia (PIN) and their regulatory mechanism were observed in the prostate of NKX3.1 knockout (KO) mice produced by the CRISPR/Cas9-mediated NKX3.1 mutant gene, at the ages of 16 and 24 weeks. The weight of dorsal-lateral prostate (DLP) and anterior prostate (AP) were observed to be increased in only the 24 weeks KO mice, although morphogenesis was constant in all groups. Obvious PIN 1 and 2 lesions were frequently detected in prostate of the 24 weeks KO mice, as compared with the same age wild type (WT) mice. Ki67, a key indicator for PIN, was densely stained in the epithelium of prostate in the 24 weeks KO mice, while the expression of p53 protein was suppressed in the same group. Also, both the 16 and 24 weeks KO mice reveal inhibition of the PI3K/AKT/mTOR pathway in the prostate. However, prostate specific antigen (PSA) levels and Bax/Bcl-2 expressions were decreased in the prostate of 16 weeks KO mice, and were increased in only the 24 weeks KO mice. Taken together, the results of the present study provide additional evidence that CRISPR/Cas9-mediated exon 1 deletion of the NKX3.1 gene successfully induces PIN lesions, along with significant alterations of Ki67 expression, EGFR signaling pathway, and cancer-regulated proteins.

Approaches to Investigating the Protein Interactome of PTEN

The tumor suppressor phosphatase and tensin homologue (PTEN) is a redox-sensitive dual specificity phosphatase with an essential role in the negative regulation of the PI3K-AKT signaling pathway, affecting metabolic and cell survival processes. PTEN is commonly mutated in cancer, and dysregulation in the metabolism of PIP₃ is implicated in other diseases such as diabetes. PTEN interactors are responsible for some functional roles of PTEN beyond the negative regulation of the PI3K pathway and are thus of great importance in cell biology. Both high-data content proteomics-based approaches and low-data content PPI approaches have been used to investigate the interactome of PTEN and elucidate further functions of PTEN. While low-data content approaches rely on co-immunoprecipitation and Western blotting, and as such require previously generated hypotheses, high-data content approaches such as affinity pull-down proteomic assays or the yeast 2-hybrid system are hypothesis generating. This review provides an overview of the PTEN interactome, including redox effects, and critically appraises the methods and results of high-data content investigations into the global interactome of PTEN. The biological significance of findings from recent studies is discussed and illustrates the breadth of cellular functions of PTEN that can be discovered by these approaches.

Codelivery of Sustainable Antimicrobial Agents and Platelet-Derived Growth Factor via Biodegradable Nanofibers for Repair of Diabetic Infectious Wounds

More than half of diabetic wounds demonstrate clinical signs of infection at presentation and lead to poor outcomes. This work develops coaxial sheath-core nanofibrous poly(lactide-co-glycolide) (PLGA) scaffolds that are loaded with bioactive antibiotics and platelet-derived growth factor (PDGF) for the repair of diabetic infectious wounds. PDGF and PLGA/antibiotic solutions were pumped, respectively, into two independent capillary tubings for coaxial electrospinning to prepare biodegradable sheath-core nanofibers. Spun nanofibrous scaffolds sustainably released PDGF, vancomycin, and gentamicin for 3 weeks. The scaffolds also reduced the phosphatase and tensin homologue content, enhanced the amount of angiogenesis marker (CD31) around the wound area, and accelerated healing in the early stage of infected diabetic wound repair. Antibiotic/biomolecule-loaded PLGA nanofibers may provide a very effective way to aid tissue regeneration at the sites of infected diabetic wounds.

Role of phosphatase and tensin homolog in pathogenesis of ameloblastoma: An immunohistochemical study

Background

Altered molecular signaling pathways in ameloblastoma have been identified to play a pivotal role in the mechanism of oncogenesis, differentiation, and tumor progression. Phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin pathway is one of the signaling pathways that are associated with the pathogenesis of ameloblastoma. Phosphatase and tensin homolog (PTEN) controls cell migration and proliferation. It monitors the level of the Akt and maintains cellular integrity. The present study was aimed to study the immunoexpression of PTEN in ameloblastoma to understand its role in the pathogenesis of ameloblastoma.

Materials and Methods

Twenty cases of ameloblastoma and ten cases of normal tooth germ were subjected to immunohistochemical staining against PTEN.

Results

Strong PTEN immunopositivity was seen in the tooth germs, while weak positivity was seen in the ameloblastoma. The immunoscore for PTEN was calculated by adding the percentage score and the intensity score. Seventeen cases showed the reduced PTEN expression in the epithelial component of ameloblastoma. The unpaired t-test showed a statistically significant difference in the mean PTEN immunoscore in tooth germ and ameloblastoma.

Conclusion

The study showed reduced PTEN immunoreactivity, which plays a role in the pathogenesis of ameloblastoma, through Akt pathway.

Early-onset renal cell carcinoma in PTEN harmatoma tumour syndrome

Individuals with PTEN hamartoma tumour syndrome (PHTS), including Cowden syndrome (CS), are susceptible to multiple benign hamartomas and an increased risk of cancer, particularly breast, endometrial, and thyroid. As a result, individuals undergo enhanced surveillance for early detection of these cancers. However, less commonly occurring cancers, such as colorectal and kidney, have insufficient guidelines for early detection. Currently, screening for kidney cancer via renal ultrasound begins at 40 years of age, because there were only rare cases of elevated risk in prospective series under 40. There have, however, been accumulating reports of kidney cancer in individuals with CS in their 30s, illustrating a need to lower the age of surveillance. We present additional evidence of renal cell carcinoma in two individuals with CS in their early twenties, and propose a reassessment of the abdominal surveillance in patients with PHTS. We propose biannual screening for kidney cancer beginning at 20 years of age.

Long non-coding RNA-ZNF281 upregulates PTEN expression via downregulation of microRNA-221 in non-small cell lung cancer

A recent study reported that zinc finger protein (ZNF)281 is a tumor-suppressive long non-coding (lnc)RNA in glioma. The present study investigated the role of ZNF281 in non-small cell lung cancer (NSCLC). ZNF281 expression in paired cancer and non-cancerous tissues from patients with NSCLCs was analyzed by RNA extraction and reverse transcription-quantitative-PCR. A 5-year follow up on patients was performed to analyze the prognostic value of ZNF281 for NSCLC. Cell transfections of ZNF281 or phosphatase and tensin homolog (PTEN) expression vector and microRNA (miR)-221 mimic were performed to analyze the relationship between ZNF281, miR-221 and PTEN. Cell apoptosis and proliferation were analyzed using Cell Counting Kit-8 and flow cytometry, respectively. In patients with NSCLC, expression levels of ZNF281 were significantly lower in cancer tissues compared with in non-cancerous tissues, and lower levels of ZNF281 expression in cancerous tissues predicted poor survival. In NSCLC cells, ZNF281 overexpression resulted in upregulated PTEN and downregulated miR-221 expression, whereas cells with miR-221 overexpression exhibited downregulated PTEN expression and unaffected ZNF281 expression. In addition, ZNF281 and PTEN overexpression resulted in accelerated cell apoptosis and inhibited the cell proliferation of NSCLC cells. Notably, miR-221 overexpression exhibited an opposite effect and attenuated the functions of ZNF281 and PTEN overexpression. Therefore, ZNF281 may upregulate PTEN via downregulation of miR-221 in NSCLC, resulting in inhibition of cancer cell proliferation and the promotion of apoptosis.

Novel Insights into PARK7 (DJ-1), a Potential Anti-Cancer Therapeutic Target, and Implications for Cancer Progression

The expression of PARK7 is upregulated in various types of cancer, suggesting its potential role as a critical regulator of the pathogenesis of cancer and in the treatment of cancer and neurodegenerative diseases, including Parkinson’s disease, Alzheimer’s disease, and Huntington disease. PARK7 activates various intracellular signaling pathways that have been implicated in the induction of tumor progression, which subsequently enhances tumor initiation, continued proliferation, metastasis, recurrence, and resistance to chemotherapy. Additionally, secreted PARK7 has been identified as a high-risk factor for the pathogenesis and survival of various cancers. This review summarizes the current understanding of the correlation between the expression of PARK7 and tumor progression.

TRIM21 and PHLDA3 negatively regulate the crosstalk between the PI3K/AKT pathway and PPP metabolism

PI3K/AKT signaling is known to regulate cancer metabolism, but whether metabolic feedback regulates the PI3K/AKT pathway is unclear. Here, we demonstrate the important reciprocal crosstalk between the PI3K/AKT signal and pentose phosphate pathway (PPP) branching metabolic pathways. PI3K/AKT activation stabilizes G6PD, the rate-limiting enzyme of the PPP, by inhibiting the newly identified E3 ligase TIRM21 and promotes the PPP. PPP metabolites, in turn, reinforce AKT activation and further promote cancer metabolic reprogramming by blocking the expression of the AKT inhibitor PHLDA3. Knockout of TRIM21 or PHLDA3 promotes crosstalk and cell proliferation. Importantly, PTEN null human cancer cells and in vivo murine models are sensitive to anti-PPP treatments, suggesting the importance of the PPP in maintaining AKT activation even in the presence of a constitutively activated PI3K pathway. Our study suggests that blockade of this reciprocal crosstalk mechanism may have a therapeutic benefit for cancers with PTEN loss or PI3K/AKT activation.

Inhibition of PLK4 might enhance the anti-tumour effect of bortezomib on glioblastoma via PTEN/PI3K/AKT/mTOR signalling pathway

Glioblastoma (GBM) is one of the most common aggressive cancers of the central nervous system in adults with a high mortality rate. Bortezomib is a boronic acid-based potent proteasome inhibitor that has been actively studied for its anti-tumour effects through inhibition of the proteasome. The proteasome is a key component of the ubiquitin-proteasome pathway that is critical for protein homeostasis, regulation of cellular growth, and apoptosis. Overexpression of polo-like kinase 4 (PLK4) is commonly reported in tumour cells and increases their invasive and metastatic abilities. In this study, we established a cell model of PLK4 knockdown and overexpression in LN-18, A172 and LN-229 cells and found that knockdown of PLK4 expression enhanced the anti-tumour effect of bortezomib. We further found that this effect may be mediated by the PTEN/PI3K/AKT/mTOR signalling pathway and that the apoptotic and oxidative stress processes were activated, while the expression of matrix metalloproteinases (MMPs) was down-regulated. Similar phenomenon was observed using in vitro experiments. Thus, we speculate that PLK4 inhibition may be a new therapeutic strategy for GBM.

Pten-mediated Gsk3β modulates the naïve pluripotency maintenance in embryonic stem cells

Mouse embryonic stem cells (ESCs) are isolated from the inner cell mass of blastocysts, and they exist in different states of pluripotency—naïve and primed states. Pten is a well-known tumor suppressor. Here, we generated Pten^−/− mouse ESCs with the CRISPR-Cas9 system and verified that Pten^−/− ESCs maintained naïve pluripotency by blocking Gsk3β activity. Serum/LIF and 2i (MAPK and GSK3 inhibitors) conditions are commonly used for ESC maintenance. We show that the Pten-inhibitor SF1670 contributed to sustaining mouse ESCs and that Pten activation by the S380A, T382A, and T383A mutations (Pten-A3) suppressed the pluripotency of ESCs. The in vivo teratoma formation ability of SF1670-treated ESCs increased, while the Pten-A3 mutations suppressed teratoma formation. Furthermore, the embryoid bodies derived from Pten-deficient ESCs or SF1670-treated wild-type ESCs showed greater expression of ectoderm and pluripotency markers. These results suggest that Pten-mediated Gsk3β modulates the naïve pluripotency of ESCs and that Pten ablation regulates the lineage-specific differentiation.

The ubiquitin system: orchestrating cellular signals in non-small-cell lung cancer

The ubiquitin system, known as a common feature in eukaryotes, participates in multiple cellular processes, such as signal transduction, cell-cycle progression, receptor trafficking and endocytosis, and even the immune response. In lung cancer, evidence has revealed that aberrant events in ubiquitin-mediated processes can cause a variety of pathological outcomes including tumorigenesis and metastasis. Likewise, ubiquitination on the core components contributing to the activity of cell signaling controls bio-signal turnover and cell final destination. Given this, inhibitors targeting the ubiquitin system have been developed for lung cancer therapies and have shown great prospects for clinical application. However, the exact biological effects and physiological role of the drugs used in lung cancer therapies are still not clearly elucidated, which might seriously impede the progress of treatment. In this work, we summarize current research advances in cell signal regulation processes mediated through the ubiquitin system during the development of lung cancer, with the hope of improving the therapeutic effects by means of aiming at efficient targets.

Downregulation of EVI1 Expression Inhibits Cell Proliferation and Induces Apoptosis in Hilar Cholangiocarcinoma via the PTEN/AKT Signalling Pathway

Aims: Hilar cholangiocarcinoma (HCCA) is a tumour with high malignancy, low surgical resection potential, and a poor prognosis. Ecotropic Viral Integration site 1 (EVI1) is a transcriptional regulator that has been proven to be associated with tumourigenesis and progression in many human solid tumours. However, the expression of EVI1 and its role in HCCA progression remain unclear. The aim of this study was to clarify the association between EVI1 expression and clinical outcomes in patients with HCCA.

Methods: The expression of EVI1 in HCCA tissue samples and cell lines was examined by quantitative real-time PCR (qRT-PCR), Western blotting, and immunohistochemistry (IHC). Kaplan-Meier analysis was used for survival analysis. A log-rank test was performed for univariate analysis of survival, and a Cox regression model was utilized for multivariate analysis of survival. Cell proliferation was measured by cell counting kit-8 (CCK-8), colony formation, and 5-ethynyl-2'-deoxyuridine (EdU) assays. The cell cycle was evaluated by flow cytometry. Cell apoptosis was detected by flow cytometry and a terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labelling (TUNEL) assay. In vivo tumour growth was observed for xenografts in nude mice.

Results: EVI1 expression was upregulated in HCCA tissue samples and correlated with a poor prognosis. In clinical specimens, the expression of EVI1 correlated with tumour histological grade and tumour size. Knocking down EVI1 expression reduced HCCA cell proliferation, blocked cell cycle progression, and promoted apoptosis in vitro and in vivo. Furthermore, we found that EVI1 could regulate the AKT signalling pathway by regulating PTEN levels in HCCA.

Conclusion: Our data revealed that EVI1 played important roles in HCCA tumourigenesis and development. Our findings suggest that EVI1 may be a potentially useful therapeutic target in HCCA.

Genetic and molecular determinants of prostate cancer among Iranian patients: An update

Prostate cancer (PCa) is one of the most common age-related cancers among men. Various environmental and genetic factors are involved in the development and progression of PCa. In most cases, the primary symptoms of disease are not severe. Therefore, it is common for patients to be referred with severe clinical manifestations at advanced stages of disease. Since this malignancy is age related and Iran will face a significant increase in the number of seniors, it is expected that the prevalence of PCa among Iranian men will rise. PCa progression has been observed to be associated with genetic and ethnic factors. It may therefore be clinically useful to determine a panel of genetic markers, in addition to routine diagnostic methods, to detect tumors in the early stages. In the present review, we have summarized the reported genetic markers in PCa Iranian patients to pave the way for the determination of an ethnic specific genetic marker panel for the early detection of PCa. To understand the genetic and molecular biology of PCa among Iranians, we have categorized these genetic markers based on their cellular functions.

Reactivation of PTEN tumor suppressor for cancer treatment through inhibition of a MYC-WWP1 inhibitory pathway

Activation of tumor suppressors for the treatment of human cancer has been a long sought, yet elusive, strategy. PTEN is a critical tumor suppressive phosphatase that is active in its dimer configuration at the plasma membrane. Polyubiquitination by the ubiquitin E3 ligase WWP1 (WW domain-containing ubiquitin E3 ligase 1) suppressed the dimerization, membrane recruitment, and function of PTEN. Either genetic ablation or pharmacological inhibition of WWP1 triggered PTEN reactivation and unleashed tumor suppressive activity. WWP1 appears to be a direct MYC (MYC proto-oncogene) target gene and was critical for MYC-driven tumorigenesis. We identified indole-3-carbinol, a compound found in cruciferous vegetables, as a natural and potent WWP1 inhibitor. Thus, our findings unravel a potential therapeutic strategy for cancer prevention and treatment through PTEN reactivation.

Dysfunction of the corticostriatal pathway in autism spectrum disorders

The corticostriatal pathway that carries sensory, motor, and limbic information to the striatum plays a critical role in motor control, action selection, and reward. Dysfunction of this pathway is associated with many neurological and psychiatric disorders. Corticostriatal synapses have unique features in their cortical origins and striatal targets. In this review, we first describe axonal growth and synaptogenesis in the corticostriatal pathway during development, and then summarize the current understanding of the molecular bases of synaptic transmission and plasticity at mature corticostriatal synapses. Genes associated with autism spectrum disorder (ASD) have been implicated in axonal growth abnormalities, imbalance of the synaptic excitation/inhibition ratio, and altered long-term synaptic plasticity in the corticostriatal pathway. Here, we review a number of ASD-associated high-confidence genes, including FMR1, KMT2A, GRIN2B, SCN2A, NLGN1, NLGN3, MET, CNTNAP2, FOXP2, TSHZ3, SHANK3, PTEN, CHD8, MECP2, DYRK1A, RELN, FOXP1, SYNGAP1, and NRXN, and discuss their relevance to proper corticostriatal function.

MiR-205 Dysregulations in Breast Cancer: The Complexity and Opportunities

MicroRNAs (miRNAs) are endogenous non-coding small RNAs that downregulate target gene expression by imperfect base-pairing with the 3' untranslated regions (3'UTRs) of target gene mRNAs. MiRNAs play important roles in regulating cancer cell proliferation, stemness maintenance, tumorigenesis, cancer metastasis, and cancer therapeutic resistance. While studies have shown that dysregulation of miRNA-205-5p (miR-205) expression is controversial in different types of human cancers, it is generally observed that miR-205-5p expression level is downregulated in breast cancer and that miR-205-5p exhibits a tumor suppressive function in breast cancer. This review focuses on the role of miR-205-5p dysregulation in different subtypes of breast cancer, with discussions on the effects of miR-205-5p on breast cancer cell proliferation, epithelial-mesenchymal transition (EMT), metastasis, stemness and therapy-resistance, as well as genetic and epigenetic mechanisms that regulate miR-205-5p expression in breast cancer. In addition, the potential diagnostic and therapeutic value of miR-205-5p in breast cancer is also discussed. A comprehensive list of validated miR-205-5p direct targets is presented. It is concluded that miR-205-5p is an important tumor suppressive miRNA capable of inhibiting the growth and metastasis of human breast cancer, especially triple negative breast cancer. MiR-205-5p might be both a potential diagnostic biomarker and a therapeutic target for metastatic breast cancer.

Fibroblast-derived CXCL12 regulates PTEN expression and is associated with the proliferation and invasion of colon cancer cells via PI3k/Akt signaling

Background

Stromal-derived CXCL12 play an important role which influence the proliferation and invasiveness of colon cancer in microenvironment. The present study aimed to analyze the underlying mechanism by which CXCL12 and tumour suppressor protein phosphatase and tensin homologue deleted on chromosome 10 (PTEN) influences the metastatic potential of colon cancer and internal relation of colon cancer and stromal cells.

Methods

RT-PCR and western blot were detected the expression of CXCL12, CXCR4 and PTEN in colon cancer cells and stromal cells. The co-operative effects of CXCL12 and PTEN on proliferation and invasion of colon cancer cells were evaluated by real-time PCR, proliferation and invasion assays using an in vitro system consisting of co-cultured cancer cells and stromal cells. We eventually investigated activation of PI3K/Akt signaling by CXCL12 regulate PTEN and involved in the metastatic process of colon cancer. In addition, we also examine how the knockdown of PTEN influences proliferation and invasion and correlate with CXCL12/CXCR4/PI3K/Akt, determination of PTEN up-down-stream targets that preferentially contribute to tumorigenesis.

Results

Blockage of PTEN phosphorylation led to a stronger enhancement of cell proliferation and invasion upon stimulation with CXCL12 via its activation of the PI3K/Akt signaling pathway. Furthermore, knockdown of PTEN by siRNA transfection was also found to enhance the activation of the PI3K/Akt pathway, thereby promoting cell invasion and proliferation. CXCL12 induced transcriptional down-regulation of activated PTEN and this signaling pathway promotes cell survival. CXCL12/CXCR4/PI3K/Akt cascade may be critical for colon cancer cells to metastasize.

Conclusions

Based on our results, we suggest that the modification of CXCR4, PTEN, or PI3K function might be promising new therapeutic approaches to inhibit the aggressive spread of colon cancer.

PTEN Suppresses Glycolysis by Dephosphorylating and Inhibiting Autophosphorylated PGK1

The PTEN tumor suppressor is frequently mutated or deleted in cancer and regulates glucose metabolism through the PI3K-AKT pathway. However, whether PTEN directly regulates glycolysis in tumor cells is unclear. We demonstrate here that PTEN directly interacts with phosphoglycerate kinase 1 (PGK1). PGK1 functions not only as a glycolytic enzyme but also as a protein kinase intermolecularly autophosphorylating itself at Y324 for activation. The protein phosphatase activity of PTEN dephosphorylates and inhibits autophosphorylated PGK1, thereby inhibiting glycolysis, ATP production, and brain tumor cell proliferation. In addition, knockin expression of a PGK1 Y324F mutant inhibits brain tumor formation. Analyses of human glioblastoma specimens reveals that PGK1 Y324 phosphorylation levels inversely correlate with PTEN expression status and are positively associated with poor prognosis in glioblastoma patients. This work highlights the instrumental role of PGK1 autophosphorylation in its activation and PTEN protein phosphatase activity in governing glycolysis and tumorigenesis.

Synthetic Essentiality of Metabolic Regulator PDHK1 in PTEN-Deficient Cells and Cancers

Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a tumor suppressor and bi-functional lipid and protein phosphatase. We report that the metabolic regulator pyruvate dehydrogenase kinase1 (PDHK1) is a synthetic-essential gene in PTEN-deficient cancer and normal cells. The PTEN protein phosphatase dephosphorylates nuclear factor κB (NF-κB)-activating protein (NKAP) and limits NFκB activation to suppress expression of PDHK1, a NF-κB target gene. Loss of the PTEN protein phosphatase upregulates PDHK1 to induce aerobic glycolysis and PDHK1 cellular dependence. PTEN-deficient human tumors harbor increased PDHK1, a biomarker of decreased patient survival. This study uncovers a PTEN-regulated signaling pathway and reveals PDHK1 as a potential target in PTEN-deficient cancers.

Potential Prognostic Significance of p185HER2 Overexpression with Loss of PTEN Expression in Gastric Carcinomas

Aims and Background

The HER2 gene encodes a 185-kd transmembrane glycoprotein receptor (p185HER2) that has partial homology with the epidermal growth factor receptor and shares intrinsic tyrosine kinase activity. The phosphatase and tensin homolog mutated on chromosome ten (PTEN) gene product is a protein tyrosine phosphatase that participates in modulating the phosphoinositide 3-kinase pathway which has antagonizing activity to protein tyrosine kinase. The authors investigated the correlation between clinicopathologic variables including survival and the overexpression of the p185HER2 with loss of PTEN expression in gastric adenocarcinoma patients.

Methods

The protein expression of p185HER2 and PTEN was examined by immunohistochemical stain in paraffin-embedded tissues of 94 (M:F, 52:42) gastric adenocarcinoma patients by using monoclonal antibody, and the results were related to clinicopathological variables and survival.

Results

p185HER2 overexpression correlated positively with lymph node metastasis, distant metastasis, AJCC classification, higher relapse rate. Patients with overexpression of p185HER2 were found to have significantly lower disease-free survival ( P = 0.003) and overall survival ( P = 0.0004). Loss of PTEN expression correlated positively with depth of invasion (T stage) and was more frequent in the advanced stage. The patient group with p185HER2 overexpression and loss of PTEN expression showed significantly shorter disease-free and overall survival ( P = 0.03, P = 0.01) than the other groups.

Conclusions

Our observations suggest potential prognostic significance of p185HER2 overexpression with PTEN loss in gastric adenocarcinoma patients. This opens up the possibility of considering p185HER2 and PTEN as a therapeutic target in gastric cancer.

TRIM14 promotes cell proliferation and inhibits apoptosis by suppressing PTEN in colorectal cancer

Background

Colorectal cancer (CRC) is among the most frequent and lethal malignancies worldwide. Although great advances have been made in the treatment of CRC, prognosis remains poor. Our previous study indicated that tripartite motif-containing 14 (TRIM14) was upregulated in CRC samples.

Methods

In the current study, the association between TRIM14 and CRC was investigated. Protein expression was determined by Western blotting and immunohistochemistry. Further, the biological roles of TRIM14 in CRC cell proliferation and apoptosis were explored both in vitro and in vivo.

Results

We observed that increased TRIM14 expression in CRC tissues was closely related with aggressive clinicopathological characteristics and poor prognosis. TRIM14 knockdown markedly reduced proliferation and increased apoptosis in HT-29 and SW620 cells, whereas TRIM14 overexpression in LoVo cells displayed opposite results. Xenograft experiments using HT-29 cells confirmed suppression of tumor growth and induction of apoptosis upon TRIM14 knockdown in vivo. Furthermore, downregulation of TRIM14 inhibited the AKT pathway, as indicated by reduced levels of phosphorylated AKT, Bcl-2 and Cyclin D1, and elevated levels of phosphatase and tensin homology (PTEN) and p27. In addition, TRIM14 colocalized with PTEN in the cytoplasm and induced PTEN ubiquitination. Moreover, PTEN overexpression significantly inhibited pro-proliferative effects of TRIM14, indicating an involvement of PTEN/AKT signaling in mediating TRIM14 functions.

Conclusions

The present data demonstrate that TRIM14 overexpression promotes CRC cell proliferation, suggesting TRIM14 as an attractive therapeutic target for CRC.

Recent Research Advances in Mitosis during Mammalian Gametogenesis

Mitosis is a highly sophisticated and well-regulated process during the development and differentiation of mammalian gametogenesis. The regulation of mitosis plays an essential role in keeping the formulation in oogenesis and gametogenesis. In the past few years, substantial research progress has been made by showing that cyclins/cyclin-dependent kinase (CDK) have roles in the regulation of meiosis. In addition, more functional signaling molecules have been discovered in mitosis. Growing evidence has also indicated that miRNAs influence cell cycling. In this review, we focus on specific genes, cyclins/Cdk, signaling pathways/molecules, and miRNAs to discuss the latest achievements in understanding their roles in mitosis during gametogenesis. Further elucidation of mitosis during gametogenesis may facilitate delineating all processes of mammalian reproduction and the development of disease treatments.

The AKT kinase signaling network is rewired by PTEN to control proximal BCR signaling in germinal center B cells

Compared to naïve B cells (NBCs), both B cell antigen receptor (BCR) and CD40 signaling are rewired in germinal center (GC) B cells (GCBCs) to optimize selection for high-affinity B cells. The mechanism for BCR reprogramming in GCBCs remains unknown. We describe a GC-specific, AKT kinase-driven negative feedback loop that attenuates BCR signaling. A mass spectrometry proteomic approach revealed that AKT activity was retargeted in GCBCs compared to NBCs. Retargeting was linked to differential AKT T308 and S473 phosphorylation, in turn due to GC-specific upregulation of phosphoinositide-dependent protein kinase PDK1 and the phosphatase PTEN, which retuned phosphatidylinositol-3-OH kinase (PI3K) signals. In GCBCs, AKT preferentially targeted CSK, SHP-1 and HPK1, which are negative regulators of BCR signaling. Phosphorylation results in markedly increased enzymatic activity of these proteins, creating a negative-feedback loop that dampens upstream BCR signaling. Inhibiting AKT substantially enhanced activation of BCR proximal kinase LYN as well as downstream BCR signaling molecules in GCBCs, establishing the relevance of this pathway.

PTENα promotes neutrophil chemotaxis through regulation of cell deformability

Neutrophils are a major component of immune defense and are recruited through neutrophil chemotaxis in response to invading pathogens. However, the molecular mechanism that controls neutrophil chemotaxis remains unclear. Here, we report that PTENα, the first isoform identified in the PTEN family, regulates neutrophil deformability and promotes chemotaxis of neutrophils. A high level of PTENα is detected in neutrophils and lymphoreticular tissues. Homozygous deletion of PTENα impairs chemoattractant-induced migration of neutrophils. We show that PTENα physically interacts with cell membrane cross-linker moesin through its FERM domain and dephosphorylates moesin at Thr558, which disrupts the association of filamentous actin with the plasma membrane and subsequently induces morphologic changes in neutrophil pseudopodia. These results demonstrate that PTENα acts as a phosphatase of moesin and modulates neutrophil-mediated host immune defense. We propose that PTENα signaling is a potential target for the treatment of infections and immune diseases.

MicroRNA-498 promotes proliferation and migration by targeting the tumor suppressor PTEN in breast cancer cells

Triple negative breast cancer (TNBC) is a subtype of breast cancer with a poor prognosis and high mortality rate. The tumor suppressor phosphatase and tensin homolog deleted on chromosome 10 (PTEN) plays an important role in cell proliferation and cell migration by negatively regulating the PI3K/Akt pathway. PTEN is downregulated by microRNAs in multiple cancers. However, few microRNAs have been reported to directly target PTEN in TNBC. In this study, microRNAs predicted to target PTEN were screened by immunoblotting and luciferase reporter assays. Expression levels of microRNA-498 (miR-498) were measured by TaqMan microRNA assays. We performed clonogenic, cell cycle and scratch wound assays to examine the oncogenic role of miR-498. We demonstrated that miR-498 directly targeted the 3'untranslated region of PTEN mRNA and reduced PTEN protein levels in TNBC cells. Compared with the non-tumorigenic breast epithelial cell line MCF-10A, TNBC cell lines overexpressed miR-498. Moreover, miR-498 promoted cell proliferation and cell cycle progression in TNBC cells in a PTEN-dependent manner. Suppressing miR-498 overexpression impaired the oncogenic effects of miR-498 on cell proliferation and cell migration. This study identified a novel microRNA (miR-498) overexpressed in TNBC cells and its oncogenic role in suppressing PTEN. These results provide new insight into the downregulation of PTEN and indicate a potential therapeutic target for treating TNBC.

Bergapten induces G1 arrest and pro-apoptotic cascade in colorectal cancer cells associating with p53/p21/PTEN axis

Bergapten is a natural compound and has potent anticancer activities. In this study, we explored the cytotoxicity of bergapten on colorectal cancer (CRC) cell DLD-1 and LoVo and its underlying mechanisms. We observed that bergapten (30 and 50 μM) decreased the viability of the CRC cells and induced the G0/G1 and sub-G1 phase arrest. Furthermore, immunoblotting results indicated that bergapten increased p53, phospho-p53(Ser-46), p21, PUMA, Bax, PTEN, and the caspase-9 and caspase-3 cleavage, but decreased cyclin E, CDK2, and phosphor-AKT(Ser-473) in the CRC cells. Inhibition of p53 by pifithrin-α reversed the bergapten-induced p53-mediated apoptotic cascade and restored the survival signaling and cell viability. Collectively, our findings reveal that bergapten decrease the cell viability and induce cell cycle arrest in the CRC cells, which may be attributed to p53-mediated apoptotic cascade, upregulation of p21 and PTEN, and inhibition of AKT.

Mechanisms of apoptosis modulation by curcumin: Implications for cancer therapy

Cancer incidences are growing and cause millions of deaths worldwide. Cancer therapy is one of the most important challenges in medicine. Improving therapeutic outcomes from cancer therapy is necessary for increasing patients' survival and quality of life. Adjuvant therapy using various types of antibodies or immunomodulatory agents has suggested modulating tumor response. Resistance to apoptosis is the main reason for radioresistance and chemoresistance of most of the cancers, and also one of the pivotal targets for improving cancer therapy is the modulation of apoptosis signaling pathways. Apoptosis can be induced by intrinsic or extrinsic pathways via stimulation of several targets, such as membrane receptors of tumor necrosis factor-α and transforming growth factor-β, and also mitochondria. Curcumin is a naturally derived agent that induces apoptosis in a variety of different tumor cell lines. Curcumin also activates redox reactions within cells inducing reactive oxygen species (ROS) production that leads to the upregulation of apoptosis receptors on the tumor cell membrane. Curcumin can also upregulate the expression and activity of p53 that inhibits tumor cell proliferation and increases apoptosis. Furthermore, curcumin has a potent inhibitory effect on the activity of NF-κB and COX-2, which are involved in the overexpression of antiapoptosis genes such as Bcl-2. It can also attenuate the regulation of antiapoptosis PI3K signaling and increase the expression of MAPKs to induce endogenous production of ROS. In this paper, we aimed to review the molecular mechanisms of curcumin-induced apoptosis in cancer cells. This action of curcumin could be applicable for use as an adjuvant in combination with other modalities of cancer therapy including radiotherapy and chemotherapy.

Genetic alteration of Exon 5 of the PTEN gene in Indian patients with ameloblastoma

OBJECTIVE

The PI3K/Akt/mTOR pathway is one of the signaling pathways associated with the pathogenesis of ameloblastoma. The phosphatase and tensin (PTEN) homologue controls cell migration and proliferation. It monitors the level of Akt and maintains cellular integrity. The aim of the present study was to study the genetic alteration of Exon 5 of the PTEN gene in Indian patients with ameloblastoma.

STUDY DESIGN

Total DNA was extracted from formalin-fixed paraffin-embedded tissue samples from 20 cases with solid multicystic ameloblastoma (SMA) and from 10 cases with normal tooth germ. Exon 5 of the PTEN gene, was assessed for its role in the pathogenesis of ameloblastoma.

RESULTS

Five of 20 cases of SMA showed genetic alteration. Of these cases 3 (15%) showed silent mutation, 1 (5%) showed change in amino acid sequence from valine to glutamic acid, and 1 (5%) showed nonsense-mediated mRNA decay.

CONCLUSIONS

The present study showed 25% somatic mutational frequency in exonic region 5 of the PTEN gene. This may indicate its role in the pathogenesis of ameloblastoma.

Restoration of tumour-growth suppression in vivo via systemic nanoparticle-mediated delivery of PTEN mRNA

Phosphatase and tensin homologue deleted on chromosome 10 (PTEN) is a well-characterized tumour-suppressor gene that is lost or mutated in about half of metastatic castration-resistant prostate cancers and in many other human cancers. The restoration of functional PTEN as a treatment for prostate cancer has, however, proven difficult. Here, we show that PTEN messenger RNA (mRNA) can be reintroduced into PTEN-null prostate cancer cells in vitro and in vivo via its encapsulation in polymer-lipid hybrid nanoparticles coated with a polyethylene glycol shell. The nanoparticles are stable in serum, elicit low toxicity and enable high PTEN mRNA transfection in prostate cancer cells. Moreover, significant inhibition of tumour growth is achieved when delivered systemically in multiple mouse models of prostate cancer. We also show that the restoration of PTEN function in PTEN-null prostate cancer cells inhibits the phosphatidylinositol 3-kinase (PI3K)-AKT pathway and enhances apoptosis. Our findings provide proof-of-principle evidence of the restoration of mRNA-based tumour suppression in vivo.

BRCA1-IRIS promotes human tumor progression through PTEN blockade and HIF-1α activation

Spontaneous overexpression of endogenous IRIS, an alternatively spliced product of the tumor suppressor gene BRCA1, allows it to function as an oncoprotein that stimulates a potentially lethal outcome, i.e. metastasis of human cancer cells to tissues served, in part, by the arterial circulation. It does so by suppressing phosphatase and tensin homolog (PTEN) mRNA synthesis, thereby stabilizing and activating HIF-1α in normoxic cells. Thus, this study provides a strong rationale for exploring the therapeutic value of interfering with spontaneously overexpressed IRIS function in multiple types of tumors that can naturally overexpress it.

BRCA1 is an established breast and ovarian tumor suppressor gene that encodes multiple protein products whose individual contributions to human cancer suppression are poorly understood. BRCA1-IRIS (also known as “IRIS”), an alternatively spliced BRCA1 product and a chromatin-bound replication and transcription regulator, is overexpressed in various primary human cancers, including breast cancer, lung cancer, acute myeloid leukemia, and certain other carcinomas. Its naturally occurring overexpression can promote the metastasis of patient-derived xenograft (PDX) cells and other human cancer cells in mouse models. The IRIS-driven metastatic mechanism results from IRIS-dependent suppression of phosphatase and tensin homolog (PTEN) transcription, which in turn perturbs the PI3K/AKT/GSK-3β pathway leading to prolyl hydroxylase-independent HIF-1α stabilization and activation in a normoxic environment. Thus, despite the tumor-suppressing genetic origin of IRIS, its properties more closely resemble those of an oncoprotein that, when spontaneously overexpressed, can, paradoxically, drive human tumor progression.

Helicobacter pylori promotes gastric epithelial cell survival through the PLK1/PI3K/Akt pathway

Purpose

Helicobacter pylori (H. pylori) infection plays a critical role in the process of gastric carcinogenesis. However, the complicated pathogenic mechanism is still unclear. Polo-like kinase 1 (PLK1) is involved in the development of multiple human malignancies, including gastric cancer. Therefore, this study aimed to elucidate the role of PLK1 in H. pylori-induced gastric carcinogenesis and the underlying signaling mechanism.

Materials and methods

We detected the expression of PLK1 in 166 patients in different stages of gastric carcinogenesis as well as the established Mongolian gerbil model with H. pylori infection by immunohistochemistry. Cell Counting Kit-8 was used to estimate the survival of gastric cancer cells.

Results

We found that PLK1 expression in gastric cancer tissues was significantly higher than that of paired adjacent mucosa. PLK1 expression was increased in intestinal metaplasia, dysplasia, and gastric cancer tissues compared to chronic non-atrophic gastritis tissues. Notably, PLK1 expression was much lower in H. pylori-negative tissues than in H. pylori-positive tissues at intestinal metaplasia stage. In addition, H. pylori infection increased PLK1 expression in the gastric epithelial cells of the Mongolian gerbil model, which was positively related to the duration of H. pylori infection. Inhibition of PLK1 significantly reduced H. pylori-induced cell proliferation. Furthermore, incubation of MKN-28 cells with H. pylori resulted in a significant increase in PLK1, p-PTEN, and the downstream PI3K/Akt pathway, and pretreatment with a PLK1 inhibitor reversed these molecular changes.

Conclusion

PLK1 is involved in H. pylori-induced gastric carcinogenesis at the early stage by activating the PI3K/Akt signaling pathway. These results may contribute to the development of new control strategies for H. pylori infection-related gastric cancer.

Downregulation of KMT2D suppresses proliferation and induces apoptosis of gastric cancer

PURPOSE

Histone lysine methyltransferase 2D (KMT2D/MLL2) is a known cancer-related protein; however, its function in gastric cancer (GC) remains uncharacterized. The present study sought to investigate the expression pattern and the role of KMT2D in GC.

METHODS

The expression of KMT2D were evaluated at mRNA and protein levels, while its clinico-pathological value were further explored. GC cells were transfected with KMT2D knockdown siRNAs or lentiviruses, and then detected by cell counting kit-8, plate clone formation, cell apoptosis, cycle, migration, invasion, and tumorigenesis assays.

RESULTS

Overexpression of KMT2D was observed in GC samples, and was strongly associated with poor survival. Depletion of KMT2D suppressed cell proliferation and induced apoptosis.

CONCLUSION

Our study demonstrated the upregulation of KMT2D in GC tissue, and KMT2D modulates proliferation and apoptosis in GC. Therefore, KMT2D might represent a novel oncogene for prognosis and optimal treatment of GC patients.

Phenotypic miRNA Screen Identifies miR-26b to Promote the Growth and Survival of Endothelial Cells

Endothelial cell (EC) proliferation is a crucial event in physiological and pathological angiogenesis. MicroRNAs (miRNAs) have emerged as important modulators of the angiogenic switch. Here we conducted high-content screening of a human miRNA mimic library to identify novel regulators of EC growth systematically. Several miRNAs were nominated that enhanced or inhibited EC growth. Of these, we focused on miR-26b, which is a conserved candidate and expressed in multiple human EC types. miR-26b overexpression enhanced EC proliferation, migration, and tube formation, while inhibition of miR-26b suppressed the proliferative and angiogenic capacity of ECs. A combinatory functional small interfering RNA (siRNA) screening of 48 predicted gene targets revealed that miR-26b enhanced EC growth and survival through inhibiting PTEN expression. Local administration of miR-26b mimics promoted the growth of new microvessels in the Matrigel plug model. In the mouse model of hindlimb ischemia, miR-26b was found to be downregulated in endothelium in the first week following ischemia, and local overexpression of miR-26b improved the survival of capillaries and muscle fibers in ischemic muscles. Our findings suggest that miR-26b enhances EC proliferation, survival, and angiogenesis. miR-26b is a potential target for developing novel pro-angiogenic therapeutics in ischemic disease.

A non-canonical tumor suppressive role for the long non-coding RNA MALAT1 in colon and breast cancers

Long noncoding RNAs (lncRNAs) constitute one of the largest classes of transcripts and have been widely implicated in various diseases such as cancer. Increasing evidence suggests that several lncRNAs are dysregulated and play critical roles in tumorigenesis. LncRNAs can be regulated by key oncogenes and tumor suppressors, adding complexity to the intricate crosstalk between protein coding genes and the noncoding transcriptome. In our study, we investigated the effect that dysregulation of the key tumor suppressor PTEN has on the noncoding transcriptome. We identified the lncRNA metastasis associated lung adenocarcinoma transcript 1 (MALAT1) as a target of PTEN and find that this regulation is conserved in both human and mouse as well as with both chronic and acute PTEN dysregulation. We show that this regulation is at least in part microRNA (miRNA)-dependent, and characterize the miRNAs that may be mediating this crosstalk. In summary, we establish and characterize a non-canonical PTEN-microRNA-MALAT1 axis that regulates tumorigenesis and describe for the first time that the MALAT1 lncRNA possesses novel tumor suppressive properties in colon and breast cancers.

The AHR represses nucleotide excision repair and apoptosis and contributes to UV-induced skin carcinogenesis

Ultraviolet B (UVB) radiation induces mutagenic DNA photoproducts, in particular cyclobutane pyrimidine dimers (CPDs), in epidermal keratinocytes (KC). To prevent skin carcinogenesis, these DNA photoproducts must be removed by nucleotide excision repair (NER) or apoptosis. Here we report that the UVB-sensitive transcription factor aryl hydrocarbon receptor (AHR) attenuates the clearance of UVB-induced CPDs in human HaCaT KC and skin from SKH-1 hairless mice. Subsequent RNA interference and inhibitor studies in KC revealed that AHR specifically suppresses global genome but not transcription-coupled NER. In further experiments, we found that the accelerated repair of CPDs in AHR-compromised KC depended on a modulation of the p27 tumor suppressor protein. Accordingly, p27 protein levels were increased in AHR-silenced KC and skin biopsies from AHR^−/− mice, and critical for the improvement of NER. Besides increasing NER activity, AHR inhibition was accompanied by an enhanced occurrence of DNA double-strand breaks triggering KC apoptosis at later time points after irradiation. The UVB-activated AHR thus acts as a negative regulator of both early defense systems against carcinogenesis, NER and apoptosis, implying that it exhibits tumorigenic functions in UVB-exposed skin. In fact, AHR^−/− mice developed 50% less UVB-induced cutaneous squamous cell carcinomas in a chronic photocarcinogenesis study than their AHR^+/+ littermates. Taken together, our data reveal that AHR influences DNA damage-dependent responses in UVB-irradiated KC and critically contributes to skin photocarcinogenesis in mice.

Multipronged activity of combinatorial miR-143 and miR-506 inhibits Lung Cancer cell cycle progression and angiogenesis in vitro

Lung cancer (LC) is the leading cause of cancer-related deaths. Downregulation of CDK1, 4 and 6, key regulators of cell cycle progression, correlates with decreased LC cell proliferation. Enforced expression of miRNAs (miRs) is a promising approach to regulate genes. Here, we study the combinatorial treatment of miR-143 and miR-506 to target the CDK1, 4/6 genes, respectively. We analyzed the differential expression of CDK genes by qPCR, and western blot, and evaluated changes in the cell cycle distribution upon combinatorial treatment. We used an antibody microarray analysis to evaluate protein expression, focusing on the cell cycle pathway, and performed RNA-sequencing for pathway analysis. The combinatorial miR treatment significantly downregulated CDK1, 4 and 6 expression, and induced a shift of the cell cycle populations, indicating a G1 and G2 cell cycle block. The two miRs induces strong cytotoxic activity, with potential synergism, and a significant Caspase 3/7 activation. We identified a strong inhibition of tube formation in the presence or absence VEGF in an in vitro angiogenesis model. Together with the pathways analysis of the RNA-sequencing data, our findings establish the combinatorial miR transfection as a viable strategy for lung cancer treatment that merits further investigation.

Broad-spectrum antiviral functions of duck interferon-induced protein with tetratricopeptide repeats (AvIFIT)

Mammalian interferon-induced proteins with tetratricopeptide repeats (IFITs) play important roles in many cellular processes and host innate immune response to viruses. However, the functions of IFIT proteins in birds are largely unknown. Here, we first describe that the only one avian IFIT protein is orthologous to ancestor of mammalian IFITs. We find that the predicted structure of duck AvIFIT protein is similar to that of human IFIT5. We also find that duck AvIFIT protein shows antiviral activity to a broad range of specific RNA and DNA viruses like mammalian IFIT proteins. Further analysis indicates that overexpression of duck AvIFIT protein in DF1 cells leads to a remarkable accumulation of cells at G1/S transition associated with growth arrest and may promote apoptosis. Moreover, duck AvIFIT binds to nucleoprotein (NP) of H5N1 influenza virus and upregulates the expression of genes involving the IFN pathway in DF1 cells. In summary, our findings support that duck AvIFIT protein plays critical role in host immune response to viruses, at least H5N1 virus, through affecting function of viral NP protein, magnifying the IFN signaling and arresting cell growth.