MiR-155-5p inhibits PDK1 and promotes autophagy via the mTOR pathway in cervical cancer

The Communication Between the PI3K/AKT/mTOR Pathway and Y-box Binding Protein-1 in Gynecological Cancer

Studies of the mechanistic (mammalian) target of rapamycin inhibitors (mTOR) represent a step towards the targeted treatment of gynecological cancers. It has been shown that women with increased levels of mTOR signaling pathway targets have worse prognosis compared to women with normal mTOR levels. Yet, targeting mTOR alone has led to unsatisfactory outcomes in gynecological cancer. The aim of our review was therefore to provide an overview of the most recent clinical results and basic findings on the interplay of mTOR signaling and cold shock proteins in gynecological malignancies. Due to their oncogenic activity, there are promising data showing that mTOR and Y-box-protein 1 (YB-1) dual targeting improves the inhibition of carcinogenic activity. Although several components differentially expressed in patients with ovarian, endometrial, and cervical cancer of the mTOR were identified, there are only a few investigated downstream actors in gynecological cancer connecting them with YB-1. Our analysis shows that YB-1 is an important player impacting AKT as well as the downstream actors interacting with mTOR such as epidermal growth factor receptor (EGFR), Snail or E-cadherin.

A Functional Polymorphism in the Promoter of miR-17-92 is Associated with a Reduced Risk of Cervical Squamous Cell Carcinoma

miR-17-92 cluster was differentially expressed in cervical cancer, playing an important role in regulating cell proliferation, apoptosis, migration, and invasion. The purpose of this study was to investigate the association between polymorphisms (i.e., rs9588884, rs982873, and rs1813389) in the promoter of miR-17-92 and the risk of cervical squamous cell carcinoma (CSCC). The rs9588884 polymorphism was genotyped using a Taqman assay and the rs982873 and rs1813389 polymorphisms were genotyped using a polymerase chain reaction-restriction fragment length polymorphism method. The expression levels of miR-17-92 were determined using a quantitative PCR analysis. The rs9588884 GG genotype was associated with a reduced risk of CSCC in homozygote comparison (adjusted OR = 0.47, 95% CI, 0.30-0.75, P = 0.001), dominant model (adjusted OR = 0.67, 95% CI, 0.50-0.91, P = 0.01), and recessive model (adjusted OR = 0.57, 95% CI, 0.38-0.85, P = 0.01). The rs9588884 G allele was also associated with a reduced risk of CSCC in allele comparison (adjusted OR = 0.71, 95% CI, 0.58-0.88, P = 0.002). Moreover, patients with the rs9588884 GG genotype had lower levels of miR-20a compared with the rs9588884 CC genotype (P = 0.03). These findings indicate that the rs9588884 GG genotype was associated with lower levels of miR-20a and eventually related to the risk of CSCC in Chinese women.

The chemical diversity and structure-based discovery of allosteric modulators for the PIF-pocket of protein kinase PDK1

Phosphoinositide-dependent protein kinase-1 (PDK1) is an important protein in mediating the PI3K-AKT pathway and is thus identified as a promising target. The catalytic activity of PDK1 is tightly regulated by allosteric modulators, which bind to the PDK1 Interacting Fragment (PIF) pocket of the kinase domain that is topographically distinct from the orthosteric, ATP binding site. Allosteric modulators by attaching to the less conserved PIF-pocket have remarkable advantages such as higher selectivity, less side effect, and lower toxicity. Targeting allosteric PIF-pocket of PDK1 has become the focus of recent attention. In this review, we summarise the current advances in the structure-based discovery of PDK1 allosteric modulators. We will first present the three-dimensional structure of PDK1 and illustrate the allosteric regulatory mechanism of PDK1 through the modulation of the PIF-pocket. Then, the recent advances of PDK1 allosteric modulators targeting the PIF-pocket will be recapitulated detailly according to the structural similarity of allosteric modulators.

miR-155-5p and miR-760 mediate radiation therapy suppressed malignancy of non-small cell lung cancer cells

MicroRNAs (miRNAs) play important roles in tumorigenesis of various cancers. Recent study suggested that miRNAs are involved in the therapeutic functions of radiation during cancer treatment. We found that radiation can decrease the migration and invasion of non-small cell lung cancer (NSCLC) cells. Mechanistically, radiation can significantly increase the expression of miR-155-5p and miR-760 in NSCLC cells. Knockdown of miR-155-5p and miR-760 can attenuate radiation suppressed proliferation of NSCLC cells. Among the various targets of miR-155-5p, radiation can decrease the expression of HIF-1α. Similarly, radiation can also suppress the expression of IL-6 via a miR-760 dependent pathway. Gain and loss of function studies confirmed that both HIF-1α and IL-6 were involved in the radiation suppressed proliferation of NSCLC cells. Collectively, our data showed that radiation can regulate the expression of miR-155-5p and miR-760 to suppress the malignancy of NSCLC cells. © 2019 BioFactors, 45(3):393-400, 2019.

Inhibition of miR-155 reduces impaired autophagy and improves prognosis in an experimental pancreatitis mouse model

Acute pancreatitis (AP) is a common digestive disease characterized by inflammation of the pancreas. MiR-155 plays a role in promoting inflammation and inhibiting the activation of anti-inflammatory pathways. Impaired autophagy could promote zymogen activation, abnormal acinar cell secretion, cell death, and the inflammatory response to aggravate AP. The aim of this study was to ascertain the effect of silencing miR-155 on AP through its effects on inflammation and impaired autophagy in vivo. In this study, AAV(adeno-associated virus)-mediated miR-155 and miR-155 sponge were injected through the tail vein of mice. After 3 weeks, AP was induced by intraperitoneal (IP) injections of cerulein. Pancreatic and pulmonary tissues were analyzed after 24 h. Silencing of miR-155 ameliorated pancreas and lung damage in three AP models of mice by preventing accumulation of autophagosomes that are unable to fuse with lysosomes and decreasing pancreatic inflammation by targeting TAB2. 3-MA could reduce the aberrant accumulation of autophagosomes, which alleviates the pancreas damage that was aggravated by increasing miR-155 levels. These findings demonstrate that the inhibition of miR-155 holds promise for limiting pancreatitis.

Rapamycin- and starvation-induced autophagy are associated with miRNA dysregulation in A549 cells

MicroRNAs (miRNAs) are short (20-23 nt) non-coding RNAs that are involved in post-transcriptional regulation of gene expression in multicellular organisms by affecting both the stability and translation of mRNAs. In recent years, deep sequencing of the transcription is being increasingly utilized with the promise of higher sensitivity for the identification of differential expression patterns as well as the opportunity to discover new transcripts, including new alternative isoforms and miRNAs. In this study, miRNAs from A549 cells treated with/without rapamycin or starvation were subject to genome-wide deep sequencing. A total of 1534 miRNAs were detected from the rapamycin- and starvation-treated A549 cells. Among them, 31 miRNAs were consistently upregulated and 131 miRNAs were downregulated in the treated cells when compared with the untreated cells. Gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis of the predicted target genes of the most significantly differentially expressed miRNAs revealed that the autophagy-related miRNAs are involved in cancer pathway. Taken together, our findings indicate that the underlying mechanism responsible for autophagy is associated with dysregulation of miRNAs in rapamycin- or starvation-induced A549 cells.

Identification of differentially expressed miRNAs in early-stage cervical cancer with lymph node metastasis across The Cancer Genome Atlas datasets

Background and aim

Previous studies have suggested that lymph node metastasis (LNM) in early-stage cervical cancer (CESC) may affect the prognosis of patients and the outcomes of subsequent adjuvant therapy. However, research focused on miRNA expression in early-stage CESC patients with LNM remains limited. Therefore, it is necessary to identify prognostic miRNAs and determine their molecular mechanisms.

Methods

We evaluated the differentially expressed genes in early-stage CESC patients with LNM compared to patients without LNM and evaluated the prognostic significance of these differentially expressed genes by analyzing a public dataset from The Cancer Genome Atlas. Potential molecular mechanisms were investigated by gene ontology, the Kyoto Encyclopedia of Genes and Genomes, and protein–protein interaction network analyses.

Results

According to the The Cancer Genome Atlas data, hsa-miR-508, hsa-miR-509-2, and hsa-miR-526b expression levels were significantly lower in early-stage CESC patients with LNM than in patients without LNM. A multivariate analysis suggested that three miRNAs were prognostic factors for CESC (P<0.05). The target genes were identified to be involved in the MAPK, cAMP, PI3K/Akt, mTOR, and estrogen cancer signaling pathways. Protein–protein interaction network analysis showed that TP53, MMP1, NOTCH1, SMAD4, and NFKB1 were the most significant hub proteins.

Conclusion

Our results indicate that hsa-miR-508, hsa-miR-509-2, and hsa-miR-526b may be potential diagnostic biomarkers for early-stage CESC with LNM, and serve as prognostic predictors for patients with CESC.

Modulation in the microRNA repertoire is responsible for the stage-specific effects of Akt suppression on murine neuroendocrine prostate cancer

Recent studies indicate a stage-specific, differential role for the oncogene Akt on various cancers. In prostate cancer (PCa), suppression of Akt activity in the advanced stages promoted transforming growth factor-β (TGFβ) pathway-mediated epithelial-to-mesenchymal transition (EMT) and metastasis to the lungs. In the current study, we performed Affymetrix analysis to compare the expression profile of microRNAs in the mouse prostate tissues collected at the prostatic inter-epithelial neoplasia (PIN) stage from Transgenic adenocarcinoma of the mouse (TRAMP)/Akt1^+/+ versus TRAMP/Akt1^–/– mice, and at the advanced stage from TRAMP/Akt1^+/+ mice treated with triciribine (Akt inhibitor) versus DMSO-treated control. Our analysis demonstrates that in the early stage, Akt1 in the TRAMP prostate tumors express a set of miRNAs responsible for regulating cancer cell survival, proliferation, and tumor growth, whereas, in the advanced stages, a different set of miRNAs that promote EMT and cancer metastasis is expressed. Our study has identified novel Akt-regulated signature microRNAs in the early and advanced PCa and demonstrates their differential effects on PCa growth and metastasis.

Human Papilloma Virus and Autophagy

Human papilloma viruses (HPVs) are a group of double-stranded DNA viruses known to be the primary cause of cervical cancer. In addition, evidence has now established their role in non-melanoma skin cancers, head and neck cancer (HNC), and the development of other anogenital malignancies. The prevalence of HPV-related HNC, in particular oropharyngeal cancers, is rapidly increasing, foreseeing that HPV-positive oropharyngeal cancers will outnumber uterine cervical cancers in the next 15–20 years. Therefore, despite the successful advent of vaccines originally licensed for cervical cancer prevention, HPV burden is still very high, and a better understanding of HPV biology is urgently needed. Autophagy is the physiological cellular route that accounts for removal, degradation, and recycling of damaged organelles, proteins, and lipids in lysosomal vacuoles. In addition to this scavenger function, autophagy plays a fundamental role during viral infections and cancers and is, therefore, frequently exploited by viruses to their own benefit. Recently, a link between HPV and autophagy has clearly emerged, leading to the conceivable development of novel anti-viral strategies aimed at restraining HPV infectivity. Here, recent findings on how oncogenic HPV16 usurp autophagy are described, highlighting similarities and differences with mechanisms adopted by other oncoviruses.