MiR-19a negatively regulated the expression of PTEN and promoted the growth of ovarian cancer cells

Correlation of PTEN signaling pathway and miRNA in breast cancer

Breast cancer (BC) is one of the most common cancers among women and can be fatal if not diagnosed and treated on time. Various genetic and environmental factors play a significant role in the development and progression of BC. Within the body, different signaling pathways have been identified that contribute to cancer progression, or conversely, cancer prevention. Phosphatase and tensin homolog (PTEN) is one of the proteins that prevent cancer by inhibiting the oncogenic PI3K/Akt/mTOR signaling pathway. MicroRNAs (miRNAs) are molecules with about 18 to 28 base pairs, which regulate about 30% of human genes after transcription. miRNAs play a key role in the progression or prevention of cancer through different signaling pathway and mechanisms, e.g., apoptosis, angiogenesis, and proliferation. miRNAs, which are upstream mediators of PTEN, can reinforce or suppress the effect of PTEN signaling on BC cells, and suppressing the PTEN signaling, linked to weakness of the cancer cells to chemotherapeutic drugs. However, the precise mechanism and function of miRNAs on PTEN in BC are not yet fully understood. Therefore, in the present study, has been focused on miRNAs regulating PTEN function in BC.

Decoding the interaction between miR-19a and CBX7 focusing on the implications for tumor suppression in cancer therapy

Cancer is a complex and multifaceted disease characterized by uncontrolled cell growth, genetic alterations, and disruption of normal cellular processes, leading to the formation of malignant tumors with potentially devastating consequences for patients. Molecular research is important in the diagnosis and treatment, one of the molecular mechanisms involved in various cancers is the fluctuation of gene expression. Non-coding RNAs, especially microRNAs, are involved in different stages of cancer. MicroRNAs are small RNA molecules that are naturally produced within cells and bind to the 3'-UTR of target mRNA, repressing gene expression by regulating translation. Overexpression of miR-19a has been reported in human malignancies. Upregulation of miR-19a as a member of the miR-17-92 cluster is key to tumor formation, cell proliferation, survival, invasion, metastasis, and drug resistance. Furthermore. bioinformatics and in vitro data reveal that the miR-19a-3p isoform binds to the 3'UTR of CBX7 and was identified as the miR-19a-3p target gene. CBX7 is known as a tumor suppressor. This review initially describes the regulation of mir-19a in multiple cancers. Accordingly, the roles of miR-19 in affecting its target gene expression CBX7 in carcinoma also be discussed.

Comparison of Oncogenes, Tumor Suppressors, and MicroRNAs Between Schizophrenia and Glioma: The Balance of Power

The risk of cancer in schizophrenia has been controversial. Confounders of the issue are cigarette smoking in schizophrenia, and antiproliferative effects of antipsychotic medications. The author has previously suggested comparison of a specific cancer like glioma to schizophrenia might help determine a more accurate relationship between cancer and schizophrenia. To accomplish this goal, the author performed three comparisons of data; the first a comparison of conventional tumor suppressors and oncogenes between schizophrenia and cancer including glioma. This comparison determined schizophrenia has both tumor-suppressive and tumor-promoting characteristics. A second, larger comparison between brain-expressed microRNAs in schizophrenia with their expression in glioma was then performed. This identified a core carcinogenic group of miRNAs in schizophrenia offset by a larger group of tumor-suppressive miRNAs. This proposed "balance of power" between oncogenes and tumor suppressors could cause neuroinflammation. This was assessed by a third comparison between schizophrenia, glioma and inflammation in asbestos-related lung cancer and mesothelioma (ALRCM). This revealed that schizophrenia shares more oncogenic similarity to ALRCM than glioma.

Hyperoside alleviates postmenopausal osteoporosis via regulating miR-19a-5p/IL-17A axis

PROBLEM

Postmenopausal osteoporosis (PMO) is a common osteoporosis. Hyperoside (Hyp), a natural flavonoid compound, has anti-osteoporotic effects, but the underlying mechanisms remain poorly understood. Inflammatory cytokine IL-17A is upregulated in PMO and plays vital roles in bone loss, but the upstream regulatory factors and mechanisms are still unknown.

METHOD OF STUDY

Twenty PMO patients and 20 healthy control subjects were included to analyze IL-17A expression changes and screen dys-regulated miRNAs in the peripheral blood of PMO patients. miR-19a-5p mimics and inhibitor were transfected into RAW264.7 osteoclasts, and injected into bilateral ovariectomized (OVX) mice to explore the regulatory effect of miR-19a-5p on IL-17A. OVX mice were randomly grouped and treated with different doses of Hyp to uncover the effective targets for the medicine in PMO disease.

RESULTS

MiR-19a-5p was downregulated in PMO patients and the expression level was negatively correlated with that of IL-17A. miR-19a-5p could directly bind to the 3'UTR of IL-17A and regulate its expression. Both in vitro and in vivo studies demonstrated that miR-19a-5p mimics decreased the expression of IL-17A, RANK and Cathepsin K, while miR-19a-5p inhibitor significantly increased the expression of IL-17A, RANK, and Cathepsin K. Importantly, the Hyp could improve bone structure of OVX mice by enhancing miR-19a-5p-mediated IL-17A downregulation.

CONCLUSION

Overall, these data demonstrated that miR-19a-5p/IL-17A axis might serve as novel therapeutic candidate for PMO. Hyp could relieve bone resorption by targeting the miR-19a-5p/IL-17A axis in OVX mice and exhibited prospective for the treatment of PMO.

A comprehensive investigation of histotype-specific microRNA and their variants in Stage I epithelial ovarian cancers

isomiRs, the sequence-variants of microRNA, are known to be tissue and cell type specific but their physiological role is largely unknown. In our study, we explored for the first time the expression of isomiRs across different Stage I epithelial ovarian cancer (EOC) histological subtypes, in order to shed new light on their biological role in tumor growth and progression. In a multicentric retrospective cohort of tumor biopsies (n = 215) we sequenced small RNAs finding 971 expressed miRNAs, 64% of which are isomiRs. Among them, 42 isomiRs showed a clear histotype specific pattern, confirming our previously identified miRNA markers (miR192/194 and miR30a-3p/5p for mucinous and clear cell subtypes, respectively) and uncovering new biomarkers for all the five subtypes. Using integrative models, we found that the 38% of these miRNA expression alterations is the result of copy number variations while the 17% of differential transcriptional activities. Our work represents the first attempt to characterize isomiRs expression in Stage I EOC within and across subtypes and to contextualize their alterations in the framework of the large genomic heterogeneity of this tumor.

Integrative analysis of circRNAs from Yangtze River Delta white goat neck skin tissue by high-throughput sequencing (circRNA-seq)

The Yangtze River Delta white goat is a unique goat species that can produce superior-quality brush hair. The formation of this brush hair is controlled by a series of critical genes and related signaling pathways. Circular RNAs (circRNAs), are ubiquitous endogenous non-coding RNAs that regulate many biological and physiological processes in mammals. However, little is known about the potential regulatory role of circRNAs on superior-quality brush hair formation in Yangtze River Delta white goat. In this study, high-throughput sequencing technology was used to only detect circRNAs in the neck skin tissue of normal-quality goats (NHQs) and superior-quality goats (HQs). A total of 61 803 circRNAs were identified and 32 of them were differentially expressed in the NHQ group vs. the HQ group. Functional enrichment analysis showed that the source gene of differentially expressed circRNAs (DE-circRNAs) was enriched mostly in platelet activation and the focal adhesion signal pathway. Action mechanism analysis revealed that DE-circRNAs could sponge to many identified miRNAs, including miR-31, miR-125b, miR-let-7a and miR-149-5p, which have important roles in goat hair follicle stem cell growth, hair follicle development and morphogenesis. Altogether, our findings provide a valuable basis for studying circRNAs involved in superior-quality brush hair traits and meanwhile advance our understanding of circRNA complex regulation mechanisms in Yangtze River Delta white goat skin hair follicle development.

MiR-149-5p promotes β-catenin-induced goat hair follicle stem cell differentiation

The Yangtze River Delta white goat is a unique goat species that can produce superior-quality brush hair. The formation of superior-quality brush hair cannot occur without goat hair follicle stem cell differentiation. However, knowledge regarding the regulatory role of miR-149-5p in hair follicle stem cell differentiation is limited. Here, we found that miR-149-5p is widely expressed in the tissues of Yangtze River Delta white goats, but its expression in the skin tissue of superior-quality brush hair goats is high compared to normal- quality goats. The functional studies showed that miR-149-5p overexpression markedly facilitated hair follicle stem cell differentiation, whereas inhibiting miR-149-5p inhibited hair follicle stem cell differentiation. These results more clearly elucidate the regulatory role of miR-149-5p in hair follicle stem cell growth.

Deregulated miRNA clusters in ovarian cancer: Imperative implications in personalized medicine

Ovarian cancer (OC) is one of the most common and fatal types of gynecological cancer. OC is usually detected at the advanced stages of the disease, making it highly lethal. miRNAs are single-stranded, small non-coding RNAs with an approximate size ranging around 22 nt. Interestingly, a considerable proportion of miRNAs are organized in clusters with miRNA genes placed adjacent to one another, getting transcribed together to result in miRNA clusters (MCs). MCs comprise two or more miRNAs that follow the same orientation during transcription. Abnormal expression of the miRNA cluster has been identified as one of the key drivers in OC. MC exists both as tumor-suppressive and oncogenic clusters and has a significant role in OC pathogenesis by facilitating cancer cells to acquire various hallmarks. The present review summarizes the regulation and biological function of MCs in OC. The review also highlights the utility of abnormally expressed MCs in the clinical management of OC.

Hypoxia Enhances Activity and Malignant Behaviors of Colorectal Cancer Cells through the STAT3/MicroRNA-19a/PTEN/PI3K/AKT Axis

Hypoxia is a typical microenvironment feature in almost all solid tumors and is frequently associated with growth of cancers including colorectal cancer (CRC). This study focuses on the influence of hypoxic microenvironment on the activity of CRC cells and the molecules involved. CRC cells were cultured under hypoxic conditions for 48 h, after which the proliferation, migration, invasion, and epithelial-mesenchymal transition activities of cells were increased. MicroRNA- (miR-) 19a was significantly upregulated in cells after hypoxia exposure according to a microarray analysis. STAT3 was confirmed as an upstream regulator of miR-19a which bound to the promoter region of miR-19a at the 96 bp/78 bp sites, and miR-19a bound to the PTEN mRNA to activate the PI3K/AKT signaling pathway. Hypoxia exposure induced STAT3 phosphorylation and PTEN knockdown in CRC cells. Silencing of STAT3 reduced the hypoxia-induced activity of CRC cells, whereas the malignant behaviors of cells were restored after miR-19a upregulation but blocked after PTEN overexpression. Similar results were reproduced in vivo where downregulation of STAT3 or overexpression of PTEN suppressed tumor growth and metastasis in nude mice. This study demonstrated that hypoxia augments activity and malignant behaviors of colorectal cancer cells through the STAT3/miR-19a/PTEN/PI3K/AKT axis.

Exosomal miR-19a and IBSP cooperate to induce osteolytic bone metastasis of estrogen receptor-positive breast cancer

Bone metastasis is an incurable complication of breast cancer. In advanced stages, patients with estrogen-positive tumors experience a significantly higher incidence of bone metastasis (>87%) compared to estrogen-negative patients (<56%). To understand the mechanism of this bone-tropism of ER+ tumor, and to identify liquid biopsy biomarkers for patients with high risk of bone metastasis, the secreted extracellular vesicles and cytokines from bone-tropic breast cancer cells are examined in this study. Both exosomal miR-19a and Integrin-Binding Sialoprotein (IBSP) are found to be significantly upregulated and secreted from bone-tropic ER+ breast cancer cells, increasing their levels in the circulation of patients. IBSP is found to attract osteoclast cells and create an osteoclast-enriched environment in the bone, assisting the delivery of exosomal miR-19a to osteoclast to induce osteoclastogenesis. Our findings reveal a mechanism by which ER+ breast cancer cells create a microenvironment favorable for colonization in the bone. These two secreted factors can also serve as effective biomarkers for ER+ breast cancer to predict their risks of bone metastasis. Furthermore, our screening of a natural compound library identifies chlorogenic acid as a potent inhibitor for IBSP-receptor binding to suppress bone metastasis of ER+ tumor, suggesting its preventive use for bone recurrence in ER+ patients.

GATA6-AS1 inhibits ovarian cancer cell proliferation and migratory and invasive abilities by sponging miR-19a-5p and upregulating TET2

GATA6 antisense RNA 1 (GATA6-AS1) has been reported to be involved in the progression of several types of cancer. In the present study, the role of GATA6-AS1 in ovarian cancer (OC) was explored. Reverse transcription quantitative PCR was used to detect the expression of GATA6-AS1, microRNA (miR)-19a-5p and tet methylcytosine dioxygenase 2 (TET2) in OC and adjacent normal tissues. Furthermore, OC cells with GATA-AS1 either knocked down or overexpressed were established. The Cell Counting Kit-8 assay was used to evaluate cell proliferation and a Transwell assay was used to assess the migratory and invasive abilities of OC cells. A dual luciferase reporter gene assay was used to determine whether GATA6-AS1 and miR-19a-5p, and miR-19a-5p and TET2, may interact with each other. The results demonstrated that GATA6-AS1 expression level was decreased in OC tissues and cells compared with control groups. In addition, GATA6-AS1 overexpression significantly inhibited the proliferation and migratory and invasive abilities of OC cells, whereas GATA6-AS1 downregulation had the opposite effects. Furthermore, GATA6-AS1 adsorbed miR-19a-5p to repress its expression and GTA6-AS1 indirectly upregulated TET2 expression. Taken together, the findings from this study suggested that GATA6-AS1 could inhibit the proliferation and migratory and invasive abilities of OC cells via regulation of the miR-19a-5p/TET2 axis.

Role of miRNA-19a in Cancer Diagnosis and Poor Prognosis

Cancer is a multifactorial disease that affects millions of people every year and is one of the most common causes of death in the world. The high mortality rate is very often linked to late diagnosis; in fact, nowadays there are a lack of efficient and specific markers for the early diagnosis and prognosis of cancer. In recent years, the discovery of new diagnostic markers, including microRNAs (miRNAs), has been an important turning point for cancer research. miRNAs are small, endogenous, non-coding RNAs that regulate gene expression. Compelling evidence has showed that many miRNAs are aberrantly expressed in human carcinomas and can act with either tumor-promoting or tumor-suppressing functions. miR-19a is one of the most investigated miRNAs, whose dysregulated expression is involved in different types of tumors and has been potentially associated with the prognosis of cancer patients. The aim of this review is to investigate the role of miR-19a in cancer, highlighting its involvement in cell proliferation, cell growth, cell death, tissue invasion and migration, as well as in angiogenesis. On these bases, miR-19a could prove to be truly useful as a potential diagnostic, prognostic, and therapeutic marker.

Identification of the miRNA signature associated with survival in patients with ovarian cancer

Ovarian cancer is a major gynaecological malignant tumor associated with a high mortality rate. Identifying survival-related variants may improve treatment and survival in patients with ovarian cancer. In this work, we proposed a support vector regression (SVR)-based method called OV-SURV, which is incorporated with an inheritable bi-objective combinatorial genetic algorithm for feature selection to identify a miRNA signature associated with survival in patients with ovarian cancer. There were 209 patients with miRNA expression profiles and survival information of ovarian cancer retrieved from The Cancer Genome Atlas database. OV-SURV achieved a mean correlation coefficient of 0.77±0.01and a mean absolute error of 0.69±0.02 years using 10-fold cross-validation. Analysis of the top ranked miRNAs revealed that the miRNAs, hsa-let-7f, hsa-miR-1237, hsa-miR-98, hsa-miR-933, and hsa-miR-889, were significantly associated with the survival in patients with ovarian cancer. Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed that four of these miRNAs, hsa-miR-182, hsa-miR-34a, hsa-miR-342, and hsa-miR-1304, were highly enriched in fatty acid biosynthesis, and the five miRNAs, hsa-let-7f, hsa-miR-34a, hsa-miR-342, hsa-miR-1304, and hsa-miR-24, were highly enriched in fatty acid metabolism. The prediction model with the identified miRNA signature consisting of prognostic biomarkers can benefit therapeutic decision making of ovarian cancer.

Silencing MAP3K1 expression inhibits the proliferation of goat hair follicle stem cells

The Yangtze River Delta White Goat is the only goat breed in the world that can produce superior-quality brush hair. Previous studies have shown that some genes are expressed differentially in the skin tissues between the goats produced superior-quality and normal-quality brush hair. Studies also have shown that different gene play varied roles in regulating the proliferation and apoptosis of hair follicle stem cells. However, the biological function of MAP3K1 (mitogen-activated protein kinase kinase kinase 1) gene in hair follicle stem cells is not fully understood. This study aims to investigate the role of MAP3K1 knockdown during the proliferation and apoptosis of hair follicle stem cells. RT-qPCR and Western blot were used to detect mRNA gene and protein expression level, CCK-8 and EdU assays were used to detect cell proliferation, and cell cycle and apoptosis were detected by flow cytometry. The results showed that the MAP3K1 expression level was significantly higher in the skin tissue of produced superior-quality brush hair than that in produced normal-quality brush hair. Moreover, functional studies indicated that si-MAP3K1 significantly inhibits the proliferation of hair follicle stem cells that came from a superior goat and promotes its apoptosis. Based on aforementioned assays, we speculated that MAP3K1 might play a regulatory effect in superior-quality brush hair traits.

Gynecologic cancers and non-coding RNAs: Epigenetic regulators with emerging roles

Gynecologic cancers involve the female genital organs, such as the vulva, vagina, cervix, endometrium, ovaries, and fallopian tubes. The occurrence and frequency of gynecologic cancer depends on personal lifestyle, history of exposure to viruses or carcinogens, genetics, body shape, and geographical habitat. For a long time, research into the molecular biology of cancer was broadly restricted to protein-coding genes. Recently it has been realized that non-coding RNAs (ncRNA), including long noncoding RNAs (LncRNAs), microRNAs, circular RNAs and piRNAs (PIWI-interacting RNAs), can all play a role in the regulation of cellular function within gynecological cancer. It is now known that ncRNAs are able to play dual roles, i.e. can exert both oncogenic or tumor suppressive functions in gynecological cancer. Moreover, several clinical trials are underway looking at the biomarker and therapeutic roles of ncRNAs. These efforts may provide a new horizon for the diagnosis and treatment of gynecological cancer. Herein, we summarize some of the ncRNAs that have been shown to be important in gynecological cancers.

MicroRNA-196b promotes cell growth and metastasis of ovarian cancer by targeting ZMYND11

BACKGROUND

The purpose of this study was to explore the mechanism by which microRNA-196b exerts a tumor promotion effect on ovarian cancer (OCa).

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to examine the expression of microRNA-196b in 60 pairs of tumor samples and paracancerous ones collected from patients with ovarian cancer, meanwhile, microRNA-196b expression in human ovarian cancer cell lines and normal ovarian epithelial cell lines were also analyzed by qRT-PCR. Bioinformatics methods suggested that ZMYND11 was predicted the target gene of microRNA-196b and its binding relationship was verified by dual luciferase reporter gene experiment. Then cell counting kit (CCK-8) and 5-Ethynyl-2'- deoxyuridine (EdU) assay were performed to analyze the influence of microRNA-196b overexpression on OCa cell proliferation.

RESULTS

QRT-PCR results showed that microRNA-196b level in OCa tissues was remarkably higher than that in normal ovarian tissues, which was closely relevant to the poor prognosis of tumors. The dual luciferase reporter gene experiments confirmed that microRNA-196b could directly bind to the 3'-UTR of ZMYND11. Overexpression of microRNA-196b remarkably enhanced the proliferation, invasiveness and migratory ability of OCa cells. Meanwhile, overexpression of microRNA-196b significantly decreased ZMYND11 mRNA and protein expression. In addition, ZMYND11 level was also significantly increased in ovarian cancer cells. Compared with the miRNA-NC group, microRNA-196b-mimics + ZMYND11-OE treatment reversed the effect of microRNA-196b-mimics on OCa cell functions.

CONCLUSIONS

MicroRNA-196b was highly expressed in OCa tissues, which can promote the proliferation, invasiveness and migratory ability of OCa cells by targeting ZMYND11. In addition, the expression disorder of microRNA-196b was associated with the malignant development of OCa.

MiR-19a enhances cell proliferation, migration, and invasiveness through enhancing lymphangiogenesis by targeting thrombospondin-1 in colorectal cancer

Colorectal cancer (CRC) is a devastating disease with high mortality and morbidity, and the underlying mechanisms of miR-19a in CRC are poorly understood. In our study, dual-luciferase reporter assays were used to evaluate the binding of miR-19a with thrombospondin-1 (THBS1). Cell viability, migration, and invasiveness were assessed using MTT, wound healing, and Transwell assays, respectively. Tube-formation assays with human lymphatic endothelial cells (HLECs) were used to evaluate lymphangiogenesis, and tumor xenograft assays were used to measure tumor growth. The results showed that miR-19a was up-regulated and THBS1 was down-regulated in CRC tissues and cells. Applying an inhibitor of miR-19a suppressed survival, migration, and invasiveness, and inhibited the expression of matrix metallopeptidase 9 (MMP-9) and vascular endothelial growth factor C (VEGFC). Further mechanistic study identified that THBS1 is a direct target of miR-19a. THBS1 silencing attenuated the above-mentioned suppressive effects induced with the miR-19a inhibitor. Furthermore, the miR-19a inhibitor suppressed the migration and tube-formation abilities of HLECs via targeting the THBS1–MMP-9/VEGFC signaling pathway. And the inhibition of miR-19a also suppressed tumor growth and lymphatic tube formation in vivo. In conclusion, miR-19a inhibition suppresses the viability, migration, and invasiveness of CRC cells, and suppresses the migration and tube-formation abilities of HLECs, and further, inhibits tumor growth and lymphatic tube formation in vivo via targeting THBS1.

MiR-19a modulates hypoxia-mediated cell proliferation and migration via repressing PTEN in human pulmonary arterial smooth muscle

AIM

The dysfunction of human pulmonary arterial smooth muscle cells (HPASMCs) has been suggested to participate in the pathophysiology of pulmonary arterial hypertension (PAH). This study determined miR-19a expression in hypoxia-induced HPASMCs and explored the mechanistic actions of miR-19a in hypoxia-induced HPASMC proliferation and migration.

METHODS

QRT-PCR and western blot assays respectively determined the mRNA and protein expression of miR-19a, phosphatase and tensin homolog (PTEN) and hypoxia-inducible factor-1 alpha (HIF-1α). In vitro functional assays determined HPASMC proliferation and migration, respectively. Luciferase reporter assay determined interaction between miR-19a and PTEN. The knockdown effects of miR-19a on PAH were confirmed in in vivo mice model.

RESULTS

Hypoxia treatment time-dependently up-regulated miR-19a expression and enhanced cell proliferation in HPASMCs. MiR-19a overexpression increased cell proliferation and migration of HPASMCs, while repression of miR-19a reduced cell proliferative and migratory potentials of hypoxia-treated HPASMCs. Bioinformatics analysis and luciferase reporter assay showed that PTEN 3' untranslated region was targeted by miR-19a, and miR-19a repressed the mRNA and protein expression of PTEN in HPASMCs. Further rescue studies revealed that miR-19a regulated proliferative and migratory potentials of hypoxia-treated HPASMCs via suppressing PTEN expression. In addition, HIF-1α was identified as one of the mediators for the hypoxia-induced aberrant expression levels of miR-19a and PTEN. MiR-19a overexpression enhanced PI3K/AKT signaling, which was attenuated by enforced expression of PTEN in HPASMCs. More importantly, knockdown of miR-19 attenuated the chronic hypoxia-induced PAH in in vivo mice model.

CONCLUSION

This study presented a novel mechanistic action of miR-19a-mediated cell proliferation and migration of HPASMCs.

The NF-κB-modulated miR-19a-3p enhances malignancy of human ovarian cancer cells through inhibition of IGFBP-3 expression

Ovarian cancer is the most lethal gynecologic malignancy due to the lack of symptoms until advanced stages, and new diagnosis and treatment strategy is in urgent need. In this study, we found higher expression of miR-19a-3p in ovarian cancer tissues compared with that in the adjacent normal tissues. By chromatin immunoprecipitation (ChIP) and electrophoretic mobility shift assay (EMSA) analysis, we showed that nuclear factor-kappaB (NF-κB) binds to the promoter of miR-19a-3p, leading to reduced expression in ovarian cancer cells. Further study indicated that miR-19a-3p inhibits the expression of insulin-like growth factor binding protein-3 (IGFBP-3), resulting in enhanced growth and migration of ovarian cancer cells in vitro and tumor growth in vivo. These results showed that miR-19a-3p enhances the oncogenesis of ovarian cancer through inhibition of IGFBP-3 expression, and which can be inhibited by NF-κB, suggesting an NF-κB/miR-19a-3p/IGFBP-3 pathway in the oncogenesis of ovarian cancer, which expands our understanding of ovarian cancer and they may contribute to the development of new diagnosis and treatment of ovarian cancer.

PTEN Alterations as a Potential Mechanism for Tumor Cell Escape from PD-1/PD-L1 Inhibition

The recent approval of immune checkpoint inhibitors drastically changed the standard treatments in many advanced cancer patients, but molecular changes within the tumor can prevent the activity of immunotherapy drugs. Thus, the introduction of the inhibitors of the immune checkpoint programmed death-1/programmed death ligand-1 (PD-1/PD-L1), should prompt deeper studies on resistance mechanisms, which can be caused by oncogenic mutations detected in cancer cells. PTEN, a tumor suppressor gene, dephosphorylates the lipid signaling intermediate PIP₃ with inhibition of AKT activity, one of the main effectors of the PI3K signaling axis. As a consequence of genetic or epigenetic aberrations, PTEN expression is often altered, with increased activation of PI3K axis. Interestingly, some data confirmed that loss of PTEN expression modified the pattern of cytokine secretion creating an immune-suppressive microenvironment with increase of immune cell populations that can promote tumor progression. Moreover, PTEN loss may be ascribed to reduction of tumor infiltrating lymphocytes (TILs), which can explain the absence of activity of immune checkpoint inhibitors. This review describes the role of PTEN loss as a mechanism responsible for resistance to anti PD-1/PD-L1 treatment. Moreover, combinatorial strategies between PD-1/PD-L1 inhibitors and PI3K/AKT targeting drugs are proposed as a new strategy to overcome resistance to immune checkpoint inhibition.

MicroRNA biogenesis, gene silencing mechanisms and role in breast, ovarian and prostate cancer

Micro-ribonucleic acids (miRNAs) are important class of short regulatory RNA molecules involved in regulation of several essential biological processes. In addition to Dicer and Drosha, over the past few years several other gene products are discovered that regulates miRNA biogenesis pathways. Similarly, various models of molecular mechanisms underlying miRNA mediated gene silencing have been uncovered through which miRNA contribute in diverse physiological and pathological processes. Dysregulated miRNA expression has been reported in many cancers manifesting tumor suppressive or oncogenic role. In this review, critical overview of recent findings in miRNA biogenesis, silencing mechanisms and specifically the role of miRNA in breast, ovarian and prostate cancer will be described. Recent advancements in miRNA research summarized in this review will enhance the molecular understanding of miRNA biogenesis and mechanism of action. Also, role of miRNAs in pathogenesis of breast, ovarian and prostate cancer will provide the insights for the use of miRNAs as biomarker or therapeutic agents for the cancers.

miR-3691-5p promotes hepatocellular carcinoma cell migration and invasion through activating PI3K/Akt signaling by targeting PTEN

Background: The enhanced ability of cancer metastasis is the major cause for the cancer-related death of hepatocellular carcinoma (HCC). Better understanding the mechanisms for the motility of cancer cells will benefit the treatment. Accumulating evidence suggests that aberrant microRNA (miRNA) expression contributes to HCC development and progression, whereas miR-3691-5p has not been reported in HCC.

Purpose: The aim of this study was to elucidate the expression, function and mechanism of miR-3691-5p in HCC.

Methods: Real-time quantitative polymerase chain reaction (qPCR) was performed to detect miR-3691-5p expression in HCC tissues and cell lines database analysis were conducted for detection of the expression of miR-3691-5p in HCC. Then, the association of miR-3691-5p with clinicopathological features of HCC patients were statistically measured. Subsequently, we attempted to observe the effects of miR-3691-5p on migration and invasion of HCC cells by transwell assays. Furthermore, bioinformatics tools and luciferase reporter gene assay as well as recuse experiments were conducted to explore the target of miR-3691-5p in HCC, and to explore whether the target mediated the effects of miR-3691-5p HCC cells.

Results: In the current study, we found that miR-3691-5p expression was elevated in both HCC tissues and cell lines, which was significantly correlated with poor prognosis and clinicopathological features including TNM stage (P=0.016) and vascular invasion (P=0.016). Furthermore, gain-or loss-of function assays demonstrated that miR-3691-5p promoted HCC cell migration and invasion. Luciferase reporter assay confirmed that PTEN was a direct downstream target of miR-3691-5p. Recuse assays showed that restoration of PTEN reversed the effects of miR-3691-5p on HCC cell migration and invasion through decreasing PI3K/Akt signaling.

Conclusion: Our results demonstrated that miR-3691-5p contributes to HCC cell migration and invasion through activating PI3K/Akt signaling by targeting PTEN.

Mechanisms of PTEN loss in cancer: It's all about diversity

PTEN is a phosphatase which metabolises PIP₃, the lipid product of PI 3-Kinase, directly opposing the activation of the oncogenic PI3K/AKT/mTOR signalling network. Accordingly, loss of function of the PTEN tumour suppressor is one of the most common events observed in many types of cancer. Although the mechanisms by which PTEN function is disrupted are diverse, the most frequently observed events are deletion of a single gene copy of PTEN and gene silencing, usually observed in tumours with little or no PTEN protein detectable by immunohistochemistry. Accordingly, with the exceptions of glioblastoma and endometrial cancer, mutations of the PTEN coding sequence are uncommon (<10%) in most types of cancer. Here we review the data relating to PTEN loss in seven common tumour types and discuss mechanisms of PTEN regulation, some of which appear to contribute to reduced PTEN protein levels in cancers.

MiR-19a Overexpression in FTC-133 Cell Line Induces a More De-Differentiated and Aggressive Phenotype

In recent years, microRNAs (miRNAs) have received increasing attention for their important role in tumor initiation and progression. MiRNAs are a class of endogenous small non-coding RNAs that negatively regulate the expression of several oncogenes or tumor suppressor genes. MiR-19a, a component of the oncogenic miR-17-92 cluster, has been reported to be highly expressed only in anaplastic thyroid cancer, the most undifferentiated, aggressive and lethal form of thyroid neoplasia. In this work, we evaluated the putative contribution of miR-19a in de-differentiation and aggressiveness of thyroid tumors. To this aim, we induced miR-19a expression in the well-differentiated follicular thyroid cancer cell line and evaluated proliferation, apoptosis and gene expression profile of cancer cells. Our results showed that miR-19a overexpression stimulates cell proliferation and alters the expression profile of genes related to thyroid cell differentiation and aggressiveness. These findings not only suggest that miR-19a has a possible involvement in de-differentiation and malignancy, but also that it could represent an important prognostic indicator and a good therapeutic target for the most aggressive thyroid cancer.