Cyclin G1 expands liver tumor-initiating cells by Sox2 induction via Akt/mTOR signaling

Dissecting SOX2 expression and function reveals an association with multiple signaling pathways during embryonic development and in cancer progression

SRY (Sex Determining Region) box 2 (SOX2) is an essential transcription factor that plays crucial roles in activating genes involved in pre- and post-embryonic development, adult tissue homeostasis, and lineage specifications. SOX2 maintains the self-renewal property of stem cells and is involved in the generation of induced pluripotency stem cells. SOX2 protein contains a particular high-mobility group domain that enables SOX2 to achieve the capacity to participate in a broad variety of functions. The information about the involvement of SOX2 with gene regulatory elements, signaling networks, and microRNA is gradually emerging, and the higher expression of SOX2 is functionally relevant to various cancer types. SOX2 facilitates the oncogenic phenotype via cellular proliferation and enhancement of invasive tumor properties. Evidence are accumulating in favor of three dimensional (higher order) folding of chromatin and epigenetic control of the SOX2 gene by chromatin modifications, which implies that the expression level of SOX2 can be modulated by epigenetic regulatory mechanisms, specifically, via DNA methylation and histone H3 modification. In view of this, and to focus further insights into the roles SOX2 plays in physiological functions, involvement of SOX2 during development, precisely, the advances of our knowledge in pre- and post-embryonic development, and interactions of SOX2 in this scenario with various signaling pathways in tumor development and cancer progression, its potential as a therapeutic target against many cancers are summarized and discussed in this article.

SOX2-associated signaling pathways regulate biological phenotypes of cancers

SOX2 is a transcription factor involved in multiple stages of embryonic development. In related reports, SOX2 was found to be abnormally expressed in tumor tissues and correlated with clinical features such as TNM staging, tumor grade, and prognosis in patients with various cancer types. In most cancer types, SOX2 is a tumor-promoting factor that regulates tumor progression and metastasis primarily by maintaining the stemness of cancer cells. In addition, SOX2 also regulates the proliferation, apoptosis, invasion, migration, ferroptosis and drug resistance of cancer cells. However, SOX2 acts as a tumor suppressor in some cases in certain cancer types, such as gastric and lung cancer. These key regulatory functions of SOX2 involve complex regulatory networks, including protein-protein and protein-nucleic acid interactions through signaling pathways and noncoding RNA interactions, modulating SOX2 expression may be a potential therapeutic strategy for clinical cancer patients. Therefore, we sorted out the phenotypes related to SOX2 in cancer, hoping to provide a basis for further clinical translation.

Signaling pathways in the regulation of cancer stem cells and associated targeted therapy

Cancer stem cells (CSCs) are defined as a subpopulation of malignant tumor cells with selective capacities for tumor initiation, self-renewal, metastasis, and unlimited growth into bulks, which are believed as a major cause of progressive tumor phenotypes, including recurrence, metastasis, and treatment failure. A number of signaling pathways are involved in the maintenance of stem cell properties and survival of CSCs, including well-established intrinsic pathways, such as the Notch, Wnt, and Hedgehog signaling, and extrinsic pathways, such as the vascular microenvironment and tumor-associated immune cells. There is also intricate crosstalk between these signal cascades and other oncogenic pathways. Thus, targeting pathway molecules that regulate CSCs provides a new option for the treatment of therapy-resistant or -refractory tumors. These treatments include small molecule inhibitors, monoclonal antibodies that target key signaling in CSCs, as well as CSC-directed immunotherapies that harness the immune systems to target CSCs. This review aims to provide an overview of the regulating networks and their immune interactions involved in CSC development. We also address the update on the development of CSC-directed therapeutics, with a special focus on those with application approval or under clinical evaluation.

Different Inhibition of Nrf2 by Two Keap1 Isoforms α and β to Shape Malignant Behaviour of Human Hepatocellular Carcinoma

Nrf2 (nuclear factor E2-related factor 2, encoded by Nfe2l2) acts as a master transcriptional regulator in mediating antioxidant, detoxification, and cytoprotective responses against oxidative, electrophilic, and metabolic stress, but also plays a crucial role in cancer metabolism and multiple oncogenic pathways, whereas the redox sensor Keap1 functions as a predominant inhibitor of Nrf2 and, hence, changes in its expression abundance directly affect the Nrf2 stability and transcriptional activity. However, nuanced functional isoforms of Keap1 α and β have rarely been identified to date. Herein, we have established four distinct cell models stably expressing Keap1^-/-, Keap1β(Keap1^Δ1-31), Keap1-Restored, and Keap1α-Restored aiming to gain a better understanding of similarities and differences of two Keap1 isoforms between their distinct regulatory profiles. Our experimental evidence revealed that although Keap1 and its isoforms are still localized in the cytoplasmic compartments, they elicited differential inhibitory effects on Nrf2 and its target HO-1. Furthermore, transcriptome sequencing unraveled that they possess similar but different functions. Such functions were further determined by multiple experiments in vivo (i.e., subcutaneous tumour formation in nude mice) and in vitro (e.g., cell cloning, infection, migration, wound healing, cell cycle, apoptosis, CAT enzymatic activity, and intracellular GSH levels). Of note, the results obtained from tumourigenesis experiments in xenograft model mice were verified based on the prominent changes in the PTEN signaling to the PI3K-AKT-mTOR pathways, in addition to substantially aberrant expression patterns of those typical genes involved in the EMT (epithelial-mesenchymal transition), cell cycle, and apoptosis.

De novo identification of maximally deregulated subnetworks based on multi-omics data with DeRegNet

Background

With a growing amount of (multi-)omics data being available, the extraction of knowledge from these datasets is still a difficult problem. Classical enrichment-style analyses require predefined pathways or gene sets that are tested for significant deregulation to assess whether the pathway is functionally involved in the biological process under study. De novo identification of these pathways can reduce the bias inherent in predefined pathways or gene sets. At the same time, the definition and efficient identification of these pathways de novo from large biological networks is a challenging problem.

Results

We present a novel algorithm, DeRegNet, for the identification of maximally deregulated subnetworks on directed graphs based on deregulation scores derived from (multi-)omics data. DeRegNet can be interpreted as maximum likelihood estimation given a certain probabilistic model for de-novo subgraph identification. We use fractional integer programming to solve the resulting combinatorial optimization problem. We can show that the approach outperforms related algorithms on simulated data with known ground truths. On a publicly available liver cancer dataset we can show that DeRegNet can identify biologically meaningful subgraphs suitable for patient stratification. DeRegNet can also be used to find explicitly multi-omics subgraphs which we demonstrate by presenting subgraphs with consistent methylation-transcription patterns. DeRegNet is freely available as open-source software.

Conclusion

The proposed algorithmic framework and its available implementation can serve as a valuable heuristic hypothesis generation tool contextualizing omics data within biomolecular networks.

Advance of SOX Transcription Factors in Hepatocellular Carcinoma: From Role, Tumor Immune Relevance to Targeted Therapy

Simple Summary

Hepatocellular carcinoma (HCC) is one of the deadliest human health burdens worldwide. However, the molecular mechanism of HCC development is still not fully understood. Sex determining region Y-related high-mobility group box (SOX) transcription factors not only play pivotal roles in cell fate decisions during development but also participate in the initiation and progression of cancer. Given the significance of SOX factors in cancer and their ‘undruggable’ properties, we summarize the role and molecular mechanism of SOX family members in HCC and the regulatory effect of SOX factors in the tumor immune microenvironment (TIME) of various cancers. For the first time, we analyze the association between the levels of SOX factors and that of immune components in HCC, providing clues to the pivotal role of SOX factors in the TIME of HCC. We also discuss the opportunities and challenges of targeting SOX factors for cancer.

Abstract

Sex determining region Y (SRY)-related high-mobility group (HMG) box (SOX) factors belong to an evolutionarily conserved family of transcription factors that play essential roles in cell fate decisions involving numerous developmental processes. In recent years, the significance of SOX factors in the initiation and progression of cancers has been gradually revealed, and they act as potential therapeutic targets for cancer. However, the research involving SOX factors is still preliminary, given that their effects in some leading-edge fields such as tumor immune microenvironment (TIME) remain obscure. More importantly, as a class of ‘undruggable’ molecules, targeting SOX factors still face considerable challenges in achieving clinical translation. Here, we mainly focus on the roles and regulatory mechanisms of SOX family members in hepatocellular carcinoma (HCC), one of the fatal human health burdens worldwide. We then detail the role of SOX members in remodeling TIME and analyze the association between SOX members and immune components in HCC for the first time. In addition, we emphasize several alternative strategies involved in the translational advances of SOX members in cancer. Finally, we discuss the alternative strategies of targeting SOX family for cancer and propose the opportunities and challenges they face based on the current accumulated studies and our understanding.

The synergistic antitumor effect of IL-6 neutralization with NVP-BEZ235 in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) still ranks among the top cancers worldwide with high incidence and mortality. Due to abnormal activation of the PI3K/AKT/mTOR signalling pathway in HCC, targeting this pathway represents a potential therapeutic strategy. NVP-BEZ235 is a novel dual-targeted ATP-competitive PI3K/mTOR inhibitor that has shown effective antitumor effects. In this study, we found that interleukin-6 (IL-6) was significantly increased after exposure to NVP-BEZ235, and we proposed a treatment in which an anti-IL-6 antibody was combined with NVP-BEZ235 for HCC. In vitro results revealed that targeted inhibition of IL-6 potentiated the antitumor effects of NVP-BEZ235 in HCC cells. The mechanism might be attributed to their synergistic inhibitory activity on the PI3K/AKT/mTOR signalling pathway. Furthermore, an in vivo study demonstrated that combined administration of NVP-BEZ235 and anti-IL-6 Ab reduced HCC tumour load more effectively than either NVP-BEZ235 or anti-IL-6 Ab treatment alone. These findings add guidance value to the analysis of HCC and provide a reference for clinical treatment.

Atypical cyclin P regulates cancer cell stemness through activation of the WNT pathway

PURPOSE

Cancer stem cells represent a cancer cell subpopulation that has been found to be associated with metastasis and chemoresistance. Therefore, it is vital to identify mechanisms regulating cancer stemness. Previously, we have shown that the atypical cyclin P (CCNP), also known as CNTD2, is upregulated in lung and colorectal cancers and is associated with a worse clinical prognosis. Given that other cyclins have been implicated in pluripotency regulation, we hypothesized that CCNP may also play a role in cancer stemness.

METHODS

Cell line-derived spheroids, ex vivo intestinal organoid cultures and induced-pluripotent stem cells (iPSCs) were used to investigate the role of CCNP in stemness. The effects of CCNP on cancer cell stemness and the expression of pluripotency markers and ATP-binding cassette (ABC) transporters were evaluated using Western blotting and RT-qPCR assays. Cell viability was assessed using a MTT assay. The effects of CCNP on WNT targets were monitored by RNA-seq analysis. Data from publicly available web-based resources were also analyzed.

RESULTS

We found that CCNP increases spheroid formation in breast, lung and colorectal cancers, and upregulates the expression of stemness (CD44, CD133) and pluripotency (SOX2, OCT4, NANOG) markers. In addition, we found that CCNP promotes resistance to anticancer drugs and induces the expression of multidrug resistance ABC transporters. Our RNA-seq data indicate that CCNP activates the WNT pathway, and that inhibition of this pathway abrogates the increase in spheroid formation promoted by CCNP. Finally, we found that CCNP knockout decreases OCT4 expression in iPSCs, further supporting the notion that CCNP is involved in stemness regulation.

CONCLUSION

Our results reveal CCNP as a novel player in stemness and as a potential therapeutic target in cancer.

Transcription factor SOX2 contributes to nonalcoholic fatty liver disease development by regulating the expression of the fatty acid transporter CD36

Nonalcoholic fatty liver disease (NAFLD) can lead to hepatocellular carcinoma (HCC). The level of the transcription factor SOX2 correlates with HCC progression, but its role in fat accumulation remains unclear. Here, a high-fat diet, with and without fructose, significantly upregulated SOX2 in murine liver tissue. Treatment with free fatty acids (FFAs) and fructose upregulated SOX2 in murine FL83B hepatocytes. SOX2 overexpression or knockdown regulated triglyceride synthesis and lipid accumulation after FFA stimulation. CD36, a fatty acid transporter, and Yes-associated protein (YAP), a downstream molecule of the Hippo signaling pathway, were upregulated by FFA/fructose in vivo and in vitro. Transcriptional regulation of CD36 by SOX2 suggested the involvement of CD36 in SOX2-mediated hepatic steatosis. Thus, SOX2 may be a target to prevent NAFLD development.

How can we turn the PI3K/AKT/mTOR pathway down? Insights into inhibition and treatment of cancer

Introduction: The phosphatidylinositol 3-kinase/protein kinase-B/mammalian target of rapamycin (PI3K/AKT/mTOR) pathway is a fundamental regulator of cell proliferation and survival. Dysregulation in this pathway leads to the development of cancer. Accumulating evidence indicates that dysregulation in this pathway is involved in cancer initiation, progression, and recurrence. However, the pathway consists of various signal transducing factors related with cellular events, such as transformation, tumorigenesis, cancer progression, and drug resistance. Therefore, it is very important to determine the targets in this pathway for cancer therapy. Although many drugs inhibiting this signaling pathway are in clinical trials or have been approved for treating solid tumors and hematologic malignancies, further understanding of the signaling mechanism is required to achieve better therapeutic efficacy.Areas covered: In this review, we have describe the PI3K/AKT/mTOR pathway in detail, along with its critical role in cancer stem cells, for identifying potential therapeutic targets. We also summarize the recent developments in different types of signaling inhibitors.Expert opinion: Downregulation of the PI3K/AKT/mTOR pathway is very important for treating all types of cancers. Thus, further studies are required to establish novel prognostic factors to support the current progress in cancer treatment with emphasis on this pathway.

Silencing the Expression of Cyclin G1 Enhances the Radiosensitivity of Hepatocellular Carcinoma In Vitro and In Vivo by Inducing Apoptosis

Radiotherapy plays an important role in the treatment of hepatocellular carcinoma (HCC). Cyclin G1 is a novel member of the cyclin family, and it is abnormally expressed in HCC. In this study we investigated the role of cyclin G1 in the radiotherapy of HCC cells. The expression of cyclin G1 was silenced by transfection of cyclin G1-siRNA into HepG2 cells and Huh7 cells, and the expression of cyclin G1 mRNA and protein was measured by qRT-PCR and Western blot analysis. The proliferation was analyzed using MTT assay, and the radiosensitivity of HCC cells was detected using colony formation assay and a xenograft tumor model. The expression of apoptosis-related proteins (Bcl-2 and Bax) was detected by Western blot analysis, and caspase-3 was detected using fluorimetry. The expression of cyclin G1 mRNA and protein in HepG2/Huh7-cyclin G1-siRNA cells was found to be significantly decreased compared to that in HepG2/Huh7 cells. Silencing the expression of cyclin G1 inhibited the proliferation of HCC cells and enhanced radiosensitivity in HCC cells in vitro and in vivo. Knockdown of cyclin G1 expression significantly decreased Bcl-2 expression, and increased Bax expression and caspase-3 activity in HCC cells. Silencing of cyclin G1 expression enhances the radiosensitivity of HCC cells in vitro and in vivo. The mechanism for this may be related to the regulation of apoptosis-related proteins.

FAM225A promotes sorafenib resistance in hepatocarcinoma cells through modulating miR-130a-5p-CCNG1 interaction network

Chemotherapy resistance is still a key hurdle in current hepatocellular carcinoma (HCC) treatment. Therefore, clarifying the molecular mechanisms contributing to this acquired resistance is urgent for the effective treatment of liver cancer. In this research, we observed that lncRNA FAM225A expression is dramatically upregulated not only in hepatocellular carcinoma tissues and cell lines but also in sorafenib-resistant HepG2/SOR cells. Moreover, FAM225A knockdown significantly weakened HepG2/SOR cells resistance to sorafenib treatment by MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Similar results were obtained from the tumor xenograft model in mice. Further mechanistic researches revealed that the direct interaction between FAM225A and miR-130a-5p, while miR-130a-5p negatively modulated CCNG1 expression by targeting 3'UTR of CCNG1. MiR-130a-5p inhibition or CCNG1 overexpression could partially offset FAM225A knockdown-induced increased viability of HepG2/SOR cells in response to sorafenib challenge. Collectively, our findings provide evidence that FAM225A/miR-130a-5p/CCNG1 interaction network regulates the resistance of HCC cells to sorafenib treatment and could supply a possible strategy for restoring sorafenib sensitivity in HCC therapy.

Functional characterization of SOX2 as an anticancer target

SOX2 is a well-characterized pluripotent factor that is essential for stem cell self-renewal, reprogramming, and homeostasis. The cellular levels of SOX2 are precisely regulated by a complicated network at the levels of transcription, post-transcription, and post-translation. In many types of human cancer, SOX2 is dysregulated due to gene amplification and protein overexpression. SOX2 overexpression is associated with poor survival of cancer patients. Mechanistically, SOX2 promotes proliferation, survival, invasion/metastasis, cancer stemness, and drug resistance. SOX2 is, therefore, an attractive anticancer target. However, little progress has been made in the efforts to discover SOX2 inhibitors, largely due to undruggable nature of SOX2 as a transcription factor. In this review, we first briefly introduced SOX2 as a transcription factor, its domain structure, normal physiological functions, and its involvement in human cancers. We next discussed its role in embryonic development and stem cell-renewal. We then mainly focused on three aspects of SOX2: (a) the regulatory mechanisms of SOX2, including how SOX2 level is regulated, and how SOX2 cross-talks with multiple signaling pathways to control growth and survival; (b) the role of SOX2 in tumorigenesis and drug resistance; and (c) current drug discovery efforts on targeting SOX2, and the future perspectives to discover specific SOX2 inhibitors for effective cancer therapy.

Bioinformatics Analysis Makes Revelation to Potential Properties on Regulation and Functions of Human Sox2

Sex determining region Y-box 2 (Sox2) is a transcription factor that is essential for maintaining self-renewal or pluripotency of undifferentiated embryonic stem cells. The expression and distribution of Sox2 in tumor tissues have been extensively recorded, which are related to the progression and metastasis of tumor. However, a complete mechanistic understanding of Sox2 regulation and function remains to be studied. Herein, we show new potential properties of Sox2 regulation and functions from bioinformatics analysis. We use numerous algorithms to characterize the Sox2 gene promoter elements and the Sox2 protein structure, physio-chemical, localization properties and its evolutionary relationships. The expression of Sox2 is regulated by a diverse set of transcription factors and associated with the levels of methylation of CpG Islands in promoters. The structural properties of Sox2 indicate that Sox2 expresses as a stem cell marker in a variety of stem cells. Sox2 together with other transcription factors or proteins regulate the expression of downstream target genes, which makes a great difference to the biological function of stem cells. Not only stem cells, Sox2 also play an important role in tumor cells. In conclusion, this information from bioinformatics analysis will help to understand Sox2 regulation and functions better in future attempts.

Overexpression of CLN3 contributes to tumour progression and predicts poor prognosis in hepatocellular carcinoma

The aberrant expression of ceroid-lipofuscinosis 3 (CLN3) has been reported in a variety of human malignancies. However, the role of CLN3 in the progression and prognosis of hepatocellular carcinoma (HCC) remains unknown. In this study, we found that CLN3 was frequently upregulated in HCC clinical samples and HCC-derived cell lines and was significantly correlated with an APF serum level ≥20 μg/L, a tumour size ≥5 cm, multiple tumours, and the absence of encapsulation. Kaplan-Meier showed that CLN3 upregulation predicted shorter recurrence-free survival (RFS) and overall survival (OS) time in HCC patients. Cox regression analysis revealed that CLN3 upregulation was an independent risk factor for RFS and OS. A functional study demonstrated that the knockdown of CLN3 expression profoundly suppressed the growth and metastasis of HCC cells both in vitro and in vivo. Mechanistic investigation revealed that the EGFR/PI3K/AKT pathway was essential for mediating CLN3 function. In conclusion, our results provide the first evidence that CLN3 contributes to tumour progression and metastasis and offer a potential prognostic predictor and therapeutic target for HCC.

CCNG1 (Cyclin G1) regulation by mutant-P53 via induction of Notch3 expression promotes high-grade serous ovarian cancer (HGSOC) tumorigenesis and progression

TP53 mutation is considerably common in advanced high-grade serous ovarian cancer (HGSOC) and significantly associated with a poor prognosis. In this study, we investigated the role of Cyclin G1 (CCNG1), a target gene of wild-type TP53 (P53wt), in HGSOC and the possible regulatory mechanism between TP53 mutant (P53mt) and CCNG1 in the progression of HGSOC. High expression level of CCNG1 was found in 61.3% of HGSOC tissues and only 18.2% in fimbriae of fallopian tubes. Additionally, overexpression of CCNG1 was significantly associated with a shorter overall survival (P < 0.0001) and progression-free survival (P < 0.0004) in HGSOC patients. In vitro, CCNG1 promoted both tumor cell motility by inducing epithelial-mesenchymal transition (EMT) and resistance to cisplatin (CDDP). In vivo, knockdown expression of CCNG1 inhibited cancer metastasis. Furthermore, P53mt increased the expression of CCNG1 by regulating Notch3 expression, and a positive correlation between CCNG1 and Notch3 protein expression was observed by Immunohistochemistry (IHC) (r = 0.39, P: 0.01528). In conclusion, the activation of P53mt-Notch3-CCNG1 pathway was responsible for tumor progression to advanced disease with correlation with worse prognosis in patients with HGSOC. These data suggest a possible molecular mechanism of disease and highlights CCNG1's potential role as a therapeutic target in HGSOC.

Non-Coding RNA Pvt1 Promotes Cancer Stem Cell-Like Traits in Nasopharyngeal Cancer via Inhibiting miR-1207

Nasopharyngeal carcinoma (NPC) is a kind of head-neck malignant tumor. lncRNA-PVT1 can promote the proliferation of carcinoma cells, and induce cells to have stem cell-like potentials. However, the function of PVT1 in NPC cells is not clear. The expressions of lncRNA-PVT1 and the expressions of the stem cell markers in NPC tissues or cell lines were investigated by qRT-PCR or western blot. The cell proliferation, and the ability of NPC cells to form spherical, clonal colonies were investigated by MTT assay, colony formation assay, and tumor-sphere formation assay. Cancer stem cells surface markers were detected by flow cytometry and western blot. PI3K/AKT signal activation in NPC cells was determined by western blot. PVT1 was significantly up-regulated in both NPC tissues and cell lines and associated with poor prognosis. PVT1 knockdown reduced NPC cells viability, clonogenicity, the cell surface CD44+/CD24- stem phenotype, and the expressions of the stem cell markers in NPC cells, including Oct4, c-Myc, SOX2, and ALDH. Furthermore, PVT1 negatively regulates the expression levels of miR-1207 in NPC cells and spheres cells, which is critical for NPC stemness. Knockdown of miR-1207 promoted stem phenotype and the expressions of the stem cell markers in NPC cells. Moreover, phosphor-PI3K (p-PI3K) and phosphor-AKT (p-AKT) were found to be down-regulated after PVT1 siRNAs transfection in NPC cells. And miR-1207 inhibitor transfection reversed the all the effects brought by PVT1 knockdown. Pvt1 promotes cancer stem cell-like properties in NPC cells via inhibiting miR-1207 and activating the PI3K/AKT signal pathway.

miR-23b suppresses lung carcinoma cell proliferation through CCNG1

Lung carcinoma with high incidence rate could be divided into four subtypes, including small cell carcinoma, squamous cell carcinoma, adenocarcinoma and large cell carcinoma. miR-23b has been reported to have a low expression and play major roles in abundant tumors, however there is little research in lung carcinoma and hence the purpose of this study was to explore the impact of miR-23b in lung carcinoma. The RNA level of miR-23b and cyclin G1 (CCNG1) was measured by reverse transcription quantitative PCR. Luciferase activity reporter assay was used to verify that CCNG1 is a target of miR-23b. MTT and Transwell assays were utilized to test the functional studies of miR-23b in lung cancer cells. In lung carcinoma and lung cancer cells miR-23b expression is low compared with that in paracancerous tissues and normal lung cells. Low miR-23b expression inhibited lung cancer cell proliferation measured by MTT assay. We applied luciferase reporter to determine whether CCNG1 is a target of miR-23b and there was a negative correlation between them. Moreover, interference with CCNG1 reduced the cell proliferation ability, which partially reversed function of miR-23b. miR-23b inhibited cell proliferation of lung cancer by directly targeting CCNG1. It is suggested that miR-23b/CCNG1 axis may present a new target for the treatment of lung cancer.

Role of microRNAs in the main molecular pathways of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common primary liver malignant neoplasia. HCC is characterized by a poor prognosis. The need to find new molecular markers for its diagnosis and prognosis has led to a progressive increase in the number of scientific studies on this topic. MicroRNAs (miRNAs) are small non-coding RNA that play a role in almost all main cellular pathways. miRNAs are involved in the regulation of expression of the major tumor-related genes in carcinogenesis, acting as oncogenes or tumor suppressor genes. The aim of this review was to identify papers published in 2017 investigating the role of miRNAs in HCC tumorigenesis. miRNAs were classified according to their role in the main molecular pathways involved in HCC tumorigenesis: (1) mTOR; (2) Wnt; (3) JAK/STAT; (4) apoptosis; and (5) MAPK. The role of miRNAs in prognosis/response prediction was taken into consideration. Bearing in mind that the analysis of miRNAs in serum and other body fluids would be crucial for clinical management, the role of circulating miRNAs in HCC patients was also investigated. The most represented miRNA-regulated pathway in HCC is mTOR, but apoptosis, Wnt, JAK/STAT or MAPK pathways are also influenced by miRNA expression levels. These miRNAs could thus be used in clinical practice as diagnostic, prognostic or therapeutic targets for HCC treatment.

The C/EBPβ-LINC01133 axis promotes cell proliferation in pancreatic ductal adenocarcinoma through upregulation of CCNG1

Long non-coding RNAs (lncRNAs) are emerging as important regulators and prognostic markers of multiple cancers. Our aim was to determine functional involvement of lncRNAs in pancreatic ductal adenocarcinoma (PDAC). In this study, we report that LINC01133 expression is higher in PDAC tissues compared to adjacent non-cancerous tissues, and this overexpression is associated with poorer prognosis among the patients. In vitro, a knockdown of LINC01133 substantially decreased PDAC cell proliferation. Tumorigenicity of PDAC cells with the LINC01133 knockdown was significantly impaired in a xenograft model assay. Moreover, we determined that CCAAT/enhancer-binding protein β (C/EBPβ) positively regulates LINC01133 expression by binding to the response elements within the LINC01133 promoter. Higher expression of C/EBPβ was observed in PDAC tissues, and this overexpression was also associated with the poorer prognosis. Furthermore, the LINC01133 knockdown decreased cyclin G1 (CCNG1) expression. Overexpression of CCNG1 attenuated the LINC01133 silencing-induced impairment of proliferation in PDAC cells. In summary, our findings revealed that the C/EBPβ-LINC01133 axis performs an oncogenic function in PDAC by activating CCNG1, which may serve as a prognostic biomarker or a therapeutic target in PDAC.

Matrix stiffness-mediated effects on stemness characteristics occurring in HCC cells

Matrix stiffness as an important physical attribute of extracellular matrix exerts significant impacts on biological behaviors of cancer cells such as growth, proliferation, motility, metabolism and invasion. However, its influence on cancer stemness still remains elusive. Here, we explore whether matrix stiffness-mediated effects on stemness characteristics occur in HCC cells. As the substrate stiffness increased, HCC cells exhibited high proportion of cells with CD133(+)/EpCAM(+), high expression levels of CD133, EpCAM, Nanog and SOX2, greater self-renewing ability and oxaliplatin resistance. Simultaneously, their phosphorylation levels of Akt and mTOR, as well as p-4E-BP and SOX2 expressions were also obviously upregulated. Conversely, knockdown of integrin β1 partially attenuated higher stiffness-mediated stemness characteristics in HCC cells, and reversed the phosphorylation levels of Akt and mTOR, and expressions of p-4E-BP and SOX2, suggesting that integrin β1 may deliver higher stiffness signal into HCC cells and activate mTOR signaling pathway. Additionally, mTOR inhibitor suppressed the mTOR phosphorylation level and expression levels of p-4E-BP and SOX2 in HCC cells grown on higher stiffness substrate, as well as depressed their stemness properties significantly, favoring a regulating role of mTOR signaling pathway in matrix stiffness-mediated effects on stemness. In summary, matrix stiffness may be involved in the process of stemness regulation via activating integrin β1/Akt/mTOR/SOX2 signaling pathway. To the best of our knowledge, this study first reveals a novel regulating pathway to direct the stemness characteristics in HCC cells.

Comprehensive phenotypic analysis of knockout mice deficient in cyclin G1 and cyclin G2

Cyclin G1 (CycG1) and Cyclin G2 (CycG2) play similar roles during the DNA damage response (DDR), but their detailed roles remain elusive. To investigate their distinct roles, we generated knockout mice deficient in CycG1 (G1KO) or CycG2 (G2KO), as well as double knockout mice (DKO) deficient in both proteins. All knockouts developed normally and were fertile. Generation of mouse embryonic fibroblasts (MEFs) from these mice revealed that G2KO MEFs, but not G1KO or DKO MEFs, were resistant to DNA damage insults caused by camptothecin and ionizing radiation (IR) and underwent cell cycle arrest. CycG2, but not CycG1, co-localized with γH2AX foci in the nucleus after γ-IR, and γH2AX-mediated DNA repair and dephosphorylation of CHK2 were delayed in G2KO MEFs. H2AX associated with CycG1, CycG2, and protein phosphatase 2A (PP2A), suggesting that γH2AX affects the function of PP2A via direct interaction with its B'γ subunit. Furthermore, expression of CycG2, but not CycG1, was abnormal in various cancer cell lines. Kaplan-Meier curves based on TCGA data disclosed that head and neck cancer patients with reduced CycG2 expression have poorer clinical prognoses. Taken together, our data suggest that reduced CycG2 expression could be useful as a novel prognostic marker of cancer.

Loss of miR-638 promotes invasion and epithelial-mesenchymal transition by targeting SOX2 in hepatocellular carcinoma

Aberrant expression of microRNAs has been identified as regulators of biological processes of hepatocellular carcinoma (HCC) by negatively regulating protein-coding mRNAs. Several studies have demonstrated that miR-638 expression was dysregulated in various human cancers. However, the clinical significance and underlying mechanisms of miR-638 involved in HCC remain to be elucidated. Herein, we confirmed that a reduced miR-638 expression was present in HCC tissues and cell lines. Our clinical analysis revealed that the downregulated miR-638 expression was significantly correlated with poor prognostic features including high Edmondson-Steiner grade, venous infiltration and advanced tumor-node-metastasis (TNM) stage. Moreover, we demonstrated that miR-638 was a novel independent prognostic marker for predicting 5-year survival of HCC patients. Functionally, overexpressed miR-638 expression inhibited cell migration and invasion, while downregulated miR-638 reversed the effect. In addition, miR-638 could regulate SOX2 by directly binding to its 3'-UTR. Alternation of SOX2 expression at least partially abolished the migration and invasion effects of miR-638 on HCC cells. Aberrant miR-638 expression could regulate the expression level of epithelial-to-mesenchymal transition markers in vitro and in vivo by modulating SOX2 expression. In conclusion, our data indicated that miR-638 functioned as a tumor suppressor gene and play a critical role in the development of HCC.

The miR27b-CCNG1-P53-miR-508-5p axis regulates multidrug resistance of gastric cancer

Multidrug resistance (MDR) correlates with treatment failure and poor prognosis among gastric cancer (GC) patients. In a previous study using high-throughput functional screening, we identified 11 microRNAs (miRNAs) that regulate MDR in GC and found that miR-508-5p reversed MDR by targeting ABCB1 and ZNRD1. However, the mechanism by which miR-508-5p was decreased in chemo-resistant GC cells was unclear. In this study, we found that ectopic miR-27b is sufficient to sensitize tumors to chemotherapy in vitro and in vivo. Moreover, miR-27b directly targets the 3′ untranslated regions (3′-UTRs) of CCNG1, a well-known negative regulator of P53 stability. Interestingly, miR-27b up-regulation leads to increased miR-508-5p expression, and this phenomenon is mediated by CCNG1 and P53. Further investigation indicated that miR-508-5p is directly regulated by P53. Thus, the miR-27b/CCNG1/P53/miR-508-5p axis plays important roles in GC-associated MDR. In addition, miR-27b and miR-508-5p expression was detected in GC tissues with different chemo-sensitivities, and we found that tissues in which miR-27b and miR-508-5p are up-regulated are more sensitive to chemotherapy. Together, these data suggest that the combination of miR-27b and miR-508-5p represents a potential marker of MDR. Restoring the miR-27b and miR-508-5p levels might contribute to MDR reversion in future clinical practice.

MiR-23b targets cyclin G1 and suppresses ovarian cancer tumorigenesis and progression

BACKGROUND

It has been proposed that cyclin G1 (CCNG1) participates in p53-dependent G1-S and G2 checkpoints and might function as an oncogenic protein in the initiation and metastasis of ovarian carcinoma. MicroRNA 23b (miR-23b) is a critical regulatory factor in the progression of many cancer cell types that targets the relevant genes.

METHODS

MiR-23b expression in ovarian tissues was quantified by quantitative reverse transcription-PCR. The ovarian cancer cell lines OVCAR3, HO8910-PM, and SKOV3/DDP were transfected with miR-23b, after we assayed the cell phenotype and expression of the relevant molecules. Dual-luciferase reporter assay and a xenograft mouse model were used to examine the expression of miR-23b and its target gene CCNG1.

RESULTS

MIR23B mRNA expression was significantly lower in epithelial ovarian carcinoma and borderline tumors than in normal ovarian tissues and benign tumors, and miR-23b expression among ages and pathological subtypes was significantly different. CCNG1 mRNA expression was significantly lower in normal ovarian tissues than in benign tumors, borderline tumors, and ovarian carcinomas, and expression among pathological subtypes was significantly different. MiR-23b overexpression inhibited ovarian cancer cell proliferation, invasion, and migration, and induced apoptosis. Dual-luciferase reporter assay showed that miR-23b bound with the 3' untranslated region of CCNG1. MiR-23b overexpression significantly downregulated CCNG1, urokinase, survivin, Bcl-xL, P70S6K, and matrix metallopeptidase-9 (MMP9) mRNA and protein expression. Furthermore, miR-23b inhibited tumor growth and suppressed CCNG1 expression in vitro.

CONCLUSIONS

Our findings show that miR-23b may inhibit ovarian cancer tumorigenesis and progression by downregulating CCNG1 and the expression of the relevant genes. MiR-23b is a potentially novel application for regulating ovarian carcinoma progression.

Roles of sex-determining region Y-box 2 in cell pluripotency and tumor-related signaling pathways

The sex-determining region Y-box 2 (SOX2) gene, a member of the Sry-like high-mobility group box (SOX) gene family, encodes the transcription factor Sox2, which significantly contributes to the regulation of cell pluripotency. Sox2 is closely associated with early embryonic development, neural differentiation and other biological processes. An inreasing number of recent studies suggest that Sox2 exerts a positive effect on malignant tumors. According to these results, Sox2 is expected to become a novel target for cancer therapy by unveiling the mechanism through which it affects the biological behavior of tumors. Therefore, it is crucial to elucidate the detailed association of Sox2 with malignant tumors. The aim of this study was to review the role of Sox2 in pluripotency maintenance, early embryonic development and neural differentiation, as well as investigate the detailed mechanism through which Sox2 regulates cancer stem cells and tumorigenesis.

Characteristics of liver cancer stem cells and clinical correlations

Liver cancer is an aggressive malignant disease with a poor prognosis. Patients with liver cancer are usually diagnosed at an advanced stage and thus miss the opportunity for surgical resection. Chemotherapy and radiofrequency ablation, which target tumor bulk, have exhibited limited therapeutic efficacy to date. Liver cancer stem cells (CSCs) are a small subset of undifferentiated cells existed in liver cancer, which are considered to be responsible for liver cancer initiation, metastasis, relapse and chemoresistance. Elucidating liver CSC characteristics and disclosing their regulatory mechanism might not only deepen our understanding of the pathogenesis of liver cancer but also facilitate the development of diagnostic, prognostic and therapeutic approaches to improve the clinical management of liver cancer. In this review, we will summarize the recent advances in liver CSC research in terms of the origin, identification, regulation and clinical correlation.

The role of Cyclin G1 in cellular proliferation and apoptosis of human epithelial ovarian cancer

Cyclin G1 plays an essential role in the development of human carcinoma. Here, we characterized the clinical significance of Cyclin G1 and investigated its role in cellular proliferation and apoptosis of epithelial ovarian cancer (EOC). Western blot was used to evaluate the expression of Cyclin G1 in nine fresh EOC tissues and three fresh normal ovarian tissues. Immunohistochemistry analysis was performed on formalin-fixed paraffin-embedded section of 119 cases of EOCs. Using cell counting kit (CCK)-8 and colony formation assays, we analyzed the effect of Cyclin G1 in cellular proliferation of EOC. Besides, the immunofluorescence and flow cytometry analysis was performed to study the role of Cyclin G1 in cellular apoptosis of EOC. We found Cyclin G1 was up-regulated in EOC tissues compared with the normal ovary tissues. Cyclin G1 expression in EOC was closely correlated with differentiation grade (P = 0.009) and malignant tumor cells in ascites (P = 0.009). The Kaplan-Meier curve showed that higher expression of Cyclin G1 was associated with significantly shorter survival in EOC patients. Multivariate analysis suggested Cyclin G1 expression was an independent prognostic factor for overall survival. CCK-8 and colony formation assays revealed that depletion of Cyclin G1 inhibited the proliferation and clone formation. Combined immunofluorescence and flow cytometry analysis showed that silencing of Cyclin G1 with shRNA could promote apoptosis of ovarian cancer cells. Additionally, the result of immunoprecipitation test showed Cyclin G1 interacted with CDK2 in EOC cells. In summary, our findings suggest that Cyclin G1 may be involved in the prognosis of EOC patients and be a useful therapeutic target for EOC.

Multiple interactive factors in hepatocarcinogenesis

Hepatocellular carcinoma (HCC) is the fifth most prevalent cancer and the third most frequent cause of cancer mortality globally. Each year there are approximately 630,000 new cases of HCC in the world and more than half of the new cases occur in China. Major risk factors of HCC include HBV or HCV infection, alcoholic liver disease, and nonalcoholic fatty liver disease. Most of these risk factors lead to chronic hepatitis and cirrhosis, which is present in 80-90% of HCC patients. Hepatocarcinogenesis has been regarded as a multi-stage process involving multiple genetic or environmental factors. Interaction and cross-regulation of distinct factors synergistically contributes to HCC occurrence. A comprehensive knowledge on the multiple factors and their interaction in hepatocarcinogenesis is necessary to improve the effectiveness of HCC intervention. In this review, we will focus on the recent progress made in understanding the mechanisms of hepatocarcinogenesis and discuss some potential issues or challenges in this area.

Ethyl pyruvate inhibits proliferation and induces apoptosis of hepatocellular carcinoma via regulation of the HMGB1-RAGE and AKT pathways

Ethyl pyruvate (EP) was recently identified as a stable lipophilic derivative of pyruvic acid with significant antineoplastic activities. The high mobility group box-B1 (HMGB1)-receptor for advanced glycation end-products (RAGE) and the protein kinase B (Akt) pathways play a crucial role in tumorigenesis and development of many malignant tumors. We tried to observe the effects of ethyl pyruvate on liver cancer growth and explored its effects in hepatocellular carcinoma model. In this study, three hepatocellular carcinoma cell lines were treated with ethyl pyruvate. An MTT colorimetric assay was used to assess the effects of EP on cell proliferation. Flow cytometry and TUNEL assays were used to analyze apoptosis. Real-time PCR, Western blotting and immunofluorescence demonstrated ethyl pyruvate reduced the HMGB1-RAGE and AKT pathways. The results of hepatoma orthotopic tumor model verified the antitumor effects of ethyl pyruvate in vivo. EP could induce apoptosis and slow the growth of liver cancer. Moreover, EP decreased the expression of HMGB1, RAGE, p-AKT and matrix metallopeptidase-9 (MMP9) and increased the Bax/Bcl-2 ratio. In conclusion, this study demonstrates that ethyl pyruvate induces apoptosis and cell-cycle arrest in G phase in hepatocellular carcinoma cells, plays a critical role in the treatment of cancer.

SHP2 promotes laryngeal cancer growth through the Ras/Raf/Mek/Erk pathway and serves as a prognostic indicator for laryngeal cancer

The overall survival rate and prognosis of patients with laryngeal cancer are not optimistic despite advances in therapeutic techniques. Gene expression prognostic models enable the development of more appropriate treatment strategies. The human gene PTPN11 encoding a non-receptor protein tyrosine phosphatase, Src homology phosphotyrosine phosphatase 2 (SHP2), is a well-documented proto-oncogene in various malignancies. This study investigated the role of SHP2 expression and associated clinical manifestations in laryngeal cancer using a tissue microarray of 112 pairs of laryngeal cancer samples and corresponding adjacent normal mucosae. SHP2 expression increased in laryngeal cancer, and this result was associated with the poor survival rate of laryngeal cancer patients. Moreover, increased SHP2 expression remarkably promoted the growth of laryngeal cancer cells in vitro and tumorigenicity of laryngeal cancer cells in vivo. The Ras/Raf/Mek/Erk pathway was also found to be involved in the SHP2-induced growth of laryngeal cancer cells. Overall, our findings indicated that SHP2 plays an important role in laryngeal cancer tumorigenesis and that its expression is negatively correlated with the prognosis of patients. Thus, SHP2 may be a promising combinational therapeutic target for treatment of laryngeal cancer. The interference of SHP2 expression can serve as a novel strategy for laryngeal cancer treatment.