ITGA6 is directly regulated by hypoxia-inducible factors and enriches for cancer stem cell activity and invasion in metastatic breast cancer models

NFAT1 Hypermethylation Promotes Epithelial-Mesenchymal Transition and Metastasis in Nasopharyngeal Carcinoma by Activating ITGA6 Transcription

DNA methylation is an important epigenetic change in carcinogenesis. However, the function and mechanism of DNA methylation dysregulation in nasopharyngeal carcinoma (NPC) is still largely unclear. Our previous genome-wide microarray data showed that NFAT1 is one of the most hypermethylated transcription factor genes in NPC tissues. Here, we found that NFAT1 hypermethylation contributes to its down-regulation in NPC. NFAT1 overexpression inhibited cell migration, invasion, and epithelial-mesenchymal transition in vitro and tumor metastasis in vivo. We further established that the tumor suppressor effect of NFAT1 is mediated by its inactivation of ITGA6 transcription. Our findings suggest the significance of activating NFAT1/ITGA6 signaling in aggressive NPC, defining a novel critical signaling mechanism that drives NPC invasion and metastasis and providing a novel target for future personalized therapy.

The Tumor Microenvironments of Lethal Prostate Cancer

Localized prostate cancer (confined to the gland) generally is considered curable, with nearly a 100% 5-year-survival rate. When the tumor escapes the prostate capsule, leading to metastasis, there is a poorer prognosis and higher mortality rate, with 5-year survival dropping to less than 30%. A major research question has been to understand the transition from indolent (low risk) disease to aggressive (high risk) disease. In this chapter, we provide details of the changing tumor microenvironments during prostate cancer invasion and their role in the progression and metastasis of lethal prostate cancer. Four microenvironments covered here include the muscle stroma, perineural invasion, hypoxia, and the role of microvesicles in altering the extracellular matrix environment. The adaptability of prostate cancer to these varied microenvironments and the cues for phenotypic changes are currently understudied areas. Model systems for understanding smooth muscle invasion both in vitro and in vivo are highlighted. Invasive human needle biopsy tissue and mouse xenograft tumors both contain smooth muscle invasion. In combination, the models can be used in an iterative process to validate molecular events for smooth muscle invasion in human tissue. Understanding the complex and interacting microenvironments in the prostate holds the key to early detection of high-risk disease and preventing tumor invasion through escape from the prostate capsule.

Integrative analysis of gene expression profiles reveals distinct molecular characteristics in oral tongue squamous cell carcinoma

Oral tongue squamous cell carcinoma (OTSCC) is the most common type of oral cancer. Despite advances in knowledge regarding the genome-scale gene expression pattern of oral cancer, the molecular portrait of OTSCC biology has remained unclear over the last few decades. Furthermore, studies concerning OTSCC gene-expression profiles are limited or inconsistent owing to tissue heterogeneity in single-cohort studies. Consequently, the present study integrated the profile datasets of three cohorts in order to screen for differentially expressed genes (DEGs), and subsequently identified the potential candidate genes and pathways in OTSCC through gene enrichment analysis and protein-protein interaction (PPI) network construction. Using the selected Gene Expression Omnibus datasets GSE13601, GSE31056 and GSE78060, 206 DEGs (125 upregulated and 81 downregulated) were identified in OTSCC, principally associated with extracellular matrix (ECM) organization and the phosphoinositide 3-kinase/protein kinase B signaling pathway. Furthermore, 146/206 DEGs were filtered into the PPI network and 20 hub genes were sorted. Further results indicated that the two most significant modules filtered from the PPI network were associated with ECM organization and human papillomavirus infection, which are important factors affecting OTSCC pathology. Overall, a set of OTSCC-associated DEGs has been identified, including certain key candidate genes that may be of vital importance for diagnosis, therapy and prevention of this disease.

miR-542-5p Attenuates Fibroblast Activation by Targeting Integrin α6 in Silica-Induced Pulmonary Fibrosis

Silicosis is a very serious occupational disease and it features pathological manifestations of inflammatory infiltration, excessive proliferation of fibroblasts and massive depositions of the extracellular matrix in the lungs. Recent studies described the roles of a variety of microRNAs (miRNAs) in fibrotic diseases. Here, we aimed to explore the potential mechanism of miR-542-5p in the activation of lung fibroblasts. To induce a pulmonary fibrosis mouse model, silica suspension and the miR-542-5p agomir were administered to mice by intratracheal instillation and tail vein injection. We found that miR-542-5p was significantly decreased in mouse fibrotic lung tissues and up-regulation of miR-542-5p visually attenuated a series of fibrotic lesions, including alveolar structural damage, alveolar interstitial thickening and silica-induced nodule formation. The down-regulation of miR-542-5p was also observed in mouse fibroblast (NIH-3T3) treated with transforming growth factor β1 (TGF-β1). The proliferation and migration ability of NIH-3T3 cells were also inhibited by the transfection of miR-542-5p mimic. Integrin α6 (Itga6), reported as a cell surface protein associated with fibroblast proliferation, was confirmed to be a direct target of miR-542-5p. The knockdown of Itga6 significantly inhibited the phosphorylation of FAK/PI3K/AKT. In conclusion, miR-542-5p has a potential function for reducing the proliferation of fibroblasts and inhibiting silica-induced pulmonary fibrosis, which might be partially realized by directly binding to Itga6. Our data suggested that miR-542-5p might be a new therapeutic target for silicosis or other pulmonary fibrosis.

Evidence of Polygenic Adaptation to High Altitude from Tibetan and Sherpa Genomes

Although Tibetans and Sherpa present several physiological adjustments evolved to cope with selective pressures imposed by the high-altitude environment, especially hypobaric hypoxia, few selective sweeps at a limited number of hypoxia related genes were confirmed by multiple genomic studies. Nevertheless, variants at these loci were found to be associated only with downregulation of the erythropoietic cascade, which represents an indirect aspect of the considered adaptive phenotype. Accordingly, the genetic basis of Tibetan/Sherpa adaptive traits remains to be fully elucidated, in part due to limitations of selection scans implemented so far and mostly relying on the hard sweep model.

In order to overcome this issue, we used whole-genome sequence data and several selection statistics as input for gene network analyses aimed at testing for the occurrence of polygenic adaptation in these high-altitude Himalayan populations. Being able to detect also subtle genomic signatures ascribable to weak positive selection at multiple genes of the same functional subnetwork, this approach allowed us to infer adaptive evolution at loci individually showing small effect sizes, but belonging to highly interconnected biological pathways overall involved in angiogenetic processes.

Therefore, these findings pinpointed a series of selective events neglected so far, which likely contributed to the augmented tissue blood perfusion observed in Tibetans and Sherpa, thus uncovering the genetic determinants of a key biological mechanism that underlies their adaptation to high altitude.

Dietary cholesterol promotes steatohepatitis related hepatocellular carcinoma through dysregulated metabolism and calcium signaling

The underlining mechanisms of dietary cholesterol and nonalcoholic steatohepatitis (NASH) in contributing to hepatocellular carcinoma (HCC) remain undefined. Here we demonstrated that high-fat-non-cholesterol-fed mice developed simple steatosis, whilst high-fat-high-cholesterol-fed mice developed NASH. Moreover, dietary cholesterol induced larger and more numerous NASH-HCCs than non-cholesterol-induced steatosis-HCCs in diethylnitrosamine-treated mice. NASH-HCCs displayed significantly more aberrant gene expression-enriched signaling pathways and more non-synonymous somatic mutations than steatosis-HCCs (335 ± 84/sample vs 43 ± 13/sample). Integrated genetic and expressional alterations in NASH-HCCs affected distinct genes pertinent to five pathways: calcium, insulin, cell adhesion, axon guidance and metabolism. Some of the novel aberrant gene expression, mutations and core oncogenic pathways identified in cholesterol-associated NASH-HCCs in mice were confirmed in human NASH-HCCs, which included metabolism-related genes (ALDH18A1, CAD, CHKA, POLD4, PSPH and SQLE) and recurrently mutated genes (RYR1, MTOR, SDK1, CACNA1H and RYR2). These findings add insights into the link of cholesterol to NASH and NASH-HCC and provide potential therapeutic targets.

SDF-1/CXCR4 axis promotes the growth and sphere formation of hypoxic breast cancer SP cells by c-Jun/ABCG2 pathway

ATP-binding cassette sub-family G member 2 (ABCG2) confers to the major phenotypes of side population (SP) cells, the cancer stem-like cells. In this study, the SP cells displayed a distinctly higher ABCG2 expression level, sphere formation efficiency (SFE) and growth rate even under hypoxia condition. CXCR4 overexpression by pcDNA-CXCR4 transfection robustly increased ABCG2 expression, and promoted SFE and growth of hypoxic SP cells, while CXCR4 inhibitor AMD3100 could suppress the promotion. Additionally, we found that CXCR4 promoted the expression of c-Jun, a major gene in the oncogenic JNK/c-Jun pathway. Our data on electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP) assays both showed that c-Jun directly bound with the ABCG2 promoter sequence. Moreover, overexpression of JNK/c-Jun promoted ABCG2 expression, SFE, and growth of hypoxic SP cells and the promotion could be rescued by c-Jun inhibitor SP600125. In conclusion, CXCR4 increases the growth and SFE of breast cancer SP cells under hypoxia through c-Jun-mediated transcriptional activation of ABCG2.

Alpha-6 integrin promotes radioresistance of glioblastoma by modulating DNA damage response and the transcription factor Zeb1

Radiotherapy is the cornerstone of glioblastoma (GBM) standard treatment. However, radioresistance of cancer cells leads to an inevitable recurrence. In the present study, we showed that blocking α6-integrin in cells derived from GBM biopsy specimens cultured as neurospheres, sensitized cells to radiation. In cells downregulated for α6-integrin expression, we observed a decrease in cell survival after irradiation and an increase in radio-induced cell death. We also demonstrated that inhibition of α6-integrin expression affects DNA damage checkpoint and repair. Indeed, we observed a persistence of γ-H2AX staining after IR and the abrogation of the DNA damage-induced G2/M checkpoint, likely through the downregulation of the checkpoint kinase CHK1 and its downstream target Cdc25c. We also showed that α6-integrin contributes to GBM radioresistance by controlling the expression of the transcriptional network ZEB1/OLIG2/SOX2. Finally, the clinical data from TCGA and Rembrandt databases demonstrate that GBM patients with high levels of the five genes signature, including α6-integrin and its targets, CHK1, ZEB1, OLIG2 and SOX2, have a significantly shorter overall survival. Our study suggest that α6-integrin is an attractive therapeutic target to overcome radioresistance of GBM cancer cells.

New insights into diagnosis and therapeutic options for proliferative hepatoblastoma

Surgery and cisplatin-based treatment of hepatoblastoma (HB) currently guarantee the survival of 70%-80% of patients. However, some important challenges remain in diagnosing high-risk tumors and identifying relevant targetable pathways offering new therapeutic avenues. Previously, two molecular subclasses of HB tumors have been described, C1 and C2, with C2 being the subgroup with the poorest prognosis, a more advanced tumor stage, and the worst overall survival rate. An associated 16-gene signature to discriminate the two tumoral subgroups was proposed, but it has not been transferred into clinical routine. To address these issues, we performed RNA sequencing of 25 tumors and matched normal liver samples from patients. The transcript profiling separated HB into three distinct subgroups named C1, C2A, and C2B, identifiable by a concise four-gene signature: hydroxysteroid 17-beta dehydrogenase 6, integrin alpha 6, topoisomerase 2-alpha, and vimentin, with topoisomerase 2-alpha being characteristic for the proliferative C2A tumors. Differential expression of these genes was confirmed by quantitative RT-PCR on an expanded cohort and by immunohistochemistry. We also revealed significant overexpression of genes involved in the Fanconi anemia (FA) pathway in the C2A subgroup. We then investigated the ability of several described FA inhibitors to block growth of HB cells in vitro and in vivo. We demonstrated that bortezomib, a Food and Drug Administration-approved proteasome inhibitor, strongly impairs the proliferation and survival of HB cell lines in vitro, blocks FA pathway-associated double-strand DNA repair, and significantly impedes HB growth in vivo.

CONCLUSION

The highly proliferating C2A subtype is characterized by topoisomerase 2-alpha gene up-regulation and FA pathway activation, and the HB therapeutic arsenal could include bortezomib for the treatment of patients with the most aggressive tumors. (Hepatology 2018;68:89-102).

Physiological Hypoxia (Physioxia) Impairs the Early Adhesion of Single Lymphoma Cell to Marrow Stromal Cell and Extracellular Matrix. Optical Tweezers Study

Adhesion is critical for the maintenance of cellular structures as well as intercellular communication, and its dysfunction occurs prevalently during cancer progression. Recently, a growing number of studies indicated the ability of oxygen to regulate adhesion molecules expression, however, the influence of physiological hypoxia (physioxia) on cell adhesion remains elusive. Thus, here we aimed: (i) to develop an optical tweezers based assay to precisely evaluate single diffuse large B-cell lymphoma (DLBCL) cell adhesion to neighbor cells (mesenchymal stromal cells) and extracellular matrix (Matrigel) under normoxia and physioxia; and, (ii) to explore the role of integrins in adhesion of single lymphoma cell. We identified the pronouncedly reduced adhesive properties of lymphoma cell lines and primary lymphocytes B under physioxia to both stromal cells and Matrigel. Corresponding effects were shown in bulk adhesion assays. Then we emphasized that impaired β1, β2 integrins, and cadherin-2 expression, studied by confocal microscopy, account for reduction in lymphocyte adhesion in physioxia. Additionally, the blockade studies conducted with anti-integrin antibodies have revealed the critical role of integrins in lymphoma adhesion. To summarize, the presented approach allows for precise confirmation of the changes in single cell adhesion properties provoked by physiological hypoxia. Thus, our findings reveal an unprecedented role of using physiologically relevant oxygen conditioning and single cell adhesion approaches when investigating tumor adhesion in vitro.

Transcriptional Repression of p53 by PAX3 Contributes to Gliomagenesis and Differentiation of Glioma Stem Cells

Although there are available therapies as surgery, chemotherapy and radiation, glioblastoma (GBM) still has been considered as the most common and overwhelming primary tumor of brain. In GBM, the brain glioma stem cells (BGSCs) were identified and played a crucial role in resistance of GBM to conventional therapies described above. PAX3 was previously identified by our group as a diagnostic/prognostic marker and a therapeutic regulator in the therapy of GBM. Here, we hypothesized PAX3/p53 axis promoted the process of differentiation, regulating to the cancer stem cell properties, such as proliferation and migration. The correlation between PAX3 and p53 in GBM were first clarified. Immunofluorescence of p53 was shown activated following BGSCs differentiation. We further identified that PAX3 might specifically bind to the promoter of p53 gene, and transcriptionally repressed p53 expression. ChIP assay further confirmed that PAX3/p53 axis regulated the differentiation process of BGSCs. Then, the function of PAX3 in BGSCs were sequentially investigated in vitro and in vivo. Ectopic PAX3 expression promoted BGSCs growth and migration while PAX3 knockdown suppressed BGSCs growth, migration in vitro and in vivo. Similar to PAX3 overexpression, p53 inhibition also showed increase in growth and migration of differentiated BGSCs. Regarding the functional interaction between PAX3 and p53, PAX3 knockdown-mediated decrease in proliferation was partially rescued by p53 inhibition. Hypoxia significantly promoted the migration potential of BGSCs. In addition, hypoxia inducible factor-1α (HIF-1α) might be a potential upstream regulator of PAX3 in differentiated BGSCs under hypoxia. Our work may provide a supplementary mechanism in regulation of the BGSCs differentiation and their functions, which should provide novel therapeutic targets for GBM in future.

Comparative transcriptome analysis of the swimbladder reveals expression signatures in response to low oxygen stress in channel catfish, Ictalurus punctatus

Channel catfish is the leading aquaculture species in the US, and one of the reasons for its application in aquaculture is its relatively high tolerance against hypoxia. However, hypoxia can still cause huge economic losses to the catfish industry. Studies on hypoxia tolerance, therefore, are important for aquaculture. Fish swimbladder has been considered as an accessory respiration organ surrounded by a dense capillary countercurrent exchange system. In this regard, we conducted RNA-Seq analysis with swimbladder samples of catfish under hypoxic and normal conditions to determine if swimbladder was responsive to low oxygen treatment and to reveal genes, their expression patterns, and pathways involved in hypoxia responses in catfish. A total of 155 differentially expressed genes (DEGs) were identified from swimbladder of adult catfish, whereas a total of 2,127 DEGs were identified from swimbladder of fingerling catfish under hypoxic condition as compared with untreated controls. Subsequent pathway analysis revealed that many DEGs under hypoxia were involved in HIF signaling pathway ( nos2, eno2, camk2d2, prkcb, cdkn1a, eno1, and tfrc), MAPK signaling pathway (voltage-dependent calcium channel subunit genes), PI3K/Akt/mTOR signaling pathway ( itga6, g6pc, and cdkn1a), Ras signaling pathway ( efna3 and ksr2), and signaling by VEGF ( fn1, wasf3, and hspb1) in catfish swimbladder. This study provided insights into regulation of gene expression and their involved gene pathways in catfish swimbladder in response to low oxygen stresses.

Mechanisms of autophagy and relevant small-molecule compounds for targeted cancer therapy

Autophagy is an evolutionarily conserved, multi-step lysosomal degradation process for the clearance of damaged or superfluous proteins and organelles. Accumulating studies have recently revealed that autophagy is closely related to a variety of types of cancer; however, elucidation of its Janus role of either tumor-suppressive or tumor-promoting still remains to be discovered. In this review, we focus on summarizing the context-dependent role of autophagy and its complicated molecular mechanisms in different types of cancer. Moreover, we discuss a series of small-molecule compounds targeting autophagy-related proteins or the autophagic process for potential cancer therapy. Taken together, these findings would shed new light on exploiting the intricate mechanisms of autophagy and relevant small-molecule compounds as potential anti-cancer drugs to improve targeted cancer therapy.

Integrative analysis of gene expression profiles reveals specific signaling pathways associated with pancreatic duct adenocarcinoma

Background

Pancreatic duct adenocarcinoma (PDAC) remains a major health problem because conventional cancer treatments are relatively ineffective against it. Microarray studies have linked many genes to pancreatic cancer, but the available data have not been extensively mined for potential insights into PDAC. This study attempted to identify PDAC-associated genes and signaling pathways based on six microarray-based profiles of gene expression in pancreatic cancer deposited in the gene expression omnibus database.

Methods

Pathway network methods were used to analyze core pathways in six publicly available pancreatic cancer gene (GSE71989, GSE15471, GSE16515, GSE32676, GSE41368 and GSE28735) expression profiles. Genes potentially linked to PDAC were assessed for potential impact on survival time based on data in The Cancer Genome Atlas and International Cancer Genome Consortium databases, and the expression of one candidate gene (CKS2) and its association with survival was examined in 102 patients with PDAC from our hospital. Effects of CKS2 knockdown were explored in the PDAC cell lines BxPC-3 and CFPAC-1.

Results

The KEGG signaling pathway called “pathway in cancer” may play an important role in pancreatic cancer development and progression. Five genes (BIRC5, CKS2, ITGA3, ITGA6 and RALA) in this pathway were significantly associated with survival time in patients with PDAC. CKS2 was overexpressed in PDAC samples from our hospital, and higher CKS2 expression in these patients was associated with shorter survival time. CKS2 knockdown substantially inhibited PDAC cell proliferation in vitro.

Conclusions

Analysis integrating existing microarray datasets allowed identification of the “pathway in cancer” as an important signaling pathway in PDAC. This integrative approach may be powerful for identifying genes and pathways involved in cancer.

Electronic supplementary material

The online version of this article (10.1186/s40880-018-0289-9) contains supplementary material, which is available to authorized users.

Two-photon fluorescent probe for detection of nitroreductase and hypoxia-specific microenvironment of cancer stem cell

Hypoxia plays a crucial role in cancer progression, and it has great significance for monitoring hypoxic level in biosystems. Cancer stem cells (CSCs) represent a small population of tumour cells that regard as the key to seed tumours. The survival of CSCs depend on the tumour microenvironment, which is distinct region has the hypoxic property. Therefore, the detection of the hypoxic CSC niche plays a pivotal role in the destructing the 'soil' of CSCs, and eliminating CSCs population. Numerous one-photon excited fluorescent probes have been developed to indicate the hypoxic status in tumours through the detection of nitroreductase (NTR) level. However, the biomedical application of one-photon fluorescent probes is limited due to the poor tissue penetration. In the present work, we reported a two-photon fluorescent probe to detect the NTR in CSCs and monitor the hypoxic microenvironment in vivo. The two-photon fluorescent molecular probe with a hypoxic specific response group can be reduced by NTR under hypoxic conditions. We used the two-photon probe to detect the hypoxia status of 3D cultured-CSCs in vitro and in vivo CSCs' microenvironment in tumour. The two-photon absorption cross section extends fluorescent excitation spectra to the near infrared region, which dramatically promotes the tissue penetration for hypoxic microenvironment detection of CSC in vivo.

Inflammatory interferon activates HIF-1α-mediated epithelial-to-mesenchymal transition via PI3K/AKT/mTOR pathway

BACKGROUND

Tumor microenvironments (TMEs) activate various axes/pathways, predominantly inflammatory and hypoxic responses, impact tumorigenesis, metastasis and therapeutic resistance significantly. Although molecular pathways of individual TME are extensively studied, evidence showing interaction and crosstalk between hypoxia and inflammation remain unclear. Thus, we examined whether interferon (IFN) could modulate both inflammatory and hypoxic responses under normoxia and its relation with cancer development.

METHODS

IFN was used to induce inflammation response and HIF-1α expression in various cancer cell lines. Corresponding signaling pathways were then analyzed by a combination of pharmacological inhibitors, immunoblotting, GST-Raf pull-down assays, dominant-negative and short-hairpin RNA-mediated knockdown approaches. Specifically, roles of functional HIF-1α in the IFN-induced epithelial-mesenchymal transition (EMT) and other tumorigenic propensities were examined by knockdown, pharmacological inhibition, luciferase reporter, clonogenic, anchorage-independent growth, wound-healing, vasculogenic mimicry, invasion and sphere-formation assays as well as cellular morphology observation.

RESULTS

We showed for the first time that IFN induced functional HIF-1α expression in a time- and dose- dependent manner in various cancer cell lines under both hypoxic and normoxic conditions, and then leading to an activated HIF-1α pathway in an IFN-mediated pro-inflammatory TME. IFN regulates anti-apoptosis activity, cellular metastasis, EMT and vasculogenic mimicry by a novel mechanism through mainly the activation of PI3K/AKT/mTOR axis. Subsequently, pharmacological and genetic modulations of HIF-1α, JAK, PI3K/AKT/mTOR or p38 pathways efficiently abrogate above IFN-induced tumorigenic propensities. Moreover, HIF-1α is required for the IFN-induced invasiveness, tumorigenesis and vasculogenic mimicry. Further supports for the HIF-1α-dependent tumorigenesis were obtained from results of xenograft mouse model and sphere-formation assay.

CONCLUSIONS

Our mechanistic study showed an induction of HIF-1α and EMT ability in an IFN-mediated inflammatory TME and thus demonstrating a novel interaction between inflammatory and hypoxic TMEs. Moreover, targeting HIF-1α may be a potential target for inhibiting tumor tumorigenesis and EMT by decreasing cancer cells wound healing and anchorage-independent colony growth. Our results also lead to rationale guidance for developing new therapeutic strategies to prevent relapse via targeting TME-providing IFN signaling and HIF-1α programming.

Deep sequencing-based microRNA expression signatures in head and neck squamous cell carcinoma: dual strands of pre-miR-150 as antitumor miRNAs

We adopted into RNA-sequencing technologies to construct the microRNA (miRNA) expression signature of head and neck squamous cell carcinoma (HNSCC). Our signature revealed that a total of 160 miRNAs (44 upregulated and 116 downregulated) were aberrantly expressed in cancer tissues. Expression of miR-150-5p (guide strand miRNA) and miR-150-3p (passenger strand miRNA) were significantly silenced in cancer tissues, suggesting both miRNAs act as antitumor miRNAs in HNSCC cells. Ectopic expression of mature miRNAs, miR-150-5p and miR-150-3p inhibited cancer cell aggressiveness. Low expression of miR-150-5p and miR-150-3p predicted significantly shorter overall survival in patients with HNSCC (P = 0.0091 and P = 0.0386) by Kaplan–Meier survival curves analyses. We identified that integrin α3 (ITGA3), integrin α6 (ITGA6), and tenascin C (TNC) were coordinately regulated by these miRNAs in HNSCC cells. Knockdown assays using siRNAs showed that ITGA3, ITGA6 and TNC acted as cancer promoting genes in HNSCC cells. Moreover, ITGA3, ITGA6, and TNC alterations were associated with significantly poorer overall survival (P = 0.0177, P = 0.0237, and P = 0.026, respectively). Dual strands of pre-150 (miR-150-5p and miR-150-3p) functioned as antitumor miRNAs based on the miRNA expression signature of HNSCC. Identification of antitumor miR-150-mediated RNA networks may provide novel insights into pathogenesis of HNSCC.

17β-Estradiol and ICI182,780 Differentially Regulate STAT5 Isoforms in Female Mammary Epithelium, With Distinct Outcomes

Prolactin (PRL) and estrogen cooperate in lobuloalveolar development of the mammary gland and jointly regulate gene expression in breast cancer cells in vitro. Canonical PRL signaling activates STAT5A/B, homologous proteins that have different target genes and functions. Although STAT5A/B are important for physiological mammary function and tumor pathophysiology, little is known about regulation of their expression, particularly of STAT5B, and the consequences for hormone action. In this study, we examined the effect of two estrogenic ligands, 17β-estradiol (E2) and the clinical antiestrogen, ICI182,780 (ICI, fulvestrant) on expression of STAT5 isoforms and resulting crosstalk with PRL in normal and tumor murine mammary epithelial cell lines. In all cell lines, E2 and ICI significantly increased protein and corresponding nascent and mature transcripts for STAT5A and STAT5B, respectively. Transcriptional regulation of STAT5A and STAT5B by E2 and ICI, respectively, is associated with recruitment of estrogen receptor alpha and increased H3K27Ac at a common intronic enhancer 10 kb downstream of the Stat5a transcription start site. Further, E2 and ICI induced different transcripts associated with differentiation and tumor behavior. In tumor cells, E2 also significantly increased proliferation, invasion, and stem cell-like activity, whereas ICI had no effect. To evaluate the role of STAT5B in these responses, we reduced STAT5B expression using short hairpin (sh) RNA. shSTAT5B blocked ICI-induced transcripts associated with metastasis and the epithelial mesenchymal transition in both cell types. shSTAT5B also blocked E2-induced invasion of tumor epithelium without altering E2-induced transcripts. Together, these studies indicate that STAT5B mediates a subset of protumorigenic responses to both E2 and ICI, underscoring the need to understand regulation of its expression and suggesting exploration as a possible therapeutic target in breast cancer.

Hypoxia-inducible factors regulate pluripotency factor expression by ZNF217- and ALKBH5-mediated modulation of RNA methylation in breast cancer cells

Exposure of breast cancer cells to hypoxia increases the percentage of breast cancer stem cells (BCSCs), which are required for tumor initiation and metastasis, and this response is dependent on the activity of hypoxia-inducible factors (HIFs). We previously reported that exposure of breast cancer cells to hypoxia induces the ALKBH5-mediated demethylation of N6-methyladenosine (m6A) in NANOG mRNA leading to increased expression of NANOG, which is a pluripotency factor that promotes BCSC specification. Here we report that exposure of breast cancer cells to hypoxia also induces ZNF217-dependent inhibition of m6A methylation of mRNAs encoding NANOG and KLF4, which is another pluripotency factor that mediates BCSC specification. Although hypoxia induced the BCSC phenotype in all breast-cancer cell lines analyzed, it did so through variable induction of pluripotency factors and ALKBH5 or ZNF217. However, in every breast cancer line, the hypoxic induction of pluripotency factor and ALKBH5 or ZNF217 expression was HIF-dependent. Immunohistochemistry revealed that expression of HIF-1α and ALKBH5 was concordant in all human breast cancer biopsies analyzed. ALKBH5 knockdown in MDA-MB-231 breast cancer cells significantly decreased metastasis from breast to lungs in immunodeficient mice. Thus, HIFs stimulate pluripotency factor expression and BCSC specification by negative regulation of RNA methylation.

Facile metabolic glycan labeling strategy for exosome tracking

BACKGROUND

Exosomes are nano-sized vesicles derived from the fusion of multivesicular bodies with the surrounding plasma membrane. Exosomes have various diagnostic and therapeutic potentials in cancer and other diseases, thus tracking exosomes is an important issue.

METHODS

Here, we report a facile exosome labeling strategy using a natural metabolic incorporation of an azido-sugar into the glycan, and a strain-promoted azide-alkyne click reaction. In culture, tetra-acetylated N-azidoacetyl-D-mannosamine (Ac₄ManNAz) was spontaneously incorporated into glycans within the cells and later redistributed onto their exosomes. These azido-containing exosomes were then labeled with azadibenzylcyclooctyne (ADIBO)-fluorescent dyes by a bioorthogonal click reaction.

RESULTS

Cellular uptake and the in vivo tracking of fluorescent labeled exosomes were evaluated in various cells and tumor bearing mice. Highly metastatic cancer-derived exosomes showed an increased self-homing in vitro and selective organ distribution in vivo.

CONCLUSION

Our metabolic exosome labeling strategy could be a promising tool in studying the biology and distribution of exosomes, and optimizing exosome based therapeutic approaches.

GENERAL SIGNIFICANT

A facile and effective exosome labeling strategy was introduced by presenting azido moiety on the surface of exosome through metabolic glycan synthesis, and then conjugating a strain-promoted fluorescent dye.

The hypoxic tumour microenvironment

Cancer progression often benefits from the selective conditions present in the tumour microenvironment, such as the presence of cancer-associated fibroblasts (CAFs), deregulated ECM deposition, expanded vascularisation and repression of the immune response. Generation of a hypoxic environment and activation of its main effector, hypoxia-inducible factor-1 (HIF-1), are common features of advanced cancers. In addition to the impact on tumour cell biology, the influence that hypoxia exerts on the surrounding cells represents a critical step in the tumorigenic process. Hypoxia indeed enables a number of events in the tumour microenvironment that lead to the expansion of aggressive clones from heterogeneous tumour cells and promote a lethal phenotype. In this article, we review the most relevant findings describing the influence of hypoxia and the contribution of HIF activation on the major components of the tumour microenvironment, and we summarise their role in cancer development and progression.

Chromatin Immunoprecipitation of HIF-α in Breast Tumor Cells Using Wild Type and Loss of Function Models

Chromatin immunoprecipitation (ChIP) is a powerful method to determine whether a protein of interest binds to specific regulatory elements of the genome. Herein, we outline protocols optimized to detect binding of Hypoxia-Inducible Factor (HIF)-1α or HIF-2α to putative hypoxia response elements (HREs) within HIF target genes expressed in breast tumor epithelial cells.

In Vitro Assays of Breast Cancer Stem Cells

Aldehyde dehydrogenase and mammosphere assays enable the cost-effective quantification and characterization of cancer stem cells (CSCs) from cancer cell lines as well as cancer tissue. Here we describe the quantification of CSCs in breast cancer cell lines using aldehyde dehydrogenase and mammosphere assays under hypoxic (1% O₂) and non-hypoxic (20% O₂) culture conditions. Using this method, a significant enrichment of CSCs compared to bulk populations is observed when breast cancer cells are exposed to 1% O₂ for 72 h.

Associations of high altitude polycythemia with polymorphisms in EPAS1, ITGA6 and ERBB4 in Chinese Han and Tibetan populations

High altitude polycythemia (HAPC) is a common chronic disease at high altitude, which is characterized by excessive erythrocytosis (females, hemoglobin ≥ 190 g/L; males, hemoglobin ≥ 210 g/L). It is the most common disease in chronic mountain sickness casued primarily by persistent arterial hypoxia and ventilatory impairment. However, the disease is still unmanageable and related molecular mechanisms remain largely unclear. This study aims to explore the genetic basis of HAPC in the Chinese Han and Tibetan populations. Subjects were screened for HAPC using the latest approved diagnostic criteria. To explore the hereditary basis of HAPC and investigate the association between three genes (EPAS1, ITGA6, ERBB4) and HAPC in Chinese Han and Tibetan populations. We enrolled 100 patients (70 Han, 30 Tibetan) with HAPC and 100 healthy control subjects (30 Han, 70 Tibetan). Subjects were screened for HAPC using the latest approved diagnostic criteria combined with excessive erythrocytosis and clinical symptoms. Analysis of variance was used to evaluate the impact of polymorphism on HAPC based on genetic variation. The Chi-squared test and analyses of genetic models, rs75591953 and rs75984373 in EPAS1, rs6744873 in ITGA6, rs17335043 in ERBB4 showed associations with reduced HAPC susceptibility in Han populations. Additionally, in Tibetan populations, rs3749148 in ITGA6, rs934607 and rs141267844 in ERBB4 showed a reduced risk of HAPC, whereas rs6710946 in ERBB4 increased the risk of HAPC. Our study suggest that the polymorphisms in the EPAS1, ITGA6 and ERBB4 correlate with susceptibility to HAPC.

Epithelial vimentin plays a functional role in mammary gland development

In the mammary gland, vimentin intermediate filaments are expressed in stromal cells and in basal epithelial cell populations, including gland-reconstituting mammary stem cells, with largely undefined functions. Here, we have studied how vimentin deficiency affects mouse mammary gland development. We find that, in adult vimentin knockout mice (Vim^-/- ), mammary ductal outgrowth is delayed. The adult Vim^-/- glands display dilated ducts and a reduced basal-to-luminal mouse mammary epithelial cell (MMEC) ratio indicative of altered progenitor cell activity. Accordingly, isolated Vim^-/- MMECs form fewer mammospheres and basal-like organoids in vitro than their wild-type counterparts. Importantly, reduced basal MMEC number translates into defects in Vim^-/- mammary gland regeneration in vivo Global gene expression profiling of basal MMECs reveals that lack of vimentin alters multiple pathways, including adhesion, cancer and Wnt signalling. Furthermore, vimentin contributes to stem-like cell properties in MDA-MB-231 breast cancer cells, wherein vimentin depletion reduces tumoursphere formation and attenuates expression of breast cancer stem cell-associated surface markers. Together, our findings identify vimentin as a positive regulator of stemness in the developing mouse mammary gland and in breast cancer cells.

The role of Tec kinase signaling pathways in the development of Mallory Denk Bodies in balloon cells in alcoholic hepatitis

Several research strategies have been used to study the pathogenesis of alcoholic hepatitis (AH). These strategies have shown that various signaling pathways are the target of alcohol in liver cells. However, few have provided specific mechanisms associated with Mallory-Denk Bodies (MDBs) formed in Balloon cells in AH. The formation of MDBs in these hepatocytes is an indication that the mechanisms of protein quality control have failed. The MDB is the result of aggregation and accumulation of proteins in the cytoplasm of balloon degenerated liver cells. To understand the mechanisms that failed to degrade and remove proteins in the hepatocyte from patients suffering from alcoholic hepatitis, we investigated the pathways that showed significant up regulation in the AH liver biopsies compared to normal control livers (Liu et al., 2015). Analysis of genomic profiles of AH liver biopsies and control livers by RNA-seq revealed different pathways that were up regulated significantly. In this study, the focus was on Tec kinase signaling pathways and the genes that significantly interrupt this pathway. Quantitative PCR and immunofluorescence staining results, indicated that several genes and proteins are significantly over expressed in the livers of AH patients that affect the Tec kinase signaling to PI3K which leads to activation of Akt and its downstream effectors.

Exploring the Role of RGD-Recognizing Integrins in Cancer

Integrins are key regulators of communication between cells and with their microenvironment. Eight members of the integrin superfamily recognize the tripeptide motif Arg-Gly-Asp (RGD) within extracelluar matrix (ECM) proteins. These integrins constitute an important subfamily and play a major role in cancer progression and metastasis via their tumor biological functions. Such transmembrane adhesion and signaling receptors are thus recognized as promising and well accessible targets for novel diagnostic and therapeutic applications for directly attacking cancer cells and their fatal microenvironment. Recently, specific small peptidic and peptidomimetic ligands as well as antibodies binding to distinct integrin subtypes have been developed and synthesized as new drug candidates for cancer treatment. Understanding the distinct functions and interplay of integrin subtypes is a prerequisite for selective intervention in integrin-mediated diseases. Integrin subtype-specific ligands labelled with radioisotopes or fluorescent molecules allows the characterization of the integrin patterns in vivo and later the medical intervention via subtype specific drugs. The coating of nanoparticles, larger proteins, or encapsulating agents by integrin ligands are being explored to guide cytotoxic reagents directly to the cancer cell surface. These ligands are currently under investigation in clinical studies for their efficacy in interference with tumor cell adhesion, migration/invasion, proliferation, signaling, and survival, opening new treatment approaches in personalized medicine.

Gene Expression Profiling of Hepatocellular Carcinoma Derived Cancer Stem Like Cell under Hypoxia

PURPOSE

Cancer stem like cells (CSCs), with unlimited self-renewal potential and other stem cell characteristics, occur in several cancers including hepatocellular carcinoma (HCC). Although CSCs can initiate tumors, malignant proliferation, relapse and multi-drug resistance, the ways how to activate them still remain unknown. This study aims to evaluate whether CSC acquire tumorigenic characters under tumor hypoxia, analyzed by microarray analysis.

MATERIALS AND METHODS

CSCs were purified from HCC patients and Affymetrix microarray was used to investigate their gene expression profiles. The results were validated by real-time polymerase chain reaction (PCR).

RESULTS

The results of the microarray indicated that 18 genes were up-regulated and 10 genes were down-regulated in CSCs. Several genes were identified to be significantly involved in the regulation of CSCs such as HCC. Furthermore, the up-regulated genes were related with metabolism, angiogenesis and hypoxia, whereas the down-regulated genes were related with apoptosis and inflammation.

CONCLUSION

The results may help to understand the mechanisms of tumor development through CSCs which acquired their distinctive tumorogenic properties by hypoxic stimulation.

Interest of integrins targeting in glioblastoma according to tumor heterogeneity and cancer stem cell paradigm: an update

Glioblastomas are malignant brain tumors with dismal prognosis despite standard treatment with surgery and radio/chemotherapy. These tumors are defined by an important cellular heterogeneity and notably contain a particular subpopulation of Glioblastoma-initiating cells, which recapitulate the heterogeneity of the original Glioblastoma. In order to classify these heterogeneous tumors, genomic profiling has also been undertaken to classify these heterogeneous tumors into several subtypes. Current research focuses on developing therapies, which could take into account this cellular and genomic heterogeneity. Among these targets, integrins are the subject of numerous studies since these extracellular matrix transmembrane receptors notably controls tumor invasion and progression. Moreover, some of these integrins are considered as membrane markers for the Glioblastoma-initiating cells subpopulation. We reviewed here integrin expression according to glioblastoma molecular subtypes and cell heterogeneity. We discussed their roles in glioblastoma invasion, angiogenesis, therapeutic resistance, stemness and microenvironment modulations, and provide an overview of clinical trials investigating integrins in glioblastomas. This review highlights that specific integrins could be identified as selective glioblastoma cells markers and that their targeting represents new diagnostic and/or therapeutic strategies.

Hypoxic pathobiology of breast cancer metastasis

Dissemination of breast cancer cells (BCCs) to distant sites (metastasis) is the ultimate cause of mortality in patients with breast cancer. Hypoxia (low O₂) is a microenvironmental hallmark of most solid cancers arising as a mismatch between cellular O₂ consumption and supply. Hypoxic selection of BCCs triggers molecular and cellular adaptations dependent upon hypoxia-inducible factors (HIFs), a family of evolutionarily conserved transcriptional activators that coordinate the expression of numerous genes controlling each step of the metastatic process. In this review, we summarize current advances in the understanding of HIF-driven molecular mechanisms that promote BCC metastatic dissemination and patient mortality. In addition, we discuss the clinical and therapeutic implications of HIF targeting in breast cancers.

Identification of potential biomarkers and analysis of prognostic values in head and neck squamous cell carcinoma by bioinformatics analysis

The purpose of this study was to find disease-associated genes and potential mechanisms in head and neck squamous cell carcinoma (HNSCC) with deoxyribonucleic acid microarrays. The gene expression profiles of GSE6791 were downloaded from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) were obtained with packages in R language and STRING constructed protein–protein interaction (PPI) network of the DEGs with combined score >0.8. Subsequently, module analysis of the PPI network was performed by Molecular Complex Detection plugin and functions and pathways of the hub gene in subnetwork were studied. Finally, overall survival analysis of hub genes was verified in TCGA HNSCC cohort. A total of 811 DEGs were obtained, which were mainly enriched in the terms related to extracellular matrix (ECM)–receptor interaction, ECM structural constituent, and ECM organization. A PPI network was constructed, consisting of 401 nodes and 1,254 edges and 15 hub genes with high degrees in the network. High expression of 4 genes of the 15 genes was associated with poor OS of patients in HNSCC, including PSMA7, ITGA6, ITGB4, and APP. Two significant modules were detected from the PPI network, and the enriched functions and pathways included proteasome, ECM organization, and ECM–receptor interaction. In conclusion, we propose that PSMA7, ITGA6, ITGB4, and APP may be further explored as potential biomarkers to aid HNSCC diagnosis and treatment.

Effect of a hypoxic microenvironment after radiofrequency ablation on residual hepatocellular cell migration and invasion

Clinical observations have shown that the boundary of tumor ablation is often less than safe border and that the use of radiofrequency ablation (RFA) in the treatment of hepatocellular carcinoma (HCC) may probably accelerate its recurrence and metastasis. RFA can cause the formation of a transition zone between normal liver tissues and necrotic coagulation, where blood stagnation and thrombosis expose residual cancer cells to a hypoxic microenvironment. As the blocked vessels are slowly reperfused, the oxygen supply is gradually restored. Here, HCC cells underwent heat treatment and were cultured under hypoxic conditions to mimic the aforementioned situation, and morphological changes were observed in the surviving cells. Compared with their parental cells, hypoxic HCC cells showed changes that include enhanced invasive, metastatic, and chemoresistant abilities as well as mesenchymal characteristics. There was also a higher percentage of stem-like cells. However, either improving the hypoxic microenvironment or silencing hypoxia inducible factor (HIF)-1α signaling significantly reduced the invasive, metastatic, and chemoresistant potential and reversed the epithelial-mesenchymal transition to varying degrees. Together, these results indicated that a sustained hypoxic microenvironment after RFA may exert a negative impact on the prognosis of HCC patients, and minimizing exposure to a hypoxic microenvironment and targeting HIF-1α signaling might be effective strategies for patients who experience insufficient RFA therapy.

STROBE-compliant integrin through focal adhesion involve in cancer stem cell and multidrug resistance of ovarian cancer

Cancer stem cells (CSCs) are considered to be the root of carcinoma relapse and drug resistance in ovarian cancer. Hunting for the potential CSC genes and explain their functions would be a feasible strategy to meet the challenge of the drug resistance in ovarian cancer. In this study, we performed bioinformatic approaches such as biochip data extraction and pathway enrichment analyses to elucidate the mechanism of the CSC genes in regulation of drug resistance. Potential key genes, integrins, were identified to be related to CSC in addition to their associations with drug resistance and prognosis in ovarian cancer. A total of 36 ovarian CSC genes involved in regulation of drug resistance were summarized, and potential drug resistance-related CSC genes were identified based on 3 independent microarrays retrieved from the Gene Expression Omnibus (GEO) Profiles. Pathway enrichment of CSC genes associated with drug resistance in ovarian cancer indicated that focal adhesion signaling might play important roles in CSC genes-mediated drug resistance. Integrins are members of the adhesion molecules family, and integrin subunit alpha 1, integrin subunit alpha 5, and integrin subunit alpha 6 (ITGA6) were identified as central CSC genes and their expression in side population cells, cisplatin-resistant SKOV3 (SKOV3/DDP2) cells, and cisplatin-resistant A2780 (A2780/DDP) cells were dysregulated as measured by real-time quantitative polymerase chain reaction. The high expression of ITGA6 in 287 ovarian cancer patients of TCGA cohort was significantly associated with poorer progression-free survival. This study provide the basis for further understanding of CSC genes in regulation of drug resistance in ovarian cancer, and integrins could be a potential biomarker for prognosis of ovarian cancer.

Integrative miRNA-Gene Expression Analysis Enables Refinement of Associated Biology and Prediction of Response to Cetuximab in Head and Neck Squamous Cell Cancer

This paper documents the process by which we, through gene and miRNA expression profiling of the same samples of head and neck squamous cell carcinomas (HNSCC) and an integrative miRNA-mRNA expression analysis, were able to identify candidate biomarkers of progression-free survival (PFS) in patients treated with cetuximab-based approaches. Through sparse partial least square–discriminant analysis (sPLS-DA) and supervised analysis, 36 miRNAs were identified in two components that clearly separated long- and short-PFS patients. Gene set enrichment analysis identified a significant correlation between the miRNA first-component and EGFR signaling, keratinocyte differentiation, and p53. Another significant correlation was identified between the second component and RAS, NOTCH, immune/inflammatory response, epithelial–mesenchymal transition (EMT), and angiogenesis pathways. Regularized canonical correlation analysis of sPLS-DA miRNA and gene data combined with the MAGIA2 web-tool highlighted 16 miRNAs and 84 genes that were interconnected in a total of 245 interactions. After feature selection by a smoothed t-statistic support vector machine, we identified three miRNAs and five genes in the miRNA-gene network whose expression result was the most relevant in predicting PFS (Area Under the Curve, AUC = 0.992). Overall, using a well-defined clinical setting and up-to-date bioinformatics tools, we are able to give the proof of principle that an integrative miRNA-mRNA expression could greatly contribute to the refinement of the biology behind a predictive model.

Integrins in the Spotlight of Cancer

Integrins are heterodimeric cell surface receptors that bind to different extracellular ligands depending on their composition and regulate all processes which enable multicellular life. In cancer, integrins trigger and play key roles in all the features that were once described as the Hallmarks of Cancer. In this review, we will discuss the contribution of integrins to these hallmarks, including uncontrolled and limitless proliferation, invasion of tumor cells, promotion of tumor angiogenesis and evasion of apoptosis and resistance to growth suppressors, by highlighting the latest findings. Further on, given the paramount role of integrins in cancer, we will present novel strategies for integrin inhibition that are starting to emerge, promising a hopeful future regarding cancer treatment.