The new tumor-suppressor gene inhibitor of growth family member 4 (ING4) regulates the production of proangiogenic molecules by myeloma cells and suppresses hypoxia-inducible factor-1 alpha (HIF-1alpha) activity: involvement in myeloma-induced angiogenesis

Hypoxic Bone Marrow Stromal Cells Secrete miR-140-5p and miR-28-3p That Target SPRED1 to Confer Drug Resistance in Multiple Myeloma

Bone marrow stromal cell (BMSC)-derived small extracellular vesicles (sEV) promote drug resistance to bortezomib in multiple myeloma cells. Elucidating the components of BMSC sEV that induce drug resistance in multiple myeloma cells could help identify strategies to overcome resistance. Considering the hypoxic nature of the myeloma microenvironment, we explored the role of hypoxia in regulating BMSC sEV cargo and investigated whether hypoxia-driven sEV miRNAs contribute to the drug resistance in multiple myeloma cells. Hypoxia increased the release of sEVs from BMSCs, and these sEVs more strongly attenuated bortezomib sensitivity in multiple myeloma cells than sEVs from BMSCs under normoxic conditions. RNA sequencing revealed that significantly elevated levels of miR-140-5p and miR-28-3p were enclosed in hypoxic BMSC-derived sEVs. Both miR-140-5p and miR-28-3p conferred bortezomib resistance in multiple myeloma cells by synergistically targeting SPRED1, a member of the Sprouty protein family that regulates MAPK activation. SPRED1 inhibition reduced sensitivity to bortezomib in multiple myeloma cells through activating MAPK-related pathways and significantly promoted multiple myeloma bortezomib resistance and tumor growth in a mouse model. These findings shed light on the role of hypoxia-induced miRNAs shuttled in BMSC-derived sEVs to multiple myeloma cells in inducing drug resistance and identify the miR-140-5p/miR-28-3p/SPRED1/MAPK pathway as a potential targetable axis for treating multiple myeloma.

SIGNIFICANCE

Hypoxia induces stromal cells to secrete extracellular vesicles with increased miR-140-5p and miR-28-3p that are transferred to multiple myeloma cells and drive drug resistance by increasing the MAPK signaling.

Diverse activity of miR-150 in Tumor development: shedding light on the potential mechanisms

There is a growing interest to understand the role and mechanism of action of microRNAs (miRNAs) in cancer. The miRNAs are defined as short non-coding RNAs (18-22nt) that regulate fundamental cellular processes through mRNA targeting in multicellular organisms. The miR-150 is one of the miRNAs that have a crucial role during tumor cell progression and metastasis. Based on accumulated evidence, miR-150 acts as a double-edged sword in malignant cells, leading to either tumor-suppressive or oncogenic function. An overview of miR-150 function and interactions with regulatory and signaling pathways helps to elucidate these inconsistent effects in metastatic cells. Aberrant levels of miR-150 are detectable in metastatic cells that are closely related to cancer cell migration, invasion, and angiogenesis. The ability of miR-150 in regulating of epithelial-mesenchymal transition (EMT) process, a critical stage in tumor cell migration and metastasis, has been highlighted. Depending on the cancer cells type and gene expression profile, levels of miR-150 and potential target genes in the fundamental cellular process can be different. Interaction between miR-150 and other non-coding RNAs, such as long non-coding RNAs and circular RNAs, can have a profound effect on the behavior of metastatic cells. MiR-150 plays a significant role in cancer metastasis and may be a potential therapeutic target for preventing or treating metastatic cancer.

MicroRNAs as the Critical Regulators of Forkhead Box Protein Family in Pancreatic, Thyroid, and Liver Cancers

The metabolism of human body is mainly regulated by the pancreas, liver, and thyroid using the hormones or exocrine secretions that affect the metabolic processes from food digestion to intracellular metabolism. Therefore, metabolic organ disorders have wide clinical symptoms that severely affect the quality of patient's life. The pancreatic, liver, and thyroid cancers as the main malignancies of the metabolic system have always been considered as one of the serious health challenges worldwide. Despite the novel therapeutic modalities, there are still significant high mortality and recurrence rates, especially in liver and pancreatic cancer patients which are mainly related to the late diagnosis. Therefore, it is required to assess the molecular bases of tumor progressions to introduce novel early detection and therapeutic markers in these malignancies. Forkhead box (FOX) protein family is a group of transcription factors that have pivotal roles in regulation of cell proliferation, migration, and apoptosis. They function as oncogene or tumor suppressor during tumor progression. MicroRNAs (miRNAs) are also involved in regulation of cellular processes. Therefore, in the present review, we discussed the role of miRNAs during pancreatic, thyroid, and liver tumor progressions through FOX regulation. It has been shown that miRNAs were mainly involved in tumor progression via FOXM and FOXO targeting. This review paves the way for the introduction of miR/FOX axis as an efficient early detection marker and therapeutic target in pancreatic, thyroid, and liver tumors.

Immunomodulatory properties of CD38 antibodies and their effect on anticancer efficacy in multiple myeloma

BACKGROUND

CD38 has been established as an important therapeutic target for multiple myeloma (MM), for which two CD38 antibodies are currently approved-daratumumab and isatuximab. CD38 is an ectoenzyme that degrades NAD and its precursors and is involved in the production of adenosine and other metabolites.

AIM

Among the various mechanisms by which CD38 antibodies can induce MM cell death is immunomodulation, including multiple pathways for CD38-mediated T-cell activation. Patients who respond to anti-CD38 targeting treatment experience more marked changes in T-cell expansion, activity, and clonality than nonresponders.

IMPLICATIONS

Resistance mechanisms that undermine the immunomodulatory effects of CD38-targeting therapies can be tumor intrinsic, such as the downregulation of CD38 surface expression and expression of complement inhibitor proteins, and immune microenvironment-related, such as changes to the natural killer (NK) cell numbers and function in the bone marrow niche. There are numerous strategies to overcome this resistance, which include identifying and targeting other therapeutic targets involved in, for example, adenosine production, the activation of NK cells or monocytes through immunomodulatory drugs and their combination with elotuzumab, or with bispecific T-cell engagers.

Shutting off the fuel supply to target metabolic vulnerabilities in multiple myeloma

Pathways that govern cellular bioenergetics are deregulated in tumor cells and represent a hallmark of cancer. Tumor cells have the capacity to reprogram pathways that control nutrient acquisition, anabolism and catabolism to enhance their growth and survival. Tumorigenesis requires the autonomous reprogramming of key metabolic pathways that obtain, generate and produce metabolites from a nutrient-deprived tumor microenvironment to meet the increased bioenergetic demands of cancer cells. Intra- and extracellular factors also have a profound effect on gene expression to drive metabolic pathway reprogramming in not only cancer cells but also surrounding cell types that contribute to anti-tumor immunity. Despite a vast amount of genetic and histologic heterogeneity within and between cancer types, a finite set of pathways are commonly deregulated to support anabolism, catabolism and redox balance. Multiple myeloma (MM) is the second most common hematologic malignancy in adults and remains incurable in the vast majority of patients. Genetic events and the hypoxic bone marrow milieu deregulate glycolysis, glutaminolysis and fatty acid synthesis in MM cells to promote their proliferation, survival, metastasis, drug resistance and evasion of immunosurveillance. Here, we discuss mechanisms that disrupt metabolic pathways in MM cells to support the development of therapeutic resistance and thwart the effects of anti-myeloma immunity. A better understanding of the events that reprogram metabolism in myeloma and immune cells may reveal unforeseen vulnerabilities and advance the rational design of drug cocktails that improve patient survival.

Hypoxic microenvironment in cancer: molecular mechanisms and therapeutic interventions

Having a hypoxic microenvironment is a common and salient feature of most solid tumors. Hypoxia has a profound effect on the biological behavior and malignant phenotype of cancer cells, mediates the effects of cancer chemotherapy, radiotherapy, and immunotherapy through complex mechanisms, and is closely associated with poor prognosis in various cancer patients. Accumulating studies have demonstrated that through normalization of the tumor vasculature, nanoparticle carriers and biocarriers can effectively increase the oxygen concentration in the tumor microenvironment, improve drug delivery and the efficacy of radiotherapy. They also increase infiltration of innate and adaptive anti-tumor immune cells to enhance the efficacy of immunotherapy. Furthermore, drugs targeting key genes associated with hypoxia, including hypoxia tracers, hypoxia-activated prodrugs, and drugs targeting hypoxia-inducible factors and downstream targets, can be used for visualization and quantitative analysis of tumor hypoxia and antitumor activity. However, the relationship between hypoxia and cancer is an area of research that requires further exploration. Here, we investigated the potential factors in the development of hypoxia in cancer, changes in signaling pathways that occur in cancer cells to adapt to hypoxic environments, the mechanisms of hypoxia-induced cancer immune tolerance, chemotherapeutic tolerance, and enhanced radiation tolerance, as well as the insights and applications of hypoxia in cancer therapy.

Inhibitor of Growth 4 (ING4) Plays a Tumor-Repressing Role in Oral Squamous Cell Carcinoma via Nuclear Factor kappa-B (NF-kB)/DNA Methyltransferase 1 (DNMT1) Axis-Mediated Regulation of Aldehyde Dehydrogenase 1A2 (ALDH1A2)

BACKGROUND

Inhibitor of growth 4 (ING4) level was reported to be decreased in head and neck squamous cell carcinoma (HNSC) tissue, however, it is unknown whether and how ING4 participates in regulating the development of oral squamous cell carcinoma (OSCC).

OBJECTIVE

To investigate the role and mechanism of ING4 in OSCC.

METHODS

ING4 was forced up-or down-regulated in two OSCC cell lines, and its effects on the malignant behavior of OSCC cells were investigated in vitro. The ubiquitination level of NF-kB p65 in ING4 upregulated cells was measured by co-immunoprecipitation. Moreover, the effects of ING4 on the methylation level of ALDH1A2 were evaluated by methylation-specific polymerase chain reaction (MSP) assay. The role of ING4 in OSCC growth in vivo was observed in nude mice.

RESULTS

Our results showed that the expression of ING4 in OSCC cell lines was lower than that in normal oral keratinocyte cells. In vitro, ING4 overexpression inhibited the proliferation, migration, and invasion of OSCC cell lines and ING4 silencing exhibited opposite results. We also demonstrated that ING4 overexpression promoted the ubiquitination and degradation of P65 and reduced DNA methyltransferase 1 (DNMT1) expression, and Aldehyde dehydrogenase 1A2 (ALDH1A2) methylation. Moreover, overexpression of p65 rescued the suppression of malignant behavior, induced by ING4 overexpression. In addition, ING4 negatively regulated the growth of OSCC xenograft tumors in vivo.

CONCLUSION

Our data evidenced that ING4 played a tumor-repressing role in OSCC in vivo and in vitro via NF-κB/DNMT1/ALDH1A2 axis.

The role of SPP1 as a prognostic biomarker and therapeutic target in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is one of the most common malignancies and has a low 5-year survival rate. Mounting evidence suggests that oral potentially malignant disorders, such as oral leukoplakia (OLK), may progress to HNSCC. Given that OLK and HNSCC are often insidious and asymptomatic, the identification of markers of OLK malignant transformation and therapeutic targets in HNSCC is critical. Using various online tools and publicly available gene expression datasets, the secreted phosphoprotein 1 gene (SPP1) was identified as a significant differentially expressed gene among OLK, HNSCC, and non-cancerous tissues. SPP1 mRNA levels were elevated in HNSCC tissues and were associated with cancer stage, tumor grade, and human papillomavirus infection status. High SPP1 mRNA levels were correlated with poor overall survival of HNSCC patients. In contrast, SPP1 mutations were not significantly associated with overall survival, although their frequency in HNSCC was very low (0.6%). Furthermore, SPP1 expression levels in HNSCC were positively correlated with the infiltration of CD4⁺ cells, macrophages, neutrophils, and dendritic cells. The study results suggest that SPP1 may represent a diagnostic and prognostic biomarker, as well as a potential therapeutic target in HNSCC.

Hypoxia Pathway Proteins and Their Impact on the Blood Vasculature

Every cell in the body requires oxygen for its functioning, in virtually every animal, and a tightly regulated system that balances oxygen supply and demand is therefore fundamental. The vascular network is one of the first systems to sense oxygen, and deprived oxygen (hypoxia) conditions automatically lead to a cascade of cellular signals that serve to circumvent the negative effects of hypoxia, such as angiogenesis associated with inflammation, tumor development, or vascular disorders. This vascular signaling is driven by central transcription factors, namely the hypoxia inducible factors (HIFs), which determine the expression of a growing number of genes in endothelial cells and pericytes. HIF functions are tightly regulated by oxygen sensors known as the HIF-prolyl hydroxylase domain proteins (PHDs), which are enzymes that hydroxylate HIFs for eventual proteasomal degradation. HIFs, as well as PHDs, represent attractive therapeutic targets under various pathological settings, including those involving vascular (dys)function. We focus on the characteristics and mechanisms by which vascular cells respond to hypoxia under a variety of conditions.

Roles of the tumor suppressor inhibitor of growth family member 4 (ING4) in cancer

Inhibitor of growth family member 4 (ING4) is best known as a tumor suppressor that is frequently downregulated, deleted, or mutated in many cancers. ING4 regulates a broad array of tumor-related processes including proliferation, apoptosis, migration, autophagy, invasion, angiogenesis, DNA repair and chromatin remodeling. ING4 alters local chromatin structure by functioning as an epigenetic reader of H3K4 trimethylation histone marks (H3K4Me3) and regulating gene transcription through directing histone acetyltransferase (HAT) and histone deacetylase (HDAC) protein complexes. ING4 may serve as a useful prognostic biomarker for many cancer types and help guide treatment decisions. This review provides an overview of ING4's central functions in gene expression and summarizes current literature on the role of ING4 in cancer and its possible use in therapy.

MiR-378a-3p as a putative biomarker for hepatocellular carcinoma diagnosis and prognosis: Computational screening with experimental validation

BACKGROUND

Hepatocellular carcinoma (HCC) is a malignant disease with high morbidity and mortality, and the molecular mechanism for the genesis and progression is complex and heterogeneous. Biomarker discovery is crucial for the personalized and precision treatment of HCC. The accumulation of reported microRNA biomarkers makes it possible to combine computational identification with experimental validation to accelerate the discovery of novel biomarker.

RESULTS

In the present work, we applied a rational computer-aided biomarker discovery model to screen for the HCC diagnosis biomarker. Two HCC-associated networks were constructed based on the microRNA and mRNA expression profiles, and the potential microRNA biomarkers were identified based on their unique regulatory and influential power in the network. These putative biomarkers were then experimentally validated. One prominent example among these identified biomarkers is MiR-378a-3p: It was shown to independently regulate several important transcription factors such as PLAGL2 and β-catenin, affecting the β-catenin signaling. Such mechanism may indicate a potential tumor suppressor role of MiR-378a-3p and the impact of its abnormal expression on the cell growth and invasion of HCC.

CONCLUSIONS

A bioinformatics model with network topological and functional characterization was successfully applied to the identification of HCC biomarkers. The predicted microRNA biomarkers were than validated with experiments using human HCC cell lines, model animal, and clinical specimens. The results confirmed the prediction by our proposed model that miR-378a-3p was a putative biomarker for diagnosis and prognosis of HCC.

Influence of metformin on HIF-1 pathway in multiple myeloma

BACKGROUND

Multiple myeloma (MM) is defined as plasma cells malignancy, developing in the bone marrow. At the beginning of the disease, the malignant plasma cells are dependent on bone marrow microenvironment, providing growth and survival factors. Importantly, the recent studies pointed hypoxia as an important factor promoting progression of MM. In particular, hypoxia-triggered HIF-1 signaling was shown to promote chemoresistance, angiogenesis, invasiveness and induction of immature phenotype, suggesting that strategies targeting HIF-1 may contribute to improvement of anti-myeloma therapies.

METHODS

The Western Blot and RT-PCR techniques were applied to analyze the influence of metformin on HIF-1 pathway in MM cells. To evaluate the effect of metformin on the growth of MM cell lines in normoxic and hypoxic conditions the MTT assay was used. The apoptosis induction in metformin treated hypoxic and normoxic cells was verified by Annexin V/PI staining followed by FACS analysis.

RESULTS

Our results showed, for the first time, that metformin inhibits HIF-1 signaling in MM cells. Moreover, we demonstrated the effect of metformin to be mainly oxygen dependent, since the HIF-1 pathway was not significantly affected by metformin in anoxic conditions as well as after application of hypoxic mimicking compound, CoCl₂. Our data also revealed that metformin triggers the growth arrest without inducing apoptosis in either normoxic or hypoxic conditions.

CONCLUSIONS

Taken together, our study indicates metformin as a promising candidate for developing new treatment strategies exploiting HIF-1 signaling inhibition to enhance the overall anti-MM effect of currently used therapies, that may considerably benefit MM patients.

Inhibitor of growth 4 affects hypoxia-induced migration and angiogenesis regulation in retinal pigment epithelial cells

Inhibitor of growth 4 (ING4), a potential tumor suppressor, is implicated in cell migration and angiogenesis. However, its effects on diabetic retinopathy (DR) have not been elucidated. In this study, we aimed to evaluate ING4 expression in normal and diabetic rats and clarify its effects on hypoxia-induced dysfunction in human retinal pigment epithelial (ARPE-19) cells. A Type 1 diabetic model was generated by injecting rats intraperitoneally with streptozotocin and then killed them 4, 8, or 12 weeks later. ING4 expression in retinal tissue was detected using western blot analysis, reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR), and immunohistochemistry assays. After transfection with an ING4 overexpression lentiviral vector or small interfering RNA (siRNA), ARPE-19 migration under hypoxia was tested using wound healing and transwell assays. The angiogenic effect of conditioned medium (CM) from ARPE-19 cells was examined by assessing human retinal endothelial cell (HREC) capillary tube formation. Additionally, western blot analysis and RT-qPCR were performed to investigate the signaling pathways in which ING4, specificity protein 1 (Sp1), matrix metalloproteinase 2 (MMP-2), MMP-9, and vascular endothelial growth factor A (VEGF-A) were involved. Here, we found that ING4 expression was significantly reduced in the diabetic rats' retinal tissue. Silencing ING4 aggravated hypoxia-induced ARPE-19 cell migration. CM collected from ING4 siRNA-transfected ARPE-19 cells under hypoxia promoted HREC angiogenesis. These effects were reversed by ING4 overexpression. Furthermore, ING4 suppressed MMP-2, MMP-9, and VEGF-A expression in an Sp1-dependent manner in hypoxia-conditioned ARPE-19 cells. Overall, our results provide valuable mechanistic insights into the protective effects of ING4 on hypoxia-induced migration and angiogenesis regulation in ARPE-19 cells. Restoring ING4 may be a novel strategy for treating DR.

The Pro-Oncogenic Adaptor CIN85 Acts as an Inhibitory Binding Partner of Hypoxia-Inducible Factor Prolyl Hydroxylase 2

The EGFR adaptor protein, CIN85, has been shown to promote breast cancer malignancy and hypoxia-inducible factor (HIF) stability. However, the mechanisms underlying cancer promotion remain ill defined. Here we show that CIN85 is a novel binding partner of the main HIF-prolyl hydroxylase, PHD2, but not of PHD1 or PHD3. Mechanistically, the N-terminal SRC homology 3 domains of CIN85 interacted with the proline-arginine-rich region within the N-terminus of PHD2, thereby inhibiting PHD2 activity and HIF degradation. This activity is essential in vivo, as specific loss of the CIN85-PHD2 interaction in CRISPR/Cas9-edited cells affected growth and migration properties, as well as tumor growth in mice. Overall, we discovered a previously unrecognized tumor growth checkpoint that is regulated by CIN85-PHD2 and uncovered an essential survival function in tumor cells by linking growth factor adaptors with hypoxia signaling. SIGNIFICANCE: This study provides unprecedented evidence for an oxygen-independent mechanism of PHD2 regulation that has important implications in cancer cell survival. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/79/16/4042/F1.large.jpg.

MicroRNA‑214 upregulates HIF‑1α and VEGF by targeting ING4 in lung cancer cells

Previous reports have indicated a potential link between microRNA (miR)‑214 and hypoxia. In the present study, the biological functions and potential mechanisms of miR‑214 were determined, as well as its correlation with HIF‑1α signaling in non‑small cell lung cancer (NSCLC) cells. Quantitative polymerase chain reaction revealed that miR‑214 expression was upregulated in lung cancer tissues compared with adjacent normal tissues. miR‑214 mimics were transfected into A549 cells, and MTT, colony formation, invasion and wound healing assays were performed. It was demonstrated that miR‑214 mimic transfection promoted the invasion, proliferation and migration of A549 cells. Furthermore, miR‑214 inhibitor transfection decreased H1299 cell invasion, proliferation and migration. Next, the association between miR‑214 expression and the HIF‑1α signaling cascade was examined. It was demonstrated that miR‑214 mimics upregulated the expression of hypoxia‑inducible factor (HIF)‑1α, vascular endothelial growth factor (VEGF), adenylate kinase 3 and matrix metalloproteinase (MMP)2, whereas miR‑214 inhibitor downregulated the expression of these factors. Using prediction software, it was demonstrated that tumor suppressor ING4 was a target of miR‑214. A luciferase reporter assay confirmed that ING4 was a direct target of miR‑214. There was a negative correlation between ING4 and miR‑214 expression in lung cancer tissues. In addition, ING4 siRNA and plasmid was transfected into cells in order to validate its effect on HIF‑1α, MMP2 and VEGF expression. ING4 overexpression downregulated HIF‑1α and its targets MMP2 and VEGF, while ING4 siRNA upregulated HIF‑1α, MMP2 and VEGF. In conclusion, it was demonstrated that miR‑214 targeted ING4 in lung cancer cells, and upregulated the HIF‑1α cascade, leading to MMP2 and VEGF upregulation. This approach may help to clarify the role of miRNA in non‑small lung cancer and may be a new therapeutic target for non‑small lung cancer.

The essential role of tumor suppressor gene ING4 in various human cancers and non-neoplastic disorders

Inhibitor of growth 4 (ING4), a member of the ING family discovered in 2003, has been shown to act as a tumor suppressor and is frequently down-regulated in various human cancers. Numerous published in vivo and in vitro studies have shown that ING4 is responsible for important cancer hallmarks such as pathologic cell cycle arrest, apoptosis, autophagy, contact inhibition, and hypoxic adaptation, and also affects tumor angiogenesis, invasion, and metastasis. These characteristics are typically associated with regulation through chromatin acetylation by binding histone H3 trimethylated at lysine 4 (H3K4me3) and through transcriptional activity of transcription factor P53 and NF-κB. In addition, emerging evidence has indicated that abnormalities in ING4 expression and function play key roles in non-neoplastic disorders. Here, we provide an overview of ING4-modulated chromosome remodeling and transcriptional function, as well as the functional consequences of different genetic variants. We also present the current understanding concerning the role of ING4 in the development of neoplastic and non-neoplastic diseases. These studies offer inspiration for pursuing novel therapeutics for various cancers.

ING4 suppresses hepatocellular carcinoma via a NF-κB/miR-155/FOXO3a signaling axis

The tumor suppressor ING4 has been shown to be reduced in human HCC. The alteration of ING4 contributes to HCC progression. However, its effect in HCC and the potential mechanism is largely unclear. Herein, we found that downregulation of ING4 in HCC tumor tissues was closely associated with cancer staging, tumor size and vascular invasion. Lentivirus-mediated ING4 overexpression significantly inhibited proliferation, migration and invasion, and induced cell cycle G1 phase arrest and apoptosis in MHCC97H human HCC cells. Moreover, overexpression of ING4 dramatically suppressed MHCC97H tumor cell growth and metastasis to lung in vivo in athymic BALB/c nude mice. Mechanistic studies revealed that overexpression of ING4 markedly increased expression of FOXO3a both at the mRNA and protein level as well as enhanced nuclear level and transcriptional activity of FOXO3a in MHCC97H tumor cells. In addition, ING4 repressed transcriptional activity of NF-κB and expression of miR-155 targeting FOXO3a. Knockdown of ING4 exhibited opposing effects in MHCC97L human HCC cells. Interestingly, knockdown of FOXO3a attenuated not only ING4-elicited tumor suppression but also ING4-mediated regulatory effect on FOXO3a downstream targets, confirming that FOXO3a is involved in ING4-directed tumor-inhibitory effect in HCC. Overexpression of miR-155 attenuated ING4-induced upregulation of FOXO3a, whereas inhibition of miR-155 blunted ING4 knockdown-induced reduction of FOXO3a. Furthermore, inhibition of NF-κB markedly impaired ING4 knockdown-induced upregulation of miR-155 and downregulation of FOXO3a. Taken together, our study provided the first compelling evidence that ING4 can suppress human HCC growth and metastasis to a great extent via a NF-κB/miR-155/FOXO3a pathway.

N-methyl-N-nitro-N-nitrosoguanidine-mediated ING4 downregulation contributed to the angiogenesis of transformed human gastric epithelial cells

AIMS

Angiogenesis is associated with the progression and mortality of gastric cancer. Epidemiological evidences indicate that long-term N-nitroso compounds (NOCs) exposure predominantly contributes to the mortality of gastric cancer. Therefore, further reduced mortality of gastric cancer demands to explore the exact mechanisms of NOCs induced angiogenesis. As a tumor suppressor gene, inhibitor of growth protein 4 (ING4) plays an important role in pathological angiogenesis. In this study, we will investigate ING4 expression level in human gastric epithelial cells after the long-term low dose exposure of N-methyl-N-nitro-N-nitrosoguanidine (MNNG) and the pathological impact of MNNG-reduced ING4 on angiogenesis of transformed cells.

MAIN METHODS

The soft agar colony formation assay, Western blotting, immunofluorescence and wound healing assay were used to evaluate the characteristics of transformed cells. HUVEC growth and tube formation assays were performed to test the angiogenic abilities. EMSA, luciferase reporter gene assay, real-time PCR and Western blotting were used to explore the exact mechanism.

KEY FINDINGS

By establishing transformed human gastric epithelial cells via chronic low dose treatment, a gradually ING4 downregulation was observed in the later-stage of MNNG-induced cell transformation. Moreover, we demonstrated that MNNG exposure-reduced ING4 expression significantly resulted into aggravating angiogenesis through increasing the phosphorylation level of NF-κB p65 and subsequently DAN binding activity and regulating the expressions of NF-κB p65 downstream pro-angiogenic genes, MMP-2 and MMP-9.

SIGNIFICANCE

Our findings provided a significant mechanistic insight into angiogenesis of MNNG-transformed human gastric epithelial cell and supported the concept that ING4 may be a relevant therapeutic target for gastric cancer.

NCOA5 promotes proliferation, migration and invasion of colorectal cancer cells via activation of PI3K/AKT pathway

The nuclear receptor coactivator 5 (NCOA5) displays both coactivator and corepressor functions. Previous studies showed that alteration of NCOA5 participates in carcinogenesis and progression. However, its roles in colorectal cancer (CRC) remain unknown. Herein, we demonstrated that expression of NCOA5 in human CRC tissues was notably higher than that in adjacent tissues, which significantly correlated with clinicopathological features such as length of tumor, regional lymph node staging and cancer staging. Knockdown of NCOA5 markedly suppressed proliferation, migration and invasion of SW620 high malignant CRC cells. Silencing of NCOA5 also inhibited in vivo growth of SW620 CRC subcutaneously xenografted tumors in athymic BALB/c nude mice. Meanwhile, Overexpression of NCOA5 facilitated these processes in SW480 low malignant CRC cells. Furthermore, knockdown of NCOA5 induced cell cycle G1 phase arrest in SW620 cells, whereas overexpression of NCOA5 promoted G1 to S phase transition in SW480 cells. Mechanistic studies revealed that NCOA5 upregulated phospho-protein kinase B (p-PKB/AKT), Cyclin D1 and matrix metalloproteinase 9 (MMP9) as well as downregulated P27 in CRC cells. Notably, PI3K inhibitor LY294002 obviously attenuated the effects of NCOA5 on p-AKT, Cyclin D1, P27 and MMP9. Moreover, LY294002 and knockdown of Cyclin D1 or MMP9 remarkably blocked the tumor-promoting activity of NCOA5. Collectively, NCOA5 promoted CRC cell proliferation, migration and invasion by upregulating Cyclin D1 and MMP9 while downregulating P27 to a great extent via activating PI3K/AKT signaling pathway. These findings suggested that NCOA5 exhibits an oncogenic effect in human CRC and represents a novel therapeutic target for CRC.

Expression of ING4 is negatively correlated with cellular proliferation and microvessel density in human glioma

The present study aimed to investigate the associations of tumor inhibitor of growth 4 (ING4) with tumor cell proliferation and microvessel density (MVD) in human glioma. Semi-quantitative reverse transcription polymerase chain reaction, western blotting and immunohistochemistry (IHC) were used to detect the level of ING4 expression in normal brain tissues and glioma tissues of different pathological grades. The cell proliferation index (PI) and the level of MVD were detected using IHC, facilitating the analysis of the correlation between ING4 and cellular proliferation and MVD in human glioma. The expression levels of ING4 mRNA and protein were significantly lower in the glioma tissues compared with the normal brain tissues (P<0.05) and decreased as the pathological grade of the glioma tissue increased (P<0.05). PI was reduced in the ING4 protein positively expressed (ING4⁺) glioma tissues compared with the ING4 protein negatively expressed (ING4^-) glioma tissues (P≤0.01). The level of MVD was significantly higher in the glioma tissues than that in the normal brain tissues (P≤0.01), while the level of MVD decreased in the ING4⁺ glioma tissue compared with the ING4^- glioma tissue (P≤0.001). A Spearman's rank correlation test revealed that ING4 protein expression was negatively correlated with PI and MVD. ING4 might inhibit tumor proliferation and angiogenesis in human glioma. The expression of ING4 was also associated with the pathological grading of the glioma tissue and negatively correlated with cellular proliferation and MVD in human glioma.

Roles of microRNA-330 and Its Target Gene ING4 in the Development of Aggressive Phenotype in Hepatocellular Carcinoma Cells

BACKGROUND

Aberrant expression of microRNAs contributes to tumor growth and progression.

AIMS

This study was designed to explore the prognostic and biological significance of miR-330 in hepatocellular carcinoma (HCC).

METHODS

The expression of miR-330 and its associations with tumor parameters and overall survival were analyzed in HCC patients. The biological functions of miR-330 in HCC cell growth, invasion, and tumorigenesis were investigated. Bioinformatic analysis and luciferase reporter assays were performed to search for potential targets of miR-330.

RESULTS

The miR-330 level was significantly higher in HCCs than in adjacent normal tissues (P = 0.0085). High expression of miR-330 was significantly associated with more aggressive phenotypes and shorter overall survival in HCC. Loss- and gain-of-function studies indicated the favorable effect of miR-330 on tumor cell growth, invasion, and tumorigenesis. Inhibitor of growth 4 (ING4) was identified to be a direct target of miR-330. Overexpression of miR-330 reduced the expression of ING4 in HCC cells. Importantly, restoration of ING4 almost completely reversed the promotion of HCC cell proliferation and invasion by miR-330.

CONCLUSIONS

Altogether, this study demonstrates that upregulation of miR-330 is associated with poor prognosis and contributes to more aggressive phenotypes of HCC. The oncogenic role of miR-330 in HCC is linked to downregulation of ING4.

INGs are potential drug targets for cancer

PURPOSE

The inhibitor of growth (ING) family consists of ING1, ING2, ING3, ING4 and ING5, which function as the type II tumor suppressors. INGs regulate cell proliferation, senescence, apoptosis, differentiation, angiogenesis, DNA repair, metastasis, and invasion by multiple pathways. In addition, INGs increase cancer cell sensitivity for chemotherapy and radiotherapy, while clinical observations show that INGs are frequently lost in some types of cancers. The aim of the study was to summarize the recent progress regarding INGs regulating tumor progression.

METHODS

The literatures of INGs regulating tumor progression were searched and assayed.

RESULTS

The regulating signaling pathways of ING1, ING2, ING3 or ING4 on tumor progression were shown. The mechanisms of INGs on tumor suppression were also assayed.

CONCLUSIONS

This review better summarized the signaling mechanism of INGs on tumor suppression, which provides a candidate therapy strategy for cancers.

Co-expression of ING4 and P53 enhances hypopharyngeal cancer chemosensitivity to cisplatin in vivo

Hypopharyngeal cancer is a distinct type of malignant head and neck tumor, which exhibits low sensitivity to anti-cancer drugs. The importance of developing methods for reducing chemotherapy resistance, and improving and enhancing prognosis has previously been emphasized and is considered a challenge for effective clinical treatment of hypopharyngeal cancer. The current study investigated the effects of co-expression of inhibitor of growth protein 4 (ING4) and P53, a tumor suppressor gene, on chemosensitivity to cisplatin in human hypopharyngeal cancer xenografts in vivo, and the potential molecular mechanisms involved. A tumor model was established by injecting athymic nude mice with FADU human hypopharyngeal cancer cells. Five days after intratumoral and peritumoral injections of an empty adenoviral vector (Ad), Ad-ING4-P53, cisplatin, or a combination of Ad-ING4-P53 and cisplatin (Ad-ING4-P53 + cisplatin) every other day for 5 days, the mice were euthanized and their tumors, livers, and kidneys were removed. The tumor weights were used to calculate the inhibition rate, and the expression levels of ING4 and P53 were detected by reverse transcription-polymerase chain reaction. Additionally, apoptotic cells were detected using terminal deoxynucleotidyl transferase dUTP nick end labeling, and immunohistochemistry determined the levels ING4, P53, B-cell lymphoma-2 (Bcl-2) and Bcl-2 associated X protein (Bax) protein expression. The results demonstrated increased expression of ING4 and P53 in the Ad-ING4-P53 groups compared with PBS and Ad groups, indicating successful introduction of the genes into the tumor cells. Notably, the Ad-ING4-P53 + cisplatin group exhibited a higher inhibition rate compared with the four other groups. The results of immunohistochemistry analysis demonstrated that Bax expression was increased and Bcl-2 was decreased in the Ad-ING4-P53 + cisplatin group. This suggested that the enhanced cisplatin chemosensitivity with Ad-ING4-P53 gene therapy in hypopharyngeal cancer xenografts may be associated with apoptosis induction through upregulation of Bax expression and downregulation of Bcl-2. The results of the present study indicated that gene therapy combined with cisplatin treatment may be a promising treatment for human hypopharyngeal cancer.

Overexpression of Inhibitor of Growth 4 Enhances Radiosensitivity in Non-Small Cell Lung Cancer Cell Line SPC-A1

Inhibitor of growth 4 is a member of the inhibitor of growth family proteins, which is involved in cell apoptosis, migration, invasion, and cell cycle progress. In this study, we investigated the inhibitor of growth 4 level in non-small cell lung cancer tissues and explored the antitumor activity of inhibitor of growth 4 in vitro and in vivo using non-small cell lung cancer cell line SPC-A1 and its underlying molecular mechanisms. We also explored its role on the radiosensitivity in SPC-A1 cells. The level of inhibitor of growth 4 protein was significantly decreased in 28 cases of non-small cell lung cancer tissues in comparison with corresponding noncancerous lung epithelial tissues. Upregulation of inhibitor of growth 4 by plasmid pcDNA3.1-ING4 delivery could suppress proliferation and increase apoptosis of SPC-A1 cells both in vitro and in vivo. Additionally, we found that overexpression of inhibitor of growth 4 in SPC-A1 cell line could lead to a higher Bcl-2/Bax ratio, which might be an important factor in the apoptosis regulation. Furthermore, overexpression of inhibitor of growth 4 enhanced the radiosensitivity of SPC-A1 cells to irradiation. Inhibitor of growth 4 upregulation plus radiotherapy induced synergistic tumor suppression in SPC-A1 xenografts implanted in athymic nude mice. Thus, the restoration of inhibitor of growth 4 function might provide a potential strategy for non-small cell lung cancer radiosensitization.

Mechanism of Histone H3K4me3 Recognition by the Plant Homeodomain of Inhibitor of Growth 3

Aberrant access to genetic information disrupts cellular homeostasis and can lead to cancer development. One molecular mechanism that regulates access to genetic information includes recognition of histone modifications, which is carried out by protein modules that interact with chromatin and serve as landing pads for enzymatic activities that regulate gene expression. The ING3 tumor suppressor protein contains a plant homeodomain (PHD) that reads the epigenetic code via recognition of histone H3 tri-methylated at lysine 4 (H3K4me3), and this domain is lost or mutated in various human cancers. However, the molecular mechanisms targeting ING3 to histones and the role of this interaction in the cell remain elusive. Thus, we employed biochemical and structural biology approaches to investigate the interaction of the ING3 PHD finger (ING3PHD) with the active transcription mark H3K4me3. Our results demonstrate that association of the ING3PHD with H3K4me3 is in the sub-micromolar range (KD ranging between 0.63 and 0.93 μm) and is about 200-fold stronger than with the unmodified histone H3. NMR and computational studies revealed an aromatic cage composed of Tyr-362, Ser-369, and Trp-385 that accommodate the tri-methylated side chain of H3K4. Mutational analysis confirmed the critical importance of Tyr-362 and Trp-385 in mediating the ING3PHD-H3K4me3 interaction. Finally, the biological relevance of ING3PHD-H3K4me3 binding was demonstrated by the failure of ING3PHD mutant proteins to enhance ING3-mediated DNA damage-dependent cell death. Together, our results reveal the molecular mechanism of H3K4me3 selection by the ING3PHD and suggest that this interaction is important for mediating ING3 tumor suppressive activities.

Galectin-1 suppression delineates a new strategy to inhibit myeloma-induced angiogenesis and tumoral growth in vivo

Galectin-1 (Gal-1) is involved in tumoral angiogenesis, hypoxia and metastases. Actually the Gal-1 expression profile in multiple myeloma (MM) patients and its pathophysiological role in MM-induced angiogenesis and tumoral growth are unknown. In this study, we found that Gal-1 expression by MM cells was upregulated in hypoxic conditions and that stable knockdown of hypoxia inducible factor-1α significantly downregulated its expression. Therefore, we performed Gal-1 inhibition using lentivirus transfection of shRNA anti-Gal-1 in human myeloma cell lines (HMCLs), and showed that its suppression modified transcriptional profiles in both hypoxic and normoxic conditions. Interestingly, Gal-1 inhibition in MM cells downregulated proangiogenic genes, including MMP9 and CCL2, and upregulated the antiangiogenic ones SEMA3A and CXCL10. Consistently, Gal-1 suppression in MM cells significantly decreased their proangiogenic properties in vitro. This was confirmed in vivo, in two different mouse models injected with HMCLs transfected with anti-Gal-1 shRNA or the control vector. Gal-1 suppression in both models significantly reduced tumor burden and microvascular density as compared with the control mice. Moreover, Gal-1 suppression induced smaller lytic lesions on X-ray in the intratibial model. Overall, our data indicate that Gal-1 is a new potential therapeutic target in MM blocking angiogenesis.

PHD2: from hypoxia regulation to disease progression

Oxygen represents one of the major molecules required for the development and maintenance of life. An adequate response to hypoxia is therefore required for the functioning of the majority of living organisms and relies on the activation of the hypoxia-inducible factor (HIF) pathway. HIF prolyl hydroxylase domain-2 (PHD2) has long been recognized as the major regulator of this response, controlling a myriad of outcomes that range from cell death to proliferation. However, this enzyme has been associated with more pathways, making the role of this protein remarkably complex under distinct pathologies. While a protective role seems to exist in physiological conditions such as erythropoiesis; the picture is more complex during pathologies such as cancer. Since the regulation of this enzyme and its closest family members is currently considered as a possible therapy for various diseases, understanding the different particular roles of this protein is essential.

Inhibitor of growth 4 suppresses colorectal cancer growth and invasion by inducing G1 arrest, inhibiting tumor angiogenesis and reversing epithelial-mesenchymal transition

Previous studies have found that inhibitor of growth 4 (ING4), a tumor suppressor, is reduced in human colorectal cancer (CRC), and is inversely correlated with clinical Dukes' stage, histological grade, lymph node metastasis and microvessel density (MVD). However, its underlying mechanism remains undetermined. In the present study, we analyzed ING4 expression in a panel of human CRC cells using low (LS174T and SW480) and high (LoVo and SW620) metastatic cell lines. We demonstrated that both the low and high metastatic CRC cells exhibited a lower level of ING4 compared to the level in normal human colorectal mucous epithelial FHC cells. Furthermore, ING4 expression in high metastatic CRC cells was less than that in low metastatic CRC cells. We then generated a lentivirus construct expressing ING4 and green fluorescent protein (GFP), established a ING4-stably transgenic LoVo CRC cell line, and investigated the effect of lentiviral-mediated ING4 expression on high metastatic LoVo CRC cells. Gain-of-function studies revealed that ING4 significantly inhibited LoVo CRC cell growth and invasion in vitro and induced cell cycle G1 phase arrest. Moreover, ING4 obviously suppressed LoVo CRC subcutaneously xenografted tumor growth and reduced tumor MVD in vivo in athymic BALB/c nude mice. Mechanistically, ING4 markedly upregulated P21 and E-cadherin but downregulated cyclin E, interleukin (IL)-6, IL-8, vascular endothelial growth factor (VEGF), Snail1, N-cadherin and vimentin in the LoVo CRC cells. Our data provide compelling evidence that i) ING4 suppresses CRC growth possibly via induction of G1 phase arrest through upregulation of P21 cyclin-dependent kinase (CDK) inhibitor and downregulation of cyclin E as well as inhibition of tumor angiogenesis through reduction of IL-6, IL-8 and VEGF proangiogenic factors; ii) ING4 inhibits CRC invasion and metastasis probably via a switch from mesenchymal marker N-cadherin to epithelial marker E-cadherin through downregulation of Snail1 epithelial-mesenchymal transition (EMT)-inducing transcription factor (EMT-TF).

Chetomin, targeting HIF-1α/p300 complex, exhibits antitumour activity in multiple myeloma

Background:

Multiple myeloma (MM) is an incurable clonal plasma cell malignancy. The constitutive expression of HIF-1α in MM suggests that inhibition of HIF-1α-mediated transcription represents an interesting target in MM.

Methods:

As p300 is a crucial co-activator of hypoxia-inducible transcription, disrupting the complex HIF-1α/p300 to target HIF activity appears to be an attractive strategy.

Results:

We reported that chetomin, an inhibitor of HIF-1α/p300 interaction, exhibits antitumour activity in human myeloma cell lines and primary MM cells from patients.

Conclusions:

Our data suggest that chetomin may be of clinical value in MM and especially for patients characterised by a high EP300/HIF-1α expression and a poor prognosis.

Inhibitor of growth-4 is a potential target for cancer therapy

The inhibitor of growth-4 (ING-4) belongs to the inhibitor of growth (ING) family that is a type II tumor suppressor gene including five members (ING1-5). As a tumor suppressor, ING4 inhibits tumor growth, invasion, and metastasis by multiple signaling pathways. In addition to that, ING4 can facilitate cancer cell sensitivity to chemotherapy and radiotherapy. Although ING4 loss is observed for many types of cancers, increasing evidences show that ING4 can be used for gene therapy. In this review, the recent progress of ING4 regulating tumorigenesis is discussed.

Synergistic tumor suppression by adenovirus-mediated ING4/PTEN double gene therapy for gastric cancer

Both inhibitor of growth 4 (ING4) and phosphatase and tensin homolog (PTEN) have been shown to be strong candidate tumor suppressors. However, the combined efficacy of ING4 and PTEN for human gastric cancer remains to be determined. In this report, we constructed a multiple promoter expression cassette-based recombinant adenovirus coexpressing ING4 and PTEN (AdVING4/PTEN), assessed the combined effects of AdVING4/PTEN on gastric cancer using wild-type p53 AGS and SNU-1 human gastric cancer cell lines, and elucidated its underlying mechanisms. We found that AdVING4/PTEN-induced synergistic growth inhibition and apoptosis in vitro AGS or SNU-1 tumor cells and in vivo AGS xenografted tumors subcutaneously inoculated in athymic BALB/c nude mice. Mechanistically, AdVING4/PTEN exhibited an enhanced effect on upregulation of p53, Ac-p53 (K382), P21, Bax, PUMA, Noxa, cleaved Caspase-9, cleaved Caspase-3 and cleaved PARP as well as downregulation of Bcl-2 in vitro and in vivo. In addition, AdVING4/PTEN synergistically downregulated tumor vessel CD34 expression and reduced microvessel density, and additively inhibited vascular endothelial growth factor (VEGF) expression in vivo. The synergistic tumor suppression elicited by AdVING4/PTEN was closely associated with the synergistic induction of apoptosis possibly via enhancement of endogenous p53 responses through cooperatively facilitating p53's stability and acetylation, and the synergistic inhibition of tumor angiogenesis probably via overlapping reduction of VEGF through cooperatively downregulating hypoxia inducible factor-1α's level and transcription activity. Thus, our results indicate that cancer gene therapy combining ING4 and PTEN may constitute a novel and effective therapeutic modality for human gastric cancer and other cancers.

Adenovirus-mediated p53 and ING4 gene co-transfer elicits synergistic antitumor effects through enhancement of p53 acetylation in breast cancer

Multigene-based combination therapy may be an effective practice in cancer gene therapy. Substantial studies have demonstrated that tumor suppressor p53 acetylation is indispensable for p53 activation. Inhibitor of growth 4 (ING4), as a novel tumor suppressor, is capable of remarkably enhancing p53 acetylation and its transcriptional activity. Hence, we assumed that combined treatment of p53 and ING4 double tumor suppressors would exhibit enhanced antitumor effects. The combined therapeutic efficacy of p53 and ING4 for human cancers has not been previously reported. We thus generated multiple promoter expression cassette-based recombinant adenovirus-co-expressing ING4 and p53 double tumor suppressor genes (AdVING4/p53), evaluated the combined effects of AdVING4/p53 on breast cancer using the MDA-MB-231 (mutant p53) human breast cancer cell line, and also elucidated its underlying molecular mechanisms. We demonstrated that AdVING4/p53-mediated p53 and ING4 co-expression induced synergistic growth inhibition and apoptosis as well as enhanced effects on upregulation of acetylated p53, P21, Bax, PUMA, Noxa, cleaved caspase-9, cleaved caspase-3 and cleaved PARP, and downregulation of Bcl-2, CD31 and microvessel density (MVD) in MDA-MB-231 breast cancer in vitro and/or in vivo subcutaneous (s.c.) xenografted tumors. The synergistic antitumor activity elicited by AdVING4/p53 was closely associated with the enhanced activation of the intrinsic apoptotic pathway and synergistic inhibition of tumor angiogenesis, very possibly via ING4-mediated enhancement of p53 acetylation and activity. Thus, our results indicate that cancer gene therapy combining two or more tumor suppressors such as p53 and ING4 may constitute a novel and effective therapeutic modality for human breast cancer and other cancers.

Experimental studies on the inhibition of adenovirus-ING4-OSM therapy on nasopharyngeal carcinoma proliferation in vitro and in vivo

In the present study, the effects of the co-transfer of the tumor growth inhibitor 4 gene (ING4) together with the Oncostatin M (OSM) were investigated on tumor regression and subsequent tumor recurrence. We constructed a recombinant adenovirus carrying ING4 and OSM, which could induce high-level expression of these three genes in NPC CNE-1 cells. Ad-ING4, Ad-OSM and Ad-ING4-OSM infection all inhibited the growth of CNE-1 cells in vitro, while the Ad-ING4-OSM exerted the strongest inhibitory effect. In CNE-1 xenograft tumor models mice, an intratumoral injection of Ad-ING4, Ad-OSM and Ad-ING4-OSM resulted in a reduced tumor burden, compared to normal saline controls. Therefore, we suggested that the introduction of adenovirus-mediated ING4 and OSM genes could synergistically decrease the recurrence or metastases and develop a control of NPC tumors, which advocate a promising therapeutic future in NPC treatment.

Therapeutic targeting of hypoxia and hypoxia-inducible factor 1 alpha in multiple myeloma

Multiple myeloma (MM) is a clonal B-cell malignancy characterized by accumulation of malignant plasma cells (PCs) within the bone marrow (BM). The PCs are in close contact with stromal cells, which secrete growth factors and cytokines, promoting tumor cell growth and survival. Despite the availability of new drugs with immunomodulatory properties targeting the neoplastic clone and its microenvironment, MM is still an incurable disease, with patients experiencing subsequent phases of remission and relapse, eventually leading to disease resistance and patient death. It is now well established that the MM BM microenvironment is hypoxic, a condition required for the activation of the hypoxia-inducible factor 1 alpha (HIF-1α). It has been shown that HIF-1α is constitutively expressed in MM even in normoxic conditions, suggesting that HIF-1α suppression might be part of a therapeutic strategy. Constitutively activated HIF-1α enhances neovascularization, increases glucose metabolism, and induces the expression of antiapoptotic proteins. HIF-1α is thought to be one of the most important molecular targets in the treatment of cancer, and a variety of chemical inhibitors for HIF-1α have been developed to date. This review examines the role of HIF-1α in MM and recent developments in harnessing the therapeutic potential of HIF-1α inhibition in MM.

Recombinant ING4 suppresses the migration of SW579 thyroid cancer cells via epithelial to mesenchymal transition

Thyroid cancer is a common endocrine malignancy that has rapidly increased in global incidence. Inhibitor of growth 4 (ING4) has been identified in various types of carcinoma; however, to the best of our knowledge, no previous studies have investigated the effects of ING4 on thyroid cancer. In the present study, SW579 thyroid cancer cells were treated with recombinant ING4 protein, and the results confirmed that recombinant ING4 protein was able to reduce the rate of proliferation, increase the rate of apoptosis and inhibit the mobility of SW579 cells. These results were obtained using a colony formation, fluoroscein isothiocyanate/propidium iodide double staining and Transwell assays, respectively. Furthermore, in the western blot analysis assays, ING4 was demonstrated to inhibit the Wnt/β catenin signaling pathway and epithelial to mesenchymal transition (EMT). Therefore, the present study demonstrated the antitumor activities of recombinant ING4 and identified ING4 could inhibit EMT in thyroid cancer cell. However, additional studies are required to confirm these results in other cell types.

ING3 protein expression profiling in normal human tissues suggest its role in cellular growth and self-renewal

Members of the INhibitor of Growth (ING) family of proteins act as readers of the epigenetic code through specific recognition of the trimethylated form of lysine 4 of histone H3 (H3K4Me3) by their plant homeodomains. The founding member of the family, ING1, was initially identified as a tumor suppressor with altered regulation in a variety of cancer types. While alterations in ING1 and ING4 levels have been reported in a variety of cancer types, little is known regarding ING3 protein levels in normal or transformed cells due to a lack of reliable immunological tools. In this study we present the characterization of a new monoclonal antibody we have developed against ING3 that specifically recognizes human and mouse ING3. The antibody works in western blots, immunofluorescence, immunoprecipitation and immunohistochemistry. Using this antibody we show that ING3 is most highly expressed in small intestine, bone marrow and epidermis, tissues in which cells undergo rapid proliferation and renewal. Consistent with this observation, we show that ING3 is expressed at significantly higher levels in proliferating versus quiescent epithelial cells. These data suggest that ING3 levels may serve as a surrogate for growth rate, and suggest possible roles for ING3 in growth and self renewal and related diseases such as cancer.

Hypoxia inducible factor-1 alpha as a therapeutic target in multiple myeloma

The increasing importance of hypoxia-inducible factor-1α (HIF-1α) in tumorigenesis raises the possibility that agents which specifically inhibit this transcription factor, would provide significant therapeutic benefit. The constitutive expression of HIF-1α in about 35% of Multiple Myeloma (MM) patients suggests HIF-1α suppression might be part of a therapeutic strategy. Accordingly, we explored the effect of EZN-2968, a small 3rd generation antisense oligonucleotide against HIF-1α, in a panel of MM cell lines and primary patients samples. Here, we demonstrated that EZN-2968 is highly specific for HIF-1α mRNA and that exposure of MM cells to EZN-2968 resulted in an efficient and homogeneous loading of the cells showing a long lasting low HIF-1α protein level. In MM cells, HIF-1α suppression induced a permanent cell cycle arrest by prolonging S-phase through cyclin A modulation and in addition it induced a mild apoptotic cell death. Moreover, HIF-1α suppression caused a metabolic shift that leaded to increased production of ATP by oxidative phosphorylation (i.e. Warburg effect reversion), that was confirmed by the observed mitochondrial membrane potential decrease. These results show that HIF-1α is an important player in MM homeostasis and that its inhibition by small antisense oligonucleotides provides a rationale for novel therapeutic strategy to improving MM treatment.

Targeting of multiple myeloma-related angiogenesis by miR-199a-5p mimics: in vitro and in vivo anti-tumor activity

Multiple myeloma (MM) cells induce relevant angiogenic effects within the human bone marrow milieu (huBMM) by the aberrant expression of angiogenic factors. Hypoxia triggers angiogenic events within the huBMM and the transcription factor hypoxia-inducible factor-1α (HIF-1α) is over-expressed by MM cells. Since synthetic miR-199a-5p mimics negatively regulates HIF-1α, we here investigated a miRNA-based therapeutic strategy against hypoxic MM cells. We indeed found that enforced expression of miR-199a-5p led to down-modulated expression of HIF-1α as well as of other pro-angiogenic factors such as VEGF-A, IL-8, and FGFb in hypoxic MM cells in vitro. Moreover, miR-199a-5p negatively affected MM cells migration, while it increased the adhesion of MM cells to bone marrow stromal cells (BMSCs) in hypoxic conditions. Furthermore, transfection of MM cells with miR-199a-5p significantly impaired also endothelial cells migration and down-regulated the expression of endothelial adhesion molecules such as VCAM-1 and ICAM-1. Finally, we identified a hypoxia/AKT/miR-199a-5p loop as a potential molecular mechanism responsible of miR-199a-5p down-regulation in hypoxic MM cells. Taken together our results indicate that miR-199a-5p has an important role for the pathogenesis of MM and support the hypothesis that targeting angiogenesis via a miRNA/HIF-1α pathway may represent a novel potential therapeutical approach for this still lethal disease.

HIF-1α inhibition blocks the cross talk between multiple myeloma plasma cells and tumor microenvironment

Multiple myeloma (MM) is a malignant disorder of post-germinal center B cells, characterized by the clonal proliferation of malignant plasma cells (PCs) within the bone marrow (BM). The reciprocal and complex interactions that take place between the different compartments of BM and the MM cells result in tumor growth, angiogenesis, bone disease, and drug resistance. Given the importance of the BM microenvironment in MM pathogenesis, we investigated the possible involvement of Hypoxia-Inducible transcription Factor-1 alpha (HIF-1α) in the PCs-bone marrow stromal cells interplay. To test this hypothesis, we used EZN-2968, a 3rd generation antisense oligonucleotide against HIF-1α, to inhibit HIF-1α functions. Herein, we provide evidence that the interaction between MM cells and BM stromal cells is drastically reduced upon HIF-1α down-modulation. Notably, we showed that upon exposure to HIF-1α inhibitor, neither the incubation with IL-6 nor the co-culture with BM stromal cells were able to revert the anti-proliferative effect induced by EZN-2968. Moreover, we observed a down-modulation of cytokine-induced signaling cascades and a reduction of MM cells adhesion capability to the extracellular matrix proteins in EZN-2968-treated samples. Taken together, these results strongly support the concept that HIF-1α plays a critical role in the interactions between bone BM cells and PCs in Multiple Myeloma.

Molecular mechanisms of action and therapeutic uses of pharmacological inhibitors of HIF-prolyl 4-hydroxylases for treatment of ischemic diseases

SIGNIFICANCE

In this review, we have discussed the efficacy and effect of small molecules that act as prolyl hydroxylase domain inhibitors (PHDIs). The use of these compounds causes upregulation of the pro-angiogenic factors and hypoxia inducible factor-1α and -2α (HIF-1α and HIF-2α) to enhance angiogenic, glycolytic, erythropoietic, and anti-apoptotic pathways in the treatment of various ischemic diseases responsible for significant morbidity and mortality in humans.

RECENT ADVANCES

Sprouting of new blood vessels from the existing vasculature and surgical intervention, such as coronary bypass and stent insertion, have been shown to be effective in attenuating ischemia. However, the initial reentry of oxygen leads to the formation of reactive oxygen species that cause oxidative stress and result in ischemia/reperfusion (IR) injury. This apparent "oxygen paradox" must be resolved to combat IR injury. During hypoxia, decreased activity of PHDs initiates the accumulation and activation of HIF-1α, wherein the modulation of both PHD and HIF-1α appears as promising therapeutic targets for the pharmacological treatment of ischemic diseases.

CRITICAL ISSUES

Research on PHDs and HIFs has shown that these molecules can serve as therapeutic targets for ischemic diseases by modulating glycolysis, erythropoiesis, apoptosis, and angiogenesis. Efforts are underway to identify and synthesize safer small-molecule inhibitors of PHDs that can be administered in vivo as therapy against ischemic diseases.

FUTURE DIRECTIONS

This review presents a comprehensive and current account of the existing small-molecule PHDIs and their use in the treatment of ischemic diseases with a focus on the molecular mechanisms of therapeutic action in animal models.

Role of hypoxia-inducible factors in breast cancer metastasis

Human breast tumors contain regions of hypoxia in which cells that are located far from a functional blood vessel have significantly reduced oxygen concentrations when compared with normal mammary tissue. Breast cancer cells adapt to hypoxic conditions by increasing levels of hypoxia-inducible factors (HIFs), which induce the expression of multiple genes involved in angiogenesis, glucose utilization, resistance to oxidative stress, cell proliferation, resistance to apoptosis, invasion and metastasis. Breast cancer patients with increased HIF expression levels in primary tumor biopsies are at increased risk of metastasis. This is an important finding since 90% of breast cancer deaths are the result of metastasis, primarily to the bone, lungs, liver, brain and regional lymph nodes. Although the prognostic significance of reduced oxygen levels in primary breast tumors of cancer patients is well recognized, the mechanisms underlying hypoxia-induced, HIF-dependent breast cancer metastasis are just beginning to be uncovered. Recent studies have implicated HIF target genes in every step of the metastatic process. Drugs, such as digoxin, show the potential therapeutic effects of blocking HIF activity by decreasing primary tumor growth, vascularization, invasion and metastasis in animal models of breast cancer.

Low ING4 protein expression detected by paraffin-section immunohistochemistry is associated with poor prognosis in untreated patients with gastrointestinal stromal tumors

BACKGROUND

Inhibitor of growth 4 (ING4) has deserved attention as a tumor suppressor gene in many malignant tumors. In our study, we investigated ING4 immunoexpression in gastrointestinal stromal tumors (GISTs) and its prognostic value.

METHOD

The expression of ING4 and Ki67 was investigated in 41 samples of various risk gastrointestinal stromal tumors by immunohistochemical technique. The associations of ING4 expression and clinicopathological parameters, and prognosis of the patients, were analyzed by multivariate Cox regression analysis.

RESULTS

ING4 expression showed a decreased trend from lower-risk to high-risk gastrointestinal stromal tumors, and an opposite trend for Ki67 expression. In lower-risk tumors, it was found the expression level of ING4 was 78.95 % ± 27.90 % and that of Ki67 was 4.42 % ± 3.75 %. However, in high-risk tumors, the expression level of ING4 was 9.23 % ± 7.66 % and that of Ki67 was 18.50 % ± 9.09 %. There was a strongly negative correlation between the expression levels of ING4 and Ki67. A significant difference was observed in the expression of ING4 between invasion and non-invasion (p < 0.001). The expression of ING4 was markedly correlated with tumor size (p < 0.001), mitotic index (p < 0.001), tumor necrosis (p = 0.021), invasion (p < 0.001), recurrence and metastasis (p = 0.021), and mortality (p < 0.001).

CONCLUSION

The low expression level of ING4 protein was correlated with high-risk GISTs. ING4 might be involved in the progression of GISTs and inhibit its invasion. ING4 might be one of the prognostic indicators in GISTs.

HIF-1α of bone marrow endothelial cells implies relapse and drug resistance in patients with multiple myeloma and may act as a therapeutic target

PURPOSE

To investigate the role of hypoxia-inducible factor-1α (HIF-1α) in angiogenesis and drug resistance of bone marrow endothelial cells of patients with multiple myeloma.

EXPERIMENTAL DESIGN

HIF-1α mRNA and protein were evaluated in patients with multiple myeloma endothelial cells (MMEC) at diagnosis, at relapse after bortezomib- or lenalidomide-based therapies or on refractory phase to these drugs, at remission; in endothelial cells of patients with monoclonal gammapathies of undetermined significance (MGUS; MGECs), and of those with benign anemia (controls). The effects of HIF-1α inhibition by siRNA or panobinostat (an indirect HIF-1α inhibitor) on the expression of HIF-1α proangiogenic targets, on MMEC angiogenic activities in vitro and in vivo, and on overcoming MMEC resistance to bortezomib and lenalidomide were studied. The overall survival of the patients was also observed.

RESULTS

Compared with the other endothelial cell types, only MMECs from 45% of relapsed/refractory patients showed a normoxic HIF-1α protein stabilization and activation that were induced by reactive oxygen species (ROS). The HIF-1α protein correlated with the expression of its proangiogenic targets. The HIF-1α inhibition by either siRNA or panobinostat impaired the MMECs angiogenesis-related functions both in vitro and in vivo and restored MMEC sensitivity to bortezomib and lenalidomide. Patients with MMECs expressing the HIF-1α protein had shorter overall survival.

CONCLUSIONS

The HIF-1α protein in MMECs may induce angiogenesis and resistance to bortezomib and lenalidomide and may be a plausible target for the antiangiogenic management of patients with well-defined relapsed/refractory multiple myeloma. It may also have prognostic significance.

Microvesicle-delivery miR-150 promotes tumorigenesis by up-regulating VEGF, and the neutralization of miR-150 attenuate tumor development

Tumor-associated macrophages (TAMs) mostly exhibit M2-like (alternatively activated) properties and play positive roles in angiogenesis and tumorigenesis. Vascular endothelial growth factor (VEGF) is a key angiogenic factor. During tumor development, TAMs secrete VEGF and other factors to promote angiogenesis; thus, anti-treatment against TAMs and VEGF can repress cancer development, which has been demonstrated in clinical trials and on an experimental level. In the present work, we show that miR-150 is an oncomir because of its promotional effect on VEGF. MiR-150 targets TAMs to up-regulate their secretion of VEGF in vitro. With the utilization of cell-derived vesicles, named microvesicles (MVs), we transferred antisense RNA targeted to miR-150 into mice and found that the neutralization of miR-150 down-regulates miR-150 and VEGF levels in vivo and attenuates angiogenesis. Therefore, we proposed the therapeutic potential of neutralizing miR-150 to treat cancer and demonstrated a novel, natural, microvesicle-based method for the transfer of nucleic acids.

ING4 regulates JWA in angiogenesis and their prognostic value in melanoma patients

Background:

We previously showed that inhibitor of growth family member 4 (ING4) inhibits melanoma angiogenesis, and JWA suppresses the metastasis of melanoma cells. As angiogenesis is essential for tumour metastasis, further investigation of the function of ING4 and JWA in melanoma angiogenesis is needed, and their prognostic value are of great interest.

Methods:

Western blot, tube-formation assays and luciferase assays were used to investigate the correlation between ING4 and JWA in melanoma angiogenesis. JWA and integrin-linked kinase (ILK) expression was determined on a tissue microarray constructed from 175 biopsies.

Results:

ING4 promoted JWA expression by activating JWA promoter. Furthermore, the regulation of growth and tube formation of endothelial cells by ING4 was partially JWA dependent. Also, ING4 inhibited the ILK-induced angiogenesis signalling pathway via JWA. Moreover, reduced JWA, or increased ILK, expression was closely associated with 5-year disease-specific survival of melanoma patients (P=0.001 and 0.007, respectively). There was also a positive correlation between ING4 and JWA yet a negative correlation between ING4 and ILK. Importantly, their concomitant expressions were significantly related to 5-year survival of melanoma patients (P=0.002 and 0.003, respectively).

Conclusion:

JWA has an important role in ING4-regulated melanoma angiogenesis, and ING4/JWA/ILK are promising prognostic markers and may be used as anti-angiogenic therapeutic targets for melanoma.

Tumor suppressor ING4 overexpression contributes to proliferation and invasion inhibition in gastric carcinoma by suppressing the NF-κB signaling pathway

There is growing evidence that inhibitor of growth 4 (ING4) plays a pivotal role in development and progression of multiple different tumors; however, its precise function in gastric carcinoma remains to be elucidated. In the present study, we investigated ING4 level in gastric carcinoma tissues and cells, and preliminarily elucidated the role of ING4 in the proliferation and invasion of gastric carcinoma. The results demonstrated that expressions of ING4 mRNA and protein in gastric carcinoma tissues and cells were significantly lower than those in normal tissues and cells (P < 0.05). ING4 level in gastric carcinoma cells stably expressing ING4 was markedly higher than those in untreated group and empty vector pcDNA3.1 group (P < 0.05). Elevated ING4 level resulted in the inhibition of proliferation and invasion in three of gastric carcinoma cell lines MKN-28, SGC-7901 and MKN-45. Most notably, increased ING4 level evidently evoked the down-regulation of p65, p-IκBα, MMP-9 and uPA proteins and the up-regulation of IκBα protein. Our results presented herein suggest that ING4 level elevation mediated proliferation and invasion inhibition may be tightly associated with the suppression of NF-κB signaling pathway.

ING4 regulates a secretory phenotype in primary fibroblasts with dual effects on cell proliferation and tumor growth

ING proteins have an essential role in the control of a variety of cellular functions whose deregulation is associated with tumor formation and dissemination, such as proliferation, apoptosis, senescence or invasion. Accordingly, loss of function of ING proteins is a frequent event in many types of human tumors. In this report, we have studied the function of ING4, a member of the ING family of tumor suppressors, in the context of normal, non-transformed primary fibroblasts. We show that ING4 negatively regulates cell proliferation in this cell type. The antiproliferative action of ING4 requires its ability to recognize chromatin marks, it is p53-dependent at least in part, and it is lost in an ING4 cancer-associated mutant. Gene expression analysis shows that ING4 regulates the expression and release of soluble factors of the chemokine family. The secretory phenotype regulated by ING4 in primary fibroblasts displays a selective paracrine effect on proliferation, fostering the division of tumor cells, while inhibiting division in primary fibroblasts. Consistently, ING4-expressing fibroblasts promoted tumor growth in vivo in co-injection tumorigenesis assays. Collectively, our results show that ING4 not only can regulate the proliferation of primary non-transformed human fibroblasts, but also orchestrates a secretory phenotype in these cells that promotes tumor cell proliferation in vitro and in vivo. These findings support a critical role for ING4 expression in normal cells in the non-cell-autonomous regulation of tumor growth.