Role of Hypoxia-inducible factor-1 alpha and Survivin in colorectal carcinoma progression

Changes in the Expression of Genes Regulating the Response to Hypoxia, Inflammation, Cell Cycle, Apoptosis, and Epithelial Barrier Functioning during Colitis-Associated Colorectal Cancer Depend on Individual Hypoxia Tolerance

One of the factors contributing to colorectal cancer (CRC) development is inflammation, which is mostly hypoxia-associated. This study aimed to characterize the morphological and molecular biological features of colon tumors in mice that were tolerant and susceptible to hypoxia based on colitis-associated CRC (CAC). Hypoxia tolerance was assessed through a gasping time evaluation in a decompression chamber. One month later, the animals were experimentally modeled for colitis-associated CRC by intraperitoneal azoxymethane administration and three dextran sulfate sodium consumption cycles. The incidence of tumor development in the distal colon in the susceptible to hypoxia mice was two times higher and all tumors (100%) were represented by adenocarcinomas, while in the tolerant mice, only 14% were adenocarcinomas and 86% were glandular intraepithelial neoplasia. The tumor area assessed on serially stepped sections was statistically significantly higher in the susceptible animals. The number of macrophages, CD3-CD19+, CD3+CD4+, and NK cells in tumors did not differ between animals; however, the number of CD3+CD8+ and vimentin+ cells was higher in the susceptible mice. Changes in the expression of genes regulating the response to hypoxia, inflammation, cell cycle, apoptosis, and epithelial barrier functioning in tumors and the peritumoral area depended on the initial mouse's hypoxia tolerance, which should be taken into account for new CAC diagnostics and treatment approaches development.

Isthmin-1 promotes growth and progression of colorectal cancer through the interaction with EGFR and YBX-1

While previous studies have indicated the involvement of Isthmin 1 (ISM1), a secreted protein, in cancer development, the precise mechanisms have remained elusive. In this study, we unveiled that ISM1 is significantly overexpressed in both the blood and tissue samples of colorectal cancer (CRC) patients, correlating with their poor prognosis. Functional experiments demonstrated that enforced ISM1 expression significantly enhances CRC proliferation, migration, invasion and tumor growth. Notably, our investigation reveals an interaction of ISM1 with epidermal growth factor receptor (EGFR), a member of the receptor tyrosine kinase (RTK) family of CRC cells. The binding of ISM1 triggered EGFR activation and initiate downstream signaling pathways. Meanwhile, intracellular ISM1 interacted with Y-box binding protein 1 (YBX1), enhancing its transcriptional regulation on EGFR. Furthermore, our research uncovered the regulation of ISM1 expression by the hypoxia-inducible transcription factor HIF-1α in CRC cells. Mechanistically, we identified HIF-1α as a direct regulator of ISM1, binding to a hypoxia response element on its promoter. This novel mechanism illuminated potential therapeutic targets, offering insights into restraining HIF-1α/ISM1/EGFR-driven CRC progression and metastasis.

Resveratrol Modulates Chemosensitisation to 5-FU via β1-Integrin/HIF-1α Axis in CRC Tumor Microenvironment

Frequent development of resistance to chemotherapeutic agents such as 5-flourouracil (5-FU) complicates the treatment of advanced colorectal cancer (CRC). Resveratrol is able to utilize β1-integrin receptors, strongly expressed in CRC cells, to transmit and exert anti-carcinogenic signals, but whether it can also utilize these receptors to overcome 5-FU chemoresistance in CRC cells has not yet been investigated. Effects of β1-integrin knockdown on anti-cancer capabilities of resveratrol and 5-FU were investigated in HCT-116 and 5-FU-resistant HCT-116R CRC tumor microenvironment (TME) with 3D-alginate as well as monolayer cultures. Resveratrol increased CRC cell sensitivity to 5-FU by reducing TME-promoted vitality, proliferation, colony formation, invasion tendency and mesenchymal phenotype including pro-migration pseudopodia. Furthermore, resveratrol impaired CRC cells in favor of more effective utilization of 5-FU by down-regulating TME-induced inflammation (NF-kB), vascularisation (VEGF, HIF-1α) and cancer stem cell production (CD44, CD133, ALDH1), while up-regulating apoptosis (caspase-3) that was previously inhibited by TME. These anti-cancer mechanisms of resveratrol were largely abolished by antisense oligonucleotides against β1-integrin (β1-ASO) in both CRC cell lines, indicating the particular importance of β1-integrin receptors for the 5-FU-chemosensitising effect of resveratrol. Lastly, co-immunoprecipitation tests showed that resveratrol targets and modulates the TME-associated β1-integrin/HIF-1α signaling axis in CRC cells. Our results suggest for the first time the utility of the β1-integrin/HIF-1α signaling axis related to chemosensitization and overcoming chemoresistance to 5-FU in CRC cells by resveratrol, underlining its potential supportive applications in CRC treatment.

HypoxaMIRs: Key Regulators of Hallmarks of Colorectal Cancer

Hypoxia in cancer is a thoroughly studied phenomenon, and the logical cause of the reduction in oxygen tension is tumor growth itself. While sustained hypoxia leads to death by necrosis in cells, there is an exquisitely regulated mechanism that rescues hypoxic cells from their fatal fate. The accumulation in the cytoplasm of the transcription factor HIF-1α, which, under normoxic conditions, is marked for degradation by a group of oxygen-sensing proteins known as prolyl hydroxylases (PHDs) in association with the von Hippel-Lindau anti-oncogene (VHL) is critical for the cell, as it regulates different mechanisms through the genes it induces. A group of microRNAs whose expression is regulated by HIF, collectively called hypoxaMIRs, have been recognized. In this review, we deal with the hypoxaMIRs that have been shown to be expressed in colorectal cancer. Subsequently, using data mining, we analyze a panel of hypoxaMIRs expressed in both normal and tumor tissues obtained from TCGA. Finally, we assess the impact of these hypoxaMIRs on cancer hallmarks through their target genes.

Regulation of Transactivation at C-TAD Domain of HIF-1α by Factor-Inhibiting HIF-1α (FIH-1): A Potential Target for Therapeutic Intervention in Cancer

Hypoxia-inducible factor-1alpha (HIF-1α) is a major transcription factor that adapts to low oxygen homeostasis and regulates the expression of several hypoxic genes, which aid in cancer survival and development. It has recently piqued the interest of translational researchers in the disciplines of cancer sciences. Hypoxia triggers an ample adaptive mechanism mediated via the HIF-1α transcriptional domain. Anaerobic glycolysis, angiogenesis, metastasis, and mitophagy are adaptive mechanisms that support tumor survival by promoting oxygen supply and regulating oxygen demand in hypoxic tumor cells. Throughout this pathway, the factor-inhibiting HIF-1α is a negative regulator of HIF-1α leading to its hydroxylation at the C-TAD domain of HIF-1α under normoxia. Thus, hydroxylated HIF-1α is unable to proceed with the transcriptional events due to interference in binding of C-TAD and CBP/p300. From this review, we can hypothesize that remodeling of FIH-1 activity is a unique mechanism that decreases the transcriptional activity of HIF-1α and, as a result, all of its hypoxic consequences. Hence, this review manuscript details the depth of knowledge of FIH-1 on hypoxia-associated cellular and molecular events, a potential strategy for targeting hypoxia-induced malignancies.

BRET analysis reveals interaction between the lysophosphatidic acid receptor LPA2 and the lysophosphatidylinositol receptor GPR55 in live cells

Lysophosphatidic acid (LPA) and lysophosphatidylinositol bind to the G protein-coupled receptors (GPCRs) LPA and GPR55, respectively. LPA₂ , a type 2 LPA receptor, and GPR55 are highly expressed in colon cancer and involved in cancer progression. However, crosstalk between the two receptors and potential effects on cellular physiology are not fully understood. Here, using BRET analysis, we found that LPA₂ and GPR55 interact in live cells. In the presence of both receptors, LPA₂ and/or GPR55 activation facilitated co-internalization, and activation of GPR55, uncoupled with Gα_i , induced reduction of intracellular cAMP. Notably, co-activation of receptors synergistically triggered further decline in the cAMP level, promoted cell proliferation, and increased the expression of cancer progression-related genes, suggesting that physical and functional crosstalk between LPA₂ and GRR55 is involved in cancer progression.

Heparanase from triple‑negative breast cancer and platelets acts as an enhancer of metastasis

Triple-negative breast cancer (TNBC), which is characterized by inherently aggressive behavior and lack of recognized molecular targets for therapy, poses a serious threat to women's health worldwide. However, targeted treatments have yet to be made available. A crosstalk between tumor cells and platelets (PLT) contributing to growth, angiogenesis and metastasis has been reported in numerous cancers. Heparanase (Hpa), the only mammalian endoglycosidase that cleaves heparan sulfate, has been demonstrated to contribute to the growth, angiogenesis and metastasis of numerous cancers. Hypoxia affects the growth, angiogenesis and metastasis of nearly all solid tumors, and the ability of Hpa to promote invasion is enhanced in hypoxia. However, whether Hpa can strengthen the crosstalk between tumor cells and PLT, and whether enhancing the biological function of Hpa in TNBC promotes malignant progression, have yet to be fully elucidated. The present study, based on bioinformatics analysis and experimental studies in vivo and in vitro, demonstrated that Hpa enhanced the crosstalk between TNBC cells and PLT to increase the supply of oxygen and nutrients, while also conferring tolerance of TNBC cells to oxygen and nutrient shortage, both of which are important for overcoming the stress of hypoxia and nutritional deprivation in the tumor microenvironment, thereby promoting malignant progression, including growth, angiogenesis and metastasis in TNBC. In addition, the hypoxia-inducible factor-1a (HIF-1a)/vascular endothelial growth factor-a (VEGF- a)/phosphorylated protein kinase B (p-)Akt axis may be the key pathway involved in the effects of Hpa on the biological processes mentioned above. Therefore, improving local hypoxia, anti-Hpa treatment and inhibiting PLT activation may improve the prognosis of TNBC.

Yin Yang 1 (YY1): Regulation of Survivin and Its Role In Invasion and Metastasis

Despite significant clinical and basic science advancements, cancer remains a devastating disease that affects people of all ages, races, and backgrounds. The pathogenesis of cancer has recently been described to result from eight biological capabilities or hallmarks and two enabling characteristics. These eight hallmarks are: deregulation of cellular energetics, avoiding immune destruction, enabling replicative immortality, inducing angiogenesis, sustaining proliferative signaling, evading growth suppressors, resisting cell death, and activating invasion and metastasis. The enabling characteristics are: genome instability and mutation and tumor-promoting inflammation. Survivin, the fourth most common transcript found in cancer cells, is a protein that is thought to be involved in the enhanced proliferation, survival, and metastasis and possibly other key hallmarks of cancer cells. Understanding how this gene is turned on and off is vitally important for attempt improving cancer management and therapy. Our work has identified a novel transcriptional regulator of survivin called Yin Yang 1 (YY1), which has been observed to activate some gene promoters and repress others and is gaining increasing interest as a target of cancer therapy. Our work shows for the first time that YY1 represses survivin transcription by physically interacting with the survivin promoter. Furthermore, YY1 appears to contribute to basal survivin transcriptional activity, indicating that disruption of its binding may in part contribute to survivin overexpression after cellular stress events including chemotherapy and radiotherapy.

DNA methylation biomarkers for the occurrence of lung adenocarcinoma from TCGA data mining

The development of lung cancer is a combination of multifactor, multistage, and multiple genetic alterations processes. DNA methylation is an important factor. Currently, the study on the genome-scale epigenetic modification for studying the pathogenesis of lung cancer is still lacking. Here, we aimed to identify the epigenetic modifications of lung cancer, thus to provide scientific basis for the personalized medicine, and research of classification screening for lung adenocarcinoma patients. The DNA methylation data, and the corresponding clinical information of lung adenocarcinoma samples were extracted from the Cancer Genome Atlas (TCGA) database. We explored the association of DNA methylation and gene transcription expression of lung adenocarcinoma by identifying the differentially expressed genes, DNA methylated locis, functional gene clusters, and the relevant genes associated with the survival. We identified 17 differentially expressed genes which had differentially methylated locis, 4 functional gene clusters regulated by methylation, and 522 genes, which were relevant to the survival time of patients. Our study suggested that methylation controlled the gene expression in a variety of ways, which had high/low expression and hyper-/hypo-methylation. Genes of different methylation status showed the different survival curve. The genes and methylated locis identified in this study could be potential biomarkers and therapeutic targets for lung adenocarcinoma.

Antagonistic Effects of p53 and HIF1A on microRNA-34a Regulation of PPP1R11 and STAT3 and Hypoxia-induced Epithelial to Mesenchymal Transition in Colorectal Cancer Cells

BACKGROUND & AIMS

In colorectal tumors, hypoxia causes resistance to therapy and promotes metastasis. Loss of the tumor suppressor p53 (encoded by TP53) provides cancer cells with a selective advantage under conditions of hypoxia, but little is known about the mediators of this effect.

METHODS

Isogenic colorectal cancer (CRC) cell lines with different TP53 genotypes were placed under conditions of hypoxia. We examined the effects on levels and activity of microRNA-34a (MIR34A) in CRC cells. We determined the expression and localization of protein phosphatase 1 regulatory inhibitor subunit 11 (PPP1R11, also called INH3, HCGV, IPP3, HCGV, TCTE5, TCTEX5, or CFAP255) in 82 human colon cancers. We analyzed data on human colorectal carcinomas from the Cancer Genome Atlas collection to determine whether expression of PPP1R11 was affected by altered level or activity of p53, markers of epithelial-to-mesenchymal transition (EMT), or MIR34A or was associated with metastasis. We determined the effects of disruption Mir34a, Mir34b, and Mir34c in ApcMin/+ mice. DLD-1 cells were transfected with small inhibitor RNAs against PPP1R1, injected into the tail veins of immune-compromised mice, and followed by noninvasive bioluminescence imaging.

RESULTS

The hypoxia inducible factor 1 alpha subunit (HIF1A) directly repressed the MIR34A gene in p53-defective CRC cells, whereas expression of MIR34A was induced in p53-proficient CRC cells exposed to hypoxia. Down-regulation of MIR34A was required for hypoxia-induced EMT, invasion and migration, and activation of STAT3 in CRC cells. We identified PPP1R11, whose product inhibits PP1, as a target of MIR34A. PPP1R11 mediates phosphorylation (activation) of STAT3, so expression of MIR34A reduced activation of STAT3 in p53-deficient CRC cells. Ectopic expression of PPP1R11 in CRC cells induced EMT, invasion, and migration, which all required STAT3. Increased expression of PPP1R11 in p53-deficient CRC cells was required for hypoxia-induced EMT, invasion, migration, and resistance to 5-fluorouracil, as well as metastasis of xenograft tumors to lungs of mice. Adenomas and derived tumoroids of ApcMin/+ mice with disruption of Mir34a, Mir34b, and Mir34c had increased levels of PPP1R11. Colorectal tumors from patients had increased levels of PPP1R11 at areas of invasion, compared with other areas of the tumor; increased level PPP1R11 associated with TP53 mutations and metastasis to the liver.

CONCLUSIONS

HIF1A represses, whereas p53 increases, expression of MIR34A in CRC cells. MIR34A reduces expression of PPP1R11 to prevent activation of STAT3 and inhibit the EMT and metastasis. Strategies to target this pathway might be developed to inhibit CRC metastasis and overcome resistance to therapy associated with hypoxia.

miRNA-335 and miRNA-182 affect the occurrence of tongue squamous cell carcinoma by targeting survivin

The aim of the present study was to characterize the roles of two microRNAs (miRs) that have been reported to be differentially expressed in tongue squamous cell carcinoma (TSCC), miR-335 and miR-182. In total, 20 tumor tissue samples and 20 corresponding adjacent non-cancerous samples were collected from patients with TSCC to measure the expression of miR-335 and miR-182 and the potential shared target of these miRs, survivin, using reverse transcription-quantitative polymerase chain reaction and western blotting. In the TSCC tissue samples, significantly decreased expression of the two miRs and increased expression of survivin were detected compared with adjacent non-cancerous controls. Subsequently, it was confirmed that survivin was the target gene of miR-335 and miR-182 using a luciferase assay in TSCC cells. In order to examine the function of miR-335 and miR-182 in the development of TSCC, TSCC cells were transiently transfected with the mimics of the two miRs, and it was confirmed that the introduction of miR-335 and miR-182 to cells suppressed the expression of survivin and markedly inhibited the proliferation of the TSCC cells. Furthermore, miR-335 and miR-182 were found to induce cell cycle arrest by suppressing the expression of survivin. The present study revealed a negative regulatory role of miR-335 and miR-182 in the proliferation of TSCC cells by targeting survivin, and miR-335 and miR-182 may be novel therapeutic targets for the treatment of TSCC.

Survivin and angiotensin-converting enzyme polymorphisms with risk of colorectal cancer: a systematic review and meta-analysis

Background

Colorectal cancer (CRC) is the most common cause of cancer death worldwide. Numerous studies have identified the roles of survivin −31 G/C and angiotensin-converting enzyme insertion/deletion (ACE I/D) polymorphisms in CRC risk; however, the results remain inconclusive. This study was to investigate associations between these two polymorphisms and CRC susceptibility.

Methods

A comprehensive literature search was conducted to collect relevant case–control studies published between 2000 and 2014. The extracted data were statistically analyzed, and the odds ratios (ORs) with 95% confidence intervals (CIs) were employed to estimate the strength of association.

Results

A total of 11 studies were included in the meta-analysis. For survivin G/C polymorphism, six articles reported 1,840 cases and 1,804 controls. Overall, we found the frequency of C allele is higher in CRC cases than that in the healthy controls (57.2% vs. 48.0%), and C allele significantly increased the risk of CRC compared to G allele in allele model (OR = 1.46, 95% CI = 1.33–1.60, P < 0.00001). This association was also found in other genetic models (P < 0.00001). Stratified analysis by ethnicity showed significant association in each genetic model among the Asian population. For ACE I/D polymorphism, five studies included 758 cases and 6,755 controls. No significant association was found in any genetic models.

Conclusions

Our results showed that survivin −31 G/C polymorphism might contribute to risk of CRC, especially in the Asian populations. However, the ACE I/D polymorphism is not a genetic factor concerning the risk for CRC. More studies with larger sample sizes are required in the future.

Hypoxia-inducible MiR-210 is an independent prognostic factor and contributes to metastasis in colorectal cancer

MicroRNA-210 (miR-210), the master hypoxamir, plays pleiotropic roles in certain cancers; however, its role in the development of human colorectal cancer remains unclear. Herein, we report that miR-210 is frequently up-regulated in colorectal cancer tissues, with high miR-210 expression significantly correlating with large tumor size, lymph node metastasis, advanced clinical stage and poor prognosis. Functionally, miR-210 overexpression promotes the migration and invasion of colorectal cancer cells. Furthermore, miR-210 can be induced by hypoxia and mediates the hypoxia-induced metastasis of colorectal cancer cells. In addition, vacuole membrane protein 1 (VMP1) is identified as the direct and functional target of miR-210. Thus, miR-210 is a useful biomarker for hypoxic tumor cells and a prognostic factor that plays an essential role in colorectal cancer metastasis.

Hypoxic tumor microenvironment in advanced retinoblastoma

PURPOSE

Retinoblastoma (RB) is a malignant tumor of infancy and childhood. Unfavorable therapeutic response is still a quest in many tumors, including retinoblastoma. Hypoxic tumor microenvironment is one of the factors that determine the therapeutic response in many tumors. The purpose of this study was to determine the presence of hypoxia and its related proteins; Hypoxia inducible factor-1α (HIF-1α), Carbonic anhydrase IX (CA IX) and survivin in RB and their association with clinicopathological features.

MATERIALS AND METHODS

We evaluated the expression of HIF-1α and survivin by immunohistochemistry in 42 archival retinoblastoma tumors and CA IX; a hypoxia marker in 33 tumors in the same cohort. The expression was correlated with tumor groups based on invasion, differentiation and IIRC.

RESULTS

Expression of HIF-1α, survivin and CA IX was observed in 83% (35/42), 86% (36/42), and 93% (31/33) of tumors respectively. We observed no significance between HIF-1α and CA IX expression in tumors with invasion, differentiation and in IIRC tumor groups. An increased survivin expression was observed in group E tumors than in group D tumors (P = 0.044). A significant association was observed between HIF-1α and survivin in differentiated (r = -0.582; P = < 0.01) and undifferentiated tumors groups (r = 0.513; P = <0.012). A similar significant association was observed between HIF-1α and CA IX in tumors with high immunoreactivity for HIF-1α (r = 0.833; P = <0.01).

CONCLUSION

Based on these observations, we propose that HIF-1α pathway is deregulated in RB. The role of drug resistance and the potential of targeting HIF-1α, CA IX, and survivin in RB should further examined.

Expression and significance of hypoxia-inducible factor-1α and survivin in laryngeal carcinoma tissue and cells

OBJECTIVE

The aim was to evaluate hypoxia-inducible factor-1α (HIF-1α) and survivin expression in laryngeal squamous cell carcinoma (LSCC) tissues and cell lines and to investigate whether HIF-1α has an effect on the regulation of survivin gene expression in LSCC cells under hypoxia.

STUDY DESIGN

Prospective, observational.

SETTING

Shanghai Jiaotong University Affiliated First People's Hospital.

SUBJECTS AND METHODS

The expression of HIF-1α and survivin protein in human LSCC tissues was analyzed by immunohistochemistry. HIF-1α and survivin gene expression levels in Hep-2 cells were detected by real-time quantitative reverse transcription polymerase chain reaction (RT-PCR) and Western blot under normoxic or hypoxic conditions. In hypoxic cells, HIF-1α expression was inhibited by RNA interference.

RESULTS

HIF-1α and survivin were both highly expressed in LSCC tissues and significantly related to the clinical stage and lymph node metastasis (P < .05). Meanwhile, a positive correlation existed between HIF-1α and survivin expression (r = 0.456, P < .01). In LSCC cells, HIF-1α and survivin expression were obviously upregulated in response to hypoxia (P < .05). The downregulation of HIF-1α expression dramatically decreased survivin gene expression in hypoxic cells (P < .05).

CONCLUSION

HIF-1α could be considered as an important regulator for the upregulation of survivin gene expression induced by hypoxia in LSCC cells, and both proteins could be regarded as 2 key predictors of malignant progression and metastasis of LSCC.

Survivin knockdown enhances gastric cancer cell sensitivity to radiation and chemotherapy in vitro and in nude mice

INTRODUCTION

The aim is to assess the effect of survivin knockdown on the radio- and chemosensitivity of gastric cancer cells in vitro and in nude mice.

METHODS

Survivin messenger RNA and protein were detected by semiquantitative reverse transcription-polymerase chain reaction and Western blot. Survivin and control small hairpin RNA (shRNA) expression constructed vectors were stably transfected into gastric cancer SGC7901 cells. The cells were in turn subjected to irradiation, cisplatin or fluorouracil (5-FU) treatment for colony formation, methyl-thiazolyl-tetrazolium cell viability and flow cytometry assays in vitro. An in vivo nude mouse xenograft assay was performed to assess the effects of Survivin knockdown on regulation of the sensitivity of SGC7901 cells to irradiation, cisplatin or 5-FU treatment.

RESULTS

Survivin shRNA markedly inhibited levels of survivin messenger RNA and protein in SGC7901 cells and significantly increased sensitivity of the tumor cells to radiation treatment, ie, the mean lethal and quasi-threshold doses in survivin shRNA-transfected cells were significantly lower than that of the negative control shRNA-transfected and parental cells. The same is true for cisplatin- and 5-FU-treated tumor cells, ie, colony formation and cell viability of the survivin-knocked down SGC7901 cells were reduced, while apoptosis was induced compared with the control cells. Furthermore, the xenograft assay showed survivin knockdown in SGC7901 cells suppressed tumor formation and growth compared with the controls.

CONCLUSIONS

Knockdown of survivin expression enhanced sensitivity of gastric cancer cells to radiation, cisplatin and 5-FU treatment in vitro and in nude mice. These results demonstrate that clinical trails are warranted of survivin shRNA as an adjuvant therapy for gastric cancer patients.

From tumor hypoxia to cancer progression: the implications of hypoxia-inducible factor-1 expression in cancers

Hypoxia, defined as a decrease of tissue oxygen levels, represents a fundamental pathophysiological condition in the microenvironment of solid tumors. Tumor hypoxia is known to be associated with radio/chemo-resistance and metastasis that eventually lead to cancer progression contributing to poor prognosis in cancer patients. Among transcription factors that accumulated under hypoxic conditions, hypoxia-inducible factor-1 (HIF-1) is a master transcription factor that has received the most intense attention in this field of research due to its capacity to modulate several hundred genes. With a clearer understanding of the HIF-1 pathway, efforts are directed at manipulation of this complex genetic process in order to ultimately decrease cellular HIF-1 levels. Some novel agents have been shown to have HIF-1 inhibition activity through a variety of molecular mechanisms and have provided promising results in the preclinical setting.

Hypoxia induces Wee1 expression and attenuates hydrogen peroxide-induced endothelial damage in MS1 cells

In an oxygen-depleted environment, endothelial cells initiate an adaptive pattern of synthesis, which may enable them to survive hypoxic crises. Using high-resolution two-dimensional gel electrophoresis in conjunction with mass spectroscopy, we obtained a 24 differential display of proteins in the pancreatic endothelial cell line, MS-1, at four time points following induction of hypoxia. The induction of Wee1 under hypoxia was confirmed both at the mRNA and protein levels. The phosphorylation of cell division cycle 2, which is downstream of Wee1, was also increased after hypoxic exposure. In addition, pre-exposure to hypoxia attenuated a decrease in hydrogen peroxide-induced cell number. The induction of bax (a pro-apoptotic protein) and reduction of bcl (an anti-apoptotic protein) after hypoxia stimulus were also attenuated by hypoxic pre-exposure. Moreover, hydrogen peroxide-induced morphologic damage did not appear in the wild-type Wee1-expressing cells. Taken together, our results suggest that Wee1 may have important role in hypoxia- induced pathophysiological situations in endothelial cells.

The survivin -31 snp in human colorectal cancer correlates with survivin splice variant expression and improved overall survival

BACKGROUND

Survivin is involved in the regulation of cell division and survival, two key processes in cancer. The majority of studies on survivin in colorectal cancer (CRC) have focused on protein expression and less is known about the expression of survivin splicing variants or survivin gene polymorphisms in CRC. In the present study, the mRNA levels of the five known isoforms of survivin as well as survivin protein were assessed in matched normal and neoplastic colorectal tissue. Moreover, the 9386 C/T and -31 G/C polymorphisms were investigated.

METHODS

Quantitative RT-PCR was used to assess mRNA levels in fresh/frozen tissue samples. Protein levels were immunohistochemically evaluated on formalin-fixed paraffin-embedded tissue sections. Individuals were genotyped using real time PCR.

RESULTS

Expression of all 5 survivin splice variants as well as survivin protein was elevated in colorectal carcinomas compared to normal tissue. Specific splice variant expression differentially correlated with clinicopathological parameters. Furthermore, both snps correlated with splice variant levels or their ratios in colorectal carcinomas while the -31 G/C snp may be related to CRC development and improved overall survival.

CONCLUSION

Our results support a role of survivin in colorectal carcinogenesis while the -31 G/C snp may constitute a marker of survival.

Targeting survivin in cancer: the cell-signalling perspective

Survivin, a prominent anticancer target, is ubiquitously expressed in a plethora of cancers and the evolving complexity in functional regulation of survivin is yet to be deciphered. However, pertaining to the recent studies, therapeutic modulation of survivin is critically regulated by interaction with prominent cell-signalling pathways [HIF-1α, HSP90, PI3K/AKT, mTOR, ERK, tumour suppressor genes (p53, PTEN), oncogenes (Bcl-2, Ras)] and a wide range of growth factors (EGFR, VEGF, among others). In our article we discuss, in detail, an overview of the recent developments in the pharmacological modulation of survivin via cell-signalling paradigms and antisurvivin therapeutics, along with an outlook on therapeutic management of survivin in drug-resistant cancers.

Hypoxia inducible factor-1 mediates expression of galectin-1: the potential role in migration/invasion of colorectal cancer cells

The expression of galectin-1, one of the most important lectins participating in the malignant tumor development, has been shown to be regulated by hypoxia, but its exact mechanism remains elusive. Here, we find that ectopically expressed hypoxia-inducible factor (HIF) 1alpha protein, an oxygen-sensitive subunit of HIF-1 that is a master factor for cellular response to hypoxia, significantly increases galectin-1 expression in both messenger RNA and protein levels in all four colorectal cancer (CRC) cell lines tested. However, hypoxia-induced galectin-1 expression cannot be seen in sentrin/SUMO-specific protease 1 homozygous-null mouse embryonic fibroblasts that fail to accumulate HIF-1alpha protein. Furthermore, silence of HIF-1alpha or HIF-1beta expression by specific short hairpin RNAs (shRNAs) antagonizes hypoxia-induced galectin-1 expression. All these results propose that galectin-1 is a direct target of transcriptional factor HIF-1. Applying luciferase reporter assay and chromatin immunoprecipitation, we identify that two hypoxia-responsive elements located at -441 to -423 bp upstream to transcriptional start site of galectin-1 gene are essential for HIF-1-mediated galectin-1 expression. Finally, the knockdown of galectin-1 by its specific shRNA can significantly reduce hypoxia-induced invasion and migration of CRC cell line, and the ectopic expression of galectin-1 can remarkably restore invasion and migration abilities of HIF-1alpha-knocked SW620 cells, proposing that galectin-1 mediates the HIF-1-induced migration and invasion of CRC cells during hypoxia. Taken together, our results shed new light for understanding mechanism for hypoxia/HIF-1-mediated migration/invasion of CRC cells.

Inhibitory effect of HuR gene small interfering RNA segment on laryngeal carcinoma Hep-2 cell growth

OBJECTIVES

To investigate the effect of the HuR gene on laryngeal carcinoma Hep-2 cell growth, and to analyse correlations between the HuR, cyclooxygenase-2 and survivin genes.

STUDY DESIGN

Experiment study.

SETTING

Department of Otolaryngology-Head and Neck Surgery, Lihuili Hospital of Ningbo University, Ningbo, a tertiary care centre in China.

METHODS

Copies of a small interfering RNA segment directed against the HuR gene were transfected into Hep-2 cells using Lipofectamine™ 2000. The effect of the small interfering RNA segment on Hep-2 cell proliferation was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Changes in the expression of the HuR, cyclooxygenase-2 and survivin genes were detected by semi-quantitative reverse transcription polymerase chain reaction analysis. Concentrations of the HuR, cyclooxygenase-2 and survivin proteins were evaluated using Western blotting.

RESULTS

Expression of the HuR, cyclooxygenase-2 and survivin genes, as indicated by messenger RNA and protein levels, was suppressed by the HuR gene small interfering RNA segment in a dose-dependent manner. The proliferation indices of all treated groups were significantly lower than those of control groups (p < 0.05).

CONCLUSIONS

Impairment of HuR gene expression, using interfering RNA technology, can significantly suppress Hep-2 cell proliferation and induce apoptosis. The HuR gene may be an effective target for gene therapy in patients with laryngeal carcinoma.

Expression of putative stem cell genes Musashi-1 and beta1-integrin in human colorectal adenomas and adenocarcinomas

BACKGROUND AND AIMS

Recent studies revealed that Musashi-1and beta1-integrin were putative stem cell genes. Overexpressions of Musashi-1 and beta1-integrin have been reported in some tumor tissues and cell lines. This study was to detect expressions of the two genes in colorectal adenomas and carcinomas and to analyze the correlation between Musashi-1 and beta1-integrin.

METHODS

Musashi-1 and beta1-integrin immunoreactivity was studied immunohistochemically in tissue microarray-based samples containing 69 colorectal adenocarcinomas, eight normal mucosa, and eight adenomas, and their messenger RNA (mRNA) expression level was detected by RT-PCR in resected specimens including the three types of tissue.

RESULTS

A percentage of 66.7% (46/69) and 59.2% (41/69) of colorectal adenocarcinomas were immunoreactive with Musashi-1 and beta1-integrin, respectively. The expressions of Musashi-1 and beta1-integrin protein were significantly higher in tissue samples of stage III than those of stage I-II (P = 0.0252; P = 0.0018, respectively). beta1-integrin expression was higher in group of adenocarcinomas than that of adenomas (P = 0.0276). Musashi-1 expression was closely correlated with beta1-integrin (rs = 0.631, P = 0.0001). Significant differences of Musashi-1 and beta1-integrin mRNA expression levels were found between the normal colorectal mucosa, adenoma, and adenocarcinoma tissues (P = 0.01; P = 0.03, respectively).

CONCLUSIONS

Musashi-1 and beta1-integrin may be involved in human colorectal tumor carcinogenesis and progression. Our observations also indicate the need for further investigations to test in vivo whether cells with these markers have stem cell properties.

Hypoxia inducible factor-1 alpha activation of the JCV promoter: role in the pathogenesis of progressive multifocal leukoencephalopathy

Activation of viral promoter transcription is a crucial event in the life cycle of several viruses. Hypoxia inducible factor-1 alpha (HIF-1alpha) is an inducible transcription factor whose activity is dependent on environmental conditions, most notably oxygen levels and cellular stress. HIF-1alpha has been implicated in the pathogenesis of several viruses, including HIV-1, HHV-8 and RSV. Under hypoxic conditions or oxidative stress, HIF-1alpha becomes stable and translocates to the nucleus, where it modulates gene transcription. The objective of the present study was to investigate a possible role for HIF-1alpha in the activation of JCV. Glial cell cultures infected with JCV demonstrated a significant increase in the levels of HIF-1alpha, in where it is located to the nucleus. Immunohistochemical studies corroborated upregulation of HIF-1alpha in JCV infected oligodendrocytes and astrocytes in clinical samples of PML compared with normal glial cells from the same samples in which HIF-1alpha expression is weak. CAT assays performed in co-transfected glial cells demonstrated activation of the JCV early promoter in the presence of HIF-1alpha. This activation was potentiated in the presence of Smad3 and Smad4. Finally, chromatin immunoprecipitation assays demonstrated the binding of HIF-1alpha to the JCV control region. These results suggest a role for HIF-1alpha in the activation of JCV; understanding of this pathway may lead to the development of more effective therapies for PML, thus far an incurable disease.