Decreased ID2 promotes metastatic potentials of hepatocellular carcinoma by altering secretion of vascular endothelial growth factor

Protein phosphatase 6 promotes stemness of colorectal cancer cells

Colorectal cancer (CRC) remains a significant global health concern, demanding a more profound comprehension of its molecular foundations for the development of improved therapeutic strategies. This study aimed to elucidate the role of protein phosphatase 6 (PP6), a member of the type 2A protein phosphatase family, in CRC. Protein phosphatase 6 functions as a heterotrimer with a catalytic subunit (PP6c), regulatory subunits (PP6Rs; PP6R1, PP6R2, and PP6R3), and scaffold subunits (ANKRD28, ANKRD44, and ANKRD52). Elevated PP6c expression has been identified in CRC tissues compared to normal mucosa, aligning with its potential involvement in CRC pathogenesis. PP6c knockdown resulted in decreased colony-forming ability and in vivo proliferation of various CRC cell lines. Transcriptome analysis revealed that PP6c knockdown resulted in altered expression of genes associated with cancer stemness. Notably, the PP6c-PP6R3 complex is a key player in regulating cancer stem cell (CSC) markers. Additionally, increased PP6c expression was observed in CSC-like cells induced by sphere formation, implicating the role of PP6c in CSC maintenance. This study highlights the role of PP6c in CRC and suggests that it is a potential therapeutic target disrupting a pathway critical for CRC progression and stem cell maintenance.

Role of m6A modification in immune microenvironment of digestive system tumors

Digestive system tumors are huge health problem worldwide, largely attributable to poor dietary choices. The role of RNA modifications in cancer development is an emerging field of research. RNA modifications are associated with the growth and development of various immune cells, which, in turn, regulate the immune response. The majority of RNA modifications are methylation modifications, and the most common type is the N6-methyladenosine (m6A) modification. Here, we reviewed the molecular mechanism of m6A in the immune cells and the role of m6A in the digestive system tumors. However, further studies are required to better understand the role of RNA methylation in human cancers for designing diagnostic and treatment strategies and predicting the prognosis of patients.

The Roles of Antisense Long Noncoding RNAs in Tumorigenesis and Development through Cis-Regulation of Neighbouring Genes

Antisense long noncoding RNA (as-lncRNA) is a lncRNA transcribed in reverse orientation that is partially or completely complementary to the corresponding sense protein-coding or noncoding genes. As-lncRNAs, one of the natural antisense transcripts (NATs), can regulate the expression of their adjacent sense genes through a variety of mechanisms, affect the biological activities of cells, and further participate in the occurrence and development of a variety of tumours. This study explores the functional roles of as-lncRNAs, which can cis-regulate protein-coding sense genes, in tumour aetiology to understand the occurrence and development of malignant tumours in depth and provide a better theoretical basis for tumour therapy targeting lncRNAs.

Elevated expression of RAB3B plays important roles in chemoresistance and metastatic potential of hepatoma cells

Background

Cancer stem cells (CSCs) are thought to play important roles in carcinogenesis, recurrence, metastasis, and therapy-resistance. We have successfully induced cancer stem-like sphere cells (CSLCs) which possess enhanced chemoresistance and metastatic potential. To enable the development of targeted therapy against CSLCs, we identified a gene responsible for this phenotype in CSLC.

Methods

Human hepatoma cell line SK-HEP-1 was used for CSLC induction with a unique sphere inducing medium, and HuH-7 cells were used as non-sphere forming cells in the same condition. RNA-sequencing was performed followed by validation with quantitative RT-PCR and western blotting. Knockdown experiments were done by using CRISPR-Cas9 genome-editing, and the rescue experiments were performed using the expressing plasmid vector. Chemoresistance and liver metastasis of the cells, was studied following the splenic injection of cells to severely immune deficient mice and evaluated using the MTS assay. Quantification of exosomes in the medium was done using ELISA.

Results

RAB3B was identified as an up-regulated gene in both CSLCs and prognostically poor hepatocellular carcinoma (HCC) by RNA-sequencing. RAB3B-KD cells showed altered CSLC phenotypes such as sphere formation, chemoresistance, and metastatic potentials, and those were rescued by RAB3B complementation. Increased exosome secretion was observed in CSLCs, and it was not observed in the RAB3B-KD cells. In addition, the RAB3B expression correlated with the expression of ABCG2, APOE, LEPR, LXN, and TSPAN13.

Conclusion

The up regulation of RAB3B may play an important role in the chemoresistance and metastatic potential of CSLCs.

Inhibitor of DNA Binding 2 (ID2): A Novel Marker for Lymph Node Metastasis in Head and Neck Squamous Cell Carcinoma

BACKGROUND

Although aggressive invasion and sequential lymph node metastasis (LNM) significantly affect the prognosis of patients with head and neck squamous cell carcinoma (HNSCC), studies on identifying the factors that regulate this process remain scarce. This study found an inhibitor of DNA binding 2 (ID2) as a novel molecule involved in the regulation of invasion and LNM of HNSCC and further verified its functional role.

METHODS

The study examined the translational significance between ID2 expression levels and the presence of LNM as well as the prognosis for 119 patients with HNSCC after treatment. In addition, in vitro and in vivo experiments were performed using ID2 gene-modulated HNSCC cell lines to determine the functional role of ID2 in the invasion and LNM of HNSCC.

RESULTS

Elevated levels of ID2 expression were closely associated with the presence of LNM in 119 patients with HNSCC, resulting in a poor prognosis. Overexpression of ID2-induced invasion and LNM of HNSCC cells was observed in vitro and in vivo. By contrast, knockdown of the ID2 gene diminished invasion and LNM of HNSCC cells. In addition, the ID2 expression level increased the expression level of matrix metalloproteinase 1 (MMP1), a molecule downstream to ID2. Furthermore, silencing of MMP1 in ID2-overexpressed HNSCC cells rescued the elevated invasion and LNM capabilities of these cells, suggesting that ID2 enhances invasion and LNM partly via MMP1 activation.

CONCLUSION

In the invasion and LNM of HNSCC, ID2 plays an important role by modulating MMP1 expression, suggesting ID2-MMP1 axis to be a novel alternative therapeutic target for invasion and LNM of HNSCC.

Role of m6A methyltransferase component VIRMA in multiple human cancers (Review)

N6-Methyladenosine (m6A) modification is one of the most widely distributed RNA modifications in eukaryotes. It participates in various RNA functions and plays vital roles in tissue development, stem cell formation and differentiation, heat shock response control, and circadian clock controlling, particularly during tumor development. The reversible regulation of m6A modification is affected by the so-called ‘reader’, ‘writer’ and ‘eraser’. As a required component and the largest methyltransferase, vir-like m6A methyltransferase associated (VIRMA) can promote the progression of cancer and is associated with poor survival in multiple types of cancer. The present review investigated the role of VIRMA in various types of cancer. In an m6A-dependent or -independent manner, VIRMA can play an oncogenic role by regulating cancer cell proliferation, migration and invasion, metastasis, apoptosis resistance and tumor growth in different pathways by targeting stem factors, CCAT1/2, ID2, GATA3, CDK1, c-Jun, etc. VIRMA can also predict better prognosis in kidney renal clear cell carcinoma (KIRC), kidney renal papillary cell carcinoma (KIRP) and papillary thyroid carcinoma by TCGA analysis. The obvious oncogenic roles of VIRMA observed in different types of cancer and the mechanisms of VIRMA promoting cancers provided the basis for potential therapeutic targeting for cancer treatments.

Epigenetic Silencing of LMX1A Contributes to Cancer Progression in Lung Cancer Cells

Epigenetic modification is considered a major mechanism of the inactivation of tumor suppressor genes that finally contributes to carcinogenesis. LIM homeobox transcription factor 1α (LMX1A) is one of the LIM-homeobox-containing genes that is a critical regulator of growth and differentiation. Recently, LMX1A was shown to be hypermethylated and functioned as a tumor suppressor in cervical cancer, ovarian cancer, and gastric cancer. However, its role in lung cancer has not yet been clarified. In this study, we used public databases, methylation-specific PCR (MSP), reverse transcription PCR (RT-PCR), and bisulfite genomic sequencing to show that LMX1A was downregulated or silenced due to promoter hypermethylation in lung cancers. Treatment of lung cancer cells with the demethylating agent 5-aza-2'-deoxycytidine restored LMX1A expression. In the lung cancer cell lines H23 and H1299, overexpression of LMX1A did not affect cell proliferation but suppressed colony formation and invasion. These suppressive effects were reversed after inhibition of LMX1A expression in an inducible expression system in H23 cells. The quantitative RT-PCR (qRT-PCR) data showed that LMX1A could modulate epithelial mesenchymal transition (EMT) through E-cadherin (CDH1) and fibronectin (FN1). NanoString gene expression analysis revealed that all aberrantly expressed genes were associated with processes related to cancer progression, including angiogenesis, extracellular matrix (ECM) remodeling, EMT, cancer metastasis, and hypoxia-related gene expression. Taken together, these data demonstrated that LMX1A is inactivated through promoter hypermethylation and functions as a tumor suppressor. Furthermore, LMX1A inhibits non-small cell lung cancer (NSCLC) cell invasion partly through modulation of EMT, angiogenesis, and ECM remodeling.

Clinical implications of cancer stem cells in digestive cancers: acquisition of stemness and prognostic impact

Digestive system cancers are the most frequent cancers worldwide and often associated with poor prognosis because of their invasive and metastatic characteristics. Recent studies have found that the plasticity of cancer cells can impart cancer stem-like properties via the epithelial-mesenchymal transition (EMT). Cancer stem-like properties such as tumor initiation are integral to the formation of metastasis, which is the main cause of poor prognosis. Numerous markers of cancer stem cells (CSCs) have been identified in many types of cancer. Therefore, CSCs, via their stem cell-like functions, may play an important role in prognosis after surgery. While several reports have described prognostic analysis using CSC markers, few reviews have summarized CSCs and their association with prognosis. Herein, we review the prognostic potential of eight CSC markers, CD133, CD44, CD90, ALDH1A1, EPCAM, SOX2, SOX9, and LGR5, in digestive cancers including those of the pancreas, colon, liver, gastric, and esophagus.

KIAA1429 regulates the migration and invasion of hepatocellular carcinoma by altering m6A modification of ID2 mRNA

Purpose

N6-methyladenosine (m6A), the most abundant mRNA modification in mammals, is involved in various biological processes. KIAA1429 is an important methyltransferase participating in m6A modification. However, the role of KIAA1429 in hepatocellular carcinoma (HCC) is still not well understood. Here, we aimed to investigate the function of KIAA1429 and its corresponding regulation mechanisms in HCC.

Patients and methods

HCC-related genes were analyzed by clinical and expression data of HCC patients in The Cancer Genome Atlas (TCGA) database. Expression of KIAA1429 was verified by quantitative reverse-transcription PCR, and interference efficiency was obtained using small interfering RNA (siRNA). Cell proliferation, migration, and invasion were assessed by cell counting kit-8 and transwell assays, and the m6A modification was detected by methylated RNA immunoprecipitation-PCR (MeRIP-PCR).

Results

We found a difference in the expression of KIAA1429 between HCC and normal hepatic tissues by analyzing data from the TCGA database. Comparing HCC cell lines (HepG2, Huh-7, HepG2.2.15) with normal hepatic cells (HL-7702), we observed an identically significant difference in KIAA1429 expression. KIAA1429 significantly enhanced proliferation, migration, and invasion of HepG2 cells. Moreover, Kyoto Encyclopedia of Genes and Genomes functional enrichment analysis and correlation analysis revealed a significant negative correlation between KIAA1429 and ID2. In the subsequent MeRIP-PCR assay, downregulation of KIAA1429 inhibited m6A modification of ID2 mRNA.

Conclusion

KIAA1429 facilitated migration and invasion of HCC by inhibiting ID2 via upregulating m6A modification of ID2 mRNA.

Identification and validation of a potent multi-mRNA signature for the prediction of early relapse in hepatocellular carcinoma

Early recurrence of hepatocellular carcinoma (HCC) is implicated in poor patient survival and is the major obstacle to improving prognosis. The current staging systems are insufficient for accurate prediction of early recurrence, suggesting that additional indicators for early recurrence are needed. Here, by analyzing the gene expression profiles of 12 Gene Expression Omnibus data sets (n = 1533), we identified 257 differentially expressed genes between HCC and non-tumor tissues. Least absolute shrinkage and selection operator regression model was used to identify a 24-messenger RNA (mRNA)-based signature in discovery cohort GSE14520. With specific risk score formula, patients were divided into high- and low-risk groups. Recurrence-free survival within 2 years (early-RFS) was significantly different between these two groups in discovery cohort [hazard ratio (HR): 7.954, 95% confidence interval (CI): 4.596–13.767, P < 0.001], internal validation cohort (HR: 8.693, 95% CI: 4.029–18.754, P < 0.001) and external validation cohort (HR: 5.982, 95% CI: 3.414–10.480, P < 0.001). Multivariable and subgroup analyses revealed that the 24-mRNA-based classifier was an independent prognostic factor for predicting early relapse of patients with HCC. We further developed a nomogram integrating the 24-mRNA-based signature and clinicopathological risk factors to predict the early-RFS. The 24-mRNA-signature-integrated nomogram showed good discrimination (concordance index: 0.883, 95% CI: 0.836–0.929) and calibration. Decision curve analysis demonstrated that the 24-mRNA-signature-integrated nomogram was clinically useful. In conclusion, our 24-mRNA signature is a powerful tool for early-relapse prediction and will facilitate individual management of HCC patients.

Validation of the OncoHepa test, a multigene expression profile test, and the tumor marker-volume score to predict postresection outcome in small solitary hepatocellular carcinomas

Purpose

OncoHepa test is a multigene expression profile test developed for assessment of hepatocellular carcinoma (HCC) prognosis. Multiplication of α-FP, des-γ-carboxy prothrombin (DCP) and tumor volume (TV) gives the α-FP-DCP-volume (ADV) score, which is also developed for assessment of HCC prognosis.

Methods

The predictive powers of OncoHepa test and ADV score were validated in 35 patients who underwent curative hepatic resection for naïve solitary HCCs ≤5 cm.

Results

Median tumor diameter was 3.0 cm. Tumor recurrence and patient survival rates were 28.6% and 100% at 1 year, 48.6% and 82.9% at 3 years, and 54.3% and 71.4% at 5 years, respectively. The site of first tumor recurrence was the remnant liver in 18, lung in 1, and the peritoneum in 1. All patients with HCC recurrence received locoregional treatment. OncoHepa test showed marginal prognostic significance for tumor recurrence and patient survival. ADV score at 4log also showed marginal prognostic difference with respect to tumor recurrence and patient survival. Combination of these 2 tests resulted in greater prognostic significance for both tumor recurrence (P = 0.046) and patient survival (P = 0.048).

Conclusion

Both OncoHepa test and ADV score have considerably strong prognostic power, thus individual and combined findings of OncoHepa test and ADV score will be helpful to guide postresection surveillance in patients with solitary HCCs ≤5 cm.

Woodchuck VEGF (wVEGF) characteristics: Model for angiogenesis and human hepatocellular carcinoma directed therapies

Vascular endothelial growth factor (VEGF) stimulates angiogenesis. Human hepatocellular carcinoma (HCC) is a VEGF-driven tumor often associated with chronic hepatitis B or C virus infection. The woodchuck is a well-characterized model of hepatitis B virus related HCC and a valuable tool for translational studies of novel VEGF targeted agents. We cloned the cDNA encoding woodchuck VEGF (wVEGF), transiently expressed it in COS cells and functionally characterized the recombinant protein. The open reading frame of wVEGF contained 645 nucleotides encoding a protein of 214 amino acids. Two protein bands (17 and 25 kDa) were detected in conditioned media of wVEGF expressing COS-1 cells and a single band of 25 kDa was identified in cell lysates. Addition of recombinant wVEGF to COS cells enhanced cell proliferation and stimulated VEGFR2, Akt, ERK1/2, and FAK phosphorylation. Sunitinib, a tyrosine kinase inhibitor, inhibited wVEGF- induced VEGFR2 phosphorylation in a dose-dependent manner. Finally, development of HCC in woodchucks was accompanied by increased laminin and PECAM1 expressing vessels, VEGFR2 expression, increased ligation of VEGF to VEGFR2, and a decrease in collagen IV-positive blood vessels. Our results suggest that woodchuck model can be used further to study angiogenesis and the effect of VEGF directed therapies in human HCC.

Metastatic ability and the epithelial-mesenchymal transition in induced cancer stem-like hepatoma cells

Cancer stem cells (CSCs) are thought to play important roles in cancer malignancy. Previously, we successfully induced sphere cancer stem-like cells (CSLCs) from several cell lines and observed the property of chemoresistance. In the present study, we examined the metastatic potential of these induced CSLCs. Sphere cancer stem-like cells were induced from a human hepatoma cell line (SK-HEP-1) in a unique medium containing neural survival factor-1. Splenic injection of cells into immune-deficient mice was used to assess hematogenous liver metastasis. Transcriptomic strand-specific RNA-sequencing analysis, quantitative real-time PCR, and flow cytometry were carried out to examine the expression of epithelial-mesenchymal transition (EMT)-related genes. Splenic injection of CSLCs resulted in a significantly increased frequency of liver metastasis compared to parental cancer cells (P < .05). In CSLCs, a mesenchymal marker, Vimentin, and EMT-promoting transcription factors, Snail and Twist1, were upregulated compared to parental cells. Correspondingly, significant enrichment of the molecular signature of the EMT in CSLCs relative to parental cancer cells was shown (q < 0.01) by RNA-sequencing analysis. This analysis also revealed differential expression of CD44 isoforms between CSLCs and parental cancer cells. Increasing CD44 isoforms containing an extra exon were observed, and the standard CD44 isoform decreased in CSLCs compared to parental cells. Interestingly, another CD44 variant isoform encoding a short cytoplasmic tail was also upregulated in CSLCs (11.7-fold). Our induced CSLCs possess an increased liver metastatic potential in which promotion of the EMT and upregulation of CD44 variant isoforms, especially short-tail, were observed.

BMP4 promotes metastasis of hepatocellular carcinoma by an induction of epithelial-mesenchymal transition via upregulating ID2

The role of bone morphogenetic protein 4 (BMP4), a crucial epithelial-mesenchymal transition (EMT) mediator, in the progression of hepatocellular carcinoma (HCC) patients heretofore has not been elucidated. The present study analyzed BMP4 expression in tumors and paired non-tumorous liver tissue and its correlation with clinicopathological characteristics from two independent cohorts consisting of 420 HCC patients. Functional analysis of BMP4 was performed in Bel-7402 and HCCLM3 HCC cells, and in a murine HCC model. The downstream targets of BMP4 in HCC were screened and confirmed. The results indicated that BMP4 expression was significantly increased in HCC tissue and highly metastatic HCC cells. BMP4 expression was correlated with vein invasion, overall survival and recurrence-free survival of HCC. BMP4 promoted HCC EMT and metastasis in vitro, and consistently in vivo. BMP4 knockdown blocked EMT and tumor metastasis in nude mice. ID2 was up-regulated by recombinant human BMP4, resulting in HCC EMT. Knockdown of ID2 blocked BMP4-induced EMT. In conclusion, BMP4 promotes invasion and metastasis of HCC by an induction of EMT via up-regulating ID2. BMP4 may be a valuable prognostic factor and potential therapeutic target for HCC therapy.

Silencing of Id2 Alleviates Chronic Neuropathic Pain Following Chronic Constriction Injury

Inhibitor of DNA binding/differentiation 2 (Id2) belongs to a helix-loop-helix family of proteins. Recent studies have showed that Id2 plays a pivotal role in neuronal survival and neuroprotection. However, under neuropathic pain conditions, the role of Id2 is still unclear. In this study, we investigated the effect of Id2 on neuropathic pain in a rat chronic constriction injury (CCI) model. Our results demonstrated that Id2 was upregulated in the dorsal root ganglion (DRG) in a CCI rat in a time-dependent manner. Intrathecal short-hairpin RNA (shRNA)-Id2 attenuates mechanical allodynia and thermal hyperalgesia in CCI rats, and inhibits the expression of TNF-α and IL-1β in the DRG in CCI rats. Furthermore, knockdown of Id2 reduces the expression of NF-κB p65 in the DRG of CCI rats. Taken together, our findings suggest that knockdown of Id2 may alleviate neuropathic pain by inhibiting the NF-κB activation to inhibit the production of pro-inflammatory mediators. Therefore, Id2 may provide an important target of neuropathic pain treatment.

Peritoneal VEGF-A expression is regulated by TGF-β1 through an ID1 pathway in women with endometriosis

VEGF-A, an angiogenic factor, is increased in the peritoneal fluid of women with endometriosis. The cytokine TGF-β1 is thought to play a role in the establishment of endometriosis lesions. Inhibitor of DNA binding (ID) proteins are transcriptional targets of TGF-β1 and ID1 has been implicated in VEGF-A regulation during tumor angiogenesis. Herein, we determined whether peritoneal expression of VEGF-A is regulated by TGF-β1 through the ID1 pathway in women with endometriosis. VEGF-A was measured in peritoneal fluid by ELISA (n = 16). VEGF-A and ID1 expression was examined in peritoneal biopsies (n = 13), and primary peritoneal and immortalized mesothelial cells (MeT5A) by immunohistochemistry, qRT-PCR and ELISA. VEGF-A was increased in peritoneal fluid from women with endometriosis and levels correlated with TGF-β1 concentrations (P < 0.05). VEGF-A was immunolocalized to peritoneal mesothelium and TGF-β1 increased VEGFA mRNA (P < 0.05) and protein (P < 0.05) in mesothelial cells. ID1 was increased in peritoneum from women with endometriosis and TGF-β1 increased concentrations of ID1 mRNA (P < 0.05) in mesothelial cells. VEGF-A regulation through ID1 was confirmed by siRNA in MeT5A cells (P < 0.05). Our data supports role for ID1 in the pathophysiology of endometriosis, as an effector of TGFβ1 dependent upregulation of VEGF-A, and highlights a novel potential therapeutic target.

A stem cell medium containing neural stimulating factor induces a pancreatic cancer stem-like cell-enriched population

Cancer stem cells (CSCs) have been studied for their self-renewal capacity and pluripotency, as well as their resistance to anticancer therapy and their ability to metastasize to distant organs. CSCs are difficult to study because their population is quite low in tumor specimens. To overcome this problem, we established a culture method to induce a pancreatic cancer stem-like cell (P-CSLC)-enriched population from human pancreatic cancer cell lines. Human pancreatic cancer cell lines established at our department were cultured in CSC-inducing media containing epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), leukemia inhibitory factor (LIF), neural cell survivor factor-1 (NSF-1), and N-acetylcysteine. Sphere cells were obtained and then transferred to a laminin-coated dish and cultured for approximately two months. The surface markers, gene expression, aldehyde dehydrogenase (ALDH) activity, cell cycle, and tumorigenicity of these induced cells were examined for their stem cell-like characteristics. The population of these induced cells expanded within a few months. The ratio of CD24high, CD44high, epithelial specific antigen (ESA) high, and CD44variant (CD44v) high cells in the induced cells was greatly enriched. The induced cells stayed in the G0/G1 phase and demonstrated mesenchymal and stemness properties. The induced cells had high tumorigenic potential. Thus, we established a culture method to induce a P-CSLC-enriched population from human pancreatic cancer cell lines. The CSLC population was enriched approximately 100-fold with this method. Our culture method may contribute to the precise analysis of CSCs and thus support the establishment of CSC-targeting therapy.

Cancer stem-like sphere cells induced from de-differentiated hepatocellular carcinoma-derived cell lines possess the resistance to anti-cancer drugs

BACKGROUND

Cancer stem cells (CSCs) are thought to play important roles in therapy-resistance. In this study, we induced cancer stem-like cells from hepatocellular carcinoma (HCC) cell lines using a unique medium, and examined their potential for resistance to anti-cancer drugs.

METHODS

The human HCC cell lines SK-HEP-1 (SK), HLE, Hep 3B, and HuH-7 were used to induce cancer stem-like cells with our sphere induction medium supplemented with neural survival factor-1. NANOG and LIN28A were examined as stemness markers. Several surface markers for CSC such as CD24, CD44, CD44 variant, and CD90 were analyzed by flow-cytometry. To assess the resistance to anti-cancer drugs, the MTS assay, cell cycle analysis, and reactive oxygen species (ROS) activity assay were performed.

RESULTS

Poorly differentiated HCC derived SK and undifferentiated HCC derived HLE cell lines efficiently formed spheres of cells (SK-sphere and HLE-sphere), but well-differentiated HCC-derived HuH-7 and Hep 3B cells did not. SK-spheres showed increased NANOG, LIN28A, and ALDH1A1 mRNA levels compared to parental cells. We observed more CD44 variant-positive cells in SK-spheres than in parental cells. The cell viability of SK-spheres was significantly higher than that of SK cells in the presence of several anti-cancer drugs except sorafenib (1.7- to 7.3-fold, each P < 0.05). The cell cycle of SK-spheres was arrested at the G0/G1 phase compared to SK cells. SK-spheres showed higher ABCG2 and HIF1A mRNA expression and lower ROS production compared to parental cells.

CONCLUSION

Our novel method successfully induced cancer stem-like cells, which possessed chemoresistance that was related to the cell cycle, drug efflux, and ROS.

ID1 promotes breast cancer metastasis by S100A9 regulation

Metastasis is a major factor responsible for mortality in patients with breast cancer. Inhibitor of DNA binding 1 (Id1) has been shown to play an important role in cell differentiation, tumor angiogenesis, cell invasion, and metastasis. Despite the data establishing Id1 as a critical factor for lung metastasis in breast cancer, the pathways and molecular mechanisms of Id1 functions in metastasis remain to be defined. Here, we show that Id1 interacts with TFAP2A to suppress S100A9 expression. We show that expression of Id1 and S100A9 is inversely correlated in both breast cancer cell lines and clinical samples. We also show that the migratory and invasive phenotypes in vitro and metastasis in vivo induced by Id1 expression are rescued by reestablishment of S100A9 expression. S100A9 also suppresses the expression of known metastasis-promoting factor RhoC activated by Id1 expression. Our results suggest that Id1 promotes breast cancer metastasis by the suppression of S100A9 expression.

IMPLICATIONS

Novel pathways by Id1 regulation in metastasis.

Predicting early intrahepatic recurrence of hepatocellular carcinoma after microwave ablation using SELDI-TOF proteomic signature

BACKGROUND/AIMS

Despite great progress in the treatment of hepatocellular carcinoma (HCC) over the last-decade, intrahepatic recurrence is still the most frequent serious adverse event after all the treatments including microwave ablation. This study aimed to predict early recurrence of HCC after microwave ablation using serum proteomic signature.

METHODS

After curative microwave ablation of HCC, 86 patients were followed-up for 1 year. Serum samples were collected before microwave ablation. The mass spectra of proteins were generated using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS). Serum samples from 50 patients were randomly selected as a training set and for biomarkers discovery and model development. The remaining serum samples were categorized for validation of the algorithm.

RESULTS

According to preablation serum protein profiling obtained from the 50 HCC samples in the training set, nine significant differentially-expressed proteins were detected in the serum samples between recurrent and non-recurrent patients. Decision classification tree combined with three candidate proteins with m/z values of 7787, 6858 and 6646 was produced using Biomarker Patterns Software with sensitivity of 85.7% and specificity of 88.9% in the training set. When the SELDI marker pattern was tested with the blinded testing set, it yielded a sensitivity of 80.0%, a specificity of 88.5% and a positive predictive value of 86.1%.

CONCLUSIONS

Differentially-expressed protein peaks in preablation serum screened by SELDI are associated with prognosis of HCC. The decision classification tree is a potential tool in predicting early intrahepatic recurrence in HCC patients after microwave ablation.

ABCB6 mRNA and DNA methylation levels serve as useful biomarkers for prediction of early intrahepatic recurrence of hepatitis C virus-related hepatocellular carcinoma

The poor prognosis of hepatocellular carcinoma (HCC) can be explained largely by the high rate of intrahepatic recurrence (IHR). Identification of genes related to IHR is needed to improve the poor prognosis and important for personalized medicine. Eighty-one HCC specimens were used in this study. We screened for IHR-related genes by DNA microarray analysis. The validation of screening was performed by using real-time PCR. The methylation levels in genomic DNAs were measured by quantitative methylation-specific PCR. Six hepatoma cell lines were used for examination of ABCB6 expressional regulation. Time-to-event analyses for recurrence after surgery were analyzed by Kaplan-Meier analysis and Cox regression analysis with cutoff values obtained from receiver operating characteristic (ROC) analysis. We confirmed that ABCB6 mRNA levels were significantly higher in hepatitis C virus (HCV)-related HCCs with early IHR compared to HCV-related HCCs without early IHR (2.5-fold, P=0.01) and the corresponding non-cancerous livers (3.1-fold, P=0.05). Experiments with cell lines showed correlation between DNA methylation and mRNA levels of ABCB6. ROC analysis revealed that mRNA levels (0.81 area under the curve, 88% sensitivity and 72% specificity) and DNA methylation levels (0.81 area under the curve, 80% sensitivity and 80% specificity) of ABCB6 in HCV-related HCCs allowed for the accurate discrimination of the development of early IHR. Cox regression analysis revealed that ABCB6 mRNA levels was an independent risk factor for IHR of HCV-related HCC. Aberrant mRNA and DNA methylation levels of ABCB6 may serve as useful predictive biomarkers for early IHR of HCV-related HCC.

Susceptibility of hepatoma-derived cells to histone deacetylase inhibitors is associated with ID2 expression

Downregulation of inhibitor of DNA binding 2 (ID2) is associated with poor prognosis in cases of hepatocellular carcinoma (HCC). Therefore, to search for effective antitumor drugs for the treatment of HCC exhibiting poor prognostic indicators, we used two HCC-derived cell lines (HuH-7 and HLE) to alter ID2 levels. Specifically, ID2 expression was knocked down in HuH-7 cells via transfection with ID2-specific small interfering RNAs and separately ID2 was overexpressed in HLE cells via an ID2 expression plasmid vector. To assess the effect of antitumor drugs, MTS assay was performed. Annexin V staining was used to evaluate apoptosis and real-time RT-PCR was used to measure mRNA levels. ID2 knockdown cells were more susceptible to histone deacethylase (HDAC) inhibitors including sodium butyrate (NaB), sodium 4-phenyl-butyrate, tricostatin A, suberoylanilide hydroxamic acid, MS-275, apicidin and HC-toxin. Conversely, cells that overexpressed ID2 were less susceptible than control cells to HDAC inhibitors. NaB-induced apoptosis was inversely correlated with ID2 expression. Expression of the anti-apoptotic mRNA BCL2 was induced by NaB in control cells, but this induction of BCL2 was inhibited by ID2 knockdown and strengthened by ID2 overexpression. Expression of another anti-apoptotic mRNA, BCL2L1, was decreased by NaB administration and then partially recovered. However, in ID2 knockdown cells, BCL2L1 levels did not recover from NaB-induced suppression. ID2 affected the susceptibility of two HCC-derived cell lines to an HDAC inhibitor by regulating the expression of anti-apoptotic genes. Therefore, HDAC inhibitors may be effective for the treatment of HCC for which the prognosis is poor based on ID2 downregulation and ID2 could serve as a marker that is predictive of the clinical response to HDAC inhibitors.

Overexpressed DNA-binding protein inhibitor 2 as an unfavorable prognosis factor promotes cell proliferation in nasopharyngeal carcinoma

The aim of the present study was to analyze the expression of DNA-binding protein inhibitor 2 (ID2) in nasopharyngeal carcinoma (NPC) and its correlation with clinicopathological features. It was found that the expression of ID2 was significantly increased in NPC cells when compared with that in NP69 cell line. Similar level of ID2 cytoplasmic expression was observed in NPC when compared with that in non-cancerous nasopharynx tissues. However, the level of ID2 in nucleus was increased in NPC when compared with that in normal nasopharynx tissues. Furthermore, the higher expression level of nuclear ID2 was significantly associated with tumor size (T classification), lymph node metastasis (N classification), and clinical stage. Patients with increased ID2 expression level had poorer overall survival rates than those with low ID2 levels. The inhibition of ID2 expression in NPC cell line SUNE1 by lentiviral-mediated short hairpin RNA could suppress cell proliferation and colony formation, but did not disrupt cell migration. Knocking down the expression of ID2 by RNA interference could down-regulate the expression of Snail, suggesting that ID2-promoted cell growth, partially attributing to the regulation of Snail activity in NPC. Our study demonstrated that over-expression of ID2 protein is an unfavorable prognostic factor which promotes cell proliferation in NPC.

Overexpression of the RD RNA binding protein in hepatitis C virus-related hepatocellular carcinoma

Hepatocellular carcinoma (HCC) often exhibits a poor prognosis due to metastatic spread caused by portal vein invasion (PVI). In the present study, we attempted to identify a novel therapeutic target related to PVI of HCC. Based on pooled genomic data, we identified RD RNA binding protein (RDBP), a member of the negative elongation factor (NELF) transcription elongation regulatory complex, to be preferentially overexpressed in HCC with PVI. We used quantitative reverse transcription polymerase chain reaction (RT-PCR) and immuno-histochemical analyses to investigate the relationship between RDBP mRNA and protein with metastatic potential in sample sets of hepatitis C virus (HCV)-related HCC and corresponding non-HCC liver tissues. We also used the small interfering RNA technique to examine the role of RDBP in invasion and proliferation of HCC cells in vitro. Our data showed that both mRNA and protein levels of RDBP were significantly higher in HCC compared to non-HCC liver tissue, and that these levels were also significantly higher in HCC with PVI compared to HCC without PVI. Multivariate analysis revealed that RDBP protein levels were an independent risk factor for early intrahepatic recurrence of HCC within 2 years of surgery. Knockdown of RDBP protein significantly inhibited the proliferation and invasion of cells in vitro. These data demonstrate that RDBP is related to the metastatic potential of HCC, suggesting a possible candidate for prevention of HCC cell metastasis.

Loss of Id2 potentiates the tumorigenic effect of Rb inactivation in a mouse model of retinoblastoma

PURPOSE

In some cancers, the oncogenic consequences of inactivating the retinoblastoma protein (Rb) appear to be mediated by unrestrained activity of the inhibitor of DNA binding protein Id2. The role of Id2 has not yet been investigated in the prototype cancer Rb-defective cancer, retinoblastoma itself. This study investigated whether loss of Id2 modified the effects of Rb inactivation in a mouse model of retinoblastoma.

METHODS

Id2 was analyzed in cultured cells using qPCR, Western blot, and colony formation assays. LH beta-Tag transgenic mice were crossed with Id2 heterozygotes to obtain mice with all three Id2 genotypes. Intraocular tumors were assessed for size, degree of differentiation, mitotic index, and tumor vascular density at 15 weeks of age.

RESULTS

Retinoblastoma cell lines expressed low levels of Id2 mRNA and protein. Depletion of Id2 in Rb-inactivated cells increased clonogenic activity. Id2-deficient tumors in vivo were significantly larger, less differentiated, and more vascularized than Id2-wild-type tumors (P = 0.02, P = 0.01, P = 0.0001, respectively). There was a dosage effect for loss of each Id2 allele with respect to differentiation and vascular density.

CONCLUSIONS

Id2 suppresses rather than promotes tumor progression in this mouse model of retinoblastoma. Id2 can act as either an oncogene or a tumor suppressor depending on context.

Epithelial-mesenchymal transition gene signature to predict clinical outcome of hepatocellular carcinoma

Hepatocellular carcinoma is one of the most lethal cancers worldwide. More accurate stratification of patients at risk is necessary to improve its clinical management. As epithelial-mesenchymal transition is critical for the invasiveness and metastasis of human cancers, we investigated expression profiles of 12 genes related to epithelial-mesenchymal transition through a real-time polymerase chain reaction. From a univariate Cox analysis for a training cohort of 128 hepatocellular carcinoma patients, four candidate genes (E-cadherin [CDH1], inhibitor of DNA binding 2 [ID2], matrix metalloproteinase 9 [MMP9], and transcription factor 3 [TCF3]) with significant prognostic values were selected to develop a risk score of patient survival. Patients with high risk scores calculated from the four-gene signature showed significantly shorter overall survival times. Moreover, the multivariate Cox analysis revealed that four-gene signature (P = 0.0026) and tumor stage (P = 0.0023) were independent prognostic factors for overall survival. Subsequently, the four-gene signature was validated in an independent cohort of 231 patients from three institutions, in which high risk score was significantly correlated with shorter overall survival (P = 0.00011) and disease-free survival (P = 0.00038). When the risk score was entered in a multivariate Cox analysis with tumor stage only, both the risk score (P = 0.0046) and tumor stage (P = 2.6 x 10(-9)) emerged as independent prognostic factors. In conclusion, we suggest that the proposed gene signature may improve the prediction accuracy for survival of hepatocellular carcinoma patients, and complement prognostic assessment based on important clinicopathologic parameters such as tumor stage.

Meta-analysis of archived DNA microarrays identifies genes regulated by hypoxia and involved in a metastatic phenotype in cancer cells

BACKGROUND

Metastasis is a major cancer-related cause of death. Recent studies have described metastasis pathways. However, the exact contribution of each pathway remains unclear. Another key feature of a tumor is the presence of hypoxic areas caused by a lack of oxygen at the center of the tumor. Hypoxia leads to the expression of pro-metastatic genes as well as the repression of anti-metastatic genes. As many Affymetrix datasets about metastasis and hypoxia are publicly available and not fully exploited, this study proposes to re-analyze these datasets to extract new information about the metastatic phenotype induced by hypoxia in different cancer cell lines.

METHODS

Affymetrix datasets about metastasis and/or hypoxia were downloaded from GEO and ArrayExpress. AffyProbeMiner and GCRMA packages were used for pre-processing and the Window Welch t test was used for processing. Three approaches of meta-analysis were eventually used for the selection of genes of interest.

RESULTS

Three complementary approaches were used, that eventually selected 183 genes of interest. Out of these 183 genes, 99, among which the well known JUNB, FOS and TP63, have already been described in the literature to be involved in cancer. Moreover, 39 genes of those, such as SERPINE1 and MMP7, are known to regulate metastasis. Twenty-one genes including VEGFA and ID2 have also been described to be involved in the response to hypoxia. Lastly, DAVID classified those 183 genes in 24 different pathways, among which 8 are directly related to cancer while 5 others are related to proliferation and cell motility. A negative control composed of 183 random genes failed to provide such results. Interestingly, 6 pathways retrieved by DAVID with the 183 genes of interest concern pathogen recognition and phagocytosis.

CONCLUSION

The proposed methodology was able to find genes actually known to be involved in cancer, metastasis and hypoxia and, thus, we propose that the other genes selected based on the same methodology are of prime interest in the metastatic phenotype induced by hypoxia.

An accurate, clinically feasible multi-gene expression assay for predicting metastasis in uveal melanoma

Uveal (ocular) melanoma is an aggressive cancer that often forms undetectable micrometastases before diagnosis of the primary tumor. These micrometastases later multiply to generate metastatic tumors that are resistant to therapy and are uniformly fatal. We have previously identified a gene expression profile derived from the primary tumor that is extremely accurate for identifying patients at high risk of metastatic disease. Development of a practical clinically feasible platform for analyzing this expression profile would benefit high-risk patients through intensified metastatic surveillance, earlier intervention for metastasis, and stratification for entry into clinical trials of adjuvant therapy. Here, we migrate the expression profile from a hybridization-based microarray platform to a robust, clinically practical, PCR-based 15-gene assay comprising 12 discriminating genes and three endogenous control genes. We analyze the technical performance of the assay in a prospective study of 609 tumor samples, including 421 samples sent from distant locations. We show that the assay can be performed accurately on fine needle aspirate biopsy samples, even when the quantity of RNA is below detectable limits. Preliminary outcome data from the prospective study affirm the prognostic accuracy of the assay. This prognostic assay provides an important addition to the armamentarium for managing patients with uveal melanoma, and it provides a proof of principle for the development of similar assays for other cancers.

Id2 deficiency promotes metastasis in a mouse model of ocular cancer

The inhibitor of DNA binding 2 (Id2) basic helix-loop-helix protein interacts genetically and physically with the pocket proteins (Rb, p107 and p130) and has been implicated as an oncogene. In other studies, however, Id2 has been shown to function as a tumor suppressor. Here, we studied the role of Id2 in a well characterized model of ocular cancer in which the three pocket proteins are inactivated by generating mice lacking one or both Id2 alleles. Id2 deficiency had no impact on tumorigenesis in the eye. Unexpectedly, however, Id2 loss significantly increased the rate of metastasis. Liver metastases in Id2 heterozygotes demonstrated significant decrease of Id2 expression and loss of the remaining Id2 allele, strongly suggesting that Id2 inactivation specifically was required for metastasis in this model. These findings provide new insights into the role of Id2 in metastasis.

Methylated cyclin D2 gene circulating in the blood as a prognosis predictor of hepatocellular carcinoma

BACKGROUND

Prognosis of hepatocellular carcinoma (HCC) remains poor because of high recurrence rate. We examined preoperatively the methylated CCND2 gene levels present in the serum following release from HCC cells as a prognosis predictor in patients undergoing curative hepatectomy.

METHODS

Quantitative real-time RT-PCR and quantitative methylation-specific PCR were used to measure methylated CCND2 gene and its mRNA levels.

RESULTS

The CCND2 mRNA levels were down-regulated in HCC with early intrahepatic recurrence (IHR) within 1year of curative hepatectomy. We also identified that this down-regulation was due to promoter hypermethylation. In 70 HCC patients who underwent curative hepatectomy, 39 patients sero-positive for the methylated CCND2 gene (>70pg/ml serum) exhibited a significantly shorter disease-free survival (DFS) period (P=0.02) than the 31 patients who were sero-negative for the methylated CCND2 gene. None of the sero-negative patients demonstrated early IHR, and this method of serum testing did not produce any false-negative predictions for early IHR. Multivariate analysis showed that the serum level of methylated CCND2 was an independent risk factor for DFS (hazard ratio of 1.866, 95% CI: 1.106-3.149).

CONCLUSION

Methylated CCND2 gene in the serum serves as a prognosis predictor of HCC after curative hepatectomy.

Expression and dynamic alteration of hepatoma-related growth factors during malignant transformation of hepatocytes

Hepatocellular carcinoma (HCC) is a common hepatic malignancy worldwide. Its nature of rapid growth results in a grave prognosis. Its treatment is challenging because the mechanisms underlying tumor progression are still largely unknown. Recently, new molecular targets have been confirmed and various targeted agents are now being investigated for the treatment of HCC. The progression of HCC is closely associated with expression of hepatic growth factors that may be molecular targets for HCC treatment. This paper concludes the expression characters and dynamic changes of several hepatoma-related growth factors such as IGF-Ⅱ, VEGF, TGF-β1 and HGF.