The angiotensin-converting enzyme inhibitor, captopril, suppressed hepatic stellate cell activation via NF-kappaB or wnt3α/ß-catenin pathway.

Activation of hepatic stellate cells (HSC) is associated with hepatic fibrogenesis, which is one of complications of diabetes mellitus. Captopril possesses potent anti-inflammation, oxidative stress and fibrosis effects. However, the specific molecular mechanism of captopril in high glucose (HG)-induced hepatic stellate cells has not been elucidated. Following the treatment of HG or captopril treatment for rat hepatic stellate cells (HSC-T6), cell activities were detected by Cell Counting Kit-8 (CCK8) assay. Reactive oxygen species (ROS) levels were determined by ROS staining. The expression of inflammation-related proteins (Interleukin (IL)-1ß, IL-6 and IL-8) and fibrosis-related proteins (fibronectin (FN), collagen I, collagen III, collagen IV, matrix metallopeptidase (MMP-2 and MMP-9) were determined by Western blot. Captopril significantly decreased HSC-T6 cell viability induced by HG in a dose-dependent manner, as well as decreased levels of malondialdehyde (MDA), ROS, pro-inflammatory markers and fibrosis-related proteins, while upregulated superoxide dismutase (SOD) activities. We further found that captopril decreased the ratio of p-IκBα/IκBα and the ratio of p-p65/p65. Intriguing, phorbol myristate acetate (PMA) or LiCl was able to significantly reverse the captopril-induced alteration of oxidative stress-, inflammation- and fibrosis-marker levels. In conclusion, in HG-stimulated HSC-T6 cells, captopril displayed a potent ability to inhibit oxidative stress, inflammation and hepatic fibrogenesis via NF-kappaB or wnt3α/ß-catenin. These results demonstrated the mechanism of captopril as well as the role of the NF-kappaB or wnt3α/ß-catenin on HSC-T6 activation induced by HG.

Epigenetic inactivation of IRX4 is responsible for acceleration of cell growth in human pancreatic cancer.

Epigenetic gene silencing by aberrant DNA methylation is one of the important mechanisms leading to loss of key cellular pathways in tumorigenesis. Methyl-CpG-targeted transcriptional activation (MeTA) reactivates hypermethylation-mediated silenced genes in a different way from DNA-demethylating agents. Microarray coupled with MeTA (MeTA-array) identified seven commonly hypermethylation-mediated silenced genes in 12 pancreatic ductal adenocarcinoma (PDAC) cell lines. Among these, we focused on IRX4 (Iroquois homeobox 4) because IRX4 is located at chromosome 5p15.33 where PDAC susceptibility loci have been identified through genome-wide association study. IRX4 was greatly downregulated in all of the analyzed 12 PDAC cell lines by promoter hypermethylation. In addition, the IRX4 promoter region was found to be frequently and specifically hypermethylated in primary resected PDACs (18/28: 64%). Reexpression of IRX4 inhibited colony formation and proliferation in two PDAC cell lines, PK-1 and PK-9. In contrast, knockdown of IRX4 accelerated cell proliferation in an IRX4-expressing normal pancreatic ductal epithelial cell line, HPDE-1. Because IRX4 is a sequence-specific transcription factor, downstream molecules of IRX4 were pursued by microarray analyses utilizing tetracycline-mediated IRX4 inducible PK-1 and PK-9 cells; CRYAB, CD69, and IL32 were identified as IRX4 downstream candidate genes. Forced expression of these genes suppressed colony formation abilities for both PK-1 and PK-9. These results suggest that DNA methylation-mediated silencing of IRX4 contributes to pancreatic tumorigenesis through aberrant transcriptional regulation of several cancer-related genes.

Methylation-mediated silencing of the LIM homeobox 6 (LHX6) gene promotes cell proliferation in human pancreatic cancer.

Epigenetic gene silencing by aberrant DNA methylation leads to loss of key cellular pathways in tumorigenesis. DNA methylation-mediated silenced genes in pancreatic cancer were searched for using the methyl-CpG targeted transcriptional activation (MeTA) method, and LHX6 (LIM homeobox 6), a transcription factor involved in embryogenesis and head development, was selected as a strong candidate gene. LHX6 was downregulated in most of the pancreatic cancer cell lines (83%, 10/12), mainly through promoter hypermethylation and histone deacetylation. Furthermore, LHX6 was methylated in primary pancreatic cancer specimens (57%, 16/28) in a tumor-specific manner. Re-expression of LHX6 inhibited colony formation and proliferation in LHX6 low-expressing pancreatic cancer cell lines, PK-1 and PK-9. In contrast, knockdown of LHX6 accelerated cell proliferation in LHX6 high-expressing pancreatic cancer cell lines, PCI-35 and MIA PaCa-2. In order to analyze LHX6 downstream genes, we performed microarray analyses using LHX6 inducible PK-1 and PK-9 and found that LHX6 induction upregulated several genes that had tumor suppressive functions. Among these, we focused on TFPI2 (Tissue factor pathway inhibitor-2) and found that TFPI2 was greatly downregulated in all twelve pancreatic cancer cell lines. Our present results suggest that epigenetic inactivation of LHX6 plays an important role in pancreatic tumorigenesis by promoting cell proliferation through aberrant transcriptional regulation of several cancer-related genes.

Phase I study of taselisib in Japanese patients with advanced solid tumors or hormone receptor-positive advanced breast cancer.

Taselisib is a potent and selective phosphatidylinositide 3-kinase (PI3K) inhibitor. The present article reports the first study of taselisib administration in Japanese patients. The aim of this 2-stage, phase I, multicenter, open-label, dose-escalation study was to evaluate the safety, pharmacokinetics, and preliminary efficacy of taselisib as monotherapy in Japanese patients with advanced solid tumors (stage 1), and as part of combination therapy in Japanese patients with hormone receptor (HR)-positive locally advanced or recurrent breast cancer (stage 2). In stage 1, oral taselisib tablets 2, 4, and 6 mg/d were given in 28-day cycles. In stage 2, successive cohorts of patients received oral taselisib tablets (2 or 4 mg/d) with i.m. fulvestrant 500 mg. Nine and 6 patients were enrolled in stage 1 and stage 2, respectively. Taselisib was well tolerated. No dose-limiting toxicities were experienced in any cohort of patients and no deaths were observed. The most common treatment-related adverse events in stage 1 and stage 2, respectively, were rash (55.6%, 66.7%), diarrhea (44.4%, 66.7%), and stomatitis (44.4%, 66.7%). Taselisib was rapidly absorbed after dosage; its half-life was 12.9-32.0 hours in stage 1 and 16.1-26.5 hours in stage 2. Two patients achieved partial response (PR), 5 patients had stable disease (SD) and 2 patients had progressive disease (PD) in stage 1, and 1 patient had PR and 3 patients had SD in stage 2. All patients with PR were positive for PIK3CA gene mutations. These preliminary data suggest that taselisib may be effective in patients with PIK3CA-mutated solid tumors or HR-positive advanced breast cancer.

The expression of S100A4 in human pancreatic cancer is associated with invasion.

OBJECTIVES: Pancreatic cancer is one of the most lethal malignancies; its poor prognosis is strongly associated with invasion and metastasis. Expression of S100A4 has been reported to correlate with poor prognosis in various cancers. We have investigated the role of S100A4 in pancreatic cancer tumorigenesis and its clinicopathologic significance. METHODS: Protein expression of S100A4 was examined by Western blot in pancreatic cancer cell lines and a human pancreatic ductal epithelium cell line, HPDE-6. Then the expressions of S100A4, TP53, and CD133 were examined immunohistochemically in resected specimens from 83 patients with pancreatic cancer to clarify their clinicopathologic significance. Survival analyses were performed using the Kaplan-Meier method and the Mantel-Cox method. RESULTS: Forty-eight (58%) of 83 patients with pancreatic cancer positively expressed S100A4, and 50 (60%) and 29 (36%) patients positively expressed TP53 and CD133, respectively. S100A4 expression was significantly correlated with perineural invasion (P = 0.029) and invasion pattern (P = 0.001). Neither TP53 nor CD133 expression showed significant correlations with any other parameters. CONCLUSIONS: Our present results suggest that S100A4 plays an important role in the invasiveness, particularly with perineural invasion and invasion pattern, of pancreatic cancer. Development of new strategies targeting S100A4 or its downstream effectors is warranted.

S100A4, frequently overexpressed in various human cancers, accelerates cell motility in pancreatic cancer cells.

S100A4, a member of the Ca(2+) dependent S100 protein family, is reported to associate with metastasis through regulation of the motility and invasiveness of cancer cells. A high level of S100A4 protein has been reported in a variety of cancers, including pancreatic cancer. However, its biological role in pancreatic carcinogenesis is largely unknown. We previously reported that S100A4 is frequently overexpressed and that RNAi-mediated knockdown induces apoptosis and suppression of cell growth, motility, and invasiveness. In this study, we analyzed the effects of forced expression of S100A4 in pancreatic cancer cell lines without S100A4-upregulation. We used two cell lines without upregulation of S100A4 (PCI-35 and PCI-43) as well as two cell lines with highly upregulated S100A4 as the control (MIA PaCa-2 and PAN-07-JCK). Cells did not show acceleration of their growth and invasiveness after forced expression of S100A4, but remarkable acceleration of cell motility was observed only in PCI-35 and PCI-43. We further performed microarray analyses using PCI-35 and PCI-43 with and without forced expression of S100A4 and identified 72 and 18 genes that were 2-fold or more upregulated or downregulated, respectively, in both cell lines after forced expression of S100A4. Our results suggest that S100A4 is crucial for cell motility in pancreatic cancer and that some downstream genes may play important roles in cell motility.

siRNA-mediated knockdown against CDCA1 and KNTC2, both frequently overexpressed in colorectal and gastric cancers, suppresses cell proliferation and induces apoptosis.

Ndc80 has been shown to play an important role in stable microtubule-kinetochore attachment, chromosome alignment, and spindle checkpoint activation in mitosis. It is composed of two heterodimers, CDCA1-KNTC2 and SPC24-SPC25. Overexpression of CDCA1 and KNTC2 is reported to be associated with poor prognosis in non-small cell lung cancers (NSCLC), and siRNA-mediated knockdown against CDCA1 or KNTC2 has been found to inhibit cell proliferation and induction of apoptosis in NSCLC, ovarian cancer, cervical cancer and glioma. Therefore, CDCA1 and KNTC2 can be considered good candidates for molecular target therapy as well as diagnosis in some cancers. However, the role of the Ndc80 complex in colorectal and gastric cancers (CRC and GC) still remains unclear. In the present study, we used qRT-PCR to evaluate the expression levels of CDCA1, KNTC2, SPC24 and SPC25 in CRC and GC and employed siRNA-mediated knockdown to examine cell proliferation and apoptosis. mRNA overexpression of these four genes was observed in CRCs and GCs when compared with the corresponding normal mucosae. Additionally, the expression levels of tumor/normal ratios of CDCA1, KNTC2, SPC24 and SPC25 correlated with each other in CRCs. MTT assays revealed that cell growths after the siRNA-mediated knockdown of either CDCA1 or KNTC2 were significantly suppressed, and flow cytometry analyses revealed significant increases of the subG1 fractions after knockdown against both genes. Our present results suggest that expressional control of component molecules of Ndc80 can be utilized for molecular target therapy of patients with CRC and GC.

RNA interference targeting against S100A4 suppresses cell growth and motility and induces apoptosis in human pancreatic cancer cells.

S100A4 protein belongs to the S100 subfamily, which has grown to be one of the large subfamilies of the EF-hand Ca(2+)-binding proteins, and overexpression of S100A4 is suggested to associate with cell proliferation, invasion, and metastasis. We observed frequent overexpression of S100A4 in pancreatic cancer cell lines and further analyzed RNAi-mediated knockdown to address the possibility of its use as a therapeutic target for pancreatic cancer. The specific knockdown of S100A4 strongly suppressed cell growth, induced G2 arrest and eventual apoptosis, and decreased cell migration. Furthermore, microarray analyses revealed that knockdown of S100A4 induced expression of the tumor suppressor genes PRDM2 and VASH1. Our present results suggest the possibility that the inhibition of S100A4 can be utilized in antitumor applications for patients with pancreatic cancer.

The methylation status of FBXW7 beta-form correlates with histological subtype in human thymoma.

FBXW7 is reported to be a tumor suppressor gene, and the functional inactivation of FBXW7 has been reported in various human tumors. In this study, we investigated the FBXW7 gene in human thymoma; although no mutations were evident, a significantly high frequency of methylation in the FBXW7 beta-form promoter was observed in types B1 or higher (P=0.014). We propose a novel mechanism for the pathogenesis of thymoma by FBXW7 beta-form and hypothesize that expressional suppression plays an important role in the malignant potential of thymoma.

Promoter hypermethylation is not the major mechanism for inactivation of the FBXW7 beta-form in human gliomas.

FBXW7 has been reported to be a candidate tumor suppressor gene on 4q31. Three isoforms (alpha-form, beta-form, and gamma-form) of FBXW7 are produced from mRNAs with distinct 5' exons. Our previous study identified the specific suppression of the mRNA expression of the FBXW7 beta-form in human gliomas. Because this form is the major FBXW7 isoform in the human brain, we elucidated the silencing mechanisms for the FBXW7 beta-form in gliomas. No genetic alterations were found in the whole FBXW7 gene including putative promoter region of the beta-form. Treatments with 5-azacytidine and trichostatin A did not induce re-expression. A sodium bisulfite-modification assay indicated that CpG sequences in the promoter of FBXW7 beta-form were not methylated in glioma cells. Meanwhile we searched for the expression of FBXW7 and the sodium bisulfite sequences in normal human peripheral blood cells, and we surprisingly found that the mRNA expression of the FBXW7 beta-form was highly suppressed and the CpG sequences in the promoter region of the FBXW7 beta-form were heavily methylated. Our data suggest that the inactivation of the FBXW7 beta-form plays an important role in the pathogenesis of gliomas and that an unknown mechanism(s) other than mutation and methylation is the major cause of the suppression of the FBXW7 beta-form in gliomas.

siRNA targeting against EGFR, a promising candidate for a novel therapeutic application to lung adenocarcinoma.

OBJECTIVE: To understand the molecular pathogenesis of lung cancer and to establish a novel therapeutic application, we examined the genetic alterations in lung cancer, and studied the effects of gefitinib and siRNA-mediated knockdown of EGFR on lung cancer. METHODS: We analyzed mutations in EGFR, KRAS, TP53, and ERBB2 in 198 surgically resected lung cancer specimens. We then analyzed the effects of gefitinib and siRNA treatment on lung adenocarcinoma cell lines. RESULTS: Mutations in EGFR were found only in adenocarcinoma (35 of 106 adenocarcinoma), mainly in females (73%). Mutually exclusive mutations of EGFR and KRAS genes were observed. Mutations of EGFR were well associated with a positive response to gefitinib. Cells with EGFR mutations were very sensitive to gefitinib as well as siRNA-mediated knockdown of EGFR, those with KRAS mutations responded poorly, and those without mutations of KRAS and EGFR showed moderate responses to both treatments. CONCLUSIONS: Our present results imply that (1) mutation analyses of EGFR and KRAS provide valuable information about whether or not to apply treatments targeting against EGFR and the selection of dosage for such treatments, and (2) siRNA-mediated knockdown is effective in lung adenocarcinomas with EGFR mutation, probably in those with resistance to gefitinib by acquired mutation in EGFR.

Orthotopic implantation mouse model and cDNA microarray analysis indicates several genes potentially involved in lymph node metastasis of colorectal cancer.

In colorectal cancer (CRC) patients, metastasis to the regional lymph node (LN) is an important first step in the dissemination of cancers. To identify the genes possibly involved in LN metastasis of CRC, we analyzed LN metastases in an orthotopic implantation mouse model with 22 CRC cell lines using Matrigel, an extracellular matrix protein derived from mice sarcoma, and combined the data with gene expression profiles of cDNA microarray of those cell lines. With this implantation analysis, the incidence of LN metastasis was 60% in 228 orthotopically implanted mice and varied from 100% to 0% among the cell lines. KM12c and Clone A showed LN metastasis in all orthotopically implanted mice, but DLD-1, HCT-8, and SW948 did not show LN metastases at all. In contrast, the incidence of liver and lung metastasis in 22 CRC cell lines was 13% and 1%, respectively. Combining those data with cDNA microarray in vitro, we isolated 636 genes that were differentially expressed depending on the incidence of LN metastasis. Among those genes, the expression level of ring finger protein 125 (RNF125), previously known as an E3 ubiquitin ligase in T cell activation, was significantly different between primary tumors in Stage III CRC patients with LN metastasis and Stage II patients without LN metastasis. In conclusion, the orthotopic implantation mice model with Matrigel was useful, and we isolated candidate genes such as RNF125 that possibly play an important role in LN metastasis of CRC cells.

The FBXW7 beta-form is suppressed in human glioma cells.

FBXW7 (F-box and WD40 domain protein 7) is an F-box protein with 7 tandem WDs (tryptophan-aspartic acid) that functions as a phosphoepitope-specific substrate recognition component of SCF (Skp1-Cul1-F-box protein) ubiquitin ligases and catalyzes the ubiquitination of proteins promoting cell proliferation, such as CCNE1, MYC, AURKA, NOTCH1, and JUN, which are frequently activated in a wide range of human cancers. FBXW7 is a candidate tumor suppressor, and mutations have been reported in some human tumors. In this study, we analyzed 84 human tumor cell lines in search for genetic alterations of FBXW7, as well as mRNA and protein expressional changes, and compared them with expression levels of the CCNE1, MYC, and AURKA proteins. We found a novel nonsense mutation in a colon cancer cell line SCC and confirmed the missense mutations in SKOV3, an ovarian cancer cell line, and LoVo, a colon cancer cell line. Moreover, suppressed expression of FBXW7 accompanied by activation of the target proteins were observed in ovarian, colon, endometrial, gastric, and prostate cancers. It is notable that highly suppressed mRNA expression of the FBXW7 beta-form was found in all the human glioma cell lines analyzed; enhanced expressions of CCNE1, MYC, and AURKA were observed in these cells. Our present results imply that FBXW7 plays a pivotal role in many tissues by controlling the amount of cell cycle promoter proteins and that dysfunction of this protein is one of the essential steps in carcinogenesis in multiple organs.

RET finger protein enhances MBD2- and MBD4-dependent transcriptional repression.

We recently demonstrated that MBD4 possesses the ability to repress transcription through methyl-CpG and is associated with methylated promoters in the CDKN2A and MLH1 genes. In order to further investigate the role of MBD4 in methylation-based transcriptional repression, a yeast two-hybrid screening was performed, and the RET finger protein (RFP) was found to be one of the major proteins that interact with the transcriptional repression domain in MBD4. The effect of the MBD4-mediated transcriptional repression in methylated CDKN2A and MLH1 promoters was extremely enhanced by the overexpression of RFP. Furthermore, RFP forms a protein complex not only with MBD4 but also with MBD2 or MBD3 and was shown to enhance transcriptional repression through MBD2. These results suggest that RFP is a mediator connecting several MBD proteins and allowing the formation of a more potent transcriptional repressor complex. Because RFP has been detected at high levels in a variety of tumor cell lines as well as testis, and embryos, RFP may have an important role in the enhancement of transcriptional repression through MBD proteins in tumorigenesis, spermatogenesis, and embryogenesis.

The thymine DNA glycosylase MBD4 represses transcription and is associated with methylated p16(INK4a) and hMLH1 genes.

Epigenetic silencing through methyl-CpG (mCpG) is implicated in many biological patterns such as genome imprinting, X chromosome inactivation, and cancer development. In this process, the mCpG binding domain (MBD) proteins play an essential role in transmitting epigenetic information to downstream regulatory proteins. Among the five MBD proteins identified so far, MBD4 has been the only exception; it has long been thought to be a DNA repair protein. Herein we demonstrate that MBD4 has the ability to repress transcription through mCpG. Transcriptional repression by the MBD4 is histone deacetylase (HDAC) dependent, and MBD4 directly binds to Sin3A and HDAC1 at three central regions that overlap transcriptional repression domains. Furthermore, a chromatin immunoprecipitation assay clearly shows that MBD4 binds to hypermethylated promoters of the p16(INK4a) and hMLH1 genes. These results suggest that MBD4 is one of the essential components involved in epigenetic silencing in cancer and its repair activity is necessary for the maintenance of hypermethylated promoters.