Expression of mucin 1 possessing a 3'-sulfated core1 in recurrent and metastatic breast cancer.

Breast cancer is the most frequent cancer threatening the lives of women between the ages of 30 and 64. The cancer antigen 15-3 assay (CA15-3) has been widely used for the detection of breast cancer recurrence; however, its sensitivity and specificity are inadequate. We previously found that the breast cancer cell line YMBS secretes mucin 1 possessing 3'-sulfated core1 (3Score1-MUC1) into the medium. Therefore, we here evaluated whether 3Score1-MUC1 is secreted into the blood streams of breast cancer patients, and whether it can serve as an improved breast cancer marker. We developed a lectin-sandwich immunoassay, called Gal4/MUC1, using a 3'-sulfated core1-specific galectin-4 and a MUC1 monoclonal antibody. Using the Gal4/MUC1 assay method, we found that 3Score1-MUC1 was profoundly expressed in the blood streams of patients with recurrent and/or metastatic breast cancer. The positive ratio of the Gal4/MUC1 assay was higher than that of the CA15-3 assay in both primary (n = 240) and relapsed (n = 43) patients, especially in the latter of which the positive ratio of Gal4/MUC1 was 86%. whereas that of CA15-3 was 47%. Furthermore, serum Gal4/MUC1 levels could more sensitively reflect the recurrence of primary breast cancer patients after surgery. Therefore, the Gal4/MUC1 assay should be an excellent alternative to the CA15-3 tumor marker for tracking the recurrence and metastasis of breast cancer.

Dendritic cells transfected with heat-shock protein 70 messenger RNA for patients with hepatitis C virus-related hepatocellular carcinoma: a phase 1 dose escalation clinical trial.

BACKGROUND: We previously reported overexpression of heat-shock protein (HSP) 70 in hepatitis C virus (HCV)-related hepatocellular carcinoma (HCC) using proteomic profiling and immunohistochemical staining (IHS). This suggested that HSP70 could be a molecular target for treatment of HCC. METHODS: Twelve patients with HCV-related HCC were enrolled in a phase 1 clinical trial. Dendritic cells (DCs) transfected with HSP70 mRNA (HSP70-DCs) induced by electroporation were injected intradermally. Patients were treated three times every 3 weeks. The number of HSP70-DCs injected was 1 × 10(7) as the lowest dose, then 2 × 10(7) as the medium dose, and then 3 × 10(7) as the highest dose. Immunological analyses were performed. FINDINGS: No adverse effects of grade III/IV, except one grade III liver abscess at the 3 × 10(7) dose, were observed. Thus, we added three more patients to confirm whether 3 × 10(7) is an appropriate dose. Eventually, we chose 3 × 10(7) as the recommended dose of DCs. Complete response (CR) without any recurrence occurred in two patients, stable disease in five, and progression of disease in five. The two patients with CR have had no recurrence for 44 and 33 months, respectively. IHS in one patient who underwent partial hepatectomy showed infiltration of CD8+ T cells and granzyme B in tumors, indicating that the dominant immune effector cells were cytotoxic T lymphocytes with tumor-killing activity. INTERPRETATION: This study demonstrated that HSP70-DCs therapy is both safe and feasible in patients with HCV-related HCC. Further clinical trials should be considered.

Adoptive immunotherapy with MUC1-mRNA transfected dendritic cells and cytotoxic lymphocytes plus gemcitabine for unresectable pancreatic cancer.

BACKGROUND: We previously reported the clinical efficacy of adoptive immunotherapy (AIT) with dendritic cells (DCs) pulsed with mucin 1 (MUC1) peptide and cytotoxic T lymphocytes (CTLs). We also reported that gemcitabine (GEM) enhances anti-tumor immunity by suppressing regulatory T cells. Therefore, in the present study, we performed combination therapy with AIT and GEM for patients with unresectable or recurrent pancreatic cancer. PATIENTS AND METHODS: Forty-two patients with unresectable or recurrent pancreatic cancer were treated. DCs were generated by culture with granulocyte macrophage colony-stimulating factor and interleukin-4 and then exposed to tumor necrosis factor-α. Mature DCs were transfected with MUC1-mRNA by electroporation (MUC1-DCs). MUC1-CTLs were induced by co-culture with YPK-1, a human pancreatic cancer cell line, and then with interleukin-2. Patients were treated with GEM, while MUC1-DCs were intradermally injected, and MUC1-CTLs were intravenously administered. RESULTS: Median survival time (MST) was 13.9 months, and the 1-year survival rate was 51.1%. Of 42 patients, one patient had complete response (2.4%), three patients had partial response (7.1%) and 22 patients had stable disease (52.4%). The disease control ratio was 61.9%. The MST and 1-year survival rate of 35 patients who received more than 1 × 10(7) MUC1-DCs per injection was 16.1 months and 60.3%, respectively. Liver metastasis occurred in only 5 patients among 35 patients without liver metastasis before treatment. There were no severe toxicities associated with AIT. CONCLUSION: AIT with MUC1-DCs and MUC1-CTLs plus GEM may be a feasible and effective treatment for pancreatic cancer.

Frizzled homolog proteins, microRNAs and Wnt signaling in cancer.

Wnt signaling pathways play important roles in tumorigenesis and are initiated by binding of Wnt to various receptors including frizzleds (FZDs). FZDs are one of several families of receptors comprised of FZD/LRP/ROR2/RYK in the Wnt signaling pathway. Expression of some FZD receptors are up regulated, thereby activating the Wnt signaling pathway and is correlated with cancer malignancy and patient outcomes (recurrence and survival) in many cancers. The FZD family contains ten genes in humans and their function has not been completely examined including the regulatory mechanisms of FZD genes in cancer. Knockdown of FZDs may suppress the Wnt signaling pathway resulting in decreased cell growth, invasion, motility and metastasis of cancer cells. Recently a number of microRNAs (miRNAs) have been identified and reported to be important in several cancers. MiRNAs regulate target gene expression at both the transcription and translation levels. The study of miRNA is a newly emerging field and promises to be helpful in understanding the pathogenesis of FZDs in cancer. In addition, miRNAs may be useful in regulating FZDs in cancer cells. Therefore, the aim of this review is to discuss current knowledge of the functional mechanisms of FZDs in cancer, including regulation by miRNAs and the potential for possible use of miRNAs and FZDs in future clinical applications.

Identification of genes specifically methylated in Epstein-Barr virus-associated gastric carcinomas.

We studied the comprehensive DNA methylation status in the naturally derived gastric adenocarcinoma cell line SNU-719, which was infected with the Epstein-Barr virus (EBV) by methylated CpG island recovery on chip assay. To identify genes specifically methylated in EBV-associated gastric carcinomas (EBVaGC), we focused on seven genes, TP73, BLU, FSD1, BCL7A, MARK1, SCRN1, and NKX3.1, based on the results of methylated CpG island recovery on chip assay. We confirmed DNA methylation of the genes by methylation-specific PCR and bisulfite sequencing in SNU-719. The expression of the genes, except for BCL7A, was upregulated by a combination of 5-Aza-2'-deoxycytidine and trichostatin A treatment in SNU-719. After the treatment, unmethylated DNA became detectable in all seven genes by methylation-specific PCR. We verified DNA methylation of the genes in 75 primary gastric cancer tissues from 25 patients with EBVaGC and 50 EBV-negative patients who were controls. The methylation frequencies of TP73, BLU, FSD1, BCL7A, MARK1, SCRN1, and NKX3.1 were significantly higher in EBVaGC than in EBV-negative gastric carcinoma. We identified seven genes with promoter regions that were specifically methylated in EBVaGC. Inactivation of these genes may suppress their function as tumor suppressor genes or tumor-associated antigens and help to develop and maintain EBVaGC.

UGT1A1*6, 1A7*3, and 1A9*22 genotypes predict severe neutropenia in FOLFIRI-treated metastatic colorectal cancer in two prospective studies in Japan.

UNLABELLED: Retrospective studies have suggested that UDP-glucuronosyltransferase (UGT)1A1, UGT1A7, and UGT1A9 predict severe toxicity and efficacy of irinotecan-containing regimens. We prospectively evaluated the impact of UGT1A genotypes and haplotypes on severe toxicity and efficacy in patients treated with fluorouracil, leucovorin, and irinotecan combination chemotherapy (FOLFIRI) for metastatic colorectal cancer (mCRC) from the two prospective multicenter phase II studies in Japan. The FLIGHT1 study was a first-line FOLFIRI trial, and FLIGHT2 was a FOLFOX-refractory, second-line FOLFIRI trial. A total of 73 patients agreed to additional analysis, and were genotyped for UGT1A polymorphisms, UGT1A1*28 (TA6>TA7), UGT1A1*6 (211G>A), UGT1A1*27 (686C>A), UGT1A1*60 (-3279T>G), UGT1A1*93 (-3156G>A), UGT1A7 (-57T>G), UGT1A7*3 (387T>G, 622T>C), and UGT1A9*22 (T9>T10). Of 73 patients, 34 developed G3/4 severe hematological toxicities. The toxicities were significantly more frequent in patients with UGT1A1*6 (211A), UGT1A7 (387G), and UGT1A9*22 reference alleles (T9). Haplotype I, which consists of all favorable alleles, was associated with a significant reduction in hematologic toxicity (P = 0.031). In contrast, haplotype II, which contains four high-risk alleles, showed significantly higher hematologic toxicity than the other haplotypes (P = 0.010). Six out of seven patients who were homozygous for UGT1A1*28 or *6 experienced severe hematological toxicity despite the fact that their response rate was not impaired (42.9%). We concluded that UGT1A polymorphisms, especially UGT1A1*6, are important for the prediction of severe toxicity of FOLFIRI in northeast Asian populations. In this regard, haplotype analyses should substantially impact the prediction of severe hematological toxicities of FOLFIRI. ( CLINICAL TRIAL REGISTRATION: UMIN000002388 and UMIN000002476).

Possible involvement of Wnt11 in colorectal cancer progression.

Our previous report revealed that the expression of Frizzled-7 (FZD7) in colorectal cancer (CRC) and its possible role in CRC progression. In this study we measured the expression levels of candidate FZD7 ligands, Wnt3 and Wnt11 in colon cancer cell lines (n = 7) and primary CRC tissues (n = 133) by quantitative RT-PCR. We also examined the functional effects of Wnt11 with the use of Wnt11 transfectants of colon cancer HCT-116 cells. Wnt11 transfectants showed the increased proliferation and migration/invasion activities compared to mock cells. Western blot analysis of transfectants revealed that phosphorylation of JNK and c-jun was increased after Wnt11 transfection. Wnt11 mRNA expression was significantly higher in the stage I, II, III, or IV tumor tissues than in non-tumor tissues (overall P < 0.003), while there was no significant difference in Wnt3 mRNA expression between tumor and non-tumor tissues. In addition, Wnt11 mRNA expression was significantly higher in patients with recurrence or death after surgery than in those with no recurrence (disease free) after surgery (P = 0.018). We also compared the expression levels of Wnt11 mRNA with those of FZD7 mRNA in the same CRC samples. Wnt11 mRNA expression was significantly higher in patients with higher FZD7 mRNA levels than in those with lower FZD7 mRNA levels (P = 0.0005). The expression levels of Wnt11 mRNA were correlated with those of FZD7 mRNA (P < 0.0001). These data suggest that Wnt11 may play an important role in CRC progression.

Role of DNA methylation in the development of Epstein-Barr virus-associated gastric carcinoma.

The frequencies of DNA methylation of certain tumor-related genes are higher in Epstein-Barr virus (EBV)-associated gastric carcinomas than in EBV-negative gastric carcinomas. EBV-associated gastric carcinomas have distinct clinicopathological features; however, there are no case-control studies comparing methylation frequency between EBV-associated gastric carcinomas and controls that have been adjusted according to the clinicopathological features of EBV-associated gastric carcinomas. This study evaluated 25 EBV-associated gastric carcinomas that were positive for EBV-encoded small RNA 1 (EBER-1) by in situ hybridization and 50 EBV-negative gastric carcinomas that were matched with the EBV-associated gastric carcinomas by age, sex, histology, depth of tumor invasion, and stage. Methylation status of 16 loci associated with tumor-related genes was analyzed by methylation-specific polymerase chain reaction (PCR) to identify genes in which DNA methylation specifically occurred in EBV-associated gastric carcinomas. Methylation frequencies of 12 of the 16 genes were higher in EBV-associated gastric carcinomas than in EBV-negative controls, and the frequency of methylation of 6 specific loci (MINT2, MINT31, p14, p16, p73, and RUNX3) was significantly higher in EBV-associated gastric carcinomas than in EBV-negative controls. There were no significant differences in the methylation frequencies of the other genes. The mean methylation index in EBV-associated gastric carcinomas was significantly higher than that in EBV-negative controls. DNA methylation of tumor suppressor genes that regulate the cell cycle and apoptosis specifically occurred in EBV-associated gastric carcinomas. Aberrant DNA methylation might lead to the development and progression of EBV-associated gastric carcinoma.

Germline copy number variations associated with breast cancer susceptibility in a Japanese population.

Although copy number variations (CNVs) are expected to affect various diseases, little is known about the association between CNVs and breast cancer susceptibility. Therefore, we investigated this relation. Array comparative genomic hybridization was performed to search for candidate CNVs related to breast cancer susceptibility. Subsequent quantitative real-time polymerase chain reaction was carried out for confirmation. We found seven CNV markers associated with breast cancer risk. The means of the relative copy numbers of patients with a history of breast cancer and women in the control group were 0.8 and 1.8 for Hs06535529_cn on 1p36.12 (P < 0.0001), 2.9 and 2.2 for Hs03103056_cn on 3q26.1 (P < 0.0001), 1.2 and 1.8 for Hs03899300_cn on 15q26.3 (P < 0.0001), 1.0 and 1.5 for Hs03908783_cn on 15q26.3 (P < 0.0001), and 1.1 and 1.7 for Hs03898338_cn on 15q26.3 (P < 0.0001), respectively. Interestingly, nine or more copies of Hs04093415_cn on 22q12.3 were found only in 8/193 (4.1 %) patients with a history of breast cancer and in none of the controls (P = 0.0081). Similarly, 12 or more copies of Hs040908898_cn on 22q12.3 were found only in 7/193 (3.6 %) patients with a history of breast cancer and in none of the controls (P = 0.016). A combination of two CNVs resulted in 80.3 % sensitivity, 80.6 % specificity, 82.4 % positive predictive value, and 78.3 % negative predictive value for the prediction of breast cancer susceptibility. These findings may lead to a new means of risk assessment for breast cancer. Confirmatory studies using independent data sets are needed to support our findings.

Epigenetic inactivation of SFRP genes allows constitutive WNT signaling in colorectal cancer.

Aberrant WNT pathway signaling is an early progression event in 90% of colorectal cancers. It occurs through mutations mainly of APC and less often of CTNNB1 (encoding beta-catenin) or AXIN2 (encoding axin-2, also known as conductin). These mutations allow ligand-independent WNT signaling that culminates in abnormal accumulation of free beta-catenin in the nucleus. We previously identified frequent promoter hypermethylation and gene silencing of the genes encoding secreted frizzled-related proteins (SFRPs) in colorectal cancer. SFRPs possess a domain similar to one in the WNT-receptor frizzled proteins and can inhibit WNT receptor binding to downregulate pathway signaling during development. Here we show that restoration of SFRP function in colorectal cancer cells attenuates WNT signaling even in the presence of downstream mutations. We also show that the epigenetic loss of SFRP function occurs early in colorectal cancer progression and may thus provide constitutive WNT signaling that is required to complement downstream mutations in the evolution of colorectal cancer.

MicroRNA-1826 directly targets beta-catenin (CTNNB1) and MEK1 (MAP2K1) in VHL-inactivated renal cancer.

The aim of this project is to identify new therapeutic microRNAs (miRNAs) for von Hippel-Lindau (VHL)-inactivated renal cancer cells. We initially identified several potential miRNAs targeting CTNNB1 and MEK1 using several targets scan algorithms. Only miR-1826 was found to target CTNNB1 and MEK1. Therefore, we focused on miRNA-1826 and performed 3' untranslated region (UTR) luciferase assay, functional analyses and association study between miR-1826 expression and renal cancer patient outcomes. miR-1826 expression was significantly lower in renal cancer tissues compared with non-neoplastic areas and lower expression was significantly associated with overall shorter survival and earlier recurrence after radical nephrectomy. Following miR-1826 transfection, 3' UTR luciferase activity and protein expression of beta-catenin and MEK1 were significantly downregulated in renal cancer cells. Introduction of miR-1826 also inhibited renal cancer cell proliferation, invasion and migration. Additionally, miR-1826 promoted apoptosis and G(1) arrest in VHL-inactivated renal cancer cells. Knockdowns of CTNNB1 and MEK1 by small interfering RNAs reproduced the tumor-suppressive effect of miR-1826. Our data suggest that the miR-1826 plays an important role as a tumor suppressor by downregulating beta-catenin and MEK1 in VHL-inactivated renal cancers.

MicroRNA-1826 targets VEGFC, beta-catenin (CTNNB1) and MEK1 (MAP2K1) in human bladder cancer.

The Wnt/beta-catenin (CTNNB1) and Ras-Raf-MEK-ERK signaling pathway play an important role in bladder cancer (BC) progression. Tumor-suppressive microRNAs (miRNAs) targeting these cancer pathways may provide a new therapeutic approach for BC. We initially identified miRNA-1826 potentially targeting CTNNB1, VEGFC and MEK1 using several target scan algorithms. Also 3' untranslated region luciferase activity and protein expression of these target genes were significantly downregulated in miR-1826-transfected BC cells (J82 and T24). The expression of miR-1826 was lower in BC tissues and inverse correlation of miR-1826 with several clinical parameters (pT, grade) was observed. Also the expression of miR-1826 was much lower in three BC cell lines (J82, T24 and TCCSUP) compared with a normal bladder cell line (SV-HUC-1). We then performed analyses to look at miR-1826 function and found that miR-1826 inhibited BC cell viability, invasion and migration. We also found increased apoptosis and G(1) cell cycle arrest in miR-1826-transfected BC cells. To examine whether the effect of miR-1826 was through CTNNB1 (beta-catenin) or MEK1 knockdown, we knocked down CTNNB1/MEK1 messenger RNA using a small interfering RNA (siRNA) technique. We observed that CTNNB1 or MEK1 siRNA knockdown resulted in effects similar to those with miR-1826 in BC cells. In conclusion, our data suggest that the miR-1826 plays an important role as tumor suppressor via CTNNB1/MEK1/VEGFC downregulation in BC.

Association of RASSF1A genotype and haplotype with the progression of clear cell renal cell carcinoma in Japanese patients.

UNLABELLED: What's known on the subject? and What does the study add? Ras association domain family 1A (RASSF1A) is a tumour suppressor and regulates cell cycle, apoptosis and microtubule stability. This is the first study to identify associations between RASSF1A polymorphisms and clinicopathological parameters and survival in patients with clear cell renal cell carcinoma (CCRCC). RASSF1A genotyping may be useful for predicting the prognosis of the clinical course of CCRCC, and this finding might provide a better understanding of the mechanism underlying the development and progression of CCRCC. However, functional and prospective studies with a larger number of patients are needed to confirm the results. OBJECTIVE: To compare Ras association domain family 1A (RASSF1A) genotypes or haplotypes with clinicopathological characteristics and survival rates of patients with clear cell renal cell carcinoma (CCRCC). PATIENTS AND METHODS: The study cohort comprised 224 Japanese patients who underwent radical nephrectomy and had CCRCC confirmed by histopathological analysis. • Three common polymorphisms in the RASSF1A gene, 133Ala/Ser (G/T), -710C/T and -392C/T, were genotyped using TaqMan assays and haplotypes were analysed using appropriate software. RESULTS: Patients with CCRCC with RASSF1A -710TT genotype exhibited a significantly higher tumour stage and higher stage grouping than those with -710CC or -710CT (P = 0.005 and P = 0.032, respectively). • There was no significant association between 133Ala/Ser or -392C/T genotype and clinicopathological characteristics. • RASSF1A 133Ala-710T-392T haplotype and -710TT genotype were significantly associated with poorer recurrence-free survival rates (P = 0.038 and P = 0.007, respectively). CONCLUSIONS: This is the first study to identify associations between RASSF1A polymorphisms and clinicopathological parameters and survival in patients with CCRCC. • RASSF1A genotyping may be useful in predicting the prognosis of the clinical course of CCRCC, and this finding might provide a better understanding of the mechanism underlying the development and progression of CCRCC. • Functional and prospective studies with a larger number of patients are needed to confirm the results.

[Molecular targeted cancer therapy and genetic tests --chairman's introductory remarks].

Genetic tests for individualized cancer therapy are now expanding their repertoire as pharmacogenomics biomarkers, coupled with advances in molecular targeted therapy. These tests were considered special in the 1990s, because they were almost entirely limited to hematopoietic tumors and other rare tumors. Molecular targeted therapy has been applied to common solid tumors as well as hematopoietic tumors in the first decade of the 21st century, leading to a breakthrough in genetic tests. In this symposium, recent advances in genetic tests for molecular targeted therapy are being presented on breast cancer, lung cancer, colorectal cancer and hematopoietic tumors by 4 speakers.

[Genetic and epigenetic changes in colorectal cancer and genetic testing for personalized medicine].

Recent studies have uncovered molecular pathways of colorectal cancer, including the chromosomal instability pathway and microsatellite pathway. In addition, according to genetic and epigenetic profiles, colorectal cancer can be subclassified into 3 distinct groups, named the CpG island methylator phenotype (CIMP) 1, CIMP2, and CIMP negative. CIMP1 is characterized by MSI and BRAF mutations and rare KRAS and p53 mutations. CIMP2 is associated with KRAS mutations and rare MSI, BRAF, or p53 mutations. CIMP negative cases have a high rate of p53 mutations and lower rates of MSI or mutations of BRAF or KRAS. Regarding genetic testing for personalized medicine for colorectal cancer, uridine disphosphate glucuronosyl transferase 1(UGT1) and KRAS tests are available. Irinotecan is one of the most effective chemotherapeutic agents in the treatment of metastatic colorectal cancer. The prodrug irinotecan is biotransformed by carboxylesterase into its active metabolite SN-38, which is inactivated by UGT1 into the inactive compound SN-38G. Here we discuss UGT1A1 gene polymorphism as a predictor of toxicity. The epidermal growth factor (EGFR) plays an important role in the development and progression of colorectal cancer. KRAS serves as a mediator between extracellular ligand binding and intracellular transduction of signals from EGFR to the nucleus. Activating KRAS mutations has been identified as a predictor of resistance to EGFR-directed antibodies such as cetuximab. Here we discuss the current understanding of KRAS mutations and the therapeutic effect of cetuximab.

Autoimmune Hepatitis Following mRNA COVID-19 Vaccination in a Very Old Patient With Preexisting Sjögren's Syndrome: A Case Report.

A case of autoimmune hepatitis (AIH) following COVID-19 vaccination in a very old patient is presented. An 85-year-old woman who had preexisting Sjögren's syndrome (SS) but had never shown evidence of liver disease was admitted to our hospital due to jaundice and liver dysfunction. Further laboratory tests, imaging studies, and liver histology proved this to be a case of definite AIH. Eight weeks before the disease onset, she had received the second dose of mRNA COVID-19 vaccination. To our knowledge, this is the first case of AIH following COVID-19 vaccination in a patient with a history of SS.

IGFBP-4 activates the Wnt/beta-catenin signaling pathway and induces M-CAM expression in human renal cell carcinoma.

The Wnt/ß-catenin signaling pathway is inactivated by Wnt antagonists in most cancers and IGFBP-4 is an antagonist of the Wnt/ ß-catenin signaling pathway. However, the function of IGFBP-4 is not currently understood in renal cell carcinoma (RCC). We initially found that the expression of IGFBP-4 was significantly lower in primary RCC and higher in metastatic RCC compared to normal human kidney tissues. To assess the function of IGFBP4, we established IGFBP4 transfectants (primary renal cancer cell line) and performed functional analyses including Tcf reporter assays, cell viability, invasive capability, mortality, and in vivo tumor growth. Interestingly IGFBP-4 transfectants promoted cell growth (in vitro and in vivo), invasion, and motility in primary renal cancer. Tcf transcriptional activity was significantly increased in IGFBP-4 transfectants compared to mock cells and ß-catenin expression was increased. Also the ß-catenin downstream effector, MT1-MMP showed increased expression in IGFBP4 transfectants. Additionally IGFBP4 induced the expression of M-CAM, a marker of tumor progression. In order to assess the role of IGFBP4 in metastatic renal cancer, IGFBP-4 mRNA in a metastatic renal cancer cell lines (ACHN) was knocked-down using a siRNA technique. The cell growth and motility was decreased in si-IGFBP4 transfected ACHN cells compared to cells transfected with control siRNA. Tcf activity in ACHN cells was also decreased with si-IGFBP-4 transfection. This is a first report documenting that IGFBP-4 expression in RCC activates cell growth, metastasis, Wnt/beta-catenin signaling and may be involved in RCC metastasis.

Wnt antagonist DKK1 acts as a tumor suppressor gene that induces apoptosis and inhibits proliferation in human renal cell carcinoma.

The functional significance of Wnt antagonist DKK1 has not been investigated in renal cell carcinoma (RCC). Therefore, we hypothesized that DKK1 may be a tumor suppressor gene and is epigenetically silenced, thus decreased DKK1 may cause progression of RCC. To assess the function of DKK1, we established stable DKK1 transfected cells and monitored them regarding cell viability, colony formation, apoptosis, cell cycle, and invasive capability. RCC cell lines had decreased levels of DKK1, which were increased after treatment with 5-Aza-2'-deoxycytidine and trichostatin A. In chromatin immunoprecipitation assay, the level of dimethyl H3K9 and trimethyl H3K27 was decreased after 5-Aza-2'-deoxycytidine/trichostatin A treatment in RCC cell lines. Increased methylation was also associated with higher pathological stages in primary RCC tissues. T-cell factor/lymphoid enhancer factor activity and nuclear beta-catenin expression were not changed in DKK1 transfectants. Also the expression of cyclinD1 and c-Myc was not changed in DKK1 transfectants. These results suggest that DKK1 may not be involved in the beta-catenin dependent pathway. We also evaluated the expression of various related genes. Cleaved caspase3, p53, p21 and puma expression were significantly upregulated in the DKK1 transfected cells. The population of apoptotic cells was increased in stable DKK1 cells and tumor growth suppression was also observed in nude mice with DKK1 transfected cells. In conclusion, this is the first report to show that DKK1 expression is epigenetically silenced in kidney cancer and its reexpression induces apoptosis and cell cycle arrest in RCC.

Wnt antagonist DICKKOPF-3 (Dkk-3) induces apoptosis in human renal cell carcinoma.

The Wnt signaling pathway is activated in most cancers while Wnt antagonist genes are inactivated. However, the functional significance and mechanisms of inactivation of Wnt antagonist Dkk-3 gene in renal cell carcinoma (RCC) has not been reported. In this study, we examined potential epigenetic mechanisms regulating Dkk-3 expression in RCC cells and whether Dkk-3 expression affects cell growth and apoptosis. The expression of Dkk-3 is regulated by histone modification rather than CpG island DNA methylation in renal cancer cells. Renal cancer cell proliferation was significantly inhibited and apoptosis was promoted in Dkk-3 transfected renal cancer cells. Dkk-3 did not inhibit the Wnt/beta-catenin signaling pathway but induced apoptosis via the noncanonical JNK pathway in renal cancer cells. Expression of p21, MDM-2, and Puma genes were increased after transfecting RCC cell lines with a Dkk-3 expression plasmid. Overexpression of Dkk-3 induced G(0)/G(1) arrest together with an increase in p21 expression. Growth of stable Dkk-3 transfected cells in nude mice was decreased compared to controls. Our data show for the first time that mRNA expression of Dkk-3 is regulated by histone modification and that Dkk-3 inhibits renal cancer growth through modulation of cell cycle and apoptotic pathways.