Histone Deacetylases and Their Regulatory MicroRNAs in Hepatocarcinogenesis

A growing body of evidence suggests that epigenetic modifications are promising potential mechanisms in cancer research. Among the molecules that mediate epigenetic mechanisms, histone deacetylases (HDACs) are critical regulators of gene expression that promote formation of heterochromatin by deacetylating histone and non-histone proteins. Aberrant regulation of HDACs contributes to malignant transformation and progression in a wide variety of human cancers, including hepatocellular carcinoma (HCC), gastric cancer, lung cancer, and other cancers. Thus, the roles of HDACs have been extensively studied because of their potential as therapeutic targets. However, the underlying mechanism leading to deregulation of individual HDACs remains largely unknown. Some reports have suggested that functional microRNAs (miRNAs) modulate epigenetic effector molecules including HDACs. Here, we describe the oncogenic or tumor suppressive functions of HDAC families and their regulatory miRNAs governing HDAC expression in hepatocarcinogenesis.

miR-27 regulates mitochondrial networks by directly targeting the mitochondrial fission factor

Mitochondrial morphology is dynamically regulated by forming small, fragmented units or interconnected networks, and this is a pivotal process that is used to maintain mitochondrial homeostasis. Although dysregulation of mitochondrial dynamics is related to the pathogenesis of several human diseases, its molecular mechanism is not fully elucidated. In this study, we demonstrate the potential role of miR-27 in the regulation of mitochondrial dynamics. Mitochondrial fission factor (MFF) mRNA is a direct target of miR-27, whose ectopic expression decreases MFF expression through binding to its 3'-untranslated region. Expression of miR-27 results in the elongation of mitochondria as well as an increased mitochondrial membrane potential and mitochondrial ATP level. Our results suggest that miR-27 is a novel regulator affecting morphological mitochondrial changes by targeting MFF.

Gastrokine 1 Expression in the Human Gastric Mucosa Is Closely Associated with the Degree of Gastritis and DNA Methylation

PURPOSE: Gastrokine 1 plays an important role in gastric mucosal defense. Additionally, the Gastrokine 1-miR-185-DNMT1 axis has been shown to suppress gastric carcinogenesis through regulation of epigenetic alteration. Here, we investigated the effects of Gastrokine 1 on DNA methylation and gastritis. MATERIALS AND METHODS: Expression of Gastrokine 1, DNMT1, EZH2, and c-Myc proteins, and the presence of Helicobacter pylori CagA protein were determined in 55 non-neoplastic gastric mucosal tissue samples by western blot analysis. The CpG island methylation phenotype was also examined using six markers (p16, hMLH1, CDH1, MINT1, MINT2 and MINT31) by methylation-specific polymerase chain reaction. Histological gastritis was assessed according to the updated Sydney classification system. RESULTS: Reduced Gastrokine 1 expression was found in 20 of the 55 (36.4%) gastric mucosal tissue samples and was closely associated with miR-185 expression. The Gastrokine 1 expression level was inversely correlated with that of DNMT1, EZH2, and c-Myc, and closely associated with the degree of gastritis. The H. pylori CagA protein was detected in 26 of the 55 (47.3%) gastric mucosal tissues and was positively associated with the expression of DNMT1, EZH2, and c-Myc. In addition, 30 (54.5%) and 23 (41.9%) of the gastric mucosal tissues could be classified as CpG island methylation phenotype-low and CpG island methylation phenotype-high, respectively. Reduced expression of Gastrokine 1 and miR-185, and increased expression of DNMT1, EZH2, and c-Myc were detected in the CpG island methylation phenotype-high gastric mucosa. CONCLUSIONS: Gastrokine 1 has a crucial role in gastric inflammation and DNA methylation in gastric mucosa.

TNF-alpha and TNF-beta Polymorphisms are Associated with Susceptibility to Osteoarthritis in a Korean Population

BACKGROUND: The tumor necrosis factor (TNF) is believed to play an important role in the pathophysiology of osteoarthritis (OA). Evidence shows that genetic polymorphisms make substantial contributions to the etiology of OA. METHODS: We investigated the genotypes TNF-alpha and TNF-beta in 301 OA patients and 291 healthy subjects as controls. We employed a polymerase chain reaction-restriction fragment length polymorphism and a polymerase chain reaction-single strand conformation polymorphism assay to identify the genotypes TNFA -G308A and TNFB +G252A, respectively. RESULTS: For TNFA -G308A, the percentages of genotypes GG, AG, and AA were 26.3% (79/301), 62.5% (188/301), and 11.3% (34/301) in OA patients and 88.7% (258/291), 11.3% (33/291), and 0% (0/291) in controls. For TNFB +G252A, the percentages of genotypes GG, AG, and AA were 15.3% (46/301), 41.9% (126/301), and 42.9% (129/301) in OA patients and 12% (35/291), 52.6% (153/291), and 35.4% (103/291) in controls. There were significant differences in genotypes and alleles of TNFA -308 between OA patients and controls (p<0.0001) and in alleles of TNFB +252 (p=0.0325). The risk of OA was significantly higher for carriers of the TNFA -308A allele and the TNFB +252 AA homozygote (p=0.0224). CONCLUSIONS: The results suggest close relationships between TNFA -G308A and TNFB +G252A polymorphisms and individual susceptibility to OA in the Korean population.

Copy Number Alterations of BCAS1 in Squamous Cell Carcinomas

BACKGROUND: Breast carcinoma amplified sequence 1 (BCAS1), located in 20q13, is amplified and overexpressed in breast cancers. Even though BCAS1 is expected to be an oncogene candidate, its contribution to tumorigenesis and copy number status in other malignancies is not reported. To elucidate the role of BCAS1 in squamous cell carcinomas, we investigated the copy number status and expression level of BCAS1 in several squamous cell carcinoma cell lines, normal keratinocytes and primary tumors. METHODS: We quantitated BCAS1 gene by real-time polymerase chain reaction (PCR). Expression level of BCAS1 was measured by real-time reverse transcription-PCR and immunoblot. RESULTS: Seven (88%) of 8 squamous cell carcinoma cell lines showed copy number gain of BCAS1 with various degrees. BCAS1 gene in primary tumors (73%) also showed copy number gain. However, expression level did not show a linear correlation with copy number changes. CONCLUSIONS: We identified copy number gain of BCAS1 in squamous cell carcinomas. Due to lack of linear correlation between copy numbers of BCAS1 and its expression level, we could not confirm that the overexpression of BCAS1 is a common finding in squamous cell carcinoma cell lines. However, this study shows that the copy number gain of BCAS1 is a common finding in squamous cell carcinomas.

Growth Differentiation Factor 5 (GDF5) Core Promoter Polymorphism Is Not Associated with Susceptibility to Osteoarthritis of the Knee in the Korean Population

BACKGROUND: Osteoarthritis (OA) is a common disease characterized by degenerating joint cartilage in the knee, hip, and hand. A functional single nucleotide polymorphism (SNP) +104T/C; rs143383 in the 5' untranslated region of the growth differentiation factor 5 (GDF5) gene was recently associated with susceptibility to OA in the Japanese and Chinese populations. METHODS: To investigate whether this association is present in the Korean population, the frequency of the polymorphism was investigated in 276 patients with knee OA and 298 healthy subjects as controls. Polymorphism analysis was performed by amplifying the core promoter region of the GDF5 gene and digesting it with the BsiEI restriction enzyme. RESULTS: The frequency of the TT, CT, and CC genotypes was 54.3% (150/276), 41.7% (115/276), and 4.0% (11/276), respectively, in patients with OA, and 53.4% (159/298), 37.9% (113/298), and 8.7% (26/298), respectively, in healthy controls. No significant differences in genotypic or allelic frequencies of the +104T/C SNP of the GDF5 gene were observed between patients with OA and controls. Also, no significant differences in allelic and genotypic frequencies were found when the individuals were stratified by age and gender. CONCLUSIONS: The results suggest that the +104T/C; rs143383 GDF5 core promoter polymorphism is not a risk factor for OA in the Korean population.

Genetic and Expression Analysis of the SIRT1 Gene in Gastric Cancers

PURPOSE: Silent mating-type information regulation 2 homologue 1 (SIRT1) is a nicotinamide adenine dinucleotide-dependent deacetylase. SIRT1 plays an important role in the regulation of cell death/survival and stress response in mammals. The aim of this study was to investigate whether the SIRT1 gene is involved in the development or progression of gastric cancers. MATERIALS AND METHODS: SIRT1 and p53 genes in 86 gastric cancers were examined for genetic alterations by PCR-single strand conformation polymorphism sequencing, as well as SIRT1 protein expression in 170 gastric cancers by immunohistochemistry. RESULTS: In the genetic analysis, we found SIRT1 and p53 mutations in two and 12 cases, respectively. Two missense mutations, c.599 C>T (T200I) and c.1258 G>A (E420K), were detected in the SIRT1 gene coding region. The SIRT1 and p53 mutation were found in mutually exclusive gastric cancers. The immunohistochemistry revealed that SIRT1 overexpression was found in 95 (55.9%) of 170 gastric cancers. Altered SIRT1 expression was not statistically associated with clinicopathological parameters, including tumor differentiation, location, lymph node metastasis, or p53 expression. Two cases with an SIRT1 mutation showed increased SIRT1 expression. CONCLUSIONS: These results suggest that genetic alterations and overexpression of the SIRT1 gene may contribute to gastric cancer development.

Transcriptional profiling and Wnt signaling activation in proliferation of human hepatic stellate cells induced by PDGF-BB / 대한간학회지

BACKGROUND/AIMS: This study aimed to better understand gene expression profiles of human hepatic stellate cell (HSC) activation and the relationship with the Wnt signaling pathway. METHODS: The global transcript levels in platelet derived growth factor-BB (PDGF-BB)-stimulated hTERT HSCs were analyzed using oligonucleotide microarrays. Oligonucleotide microarrays with 19K human oligo chips were performed to obtain gene expression profiles associated with proliferation in human hTERT HSCs. The microarray data was verified by real time quantitative PCR and expression of the components of Wnt signaling was analyzed by Western blot. RESULTS: Microarray data showed 243 up-regulated and 265 down-regulated genes in PDGF-BB-treated HSCs. The changes in expression of glypican3 and BH3 interacting domain death agonist (BID) mRNA in real time quantitative PCR, especially among the highly up- or down-regulated genes, were statistically consistent with the microarray data. The Wnt signaling pathway components, frizzled10 (FZD10) and calcium/calmodulin-dependent protein kinase II alpha (CAMK2A), showed increased expression in the short time course microarray and the up-regulation of FZD10 also occurred at the protein level. Our data showed various gene expression profiles during activation of human HSC. CONCLUSIONS: The up-regulated expression of FZD10 and CAMK2A suggests that the Wnt/Ca2+ signaling pathway is active in hTERT HSCs and may participate in HSC activation and proliferation

Notochordal Cells Induce Chemotaxis of Cartilage-Endplate Chondrocytes in In Vitro Motility Assays / 대한척추외과학회지

STUDY DESIGN: In vitro motility assays were carried out using rat intervertebral discs (IVDs). OBJECTIVES: To demonstrate the motile properties of the cartilage endplate (CE) chondrocytes and the effect of notochordal cells on this property. LITERATURE REVIEW: Although previous in vivo studies have provided evidence for the migration of CE chondrocyte from hyaline CEs into the notochordal nucleus pulposus (NP), it is unclear if CE chondrocytes of the IVD actually have motile properties. In addition, the effect of notochordal cells on these properties has not been reported. MATERIALS AND METHODS: Notochordal cells and CE chondrocytes were harvested from three-month-old male Wistar rats and cultured separately. The motility was assayed in quadruplicate using a 48-well microchemotaxis chamber and a gelatin-coated 8-micrometer polycarbonate membrane filter. The control medium (serum-free culture medium), notochordal cells (4x, 2x, 1x and 0.5x10(6)) and concentrated conditioned medium (10-, 50-fold) where notochordal cells were cultured were loaded into the wells of the lower chamber, and CE chondrocytes were added to the wells of the upper chamber. At the end of the assays, the CE chondrocytes that migrated to the bottom side of the membrane filter were stained, counted, and compared. RESULTS: Compared with the control medium, the notochordal cells (N = 4x, 2x, 1x and 0.5x10(6)) and concentrated conditioned medium (10- and 50-fold) significantly increased the chemotactic motility of the CE chondrocytes in a number- and concentration-dependent manner (p<0.05). CONCLUSION: The CE chondrocytes of the intervertebral disc are motile, and soluble factors produced by notochordal cells induce the chemotaxis of CE chondrocytes.

Expression Pattern of EphB2 in Gastric Cancer

PURPOSE: The EphB2 receptor, a member of the receptor tyrosine kinase family, is a target gene of the Wnt signaling pathway and may achieve a tumor suppressor function through regulation of cell growth and migration. Our aim was to determine whether an altered expression of EphB2 might be associated with gastric cancer development and, if so, to determine to which pathologic parameter it is linked. MATERIALS AND METHODS: For the construction of the gastric cancer tissue microarray, 83 paraffin-embedded tissues containing gastric cancer areas were cored 3 times and transferred to the recipient master block. The expression patterns of EphB2 were examined on tissue microarray slides by using immunohistochemistry and were compared using pathologic parameters, including histological type, depth of invasion, lymph node metastatsis, and peritoneal dissemination. RESULTS: The EphB2 protein was expressed in the normal gastric mucosal epithelium, especially in the bottom of the mucosa. We found loss of EphB2 expression in 30 (36.1%) of the 83 gastric cancer tissues. Statistically, loss of EphB2 expression was more common in gastric cancer with lymph-node metastasis. There was no significant correlation between EphB2 expression and depth of invasion, histologic type, or peritoneal dissemination. CONCLUSION: Our findings suggest that loss of EphB2 expression may represent a critical step in gastric carcinogenesis.

Genetic and expression analysis of the KCNRG gene in hepatocellular carcinomas

The potassium channels are ubiquitous multisubunit membrane proteins, and potassium-dependent alterations in the membrane potential play an important role in the proliferation of many types of cells. This study analyzed the mutation, allelic loss and expression patterns of the KCNRG gene in 77 HCCs in order to determine if the KCNRG gene, which encodes the potassium channel regulating protein, is involved in the tumorigenesis of hepatocellular carcinoma (HCC). One KCNRG missense mutation, CGT->CAT (Arg->His) was found at codon 92 within the T1 domain. Hep3B hepatoma cells were transfected with the wild- or mutant-KCNRG to determine the effect of this mutation in KCNRG. Interestingly, the suppressive cell growth activity of the mutant-type KCNRG was significantly lower than that of the wild-type KCNRG. In addition, allelic loss was detected in 17 out of 64 (26.5%) informative HCC cases, and all were hepatitis B virus (HBV)-positive. Moreover, the allelic loss was closely related to an intrahepatic metastasis (P=0.0247), higher grade (P=0.0078) and clinical stage (P=0.0071). Expression analysis revealed 22 tumor tissues to have a loss of expression of the KCNRG transcript. These results suggest that genetic alterations and the expression of KCNRG might play an important role in the development and/or progression of a subset of HCCs.

Mutational Analysis of Pro-apoptotic BAD Gene in Nonsmall Cell Lung Cancer

PURPOSE : Evidence exists that deregulation of apoptosis is involved in the mechanisms of cancer development, and the somatic mutations of apoptosisrelated genes have been reported in human cancers. Bcl- XL/Bcl-2-associated death promoter (BAD), a pro-apoptotic member of Bcl-2 family, plays an important role in the intrinsic apoptosis pathway. MATERIALS AND METHODS : To explore the possibility that the genetic alterations of BAD might be involved in the development of human cancers, we analyzed the entire coding region and all splice sites of human BAD gene in 100 human non-small cell lung cancers (NSCLC) by polymerase chain reaction (PCR)-based single-strand conformation polymorphism (SSCP). RESULTS : The PCR-SSCP analysis detected no mutation in the entire coding regions and all splice sites of human BAD gene in the 100 NSCLCs. CONCLUSION : The data presented here suggested that BAD gene mutation may not contribute to the pathogenesis of human NSCLCs

Mutational Analysis of Proapoptotic bcl-2 Family genes in Colon Carcinomas

BACKGROUND: Several lines of evidence have indicated that the deregulation of apoptosis is involved in the mechanisms of cancer development, and somatic mutations of the apoptosisrelated genes have been reported in human cancers. Members of the bcl-2 family proteins regulate the intrinsic apoptosis pathway mainly in the mitochondria. The aim of this study was to explore whether the somatic mutation of the proapoptotic bcl-2 family genes, one of the mechanisms that prolong the survival of cancer cells, occurred in colorectal carcinomas. METHODS: In the current study, to detect the somatic mutations in the DNA sequences encoding the bcl-2 homology 3 (BH3) domain of the human bak, bid, bik, bim, PUMA, bcl-rambo, bcl-G, and bmf genes in 98 colon adenocarcinomas, we used polymerase chain reaction (PCR), single strand conformation polymorphism (SSCP), and DNA sequencing. RESULTS: The SSCP analysis detected no evidence of somatic mutations of the genes in the coding regions of the BH3 domain in the cancers. CONCLUSIONS: The data presented here indicate that the proapoptotic bcl-2 family genes, bak, bid, bik, bim, PUMA, bcl-rambo, bcl-G and bmf may not be somatically mutated in human colorectal carcinomas, and suggest that the colorectal cancers may not utilize mutational events of these proapoptotic bcl-2 family genes in the mechanisms for evading apoptosis.

Hypermethylation of the RUNX3 gene in hepatocellular carcinoma

Methylation events play a critical role in various cellular processes including regulation of gene transcription and proliferation. Recently, RUNX3 gene, one of TGF-beta-Smads signaling transduction pathway genes, showed strong tumor-suppressor activity by regulation of epithelial proliferation and apoptosis. To elucidate the potential etiological role of the RUNX3 gene in the development of hepatocellular carcinoma (HCC), we have analyzed the methylation status of 5' CpG island of the RUNX3 gene in a series of 73 HCC tissues and 11 liver cell lines. Expectedly, promoter methylation of RUNX3 gene was found in 2 (2.7%) of 73 corresponding normal liver, whereas 30 (41.1%) of 73 HCCs and 4 (40%) of 10 liver cancer cell lines showed hypermethylation of the gene, respectively. There was no significant difference between promoter hypermethylaion and clinicopathologic parameters of primary HCC samples, including histologic grade, microvascular invasion, and clinical stage. Interestingly, demethylating agent 5-aza-2-deoxycytidine induced reactivation and more potent expression of RUNX3 gene in HCC cell lines. Our findings indicate that promoter hypermethylation of RUNX3 gene may occur as an early event in the development of HCC and that methylation may be a major mechanism for inactivation of RUNX3 gene in HCC.

Mutation of the Chk1 Gene in Gastric Cancers with Microsatellite Instability

PURPOSE: The protein kinase Chk1 is required for cell cycle arrest in response to DNA damage and is shown to play an important role in the G2/M checkpoint. The aim of this study was to investigate the relationship between microsatellite instability and frameshift mutation of the Chk1 gene in gastric cancers. MATERIALS AND METHODS: The microsatellite instability was analyzed in 95 primary gastric carcinomas by using microdissection and 6 microsatellite markers. We also performed single strand conformational polymorphism and sequencing to detect frameshift mutation of the Chk1 gene. RESULTS: We found positive microsatellite instability in 19 (20%) of the 95 gastric cancers, 13 high- and 6 low-frequency microsatellite instability cases. The frameshift mutation of Chk1, which resulted in a truncated Chk1 protein, was detected in two high-frequency microsatellite instability cases. CONCLUSION: These data suggest that the microsatellite instability may contribute to the development of gastric carcinomas through inactivation of Chk1.

Mutational Analysis of Caspase-7 and 8 Genes in Non-small Cell Lung Cancer

PURPOSE : Several lines of evidence have indicated that deregulation of apoptosis is involved in the mechanism of cancer development. Caspase-8 activation plays a central role in the initiation phase of apoptosis, while caspase-7 is one of the main execution phase caspases of apoptosis. The aim of this study was to explore the possibility that genetic alterations of the caspase-8 and caspase-7 genes are involved in the development of human non-small cell lung cancer (NSCLC). MATERIALS AND METHODS : We have analyzed the entire coding region of both the caspase-7 and caspase-8 genes to detect the somatic mutations in 100 NSCLCs by using polymerase chain reaction (PCR)- single strand conformation polymorphism (SSCP). RESULTS : The PCR-SSCP analysis detected no mutations in the entire coding regions of both the caspase-7 and caspase-8 genes in the NSCLCs. CONCLUSION : The data presented here suggests that both the caspase-7 and caspase-8 genes may not be somatically mutated in human NSCLCs

Expression Pattern of KLF6 in Korean Gastric Cancers

PURPOSE: KLF6, a member of the KLF family, is a ubiquitous zinc finger tumor suppressor protein that is mutated in several human cancers. Our aim was to determine whether the expression pattern of KLF6 might be associated with gastric cancer development and, if so, to determine to which pathologic parameter it is linked. MATERIALS AND METHODS: For the construction of the gastric cancer tissue microarray, 85 paraffin-embedded tissues containing gastric cancer areas were cored 3 times and transferred to the recipient master block. The expression pattern of KLF6 was examined on tissue microarray slides by using immunohistochemistry and was compared with pathologic parameters, including histologic type, depth of invasion, lymph node metastasis, and peritoneal dissemination. RESULTS: The KLF6 protein was expressed on superficial and foveolar epithelial cells in the gastric mucosa. We found loss of KLF6 expression in 28 (32.9%) of the 85 gastric cancer tissues. There was a significant correlation between loss of KLF6 expression and lymph-node metastasis. However, other pathologic parameters, such as histologic type, depth of invasion, and peritoneal dissemination, were not statistically associated with loss of KLF6 expression. CONCLUSION: Our findings suggest that loss of KLF6 expression may contribute to abnormal regulation of gastrointestinal epithelial cell growth and differentiation and to the development and/or progression of Korean gastric cancer.

Expression Pattern of KLF4 in Korean Gastric Cancers

PURPOSE: KLF4, a member of the KLF family, is a zinc finger tumor suppressor protein that is critical for gastric epithelial homeostasis. Our aim was to determine whether the altered expression of KLF4 might be associated with gastric cancer development and, if so, to determine to which pathologic parameter it is linked. MATERIALS AND METHODS: For the construction of the gastric cancer tissue microarray, 84 paraffin-embedded tissues containing gastric cancer areas were cored 3 times and transferred to the recipient master block. The expression pattern of KLF4 was examined on tissue microarray slides by using immunohistochemistry and was compared with pathologic parameters, including histologic type, depth of invasion, lymph node metastasis, and peritoneal dissemination. RESULTS: The KLF4 protein was expressed in cytoplasm and nucleus of superficial and foveolar epithelial cells in the normal gastric mucosa. We found markedly reduced or loss of KLF4 expression in 43 (51.2%) of the 84 gastric cancer tissues. There was no significant correlation between KLF4 expression and pathologic parameters, including histologic type, depth of invasion, lymph node metastasis and peritoneal dissemination. CONCLUSION: Our findings suggest that altered expression of KLF4 may contribute to abnormal regulation of gastrointestinal epithelial cell growth and differentiation and to the development of Korean gastric cancer, as an early event.

Mutational Analysis of the Epidermal Growth Factor Receptor Gene in Gastrointestinal Stromal Tumors

PUPOSE: Most gastrointestinal stromal tumors (GISTs) have gain-of-function mutations of the KIT or the platelet-derived growth factor receptor alpha (PDGFRA) genes, but approximately 10% of the GISTs are wild types for both the KIT and the PDGFRA genes. The purpose of this study was to investigate the possibility that epidermal growth factor receptor (EGFR) gene mutation might be responsible for the pathogenesis of GIST. MATERIALS AND METHODS: We analyzed the EGFR gene in 60 GISTs for the detection of somatic mutations by using the polymerase chain reaction (PCR), the single strand conformation polymorphism (SSCP), and DNA sequencing in exon 18, 19, and 21 encoding the kinase domain. RESULTS: The SSCP analysis revealed no evidence of EGFR mutations in exon 18, 19, and 21 in GISTs. CONCLUSION: The data indicate that the EGFR gene may not be mutated in human GIST and suggest that therapies targeting the mutated EGFR gene products might not be useful in the treatment of GISTs.

Biological Activities of HA-coated Zirconia / 대한치주과학회지

Hydroxyapatite(HA) has been extensively used as bone graft materials and tooth implant surface coating materials because of its biocompatibility and osteoconductive properties. However, as HA is intrinsically poor in mechanical properties, zirconia(ZrO2) was incorporated with HA as reinforcing phases for improvement of mechanical properties. The purpose of this study was to investigate the biological activities of HA-coated zirconia through the cell proliferation test, measurements of alkaline phosphatase activity, and histologic examination. Four kinds of tested blocks were prepared according to the pore size (300-500micrometer/500-700micrometer) and the porosity (70%/90%). Cell proliferation and alkaline phosphatase activity was measured at 1, 7, 14 days. The number of cells proliferate after 7, 14 days were significantly increased in all groups when compared with that of the first day, but there was no significant difference between the 4 groups at each time period. At the 7 day, alkaline phosphatase activities of cells cultured in 4 groups were higher than that of the first day, but there was no significant difference between the 4 groups at each time period. The human gingival fibroblast and MG 63 cell was used to evaluate the cell cytotoxicity using MTT test. The materials tested in the current study turned out to be non-cytotoxic. In histologic examination(SEM), at 1 day there were many cells attached on the surfaces of all kinds of tested blocks. The number of cells were increased over time. At the 14 day, there were more cells proliferated than 1 day and some of the pores of blocks were partially filled with the proliferated cells. The in vitro response of osteoblast-like cells to the HA-coated zirconia showed comparable effect on transformation comparable to hydroxyapatite.