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Biomedical subjects

Irene O L Ng

Publications and source records attributed to Irene O L Ng.

16 recordsLinked to original sources
PubMed2006

Osteomyelitis with proliferative periostitis: an unusual case.

Chronic osteomyelitis with subperiosteal new bone formation results from periosteal reaction to chronic inflammatory/infectious stimulation. In the maxillofacial region, it has traditionally been termed Garrè's osteomyelitis with proliferative periostitis and more recently periostitis ossificans. The term Garrè's osteomyelitis has been regarded as a misnomer by many authors in the recent literature. The term chronic osteomyelitis with proliferative periostitis, although cumbersome, is considered to be the most accurate description of the pathology. It usually affects the mandible of young patients secondary to dental infection. Management involves removal of the source of infection and antibiotic treatment. We present an unusual case of chronic osteomyelitis with proliferative periostitis affecting the mandible of a 12-year-old patient. The source of infection was related to the developing lower left third molar, which had apparently no communication with the oral cavity.

Child↗
PubMed2006

Prickle-1 negatively regulates Wnt/beta-catenin pathway by promoting Dishevelled ubiquitination/degradation in liver cancer.

BACKGROUND & AIMS: Aberrant activation of Wnt signaling due to accumulation of beta-catenin has been linked to tumorigenesis. Mutations of beta-catenin, APC, and axins are important but not frequent enough to be accountable for the accumulation of beta-catenin in human hepatocellular carcinoma (HCC). In this study, we characterized the roles of Prickle-1, a Dishevelled (Dvl)-associated protein, in regulation of Wnt/beta-catenin activity in HCC. METHODS: The expression levels of human Prickle-1 and Dvl3 were examined in HCC cell lines and human HCC samples. The interaction and effects of Prickle-1 on Dvl3, the Wnt/beta-catenin pathway, and cell growth were assessed in HCC cell lines. RESULTS: We showed that Prickle-1 bound with Dvl3 and facilitated Dvl3 ubiquitination/degradation, and this was through its destruction box (D-box) motifs. Enforced expression of Prickle-1 significantly reduced the Wnt/beta-catenin activity and tumorigenic properties of HCC cells. Clinicopathologic analysis showed that underexpression of Prickle-1 was significantly associated with overexpression of Dvl3, beta-catenin accumulation (P = .023), and larger tumor size (P = .030). CONCLUSIONS: Our results have elucidated a novel mechanistic relationship between Prickle-1 and Dvl3 in the Wnt/beta-catenin pathway. The facilitation of Prickle-1 on Dvl3 degradation and the suppression of beta-catenin activity and cell growth suggest that Prickle-1 is a negative regulator of the Wnt/beta-catenin signaling pathway and is a putative tumor suppressor in human HCCs.

Adaptor Proteins, Signal Transducing↗
PubMed2006

Proteomic profiling of hepatocellular carcinoma in Chinese cohort reveals heat-shock proteins (Hsp27, Hsp70, GRP78) up-regulation and their associated prognostic values.

To facilitate the identification of candidate molecular biomarkers that are linked to the pathogenesis of hepatocellular carcinoma (HCC), we investigated protein-expression profiles of 146 tissue specimens including 67 pairs of tumors and adjacent non-tumors resected from HCC patients as well as 12 normal livers by 2-DE. Among the 1800 spots displayed in the liver proteome, a total of 90 protein species were found to be significantly different between the three groups (P < 0.05). Three of the top candidate markers up-regulated in HCC, with high receiver operating characteristic (ROC) curves, were identified by MS/MS analysis and belonged to the chaperone members: heat-shock protein (Hsp)27, Hsp70 and glucose-regulated protein (GRP)78. Over-expression of these chaperone proteins in HCC tissues was confirmed by Western blotting and immunohistochemistry. In correlation with clinico-pathological parameters, expression of Hsp27 was linked to alpha-fetoprotein level (P = 0.007) whereas up-regulation of GRP78 was associated with tumor venous infiltration (P = 0.035). No significant association of Hsp70 with any pathologic features was observed. The present HCC proteome analysis revealed that in response to the stressful cancerous microenvironment, tumor cells strived to increase the expression of chaperone proteins for cyto-protective function and to enhance tumor growth and metastasis.

Adolescent↗
PubMed2004

The relative contribution of CHK1 and CHK2 to Adriamycin-induced checkpoint.

Topoisomerase II poisons like Adriamycin (ADR, doxorubicin) are clinically important chemotherapeutic agents. Adriamycin-induced DNA damage checkpoint activates ATM and ATR, which could in turn inhibit the cell cycle engine through either CHK1 or CHK2. In this study, we characterized whether CHK1 or CHK2 is required for Adriamycin-induced checkpoint. We found that both CHK1 and CHK2 were phosphorylated after Adriamycin treatment. Several lines of evidence from dominant-negative mutants, short hairpin RNA (shRNA), and knockout cells indicated that CHK1, but not CHK2, is critical for Adriamycin-induced cell cycle arrest. Disruption of CHK1 function bypassed the checkpoint, as manifested by the increase in CDC25A, activation of CDC2, increase in histone H3 phosphorylation, and reduction in cell survival after Adriamycin treatment. In contrast, CHK2 is dispensable for Adriamycin-induced responses. Finally, we found that CHK1 was upregulated in primary hepatocellular carcinoma (HCC), albeit as an inactive form. The presence of a stockpile of dormant CHK1 in cancer cells may have important implications for treatments like topoisomerase II poisons. Collectively, the available data underscore the pivotal role of CHK1 in checkpoint responses to a variety of stresses.

Base Sequence↗
PubMed2004

PIN1 overexpression and beta-catenin gene mutations are distinct oncogenic events in human hepatocellular carcinoma.

The peptidyl-proplyl-isomerase, PIN1, upregulates beta-catenin by inhibiting its interaction with APC. beta-catenin accumulation occurs in about 70% of hepatocellular carcinoma (HCC), of which only 20% are due to beta-catenin mutations. The role of PIN1 in beta-catenin upregulation in HCC was investigated. PIN1 was shown to be overexpressed in more than 50% of HCC. All cases with PIN1 overexpression also showed beta-catenin accumulation, with 68% of cases showing concomitant beta-catenin and cyclin D1 accumulation. PIN1 was shown to contribute to beta-catenin and cyclin D1 overexpression directly by in vitro cell-line transfection experiments. Finally, we showed that PIN1 overexpression and beta-catenin gene mutations appeared to be mutually exclusive events, leading to beta-catenin accumulation in HCC. These results showed that PIN1 overexpression leading to beta-catenin accumulation might be a critical event in hepatocarcinogenesis, and that PIN1 is a potential target for therapeutic intervention in HCC.

Carcinoma, Hepatocellular↗
PubMed2004

Hepatitic graft-versus-host disease after hematopoietic stem cell transplantation: clinicopathologic features and prognostic implication.

BACKGROUND: Graft-versus-host disease (GVHD) of the liver after allogeneic hematopoietic stem cell transplantation classically presents with increased bilirubin and alkaline phosphatase (ALP) levels. A hepatitic variant was recently recognized, with more than a 10-fold increase in aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels. This study defines the clinicopathologic features and prognostic implications of hepatitic GVHD compared with classic liver GVHD. METHOD: A total of 38 cases of hepatitic GVHD, 68 cases of classic liver GVHD, and 13 cases of hepatitis B virus (HBV)-related hepatitis after hematopoietic stem cell transplantation were analyzed. RESULTS: Hepatitic GVHD cases showed significantly higher ALT, AST, and ALP levels compared with classic liver GVHD cases (at onset, mean ALT: 154 vs. 58 U/L, P <0.001; AST: 167 vs. 77 U/L, P <0.001; at peak, ALT: 435 vs. 112 U/L, P <0.001; AST: 587 vs. 150 U/L, P <0.001; ALP: 416 vs. 238 U/L, P =0.001), persisted longer (74 vs. 32 days, P =0.006), and showed more lobular pathologic changes in biopsy (lobular changes: 16/26 vs. 4/19, P =0.007; hepatocyte necrosis: 16/26 vs. 6/19, P =0.008; acidophil bodies: 15/26 vs. 4/19, P =0.014) but less cholestasis (4/26 vs. 8/19, P =0.045). However, cumulative doses of immunosuppressants prescribed, response, and outcome were similar. Compared with hepatitic GVHD, HBV-related hepatitis occurred later (95 vs. 184 days, P =0.049), but clinical and biochemical profiles were similar, requiring liver biopsies for their distinction. CONCLUSIONS: Hepatitic and classic liver GVHD differed biochemically and pathologically, but these differences showed no obvious impact on outcome. The distinction of hepatitic GVHD from other hepatitis is mandatory.

Adolescent↗
PubMed2003

Role of liver biopsy in the management of liver dysfunction after hematopoietic stem-cell transplantation in a hepatitis B virus-prevalent patient population.

BACKGROUND: Derangement of liver function tests (LFT) is common after hematopoietic stem-cell transplantation (HSCT). The role of liver biopsy in such cases has not been defined in hepatitis B virus (HBV)-prevalent patients. The impact of liver biopsy in the management of LFT derangement after HSCT in an HBV-prevalent population was examined. METHODS: Seventy-five liver biopsies, performed for 323 patients with LFT derangement post-HSCT (263 allogeneic, 60 autologous), were analyzed. The HBV carrier rate was 13.6%. RESULTS: Significantly more LFT derangements and therefore liver biopsies occurred in allogeneic versus autologous HSCT. Before biopsy, graft-versus-host disease (GVHD) and HBV reactivation were clinically diagnosed in 70.6% and 25.3% of cases, respectively. A definite histopathologic diagnosis was obtained after biopsy in 53 cases, with GVHD, HBV hepatitis, and concomitant GVHD-HBV hepatitis found in 33%, 21%, and 8% of cases, respectively. The clinical and histopathologic diagnoses were concordant in 43 cases and discordant in 9 cases. Clinical management was altered in six of nine discordant cases, five of which were caused by HBV or hepatitis C virus (HCV) reactivation. Twenty-two biopsy specimens showed nondiagnostic histopathologic features. Twenty of these cases were successfully managed on the basis of clinical diagnoses. The clinical-biochemical features of patients clinically diagnosed to have GVHD did not differ significantly whether or not they were HBV-HCV carriers. However, liver biopsies in HBV-HCV carriers resulted in significantly more treatment alterations as compared with noncarriers. CONCLUSIONS: Clinical diagnoses of LFT derangements post-HSCT might be adequate for initiation of treatment, but liver biopsies in HBV-HCV carriers were needed, as this might impact on management.

Adolescent↗
PubMed2003

Allelic alterations in nontumorous liver tissues and corresponding hepatocellular carcinomas from chinese patients.

Allelic imbalance may play an important in tumor progression in hepatocarcinogenesis, but the genetic background of the corresponding nontumorous liver in hepatocellular carcinoma (HCC) is not well defined. We studied the incidence of loss of heterozygosity (LOH) and microsatellite instability (MSI) by microsatellite analysis in both nontumorous livers and the corresponding tumors, by comparing them with the normal DNA from Chinese patients with resected primary HCCs. We also evaluated the pathologic significance of the alterations. We used 18 highly polymorphic microsatellite markers on chromosomes 1, 3, 4, 7, 8, 9, 13, 16, 17, and 18. Our results showed that 70.6% (24 of 34) of the HCCs exhibited LOH at 1 or more loci, and that the overall fractional allelic loss (FAL) was 0.169. MSI was observed in only 1 tumor. In contrast, the nontumorous livers of the HCCs showed a very low incidence of LOH, with only a single LOH detected in 1 of 34 (2.9%) of the nontumorous livers, with an overall FAL index of 0.005. Tumors with LOH at 1 or more loci had significantly more frequent venous invasion (P = 0.019). Allelic loss at locus D9S199 (9p23) was seen more frequently in larger tumors (P = 0.031), and, less significantly, allelic loss at locus D16S516 (16q24.1) was seen more frequently in larger tumors (P = 0.059). LOH was common in predominantly hepatitis B virus-associated HCCs from Chinese patients. However, LOH or MSI in the corresponding cirrhotic or noncirrhotic livers was uncommon.

Adult↗
PubMed2002

Identify metastasis-associated genes in hepatocellular carcinoma through clonality delineation for multinodular tumor.

Disease recurrence and metastasis are frequently observed in many successfullytreated localized cancers, including hepatocellular carcinoma in which intrahepatic and extrahepatic recurrence (metastasis) are frequently observed after curative resection. The present study aimed at identifying metastasis-associated genes through delineation of the clonality for multinodular liver cancer. The clonal relationship of 22 tumor foci from six patients was investigated by the genome-wide expression profile via cDNA microarray consisting of 23,000 genes. Tumor molecular properties including p53 protein overexpression and gene mutation, hepatitis B virus integration pattern, and genetic alteration examined by comparative genomic hybridization were compared. Results indicated that gene expression patterns could serve as the molecular fingerprint for clonality identification. Together with the molecular data from p53, hepatitis B virus integration and comparative genomic hybridization profiles, tumor nodules from five patients were confirmed with clonal relationship, and the expression profiles of the primary nodules were compared with their corresponding intrahepatic metastatic nodules. A total of 90 clones were found to be correlated with intrahepatic metastasis by Student's t test (P < 0.05). With reference to the primary tumor, 63 clones (39 known genes and 24 express sequence tags) were down-regulated whereas 27 clones (14 known genes and 13 express sequence tags) were up-regulated in the metastatic nodules. These metastasis-associated genes may provide clues to reveal patients with increased risk of developing metastasis, and to identify novel therapeutic targets for the treatment of metastasis.

Adolescent↗
PubMed2002

Gene expression profiling by cDNA array in human hepatoma cell line in response to cisplatin treatment.

Gene expression profiling with cDNA array allows simultaneous analysis of the gene expression pattern of a large number of genes and may enhance the investigation of the molecular mechanisms involved in the treatment of hepatocellular carcinoma with cisplatin. We used cDNA array technology to assess the gene expression profiles related to cell cycle regulation and apoptosis in human hepatoma Hep3B cells in response to cisplatin treatment. In Hep3B cells, apoptosis induced by cisplatin was p53-independent, and was associated with up-regulation of cell cycle regulators, pro-apoptotic genes, growth receptors, and genes involved in signal transduction. These included p33ING1, c-Abl, Bax, insulin-like growth factor binding protein 3, Siva, cyclin D1, RhoA, and Raf-1. Down-regulation of cell cycle regulator CDC2 was observed. Semi-quantitative reverse transcription-polymerase chain reaction and/or Western blot analysis performed on seven of these genes confirmed their upregulation of gene expression. Such global analysis of the cytotoxic response to chemotherapeutic drugs may yield insight into the mechanisms of drug action and allow rational design of more effective treatment strategies.

Antineoplastic Agents↗
PubMed2002

Induction of apoptosis by cisplatin and its effect on cell cycle-related proteins and cell cycle changes in hepatoma cells.

We investigated cisplatin-induced apoptosis and the effects on cell cycle-related proteins and cell cycle changes. Two human hepatoma cell lines, HepG2 (with wild-type p53) and Hep3B (with deleted p53), were treated with different concentrations of cisplatin. Cisplatin induced apoptosis in both cell lines as assessed by cell morphology, DNA fragmentation analysis,TdT-mediated dUTP nick end labeling assay and flow cytometry. HepG2 cells were more sensitive to cisplatin than Hep3B. Low-dose cisplatin induced a transient G(1) arrest, S phase block and upregulation of p53 and p21(WAF1/CIP1) expression in HepG2, but not in Hep3B cells. With cisplatin at a high dose, both cell lines underwent apoptosis that was accompanied by downregulation of p27(KIP1) and Bcl-x(L). In HepG2, upregulation of p53 and p21(WAF1/CIP1) was observed before apoptosis occurred, suggesting that cisplatin-induced apoptosis in HepG2 might be p53-dependent. Expression of Fas was also increased following cisplatin treatment in HepG2. However, there was no induction of p53, p21(WAF1/CIP1) and Fas observed in Hep3B cells. In conclusion, cisplatin induced apoptosis in hepatoma cells via both p53-dependent and -independent pathways.

Actins↗
PubMed2002

Activation of cyclin-dependent kinases CDC2 and CDK2 in hepatocellular carcinoma.

BACKGROUND: The cyclin-dependent kinases (CDKs) CDC2 and CDK2 are key regulators of the cell cycle. The expression of the CDK alone does not necessary reflect their true activities because they are highly regulated by post-translational mechanisms. Human hepatocellular carcinoma (HCC) is one of the most common cancers in the world, but the kinase activities of CDKs in HCC have not been examined. METHODS: Here we examined the protein expression and kinase activities associated with CDC2 and CDK2 in HCC and the corresponding non-tumorous liver tissues. RESULTS: CDC2 and CDK2 are activated in HCC in over 70% and 80% of the cases, respectively, but have little correlation with clinical parameters and PCNA expression. Interestingly, PCNA was readily detectable in extracts from non-tumorous liver, but more than 60% of samples contain higher concentration of PCNA in HCC than the corresponding non-tumorous tissues. CDC2 and CDK2 are generally activated in the same HCC samples, but the extent of their activation varied significantly, suggesting that the pathways leading to the activation of CDC2 and CDK2 can be regulated independently. Both positive regulators of CDK activity like cyclins and CDKs, and negative regulators of CDK activity like p21(CIP1/WAF1) and Thr14/Tyr15 phosphorylation were up-regulated in HCC. CONCLUSION: CDC2 and CDK2 are activated in HCC, and this may be due to a complex interplay between the level of the cyclin, CDK, CDK inhibitors, and inhibitory phosphorylation.

CDC2 Protein Kinase↗
PubMed2002

Gene expression patterns in human liver cancers.

Hepatocellular carcinoma (HCC) is a leading cause of death worldwide. Using cDNA microarrays to characterize patterns of gene expression in HCC, we found consistent differences between the expression patterns in HCC compared with those seen in nontumor liver tissues. The expression patterns in HCC were also readily distinguished from those associated with tumors metastatic to liver. The global gene expression patterns intrinsic to each tumor were sufficiently distinctive that multiple tumor nodules from the same patient could usually be recognized and distinguished from all the others in the large sample set on the basis of their gene expression patterns alone. The distinctive gene expression patterns are characteristic of the tumors and not the patient; the expression programs seen in clonally independent tumor nodules in the same patient were no more similar than those in tumors from different patients. Moreover, clonally related tumor masses that showed distinct expression profiles were also distinguished by genotypic differences. Some features of the gene expression patterns were associated with specific phenotypic and genotypic characteristics of the tumors, including growth rate, vascular invasion, and p53 overexpression.

Carcinoma, Hepatocellular↗
PubMed2002

Clinicopathologic and prognostic significance of the histologic activity of noncancerous liver tissue in hepatitis B virus-associated hepatocellular carcinoma.

We prospectively studied 66 patients infected with the hepatitis B virus who underwent liver resection for hepatocellular carcinoma (HCC) to evaluate the influence of the histologic activity of noncancerous liver tissue on clinicopathologic features and prognosis. Based on the histologic activity index (HAI) score of nontumorous liver tissue, patients were classified into 3 groups: mild, moderate, or severe hepatitis. Overall, higher HAI scores were more frequent in patients with poorer liver function: lower serum albumin levels and higher indocyanine green retention at 15 minutes. Moreover, patients with moderate hepatitis had more frequent venous invasion, and the tumor size decreased with increasing HAI scores. Similar results were observed when the fibrosis category was excluded in the calculation of HAI scores. The overall or disease-free survival rates did not differ significantly among the 3 groups of patients. However, higher fibrosis scores were associated significantly with shorter disease-free survival rates. HAI scores correlated significantly with certain clinicopathologic features. In patients with hepatitis B-related HCC, a higher fibrosis score in the nontumorous liver tissue, but not histologic hepatitic activity, seems to be a significant factor predisposing to shorter survival.

Adult↗
PubMed2002

Clinicopathological significance of loss of heterozygosity on chromosome 13q in hepatocellular carcinoma.

PURPOSE: Allelic loss is the most frequently genetic alteration found in hepatocellular carcinoma (HCC). Previous genome-wide studies have indicated that chromosome 13q is one of the most frequently affected chromosomes. However, reports on detailed deletion mapping as well as detailed clinicopathological correlation are scanty. EXPERIMENTAL DESIGN: We performed high-density allelotyping on chromosome 13q in HCC from 60 patients and investigated the correlation between allelic losses on chromosome 13q and the clinicopathological features. RESULTS: Allelic loss at one or more of the 29 microsatellite markers was found in 28 (47%) of the 60 HCCs. Allelic losses were more frequently found in tumors with larger size or in tumors at more advanced tumor stages (P = 0.015 and 0.012, respectively). These two clinicopathological features were also significantly associated with the accumulation of allelic losses in terms of fractional allelic loss index (P = 0.028 and 0.018, respectively). In addition, subchromosomal regions located at 13q12.3-14.1 and 13q32 were found to be significantly associated with advanced tumor stages and larger tumor size, respectively (P = 0.008 and 0.007). CONCLUSIONS: The overall findings suggested that allelic losses on 13q might play an important role in contributing to a more aggressive tumor behavior. Putative tumor suppressor genes might be harbored at 13q12.3-14.1 and 13q32, and inactivation of these genes via allelic losses might enhance tumor progression in HCC.

Adult↗