High prevalence of chronic viral hepatitis B and C in Minnesota Somalis contributes to rising hepatocellular carcinoma incidence

BACKGROUND

Chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infections are known risk factors for liver disease, cirrhosis and hepatocellular carcinoma (HCC). There is substantial global variation in HBV and HCV prevalence resulting in variations in cirrhosis and HCC. We previously reported high prevalence of HBV and HCV infections in Somali immigrants seen at an academic medical center in Minnesota.

AIM

To determine the prevalence of chronic viral hepatitis in Somali immigrants in Minnesota through a community-based screening program.

METHODS

We conducted a prospective community-based participatory research study in the Somali community in Minnesota in partnership with community advisory boards, community clinics and local mosques between November 2010 and December 2015 (data was analyzed in 2020). Serum was tested for hepatitis B surface antigen, hepatitis B core antibody, hepatitis B surface antibody and anti-HCV antibody.

RESULTS

Of 779 participants, 15.4% tested positive for chronic HBV infection, 50.2% for prior exposure to HBV and 7.6% for chronic HCV infection. Calculated age-adjusted frequencies in males and females for chronic HBV were 12.5% and 11.6%; for prior exposure to HBV were 44.8% and 41.3%; and for chronic HCV were 6.7% and 5.7%, respectively. Seven participants developed incident HCC during follow up.

CONCLUSION

Chronic HBV and HCV are major risk factors for liver disease and HCC among Somali immigrants, with prevalence of both infections substantially higher than in the general United States population. Community-based screening is essential for identifying and providing health education and linkage to care for diagnosed patients.

Knockout of sulfatase 2 is associated with decreased steatohepatitis and fibrosis in a mouse model of nonalcoholic fatty liver disease

Sulfatase 2 (SULF2) is a heparan sulfate editing enzyme that regulates the milieu of growth factors and cytokines involved in a variety of cellular processes. We used a murine model of diet-induced steatohepatitis to assess the effect of SULF2 downregulation on the development of nonalcoholic steatohepatitis (NASH) and liver fibrosis. Wild-type B6;129 mice (WT) and Sulf2-knockout B6;129P2-SULF2^{Gt(PST111)Byg} mice (Sulf2-KO) were fed a fast-food diet (FFD) rich in saturated fats, cholesterol, and fructose or a standard chow diet (SC) ad libitum for 9 mo. WT mice on FFD showed a threefold increase in hepatic Sulf2 mRNA expression, and a 2.2-fold increase in hepatic SULF2 protein expression compared with WT mice on SC. Knockout of Sulf2 led to a significant decrease in diet-mediated weight gain and dyslipidemia compared with WT mice on FFD. Knockout of Sulf2 also abrogated diet-induced steatohepatitis and hepatic fibrosis compared with WT mice on FFD. Furthermore, expression levels of the profibrogenic receptors TGFβR2 and PDGFRβ were significantly decreased in Sulf2-KO mice compared with WT mice on FFD. Together, our data suggest that knockout of Sulf2 significantly downregulates dyslipidemia, steatohepatitis, and hepatic fibrosis in a diet-induced mouse model of NAFLD, suggesting that targeting of SULF2 signaling may be a potential therapeutic mechanism in NASH.NEW & NOTEWORTHY We report for the first time that in wild-type (WT) mice, fast-food diet (FFD) induced a threefold increase in hepatic Sulf2 mRNA and a 2.2-fold increase in sulfatase 2 (SULF2) protein expression compared with WT mice on standard chow diet (SC). We showed that knockout of SULF2 ameliorates FFD-induced obesity, hyperlipidemia, steatohepatitis, and fibrosis. These data, along with work from other laboratories, suggest that SULF2 may be critical to the ability of the liver to progress to nonalcoholic steatohepatitis and fibrosis in conditions of overnutrition.

Leu72Met and Other Intronic Polymorphisms in the GHRL and GHSR Genes Are Not Associated with Type 2 Diabetes Mellitus, Insulin Resistance, or Serum Ghrelin Levels in a Saudi Population

BACKGROUND

Ghrelin (GHRL), a gastric peptide encoded by the GHRL gene, is known to be involved in energy homeostasis via its G protein receptor, encoded by the growth hormone secretagogue receptor (GHSR) gene. Some studies have shown associations between plasma GHRL levels and GHRL single-nucleotide polymorphisms (SNPs), namely the Leu72Met polymorphism (rs696217 TG), with type 2 diabetes mellitus (T2DM) and insulin resistance (IR), while others have not. The controversies in these associations raise the issue of 'which SNPs in which populations.' The aim of this study was to investigate whether SNPs in GHRL and/or GHSR genes were associated with T2DM, IR, or plasma GHRL levels among Arab Saudis.

METHODS

Blood was collected from 208 Saudi subjects with (n=107) and without (n=101) T2DM. DNA samples from these subjects were analyzed by real-time polymerase chain reaction to genotype five intronic SNPs in the GHRL (rs696217 TG, rs27647 CT, rs2075356 CT, and rs4684677 AT) and GHSR (rs509030 GC) genes. In addition, plasma GHRL levels were measured by a radioimmunoassay.

RESULTS

None of the SNPs were associated with T2DM, IR, or plasma GHRL levels. The frequencies of the alleles, genotypes, and haplotypes of the five SNPs were comparable between the T2DM patients and the non-diabetic subjects. A large number of the GHRL haplotypes indicates the molecular heterogeneity of the preproghrelin gene in this region.

CONCLUSION

Neither the Leu72Met polymorphism nor the other intronic GHRL and GHSR SNPs were associated with T2DM, IR, or GHRL levels. Further investigations should be carried out to explain the molecular basis of the association of the GHRL peptide with T2DM and IR.

Association of Plasma Ghrelin Levels with Insulin Resistance in Type 2 Diabetes Mellitus among Saudi Subjects

BACKGROUND

Although the exact mechanism of insulin resistance (IR) has not yet been established, IR is the hallmark characteristic of type 2 diabetes mellitus (T2DM). The aim of this study was to examine the relationship between plasma ghrelin levels and IR in Saudi subjects with T2DM.

METHODS

Patients with T2DM (n=107, cases) and non-diabetic apparently healthy subjects (n=101, controls) from Saudi Arabia were included in this study. The biochemical profiles and plasma insulin levels of all subjects were analyzed, and IR was estimated using the homeostatic model assessment of insulin resistance (HOMA-IR) index. Active ghrelin levels in plasma were measured using the radioimmunoassay technique.

RESULTS

Only 46.7% (50 of 107) of the T2DM subjects had IR, including 26% (28 of 107) with severe IR (HOMA-IR ≥5), while 5.9% (six of 101) of the controls had moderate IR (3 ≤HOMA-IR <5). HOMA-IR values were not associated with age, disease duration, or gender. Importantly, T2DM itself and the co-occurrence of IR with T2DM were significantly associated with low plasma ghrelin levels. However, ghrelin levels were inversely correlated with the HOMA-IR index, body weight, and fasting plasma insulin levels, mainly in the control subjects, which was indicative of the breakdown of metabolic homeostasis in T2DM.

CONCLUSION

The prevalence of IR was relatively low, and IR may be inversely associated with plasma ghrelin levels among Saudi patients with T2DM.

Abstract B64: Hepatocellular carcinoma characteristics and outcomes among Somali immigrants

Background: Hepatocellular Carcinoma (HCC) is the 6th most common cancer and the 2nd leading cause of cancer-related mortality in the world. Sub-Saharan Africa and Eastern Asia are regions endemic for viral hepatitis, accounting for 80% of all HCC cases worldwide. A recent hospital-based study assessing the frequency of hepatitis B (HBV), hepatitis C (HCV), and HCC among Somali immigrants seen at Mayo Clinic determined the adjusted frequency for HBsAg positivity was 10-fold higher and anti-HCV positivity was 3-fold higher as compared to non-Somali residents of Olmsted County, Minnesota. Furthermore, HCV infection was identified as the leading contributor to HCC development among Somalis. The overall goal of this study is to determine the risk factors, surveillance, treatment options, and outcomes of Somalis with HCC seen at Mayo Clinic.

Methods: The Mayo Clinic Unified Data Platform Advanced Cohort Explorer (ACE) query tool was used to identify Somali patients seen at Mayo Clinic from March 1, 1998 to March 31, 2015. Clinical notes were searched in ACE using conjunction and disjunction combinations: the terms Somali, Somalia or Somalian were linked with the terms HCC, Hepatocellular Carcinoma or Liver Cancer. Diagnosis was validated using histopathology and/or imaging reports from the electronic medical record (EMR). To confirm the ethnicity of identified patients, names were screened by author HMA who is of Somali heritage. Variables abstracted from the EMR include demographics, etiology of HCC, diagnosis date, date of death or last contact, Child-Turcotte-Pugh class, Barcelona Clinic Liver Cancer (BCLC) stage, comorbid conditions, initial and subsequent treatments, HCC surveillance, cirrhosis and other malignancies.

Results: 54 Somali patients diagnosed with HCC were seen at Mayo Clinic from March 1, 1998 to March 31, 2015. The mean age was 63±16.3 and 36 (67%) individuals were male. Thirty-eight (70%) of the 54 HCC patients had HCV, 14 (26%) had HBV, 1 (2%) had non-alcoholic steatohepatitis (NASH), and 1 (2%) had unknown etiology for HCC. Of those with known HCV genotypes, the most common were genotype 4 (45%) and 3 (35%). At the time of HCC diagnosis, 16 (32%) presented with BCLC stage A, 5 (10%) with stage B, 17 (34%) with stage C, and 12 (24%) with stage D. Of the 54 patients, 43 (80%) had cirrhosis, 15 (28%) had vascular invasion, and 10 (19%) had metastatic HCC. Regarding treatment, 12 (22%) patients received curative treatment while 42 (78%) received palliative treatment. Orthotopic liver transplantation (OLT) was received by 3 (6%) of Somali patients compared to 19% of non-Somali HCC patients seen at Mayo Clinic between 2007 and 2009. HCC was detected during surveillance in 11 (20%) Somali HCC patients; of the 11, 2 (4%) received semiannual surveillance.

Conclusions: These findings provide a starting point to address liver cancer disparities among Somalis. HCV genotype 4 was most commonly associated with HCC development among the study population. Due to low surveillance rates, more Somalis presented with end-stage liver disease. Furthermore, advanced stage HCC was disproportionately found among Somalis compared to the general North American population. A recent study demonstrated that 11% of North American HCC patients seen at 4 major medical centers presented with stage D. By contrast, our study found 25% of Somalis had Stage D HCC. As a result, Somalis are more likely to receive palliative rather than curative treatments. Improving the identification of individuals with chronic HBV or HCV who are at increased risk for HCC and implementing more comprehensive HCC surveillance is likely to reduce the burden of HCC among this population.

Citation Format: Hawa M. Ali, Nasra H. Giama, Hager Ahmed Mohammed, Essa A. Mohamed, Ju Dong Yang, Abdirashid M. Shire, Lewis R. Roberts. Hepatocellular carcinoma characteristics and outcomes among Somali immigrants. [abstract]. In: Proceedings of the Eighth AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 13-16, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2016;25(3 Suppl):Abstract nr B64.

Completion of the human papillomavirus vaccination series lags in Somali adolescents

OBJECTIVE

It is unknown whether the Somali population in the United States is likely to participate in human papillomavirus (HPV) vaccination. We aimed to determine whether Somali girls living in a US community are following the recommendations for HPV vaccination.

MATERIALS AND METHODS

We conducted a study of HPV vaccination among Somali girls seen at Mayo Clinic, Rochester, MN. Each Somali subject was matched by year of birth to white/non-Hispanic subjects in a 1:3 ratio. We abstracted information between August 1, 2006, and December 31, 2009, related to HPV vaccine series initiation and completion. Initiation and completion frequencies were compared between study groups using the χ(2) test.

RESULTS

A total of 251 Somali and 727 white/non-Hispanic girls were identified, using the Rochester Epidemiology Project, who met all inclusion criteria for final analysis. A total of 114 Somali girls (45%) and 334 white/non-Hispanic girls (46%) initiated the series (odds ratio = 0.98; 95% confidence interval = 0.73-1.31), but only 59 Somali girls (52%) completed the vaccination series, compared with 240 (72%) of the white/non-Hispanic girls (odds ratio = 0.42; 95% confidence interval = 0.27-0.65).

CONCLUSIONS

We found Somali girls to be generally accepting of initiating the HPV vaccine series but less likely to complete the series as compared with white non-Hispanic girls of the same age.

Methylated Bone Morphogenetic Protein 3 (BMP3) Gene: Evaluation of Tumor Suppressor Function and Biomarker Potential in Biliary Cancer

Background

Although cholangiocarcinoma (CC) is an uncommon and highly lethal malignancy, early detection enables the application of potentially curative therapies and improves survival. Consequently, tools to improve the early diagnosis of CC are urgently needed. During a screen for genes epigenetically suppressed by methylation in CC that might serve as methylation markers for CC, we found that the BMP3 gene is methylated in CC cell lines, but the potential diagnostic value and the function of BMP3 in CC are unknown.

Methods

We aimed to quantitatively assess BMP3 methylation in resected CC tumor specimens using methylation specific PCR and evaluate the tumor suppressor role of BMP3 in biliary cancer cell lines in comparison to an immortalized normal cholangiocyte cell line. Expression of BMP3 was quantified by mRNA levels before and after treatment with 5-Aza-2’-deoxycytidine and trichostatin A. After transfection with a BMP3-containing plasmid, cell viability was measured using the bromodeoxyuridine incorporation assay and apoptosis quantified by caspase assay.

Results

In primary CC tumor tissue specimens significantly more methylated BMP3 copies were found when compared to matched benign bile duct epithelium from the same patient, with high specificity. BMP3 expression was absent in cell lines with BMP3 methylation; this suppression of BMP3 expression was reversed by treatment with a DNA demethylating agent and histone de-acetylase inhibitor. Transfection of a BMP3-expressing construct into a BMP3-negative biliary cancer cell line restored BMP3 mRNA expression and reduced cell proliferation and cell viability while increasing the rate of apoptosis.

Conclusion

These findings strongly support a tumor suppressor role for BMP3 in CC and suggest that BMP3 methylation may be a new biomarker for early detection of CCs. of the peptidome are also involved.

The transcription factor GLI1 mediates TGFβ1 driven EMT in hepatocellular carcinoma via a SNAI1-dependent mechanism

The role of the epithelial-to-mesenchymal transition (EMT) during hepatocellular carcinoma (HCC) progression is well established, however the regulatory mechanisms modulating this phenomenon remain unclear. Here, we demonstrate that transcription factor glioma-associated oncogene 1 (GLI1) modulates EMT through direct up-regulation of SNAI1 and serves as a downstream effector of the transforming growth factor-β1 (TGFβ1) pathway, a well-known regulator of EMT in cancer cells. Overexpression of GLI1 increased proliferation, viability, migration, invasion, and colony formation by HCC cells. Conversely, GLI1 knockdown led to a decrease in all the above-mentioned cancer-associated phenotypes in HCC cells. Further analysis of GLI1 regulated cellular functions showed that this transcription factor is able to induce EMT and identified SNAI1 as a transcriptional target of GLI1 mediating this cellular effect in HCC cells. Moreover, we demonstrated that an intact GLI1-SNAI1 axis is required by TGFβ1 to induce EMT in these cells. Together, these findings define a novel cellular mechanism regulated by GLI1, which controls the growth and EMT phenotype in HCC.

The human sulfatase 2 inhibitor 2,4-disulfonylphenyl-tert-butylnitrone (OKN-007) has an antitumor effect in hepatocellular carcinoma mediated via suppression of TGFB1/SMAD2 and Hedgehog/GLI1 signaling

Human sulfatase 2 (SULF2) functions as an oncoprotein in hepatocellular carcinoma (HCC) development by promoting tumor growth and metastasis via enhancement of fibroblast growth factor-2/extracellular signal-regulated kinase and WNT/β-catenin signaling. Recent results implicate that SULF2 activates the transforming growth factor beta (TGFB) and Hedgehog/GLI1 pathways in HCC. OKN-007 is a novel phenyl-sulfonyl compound that inhibits the enzymatic activity of SULF2. To investigate the antitumor effect of OKN-007 in HCC, we treated Huh7 cells, which express high levels of SULF2, with OKN-007 and found that it significantly promoted tumor cell apoptosis and inhibited cell proliferation, viability, and migration. To understand the action of OKN-007 on SULF2, we used Huh7 cells which normally express SULF2 and Hep3B cells that do not normally express SULF2. Utilizing Huh7 cells transfected with short hairpin RNA targeting SULF2 and transfection of Hep3B cells with a SULF2 plasmid to enhance SULF2 expression, we showed that the antitumor activity of OKN-007 was more pronounced in cells expressing SULF2. Furthermore, in vivo experiments verified that OKN-007 repressed tumor growth significantly. These results identify SULF2 as an important target of the antitumor effect of OKN-007. To determine the molecular mechanism of the antitumor effect of OKN-007, both TGFB1/SMAD and Hedgehog/GLI1 signaling pathway activity were measured by Western blot and SMAD- or GLI-reporter luciferase assays. We found that both signaling pathways were inhibited by OKN-007. Together, these results show that OKN-007 can suppress TGFB1/SMAD and Hedgehog/GLI1 signaling via its inhibition of SULF2 enzymatic activity. We conclude that OKN-007 or more potent derivatives may be promising agents for the treatment of HCC.

Prevention of hepatocellular carcinoma: progress and challenges

Hepatocellular carcinoma (HCC) is a lethal cancer for both men and women and is caused by multiple risk factors. Most patients with HCC have an underlying liver disease caused by either chronic viral infection due to hepatitis B or hepatitis C virus or non-viral etiologic risk factors such as alcohol, fatty liver disease, dietary aflatoxin exposure, smoking and diabetes mellitus. While these risk factors are progressively and persistently damaging the liver, the majority of patients show very few symptoms of HCC. By the time symptoms appear the cancer is typically at a very advanced stage with limited options for treatment. In order to prevent death from HCC, it is therefore critically important to reduce the prevalence of the major risk factors, identify and treat those at high risk for development of HCC, and institute effective surveillance strategies for early diagnosis and treatment of HCC. This article reviews the recent progress and current challenges to the prevention of HCC.

Viral hepatitis among Somali immigrants in Minnesota: association of hepatitis C with hepatocellular carcinoma

OBJECTIVE

To study the frequencies of chronic hepatitis B virus (HBV) and hepatitis C virus (HCV) infection, and their associations with hepatocellular carcinoma (HCC) in immigrant Somalis seen at Mayo Clinic in Rochester, Minnesota.

PATIENTS AND METHODS

We determined the frequencies of HBV and HCV infection and HCC in immigrant Somalis seen at Mayo Clinic from July 1, 1996, through October 31, 2009. Non-Somali Olmsted County residents served as controls.

RESULTS

For Somali males and females, age-adjusted proportions (per 1000 population) were 209 and 123 for hepatitis B surface antigen (HBsAg), 644 and 541 for hepatitis B core antibody (HBcAb), and 99 and 66 for anti-HCV. The comparative proportions in non-Somalis were 20 and 9 for HBsAg, 126 and 97 for HBcAb, and 32 and 17 for anti-HCV. Hepatitis C virus RNA confirmed that 68 of 73 Somalis (93.2%) and 261 of 282 non-Somalis (92.6%) with positive anti-HCV test results had active HCV infection. Of 30 Somali patients with HCC, 22 (73.3%) tested anti-HCV positive (odds ratio [OR], 31.3; 95% confidence interval [CI], 13.0-75.5; P<.001; compared with anti-HCV-negative Somalis), 5 (16.7%) were HBsAg positive (OR, 1.4; 95% CI, 0.5-3.7; P=.53), and 18 (60.0%) were HBcAb positive (OR, 1.8; 95% CI, 0.8-4.2; P=.16). Viral hepatitis was diagnosed coincident with HCC in 9 of 20 patients (45.0%) with HCV-associated HCCs. Only 4 of 24 cases of HCC (16.7%) were detected during surveillance.

CONCLUSION

Both HBV and HCV occurred frequently in this sample of Somali immigrants. However, HCV was the major risk factor for HCC. Screening Somali immigrants for HCV infection may enhance the prevention, early detection, and optimal treatment of HCC.

Utility of serum immunoglobulin G4 in distinguishing immunoglobulin G4-associated cholangitis from cholangiocarcinoma

Elevated serum immunoglobulin G4 (sIgG4) is a feature of autoimmune pancreatitis (AIP) and IgG4-associated cholangitis (IAC); a >2-fold increase in sIgG4 is considered highly specific for these disorders. Many patients with IAC present with biliary strictures and obstructive jaundice, making cholangiocarcinoma (CCA) an important differential diagnosis. We determined the value of sIgG4 in distinguishing IAC from CCA. sIgG4 levels were measured in a test cohort of 126 CCA and 50 IAC patients. The results were confirmed in a validation cohort of 161 CCA and 47 IAC patients. Of the 126 CCA patients in the test cohort, 17 (13.5%) had elevated sIgG4 (>140 mg/dL) and four (3.2%) had a >2-fold (>280 mg/dL) increase. Primary sclerosing cholangitis (PSC) was present in 31/126 CCA patients, of whom seven (22.6%) had elevated sIgG4 and two (6.5%) had a >2-fold elevation. Of the 50 IAC patients, 39 (78.0%) had elevated sIgG4 and 25 (50.0%) had a >2-fold increase. The results in the validation cohort were consistent with those of the test cohort.

CONCLUSION

Although elevated sIgG4 levels are characteristic of IAC, some patients with CCA, particularly with PSC, have elevated sIgG4 levels, including a small percentage with a more than a 2-fold increase in sIgG4. Therefore, sIgG4 elevation alone does not exclude the diagnosis of CCA. Depending on the prevalence of the two diagnoses, the use of a 2-fold cutoff for sIgG4 may not reliably distinguish IAC from CCA. At a cutoff of 4 times the upper limit of normal, sIgG4 is 100% specific for IAC.

The oncogenic effect of sulfatase 2 in human hepatocellular carcinoma is mediated in part by glypican 3-dependent Wnt activation

Heparan sulfate proteoglycans (HSPGs) act as coreceptors or storage sites for growth factors and cytokines such as fibroblast growth factor and Wnts. Glypican 3 (GPC3) is the most highly expressed HSPG in hepatocellular carcinoma (HCC). Sulfatase 2 (SULF2), an enzyme with 6-O-desulfatase activity on HSPGs, is up-regulated in 60% of primary HCCs and is associated with a worse prognosis. We have previously shown that the oncogenic effect of SULF2 in HCC may be mediated in part through up-regulation of GPC3. Here we demonstrate that GPC3 stimulates the Wnt/β-catenin pathway and mediates the oncogenic function of SULF2 in HCC. Wnt signaling in vitro and in vivo was assessed in SULF2-negative Hep3B HCC cells transfected with SULF2 and in SULF2-expressing Huh7 cells transfected with short hairpin RNA targeting SULF2. The interaction between GPC3, SULF2, and Wnt3a was assessed by coimmunoprecipitation and flow cytometry. β-catenin-dependent transcriptional activity was assessed with the TOPFLASH (T cell factor reporter plasmid) luciferase assay. In HCC cells, SULF2 increased cell surface GPC3 and Wnt3a expression, stabilized β-catenin, and activated T cell factor transcription factor activity and expression of the Wnt/β-catenin target gene cyclin D1. Opposite effects were observed in SULF2-knockdown models. In vivo, nude mouse xenografts established from SULF2-transfected Hep3B cells showed enhanced GPC3, Wnt3a, and β-catenin levels.

CONCLUSION

Together, these findings identify a novel mechanism mediating the oncogenic function of SULF2 in HCC that includes GPC3-mediated activation of Wnt signaling via the Wnt3a/glycogen synthase kinase 3 beta axis.

Sulfatase 2 protects hepatocellular carcinoma cells against apoptosis induced by the PI3K inhibitor LY294002 and ERK and JNK kinase inhibitors

BACKGROUND

Sulfatase 2 (SULF2), an extracellular heparan sulphate 6-O-endosulphatase, has an oncogenic effect in hepatocellular carcinoma (HCC) that is partially mediated through glypican 3, which promotes heparin-binding growth factor signalling and HCC cell growth. SULF2 also increases phosphorylation of the anti-apoptotic Akt kinase substrate GSK3β and SULF2 expression is associated with a decreased apoptotic index in human HCCs.

METHODS

We investigated the functional and mechanistic effects of SULF2 on drug-induced apoptosis of HCC cells using immunohistochemistry, Western immunoblotting, gene transfection, real-time quantitative polymerase chain reaction, MTT and apoptosis assays and immunocytochemistry.

RESULTS

The increased expression of SULF2 in human HCCs was confirmed by immunohistochemistry and immunoblotting. Treatment with inhibitors of MEK, JNK and PI3 kinases decreased the viability of SULF2-negative Hep3B HCC cells and induced apoptotic caspase 3 and 7 activity, which was most strongly induced by the PI3K inhibitor LY294002. Forced expression of SULF2 in Hep3B cells significantly decreased activity of the apoptotic caspases 3 and 7 and induced resistance to LY294002-induced apoptosis. As expected, LY294002 inhibited activation of Akt kinase by PI3K. Conversely, knockdown of SULF2 using an shRNA construct targeting the SULF2 mRNA induced profound cell growth arrest and sensitized the endogenously SULF2-expressing HCC cell lines Huh7 and SNU182 to drug-induced apoptosis. The effects of knockdown of SULF2 on HCC cells were mediated by decreased Akt phosphorylation, downregulation of cyclin D1 and the anti-apoptotic molecule Bcl-2, and upregulation of the pro-apoptotic molecule BAD.

CONCLUSION

The prosurvival, anti-apoptotic effect of SULF2 in HCC is mediated through activation of the PI3K/Akt pathway.

Additive effect of apicidin and doxorubicin in sulfatase 1 expressing hepatocellular carcinoma in vitro and in vivo

BACKGROUND/AIMS

There are limited chemotherapy options for hepatocellular carcinoma (HCC). The heparin-degrading endosulfatase SULF1 functions as a liver tumor suppressor. We investigated the effects of the histone deacetylase inhibitor apicidin in combination with doxorubicin in SULF1-expressing HCC cells in vitro and in SULF1-expressing xenografts in nude mice.

METHODS

We evaluated the effects of apicidin alone or combined with doxorubicin on apoptosis, caspase activity, and phosphorylation of Erk and Akt in SULF1-transfected Huh7 and Hep3B cells in vitro and in vivo.

RESULTS

Apicidin induced HCC cell apoptosis and caspase activation in a dose- and time-dependent manner. Apicidin-induced caspase activation was significantly inhibited by the caspase inhibitor Z-Vad-fmk. Apicidin also decreased phosphorylation of both Erk and Akt. Expression of constitutively-active Mek1 and Akt significantly decreased apicidin-induced apoptosis. The combination of doxorubicin with apicidin significantly increased the anti-tumor effect in the SULF1-expressing Huh7 and Hep3B cells as compared to either apicidin or doxorubicin alone, both in vitro and in vivo.

CONCLUSIONS

The combination of a histone deacetylase inhibitor with doxorubicin may be a novel and promising therapeutic modality for HCCs, particularly for SULF1-expressing HCCs.

The tumor suppressor function of human sulfatase 1 (SULF1) in carcinogenesis

INTRODUCTION

Human sulfatase 1 (SULF1) was recently identified and shown to desulfate cellular heparan sulfate proteoglycans (HSPGs). Since sulfated HSPGs serve as co-receptors for many growth factors and cytokines, SULF1 was predicted to modulate growth factor and cytokine signaling.

DISCUSSION

The role of SULF1 in growth factor signaling and its effects on human tumorigenesis are under active investigation. Initial results show that SULF1 inhibits the co-receptor function of HSPGs in multiple receptor tyrosine kinase signaling pathways, particularly by the heparin binding growth factors--fibroblast growth factor 2, vascular endothelial growth factor, hepatocyte growth factor, PDGF, and heparin-binding epidermal growth factor (HB-EGF). SULF1 is downregulated in the majority of cancer cell lines examined, and forced expression of SULF1 decreases cell proliferation, migration, and invasion. SULF1 also promotes drug-induced apoptosis of cancer cells in vitro and inhibits tumorigenesis and angiogenesis in vivo.

CONCLUSION

Strategies targeting SULF1 or the interaction between SULF1 and the related sulfatase 2 will potentially be important in developing novel cancer therapies.

Sulfatase 2 up-regulates glypican 3, promotes fibroblast growth factor signaling, and decreases survival in hepatocellular carcinoma

It has been shown that the heparin-degrading endosulfatase, sulfatase 1 (SULF1), functions as a liver tumor suppressor, but the role of the related sulfatase, sulfatase 2 (SULF2), in liver carcinogenesis remains to be elucidated. We investigated the effect of SULF2 on liver tumorigenesis. Expression of SULF2 was increased in 79 (57%) of 139 hepatocellular carcinomas (HCCs) and 8 (73%) of 11 HCC cell lines. Forced expression of SULF2 increased HCC cell growth and migration, whereas knockdown of SULF2 using short hairpin RNA targeting SULF2 abrogated HCC cell proliferation and migration in vitro. Because SULF1 and SULF2 desulfate heparan sulfate proteoglycans (HSPGs) and the HSPG glypican 3 (GPC3) is up-regulated in HCC, we investigated the effects of SULF2 on GPC3 expression and the association of SULF2 with GPC3. SULF2-mediated cell growth was associated with increased binding of fibroblast growth factor 2 (FGF2), phosphorylation of extracellular signal-regulated kinase and AKT, and expression of GPC3. Knockdown of GPC3 attenuated FGF2 binding in SULF2-expressing HCC cells. The effects of SULF2 on up-regulation of GPC3 and tumor growth were confirmed in nude mouse xenografts. Moreover, HCC patients with increased SULF2 expression in resected HCC tissues had a worse prognosis and a higher rate of recurrence after surgery.

CONCLUSION

In contrast to the tumor suppressor effect of SULF1, SULF2 has an oncogenic effect in HCC mediated in part through up-regulation of FGF signaling and GPC3 expression.

Highly methylated genes in colorectal neoplasia: implications for screening

Discriminant markers are required for accurate cancer screening. We evaluated genes frequently methylated in colorectal neoplasia to identify the most discriminant ones. Four genes specifically methylated in colorectal cancer [bone morphogenetic protein 3 (BMP3), EYA2, aristaless-like homeobox-4 (ALX4), and vimentin] were selected from 41 candidate genes and evaluated on 74 cancers, 62 adenomas, and 70 normal epithelia. Methylation status was analyzed qualitatively and quantitatively and confirmed by bisulfite genomic sequencing. Effect of methylation on gene expression was evaluated in five colon cancer cell lines. K-ras and BRAF mutations were detected by sequencing. Methylation of BMP3, EYA2, ALX4, or vimentin was detected respectively in 66%, 66%, 68%, and 72% of cancers; 74%, 48%, 89%, and 84% of adenomas; and 7%, 5%, 11%, and 11% of normal epithelia (P < 0.01, cancer or adenoma versus normal). Based on area under the curve analyses, discrimination was not significantly improved by combining markers. Comethylation was frequent (two genes or more in 72% of cancers and 84% of adenomas), associated with proximal neoplasm site (P < 0.001), and linked with both BRAF and K-ras mutations (P < 0.01). Cell line experiments supported silencing of expression by methylation in all four study genes. This study shows BMP3, EYA2, ALX4, and vimentin genes are methylated in most colorectal neoplasms but rarely in normal epithelia. Comethylation of these genes is common, and pursuit of complementary markers for methylation-negative neoplasms is a rational strategy to optimize screening sensitivity.

Epigenetic DNA hypermethylation in cholangiocarcinoma: potential roles in pathogenesis, diagnosis and identification of treatment targets

Cholangiocarcinomas (CCs) are highly lethal malignant tumours arising from the biliary tract epithelium. The disease is notoriously difficult to diagnose and is usually fatal because of its typically late clinical presentation and the lack of effective non-surgical therapeutic modalities. The overall survival rate, including resected patients is poor, with less than 5% of patients surviving 5 years, a rate which has not changed significantly over the past 30 years. Although CC is a relatively uncommon tumor, interest in this disease is rising as incidence and mortality rates for intrahepatic cholangiocarcinoma are increasing markedly worldwide. A variety of risk factors, including primary sclerosing cholangitis, liver fluke infestation, and hepatolithiasis have been described. However, for most CCs the cause is unknown, and affected individuals have no history of exposure to, or association with, known risk factors. Recent advances in molecular pathogenesis have highlighted the importance of epigenetic alterations in the form of promoter region hypermethylation and histone deacetylation in addition to genetic changes in the process of cholangiocarcinogenesis. This review provides a comprehensive overview of the genes reported to be methylated in CC to date and their putative roles in cholangiocarcinogenesis. Future directions in the study of methylated genes and their potential roles as diagnostic and prognostic markers are also discussed.

SINE elements of Entamoeba dispar

Entamoeba histolytica and E. dispar are closely related protozoan parasites; the former causes clinical amoebiasis in humans while the latter appears to be non-pathogenic. The molecular biology of E. histolytica shows a number of unusual features, one of which is the abundance of polyadenylated but apparently untranslatable mRNAs produced; many of these are the product of at least three families of SINEs (EhSINE1-3). Here we show that the genome of E. dispar contains numerous copies of a SINE element (EdSINE1) whose 5'- and 3'-ends are very similar to those of EhSINE1 but with a much less similar middle portion. Twelve out of 18 copies examined had target site duplications. In none out of six cases examined was there a SINE element in the homologous region of the E. histolytica genome but a single copy of EdSINE1 is present in E. histolytica where it is identified as EhSINE3.

Ethnic variation in AMD-associated complement factor H polymorphism p.Tyr402His

Age-related macular degeneration (AMD) is the most common cause of irreversible visual loss in the developed world. Previous studies have demonstrated that the c.1204T>C, p.Tyr402His allelic variant in the complement factor H (CFH) gene is associated with an approximately three-fold increased risk for AMD in Caucasians of predominantly European descent. Both the prevalence as well as the phenotypic spectrum of AMD varies widely among persons of different ethnicities. We hypothesized that populations with a lower prevalence of AMD might also have a lower prevalence of the CFH risk allele. In this study we sought to determine the frequency of this sequence variant in control populations of Caucasians, African Americans, Hispanics, Somalis, and Japanese. Normal control populations were assembled for each ethnic group: Caucasian (n=148), Somali (n=128), African American (n=75), Hispanic (n=81), and Japanese (n=82). Individuals were genotyped using a restriction digest assay and the frequency of the C allele at nucleotide position 1204 of the CFH gene was determined. A bioinformatic approach was used to identify SNPs in linkage disequilibrium with rs1061170 (c.1204T>C, p.Tyr402His) from the human haplotype map project database (HapMap) in order to validate the findings. We found widely discordant frequencies of the risk allele between some of the different ethnic groups: Japanese 0.07+/-0.02, Hispanics 0.17+/-0.03, African-Americans 0.35+/-0.04, Caucasians 0.34+/-0.03, and Somalis 0.34+/-0.03. Allele frequencies generated by analysis of the HapMap database were consistent with these findings. This study suggests that there are other yet unidentified genetic factors important in the pathogenesis of AMD that may mitigate the effects of c.1204T>C, p.Tyr402His variant.