Zaki A. Sherif

Global Epidemiology of Nonalcoholic Fatty Liver Disease and Perspectives on US Minority Populations

BackgroundNon-alcoholic fatty liver disease (NAFLD) is a clinical syndrome predicted to be the next global epidemic affecting millions of people worldwide. The natural course of this disease including its subtype, non-alcoholic steatohepatitis (NASH), is not clearly defined especially in the African-American segment of the US population.AimsTo conduct a review of the global epidemiology of NAFLD with emphasis on US minority populations.MethodsA thorough search of evidence-based literature was conducted using the Pubmed database and commercial web sources such as Medscape and Google Scholar.ResultsNAFLD and its subtype NASH are becoming the principal cause of chronic liver disease across the world. In the US, Hispanics are the most disproportionately affected ethnic group with hepatic steatosis, and elevated aminotransferase levels, whereas African-Americans are the least affected. Genetic disparities involved in lipid metabolism seem to be the leading explanation for the lowest incidence and prevalence of both NAFLD and NASH in African-Americans.ConclusionsThe unprecedented rise in the prevalence of NAFLD globally requires an initiation of population cohort studies with long-term follow-up to determine the incidence and natural history of NAFLD and its underrepresentation in African-Americans. Future studies should also focus on the delineation of the interplay between genetic and environmental factors that trigger the development of NAFLD and NASH.

Divergent control of Cav-1 expression in non-cancerous Li-Fraumeni syndrome and human cancer cell lines.

Li-Fraumeni syndrome (LFS) is primarily characterized by development of tumors exhibiting germ-line mutations in the p53 gene. Cell lines developed from patients of a LFS family have decreased p53 activity as evidenced by the absence of apoptosis upon etoposide treatment. To test our hypothesis that changes in gene expression beyond p53 per se are contributing to the development of tumors, we compared gene expression in non-cancerous skin fibroblasts of LFS-affected (p53 heterozygous) vs. non-affected (p53 wild-type homozygous) family members. Expression analysis showed that several genes were differentially regulated in the p53 homozygous and heterozygous cell lines. We were particularly intrigued by the decreased expression (~88%) of a putative tumor-suppressor protein, caveolin-1 (Cav-1), in the p53-mutant cells. Decreased expression of Cav-1 was also seen in both p53-knockout and p21-knockout HTC116 cells suggesting that p53 controls Cav-1 expression through p21 and leading to the speculation that p53, Cav-1 and p21 may be part of a positive auto-regulatory feedback loop. The direct relationship between p53 and Cav-1 was also tested with HeLa cells (containing inactive p53), which expressed a significantly lower Cav-1 protein. A panel of nonfunctional and p53-deficient colon and epithelial breast cancer cell lines showed undetectable expression of Cav-1 supporting the role of p53 in the control of Cav-1. However, in two aggressively metastasizing breast cancer cell lines, Cav-1 was strongly expressed suggesting a possible role in tumor metastasis. Thus, there is a divergent control of Cav-1 expression as evidenced in non-cancerous Li-Fraumeni syndrome and some aggressive human cancer cell lines.

Race and colorectal cancer screening compliance among persons with a family history of cancer.

AIM To determine compliance to colorectal cancer (CRC) screening guidelines among persons with a family history of any type of cancer and investigate racial differences in screening compliance. METHODS We used the 2007 Health Information National Trends Survey and identified 1094 (27.4%) respondents (weighted population size = 21959672) without a family history of cancer and 3138 (72.6%) respondents (weighted population size = 58201479) with a family history of cancer who were 50 years and older. We defined compliance with CRC screening as the use of fecal occult blood testing within 1 year, sigmoidoscopy within 5 years, or colonoscopy within 10 years. We compared compliance with CRC screening among those with and without a family member with a history of cancer. RESULTS Overall, those with a family member with cancer were more likely to be compliant with CRC screening (64.9% vs 55.1%; OR = 1.45; 95%CI: 1.20-1.74). The absolute increase in screening rates associated with family history of cancer was 8.2% among whites. Hispanics had lowest screening rates among those without family history of cancer 41.9% but had highest absolute increase (14.7%) in CRC screening rate when they have a family member with cancer. Blacks had the lowest absolute increase in CRC screening (5.3%) when a family member has a known history of cancer. However, the noted increase in screening rates among blacks and Hispanics when they have a family member with cancer were not higher than whites without a family history of cancer: (54.5% vs 58.7%; OR = 1.16; 95%CI: 0.72-1.88) for blacks and (56.7% vs 58.7%; OR = 1.25; 95%CI: 0.72-2.18) for Hispanics. CONCLUSION While adults with a family history of any cancer were more likely to be compliant with CRC screening guidelines irrespective of race/ethnicity, blacks and Hispanics with a family history of cancer were less likely to be compliant than whites without a family history. Increased burden from CRC among blacks may be related to poor uptake of screening among high-risk groups.

Place of birth, cancer beliefs and being current with colon cancer screening among US adults

Background Historically, studies suggested that immigrants acquire the risk of colorectal cancer (CRC) as US-born persons within the same generation. CRC risk of immigrants is largely unknown in this era of cancer screening and widespread immigration. We investigated the association of place of birth and cancer beliefs with uptake of CRC screening. Methods The 2007 Health Information National Trends Survey was used and 4,299 respondents (weighted population size=81,896,392) who were 50 years and older (3,960 US-born and 339 foreign-born) were identified. We defined being current with CRC screening guidelines as the use of fecal occult blood test within 1 year, sigmoidoscopy within 5 years, or colonoscopy within 10 years. We compared being up-to-date with CRC screening among foreign-born versus US-born respondents. Logistic regression models were used to calculate odds ratios (OR) and 95% confidence intervals (CI). Results Overall, 2,594 (63.3%) US-born and 208 (52.8%) foreign-born respondents were current with CRC screening. Foreign-born respondents were less current in unadjusted model (OR 0.65; 95% CI: 0.50-0.85) but became non-statistically significant after adjustment (OR 0.79; 95% CI: 0.51-1.24). Respondents who believed that screening finds cancer when it is easy to treat (OR 2.85; 95% CI: 1.44-3.61), those who believed that cancer can be cured when detected early (OR 1.56; 95% CI: 1.20-2.00), and those who worry about getting cancer (OR 1.34; 95% CI: 1.10-1.61) were likely to be current with CRC screening. However, respondents with fatalistic beliefs were borderline less likely to be current (OR 0.82; 95% CI: 0.65-1.04). Conclusion There is a need to improve education on CRC screening, particularly among foreign-born adults.

Molecular Markers of Hepatitis C Virus-Related Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is triggered by many factors including infection with hepatitis C virus (HCV). However, the molecular basis of the development of HCV-related HCC remains unknown. The present study was designed to reveal the interference of the HCV infection in HCC patients with a set of anti-apoptotic factors, and expression levels of some molecular markers between HCV-related HCC and non-HCV-related HCC. We have determined the plasma circulating levels of Bcl-2, TGF-??, VEGF, ?2-MG, and immunohistochemistry staining of p53 in HCV-related HCC patients (n=40) and compared them in relation to both HCV-free HCC patients (n=37) and normal control group (n=20). The present data do not distinctly predict a significant role of HCV infection on the circulating Bcl-2 protein since in both HCC and HCC/HCV groups a limited number of patients have high levels of Bcl-2. However, TGF-?? expression is markedly decreased in all patients, particularly in HCC associated with HCV. Moreover, serum VEGF is significantly higher in HCC patients with or without HCV infection than in normal control. No significant difference, however, was found between HCV-infected and HCV-free groups. Presence of HCV is associated with a high incidence of Loss of Heterozygosity (LOH) at M6P/IGFIIr site compared to HCV-free patients. Although ?2-MG is markedly elevated in all patients, a significant increase was observed in the presence of HCV. Immunohistochemical positive total staining for p53 protein was detected in 32/77(41.5%); HCC-positive HCV was 21/40 (52.2%), and HCC-negative HCV was 11/37 (29.73%). Collectively, in HCC patients, HCV infection does not affect the levels of Bcl-2 and VEGF. ?2-MG and LOH levels at the M6P/IGFIIr site were higher in the presence of HCV concomitant with a decrease in TGF-?1. There was no significant correlation between p53 and stage of the disease or between p53 protein expression and clinic-pathological manifestations.

A Microbiomic Analysis in African Americans with Colonic Lesions Reveals Streptococcus sp.VT162 as a Marker of Neoplastic Transformation

Increasing evidence suggests a role of the gut microbiota in colorectal carcinogenesis (CRC). To detect bacterial markers of colorectal cancer in African Americans a metabolomic analysis was performed on fecal water extracts. DNA from stool samples of adenoma and healthy subjects and from colon cancer and matched normal tissues was analyzed to determine the microbiota composition (using 16S rDNA) and genomic content (metagenomics). Metagenomic functions with discriminative power between healthy and neoplastic specimens were established. Quantitative Polymerase Chain Reaction (q-PCR) using primers and probes specific to Streptococcus sp. VT_162 were used to validate this bacterium association with neoplastic transformation in stool samples from two independent cohorts of African Americans and Chinese patients with colorectal lesions. The metabolomic analysis of adenomas revealed low amino acids content. The microbiota in both cancer vs. normal tissues and adenoma vs. normal stool samples were different at the 16S rRNA gene level. Cross-mapping of metagenomic data led to 9 markers with significant discriminative power between normal and diseased specimens. These markers identified with Streptococcus sp. VT_162. Q-PCR data showed a statistically significant presence of this bacterium in advanced adenoma and cancer samples in an independent cohort of CRC patients. We defined metagenomic functions from Streptococcus sp. VT_162 with discriminative power among cancers vs. matched normal and adenomas vs. healthy subjects’ stools. Streptococcus sp. VT_162 specific 16S rDNA was validated in an independent cohort. These findings might facilitate non-invasive screening for colorectal cancer.

Caspase Activation and Aberrant Cell Growth in a p53(+/+) Cell Line from a Li-Fraumeni Syndrome Family.

Wild-type p53 is well known to induce cell cycle arrest and apoptosis to block aberrant cell growth. However, p53s unique role in apoptosis and cell proliferation in Li-Fraumeni Syndrome (LFS) has not been well elucidated. The aim of this study is to characterize the activity of wild-type p53 protein in LFS family dominated by a germline negative mutant p53. As expected, etoposide-treated wild-type p53-containing cell lines, LFS 2852 and control Jurkat, showed a greater rate of caspase- and annexin V-induced apoptotic cell death compared to the p53-mutant LFS 2673 cell line although mitochondrial and nuclear assays could not detect apoptosis in these organelles. The most intriguing part of the observation was the abnormal proliferation rate of the wild-type p53-containing cell line, which grew twice as fast as 2673 and Jurkat cells. This is important because apoptosis inducers acting through the mitochondrial death pathway are emerging as promising drugs against tumors where the role of p53 is not only to target gene regulation but also to block cell proliferation. This study casts a long shadow on the possible dysregulation of p53 mediators that enable cell proliferation. The deregulation of proliferation pathways represents an important anticancer therapeutic strategy for patients with the LFS phenotype.

NUCLEAR INHERITANCE OF A GENE AFFECTING MITOCHONDRIAL GENE EXPRESSION

Due to a deficiency in mitochondrial protein synthesis, Chinese hamster lung (CHL) cell mutant Gal− 32 does not grow in galactose or fructose. This report examines the nuclear or cytoplasmic inheritance of this single, recessive mutation. In a control experiment, fusion of Gal+TGsTK− cells with Gal−32TGRTK+ cells resulted in tetraploid hybrids (as verified by karyotyping) that were selected in hypoxanthine/aminopterin/thymidine medium. The majority (2/3) of the control hybrids grew in galactose as expected since Gal− is dominant over Gal−. Fusion of Rhodamine 6-G treated Gal+TGSTK− cells with Gal−32TGRTK+ cells resulted in Rhodamine 6-G-tetraploid hybrids that were selected in hypoxanthine/aminopterin/thymidine medium. The majority (7/12) of the Rhodamine 6-G-hybrids grew in galactose as expected for a nuclearly encoded gene considering that Rhodamine 6-G interferes with transmission of mtDNA but not nuclear DNA. Therefore, these results are compelling in their demonstration of the nuclear origin of the Gal− 32 mutation.

Abstract 4488: Targeted sequencing revealed distinctive and pathogenic mutations in African Americans with colorectal cancer

Background & Aim: We recently analyzed 12 pairs of African American CRC tumors and their matched normal tissue using whole exome sequencing and established a panel of novel mutations that are potentially useful for the detection of CRC in this population. In this study, we examined APC, MSH3, and MSH6 mutations using targeted exome sequencing (TES) to determine distinctive mutations frequencies and their chronology in the neoplastic transformation. Materials & Methods: A total of 140 colon samples: (30 normal, 21 adenomas, 33 advanced adenomas & 56 tumors collected from African Americans were used as our discovery set on an Ion Torrent platform. A subset of 36 samples were used as validation set on an Illumina platform. Bioinformatic analysis was performed on both sets of data. Common mutations were considered validated. Results: Two novel MSH6 mutations were validated. Four known mutations in MSH3 were validated and were located in nonsynonymous (exon 10) and 1synonomous mutation (exon 18). As for the APC, 20 mutations were validated include 4 novel mutations. The novel mutations were 3 stopgain and 1 nonsynonymous located at the EB1 binding site, in the mutational cluster region (MCR), and at the 15 Amino Acid repeat. Conclusion: We here defined novel mutations that target DNA MMR and APC genes in African Americans with colorectal lesions. Greater frequency of mutations in cells defective for DNA repair and APC genes is an advantage in cell growth and genetic instability and relevant to the initiating events of colon tumorigenesis. Citation Format: Hassan Ashktorab, Hamed Azimi, Mike Nickerson, Sara Bass, Joseph Boland, Meredith Yeager, Sudhir Varma, Mohamed Daremipouran, Zaki Sherif, Shima Ghavimi, Babak Shokrani, Edward Lee, Adeyinka Laiyemo, Hassan Brim. Targeted sequencing revealed distinctive and pathogenic mutations in African Americans with colorectal cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4488.

Abstract 800: Dysregulation of DLL4 gene expression in Li-Fraumeni syndrome and tumorigenesis

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA Li-Fraumeni Syndrome (LFS), a clinically and genetically rare heterogeneous cancer syndrome, is characterized primarily by a p53 (TP53) gene mutation. This study is an attempt to understand why 30-40% of LFS patients who do not harbor p53 mutation are nonetheless besieged by the same preponderance of primary cancers, die at an early age, and at the same rate as those with the p53 mutation. LFS provides powerful insights into our understanding of the somatic mutations present in sporadic cancers influenced by p53. The p53 protein is a transcription factor that guards against genomic instability by inducing target genes that mediate its functions. Utilizing cytogenetic techniques, we previously discovered a novel balanced reciprocal translocation t(11;15)(q23;q15) between chromosomes 11 and 15 in the normal skin fibroblasts of a patient with LFS who had bilateral breast cancer but was homozygous for wild-type p53. Analysis of the breakpoint regions of this translocation yielded a number of genes; of particular interest was DLL4 (Delta-like ligand 4, locus 15q15.1), which encodes a ligand that binds to Notch receptors. Notch signaling controls cell fate specification during embryonic and postnatal development. DLL4 is a putative regulator of T cell lineage and thymopoiesis. In this study, we analyzed DLL4 gene expression and regulation in tumorigenesis. We also analyzed the transcriptional regulation of the DLL4 promoter. Our data reveal that DLL4 expression is abrogated in the normal skin fibroblasts of all LFS patients under study and markedly down-regulated in breast cancer cells and neuroblastoma cells due to TP53 mutation, DNA methylation or gene disruption caused by a balanced reciprocal translocation between chromosomes 11q23 and 15q15. Immunohistochemistry (IHC) staining corroborated the down-regulation of DLL4 in cancer tissue samples from different organs. These findings taken together not only have possible implications for karyotype-phenotype correlation in carcinogenesis, specifically of breast cancer, but also shed light on the possible implication of DLL4 in LFS and breast cancer initiation and progression. The drastic reduction or absence in the expression of DLL4 in normal skin fibroblasts of LFS patients as well as breast and brain cancer cells is significant and supports the concept that this ligand may play a role in cancer immune-surveillance and its resuscitation in the tumor microenvironment may stimulate T-cell immunity and suppress tumor growth. This demonstrates that DLL4 may provide a strong platform as an immuno-therapeutic target in LFS and breast cancer patients. Citation Format: Zhixing Yao, Zaki A. Sherif. Dysregulation of DLL4 gene expression in Li-Fraumeni syndrome and tumorigenesis. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 800. doi:10.1158/1538-7445.AM2015-800