Associations between apoE genotype and colon and rectal cancer

Apolipoprotein E is a Potential Biomarker for Predicting Cancer Prognosis and is Correlated with Immune Infiltration

Background

Apolipoprotein E (APOE) is a polymorphic protein that plays a role in lipoprotein transformation and metabolism. It is involved in numerous physiological processes within the body and is closely associated with tumor growth and metastasis. However, the role of APOE in pan-cancer has yet to be evaluated. Therefore, studying the association between APOE and various cancer types is crucial for providing a basis for individualized treatment strategies and clinical prognosis assessment.

Methods

We investigated the diagnostic and prognostic significance of APOE across 33 tumor types, as well as its correlation with tumor mutation burden (TMB) and microsatellite instability (MSI). Additionally, we employed the ESTIMATE and CIBERSORT algorithms to analyze the potential impact of APOE on the immune system. Furthermore, gene set enrichment analysis (GSEA) was conducted to explore its underlying physiological function.

Results

Based on observations from a pan-cancer dataset, APOE expression was significantly different between cancer and normal tissues, and was simultaneously associated with survival outcomes in terms of cancer type, clinical annotation, TMB, MSI, and TICs abundance. In addition, the results also showed that expression of APOE may respond to a variety of cancer chemotherapy.

Conclusion

The findings from this study strongly indicate a close association between APOE and tumor development. Moreover, APOE shows promise as a potential biomarker for predicting prognosis and response to immunotherapy in patients with pan-cancer.

Highly Efficient A-to-G Editing in PFFs via Multiple ABEs

Cytosine base editors (CBEs) and adenine base editors (ABEs) are recently developed CRISPR-mediated genome-editing tools that do not introduce double-strand breaks. In this study, five ABEs, ABE7.10, ABEmax, NG-ABEmax, ABE8e and NG-ABE8e, were used to generate A-to-G (T-to-C) conversions in five genome loci in porcine fetal fibroblasts (PFFs). Variable yet appreciable editing efficiencies and variable activity windows were observed in these targeting regions via these five editors. The strategy of two sgRNAs in one vector exhibited superior editing efficiency to that of using two separate sgRNA expression vectors. ABE-mediated start-codon mutation in APOE silenced its expression of protein and, unexpectedly, eliminated the vast majority of its mRNA. No off-target DNA site was detected for these editors. Substantial off-target RNA events were present in the ABE-edited cells, but no KEGG pathway was found to be significantly enriched. Our study supports that ABEs are powerful tools for A-to-G (T-to-C) point-mutation modification in porcine cells.

From degenerative disease to malignant tumors: Insight to the function of ApoE

Apolipoprotein E (ApoE) is a multifunctional protein involved in lipid transport and lipoprotein metabolism, mediating lipid distribution/redistribution in tissues and cells. It can also regulate inflammation and immune function, maintain cytoskeleton stability, and improve neural tissue Function. Due to genetic polymorphisms of ApoE (ε2, ε3, and ε4), its three common structural isoforms (ApoE2, ApoE3, ApoE4) are also associated with the risk of many diseases, especially degenerative diseases, such as vascular degenerative diseases including atherosclerosis (AS), coronary heart disease (CHD), and neurodegenerative disease like Alzheimer's disease (AD). The frequency of the ε4 allele and APOE variants were significantly higher than that of the ε2 and ε3 alleles in the patients with CHD or AD. In recent years, ApoE has frequently appeared in tumor research and become a tumor biomarker gradually. It has been found that ApoE is highly expressed in most solid tumor tissues, such as glioblastoma, gastric cancer, pancreatic ductal cell carcinoma, etc. Studies illustrated that ApoE could regulate the polarization changes of macrophages, participate in the construction of tumor immune microenvironment, regulate tumor inflammation and immune response and play a role in tumor progression, invasion, and metastasis. Of course, many functions of ApoE and its relationship with diseases are still under research. By reviewing the structure and function of ApoE from degeneration diseases to tumor neoplasms, we hope to better understand such a biomarker and further explore the value of ApoE in later studies.

A Novel Four Mitochondrial Respiration-Related Signature for Predicting Biochemical Recurrence of Prostate Cancer

The biochemical recurrence (BCR) of patients with prostate cancer (PCa) after radical prostatectomy is high, and mitochondrial respiration is reported to be associated with the metabolism in PCa development. This study aimed to establish a mitochondrial respiratory gene-based risk model to predict the BCR of PCa. RNA sequencing data of PCa were downloaded from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases, and mitochondrial respiratory-related genes (MRGs) were sourced via GeneCards. The differentially expressed mitochondrial respiratory and BCR-related genes (DE-MR-BCRGs) were acquired through overlapping BCR-related differentially expressed genes (BCR-DEGs) and differentially expressed MRGs (DE-MRGs) between PCa samples and controls. Further, univariate Cox, least absolute shrinkage and selection operator (LASSO), and multivariate Cox analyses were performed to construct a DE-MRGs-based risk model. Then, a nomogram was established by analyzing the independent prognostic factor of five clinical features and risk scores. Moreover, Gene Set Enrichment Analysis (GSEA), tumor microenvironment, and drug susceptibility analyses were employed between high- and low-risk groups of PCa patients with BCR. Finally, qRT-PCR was utilized to validate the expression of prognostic genes. We identified 11 DE-MR-BCRGs by overlapping 132 DE-MRGs and 13 BCR-DEGs and constructed a risk model consisting of 4 genes (APOE, DNAH8, EME2, and KIF5A). Furthermore, we established an accurate nomogram, including a risk score and a Gleason score, for the BCR prediction of PCa patients. The GSEA result suggested the risk model was related to the PPAR signaling pathway, the cholesterol catabolic process, the organic hydroxy compound biosynthetic process, the small molecule catabolic process, and the steroid catabolic process. Simultaneously, we found six immune cell types relevant to the risk model: resting memory CD4+ T cells, monocytes, resting mast cells, activated memory CD4+ T cells, regulatory T cells (Tregs), and macrophages M2. Moreover, the risk model could affect the IC50 of 12 cancer drugs, including Lapatinib, Bicalutamide, and Embelin. Finally, qRT-PCR showed that APOE, EME2, and DNAH8 were highly expressed in PCa, while KIF5A was downregulated in PCa. Collectively, a mitochondrial respiratory gene-based nomogram including four genes and one clinical feature was established for BCR prediction in patients with PCa, which could provide novel strategies for further studies.

Effects of APOE gene ε4 allele on serum lipid profiles and risk of cardiovascular disease and tumorigenesis in southern Chinese population

Background

Human apolipoprotein E (APOE) polymorphisms are attributable to the presence of three common alleles, namely, ε2, ε3, and ε4, which generate six genotypes, viz, E2/E2, E2/E3, E3/E3, E3/E4, E4/E4, and E2/E4. APOE polymorphisms are associated with all types of tumors and cardiovascular diseases (CVD). However, the relationship between the type of APOE polymorphisms and tumorigenesis remains debatable. Therefore, we aimed to investigate the role of APOE polymorphisms on the tumor with or without CVD in southern China.

Methods

A total of 1438 participants were categorized into 4 groups: 409 patients with tumor, 369 patients with CVD, 338 patients with both tumor and CVD, and 322 controls. APOE polymorphisms were determined by genotyping assay. The factors influencing tumor patients with or without CVD were also analyzed by logistic regression analysis.

Results

The present study involved different types of solid tumors. Lung cancer was the most common cancer (20.2%, 151/747), followed by colorectal (17%, 127/747), esophageal (9.8%, 73/747), and liver (8.7%, 65/747) cancers. E3/E3 was the most frequent genotype, and ɛ3 was the greatest allele frequency in our study population. The frequencies of the E3/E3, E3/E4, E2/E3, E2/E4, E4/E4, and E2/E2 genotypes in tumor patients were 76.97% (575/747), 14.19% (106/747), 6.83% (51/747), 1.2% (9/747), 0.4% (3/747), and 0.4% (3/747), respectively. Tumor patients carrying ε3 with or without CVD showed higher levels of TG, TC, and LDL-C and lower levels of HDL-C compared to the controls carrying ε3. On the other hand, the tumor patients carrying ε4 with or without CVD showed higher levels of TG and LDL-C and lower levels of HDL-C (all P < 0.05). The frequency of APOE ε4 allele and the E3/E4 genotype was relatively greater in tumor or CVD patients (P < 0.001). In addition, ε4 allele acted as an independent risk factor for tumor patients group (P = 0.037, adjusted OR = 1.92, 95% CI 1.04–3.55) and tumor + CVD patients group (P = 0.012, adjusted OR = 2.53, 95% CI 1.22–5.23).

Conclusions

Individuals carrying ε4 are at a higher risk of tumor with or without CVD, and APOE polymorphisms affect the serum lipid profiles.

Cancer diagnosis is associated with a lower burden of dementia and less Alzheimer's-type neuropathology

Cancer and Alzheimer's disease are common diseases in ageing populations. Previous research has reported a lower incidence of Alzheimer's disease-type (amnestic) dementia among individuals with a diagnosis of cancer. Both cancer and amnestic dementia are prevalent and potentially lethal clinical syndromes. The current study was conducted to investigate the association of cancer diagnosis with neuropathological and cognitive features of dementia. Data were analysed from longitudinally evaluated participants in a community-based cohort study of brain ageing who came to autopsy at the University of Kentucky Alzheimer's Disease Research Center. These data were linked to the Kentucky Cancer Registry, a population-based state cancer surveillance system, to obtain cancer-related data. We examined the relationship between cancer diagnosis, clinical dementia diagnosis, Mini-Mental State Examination scores and neuropathological features using inverse probability weighting to address bias due to confounding and missing data. To address bias due to inclusion of participants with dementia at cohort baseline, we repeated all analyses restricted to the participants who were cognitively normal at baseline. Included participants (n = 785) had a mean ± standard deviation age of death of 83.8 ± 8.6 years; 60.1% were female. Cancer diagnosis was determined in 190 (24.2%) participants, and a diagnosis of mild cognitive impairment or dementia was determined in 539 (68.7%). APOE ɛ4 allele dosage was lower among participants with cancer diagnosis compared to cancer-free participants overall (P = 0.0072); however, this association was not observed among those who were cognitively normal at baseline. Participants with cancer diagnosis had lower odds of mild cognitive impairment or dementia, and higher cognitive test scores (e.g. Mini-Mental State Examination scores evaluated 6 and ≤2 years ante-mortem, P < 0.001 for both comparisons). Cancer diagnosis also associated with lower odds of higher Braak neurofibrillary tangle stages (III/IV) or (V/VI), moderate/frequent neuritic plaques, moderate/frequent diffuse plaques and moderate/severe cerebral amyloid angiopathy (all P < 0.05). By contrast, TDP-43, α-synuclein and cerebrovascular pathologies were not associated with cancer diagnosis. Cancer diagnosis was associated with a lower burden of Alzheimer's disease pathology and less cognitive impairment. These findings from a community-based cohort with neuropathological confirmation of substrates support the hypothesis that there is an inverse relationship between cancer and Alzheimer's disease.

The Role of ApoE Serum Levels and ApoE Gene Polymorphisms in Patients with Laryngeal Squamous Cell Carcinoma

Recent studies have revealed that the inflammatory ApoE effect may play a significant role in various cancer development. However, this effect has still not been analyzed in patients with laryngeal squamous cell carcinoma (LSCC). In the present study, we evaluated two single nucleotide polymorphisms (SNPs) of ApoE (rs7412 and rs429358) and determined their associations with LSCC development and the LSCC patients’ five-year survival rate. Additionally, we analyzed serum ApoE levels using an enzyme-linked immunosorbent assay. A total of 602 subjects (291 histologically verified LSCC patients and 311 healthy controls) were involved in this study. The genotyping was carried out using the real-time PCR. We revealed that ApoE ε3/ε3 was associated with a 1.7-fold higher probability of developing LSCC (p = 0.001), with 1.7-fold increased odds of developing LSCC without metastasis to the lymph nodes (p = 0.002) and with a 2.0-fold increased odds of developing well-differentiated LSCC (p = 0.008), as well as 1.6-fold increased odds of developing poorly differentiated LSCC development (p = 0.012). The ApoE ε2/ε4 and ε3/ε4 genotypes were associated with a 2.9-fold and 1.5-fold decrease in the likelihood of developing LSCC (p = 0.042; p = 0.037, respectively). ApoE ε3/ε4 was found associated with a 2.4-fold decreased likelihood of developing well-differentiated LSCC (p = 0.013). Conclusion: ApoE ε2/ε4 and ε3/ε4 were found to play a protective role in LSCC development, while ApoE ε3/ε3 may have a risk position in LSCC development.

Most Pathways Can Be Related to the Pathogenesis of Alzheimer’s Disease

Alzheimer’s disease (AD) is a complex neurodegenerative disorder. The relative contribution of the numerous underlying functional mechanisms is poorly understood. To comprehensively understand the context and distribution of pathways that contribute to AD, we performed text-mining to generate an exhaustive, systematic assessment of the breadth and diversity of biological pathways within a corpus of 206,324 dementia publication abstracts. A total of 91% (325/335) of Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways have publications containing an association via at least 5 studies, while 63% of pathway terms have at least 50 studies providing a clear association with AD. Despite major technological advances, the same set of top-ranked pathways have been consistently related to AD for 30 years, including AD, immune system, metabolic pathways, cholinergic synapse, long-term depression, proteasome, diabetes, cancer, and chemokine signaling. AD pathways studied appear biased: animal model and human subject studies prioritize different AD pathways. Surprisingly, human genetic discoveries and drug targeting are not enriched in the most frequently studied pathways. Our findings suggest that not only is this disorder incredibly complex, but that its functional reach is also nearly global. As a consequence of our study, research results can now be assessed in the context of the wider AD literature, supporting the design of drug therapies that target a broader range of mechanisms. The results of this study can be explored at www.adpathways.org.

Heterogeneity in Alzheimer's Disease Diagnosis and Progression Rates: Implications for Therapeutic Trials

The clinical presentation and the pathological processes underlying Alzheimer's disease (AD) can be very heterogeneous in severity, location, and composition including the amount and distribution of AB deposition and spread of neurofibrillary tangles in different brain regions resulting in atypical clinical patterns and the existence of distinct AD variants. Heterogeneity in AD may be related to demographic factors (such as age, sex, educational and socioeconomic level) and genetic factors, which influence underlying pathology, the cognitive and behavioral phenotype, rate of progression, the occurrence of neuropsychiatric features, and the presence of comorbidities (e.g., vascular disease, neuroinflammation). Heterogeneity is also manifest in the individual resilience to the development of neuropathology (brain reserve) and the ability to compensate for its cognitive and functional impact (cognitive and functional reserve). The variability in specific cognitive profiles and types of functional impairment may be associated with different progression rates, and standard measures assessing progression may not be equivalent for individual cognitive and functional profiles. Other factors, which may govern the presence, rate, and type of progression of AD, include the individuals' general medical health, the presence of specific systemic conditions, and lifestyle factors, including physical exercise, cognitive and social stimulation, amount of leisure activities, environmental stressors, such as toxins and pollution, and the effects of medications used to treat medical and behavioral conditions. These factors that affect progression are important to consider while designing a clinical trial to ensure, as far as possible, well-balanced treatment and control groups.

Colonic Stent as Bridge to Surgery for Malignant Obstruction Induces Gene Expressional Changes Associated with a More Aggressive Tumor Phenotype

BACKGROUND

Colonic stent is recommended as a bridge to elective surgery for malignant obstruction to improve short-term clinical outcomes for patients with colorectal cancer. However, since the oncological outcomes remain controversial, this study aimed to investigate the impact of self-expandable metallic stent (SEMS) on the tumor microenvironment.

METHODS

Patients treated with colonic stent as a bridge to surgery from 2010 to 2015 were identified from hospital records. Tumor biopsies and resected tumor samples of the eligible patients were retrieved retrospectively. Gene expression analysis was performed using the NanoString nCounter PanCancer IO 360 gene expression panel.

RESULTS

Of the 164 patients identified, this study included 21 who underwent colonic stent placement as a bridge to elective surgery. Gene expression analysis revealed 82 differentially expressed genes between pre- and post-intervention specimens, of which 72 were upregulated and 10 downregulated. Among the significantly upregulated genes, 46 are known to have protumor functions, of which 26 are specifically known to induce tumorigenic mechanisms such as proliferation, migration, invasion, angiogenesis, and inflammation. In addition, ten differentially expressed genes were identified that are known to promote antitumor functions.

CONCLUSION

SEMS induces gene expressional changes in the tumor microenvironment that are associated with tumor progression in colorectal cancer and may potentiate a more aggressive phenotype. Future studies are warranted to establish optimal timing of surgery after SEMS insertion in patients with obstructive colorectal cancer.

Flavokawain C exhibits anti-tumor effects on in vivo HCT 116 xenograft and identification of its apoptosis-linked serum biomarkers via proteomic analysis

Chalcones and their derivatives belong to the flavonoid family. They have been extensively studied for their anticancer properties and some have been approved for clinical use. In this study, the in vivo anti-tumor activity of flavokawain C (FKC), a naturally occurring chalcone found in Kava (Piper methysticum Forst) was evaluated in HCT 116 cells (colon carcinoma). We also attempted to identify potential biomarkers and/or molecular targets in serum with applicability in predicting treatment outcome. The anti-tumor effects and toxicity of FKC were assessed using the xenograft nude mice model. Cisplatin was used as positive control. The anti-proliferative and apoptotic activities were then evaluated in tumor tissues treated with FKC. Furthermore, two-dimensional electrophoresis (2-DE) followed by protein identification using MALDI-TOF/TOF-MS/MS was performed to compare the serum proteome profiles between healthy nude mice and nude mice bearing HCT 116 tumor treated with vehicle solution and FKC, respectively. Our results showed that FKC treatment significantly inhibited HCT 116 tumor growth. In vivo toxicity studies showed that administration of FKC did not cause damage to major organs and had no significant effect on body weight. FKC was found to induce apoptosis in tumor, and this was associated with increased expression of cleaved caspase-3 and decreased expression of Ki67 in tumor tissues. Our proteomic analysis identified five proteins that changed in abundance - Ig mu chain C region (secreted form), GRP78, hemopexin, kininogen-1 and apolipoprotein E. Overall, our findings demonstrated the potential of FKC as an anti-cancer agent for the treatment of colon carcinoma.

Apolipoprotein C2 - CD36 Promotes Leukemia Growth and Presents a Targetable Axis in Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a devastating hematologic malignancy that affects the hematopoietic stem cells. The 5-year overall survival (OS) of patients with AML is less than 30%, highlighting the urgent need to identify new therapeutic targets. Here, we analyze gene expression datasets for genes that are differentially overexpressed in AML cells compared with healthy hematopoietic cells. We report that apolipoprotein C2 (APOC2) mRNA is significantly overexpressed in AML, particularly in patients with mixed-lineage leukemia rearrangements. By multivariate analysis, high APOC2 expression in leukemia blasts is significantly associated with decreased OS (HR: 2.51; 95% CI, 1.03-6.07; P = 0.04). APOC2 is a small secreted apolipoprotein that constitutes chylomicrons, very-low-density lipoproteins, and high-density lipoproteins with other apolipoproteins. APOC2 activates lipoprotein lipase and contributes to lipid metabolism. By gain and loss of function approaches in cultured AML cells, we demonstrate that APOC2 promotes leukemia growth via CD36-mediated LYN-ERK signaling activation. Knockdown or pharmacological inhibition of either APOC2 or CD36 reduces cell proliferation, induces apoptosis in vitro, and delays leukemia progression in mice. Altogether, this study establishes APOC2-CD36 axis as a potential therapeutic target in AML.

Apolipoprotein: prospective biomarkers in digestive tract cancer

Digestive tract cancer, which is characterized by high morbidity and mortality, seriously affects the quality of life of patients worldwide. The digestive tract has abundant blood supply and nutriment, providing a suitable environment for tumor cells. Under chemical, physical, and biological stimuli, the activated cancer-related genes promote tumorigenesis. The synthesis of apolipoprotein occurs in the liver, intestine, and other digestive organs. However, the functions of apolipoproteins are not limited to lipid metabolism. An increasing number of studies have revealed that apolipoproteins take part in the regulation of tumor behavior. Apolipoprotein A (apoA) has recently been acknowledged as a beneficial indicator of several cancers, including colon, hepatocellular, and pancreatic cancer. Apolipoprotein E (apoE) can affect tumor susceptibility on account of genetic polymorphism. Levels of apolipoprotein C (apoC), B (apoB), and D (apoD) also impact tumor progression and the prognosis of patients. However, because of individual, racial, and genetic differences, a consensus has not yet been reached. Based on clinical data and analysis, apolipoproteins could be a novel target and marker in tumor therapy and prevention.

Integrated bioinformatics analysis of the association between apolipoprotein E expression and patient prognosis in papillary thyroid carcinoma

The prognosis of most patients with papillary thyroid carcinoma (PTC) is excellent despite some cases of tumor progression or relapse. The present study was designed to reveal possible prognostic risk indicators for PTC. Differentially expressed genes (DEGs) extracted from 4 Gene Expression Omnibus (GEO) cohorts were subjected to functional enrichment analyses by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genome (KEGG) pathway analysis. A dataset from The Cancer Genome Atlas (TCGA) was obtained to filter and validate significant genes using cytoHubba, followed by analysis of their association with clinicopathological characteristics and prognosis. In total, 240 DEGs were identified after data preprocessing. These DEGs were enriched in ‘intracellular redox equilibrium’, ‘release of exosome’, ‘cell adhesion’, ‘regulation of extracellular matrix’, ‘collagen binding’ and ‘energy metabolism’ based on GO analysis which including cellular component, molecular function and biological process. KEGG pathway analysis revealed that the DEGs were enriched in thyroid hormone synthesis, pathways in cancer, focal adhesion, metabolic pathways, apoptosis, PPAR signaling pathway and PI3K/AKT signaling pathway. Using cytoHubba, the following hub genes were identified: Apolipoprotein E (APOE); hemoglobin subunit α1 (HBA1); angiotensin II receptor 1 (AGTR1); collagen I α1 (COL1A1); galectin 3 (LGALS3) and TIMP metallopeptidase inhibitor 1 (TIMP1). The expression of these genes was found to be consistent in TCGA datasets. Kaplan-Meier analysis revealed that APOE was significantly associated with overall survival (P=0.00067) and disease free survival (P=0.00220). Additionally, low expression of APOE was significantly associated with older age (P<0.001) and higher TNM stage (P<0.001) compared with the high expression group. Therefore, APOE may function as a predictive risk indicator for progression as well as prognosis of PTC.

Oxidised low-density lipoprotein, a possible distinguishing lipid profile biomolecule between prostate cancer and benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) and prostate cancer (PCa) share common conditions such as lower urinary tract symptoms (LUTS) and dyslipidaemia. Whether an extensive lipid profile analysis could discriminate between BPH and PCa was the objective. Thirty-six (36) BPH and twenty (20) PCa outpatients of a urology clinic plus forty (40) controls without LUTS, but normal PSA, were recruited. Body mass index (BMI), lipid profile (total cholesterol [CHOL], triglycerides [TG], high-density lipoprotein [HDL], very-low-density lipoprotein [VLDL], low-density lipoprotein [LDL] and Castelli's risk index I [CR I] [TC/HDL]), oxidised LDL, apolipoprotein E, ceramide and PSA were determined. Mean ages for BPH, PCa and control were 69 ± 13, 67 ± 10 and 53 ± 7 years respectively. Most parameters apart from BMI and HDL were significantly different compared to the control group. oxLDL for BPH versus control, PCa versus control and BPH versus PCa was significant (p < 0.001, p = 0.02 and p < 0.001 respectively). Ceramide showed significant group differences. Between BPH and PCa, total cholesterol, LDL and Apo E were significantly different (p = 0.00, p = 0.01 and p = 0.03 respectively). Apo E could potentially be a discriminating biomarker. Receiver operating characteristic curves for TPSA, Apo E and oxLDL demonstrated sensitivity of 69.44 and specificity of 88.24 for oxLDL, hence more discriminatory.

Apolipoprotein E Overexpression Is Associated With Tumor Progression and Poor Survival in Colorectal Cancer

Apolipoprotein E (ApoE) plays a key role in tumorigenesis and progression, such as cell proliferation, angiogenesis and metastasis. ApoE overexpression was associated with aggressive biological behaviors and poor prognosis in a variety of tumor according to previous studies. This study aimed to assess the prognostic value and explore the potential relationship with tumor progression in colorectal cancer (CRC). We collected the expression profiling microarray data from the Gene Expression Omnibus (GEO), investigated the ApoE expression pattern between the primary CRC and liver metastasis of CRC, and then explored the gene with prognostic significance based on the TCGA database. ApoE high expression was associated with poor overall survival (OS, p = 0.015) and progression-free survival (PFS, p = 0.004) based on the public databases. Next, ApoE expression was evaluated in two CRC cohorts by immunohistochemistry, of whom 306 cases were stage II and 201 cases were metastatic liver CRC. In the cohort of the liver metastasis, the ApoE expression was increasing in normal mucosa tissue, primary colorectal cancer (PC), and colorectal liver metastases (CLM) in order. Meanwhile, the level of ApoE expression in stage II tumor sample which had no progression evidence in 5 years was lower than that in PC of synchronous liver metastases. The high ApoE expression in PC was an independent risk factor in both stage II (HR = 2.023, [95% CI 1.297-3.154], p = 0.002; HR = 1.883, [95% CI 1.295-2.737], p = 0.001; OS and PFS respectively) and simultaneous liver metastasis (HR = 1.559, [95% CI 1.096-2.216], p = 0.013; HR = 1.541, [95% CI 1.129-2.104], p = 0.006; OS and PFS respectively). However, the overexpression of ApoE could not predict the benefit from the chemotherapy in stage II. The study revealed that the relevance of the ApoE overexpression in CRC progression, conferring a poor prognosis in CRC patients especially for stage II and simultaneous liver metastasis. These finding may improve the prognostic stratification of patients for clinical strategy selection and promote CRC clinic outcomes.

Hidden heterogeneity in Alzheimer's disease: Insights from genetic association studies and other analyses

Despite evident success in clarifying many important features of Alzheimer's disease (AD) the efficient methods of its prevention and treatment are not yet available. The reasons are likely to be the fact that AD is a multifactorial and heterogeneous health disorder with multiple alternative pathways of disease development and progression. The availability of genetic data on individuals participated in longitudinal studies of aging health and longevity, as well as on participants of cross-sectional case-control studies allow for investigating genetic and non-genetic connections with AD and to link the results of these analyses with research findings obtained in clinical, experimental, and molecular biological studies of this health disorder. The objective of this paper is to perform GWAS of AD in several study populations and investigate possible roles of detected genetic factors in developing AD hallmarks and in other health disorders. The data collected in the Framingham Heart Study (FHS), Cardiovascular Health Study (CHS), Health and Retirement Study (HRS) and Late Onset Alzheimer's Disease Family Study (LOADFS) were used in these analyses. The logistic regression and Cox's regression were used as statistical models in GWAS. The results of analyses confirmed strong associations of genetic variants from well-known genes APOE, TOMM40, PVRL2 (NECTIN2), and APOC1 with AD. Possible roles of these genes in pathological mechanisms resulting in development of hallmarks of AD are described. Many genes whose connection with AD was detected in other studies showed nominally significant associations with this health disorder in our study. The evidence on genetic connections between AD and vulnerability to infection, as well as between AD and other health disorders, such as cancer and type 2 diabetes, were investigated. The progress in uncovering hidden heterogeneity in AD would be substantially facilitated if common mechanisms involved in development of AD, its hallmarks, and AD related chronic conditions were investigated in their mutual connection.

ApoE deficiency promotes colon inflammation and enhances inflammatory potential oxidized-LDL and TNF-α in colon epithelial cells

Although deficiency in Apolipoprotein E (ApoE) is linked to many diseases, its effect on colon homoeostasis remains unknown. ApoE appears to control inflammation by regulating nuclear factor-κB (NF-κB). The present study was designed to examine whether ApoE deficiency affects factors of colon integrity in vivo and given the likelihood that ApoE deficiency increases oxidized lipids and TNF-α, the present study also examined whether such deficiency enhances the inflammatory potential of oxidized-LDL (oxLDL) and TNF-α in colon epithelial cells (CECs), in vitro. Here we show that ApoE deficiency is associated with chronic inflammation systemically and in colonic tissues as assessed by TNF-α levels. Increased colon TNF-α mRNA coincided with a substantial increase in cyclooxygenase (COX)-2. ApoE deficiency enhanced the potential of oxLDL and TNF-α to induce COX-2 expression as well as several other inflammatory factors in primary CECs. Interestingly, oxLDL enhanced TGF-β expression only in ApoE^−/−, but not in wild-type, epithelial cells. ApoE deficiency appears to promote COX-2 expression enhancement through a mechanism that involves persistent NF-κB nuclear localization and PI3 and p38 MAP kinases but independently of Src. In mice, ApoE deficiency promoted a moderate increase in crypt length, which was associated with opposing effects of an increase in cell proliferation and apoptosis at the bottom and top of the crypt respectively. Our results support the notion that ApoE plays a central role in colon homoeostasis and that ApoE deficiency may constitute a risk factor for colon pathologies.

8q24 Polymorphisms and Diabetes Mellitus Regulate Apolipoprotein A-IV in Colorectal Carcinogenesis

BACKGROUND

Here, we explored the genetic interactions between diabetes and oncogenic single-nucleotide polymorphisms (SNPs) that determine colorectal cancer (CRC) morbidity.

METHODS

8q24 rs6983267 polymorphism analysis and cDNA microarray were performed in 107 CRCs to identify the genes associated with diabetes and the oncogenic SNP. Then clinical significance of the gene was validated in 132 CRCs. Meta-analysis of microarray data and diabetic comorbidity was performed.

RESULTS

Of genes associated with a minor SNP allele at 8q24, diabetes, and MYC overexpression, apolipoprotein A-IV (ApoA-IV) was associated with oncogenesis and poor prognosis in CRC patients. Patients with high ApoA-IV expression showed significantly poorer prognosis by univariate and multivariate analysis. Meta-analysis revealed lipid metabolism was associated with ApoA-IV-related oncogenesis in diabetic patients.

CONCLUSIONS

Changes in lipid metabolism associated with aberrant expression of ApoA-IV were risks for CRC oncogenesis.

Causal relevance of circulating high-density lipoprotein cholesterol with cancer: a Mendelian randomization meta-analysis

We summarized published data on the associations of apolipoprotein E (APOE) gene ε2/ε3/ε4 polymorphism with both cancer risk and circulating lipid profiles, aiming to examine the causal relevance between lipids and cancer risk. Article identification and data abstraction were conducted in duplicate and independently by two authors. Data were analyzed by STATA software. Twenty-five articles that examined the associations of APOE gene ε2/ε3/ε4 polymorphism with either cancer risk (n = 22) or circulating lipid changes (n = 4) were eligible. The presence of ε2 and ε4 alleles showed no overall associations with overall cancer risk when compared with ε3 allele. The ε4 allele was significantly associated with 1.40-fold (odds ratio or OR = 1.40; 95% confidence interval or CI: 1.00–1.94; P = 0.047) increased risk of developing cancer in Asian populations, and the presence of heterogeneity was low (I² = 37.6%). Carriers of ε3/ε4 genotype had a significant reduction in circulating HDL-C (WMD = −2.62; 95% CI: −4.19 to −1.04; P = 0.001) without heterogeneity (I² = 16.6%). The predicted odds of having cancer for 1 mg/dL reduction in circulating HDL-C was 1.14 (95% CI: 1.00 to 1.89). The findings of this Mendelian randomization meta-analysis demonstrate that reduced circulating HDL-C might be a potentially causal risk factor for the development of overall cancer in Asians.

Cancer risk among people with type 1 and type 2 diabetes: disentangling true associations, detection bias, and reverse causation

OBJECTIVE

Evidence indicates an increased risk of certain cancers among people with type 2 diabetes. Evidence for rarer cancers and for type 1 diabetes is limited. We explored the excess risk of site-specific cancer incidence and mortality among people with type 1 and type 2 diabetes, compared with the general Australian population.

RESEARCH DESIGN AND METHODS

Registrants of a national diabetes registry (953,382) between 1997 and 2008 were linked to national death and cancer registries. Standardized incidence and mortality ratios (SIRs/SMRs) are reported.

RESULTS

For type 1 diabetes, significant elevated SIRs were observed for pancreas, liver, esophagus, colon and rectum (females only [F]), stomach (F), thyroid (F), brain (F), lung (F), endometrium, and ovary, and decreased SIRs were observed for prostate in males. Significantly increased SMRs were observed for pancreas, liver, and kidney (males only), non-Hodgkin's lymphoma, brain (F), and endometrium. For type 2 diabetes, significant SIRs were observed for almost all site-specific cancers, with highest SIRs observed for liver and pancreas, and decreased risks for prostate and melanoma. Significant SMRs were observed for liver, pancreas, kidney, Hodgkin's lymphoma, gallbladder (F), stomach (F), and non-Hodgkin's lymphoma (F). Cancer risk was significantly elevated throughout follow-up time but was higher in the first 3 months postregistration, suggesting the presence of detection bias and/or reverse causation.

CONCLUSIONS

Type 1 and type 2 diabetes are associated with an excess risk of incidence and mortality for overall and a number of site-specific cancers, and this is only partially explained by bias. We suggest that screening for cancers in diabetic patients is important.

Predicting response to vascular endothelial growth factor inhibitor and chemotherapy in metastatic colorectal cancer

BACKGROUND

Bevacizumab improves progression free survival (PFS) and overall survival (OS) in metastatic colorectal cancer patients however currently there are no biomarkers that predict response to this treatment. The aim of this study was to assess if differential protein expression can differentiate patients who respond to chemotherapy and bevacizumab, and to assess if select proteins correlate with patient survival.

METHODS

Pre-treatment serum from patients with metastatic colorectal cancer (mCRC) treated with chemotherapy and bevacizumab were divided into responders and nonresponders based on their progression free survival (PFS). Serum samples underwent immunoaffinity depletion and protein expression was analysed using two-dimensional difference gel electrophoresis (2D-DIGE), followed by LC-MS/MS for protein identification. Validation on selected proteins was performed on serum and tissue samples from a larger cohort of patients using ELISA and immunohistochemistry, respectively (n = 68 and n = 95, respectively).

RESULTS

68 proteins were identified following LC-MS/MS analysis to be differentially expressed between the groups. Three proteins (apolipoprotein E (APOE), angiotensinogen (AGT) and vitamin D binding protein (DBP)) were selected for validation studies. Increasing APOE expression in the stroma was associated with shorter progression free survival (PFS) (p = 0.0001) and overall survival (OS) (p = 0.01), DBP expression (stroma) was associated with shorter OS (p = 0.037). Increasing APOE expression in the epithelium was associated with a longer PFS and OS, and AGT epithelial expression was associated with a longer PFS (all p < .05). Increasing serum AGT concentration was associated with shorter OS (p = 0.009).

CONCLUSIONS

APOE, DBP and AGT identified were associated with survival outcomes in mCRC patients treated with chemotherapy and bevacizumab.

Cardiovascular, diabetes, and cancer strips: evidences, mechanisms, and classifications

OBJECTIVES

To report and name firstly that there are cardiovascular disease (CVD), diabetes mellitus (DM) and cancers (CDC) strips; and disclose their mechanisms, classifications, and clinical significances.

STUDY DESIGN

Narrative and systematic review study and interpretive analysis.

METHODS

DATA SOURCES AND STUDY SELECTION

to collect and present related evidences on CDC strips from evidence-based, open-access, both Chinese- and English-language literatures in recent 10 years on clinical trials from PubMed according to keywords "CVD, DM and cancers" as well as authors' extensive clinical experience with the treatment of more than fifty thousands of patients with CVD, diabetes and cancers over the past decades, and analyze their related mechanisms and categories which based on authors' previous works.

DATA EXTRACTION

data were mainly extracted from 48 articles which are listed in the reference section of this review. Qualitative, quantitative and mixed data were included, narratively and systematically reviewed.

RESULTS

With several conceptual and technical breakthrough, authors present related evidences on CDC strips, these are, CVD and DM, DM and cancers, cancers and CVD linked, respectively; And "Bad SEED" +/- "bad soil" theory or doctrine may explain this phenomenon due to "internal environmental injure, abnormal or unbalance" in human body resulting from the role of risk factors (RFs) related multi-pathways and multi-targets, which including organ & tissue (e.g., vascular-specific), cell and gene-based mechanisms. Their classifications include main strips/type B, and Branches/type A as showed by tables and figures in this article.

CONCLUSIONS

There are CDC strips and related mechanisms and classifications. CDC strips may help us to understand, prevent, and control related common non-communicable diseases (NCDs) as well as these high risk strips.

Apolipoprotein E polymorphism and colorectal neoplasm: results from a meta-analysis

To investigate the relationship of Apolipoprotein E (APOE) gene polymorphism to colorectal neoplasia (CRN), we performed a systematic review and meta-analysis. Eligible studies were identified through a systematic literature review from PubMed, EMBASE, and the Science Citation Index up to February 2014. A combined analysis was performed, followed by a subgroup analyses stratified by the study design. We used data collected from 8 prospective studies involving respectively a total of 9243 participants and 4310 CRN cases which including 438 patients with colorectal adenoma (CRA), and 3873 patients with colorectal carcinoma (CRC). The pooled data from this meta-analysis indicated there was no significant association between APOE polymorphism and CRN (ε2: P = 0.51, OR 1.04 95% CI 0.93 to 1.16; ε4: P = 0.72, OR 0.98 95% CI 0.90 to 1.07). Interestingly, subgroup analysis demonstrated there was a significant decreased risk for proximal CRN in patients with APOE ε4 (P = 0.0007, OR 0.52 95% CI 0.35 to 0.76). Data showed no significant association between APOE genotype and overall CRN. However, compared with those carry APOE ε3 alleles, persons with APOE ε4 genotype have significant decreased risk suffering from proximal CRN but not from distal CRN.

Association between apolipoprotein E genotype and cancer susceptibility: a meta-analysis

BACKGROUND

Apolipoprotein E (ApoE), a protein primarily involved in lipoprotein metabolism, occurs in three isoforms (E2, E3 and E4). Studies evaluating the association between APOE genotype and incidence of malignancies have given inconclusive results.

OBJECTIVE

The objective of the present study was to analyze the association between APOE genotype and incidence of cancer by a meta-analysis.

METHODS

We conducted a literature search in the electronic databases for studies with information on APOE genotype in malignancies. Sixteen studies (14 case-control and 2 cohort; 77,970 controls and 12,010 cases) were included for the present meta-analysis. Pooled odds ratios (OR) with 95 % confidence intervals (CI) were calculated assuming a random-effect model for all the genotypes and alleles. Subgroup analyses based on study design, ethnicity of populations, site of cancer and source of controls were performed as a post hoc measure. Appropriate tests to detect heterogeneity, publication bias and sensitivity were done at all stages. The review protocol is registered with the PROSPERO database vide registration number CRD42013006496.

RESULTS

The pooled effect measure for the comparisons did not reveal an association in primary analyses. In the subgroup analyses, we observed a negative association between APOE4+ genotypes and overall risk of cancer in the cohort study subgroup (pooled OR 0.86; 95 % CI 0.82-0.91; p < 0.00001; I (2) = 0 %). Sensitivity analyses did not alter the overall pooled effect measure, and there were no evidences to suggest a publication bias.

CONCLUSION

Overall, the present meta-analysis did not show any association between APOE alleles and genotypes with incidence of cancer in general.

Genetic variation in prostaglandin synthesis and related pathways, NSAID use and colorectal cancer risk in the Colon Cancer Family Registry

Although use of non-steroidal anti-inflammatory drugs (NSAIDs) generally decreases colorectal cancer (CRC) risk, inherited genetic variation in inflammatory pathways may alter their potential as preventive agents. We investigated whether variation in prostaglandin synthesis and related pathways influences CRC risk in the Colon Cancer Family Registry by examining associations between 192 single nucleotide polymorphisms (SNPs) and two variable nucleotide tandem repeats (VNTRs) within 17 candidate genes and CRC risk. We further assessed interactions between these polymorphisms and NSAID use on CRC risk. Using a case-unaffected-sibling-control design, this study included 1621 primary invasive CRC cases and 2592 sibling controls among Caucasian men and women aged 18-90. After adjustment for multiple comparisons, two intronic SNPs were associated with rectal cancer risk: rs11571364 in ALOX12 [OR(het/hzv) = 1.87, 95% confidence interval (CI) = 1.19-2.95, P = 0.03] and rs45525634 in PTGER2 (OR(het/hzv) = 0.49, 95% CI = 0.29-0.82, P = 0.03). Additionally, there was an interaction between NSAID use and the intronic SNP rs2920421 in ALOX12 on risk of CRC (P = 0.03); among those with heterozygous genotypes, risk was reduced for current NSAID users compared with never or former users (OR(het) = 0.60, 95% CI = 0.45-0.80), though not among those with homozygous wild-type or variant genotypes. The results of this study suggest that genetic variation in ALOX12 and PTGER2 may affect the risk of rectal cancer. In addition, this study suggests plausible interactions between NSAID use and variants in ALOX12 on CRC risk. These results may aid in the development of genetically targeted cancer prevention strategies with NSAIDs.

Age, gender, and cancer but not neurodegenerative and cardiovascular diseases strongly modulate systemic effect of the Apolipoprotein E4 allele on lifespan

Enduring interest in the Apolipoprotein E (ApoE) polymorphism is ensured by its evolutionary-driven uniqueness in humans and its prominent role in geriatrics and gerontology. We use large samples of longitudinally followed populations from the Framingham Heart Study (FHS) original and offspring cohorts and the Long Life Family Study (LLFS) to investigate gender-specific effects of the ApoE4 allele on human survival in a wide range of ages from midlife to extreme old ages, and the sensitivity of these effects to cardiovascular disease (CVD), cancer, and neurodegenerative disorders (ND). The analyses show that women's lifespan is more sensitive to the e4 allele than men's in all these populations. A highly significant adverse effect of the e4 allele is limited to women with moderate lifespan of about 70 to 95 years in two FHS cohorts and the LLFS with relative risk of death RR = 1.48 (p = 3.6×10⁻⁶) in the FHS cohorts. Major human diseases including CVD, ND, and cancer, whose risks can be sensitive to the e4 allele, do not mediate the association of this allele with lifespan in large FHS samples. Non-skin cancer non-additively increases mortality of the FHS women with moderate lifespans increasing the risks of death of the e4 carriers with cancer two-fold compared to the non-e4 carriers, i.e., RR = 2.07 (p = 5.0×10⁻⁷). The results suggest a pivotal role of non-sex-specific cancer as a nonlinear modulator of survival in this sample that increases the risk of death of the ApoE4 carriers by 150% (p = 5.3×10⁻⁸) compared to the non-carriers. This risk explains the 4.2 year shorter life expectancy of the e4 carriers compared to the non-carriers in this sample. The analyses suggest the existence of age- and gender-sensitive systemic mechanisms linking the e4 allele to lifespan which can non-additively interfere with cancer-related mechanisms.

Discovering genetic origins of healthspan and lifespan could lead to breakthroughs in increasing the years of healthy and long life. In this paper we characterize the association of the e4 allele of the well-studied ApoE gene with lifespan in two generations of participants of large longitudinal studies, the Framingham Heart Study and the Long Life Family Study, and investigate the role of major human diseases such as cardiovascular disease, cancer, and neurodegenerative disorders in this association. This wide range of systemic analyses is possible given the large sample with directly genotyped ApoE polymorphism available from these studies (N = 9841, with 2557 deaths). The analyses show that women's lifespan is more sensitive to the e4 allele than men's in these populations. However, the strongly adverse effect of the e4 allele is not observed for all women, but only for those 70 to 95 years old. Cardiovascular disease, cancer, and neurodegenerative disorders do not mediate the association of the e4 allele with lifespan. However, cancer, but not cardiovascular and neurodegenerative diseases, non-additively enhances this effect resulting in 4.2 years of difference in mean lifespan for the e4 allele carriers compared to the non-carriers.

A case-control study on the effect of Apolipoprotein E genotypes on gastric cancer risk and progression

Background

Apolipoprotein E (ApoE) is a multifunctional protein playing both a key role in the metabolism of cholesterol and triglycerides, and in tissue repair and inflammation. The ApoE gene (19q13.2) has three major isoforms encoded by ε2, ε3 and ε4 alleles with the ε4 allele associated with hypercholesterolemia and the ε2 allele with the opposite effect. An inverse relationship between cholesterol levels and gastric cancer (GC) has been previously reported, although the relationship between apoE genotypes and GC has not been explored so far.

Methods

One hundred and fifty-six gastric cancer cases and 444 hospital controls were genotyped for apoE polymorphism (ε2, ε3, ε4 alleles). The relationship between GC and putative risk factors was measured using the adjusted odds ratios (ORs) and their 95% confidence intervals (CIs) from logistic regression analysis. A gene-environment interaction analysis was performed. The effect of the apoE genotypes on survival from GC was explored by a Kaplan–Meier analysis and Cox proportional hazard regression model.

Results

Subjects carrying at least one apoE ε2 allele have a significant 60% decrease of GC risk (OR=0.40, 95% CI: 0.19 – 0.84) compared with ε3 homozygotes. No significant interaction emerged between the ε4 or ε2 allele and environmental exposures, nor ε2 or ε4 alleles affected the median survival times, even after correcting for age, gender and stadium.

Conclusions

Our study reports for the first time a protective effect of the ε2 allele against GC, that might be partly attributed to the higher antioxidant properties of ε2 compared with the ε3 or ε4 alleles. Given the study’s sample size, further studies are required to confirm our findings.

Trade-off in the effects of the apolipoprotein E polymorphism on the ages at onset of CVD and cancer influences human lifespan

Progress in unraveling the genetic origins of healthy aging is tempered, in part, by a lack of replication of effects, which is often considered a signature of false-positive findings. We convincingly demonstrate that the lack of genetic effects on an aging-related trait can be because of trade-offs in the gene action. We focus on the well-studied apolipoprotein E (APOE) e2/3/4 polymorphism and on lifespan and ages at onset of cardiovascular diseases (CVD) and cancer, using data on 3924 participants of the Framingham Heart Study Offspring cohort. Kaplan-Meier estimates show that the e4 allele carriers live shorter lives than the non-e4 allele carriers (log rank = 0.016). The adverse effect was attributed to the poor survival of the e4 homozygotes, whereas the effect of the common e3/4 genotype was insignificant. The e3/4 genotype, however, was antagonistically associated with onsets of those diseases predisposing to an earlier onset of CVD and a later onset of cancer compared to the non-e4 allele genotypes. This trade-off explains the lack of a significant effect of the e3/4 genotype on survival; adjustment for it in the Cox regression model makes the detrimental effect of the e4 allele highly significant (P = 0.002). This trade-off is likely caused by the lipid-metabolism-related (for CVD) and nonrelated (for cancer) mechanisms. An evolutionary rationale suggests that genetic trade-offs should not be an exception in studies of aging-related traits. Deeper insights into biological mechanisms mediating gene action are critical for understanding the genetic regulation of a healthy lifespan and for personalizing medical care.

High incidence of tumors in diabetic thrombin activatable fibrinolysis inhibitor and apolipoprotein E double-deficient mice

BACKGROUND

Activation of the complement system has been implicated in tumor growth. The antifibrinolytic protein, activated thrombin-activatable fibrinolysis inhibitor (TAFIa), can modulate the activation of the complement system by inactivating the anaphylatoxins C3a and C5a. The apolipoprotein-E (ApoE) genotype has been associated with carcinogenesis.

OBJECTIVE

The aim of this study was to evaluate whether TAFIa can affect the development of cancer in the ApoE-deficient mouse model.

METHODS

TAFI and ApoE double-knockout mice were generated. A group of mice was treated with the diabetogenic and carcinogenic compound streptozotocin (stz). Mice treated with saline, single knockout mice and wild-type (wt) mice served as controls.

RESULTS

Six months after treatment with stz, mice were sacrificed. Hepatic tumors were found in male double-knockout mice treated with stz but none was found in control animals that were not treated with stz or in single knockout of ApoE or wt animals. There was no significant difference in coagulation system activation between the groups of mice. The plasma concentrations of C5a, factor D and transforming growth factor-β1 were increased in TAFI/ApoE double-deficient mice treated with stz compared with the mice of the same genotype treated with saline.

CONCLUSION

Apo-E deficiency alone was not associated with tumors but the lack of TAFI appears to make the mice permissive for tumor formation in ApoE mice.

SHMT1 1420 and MTHFR 677 variants are associated with rectal but not colon cancer

Background

Association between rectal or colon cancer risk and serine hydroxymethyltransferase 1 (SHMT1) C1420T or methylenetetrahydrofolate reductase (MTHFR) C677T polymorphisms was assessed. The serum total homocysteine (HCY), marker of folate metabolism was also investigated.

Methods

The SHMT1 and MTHFR genotypes were determined by real-time PCR and PCR-RFLP, respectively in 476 patients with rectal, 479 patients with colon cancer and in 461 and 478, respective controls matched for age and sex. Homocysteine levels were determined by HPLC kit. The association between polymorphisms and cancer risk was evaluated by logistic regression analysis adjusted for age, sex and body mass index. The population stratification bias was also estimated.

Results

There was no association of genotypes or diplotypes with colon cancer. The rectal cancer risk was significantly lower for SHMT1 TT (OR = 0.57, 95% confidence interval (CI) 0.36-0.89) and higher for MTHFR CT genotypes (OR = 1.4, 95%CI 1.06-1.84). A gene-dosage effect was observed for SHMT1 with progressively decreasing risk with increasing number of T allele (p = 0.014). The stratified analysis according to age and sex revealed that the association is mainly present in the younger (< 60 years) or male subgroup. As expected from genotype analysis, the SHMT1 T allele/MTHFR CC diplotype was associated with reduced rectal cancer risk (OR 0.56, 95%CI 0.42-0.77 vs all other diplotypes together). The above results are unlikely to suffer from population stratification bias. In controls HCY was influenced by SHMT1 polymorphism, while in patients it was affected only by Dukes' stage. In patients with Dukes' stage C or D HCY can be considered as a tumor marker only in case of SHMT1 1420CC genotypes.

Conclusions

A protective effect of SHMT1 1420T allele or SHMT1 1420 T allele/MTHFR 677 CC diplotype against rectal but not colon cancer risk was demonstrated. The presence of SHMT1 1420 T allele significantly increases the HCY levels in controls but not in patients. Homocysteine could be considered as a tumor marker in SHMT1 1420 wild-type (CC) CRC patients in Dukes' stage C and D. Further studies need to clarify why SHMT1 and MTHFR polymorphisms are associated only with rectal and not colon cancer risk.

A case-control study on the effect of apoliprotein E genotype on head and neck cancer risk

BACKGROUND

The apolipoprotein E gene (apoE) has three major isoforms encoded by the ε2, ε3, and ε4 alleles, with the ε4 allele associated with hypercholesterolemia and the ε2 allele with the opposite effect. An inverse relationship between cholesterolemia and head and neck cancer (HNC) has been previously reported, although the relationship between apoE genotypes and HNC has not been explored to date.

METHODS

Four hundred and seventeen HNC cases and 436 hospital controls were genotyped for apoE polymorphisms. Adjusted odds ratios (ORs) and 95% confidence intervals (CI) from logistic regression were used to explore the relationship between HNC and putative risk factors. A gene-environment interaction analysis was done.

RESULTS

A borderline significant 40% decreased HNC risk (OR, 0.58; 95% CI, 0.31-1.05) was observed for individuals carrying at least one ε2 allele. Females carrying at least one ε2 allele showed a 60% risk reduction (OR, 0.43; 95% CI, 0.21-0.90) for HNC compared with ε3 homozygotes. A statistically significant interaction was found between alcohol use and the ε4 allele (P for interaction = 0.04), with a 2-fold increased risk (OR, 2.06; 95% CI, 0.95-4.48) among ever drinkers with an ε4 allele, with respect to ε3 homozygote nondrinkers.

CONCLUSIONS

Our study provides novel evidence of a possible protective effect of the ε2 allele against HNC, probably due to its increased antioxidant properties.

IMPACT

According to our results, apolipoprotein E may play a different role in carcinogenesis other than its well-known role in regulating blood serum cholesterol levels.

Functional polymorphisms to modulate luminal lipid exposure and risk of colorectal cancer

PURPOSE

Fat absorption may play a crucial role in colorectal carcinogenesis by determining intra-colonic exposure to potentially carcinogenic lipid metabolites.

METHODS

We conducted a population-based case-control study that included 1163 cases and 1501 controls to examine whether individuals who carry genetic variants associated with lower lipid absorption have a higher risk of colorectal cancer. Using Taqman assay, we determined FABP2 alanine (A)/threonine (T) polymorphism at codon 54 in exon-2 and APOE isoforms. Multivariable odds ratios (OR) and 95% confidence intervals (CI) were calculated by unconditional logistic regression models, assuming FABP2 A54 and APO non-E4 as high risk alleles.

RESULTS

We found no associations with either of the polymorphisms. The OR associated with FABP2 A54 homozygotes compared with the others was 1.01 (95% CI; 0.86-1.45) and that for non-ApoE4 carriers compared with carries was 0.95 (95% CI; 0.80-1.13). However, there was a statistically significant negative interaction between total fat intake and FABP2 AA genotypes (p=0.025), indicating that the risk of colorectal cancer associated with this polymorphism is higher in the subjects with lower fat intake.

CONCLUSIONS

These results suggest that these SNPs may not be useful in predicting colorectal cancer risk in populations with high fat intake.

High expression of apolipoprotein E impairs lipid storage and promotes cell proliferation in human adipocytes

Apolipoprotein E (apoE), a key regulator of lipid metabolism, is highly produced by adipose tissue and adipocytes. However, there is little information about its role on adipocyte functions. Because apoE-deficiency in adipocytes was shown to impair adipocyte differentiation, we investigated the consequences of apoE high expression on differentiation and proliferation of a human adipocytic cell line (SW872). SW872 cells were transfected with human apoE to induce a fivefold increase in apoE production and secretion. Adipocyte differentiation and proliferation were assayed by measuring lipid content, adipogenic gene expression, cell number, cell resistance to serum deprivation, and cell division kinetics. Cultured apoE-transfected cells accumulated less triglycerides and less cholesterol than control cells. This decrease in lipid accumulation was associated with a strong downregulation of peroxisome proliferator-activated receptors gamma1 and gamma2 and stearoyl-CoA desaturase 1. The decrease in lipid accumulation was not dependent on the presence of lipids, lipoproteins, or PPAR-gamma agonists in the culture medium, nor was it observed with exogenously added apoE. Moreover, we observed that apoE-transfected cells were more resistant to death induced by serum deprivation, and that these cells underwent more cell divisions than control cells. These results bring new evidence of apoE-involvement in metabolic disorders at the adipocyte level.

Association of apolipoprotein E polymorphisms and dietary factors in colorectal cancer

ApoE single nucleotide polymorphisms (SNPs) Cys112Arg (Epsilon-4), and Arg158Cys (Epsilon-2) have been implicated in cardiovascular and Alzheimer's disease, but their role in colorectal cancer (CRC) has not been extensively studied. We investigated whether ApoE polymorphisms alone or in combination with dietary factors selectively contribute to mismatch-repair (MMR) proficient (microsatellite stable/low or MSS/L) vs deficient (microsatellite unstable or MSI-H) CRCs. We carried out a case–control study with 906 CRC cases and 911 unaffected controls to examine the associations between ApoE polymorphisms and dietary factors and assessed their contribution to MSS/L and MSI-H CRCs. We used unconditional logistic regression to evaluate the associations between ApoE SNPs, tumour MSI status, and dietary factors after adjusting for age and sex. All statistical tests were two-sided. No significant differences in ApoE genotype frequencies were observed between CRC cases and unaffected controls. We observed that increased dietary intake of total fat, saturated fat, cholesterol, and red meat was significantly associated with CRC. Among non-ApoE4 carriers, 2–4 and >4 red meat servings/week were associated with developing MSS/L CRC (OR=1.51, 95% CI 1.10–2.07 and OR=1.80, 95% CI 1.30–2.48, respectively), whereas among ApoE4 allele carriers, four or more red meat servings/week were associated with MSI-H CRC (OR=4.62, 95% CI 1.20–17.77) when compared with the controls. ApoE isoforms modulate the risk of MSI-H and MSS/L CRCs among high red meat consumers.

Colon tumor mutations and epigenetic changes associated with genetic polymorphism: insight into disease pathways

Variation in genes associated with serum levels of proteins may be useful for examining specific disease pathways. Using data from a large study of colon cancer, we examine genetic variants in insulin, inflammation, estrogen, metabolizing enzymes, and energy homeostasis genes to explore associations with microsatellite instability (MSI), CpG Island methylator phenotype (CIMP), mutations of p53 in exons 5 through 8, and mutations in codons 12 and 13 of Ki-ras. Insulin-related genes were associated with CIMP-positive and MSI tumors, with the strongest associations among aspirin users. The Fok1 vitamin D receptor (VDR) polymorphism was associated with CIMP-positive/Ki-ras-mutated tumors; the Poly A and CDX2 VDR polymorphisms were associated only with Ki-ras-mutated tumors. NAT2 was associated with CIMP-positive/Ki-ras-mutated tumors but not with MSI tumors. The TCF7L2 rs7903146 polymorphism was associated with p53 mutated tumors. Most associations varied by recent aspirin/NSAID use: IL6 rs1800796 and rs1800795 polymorphisms were associated inversely with tumor mutations in the presence of aspirin/NSAIDs; POMC significantly reduced risk of Ki-ras-mutated tumors when aspirin/NSAIDs were not used; the TCF7L2 rs7903146 was associated with reduced risk of Ki-ras-mutated tumors in the presence of aspirin and increased risk in the absence of aspirin. These data, although exploratory, identify specific tumor subsets that may be associated with specific exposures/polymorphism combinations. The important modifying effects of aspirin/NSAIDs on associations with genetic polymorphisms reinforce the underlying role of inflammation in the etiology of colon cancer.

Apolipoprotein e expression in anaplastic thyroid carcinoma

OBJECTIVES

Apolipoprotein E (Apo E) has been known to play a role in cholesterol transport and metabolism. However, recently the relationship between Apo E and carcinoma progression has been investigated. In this study, we investigated Apo E expression in thyroid carcinoma at both the protein and molecular levels.

METHODS

We investigated Apo E expression at the protein and molecular level in 124 thyroid neoplasms.

RESULTS

In RT-PCR and in situ hybridization, the Apo E mRNA expression level was very low in papillary and follicular carcinomas as well as normal thyroid, but was dramatically elevated in anaplastic carcinoma. In an immunohistochemical study, 32 of 33 anaplastic carcinomas (97.0%) showed high levels of Apo E expression, but this phenomenon was seen only in 1 of 51 papillary carcinomas (2.0%). None of the follicular carcinomas or adenomas showed high levels of Apo E expression.

CONCLUSIONS

These findings suggest that Apo E is one of the typical biological characteristics of anaplastic thyroid carcinoma.

Apolipoprotein E gene polymorphism and allele frequencies in the Lebanese population

Apolipoprotein E (ApoE) genotypes were studied in order to determine the prevalence in the Lebanese population and compare it with other populations. DNA from 160 unrelated healthy donors from our HLA-bank was used. ApoE genotype was determined using the CardioVascular Disease (CVD) StripAssay (this assay is based on a Polymerase Chain Reaction-Reverse Hybridization technique). The prevalence of genotypes E3/3, E3/4, and E2/3 was found to be 69%, 26%, and 22%, respectively, and 0.6% for each of E2/4 and E4/4 genotypes. The Lebanese population tested showed similarities to earlier reported ApoE genotypic distributions (high E3 allele frequency) but also peculiar differences especially to some Arabic countries (total absence of E2 allele among Saudis) and other populations. This is the first report from Lebanon that will serve as a template for future investigations of the prevalence of ApoE alleles in association with various clinical entities.