Association between ambient ultraviolet radiation and risk of esophageal cancer

A Review of the Potential Benefits of Increasing Vitamin D Status in Mongolian Adults through Food Fortification and Vitamin D Supplementation

Serum 25-hydroxyvitamin D (25(OH)D) concentrations are low in Mongolia, averaging 22 ng/mL in summer and only 8 ng/mL in winter. Mongolians have high incidence and/or prevalence of several diseases linked to low 25(OH)D concentrations, including ischemic heart disease, malignant neoplasms, cirrhosis of the liver, ischemic stroke, lower respiratory tract infections, preterm birth complications, and diabetes mellitus. Fortifying regularly consumed foods such as flour, milk, and edible oils with vitamin D₃ could raise 25(OH)D concentrations by about 10 ng/mL. However, to achieve 25(OH)D concentrations of 30–40 ng/mL in adults, vitamin D intakes of 1000 to 4000 IU/day would be required, making personal supplement use necessary. On the basis of prospective observational studies and clinical trials of disease incidence or known mortality rates and adverse pregnancy and birth outcomes, raising mean serum 25(OH)D concentrations to 40 ng/mL would likely reduce incidence and mortality rates for those and other diseases, reduce the rate of adverse pregnancy and birth outcomes, and increase mean life expectancy by one year or more.

No Association Between Vitamin D Status and Risk of Barrett's Esophagus or Esophageal Adenocarcinoma: A Mendelian Randomization Study

BACKGROUND & AIMS

Epidemiology studies of circulating concentrations of 25 hydroxy vitamin D (25(OH)D) and risk of esophageal adenocarcinoma (EAC) have produced conflicting results. We conducted a Mendelian randomization study to determine the associations between circulating concentrations of 25(OH)D and risks of EAC and its precursor, Barrett's esophagus (BE).

METHODS

We conducted a Mendelian randomization study using a 2-sample (summary data) approach. Six single-nucleotide polymorphisms (SNPs; rs3755967, rs10741657, rs12785878, rs10745742, rs8018720, and rs17216707) associated with circulating concentrations of 25(OH)D were used as instrumental variables. We collected data from 6167 patients with BE, 4112 patients with EAC, and 17,159 individuals without BE or EAC (controls) participating in the Barrett's and Esophageal Adenocarcinoma Consortium, as well as studies from Bonn, Germany, and Cambridge and Oxford, United Kingdom. Analyses were performed separately for BE and EAC.

RESULTS

Overall, we found no evidence for an association between genetically estimated 25(OH)D concentration and risk of BE or EAC. The odds ratio per 20 nmol/L increase in genetically estimated 25(OH)D concentration for BE risk estimated by combining the individual SNP association using inverse variance weighting was 1.21 (95% CI, 0.77-1.92; P = .41). The odds ratio for EAC risk, estimated by combining the individual SNP association using inverse variance weighting, was 0.68 (95% CI, 0.39-1.19; P = .18).

CONCLUSIONS

In a Mendelian randomization study, we found that low genetically estimated 25(OH)D concentrations were not associated with risk of BE or EAC.

Vitamin D and Gastrointestinal Cancers: A Narrative Review

Calcitriol (1,25(OH)₂D₃) performs various activities throughout the body. Although low serum 25-hydroxyvitamin D [25(OH)D] levels are associated with several disease processes such as risk of fractures and falls, hypertension, cardiovascular disease, and diabetes mellitus, recent evidence attests that this important hormone also regulates several cellular pathways involved in cancer development and progression. Calcitriol modulates several genes controlling gut physiology and calcium homeostasis and also maintains the integrity of epithelial barriers, regulates the absorption of phosphate and calcium, and modulates host defense against pathogens and inflammatory response by interplaying with several types of secretory and immune cells. Vitamin D deficiency is significantly related to increased risk of developing certain types of cancer. This deficiency can be prevented by vitamin D supplementation which is both economical and safe. This can lower the risk of developing cancer and also improve the prognosis of patients with gastrointestinal malignancy, but epidemiological data remain inconsistent. Several retrospective observational studies have demonstrated the benefits of vitamin D supplementation, but a few randomized controlled trials have not seemingly supported the beneficial role of vitamin D supplementation in gastrointestinal cancers. Therefore, in this literature review, we aimed to examine the possible role of vitamin D in gastrointestinal malignancies, including gastric, esophageal, pancreatic, hepatic, and colorectal cancers.

The association of gastrointestinal cancers (esophagus, stomach, and colon) with solar ultraviolet radiation in Iran-an ecological study

Iran has variations in the incidence of cancer in its different provinces. Moreover, it is one of the countries with a high incidence of gastrointestinal cancers in the world. The aim of this study was to investigate the relation between the incidence of esophageal, stomach, and colon cancers with ultraviolet radiation. This is an ecological study. The age-standardized incidence of cancer from 2004 to 2008 was obtained from the National Cancer Registry of Iran for all provinces. UV index data was taken from the world weather site. The altitude and latitude of cities were obtained from the National Topography Organization. Demographic variables were taken from the STEPS report of the Ministry of Health. In this study, lung cancer were used as the index of the effects of smoking. Data were analyzed using the SPSS22 software and through linear regression. UV emission levels showed a strong negative correlation with the incidence of esophageal and gastric cancers, in both genders, in all years. However, this correlation was stronger in men. UV radiation showed a significant correlation with colon cancer among both genders as well. There was no relation between altitude and incidence of cancer. Linear regression results showed that with a unit increase in UV, the incidence of gastric and esophagus cancers in males decreases by β = -4.99 and β = - 3.16 significant coefficients, respectively. Cities with higher levels of UV index have a relatively lower incidence of gastrointestinal cancers. Ultraviolet radiation may act as a protective factor against these cancers.

Association of Vitamin D and Parathyroid Hormone With Barrett's Esophagus

BACKGROUND

Esophageal adenocarcinoma has been inversely associated with exposure to ultraviolet radiation. This could be because of vitamin D deficiency or hyperparathyroidism promoting gastroesophageal reflux disease (GERD) and Barrett's esophagus.

AIM

The aim of this study is to determine the association between parathyroid hormone (PTH) and vitamin D deficiency with GERD symptoms, erosive esophagitis, and Barrett's esophagus.

METHODS

We assayed banked serum for PTH and total 25-hydroxy vitamin D from a cross-sectional cohort. Logistic regression was performed to estimate the associations of vitamin D deficiency and hyperparathyroidism with GERD symptoms, erosive esophagitis, and Barrett's esophagus.

RESULTS

Sera from 605 men were assayed, including 150 with GERD, 216 with erosive esophagitis, 145 with Barrett's esophagus, and 174 normal subjects. Contrary to our hypothesis, we found a strong inverse association between Barrett's esophagus and hyperparathyroidism (odds ratio=0.516; 95% confidence interval=0.265, 1.01), and a trend toward an inverse association with vitamin D deficiency. We found no association between vitamin D deficiency or hyperparathyroidism with GERD symptoms or erosive esophagitis.

CONCLUSIONS

Contrary to our hypothesis, we found an inverse association between serum PTH and Barrett's esophagus. Validation of the finding and the mechanism of that association deserves further study.

Systematic review: the etiology of esophageal squamous cell carcinoma in low-income settings

Esophageal carcinoma causes over 380 000 deaths per year, ranking sixth worldwide in mortality amongst all malignancies. Globally, the squamous cell subtype is most common and accounts for 80% of esophageal cancers. Nonetheless, esophageal squamous cell carcinoma is much more poorly understood than esophageal adenocarcinoma, including what is driving such high prevalences, why it often presents in young patients, and shows such marked geographical delineations Areas covered: The current literature was searched for articles focusing on aetiopathogenesis of squamous cell esophageal carcinoma via a systematic review, particularly in low-resource settings. This was supplemented by papers of interest known to the authors. Expert commentary: Current putative mechanisms include polycyclic aromatic hydrocarbons, nitrosamines, acetaldehyde, cyclo-oxygenase-2 pathways, androgen and their receptor levels, as well as smoking & alcohol, micronutrient deficiencies and diet, mycotoxins, thermal damage, oral hygiene and microbiotal factors, inhaled smoke, viral infections such as HPV, and chronic irritative states. Etiology is likely multifactorial and varies geographically. Though smoking and alcohol play a predominant role in high-income settings, there is strong evidence that mycotoxins, diet and temperature effects may play an under-recognized role in low and middle-income settings.

Vitamin D receptor as a marker of prognosis in oesophageal adenocarcinoma: a prospective cohort study

AIMS

Vitamin D receptor (VDR) expression has been associated with survival in several cancer sites. This study aims to evaluate the association between VDR expression and prognosis in oesophageal adenocarcinoma patients.

RESULTS

During a median of 2.5 (maximum 9) years of follow-up, 75 patients died. In analysis adjusted for confounders, higher VDR expression was associated with an improved overall survival (HR 0.49 95% CI 0.25-0.96) and disease-specific survival (HR 0.50 95% CI 0.26-0.99), when comparing the highest with the lowest tertile of expression. These associations were strongest in sensitivity analysis restricted to junctional tumours.

CONCLUSIONS

This study is the first to demonstrate that patients with higher VDR expression in oesophageal adenocarcinoma have a more favourable prognosis. Further work is needed to validate these findings, and to define the role of VDR in the aetiology, progression and management of oesophageal adenocarcinoma.

METHODS

Oesophageal adenocarcinoma specimens and clinical data were collected from 130 patients treated with neo-adjuvant chemotherapy prior to surgical resection at the Northern Ireland Cancer Centre between 2004 and 2012. Tissue microarrays were created and immunohistochemical staining for VDR was performed on triplicate tumour cores from each resection specimen. Cox proportional hazards models were applied to evaluate associations between VDR, according to tertiles of expression, and survival outcomes.

Does sunlight protect us from cancer?

The Ultraviolet (UV) radiation contained in sunlight is a powerful mutagen and immune suppressant which partly explains why exposure to solar UV is the biggest risk factor for the development of cutaneous tumours. Evidence is building that sunlight may be protective against some internal malignancies. Because patients with these tumours are often vitamin D deficient, this has led some to propose that vitamin D supplementation will be beneficial in the treatment of these cancers. However, the results from already completed trials have been disappointing which has given weight to the argument that there must be something else about sunlight that explains its cancer-protecting properties.

Annual Ambient UVB at Wavelengths that Induce Vitamin D Synthesis is Associated with Reduced Esophageal and Gastric Cancer Risk: A Nested Case-Control Study

Vitamin D has been shown to be beneficial at reducing the risk of cancer; however, studies examining esophageal and gastric cancer have been scarce and findings inconsistent. The UK Biobank cohort was used for this nested case-control study (N = 3732). Primary, incident esophageal and gastric cancer cases diagnosed after recruitment were identified via linkage to National Cancer Registries. Tropospheric Emissions Monitoring Internet Service database was used to calculate ambient annual UVB dose (D-UVB). Conditional logistic regression was used to investigate the relationship between annual ambient D-UVB and risk of esophageal and gastric cancer, and odds ratios (ORs) are reported. In total, 373 esophageal and 249 gastric cancer cases and 3110 age- and gender-matched controls were included in the study. We found a strong inverse association between annual ambient D-UVB and odds of developing esophageal or gastric cancer: Compared to the lowest tertile, OR for the highest tertile was 0.64 (95%CI:0.51-0.79) in adjusted analysis. The association was strengthened when restricted to esophageal cancer (OR = 0.60; 95%CI:0.45-0.80) and esophageal adenocarcinoma cases (OR = 0.48; 95%CI: 0.34-0.68). Similar results were found in unadjusted and stratified analysis. In conclusion, ambient UVB radiation is inversely associated with the development of esophageal and gastric cancer, even in a high-latitude country.

Vitamin D in esophageal cancer: Is there a role for chemoprevention?

Vitamin D has emerged as a promising anti-cancer agent due to its diverse biological effects on tumor differentiation, apoptosis and suppression of cellular proliferation. Current evidence suggests a protective role of vitamin D in colon cancer. The effect of vitamin D on esophageal cancer remains controversial. Multiple studies investigated the association between vitamin D and esophageal cancer, employing different modes of assessment of vitamin D status such as serum 25-hydroxyvitamin D levels, vitamin D dietary intake or exposure to ultraviolet B (UVB) radiation. Genetic variations of the vitamin D receptor (VDR) gene and VDR expression in esophageal specimens have also been investigated. Ecological studies evaluating exposure to UVB radiation yielded an inverse correlation with esophageal cancer. When vitamin D dietary intake was assessed, direct association with esophageal cancer was observed. However, circulating 25-hydroxyvitamin D concentrations showed inconsistent results. In this review article, we present a detailed summary of the current data on the effects of vitamin D on various histological subtypes of esophageal cancer and their precursor lesions. Well-powered prospective studies with accurate measurement of vitamin D status are needed before chemoprevention with vitamin D is recommended, as current evidence does not support a chemopreventive role of vitamin D against esophageal cancer. Future studies looking at the incidence of esophageal cancer in patients with pre-cancerous lesions (Barrett's esophagus and squamous cell dysplasia) receiving vitamin D supplementation are needed.

Temporal Trends in Satellite-Derived Erythemal UVB and Implications for Ambient Sun Exposure Assessment

Ultraviolet radiation (UVR) has been associated with various health outcomes, including skin cancers, vitamin D insufficiency, and multiple sclerosis. Measurement of UVR has been difficult, traditionally relying on subject recall. We investigated trends in satellite-derived UVB from 1978 to 2014 within the continental United States (US) to inform UVR exposure assessment and determine the potential magnitude of misclassification bias created by ignoring these trends. Monthly UVB data remotely sensed from various NASA satellites were used to investigate changes over time in the United States using linear regression with a harmonic function. Linear regression models for local geographic areas were used to make inferences across the entire study area using a global field significance test. Temporal trends were investigated across all years and separately for each satellite type due to documented differences in UVB estimation. UVB increased from 1978 to 2014 in 48% of local tests. The largest UVB increase was found in Western Nevada (0.145 kJ/m2 per five-year increment), a total 30-year increase of 0.87 kJ/m2. This largest change only represented 17% of total ambient exposure for an average January and 2% of an average July in Western Nevada. The observed trends represent cumulative UVB changes of less than a month, which are not relevant when attempting to estimate human exposure. The observation of small trends should be interpreted with caution due to measurement of satellite parameter inputs (ozone and climatological factors) that may impact derived satellite UVR nearly 20% compared to ground level sources. If the observed trends hold, satellite-derived UVB data may reasonably estimate ambient UVB exposures even for outcomes with long latency phases that predate the satellite record.

Markers of Vitamin D Exposure and Esophageal Cancer Risk: A Systematic Review and Meta-analysis

Vitamin D has been associated with reduced risk of many cancers, but evidence for esophageal cancer is mixed. To clarify the role of vitamin D, we performed a systematic review and meta-analysis to evaluate the association of vitamin D exposures and esophageal neoplasia, including adenocarcinoma, squamous cell carcinoma (SCC), Barrett's esophagus, and squamous dysplasia. Ovid MEDLINE, EMBASE, and Web of Science were searched from inception to September 2015. Fifteen publications in relation to circulating 25-hydroxyvitamin D [25(OH)D; n = 3], vitamin D intake (n = 4), UVB exposure (n = 1), and genetic factors (n = 7) were retrieved. Higher [25(OH)D] was associated with increased risk of cancer [adenocarcinoma or SCC, OR = 1.39; 95% confidence interval (CI), 1.04-1.74], with the majority of participants coming from China. No association was observed between vitamin D intake and risk of cancer overall (OR, 1.03; 0.65-1.42); however, a nonsignificantly increased risk for adenocarcinoma (OR, 1.45; 0.65-2.24) and nonsignificantly decreased risk for SCC (OR, 0.80; 0.48-1.12) were observed. One study reported a decreased risk of adenocarcinoma with higher UVB exposure. A decreased risk was found for VDR haplotype rs2238135(G)/rs1989969(T) carriers (OR, 0.45; 0.00-0.91), and a suggestive association was observed for rs2107301. In conclusion, no consistent associations were observed between vitamin D exposures and occurrence of esophageal lesions. Further adequately powered, well-designed studies are needed before conclusions can be made. Cancer Epidemiol Biomarkers Prev; 25(6); 877-86. ©2016 AACR.

The contributions of adjusted ambient ultraviolet B radiation at place of residence and other determinants to serum 25-hydroxyvitamin D concentrations

BACKGROUND

Solar ultraviolet B (UVB) radiation is the major source of vitamin D (vitD) for humans.

OBJECTIVES

To describe ambient UVB radiation at wavelengths that induce vitD synthesis (vitD-UVB) in Scotland, and to examine the relationship to serum 25-hydroxyvitamin D (25OHD).

METHODS

We estimated the average vitD-UVB dose for each day of the year and for each postcode area in Scotland, using the Tropospheric Emission Monitoring Internet Service database. Cumulative and weighted vitD-UVB (CW-vitD-UVB) exposure at place of residence was calculated for each participant. Plasma 25OHD was assayed in 1964 healthy participants.

RESULTS

Significant seasonal and geographical variation in vitD-UVB was observed. Ambient vitD-UVB exposure at place of residence was significantly associated with plasma 25OHD (P < 0·01). An average increase in 25OHD of 1 ng mL(-1) was observed for every 1000 mJ cm(-2) higher CW-vitD-UVB dose or for every 2·5 μg of daily supplement taken. Adequate 25OHD concentration (> 16 ng mL(-1)) was observed in the majority when CW-vitD-UVB dose was > 6000 mJ cm(-2), a level of ambient radiation achieved only in summer months in Scotland. When predicting vitD deficiency, dramatic improvement in the area under the curve was observed (from 0·55 to 0·70) after CW-vitD-UVB dose was added to the model, in addition to a range of other covariates.

CONCLUSIONS

Ambient vitD-UVB can be a useful predictor of vitD status. Geotemporally mapped measurements of vitD-UVB can be used as a proxy for vitD status or as a covariate in epidemiological research, particularly if 25OHD is unavailable.

Serum 25-Hydroxyvitamin D Levels and the Risk of Dysplasia and Esophageal Adenocarcinoma in Patients with Barrett's Esophagus

BACKGROUND

To date, there are no studies reporting an association between vitamin D and Barrett's esophagus (BE), the precursor for esophageal adenocarcinoma (EAC).

AIMS

Our aim was to study the association between serum 25-hydroxyvitamin D (25(OH)D) levels and prevalence and incidence of dysplasia/EAC in BE.

METHODS

Patients from our BE Registry cohort seen between 2000 and 2012 who had serum 25(OH)D levels measured were included. Age, gender, race, BE length, hiatal hernia size, and histological findings were recorded. Patients without high-grade dysplasia (HGD)/EAC at or within 1 year of index biopsy and who had follow-up endoscopies and 25(OH)D levels were studied for incidence of dysplasia/EAC.

RESULTS

Among 429 patients with BE, the mean 25(OH)D level was 72 ± 31.2 nmol/L. Hundred and one (23.6 %) patients had deficiency (<50 nmol/L), 149 (34.7 %) had insufficiency (50-74.9 nmol/L), and 179 (41.7 %) had normal levels of 25(OH)D. There was no association between serum 25(OH)D levels and dysplasia (p = 0.90). In the incidence cohort of 246 patients with median follow-up of 46 months, there were 34 cases of low-grade dysplasia, 12 of HGD, and 5 of EAC. Change in 25(OH)D levels did not impact progression to dysplasia/EAC (every 5 nmol/L increase from baseline, hazard ratio 0.98; p = 0.62).

CONCLUSIONS

Serum 25(OH)D levels were low in 58.3 % of our BE cohort. There was no association between 25(OH)D levels and prevalence or incidence of HGD/EAC in patients with BE. Further long-term studies are needed to study the association between vitamin D status and progression of dysplasia in BE.

Risk factors for Barrett's esophagus

PURPOSE OF REVIEW

To summarize the emerging data on the risk factors for Barrett's esophagus and risk stratification tools.

RECENT FINDINGS

Obesity, particularly abdominal obesity, is associated with Barrett's esophagus, likely because of both mechanical effects promoting gastroesophageal reflux and nonmechanical effects. Circulating peptides related to obesity alter the risk of Barrett's esophagus and may work synergistically with gastroesophageal reflux. Tobacco use is an underappreciated risk for Barrett's esophagus. A number of genetic variants have been associated with Barrett's esophagus, involving pathways in esophageal development. Risk stratification tools are becoming available that have modest discriminatory capability and good calibration.

SUMMARY

The developing understanding of risk factors for Barrett's esophagus is shifting the clinical guidelines to a nuanced approach incorporating multiple risk factors to select patients for screening for Barrett's esophagus.

The vitamin D hypothesis revisited: race-based disparities in birth outcomes in the United States and ultraviolet light availability

Skin color has been proposed to contribute to race-based health disparities in the United States because of differences in ultraviolet (UV) light-induced vitamin D synthesis. The prediction of this hypothesis, herein named the UVD hypothesis, is that racial disparities in health outcomes are correlated with UV light availability. This paper investigates whether UV light availability is associated with disparities in the rates of low birth weight (LBW) and preterm birth (PTB) between whites and blacks, because these outcomes are thought to be influenced by vitamin D status and to shape disease risk in later life. Data on LBW and PTB from 2007 (n = 2,825,620 births) were compared with data on UV light exposure across the United States. Contrary to the predictions of the UVD hypothesis, LBW and PTB rate disparities were greatest in states with the highest UV light exposure. Notably, income inequality was positively and significantly related to LBW and PTB disparities, even after controlling for UV light availability. The results of this analysis demonstrate that there is a significant environmental gradient in racial disparities in birth outcomes in the United States, but other social or environmental factors associated with living in the southern United States are likely stronger contributors to disparities in birth outcomes than UV light-induced vitamin D status.

1,25-dihydroxyvitamin D in the pathogenesis of Barrett's esophagus and esophageal adenocarcinoma

The incidence of reflux-related esophageal disease - Barrett's esophagus and esophageal adenocarcinoma - is rising, and the prognosis remains poor. Evidence exists that 1,25-dihydroxyvitamin D may augment the course of colon, breast and prostate cancer but little knowledge exists regarding its impact on disease of the esophagus. Important immune cells involved in reflux-related esophageal disease include CD4(+) T cells, macrophages and dendritic cells, and key signaling pathways include Wnt, Hedgehog, NFκ-B and IL-6-JAK-STAT. There is an inter-relationship between these entities and 1,25-dihydroxyvitamin D, which has been described in animal models and some human tissue. Despite this, there is an incomplete understanding of how the immune cell population and signaling pathways contribute to the course and prognosis of Barrett's esophagus and esophageal adenocarcinoma. More investigation with a focus on the clinical outcomes of patients with Barrett's esophagus and esophageal adenocarcinoma and the immune cell population and cell signaling activity in the diseased esophagus is necessary to determine the immunomodulatory role of 1,25-dihydroxyvitamin D in the pathogenesis of esophageal diseases.

The relationship between ambient ultraviolet radiation (UVR) and objectively measured personal UVR exposure dose is modified by season and latitude

Despite the widespread use of ambient ultraviolet radiation (UVR) as a proxy measure of personal exposure to UVR, the relationship between the two is not well-defined.

Helicobacter pylori infection and esophageal cancer risk: an updated meta-analysis

AIM

To clarify the association between Helicobacter pylori (H. pylori) infection and the risk of esophageal carcinoma through a meta-analysis of published data.

METHODS

Studies which reported the association between H. pylori infection and esophageal cancer published up to June 2013 were included. The odds ratios (ORs) and corresponding 95%CIs of H. pylori infection on esophageal cancer with respect to health control groups were evaluated. Data were extracted independently by two investigators and discrepancies were resolved by discussion with a third investigator. The statistical software, STATA (version 12.0), was applied to investigate heterogeneity among individual studies and to summarize the studies. A meta-analysis was performed using a fixed-effect or random-effect method, depending on the absence or presence of significant heterogeneity.

RESULTS

No significant association between H. pylori infection and esophageal squamous cell carcinoma (ESCC) risk was found in the pooled overall population (OR = 0.97, 95%CI: 0.76-1.24). However, significant associations between H. pylori infection and ESCC risk were found in Eastern subjects (OR = 0.66, 95%CI: 0.43-0.89). Similarly, cytotoxin-associated gene-A (CagA) positive strains of infection may decrease the risk of ESCC in Eastern subjects (OR = 0.77, 95%CI: 0.65-0.92), however, these associations were not statistically significant in Western subjects (OR = 1.26, 95%CI: 0.97-1.63). For esophageal adenocarcinoma (EAC) the summary OR for H. pylori infection and CagA positive strains of infection were 0.59 (95%CI: 0.51-0.68) and 0.56 (95%CI: 0.45-0.70), respectively.

CONCLUSION

H. pylori infection is associated with a decreased risk of ESCC in Eastern populations and a decreased risk of EAC in the overall population.

Hugl-1 induces apoptosis in esophageal carcinoma cells both in vitro and in vivo

AIM: To determine whether the human giant larvae homolog 1 gene (Hugl-1/Llg1/Lgl1) exerts tumor suppressor effects in esophageal cancer.

METHODS: We constructed a Hugl-1 expression plasmid, pEZ-M29-Hugl1, for gene transfection. We transfected the pEZ-M29-Hugl1 plasmid into Eca109 esophageal cancer cell lines with Lipofectamine 2000 to overexpress Hugl-1. Real-time reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting were performed to determine the effects of the plasmid on Hugl-1 expression. In vitro cell proliferation and apoptosis were examined separately by cell counting Kit-8 (CCK-8) assay, flow cytometry, and Western blotting before and after the transfection of the plasmid into Eca109 cells. Cell cycle distribution was assessed with flow cytometry. The effect of Hugl-1 overexpressing on tumor growth in vivo was performed with a xenograft tumor model in nude mice. Expression of Hugl-1 in xenograft tumor was analyzed by immunohistochemistry. The transferase-mediated dUTP nick end-labeling (TUNEL) technique was performed to detect and quantitate apoptotic cell.

RESULTS: The transfection efficiency was confirmed with real-time RT-PCR and Western blotting. Our results show that compared with control groups the mRNA levels and protein levels of Hugl-1 in pEZ-M29-Hugl1-treated group were remarkably increased (P < 0.05). The CCK-8 assay demonstrated that the growth of cells overexpressing Hugl-1 was significantly lower than control cells. Cell cycle distribution showed there was a G₀/G₁ cell cycle arrest in cells overexpressing Hugl-1 (64.09% ± 3.14% vs 50.32% ± 4.60%, 64.09% ± 3.14% vs 49.13% ± 2.24%). Annexin V-fluorescein isothiocyanate revealed that apoptosis was significantly increased in cells overexpressing Hugl-1 compared with control group (17.33% ± 4.76% vs 6.90% ± 1.61%, 17.33% ± 4.76% vs 6.27% ± 0.38%). Moreover, we found that Hugl-1 changes the level of the anti-apoptotic protein Bcl-2 and the pro-apoptotic protein Bax and the activation of both caspase-3 and caspase-9. With a TUNEL assay, we found that Hugl-1 markedly increased the apoptosis rate of Eca109 cells in vivo (60.50% ± 9.11% vs 25.00% ± 12.25%). It was shown that Hugl-1 represents a significantly more effective tumor suppressor gene alone in a xenograft tumor mouse model. This data suggest that Hugl-1 inhibited tumor growth and induced cell apoptosis in vivo.

CONCLUSION: These results suggest that Hugl-1 induces growth suppression and apoptosis in a human esophageal squamous cell carcinoma cell line both in vitro and in vivo.

Vitamin D and the epidemiology of upper gastrointestinal cancers: a critical analysis of the current evidence

Prospective analyses have yet to uncover a consistent relationship between vitamin D status and incidence and mortality of rarer cancers including esophageal and upper gastrointestinal cancers. We searched PubMed for literature about the epidemiology of upper gastrointestinal cancers and vitamin D published over the last decade and then summarized and critiqued the results of these studies in this review. The search yielded nine relevant studies. Overall, no consistent relationship was reported between serum vitamin D levels or a surrogate and upper gastrointestinal cancers. Four studies reported negative correlations between vitamin D status and upper gastrointestinal cancer, three reported positive correlations, one reported no correlation, and one reported both positive and negative correlations. No relationship has been established on the basis of epidemiologic data, but studies examining sun exposure consistently report an inverse association with esophageal cancer. The current literature is limited by the methods used to assess vitamin D status, lack of specific data for the types of upper gastrointestinal cancer, and failure to establish a temporal relationship between vitamin D status assessment and presentation of upper gastrointestinal cancer. It is possible that the lack of a consistent relationship is a consequence of inaccurate and imprecise assessment of vitamin D status.