The Kinome of Human Alveolar Type II and Basal Cells, and Its Reprogramming in Lung Cancer.

The discovery of mutant tyrosine kinases as oncogenic drivers of lung adenocarcinomas has changed the basic understanding of lung cancer development and therapy. Yet, expressed kinases (kinome) in lung cancer progenitor cells, as well as whether kinase expression and the overall kinome changes or is reprogrammed upon transformation, is incompletely understood. We hypothesized that the kinome differs between lung cancer progenitor cells, alveolar type II cells (ATII), and basal cells (BC) and that their respective kinomes undergo distinct lineage-specific reprogramming to adenocarcinomas and squamous cell carcinomas upon transformation. We performed RNA sequencing on freshly isolated human ATII, BC, and lung cancer cell lines to define the kinome in nontransformed cells and transformed cells. Our studies identified a unique kinome for ATII and BC and changes in their kinome upon transformation to their respective carcinomas.

Cigarette Smoke Induces Human Epidermal Receptor 2-Dependent Changes in Epithelial Permeability.

The airway epithelium constitutes a protective barrier against inhaled insults, such as viruses, bacteria, and toxic fumes, including cigarette smoke (CS). Maintenance of bronchial epithelial integrity is central for airway health, and defective epithelial barrier function contributes to the pathogenesis of CS-mediated diseases, such as chronic obstructive pulmonary disease. Although CS has been shown to increase epithelial permeability, current understanding of the mechanisms involved in CS-induced epithelial barrier disruption remains incomplete. We have previously identified that the receptor tyrosine kinase human epidermal receptor (HER) 2 growth factor is activated by the ligand neuregulin-1 and increases epithelial permeability in models of inflammatory acute lung injury. We hypothesized that CS activates HER2 and that CS-mediated changes in barrier function would be HER2 dependent in airway epithelial cells. We determined that HER2 was activated in whole lung, as well as isolated epithelial cells, from smokers, and that acute CS exposure resulted in HER2 activation in cultured bronchial epithelial cells. Mechanistic studies determined that CS-mediated HER2 activation is independent of neuregulin-1 but required upstream activation of the epidermal growth factor receptor. HER2 was required for CS-induced epithelial permeability as knockdown of HER2 blocked increases in permeability after CS. CS caused an increase in IL-6 production by epithelial cells that was dependent on HER2-mediated extracellular signal-regulated kinases (Erk) activation. Finally, blockade of IL-6 attenuated CS-induced epithelial permeability. Our data indicate that CS activates pulmonary epithelial HER2 and that HER2 is a central mediator of CS-induced epithelial barrier dysfunction.

HER2 activation results in ß-catenin-dependent changes in pulmonary epithelial permeability.

The receptor tyrosine kinase human epidermal growth factor receptor-2 (HER2) is known to regulate pulmonary epithelial barrier function; however, the mechanisms behind this effect remain unidentified. We hypothesized that HER2 signaling alters the epithelial barrier through an interaction with the adherens junction (AJ) protein ß-catenin, leading to dissolution of the AJ. In quiescent pulmonary epithelial cells, HER2 and ß-catenin colocalized along the lateral intercellular junction. HER2 activation by the ligand neuregulin-1 was associated with tyrosine phosphorylation of ß-catenin, dissociation of ß-catenin from E-cadherin, and decreased E-cadherin-mediated cell adhesion. All effects were blocked with the HER2 inhibitor lapatinib. ß-Catenin knockdown using shRNA significantly attenuated neuregulin-1-induced decreases in pulmonary epithelial resistance in vitro. Our data indicate that HER2 interacts with ß-catenin, leading to dissolution of the AJ, decreased cell-cell adhesion, and disruption of the pulmonary epithelial barrier.

Bioinformatics-driven discovery of rational combination for overcoming EGFR-mutant lung cancer resistance to EGFR therapy.

MOTIVATION: Non-small-cell lung cancer (NSCLC) is the leading cause of cancer death in the United States. Targeted tyrosine kinase inhibitors (TKIs) directed against the epidermal growth factor receptor (EGFR) have been widely and successfully used in treating NSCLC patients with activating EGFR mutations. Unfortunately, the duration of response is short-lived, and all patients eventually relapse by acquiring resistance mechanisms. RESULT: We performed an integrative systems biology approach to determine essential kinases that drive EGFR-TKI resistance in cancer cell lines. We used a series of bioinformatics methods to analyze and integrate the functional genetics screen and RNA-seq data to identify a set of kinases that are critical in survival and proliferation in these TKI-resistant lines. By connecting the essential kinases to compounds using a novel kinase connectivity map (K-Map), we identified and validated bosutinib as an effective compound that could inhibit proliferation and induce apoptosis in TKI-resistant lines. A rational combination of bosutinib and gefitinib showed additive and synergistic effects in cancer cell lines resistant to EGFR TKI alone. CONCLUSIONS: We have demonstrated a bioinformatics-driven discovery roadmap for drug repurposing and development in overcoming resistance in EGFR-mutant NSCLC, which could be generalized to other cancer types in the era of personalized medicine. AVAILABILITY AND IMPLEMENTATION: K-Map can be accessible at: http://tanlab.ucdenver.edu/kMap. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Bronchoalveolar lavage neuregulin-1 is elevated in acute lung injury and correlates with inflammation.

Shedding of neuregulin (NRG)-1 from the pulmonary epithelium leads to activation of the epithelial human epidermal growth factor receptor (HER)2 receptor, increased pulmonary epithelial permeability and acute lung injury (ALI). We sought to determine whether NRG-1 was detectable and elevated in bronchoalveolar lavage (BAL) and plasma from patients with ALI compared with controls and to determine whether a correlation exists between NRG-1 and inflammation and outcome in ALI. Matched BAL and plasma samples were obtained from 23 ALI patients requiring intubation and mechanical ventilation. Control patients (n=5) included healthy volunteers. NRG-1 and indices of inflammation were measured in BAL and plasma via ELISA. The mean±sd BAL NRG-1 concentration in ALI patients was 187.0±21.35 pg·mL(-1) compared with 85.50±9.2 pg·mL(-1) in controls (p=0.001). Increased BAL NRG-1 was associated with markers of inflammation, and inversely correlated with ventilator-free days (VFDs; r= -0.51, p=0.015). Plasma NRG-1 was elevated in ALI patients compared with controls (611.7±354.2 versus 25.17±19.33 pg·mL(-1), p<0.001) and inversely correlated with VFDs (r= -0.51, p=0.04). These results confirm shedding of NRG-1 in ALI and suggest that the NRG-1-HER2 pathway is active in patients with ALI.

Maternal obesity affects gene expression and cellular development in fetal brains.

OBJECTIVES: Female rat neonates reared on a high carbohydrate (HC) milk formula developed chronic hyperinsulinemia and adult-onset obesity (HC phenotype). Furthermore, we have shown that fetal development in the HC intrauterine environment (maternal obesity complicated with hyperinsulinemia, hyperleptinemia, and increased levels of proinflammatory markers) resulted in increased levels of serum insulin and leptin in term HC fetuses and the spontaneous transfer of the HC phenotype to the adult offspring. The objectives of this study are to identify changes in global gene expression pattern and cellular development in term HC fetal brains in response to growth in the adverse intrauterine environment of the obese HC female rat. METHODS: GeneChip analysis was performed on total RNA obtained from fetal brains for global gene expression studies and immunohistochemical analysis was performed on fetal brain slices for investigation of cellular development in term HC fetal brains. RESULTS: Gene expression profiling identified changes in several clusters of genes that could contribute to the transfer of the maternal phenotype (chronic hyperinsulinemia and adult-onset obesity) to the HC offspring. Immunohistochemical analysis indicated diminished proliferation and neuronal maturation of stem-like cells lining the third ventricle, hypothalamic region, and the cerebral cortex in HC fetal brains. DISCUSSION: These results suggest that maternal obesity during pregnancy could alter the developmental program of specific fetal brain cell-networks. These defects could underlie pathologies such as metabolic syndrome and possibly some neurological disorders in the offspring at a later age.

A high-fat diet containing whole walnuts (Juglans regia) reduces tumour size and growth along with plasma insulin-like growth factor 1 in the transgenic adenocarcinoma of the mouse prostate model.

Prostate cancer (PCa) has been linked to fat intake, but the effects of both different dietary fat levels and types remain inconsistent and incompletely characterised. The effects on PCa in the transgenic adenocarcinoma of the mouse prostate (TRAMP) cancer model of an elevated fat (20 % of energy as fat) diet containing 155 g of whole walnuts were compared to those of an elevated fat (20 % of energy as soyabean oil) diet with matched macronutrients, tocopherols as well as a low-fat (8 % of energy as soyabean oil) diet. Mice, starting at 8 weeks of age, consumed one of the three different diets ad libitum; and prostates, livers and blood were obtained after 9, 18 or 24 weeks of feeding. No differences were observed in whole animal growth rates in either high-fat (HF) diet group, but prostate tumour weight and growth rate were reduced in the walnut diet group. Walnut diet group prostate weight, plasma insulin-like growth factor 1, resistin and LDL were lower at 18 weeks, while no statistically significant prostate weight differences by diet were seen at 9 or 24 weeks. Multiple metabolites in the livers differed by diet at 9 and 18 weeks. The walnut diet's beneficial effects probably represent the effects of whole walnuts' multiple constituents and not via a specific fatty acid or tocopherols. Moreover, as the two HF diets had dissimilar effects on prostate tumour growth rate and size, and yet had the same total fat and tocopherol composition and content, this suggests that these are not strongly linked to PCa growth.

α-Tocopherol Pharmacokinetics in Adults with Cystic Fibrosis: Benefits of Supplemental Vitamin C Administration.

BACKGROUND: Numerous abnormalities in cystic fibrosis (CF) could influence tocopherol absorption, transportation, storage, metabolism and excretion. We hypothesized that the oxidative distress due to inflammation in CF increases vitamin E utilization, which could be positively influenced by supplemental vitamin C administration. METHODS: Immediately before and after receiving vitamin C (500 mg) twice daily for 3.5 weeks, adult CF patients (n = 6) with moderately advanced respiratory tract (RT) disease consumed a standardized breakfast with 30% fat and a capsule containing 50 mg each hexadeuterium (d6)-α- and dideuterium (d2)-γ-tocopheryl acetates. Blood samples were taken frequently up to 72 h; plasma tocopherol pharmacokinetics were determined. During both trials, d6-α- and d2-γ-tocopherols were similarly absorbed and reached similar maximal plasma concentrations ~18-20 h. As predicted, during vitamin C supplementation, the rates of plasma d6-α-tocopherol decline were significantly slower. CONCLUSIONS: The vitamin C-induced decrease in the plasma disappearance rate of α-tocopherol suggests that vitamin C recycled α-tocopherol, thereby augmenting its concentrations. We conclude that some attention should be paid to plasma ascorbic acid concentrations in CF patients, particularly to those individuals with more advanced RT inflammatory disease and including those with severe exacerbations.

Circadian disruption in lung cancer.

Despite major developments in lung cancer investigations and the progress of innovative oncology treatments in recent decades, lung cancer continues to be the predominant cause of cancer-related mortality globally, with over a million deaths each year. This highlights the urgent need to develop a deeper understanding of the current state of cancer care. At the environmental and cellular levels, circadian rhythms are closely associated with living organisms. In humans, the suprachiasmatic nucleus is the principal circadian pacemaker. Circadian gene feedback loops regulate the clock, connecting peripheral tissue metabolism, cell proliferation, DNA repair, and cell death to energy homeostasis, physical activity, and neurohormonal regulation at the organismal level. Endogenous circadian homeostasis has been frequently disturbed in modern civilizations, resulting in a higher risk of many disorders, including lung cancer. Despite major developments in lung cancer investigations and the progress of innovative oncology treatments in recent decades, lung cancer continues to be the predominant cause of cancer-related mortality globally, with over a million deaths each year. This highlights the urgent need to develop a deeper understanding of the current state of cancer care. At the environmental and cellular levels, circadian rhythms are closely associated with living organisms. In humans, the suprachiasmatic nucleus is the principal circadian pacemaker. Circadian gene feedback loops regulate the clock, connecting peripheral tissue metabolism, cell proliferation, DNA repair, and cell death to energy homeostasis, physical activity, and neurohormonal regulation at the organismal level. Endogenous circadian homeostasis has been frequently disturbed in modern civilizations, resulting in a higher risk of many disorders, including lung cancer. The mammalian circadian clock controls metabolism and cell division, and disruption of these processes may lead to cancer pathogenesis. Furthermore, circadian disturbance has recently been identified as a self-regulating cancer risk factor and is listed as a carcinogen. The theory that both somatic and systemic disturbances of circadian rhythms are related to a higher risk of lung cancer development and poor prognosis is addressed in this study. The chronotherapy principles hold much more promise for enhancing the lung cancer care options currently available. Developing a better understanding of the molecular interactions that control the physiological equilibrium between both the circadian rhythm and the cycle of cell division could significantly influence the development of novel treatments for lung cancer and other diseases.

Modulation of ozone-sensitive genes in alpha-tocopherol transfer protein null mice.

Alpha-tocopherol transfer protein (ATTP) null mice (ATTP-/-) have a systemic alpha-tocopherol (AT) deficiency, with their lung AT levels being < 10% of those in AT-replete ATTP(+/+) mice when fed a standard rodent chow diet. ATTP(+/+) and ATTP(-/-) mice (4 wk old male mice, n = 16 per group) were fed a standard diet (35 IU AT/kg diet) for 8-12 wk, exposed 6 h/day for 3 days to either to O(3) (0.5 ppm) or filtered air, then sacrificed. No significant differences in plasma or lung AT concentrations were observed in response to this level of O(3) exposure. Lung genomic responses of the lungs to O(3) were determined using Affymetrix 430A 2.0 arrays containing over 22,600 probe sets representing 14,000 well-characterized mouse genes. As compared with filtered air exposure, O(3) exposure resulted in 99 genes being differentially expressed in ATTP(-/-) mice, as compared to 52 differentially expressed genes in ATTP(+/+) mice. The data revealed an O(3)-induced upregulation of genes related to cell proliferation/DNA repair and inflammatory-immune responses in both ATTP(+/+) and ATTP(-/-) mice, with the expression of 22 genes being common to both, whereas 30 and 77 genes were unique to ATTP(+/+) and ATTP(-/-) mice, respectively. The expressions of O(3) sensitive genes-Timp1, Areg, Birc5 and Tnc-were seen to be further modulated by AT status. The present study reveals AT modulation of adaptive response of lung genome to O(3) exposure.

Mice lacking alpha-tocopherol transfer protein gene have severe alpha-tocopherol deficiency in multiple regions of the central nervous system.

Ataxia with vitamin E deficiency is caused by mutations in alpha-tocopherol transfer protein (alpha-TTP) gene and it can be experimentally generated in mice by alpha-TTP gene inactivation (alpha-TTP-KO). This study compared alpha-tocopherol (alpha-T) concentrations of five brain regions and of four peripheral organs from 5 months old, male and female, wild-type (WT) and alpha-TTP-KO mice. All brain regions of female WT mice contained significantly higher alpha-T than those from WT males. alpha-T concentration in the cerebellum was significantly lower than that in other brain regions of WT mice. These sex and regional differences in brain alpha-T concentrations do not appear to be determined by alpha-TTP expression which was undetectable in all brain regions. All the brain regions of alpha-TTP-KO mice were severely depleted in alpha-T. The concentration of another endogenous antioxidant, total glutathione, was unaffected by gender but was decreased slightly but significantly in most brain regions of alpha-TTP-KO mice. The results show that both gender and the hepatic alpha-TTP, but not brain alpha-TTP gene expression are important in determining alpha-T concentrations within the brain. Interestingly, functional abnormality (ataxia) develops only very late in alpha-TTP-KO mice in spite of the severe alpha-tocopherol deficiency in the brain starting at an early age.

A dose-response study on the effects of purified lycopene supplementation on biomarkers of oxidative stress.

OBJECTIVE: While tomato product supplementation, containing antioxidant carotenoids, including lycopene, decreases oxidative stress, the role of purified lycopene as an antioxidant remains unclear. Thus, we tested the effects of different doses of purified lycopene supplementation on biomarkers of oxidative stress in healthy volunteers. METHODS: This was a double-blind, randomized, placebo-controlled trial, examining the effects of 8-week supplementation of purified lycopene, on plasma lycopene levels, biomarkers of lipid peroxidation {LDL oxidizability, malondialdehyde & hydroxynonenals (MDA & HNE), urinary F(2)-isoprostanes}, and markers of DNA damage in urine and lymphocytes. Healthy adults (n = 77, age > or = 40 years), consumed a lycopene-restricted diet for 2 weeks, and were then randomized to receive 0, 6.5, 15, or 30 mg lycopene/day for 8 weeks, while on the lycopene-restricted diet. Blood and urine samples were collected at the beginning and end of Week 2 of lycopene-restricted diet, and at end of Week 10 of the study. RESULTS: Independent of the dose, plasma lycopene levels significantly increased in all lycopene supplemented groups versus placebo (p < 0.05). ANOVA revealed a significant decrease in DNA damage by the comet assay (p = 0.007), and a significant decrease in urinary 8-hydroxy deoxoguanosine (8-OHdG) at 8 weeks versus baseline (p = 0.0002), with 30 mg lycopene/day. No significant inter- or intra-group differences were noted for glucose, lipid profile, or other biomarkers of lipid peroxidation at any dose/time point. CONCLUSIONS: Thus, purified lycopene was bioavailable and was shown to decrease DNA oxidative damage and urinary 8-OHdG at the high dose.

Genome-wide screening of alpha-tocopherol sensitive genes in heart tissue from alpha-tocopherol transfer protein null mice (ATTP(-/-)).

Alpha-tocopherol transfer protein (ATTP) null mice (ATTP(-/-)) have a systemic deficiency of alpha-tocopherol (AT). The heart AT levels of ATTP(-/-) are <10% of those in ATTP(+/+) mice. The genomic responses of heart to AT deficiency were determined in 3 months old male ATTP(-/-) mice and compared with their ATTP(+/+) littermate controls using Affymetrix 430A 2.0 high density oligonucleotide arrays. Differential analysis of approximately 13000 genes identified repression of genes related to immune system and activation of genes related to lipid metabolism and inflammation with no significant change in the expression of classical antioxidant genes (catalase, superoxide dismutase, glutathione peroxidase) in ATTP(-/-) as compared to ATTP(+/+) mice. The present data identifies novel classes of AT sensitive genes in heart tissue.

Genome wide responses of murine lungs to dietary alpha-tocopherol.

Alpha-tocopherol (alpha-T) may affect biological processes by modulating mRNA concentrations. This study screened the responses of approximately 15,000 lung mRNAs to dietary alpha-T in mice. The lung was chosen as the target organ because it is subjected to cyclical variations in oxidant and inflammatory stressors and alpha-T has been implicated in their modulations. The analysis identified approximately 400 mRNAs sensitive to alpha-T status of lungs determined by dietary alpha-T. The female lung transcriptome appears to be more sensitive to the alpha-T status than that of the male lungs. Here, we focus on the induction of 13 cytoskeleton genes by dietary alpha-T because they were similarly induced in the male and the female lungs. Their inductions were confirmed by quantitative-real-time-polymerase chain reaction (qRT-PCR). Immunohistochemical analyses of three of the encoded proteins suggest that they are expressed in lung vasculature and alveolar regions. The data suggest that the lung alpha-T status may modulate cytoarchitecture of lungs.

Inhibition of the hexosamine biosynthetic pathway promotes castration-resistant prostate cancer.

The precise molecular alterations driving castration-resistant prostate cancer (CRPC) are not clearly understood. Using a novel network-based integrative approach, here, we show distinct alterations in the hexosamine biosynthetic pathway (HBP) to be critical for CRPC. Expression of HBP enzyme glucosamine-phosphate N-acetyltransferase 1 (GNPNAT1) is found to be significantly decreased in CRPC compared with localized prostate cancer (PCa). Genetic loss-of-function of GNPNAT1 in CRPC-like cells increases proliferation and aggressiveness, in vitro and in vivo. This is mediated by either activation of the PI3K-AKT pathway in cells expressing full-length androgen receptor (AR) or by specific protein 1 (SP1)-regulated expression of carbohydrate response element-binding protein (ChREBP) in cells containing AR-V7 variant. Strikingly, addition of the HBP metabolite UDP-N-acetylglucosamine (UDP-GlcNAc) to CRPC-like cells significantly decreases cell proliferation, both in-vitro and in animal studies, while also demonstrates additive efficacy when combined with enzalutamide in-vitro. These observations demonstrate the therapeutic value of targeting HBP in CRPC.

Hypolipidaemic and antioxidant effect of Enicostemma littorale Blume aqueous extract in cholesterol fed rats.

Enicostemma littorale aqueous extract (1.5 g/100 g body weight/day, p.o.) was administered to rats along with hypercholesterolaemic diet for 6 weeks and the hypolipidaemic and antioxidant effect was evaluated. Feeding cholesterol increased serum cholesterol, serum triglycerides, LDL, VLDL and decreased HDL levels as compared to normal diet fed rats. Enicostemma littorale treatment increased HDL levels and decreased serum cholesterol, triglyceride, LDL, VLDL, LDL/HDL ratio. In addition, treatment with the extract showed a decrease in activities of erythrocyte catalase, superoxide dismutase and lipid peroxidation levels, with an increase in reduced glutathione levels as compared to cholesterol fed untreated rats. Liver and kidney cholesterol levels and triglyceride levels were also decreased in Enicostemma littorale treated rats. Hepatic HMG CoA reductase activity was significantly reduced in the extract treated hypercholesterolemic rats. Lovastatin was used as a reference drug. The hypolipidaemic and antioxidant effect of Enicostemma littorale aqueous extract in cholesterol fed rats is being reported for the first time.

Glucose lowering effect of aqueous extract of Enicostemma littorale Blume in diabetes: a possible mechanism of action.

Diabetes mellitus is a chronic metabolic disorder characterized by hyperglycemia. Enicostemma littorale Blume is a small herb and recently we have reported its blood glucose lowering potential in alloxan induced diabetic rats. A single dose of aqueous extract of E. littorale (15 g dry plant equivalent extract per kg) had shown significant increase in the serum insulin levels in alloxan-induced diabetic rats at 8 h. The insulinotropic action of aqueous extract of E. littorale was further investigated using rat pancreatic islets. Extract has the potential to enhance glucose-induced insulin release at 11.1 mM glucose from isolated rat pancreatic islets and was partially able to reverse the effect of diazoxide (0.25 mM). Incubation with Ca(2+) chelator (EGTA) and Ca(2+) channel blocker (nimodipine) did not affect the glucose-induced insulin release augmented by the extract. Above results suggest the glucose lowering effect of aqueous extract of E. littorale to be associated with potentiation of glucose-induced insulin release through K(+)-ATP channel dependent pathway but did not require Ca(2+) influx.

Contributions of KRAS and RAL in non-small-cell lung cancer growth and progression.

INTRODUCTION: KRAS mutations are poor prognostic markers for patients with non-small-cell lung cancer (NSCLC). RALA and RALB GTPases lie downstream of RAS and are implicated in RAS-mediated tumorigenesis. However, their biological or prognostic role in the context of KRAS mutation in NSCLC is unclear. METHODS: Using expression analysis of human tumors and a panel of cell lines coupled with functional in vivo and in vitro experiments, we evaluated the prognostic and functional importance of RAL in NSCLC and their relationship to KRAS expression and mutation. RESULTS: Immunohistochemical (N = 189) and transcriptomic (N = 337) analyses of NSCLC patients revealed high RALA and RALB expression was associated with poor survival. In a panel of 14 human NSCLC cell lines, RALA and RALB had higher expression in KRAS mutant cell lines whereas RALA but not RALB activity was higher in KRAS mutant cell lines. Depletion of RAL paralogs identified cell lines that are dependent on RAL expression for proliferation and anchorage independent growth. Overall, growth of NSCLC cell lines that carry a glycine to cystine KRAS mutation were more sensitive to RAL depletion than those with wild-type KRAS. The use of gene expression and outcome data from 337 human tumors in RAL-KRAS interaction analysis revealed that KRAS and RAL paralog expression jointly impact patient prognosis. CONCLUSION: RAL GTPase expression carries important additional prognostic information to KRAS status in NSCLC patients. Simultaneously targeting RAL may provide a novel therapeutic approach in NSCLC patients harboring glycine to cystine KRAS mutations.

Evaluation of long-term vitamin E insufficiency or excess on bone mass, density, and microarchitecture in rodents.

High dietary α-tocopherol levels reportedly result in osteopenia in growing rats, whereas α-tocopherol deficiency in α-tocopherol transfer protein-knockout (α-TTP-KO) mice results in increased cancellous bone mass. Because osteoporosis is a disease associated primarily with aging, we hypothesized that age-related bone loss would be attenuated in α-TTP-KO mice. Cancellous and cortical bone mass and microarchitecture were assessed using dual-energy X-ray absorptiometry and micro-computed tomography in 2-year-old α-TTP-KO and wild-type (WT) male and female mice fed dl-α-tocopherol acetate. In contrast to our expectations, differences in cancellous bone were not detected between WT and α-TTP-KO mice of either gender, and α-TTP-KO males had lower (p<0.05) cortical bone mass than WT males. We therefore evaluated bone mass, density, and microarchitecture in proximal femur of skeletally mature (8.5-month-old) male Sprague-Dawley rats fed diets containing low (15 IU/kg diet), adequate (75 IU/kg diet), or high (500 IU/kg diet) dl-α-tocopherol acetate for 13 weeks. Low dietary α-tocopherol did not increase bone mass. Furthermore, no reductions in cancellous or cortical bone mass were detected with high dietary α-tocopherol. Failure to detect increased bone mass in aged α-TTP-KO mice or bone changes in skeletally mature rats fed either low or high levels of α-tocopherol does not support the hypothesis that α-tocopherol has a negative impact on bone mass, density, or microarchitecture in rodents.