Type 2 diabetes and late-onset Alzheimer's disease

BACKGROUND/AIMS

To confirm in a cohort recruited in 1999-2001 our finding in a cohort recruited in 1992-1994 relating type 2 diabetes (T2D) to late-onset Alzheimer's disease (LOAD).

METHODS

Participants were 1,488 persons aged 65 years and older without dementia at baseline from New York City. T2D was ascertained by self-report. Dementia and LOAD were ascertained by standard research procedures. Proportional hazard regression was used for analyses relating T2D and LOAD.

RESULTS

The prevalence of T2D was 17%. There were 161 cases of dementia and 149 cases of LOAD. T2D was related to dementia (hazard ratio = 1.7; 95% confidence interval = 1.4-2.9) and LOAD (1.6; 1.0-2.6) after adjustment for age, sex, education, ethnic group and apolipoprotein E ε4. This association was weaker when only AD - excluding cases of mixed dementia - was considered (hazard ratio = 1.3; 95% confidence interval = 0.8-2.2).

CONCLUSION

T2D is associated with LOAD. Cerebrovascular disease may be an important mediator.

Two novel BRM insertion promoter sequence variants are associated with loss of BRM expression and lung cancer risk

SWI/SNF (SWItch/sucrose non-fermentable) complexes are ATP-dependent chromatin remodeling enzymes critically involved in the regulation of multiple functions, including gene expression, differentiation, development, DNA repair, cell adhesion and cell cycle control. BRM, a key SWI/SNF complex subunit, is silenced in 15-20% of many solid tumors. As BRM-deficient mice develop 10-fold more tumors when exposed to carcinogens, BRM is a strong candidate for a cancer susceptibility gene. In this paper, we show that BRM is regulated by transcription, thus demonstrating that the promoter region is important for BRM expression. We sequenced the BRM promoter region, finding two novel promoter indel polymorphisms, BRM -741 and BRM -1321, that are in linkage disequilibrium (D'≥0.83). The variant insertion alleles of both polymorphisms produce sequence variants that are highly homologous to myocyte enhancer factor-2 (MEF2) transcription factor-binding sites; MEF2 is known to recruit histone deacetylases that silence BRM expression. Each polymorphic BRM insertion variant is found in ~20% of Caucasians, and each correlates strongly with the loss of protein expression of BRM, both in cancer cell lines (P=0.009) and in primary human lung tumor specimens (P=0.015). With such strong functional evidence, we conducted a case-control study of 1199 smokers. We found an increased risk of lung cancer when both BRM homozygous promoter insertion variants were present: adjusted odds ratio of 2.19 (95% confidence interval, 1.40-3.43). Thus, we here demonstrate a strong functional association between these polymorphisms and loss of BRM expression. These polymorphisms thus have the potential to identify a sub-population of smokers at greater lung cancer risk, wherein this risk could be driven by an aberrant SWI/SNF chromatin-remodeling pathway.

Neutralizing antibodies to 500 μg interferon beta-1b: 28-month results of the IDEAS extension trial

The Interferon Dose Escalation Assessment of Safety extension trial monitored neutralizing antibodies to interferon beta-1b in patients who currently or had previously received the double dose (500 μg) for up to 28 months. Fifteen patients entered the extension trial; five patients were neutralizing antibody-positive at the start of the trial. The present study demonstrates that when neutralizing antibodies develop in patients receiving higher doses of interferon beta-1b they tend to persist for a prolonged period, although neutralizing antibody titers tend to decrease over time and some patients may revert to neutralizing antibody-negative status.

Observation of efficacy and safety of converting the calcineurin inhibitor to sirolimus in renal transplant recipients with chronic allograft nephropathy

OBJECTIVE

The objective of this study was to evaluate the efficacy and safety of converting from a calcineurin inhibitor (CNI) to sirolimus among renal transplant recipients with chronic allograft nephropathy (CAN).

METHODS

In 16 patients with CAN, substituted sirolimus for CsA or FK506 and observed the incidence of acute rejection and changes in serum creatinine, triglycerides, cholesterol, blood uric acid, and peripheral blood leukocyte/platelet counts within 12 months. All recipients underwent an allograft biopsy before conversion. The targeted sirolimus level was 4-8 ug/L.

RESULTS

After conversion to sirolimus, the creatinine level of 7 cases decreased and the efficacy rate was (43.8%). No acute rejection occurred during the follow-up. The cases with hypercholesteremia increased from 3 to 7 after conversion; hypertriglyceridemia increased from 3 to 5; leukopenia occurred in 2; subnormal platelet counts increased from 2 to 3; and hyperuricemia increased from 6 to 7. Meanwhile, the average level of peripheral blood leukocytes obviously decreased in the first month, the average peripheral blood cholesterol increased over 12 months, but the average content of peripheral blood platelets, triglyceride and blood uric acid failed to display as statistic difference. Eight patients showed C4d deposition in peritubular capillary in graft tissue before conversion, 7 cases of whom showed no improvement in renal function. In 6 cases there was no C4d deposition in peritubular capillary in graft tissue. Only 2 of 6 cases showed no improvement in renal function. There were 6 patients whose creatinine level was <2.48 mg/dL before conversion, and renal function in 5 of them improved in a year after conversion. In contrast, among 10 patients whose blood creatinine level was >2.48 mg/dL, only 2 cases improved.

CONCLUSION

It is safe for patients with CAN to use substitute sirolimus for CNI; the incidence of acute rejection did not increase. In this study, 43.8% of patients showed improved renal function. The main adverse reactions after conversion to sirolimus were hypercholesteremia and decreased peripheral blood leukocytes. The serum creatinine level and the deposition of C4d in peritubular capillary were important factors influencing therapeutic efficacy.

Cluster analysis of risk factor genetic polymorphisms in Alzheimer's disease

Multiple genetic variants may contribute to the risk of developing Alzheimer's disease. We have analyzed polymorphisms in 9 genes to determine whether particular combinations would contribute to this risk. The genes were APOE, LDLr, CST3, CTSD, TNF, BACE1, MAPT, STH, eNOS, and TFCP2. Three risk groups for the disease were identified. Risk group I was younger, was heterozygous for the CST3 (GA), CTSD2936 (AG), TNF -308 (AG) genetic variants. Risk group II was older, was homozygous for the -427 APOE promoter polymorphism (TT), and heterozygous for the MAPT deletion and for the STH variant (QR). Group III had both the youngest and oldest subjects, were heterozygous for the -863 (AC) and -1031 (CT) TNF promoter polymorphisms. All three groups carried the APOE 4 allele and were heterozygous for both BACE1 polymorphisms. The control groups were carriers of the APOE 3 allele and were homozygous for the BACE1 genetic variants.

Impact of adenomatous polyposis coli (APC) tumor supressor gene in human colon cancer cell lines on cell cycle arrest by apigenin

This research assessed the importance of the adenomatous polyposis coli (APC) tumor suppressor mutation in the ability of apigenin to induce cell cycle arrest using HT29-APC cells, which contain inducible wild-type APC under the metallothionein promoter. HT29-GAL cells, containing beta-galactosidase (GAL), were included as control. Treatment with apigenin (0, 20, 40, 60, and 80 microM) for 48 h resulted in reduction in the cell number (P < 0.05) concurrent with flow cytometry results showing a dose-dependent accumulation of cells in the G2/M phase in both HT29-APC and HT29-GAL cells without ZnCl(2) treatment. Flow cytometric analysis showed an increase (P < 0.05) in the percentage of cells in G2/M when HT29-APC cells were treated with 80 microM apigenin for 120 h. This increase was not present in HT29-APC cells when treated with both 80 microM apigenin and 100 microM ZnCl(2) for 120 h. Western blot analysis verified the induction of APC protein expression in ZnCl(2)-treated HT29-APC cells but not in ZnCl(2)-treated HT29-GAL cells. Apigenin plus ZnCl(2) treatment increased the expression of APC protein in HT29-APC cells by 50 fold above expression observed with ZnCl(2) alone. Upon induction of the APC gene with ZnCl(2) in HT29-APC cells, the percentage of apoptotic cells increased significantly (P < 0.05) after 120-h treatment. Additionally, apigenin treatment (80 microM) further increased the percentage of apopototic HT29-APC following ZnCl(2) treatment to induce wild-type APC expression. These results suggest that APC dysfunction may be critical for apigenin to induce cell cycle arrest in human colon cancer cell lines and furthermore, apigenin enhances APC expression and apoptosis in cells with wild-type APC.

Combined therapy for rectal cancer in the elderly

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Background: Neoadjuvant or Adjuvant Chemoradiotherapy (CRT) plus surgery is the standard of care for treatment of Stage II/Stage III rectal cancer. Previous studies of practice patterns have evaluated SEER data using single dose chemotherapy as a surrogate for having ever been treated. No study to date has evaluated the use of CRT along with surgery to determine the ability of elderly patients with rectal cancer to complete prescribed therapy. Methods: A retrospective study of all patients treated for Stage II/III rectal cancer identified by Tumor Registrar from January 1, 1987 to June 1, 2006 at the Boston VAMC and Boston Medical Center were analyzed. Data was extracted from computerized records and paper charts. Statistical analysis was performed with SAS software. The primary endpoint was to determine if younger (<70 yr) and older (>=70yr) patients were equally likely to complete CRT and surgery without having a dose of chemotherapy or radiation reduced, held, or delayed. Secondary endpoints were to determine if older and younger age groups were equally likely to receive CRT and a multivariate analysis of factors (age, having received neoadjuvant therapy, number of comorbidities, stage of tumor) had an effect on these outcomes. Results: A total of 266 patients were identified and included in the study. The likelihood of completing CRT and surgery without a dose being held, delayed or reduced was statistically similar among patients age 70 and older (16.1%) as among younger patients (23.9%) (Chi-square 2.16 p=0.1414). However, older patients were far less likely (58.24%) than younger patients (76%) to receive CRT (Chi-square 8.79 p=0.003). A multivariate analysis of factors associated with completion of CRT without a dose being held, delayed or reduced identified only the number of comorbidities (one or more) OR=0.383 (95% CI 0.186–0.790) as statistically significant. In addition, multivariate analysis of factors associated with receiving CRT identified having received neoadjuvant therapy OR=5.397 (95% CI 2.303–12.60) and age >=70 OR=0.424 ( 95% CI 0.201–0.898) as statistically signficant. Conclusion: Elderly patients with rectal cancer are less likely to be prescribed CRT than younger patients. However, elderly patients who are prescribed to receive CRT appear to be able to tolerate the therapy as well as younger patients.

No significant financial relationships to disclose.

Functional interaction between APOE4 and LDL receptor isoforms in Alzheimer's disease

BACKGROUND

Multiple genes have been provisionally associated with Alzheimer's disease, including the coding polymorphisms in exons 8 and 13 in the low density lipoprotein receptor gene (LDLR), situated on chromosome 19p13.2.

METHODS

The sample groups consisted of 180 AD patients and 141 control spouses. We carried out genotyping of LDLR8 and LDLR13.

RESULTS

The LDLR8 GG genotype was common, found in 84% of the unaffected control subjects and 91% of the AD patients in our study. There was a ninefold elevation in risk associated with GG:CC versus A- and T- among APOE4+ subjects when compared with APOE4- subjects (odds ratio 9.3; 95% confidence interval 1.8 to 48.2). With the additional information on LDLR polymorphism, we defined an overall 12 fold elevation in risk for APOE4 in combination with LDLR GG:CC (11.9; 2.8 to 50.0; Fisher's exact test, p = 0.0002; standard power 0.999), compared with other subjects lacking all three of these polymorphisms.

CONCLUSION

These results imply a functional interaction between ApoE and LDL receptor proteins that determines risk for Alzheimer's disease.

Prostate stem cells and prostate cancer

Understanding prostate stem cells (PSCs) may provide insight for the design of therapeutics for prostate cancer. We have developed a quantitative in vivo colony-forming assay and have demonstrated that the Sca-1 antigen is present on the surface of a prostate cell subpopulation that possesses multiple stem cell properties. Immunofluorescent analysis demonstrates that Sca-1 is expressed by both basal and luminal cells in the proximal region of the adult prostate, but is not expressed by either lineage in more distal regions. The proximal region has been suggested as the PSC niche based on BrdU label-retention studies and the presence of distinct smooth-muscle cells that produce high levels of TGF-beta. Sca-1 is also expressed by nearly all cells within fetal prostate epithelial chords, suggesting Sca-1 may be conserved on PSCs throughout development. Malignant epithelial cells from TRAMP mice, as well as normal prostate cells with lentiviral-mediated alteration of the PTEN/AKT signaling pathway, give rise to PIN lesions and prostate cancer in vivo. Alteration of PTEN/AKT signaling in Sca-1-enriched PSCs also results in PIN lesions, suggesting that PSCs can serve as one target for prostate carcinogenesis.

Sole BCR-ABL inhibition is insufficient to eliminate all myeloproliferative disorder cell populations

Protein kinase inhibitors can be effective in treating selected cancers, but most suppress several kinases. Imatinib mesylate has been useful in the treatment of Philadelphia chromosome-positive chronic myelogenous leukemia and B cell acute lymphoblastic leukemia through the inhibition of BCR-ABL tyrosine kinase activity. Imatinib mesylate has also been shown to inhibit KIT, ARG, and platelet-derived growth factor receptors alpha and beta, and potentially other tyrosine kinases. We have produced a mutant allele of BCR-ABL (T315A) that is uniquely inhibitable by the small molecule 4-amino-1-tert-butyl-3-(1-naphthyl)pyrazolo[3,4-d]pyrimidine and used it to demonstrate that sole suppression of BCR-ABL activity was insufficient to eliminate BCR-ABL(+) KIT(+)-expressing immature murine myeloid leukemic cells. In contrast, imatinib mesylate effectively eliminated BCR-ABL(+) KIT(+)-expressing leukemic cells. In the cellular context of mature myeloid cells and Pro/Pre B cells that do not express KIT, monospecific BCR-ABL inhibition was quantitatively as effective as imatinib mesylate in suppressing cell growth and inducing apoptosis. These results suggest that the therapeutic effectiveness of small molecule drugs such as imatinib mesylate could be due to the inhibitor's ability to suppress protein kinases in addition to the dominant target.

Targeting oestrogen to kill the cancer but not the patient

The link between sex steroids and the development and growth of breast cancer has proved to be an invaluable clue for advances in the prevention and treatment of breast cancer. The identification of the oestrogen receptor (ER) not only allowed advances in the molecular endocrinology of oestrogen action, but also provided a target for antioestrogenic therapeutic agents. However, the application of long-term or indefinite treatment regimens has consequences for the breast cancer. New forms of resistance, based upon enhanced cellular survival networks independent of ER and the suppression of apoptotic mechanisms, develop and then evolve. Remarkably, low concentrations of oestrogen collapse survival pathways and induce apoptosis in completely antihormonally refractory breast cancer. However, recurrent oestrogen-stimulated disease is again sensitive to antihormonal therapy. The novel reapplication of the ER as a therapeutic target for apoptosis is emerging as a new strategy for the long-term targeted maintenance treatment of breast cancer, and in formulating a targeted strategy for endocrine independent cancer.

Functional expression of ATM gene carried by HSV amplicon vector in vitro and in vivo

Ataxia-telangiectasia (AT) is a human autosomal recessive disease with a pleiotropic phenotype characterized by cerebellar degeneration, immunodeficiency, premature aging, cancer predisposition, and radiation sensitivity. The gene mutated in AT, ATM (for AT-mutated), had been cloned and found to have ionizing radiation and oxidative stress-inducible kinase activity. No treatment can stop the progression of the disease. In this study, the complete open-reading frame of ATM cDNA was cloned into a Herpes simplex virus type-1 (HSV-1) amplicon vector (pTO-ATM), and the transduction of cultured AT cells was demonstrated by immunohistochemistry and Western blot analysis. Functional gene expression was evaluated by cell colony-forming assays following exposure to oxidative stress. The survival of AT cells with ATM gene transduction was about 100% higher compared to nontransduced cells after t-butyl hydroperoxide treatments. Next, the normal ATM gene expression in different regions of the rat brain was studied. Immunohistochemistry staining demonstrated weak endogenous ATM protein expression in neurons of the caudate-putamen, with significantly higher levels of expression detected in neurons in other brain regions. Exogenous ATM gene expression from pTO-ATM after viral transduction in the caudate-putamen of the adult rat was examined. At 3 days after injection of the pTO-ATM viral vector, abundant positive ATM staining of the neurons was found at the injection sites, in comparison to the controls. These data demonstrate that the relatively large ATM cDNA can be transduced and expressed in vitro and in vivo from an HSV amplicon viral vector. These data provide initial evidence that the replacement of the ATM gene into the cells of AT patients might be possible some day.