Haploinsufficiency of GRN, the gene encoding progranulin (PGRN), causes frontotemporal lobar degeneration (FTLD), the second most common cause of early-onset dementia. Receptor-mediated lysosomal targeting has been shown to regulate brain PGRN levels, and complete deficiency of PGRN is a direct cause of neuronal ceroid lipofuscinosis (NCL), a lysosomal storage disease. Here we show that the lysosomal cysteine protease cathepsin L (Cat L) can mediate the proteolytic cleavage of intracellular PGRN into poly-granulin and granulin fragments. Further, PGRN and Cat L co-localize in lysosomes of HEK293 cells, iPSC-derived neurons and human cortical neurons from human postmortem tissue. These data identify Cat L as a key intracellular lysosomal PGRN protease, and provides an intriguing new link between lysosomal dysfunction and FTLD.

BACKGROUND: Evidence of the chemopreventive effects of the dietary antioxidants alpha-tocopherol (vitamin E) and l-selenomethionine (selenium) comes from secondary analysis of two phase III clinical trials that found treatment with these antioxidants reduced the incidence of prostate cancer. To determine the effects of selenium and vitamin E in blood and prostate tissue, we undertook a preoperative feasibility study complementary to the currently ongoing Selenium and Vitamin E Cancer Prevention Trial. METHODS: Forty-eight patients with clinically localized prostate cancer enrolled on this 2 x 2 factorial design study were randomized to take selenium, vitamin E, both, or placebo for 3 to 6 weeks before prostatectomy. Sera were collected from patients before and after dietary supplementation. Thirty-nine patients were evaluable, and 29 age-matched disease-free men served as controls. Mass profiling of lipophilic serum proteins of lower molecular weight (2-13.5 kDa) was conducted, and mass spectra data were analyzed using custom-designed software. RESULTS: Weighted voting analyses showed a change in sera classification from cancerous to healthy for some patients with prostate cancer after dietary intervention. ANOVA analysis showed significantly different treatment effects on prediction strength changes among the four groups at a 95% confidence level. Eliminating an outlying value and performing post hoc analysis using Fisher's least significant difference method showed that effects in the group treated with the combination were significantly different from those of the other groups. CONCLUSION: In sera from patients with prostate cancer, selenium and vitamin E combined induced statistically significant proteomic pattern changes associated with prostate cancer-free status.

PURPOSE: Various strategies have recently emerged to improve the diagnostic prediction of prostate cancer (CaP). One such strategy includes the mass profiling of serum protein fractions selectively adsorbed onto chemically modified probes. In the current study we further validated this approach, while offering a more versatile, less expensive and yet equally predictive alternative to existing technologies. MATERIALS AND METHODS: A solid core lipophilic C-18 resin was used to extract and enrich the low molecular weight protein fraction from patient serum for further analysis by mass spectrometry. Mass spectra generated from a 48 patient training set were data mined using multivariate analysis to identify diagnostically significant protein peaks. These peaks were then used to test a blinded study set comprising 168 patients with common statistical algorithms and commercially available software packages. RESULTS: A total of 36 peaks generated from the training set were used to test the combined set of 168 serum samples obtained from 98 healthy individuals and 70 patients with CaP. We report a sensitivity of 94.1% and a specificity of 99.0% with 1 false-positive, 4 false-negative and 5 nondiagnosed cases. CONCLUSIONS: Our results further indicate that mass profiling of serological proteins provides a means for the accurate detection of CaP. In addition, our approach was found to be superior to chip based protocols, generating rich, sharp, highly reproducible spectra attainable in a high throughput manner and at minimal cost. This technique is also scaleable for subsequent protein characterization using multidimensional protein identification technologies. Finally, analyses of mass spectra with commercially available statistical applications was found to be highly effective in generating highly discriminatory m/z values for CaP diagnosis.

An enzyme previously identified as alpha-methylacyl-CoA racemase (AMACR) is overexpressed in high-grade prostatic intraepithelial neoplasia and in a majority (60-100%) of prostate cancers (CaPs) as compared with normal and benign hyperplastic lesions of the prostate, where it is minimally expressed. This enzyme is required for the beta-oxidation of branched-chain fatty acids, which include phytanic acid and its alpha-oxidation product, pristanic acid. Interestingly, there is an established correlation between CaP risk and the consumption of dairy and beef products, which also contain marked quantities of these two phytols. In this context, it has also been reported that sex steroids influence lipogenesis through the induction of fatty acid synthase in CaP-derived cell lines and CaP tissues. These findings indicate a potential role for AMACR and the possible influence of sex steroids in both the early development and subsequent progression of CaP. Despite the recent interest in AMACR as a histological marker for CaP, little is known about the regulation of this enzyme and its role in CaP development. To identify potential AMACR-regulating factors, we treated LNCaP cells (an androgen-responsive CaP-derived cell line) and NPrEC cells (a normal prostate basal epithelial cell line) with increasing concentrations of pristanic acid, phytanic acid, 5alpha-dihydrotestosterone, and 17beta-estradiol. Neither the biologically potent androgen 5alpha-dihydrotestosterone nor 17beta-estradiol had any apparent effect on AMACR expression at the protein or transcriptional levels in either cell line. Conversely, pristanic acid and, to a much lesser extent, phytanic acid markedly increased AMACR protein levels selectively in the LNCaP cell line, but not the NPrEC cell line. However, no change was measured at the transcriptional level in either cell line. AMACR is therefore significantly increased at the protein level in CaP cells, through what appears to be the stabilizing effect of the same fatty acids that are present at appreciable concentrations in beef and dairy products, which have been associated with CaP risk. Our findings therefore provide a link between the consumption of dietary fatty acids and the enhanced expression of AMACR, an enzyme that may play an important role in genesis and progression of CaP.