Modestly Increased Incidence of Ketosis in Caloric Restriction Does not Significantly Alter the Effects of Caloric Restriction

OBJECTIVES

Caloric restriction (CR) has been shown to slow the aging processes in a number of preclinical studies and reduces expression of aging-associated biomarkers in human trials. We hypothesized that CR would lead to increased incidence of ketosis and that ketosis in CR individuals would alter the aging-protective effects of CR or biomarkers thereof.

DESIGN/SETTING/PARTICIPANTS

We analyzed data from the "Comprehensive Assessment of Long-Term Effects of Reducing Intake of Energy (CALERIE, Phase 2)" Public Use Database available at calerie.duke.edu. In this study, non-obese adults between the ages of 21 and 50 were randomized to 25% CR or control (ad lib) diet groups and extensively monitored for two years. Given our focus on the effect of caloric restriction on ketosis, individuals with detectible ketones during the baseline visit (pre-randomization) and those with missing data for ketone testing were excluded from the analysis, leaving 71 control and 117 CR participants.

MEASUREMENTS

We analyzed the incidence of ketosis as well as ketosis free survival in control and CR participants and assessed the effect of ketosis on a number of clinical lab values, functional assessments, and participant survey data related to aging biology.

RESULTS

We report that CR was associated with modestly increased incidence of ketosis (4.4% in CR vs 1.9% in control), though CR-associated changes in T3, VO2, SUMPT-WT (weight normalized composite strength score - peak torque), physical functioning, and general health did not appear to be altered by the presence or absence of ketosis. Additional observations of interest include: 1) striking patterns of biomarker expression changes (MCP-1, TNFα, TGF-β1, GH) in both the control and CR participants between the baseline visit and the 24-month post-randomization visit and 2) pro-growth/anti-inflammatory baseline (pre-randomization) biomarker expression profile in CR individuals that later test ketone positive relative to other CR individuals.

CONCLUSIONS

CR modestly increases the incidence of ketosis in healthy adults, yet the increase in ketosis in CR patients did not significantly affect the aging-protective effects of CR. However, given the relatively small number of participants who were ketone positive, further investigation in larger study cohorts is still required for definitive conclusions.

Differences in characteristics of men with localised prostate cancer who demonstrate low, intermediate or high prostate-specific antigen velocity

BACKGROUND

Current diagnostic tools are inadequate for reliable prediction of prostate cancer (PCa) aggressiveness in patients with localised disease. This results in many patients being exposed to potentially unnecessary invasive treatment and its associated morbidities. In order to develop appropriate treatment strategies, it is essential to understand the differences between patients who will develop aggressive disease and those who will not.

METHODS

A longitudinal study was conducted in men with localised PCa on active surveillance for their disease in which 140 subjects were followed every 3 months for up to 5 years. Change in prostate-specific antigen (PSA) over time (PSA velocity) was used as a marker for PCa progression. Subjects were categorised as slow, intermediate and fast progressors based on tertiles of PSA velocity. Differences in baseline markers were investigated using logistic regressions. Two approaches were used, slow progressors were compared with fast progressors (model 1) and slow progressors were compared with combination of intermediate and fast progressors (model 2).

RESULTS

Aspirin was negatively associated with high PSA velocity in model 1 (odds ratio (95% confidence interval): 0.24 (0.06, 0.94), P-value = 0.04) and model 2 (odds ratio = 0.22 (0.08, 0.59), P-value = 0.003), whereas smoking was positively associated with high PSA velocity in model 1 (1.03 (0.92, 1.13), P-value = 0.01).

CONCLUSIONS

These findings highlight the role of aspirin and smoking in PCa progression. They have potential towards risk stratification as well as PCa prevention and hence need to be investigated further.

Selenium and prevention of prostate cancer in high-risk men: the Negative Biopsy Study

Epidemiological and clinical studies suggesting a significant inverse relationship between intake of dietary selenium and overall cancer risk have led to initiation of a randomized, placebo-controlled, phase III clinical trial testing the safety and efficacy of selenized yeast as a chemopreventive agent for prostate cancer. Participants eligible for the 'Negative Biopsy Study', which was initiated in August 1999, are men considered to be at high risk for prostate cancer because of at least one negative sextant prostate biopsy, which was clinically indicated within 1 year of enrollment to the study. After a 30-day run-in period to ensure protocol compliance, participants are randomized to receive either 200 or 400 microg selenized yeast or matched placebo once daily. Primary study endpoints include development of prostate cancer and prostate-specific antigen (PSA) velocity. Secondary biochemical endpoints include change in chromagranin A and alkaline phosphatase. As of 1 June 2003, 514 eligible participants had been enrolled. Randomization schema was effective for selected parameters including age, body mass index, smoking status, baseline PSA and baseline plasma selenium level. Various data, including medical history, family history, and urological symptoms and specimens (including blood and subsequent prostate biopsy samples) had been collected at baseline, and throughout both the intervention and follow-up stages of the protocol. The goal for accrual is 700 evaluable participants.

Selenium and inhibition of disease progression in men diagnosed with prostate carcinoma: study design and baseline characteristics of the ‘Watchful Waiting’ Study

Impediment of the promotion and progression stages of carcinogenesis of the prostate could have a profound impact on treatment choice and prognosis for prostate cancer. Efficacious chemopreventive agents that elicit their activity by slowing the processes of progression could make watchful waiting a viable alternative for a large population of men or could delay the necessity for surgery, radiation or other more invasive treatment modalities associated with frequent side effects. Reports from the Nutritional Prevention of Cancer (NPC) study reported that dietary supplementation with selenium significantly reduced the risk of developing prostate cancer. These data led to initiation of the Watchful Waiting Study, a phase II, multi-center, randomized, double-blind, placebo-controlled clinical intervention study testing the effects of two doses of selenized yeast on progression of prostate cancer. Participants are men with biopsy-proven prostate cancer who have elected to forgo therapy and be closely followed by 'watchful waiting' that includes quarterly prostate-specific antigen (PSA) screening. Subjects are randomized to receive 200 or 800 microg of selenized yeast or matched placebo daily. Endpoints include time to disease progression and PSA velocity. Secondary endpoints include time to initiation of therapy as well as biochemical markers of disease progression including chromagranin A and alkaline phosphatase. Immunohistochemical analyses for indicators of apoptosis, proliferation and differentiation will be performed on baseline and subsequent prostate biopsy specimens. This report summarizes the primary objectives, research methods and the randomized subjects in this important clinical trial.

Expression of the matrix metalloproteinase promatrilysin in coculture of prostate carcinoma cell lines

BACKGROUND

Matrix metalloproteinases (MMPs) are involved in tumor progression. Matrilysin (MMP-7) has been shown to be upregulated in prostatic carcinomas and can increase the invasive capacity of DU-145 cells. Because of the heterogenous nature of prostatic tumors, we examined promatrilysin expression in cocultures containing two different prostatic carcinoma cell lines, DU-145 and LNCaP.

METHODS

Using enzyme linked immunosorbent assay (ELISA) analyses, promatrilysin expression was measured in DU-145/LNCaP cocultures and conditioned media cross-cultures. The effects of blocking IL-6 on promatrilysin expression were examined by pretreating conditioned media with IL-6 neutralizing antibody.

RESULTS

A significant induction of promatrilysin expression was observed in DU-145/LNCaP cocultures compared to LNCaP cells alone. In addition, DU-145 conditioned medium induced the same fold induction of promatrilysin as was observed in the cocultures. LNCaP cell conditioned medium did not induce promatrilysin expression in DU-145 cells. Neutralization of IL-6 with neutralizing antibody abrogated DU-145 conditioned media induced promatrilysin expression to baseline levels.

CONCLUSIONS

IL-6 secreted by DU-145 cells can induce promatrilysin expression in LNCaP cells. IL-6, in vivo, may act as a paracrine signaling factor that regulates matrix metalloproteinase expression. Therefore, IL-6 may play a role in invasive metastatic processes of a prostate carcinoma.