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Purpose Data suggest that circulating 25-hydroxyvitamin D [25(OH)D] interacts with the vitamin D receptor (VDR) to decrease proliferation and increase apoptosis for some malignancies, although evidence for prostate cancer is less clear. How VDR expression in tumor tissue may influence prostate cancer progression has not been evaluated in large studies. Patients and Methods We examined protein expression of VDR in tumor tissue among 841 patients with prostate cancer in relation to risk of lethal prostate cancer within two prospective cohorts, the Physicians' Health Study and Health Professionals Follow-Up Study. We also examined the association of VDR expression with prediagnostic circulating 25(OH)D and 1,25-dihydroxyvitamin D levels and with two VDR single nucleotide polymorphisms, FokI and BsmI. Results Men whose tumors had high VDR expression had significantly lower prostate-specific antigen (PSA) at diagnosis (P for trend < .001), lower Gleason score (P for trend < .001), and less advanced tumor stage (P for trend < .001) and were more likely to have tumors harboring the TMPRSS2:ERG fusion (P for trend = .009). Compared with the lowest quartile, men whose tumors had the highest VDR expression had significantly reduced risk of lethal prostate cancer (hazard ratio [HR], 0.17; 95% CI, 0.07 to 0.41). This association was only slightly attenuated after adjustment for Gleason score and PSA at diagnosis (HR, 0.33; 95% CI, 0.13 to 0.83) or, additionally, for tumor stage (HR, 0.37; 95% CI, 0.14 to 0.94). Neither prediagnostic plasma vitamin D levels nor VDR polymorphisms were associated with VDR expression. Conclusion High VDR expression in prostate tumors is associated with a reduced risk of lethal cancer, suggesting a role of the vitamin D pathway in prostate cancer progression.

Purpose: SPINK1 overexpression has been described in prostate cancer and is linked with poor prognosis in many cancers. The objective of this study was to characterize the association between SPINK1 overexpression and prostate cancer–specific survival. Experimental Design: The study included 879 participants in the U.S. Physicians' Health Study and Health Professionals Follow-Up Study, diagnosed with prostate cancer (1983–2004) and treated by radical prostatectomy. Protein tumor expression of SPINK1 was evaluated by immunohistochemistry on tumor tissue microarrays. Results: Seventy-four of 879 (8%) prostate cancer tumors were SPINK1 positive. Immunohistochemical data were available for PTEN, p-Akt, pS6, stathmin, androgen receptor (AR), and ERG (as a measure of the TMPRSS2:ERG translocation). Compared with SPINK1-negative tumors, SPINK1-positive tumors showed higher PTEN and stathmin expression, and lower expression of AR (P < 0.01). SPINK1 overexpression was seen in 47 of 427 (11%) ERG-negative samples and in 19 of 427 (4%) ERG-positive cases (P = 0.0003). We found no significant associations between SPINK1 status and Gleason grade or tumor stage. There was no association between SPINK1 expression and biochemical recurrence (P = 0.56). Moreover, there was no association between SPINK1 expression and prostate cancer mortality (there were 75 lethal cases of prostate cancer during a mean of 13.5 years follow-up; HR = 0.71; 95% confidence interval, 0.29–1.76). Conclusions: Our results suggest that SPINK1 protein expression may not be a predictor of recurrence or lethal prostate cancer amongst men treated by radical prostatectomy. SPINK1 and ERG protein expression do not seem to be entirely mutually exclusive, as some previous studies have suggested. Clin Cancer Res; 20(18); 4904–11. ©2014 AACR.