Transcriptomic and Clinical Characterization of Neuropeptide Y Expression in Localized and Metastatic Prostate Cancer: Identification of Novel Prostate Cancer Subtype with Clinical Implications
Authors: Alshalalfa M, Nguyen PL, Beltran H, Chen WS, Davicioni E, Zhao SG, Rebbeck TR, Schaeffer EM, Lotan TL, Feng FY, Mahal BA
Background Tumor microenvironment and its interaction with neuroendocrine modulators contribute to prostate carcinogenesis and progression.
Design, setting, and participants Genome-wide expression profiling of three localized prostate cancer (total n = 18 818) and five metastatic castrate-resistant prostate cancer (mCRPC; total n = 495) cohorts was used to characterize NPY expression. All men underwent radical prostatectomy (RP) for localized prostate cancer.
Outcome measurements and statistical analysis Patients were grouped into those with low NPY and high NPY based on NPY expression. Associations between these groups and histological, genomic, and clinical outcomes including progression-free survival (PFS) and metastases-free survival (MFS) were examined. Combining ERG-fusion status with NPY expression, four groups were defined (lowNPY/ERG+, lowNPY/ERG−, highNPY/ERG+, and highNPY/ERG−). Cox proportional hazards modeled the time to distant metastasis after RP. Genomic risk scores for metastasis were calculated for prospective samples, based on a 22-gene signature.
Results and limitations Across cancers, NPY showed the highest expression in prostate cancer in The Cancer Genome Atlas (TCGA) PAN-Cancer cohort (n = 9483, p < 0.0001). In 17 967 prospective samples, low NPY expression was associated with aggressive grade group 5 disease and a higher genomic risk (p < 0.0001). In the retrospective (n = 355) and TCGA (n = 497) cohorts, low NPY was associated with shorter MFS and PFS, respectively (p = 0.001 for both). In mCRPC cohorts, low NPY was associated with neuroendocrine development (p < 0.01). NPY was highly correlated to ERG; thus, we defined four groups based on NPY expression and ERG fusion. The lowNPY/ERG+ subtype was associated with the highest genomic risk for metastasis (p < 0.0001) and the highest rate of metastasis compared with all other subtypes (hazard ratio [HR]: 2.2 [1.22–4.03], p = 0.008), while the highNPY/ERG− subtype was associated with the lowest genomic risk for metastasis (p < 0.0001) and the lowest rate of metastasis (HR: 0.53 [0.35–0.81], p = 0.003).
Conclusions Low NPY expression is associated with adverse genomic features and clinical correlates and outcomes. The lowNPY/ERG+ subtype was associated with the highest risk of developing metastasis. Prognostic subgrouping and tailored treatments by NPY expression and ERG fusion status warrant further study.
Patient summary The low neuropeptide Y prostate cancer subtype appears to be aggressive with a high risk of developing metastasis.