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Abstract Background Androgen deprivation therapy (ADT) is still the first-line treatment of prostate cancer (PCa). However, after a certain period of therapy, primary PCa inevitably progresses into castration-resistant PCa (CRPC). Enzalutamide (Enz) is an androgen receptor (AR) signal inhibitor which can delay the progression of CRPC and increase survival of patients with metastatic CRPC. However, the mechanisms involved in enzalutamide-resistant (EnzR) CRPC are still controversial. In the study, we used bioinformatic methods to find potential genes that correlated with the occurrence of EnzR CRPC. Methods We collected RNA sequencing data of the EnzR CRPC cell line LNCaP (EnzR LNCaP) from GSE44905, GSE78201, and GSE150807. We found the hub genes from the three datasets. Then we tested the expression of the hub genes in different databases and the potential drugs that can affect the hub genes. Finally, we verified the hub gene expression and drug function. Results From GSE44905, GSE78201 and GSE150807, we found 45 differentially expressed genes (DEGs) between LNCaP and EnzR LNCaP. Ten hub genes were found in the protein–protein interaction (PPI) network. The expression of hub gene and survival analysis were analyzed by different databases. We found that cyclin-dependent kinase 6 (CDK6) was highly expressed in both the EnzR LNCaP cell and PCa patients. Ten potential small molecules could suppress CDK6 expression as per “CLUE COMMAND” findings. Finally, we found the expression of CDK6 increased in both PCa patients’ samples, CRPC and EnzR PCa cell lines. Three potential CDK6 inhibitors, namely apigenin, chrysin and fisetin, can decrease cell proliferation. Conclusions The study proved that the abnormal overexpression of CDK6 may be a reason behind EnzR CRPC occurrence and suppression CDK6 expression may help treat EnzR CRPC.

Abstract Background A history of prior cancer commonly results in exclusion from cancer clinical trials. However, whether a prior cancer history has an adversely impact on clinical outcomes for patients with advanced prostate cancer (APC) remains largely unknown. We therefore aimed to investigate the impact of prior cancer history on these patients. Methods We identified patients with advanced prostate cancer diagnosed from 2004 to 2010 in the Surveillance, Epidemiology, and End Results (SEER) database. Propensity score matching (PSM) was used to balance baseline characteristics. Kaplan–Meier method and the Cox proportional hazard model were utilized for survival analysis. Results A total of 19,772 eligible APC patients were included, of whom 887 (4.5 %) had a history of prior cancer. Urinary bladder (19 %), colon and cecum (16 %), melanoma of the skin (9 %) malignancies, and non-hodgkin lymphoma (9 %) were the most common types of prior cancer. Patients with a history of prior cancer had slightly inferior overall survival (OS) (AHR = 1.13; 95 % CI [1.02–1.26]; P = 0.017) as compared with that of patients without a prior cancer diagnosis. Subgroup analysis further indicated that a history of prior cancer didn’t adversely impact patients’ clinical outcomes, except in patients with a prior cancer diagnosed within 2 years, at advanced stage, or originating from specific sites, including bladder, colon and cecum, or lung and bronchus, or prior chronic lymphocytic leukemia. Conclusions A large proportion of APC patients with a prior cancer history had non-inferior survival to that of patients without a prior cancer diagnosis. These patients may be candidates for relevant cancer trials.