title: Quantitative proteomics reveals that enzymes of the ketogenic pathway are associated with prostate cancer progression.
abstract: Prostate cancer is the most common malignancy and the second leading cause of cancer-related deaths in men. One common treatment is androgen-deprivation therapy, which reduces symptoms in most patients. However, over time, patients develop tumors that are androgen-independent and ultimately fatal. The mechanisms that cause this transition remain largely unknown, and as a result, there are no effective treatments against androgen-independent prostate cancer. As a model platform, we used the LNCaP cell line and its androgen-independent derivative, LNCaP-SF. Utilizing stable isotope labeling with amino acids in cell culture coupled to mass spectrometry, we assessed the differential global protein expression of the two cell lines. Our proteomic analysis resulted in the quantification of 3355 proteins. Bioinformatic prioritization resulted in 42 up-regulated and 46 down-regulated proteins in LNCaP-SF cells relative to LNCaP cells. Our top candidate, HMGCS2, an enzyme involved in ketogenesis, was found to be 9-fold elevated in LNCaP-SF cells, based on peptide ratios. After analyzing the remaining enzymes of this pathway (ACAT1, BDH1, HMGCL, and OXCT1), we observed increased expression of these proteins in the LNCaP-SF cells, which was further verified using Western blotting. To determine whether these enzymes were up-regulated in clinical samples, we performed quantitative PCR and immunohistochemistry on human prostate cancer tissues, from which we observed significantly increased transcript and protein levels in high-grade cancer (Gleason grade ≥ 8). In addition, we observed significant elevation of these enzymes in the LuCaP 96AI castration-resistant xenograft. Further assessment of ACAT1 on human castration-resistant metastatic prostate cancer tissues revealed substantially elevated expression of ACAT1 in these specimens. Taken together, our results indicate that enzymes of the ketogenic pathway are up-regulated in high-grade prostate cancer and could serve as potential tissue biomarkers for the diagnosis or prognosis of high-grade disease.
authors: Department of Pathology and Laboratory Medicine, Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, ON, Canada M5T 3L9.
authors: Punit
authors: P
authors: Saraon
authors: Daniela
authors: D
authors: Cretu
authors: Natasha
authors: N
authors: Musrap
authors: George S
authors: GS
authors: Karagiannis
authors: Ihor
authors: I
authors: Batruch
authors: Andrei P
authors: AP
authors: Drabovich
authors: Theodorus
authors: T
authors: van der Kwast
authors: Atsushi
authors: A
authors: Mizokami
authors: Colm
authors: C
authors: Morrissey
authors: Keith
authors: K
authors: Jarvi
authors: Eleftherios P
authors: EP
authors: Diamandis
mesh_terms: D000101:Acetyl-CoA C-Acetyltransferase / Q000235:genetics* / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D018450:Disease Progression; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D006904:Hydroxymethylglutaryl-CoA Synthase / Q000235:genetics* / Q000378:metabolism; D007553:Isotope Labeling; D008297:Male; D013058:Mass Spectrometry; D060787:Neoplasm Grading; D009362:Neoplasm Metastasis; D009363:Neoplasm Proteins / Q000235:genetics* / Q000378:metabolism; D011467:Prostate / Q000378:metabolism / Q000473:pathology; D011471:Prostatic Neoplasms / Q000175:diagnosis / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D064129:Prostatic Neoplasms, Castration-Resistant / Q000175:diagnosis / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D040901:Proteomics
chemical_list: D014408:Biomarkers, Tumor; D009363:Neoplasm Proteins; C506639:ACAT1 protein, human; D000101:Acetyl-CoA C-Acetyltransferase; D006904:Hydroxymethylglutaryl-CoA Synthase