Schlafen 12 expression modulates prostate cancer cell differentiation.
BACKGROUND
Schlafen proteins have previously been linked to leukocyte and intestinal epithelial differentiation. We hypothesized that Schlafen 12 (SLFN12) overexpression in human prostate epithelial cells would modulate expression of prostate-specific antigen (PSA) and dipeptidyl peptidase 4 (DPP4), markers of prostatic epithelial differentiation.


METHODS
Differentiation of the human prostate cancer cell lines LNCaP and PC-3 was compared after infection with an adenoviral vector coding for SLFN12 (Ad-SLFN12) or green fluorescent protein (GFP) only expressing virus (control). Transcript levels of SLFN12, PSA, and DPP4 were evaluated by real-time reverse transcription PCR and protein levels by Western blotting. Because mixed lineage kinase (MLK) and one of its downstream effectors (extracellular signal-regulated kinases [ERK]) have previously been implicated in some aspects of prostate epithelial differentiation, we conducted further studies in which LNCaP cells were cotreated with dimethyl sulfoxide (control), PD98059 (ERK inhibitor), or MLK inhibitor during transfection with Ad-SLFN12 for 72 h.


RESULTS
Treatment of LNCaP or PC-3 cells with Ad-SLFN12 reduced PSA expression by 56.6±4.6% (P<0.05) but increased DPP4 transcript level by 4.8±1.0 fold (P<0.05) versus Ad-GFP-treated controls. Further studies in LNCaP cells showed that Ad-SLFN12 overexpression increased the ratio of the mature E-cadherin protein to its precursor protein. Furthermore, SLFN12 overexpression promoted DPP4 expression either when MLK or ERK was blocked. ERK inhibition did not reverse SLFN12-induced changes in PSA, E-cadherin, or DPP4.


CONCLUSIONS
SLFN12 may regulate differentiation in prostate epithelial cells, at least in part independently of ERK or MLK. Understanding how SLFN12 influences prostatic epithelial differentiation may ultimately identify targets to influence the phenotype of prostatic malignancy.
Department of Surgery, College of Human Medicine, Michigan State University, East Lansing, Michigan.
Pavlo L
PL
Kovalenko
Department of Surgery, College of Human Medicine, Michigan State University, East Lansing, Michigan. Electronic address: marc.basson@hc.msu.edu.
Marc D
MD
Basson
D015820:Cadherins / Q000032:analysis; D002454:Cell Differentiation; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D018819:Dipeptidyl Peptidase 4 / Q000235:genetics; D006801:Humans; D020935:MAP Kinase Signaling System / Q000502:physiology; D008297:Male; D017430:Prostate-Specific Antigen / Q000502:physiology; D011471:Prostatic Neoplasms / Q000473:pathology*; D011506:Proteins / Q000502:physiology*; D047908:Intracellular Signaling Peptides and Proteins
D015820:Cadherins; D018819:Dipeptidyl Peptidase 4; D017430:Prostate-Specific Antigen; D011506:Proteins; C042807:DPP4 protein, human; C000656172:SLFN12 protein, human; D047908:Intracellular Signaling Peptides and Proteins
DPP4; E-cadherin; LNCaP; Metastasis; PC-3; PSA; Proliferation