Limits...
Diverse effects of ANXA7 and p53 on LNCaP prostate cancer cells are associated with regulation of SGK1 transcription and phosphorylation of the SGK1 target FOXO3A.

Srivastava M, Leighton X, Starr J, Eidelman O, Pollard HB - Biomed Res Int (2014)

Bottom Line: In addition, p53 reduced the expression of aberrant SGK1 protein form in LNCaP.Using Ingenuity Pathway Analysis and p53-signature genes, we elucidated the role of distinct SGK1/FOXO3A-associated regulation in p53 versus ANXA7 responses and proposed that aberrant SGK1 could affect reciprocal SGK1-FOXO3A-Akt regulation.Thus, the failure of the cell growth regulator p53 versus the phospholipid-binding ANXA7 could be potentially attributed to its diverse effects on SGK1-FOXO3A-Akt pathway in the PTEN-deficient LNCaP.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy, Physiology and Genetics and Institute for Molecular Medicine, Uniformed Services University of Health Sciences (USUHS), School of Medicine, Bethesda, MD 20814, USA.

ABSTRACT
Tumor suppressor function of the calcium/phospholipid-binding Annexin-A7 (ANXA7) has been shown in Anxa7-deficient mice and validated in human cancers. In the androgen-resistant prostate cancer cells, ANXA7 and p53 showed similar cytotoxicity levels. However, in the androgen-sensitive LNCaP, ANXA7 greatly exceeded the p53-induced cytotoxicity. We hypothesized that the p53 underperformance in LNCaP could be due to the involvement of p53-responsive SGK1 and FOXO3A. In this study, we show that p53 failed to match programmed cell death (PCD) and G1-arrest that were induced by ANXA7 in LNCaP. WT-ANXA7 preserved total FOXO3A expression with no hyperphosphorylation that could enable FOXO3A nuclear translocation and proapoptotic transcription. In contrast, in the p53-transfected LNCaP cells with maintained cell proliferation, the phosphorylated (but not total) FOXO3A fraction was increased implying a predominantly cytoplasmic localization and, subsequently, a lack of FOXO3A proapoptotic transcription. In addition, p53 reduced the expression of aberrant SGK1 protein form in LNCaP. Using Ingenuity Pathway Analysis and p53-signature genes, we elucidated the role of distinct SGK1/FOXO3A-associated regulation in p53 versus ANXA7 responses and proposed that aberrant SGK1 could affect reciprocal SGK1-FOXO3A-Akt regulation. Thus, the failure of the cell growth regulator p53 versus the phospholipid-binding ANXA7 could be potentially attributed to its diverse effects on SGK1-FOXO3A-Akt pathway in the PTEN-deficient LNCaP.

Show MeSH

Related in: MedlinePlus

Graphs represent the differences (delta %) in cell numbers in different phases in response to WT/DN-ANXA7 and p53 (18 hr); mean values from replicates (%) are presented after the subtraction of control levels in corresponding vectors.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4016907&req=5

fig2: Graphs represent the differences (delta %) in cell numbers in different phases in response to WT/DN-ANXA7 and p53 (18 hr); mean values from replicates (%) are presented after the subtraction of control levels in corresponding vectors.

Mentions: Programmed cell death (PCD) responses to WT/DN-ANXA7 and p53 (18 hr) were assessed by Annexin V-PE and APO-BRDU. In AnnexinV-PE assay (Figure 1(a)), WT-ANXA7 induced early apoptosis with phosphatidylserine exposure as well as late apoptosis with membrane permeabilization, whereas DN-ANXA7 failed to reach the same PCD rates (P < 0.001 for both comparisons) in LNCaP cells. In APO-BRDU assay (Figure 1(b)), WT-ANXA7 caused a 2-fold PCD increase compared to DN-ANXA7 (P < 0.001) inducing DNA fragmentation almost in half of LNCaP cells. In the meantime, p53 caused only a slight increase with the phosphatidylserine exposure causing a potentially reversible early apoptosis. In contrast, WT-ANXA7 and p53 induced comparable levels of PCD and cell growth inhibition in androgen-resistant DU145 and PC3 [4]. As shown in Figure 2, WT-ANXA7 caused a G1-arrest in LNCaP cells that was not matched by DN-ANXA7 (P < 0.001), whereas p53 failed to reach the cell growth inhibition effects of WT- as well as DN-ANXA7. These results along with DNA fragmentation (APO-BRDU) as well as by phosphatidylserine exposure and membrane permeabilization (AnnexinV-PE) suggest that wild-type- (WT-) ANXA7 surpassed the p53-induced PCD and cell cycle inhibition in androgen-sensitive LNCaP.


Diverse effects of ANXA7 and p53 on LNCaP prostate cancer cells are associated with regulation of SGK1 transcription and phosphorylation of the SGK1 target FOXO3A.

Srivastava M, Leighton X, Starr J, Eidelman O, Pollard HB - Biomed Res Int (2014)

Graphs represent the differences (delta %) in cell numbers in different phases in response to WT/DN-ANXA7 and p53 (18 hr); mean values from replicates (%) are presented after the subtraction of control levels in corresponding vectors.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4016907&req=5

fig2: Graphs represent the differences (delta %) in cell numbers in different phases in response to WT/DN-ANXA7 and p53 (18 hr); mean values from replicates (%) are presented after the subtraction of control levels in corresponding vectors.
Mentions: Programmed cell death (PCD) responses to WT/DN-ANXA7 and p53 (18 hr) were assessed by Annexin V-PE and APO-BRDU. In AnnexinV-PE assay (Figure 1(a)), WT-ANXA7 induced early apoptosis with phosphatidylserine exposure as well as late apoptosis with membrane permeabilization, whereas DN-ANXA7 failed to reach the same PCD rates (P < 0.001 for both comparisons) in LNCaP cells. In APO-BRDU assay (Figure 1(b)), WT-ANXA7 caused a 2-fold PCD increase compared to DN-ANXA7 (P < 0.001) inducing DNA fragmentation almost in half of LNCaP cells. In the meantime, p53 caused only a slight increase with the phosphatidylserine exposure causing a potentially reversible early apoptosis. In contrast, WT-ANXA7 and p53 induced comparable levels of PCD and cell growth inhibition in androgen-resistant DU145 and PC3 [4]. As shown in Figure 2, WT-ANXA7 caused a G1-arrest in LNCaP cells that was not matched by DN-ANXA7 (P < 0.001), whereas p53 failed to reach the cell growth inhibition effects of WT- as well as DN-ANXA7. These results along with DNA fragmentation (APO-BRDU) as well as by phosphatidylserine exposure and membrane permeabilization (AnnexinV-PE) suggest that wild-type- (WT-) ANXA7 surpassed the p53-induced PCD and cell cycle inhibition in androgen-sensitive LNCaP.

Bottom Line: In addition, p53 reduced the expression of aberrant SGK1 protein form in LNCaP.Using Ingenuity Pathway Analysis and p53-signature genes, we elucidated the role of distinct SGK1/FOXO3A-associated regulation in p53 versus ANXA7 responses and proposed that aberrant SGK1 could affect reciprocal SGK1-FOXO3A-Akt regulation.Thus, the failure of the cell growth regulator p53 versus the phospholipid-binding ANXA7 could be potentially attributed to its diverse effects on SGK1-FOXO3A-Akt pathway in the PTEN-deficient LNCaP.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy, Physiology and Genetics and Institute for Molecular Medicine, Uniformed Services University of Health Sciences (USUHS), School of Medicine, Bethesda, MD 20814, USA.

ABSTRACT
Tumor suppressor function of the calcium/phospholipid-binding Annexin-A7 (ANXA7) has been shown in Anxa7-deficient mice and validated in human cancers. In the androgen-resistant prostate cancer cells, ANXA7 and p53 showed similar cytotoxicity levels. However, in the androgen-sensitive LNCaP, ANXA7 greatly exceeded the p53-induced cytotoxicity. We hypothesized that the p53 underperformance in LNCaP could be due to the involvement of p53-responsive SGK1 and FOXO3A. In this study, we show that p53 failed to match programmed cell death (PCD) and G1-arrest that were induced by ANXA7 in LNCaP. WT-ANXA7 preserved total FOXO3A expression with no hyperphosphorylation that could enable FOXO3A nuclear translocation and proapoptotic transcription. In contrast, in the p53-transfected LNCaP cells with maintained cell proliferation, the phosphorylated (but not total) FOXO3A fraction was increased implying a predominantly cytoplasmic localization and, subsequently, a lack of FOXO3A proapoptotic transcription. In addition, p53 reduced the expression of aberrant SGK1 protein form in LNCaP. Using Ingenuity Pathway Analysis and p53-signature genes, we elucidated the role of distinct SGK1/FOXO3A-associated regulation in p53 versus ANXA7 responses and proposed that aberrant SGK1 could affect reciprocal SGK1-FOXO3A-Akt regulation. Thus, the failure of the cell growth regulator p53 versus the phospholipid-binding ANXA7 could be potentially attributed to its diverse effects on SGK1-FOXO3A-Akt pathway in the PTEN-deficient LNCaP.

Show MeSH
Related in: MedlinePlus