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Resveratrol and STAT inhibitor enhance autophagy in ovarian cancer cells

View Article: PubMed Central - PubMed

ABSTRACT

Autophagic activity reflects cellular response to drug treatment and can be regulated by STAT3 signaling. Resveratrol inhibits STAT3 activation and causes remarkable growth arrest and cell death of ovarian cancer (OC) cells. However, the autophagic status and its relevance with resveratrol’s anti-OC effects remain unclear. We analyzed the states of autophagic activities, the nature of autophagosomes and the levels of autophagy-related proteins (LC-3, Beclin 1 and STAT3) in resveratrol-treated CAOV-3 and OVCAR-3 OC cells using multiple approaches. We elucidated the correlation of STAT3 inhibition with autophagic activity by treating OC cells with an upstream inhibitor of STAT proteins, AG490. Resveratrol efficiently suppressed growth, induced apoptosis and inactivated STAT3 signaling of the two OC cell lines. We found enhanced autophagic activity accompanied with Beclin-1 upregulation and LC3 enzymatic cleavage in resveratrol-treated OC cells. Immunofluorescent (IF) microscopic and IF-based confocal examinations demonstrated the accumulation of cytoplasmic granules co-labeled with LC3 and cytochrome C in resveratrol- or AG490-treated OC cells. Using electron microscopy, we confirmed an increase in autophagosomes and mitochondrial spheroids in either resveratrol- or AG490-treated OC cells. This study demonstrates the abilities of resveratrol to enhance apoptotic and autophagic activities in OC cells, presumably via inactivating STAT3 signaling. Resveratrol or the selective JAK2 inhibitor also leads to mitochondrial turnover, which would be unfavorable for OC cell survival and sensitize OC cells to resveratrol.

No MeSH data available.


Evaluation of STAT3 activation, autophagic activities and apoptosis of CAOV-3 cells without (N) and with AG490 treatment (AG490). (a) Immunocytochemical staining for p-STAT3, LC-3 and Beclin 1; (b) Confocal images of double LC-3 and cytochrome C IF labeling; (c) H/E morphological staining performed on the IF stained coverslips for confocal examination. Arrow indicates the cell shown in the inset with higher magnification.
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fig5: Evaluation of STAT3 activation, autophagic activities and apoptosis of CAOV-3 cells without (N) and with AG490 treatment (AG490). (a) Immunocytochemical staining for p-STAT3, LC-3 and Beclin 1; (b) Confocal images of double LC-3 and cytochrome C IF labeling; (c) H/E morphological staining performed on the IF stained coverslips for confocal examination. Arrow indicates the cell shown in the inset with higher magnification.

Mentions: To elucidate the role of STAT3 signaling in regulating autophagic activity, AG490, a selective JAK2 inhibitor, was used to treat the CAOV-3 cell line for 48 h, followed by TUNEL apoptotic cell labeling, STAT3-oriented immunocytochemical staining and double immunoflorescent staining/IF for LC3/Becline-1 and LC3/cytochrome C. As shown in Figure 5, AG490 suppressed cell growth, inhibited STAT3 nuclear translocation and upregulated Becline-1 and, especially, LC3 expression. Furthermore, LC3+/cytochrome C+ granules (Figure 5c) and TUNEL-positive cells (Figure 5b) were frequently observed in AG490-treated CAOV-3 cells.


Resveratrol and STAT inhibitor enhance autophagy in ovarian cancer cells
Evaluation of STAT3 activation, autophagic activities and apoptosis of CAOV-3 cells without (N) and with AG490 treatment (AG490). (a) Immunocytochemical staining for p-STAT3, LC-3 and Beclin 1; (b) Confocal images of double LC-3 and cytochrome C IF labeling; (c) H/E morphological staining performed on the IF stained coverslips for confocal examination. Arrow indicates the cell shown in the inset with higher magnification.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4979504&req=5

fig5: Evaluation of STAT3 activation, autophagic activities and apoptosis of CAOV-3 cells without (N) and with AG490 treatment (AG490). (a) Immunocytochemical staining for p-STAT3, LC-3 and Beclin 1; (b) Confocal images of double LC-3 and cytochrome C IF labeling; (c) H/E morphological staining performed on the IF stained coverslips for confocal examination. Arrow indicates the cell shown in the inset with higher magnification.
Mentions: To elucidate the role of STAT3 signaling in regulating autophagic activity, AG490, a selective JAK2 inhibitor, was used to treat the CAOV-3 cell line for 48 h, followed by TUNEL apoptotic cell labeling, STAT3-oriented immunocytochemical staining and double immunoflorescent staining/IF for LC3/Becline-1 and LC3/cytochrome C. As shown in Figure 5, AG490 suppressed cell growth, inhibited STAT3 nuclear translocation and upregulated Becline-1 and, especially, LC3 expression. Furthermore, LC3+/cytochrome C+ granules (Figure 5c) and TUNEL-positive cells (Figure 5b) were frequently observed in AG490-treated CAOV-3 cells.

View Article: PubMed Central - PubMed

ABSTRACT

Autophagic activity reflects cellular response to drug treatment and can be regulated by STAT3 signaling. Resveratrol inhibits STAT3 activation and causes remarkable growth arrest and cell death of ovarian cancer (OC) cells. However, the autophagic status and its relevance with resveratrol’s anti-OC effects remain unclear. We analyzed the states of autophagic activities, the nature of autophagosomes and the levels of autophagy-related proteins (LC-3, Beclin 1 and STAT3) in resveratrol-treated CAOV-3 and OVCAR-3 OC cells using multiple approaches. We elucidated the correlation of STAT3 inhibition with autophagic activity by treating OC cells with an upstream inhibitor of STAT proteins, AG490. Resveratrol efficiently suppressed growth, induced apoptosis and inactivated STAT3 signaling of the two OC cell lines. We found enhanced autophagic activity accompanied with Beclin-1 upregulation and LC3 enzymatic cleavage in resveratrol-treated OC cells. Immunofluorescent (IF) microscopic and IF-based confocal examinations demonstrated the accumulation of cytoplasmic granules co-labeled with LC3 and cytochrome C in resveratrol- or AG490-treated OC cells. Using electron microscopy, we confirmed an increase in autophagosomes and mitochondrial spheroids in either resveratrol- or AG490-treated OC cells. This study demonstrates the abilities of resveratrol to enhance apoptotic and autophagic activities in OC cells, presumably via inactivating STAT3 signaling. Resveratrol or the selective JAK2 inhibitor also leads to mitochondrial turnover, which would be unfavorable for OC cell survival and sensitize OC cells to resveratrol.

No MeSH data available.