Abstract
Purpose: Dopamine and cAMP-regulated phosphoprotein, Mr 32,000 (DARPP-32), is overexpressed during the gastric carcinogenesis cascade. Here, we investigated the role of DARPP-32 in promoting resistance to treatment with TRAIL. Experimental Design: In vitro cell models including stable expression and knockdown of DARPP-32 were used. The role of DARPP-32 in regulating TRAIL-dependent apoptosis was evaluated by clonogenic survival assay, Annexin V staining, immunofluorescence, quantitative reverse transcriptase PCR, Western blot, and luciferase reporter assays. Results: Stable expression of DARPP-32 in MKN-28 cells enhanced cell survival and suppressed TRAIL-induced cytochrome c release and activation of caspase-8, -9, and -3. Conversely, short hairpin RNA-mediated knockdown of endogenous DARPP-32 sensitized the resistant MKN-45 cells to TRAIL-induced apoptosis and enhanced TRAIL-mediated activation of caspase-8, -9, and -3. DARPP-32 induced BCL-xL expression through activation of Src/STAT3 signaling, and treatment with the Src-specific inhibitor PP1 abrogated DARPP-32-dependent BCL-xL upregulation and cell survival in MKN-28 cells. The TRAIL treatment induced caspase-dependent cleavage of NF-κBp65 protein; this cleavage was prevented by DARPP-32, thus maintaining NF-κB activity and the expression of its target, FLIP(S) protein. This suggests that upregulation of BCL-xL could play a possible role in blocking the mitochondria intrinsic apoptosis pathway, whereas the DARPP-32 effect on the NF-κB/FLIP(S) axis could serve as an additional negative feedback loop that blocks TRAIL-induced activation of caspase-8. Conclusion: Our findings uncover a novel mechanism of TRAIL resistance mediated by DARPP-32, whereby it inhibits the intrinsic apoptosis pathway through upregulation of BCL-xL, and the extrinsic apoptosis pathway through the NF-κB/FLIP(S) axis.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 3889-3900 |
| Number of pages | 12 |
| Journal | Clinical Cancer Research |
| Volume | 18 |
| Issue number | 14 |
| DOIs | |
| State | Published - Jul 15 2012 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Oncology
- Cancer Research
Cite this
Resistance to TRAIL is mediated by DARPP-32 in gastric cancer. / Belkhiri, Abbes; Zhu, Shoumin; Chen, Zheng; Soutto, Mohammed; El-Rifai, Wael.
In: Clinical Cancer Research, Vol. 18, No. 14, 15.07.2012, p. 3889-3900.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Resistance to TRAIL is mediated by DARPP-32 in gastric cancer
AU - Belkhiri, Abbes
AU - Zhu, Shoumin
AU - Chen, Zheng
AU - Soutto, Mohammed
AU - El-Rifai, Wael
PY - 2012/7/15
Y1 - 2012/7/15
N2 - Purpose: Dopamine and cAMP-regulated phosphoprotein, Mr 32,000 (DARPP-32), is overexpressed during the gastric carcinogenesis cascade. Here, we investigated the role of DARPP-32 in promoting resistance to treatment with TRAIL. Experimental Design: In vitro cell models including stable expression and knockdown of DARPP-32 were used. The role of DARPP-32 in regulating TRAIL-dependent apoptosis was evaluated by clonogenic survival assay, Annexin V staining, immunofluorescence, quantitative reverse transcriptase PCR, Western blot, and luciferase reporter assays. Results: Stable expression of DARPP-32 in MKN-28 cells enhanced cell survival and suppressed TRAIL-induced cytochrome c release and activation of caspase-8, -9, and -3. Conversely, short hairpin RNA-mediated knockdown of endogenous DARPP-32 sensitized the resistant MKN-45 cells to TRAIL-induced apoptosis and enhanced TRAIL-mediated activation of caspase-8, -9, and -3. DARPP-32 induced BCL-xL expression through activation of Src/STAT3 signaling, and treatment with the Src-specific inhibitor PP1 abrogated DARPP-32-dependent BCL-xL upregulation and cell survival in MKN-28 cells. The TRAIL treatment induced caspase-dependent cleavage of NF-κBp65 protein; this cleavage was prevented by DARPP-32, thus maintaining NF-κB activity and the expression of its target, FLIP(S) protein. This suggests that upregulation of BCL-xL could play a possible role in blocking the mitochondria intrinsic apoptosis pathway, whereas the DARPP-32 effect on the NF-κB/FLIP(S) axis could serve as an additional negative feedback loop that blocks TRAIL-induced activation of caspase-8. Conclusion: Our findings uncover a novel mechanism of TRAIL resistance mediated by DARPP-32, whereby it inhibits the intrinsic apoptosis pathway through upregulation of BCL-xL, and the extrinsic apoptosis pathway through the NF-κB/FLIP(S) axis.
AB - Purpose: Dopamine and cAMP-regulated phosphoprotein, Mr 32,000 (DARPP-32), is overexpressed during the gastric carcinogenesis cascade. Here, we investigated the role of DARPP-32 in promoting resistance to treatment with TRAIL. Experimental Design: In vitro cell models including stable expression and knockdown of DARPP-32 were used. The role of DARPP-32 in regulating TRAIL-dependent apoptosis was evaluated by clonogenic survival assay, Annexin V staining, immunofluorescence, quantitative reverse transcriptase PCR, Western blot, and luciferase reporter assays. Results: Stable expression of DARPP-32 in MKN-28 cells enhanced cell survival and suppressed TRAIL-induced cytochrome c release and activation of caspase-8, -9, and -3. Conversely, short hairpin RNA-mediated knockdown of endogenous DARPP-32 sensitized the resistant MKN-45 cells to TRAIL-induced apoptosis and enhanced TRAIL-mediated activation of caspase-8, -9, and -3. DARPP-32 induced BCL-xL expression through activation of Src/STAT3 signaling, and treatment with the Src-specific inhibitor PP1 abrogated DARPP-32-dependent BCL-xL upregulation and cell survival in MKN-28 cells. The TRAIL treatment induced caspase-dependent cleavage of NF-κBp65 protein; this cleavage was prevented by DARPP-32, thus maintaining NF-κB activity and the expression of its target, FLIP(S) protein. This suggests that upregulation of BCL-xL could play a possible role in blocking the mitochondria intrinsic apoptosis pathway, whereas the DARPP-32 effect on the NF-κB/FLIP(S) axis could serve as an additional negative feedback loop that blocks TRAIL-induced activation of caspase-8. Conclusion: Our findings uncover a novel mechanism of TRAIL resistance mediated by DARPP-32, whereby it inhibits the intrinsic apoptosis pathway through upregulation of BCL-xL, and the extrinsic apoptosis pathway through the NF-κB/FLIP(S) axis.
UR - http://www.scopus.com/inward/record.url?scp=84863928392&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84863928392&partnerID=8YFLogxK
U2 - 10.1158/1078-0432.CCR-11-3182
DO - 10.1158/1078-0432.CCR-11-3182
M3 - Article
C2 - 22589394
AN - SCOPUS:84863928392
VL - 18
SP - 3889
EP - 3900
JO - Clinical Cancer Research
JF - Clinical Cancer Research
SN - 1078-0432
IS - 14
ER -