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Calbindin 2 (CALB2) regulates 5-fluorouracil sensitivity in colorectal cancer by modulating the intrinsic apoptotic pathway.

Stevenson L, Allen WL, Proutski I, Stewart G, Johnston L, McCloskey K, Wilson PM, Longley DB, Johnston PG - PLoS ONE (2011)

Bottom Line: Moreover, 5-FU-induced apoptosis was significantly reduced in HCT116 and LS174T CRC cell lines in which CALB2 expression had been silenced.Furthermore, CALB2 silencing decreased 5-FU-induced cytochrome c and smac release from the mitochondria and also decreased 5-FU-induced activation of caspases 9 and 3/7.Collectively, these results suggest that following 5-FU treatment in CRC cell lines, CALB2 is involved in apoptosis induction through the intrinsic mitochondrial pathway.

View Article: PubMed Central - PubMed

Affiliation: Drug Resistance Group, Centre for Cancer Research and Cell Biology, Queen's University Belfast, Belfast, Northern Ireland.

ABSTRACT
The role of the calcium binding protein, Calbindin 2 (CALB2), in regulating the response of colorectal cancer (CRC) cells to 5-Fluorouracil (5-FU) was investigated. Real-time RT-PCR and Western blot analysis revealed that CALB2 mRNA and protein expression were down-regulated in p53 wild-type and p53 isogenic HCT116 CRC cell lines following 48 h and 72 h 5-FU treatment. Moreover, 5-FU-induced apoptosis was significantly reduced in HCT116 and LS174T CRC cell lines in which CALB2 expression had been silenced. Further investigation revealed that CALB2 translocated to the mitochondria following 5-FU treatment and that 5-FU-induced loss of mitochondrial membrane potential (Ξ”Οˆ(m)) was abrogated in CALB2-silenced cells. Furthermore, CALB2 silencing decreased 5-FU-induced cytochrome c and smac release from the mitochondria and also decreased 5-FU-induced activation of caspases 9 and 3/7. Of note, co-silencing of XIAP overcame 5-FU resistance in CALB2-silenced cells. Collectively, these results suggest that following 5-FU treatment in CRC cell lines, CALB2 is involved in apoptosis induction through the intrinsic mitochondrial pathway. This indicates that CALB2 may be an important mediator of 5-FU-induced cell death. Moreover, down-regulation of CALB2 in response to 5-FU may represent an intrinsic mechanism of resistance to this anti-cancer drug.

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CALB2 expression in CRC patients.Kaplan-Meier survival curves for CALB2 expression across a CRC patient cohort (Dataset: GSE12945, probe ID: 20542 s at, nβ€Š=β€Š62). CALB2 expression and patient survival were analysed for stage 3 patients (nβ€Š=β€Š26, includes 5 stage 4 patients) and combined stage tumours (nβ€Š=β€Š62). The red line shows patients with high CALB2 expression and the blue line shows patients with low CALB2 expression. High and low level expression cut-points were based on median CALB2 expression.
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pone-0020276-g005: CALB2 expression in CRC patients.Kaplan-Meier survival curves for CALB2 expression across a CRC patient cohort (Dataset: GSE12945, probe ID: 20542 s at, nβ€Š=β€Š62). CALB2 expression and patient survival were analysed for stage 3 patients (nβ€Š=β€Š26, includes 5 stage 4 patients) and combined stage tumours (nβ€Š=β€Š62). The red line shows patients with high CALB2 expression and the blue line shows patients with low CALB2 expression. High and low level expression cut-points were based on median CALB2 expression.

Mentions: Given the pro-apoptotic function of CALB2 in CRC cell lines, we used a public CRC data set to determine whether CALB2 expression was associated with patient prognosis (Fig. 5). CALB2 expression in the CRC GSE12945 dataset (PMID: 19399471; probe ID: 20542 s at) was analysed for stage 3 tumours and combined staging. A non-significant trend for high CALB2 expression correlating with increased overall survival was observed in all patients (HRβ€Š=β€Š2.507; 95% CI of ratioβ€Š=β€Š0.8066–7.793; pβ€Š=β€Š0.1122; nβ€Š=β€Š62) and the later stage patients (p valueβ€Š=β€Š0.3057; nβ€Š=β€Š26, includes 21 stage 3 and 5 stage 4 patients). This data suggests a potential association between CALB2 and patient outcome, however this would require validation in a large independent CRC patient cohort.


Calbindin 2 (CALB2) regulates 5-fluorouracil sensitivity in colorectal cancer by modulating the intrinsic apoptotic pathway.

Stevenson L, Allen WL, Proutski I, Stewart G, Johnston L, McCloskey K, Wilson PM, Longley DB, Johnston PG - PLoS ONE (2011)

CALB2 expression in CRC patients.Kaplan-Meier survival curves for CALB2 expression across a CRC patient cohort (Dataset: GSE12945, probe ID: 20542 s at, nβ€Š=β€Š62). CALB2 expression and patient survival were analysed for stage 3 patients (nβ€Š=β€Š26, includes 5 stage 4 patients) and combined stage tumours (nβ€Š=β€Š62). The red line shows patients with high CALB2 expression and the blue line shows patients with low CALB2 expression. High and low level expression cut-points were based on median CALB2 expression.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3101240&req=5

pone-0020276-g005: CALB2 expression in CRC patients.Kaplan-Meier survival curves for CALB2 expression across a CRC patient cohort (Dataset: GSE12945, probe ID: 20542 s at, nβ€Š=β€Š62). CALB2 expression and patient survival were analysed for stage 3 patients (nβ€Š=β€Š26, includes 5 stage 4 patients) and combined stage tumours (nβ€Š=β€Š62). The red line shows patients with high CALB2 expression and the blue line shows patients with low CALB2 expression. High and low level expression cut-points were based on median CALB2 expression.
Mentions: Given the pro-apoptotic function of CALB2 in CRC cell lines, we used a public CRC data set to determine whether CALB2 expression was associated with patient prognosis (Fig. 5). CALB2 expression in the CRC GSE12945 dataset (PMID: 19399471; probe ID: 20542 s at) was analysed for stage 3 tumours and combined staging. A non-significant trend for high CALB2 expression correlating with increased overall survival was observed in all patients (HRβ€Š=β€Š2.507; 95% CI of ratioβ€Š=β€Š0.8066–7.793; pβ€Š=β€Š0.1122; nβ€Š=β€Š62) and the later stage patients (p valueβ€Š=β€Š0.3057; nβ€Š=β€Š26, includes 21 stage 3 and 5 stage 4 patients). This data suggests a potential association between CALB2 and patient outcome, however this would require validation in a large independent CRC patient cohort.

Bottom Line: Moreover, 5-FU-induced apoptosis was significantly reduced in HCT116 and LS174T CRC cell lines in which CALB2 expression had been silenced.Furthermore, CALB2 silencing decreased 5-FU-induced cytochrome c and smac release from the mitochondria and also decreased 5-FU-induced activation of caspases 9 and 3/7.Collectively, these results suggest that following 5-FU treatment in CRC cell lines, CALB2 is involved in apoptosis induction through the intrinsic mitochondrial pathway.

View Article: PubMed Central - PubMed

Affiliation: Drug Resistance Group, Centre for Cancer Research and Cell Biology, Queen's University Belfast, Belfast, Northern Ireland.

ABSTRACT
The role of the calcium binding protein, Calbindin 2 (CALB2), in regulating the response of colorectal cancer (CRC) cells to 5-Fluorouracil (5-FU) was investigated. Real-time RT-PCR and Western blot analysis revealed that CALB2 mRNA and protein expression were down-regulated in p53 wild-type and p53 isogenic HCT116 CRC cell lines following 48 h and 72 h 5-FU treatment. Moreover, 5-FU-induced apoptosis was significantly reduced in HCT116 and LS174T CRC cell lines in which CALB2 expression had been silenced. Further investigation revealed that CALB2 translocated to the mitochondria following 5-FU treatment and that 5-FU-induced loss of mitochondrial membrane potential (Ξ”Οˆ(m)) was abrogated in CALB2-silenced cells. Furthermore, CALB2 silencing decreased 5-FU-induced cytochrome c and smac release from the mitochondria and also decreased 5-FU-induced activation of caspases 9 and 3/7. Of note, co-silencing of XIAP overcame 5-FU resistance in CALB2-silenced cells. Collectively, these results suggest that following 5-FU treatment in CRC cell lines, CALB2 is involved in apoptosis induction through the intrinsic mitochondrial pathway. This indicates that CALB2 may be an important mediator of 5-FU-induced cell death. Moreover, down-regulation of CALB2 in response to 5-FU may represent an intrinsic mechanism of resistance to this anti-cancer drug.

Show MeSH
Related in: MedlinePlus