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Genomic analysis and selective small molecule inhibition identifies BCL-X(L) as a critical survival factor in a subset of colorectal cancer.

Zhang H, Xue J, Hessler P, Tahir SK, Chen J, Jin S, Souers AJ, Leverson JD, Lam LT - Mol. Cancer (2015)

Bottom Line: Because cancer types with BCL2 and MCL1 amplification are more prone to inhibition of their respectively encoded proteins, we hypothesized that cancers with a significant frequency of BCL2L1 amplification would have greater dependency on BCL-X(L) for survival.Silencing the expression of BCL-X(L) via siRNA killed the cell lines that were sensitive to A-1155463 while having little effect on lines that were resistant.This work demonstrates the utility of characterizing frequent genomic alterations to identify cancer survival genes.

View Article: PubMed Central - PubMed

Affiliation: Oncology Research, AbbVie, 1 N Waukegan Road, North Chicago, IL, 60064-6101, USA. Haichao.zhang@abbvie.com.

ABSTRACT

Background: Defects in programmed cell death, or apoptosis, are a hallmark of cancer. The anti-apoptotic B-cell lymphoma 2 (BCL-2) family proteins, including BCL-2, BCL-X(L), and MCL-1 have been characterized as key survival factors in multiple cancer types. Because cancer types with BCL2 and MCL1 amplification are more prone to inhibition of their respectively encoded proteins, we hypothesized that cancers with a significant frequency of BCL2L1 amplification would have greater dependency on BCL-X(L) for survival.

Methods: To identify tumor subtypes that have significant frequency of BCL2L1 amplification, we performed data mining using The Cancer Genome Atlas (TCGA) database. We then assessed the dependency on BCL-X(L) in a panel of cell lines using a selective and potent BCL-X(L) inhibitor, A-1155463, and BCL2L1 siRNA. Mechanistic studies on the role of BCL-X(L) were further undertaken via a variety of genetic manipulations.

Results: We identified colorectal cancer as having the highest frequency of BCL2L1 amplification across all tumor types examined. Colorectal cancer cell lines with BCL2L1 copy number >3 were more sensitive to A-1155463. Consistently, cell lines with high expression of BCL-XL and NOXA, a pro-apoptotic protein that antagonizes MCL-1 activity were sensitive to A-1155463. Silencing the expression of BCL-X(L) via siRNA killed the cell lines that were sensitive to A-1155463 while having little effect on lines that were resistant. Furthermore, silencing the expression of MCL-1 in resistant cell lines conferred sensitivity to A-1155463, whereas silencing NOXA abrogated sensitivity.

Conclusions: This work demonstrates the utility of characterizing frequent genomic alterations to identify cancer survival genes. In addition, these studies demonstrate the utility of the highly potent and selective compound A-1155463 for investigating the role of BCL-X(L) in mediating the survival of specific tumor types, and indicate that BCL-X(L) inhibition could be an effective treatment for colorectal tumors with high BCL-X(L) and NOXA expression.

No MeSH data available.


Related in: MedlinePlus

Colon cancer cell lines with high BCL-XL and NOXA are more sensitive to BCL-XL inhibitor. a Protein expression of BCL-2 family members in colorectal cancer cell lines. BCL2L1 copy number gains >3 is indicated with + or -. b Protein and mRNA expression of BCL-XL, NOXA, MCL-1, and ratio of BCL-XL /MCL-1 in A-1155463-sensitive vs. resistant colorectal cancer cell lines
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Fig3: Colon cancer cell lines with high BCL-XL and NOXA are more sensitive to BCL-XL inhibitor. a Protein expression of BCL-2 family members in colorectal cancer cell lines. BCL2L1 copy number gains >3 is indicated with + or -. b Protein and mRNA expression of BCL-XL, NOXA, MCL-1, and ratio of BCL-XL /MCL-1 in A-1155463-sensitive vs. resistant colorectal cancer cell lines

Mentions: To determine if expression of BCL-2 family members plays a role in the sensitivity of colorectal cell lines to A-1155463, we collected lysates from these cell lines and performed western blotting analysis. Colorectal cell lines within our panel expressed varying levels of MCL-1 and BCL-XL (Fig. 3a). In general, there was an inverse relationship between the expression of MCL-1 versus NOXA and BCL-XL. We observed a strong correlation (0.68) between cell lines with BCL2L1 gain and BCL-XL protein expression. In addition, sensitive lines had higher protein expression of BCL-XL (p = 0.0002) and NOXA (p = 0.02), higher BCL-XL to MCL-1 ratio (p = 0.0027), and a trend towards lower expression of MCL-1, although not statistical significant (p = 0.12). The Pearson correlation between log EC50 and expression of BCL-XL, NOXA, MCL-1, and BCL-XL/MCL-1 was 0.75, 0.653, 0.363, and 0.637, respectively. The Spearman correlation between EC50 and expression of BCL-XL, NOXA, MCL-1, and BCL-XL/MCL-1 was 0.789, 0.749, 0.277, and 0.795, respectively. BCL-2 expression was detected in a single line, consistent with other studies showing that BCL-2 expression is less common in solid tumor cell lines [19]. To confirm these findings, we performed correlation analyses with mRNA expression data. There was a strong correlation between protein and mRNA expression for MCL-1 and BCL-XL. Additionally, sensitive lines had higher expression of BCL2L1 (p = 0.0078) and NOXA (p = 0.02), a higher BCL2L1 to MCL1 ratio (p = 0.0086), and a trend towards lower expression of MCL1 mRNA, although not statistical significant (p = 0.15) (Fig. 3b). The correlation coefficients for BCL2L1 and MCL1 versus sensitivity were −0.41 and 0.56, respectively, while the correlation coefficient for the BCL2L1 to MCL1 ratio was −0.56. These data indicate that BCL2L1 and NOXA expression may play important roles in determining sensitivity to selective BCL-XL inhibitors.Fig. 3


Genomic analysis and selective small molecule inhibition identifies BCL-X(L) as a critical survival factor in a subset of colorectal cancer.

Zhang H, Xue J, Hessler P, Tahir SK, Chen J, Jin S, Souers AJ, Leverson JD, Lam LT - Mol. Cancer (2015)

Colon cancer cell lines with high BCL-XL and NOXA are more sensitive to BCL-XL inhibitor. a Protein expression of BCL-2 family members in colorectal cancer cell lines. BCL2L1 copy number gains >3 is indicated with + or -. b Protein and mRNA expression of BCL-XL, NOXA, MCL-1, and ratio of BCL-XL /MCL-1 in A-1155463-sensitive vs. resistant colorectal cancer cell lines
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4487849&req=5

Fig3: Colon cancer cell lines with high BCL-XL and NOXA are more sensitive to BCL-XL inhibitor. a Protein expression of BCL-2 family members in colorectal cancer cell lines. BCL2L1 copy number gains >3 is indicated with + or -. b Protein and mRNA expression of BCL-XL, NOXA, MCL-1, and ratio of BCL-XL /MCL-1 in A-1155463-sensitive vs. resistant colorectal cancer cell lines
Mentions: To determine if expression of BCL-2 family members plays a role in the sensitivity of colorectal cell lines to A-1155463, we collected lysates from these cell lines and performed western blotting analysis. Colorectal cell lines within our panel expressed varying levels of MCL-1 and BCL-XL (Fig. 3a). In general, there was an inverse relationship between the expression of MCL-1 versus NOXA and BCL-XL. We observed a strong correlation (0.68) between cell lines with BCL2L1 gain and BCL-XL protein expression. In addition, sensitive lines had higher protein expression of BCL-XL (p = 0.0002) and NOXA (p = 0.02), higher BCL-XL to MCL-1 ratio (p = 0.0027), and a trend towards lower expression of MCL-1, although not statistical significant (p = 0.12). The Pearson correlation between log EC50 and expression of BCL-XL, NOXA, MCL-1, and BCL-XL/MCL-1 was 0.75, 0.653, 0.363, and 0.637, respectively. The Spearman correlation between EC50 and expression of BCL-XL, NOXA, MCL-1, and BCL-XL/MCL-1 was 0.789, 0.749, 0.277, and 0.795, respectively. BCL-2 expression was detected in a single line, consistent with other studies showing that BCL-2 expression is less common in solid tumor cell lines [19]. To confirm these findings, we performed correlation analyses with mRNA expression data. There was a strong correlation between protein and mRNA expression for MCL-1 and BCL-XL. Additionally, sensitive lines had higher expression of BCL2L1 (p = 0.0078) and NOXA (p = 0.02), a higher BCL2L1 to MCL1 ratio (p = 0.0086), and a trend towards lower expression of MCL1 mRNA, although not statistical significant (p = 0.15) (Fig. 3b). The correlation coefficients for BCL2L1 and MCL1 versus sensitivity were −0.41 and 0.56, respectively, while the correlation coefficient for the BCL2L1 to MCL1 ratio was −0.56. These data indicate that BCL2L1 and NOXA expression may play important roles in determining sensitivity to selective BCL-XL inhibitors.Fig. 3

Bottom Line: Because cancer types with BCL2 and MCL1 amplification are more prone to inhibition of their respectively encoded proteins, we hypothesized that cancers with a significant frequency of BCL2L1 amplification would have greater dependency on BCL-X(L) for survival.Silencing the expression of BCL-X(L) via siRNA killed the cell lines that were sensitive to A-1155463 while having little effect on lines that were resistant.This work demonstrates the utility of characterizing frequent genomic alterations to identify cancer survival genes.

View Article: PubMed Central - PubMed

Affiliation: Oncology Research, AbbVie, 1 N Waukegan Road, North Chicago, IL, 60064-6101, USA. Haichao.zhang@abbvie.com.

ABSTRACT

Background: Defects in programmed cell death, or apoptosis, are a hallmark of cancer. The anti-apoptotic B-cell lymphoma 2 (BCL-2) family proteins, including BCL-2, BCL-X(L), and MCL-1 have been characterized as key survival factors in multiple cancer types. Because cancer types with BCL2 and MCL1 amplification are more prone to inhibition of their respectively encoded proteins, we hypothesized that cancers with a significant frequency of BCL2L1 amplification would have greater dependency on BCL-X(L) for survival.

Methods: To identify tumor subtypes that have significant frequency of BCL2L1 amplification, we performed data mining using The Cancer Genome Atlas (TCGA) database. We then assessed the dependency on BCL-X(L) in a panel of cell lines using a selective and potent BCL-X(L) inhibitor, A-1155463, and BCL2L1 siRNA. Mechanistic studies on the role of BCL-X(L) were further undertaken via a variety of genetic manipulations.

Results: We identified colorectal cancer as having the highest frequency of BCL2L1 amplification across all tumor types examined. Colorectal cancer cell lines with BCL2L1 copy number >3 were more sensitive to A-1155463. Consistently, cell lines with high expression of BCL-XL and NOXA, a pro-apoptotic protein that antagonizes MCL-1 activity were sensitive to A-1155463. Silencing the expression of BCL-X(L) via siRNA killed the cell lines that were sensitive to A-1155463 while having little effect on lines that were resistant. Furthermore, silencing the expression of MCL-1 in resistant cell lines conferred sensitivity to A-1155463, whereas silencing NOXA abrogated sensitivity.

Conclusions: This work demonstrates the utility of characterizing frequent genomic alterations to identify cancer survival genes. In addition, these studies demonstrate the utility of the highly potent and selective compound A-1155463 for investigating the role of BCL-X(L) in mediating the survival of specific tumor types, and indicate that BCL-X(L) inhibition could be an effective treatment for colorectal tumors with high BCL-X(L) and NOXA expression.

No MeSH data available.


Related in: MedlinePlus