Expression and mutational analyses of the humanMAD2L1 gene in breast cancer cells

Abstract

Breast cancer is a heterogeneous disorder in which most tumors display some degree of aneuploidy, especially those at later stages of the disease. Aneuploidy and associated chromosome instability may be important in the progression of mammary tumorigenesis. Aneuploidy is prevented during normal cell division in part through regulation of a mitotic spindle checkpoint where mitotic arrest prevents segregation of misaligned chromosomes into daughter cells at anaphase. Mitotic arrest genes, including the MAD family, which was originally characterized in yeast, help regulate normal function of the mitotic spindle checkpoint. Decreased expression of the human gene MAD2L1 was previously reported in a breast cancer cell line exhibiting chromosome instability and aneuploidy. To explore further the potential role of MAD2L1 in breast cancer, we analyzed MAD2L1 gene expression in 13 minimally to grossly aneuploid human breast cancer cell lines and found significant differences of expression in three lines. Sequence analysis of MAD2L1 cDNA in these as well as nine additional aneuploid breast cancer and five immortalized normal human mammary epithelial cell lines revealed one heterozygous frameshift (572 del A) mutation in a cancer cell line that demonstrated a high level of transcript expression. In addition, two 3′UTR sequence variants were noted in breast cancer cell lines. The 572 del A mutation creates a truncated MAD2 protein product. Further functional studies in primary breast tumors are therefore warranted to determine the potential role MAD2L1 may play in breast cancer. © 2000 Wiley‐Liss, Inc.

Overexpression of the mitotic checkpoint genes BUB1, BUBR1 , and BUB3 in gastric cancer—association with tumour cell proliferation

“…No correlation between ploidy state and BUB transcript expression levels was found. This result is in keeping with an expression study of another checkpoint protein, MAD2L1, in breast cancer cells 40.…”

Overexpression of the mitotic checkpoint genes BUB1, BUBR1 , and BUB3 in gastric cancer—association with tumour cell proliferation

“…No correlation between ploidy state and BUB transcript expression levels was found. This result is in keeping with an expression study of another checkpoint protein, MAD2L1, in breast cancer cells 40.…”

Systems biomedicine of primary and metastatic colorectal cancer reveals potential therapeutic targets

“…Increasement in the level of BUB1B and MAD2L1 transcripts was detected in a large number of samples of the ductal breast carcinoma [60]. MAD2L1 inhibits APC (anaphase-promoting complex), but is absent when chromosomes are correctly aligned on the metaphase plate [61]. Its upregulation in our analysis would provide evidence that cancerous cells were dealing with mitotic deficiencies.…”

Mad2 Overexpression Promotes Aneuploidy and Tumorigenesis in Mice

“…Indeed, we and others have observed a threshold for cell viability in cell culture and animal models as high level of expression of Mad2 (this study), complete loss of separase in mice (Kumada et al, 2006;Wirth et al, 2006) and complete loss of mitotic checkpoint function all lead to a profound cell death and early embryonic lethality (Babu et al, 2003;Dobles et al, 2000;Kops et al, 2004;Wang et al, 2004). It is likely for this reason that no human tumors to date have been identified which have sustained a complete loss of Mad2 function, although partial loss of function has been observed (Percy et al, 2000;Wang et al, 2002;Wang et al, 2000). It will be of interest to see if separase heterozygous mice will develop tumors with prolonged latency.…”

Overexpression of the mitotic checkpoint genes BUB1, BUBR1 , and BUB3 in gastric cancer—association with tumour cell proliferation

“…No correlation between ploidy state and BUB transcript expression levels was found. This result is in keeping with an expression study of another checkpoint protein, MAD2L1, in breast cancer cells 40.…”

Systems biomedicine of primary and metastatic colorectal cancer reveals potential therapeutic targets

“…Increasement in the level of BUB1B and MAD2L1 transcripts was detected in a large number of samples of the ductal breast carcinoma [60]. MAD2L1 inhibits APC (anaphase-promoting complex), but is absent when chromosomes are correctly aligned on the metaphase plate [61]. Its upregulation in our analysis would provide evidence that cancerous cells were dealing with mitotic deficiencies.…”

Mad2 Overexpression Promotes Aneuploidy and Tumorigenesis in Mice

“…Indeed, we and others have observed a threshold for cell viability in cell culture and animal models as high level of expression of Mad2 (this study), complete loss of separase in mice (Kumada et al, 2006;Wirth et al, 2006) and complete loss of mitotic checkpoint function all lead to a profound cell death and early embryonic lethality (Babu et al, 2003;Dobles et al, 2000;Kops et al, 2004;Wang et al, 2004). It is likely for this reason that no human tumors to date have been identified which have sustained a complete loss of Mad2 function, although partial loss of function has been observed (Percy et al, 2000;Wang et al, 2002;Wang et al, 2000). It will be of interest to see if separase heterozygous mice will develop tumors with prolonged latency.…”

Overexpression of the mitotic checkpoint genes BUB1, BUBR1 , and BUB3 in gastric cancer—association with tumour cell proliferation

“…No correlation between ploidy state and BUB transcript expression levels was found. This result is in keeping with an expression study of another checkpoint protein, MAD2L1, in breast cancer cells 40.…”

Systems biomedicine of primary and metastatic colorectal cancer reveals potential therapeutic targets

“…Increasement in the level of BUB1B and MAD2L1 transcripts was detected in a large number of samples of the ductal breast carcinoma [60]. MAD2L1 inhibits APC (anaphase-promoting complex), but is absent when chromosomes are correctly aligned on the metaphase plate [61]. Its upregulation in our analysis would provide evidence that cancerous cells were dealing with mitotic deficiencies.…”

Mad2 Overexpression Promotes Aneuploidy and Tumorigenesis in Mice

“…Indeed, we and others have observed a threshold for cell viability in cell culture and animal models as high level of expression of Mad2 (this study), complete loss of separase in mice (Kumada et al, 2006;Wirth et al, 2006) and complete loss of mitotic checkpoint function all lead to a profound cell death and early embryonic lethality (Babu et al, 2003;Dobles et al, 2000;Kops et al, 2004;Wang et al, 2004). It is likely for this reason that no human tumors to date have been identified which have sustained a complete loss of Mad2 function, although partial loss of function has been observed (Percy et al, 2000;Wang et al, 2002;Wang et al, 2000). It will be of interest to see if separase heterozygous mice will develop tumors with prolonged latency.…”