Association between Bmi1 and clinicopathological status of esophageal squamous cell carcinoma

Table 1 Associations of Bmi-1 mRNA expression in ESCC tissues with clinicopathological characteristics (mean ± SD)

Parameter	Bmi-1 mRNA	P
Age (yr)
≥ 60	2.312 ± 2.171	0.3816
< 60	2.167 ± 2.045
Gender
Male	2.402 ± 2.359	0.2133
Female	1.770 ± 1.690
Lymph node metastases
Yes	3.580 ± 2.487	0.0003
No	1.703 ± 0.758
Stage
III/IV	3.827 ± 2.673	0.0001
I/II	1.590 ± 0.735
Histological grade
I	0.881 ± 0.418	0.000
II	1.858 ± 0.979
III	3.580 ± 2.487

Quantitative real-time PCR was employed to identify Bmi1 mRNA expression. The comparative expression levels were determined as a ratio between Bmi1 and housekeeping gene (β-actin) to correct variation in the amount of mRNA.

Table 2 Relationship between Bmi-1 protein expression in ESCC tissues and clinicopathological status

Parameter	> 50%	10%-50%	< 10%	P
Age (yr)
≥ 60	23	9	4	0.784
< 60	21	7	6
Histological grade
I	7	3	3	0.079
II	28	5	6
III	9	8	1
Lymph node metastases
+	11	9	3	0.073
-	33	7	7
Stage
III/IV	9	4	1	0.691
I/II	35	12	9
Location
Nucleus	0	7	8	0.000
Cytoplasm	30	18	16
Both nucleus and cytoplasm	5	15	20

ESCC was subjected to immunohistochemistry using antibodies to Bmi1. χ² test was used to detect the difference between Bmi1 oncoprotein and clinicopathological status.