The membrane cytoskeletal crosslinker ezrin is required for metastasis of breast carcinoma cells

Breast Cancer Research

Table 1 Expression of amino-terminal ezrin inhibits metastasis of breast carcinoma cells

Cell line^a	Transfected with	Primary tumour takes (%)	Day of 1 cm tumour diameter^b	Day of sacrifice	Metastasis (%)^c
SP1	None	100% (13/13)	24 ± 7	35	23% (3/13)
AC2M2	None	100% (11/11)	30 ± 5	41	90% (10/11)^†
pCB6	Vector	100% (8/8)	33 ± 4	39	88% (7/8)
WTC4	WT ezrin	100% (7/7)	28 ± 4	41	88% (6/7)
WTC6	WT ezrin	100% (15/15)	26 ± 2	39	87% (13/15)
NTC6	N-term ezrin	38% (3/8)	40 ± 10*	47	0% (0/8)^‡
NTC7	N-term ezrin	100% (8/8)	28 ± 1	39	38% (3/8)^‡
NTB8^d	N-term ezrin	100% (5/5)	29 ± 3	41	0% (0/5)^‡

^aPoorly metastatic parental SP1 cells or highly metastatic variant AC2M2 cells alone, or transfected with empty pCB6 vector, or a vector encoding wild-type (WT) ezrin or amino-terminal (N-term) ezrin, were transplanted (7.5 × 10³ cells) into the mammary fat pad of syngeneic mice (see text). ^bDay to 1 cm tumour diameter was calculated by linear regression analysis of data from individual mice. Values are expressed as mean ± standard deviation. Clone NTC6 showed a significant increase (*) in the day of 1 cm tumour diameter compared with WTC4 and WTC6 (P = 0.012). Mice with NTC6 tumours were therefore killed approximately 1 week later to allow tumour growth to a comparable size. ^cAC2M2 cells showed significantly more metastases than did the parental SP1 cells (^† P = 0.003; Fisher's exact test). Pooled results from three N-term ezrin expressing clones showed a significant reduction in metastases compared with two WT ezrin expressing clones (^‡ P < 0.0001). Individual P values for NTC6, NTC7 and NTB8 are as follows (respectively): <0.0001, 0.002 and 0.002. ^dNTB8 is an N-term ezrin-expressing clone derived from an independent transfection of AC2M2 cells, and was transplanted as described above.

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