Overexpression of low-molecular-weight caldesmon is associated with aggressive phenotypes and epithelial-mesenchymal transition in breast cancer cells

Table 1 Breast cancer cell lines used in this study and their tumor origin[32,45]

Cell line	Tumor source	Breast cancer subtypes
MCF7	Adenocarcinoma of the mammary gland; cells were obtained from a metastatic site (pleural effusion)	Luminal A (ER+ and/or PR+ HER2-)
MDA-MB-361	Adenocarcinoma of the mammary gland; cells were obtained from a metastatic site (brain)	Luminal (ER+, PR-, and HER2+ amplified)
ZR-75-1	Ductal carcinoma of the mammary gland; cells were obtained from a metastatic site (ascites)	Luminal A (ER+ and/or PR+ HER2-)
CAL-51	Adenocarcinoma isolated from malignant pleural effusion of metastatic breast cancer, normal karyotype with genetic stability	Triple-negative (ER-, PR-, HER2-)
1001	Derived from parental MCF7 (MCF7/R-A1), which are cells exposed to increasing doses of recombinant TNF, transfected with p55 TNF receptor cDNA, mutation in R280K	Luminal A (ER+ and/or PR+ HER2-)
MDA-MB-231	Adenocarcinoma of the mammary gland, cells were obtained from the metastatic site; pleural effusion	Basal subtype receptor status: Triple-negative (ER-, PR- HER2-)
T47D	Ductal carcinoma of the mammary gland, cells were obtained from the metastatic site; pleural effusion	Luminal B (ER+ and/or PR+ HER2+/-)
BT-549	Ductal carcinoma of the mammary gland, cells were obtained from the mammary gland	Basal B subtype receptor status: Triple-negative (ER-, PR-, HER2-)

BC: Breast cancer; ER: Estrogen receptor; PR: Progesterone receptor; TNF: Tumor necrosis factor.

Table 2 Breast cancer samples and their pathological characteristics, n = 51

Variables	n (%)
Age in years
< 40	9 (18.0)
> 40	42 (82.0)
Tumor stage
1	None
2	15 (29.4)
3	32 (62.7)
4	4 (7.8)
Molecular subtype
Luminal A (E2+/PR+) HER2-	36 (70.6)
Luminal B (E2+/PR+) HER2+	4 (8.0)
HER2-enriched	6 (12.0)
Triple-negative	5 (10.0)
Ki-67 index
≤ 50%	21 (41.0)
> 50%	30 (59.0)
Lymphovascular invasion
No	29 (57.0)
Yes	22 (43.0)
In situ component
No	28 (55.0)
Yes	23 (45.0)

ER: Estrogen receptor; PR: Progesterone receptor.

Table 3 Low-molecular-weight isoform of caldesmon expression in breast cancer cases and its association with clinicopathological characteristics, n = 51, n (%)

Parameter	Category	Total	L-CAD-negative	L-CAD-positive	P value
Age in years	< 40	9 (18)	4	5	-
	≥ 40	42 (82)	19	23
Histological stage	Early: 1-2	15 (29)	6	9	-
	Late: 3-4	36 (71)	17	19
Ki-67 index	< 50%	21 (41)	11	10	-
	≥ 50%	30 (59)	12	18
Lymphatic invasion	Absent = 0	29 (57)	17	12	0.025865
	Present = 1	22 (43)	6	16
In situ component	Absent	28 (55)	16	12	0.056477
	Present	23 (45)	7	16
HER2 status	HER2+	10 (20)	2	8	0.000277
	HER2-	41 (80)	19	22
E2/PR	E2+/PR+	31 (61)	16	15	0.005555
	E2+/PR-	3 (6)	2	1
	E2-/PR+	5 (10)	2	3
	E2-/PR-	12 (24)	2	10

Immunohistochemistry was performed on 51 formalin-fixed, paraffin-embedded breast cancer specimens using a semi-quantitative scoring system. P values were calculated using MS Excel and the Vassar Stats Web-based statistical program. All P values were two-tailed, and P values < 0.05 were considered statistically significant. ER: Estrogen receptor; l-CAD: Low-molecular-weight isoform of caldesmon; PR: Progesterone receptor.