miR-19b serves as a prognostic biomarker of breast cancer and promotes tumor progression through PI3K/AKT signaling pathway

Figures & data

Table 1 Association of miR-19b with the clinicopathological features of breast cancer patients

Features	Total N=124	miR-19b expression		P-value
		Low (n=56)	High (n=68)
Age (years)				0.647
≤50	46	22	24
>50	78	34	44
Tumor size (cm)				0.470
≤3	62	30	32
>3	62	26	36
ER expression				0.342
Negative	74	36	38
Positive	50	20	30
PR expression				0.284
Negative	71	35	36
Positive	53	21	32
HER-2 expression				0.075
Negative	78	40	38
Positive	46	16	30
Distant metastasis				0.010*
Negative	85	45	40
Positive	39	11	28
TNM stage				0.004*
I–II	62	36	26
III–IV	62	20	42

Note:

* P<0.05.

Abbreviations: miR-19b, microRNA-19b; ER, estrogen receptor; PR, progesterone receptor.

Figure 1 Expression of miR-19b, measured by qRT-PCR, in breast cancer tissues and cell lines.

Notes: (A) miR-19b expression was upregulated in breast cancer tissues compared with adjacent normal controls (***P<0.001). (B) The expression of miR-19b was higher in the breast cancer cell lines than that in the normal breast cells (*P<0.05, **P<0.01 and ***P<0.001).
Abbreviations: miR-19b, microRNA-19b; qRT-PCR, quantitative real time PCR.

Table 2 Multivariate Cox regression analysis for miR-19b in breast cancer patients

Variables	Multivariate analysis
	HR	95% CI	P-value
miR-19b	2.560	1.130–5.796	0.024*
Age (years)	1.129	0.581–2.193	0.721
Tumor size	1.061	0.535–2.104	0.866
ER expression	1.084	0.524–2.245	0.828
PR expression	1.004	0.516–1.954	0.991
HER-2 expression	1.015	0.510–2.020	0.967
Distant metastasis	1.351	0.629–2.902	0.441
TNM stage	2.079	1.033–4.186	0.040*

Note:

* P<0.05.

Abbreviations: miR-19b, microRNA-19b; ER, estrogen receptor; PR, progesterone receptor.

Figure 2 Kaplan–Meier survival analysis of breast cancer patients based on the expression of miR-19b.

Note: Patients with high miR-19b expression had a shorter survival time than those with low miR-19b expression (log-rank P=0.002).
Abbreviation: miR-19b, microRNA-19b.

Figure 3 Effects of miR-19b on cell proliferation, migration, and invasion in MCF-7 and MDA-MB-231 cells.

Notes: (A) In the two cell lines, expression of miR-19b was significantly increased by miR-19b mimic but was decreased by miR-19b inhibitor compared with the corresponding NCs (***P<0.001). (B) Cell proliferation was enhanced by overexpression of miR-19b but was suppressed by knockdown of miR-19b in both MCF-7 and MDA-MB-231 cells (*P<0.05 and **P<0.01). (C) The results of migration analysis for MCF-7 and MDA-MB-231 cells. (D) The results of invasion assay for MCF-7 and MDA-MB-231 cells. (E, F) Overexpression of miR-19b by miR-19b mimic could promote the cell migration and invasion, but the downregulated miR-19b expression could inhibit the cell migration and invasion (*P<0.05, **P<0.01, and ***P<0.001).
Abbreviations: miR-19b, microRNA-19b; NC, negative control.

Figure 4 PI3K/AKT signaling pathway was regulated by miR-19b expression in breast cancer cells.

Notes: (A) The Western blot results of proteins involved in PI3K/AKT signaling pathway in MCF-7 cells. (B) The Western blot results of proteins involved in PI3K/AKT signaling pathway in MDA-MB-231 cells. (C–G) The densitometric analysis for the blots revealed that the protein expression levels of p-PI3K, p-AKT, and CCND1 were elevated by miR-19b overexpression but were decreased by reduction of miR-19b in both MCF-7 and MDA-MB-231 cells. The total PI3K and AKT protein expression had no obvious alterations (*P<0.05).
Abbreviations: miR-19b, microRNA-19b; NC, negative control.

Figure 5 Schematic model of miR-19b-mediated promotion of progression of breast cancer.

Abbreviation: miR-19b, microRNA-19b.