Increased expression of SRPK1 (serine/arginine-rich protein-specific kinase 1) is associated with progression and unfavorable prognosis in cervical squamous cell carcinoma

Figures & data

Figure 1. mRNA and protein expression of SRPK1 in CESC samples.

(a) The mRNA level of SRPK1 was exhibited as transcripts per million (TPM), which was retrieved from TCGA database. Each red dot represents one sample data of CESC (n = 306), each green dot represent one sample data from normal cervix (n = 13). (b) Patients in TCGA database was divided to high-SRPK1 group (n = 146) and low-SRPK1 group (n = 145). Kaplan–Meier method was used to generate the disease-free survival curve according to the mRNA level of SRPK1. (c) Similarly, the overall survival curves were plotted and tested via log-rank test, which revealed that higher SRPK1 TPM level indicates poorer overall survival (P = 0.018). (d) Representative IHC images showing the high SRPK1 (left panel) and low SRPK1 (right panel) staining in CESC tissues. Magnification: 400X.

Table 1. Correlation between SRPK1 protein expression and clinicopathologic characteristics of CSCC patients

Variables	Cases (n = 122)	SRPK1 protein level		P
		Low (n = 54)	High (n = 68)
Age (year)
< 47	53	24	29	0.856
≥ 47	69	30	39
HPV infection
Negative	17	6	11	0.600
Positive	105	48	57
Horizontal diffusion diameter
< 4.0 cm	78	42	36	0.005*
≥ 4.0 cm	44	12	32
Stromal invasion depth
< 2/3	63	26	37	0.585
≥ 2/3	59	28	31
Vagina invasion
Negative	94	42	52	0.999
Positive	28	12	16
Parametrial invasion
Negative	96	48	48	0.015*
Positive	26	6	20
Lymphovascular invasion
Negative	82	41	41	0.082
Positive	40	13	27
Lymph node metastasis
Negative	78	42	36	0.005*
Positive	44	12	32
FIGO stage
Stage I	74	47	27	<0.001*
Stage II	48	7	41

P value was analyzed by Fisher Exact test. * indicates P < 0.05 with statistical significance.

The average diagnostic age of our cohort was 47.2 years old, therefore we chose 47 years old as the cutoff for age. As for the horizontal diffusion tumor size, we chose 4.0 cm as the cutoff because it is a critical number for cervical cancer FIGO staging

Figure 2. Disease-free survival analyses.

Kaplan–Meier method was utilized to evaluate the prognostic significances of all variables, including age (a), HPV infection (b), horizontal diffusion diameter (c), stromal invasion depth (d), vagina invasion (e), parametrial invasion (f), lymphovascular invasion (g), lymph node metastasis (h), FIGO stage (i), and SRPK1 expression (j). Data was analyzed by Kaplan–Meier method, and survival curves were compared by long-rank test. * P < 0.05.

Table 2. Disease-free survival (DFS) information of enrolled CSCC patients

Variables	Cases(n = 122)	Univariate analysis			Multivariate analysis
		5-year DFS rate (%)	Median DFS time (months)	P	HR (95% CI)	P
Age (year)
< 47	53	45.1%	59.0 ± 3.6	0.111
≥ 47	69	32.7%	48.0 ± 6.4
HPV infection
Negative	17	63.7%	70.0 ± 18.2	0.258
Positive	105	35.1%	54.0 ± 3.8
Horizontal diffusion diameter
< 4.0 cm	78	42.7%	58.0 ± 1.9	0.002*	Reference	0.014*
≥ 4.0 cm	44	33.3%	25.0 ± 6.0		1.96 (1.15–3.35)
Stromal invasion depth
< 2/3	63	37.6%	56.0 ± 5.1	0.470
≥ 2/3	59	39.0%	55.0 ± 8.8
Vagina invasion
Negative	94	39.9%	56.0 ± 4.1	0.081
Positive	28	30.1%	22.0 ± 1.1
Parametrial invasion
Negative	96	40.4%	57.0 ± 4.0	0.007*	Reference	0.028*
Positive	26	35.6%	26.0 ± 9.6		1.98 (1.08–3.64)
Lymphovascular invasion
Negative	82	47.6%	59.0 ± 6.8	<0.001*	Reference	<0.001*
Positive	40	16.6%	31.0 ± 11.2		2.69 (1.67–4.35)
Lymph node metastasis
Negative	78	53.1%	70.0 ± 12.8	<0.001*	Reference	0.002*
Positive	44	14.9%	33.0 ± 5.6		2.35 (1.37–4.02)
FIGO stage
Stage I	74	54.8%	70.0 ± 5.7	<0.001*	Reference	0.036*
Stage II	48	6.1%	26.0 ± 6.2		1.90 (1.04–3.47)
SRPK1 expression
Low	54	59.6%	71.0 ± 3.9	<0.001*	Reference	0.047*
High	68	12.6%	41.0 ± 5.5		1.88 (1.01–3.50)

P value was analyzed by log-rank test. * indicates P < 0.05 with statistical significance.

Table 3. Overall survival (OS) information of enrolled CSCC patients

Variables	Cases(n = 122)	Univariate analysis			Multivariate analysis
		5-year OS rate (%)	Median OS time (months)	P	HR (95% CI)	P
Age (year)
< 47	53	58.9%	83.0 ± 17.1	0.204
≥ 47	69	51.8%	62.0 ± 5.5
HPV infection
Negative	17	70.6%	99.0 ± 0	0.369
Positive	105	52.9%	66.0 ± 4.8
Horizontal diffusion diameter
< 4.0 cm	78	64.1%	72.0 ± 5.1	0.008*	Reference	0.053
≥ 4.0 cm	44	38.6%	36.0 ± 11.2		1.77 (0.99–3.16)
Stromal invasion depth
< 2/3	63	60.4%	69.0 ± 10.5	0.175
≥ 2/3	59	48.8%	59.0 ± 9.5
Vagina invasion
Negative	94	59.2%	69.0 ± 5.4	0.060
Positive	28	39.8%	30.0 ± 20.1
Parametrial invasion
Negative	96	59.6%	72.0 ± 7.3	0.006*	Reference	0.023*
Positive	26	34.9%	47.0 ± 13.4		2.10 (1.11–3.96)
Lymphovascular invasion
Negative	82	64.3%	80.0 ± 7.4	<0.001*	Reference	<0.001*
Positive	40	34.6%	46.0 ± 11.9		2.90 (1.71–4.92)
Lymph node metastasis
Negative	78	65.0%	83.0 ± 9.7	<0.001*	Reference	0.005*
Positive	44	35.9%	43.0 ± 5.9		2.30 (1.30–4.10)
FIGO stage
Stage I	74	72.3%	80.0 ± 7.1	<0.001*	Reference	0.044*
Stage II	48	22.0%	41.0 ± 5.5		1.26 (1.02–2.49)
SRPK1 expression
Low	54	69.7%	80.0 ± 7.4	0.001*	Reference	0.042*
High	68	41.3%	54.0 ± 8.4		1.87 (1.03–3.67)

P value was analyzed by log-rank test. * indicates P < 0.05 with statistical significance.

Figure 3. Overexpressing SRPK1 promotes CESC proliferation, migration, and invasion.

(a) The transfection efficiencies were tested via Western blot in both C-33A and SW756 cells. (b) MTT assays were used to plot the cell proliferation curves, showing the significant effect of SRPK1 on facilitating CESC cell proliferation. (c) Transwell experiments demonstrated that SRPK1-transfection can enhance CESC migration capacity. (d) Matrigel-Transwell data revealed the role of SRPK1 on promoting CESC invasion.Data were obtained from three independent repeats and presented as mean + SD. * P < 0.05 by Student’s t-test.

Figure 4. SRPK1 interference results in attenuated CESC viability.

(a) Knockdown efficiencies of shRNAs were tested via Western blot in both C-33A and SW756 cells. (b) MTT assays showed significant effects of SRPK1-shRNAs on inhibiting CESC cell proliferation. (c) Transwell data demonstrated that silencing SRPK1 suppressed CESC migration. (d) Matrigel-Transwell results validated the invasion-suppressing role of SRPK1 interference. Data were obtained from three independent repeats and presented as mean + SD. * P < 0.05.