High expression of proenkephalin is associated with favorable outcomes in patients with gastrointestinal stromal tumors

Figures & data

Table 1 Clinicopathological characteristics of 268 GIST patients

Clinicopathological characteristic	Patients, n (%)
Age^a (year)
≤58	130(48.5%)
>58	138(51.5%)
Gender
Male	143(53.4%)
Female	125(%)
Tumor site
Stomach	150(56%)
Small bowel	84(31.3%)
Colon	9(3.4%)
Other	25(9.3%)
Tumor size (cm)
≤2	13(4.9%)
>2&≤5	101(37.7%)
>5&≤10	97(36.2%)
>10	57(21.2%)
Mitosis count per 50 HPFs
≤5	181(67.5%)
>5&≤10	45(16.8%)
>10	42(15.7%)
Modified NIH risk grade
Very low	12(4.5%)
Low	91(34%)
Intermediate	43(16%)
High	122(45.5%)
Tumor rupture
Yes	41(15.3%)
No	227(74.7%)
Tumor mutation type
KIT exon 11	89(33.2%)
KIT exon 9	10(3.7%)
PDGFRA	6(2.3%)
PDGFRA D842V	5(1.9%)
KIT/PDGFRA wild type	9(3.4%)
Not analyzed	154(57.5%)
Imatinib treatment
Yes	55(20.5%)
No	213(79.5%)
Follow-up duration, months
Median (range)	79.5(3–149)

Notes: ^aThe median age of the enrolled GIST patients was 58, and the range was 23 to 87.

Abbreviations: GIST, gastrointestinal stromal tumor; HPF, high-power fields; NIH, National Institutes of Health.

Table 2 Clinicopathological characteristics of 268 GIST patients grouped by PENK expression

Clinicopathological characteristic	n	PENK		P-value
		Negative (%)	Positive (%)
Age (year)				0.588
≤58	130	87(32.5)	43(16.0)
>58	138	88(32.8)	50(18.7)
Gender				0.676
Male	143	95(35.4)	48(17.9)
Female	125	80(29.9)	45(16.8)
Tumor site				0.106
Stomach	150	91(34.0)	59(22.0)
Small bowel	84	58(21.6)	26(9.7)
Colon	9	6(2.2)	3(1.1)
Other	25	16(6.0)	9(3.3)
Tumor size (cm)				0.001**
≤10	211	127(47.4)	84(31.3)
>10	57	48(17.9)	9(3.3)
Mitosis count per 50 HPFs				＜0.001**
≤5	181	96(35.8)	85(31.7)
>5	87	79(29.5)	8(3.0)
Tumor rupture				0.026*
Yes	41	33(12.3)	8(3.0)
No	227	142(53.0)	85(31.7)
Modified NIH risk grade				＜0.001**
Very low or low	103	38(14.2)	65(24.3)
Intermediate	43	23(8.6)	20(7.5)
High	122	110(41.0)	12(4.5)

Notes: Pearson chi square tests and one-way ANOVA were used to compare the associations between PENK expression and the clinicopathological variables. *P<0.05; **P<0.01.

Abbreviations: GIST, gastrointestinal stromal tumor; HPF, high-power field; NIH, National Institutes of Health; PENK, proenkephalin.

Figure 1 PENK expression detected in GIST tissues by immunohistochemical staining.

Notes: (A) Negative, (B) weak positive, (C) moderate, and (D) strong positive PENK staining in GIST tissues.

Abbreviations: GIST, gastrointestinal stromal tumor; PENK, proenkephalin.

Figure 2 PENK expression in GIST tissues detected by qRT-PCR and WB.

Notes: (A) Relative mRNA expression levels of PENK in the low- and intermediate-risk groups were significantly higher than that in the high-risk group (P=0.004 and P=0.012, respectively). (B, C) WB analysis showed that PENK protein expression levels in the low- and intermediate-risk groups were higher than that in the high-risk group (P=0.002 and P=0.008, respectively). However, there was no significant difference between the low- and intermediate-risk groups (P=0.166). GAPDH was included as a loading control.

Abbreviations: GAPDH, glyceraldehyde phosphate dehydrogenase; GIST, gastrointestinal stromal tumor; PENK, proenkephalin; qRT-PCR, quantitative real-time polymerase chain reaction; WB, Western blotting.

Table 3 Univariate and multivariate analyses of predictors of OS in 268 GIST patients

Variable	Univariate			Multivariate
	HR	95%CI	P-value	HR	95%CI	P-value
Age (≤58, >58)	1.409	0.698–2.536	0.312	1.465	0.681–2.735	0.310
Gender (male, female)	0.963	0.476–1.998	0.039*	1.201	0.458–2.340	0.112
Tumor site (stomach, other)	1.740	1.087–2.715	0.035*	3.309	1.901–5.213	0.271
Tumor size (≤10cm, >10cm)	3.297	2.298–4.830	0.001**	3.167	1.428–5.116	＜0.001**
Mitosis count (≤5/50 HPFs, >5/50 HPFs)	3.615	2.866–5.981	0.000**	4.527	2.270–7.158	＜0.001**
Tumor rupture (no, yes)	3.226	2.259–5.672	0.038*	8.210	4.614–13.992	0.048*
PENK (positive, negative)	1.460	1.300–1.897	0.000**	1.596	1.006–2.914	＜0.001**

Notes: *P<0.05; **P<0.01. 95%CI, 95% confidence interval.

Abbreviations: GIST, gastrointestinal stromal tumor; HPF, high-power field; HR, hazard ratio; OS, overall survival; PENK, proenkephalin.

Table 4 Univariate and multivariate analyses of predictors of RFS in 268 GIST patients

Variable	Univariate			Multivariate
	HR	95%CI	P-value	HR	95%CI	P-value
Age (≤58, >58)	1.612	0.769–2.755	0.410	1.827	1.012–3.136	0.536
Gender (male, female)	1.157	0.598–2.362	0.056	1.670	0.458–3.610	0.326
Tumor site (stomach, other)	2.078	0.827–3.610	0.042*	4.005	1.744–7.035	0.620
Tumor size (≤10cm, >10cm)	4.863	3.210–7.853	0.006**	4.278	2.029–7.080	0.001*
Mitosis count (≤5/50 HPFs, >5/50 HPFs)	4.211	3.900–6.899	0.000**	5.109	3.664–8.002	＜0.001**
Tumor rupture (no, yes)	4.138	1.186–8.002	0.022*	10.104	7.014–13.871	0.037*
PENK (positive, negative)	1.956	1.515–2.897	0.000**	1.910	0.977–3.089	＜0.001**

Notes: *P<0.05; **P<0.01. 95%CI, 95% confidence interval.

Abbreviations: GIST, gastrointestinal stromal tumor; HPF, high-power field; HR, hazard ratio; PENK, proenkephalin; RFS, recurrence-free survival.

Figure 3 Prognostic value of PENK expression in 268 GISTs was assessed using the Kaplan-Meier method and the log-rank test.

Notes: Comparisons of (A) OS (P=0.001) and (B) RFS (P=0.001) among low-, intermediate-, and high-risk NIH grades. Comparisons of (C) OS (P=0.034) and RFS (P=0.033) between PENK-negative and PENK-positive groups.

Abbreviations: GIST, gastrointestinal stromal tumor; NIH, National Institutes of Health; OS, overall survival; PENK, proenkephalin; RFS, recurrence-free survival.