E3 ubiquitin ligase Smurf2: a prognostic factor in microsatellite stable colorectal cancer

Figures & data

Table 1 Overview of clinical parameters and expression of Smurf2

Patient characteristics	n	Median expression
		Smurf2	P-value
Gender
Male	57	1.729	0.071
Female	41	1.000
Age at operation
Median <67 years	47		0.864
Median ≥67 years	51
T stage
T1	1	–	0.682
T2	13	0.888
T3	68	1.214
T4	16	1.028
N stage
N0	45	1.117	0.187
N1	24	1.568
N2	29	0.901
M stage
M0	63	1.006	0.516
M1	35	1.681
M stage (MSS tumors)
M0	35	0.747	0.024
M1	23	1.474
Tumor grade
G1	3	0.611	0.893
G2	63	1.205
G3	26	0.904
n/a	6	0.767
Colorectal liver metastases
Synchronous	31	1.474	0.342
Metachronous	6	0.760
Resection margin status
R0	89	1.071	0.909
R1	6	1.538
R2	3	2.770
Tumor site
Sigmoid	21	1.013	0.732
Rectum	33	1.000
Rectosigmoid	4	2.058
Colon descendens	8	1.687
Colon transversum	2	13.170
Colon ascendens	16	1.330
Caecum	14	1.340
Surgical procedure
High anterior resection	8	0.848	0.474
Low anterior resection	26	0.936
Sigmoidectomie	12	1.284
Left colectomy	14	1.687
Right colectomy	30	1.340
Abdominoperineal resection	5	1.071
Subtotal colectomy	2	13.170
Pelvic exenteration	1	–
Neoadjuvant therapy
Yes	13	1.125	0.230
No	85	0.611
Anastomotic leakage
Yes	12	1.003	0.983
No	86	1.153
Microsatellite status
MSS	58	0.898	0.006*
MSI	11	2.462
Recurrence
Yes	17	0.773	0.320
No	81	1.117

Note: P<0.05 was considered statistically significant.

Abbreviations: MSI, microsatellite instable; MSS, microsatellite stable; n/a, not available.

Figure 1 Transcript expression levels of Smurf2 in colorectal cancer tissue and corresponding healthy mucosa (n=98).

Notes: Smurf2 was significantly overexpressed in colorectal cancer specimens compared to corresponding healthy mucosa. Bars represent mean + SEM. **P=0.003.

Abbreviation: SEM, standard error of the mean.

Figure 2 (A) Smurf2 expression dependent on patients’ microsatellite status. Patients with microsatellite stable (MSS) tumors (n=58) displayed a significantly lower expression of Smurf2 than patients with microsatellite instable (MSI) tumors (n=11; P=0.006). (B) Within the 58 MSS tumors, Smurf2 expression was significantly higher in M1 staged patients vs M0 (P=0.024).

Figure 3 Representative immunohistochemistry revealing spatial localization of Smurf2 protein (40 × magnification).

Notes: Smurf2 was strongly expressed in the tumor cells (A), particularly in the cytoplasm (arrowheads), whereas healthy mucosa cells (B) only showed a very weak expression of Smurf 2.

Figure 4 (A) Correlation of Smurf2 expression and overall survival of the entire patient cohort revealed no significant difference between Smurf2 high and Smurf2 low tumors (n=98) (P=0.86). (B) Correlation of Smurf2 with microsatellite status and overall survival. Overall survival was significantly impaired in microsatellite stable (MSS) patients expressing high levels of Smurf2 (n=58) (*P=0.044).

Figure 5 Invasion (A) and migration (B) assays.

Notes: Smurf2 siRNA-transfected SW-480 cells were both significantly less invasive (*P=0.012) and migrative (*P=0.011); DLD-1 cells revealed significantly reduced invasive potential (*P=0.013). Bars represent mean + SEM.

Abbreviation: SEM, standard error of the mean.