Clinicopathological data
Among the 44 patients studied, 21 (61%) were men and 17 (39%) were women, with a mean age of 65 years (range, 53 to 82 years). Total gastrectomy was performed in 21 patients and distal subtotal gastrectomy in 23 patients. Thirty-six patients had H. pylori infection. The histological examination after surgery showed 5 cases of mucinous type, 29 cases of tubular type, 1 case of signet-ring cell carcinoma, and 9 cases of others. Twenty-five (57%) of the studied tumors were classified as moderately differentiated type and 19 (43%) as poorly differentiated type. According to TNM classification, 15 (34%) were of limited (T1/2) extent and 29 (66%) were locally advanced (T3/4). By pathological and clinical assessment, the majority of patients had lymphatic metastases (N1-N3; 73%). In contrast, only 4 cases had distant metastases (M1) at the time of surgery. Twenty-three cases showed presence of lymphatic tumor emboli. Five (11%) cases had stage I disease, 17 (39%) had stage II disease, 18 (41%) cases had stage III disease and 4 (9%) cases had stage III disease (Table 1).
Table 1
Patient and tumor characteristics
| | Patient characteristics |
Total number | 44 |
Age (years) | |
Median [Range] | 65 [53–82] |
Gender | | |
Female | | 17 (39%) |
Male | | 27 (61%) |
T-Status | | |
1 | | 1 (2%) |
2 | | 14 (32%) |
3 | | 2 (4%) |
4 | | 27 (62) |
N-Status | | |
0 | | 12 (27%) |
1 | | 8 (18%) |
2 | | 17 (39%) |
3 | | 7 (16%) |
M-Status | | |
0 | | 40 (91%) |
1 | | 4 (9%) |
Borrmann classification |
I | | 7 (16%) |
II | | 17 (39%) |
III | | 18 (41%) |
IV | | 2 (4%) |
Stage | | |
I | | 5 (11%) |
II | | 17 (39%) |
III | | 18 (41%) |
IV | | 4 (9%) |
H. pylori infection | | |
+ | | 36 (82%) |
- | | 8 (18%) |
Tumor emboli | | |
+ | | 23 (52%) |
- | | 21 (48%) |
Histologic differentiation |
Moderated | | 14 (32%) |
Poorly | | 30 (68%) |
Expression of OGN decreased in the GC tissues compared with the adjacent normal tissues
To determine whether the expression of OGN was dysregulated in gastric cancer, IHC was performed on the TMA with 44 GC tissues and 40 non-tumorous stomach tissues. OGN expression was seen throughout the foveolar and glandular epithelium of the mucosa (38/40, 95%), with the basal segments of the gland showing more intensive staining (Fig. 1A). In contrast, GC samples revealed varying expression intensities of OGN ranging from strong to absent (Fig. 1A). Quantitative analysis of the IHC results, as shown in (Fig. 1B), showed that loss of OGN expression occurred in 75% of gastric carcinoma samples (P < 0.001). These results indicate that the expression of OGN in the GC tissues was significantly reduced than that in the non-tumorous tissues.
Ogn Expression Correlates With Histological Differentiation Of Gc
The degree of tumor differentiation is an important indicator of tumor malignancy, with poorly differentiated tumors tending to be more aggressive.[23] To study whether the expression level of OGN protein is related to the degree of GC differentiation, we compared the expression of OGN in GC tissues with different differentiation status (Fig. 2A). The statistical analysis showed that expression levels of OGN in the poorly differentiated GC tissues were significantly lower than those in the moderately differentiated GC tissues (P = 0.0015, Fig. 2B). This result indicates OGN expression in GC is negatively correlated with the degree of tumor differentiation.
GC samples with lower OGN expression demonstrated higher degree of lymph node metastasis
We further examined the association of OGN expression levels with several other clinic-pathological parameters of the GC patients. There was no significant correlation between the levels of OGN and the gastric cancer subtype, Borrmann classification, status of tumor emboli, histological type, or H. pylori infection status (Table 2).
Table 2
Association of expression of OGN with clinicopathological characteristics in gastric cancer patients
Characteristic | OGN |
High expression | Low expression | 𝑝 |
Total | | | | |
Cancer | | 11 (25%) | 33 (75%) | 0.000 |
Adjacent normal tissue | 38 (95%) | 2 (5%) |
Histologic differentiation | | |
medium | | 8 (57%) | 6 (43%) | 0.001 |
Poorly | | 3 (10%) | 27 (90%) |
N-status | | | | |
0&1 | | 8 (40%) | 12 (60%) | 0.036 |
2&3 | | 3 (13%) | 21 (87%) |
Borrmann classification | | |
I | | 3 (43%) | 4 (57%) | 0.250 |
II | | 2 (12%) | 15 (88%) |
III | | 6 (33%) | 12 (67%) |
IV | | 0 (0%) | 2 (100%) |
Stage | | | | |
I | | 1 (20%) | 4 (80%) | 0.218 |
II | | 7 (41%) | 10 (59%) |
III | | 3 (17%) | 15 (83%) |
IV | | 0 (0%) | 4 (100%) |
H. pylori infection | | | |
+ | | 6 (75%) | 2 (25%) | 0.549 |
- | | 23 (64%) | 13 (36%) |
Tumor emboli | | | |
+ | | 14 (61%) | 9 (39%) | 0.461 |
- | | 15 (71%) | 6 (29%) |
Gastric carcinoma subtype | | |
Intestinal | | 5 (19%) | 22 (81%) | 0.324 |
Diffuse | | 1 (14%) | 6 (86%) |
Mixed | | 4 (40%) | 6 (60%) |
Histological type | | | |
Tubular | | 6 (21%) | 23 (79%) | 0.670 |
Mucinous | | 2 (40%) | 3 (60%) |
Signet ring | | 0 (0%) | 1 (100%) |
Others | | 3(33%) | 6 (67%) |
Tumor invasion and metastasis is one of the main causes of death in patients with GC.[24, 25] Notably, GC patients with lower OGN expression were more prone to exhibit higher degree of lymph node metastasis than patients with higher OGN expression (Fig. 3A and 3B). These results indicate that decreased OGN expression is associated with enhanced lymph node metastasis in GC.