[Where are we in the treatment of gastric cancer? Experiences and evidences 30 years later]

Frequency and clinical characteristics of early gastric cancer in comparison to advanced gastric cancer in a health area of Spain

INTRODUCTION

Gastric cancer (GC) incidence is currently decreasing; however, survival is still low. Early GC (EGC) has better prognosis and it could be cured by endoscopic methods.

PATIENTS AND METHODS

Observational study of a retrospective cohort of all patients with GC during a five-year period in a health area of Spain. EGC diagnosis was defined as mucosal or submucosal (T1) cancers regardless of lymph node involvement, whereas the advanced GC were T2-T4.

RESULTS

209 patients were included, and 26 (12%) of them were EGC. There was no difference between EGC and advanced GC in age, sex, HP infection, precancerous lesions or histological type. Other characteristics of EGC were different from advanced GC: location (antrum and incisura in 76% vs 38%, p=0.01), alarm symptoms (69% vs 90%, p<0.01), curative treatment (100% vs 30%, p<0.01), performance status (PS 0-1: 92% vs 75%, p=0.03) and survival (85% vs 20%, p<0.001). Among patients who received curative treatment, 98% (79/81) underwent surgery and 2% (2/81) were treated by mucosectomy. Seven (27%) patients with EGC could have benefited from treatment by endoscopic submucosal resection.

DISCUSSION

EGC frequency was low (12% of GCs) in our health area. EGC had a high percentage of alarm symptoms, and was located in the distal third of the stomach (antrum and incisura) and had better prognosis compared to advanced GC. Strategies to increase detection and endoscopic treatment of EGC should be implemented.

Silencing of RegIV by shRNA causes the loss of stemness properties of cancer stem cells in MKN45 gastric cancer cells

Regenerating islet-derived family member 4 (RegIV) is overexpressed in several types of tumours, including pancreatic and gastric cancer (GC). However, the role it plays in gastric cancer stem cells (GCSCs) remains unknown. The present study tested the hypothesis that the silencing of RegIV by shRNA in GC cells may cause the loss of their stemness properties, indicating the inhibition of growth, proliferation and increased sensitivity to chemoradiation-induced cell death. MKN45 poorly differentiated human GC cells were propagated as mammospheres in stem cell culture conditions. Mammospheres were identified as CSCs using generally acknowledged CSC markers such as CD44. A panel of 21-nucleotide shRNAs were designed to target RegIV gene expression. Several shRNA constructs were identified that led to significant reduction in RegIV mRNA expression. Furthermore, the stemness properties of control mammospheres and RegIV knockdown mammospheres were compared by tumourigenicity assay in vivo and plate colony formation assay in vitro. Finally, we evaluated the treatment response in both mammospheres which underwent chemoradiation. The knockdown expression of RegIV by shRNA deprived CSCs of their stemness properties and increased the effectiveness of cell killing following chemoradiation. Inhibition of endogenous RegIV expression may be a new therapeutic strategy for human GC.