This study examined the expression of
connexin and
protease-activated receptor 3 (par-3) in the distal
resection margin of
rectal cancer and the correlation of the expression of the two
proteins with
tumor relapse. A total of 40 patients with
rectal cancer underwent ultra-low anterior resection with curved cutter stapler. The pathological specimens were divided into 3 groups in terms of sampling sites:
tumor group, 2.0-cm group (in which the tissues were harvested 2.0 cm distal to the
tumor tissues), 3.0-cm group (in which the tissues were taken 3.0 cm away from the
tumor tissues). All the samples were pathologically observed and then measured for the expression of
connexin and par-3 by employing immunohistochemistry and Western blotting. The operations in this series went uneventfully. No anastomotic stoma
bleeding,
stenosis and death occurred postoperatively. Histopathologically, in the
tumor group, epithelial cells lost normal pattern of arrangement and polarity, and were loosely connected and even detached. In the 3.0-cm group, the epithelia had normal appearance, obvious cell polarity and essentially intact cell junction. Immunohistochemistry and Western blotting indicated that the 3.0-cm group had the strongest expression of
connexin and par-3, and the expression in the 2.0-cm group and the
tumor group was relatively weak. There existed significant difference in the expression of the two
proteins among the three groups (P<0.05 for all). It was concluded that the down-regulated
connexin and par-3 in the distal margin of
rectal cancer tissues may indicate the progression of the disease and high likelihood of recurrence and
metastasis. Although no
tumor cells were found in the sections of the 2.0-cm group, the decreased expression of
connexin and par-3 may suggest the development of
anaplasia and the increased odds of
tumor relapse. Therefore, we are led to speculate that
tumor resection only including 2.0 cm of unaffected rectum could not completely avoid the distant
metastasis and local relapse.