Peptidergic innervation of human esophageal and cardiac carcinoma

Abstract

Aim: To investigate the distribution of neuropeptide-immunoreactive nerve fibers in esophageal and cardiac carcinoma as well as their relationship with tumor cells so as to explore if there is nerve innervation in esophageal and cardiac carcinoma.

Methods: Esophageal and cardiac carcinoma specimens were collected from surgical operation. One part of them were fixed immediately with 4 % paraformaldehyde and then cut with a cryostat into 40-microm-thick sections to perform immunohistochemical analysis. Antibodies of ten kinds of neuropeptide including calcitonin gene-related peptide (CGRP), galanin (GAL), substance P (SP), etc. were used for immunostaining of nerve fibers. The other part of the tumor specimens were cut into little blocks (1 mm(3)) and co-cultured with chick embryo dorsal root ganglia (DRG) to investigate if the tumor blocks could induce the neurons of DRG to extend processes, so as to probe into the possible reasons for the nerve fibers growing into tumors.

Results: Substantial amounts of neuropeptide including GAL-, NPY-, SP-immunoreactive nerve bundles and scattered nerve fibers were distributed in esophageal and cardiac carcinomas. The scattered nerve fibers waved their way among tumor cells and contacted with tumor cells closely. Some of them even encircled tumor cells. There were many varicosities aligned on the nerve fibers like beads. They were also closely related to tumor cells. In the co-culture group, about 63 % and 67 % of DRG co-cultured with esophageal and cardiac tumor blocks respectively extended enormous processes, especially on the side adjacent to the tumor, whereas in the control group (without tumor blocks), no processes grew out.

Conclusion: Esophageal and cardiac carcinomas may be innervated by peptidergic nerve fibers, and they can induce neurons of DRG to extend processes in vitro.

Figure 1

GAL-immunostaining of esophageal carcinoma. Scat-tered nerve fibers (arrows) branched almost vertically from nerve bundles in connective tissue and entered into tumor parenchyma × 250.

Figure 2

L-ENK-immunoreactive nerve fibers in esophageal carcinoma. The fine nerve fiber (arrow) with varicosities on it encircled a tumor cell and contacted with it closely ×500.

Figure 3

GAL-immunostaining of esophageal carcinoma. Many nerve fibers entered into a nestlike cancerous tissue (T) convergently from collective tissue around it. The structure on the top right corner was amplified in Figure 4 ×125.

Figure 4

Higher magnification of the part on the top right in Fig.3. GAL- immunoreactive nerve fibers entered into esoph-ageal carcinoma from peripheral areas × 250.

Figure 5

Section of Cardiac adenocarcinoma immunostained for GAL. Many immunoreactive nerve fibers with beads-like varicosities distributed in the parenchyma of tumor ×500.

Figure 6

GAL-immunoreactive nerve fibers extended into nestlike cancerous tissue formed by cardiac adenocarcinoma cells. The scattered nerve fibers contacted with tumor cells closely ×500.

Figure 7

Montage photographs showing the effects of esoph-ageal (a) and cardiac (b) carcinoma tissue block (T) on co-cul-tured DRG (G). On the side adjacent to tumor, DRG extending long and dense processes whereas on the opposite side, the pro-cesses are sparse and short (b), or no processes at all (a) ×125.