The Distribution And The Significance Of Nerve Fiber Containing Substance P In Human Gastric Carcinoma

Gastric carcinoma is one of the most common malignant cancers in the world. The incidence rates and mortality of gastric carcinoma is still high in our country. Thus the study of gastric cancer is of great importance and a thorough understanding of the etiology of gastric cancer will have a profound impact on our approach to dealing with it.It is known to us that most of our organs were innervated. Nervous fiber can regulate some kind of tissue proliferation and development. Recent studies have demonstrated that adenoma of the ciliary body epithelium of the eye was innervated and some kinds of cancer cells, such as breast cancer cells, can express tachykinin receptors (NK-1). Although there were no relating reports about the distribution of nervous fiber in gastric adenocarcinoma, and little is known about the effects of nervous fiber on gastric cancer cells, we would like to undertake the following experiments to investigate the existence and the distribution of SP-IR positive nerve fibers in human gastric adenocarcinoma and to7study their effects on gastric cancer cells.First, specimens of gastric adenocarcinomas that had been surgically removed from 34 patients were processed for immunohistochemistry analyses for the existence and distribution of SP immune-positive nerve fiber. A large number of nerve fibers containing clear and dense core vesicles could be seen implanting to carcinoma nests from the periphery tissues and branching off to the central areas. The nerve fibers were located close to tumor cells in the tumor, and a lot of structures like growth-cones were detected in the central areas. The appearance of activated ERK1/2 immune reactive positive (IRP) nerve fiber suggested that these nerve fibers were undergoing re-generation, and the growth-cones occurrence were also demonstrations of nerve re-generation.To determine the reasons of the nerve fiber appearance in gastric cancer tissues in vitro, immunohistochemistry staining was performed on two gastric cancer cell lines MKN45 and MKN28 to investigate if these cell lines could express nerve growth factor (NGF), which would induce the re-generation of nervous fibers to the site or semaphorin 3A. Semaphorin 3A is a secreted protein that in vitro causes neuronal growth cone collapse and chemorepulsion of neuritis, and that in vivo is required for correct sensory afferent innervation and other aspects of development. The results showed that both cell lines expressed NGF, but it was MKN28 cells, not MKN45 cells that expressed semaphorin 3A.Our findings indicated that NGF and semaphorin 3A contributed to nervous fiber re-generation in gastric cancer.As we know, SP exerts its effects by binding to its high affinity NK-1 receptor, so if SP exerts its effects on gastric cancer cells, these cells must expresse NK-1. We also found both the cancer cells in slices and gastric cancer cell lines did express NK-I receptor, and a lot of NK-1 and active ERK1/2 co-expression cells were found by microscopic analysis of gastric cancer sections stained "lth antibodies specific for these two substances. This result suggested that SP might have some effects, for example, mitogenic effect on gastric cancer cells by binding to the NK-1, which expressed by gastric cancer cell. To examine the mitogenic effect of SP on gastric cancer cells, MKN45 and MKN28 cells were stimulated with SP. We found SP increased DMA synthesis rate of MKN45 cells significantly compared with MKN28 cells, PCNA expression level in MKN45 cells also increased when assayed by Western blot. The number active ERK1/2 immune reactive positive cells of both two-cell lines increased after SP stimulation. These findings confirmed that SP had amitogenic effect on gastric cancer cell and that the mitogenic effect was mediated by the MAPK/ERK pathway.SP has been implicated in the regulation of several physiologic and pathophysiologic processes. A large body of in vitro and in vivo studies suggested a role for SP as a proinflammatory agent. For example, SP is a chemoattractant for monocyte...