| Salivary adenoid cystic carcinoma(ACC) has a characteristic of perineural invasion, so there is great clinical significance to seek biological markers and understand the reasons for perineural invasionin ACC. As for neurotrophins and their receptors, there are still no reports on their expression in ACC or their effects on ACC cells' ability of invasion.Objective: To study the expression of neurotrophins and their receptors in ACC and to find factors which may correlate with perineural invasion in ACC. To evaluate the effects of neurotrophins on ACC cells' ability of invasion in vitro. To provide evidence for the understanding of the reasons for perineural invasion in ACC and for the controlling of ACC's invasion to nerves.Methods: 1. Immunohistochemistry: 32-33 salivary ACC tissue samples were divided in to 2 groups according to the pathological presence of perineural invasion, 5-7 normal parotid glands and 3 acinic cell carcinoma tissue samples were also studied. The expression of two neurotrophins (NGF and NT-3) and two receptors (TrkA and TrkC) was assessed by the proportion of immunoreactive cancer cells and intensity of staining, and neural symptoms of ACC patients were reviewed. For statistical analysis, Fisher's exact test was used to evaluate the relationship between their expression and perineural invasion. We also observed their expression in human salivary ACC cell line SACC-83. 2. Adhesion test in vitro: cell culture well was coated with Matrigel, and SACC-83 cell line was co-cultured with NGF of different concentrations. The adhesion rate was investigated with MTT colorimetric assay, and t test was used for statistical analysis. Human tongue cancer cell line TCA-8113 was also studied for comparison. 3. Assessment of motility in vitro: invasive chamber was applied to investigate different concentrations of NGF's effect on the number of SACC-83 cells which had moved towards lower chamber through the porous filter. 4. Assessment of invasion in vitro: the upper surface ofporous filter was coated with Matrigel, and different concentrations of NGF's effect on the number of SACC-83 cells which had invaded Matrigel was observed.Results: 1. NGF, NT-3, TrkA and TrkC presented positive in over 90% of ACC paraffin sections, and their expression in group with perineural invasion defined pathologically was significantly higher than the group without perineural invasion. In cribriform and tubular-trabecular patterns, cancer cells in the glandiform structure were the main positive cells, while positive cancer cells in solid pattern were pervasive. As for NGF, NT-3 and TrkA, cancer cells far from nerves presented weaker positive than in perinural space, while there wasn't this phenomenon in the study of TrkC. NGF expression in group with pain syndrome was significantly higher than the one without pain. In several cases, perineural invasion defined pathologically didn't coexist with neural symptoms. All the 4 neurotrophins and receptors presented positive in ductule cells of normal parotid glands but not in acinic cell carcinoma. In the study of SACC-83 cell line, NGF and NT-3 presented moderate to strong positive, while TrkA and TrkC presented weak to moderate positive, and the proportion of immunoreactive cancer cells were +++ in the expression of all the 4 neurotrophins and receptors. 2. Without NGF, the adhesion rate of SACC-83 cell line and TCA-8113 cell line on Matrigel was significantly higher than on plastic of culture well after the same time of culture. When coated with Matrigel, the adhesion rates of SACC-83 cell line incubated for 90min with NGF of 25ng/ml as well as for 6h with NGF of 5, 25ng/ml were significantly higher than without NGF after the same time of culture, while this difference wasn't observed in TCA-8113 cell line. 3. After incubated with NGF of 5, 25, 50ng/ml, the number of SACC-83 cellschamber was significantly higher than without NGF. 4. After incubated with NGF of 25, 50ng/ml, the number of SACC-83 cells which had invaded and penetrated Matrigel was significantly increa...
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