Background/Aims: It has been demonstrated that substance P (SP) and neurokinin-1 (NK-1) receptor antagonist L-733,060 induces cell proliferation and inhibition, respectively, in several human cancer cell lines. At present, it is unknown whether such actions are exerted on human gastric and colon adenocarcinomas. We carried out an in vitro study of the growth-inhibitory capacity of L-733,060 against human gastric and colon adenocarcinomas. Methods: A coulter counter was used to determine viable cell numbers followed by application of the tetrazolium compound MTS. Immunoblot analysis was used to determine the NK-1 receptors and the DAPI method was applied to demonstrate apoptosis. Immunohistochemistry was used to demonstrate NK-1 receptors in primary human gastric and colon adenocarcinomas. Results: We observed the presence of several NK-1 receptor isoforms in human gastric and colon adenocarcinomas. Nanomolar concentrations of SP increased the growth of both cell lines and micromolar concentrations of L-733,060 inhibited the growth of such cell lines, with and without previous administration of SP. L-733,060 inhibited the growth of the 23132/87 and SW-403 cell lines in a dose-dependent manner. After administration of L-733,060, apoptosis was observed in both cell lines. In both human primary gastric and colon adenocarcinomas, a high density of NK-1 receptors was observed. Immunoreactivity, showing a diffuse cytoplasmic staining, was observed in the epithelial cells of normal and tumor glands and in numerous stromal elements. Conclusions: We demonstrated that NK-1 receptors were expressed in 23132/37 and SW-403 cell lines and in human primary gastric and colon adenocarcinomas, that SP is a mitogen and that the antitumor action of L-733,060 on both human cell lines occurs through the NK-1 receptor. Data also indicate that the cell death observed is produced by apoptosis. These data suggest that the NK-1 receptor is a new and promising target in the treatment of human gastrointestinal adenocarcinomas.

Melanoma, the most deadly form of skin cancer, is aggressive and resistant to current therapies. It has been previously reported that the substance P and neurokinin-1 (NK-1) receptor antagonists induce cell proliferation and cell inhibition, respectively, in human melanoma cell lines. Aprepitant is a selective high-affinity antagonist of the human NK-1 receptor. Until now, this drug has been used as an anxiolytic, antidepressant and antiemetic. Moreover, the antitumor action of aprepitant has been previously reported. However, the presence of NK-1 receptors in human melanomas and whether the antitumor action of the NK-1 receptor antagonist aprepitant is exerted on human malignant melanomas have not been previously described. The aims of this study are to show the presence of NK-1 receptors in human malignant melanomas and the antitumoral action of aprepitant against several human melanoma cell lines. Immunoblot analysis was used to determine the presence of NK-1 receptors in human melanoma cell lines, and immunohistochemistry was used to demonstrate NK-1 receptors in human melanoma samples. We performed an in vitro study of the cytotoxicity of the NK-1 receptor antagonist aprepitant on human melanoma cell lines. A coulter counter was used to determine viable cell numbers, followed by application of the tetrazolium compound MTS. The DAPI method was applied to demonstrate apoptosis. We observed that NK-1 receptors were present in all the melanoma samples studied as well as in human melanoma cell lines. We also showed that melanoma cell lines expressed mRNA for the NK-1 receptor. Moreover, after using a knockdown method, we showed that NK-1 receptors are involved in the viability of tumor cells. In this study, we also report that aprepitant, at 10-60 mM concentrations, elicits cell growth inhibition in a concentration-dependent manner in all melanoma cell lines studied, that the specific antitumor action of aprepitant occurs through the NK-1 receptor and that melanoma cell death is due to apoptosis. These findings show for the first time that the NK-1 receptor may be a promising new target and that the NK-1 receptor antagonist aprepitant could be a candidate as a new antitumor drug in the treatment of human melanoma.

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Our multi-centric trial using the OSNA assay for sentinel node evaluation in breast cancer demonstrates that this is a highly sensitive, specific and reproducible technique that allows for standardization of the SN diagnostic procedure, a necessary, and until now unresolved, issue.