The neurokinin-1 receptor antagonist aprepitant is a promising candidate for the treatment of breast cancer.

The substance P (SP)/neurokinin (NK)-1 receptor system plays an important role in the development of cancer. No in-depth studies of the involvement of this system in breast cancer (BC) have been carried out, and the action exerted by the drug aprepitant on BC cells is currently unknown. We show the involvement of this system in human BC cell lines: i) these cells express mRNA for the NK-1 receptor; ii) they overexpress NK-1 receptors; iii) the NK-1 receptor is involved in their viability; iv) SP induces their proliferation; v) NK-1 receptor antagonists block SP-induced mitogen stimulation of these cells; vi) the specific antitumor action of such antagonists on these cells occurs through the NK-1 receptor; and vii) BC cell death is due to apoptosis. We also found NK-1 receptors and SP in all human BC samples studied. The NK-1 receptor may be a promising target in the treatment of BC and NK-1 receptor antagonists could be candidates as a new antitumor drug in the treatment of BC.

Uveal melanoma expresses NK-1 receptors and cyclosporin A induces apoptosis in human melanoma cell lines overexpressing the NK-1 receptor.

Substance P and neurokinin-1 (NK-1) receptor antagonists respectively induce proliferation and growth inhibition in human melanoma cell lines. The presence of NK-1 receptors in human melanoma cell lines and samples has been reported, but the presence of NK-1 receptors has not been demonstrated in uveal melanomas. It is known that melanoma express the tachykinin 1 receptor (TAC1R) gene. This gene is overexpressed in several human cancer cell lines, but such overexpression is currently unknown in human malignant melanoma cell lines (COLO 858, MEL HO, COLO 679). In this study, we attempt to demonstrate the overexpression of the TAC1R gene in such cells. We performed an in vitro study by real-time quantitative RT-PCR for TAC1R and found that the NK-1 receptor was overexpressed in the three human melanoma cell lines studied. Using a knockdown method, we demonstrate that the NK-1 receptor is involved in the viability of the COLO 858 melanoma cell line. Immunohistochemistry was also used to demonstrate NK-1 receptors in uveal melanoma samples. We observed that NK-1 receptors were present in the 21/21 uveal melanomas. In addition, cyclosporin A inhibited the growth of the three melanoma cell lines studied in a dose-dependent manner, and after the administration of this immunosuppresive drug apoptosis was observed. This indicates at least that the antitumor action of cyclosporin A is mediated by the NK-1 receptor. Our findings suggest that the NK-1 receptor could be a promising target in the treatment of human melanomas.

Antitumor activity of neurokinin-1 receptor antagonists in MG-63 human osteosarcoma xenografts.

Osteosarcoma is a highly malignant bone tumor in children and adolescents. Aprepitant is a selective high­affinity antagonist of the human neurokinin­1 (NK­1) receptor (NK1R) with robust antitumor activity. No data exist on the presence of NK1R in osteosarcoma and whether this tumor responds to NK1R antagonists. Here, we analyzed the expression of NK1R in the human osteosarcoma cell line MG-63 with western blot analysis and PCR and found significant expression both at the protein and mRNA levels. We further studied the growth inhibitory capacity of aprepitant and other NK1R antagonists on MG-63 in vitro using an MTS cytotoxicity assay and DAPI staining. All antagonists induced tumor growth inhibition and apoptosis. Synergism was observed for the combination of L-733,060 with common cytostatic drugs in MG-63, but not in non-malignant HEK293 cells. Pretreatment of HEK293 with L-733,060 prior to exposure to cytostatic drugs partially protected HEK293 cells from inhibition by these drugs. Furthermore, nanomolar concentrations of substance P (SP), the natural ligand of the NK1R, increased the growth rate of MG­63 cells and micromolar concentrations of aprepitant inhibited SP-induced growth in a dose­dependent manner. In vivo, a xenograft for MG-63 was created in nude mice and treated with peritumoral s.c. injections of fosaprepitant, which resulted in a significant reduction of tumor volume. Collectively, we demonstrated for the first time that the NK1R is expressed in human osteosarcoma cell line MG­63 and that this receptor can be targeted with NK1R antagonists both in vitro as well as in vivo.

The substance P/neurokinin-1 receptor system in lung cancer: focus on the antitumor action of neurokinin-1 receptor antagonists.

The last decades have seen no significant progress in extending the survival of lung cancer patients and there is an urgent need to improve current therapies. The substance P (SP)/neurokinin-1 receptor (NK-1R) system plays an important role in the development of cancer: SP and NK-1R antagonists respectively induce cell proliferation and inhibition in human cancer cell lines. No study of the involvement of this system in non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC) cells has been carried out in depth. Here, we demonstrate the involvement of the SP/NK-1R system in human H-69 (SCLC) and COR-L23 (NSCLC) cell lines: (1) they express isoforms of the NK-1R and mRNA for the NK-1R; (2) they overexpress the tachykinin 1 gene; (3) the NK-1R is involved in their viability; (4) SP induces their proliferation; (5) NK-1R antagonists (Aprepitant (Emend), L-733,060, L-732,138) inhibit the growth of both cell lines in a concentration-dependent manner; (6) the specific antitumor action of these antagonists against such cells occurs through the NK-1R; and (7) lung cancer cell death is due to apoptosis. We also demonstrate the presence of NK-1Rs and SP in all the human SCLC and NSCLC samples studied. Our findings indicate that the NK-1R may be a promising new target in the treatment of lung cancer and that NK-1R antagonists could be new candidate antitumor drugs in the treatment of SCLC and NSCLC.

The NK-1 receptor is expressed in human leukemia and is involved in the antitumor action of aprepitant and other NK-1 receptor antagonists on acute lymphoblastic leukemia cell lines.

Substance P and neurokinin-1 (NK-1) receptor antagonists respectively induce cell proliferation and cell inhibition in human cancer cell lines. In acute lymphoblastic leukemia (ALL), substance P is expressed in human blast cells. However, the possible presence of NK-1 receptors in human ALL and the issue of whether the antitumor action of NK-1 receptor antagonists is exerted or not on human ALL (T-ALL BE-13 and B-ALL SD-1 cell lines) remain unknown. An immunoblot analysis was performed and an in vitro study of the cytotoxicity of three NK-1 receptor antagonists (L-733,060, L-732,138, aprepitant) was carried out on both cell lines. NK-1 receptors were found in those cell lines, and both expressed mRNA for this receptor. Using a knockdown method, we demonstrate that NK-1 receptors are involved in the viability of tumor cells. TAC1R cDNA was detected in the ALL cell lines by real-time quantitative RT-PCR. We also observed that the three NK-1 receptor antagonists elicited the inhibition of ALL cell growth; that the specific antitumor action of the NK-1 receptor antagonists occurs through the NK-1 receptor, and that ALL cell death is due to apoptosis. These findings suggest that NK-1 receptor antagonists could be considered as new antitumor drugs for the treatment of human ALL.

The NK-1 receptor is expressed in human melanoma and is involved in the antitumor action of the NK-1 receptor antagonist aprepitant on melanoma cell lines.

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 microM 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.

The NK-1 Receptor Antagonist L-732,138 Induces Apoptosis and Counteracts Substance P-Related Mitogenesis in Human Melanoma Cell Lines.

It has been recently demonstrated that substance P (SP) and neurokinin-1 (NK-1) receptor antagonists induce cell proliferation and cell inhibition in human melanoma cells, respectively. However, the antitumor action of the NK-1 receptor antagonist L-732,138 on such cells is unknown. The aim of this study was to demonstrate an antitumor action of L-732,138 against three human melanoma cell lines (COLO 858, MEL HO, COLO 679). We found that L-732,138 elicits cell growth inhibition in a concentration dependent manner in the melanoma cells studied. Moreover, L-732,138 blocks SP mitogen stimulation. The specific antitumor action of L-732,138 occurred through the NK-1 receptor and melanoma cell death was by apoptosis. These findings indicate that the NK-1 receptor antagonist L-732,138 could be a new antitumor agent in the treatment of human melanoma.