The substance P (SP)/neurokinin (NK)-1 receptor system plays an important role in cancer. SP promotes the proliferation of tumour cells, angiogenesis and the migration of tumour cells. We review the involvement of SP, the NK-1 receptor and NK-1 receptor antagonists in cancer. Tumour cells overexpress NK-1 receptors, which are involved in their viability. This overexpression suggests the possibility of specific treatment against tumour cells using NK-1 receptor antagonists, thus promoting a considerable decrease in the side effects of the treatment. This strategy opens up new approaches for cancer treatment, since these antagonists, after binding to their molecular target, induce the death of tumour cells by apoptosis, exert an antiangiogenic action and inhibit the migration of tumour cells. The use of NK-1 receptor antagonists such as aprepitant (used in clinical practice) as antitumour agents could be a promising innovation. The value of aprepitant as an antitumour agent could be determined faster than for less wellknown compounds because many studies addressing its safety and characterization have already been completed. The NK-1 receptor may be a promising target in the treatment of cancer; NK-1 receptor antagonists could act as specific drugs against tumour cells; and these antagonists could be new candidate anti-cancer drugs.

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It has been demonstrated that substance P (SP) induces cell proliferation and neurokinin-1 (NK-1) receptor antagonists inhibit growth in several human cancer cell lines, but it is currently unknown whether such actions are exerted on human laryngeal carcinoma cell line HEp-2. In addition, the presence of NK-1 receptor has not been demonstrated in this cell line. We carried out an in vitro study of the growth inhibitory capacity of the NK-1 receptor antagonists L-733,060 and L-732,138 against human laryngeal carcinoma cell line HEp-2. Coulter counter was used to determine viable cell numbers followed by application of the tetrazolium compound MTS. Furthermore, an immunoblot analysis was used to determine the NK-1 receptor, and the 4',6-diamidino-2-phenylindole (DAPI) method was applied to demonstrate apoptosis of the laryngeal carcinoma cells. We observed the presence of several NK-1 receptors isoforms (34, 46, 58 and 75 kDa). Nanomolar concentrations of SP increased the growth rate of the cell line and micromolar concentrations of L-733,060 and L-732,138 inhibited the growth of the HEp-2 cells in a dose-dependent manner, with and without previous administration of SP. The 50% inhibition concentration values were 21.34 microM and 37.97 (48 h) respectively for HEp-2. NK-1 receptor presence on HEp-2 cells was confirmed by western blotting. DAPI staining revealed the presence of apoptosis following NK-1 receptor antagonists treatment. We demonstrated that NK-1 receptors were present in this laryngeal cancer cell line; these findings demonstrate that SP acts as a mitogen on the human laryngeal carcinoma cell line HEp-2 through the NK-1 receptor, and also indicate that both NK-1 receptors antagonists induced apoptosis of the tumour cells. This new action, reported here for the first time, suggests that the NK-1 receptor is a new and promising target in the treatment of human laryngeal carcinoma.

Summary The expression of HLA class I antigens was studied in 99 primary tumours (colorectal, gastric and laryngeal carcinomas) and 57 autologous metastases using immunohistological techniques and monoclonal antibodies against class I monomorphic determinants, HLA-B isotypic determinants and HLA polymorphic determinants. Fourteen per cent of colorectal, 9.6% of gastric and 20% of laryngeal carcinomas completely lacked class I molecules. Selective losses of HLA-B antigens were also detected in 8.8, 3.4 and 5.8% of these tumours respectively. Taking into account complete and selective loss of HLA-B the average alteration in the class I molecules expression totalled 21%. The comparison of class I expression between primary tumours and autologous metastases showed differences in 24% of the patients. These differences consisted mainly in a decrease of class I expression by metastases. Nevertheless, four types of divergence were detected in laryngeal carcinomas, namely: + / -, + / +, -/ +, -/-. In addition, a clear correlation between degree of differentiation and class I expression was observed in laryngeal tumours. Finally, when class I gene RFLPs were compared with DNA from 15 tumours and autologous normal mucosa or peripheral lymphocytes, no differences were detected between these samples.

Human papillomavirus types HPV 16 and HPV 11 DNA sequences were analyzed in normal and neoplastic tissues of the larynx, using the technique of polymerase chain reaction (PCR). An amplified region of E6 ORF was hybridized with 3' end-labelled oligonucleotide probe. Twenty six out of 48 (54%) squamous-cell carcinomas, and 3 out of 3 verrucous-cell carcinomas hybridized with HPV 16 DNA sequences, whereas we did not detect HPV 11 sequences. HPV 16 DNA sequences were also found in normal, autologous mucosa and lymphnode metastases, although these were absent in other tissues analyzed. HPV-16-positive tumors were most frequently poorly differentiated squamous-cell carcinomas.