We report a series of new in vitro and in vivo data proving the selective antitumor activity of our somatostatin structural derivative, TT-232. In vitro, it inhibited the proliferation of 20 different human tumor cell lines in the range of 50-95% and induced a very strong apoptosis. In vivo was not toxic at a dose of 120 mg/kg of b.w. in mice. Long-term incubation (24 h) of tumor cells with TT-232 caused significant inhibition of tyrosine kinases in good correlation with the apoptosis-inducing effect. The level of p53 or KU86 did not change following TT-232 treatment, suggesting a p53-independent apoptotic effect. Preincubation of human breast cancer cells (MDA-MB-453) with TT-232 for 2 h decreased the growth factor receptor autophosphorylation. All of these data suggest that TT-232 is a promising and selective antitumor agent.
A major goal of cancer genomics is to identify all genes that play critical roles in carcinogenesis. Most approaches focused on genes positively selected for mutations that drive carcinogenesis and neglected the role of negative selection. Some studies have actually concluded that negative selection has no role in cancer evolution. We have re-examined the role of negative selection in tumor evolution through the analysis of the patterns of somatic mutations affecting the coding sequences of human genes. Our analyses have confirmed that tumor suppressor genes are positively selected for inactivating mutations, oncogenes, however, were found to display signals of both negative selection for inactivating mutations and positive selection for activating mutations. Significantly, we have identified numerous human genes that show signs of strong negative selection during tumor evolution, suggesting that their functional integrity is essential for the growth and survival of tumor cells.
The prognostic significance of spontaneous regression of primary melanoma is a controversial issue. Studies on sentinel lymph node status and circulating tumour cells may represent a step towards a better understanding. The clinical details of 269 melanoma patients who underwent sentinel lymph node biopsy were analysed. Correlation was sought between the parameters of the primary tumour, particularly tumours showing a partial intermediate level of regression, and sentinel lymph node status. The presence of circulating tumour cells was studied by reverse transcription-polymerase chain reaction for tyrosinase messenger RNA preoperatively in 94 patients. Of the examined tumours, 27.8% showed histological features of a partial intermediate level of regression. Regressive tumours were localized predominantly on the trunk (P=0.006), were significantly thinner (P<0.0000) and were less frequently ulcerated (P=0.003) than tumours without regression. Moreover, the majority of regressive melanomas were of the superficial spreading type (P<0.0000) and their sentinel node status was more favourable (P=0.026). We demonstrated the presence of circulating tumour cells in five of 26 (19.2%) regressive and 19 of 68 (29.4%) non-regressive tumours. The difference was not significant (P=0.32). By multivariate analysis, however, the Breslow thickness and ulceration of the primary tumour were predictors of the sentinel lymph node status, in agreement with literature data. A partial intermediate level of regression of the primary tumour did not affect unfavourably the sentinel lymph node status in our study. We failed to demonstrate a significant relationship between the presence of circulating tumour cells and either primary tumour regression or the sentinel lymph node status.
Squamous cell cancer in the head and neck region (HNSC) is unique concerning its progression since it remains locoregional for long time and visceral metastases develop only in a later stage of the disease. Accordingly, molecular markers of the local invasion and the lymphatic dissemination both have critical importance. HNSC progression is associated with deregulated control of cell proliferation and apoptosis but it seems equally significant the disregulation of the proteolytic machineries. Here we outline the lymphatic metastatic cascade for HNSC to depict key molecular determinants as possible prognostic factors or therapeutic targets identifying immunological selection as a major feature. Unlike in local spreading, invasive potential of cancer cells seems to be less significant during lymphatic dissemination due to the anatomical properties of the lymphatic vessels and tissues. There is a general believe that HNSC is one disease however, data indicate that the anatomical localization of the tumor (the "soil") such as oral, lingual, glottic or pharyngeal has a significant effect on the gene expression profile and corresponding biological behavior of HNSC. Furthermore, even the endocrine milieu of the host was proved to be influential in modulating the progression of HNSC. Gene expression profiling techniques combined with proteomics could help to define and select usefull genetic and biomarkers of progression of HNSC, some of them could well be potential novel therapeutic target.
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