The aim of this study is to compare the effects of new fluorinated taxanes SB-T-12851, SB-T-12852, SB-T-12853, and SB-T-12854 with those of the classical taxane, paclitaxel, and novel non-fluorinated taxane SB-T-1216 on cancer cells. Paclitaxel-sensitive MDA-MB-435 and paclitaxel-resistant NCI/ADR-RES human cancer cell lines were used. Cell growth and survival evaluation, colorimetric assessment of caspases activities, flow cytometric analyses of the cell cycle and the assessment of mitochondrial membrane potential, reactive oxygen species (ROS) and the release of cytochrome c from mitochondria were studied. All fluorinated taxanes examined have similar effects on cell growth and survival. For MDA-MB-435 cells, the C 50 values of SB-T-12851, SB-T-12852, SB-T-12853 and SB-T-12854 were 3 nM, 4 nM, 3 nM and 5 nM, respectively. For paclitaxel-resistant NCI/ADR-RES cells, the C 50 values of SB-T-12851, SB-T-12852, SB-T-12853, and SB-T-12854 were 20 nM, 20 nM, 10 nM and 10nM, respectively. Selected fluorinated taxanes, SB-T-12853 and SB-T-12854, at the cell death-inducing concentrations (30 nM for MDA-MB-435 and 300 nM for NCI/ADR-RES) were shown to activate significantly caspase-3, caspase-2 and caspase-9, as well as caspase-8 in lesser extent. Cell death was associated with significant accumulation of cells in the G 2 /M phase. Cytochrome c was not found to be released from mitochondria and other mitochondrial functions were not significantly impaired. The new fluorinated taxanes appear to use the same or very similar mechanisms of cell death induction as compared with SB-T-1216 and paclitaxel. New fluorinated and non-fluorinated taxanes are more effective against drug-resistant cancer cells than paclitaxel. Therefore, new generation taxanes, either non-fluorinated or fluorinated, are excellent candidates for further and detailed studies.

Resistance of tumours to taxanes causes chemotherapy failure in numerous patients. Resistance is partly due to the low tumour uptake of taxanes and their rapid metabolism. Structural modifications of taxanes can reduce their P-glycoprotein-related efflux or decrease metabolism and consequently increase taxane efficiency. This study compared cytotoxicity and effects of the cell cycle, transport and metabolism of novel taxanes SB-T-1102, SB-T-1103, SB-T-1214 and SB-T-1216, fluorinated SB-T-12851, SB-T-12852, SB-T-12853, SB-T-12854 and IDN5109 with paclitaxel in paclitaxel-sensitive (MDA-MB-435) and paclitaxel-resistant (NCI/ADR-RES) human cancer cells. We have shown before that NCI/ADR-RES cells were 1,000-fold less sensitive to paclitaxel than MDA-MB-435 cells in correspondence to P-glycoprotein overexpression and up to 20-fold lower uptake of the drug in the resistant cells. The uptake of novel taxanes was 1.2 to 3.8 times lower than that of paclitaxel in the MDA-MB-435 cells, but 1.5 to 6.5 times higher in NCI/ADR-RES cells. NCI/ADR-RES cells were correspondingly only 2- to 6.6-fold less sensitive than the MDA-MB-435 cells to novel taxanes. Both cell lines showed minimal metabolism of the novel taxanes which was therefore not responsible for their different sensitivity, the observed differences in their individual efficiency and higher effects than paclitaxel. All novel taxanes caused G(2)/M block of the cell cycle similar to paclitaxel, but lower at concentrations by order of magnitude. Thus, structural modifications of taxanes resulting in their decreased P-glycoprotein-related transport probably caused their higher efficiency than paclitaxel in multidrug-resistant NCI/ADR-RES tumour cells.

The study investigated possible mechanisms by which second-generation taxanes, established as significantly more effective than paclitaxel in vitro, suppress a rat lymphoma model in vivo. The studied mechanisms included taxane pharmacokinetics, expression of genes dominating their metabolism (Cyp3a1/2) and transport (Abcb1) and genes controlling tumour angiogenesis (growth factors and receptors). SB-T-1214, SB-T-12854 and IDN5109 suppressed rat lymphoma more effectively than paclitaxel, SB-T-12851, SB-T-12852, SB-T-12853 or IDN5390 as well as P388D1 leukaemia cells in vitro. The greater anti-lymphoma effects of SB-T-1214 in rats corresponded to a higher bioavailability than with SB-T-12854, and lower systemic toxicity of SB-T-1214 for rats reflected its lower cytotoxicity for P388D1 cells in vitro. Suppression of Abcb1 and CYP3a1 expression by SB-T-1214 and IDN5109 could partly explain their anti-lymphoma effects, but not that of SB-T-12854. Growth factors genes Egf, Fgf, Pdgf, and Vegf associated with tumour angiogenesis had significantly lower expression following treatment with anti-lymphoma effective IDN5109 and their receptors were unaffected, whereas inefficient IDN5390 increased expression of the most important Vegf. The effective SB-T-12854 inhibited Egf, Egfr, Fgfr and Pdgfr expression, while the ineffective SB-T-12851, SB-T-12852 and SB-T-12853 inhibited only Egf or Egfr expression. Vegfr expression was inhibited significantly by SB-T-12851 and SB-T-12854, but effect of SB-T-12851 was compromised by induced Vegf expression. The very effective SB-T-1214 decreased the expression of Vegf, Egf and all receptors most prominently indicating the possible supporting role of these genes in anti-lymphoma effects. In conclusion, SB-T-1214, SB-T-12854 and IDN5109 are good candidates for further study.

Nuclear factor-kappaB (NF-κB), especially p65 subunit, has been associated with origin and progression of cancer as well as with the resistance to radiotherapy and chemotherapy in experimental models. The aim of the present study was to determine expression of NF-κB/p65 in tumor specimens before and after treatment of rectal cancer patients and to evaluate possible relationship between expression of NF-κB/p65 before and after (chemo)radiotherapy, other tumor characteristics and the clinical outcome. Furthermore, NF-κB/p65 was studied in relationship to pathologic response to preoperative (chemo)radiotherapy. Fifty patients with rectal cancer undergoing neoadjuvant (chemo)radiotherapy and surgery were included in the study. Pre-treatment rectal cancer specimens were obtained from diagnostic colonoscopy. Post-treatment rectal cancer specimens were obtained from surgically removed part of the rectum with the tumor. NF-κB/p65 expression was determined by immunohistochemistry and analysis was performed both in biopsies and in post-treatment tumor samples. Cytoplasmic positivity in tumor cells and nuclear positivity in lymphocytes were detected. High NF-κB/p65 positivity in pre-treatment tumor samples was significantly associated with shortened overall survival (OS). Disease-free survival (DFS) tends to be shortened as well. In post-treatment tumor samples, high NF-κB/p65 positivity was neither associated with shortened OS nor with shortened DFS. In post-treatment samples residual tumor cells deeply infiltrating the wall of the rectum with high NF-κB/p65 expression were found. The cells were linked to significantly worse clinical outcome in terms of shortened OS and DFS. NF-κB/p65 positivity did not correlate with pathologic response to preoperative (chemo)radiotherapy. In conclusion, our data suggest that high level of NF-κB/p65 subunit may be associated with more aggressive features of the tumor, higher metastatic potential, and shortened overall survival, but it does not correlate with resistance to (chemo)radiotherapy. Consequently, the level of NF-κB/p65 may help to select those patients who have poor prognosis and are candidates for more intensive anticancer therapy. For these purposes both pre-treatment and post-treatment tumor samples may be used.

Objectives Nuclear factor-kappaB (NF-kappaB), especially p65 subunit, seems to be associated with origin and progression of cancer. The aim of the study was to determine expression of NF-kappaB/p65 in rectal cancer patients before and after radiotherapy as well as to assess the relationship between NF-kappaB/p65 expression, other tumor characteristics, and disease progression. Further aim was to evaluate whether expression of NF-kappaB/p65 in tumor tissue may serve as a predictive marker of patient outcome. Patients and methods Twenty-five patients with rectal cancer undergoing pre-operative radiotherapy were included in the study. Unirradiated rectal cancer specimens were obtained from diagnostic colonoscopy. Irradiated rectal cancer specimens were obtained from surgically removed part of the rectum with the tumor. NF-kappaB/p65 expression was determined by immunohistochemistry. Results Cytoplasmic positivity in cancer cells and nuclear positivity in lymphocytes were detected. In post-radiotherapy specimens single tumor cells or small clones of them deeply infiltrating the wall of the rectum, that were characterized by high NF-kappaB/p65 expression, were found. Patients with presence of these cells in post-radiotherapy specimens have worse clinical outcome in terms of overall survival and disease-free interval. Conclusion While the NF-kappaB/p65 positive staining of the epithelial cells did not have any clinical implications in this study, it may be of clinical significance in the future. Residual invasively growing cancer cells with high NF-kappaB/p65 positivity found in specimens after radiotherapy and surgery may be used to find what patients have a worse outcome. Thus, patients being at risk of cancer progression and requiring more aggressive anti-cancer therapy may be identified.