Relapse after chemotherapy treatment depends on the cancer initiating cells (CICs). PEDF (Pigmented Epithelium Derived Factor) is an anti-angiogenic, neurotrophic and self-renewal regulator molecule, also involved in CICs biology. Acute and chronic exposition of colon cancer cell lines to CT/CTE PEDF-derived peptides decreased drug-resistance to conventional colorectal cancer treatments, such as oxaliplatin or irinotecan. We confirmed a reduction in the irinotecan and oxaliplatin IC50 doses for all tested tumour cell lines. After xenograft transplantation, CT/CTE treatments also produced a reduction in resistance to conventional chemotherapy treatments as in culture-assays. Metastatic capacity of these treated cell lines was also depleted. The PEDF signaling pathway could be a future therapeutic tool for use as an adjuvant therapy that decreases IC50 dosis, adverse effects and treatment costs. This pathway could also be involved in an increase of the time relapse in patients, decreased tumourigenicity, and decreased capacity to produce metastasis.

We studied potential changes in the subventricular zone (SVZ) stem cell niche of the senescence-accelerated mouse prone-8 (SAM-P8) aging model. Bromodeoxyuridine (BrdU) assays with longtime survival revealed a lower number of label-retaining stem cells in the SAM-P8 SVZ compared with the SAM-Resistant 1 (SAM-R1) control strain. We also found that in SAM-P8 niche signaling is attenuated and the stem cell pool is less responsive to the self-renewal niche factor pigmented epithelium-derived factor (PEDF). Protein analysis demonstrated stable amounts of the PEDF ligand in the SAM-P8 SVZ niche; however, SAM-P8 stem cells present a significant expression decrease of patatin-like phospholipase domain containing 2, a receptor for PEDF (PNPLA2-PEDF) receptor, but not of laminin receptor (LR), a receptor for PEDF (LR-PEDF) receptor. We observed changes in self-renewal related genes (hairy and enhancer of split 1 (Hes1), hairy and enhancer of split 1 (Hes5), Sox2] and report that although these genes are down-regulated in SAM-P8, differentiation genes (Pax6) are up-regulated and neurogenesis is increased. Finally, sheltering mammalian telomere complexes might be also involved given a down-regulation of telomeric repeat binding factor 1 (Terf1) expression was observed in SAM-P8 at young age periods. Differences between these 2 models, SAM-P8 and SAM-R1 controls, have been previously detected at more advanced ages. We now describe alterations in the PEDF signaling pathway and stem cell self-renewal at a very young age, which could be involved in the premature senescence observed in the SAM-P8 model.

We report on two patients, successfully treated by the combination therapy of gemcitabine and 24-h intravenous infusion of cisplatin, who were initially diagnosed with node-positive advanced urothelial cancer. Each patient had a very good clinical response and underwent curative radical surgery after gemcitabine/cisplatin chemotherapy. A microscopically detailed examination of surgically obtained specimens showed the complete disappearance of malignant cells in the two cases. As a pilot study, we have used the regimen of gemcitabine plus 24-h continuous infusion of cisplatin, instead of bolus injection, for the treatment of 20 patients with node-positive or metastatic urothelial cancer. The clinical response rate in this regimen was 75% (complete response 7/20; 35%, partial response 8/20; 40%). The median overall survival was 665 days. As for the adverse effects, the incidences of severe neutropenia and thrombocytopenia (grade 3-4) were 20% and 15%, which might be less toxic than conventional gemcitabine plus cisplatin therapy. The 24-h infusion of cisplatin combined with gemcitabine can be highly recommended as neoadjuvant chemotherapy for locally advanced urothelial cancer.

Background: Breast cancer is the leading cause of death among females in developed countries. Although the implementation of screening tests and the development of new therapies has increased the probability of remission, relapse rates still remain high. Numerous studies have indicated the connection between cancer initiating cells and slow cellular cycle cells, identified by their capacity to retain long labelling (LT+). Methods: We have designed a transgenic protein consisting in the C-terminal part of this protein, which acts by blocking endogenous PEDF in culture cell assays. Present work is based in doses-response in vitro assays as well as flow cytometry analysis of surface markers and cell cycle kinetic study of the tumour initiating cells.Results: In this study we show that this type of cells is present not only in cancer cell lines but also in cancer cells from patients with metastatic and advanced stage tumours. We also present new assays showing how stem cell self-renewal modulating proteins, such as PEDF, can modify the properties, expression of markers, and carcinogenicity of cancer stem cells. This protein has been involved in self-renewal in adult stem cells and has been described as anti-tumoral because of its anti-angiogenic effect. However, we show that PEDF enhances resistance in breast cancer patient cells in vitro culture by favoring a slow cellular cycle population (LT+). The PEDF signalling pathway could be a useful tool for controlling cancer stem cells self-renewal, and therefore control patient relapse. Conclusions: We demonstrate that it is possible to interfere with the self-renewal capacity of cancer stem cells, induce anoikis in vivo, and reduce resistance against Docetaxel treatment in cancer patient cells in vitro culture. We have also demonstrated that this PEDF modified protein produces a significant decrease in cancer stem cell markers. All these properties make this protein a potential application in clinical cancer therapies via co-administration with chemotherapy for relapse cancer treatment.