Characterization of colon cancer stem cells and their response to treatment with extracts of medical plants

Il cancro del colon-retto è una delle neoplasie più frequenti, ad alto tasso di mortalità, causato dall’interazione di fattori genetici e ambientali. Parallelamente al modello stocastico, secondo il quale tutte le cellule tumorali (CT) hanno una stessa probabilità di rigenerare un tumore, sta prendendo piede il modello che vede solamente in un piccolissimo sottogruppo di cellule staminali tumorali (CST) la capacità di dar luogo e sostenere la crescita tumorale. Dalla letteratura si evince come le CST mostrino deregolazioni a carico di geni implicati in: chemio-resistenza, transizione epitelio-mesenchimale (EMT), auto-rinnovamento incontrollato, processi peculiari delle CST, che favoriscono l’insorgenza di un fenotipo tumorale. Lo scopo del progetto di Dottorato è stato quello di isolare e caratterizzare le CST sia da linee cellulari tumorali che da biopsie di tumore al colon-retto, per identificare marcatori tumorali utili a delineare le fasi di progressione del tumore e di individuare potenziali bersagli terapeutici. Inoltre, ho sottoposto le CT e le CST di una linea di adenocarcinoma del colon-retto (HCA7), a trattamento con l’estratto naturale di T. cordifolia, pianta utilizzata della medicina Ayurvedica, ed uno dei suoi principi attivi, la berberina, allo scopo di verificarne l'efficacia antitumorale. Ho osservato importanti deregolazioni nelle popolazioni cellulari trattate, a carico di diversi geni coinvolti principalmente nella EMT, nella regolazione del ciclo cellulare e della apoptosi e nel favorire un fenotipo chemio-resistente. I livelli di espressione di questi geni sono risultati essere significativamente sotto-espressi, sia nelle CT trattate che nelle CST trattate. I risultati che ho ottenuto depongono a favore di un potenziale ruolo attivo della sostanza naturale sottoposta ad indagine, nel contrastare molti di quei processi fondamentali per lo sviluppo di un fenotipo tumorale. Inoltre, i miei dati avvallano anche l’ipotesi che vede le CST come potenziali bersagli terapeutici, per ottenere un effetto mirato su questa popolazione cellulare tumorale.Colorectal cancer is one of the most frequent cancer, with a high mortality rate, caused by the interaction of genetic and environmental factors. Parallel to the stochastic model, according to which all tumor cells (CT) have the same probability of regenerating a tumor, there is a new model that look in a very small subset of cancer stem cells (CST) the responsible of tumor growth. In the literature, CSTs shows important deregulations on genes implicated in: chemo-resistance, epithelial-mesenchymal transition (EMT), uncontrolled self-renewal, peculiar processes of this small subpopulation, which favor the onset of a tumor phenotype . The aim of my PhD project was to isolate and characterize CSTs both from tumor cell lines and from colorectal cancer biopsies, in order to identify tumor markers useful for delineating the phases of tumor progression and identifying potential therapeutic targets. In addition, I treated the CT and CST of a line of colorectal adenocarcinoma (HCA7) with the natural extract of T. cordifolia, a plant used in Ayurvedic medicine, and one of its active ingredients, berberine, in order to verify its antitumor efficacy. I observed important deregulations in treated cell populations, dependent on several genes involved mainly in EMT, in cell cycle regulation and apoptosis, but also in promoting a chemo-resistant phenotype. The expression levels of these genes were found to be significantly under-expressed, both in the treated CTs and in the treated CSTs. The results I have obtained are in favor of a potential active role of the investigated natural substance, in countering many of those fundamental processes for the development of a tumor phenotype. Furthermore, my data also support the hypothesis that CSTs are potential therapeutic targets for the purpose of achieving a targeted effect on this cell tumor population

Berberine and Tinospora cordifolia exert a potential anticancer effect on colon cancer cells by acting on specific pathways

Berberine (BBR) is a natural active principle with potential antitumor activity. The compound targets multiple cell signaling pathways, including proliferation, differentiation, and epithelial-mesenchymal transition. The aim of this study was to elucidate the mechanisms behind the anticancer activity of BBR by comparing the effects of purified BBR with those of the extract of Tinospora cordifolia, a medicinal plant that produces this metabolite. The expression levels of a panel of 44 selected genes in human colon adenocarcinoma (HCA-7) cell line were quantified by real-time polymerase chain reaction (PCR). BBR treatment resulted in a time- and dose-dependent down regulation of 33 genes differently involved in cell cycle, differentiation, and epithelial-mesenchymal transition. The trend was confirmed across the two types of treatment, the two time points, and the different absolute dosage of BBR. These findings suggest that the presence of BBR in T. cordifolia extract significantly contributes to its antiproliferative activity

Isolation and characterization of cancer stem cells in head and neck squamous cell carcinoma

The hypothesis that a small subset of cells with characteristics of staminality is essential for the cancer onset has been widely studied in many tumors, included head-neck cancer, the seventh most common cancer in humans (1). These cells represent a small oncogenic subpopulation, with a characteristic phenotype that confers them a greater resistance to chemotherapy and radiotherapy (2). In this study the expression profile of some genes that differentiates cancer stem cells (CSC) from tumor cell of origin (TC) has been evaluated using Real Time PCR. Three cell lines, PE46, PE15 and HEP2, obtained from head and neck squamous cell carcinoma, where placed in culture, in absence of serum and in the presence of specific growth factors, giving rise to a spheroid cell subpopulation, with characteristics belonging to CSC. CSC were isolated using a selective filtration procedure based on beads labeled with the anti-CD44, that recognize a specific antigen of CSC in head and neck cancer (1). Few genes potentially involved in the onset and progression of oral cancer, were eval- uated in Real Time PCR, in order to compare their expression in CSC respect TC. All the three cell lines showed a common expression profile among the stem cell markers, resulting in an overexpression of the CD44 and ALDH1A in the spheroid population. Many of the investigated tumor markers were highly over-expressed in CSC, like TNFα, a pro-inflammatory factor that inhibits precancerous cell death, TP63, which is associated with an increase in the malignant transformation and a poor prognosis, and S100A4, a pro-inflammatory mediator involved in epithelial-mesenchymal transition of cancer cells. These results suggest the potential role of CSC in the tumor invasiveness. The characterization of CSC may lead to an improvement in the diagnosis and cancer therapy, allowing implementing treatments able to destroy cells which are probably involved in the process of metastasis