AurkA inhibitors enhance the effects of B-RAF and MEK inhibitors in melanoma treatment

Background: Aurora kinase A (AurkA) is over-expressed in melanoma and its inhibition has been observed to limit tumor growth, suggesting a potential role in melanoma treatment. Methods: A human melanoma cell line with the B-RAF (V600E) mutation (A375mel) was exposed to B-RAF inhibitor (GSK2118436), MEK inhibitor (GSK1120212) and AurkA inhibitor (MLN8054) as single agents or in various combinations (BRAF plus AurkA inhibitor, MEK plus AurkA inhibitor or triple combination BRAF plus MEK plus AurkA inhibitor). Cell proliferation was assessed using xCELLigence technology. Total protein extracts were examined for p53 and c-Myc protein expression by Western blot analysis. Drug anti-tumor effects were further assessed using a 3D-human melanoma skin reconstruction model, in which tissues were incubated with serum-free medium containing control, B-RAF plus MEK inhibitor, MEK plus AurkA inhibitor or the triple combination. Results: AurkA inhibitor plus B-RAF inhibitor, AurkA inhibitor plus MEK inhibitor or triple combination had a markedly greater anti-proliferative effect on A375 (BRAFV600E) melanoma cells than single agents. In the 3D human skin model, the triple combination had a greater anti-tumor effect at the epidermal/dermal junction than control or either double combination. However, S-100 and Ki-67 positively stained spindle-shaped cells were detected in the dermal stratum, suggesting the presence of alive and proliferating melanoma cells. Conclusions: These findings provide new prospects for melanoma research, including combined B-RAF/AurkA inhibition for B-RAF mutated melanomas and MEK/AurkA inhibitor combination for patients without B-RAF mutations. Moreover, for the first time, we have shown that a B-RAF, MEK and AurkA inhibitor triple drug combination offers increased efficacy against melanoma cell growth and might be considered as a potential treatment strategy for enhancing clinical response in melanoma. However, although this triple drug combination was more effective at the epidermal/dermal junction, the suggested presence of alive and proliferating melanoma cells in the dermal stratum could result in drug resistance and disease recurrence. Molecular characterization of these dermal cells may be critical for the development of novel therapeutic strategies

A novel mechanism of inactivation of cycline-dependent kinase inhibitor p27Kip1 in thyroid cancer: cytoplasmic delocalization induced by the protein kinase Akt

Esistono considerevoli evidenze a proposito del fatto che l’inattivazione dell’inibitore delle chinasi ciclino-dipendenti p27 rappresenti un evento fondamentale nello sviluppo dei tumori umani. L’inattivazione di p27 nei tumori umani avviene sia mediante la perdita di espressione sia mediante sequestro citoplasmatico della proteina. Il lavoro da me svolto durante la tesi di dottorato ha contribuito ad una migliore comprensione delle alterazioni della funzione di p27 nel cancro della tiroide (e della mammella) ed all’identificazione dei diversi meccanismi che contribuiscono a tale alterazione. I risultati presentati dimostrano che la serin-treonin chinasi PKB/Akt regola la proliferazione cellulare in cellule tumorali tiroidee attraverso la fosforilazione diretta di p27. La treonina 157, che mappa all’interno del sito di localizzazione nucleare della proteina, e la treonina 198 costituiscono i siti di fosforilazione nella proteina p27 da parte di PKB/Akt. la fosforilazione di p27 da parte di PKB/Akt provoca il legame alle proteine della famiglia 14.3.3 e l’accumulo di p27 nel citoplasma delle cellule cancerose, impedendo l’arresto del ciclo cellulare in fase G1 dipendente da p27. I mutanti non fosforilabili di p27 (T157A-T198A) non legano 14.3.3, si accumulano nel nucleo e risultano insensibili all’attività mitogenica indotta da Akt. Esperimenti effettuati su 5 linee cellulari rappresentative dei diversi istotipi del carcinoma tiroideo (papillifero, follicolare ed anaplastico) hanno infine dimostrato che l’attivazione costitutiva della via di trasduzione del segnale che attiva la chinasi PKB/Akt, la via della fosfatidil-inositolo-3 chinasi (PI3K), gioca un ruolo importante nella carcinogenesi tiroidea e che p27 rappresenta una molecola importante attraverso cui tale via promuove la crescita in cellule derivate da carcinoma della tiroide. Utilizzando specifici inibitori della PI3K (LY294002, Wortmannina. PTEN) o un costrutto codificante per una forma costitutivamente attiva di PKB/Akt (Akt miristilato) abbiamo dimostrato che il controllo PI3K/Akt-dipendente della proliferazione delle cellule tiroidee avviene mediante la regolazione della localizzazione subcellulare di p27; che la localizzazione di p27 è dipendente dalla fosforilazione Akt-dipendente sui residui T157 e T198; infine che p27 fosforilata sui residui T157-T198 si accumula nel citoplasma di cellule tumorali tiroidee e ciò coincide con l’attivazione di Akt

Controversial Role of Kisspeptins/KiSS-1R Signaling System in Tumor Development

KiSS-1 was first described as a metastasis suppressor gene in malignant melanoma. KiSS-1 encodes a 145 amino-acid residue peptide that is further processed, producing the 54 amino acid metastin and shorter peptides collectively named kisspeptins (KPs). KPs bind and activate KiSS-1R (GPR54). Although the KPs system has been extensively studied for its role in endocrinology of reproductive axis in mammals, its role in cancer is still controversial. Experimental evidences show that KP system exerts an anti-metastatic effect by the regulation of cellular migration and invasion in several cancer types. However, the role of KPs/KiSS-1R is very complex. Genomic studies suggest that KiSS-1/KiSS-1R expression might be different in the various stages of tumor development. Furthermore, overexpression of KiSS-1R has been reported to elicit drug resistance in triple negative breast cancer. In this review, we focused on multiple functions exerted by the KPs/KiSS-1R system in regulating tumor progression

Role of Microenvironment on the Fate of Disseminating Cancer Stem Cells.

Disseminating Cancer Stem Cells (CSCs) initiate growth in specific niches of the host tissues, the cellular and molecular components of which sustain signaling pathways that support their survival, self-renewal dormancy and reactivation. In the metastatic niche, tumor cells may enter in a dormant state to survive and, consequently, the metastasis can remain latent for years. Despite the clinical importance of metastatic latency, little is known about what induces CSCs to enter a dormant state and what allows them to remain viable for years in this state. CSCs exhibit genetic, epigenetic and cellular adaptations that confer resistance to classical therapeutic approaches. The identification of potential CSC targets is complicated by the fact that CSCs may arise as a consequence of their relationship with the local microenvironment into the metastatic niches. Indeed, microenvironment modulates the capability of CSCs to evade the innate immune response and survive. Some new therapeutic options that include drugs targeting microenvironment components are achieving encouraging results in reducing the number of CSCs in tumors and/or overcoming their resistance in preclinical studies. This review will focus on specific CSC features with an emphasis on the role of tumor microenvironment in supporting metastatic dissemination of CSCs. In addition, it sheds light on potential microenvironment-targeted therapies aimed to counteract seeding and survival of CSCs in the metastatic niche

Minireview: The Epigenetic Modulation of KISS1 in Reproduction and Cancer

Epigenetics describes how both lifestyle and environment may affect human health through the modulation of genome functions and without any change to the DNA nucleotide sequence. The discovery of several epigenetic mechanisms and the possibility to deliver epigenetic marks in cells, gametes, and biological fluids has opened up new perspectives in the prevention, diagnosis, and treatment of human diseases. In this respect, the depth of knowledge of epigenetic mechanisms is fundamental to preserving health status and to developing targeted interventions. In this minireview, we summarize the epigenetic modulation of the KISS1 gene in order to provide an example of epigenetic regulation in health and disease

Controversial Role of Kisspeptins/KiSS-1R Signaling System in Tumor Development

KiSS-1 was first described as a metastasis suppressor gene in malignant melanoma. KiSS-1 encodes a 145 amino-acid residue peptide that is further processed, producing the 54 amino acid metastin and shorter peptides collectively named kisspeptins (KPs). KPs bind and activate KiSS-1R (GPR54). Although the KPs system has been extensively studied for its role in endocrinology of reproductive axis in mammals, its role in cancer is still controversial. Experimental evidences show that KP system exerts an anti-metastatic effect by the regulation of cellular migration and invasion in several cancer types. However, the role of KPs/KiSS-1R is very complex. Genomic studies suggest that KiSS-1/KiSS-1R expression might be different in the various stages of tumor development. Furthermore, overexpression of KiSS-1R has been reported to elicit drug resistance in triple negative breast cancer. In this review, we focused on multiple functions exerted by the KPs/KiSS-1R system in regulating tumor progression