In human retinoblastoma Y79 cells okadaic acid-parthenolide co-treatment induces synergistic apoptotic effects, with PTEN as a key player.
Retinoblastoma is the most common intraocular malignancy of childhood. In developing countries, treatment is limited, long-term survival rates are low and current chemotherapy causes significant morbidity to pediatric patients and significantly limits dosing. Therefore there is an urgent need to identify new therapeutic strategies to improve the clinical outcome of patients with retinoblastoma. Here, we investigated the effects of two natural compounds okadaic acid (OKA) and parthenolide (PN) on human retinoblastoma Y79 cells. For the first time we showed that OKA/PN combination at subtoxic doses induces potent synergistic apoptotic effects accompanied by lowering in p-Akt levels, increasing in the stabilized forms of p53 and potent decrease in pS166-Mdm2. We also showed the key involvement of PTEN which, after OKA/PN treatment, potently increased before p53, thus suggesting that p53 activation was under PTEN action. Moreover, after PTEN-knockdown p-Akt/ pS166Mdm2 increased over basal levels and p53 significantly lowered, while OKA/PN treatment failed both to lower p-Akt and pS166-Mdm2 and to increase p53 below/over their basal levels respectively. OKA/PN treatment potently increased ROS levels whereas decreased those of GSH. Reducing cellular GSH by l-butathionine-[S,R]-sulfoximine treatment significantly anticipated the cytotoxic effect exerted by OKA/PN. Furthermore, the effects of OKA/PN treatment on both GSH content and cell viability were less pronounced in PTEN silenced cells than in control cells. The results provide strong suggestion for combining a treatment approach that targets the PTEN/Akt/Mdm2/p53 pathway.
Laboratory of Biochemistry; Department of Biological, Chemical and Pharmaceutical Sciences and Technologies; University of Palermo, Polyclinic; Palermo, Italy.
Riccardo
R
Di Fiore
Rosa
R
Drago-Ferrante
Antonella
A
D'Anneo
Giuseppa
G
Augello
Daniela
D
Carlisi
Anna
A
De Blasio
Michela
M
Giuliano
Giovanni
G
Tesoriere
Renza
R
Vento
D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D045744:Cell Line, Tumor; D048430:Cell Shape / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004354:Drug Screening Assays, Antitumor; D004357:Drug Synergism; D015870:Gene Expression; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D019319:Okadaic Acid / Q000494:pharmacology*; D018384:Oxidative Stress; D051059:PTEN Phosphohydrolase / Q000235:genetics / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051736:Proto-Oncogene Proteins c-mdm2 / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D012175:Retinoblastoma; D012717:Sesquiterpenes / Q000494:pharmacology*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
D000970:Antineoplastic Agents; D017382:Reactive Oxygen Species; D012717:Sesquiterpenes; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D019319:Okadaic Acid; C002669:parthenolide; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2; D051057:Proto-Oncogene Proteins c-akt; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human; D005978:Glutathione
PTEN/Akt/Mdm2/p53 pathway; Y79 cells; natural drugs; okadaic acid; oxidative stress; parthenolide; retinoblastoma; synergistic apoptotic effects