Autophagic cell death associated to Sorafenib in renal cell carcinoma is mediated through Akt inhibition in an ERK1/2 independent fashion

Abstract

ObjectivesTo fully clarify the role of Mitogen Activated Protein Kinase in the therapeutic response to Sorafenib in Renal Cell Carcinoma as well as the cell death mechanism associated to this kinase inhibitor, we have evaluated the implication of several Mitogen Activated Protein Kinases in Renal Cell Carcinoma-derived cell lines.Materials and methodsAn experimental model of Renal Cell Carcinoma-derived cell lines (ACHN and 786-O cells) was evaluated in terms of viability by MTT assay, induction of apoptosis by caspase 3/7 activity, autophagy induction by LC3 lipidation, and p62 degradation and kinase activity using phospho-targeted antibodies. Knock down of ATG5 and ERK5 was performed using lentiviral vector coding specific shRNAResultsOur data discard Extracellular Regulated Kinase 1/2 and 5 as well as p38 Mitogen Activated Protein Kinase pathways as mediators of Sorafenib toxic effect but instead indicate that the inhibitory effect is exerted through the PI3K/Akt signalling pathway. Furthermore, we demonstrate that inhibition of Akt mediates cell death associated to Sorafenib without caspase activation, and this is consistent with the induction of autophagy, as indicated by the use of pharmacological and genetic approaches.ConclusionThe present report demonstrates that Sorafenib exerts its toxic effect through the induction of autophagy in an Akt-dependent fashion without the implication of Mitogen Activated Protein Kinase. Therefore, our data discard the use of inhibitors of the RAF-MEK-ERK1/2 signalling pathway in RCC and support the use of pro-autophagic compounds, opening new therapeutic opportunities for Renal Cell Carcinoma.

SETD2 mutation in renal clear cell carcinoma suppress autophagy via regulation of ATG12

“…The apparent defect in the ATG12-dependent conjugation system was associated with decrease autophagic flux, in accordance with the role for this ubiquitin-like protein conjugation system in autophagosome formation and expansion 38,39 . Considering the impact autophagy can have on cancer cells survival or dismiss 54 , targeting the autophagy process has been considered as potential therapeutic strategy to combat various type of tumors, including in patient with ccRCC [20][21][22][23][24] .…”

“…Hence, interventions to both stimulate and inhibit autophagy have been proposed as cancer therapies 19 . Likewise, inhibition and induction of autophagy have both been considered as therapeutic strategies to combat RCC [20][21][22][23][24] . Additional studies suggest that autophagic gene polymorphisms are associated with ccRCC risk and patient outcome 25,26 .…”

CDK5: Key Regulator of Apoptosis and Cell Survival

“…Autophagy activation insures and protects cancer cells, and this process in known as adaptive autophagy, which is directly associated with CDK5. Cancer cells subjected to chemotherapy treatments have the ability to induce autophagic cell death through the inhibition of Akt [108]. Recent studies have showed that autophagy could be regulated using anticancer drugs.…”

CDK5RAP3 Participates in Autophagy Regulation and Is Downregulated in Renal Cancer

“…However, severe activation of autophagy, known as maladaptive autophagy, could directly induce cell death [17–20]. Therefore, the level of autophagy is strictly controlled by various signaling pathways, such as PI3K/Akt/mTOR and ERK1/2 [23]. Blockade of autophagy in many cancers (including renal cancer cells) induces the exhaustion of metabolic substrates and causes energetic impairment, which eventually leads to cell death [27].…”

“…It has been reported that cancer cells are able to activate autophagy when exposed to chemotherapy drugs [20–22]. In renal cancer, sorafenib could induce autophagic cell death through Akt inhibition [23]. However, blocking autophagy with chloroquine enhances the anticancer effect of sunitinib [24].…”