Inhibitor PF-04691502 works as a senolytic to regulate cellular senescence

Aging is a gradual process of natural change that occurs after reaching sexual maturity. It is also a known risk factor for many chronic diseases. Recent research has shown that senolytics can extend the lifespans and health spans of model organisms, and they have also been demonstrated effective in treating age-related diseases. In this study, we conducted a high-throughput screening of 156 drugs that targeted the PI3K/AKT/mTOR pathway to identify potential senolytic medications. Among these drugs, PF-04691502 was selected for further investigation to understand its molecular mechanism of action. Our findings indicate that PF-04691502, a dual inhibitor of PI3K/AKT and mTOR, specifically eliminates senescent cells. It reduces the expression levels of key markers of cellular senescence, such as SA-β-Gal, senescence-associated secretory phenotypes (SASPs) and p16INK4a. Additionally, PF-04691502 inhibits the phosphorylation of S6K and AKT, leading to the apoptosis of senescent cells. These results suggest that PF-04691502 holds promise as a new senolytic drug. This paper provides important insights into the potential application of PF-04691502 in the study of cell senescence.

HMGA1 augments palbociclib efficacy via PI3K/mTOR signaling in intrahepatic cholangiocarcinoma

BACKGROUND

Intrahepatic cholangiocarcinoma (iCCA) is a highly aggressive cancer that is challenging to diagnose at an early stage. Despite recent advances in combination chemotherapy, drug resistance limits the therapeutic value of this regimen. iCCA reportedly harbors high HMGA1 expression and pathway alterations, especially hyperactivation of the CCND1/CDK4/CDK6 and PI3K signaling pathway. In this study, we explored the potential of targeting CDK4/6 and PI3K inhibition to treat iCCA.

METHODS

The significance of HMGA1 in iCCA was investigated with in vitro/vivo experiments. Western blot, qPCR, dual-luciferase reporter and immunofluorescence assays were performed to examine the mechanism of HMGA1 induced CCND1 expression. CCK-8, western blot, transwell, 3D sphere formation and colony formation assays were conducted to predict the potential role of CDK4/6 inhibitors PI3K/mTOR inhibitors in iCCA treatment. Xenograft mouse models were also used to determine the efficacy of combination treatment strategies related to HMGA1 in iCCA.

RESULTS

HMGA1 promoted the proliferation, epithelial-mesenchymaltransition (EMT), metastasis and stemness of iCCA. In vitro studies showed that HMGA1 induced CCND1 expression via promoting CCND1 transcription and activating the PI3K signaling pathway. Palbociclib(CDK4/6 inhibitor) could suppress iCCA proliferation, migration and invasion, especially during the first 3 days. Although there was more stable attenuation of growth in the HIBEpic model, we observed substantial outgrowth in each hepatobiliary cancer cell model. PF-04691502(PI3K/mTOR inhibitor) exhibited similar effects to palbociclib. Compared with monotherapy, the combination retained effective inhibition for iCCA through the more potent and steady inhibition of CCND1, CDK4/6 and PI3K pathway. Furthermore, more significant inhibition of the common downstream signaling pathways is observed with the combination compared to monotherapy.

CONCLUSIONS

Our study reveals the potential therapeutic role of dual inhibition of CDK4/6 and PI3K/mTOR pathways in iCCA, and proposes a new paradigm for the clinical treatment of iCCA.

Synergistic cytotoxicity of dual PI3K/mTOR and FLT3 inhibition in FLT3-ITD AML cells

Acute myeloid leukemia (AML) is an aggressive hematopoietic malignancy, characterized by a heterogeneous genetic landscape and complex clonal evolution, with poor outcomes. Mutation at the internal tandem duplication of FLT3 (FLT3-ITD) is one of the most common somatic alterations in AML, associated with high relapse rates and poor survival due to the constitutive activation of the FLT3 receptor tyrosine kinase and its downstream effectors, such as PI3K signaling. Thus, aberrantly activated FLT3-kinase is regarded as an attractive target for therapy for this AML subtype, and a number of small molecule inhibitors of this kinase have been identified, some of which are approved for clinical practice. Nevertheless, acquired resistance to these molecules is often observed, leading to severe clinical outcomes. Therapeutic strategies to tackle resistance include combining FLT3 inhibitors with other antileukemic agents. Here, we report on the preclinical activity of the combination of the FLT3 inhibitor quizartinib with the dual PI3K/mTOR inhibitor PF-04691502 in FLT3-ITD cells. Briefly, we show that the association of these two molecules displays synergistic cytotoxicity in vitro in FLT3-ITD AML cells, triggering 90% cell death at nanomolar concentrations after 48 h.