Precision Medicine Highlights Dysregulation of the CDK4/6 Cell Cycle Regulatory Pathway in Pediatric, Adolescents and Young Adult Sarcomas.

Despite improved therapeutic and clinical outcomes for patients with localized diseases, outcomes for pediatric and AYA sarcoma patients with high-grade or aggressive disease are still relatively poor. With advancements in next generation sequencing (NGS), precision medicine now provides a strategy to improve outcomes in patients with aggressive disease by identifying biomarkers of therapeutic sensitivity or resistance. The integration of NGS into clinical decision making not only increases the accuracy of diagnosis and prognosis, but also has the potential to identify effective and less toxic therapies for pediatric and AYA sarcomas. Genome and transcriptome profiling have detected dysregulation of the CDK4/6 cell cycle regulatory pathway in subpopulations of pediatric and AYA OS, RMS, and EWS. In these patients, the inhibition of CDK4/6 represents a promising precision medicine-guided therapy. There is a critical need, however, to identify novel and promising combination therapies to fight the development of resistance to CDK4/6 inhibition. In this review, we offer rationale and perspective on the promise and challenges of this therapeutic approach.

Integrative Multi-OMICs Identifies Therapeutic Response Biomarkers and Confirms Fidelity of Clinically Annotated, Serially Passaged Patient-Derived Xenografts Established from Primary and Metastatic Pediatric and AYA Solid Tumors.

Establishment of clinically annotated, molecularly characterized, patient-derived xenografts (PDXs) from treatment-naïve and pretreated patients provides a platform to test precision genomics-guided therapies. An integrated multi-OMICS pipeline was developed to identify cancer-associated pathways and evaluate stability of molecular signatures in a panel of pediatric and AYA PDXs following serial passaging in mice. Original solid tumor samples and their corresponding PDXs were evaluated by whole-genome sequencing, RNA-seq, immunoblotting, pathway enrichment analyses, and the drug−gene interaction database to identify as well as cross-validate actionable targets in patients with sarcomas or Wilms tumors. While some divergence between original tumor and the respective PDX was evident, majority of alterations were not functionally impactful, and oncogenic pathway activation was maintained following serial passaging. CDK4/6 and BETs were prioritized as biomarkers of therapeutic response in osteosarcoma PDXs with pertinent molecular signatures. Inhibition of CDK4/6 or BETs decreased osteosarcoma PDX growth (two-way ANOVA, p < 0.05) confirming mechanistic involvement in growth. Linking patient treatment history with molecular and efficacy data in PDX will provide a strong rationale for targeted therapy and improve our understanding of which therapy is most beneficial in patients at diagnosis and in those already exposed to therapy.

Inhibition of PI3K pathway using BKM120 intensified the chemo-sensitivity of breast cancer cells to arsenic trioxide (ATO).

Although conventional therapeutic approaches have brought remarkable advantages for the treatment of breast cancer (BC), drug-resistance still remains as a leading cause of tumor recurrence in this malignancy. In the present study, we designed experiments to evaluate the therapeutic value of PI3K inhibition in combination with Arsenic trioxide (ATO) in MCF-7 cells. The results of our study manifested that BKM120 sensitized MCF-7 cells to the lower concentrations of ATO. The significant anti-cancer effect of PI3K inhibition became even more evident when we found that BKM120, either as a single agent or in combination with ATO, reduced clonogenic ability of anoikis-resistant stem-like MCF-7 cells. Our findings also showed that BKM120 augmented ATO-induced anti-proliferative effects through inducing G1 arrest and reducing the incorporation of BrdU into the synthesized DNA of drugs-treated cells, which was coupled with c-Myc-mediated suppression of hTERT expression. Moreover, we found that in the presence of PI3K inhibitor, ATO is able to more profoundly induce apoptosis in MCF-7 cells, as revealed by the increment in the percentage of haplodiploid sub-G1 cells and the externalization of phosphatidylserine. Real-time PCR analysis also revealed that probably down-regulation of survivin coupled with up-regulation of forkhead family transcription factors is responsible for the enhancive effect of drugs in this cell line. Conclusively, this study shed lights on the effect of PI3K inhibition in chemo-sensitivity of MCF-7 cells, disclosing that combination of BKM120 and ATO could be a promising therapeutic approach in BC.

Synergistic Effects of PI3K and c-Myc Co-targeting in Acute Leukemia: Shedding New Light on Resistance to Selective PI3K-δ Inhibitor CAL-101.

Enthusiasms into the application of PI3K-δ inhibitor CAL-101 has been muted due to the over-activation of compensatory molecules. Our results delineated that c-Myc suppression using 10058-F4 enhanced CAL-101 cytotoxicity in less sensitive cells through different mechanisms based on p53 status; while CAL-101-plus-10058-F4 induced G1 arrest in wild-type p53-expressing leukemic cells, no conspicuous increase in G1 was noted in U937 cells harboring mutant p53. Conclusively, this study shed lights on the role of c-Myc oncoprotein in acute leukemia cells sensitivity to PI3K inhibitor and outlined that the combination of c-Myc inhibitor and CAL-101 may be a promising therapeutic approach in leukemia.

Suppression of c-Myc using 10058-F4 exerts caspase-3-dependent apoptosis and intensifies the antileukemic effect of vincristine in pre-B acute lymphoblastic leukemia cells.

Despite an old history behind the identification of the leading role of c-Myc in leukemogenesis, the road to constructing a therapeutic perspective for this molecule in acute lymphoblastic leukemia (ALL) is yet mesmerizing. This study was designed to provide a better outlook for the anticancer property of 10058-F4, an appealing inhibitor of c-Myc, in pre-B ALL cell lines either in the context of monotherapy or in combination with chemotherapeutic drugs. Our results declared that abrogation of c-Myc decreased the proliferative capacity of pre-B ALL-derived cells through halting the transition of the cells from G1 phase, and reducing the replicative potential of both REH and Nalm-6 cells, at least partly, through c-Myc-mediated suppression of human telomerase reverse transcriptase. Moreover, 10058-F4 potently induced a caspase-3-dependent apoptosis in pre-B ALL cells via shifting the balance between pro- and anti-apoptotic target genes. Although the inhibition of PI3Kδ using Idelalisib upregulated the messenger RNA expression of autophagy-related genes in 10058-F4-treated cells, treatment with autophagy inhibitor chloroquine decreased viability of the cells, either as a single agent or in combination with Idelalisib and/or 10058-F4; suggesting that the activation of autophagy in pre-B ALL cells could blunt apoptotic events and attenuate anticancer effect of both c-Myc and PI3K inhibitors. Finally, the results of our synergistic experiments delineated that 10058-F4 produced a synergistic effect with vincristine and provided an enhanced therapeutic efficacy in ALL cells, highlighting that c-Myc oncoprotein could be a bona fide target for the treatment of ALL.

Small molecule inhibitor of c-Myc 10058-F4 inhibits proliferation and induces apoptosis in acute leukemia cells, irrespective of PTEN status.

Based on the frequent over-expression of c-Myc in hematologic malignancies and its crucial role in the regulation of diverse oncogenic pathways involved in leukomogenesis, intense interest has recently focused on this factor as an appealing therapeutically target in leukemia. In the present study, we aimed to investigate the anti-leukemic property of small molecule inhibitor of c-Myc 10058-F4 in two distinct acute leukemia cell lines consist of acute promyelocytic leukemia (APL)-derived NB4 cells (with wild-type PTEN) and acute lymphoblastic leukemia (ALL)-derived Nalm-6 cells (with down-regulated PTEN). 10058-F4 effectively reduced survival of leukemic cells; however, we found a different cell sensitivity pattern in the tested cell lines. To the best of our knowledge, no study has addressed the underlying mechanisms responsible for leukemic cell resistance to 10058-F4, and we propose for the first time that the effectiveness of c-Myc inhibition might be attenuated through over-activated phosphoinositide 3-kinase (PI3K) in less sensitive Nalm-6 cells. Notably, we failed to find an obvious correlation between PTEN status and cell sensitivity to the inhibitor in a panel of hematologic malignant cells. Beyond 10058-F4 cytotoxicity as a single agent, synergistic experiments also delineated that pharmaceutical targeting of c-Myc could potentiate the anti-cancer effect of both vincristine and Arsenic trioxide in ALL and APL cells, respectively. In conclusion, this study sheds light on the potent anti-leukemic characteristics of 10058-F4 and provide an interesting evidence to the application of this agent in combination with PI3K inhibitors especially in acute leukemia with over-activated PI3K, irrespective of PTEN status.

Inhibition of PI3K signaling pathway enhances the chemosensitivity of APL cells to ATO: Proposing novel therapeutic potential for BKM120.

The latest molecular investigations leading to the discovery of the brand-new mechanisms associated to immortalized nature of cancer cells have questioned the efficacy of the conventional therapies and have increased the demand for more influential approaches, especially in the context of synergistic strategies. In an effort to enhance the effectiveness of acute promyelocytic leukemia (APL) treatment and to investigate the potential therapeutic value of Phosphoinositide 3-kinase (PI3K) inhibition synergism with chemotherapy, we designed experiments to evaluate the effect of Arsenic trioxide (ATO) in combination with BKM120 for the treatment of APL-derived NB4 cells. The results of the present study highlighted the favorable outcome of the PI3K inhibition using BKM120 in potentiating the anti-cancer effect of ATO, while reducing its cytotoxic concentration. Investigating the molecular mechanisms leading to this synergistic effect showed that probably down-regulation of the transcription factor SIRT1 coupled with suppression of c-Myc might halt the progression of the cell cycle from the G1 phase, resulting in the enhanced growth suppressive effect in ATO-plus-BKM120 combination. Moreover, we found that the positive regulatory role of the PI3K inhibition in augmenting the intracellular level of reactive oxygen species disturbed the balance between the death promoter and death repressor genes, which in turn amplified the caspase-3-dependent apoptotic activity of ATO in NB4. By and large, this study laid a therapeutic value on BKM120 in combination with ATO and suggested this combination as a novel therapeutic strategy that may be clinically accessible in the near future.