Synergistic Antitumor Effect of BKM120 with Prima-1Met Via Inhibiting PI3K/AKT/mTOR and CPSF4/hTERT Signaling and Reactivating Mutant P53

Abstract

Background/Aims: PI3KCA and mutant p53 are associated with tumorigenesis and the development of cancers. NVP-BKM120, a selective pan-PI3K inhibitor, exerts the antitumor activity by suppressing the PI3K signaling pathway. Prima-1^Met, a low molecular weight compound, can rescue the gain-of-function of mutant p53 by restoring its transcriptional function. In this study, we investigated whether PI3K inhibition combined with mutant p53 reactivation could enhance the antitumor effect in thyroid cancer cells. Methods: The effects of BKM120 and Prima-1^Met on the proliferation, apoptosis, migration and invasion of thyroid cancer cells were measured by MTT, colony formation, flow cytometry, wound-healing and transwell assays, respectively. Thyroid differentiation was assessed by detecting the expression levels of specific markers using RT-PCR and Western blot. The in vivo antitumor efficacy was analyzed in a mouse xenograft model. Results: The combinational treatment of BKM120 and Prima-1^Met significantly enhanced the inhibitions of cell viability, colony formation, migration and invasion, and the induction of apoptosis in thyroid cell lines, and synergistically suppressed tumor xenograft growth by inhibiting the PI3K/Akt/mTOR and EMT signaling pathways, up-regulating p53 targeted genes, and triggering the release of cytochrome c. Moreover, the combination of BKM120 and Prima-1^Met suppressed the stemlike traits of thyroid cancer cells and promoted their differentiation by upregulating the expression of thyroid-specific differentiation markers and repressing the expression of cancer stem cell markers. Furthermore, the mechanism study demonstrated that the combinational treatment synergistically abrogated the binding of CPSF4 at the promoter of hTERT and thus suppressed hTERT expression. Consistently, overexpression of hTERT rescued the inhibitions of cell viability, invasion and stem-like traits mediated by the combination of BKM120 and Prima-1^Met. Conclusion: Our results showed that the combination of BKM120 with Prima-1^Met synergistically suppressed the growth of thyroid cancer cells and tumor xenografts via inhibiting PI3K/Akt/mTOR and CPSF4/hTERT signaling and reactivating mutant p53.

Combinatorial Therapies in Thyroid Cancer: An Overview of Preclinical and Clinical Progresses

“…In this context, the molecule PRIMA-1Met reactivates mutant p53 and has been already tested in melanoma, showing encouraging results in combination with the BRAF and MEK inhibitors [73,74]. Recently, the pan PI3K inhibitor NVP-BKM120, causing the suppression of PI3K downstream signaling, has been associated with the PRIMA-1Met and displayed synergistic antitumour effects both in vitro and in vivo thyroid cancer, thus opening the doors to a potential novel approach to the thyroid cancer treatment [75].…”

“…The current targets known for this molecule are VEGFR1-3, fibroblast growth factor receptors 1-4 (FGFR1-4), RET, c-kit, PDGFRa, and mast/stem cell growth factor receptor (SCFR) [81]. These molecules thus interact with many essential functions of cancer cells as proliferation, apoptosis, autophagy, and angiogenesis [75], but, alone, weak antiproliferative properties are observed for sorafenib and for lenvatinib, clinical studies discussed below showed adverse effects for >50% of patients included hypertension, diarrhea, or decreased appetite [81]. In this context, the strategy to combine these molecules to potentiate their properties with other molecules has been the object of preclinical studies described below.…”

“…Concerning thyroid cancer, different classes of molecules have been tested both in vitro and in vivo with promising results. Among them, histone deacetylase (HDAC) inhibitors, antimalaria drug, antidiabetic drug, curcumin, or autophagy inhibitor have been tested in combination with sorafenib [75,[82][83][84].…”

“…with promising results. Among them, histone deacetylase (HDAC) inhibitors, antimalaria drug, antidiabetic drug, curcumin, or autophagy inhibitor have been tested in combination with sorafenib [75,[82][83][84]. Besides, RNA interference technology (siRNA) silencing AKT was combined with sorafenib resulting in a reduction of phosphorylation levels of both ERK and AKT.…”

Genetic alterations in anaplastic thyroid carcinoma and targeted therapies (Review)

“…It has been proven that NVP-BKM120 suppresses downstream factors of PI3K, including downregulation of p-Akt and p-S6R and cancer stem markers. A previous study by our group suggested that synergistic action of BKM120 and Prima-1 Met effectively suppressed the proliferation and migration and promoted the differentiation of thyroid cancer cells in vivo and in vitro (19). Radiation therapy is another important treatment for thyroid cancer, but low-dose radiation induces the activation of the PI3K/Akt/mTOR pathway, leading to the occurrence of epithelial-mesenchymal transition (EMT).…”