Co-encapsulated nanoparticles of Erlotinib and Quercetin for targeting lung cancer through nuclear EGFR and PI3K/AKT inhibition

Erlotinib-based EGFR targeted therapy has proven significant clinical improvement against non-small cell lung cancer (NSCLC). However, the anticancer activity of Erlotinib (Ertb) is limited by the development of Ertb resistance and possess a challenge to clinicians and patients. To explore a better therapeutic strategy, we evaluated Ertb in combinations with different natural products. We identified that Ertb and Quercetin (Quer) combination is more synergistic against A549 and NCI H460 cells compared to Ertb with Fisetin/Carnosic acid/Luteolin. To further improve the efficacy and overcome the limitation of free therapeutics, Ertb and Quer loaded solid lipid nanoparticles (EQNPs) were prepared using Chitosan-MA-TPGS polymer by hot homogenization method. The drug-loaded nanoparticles (NPs) have shown high encapsulation efficiency (77% Ertb and 71.4% Quer) as well as small particle size of 87.3 ± 0.78 nm and positive zeta potential + 13.4 ± 1.12 mV. At pH 5.5, Ertb and Quer were released at their highest levels. We found that, EQNPs decreased the expression of P-glycoprotein (P-gp) and nuclear epidermal growth factor receptor (nEGFR). EQNPs increased the uptake of Ertb and Quer, and apoptosis induction in Ertb resistant A549/ER cells. Further, in vivo EQNPs formulation have shown increased uptake of nanoparticles in the lung tissue and significantly reduced the expression of nEGFR. Thus, EQNPs may be developed as a targeted medicine with minimum side effects for treatment of NSCLC to improve the quality of life and survival of NSCLC patients.

Targeting the PI3K/Akt/mTOR pathway in non-small cell lung cancer (NSCLC)

The traditional classification of lung cancer into small cell lung cancer and non‐small cell lung cancer (NSCLC) has been transformed with the increased understanding of the molecular alterations and genomic biomarkers that drive the development of lung cancer. Increased activation of the phosphatidylinositol 3‐kinase (PI3K)/Akt/mechanistic target of rapamycin (mTOR) pathway leads to numerous hallmarks of cancer and this pathway represents an attractive target for novel anticancer therapies. In NSCLC, the PI3K/Akt/mTOR pathway has been heavily implicated in both tumorigenesis and the progression of disease. A number of specific inhibitors of PI3K, Akt and mTOR are currently under development and in various stages of preclinical investigation and in early phase clinical trials for NSCLC. Early evidence has yielded disappointing results. Clinical trials, however, have been performed on predominantly molecularly unselected populations, and patient enrichment strategies using high‐precision predictive biomarkers in future trials will increase the likelihood of success. A greater understanding of the underlying molecular biology including epigenetic alterations is also crucial to allow for the detection of appropriate biomarkers and guide combination approaches.

Phosphatidylinositol 3-kinase (PI3K) inhibitors as cancer therapeutics

Phosphatidylinositol 3-kinases (PI3Ks) are lipid kinases that regulate diverse cellular processes including proliferation, adhesion, survival, and motility. Dysregulated PI3K pathway signaling occurs in one-third of human tumors. Aberrantly activated PI3K signaling also confers sensitivity and resistance to conventional therapies. PI3K has been recognized as an attractive molecular target for novel anti-cancer molecules. In the last few years, several classes of potent and selective small molecule PI3K inhibitors have been developed, and at least fifteen compounds have progressed into clinical trials as new anticancer drugs. Among these, idelalisib has advanced to phase III trials in patients with advanced indolent non-Hodgkin's lymphoma and mantle cell lymphoma. In this review, we summarized the major molecules of PI3K signaling pathway, and discussed the preclinical models and clinical trials of potent small-molecule PI3K inhibitors.

Preclinical rationale for PI3K/Akt/mTOR pathway inhibitors as therapy for epidermal growth factor receptor inhibitor-resistant non-small-cell lung cancer

Mutations in the epidermal growth factor receptor gene (EGFR) are frequently observed in non-small-cell lung cancer (NSCLC), occurring in about 40% to 60% of never-smokers and in about 17% of patients with adenocarcinomas. EGFR tyrosine kinase inhibitors (TKIs), such as gefitinib and erlotinib, have transformed therapy for patients with EGFR-mutant NSCLC and have proved superior to chemotherapy as first-line treatment for this patient group. Despite these benefits, there are currently 2 key challenges associated with EGFR inhibitor therapy for patients with NSCLC. First, only 85% to 90% of patients with the EGFR mutation derive clinical benefit from EGFR TKIs, with the remainder demonstrating innate resistance to therapy. Second, acquired resistance to EGFR TKIs inevitably occurs in patients who initially respond to therapy, with a median duration of response of about 10 months. Mutant EGFR activates various subcellular signaling cascades, including the phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway, which demonstrates maintained activity in a variety of TKI-resistant cancers. Given the fundamental role of the PI3K/Akt/mTOR pathway in tumor oncogenesis, proliferation, and survival, PI3K pathway inhibitors have emerged as a possible solution to the problem of EGFR TKI resistance. However resistance to EGFR TKIs is associated with considerable heterogeneity and complexity. Preclinical experiments investigating these phenomena suggest that in some patients, PI3K inhibitors will have to be paired with other targeted agents if they are to be effective. This review discusses the preclinical data supporting PI3K/Akt/mTOR pathway inhibitor combinations in EGFR TKI-resistant NSCLC from the perspective of the various agents currently being investigated in clinical trials.

The Biological Role of PI3K Pathway in Lung Cancer

Lung cancer is the primary cause of cancer-related mortality worldwide and although improvements in treatment have been achieved over the last few years, long-term survival rates for lung cancer patients remain poor. Therefore, there is an imperative need for molecularly targeted agents that will achieve long-term disease control. Numerous downstream molecular pathways, such as EGF/RAS/RAF/MEK/ERK and PI3K/AKT/mTOR are identified as having a key role in the pathogenesis of various forms of human cancer, including lung cancer. PI3K/AKT/mTOR signal pathway is an important intracellular signal transduction pathway with a significant role in cell proliferation, growth, survival, vesicle trafficking, glucose transport, and cytoskeletal organization. Aberrations in many primary and secondary messenger molecules of this pathway, including mutations and amplifications, are accounted for tumor cell proliferation, inhibition of apoptosis, angiogenesis, metastasis and resistance to chemotherapy-radiotherapy. In this review article, we investigate thoroughly the biological role of PI3K pathway in lung cancer and its contribution in the development of future therapeutic strategies.

Drug development to overcome resistance to EGFR inhibitors in lung and colorectal cancer

Epidermal growth factor receptor (EGFR) is a validated target in different human malignancies. EGFR tyrosine kinase inhibitors (TKIs) are known to contribute considerably to the extension of progression-free survival in EGFR-mutant non-small cell lung cancer and monoclonal antibodies (mAbs) targeting EGFR have also improved the efficacy outcomes in KRAS wild-type colorectal cancer. Nevertheless, a significant percentage of lung and colorectal cancer patients do not respond to anti-EGFR agents and secondary resistance after initial benefit is a challenging reality faced by clinicians. Extensive preclinical work on the potential mechanisms of resistance to EGFR inhibitors in different disease settings has guided the development of second-generation irreversible EGFR TKIs, more efficient anti-EGFR mAbs, and combination strategies with agents targeting other receptors and downstream effectors. In order to elucidate the role of the multiple therapeutic strategies under investigation to overcome EGFR inhibitors-resistance, rational drug development based on stringent preclinical data, biomarker validation and proper selection of patients in the ongoing clinical trials are of paramount importance. Preliminary results of clinical trials evaluating these approaches will be discussed in this manuscript, with emphasis on TKIs in lung cancer and mAbs in advanced colorectal cancer.

Antitumor activity of NVP-BKM120--a selective pan class I PI3 kinase inhibitor showed differential forms of cell death based on p53 status of glioma cells

PURPOSE

The aim of this study was to show preclinical efficacy and clinical development potential of NVP-BKM120, a selective pan class I phosphatidylinositol-3 kinase (PI3K) inhibitor in human glioblastoma (GBM) cells in vitro and in vivo.

EXPERIMENTAL DESIGN

The effect of NVP-BKM120 on cellular growth was assessed by CellTiter-Blue assay. Flow cytometric analyses were carried out to measure the cell-cycle, apoptosis, and mitotic index. Mitotic catastrophe was detected by immunofluorescence. The efficacy of NVP-BKM120 was tested using intracranial U87 glioma model.

RESULTS

We tested the biologic effects of a selective PI3K inhibitor NVP-BKM120 in a set of glioma cell lines. NVP-BKM120 treatment for 72 hours resulted in a dose-dependent growth inhibition and effectively blocked the PI3K/Akt signaling cascade. Although we found no obvious relationship between the cell line's sensitivity to NVP-BKM120 and the phosphatase and tensin homolog (PTEN) and epidermal growth factor receptor (EGFR) statuses, we did observe a differential sensitivity pattern with respect to p53 status, with glioma cells containing wild-type p53 more sensitive than cells with mutated or deleted p53. NVP-BKM120 showed differential forms of cell death on the basis of p53 status of the cells with p53 wild-type cells undergoing apoptotic cell death and p53 mutant/deleted cells having a mitotic catastrophe cell death. NVP-BKM120 mediates mitotic catastrophe mainly through Aurora B kinase. Knockdown of p53 in p53 wild-type U87 glioma cells displayed microtubule misalignment, multiple centrosomes, and mitotic catastrophe cell death. Parallel to the assessment of the compound in in vitro settings, in vivo efficacy studies using an intracranial U87 tumor model showed an increased median survival from 26 days (control cohort) to 38 and 48 days (treated cohorts).

CONCLUSION

Our present findings establish that NVP-BKM120 inhibits the PI3K signaling pathways, leading to different forms of cell death on the basis of p53 statuses. Further studies are warranted to determine if NVP-BKM120 has potential as a glioma treatment.