pd-0325901 and Adenocarcinoma-of-Lung

Mesenchymal-type cancers after epithelial mesenchymal transition (EMT) were recently shown to acquire chemoresistance through expressing EMT specific transcription factors. However, druggable (or actionable) target(s) for chemoresistance in mesenchymal-type lung cancers remain unidentified. Here, we used a public clinical genomic database and mesenchymal lung cancer cells (MLCC) model derived from the A549 lung adenocarcinoma cell line to demonstrate that BCL2 expression, which is highly induced in mesenchymal-type lung cancers, as a predictor of poor prognosis in mesenchymal lung cancer patients and association with acquired chemoradioresistance. Thereby, combination treatment with BH3 mimetics, such as ABT-263 and ABT-737, clearly attenuated chemoresistance in MLCCs. BCL2 expression in MLCCs was induced by ERK1 activity through the upregulation of the MEK1/ERK1 scaffold protein MEK partner-1 (MP1). Interfering with the MEK1/MP1/ERK1 axis using a MEK1 inhibitor or MP1 depletion repressed BCL2 expression and sensitized MLCCs to chemoradiotherapy. Taken together, our results suggest that targeting druggable proteins in the MEK1/MP1/ERK1/BCL2 axis, such as MEK1 or BCL2, with currently available FDA approved drugs is a currently feasible approach to improve clinical outcomes of mesenchymal lung cancer patients.

Topics: A549 Cells; Adaptor Proteins, Signal Transducing; Adenocarcinoma; Adenocarcinoma of Lung; Aniline Compounds; Antineoplastic Combined Chemotherapy Protocols; Benzamides; Biphenyl Compounds; Cell Proliferation; Cell Survival; Chemoradiotherapy; Diphenylamine; Dose-Response Relationship, Drug; Drug Resistance, Neoplasm; Etoposide; Gene Expression Regulation, Neoplastic; Humans; Lung Neoplasms; MAP Kinase Kinase 1; Mitogen-Activated Protein Kinase 3; Mitogen-Activated Protein Kinases; Molecular Mimicry; Nitrophenols; Peptide Fragments; Piperazines; Protein Kinase Inhibitors; Proto-Oncogene Proteins; Proto-Oncogene Proteins c-bcl-2; Radiation Tolerance; RNA Interference; Signal Transduction; Sulfonamides; Transfection; Up-Regulation

Genetically engineered mouse (GEM) models of lung tumorigenesis allow careful evaluation of lung tumor initiation, progression, and response to therapy. Using GEM models of oncogene-induced lung cancer, we show the striking similarity of the earliest stages of tumorigenesis induced by KRAS(G12D) or BRAF(V600E). Cre-mediated expression of KRAS(G12D) or BRAF(V600E) in the lung epithelium of adult mice initially elicited benign lung tumors comprising cuboidal epithelial cells expressing markers of alveolar pneumocytes. Strikingly, in a head-to-head comparison, oncogenic BRAF(V600E) elicited many more such benign tumors and did so more rapidly than KRAS(G12D). However, despite differences in the efficiency of benign tumor induction, only mice with lung epithelium expression of KRAS(G12D) developed malignant non-small cell lung adenocarcinomas. Pharmacologic inhibition of mitogen-activated protein (MAP)-extracellular signal-regulated kinase (ERK) kinase (MEK)1/2 combined with in vivo imaging showed that initiation and maintenance of both BRAF(V600E)- or KRAS(G12D)-induced lung tumors was dependent on MEK→ERK signaling. Although the tumors dramatically regressed in response to MEK1/2 inhibition, they regrew following cessation of drug treatment. Together, our findings show that RAF→MEK→ERK signaling is both necessary and sufficient for KRAS(G12D)-induced benign lung tumorigenesis in GEM models. The data also emphasize the ability of KRAS(G12D) to promote malignant lung cancer progression compared with oncogenic BRAF(V600E).

Topics: Adenocarcinoma; Adenocarcinoma of Lung; Animals; Antineoplastic Agents; Benzamides; Carcinoma, Non-Small-Cell Lung; Cell Proliferation; Diphenylamine; Disease Models, Animal; Extracellular Signal-Regulated MAP Kinases; Lung Neoplasms; MAP Kinase Kinase 1; MAP Kinase Kinase 2; MAP Kinase Signaling System; Mice; Mice, Transgenic; Proto-Oncogene Proteins B-raf; Proto-Oncogene Proteins p21(ras); Respiratory Mucosa; Tumor Cells, Cultured

The role of PI3K and MAPK pathways in tumor initiation and progression is well established; hence, several inhibitors of these pathways are currently in different stages of clinical trials. Recent studies identified a PI3K/mTOR (PF-04691502) and a MEK inhibitor (PD-0325901) with strong potency and efficacy in different cell lines and tumor models. PD-0325901, however, showed adverse effects when administered at or above MTD (maximum tolerated dose) in the clinic. Here, we show in preclinical models that PD-0325901 at doses well below MTD (sub-MTD 1.5 mg/kg SID) is still a potent compound as single agent or in combination with PF-04691502. We first observed that PD-0325901 at 1.5 mg/kg SID and in combination with PF-04691502 (7.5 mg/kg; SID) significantly inhibited growth of H460 (carry Kras and PIK3CA mutations) orthotopic lung tumors. Additionally, we tested efficacy of PD-0325901 in Kras(G12D-LSL) conditional GEMMs (genetically engineered mouse models) which are a valuable tool in translational research to study tumor progression. Intranasal delivery of adenoviruses expressing Cre recombinase (Adeno-Cre) resulted in expression of mutant Kras leading to development of tumor lesions in lungs including adenomatous hyperplasia, large adenoma, and adenocarcinoma. Similar to H460 tumors, PD-0325901 as single agent or in combination with PF-04691502 significantly inhibited growth of tumor lesions in lungs in Kras(G12D-LSL) mice when treatment started at adenocarcinoma stage (at 14 weeks post-Adeno-Cre inhalation). In addition, immunohistochemistry showed inhibition of pS6 (phosphorylated ribosomal S6) in the treated animals particularly in the combination group providing a proof of mechanism for tumor growth inhibition. Finally, m-CT imaging in live Kras(G12D-LSL) mice showed reduction of tumor burdens in PD-0325901-treated animals at sub-MTD dose. In conclusion, our data suggest that PD-0325901 at doses below MTD is still a potent compound capable of tumor growth inhibition where Kras and/or PI3K are drivers of tumor growth and progression.

Topics: Adenocarcinoma; Adenocarcinoma of Lung; Animals; Antineoplastic Combined Chemotherapy Protocols; Benzamides; Cell Line, Tumor; Diphenylamine; Dose-Response Relationship, Drug; Heterozygote; Humans; Lung Neoplasms; Maximum Tolerated Dose; Mice; Mice, Mutant Strains; Mitogen-Activated Protein Kinase Kinases; Neoplasm Transplantation; Phosphoinositide-3 Kinase Inhibitors; Proto-Oncogene Proteins p21(ras); Pyridones; Pyrimidines; TOR Serine-Threonine Kinases