(5-(2-4-bis((3s)-3-methylmorpholin-4-yl)pyrido(2-3-d)pyrimidin-7-yl)-2-methoxyphenyl)methanol and dactolisib

Triple-negative breast cancer (TNBC) shows a higher malignant and poorer clinical outcome compared with other breast cancer subtypes. Albeit that chemotherapy is the first choice for TNBC treatment, rapid emergence of chemoresistance and variability of chemotherapeutic responses in TNBC patients call for novel therapeutic strategies. Here, we reported evidences highlighting that combination of BH3 mimetics and mTOR inhibitors could be a promising therapeutic strategy to improve TNBC treatment. Our results showed that combination of the BH3 mimetic ABT263 and typical mTOR inhibitors, BEZ235 or AZD8055, leads to efficient apoptosis in vitro. Tumor regression was significantly improved by combination therapy compared with either drug alone in the xenograft model. Further mechanistic investigations revealed that mTOR inhibitors induced the suppression of MCL-1; concomitantly, the expression level of PUMA was significantly upregulated in a FOXO3a-dependent manner. The specific changes of MCL-1 and PUMA facilitated the release of the apoptotic regulators, such as BIM, BAX, and BAK, to induce the activation of mitochondrial apoptotic pathway, thereby sensitizing the ABT263 activity in TNBC. Therefore, our findings provided evidences that mTOR inhibitors can enhance antitumor efficacy of BH3 mimetics via downregulating MCL-1 and upregulating PUMA in TNBC; it could be a promising therapeutic strategy to treat TNBC.

Topics: Aniline Compounds; Animals; Antineoplastic Agents; Apoptosis; Apoptosis Regulatory Proteins; Cell Line, Tumor; Cell Proliferation; Down-Regulation; Drug Synergism; Female; Forkhead Box Protein O3; Humans; Imidazoles; Mice, Nude; Models, Biological; Morpholines; Myeloid Cell Leukemia Sequence 1 Protein; Protein Biosynthesis; Protein Kinase Inhibitors; Proto-Oncogene Proteins; Quinolines; Sulfonamides; TOR Serine-Threonine Kinases; Triple Negative Breast Neoplasms; Up-Regulation

Cancer therapies that simultaneously target activated mammalian target of rapamycin (mTOR) and cell metabolism are urgently needed. The goal of our study was to identify therapies that effectively inhibited both mTOR activity and cancer cell metabolism in primary tumors in vivo. Using our mouse model of spontaneous breast cancer promoted by loss of LKB1 expression in an ErbB2 activated model; referred to as LKB1-/-NIC mice, we evaluated the effect of novel therapies in vivo on primary tumors. Treatment of LKB1-/-NIC mice with AZD8055 and 2-DG mono-therapies significantly reduced mammary gland tumorigenesis by inhibiting mTOR pathways and glycolytic metabolism; however simultaneous inhibition of these pathways with AZD8055/2-DG combination was significantly more effective at reducing tumor volume and burden. At the molecular level, combination treatment inhibited mTORC1/mTORC2 activity, selectively inhibited mitochondria function and blocked MAPK pro-survival signaling responsible for the ERK-p90RSK feedback loop. Our findings suggest that loss of LKB1 expression be considered a marker for metabolic dysfunction given its role in regulating AMPK and mTOR function. Finally, the outcome of our pre-clinical study confirms therapies that simultaneously target mTORC1/mTORC2 and glycolytic metabolism in cancer produce the best therapeutic outcome for the treatment of patients harboring metabolically active HER2 positive breast cancers.

Topics: AMP-Activated Protein Kinases; Animals; Antineoplastic Combined Chemotherapy Protocols; Deoxyglucose; Disease Models, Animal; Female; Glycolysis; Imidazoles; Mammary Neoplasms, Experimental; Mice; Mice, Transgenic; Molecular Targeted Therapy; Morpholines; Protein Serine-Threonine Kinases; Quinolines; Signal Transduction; TOR Serine-Threonine Kinases

To evaluate first-generation rapamycin analogs (everolimus, temsirolimus, and rapamycin) and second-generation drugs inhibiting mTOR kinase (AZD-8055), PI3K (BKM-120) or both (BEZ-235 and GDC-0980) in hepatocellular carcinoma (HCC) and renal cell carcinoma (RCC) cells characterized for acquired resistance to sorafenib or sunitinib.. Anti-proliferative (MTT assay) and cell signaling (Western blot) effects of rapamycin analogs (1-20 μM) and second-generation drugs (0.03-20.0 μM) were assessed in human HCC SK-HEP1, RCC 786-0, and sorafenib- (SK-Sora) or sunitinib-resistant (786-Suni) cells.. In SK-HEP1 cells displaying high PTEN and Bcl2 expression, rapamycin analogs had poor anti-proliferative effects. However, SK-Sora cells were more sensitive to rapamycin analogs (≥1 μM) than SK-HEP1 cells. In 786-0 cells, lacking PTEN and Bcl2 expression, ≥1 μM rapamycin analogs blocked mTORC1 signaling, transiently activated Akt, and inhibited cell proliferation. Protracted sunitinib exposure in 786-Suni cells yielded an increase in p27 expression and a decreased sensitivity to rapamycin analogs, although mTORC1 function could be inhibited with rapamycin analogs. Second-generation drugs induced more potent growth inhibition than rapamycin analogs at concentrations >0.03 μM in parental cells, SK-Sora, and 786-Suni cells. Growth inhibitory concentrations of these new drugs also blocked mTORC1 downstream targets.. Rapamycin analogs inhibited mTORC1 downstream targets and yielded anti-proliferative effects in HCC and RCC cells. Second-generation drugs also appeared to be potent inhibitors of mTORC1 signaling; however, they appeared to be far more potent in inhibiting cellular proliferation in parental HCC and RCC cells and in cells developing resistance to sorafenib or sunitinib.

Topics: Aminopyridines; Antineoplastic Agents; Bridged Bicyclo Compounds, Heterocyclic; Carcinoma, Hepatocellular; Carcinoma, Renal Cell; Cell Line, Tumor; Cell Proliferation; Dose-Response Relationship, Drug; Drug Resistance, Neoplasm; Everolimus; Humans; Imidazoles; Indoles; Kidney Neoplasms; Liver Neoplasms; Mechanistic Target of Rapamycin Complex 1; Morpholines; Multiprotein Complexes; Niacinamide; Phenylurea Compounds; Phosphoinositide-3 Kinase Inhibitors; Pyrimidines; Pyrroles; Quinolines; Signal Transduction; Sirolimus; Sorafenib; Sunitinib; TOR Serine-Threonine Kinases

(V600E)B-RAF mutation is found in 50% to 60% of melanomas, and the novel agents PLX4032/vemurafenib and GSK2118436 that inhibit the (V600E)B-RAF kinase achieve a remarkable clinical response rate. However, as might be expected, acquired clinical resistance to these agents arises in most melanoma patients. PLX4032/vemurafenib resistance that arises in vivo in tumor matched short-term cultures or in vitro in melanoma cell lines is not caused by acquisition of secondary mutations in (V600E)B-RAF but rather is caused by upregulating platelet-derived growth factor receptor β (PDGFRβ) or N-RAS which results in resistance or sensitivity to mitogen-activated protein (MAP)/extracellular signal-regulated (ERK; MEK) kinase inhibitors, respectively. In this study, we define a targeted combinatorial strategy to overcome PLX4032/vemurafenib resistance in melanoma cell lines or short-term culture where the resistance is driven by PDGFRβ upregulation, achieving synergistic growth inhibition and cytotoxicity. PDGFRβ-upregulated, PLX4032-resistant (PPRM) cell lines show dual phospho (p)-ERK and p-AKT upregulation, and their growth inhibitory responses to specific small molecule inhibitors correlated with p-ERK, p-AKT, and p-p70S6K levels. Coordinate inhibition of (V600E)B-RAF inhibition and the RTK-PI3K-AKT-mTORC axis led to functionally significant rebound signaling, illustrating a robust and dynamic network connectivity. Combined B-RAF, phosphoinositide 3-kinase (PI3K), and mTORC1/2 inhibition suppressed both immediate early and delayed compensatory signaling, resulting in a highly synergistic growth inhibitory response but less efficient cytotoxic response. In contrast, the combination of MEK1/2, PI3K, and mTORC1/2 inhibitors consistently triggered apoptosis in a highly efficient manner. Together, our findings offer a rational strategy to guide clinical testing in preidentified subsets of patients who relapse during treatment with (V600E)B-RAF inhibitors.

Topics: Antineoplastic Agents; Apoptosis; Drug Resistance, Neoplasm; Drug Screening Assays, Antitumor; Drug Synergism; Humans; Imidazoles; Indoles; MAP Kinase Kinase Kinases; Mechanistic Target of Rapamycin Complex 1; Melanoma; Morpholines; Multiprotein Complexes; Neoplasm Proteins; Phosphatidylinositol 3-Kinases; Phosphoinositide-3 Kinase Inhibitors; Point Mutation; Proteins; Proto-Oncogene Proteins B-raf; Proto-Oncogene Proteins c-akt; Quinolines; Receptor, Platelet-Derived Growth Factor beta; Recombinant Fusion Proteins; Signal Transduction; Spheroids, Cellular; Sulfonamides; TOR Serine-Threonine Kinases; Transcription Factors; Vemurafenib