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

The mechanistic target of rapamycin complex 2 (mTORC2) is a potentially novel and promising anticancer target due to its critical roles in proliferation, apoptosis, and metabolic reprogramming of cancer cells. However, the activity and function of mTORC2 in distinct cells within malignant tissue in vivo is insufficiently explored. Surprisingly, in primary human and mouse colorectal cancer (CRC) samples, mTORC2 signaling could not be detected in tumor cells. In contrast, only macrophages in tumor-adjacent areas showed mTORC2 activity, which was downregulated in stromal macrophages residing within human and mouse tumor tissues. Functionally, inhibition of mTORC2 by specific deletion of Rictor in macrophages stimulated tumorigenesis in a colitis-associated CRC mouse model. This phenotype was driven by a proinflammatory reprogramming of mTORC2-deficient macrophages that promoted colitis via the cytokine SPP1/osteopontin to stimulate tumor growth. In human CRC patients, high SPP1 levels and low mTORC2 activity in tumor-associated macrophages correlated with a worsened clinical prognosis. Treatment of mice with a second-generation mTOR inhibitor that inhibits mTORC2 and mTORC1 exacerbated experimental colorectal tumorigenesis in vivo. In conclusion, mTORC2 activity is confined to macrophages in CRC and limits tumorigenesis. These results suggest activation but not inhibition of mTORC2 as a therapeutic strategy for colitis-associated CRC.

Topics: Animals; Carcinogenesis; Cell Line, Tumor; Cell Proliferation; Cells, Cultured; Colitis, Ulcerative; Colon; Colorectal Neoplasms; Dextran Sulfate; Disease Models, Animal; Female; Humans; Intestinal Mucosa; Kaplan-Meier Estimate; Macrophages; Male; Mechanistic Target of Rapamycin Complex 2; Mice; Mice, Transgenic; Morpholines; Osteopontin; Primary Cell Culture; Prognosis; Survival Rate

BACKGROUND Although 5-Flourouracil(5-FU) is used as the first-choice treatment for advanced hepatocellular carcinoma (HCC), it is associated with acquired and intrinsic resistance. Hyperactivation of mTOR signaling has been linked to tumorigenesis and chemoresistance in HCC. The aim of this study was to evaluate and compare the antitumor effects of mTORC1 inhibitor everolimus and mTORC1/2 inhibitor AZD8055 and to examine the interaction between 5-FU and mTORC1/2 inhibitor in HCC. MATERIAL AND METHODS Using cultured HCC cells and mouse xenograft, the antitumor effects of everolimus and AZD8055 were analyzed as mono- and combination therapy with 5-Flourouracil. RESULTS TSC2-deficient HCC cell lines were more sensitive to everolimus and AZD8055. AZD8055, but not everolimus, potently prevented cells from transitioning from G1 phase to S phase in TSC2-high-expressing HCC cells. AZD8055 reduced phosphorylation of both mTORC1 and mTORC2 substrates. In contrast, everolimus reduced the phosphorylation of mTORC1 substrates, but increased the phosphorylation of AKT. Notably, AZD8055, but not everolimus, synergistically enhanced the efficacy of 5-FU via reversing 5-FU-induced upregulation of P-glycoprotein (P-gp). The synergistic antitumor effect of AZD8055 and 5-FU was also observed in a HCC xenograft mouse model. CONCLUSIONS TSC2 in HCC is a promising efficacy-predicting biomarker for the treatment of mTORC1/2 inhibitor. AZD8055 showed stronger antitumor activity than everolimus in TSC2-high-expressing HCC cells. Moreover, the combination of mTORC1/2 inhibitor with 5-FU appears to be a promising option for HCC patients refractory to chemotherapy.

Topics: Animals; ATP Binding Cassette Transporter, Subfamily B, Member 1; Carcinogenesis; Carcinoma, Hepatocellular; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Proliferation; Drug Synergism; Everolimus; Fluorouracil; G1 Phase; Humans; Liver Neoplasms; Male; Mechanistic Target of Rapamycin Complex 1; Mechanistic Target of Rapamycin Complex 2; Mice, Inbred BALB C; Mice, Nude; Molecular Targeted Therapy; Morpholines; Treatment Outcome; Tuberous Sclerosis Complex 2 Protein; Tumor Suppressor Proteins; Up-Regulation; Xenograft Model Antitumor Assays

Autophagy is a vital process that involves degradation of long-lived proteins and dysfunctional organelles and contributes to cellular metabolism. Glioma-initiating cells (GICs) have the ability to self-renew, differentiate into heterogeneous types of tumor cells, and sustain tumorigenicity; thus, GICs lead to tumor recurrence. Accumulating evidence indicates that autophagy can induce stem cell differentiation and increase the lethality of temozolomide against GICs. However, the mechanism underlying the regulation of GIC self-renewal by autophagy remains uncharacterized. In the present study, autophagy induced by AZD8055 and rapamycin treatment suppressed GIC self-renewal in vitro. We found that autophagy inhibited Notch1 pathway activation. Moreover, autophagy activated Notch1 degradation, which is associated with maintenance of the self-renewal ability of GICs. Furthermore, autophagy abolished the tumorigenicity of CD133 + U87-MG neurosphere cells in an intracranial model. These findings suggest that autophagy regulating GICs self-renewal and tumorigenicity is probably bound up with Notch1 degradation. The results of this study could aid in the design of autophagy-based clinical trials for glioma treatments, which may be of great value.

Topics: Animals; Antineoplastic Agents; Autophagy; Brain Neoplasms; Calcium-Binding Proteins; Carcinogenesis; Cell Differentiation; Cell Line, Tumor; Cell Proliferation; Female; Gene Expression Regulation, Neoplastic; Glioblastoma; Humans; Membrane Proteins; Mice; Mice, Nude; Morpholines; Neoplastic Stem Cells; Proteolysis; Receptor, Notch1; Signal Transduction; Sirolimus; Sodium-Potassium-Exchanging ATPase; Spheroids, Cellular; Survival Analysis; Xenograft Model Antitumor Assays