scholarly journals mTOR-targeted cancer therapy: great target but disappointing clinical outcomes, why?

2020 ◽  
Author(s):  
Shi-Yong Sun
Keyword(s):  
Cancer Therapy ◽  
Kinase Inhibitors ◽  
Mammalian Target Of Rapamycin ◽  
Mtor Inhibitors ◽  
Targeted Cancer Therapy ◽  
Biological Functions ◽  
New Findings ◽  
Survival Signaling ◽  
Mtor Complex 1

Abstract The mammalian target of rapamycin (mTOR) critically regulates several essential biological functions, such as cell growth, metabolism, survival, and immune response by forming two important complexes, namely, mTOR complex 1 (mTORC1) and complex 2 (mTORC2). mTOR signaling is often dysregulated in cancers and has been considered an attractive cancer therapeutic target. Great efforts have been made to develop efficacious mTOR inhibitors, particularly mTOR kinase inhibitors, which suppress mTORC1 and mTORC2; however, major success has not been achieved. With the strong scientific rationale, the intriguing question is why cancers are insensitive or not responsive to mTOR-targeted cancer therapy in clinics. Beyond early findings on induced activation of PI3K/Akt, MEK/ERK, and Mnk/eIF4E survival signaling pathways that compromise the efficacy of rapalog-based cancer therapy, recent findings on the essential role of GSK3 in mediating cancer cell response to mTOR inhibitors and mTORC1 inhibition-induced upregulation of PD-L1 in cancer cells may provide some explanations. These new findings may also offer us the opportunity to rationally utilize mTOR inhibitors in cancer therapy. Further elucidation of the biology of complicated mTOR networks may bring us the hope to develop effective therapeutic strategies with mTOR inhibitors against cancer.

scholarly journals Dual mTORC1/mTORC2 inhibition as a Host-Directed Therapeutic Target in Pathologically Distinct Mouse Models of Tuberculosis

2021 ◽  
Author(s):  
Rokeya Tasneen ◽  
Deborah S. Mortensen ◽  
Paul J. Converse ◽  
Michael E. Urbanowski ◽  
Anna Upton ◽  
...  
Keyword(s):  
Kinase Inhibitors ◽  
Therapeutic Potential ◽  
Mammalian Target Of Rapamycin ◽  
Mtor Inhibitors ◽  
Kinase Domain ◽  
Lung Damage ◽  
Mtor Inhibition ◽  
Mtor Kinase ◽  
Tb Treatment ◽  
Mtor Complex 1

Efforts to develop more effective and shorter-course therapies for tuberculosis have included a focus on host-directed therapy (HDT). The goal of HDT is to modulate the host response to infection, thereby improving immune defenses to reduce the duration of antibacterial therapy and/or the amount of lung damage. As a mediator of innate and adaptive immune responses involved in eliminating intracellular pathogens, autophagy is a potential target for HDT in tuberculosis. Because Mycobacterium tuberculosis modulates mammalian target of rapamycin (mTOR) signaling to impede autophagy, pharmacologic mTOR inhibition could provide effective HDT. mTOR exists within two distinct multiprotein complexes, mTOR complex-1 (mTORC1) and mTOR complex-2 (mTORC2). Rapamycin and its analogs only partially inhibit mTORC1. We hypothesized that novel mTOR kinase inhibitors blocking both complexes would have expanded therapeutic potential. We compared the effects of two mTOR inhibitors: rapamycin and the orally available mTOR kinase domain inhibitor CC214-2, which blocks both mTORC1 and mTORC2, as adjunctive therapies against murine TB, when added to the first-line regimen (RHZE) or the novel bedaquiline-pretomanid-linezolid (BPaL) regimen. Neither mTOR inhibitor affected lung CFU counts after 4-8 weeks of treatment when combined with BPaL or RHZE. However, addition of CC214-2 to BPaL and RHZE was associated with significantly fewer relapses in C3HeB/FeJ compared to addition of rapamycin and, in RHZE-treated mice, resulted in fewer relapses compared to RHZE alone. Therefore, CC214-2 and related mTOR kinase inhibitors may be more effective candidates for HDT than rapamycin analogs and may have the potential to shorten the duration of TB treatment.

scholarly journals Dual mTORC1/mTORC2 inhibition as a Host-Directed Therapeutic Target in Pathologically Distinct Mouse Models of Tuberculosis

2021 ◽  
Author(s):  
Rokeya Tasneen ◽  
Deborah S. Mortensen ◽  
Paul J. Converse ◽  
Michael E. Urbanowski ◽  
Anna Upton ◽  
...  
Keyword(s):  
Kinase Inhibitors ◽  
Therapeutic Potential ◽  
Mammalian Target Of Rapamycin ◽  
Mtor Inhibitors ◽  
Kinase Domain ◽  
Lung Damage ◽  
Mtor Inhibition ◽  
Mtor Kinase ◽  
Tb Treatment ◽  
Mtor Complex 1

AbstractEfforts to develop more effective and shorter-course therapies for tuberculosis have included a focus on host-directed therapy (HDT). The goal of HDT is to modulate the host response to infection, thereby improving immune defenses to reduce the duration of antibacterial therapy and/or the amount of lung damage. As a mediator of innate and adaptive immune responses involved in eliminating intracellular pathogens, autophagy is a potential target for HDT in tuberculosis. Because Mycobacterium tuberculosis modulates mammalian target of rapamycin (mTOR) signaling to impede autophagy, pharmacologic mTOR inhibition could provide effective HDT. mTOR exists within two distinct multiprotein complexes, mTOR complex-1 (mTORC1) and mTOR complex-2 (mTORC2). Rapamycin and its analogs only partially inhibit mTORC1. We hypothesized that novel mTOR kinase inhibitors blocking both complexes would have expanded therapeutic potential. We compared the effects of two mTOR inhibitors: rapamycin and the orally available mTOR kinase domain inhibitor CC214-2, which blocks both mTORC1 and mTORC2, as adjunctive therapies against murine TB, when added to the first-line regimen (RHZE) or the novel bedaquiline-pretomanid-linezolid (BPaL) regimen. Neither mTOR inhibitor affected lung CFU counts after 4-8 weeks of treatment when combined with BPaL or RHZE. However, addition of CC214-2 to BPaL and RHZE was associated with significantly fewer relapses in C3HeB/FeJ compared to addition of rapamycin and, in RHZE-treated mice, resulted in fewer relapses compared to RHZE alone. Therefore, CC214-2 and related mTOR kinase inhibitors may be more effective candidates for HDT than rapamycin analogs and may have the potential to shorten the duration of TB treatment.

scholarly journals The Role of mTOR Signaling as a Therapeutic Target in Cancer

2021 ◽  
Vol 22 (4) ◽  
pp. 1743
Author(s):  
Nadezhda V. Popova ◽  
Manfred Jücker
Keyword(s):  
Mammalian Target Of Rapamycin ◽  
Mtor Inhibitors ◽  
Genetic Alterations ◽  
Mtor Pathway ◽  
Mtor Signaling ◽  
Cell Processes ◽  
And Function ◽  
Available Information ◽  
Mtor Complex 1

The aim of this review was to summarize current available information about the role of phosphatidylinositol-3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) signaling in cancer as a potential target for new therapy options. The mTOR and PI3K/AKT/mTORC1 (mTOR complex 1) signaling are critical for the regulation of many fundamental cell processes including protein synthesis, cell growth, metabolism, survival, catabolism, and autophagy, and deregulated mTOR signaling is implicated in cancer, metabolic dysregulation, and the aging process. In this review, we summarize the information about the structure and function of the mTOR pathway and discuss the mechanisms of its deregulation in human cancers including genetic alterations of PI3K/AKT/mTOR pathway components. We also present recent data regarding the PI3K/AKT/mTOR inhibitors in clinical studies and the treatment of cancer, as well the attendant problems of resistance and adverse effects.

Aurora Kinase Inhibitors in Head and Neck Cancer

2018 ◽  
Vol 18 (3) ◽  
pp. 199-213
Author(s):  
Guangying Qi ◽  
Jing Liu ◽  
Sisi Mi ◽  
Takaaki Tsunematsu ◽  
Shengjian Jin ◽  
...  
Keyword(s):  
Head And Neck Cancer ◽  
Cancer Therapy ◽  
Kinase Inhibitors ◽  
Biological Function ◽  
Aurora Kinase ◽  
Aurora Kinases ◽  
Related Research ◽  
Chemotherapy Drugs ◽  
Aurora Kinase Inhibitors

Aurora kinases are a group of serine/threonine kinases responsible for the regulation of mitosis. In recent years, with the increase in Aurora kinase-related research, the important role of Aurora kinases in tumorigenesis has been gradually recognized. Aurora kinases have been regarded as a new target for cancer therapy, resulting in the development of Aurora kinase inhibitors. The study and application of these small-molecule inhibitors, especially in combination with chemotherapy drugs, represent a new direction in cancer treatment. This paper reviews studies on Aurora kinases from recent years, including studies of their biological function, their relationship with tumor progression, and their inhibitors.

Role of PRAS40 in Akt and mTOR signaling in health and disease

2012 ◽  
Vol 302 (12) ◽  
pp. E1453-E1460 ◽  
Author(s):  
Claudia Wiza ◽  
Emmani B. M. Nascimento ◽  
D. Margriet Ouwens
Keyword(s):  
Mammalian Target Of Rapamycin ◽  
Mtor Signaling ◽  
Cellular Growth ◽  
S6 Kinase ◽  
Binding Partners ◽  
Health And Disease ◽  
Mtor Complex 1 ◽  
Mtor Activity

The proline-rich Akt substrate of 40 kDa (PRAS40) acts at the intersection of the Akt- and mammalian target of rapamycin (mTOR)-mediated signaling pathways. The protein kinase mTOR is the catalytic subunit of two distinct signaling complexes, mTOR complex 1 (mTORC1) and mTORC2, that link energy and nutrients to the regulation of cellular growth and energy metabolism. Activation of mTOR in response to nutrients and growth factors results in the phosphorylation of numerous substrates, including the phosphorylations of S6 kinase by mTORC1 and Akt by mTORC2. Alterations in Akt and mTOR activity have been linked to the progression of multiple diseases such as cancer and type 2 diabetes. Although PRAS40 was first reported as substrate for Akt, investigations toward mTOR-binding partners subsequently identified PRAS40 as both component and substrate of mTORC1. Phosphorylation of PRAS40 by Akt and by mTORC1 itself results in dissociation of PRAS40 from mTORC1 and may relieve an inhibitory constraint on mTORC1 activity. Adding to the complexity is that gene silencing studies indicate that PRAS40 is also necessary for the activity of the mTORC1 complex. This review summarizes the regulation and potential function(s) of PRAS40 in the complex Akt- and mTOR-signaling network in health and disease.

Pancreatic endocrine disorders and multiple endocrine neoplasia

2020 ◽  
pp. 2449-2463
Author(s):  
B. Khoo ◽  
T.M. Tan ◽  
S.R. Bloom
Keyword(s):  
Kinase Inhibitors ◽  
Neuroendocrine Tumours ◽  
Mammalian Target Of Rapamycin ◽  
Peptide Receptor Radionuclide Therapy ◽  
Mtor Inhibitors ◽  
Somatostatin Analogues ◽  
Endocrine Disorders ◽  
Pancreatic Neuroendocrine Tumours ◽  
Islet Cell Tumours ◽  
Cancer Syndromes

Pancreatic neuroendocrine tumours (islet-cell tumours) are rare and usually sporadic, but they may be associated with complex familial endocrine cancer syndromes. Recognized types of pancreatic neuroendocrine tumours are those that are non-functioning (often advanced at diagnosis and presenting with mass effects due to the absence of symptoms attributable to hormone hypersecretion), insulinoma (the most frequent type), and others including gastrinoma, VIPoma, and glucagonoma. The following should be considered in addition to the symptomatic treatments: surgical resection—the only curative treatment, but not possible in many cases; tyrosine kinase inhibitors which inhibit specific kinases involved in tumour cell proliferation, growth, and angiogenesis; mammalian Target of Rapamycin (mTOR) inhibitors; peptide-receptor radionuclide therapy (radiolabelled somatostatin analogues).

New Frontiers in Mucositis

2012 ◽  
pp. 545-551 ◽  
Author(s):  
Douglas E. Peterson ◽  
Dorothy M. Keefe ◽  
Stephen T. Sonis
Keyword(s):  
Kinase Inhibitors ◽  
Management Strategies ◽  
Mammalian Target Of Rapamycin ◽  
Cancer Therapeutics ◽  
Mtor Inhibitors ◽  
Mucosal Injury ◽  
Mucosal Damage ◽  
Nucleotide Polymorphisms ◽  
Oncology Patient ◽  
Novel Technologies

Overview: Mucositis is among the most debilitating side effects of radiotherapy, chemotherapy, and targeted anticancer therapy. Research continues to escalate regarding key issues such as etiopathology, incidence and severity across different mucosae, relationships between mucosal and nonmucosal toxicities, and risk factors. This approach is being translated into enhanced management strategies. Recent technology advances provide an important foundation for this continuum. For example, evolution of applied genomics is fostering development of new algorithms to rapidly screen genomewide single-nucleotide polymorphisms (SNPs) for patient-associated risk prediction. This modeling will permit individual tailoring of the most effective, least toxic treatment in the future. The evolution of novel cancer therapeutics is changing the mucositis toxicity profile. These agents can be associated with unique mechanisms of mucosal damage. Additional research is needed to optimally manage toxicity caused by agents such as mammalian target of rapamycin (mTOR) inhibitors and tyrosine kinase inhibitors, without reducing antitumor effect. There has similarly been heightened attention across the health professions regarding clinical practice guidelines for mucositis management in the years following the first published guidelines in 2004. New opportunities exist to more effectively interface this collective guideline portfolio by capitalizing upon novel technologies such as an Internet-based Wiki platform. Substantive progress thus continues across many domains associated with mucosal injury in oncology patients. In addition to enhancing oncology patient care, these advances are being integrated into high-impact educational and scientific venues including the National Cancer Institute Physician Data Query (PDQ) portfolio as well as a new Gordon Research Conference on mucosal health and disease scheduled for June 2013.

scholarly journals The Role of mTOR Inhibitors in Liver Transplantation: Reviewing the Evidence

2014 ◽  
Vol 2014 ◽  
pp. 1-45 ◽  
Author(s):  
Goran B. Klintmalm ◽  
Björn Nashan
Keyword(s):  
Metabolic Syndrome ◽  
Liver Transplantation ◽  
Renal Function ◽  
De Novo ◽  
Immunosuppressive Agents ◽  
Mammalian Target Of Rapamycin ◽  
Calcineurin Inhibitors ◽  
Mtor Inhibitors

Despite the success of liver transplantation, long-term complications remain, includingde novomalignancies, metabolic syndrome, and the recurrence of hepatitis C virus (HCV) and hepatocellular carcinoma (HCC). The current mainstay of treatment, calcineurin inhibitors (CNIs), can also worsen posttransplant renal dysfunction, neurotoxicity, and diabetes. Clearly there is a need for better immunosuppressive agents that maintain similar rates of efficacy and renal function whilst minimizing adverse effects. The mammalian target of rapamycin (mTOR) inhibitors with a mechanism of action that is different from other immunosuppressive agents has the potential to address some of these issues. In this review we surveyed the literature for reports of the use of mTOR inhibitors in adult liver transplantation with respect to renal function, efficacy, safety, neurological symptoms,de novotumors, and the recurrence of HCC and HCV. The results of our review indicate that mTOR inhibitors are associated with efficacy comparable to CNIs while having benefits on renal function in liver transplantation. We also consider newer dosing schedules that may limit side effects. Finally, we discuss evidence that mTOR inhibitors may have benefits in the oncology setting and in relation to HCV-related allograft fibrosis, metabolic syndrome, and neurotoxicity.

The role of mTOR inhibitors in targeting a putative cancer stem cell-like population in esophageal cancer.

2016 ◽  
Vol 34 (4_suppl) ◽  
pp. 43-43
Author(s):  
Da Wang ◽  
Roland Chiu ◽  
John Theodorus Plukker ◽  
Robert P. Coppes
Keyword(s):  
Esophageal Cancer ◽  
Cell Lines ◽  
Mammalian Target Of Rapamycin ◽  
Neoadjuvant Chemoradiotherapy ◽  
Mtor Inhibitors ◽  
Mtor Pathway ◽  
Tumor Biopsy ◽  
Sphere Formation ◽  
Dose Dependent

43 Background: Despite modern advances in the treatment of esophageal cancer (EC), using neoadjuvant chemoradiotherapy (CRT) and esophagectomy, most patients face poor outcome. Growing evidence indicates that cancer stem cells (CSCs) might contribute to the poor prospects. CSCs are usually resistant to CRT and ultimately can generate a new tumor. The mammalian target of rapamycin (mTOR) pathway is associated with cancer stemness. However, its role in EC CSC-like populations needs to be elucidated. Here, we investigate the role of mTOR pathway on the stemness of a putative CSC-like population. Methods: Previously, we identified a putative CSC-like population (CD44+/CD24-) in EC cell lines and in tumor biopsy from EC patients. qPCR was used to measure the expression of mTOR in CD44+/CD24- CSC-like population of OE21 squamous cell carcinoma and OE33 adenocarcinoma cell lines compared to controls, that consisted of solid tumors generated from the same cell lines obtained from xenografts. mTOR inhibitors rapamycin and torin-1 were used to see their effect on CD44+/CD24- expression and sphere formation. Results: mTOR expression was 2-fold up-regulated in the OE33 CD44+/CD24- CSC-like population compared to control. Furthermore, in OE21 this up-regulation was 1.9-fold. Surprisingly, inhibiting the mTOR pathway with rapamycin enhanced OE33 CD44+/CD24- expression compared to its control (p = 0.01). In pilot experiments this effect was dose dependent and cells treated with rapamycin formed more spheres than control. Rapamycin did not alter the expression of CD44+/CD24- in OE21. Inhibiting the mTOR pathway with Torin-1 enhanced OE21 CD44+/CD24- expression by 1.2-fold compared to control (N = 2). In another pilot experiment Torin-1 treated cells were able to form more spheres compared to control. Torin-1 did not have an effect on the expression of CD44+/CD24- in OE33. Conclusions: These findings indicate that inhibiting the mTOR pathway may enhance CSC-like properties in EC. Additional research needs to be done to further support this hypothesis and elucidate the mechanism in this process. Furthermore, the effect of mTOR pathway inducers in EC needs to be explored.

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