Targeting tumorigenesis: development and use of mTOR inhibitors in cancer therapy

Integrated multi-omics analysis and machine learning developed a prognostic model based on mitochondrial function in a large multicenter cohort for Gastric Cancer

BACKGROUND

Gastric cancer (GC) is a common and aggressive type of cancer worldwide. Despite recent advancements in its treatment, the prognosis for patients with GC remains poor. Understanding the mechanisms of cell death in GC, particularly those related to mitochondrial function, is crucial for its development and progression. However, more research is needed to investigate the significance of the interaction between mitochondrial function and GC cell death.

METHODS

We employed a robust computational framework to investigate the role of mitochondria-associated proteins in the progression of GC in a cohort of 1,199 GC patients. Ten machine learning algorithms were utilized and combined into 101 unique combinations. Ultimately, we developed a Mitochondrial-related-Score (MitoScore) using the machine learning model that exhibited the best performance. We observed the upregulation of LEMT2 and further explored its function in tumor progression. Mitochondrial functions were assessed by measuring mitochondrial ATP, mitochondrial membrane potential, and levels of lactate, pyruvate, and glucose.

RESULTS

MitoScore showed significant correlations with GC immune and metabolic functions. The higher MitoScore subgroup exhibited enriched metabolic pathways and higher immune activity. Overexpression of LETM2 (leucine zipper and EF-hand containing transmembrane protein 2) significantly enhanced tumor proliferation and metastasis. LETM2 plays a role in promoting GC cell proliferation by activating the mTOR pathway, maintaining mitochondrial homeostasis, and promoting glycolysis.

CONCLUSION

The powerful machine learning framework highlights the significant potential of MitoScore in providing valuable insights and accurate assessments for individuals with GC. This study also enhances our understanding of LETM2 as an oncogene signature in GC. LETM2 may promote tumor progression by maintaining mitochondrial health and activating glycolysis, offering potential targets for diagnosis, treatment, and prognosis of GC.

Narrative review: precision medicine applications in neuroblastoma-current status and future prospects

Background and Objective

Neuroblastoma (NB) is a common malignant tumor in children, and its treatment remains challenging. Precision medicine, as an individualized treatment strategy, aims to improve efficacy and reduce toxicity by combining unique patient- and tumor-related factors, bringing new hope for NB treatment. In this article, we review the evidence related to precision medicine in NB, with a focus on potential clinically actionable targets and a series of targeted drugs associated with NB.

Methods

We conducted an extensive search in PubMed, EMBASE, and Web of Science using key terms and database-specific strategies, filtered for time and language, to ensure a comprehensive collection of literature related to precision medicine in NB. The main search terms consisted of "neuroblastoma", "precision medicine", "pediatrics", and "targeting". The articles included in this study encompass those published from 1985 to the present, without restrictions on the type of articles.

Key Content and Findings

ALK inhibitors and MYCN inhibitors have been developed to interfere with tumor cell growth and dissemination, thereby improving treatment outcomes. Additionally, systematic testing to identify relevant driver mutations is crucial and can be used for diagnosis and prognostic assessment through the detection of many associated molecular markers. Furthermore, liquid biopsy, a non-invasive tumor detection method, can complement tissue biopsy and play a role in NB by analyzing circulating tumor DNA and circulating tumor cells to provide genetic information and molecular characteristics of the tumor. Recently, trials conducted by many pediatric oncology groups have shown the urgent need for new approaches to cure relapsed and refractory patients.

Conclusions

The purpose of this review is to summarize the latest advances in clinical treatment of NB, to better understand and focus on the development of promising treatment approaches, and to expedite the transition to the precision medicine clinical relevance in NB patients.

MetaLnc9 facilitates osteogenesis of human bone marrow mesenchymal stem cells by activating the AKT pathway

AIM OF THE STUDY

To investigate the role of MetaLnc9 in the osteogenesis of human bone marrow mesenchymal stem cells (hBMSCs).

MATERIALS AND METHODS

We used lentiviruses to knockdown or overexpress MetaLnc9 in hBMSCs. qRT-PCR was employed to determine the mRNA levels of osteogenic-related genes in transfected cells. ALP staining and activity assay, ARS staining and quantification were used to identify the degree of osteogenic differentiation. Ectopic bone formation was conducted to examine the osteogenesis of transfected cells in vivo. AKT pathway activator SC-79 and inhibitor LY294002 were used to validate the relationship between MetaLnc9 and AKT signaling pathway.

RESULTS

The expression of MetaLnc9 was significantly upregulated in the osteogenic differentiation of hBMSCs. MetaLnc9 knockdown inhibited the osteogenesis of hBMSCs, whereas overexpression of it promoted the osteogenic differentiation both in vitro and in vivo. Taking a deeper insight, we found that MetaLnc9 enhanced the osteogenic differentiation by activating AKT signaling. The inhibitor of AKT signaling LY294002 could reverse the positive effect on osteogenesis brought by MetaLnc9 overexpression, whereas the activator of AKT signaling SC-79 could reverse the negative effect caused by MetaLnc9 knockdown.

CONCLUSION

Our works uncovered a vital role of MetaLnc9 in osteogenesis via regulating the AKT signaling pathway. [Figure: see text].

Rapamycin and rapalogs for tuberous sclerosis complex

BACKGROUND

Potential benefits of rapamycin or rapalogs for treating people with tuberous sclerosis complex (TSC) have been shown. Currently everolimus (a rapalog) is only approved for TSC-associated renal angiomyolipoma and subependymal giant cell astrocytoma (SEGA), but not other manifestations of TSC. A systematic review needs to establish evidence for rapamycin or rapalogs for various manifestations in TSC. This is an updated review.

OBJECTIVES

To determine the effectiveness of rapamycin or rapalogs in people with TSC for decreasing tumour size and other manifestations and to assess the safety of rapamycin or rapalogs in relation to their adverse effects.

SEARCH METHODS

We identified relevant studies from the Cochrane-Central-Register-of-Controlled-Trials (CENTRAL), Ovid MEDLINE and ongoing trials registries with no language restrictions. We searched conference proceedings and abstract books of conferences. Date of the last searches: 15 July 2022.

SELECTION CRITERIA

Randomised controlled trials (RCTs) or quasi-RCTs of rapamycin or rapalogs in people with TSC.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the risk of bias of each study; a third review author verified the extracted data and risk of bias decisions. We assessed the certainty of the evidence using GRADE.

MAIN RESULTS

The current update added seven RCTs, bringing the total number to 10 RCTs (with 1008 participants aged 3 months to 65 years; 484 males). All TSC diagnoses were by consensus criteria as a minimum. In parallel studies, 645 participants received active interventions and 340 placebo. Evidence is low-to-high certainty and study quality is mixed; mostly a low risk of bias across domains, but one study had a high risk of performance bias (lack of blinding) and three studies had a high risk of attrition bias. Manufacturers of the investigational products supported eight studies. Systemic administration Six studies (703 participants) administered everolimus (rapalog) orally. More participants in the intervention arm reduced renal angiomyolipoma size by 50% (risk ratio (RR) 24.69, 95% confidence interval (CI) 3.51 to 173.41; P = 0.001; 2 studies, 162 participants, high-certainty evidence). In the intervention arm, more participants in the intervention arm reduced SEGA tumour size by 50% (RR 27.85, 95% CI 1.74 to 444.82; P = 0.02; 1 study; 117 participants; moderate-certainty evidence) ,and reported more skin responses (RR 5.78, 95% CI 2.30 to 14.52; P = 0.0002; 2 studies; 224 participants; high-certainty evidence). In one 18-week study (366 participants), the intervention led to 25% fewer seizures (RR 1.63, 95% CI 1.27 to 2.09; P = 0.0001) or 50% fewer seizures (RR 2.28, 95% CI 1.44 to 3.60; P = 0.0004); but there was no difference in numbers being seizure-free (RR 5.30, 95% CI 0.69 to 40.57; P = 0.11) (moderate-certainty evidence). One study (42 participants) showed no difference in neurocognitive, neuropsychiatry, behavioural, sensory and motor development (low-certainty evidence). Total adverse events (AEs) did not differ between groups (RR 1.09, 95% CI 0.97 to 1.22; P = 0.16; 5 studies; 680 participants; high-certainty evidence). However, the intervention group experienced more AEs resulting in withdrawal, interruption of treatment, or reduced dose (RR 2.61, 95% CI 1.58 to 4.33; P = 0.0002; 4 studies; 633 participants; high-certainty evidence and also reported more severe AEs (RR 2.35, 95% CI 0.99 to 5.58; P = 0.05; 2 studies; 413 participants; high-certainty evidence). Topical (skin) administration Four studies (305 participants) administered rapamycin topically. More participants in the intervention arm showed a response to skin lesions (RR 2.72, 95% CI 1.76 to 4.18; P < 0.00001; 2 studies; 187 participants; high-certainty evidence) and more participants in the placebo arm reported a deterioration of skin lesions (RR 0.27, 95% CI 0.15 to 0.49; 1 study; 164 participants; high-certainty evidence). More participants in the intervention arm responded to facial angiofibroma at one to three months (RR 28.74, 95% CI 1.78 to 463.19; P = 0.02) and three to six months (RR 39.39, 95% CI 2.48 to 626.00; P = 0.009; low-certainty evidence). Similar results were noted for cephalic plaques at one to three months (RR 10.93, 95% CI 0.64 to 186.08; P = 0.10) and three to six months (RR 7.38, 95% CI 1.01 to 53.83; P = 0.05; low-certainty evidence). More participants on placebo showed a deterioration of skin lesions (RR 0.27, 95% CI 0.15 to 0.49; P < 0.0001; 1 study; 164 participants; moderate-certainty evidence). The intervention arm reported a higher general improvement score (MD -1.01, 95% CI -1.68 to -0.34; P < 0.0001), but no difference specifically in the adult subgroup (MD -0.75, 95% CI -1.58 to 0.08; P = 0.08; 1 study; 36 participants; moderate-certainty evidence). Participants in the intervention arm reported higher satisfaction than with placebo (MD -0.92, 95% CI -1.79 to -0.05; P = 0.04; 1 study; 36 participants; low-certainty evidence), although again with no difference among adults (MD -0.25, 95% CI -1.52 to 1.02; P = 0.70; 1 study; 18 participants; low-certainty evidence). Groups did not differ in change in quality of life at six months (MD 0.30, 95% CI -1.01 to 1.61; P = 0.65; 1 study; 62 participants; low-certainty evidence). Treatment led to a higher risk of any AE compared to placebo (RR 1.72, 95% CI 1.10, 2.67; P = 0.02; 3 studies; 277 participants; moderate-certainty evidence); but no difference between groups in severe AEs (RR 0.78, 95% CI 0.19 to 3.15; P = 0.73; 1 study; 179 participants; moderate-certainty evidence).

AUTHORS' CONCLUSIONS

Oral everolimus reduces the size of SEGA and renal angiomyolipoma by 50%, reduces seizure frequency by 25% and 50% and implements beneficial effects on skin lesions with no difference in the total number of AEs compared to placebo; however, more participants in the treatment group required a dose reduction, interruption or withdrawal and marginally more experienced serious AEs compared to placebo. Topical rapamycin increases the response to skin lesions and facial angiofibroma, an improvement score, satisfaction and the risk of any AE, but not severe adverse events. With caution regarding the risk of severe AEs, this review supports oral everolimus for renal angiomyolipoma, SEGA, seizure, and skin lesions, and topical rapamycin for facial angiofibroma.

Fibrolamellar hepatocellular carcinoma: A rare but unpleasant event

Fibrolamellar carcinoma (FLC) is a rare variant of hepatocellular carcinoma (HCC), comprising 1%–9% of all HCCs. FLC is a poorly understood malignancy, which seems to be more prevalent in young patients with no underlying liver diseases. The term “fibrolamellar” is derived from thick fibrous collagen bands surrounding the tumor cells. Unlike HCC, cirrhosis and viral hepatitis infection are not predisposing to FLC, and it is not associated with elevations in serum alpha-fetoprotein. FLC patients often present with vague abdominal pain, nausea, malaise, and weight loss. Most cases present are at an advanced stage at the time of initial diagnosis. However, curative treatment options can still be offered to up to 70% of patients. Surgery (resection/liver transplantation) is the mainstay of treatment and the only potentially curative option. FLCs have been less chemo-responsive than the conventional HCC, however, in advanced cases, multimodality treatments can be effective. Recent advances in molecular studies of FLC have found a unique DNAJB1–PRKACA fusion transcript in most of the cases studied. The review aims to describe clinical characteristics, diagnostic methods, and therapeutic modalities for this rare tumor to raise awareness among clinicians and surgeons.

Application of mTORC1 Inhibitors for Tissue-Agnostic Management of Standard-Therapy-Refractory Solid Tumors

In this analysis, we examined the efficacy, feasibility, and limitations of the application of mTOR inhibitors based on the individual molecular profiles of pretreated cancer patients after the failure of all standard treatments in the palliative setting. In this single-center, real-world analysis of our platform for precision medicine, we analyzed the molecular characteristics of 71 cancer patients. The tumor samples of the patients were analyzed using next-generation sequencing panels of mutation hotspots, microsatellite stability testing, and immunohistochemistry. All profiles were reviewed by a multidisciplinary team to provide a targeted treatment recommendation after a consensus discussion. Seventy-one cancer patients with activation of the mTOR pathway were offered an mTORC1-inhibitor-based targeted therapy, and twenty-three (32.4%) of them eventually received the targeted therapy. Only three patients (4.2%) achieved stable disease, of whom one experienced progressive disease again after 9.1 months. The median time to treatment failure was 2.8 months. In total, 110 mutations were detected in 60 patients (84.5%). The three most frequent mutations were found in TP53, PTEN, and KRAS, which accounted for over 50% (56.4%) of all mutations. In sum, in selected patients with heavily pretreated solid tumors with activation of the mTOR pathway, the antitumoral activity of mTORC1 inhibition was weak.

Recycling of SLC38A1 to the plasma membrane by DSCR3 promotes acquired temozolomide resistance in glioblastoma

PURPOSE

Glioblastoma multiforme (GBM) is a primary brain tumor with devastating prognosis. Although the O⁶-methylguanine-DNA methyltransferase (MGMT) leads to inherent temozolomide (TMZ) resistance, approximately half of GBMs were sufficient to confer acquired TMZ resistance, which express low levels of MGMT. The purpose of this study was to investigate the underlying mechanisms of the acquired TMZ resistance in MGMT-deficient GBM.

METHODS

The function of Down syndrome critical region protein 3 (DSCR3) on MGMT-deficient GBM was investigated in vitro and in an orthotopic brain tumor model in mice. Purification of plasma membrane proteins by membrane-cytoplasmic separation and subsequent label free-based quantitative proteomics were used to identified potential protein partners for DSCR3. Immunofluorescence was performed to show the reverse transport of solute carrier family 38 member 1 (SLC38A1) mediated by DSCR3.

RESULTS

DSCR3 is upregulated in MGMT-deficient GBM cells during TMZ treatment. Both DSCR3 and SLC38A1 were highly expressed in recurrent GBM patients. Silencing DSCR3 or SLC38A1 expression can increase TMZ sensitivity in MGMT-deficient GBM cells. Combination of proteomics and in vitro experiments show that DSCR3 directly binds internalized SLC38A1 to mediate its sorting into recycling pathway, which maintains the abundance on plasma membrane and enhances uptake of glutamine in MGMT-deficient GBM cells.

CONCLUSIONS

DSCR3 is a crucial regulator of acquired TMZ resistance in MGMT-deficient GBM. The DSCR3-dependent recycling of SLC38A1 maintains its abundance on plasma membrane, leading to tumor progression and acquired TMZ resistance in MGMT-deficient GBM.

Development and Validation of an LC-MS/MS Method for AC1LPSZG and Pharmacokinetics Application in Rats

Promising preliminary clinical data have stimulated research on the use of the mammalian target of rapamycin (mTOR) inhibitors in lung cancer. AC1LPSZG is an mTOR inhibitor that can significantly reduce the viability in lung adenosquamous carcinoma cell line HTB-178 cells, showing potential benefits in effective control of non-small cell lung carcinomas. In this study, a sensitive LC-MS/MS analytical method for quantification of AC1LPSZG has been developed and optimized to a running time of 3 min per sample. A linear dose-response for quantification was observed over the range of 10-5000 ng/mL in rat plasma with required precision and accuracy. High extraction recovery was achieved in the ranges of 86.87-102.51% at QC levels from rat plasma without significant matrix effect. Stability profile of AC1LPSZG in rat plasma and in extract after protein precipitation suggested that samples should be processed within 6 h after collection and stored at -80 °C until analysis within 30 days. The method was successfully applied to plasma pharmacokinetics (PK) study of AC1LPSZG in rat, showing the plasma drug concentration followed a two-compartment model.

Molecular Mechanisms and Cellular Contribution from Lung Fibrosis to Lung Cancer Development

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, fibrosing interstitial lung disease (ILD) of unknown aetiology, with a median survival of 2–4 years from the time of diagnosis. Although IPF has unknown aetiology by definition, there have been identified several risks factors increasing the probability of the onset and progression of the disease in IPF patients such as cigarette smoking and environmental risk factors associated with domestic and occupational exposure. Among them, cigarette smoking together with concomitant emphysema might predispose IPF patients to lung cancer (LC), mostly to non-small cell lung cancer (NSCLC), increasing the risk of lung cancer development. To this purpose, IPF and LC share several cellular and molecular processes driving the progression of both pathologies such as fibroblast transition proliferation and activation, endoplasmic reticulum stress, oxidative stress, and many genetic and epigenetic markers that predispose IPF patients to LC development. Nintedanib, a tyrosine–kinase inhibitor, was firstly developed as an anticancer drug and then recognized as an anti-fibrotic agent based on the common target molecular pathway. In this review our aim is to describe the updated studies on common cellular and molecular mechanisms between IPF and lung cancer, knowledge of which might help to find novel therapeutic targets for this disease combination.

Genetics in Epilepsy

The presence of unprovoked, recurrent seizures, particularly when drug resistant and associated with cognitive and behavioral deficits, warrants investigation for an underlying genetic cause. This article provides an overview of the major classes of genes associated with epilepsy phenotypes divided into functional categories along with the recommended work-up and therapeutic considerations. Gene discovery in epilepsy supports counseling and anticipatory guidance but also opens the door for precision medicine guiding therapy with a focus on those with disease-modifying effects.

Relationship between metabolic toxicity and efficacy of everolimus in patients with neuroendocrine tumors: A pooled analysis from the randomized, phase 3 RADIANT-3 and RADIANT-4 trials

BACKGROUND

Hyperglycemia and hypercholesterolemia are class effects of mammalian target of rapamycin inhibitors such as everolimus. This post hoc pooled analysis assessed the potential impact of these events on the efficacy of everolimus.

METHODS

Patients with advanced, low- or intermediate-grade pancreatic, gastrointestinal, or lung neuroendocrine tumors received either oral everolimus at 10 mg/d or a placebo in the RAD001 in Advanced Neuroendocrine Tumors 3 (RADIANT-3) and RAD001 in Advanced Neuroendocrine Tumors 4 (RADIANT-4) trials. A landmark progression-free survival (PFS) analysis by central review was performed for patients treated for at least 16 weeks (n = 308) and according to the occurrence of any-grade adverse events (AEs) within this treatment period.

RESULTS

The overall PFS with everolimus from the pooled analysis was 11.4 months (95% confidence interval, 11.01-13.93 months), which was consistent with the findings of RADIANT-3 and RADIANT-4. Overall, 19.1% and 9.8% of patients in RADIANT-3 and 11.9% and 6.4% of patients in RADIANT-4 developed any-grade hyperglycemia and hypercholesterolemia, respectively (regardless of the study drug). The duration of everolimus exposure was longer in patients who developed these AEs versus patients without these AEs. Overall, 308 patients were exposed to treatment for at least 16 weeks (hyperglycemia, 39 of 269 patients; hypercholesterolemia, 20 of 288 patients). No association was observed between the development of these AEs and PFS (18.8 and 14.1 months with and without hyperglycemia, respectively, and 14.1 and 14.8 months with and without hypercholesterolemia, respectively).

CONCLUSIONS

Although limitations apply because of the small number of AEs observed, there was no significant impact of these AEs on PFS; this suggests similar efficacy in the presence or absence of these events.

Therapeutic strategies of different HPV status in Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) is the 9^th most common malignant tumor in the world. Based on the etiology, HNSCC has two main subtypes: human papillomavirus (HPV) -related and HPV-unrelated. HPV-positive HNSCC is more sensitive to treatment with favorable survival. Due to the different biological behaviors, individual therapy is necessary and urgently required to deduce the therapeutic intensity of HPV-positive disease and look for a more effective and toxicity-acceptable regimen for HPV-negative disease. EGFR amplification and PI3K/AKT/mTOR pathway aberrant activation are quite common in HPV-positive HNSCC. Besides, HPV infection alters immune cell infiltrating in HNSCC and encompasses a diverse and heterogeneous landscape with more immune infiltration. On the other hand, the chance of HPV-negative cancers harboring mutation on the P53 gene is significantly higher than that of HPV-positive disease. This review focuses on the updated preclinical and clinical data of HPV-positive and HPV-negative HNSCC and discusses the therapeutic strategies of different HPV status in HNSCC.

Neonatal Autoimmune Lymphoproliferative Syndrome: A Case Report and A Brief Review

The authors are reporting a case of autoimmune lymphoproliferative syndrome in a newborn who presented with massive hepatosplenomegaly, thrombocytopenia, and anemia at birth. Antenatal ultrasound revealed a fetus with hepatosplenomegaly. The infant was treated with steroids and sirolimus and is doing well at 4 years of age. This is the first case report of autoimmune lymphoproliferative syndrome presenting as hepatosplenomegaly during fetal life.

SPR965, a Dual PI3K/mTOR Inhibitor, as a Targeted Therapy in Ovarian Cancer

SPR965 is an inhibitor of PI3K and mTOR C1/C2 and has demonstrated anti-tumorigenic activity in a variety of solid tumors. We sought to determine the effects of SPR965 on cell proliferation and tumor growth in human serous ovarian cancer cell lines and a transgenic mouse model of high grade serous ovarian cancer (KpB model) and identify the underlying mechanisms by which SPR965 inhibits cell and tumor growth. SPR965 showed marked anti-proliferative activity by causing cell cycle arrest and inducing cellular stress in ovarian cancer cells. Treatment with SPR965 significantly inhibited tumor growth in KpB mice, accompanied by downregulation of Ki67 and VEGF and upregulation of Bip expression in ovarian tumors. SPR965 also inhibited adhesion and invasion through induction of the epithelial–mesenchymal transition process. As expected, downregulation of phosphorylation of AKT and S6 was observed in SPR965-treated ovarian cancer cells and tumors. Our results suggest that SPR965 has significant anti-tumorigenic effects in serous ovarian cancer in vitro and in vivo. Thus, SPR965 should be evaluated as a promising targeted agent in future clinical trials of ovarian cancer.

Rapamycin inhibits lung squamous cell carcinoma growth by downregulating glypican-3/Wnt/β-catenin signaling and autophagy

PURPOSE

There is not much progress in the treatment for lung squamous cell carcinoma LSCC in the past few years. Rapamycin Rapa, an inhibitor of mammalian target of rapamycin mTOR, has exhibited antitumor efficacy in a variety of malignant tumors. It has recently been reported that Rapamycin can induce autophagy signaling pathway in lung cancer and Glypican-3GPC3 can promote the growth of hepatocellular carcinoma by stimulating canonical Wnt signaling pathway. The aim of this study is to investigate the mechanisms of rapamycin's antitumor efficacy in relation to GPC3/Wnt/β-catenin pathway and autophagy in LSCC.

METHODS

SK-MES-1 cells, a LSCC cell line, were treated with various concentrations of rapamycin with or without Glypican-3 GPC3-targeting siRNA. SK-MES-1 cell proliferation was determined by MTT assay. Protein expression levels of GPC3, β-catenin, Beclin-1 were checked via western blotting. We established the xenograft mice model to investigate the suppression effect of rapamycin on LSCC. In addition, we further testified the metabolism protein of autophagy process using the xenograft tumor tissue.

RESULTS

Rapamycin could inhibit the SK-MES-1 cell proliferation in a concentration-dependent manner both in vitro and in vivo by decreasing the GPC3 expression and downregulating the glypican-3/Wnt/β-catenin signaling pathway. In addition, we found that GPC3 silencing can activate the glypican-3/Wnt/β-catenin pathway and autophagy, which contribute to the suppression of tumor growth both in vitro and in vivo.

CONCLUSION

Rapamycin suppresses the growth of lung cancer through down-regulating glypican-3/Wnt/β-catenin signaling, which mediates with activation of autophagy. This study suggests GPC3 is a new promising target for rapamycin in the treatment of lung cancer.

Osteonecrosis of the jaws associated with protein kinase inhibitors: a systematic review

This systematic review analysed evidence relating to medication-related osteonecrosis of the jaws (MRONJ) associated with protein kinase inhibitors in antiresorptive naïve patients. A literature search of major biomedical databases was conducted in March 2020. Information extracted from relevant articles included bibliographic information, patient characteristics, MRONJ characteristics at diagnosis, management strategies and outcomes. Sixteen studies, representing data from 17 patients, were included for final analysis. Descriptive statistics were used to synthesis available data. Eleven protein kinase inhibitors were implicated, with a mean exposure of 13 months prior to MRONJ. Renal cell carcinoma was the primary diagnosis in 41.2% of patients. Patient symptoms, clinical features, radiographic findings and histological findings were consistent with those previously described in patients with MRONJ associated with antiresorptive medications. Overall, there was a 75% rate of cure, with a mean healing time of 17.2 weeks. Patients were treated surgically in 53.3% of the cases. Patients treated surgically achieved complete healing in 100% of cases, compared with 58% in those treated conservatively. Drug discontinuation was reported in 69.2% of patients. Patients who had the offending drug discontinued achieved complete healing in 75% of cases, compared with 50% in those who did not. Evidence relating to MRONJ associated with protein kinase inhibitors is of low quality. From the available data, there are notable differences relating to patient characteristics, treatment strategies and outcomes, between MRONJ associated with protein kinase inhibitors compared with antiresorptives. Higher quality evidence is required to support the findings of this review.

MEK inhibition overcomes everolimus resistance in gastric cancer

BACKGROUND

Although substantial evidence has shown that the mammalian target of rapamycin (mTOR) pathway is an important therapeutic target in gastric cancer, the overall response rates in patients to mTOR inhibitor everolimus have been less than initially expected. We hypothesized that the limited efficacy of everolimus in gastric cancer is due to the activation of extracellular signal-regulated kinase (ERK).

METHODS

ERK activation was investigated using western blot. The effects of dual inhibition of ERK and mTOR via genetic and pharmacological approaches were determined using cellular assays and xenograft mouse model.

RESULTS

We observed the decreased phosphorylation of mTOR, rS6, and 4EBP1 and increased phosphorylation of ERK and p90RSK in gastric cancer cells exposed to everolimus at clinically relevant concentration. Using both in vitro cell culture assays and in vivo xenograft mouse model, we found that trametinib overcame everolimus resistance by either effectively targeting resistant cells or further enhancing everolimus' efficacy in sensitive cells. Mechanism studies confirmed that trametinib overcame everolimus resistance via specifically inhibiting ERK and regulating ERK-mediated Bcl-2 family proteins in gastric cancer cells.

CONCLUSIONS

Inhibition of mTOR pathway can induce "paradoxical" activation of ERK in gastric cancer, and this activation can be reversed by trametinib. Since both drugs are clinically available, our findings might accelerate the initiation of clinical trials on gastric cancer using everolimus and trametinib combination.

Overcoming the Blood-Brain Barrier: Successes and Challenges in Developing Nanoparticle-Mediated Drug Delivery Systems for the Treatment of Brain Tumours

High-grade gliomas are still characterized by a poor prognosis, despite recent advances in surgical treatment. Chemotherapy is currently practiced after surgery, but its efficacy is limited by aspecific toxicity on healthy cells, tumour cell chemoresistance, poor selectivity, and especially by the blood–brain barrier (BBB). Thus, despite the large number of potential drug candidates, the choice of effective chemotherapeutics is still limited to few compounds. Malignant gliomas are characterized by high infiltration and neovascularization, and leaky BBB (the so-called blood–brain tumour barrier); surgical resection is often incomplete, leaving residual cells that are able to migrate and proliferate. Nanocarriers can favour delivery of chemotherapeutics to brain tumours owing to different strategies, including chemical stabilization of the drug in the bloodstream; passive targeting (because of the leaky vascularization at the tumour site); inhibition of drug efflux mechanisms in endothelial and cancer cells; and active targeting by exploiting carriers and receptors overexpressed at the blood–brain tumour barrier. Within this concern, a suitable nanomedicine-based therapy for gliomas should not be limited to cytotoxic agents, but also target the most important pathogenetic mechanisms, including cell differentiation pathways and angiogenesis. Moreover, the combinatorial approach of cell therapy plus nanomedicine strategies can open new therapeutical opportunities. The major part of attempted preclinical approaches on animal models involves active targeting with protein ligands, but, despite encouraging results, a few number of nanomedicines reached clinical trials, and most of them include drug-loaded nanocarriers free of targeting ligands, also because of safety and scalability concerns.

A Phase I Study of Safety, Pharmacokinetics, and Pharmacodynamics of Concurrent Everolimus and Buparlisib Treatment in Advanced Solid Tumors

PURPOSE

Concurrent inhibition of mTOR and PI3K led to improved efficacy in preclinical models and provided the rationale for this phase I study of everolimus and buparlisib (BKM120) in patients with advanced solid tumor.

PATIENTS AND METHODS

We used the Bayesian Escalation with Overdose Control design to test escalating doses of everolimus (5 or 10 mg) and buparlisib (20, 40, 60, 80, and 100 mg) in eligible patients. Pharmacokinetic assessment was conducted using blood samples collected on cycle 1, days 8 and 15. Pharmacodynamic impact on mTOR/PI3K pathway modulation evaluated in paired skin biopsies collected at baseline and end of cycle 1.

RESULTS

We enrolled 43 patients, median age of 63 (range, 39-78) years; 25 (58.1%) females, 35 (81.4%) Caucasians, and 8 (18.6%) Blacks. The most frequent toxicities were hyperglycemia, diarrhea, nausea, fatigue, and aspartate aminotransferase elevation. Dose-limiting toxicities observed in 7 patients were fatigue (3), hyperglycemia (2), mucositis (1), acute kidney injury (1), and urinary tract infection (1). The recommended phase II dose (RP2D) for the combination was established as everolimus (5 mg) and buparlisib (60 mg). The best response in 27 evaluable patients was progressive disease and stable disease in 3 (11%) and 24 (89%), respectively. The median progression-free survival and overall survival were 2.7 (1.8-4.2) and 9 (6.4-13.2) months. Steady-state pharmacokinetic analysis showed dose-normalized maximum concentrations and AUC values for everolimus and buparlisib in combination to be comparable with single-agent pharmacokinetic.

CONCLUSIONS

The combination of everolimus and buparlisib is safe and well-tolerated at the RP2D of 5 and 60 mg on a continuous daily schedule.

mTOR Pathway in Gastroenteropancreatic Neuroendocrine Tumor (GEP-NETs)

Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) originate from neuroendocrine cells in the gastrointestinal tract. They are heterogeneous, and though initially considered rare tumors, the incidence of GEP-NENs has increased in the last few decades. Therapeutic approaches for the metastatic disease include surgery, radiological intervention by chemoembolisation, radiofrequency ablation, biological therapy in addition to somatostatin analogs, and PRRT therapy (177Lu-DOTATATE). The PI3K-AKT-mTOR pathway is essential in the regulation of protein translation, cell growth, and metabolism. Evidence suggests that the mTOR pathway is involved in malignant progression and resistance to treatment through over-activation of several mechanisms. PI3K, one of the main downstream of the Akt-mTOR axis, is mainly involved in the neoplastic process. This pathway is frequently deregulated in human tumors, making it a central target in the development of new anti-cancer treatments. Recent molecular studies identify potential targets within the PI3K/Akt/mTOR pathway in GEP-NENs. However, the use of target therapy has been known to lead to resistance due to several mechanisms such as feedback activation of alternative pathways, inactivation of protein kinases, and deregulation of the downstream mTOR components. Therefore, the specific role of targeted drugs for the management of GEP-NENs is yet to be well-defined. The variable clinical presentation of advanced neuroendocrine tumors is a significant challenge for designing studies. This review aims to highlight the role of the PI3K/Akt/mTOR pathway in the development of neuroendocrine tumors and further specify its potential as a therapeutic target in advanced stages.

Everolimus Inhibits the Progression of Ductal Carcinoma In Situ to Invasive Breast Cancer Via Downregulation of MMP9 Expression

PURPOSE

We evaluated the role of everolimus in the prevention of ductal carcinoma in situ (DCIS) to invasive ductal carcinoma (IDC) progression.

EXPERIMENTAL DESIGN

The effects of everolimus on breast cancer cell invasion, DCIS formation, and DCIS progression to IDC were investigated in a 3D cell culturing model, intraductal DCIS xenograft model, and spontaneous MMTV-Her2/neu mouse model. The effect of everolimus on matrix metalloproteinase 9 (MMP9) expression was determined with Western blotting and IHC in these models and in patients with DCIS before and after a window trial with rapamycin. Whether MMP9 mediates the inhibition of DCIS progression to IDC by everolimus was investigated with knockdown or overexpression of MMP9 in breast cancer cells.

RESULTS

Everolimus significantly inhibited the invasion of human breast cancer cells in vitro. Daily intragastric treatment with everolimus for 7 days significantly reduced the number of invasive lesions from intraductal DCIS foci and inhibited DCIS progression to IDC in the MMTV-Her2/neu mouse mammary tumor model. Mechanistically, everolimus treatment decreased the expression of MMP9 in the in vitro and in vivo models, and in breast tissues from patients with DCIS treated with rapamycin for 1 week. Moreover, overexpression of MMP9 stimulated the invasion, whereas knockdown of MMP9 inhibited the invasion of breast cancer cell-formed spheroids in vitro and DCIS in vivo. Knockdown of MMP9 also nullified the invasion inhibition by everolimus in vitro and in vivo.

CONCLUSIONS

Targeting mTORC1 can inhibit DCIS progression to IDC via MMP9 and may be a potential strategy for DCIS or early-stage IDC therapy.

Stomatitis And Everolimus: A Review Of Current Literature On 8,201 Patients

Background

Oral toxicities, such as mucositis and stomatitis, are some of the most significant and unavoidable side effects associated with anticancer therapies. In past decades, research has focused on newer targeted agents with the aim of decreasing the rates of side effects on healthy cells. Unfortunately, even targeted anticancer therapies show significant rates of toxicity on healthy tissue. mTOR inhibitors display some adverse events, such as hyperglycemia, hyperlipidemia, hypophosphatemia, hematologic toxicities, and mucocutaneous eruption, but the most important are still stomatitis and skin rash, which are often dose-limiting side effects.

Aim

This review was performed to answer the question “What is the incidence of stomatitis in patients treated with everolimus?”

Methods

We conducted a systematic search on the PubMed and Medline online databases using a combination of MESH terms and free text: “everolimus” (MESH) AND “side effects” OR “toxicities” OR “adverse events”. Only studies fulfilling the following inclusion criteria were considered eligible for inclusion in this study: performed on human subjects, reporting on the use of everolimus (even if in combination with other drugs or ionizing radiation), written in the English language, and reporting the incidence of side effects.

Results

The analysis of literature revealed that the overall incidence of stomatitis after treatment with everolimus was 42.6% (3,493) and that of stomatitis grade G1/2 84.02% (2,935), while G3/4 was 15.97% (558).

Conclusion

Results of the analysis showed that the incidence of stomatitis of grade 1 or 2 is higher than grade 3 or 4. However, it must be taken into account that it is not possible to say if side effects are entirely due to everolimus therapy or combinations with other drugs.

Therapies targeting the signal pathways of pheochromocytoma and paraganglioma

Pheochromocytoma and paraganglioma (PCC/PGL) are rare tumors that originate from adrenal or extra-adrenal chromaffin cells. A significant clinical manifestation of PCC/PGL is that the tumors release a large number of catecholamines continuously or intermittently, causing persistent or paroxysmal hypertension and multiple organ functions and metabolic disorders. Though majority of the tumors are non-metastatic, about 10% are metastatic tumors. Others even have estimated that the rate of metastasis may be as high as 26%. The disease is most common in individuals ranging from 20 to 50 years old and the age of onset strongly depends on the genetic background: patients with germline mutations in susceptible genes have an earlier presentation. Besides, there are no significant differences in the incidence between men and women. At present, traditional treatments, such as surgical treatment, radionuclide therapy, and chemotherapy are still prior choices. However, they all have several deficiencies so that the effects are not extremely significant. Contemporary studies have shown that hypoxia-associated signal pathway, associated with the cluster 1 genes of PCC/PGL, and increased kinase signal pathways, associated with the cluster 2 genes of PCC/PGL, are the two major pathways involving the molecular pathogenesis of PCC/PGL, indicating that PCC/PGL can be treated with targeted therapies in emerging trends. This article reviews the progress of molecular-targeted therapies for PCC/PGL.

Chemistry Routes for Copolymer Synthesis Containing PEG for Targeting, Imaging, and Drug Delivery Purposes

Polyethylene glycol (PEG) is one of the most frequently used polymers for coating nanocarriers to enhance their biocompatibility, hydrophilicity, stability, and biodegradability. PEG is now considered to be among the best biocompatible polymers. It offers sterical hindrance against other nanoparticles and blood components such as opsonin, preventing their macrophage phagocytosis and resulting in a prolonged circulation time in blood stream, consequently a ‘stealth character’ in vivo. Therefore, PEG has a very promising future for the development of current therapeutics and biomedical applications. Moreover, the vast number of molecules that PEG can conjugate with might enhance its ability to have an optimistic perspective for the future. This review will present an update on the chemistry used in the modern conjugation methods for a variety of PEG conjugates, such methods include, but are not limited to, the synthesis of targeting PEG conjugates (i.e., Peptides, Folate, Biotin, Mannose etc.), imaging PEG conjugates (i.e., Coumarin, Near Infrared dyes etc.) and delivery PEG conjugates (i.e., doxorubicin, paclitaxel, and other hydrophobic low molecular weight drugs). Furthermore, the type of nanoparticles carrying those conjugates, along with their biomedical uses, will be briefly discussed.

PI3K-PKB-mTOR hyperactivation in relation to nasopharyngeal carcinoma progression and prognosis

Nasopharyngeal carcinoma (NPC) has a unique and complex etiology, which is not completely understood. The aim of this study is to investigate the expression patterns of phosphatidylinositol 3-kinase (PI3K), protein kinase B (PKB), and mammalian target of rapamycin (mTOR) proteins in patients with NPC and their relationship with NPC progression and prognosis. Between January 2008 and March 2010, PI3K, PKB, and mTOR protein expressions were detected using immunohistochemistry among 119 patients with NPC and 30 healthy people. A 5-year follow-up was conducted for all patients. Correlations of PI3K, PKB, and mTOR proteins with the clinicopathological features and prognosis of NPC were evaluated using Spearman's rank correlation coefficient and Kaplan-Meier curve. Cox's regression analysis was performed to analyze the risk factors for the prognosis of NPC. First, PI3K, PKB, and mTOR were highly expressed in patients with NPC. The expressions of PI3K, PKB, and mTOR proteins were associated with T stage, N stage, clinical stage, relapse, and distant metastasis. Meanwhile, PI3K is positively correlated with PKB and PKB is positively correlated with mTOR in NPC. Higher PI3K, PKB, and mTOR protein expressions were related to a shorter survival time and a lower survival rate in NPC. Cox regression analysis revealed that age, T stage, N stage, PI3K, PKB, and mTOR were independent risk factors for NPC patient survival. Altogether, our data suggest that overexpression of PI3K, PKB, and mTOR proteins is an important indicator of poor survival in NPC. In addition, inhibition of PI3K-PKB-mTOR signaling may also contribute to the development of new therapeutic strategies for NPC.

Whole-genome sequencing of esophageal adenocarcinoma in Chinese patients reveals distinct mutational signatures and genomic alterations

While the incidence of esophageal adenocarcinoma (EAC) has risen drastically in Western countries over the last 40 years, a similar trend has not been observed for EAC in China. Here, we analyzed mutational spectrum, copy number alterations, and structural variants from whole-genome sequencing of 10 Chinese EAC tumor samples and their matched normal samples, and compared them to previously reported EAC tumor specimens from Western countries. The mutational burden in Chinese EAC was significantly lower than that found in EAC from Western countries. The hallmark A>C mutational signature observed at high frequency in EAC from Western countries, which has been linked to acid reflux, is completely absent in Chinese samples. Furthermore, none of the Chinese samples showed evidence of chromothripsis and genome doubling that are often found in EAC from Western countries. In summary, Chinese EAC tumor samples had distinct genomic profiles and signatures, suggesting that EAC in Chinese individuals may arise from a different etiological pathway.

The combination of everolimus and terameprocol exerts synergistic antiproliferative effects in endometrial cancer: molecular role of insulin-like growth factor binding protein 2

Oncogenic PIK3CA mutations are common in endometrial cancers, and the PI3K/AKT/mTOR pathway is targetable by drugs. We sought to investigate whether the combination of an mTOR inhibitor, everolimus (RAD001), and an AKT inhibitor, terameprocol (M4N), exerts better antiproliferative effects in endometrial cancer. The molecular mechanisms underlying their pharmacological action were also examined. The combination of RAD001 and M4N exerted in vitro synergistic effects on cell viability, apoptosis, and expression of IGFBP2 in endometrial cancer cells. Mechanistically, the Sp1 site on the IGFBP2 promoter was required for RAD001- and M4N-induced downregulation. IGFBP2 protein expression was higher in endometrial cancer than in the normal endometrium (P < 0.001). Furthermore, elevated IGFBP2 histoscores were significantly associated with a lower overall survival (P = 0.021). In conclusion, our in vitro results demonstrate that RAD001 and M4N exert synergistic antiproliferative effects against endometrial cancer cells, which appeared to be mediated by the inhibition of IGFBP2, a key anti-apoptotic regulator. Further clinical studies of this drug combination in patients with endometrial cancer may be warranted, especially in the presence of PIK3CA and IGFBP2 aberrations. KEY MESSAGES: RAD001 and M4N synergistically suppress endometrial cancer growth. IGFBP2 is overexpressed in endometrial cancer. The combination of RAD001 and M4N significantly reduces IGFBP2 overexpression. Sp1 binding site on the IGFBP2 promoter is required for RAD001- and M4N-induced downregulation. High IGFBP2 histoscore in endometrial cancer portends a poor prognosis.

Rapamycin Combi with TAE on the Growth, Metastasis, and Prognosis of Hepatocellular Carcinoma in Rat Models

INTRODUCTION AND AIM

To investigate the effect of mTOR inhibitor Rapamycin combined with transcatheter arterial embolization (TAE) on the growth, metastasis, and prognosis of hepatocellular carcinoma (HCC) in rat model.

MATERIAL AND METHOD

McARH7777 cells were used to construct rat models of HCC, which were randomly divided into Model, Rapamycin, TAE, and Rapamycin + TAE groups. Quantitative reverse transcription-PCR (qRT-PCR) and Western Blot were used to detect the expression of Epithelial-Mesenchymal Transition (EMT)-related molecules, and immunohistochemical staining to determine the expression of EMTrelated proteins, angiogenic factors as well as microvessel density (MVD)-CD34.

RESULTS

The hepatic tumor volume of rats in the other three groups were all significantly smaller than the Model group on the 7th, 14th, and 21st day after treatment and the combination treatment was apparently more effective than either treatment alone. Besides, both the number and the size of metastatic nodules of HCC rats after combination treatment were remarkably reduced. In addition, compared with rats in the Rapamycin + TAE group, N-cadherin, Vimentin, HIF-1α, VEGF, and MVD-CD34 were obviously enhanced, while E-cadherin was lowered in those TAE group, which were the complete opposite to the Rapamycin group. Besides, the median survival time of rats in the Rapamycin + TAE group was evidently longer than the resting groups.

CONCLUSION

Rapamycin combined with TAE may effectively suppress the EMT formation and angiogenesis, thereby inhibiting the growth and lung metastasis of HCC rats, which provides a new idea for countering the recurrence and metastasis of HCC.

Unintended Consequences of Systemic and Ablative Oncologic Therapy in the Abdomen and Pelvis

Human cancers are genetically complex and diverse. Although advances in oncologic therapy aim to define and target unique steps in carcinogenesis, oncologists often rely on less discriminate anticancer therapies that have consequences for normal tissues. Even many of the so-called targeted therapies currently employed can adversely affect normal cells, leading to complications that necessitate dose reductions or cessation of specific therapies. This article explores the unintended consequences of currently employed systemic and ablative anticancer therapies that might manifest at imaging examinations of the abdomen and pelvis, including cytotoxic, molecular targeted, and immunologic agents; ablation; and hematopoietic stem cell transplant. Each of these treatments can have both major and minor unintended effects in the targeted organ(s), in local or adjacent structures, or at distant sites. Timely detection and reporting of adverse consequences of anticancer therapies by the astute imager can result in critical treatment modifications and/or lifesaving interventions; therefore, knowledge of these unintended effects is paramount for radiologists interpreting the results of imaging examinations in cancer patients. ^©RSNA, 2018.

Osteonecrosis of the Jaw Associated with Antiangiogenics in Antiresorptive-Naïve Patient: A Comprehensive Review of the Literature

Objectives

To review the available literature on medication-related osteonecrosis of the jaw (MRONJ) associated with antiangiogenics in antiresorptive-naïve individuals.

Methods

A literature search was performed using MEDLINE via PubMed, EMBASE, and Web of Science in December 2017.

Results

We identified reports describing a total of 35 antiresorptive drugs-naïve patients who developed antiangiogenic-related MRONJ. The mean age of these patients was 59.06 years and the F : M ratio was 4 : 5. The most common underlying disease was metastatic renal cell cancer. Pain to the mandible was the most common complaint (34.29%) and the majority of patients presented with bone exposure. The mean duration of intravenous and oral antiangiogenics before MRONJ development was 6.5 and 16.72 months, respectively. The most common additional risk factor was dental extraction (37.14%). Almost half of the MRONJ patients (48.57%) received surgical treatment. 18 patients (62.06%) were reported to have disease resolution within an average time of 6.75 months.

Conclusion

MRONJ associated with antiangiogenic therapy in antiresorptive-naïve patients is a rare but potentially serious adverse effect. Available data suggests that there might be notable differences between MRONJ associated with antiangiogenics and antiresorptives; however, further prospective well-designed studies are required.

Everolimus rescues multiple cellular defects in laminopathy-patient fibroblasts

LMNA encodes the A-type lamins that are part of the nuclear scaffold. Mutations in LMNA can cause a variety of disorders called laminopathies, including Hutchinson-Gilford progeria syndrome (HGPS), atypical Werner syndrome, and Emery-Dreifuss muscular dystrophy. Previous work has shown that treatment of HGPS cells with the mTOR inhibitor rapamycin or with the rapamycin analog everolimus corrects several of the phenotypes seen at the cellular level-at least in part by increasing autophagy and reducing the amount of progerin, the toxic form of lamin A that is overproduced in HGPS patients. Since other laminopathies also result in production of abnormal and potentially toxic lamin proteins, we hypothesized that everolimus would also be beneficial in those disorders. To test this, we applied everolimus to fibroblast cell lines from six laminopathy patients, each with a different mutation in LMNA Everolimus treatment increased proliferative ability and delayed senescence in all cell lines. In several cell lines, we observed that with treatment, there is a significant improvement in nuclear blebbing, which is a cellular hallmark of HGPS and other lamin disorders. These preclinical results suggest that everolimus might have clinical benefit for multiple laminopathy syndromes.

Current and Emerging Therapeutic Targets for Metastatic Renal Cell Carcinoma

PURPOSE OF REVIEW

The treatment of advanced renal cell carcinoma has evolved dramatically over recent years. In this review, we will summarize current and emerging therapies based on molecular targets and provide insight into treatment strategy for metastatic renal cell carcinoma.

RECENT FINDINGS

We have witnessed a paradigm shift in the therapeutic landscape as treatment was formerly reliant on cytokine-based agents which have now been replaced with therapies targeting angiogenesis, mammalian target of rapamycin pathways, and immune responses. These dramatic changes are primarily due to our improved understanding of the underlying mutations and molecular mechanisms leading to tumorigenesis and progression. We now have targeted agents in the form of small-molecule tyrosine kinase inhibitors, monoclonal antibodies, and mTOR inhibitors. Moreover, immunotherapy-targeting checkpoints of T-lymphocyte activity has provided increased overall survival and a new class of agents with potential to radically change the treatment options. With these agents and their combination, durable responses are increasingly seen even though treatment resistance remains a huge challenge. New treatment strategies are rapidly developing and the therapeutic landscape is expected for further evolution.

The therapeutic potential of targeting the PI3K pathway in pediatric brain tumors

Central nervous system tumors are the most common cancer type in children and the leading cause of cancer related deaths. There is therefore a need to develop novel treatments. Large scale profiling studies have begun to identify alterations that could be targeted therapeutically, including the phosphoinositide 3-kinase (PI3K) signaling pathway, which is one of the most commonly activated pathways in cancer with many inhibitors under clinical development. PI3K signaling has been shown to be aberrantly activated in many pediatric CNS neoplasms. Pre-clinical analysis supports a role for PI3K signaling in the control of tumor growth, survival and migration as well as enhancing the cytotoxic effects of current treatments. Based on this evidence agents targeting PI3K signaling have begun to be tested in clinical trials of pediatric cancer patients. Overall, targeting the PI3K pathway presents as a promising strategy for the treatment of pediatric CNS tumors. In this review we examine the genetic alterations found in the PI3K pathway in pediatric CNS tumors and the pathological role it plays, as well as summarizing the current pre-clinical and clinical data supporting the use of PI3K pathway inhibitors for the treatment of these tumors.

DEPTOR suppresses the progression of esophageal squamous cell carcinoma and predicts poor prognosis

As a naturally occurring inhibitor of mTOR, accumulated evidence has suggested that DEPTOR plays a pivotal role in suppressing the progression of human malignances. However, the function of DEPTOR in the development of esophageal squamous cell carcinoma (ESCC) is still unclear. Here we report that the expression of DEPTOR is significantly reduced in tumor tissues derived from human patients with ESCC, and the downregulation of DEPTOR predicts a poor prognosis of ESCC patients. In addition, we found that the expression of DEPTOR negatively regulates the tumorigenic activities of ESCC cell lines (KYSE150, KYSE510 and KYSE190). Furthermore, ectopic DEPTOR expression caused a significant suppression of the cellular proliferation, migration and invasion of KYSE150 cells, which has the lowest expression level of DEPTOR in the three cell lines. Meanwhile, CRISPR/Cas9 mediated knockout of DEPTOR in KYSE-510 cells significantly promoted cellular proliferation, migration and invasion. In addition, in vivo assays further revealed that tumor growth was significantly inhibited in xenografts with ectopic DEPTOR expression as compared to untreated KYSE150 cells, and was markedly enhanced in DEPTOR knockout KYSE-510 cells. Biochemical studies revealed that overexpression of DEPTOR led to the suppression of AKT/mTOR pathway as evidenced by reduced phosphorylation of AKT, mTOR and downstream SGK1, indicating DEPTOR might control the progression of ESCC through AKT/mTOR signaling pathway. Thus, these findings, for the first time, demonstrated that DEPTOR inhibits the tumorigenesis of ESCC cells and might serve as a potential therapeutic target or prognostic marker for human patients with ESCC.

Antitumor activity and inhibitory effects on cancer stem cell-like properties of Adeno-associated virus (AAV) -mediated Bmi-1 interference driven by Bmi-1 promoter for gastric cancer

Bmi-1 is aberrantly activated in various cancers and plays a vital role in maintaining the self-renewal of stem cells. Our previous research revealed that Bmi-1 was overexpressed in gastric cancer (GC) and it's overexpression was an independent negative prognostic factor, suggesting it can be a therapeutic target. The main purpose of this investigation was to explore the antitumor activity of Bmi-1 interference driven by its own promoter (Ad-Bmi-1i) for GC. In this study, we used adenoviral vector to deliver Bmi-1 shRNA driven by its own promoter to treat GC. Our results revealed that Ad-Bmi-1i could selectively silence Bmi-1 in GC cells which overexpress Bmi-1 and suppress the malignant phenotypes and stem-like properties of GC cells in vitro and in vivo. Moreover, direct injection of Ad-Bmi-1i into xenografts suppressed tumor growth and destroyed cancer cells in vivo. Ad-Bmi-1i inhibited the proliferation of GC cells mainly via inducing senescence in vitro, but it suppressed tumor through inducing senescence and apoptosis, and inhibiting angiogenesis in vivo. Bmi-1 knockdown by Ad-Bmi-1i downregulated VEGF via inhibiting AKT activity. These results suggest that Ad-Bmi-1i not only inhibits tumor growth and stem cell-like phenotype by inducing cellular senescence directly, but also has an indirect anti-tumor activity by anti-angiogenesis effects via regulating PTEN/AKT/VEGF pathway. Transfer of gene interference guided by its own promoter by an adeno-associated virus (AAV) vector might be a potent antitumor approach for cancer therapy.

Evaluation of mTOR signaling pathway proteins in rat gastric mucosa exposed to sulfite and ghrelin

BACKGROUND/AIMS

Mammalian target of rapamycin (mTOR) signaling serves as a central regulator of cell growth, proliferation, and survival. In this study, we planned to evaluate the expressions of mTOR signaling constituents (p-p70S6K, p-mTOR, and p-Tuberin) in rat gastric mucosa and to compare the results in sulfite- and sulfite+ghrelin-exposed groups.

MATERIALS AND METHODS

Rats were divided into three groups: the control group (C), the sodium metabisulfite (Na2S2O5) (S) group, and sulfite+ghrelin (SG) group. Sodium metabisulfite at 100 mg/kg/day was administered via gavage, and ghrelin at 20 μg/kg/day was administered intraperitoneally for 35 days. We have used immunohistochemistry for mTOR signaling pathway components.

RESULTS

There were no significant differences for p-p70S6K and p-mTOR expression among the C, S, and SG groups. Tuberin expression was significantly increased in the S group compared to the C group. Furthermore, tuberin expression was found to be significantly decreased in the SG group.

CONCLUSION

This study is the first one in the literature that shows the expression of mTOR signaling proteins in gastric mucosa of rats exposed to sulfite and ghrelin. Furthermore, it demonstrates that ghrelin treatment reduces p-Tuberin expression induced by ingested sulfite.

The selective MEK1 inhibitor Selumetinib enhances the antitumor activity of everolimus against renal cell carcinoma in vitro and in vivo

Renal cell carcinoma (RCC) is a urologic malignant cancer and often diagnosed at an advanced stage, which results in high mortality. Targeted therapy may improve the quality of life and survival of patients who are not suitable for nephrectomy. Everolimus, an mTOR inhibitor, is currently used as sequential or second-line therapy for RCC refractory to Sunitinib or sorafenib. However, its efficiency is palliative. In this study, we evaluated whether the antitumor activity of everolimus against RCC is enhanced by Selumetinib, a selective MEK1 inhibitor. We discovered that everolimus in combination with Selumetinib synergistically inhibited the proliferation of Caki-1, 786-O and 769-P cells in vitro. Mechanistically, this combination decreased p-RPS6 and p-4E-BP1 dramatically, which causes G1 cell cycle arrest and prevents reactivation of AKT and ERK. In vivo, the antitumor efficacy and pharmacodynamic biomarkers of the combination therapy were recapitulated in Caki-1 xenograft model. In addition, this combination treatment potently inhibited angiogenesis in xenograft models by impairing VEGF secretion from tumor cells. Our findings provide a sound evidence that combination of everolimus and Selumetinib is a potential dual-targeted strategy for renal cell carcinoma.

The Effect of Targeted Therapy for Genitourinary Malignancies on Sexual Function and Fertility

PURPOSE OF REVIEW

Targeted therapy for genitourinary cancer is being used at an increasing rate. These medications show great survival benefit but are relatively lacking in long-term adverse effect data. With increasing survivability, measures to improve quality of life must be considered for GU cancer and a large proponent of this is sexual function.

RECENT FINDINGS

mTOR inhibitors have shown an effect on testosterone levels and may have a link to abnormal semen parameters. Tyrosine kinase inhibitors (TKIs) have shown no adverse sexual outcomes in the literature. There are laboratory links to tyrosine kinases having a beneficial effect on erectile and sexual function. Possible sexual side effects must be discussed with patients receiving a diagnosis of cancer. Further research is required to determine the exact mechanisms and outcomes of sexual function with new and emerging targeted therapy.

Effects of mTOR inhibition on cardiac and adipose tissue pathology and glucose metabolism in rats with metabolic syndrome

The mammalian target of rapamycin (mTOR) is a regulator of metabolism and is implicated in pathological conditions such as obesity and diabetes. We aimed to investigate the role of mTOR in obesity. A new animal model of metabolic syndrome (MetS), named DahlS.Z-Lepr^fa /Lepr^fa (DS/obese) rats was established previously in our laboratory. In this study, we used this model to evaluate the effects of mTOR inhibition on cardiac and adipose tissue pathology and glucose metabolism. DS/obese rats were treated with the mTOR inhibitor, everolimus, (0.83 mg/kg per day, per os) for 4 weeks at 9 weeks of age. Age-matched homozygous lean (DahlS.Z-Lepr⁺ /Lepr⁺ or DS/lean) littermates of DS/obese rats were used as controls. Treatment with everolimus ameliorated hypertension, left ventricular (LV) hypertrophy and fibrosis, and LV diastolic dysfunction, and attenuated cardiac oxidative stress and inflammation in DS/obese rats, but had no effect on these parameters in DS/lean rats. Treatment with everolimus reduced Akt Thr308 phosphorylation in the heart of DS/obese rats. It also alleviated obesity, hyperphagia, adipocyte hypertrophy, and adipose tissue inflammation in DS/obese rats. Everolimus treatment exacerbated glucose intolerance, but did not affect Akt phosphorylation levels in the fat or liver in these rats. Pancreatic β-cell mass was increased in DS/obese rats compared with that in DS/lean rats and this effect was attenuated by everolimus. Activation of mTOR signaling contributes to the pathophysiology of MetS and its associated complications. And mTOR inhibition with everolimus ameliorated obesity as well as cardiac and adipose tissue pathology, but exacerbated glucose metabolism in rats with MetS.

Controlled Release of Second Generation mTOR Inhibitors to Restrain Inflammation in Primary Immune Cells

Autoimmune disease occurs when the immune system incorrectly targets the body's own tissue. Inflammatory CD4⁺ T cell phenotypes, such as T_H1 and T_H17, are key drivers of this attack. Recent studies demonstrate treatment with rapamycin-a key inhibitor of the mTOR pathway-can skew T cell development, moving T cell responses away from inflammatory phenotypes and toward regulatory T cells (T_REGS). T_REGS are important in inducing and maintaining tolerance to self-antigens, creating new potential to treat autoimmune diseases more effectively and specifically. Next generation analogs of rapamycin, such as everolimus and temsirolimus, confer increased potency with reduced toxicity, but are understudied in the context of autoimmunity. Further, these drugs are still broadly-acting and require frequent treatment due to short half-lives. Thus, there is strong interest in harnessing the unique properties of biomaterials-controlled drug release and targeting, for example, to improve autoimmune therapies. Using second generation mTOR inhibitors and rapamycin, we prepared sets of degradable polymer particles from poly(lactide-co-glycolide). We then used these materials to assess physicochemical properties and the ability to control autoimmune inflammation in a primary cell co-culture model. Treatment with particle formulations resulted in significant dose-dependent decreases in dendritic cell activation, T cell proliferation, inflammatory cytokines, and frequencies of inflammatory T_H1 phenotypes. Considering the current limitations of rapamycin, and the potential of next-generation analogs, this work provides a screening platform for biomaterials and sets the stage for in vivo evaluation, where delivery kinetics, stability, and targeting could improve autoimmune therapies through biomaterial-enabled delivery.

Recent Advances and Challenges of mTOR Inhibitors Use in the Treatment of Patients with Tuberous Sclerosis Complex

Tuberous sclerosis complex (TSC) is a genetic condition characterized by the presence of benign, noninvasive, and tumor-like lesions called hamartomas that can affect multiple organ systems and are responsible for the clinical features of the disease. In the majority of cases, TSC results from mutations in the TSC1 and TSC2 genes, leading to the overactivation of the mammalian target of rapamycin (mTOR) signalling pathway, which controls several cell functions, including cell growth, proliferation, and survival. The establishment of a connection between TSC and mTOR led to the clinical use of drugs known as mTOR inhibitors (like rapamycin, also known as sirolimus and everolimus), which are becoming an increasingly interesting tool in the management of TSC-associated features, such as subependymal giant cell astrocytomas, renal angiomyolipomas, and also epilepsy. However, the intrinsic characteristics of these drugs and their systemic effects in such a heterogeneous condition pose many challenges in clinical practice, so that some questions remain unanswered. This article provides an overview of the pharmacological aspects of mTOR inhibitors about the clinical trials leading to their approval in TSC-related conditions and exposes current challenges and future directions associated with this promising therapeutic line.

High-content screening of clinically tested anticancer drugs identifies novel inhibitors of human MRP1 (ABCC1)

Multidrug resistance protein 1 (MRP1/ABCC1), an integral transmembrane efflux transporter, belongs to the ATP-binding cassette (ABC) protein superfamily. MRP1 governs the absorption and disposition of a wide variety of endogenous and xenobiotic substrates including various drugs across organs and physiological barriers. Additionally, its overexpression has been implicated in multidrug resistance in chemotherapy of multiple cancers. Here, we describe the development of a high content imaging-based screening assay for MRP1 activity. This live cell-based automated microscopy assay is very robust and allows simultaneous detection of cell permeable, non-toxic and potent inhibitors. The validity of the assay was demonstrated by profiling a library of 386 anti-cancer compounds, which are under clinical trials, for interactions with MRP1. The assay identified 12 potent inhibitors including two known MRP1 inhibitors, cyclosporine A and rapamycin. On the other hand, MRP1-inhibitory activity of tipifarnib, AZD1208, deforolimus, everolimus, temsirolimus, HS-173, YM201636, ESI-09, TAK-733, and CX-6258 has not been previously reported. Inhibition of MRP1 activity was further validated using flow cytometry and confocal microscopy for the respective detection of calcein and doxorubicin in MRP1-overexpressing cells. Among the identified compounds, tipifarnib, AZD1208, rapamycin, deforolimus, everolimus, TAK-733, and temsirolimus resensitized MRP1-overexpressing H69AR cells towards vincristine, a cytotoxic chemotherapeutic agent, by 2-6-fold. Using purified HEK293 membrane vesicles overexpressing MRP1, MRP2, MRP3, and MRP4, we also demonstrated that the identified compounds exert differential and selective response on the uptake of estradiol glucuronide, an endogenous MRP substrate. In summary, we demonstrated the effectiveness of the high content imaging-based high-throughput assay for profiling compound interaction with MRP1.

mTOR activity in AIDS-related diffuse large B-cell lymphoma

BACKGROUND

Patients infected with HIV have a significantly increased risk of developing non-Hodgkin lymphomas despite the widespread use of HAART. To investigate mTOR pathway activity in acquired immunodeficiency syndrome (AIDS) related diffuse large B-cell lymphoma AR-DLBCL, we used immunohistochemistry to examine the presence of the phosphorylated 70 ribosomal S6 protein-kinase (p70S6K), an extensively studied effector of mTOR Complex 1 (mTORC1) and the phosphorylated phosphatase and tensin homolog (pPTEN), a negative regulator of mTORC1 pathway.

MATERIALS AND METHODS

We evaluated tissue samples from 126 patients with AR-DLBCL. Among them, 98 samples were from tissue microarrays (TMAs) supplied by the Aids and Cancer Specimen Resource (ACSR), the remaining 28 samples were from cases diagnosed and treated at the University of California, San Diego (UCSD). The presence of p70S6K was evaluated with two antibodies directed against the combined epitopes Ser235/236 and Ser240/244, respectively; and additional monoclonal anti-bodies were used to identify pPTEN and phosphorylated proline-rich Akt substrate of 40kDa (pPRAS40). The degree of intensity and percentage of cells positive for p70S6K and pPTEN were assessed in all the samples. In addition, a subgroup of 28 patients from UCSD was studied to assess the presence of pPRAS40, an insulin-regulated activator of the mTORC1. The expression of each of these markers was correlated with clinical and histopathologic features.

RESULTS

The majority of the patients evaluated were males (88%); only two cases (1.6%) were older than 65 years of age. We found high levels of both p70S6K-paired epitopes studied, 48% positivity against Ser235/236 (44% in ACSR and 64% in UCSD group), and 86% positivity against Ser240/244 (82% in ACSR and 100% in UCSD group). We observed more positive cells and stronger intensity with epitope Ser240/244 in comparison to Ser235/236 (p<0.0001). The degree of intensity and percentage of cells positive for pPTEN was positively correlated with p70S6K levels (p = 0.016 for 235/236 and p = 0.007 for 240/244). High levels of pPRAS40 were observed in the majority of the cases evaluated (64.3%), but no correlation was found with either pPTEN (p = 0.9) or p70S6K (p = 0.9) levels.

CONCLUSION

AR-DLBCL frequently contain p70S6K, a main downstream effector of the mTOR pathway. The presence of p70S6K is positively correlated with pPTEN, an inactive form of PTEN, which makes mTORC1 activated. The presence of p70S6K was independent of HIV viral load or CD4 (+) counts. These results suggest that the mTOR pathway is active in the majority of AR-DLBCL, and p70S6K, particularly the Ser240/244 epitope immunohistochemistry is an excellent surrogate biomarker, which could be used to identify cases expected to be responsive to mTOR inhibitors.

New treatment options for metastatic renal cell carcinoma with prior anti-angiogenesis therapy

Angiogenesis is a critical process in the progression of advanced renal cell carcinoma. Agents targeting angiogenesis have played a primary role in the treatment of metastatic renal cell carcinoma. However, resistance to anti-angiogenesis therapy almost always occurs, and major progress has been made in understanding its underlying molecular mechanism. Axitinib and everolimus have been used extensively in patients whom have had disease progression after prior anti-angiogenesis therapy. Recently, several new agents have been shown to improve overall survival in comparison with everolimus. This review provides an in-depth summary of drugs employable in the clinical setting, the rationale to their use, and the studies conducted leading to their approval for use and provides perspective on the paradigm shift in the treatment of renal cell carcinoma. Highlighted are the newly approved agents cabozantinib, nivolumab, and lenvatinib for advanced renal cell carcinoma patients treated with prior anti-angiogenesis therapy.