Is mTOR Inhibitor Good Enough for Treatment All Tumors in TSC Patients?

Recurrent Tuberous Sclerosis Complex/Mammalian Target of Rapamycin Mutations Define Primary Renal Hemangioblastoma as a Unique Entity Distinct From Its Central Nervous System Counterpart

ABSTRACT

Renal hemangioblastoma (HB) is a rare subset of HBs arising outside of the central nervous system (CNS), with its molecular drivers remaining entirely unknown. There were no significant alterations detected in previous studies, including von Hippel-Lindau gene alterations, which are commonly associated with CNS-HB. This study aimed to determine the real molecular identity of renal HB and better understand its relationship with CNS-HB. A cohort of 10 renal HBs was submitted for next-generation sequencing technology. As a control, 5 classic CNS-HBs were similarly analyzed. Based on the molecular results, glycoprotein nonmetastatic B (GPNMB) immunohistochemistry was further performed in the cases of renal HB and CNS-HB. Mutational analysis demonstrated that all 10 renal HBs harbored somatic mutations in tuberous sclerosis complex 1 ( TSC1 , 5 cases), TSC2 (3 cases), and mammalian target of rapamycin (2 cases), with the majority classified as pathogenic or likely pathogenic. The CNS-HB cohort uniformly demonstrated somatic mutations in the von Hippel-Lindau gene. GPNMB was strong and diffuse in all 10 renal HBs and completely negative in CNS-HBs, reinforcing the molecular findings. Our study reveals a specific molecular hallmark in renal HB, characterized by recurrent TSC/mammalian target of rapamycin mutations, which defines it as a unique entity distinct from CNS-HB. This molecular finding potentially expands the therapeutic options for patients with renal HB. GPNMB can be considered for inclusion in immunohistochemical panels to improve renal HB identification.

Sirolimus can promote the disappearance of renal angiomyolipoma associated with tuberous sclerosis complex: a prospective cohort study

BACKGROUND

Renal angiomyolipoma (RAML) is the most common kidney lesion in patients with tuberous sclerosis complex (TSC), affecting about 80% of patients. It is a benign tumor that grows over time, usually bilaterally, and can easily lead to kidney complications such as acute hemorrhage. Herein, we investigated the efficacy and safety of sirolimus in children with TSC-associated RAML and explored the factors affecting tumor disappearance under sirolimus treatment through subgroup analysis.

METHODS

A prospective cohort study was conducted. Sirolimus was initiated at 1 mg/(m2 × day), and dose adjustments were made by a 2-week titration period to attain a trough blood concentration of 5-10 ng/mL. The disappearance of RAML in children after sirolimus treatment was observed, and Cox regression was used to screen the factors affecting tumor disappearance.

RESULTS

One hundred and twenty-six patients who met the criteria were analyzed. After 3 months, 6 months, 12 months, and 24 months of follow-up, tumors disappeared in 18 (14.3%), 30 (23.8%), 39 (31.0%), and 42 (33.3%) children, respectively. Tumors disappeared in 50 (39.7%) children by the last visit of each individual, and 30 (60%) of them occurred within 6 months. The multivariate Cox regression analysis showed that patients with a smaller maximum tumor diameter at baseline had a higher tumor disappearance rate. Thirty-six (29%) patients had stomatitis during the entire treatment period, and no serious adverse reactions were observed.

CONCLUSIONS

Sirolimus could promote the disappearance of TSC-related RAML. The disappearance rate was correlated with the maximum diameter at baseline, and the smaller the tumor was, the higher the disappearance rate. It is well tolerated in the treatment of RAML associated with TSC.

Malignant tumors in tuberous sclerosis complex: a case report and review of the literature

BACKGROUND

Tuberous sclerosis complex (TSC) is a rare, autosomal dominant genetic disease that arises from TSC1 or TSC2 genetic mutations. These genetic mutations can induce the development of benign tumors in any organ system with significant clinical implications in morbidity and mortality. In rare instances, patients with TSC can have malignant tumors, including renal cell carcinoma (RCC) and pancreatic neuroendocrine tumor (PNET). It is considered a hereditary renal cancer syndrome despite the low incidence of RCC in TSC patients. TSC is typically diagnosed in prenatal and pediatric patients and frequently associated with neurocognitive disorders and seizures, which are often experienced early in life. However, penetrance and expressivity of TSC mutations are highly variable. Herein, we present a case report, with associated literature, to highlight that there exist undiagnosed adult patients with less penetrant features, whose clinical presentation may contain non-classical signs and symptoms, who have pathogenic TSC mutations.

CASE PRESENTATION

A 31-year-old female with past medical history of leiomyomas status post myomectomy presented to the emergency department for a hemorrhagic adnexal cyst. Imaging incidentally identified a renal mass suspicious for RCC. Out of concern for hereditary leiomyomatosis and renal cell carcinoma (HLRCC) syndrome, the mass was surgically removed and confirmed as RCC. Discussion with medical genetics ascertained a family history of kidney cancer and nephrectomy procedures and a patient history of ungual fibromas on the toes. Genetic testing for hereditary kidney cancer revealed a 5'UTR deletion in the TSC1 gene, leading to a diagnosis of TSC. Following the diagnosis, dermatology found benign skin findings consistent with TSC. About six months after the incidental finding of RCC, a PNET in the pancreatic body/tail was incidentally found on chest CT imaging, which was removed and determined to be a well-differentiated PNET. Later, a brain MRI revealed two small cortical tubers, one in each frontal lobe, that were asymptomatic; the patient's history and family history did not contain seizures or learning delays. The patient presently shows no evidence of recurrence or metastatic disease, and no additional malignant tumors have been identified.

CONCLUSIONS

To our knowledge, this is the first report in the literature of a TSC patient without a history of neurocognitive disorders with RCC and PNET, both independently rare occurrences in TSC. The patient had a strong family history of renal disease, including RCC, and had several other clinical manifestations of TSC, including skin and brain findings. The incidental finding and surgical removal of RCC prompted the genetic evaluation and diagnosis of TSC, leading to a comparably late diagnosis for this patient. Reporting the broad spectrum of disease for TSC, including more malignant phenotypes such as the one seen in our patient, can help healthcare providers better identify patients who need genetic evaluation and additional medical care.

Rare Neuronal, Glial and Glioneuronal Tumours in Adults

Rare glial, neuronal and glioneuronal tumours in adults form a heterogeneous group of rare, primary central nervous system tumours. These tumours, with a glial and/or neuronal component, are challenging in terms of diagnosis and therapeutic management. The novel classification of primary brain tumours published by the WHO in 2021 has significantly improved the diagnostic criteria of these entities. Indeed, diagnostic criteria are nowadays multimodal, including histological, immunohistochemical and molecular (i.e., genetic and methylomic). These integrated parameters have allowed the specification of already known tumours but also the identification of novel tumours for a better diagnosis.

Challenges in Treating Genodermatoses: New Therapies at the Horizon

Genodermatoses are rare inherited skin diseases that frequently affect other organs. They often have marked effects on wellbeing and may cause early death. Progress in molecular genetics and translational research has unravelled many underlying pathological mechanisms, and in several disorders with high unmet need, has opened the way for the introduction of innovative treatments. One approach is to intervene where cell-signaling pathways are dysregulated, in the case of overactive pathways by the use of selective inhibitors, or when the activity of an essential factor is decreased by augmenting a molecular component to correct disequilibrium in the pathway. Where inflammatory reactions have been induced by a genetically altered protein, another possible approach is to suppress the inflammation directly. Depending on the nature of the genodermatosis, the implicated protein or even on the particular mutation, to correct the consequences or the genetic defect, may require a highly personalised stratagem. Repurposed drugs, can be used to bring about a "read through" strategy especially where the genetic defect induces premature termination codons. Sometimes the defective protein can be replaced by a normal functioning one. Cell therapies with allogeneic normal keratinocytes or fibroblasts may restore the integrity of diseased skin and allogeneic bone marrow or mesenchymal cells may additionally rescue other affected organs. Genetic engineering is expanding rapidly. The insertion of a normal functioning gene into cells of the recipient is since long explored. More recently, genome editing, allows reframing, insertion or deletion of exons or disruption of aberrantly functioning genes. There are now several examples where these stratagems are being explored in the (pre)clinical phase of therapeutic trial programmes. Another stratagem, designed to reduce the severity of a given disease involves the use of RNAi to attenuate expression of a harmful protein by decreasing abundance of the cognate transcript. Most of these strategies are short-lasting and will thus require intermittent life-long administration. In contrast, insertion of healthy copies of the relevant gene or editing the disease locus in the genome to correct harmful mutations in stem cells is more likely to induce a permanent cure. Here we discuss the potential advantages and drawbacks of applying these technologies in patients with these genetic conditions. Given the severity of many genodermatoses, prevention of transmission to future generations remains an important goal including offering reproductive choices, such as preimplantation genetic testing, which can allow selection of an unaffected embryo for transfer to the uterus.

Economic burden associated with tuberous sclerosis complex in patients with epilepsy

OBJECTIVES

Data on the economic burden associated with tuberous sclerosis complex (TSC) among patients with epilepsy in the United States (US) are limited. This study aimed to assess all-cause and epilepsy-related healthcare resource utilization (HRU) and healthcare costs in the US among patients with epilepsy and TSC compared with patients with epilepsy but without TSC.

METHODS

This retrospective study was conducted using the Symphony Health Solutions claims database (April 1, 2017-June 30, 2019). Patients with ≥1 medical claim with a diagnosis code representing epilepsy or seizures were assigned to the cohort with TSC if they had ≥1 medical claim for TSC; the remaining patients were assigned to the cohort without TSC. Patients in the cohort with TSC were exactly matched 1:5 on demographics to patients in the cohort without TSC. All-cause and epilepsy-related HRU, medical charges, prescription drug costs, and the use of antiepileptic drugs (AEDs) were compared between the matched cohorts over the 1-year study period.

RESULTS

A total of 2028 patients with epilepsy and TSC were matched to 10,140 patients with epilepsy but without TSC. Patients with TSC were more likely to have a diagnosis code for refractory epilepsy (38.7% vs. 10.2%, p < 0.001) and more likely to have used an AED (89.5% vs. 71.2%, p < 0.001) than patients without TSC over the study period. On average, patients with TSC received 2.1 distinct AEDs versus 1.3 distinct AEDs among patients without TSC. Compared with patients without TSC, patients with TSC had numerically but not statistically higher incidence rates of all-cause outpatient, clinic, office, and other visits; significantly lower rates of all-cause inpatient and emergency room visits (p < 0.001); and statistically significantly higher incidence rates of epilepsy-related outpatient, inpatient, office, and other visits (p ≤ 0.001). All-cause prescription drug costs were significantly higher among patients with TSC than patients without TSC (cost difference per patient: $14,179, p < 0.001). All-cause medical service charges were numerically higher for patients with TSC, but the differences were not statistically significant (charge difference per patient: $4293 for medical services, p = 0.707). Epilepsy-related costs were significantly higher for patients with TSC; the cost difference per patient was $14,639 for prescription costs (p < 0.001), and the charge difference per patient was $16,838 for medical charges (p = 0.019).

CONCLUSION

The results of this study underscore the high epilepsy-related HRU and costs incurred by patients with epilepsy and TSC relative to those incurred by patients with epilepsy but without TSC.

Recent advances in human stem cell-based modeling of Tuberous Sclerosis Complex

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterized by epilepsy, intellectual disability, and benign tumors of the brain, heart, skin, and kidney. Animal models have contributed to our understanding of normal and abnormal human brain development, but the construction of models that accurately recapitulate a human pathology remains challenging. Recent advances in stem cell biology with the derivation of human-induced pluripotent stem cells (hiPSCs) from somatic cells from patients have opened new avenues to the study of TSC. This approach combined with gene-editing tools such as CRISPR/Cas9 offers the advantage of preserving patient-specific genetic background and the ability to generate isogenic controls by correcting a specific mutation. The patient cell line and the isogenic control can be differentiated into the cell type of interest to model various aspects of TSC. In this review, we discuss the remarkable capacity of these cells to be used as a model for TSC in two- and three-dimensional cultures, the potential variability in iPSC models, and highlight differences between findings reported to date.

miR-125b-5p/STAT3 Pathway Regulated by mTORC1 Plays a Critical Role in Promoting Cell Proliferation and Tumor Growth

Aberrant activation of the mammalian target of rapamycin complex 1 (mTORC1) plays a critical role in tumorigenesis. However, the precise underlying mechanism is still not fully understood. Although accumulating evidence suggests that mTORC1 signaling is regulated by microRNAs (miRNAs), whether miRNAs are involved in the tumorigenesis mediated by mTORC1 dysregulation remains largely unclear. In our study, the comparison between tuberous sclerosis complex 1 (Tsc1) -/- or Tsc2-/- mouse embryonic fibroblasts (MEFs) and the control cells revealed the involvement of microRNA-125b-5p (miR-125b-5p) in the tumorigenesis driven by mTORC1 activation. Our study also showed that loss of TSC1 or TSC2 led to significant downregulation of miR-125b-5p and upregulation of signal transducer and activator of transcription 3 (STAT3) via mTORC1 activation. Overexpression of miR-125b-5p inhibited the proliferation of the cells with hyperactivated mTORC1 both in vitro and in vivo. Furthermore, we demonstrated that STAT3 is a direct target of miR-125b-5p. Depletion of STAT3 mimicked the effect of ectopic expression of miR-125b-5p, and reintroduction of STAT3 rescued the compromised cell proliferation driven by miR-125b-5p overexpression in Tsc1-/- or Tsc2-/- MEFs. We conclude that the miR-125b-5p/STAT3 pathway plays a crucial role in hyperactivated mTORC1-mediated tumorigenesis and miR-125b-5p is a potential therapeutic target.

Autophagy Modulators: Mechanistic Aspects and Drug Delivery Systems

Autophagy modulation is considered to be a promising programmed cell death mechanism to prevent and cure a great number of disorders and diseases. The crucial step in designing an effective therapeutic approach is to understand the correct and accurate causes of diseases and to understand whether autophagy plays a cytoprotective or cytotoxic/cytostatic role in the progression and prevention of disease. This knowledge will help scientists find approaches to manipulate tumor and pathologic cells in order to enhance cellular sensitivity to therapeutics and treat them. Although some conventional therapeutics suffer from poor solubility, bioavailability and controlled release mechanisms, it appears that novel nanoplatforms overcome these obstacles and have led to the design of a theranostic-controlled drug release system with high solubility and active targeting and stimuli-responsive potentials. In this review, we discuss autophagy modulators-related signaling pathways and some of the drug delivery strategies that have been applied to the field of therapeutic application of autophagy modulators. Moreover, we describe how therapeutics will target various steps of the autophagic machinery. Furthermore, nano drug delivery platforms for autophagy targeting and co-delivery of autophagy modulators with chemotherapeutics/siRNA, are also discussed.

Are Sporadic Eosinophilic Solid and Cystic Renal Cell Carcinomas Characterized by Somatic Tuberous Sclerosis Gene Mutations?

Eosinophilic solid and cystic renal cell carcinomas (ESC RCC) is a rare, unique tumor type not yet included in the World Health Organization classification of renal neoplasia. Separately, RCCs found in patients with tuberous sclerosis complex (TSC) have recently been categorized into 3 morphologic groups: RCC with a tubulopapillary architecture separated by smooth muscle stroma, chromophobe-like, and eosinophilic-microcytic type. The third classification has been identified in ∼11% of TSC-associated RCC and have histology identical to ESC RCCs. The sporadic form of ESC RCC, not associated with TSC, have only been characterized on the cytogenetic level and the full molecular underpinnings have yet to be examined. Using next-generation sequencing we present 2 cases of sporadic ESC RCC in patients without clinical features of tuberous sclerosis, which demonstrate pathogenic somatic TSC2 gene mutations. These mutations are without other alterations in any other genes associated with RCC, suggesting that sporadic ESC RCC may be characterized by somatic tuberous sclerosis gene mutations (TSC2).

mTOR Signaling Pathway in Cancer Targets Photodynamic Therapy In Vitro

The Mechanistic or Mammalian Target of Rapamycin (mTOR) is a major signaling pathway in eukaryotic cells belonging to the P13K-related kinase family of the serine/threonine protein kinase. It has been established that mTOR plays a central role in cellular processes and implicated in various cancers, diabetes, and in the aging process with very poor prognosis. Inhibition of the mTOR pathway in the cells may improve the therapeutic index in cancer treatment. Photodynamic therapy (PDT) has been established to selectively eradicate neoplasia at clearly delineated malignant lesions. This review highlights recent advances in understanding the role or regulation of mTOR in cancer therapy. It also discusses how mTOR currently contributes to cancer as well as future perspectives on targeting mTOR therapeutically in cancer in vitro.

The scientific report from the first pressurized intraperitoneal aerosol chemotherapy (PIPAC) procedures performed in the eastern part of Central Europe

Objective To perform a single-centre, detailed analysis of the preparations for the introduction of the first pressurized intraperitoneal aerosol chemotherapy (PIPAC) programme in the eastern part of Central Europe. Methods The study analysed the 14-month preparation period prior to the performance of the first PIPAC procedure with respect to: (i) general preparations; (ii) patient referral and qualification; (iii) the first PIPAC procedure; (iv) the 2 weeks following PIPAC programme establishment; and (v) general problematic issues that arose. Results The length of time needed to prepare our institution for the first PIPAC procedure was extremely long compared with other European Union PIPAC centres: 14 months versus a standard 3-6 months of preparation. The longest amount of time (12 months) was required to prepare the required paperwork. Conclusions A new PIPAC programme was successfully established in the eastern part of Central Europe. The length of time to implement this method was significantly longer because of lengthy bureaucratic processes. These current findings should help new centres, especially in this part of Europe, to establish a PIPAC programme more quickly.

A new drug combination significantly reduces kidney tumor progression in kidney mouse model

Tuberous sclerosis complex (TSC) disease is associated with tumors in many organs, particularly angiomyolipoma (AML) in the kidneys. Loss or inactivation of TSC1/2 results in high levels of HIF-α activity and VEGF expression. mTOR inhibitor (rapamycin) and the AMPK activator 5-aminoimidazole-4-carboxamide (AICA)-riboside (AICAR) are currently used separately to treat cancer patients. Here, we investigated the effect of a novel combination of rapamycin and AICAR on tumor progression. Our data show that treatment of AML human cells with drug combinations resulted in 5-7-fold increase in cell apoptosis compared to each drug alone. In addition, drug combinations resulted in 4-5-fold decrease in cell proliferation compared to each drug alone. We found that drug combinations abolished Akt and HIF activity in AML cells. The drug combinations resulted in decrease in cell invasion and cell immigration by 70% and 84%, respectively in AML cells. The combined drugs also significantly decreased the VEGF expression compare to each drug alone in AML cells. Drug combinations effectively abolished binding of HIF-2α to the putative Akt site in the nuclear extracts isolated from AML cells. Treatment TSC mice with drug combinations resulted in 75% decrease in tumor number and 88% decrease in tumor volume compared to control TSC mice. This is first evidence that drug combinations are effective in reducing size and number of kidney tumors without any toxic effect on kidney. These data will provide evidence for initiating a new clinical trial for treatment of TSC patients.

Age-Dependent Cellular and Behavioral Deficits Induced by Molecularly Targeted Drugs Are Reversible

Newly developed targeted anticancer drugs inhibit signaling pathways commonly altered in adult and pediatric cancers. However, as these pathways are also essential for normal brain development, concerns have emerged of neurologic sequelae resulting specifically from their application in pediatric cancers. The neural substrates and age dependency of these drug-induced effects in vivo are unknown, and their long-term behavioral consequences have not been characterized. This study defines the age-dependent cellular and behavioral effects of these drugs on normally developing brains and determines their reversibility with post-drug intervention. Mice at different postnatal ages received short courses of molecularly targeted drugs in regimens analagous to clinical treatment. Analysis of rapidly developing brain structures important for sensorimotor and cognitive function showed that, while adult administration was without effect, earlier neonatal administration of targeted therapies attenuated white matter oligodendroglia and hippocampal neuronal development more profoundly than later administration, leading to long-lasting behavioral deficits. This functional impairment was reversed by rehabilitation with physical and cognitive enrichment. Our findings demonstrate age-dependent, reversible effects of these drugs on brain development, which are important considerations as treatment options expand for pediatric cancers.Significance: Targeted therapeutics elicit age-dependent long-term consequences on the developing brain that can be ameliorated with environmental enrichment. Cancer Res; 78(8); 2081-95. ©2018 AACR.

A Novel Mutation in TSC2 Gene: A 34-Year-Old Female with Pulmonary Lymphangioleiomyomatosis with Concomitant Hepatic Lesions

Tuberous sclerosis complex (TSC) is an autosomal dominant disease resulting from mutation(s) in TSC1 or TSC2 genes. TSC is associated with the formation of hamartomas in the brain, heart, eyes, skin, kidneys, and lymphangioleiomyomatosis (LAM) of the lungs. LAM is almost restricted to women in reproductive age. Different mutations in TSC1 and TSC2 genes have been reported in the literature. Here, we present a female patient with TSC-LAM with a novel mutation in TSC2 gene. The patient also had multiple hepatic angiomyolipomas, which is a relatively less-reported manifestation of the disease. The impact of this mutation on the pattern of disease presentation and response to treatment is not clear yet.

Evolving Treatment Paradigms in Non-clear Cell Kidney Cancer

OPINION STATEMENT

With no therapy specifically approved for non-clear cell cancers of the kidney, this disease remains an orphan site. Clear cell renal cancers (ccRCC) have seen a flurry of activity with multiple agents gaining Food and Drug Administration (FDA) approval in recent years. Simultaneously, non-clear cell RCC (ncRCC) have also seen a fair share of activity and exploration of new agents in development but no specific FDA approvals. Non-clear cell RCC is a mixed bag of multiple types of tumors originating in the kidney with distinct clinical molecular and genetic characteristics that vary significantly from clear cell carcinoma of the kidney. Conventionally, non-clear cell RCC have been treated with the same therapies as clear cell RCC. The clinical trials are typically conducted in ccRCC and the FDA approval covers non-clear cell cancer as well. Few randomized clinical trials have been conducted specifically for ncRCC. With the advent of molecular and tumor genomic testing, leading to discovery of targets and associated therapies for ncRCC, a specific review of the state of management of this disease is timely and clinically relevant.

Inhibiting 4EBP1 in Glioblastoma

Glioblastoma is the most common and aggressive adult brain cancer. Tumors show frequent dysregulation of the PI3K-mTOR pathway. Although a number of small molecules target the PI3K-AKT-mTOR axis, their preclinical and clinical efficacy has been limited. Reasons for treatment failure include poor penetration of agents into the brain and observations that blockade of PI3K or AKT minimally affects downstream mTOR activity in glioma. Clinical trials using allosteric mTOR inhibitors (rapamycin and rapalogs) to treat patients with glioblastoma have also been unsuccessful or uncertain, in part, because rapamycin inefficiently blocks the mTORC1 target 4EBP1 and feeds back to activate PI3K-AKT signaling. Inhibitors of the mTOR kinase (TORKi) such as TAK-228/MLN0128 interact orthosterically with the ATP- and substrate-binding pocket of mTOR kinase, efficiently block 4EBP1 in vitro, and are currently being investigated in the clinical trials. Preclinical studies suggest that TORKi have poor residence times of mTOR kinase, and our data suggest that this poor pharmacology translates into disappointing efficacy in glioblastoma xenografts. RapaLink-1, a TORKi linked to rapamycin, represents a drug with improved pharmacology against 4EBP1. In this review, we clarify the importance of 4EBP1 as a biomarker for the efficacy of PI3K-AKT-mTOR inhibitors in glioblastoma. We also review mechanistic data by which RapaLink-1 blocks p-4EBP1 and discuss future clinical strategies for 4EBP1 inhibition in glioblastoma. Clin Cancer Res; 24(1); 14-21. ©2017 AACR.

Hyperactivated mTORC1 downregulation of FOXO3a/PDGFRα/AKT cascade restrains tuberous sclerosis complex-associated tumor development

Hyperactivation of mammalian target of rapamycin complex 1 (mTORC1), caused by loss-of-function mutations in either the TSC1 or TSC2 gene, leads to the development of tuberous sclerosis complex (TSC), a benign tumor syndrome with multiple affected organs. mTORC1-mediated inhibition of AKT constrains the tumor progression of TSC, but the exact mechanisms remain unclear. Herein we showed that loss of TSC1 or TSC2 downregulation of platelet-derived growth factor receptor α (PDGFRα) expression was mediated by mTORC1. Moreover, mTORC1 inhibited PDGFRα expression via suppression of forkhead box O3a (FOXO3a)-mediated PDGFRα gene transcription. In addition, ectopic expression of PDGFRα promoted AKT activation and enhanced proliferation and tumorigenic capacity of Tsc1- or Tsc2-null mouse embryonic fibroblasts (MEFs), and vice versa. Most importantly, rapamycin in combination with AG1295, a PDGFR inhibitor, significantly inhibited growth of TSC1/TSC2 complex-deficient cells in vitro and in vivo. Therefore, downregulated FOXO3a/PDGFRα/AKT pathway exerts a protective effect against hyperactivated mTORC1-induced tumorigenesis caused by loss of TSC1/TSC2 complex, and the combination of rapamycin and AG1295 may be a new effective strategy for TSC-associated tumors treatment.

TRIM59 is a novel potential prognostic biomarker in patients with non-small cell lung cancer: A research based on bioinformatics analysis

Lung cancer is the leading cause of cancer-associated mortality worldwide and its prognosis is poor. Few effective biomarkers for non-small cell lung cancer (NSCLC) have been translated into the clinical practice aiming to assist in the treatment plan design and prognosis evaluation. The aim of the present study was to identify novel potential prognostic biomarkers for NSCLC. Tripartite motif 59 (TRIM59) was identified from a microarray dataset of matched-samples and was verified as an aberrantly upregulated gene in NSCLC tissue. The expression level of TRIM59 in NSCLC subtypes was observed to be significantly increased in large cell lung carcinoma and squamous cell carcinoma as compared with that in adenocarcinoma. Its expression correlated with several clinicopathological features, including gender, smoking habits, and unfavorable tumor node and pathological stages. Notably, TRIM59 demonstrated a negative correlation with survival time and its overexpression indicated a poor prognosis in NSCLC. Furthermore, univariate and multivariate Cox's regression analyses indicated that TRIM59 was an independent prognostic factor in tumor tissue as compared with age, gender, tumor stage, node stage, and metastasis. Gene set enrichment analysis and protein-protein interaction network construction revealed that TRIM59 was associated with oncogenic mammalian target of rapamycin (MTOR) and eukaryotic initiation factor 4E (EIF4E) signaling through ubiquitin C binding. In conclusion, it was revealed that TRIM59 is a novel prognostic biomarker modulating oncogenic MTOR and EIF4E signaling pathways in NSCLC. These findings provided a novel insight into the clinical application of TRIM59. Therefore, TRIM59 may serve as an independent predictor for prognosis and a potential therapeutic target for NSCLC.

Resistance to mTORC1 Inhibitors in Cancer Therapy: From Kinase Mutations to Intratumoral Heterogeneity of Kinase Activity

Targeting mTORC1 has been thoroughly explored in cancer therapy. Following encouraging preclinical studies, mTORC1 inhibitors however failed to provide substantial benefits in cancer patients. Several resistance mechanisms have been identified including mutations of mTOR and activation of alternate proliferation pathways. Moreover, emerging evidence discloses intratumoral heterogeneity of mTORC1 activity that further contributes to a reduced anticancer efficacy of mTORC1 inhibitors. Genetic heterogeneity as well as heterogeneous conditions of the tumor environment such as hypoxia profoundly modifies mTORC1 activity in tumors and hence influences the response of tumors to mTORC1 inhibitors. Intriguingly, the heterogeneity of mTORC1 activity also occurs towards its substrates at the single cell level, as mutually exclusive pattern of activation of mTORC1 downstream effectors has been reported in tumors. After briefly describing mTORC1 biology and the use of mTORC1 inhibitors in patients, this review will give an overview on concepts of resistance to mTORC1 inhibition in cancer with a particular focus on intratumoral heterogeneity of mTORC1 activity.