Rapamycin weekly maintenance dosing and the potential efficacy of combination sorafenib plus rapamycin but not atorvastatin or doxycycline in tuberous sclerosis preclinical models

Rapidly evolving pelvic lymphangioleiomyomatosis (LAM) mimicking bilateral hydrosalpinx: report of a rare case and literature review

Lymphangioleiomyomatosis (LAM) represents a rare neoplasm affecting almost exclusively women of reproductive age. This condition mainly affects the lungs, but extrapulmonary locations such as the pelvis and the retroperitoneum are possible. Clinical evaluation and ultrasound imaging are usually non-specific, and the diagnosis is obtained through surgical excision and histopathological examination. We report a very rare case of abdominal LAM in a young female patient. A thorough literature review of this rare condition with emphasis on gynecologic implications will be presented. The patient was referred for gynecologic consultation due to pelvic pain and infertility. Unfortunately, despite prompt diagnosis and treatment, the course of the disease was severe and led to patient's exitus in a short time. We encountered an extremely rare deadly pathology mimicking a very common gynecologic condition. The gynecologist must always be alert of possible unexpected conditions that will require prompt attention.

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.

Targeting the biology of aging with mTOR inhibitors

Inhibition of the protein kinase mechanistic target of rapamycin (mTOR) with the Food and Drug Administration (FDA)-approved therapeutic rapamycin promotes health and longevity in diverse model organisms. More recently, specific inhibition of mTORC1 to treat aging-related conditions has become the goal of basic and translational scientists, clinicians and biotechnology companies. Here, we review the effects of rapamycin on the longevity and survival of both wild-type mice and mouse models of human diseases. We discuss recent clinical trials that have explored whether existing mTOR inhibitors can safely prevent, delay or treat multiple diseases of aging. Finally, we discuss how new molecules may provide routes to the safer and more selective inhibition of mTOR complex 1 (mTORC1) in the decade ahead. We conclude by discussing what work remains to be done and the questions that will need to be addressed to make mTOR inhibitors part of the standard of care for diseases of aging.

Effects of Rapamycin on Insulin Brain Endothelial Cell Binding and Blood-Brain Barrier Transport

Rapamycin is an exogenous compound that has been shown to improve cognition in Alzheimer’s disease mouse models and can regulate pathways downstream of the insulin receptor signaling pathway. Insulin is also known to improve cognition in rodent models of Alzheimer’s disease. Central nervous system (CNS) insulin must first cross the blood–brain barrier (BBB), a specialized network of brain endothelial cells. This transport process is regulated by physiological factors, such as insulin itself, triglycerides, cytokines, and starvation. Since rapamycin treatment can alter the metabolic state of rodents, increase the circulating triglycerides, and acts as a starvation mimetic, we hypothesized rapamycin could alter the rate of insulin transport across the BBB, providing a potential mechanism for the beneficial effects of rapamycin on cognition. Using young male and female CD-1 mice, we measured the effects of rapamycin on the basal levels of serum factors, insulin receptor signaling, vascular binding, and BBB pharmacokinetics. We found chronic rapamycin treatment was able to affect basal levels of circulating serum factors and endothelial cell insulin receptor signaling. In addition, while acute rapamycin treatment did affect insulin binding at the BBB, overall transport was unaltered. Chronic rapamycin slowed insulin BBB transport non-significantly (p = 0.055). These results suggest that rapamycin may not directly impact the transport of insulin at the BBB but could be acting to alter insulin signaling within brain endothelial cells, which can affect downstream signaling.

Rapamycin Plus Doxycycline Combination Affects Growth Arrest and Selective Autophagy-Dependent Cell Death in Breast Cancer Cells

Metabolic alteration is characteristic during tumour growth and therapy; however, targeting metabolic rewiring could overcome therapy resistance. mTOR hyperactivity, autophagy and other metabolic processes, including mitochondrial functions, could be targeted in breast cancer progression. We investigated the growth inhibitory mechanism of rapamycin + doxycycline treatment in human breast cancer model systems. Cell cycle and cell viability, including apoptotic and necrotic cell death, were analysed using flow cytometry, caspase activity measurements and caspase-3 immunostainings. mTOR-, autophagy-, necroptosis-related proteins and treatment-induced morphological alterations were analysed by Wes^TM, Western blot, immunostainings and transmission electron microscopy. The rapamycin + doxycycline combination decreased tumour proliferation in about 2/3rd of the investigated cell lines. The continuous treatment reduced tumour growth significantly both in vivo and in vitro. The effect after short-term treatment was reversible; however, autophagic vacuoles and degrading mitochondria were detected simultaneously, and the presence of mitophagy was also observed after the long-term rapamycin + doxycycline combination treatment. The rapamycin + doxycycline combination did not cause apoptosis or necrosis/necroptosis, but the alterations in autophagy- and mitochondria-related protein levels (LC3-B-II/I, p62, MitoTracker, TOM20 and certain co-stainings) were correlated to autophagy induction and mitophagy, without mitochondria repopulation. Based on these results, we suggest considering inducing metabolic stress and targeting mTOR hyperactivity and mitochondrial functions in combined anti-cancer treatments.

mTORC1 promotes cell growth via m6A-dependent mRNA degradation

Dysregulated mTORC1 signaling alters a wide range of cellular processes, contributing to metabolic disorders and cancer. Defining the molecular details of downstream effectors is thus critical for uncovering selective therapeutic targets. We report that mTORC1 and its downstream kinase S6K enhance eIF4A/4B-mediated translation of Wilms' tumor 1-associated protein (WTAP), an adaptor for the N6-methyladenosine (m6A) RNA methyltransferase complex. This regulation is mediated by 5' UTR of WTAP mRNA that is targeted by eIF4A/4B. Single-nucleotide-resolution m6A mapping revealed that MAX dimerization protein 2 (MXD2) mRNA contains m6A, and increased m6A modification enhances its degradation. WTAP induces cMyc-MAX association by suppressing MXD2 expression, which promotes cMyc transcriptional activity and proliferation of mTORC1-activated cancer cells. These results elucidate a mechanism whereby mTORC1 stimulates oncogenic signaling via m6A RNA modification and illuminates the WTAP-MXD2-cMyc axis as a potential therapeutic target for mTORC1-driven cancers.

The paradox of autophagy in Tuberous Sclerosis Complex

Tuberous sclerosis complex (TSC) is an autosomal dominant genetic disorder caused by germline mutations in TSC1 or TSC2 genes, which leads to the hyperactivation of the mTORC1 pathway, an important negative regulator of autophagy. This leads to the development of hamartomas in multiple organs. The variability in symptoms presents a challenge for the development of completely effective treatments for TSC. One option is the treatment with mTORC1 inhibitors, which are targeted to block cell growth and restore autophagy. However, the therapeutic effect of rapamycin seems to be more efficient in the early stages of hamartoma development, an effect that seems to be associated with the paradoxical role of autophagy in tumor establishment. Under normal conditions, autophagy is directly inhibited by mTORC1. In situations of bioenergetics stress, mTORC1 releases the Ulk1 complex and initiates the autophagy process. In this way, autophagy promotes the survival of established tumors by supplying metabolic precursors during nutrient deprivation; paradoxically, excessive autophagy has been associated with cell death in some situations. In spite of its paradoxical role, autophagy is an alternative therapeutic strategy that could be explored in TSC. This review compiles the findings related to autophagy and the new therapeutic strategies targeting this pathway in TSC.

A phase II clinical trial of the Safety Of Simvastatin (SOS) in patients with pulmonary lymphangioleiomyomatosis and with tuberous sclerosis complex

INRODUCTION

The mechanistic target of rapamycin inhibitors (mTORi) sirolimus and everolimus stabilize lung function in patients with pulmonary lymphangioleiomyomatosis (LAM) but do not induce remission. Pre-clinical studies suggest that simvastatin in combination with sirolimus induces LAM cell death. The objective of this study was to assess the safety of simvastatin with either sirolimus or everolimus in LAM patients.

METHODS

This was a phase II single arm trial evaluating the safety of escalating daily simvastatin (20-40 mg) in LAM patients already treated with sirolimus or everolimus. Adverse events and changes in lipid panel profile, pulmonary function tests, and VEGF-D were assessed.

RESULTS

Ten LAM patients on a stable dose of mTORi for >3 months were treated with 20 mg simvastatin for two months followed by 40 mg for two months. The most common adverse events were peripheral edema (30%), cough (30%), and diarrhea (30%). No patients withdrew or had a reduction in simvastatin dose because of adverse events. Two patients required sirolumus dose reduction for supratherapeutic trough levels following simvastatin initiation. Total cholesterol and low density lipoproteins declined over the study period (-46.0 mg/dL±20.8, p = 0.008; -41.9 mg/dL±22.0, p = 0.01, respectively). There was also a decline in FEV1 (-82.0 mL±86.4, p = 0.02) but no significant change in FVC, DLCO, or VEGF-D.

CONCLUSIONS

The combination of simvastatin with mTORi in LAM patients is safe and well-tolerated from an adverse events perspective. The addition of simvastatin, however, was associated with decline in FEV1 and the efficacy of this combination should be explored in larger trials.

Activin-A enhances mTOR signaling to promote aberrant chondrogenesis in fibrodysplasia ossificans progressiva

Fibrodysplasia ossificans progressiva (FOP) is a rare and intractable disease characterized by extraskeletal bone formation through endochondral ossification. Patients with FOP harbor point mutations in ACVR1, a type I receptor for BMPs. Although mutated ACVR1 (FOP-ACVR1) has been shown to render hyperactivity in BMP signaling, we and others have uncovered a mechanism by which FOP-ACVR1 mistransduces BMP signaling in response to Activin-A, a molecule that normally transduces TGF-β signaling. Although Activin-A evokes enhanced chondrogenesis in vitro and heterotopic ossification (HO) in vivo, the underlying mechanisms have yet to be revealed. To this end, we developed a high-throughput screening (HTS) system using FOP patient-derived induced pluripotent stem cells (FOP-iPSCs) to identify pivotal pathways in enhanced chondrogenesis that are initiated by Activin-A. In a screen of 6,809 small-molecule compounds, we identified mTOR signaling as a critical pathway for the aberrant chondrogenesis of mesenchymal stromal cells derived from FOP-iPSCs (FOP-iMSCs). Two different HO mouse models, an FOP model mouse expressing FOP-ACVR1 and an FOP-iPSC-based HO model mouse, revealed critical roles for mTOR signaling in vivo. Moreover, we identified ENPP2, an enzyme that generates lysophosphatidic acid, as a linker of FOP-ACVR1 and mTOR signaling in chondrogenesis. These results uncovered the crucial role of the Activin-A/FOP-ACVR1/ENPP2/mTOR axis in FOP pathogenesis.

Pedal Cutaneous Manifestations of Tuberous Sclerosis

This case report concerns a patient with a painful soft-tissue mass on his fourth toe. He was evaluated for this soft-tissue mass and was diagnosed as having tuberous sclerosis. The podiatric physician should be able to evaluate a patient with a lower-extremity complaint and relate whether this complaint may correlate with a systemic disorder. This case report will make the podiatric physician more aware of tuberous sclerosis and the manifestations of the disorder.

Rapamycin and rapalogs for tuberous sclerosis complex

BACKGROUND

Previous studies have shown potential benefits of rapamycin or rapalogs for treating people with tuberous sclerosis complex. Although everolimus (a rapalog) is currently approved by the FDA (U.S. Food and Drug Administration) and the EMA (European Medicines Agency) for tuberous sclerosis complex-associated renal angiomyolipoma and subependymal giant cell astrocytoma, applications for other manifestations of tuberous sclerosis complex have not yet been established. A systematic review is necessary to establish the clinical value of rapamycin or rapalogs for various manifestations in tuberous sclerosis complex.

OBJECTIVES

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

SEARCH METHODS

Relevant studies were identified by authors from the Cochrane Central Register of Controlled Trials (CENTRAL), Ovid MEDLINE, and clinicaltrials.gov. Relevant resources were also searched by the authors, such as conference proceedings and abstract books of conferences, from e.g. the Tuberous Sclerosis Complex International Research Conferences, other tuberous sclerosis complex-related conferences and the Human Genome Meeting. We did not restrict the searches by language as long as English translations were available for non-English reports.Date of the last searches: 14 March 2016.

SELECTION CRITERIA

Randomized or quasi-randomized studies of rapamycin or rapalogs in people with tuberous sclerosis complex.

DATA COLLECTION AND ANALYSIS

Data were independently extracted by two authors using standard acquisition forms. The data collection was verified by one author. The risk of bias of each study was independently assessed by two authors and verified by one author.

MAIN RESULTS

Three placebo-controlled studies with a total of 263 participants (age range 0.8 to 61 years old, 122 males and 141 females, with variable lengths of study duration) were included in the review. We found high-quality evidence except for response to skin lesions which was judged to be low quality due to the risk of attrition bias. Overall, there are 175 participants in the treatment arm (rapamycin or everolimus) and 88 in the placebo arm. Participants all had tuberous sclerosis complex as proven by consensus diagnostic criteria as a minimum. The quality in the description of the study methods was mixed, although we assessed most domains as having a low risk of bias. Blinding of treatment arms was successfully carried out in all of the studies. However, two studies did not report allocation concealment. Two of the included studies were funded by Novartis Pharmaceuticals.Two studies (235 participants) used oral (systemic) administration of everolimus (rapalog). These studies reported response to tumour size in terms of the number of individuals with a reduction in the total volume of tumours to 50% or more relative to baseline. Significantly more participants in the treatment arm (two studies, 162 participants, high quality evidence) achieved a 50% reduction in renal angiomyolipoma size, risk ratio 24.69 (95% confidence interval 3.51 to 173.41) (P = 0.001). For the sub-ependymal giant cell astrocytoma, our analysis of one study (117 participants, high quality evidence) showed significantly more participants in the treatment arm achieved a 50% reduction in tumour size, risk ratio 27.85 (95% confidence interval 1.74 to 444.82) (P = 0.02). The proportion of participants who showed a skin response from the two included studies analysed was significantly increased in the treatment arms, risk ratio 5.78 (95% confidence interval 2.30 to 14.52) (P = 0.0002) (two studies, 224 participants, high quality evidence). In one study (117 participants), the median change of seizure frequency was -2.9 in 24 hours (95% confidence interval -4.0 to -1.0) in the treatment group versus -4.1 in 24 hour (95% confidence interval -10.9 to 5.8) in the placebo group. In one study, one out of 79 participants in the treatment group versus three of 39 in placebo group had increased blood creatinine levels, while the median percentage change of forced expiratory volume at one second in the treatment arm was -1% compared to -4% in the placebo arm. In one study (117 participants, high quality evidence), we found that those participants who received treatment had a similar risk of experiencing adverse events compared to those who did not, risk ratio 1.07 (95% confidence interval 0.96 - 1.20) (P = 0.24). However, as seen from two studies (235 participants, high quality evidence), the treatment itself led to significantly more adverse events resulting in withdrawal, interruption of treatment, or reduction in dose level, risk ratio 3.14 (95% confidence interval 1.82 to 5.42) (P < 0.0001).One study (28 participants) used topical (skin) administration of rapamycin. This study reported response to skin lesions in terms of participants' perception towards their skin appearance following the treatment. There was a tendency of an improvement in the participants' perception of their skin appearance, although not significant, risk ratio 1.81 (95% confidence interval 0.80 to 4.06, low quality evidence) (P = 0.15). This study reported that there were no serious adverse events related to the study product and there was no detectable systemic absorption of the rapamycin during the study period.

AUTHORS' CONCLUSIONS

We found evidence that oral everolimus significantly increased the proportion of people who achieved a 50% reduction in the size of sub-ependymal giant cell astrocytoma and renal angiomyolipoma. Although we were unable to ascertain the relationship between the reported adverse events and the treatment, participants who received treatment had a similar risk of experiencing adverse events as compared to those who did not receive treatment. Nevertheless, the treatment itself significantly increased the risk of having dose reduction, interruption or withdrawal. This supports ongoing clinical applications of oral everolimus for renal angiomyolipoma and subependymal giant cell astrocytoma. Although oral everolimus showed beneficial effect on skin lesions, topical rapamycin only showed a non-significant tendency of improvement. Efficacy on skin lesions should be further established in future research. The beneficial effects of rapamycin or rapalogs on tuberous sclerosis complex should be further studied on other manifestations of the condition.

Combination targeted therapy of VEGFR inhibitor, sorafenib, with an mTOR inhibitor, sirolimus induced a remakable response of rapid progressive Uterine PEComa

Perivascular epithelioid cell tumor is a rare tumor. To date, there is no consensus of therapy to be recommended for unresectable disease. For a low incidence and a rarely curable disease, the finding of new therapy is essential. Here we report the first case of a patient with perivascular epithelioid cell tumor whose disease had a rapid progression after surgery and had a rapid remarkable response of combination therapy of a VEGFR inhibitor, sorafenib, with an mTOR inhibitor, sirolimus. This result may have potential to deliver a new treatment option and inhibiting the mTOR pathway combined with inhibiting the VEGF pathways may be a useful strategy for malignant PEComas.

Mesenchymal Tumorigenesis Driven by TSC2 Haploinsufficiency Requires HMGA2 and Is Independent of mTOR Pathway Activation

Tuberous sclerosis (TSC) is a tumor suppressor gene syndrome that is associated with the widespread development of mesenchymal tumor types. Genetically, TSC is said to occur through a classical biallelic inactivation of either TSC genes (TSC1, hamartin or TSC2, tuberin), an event that is implicated in the induction of the mTOR pathway and subsequent tumorigenesis. High Mobility Group A2 (HMGA2), an architectural transcription factor, is known to regulate mesenchymal differentiation and drive mesenchymal tumorigenesis in vivo. Here, we investigated the role of HMGA2 in the pathogenesis of TSC using the TSC2(+/-) mouse model that similarly mirrors human disease and human tumor samples. We show that HMGA2 expression was detected in 100% of human and mouse TSC tumors and that HMGA2 activation was required for TSC mesenchymal tumorigenesis in genetically engineered mouse models. In contrast to the current dogma, the mTOR pathway was not activated in all TSC2(+/-) tumors and was elevated in only 50% of human mesenchymal tumors. Moreover, except for a subset of kidney tumors, tuberin was expressed in both human and mouse tumors. Therefore, haploinsufficiency of one TSC tumor suppressor gene was required for tumor initiation, but further tumorigenesis did not require the second hit, as previously postulated. Collectively, these findings demonstrate that tissue-specific genetic mechanisms are employed to promote tumor pathogenesis in TSC and identify a novel, critical pathway for potential therapeutic targeting.

period-Regulated Feeding Behavior and TOR Signaling Modulate Survival of Infection

Most metazoans undergo dynamic, circadian-regulated changes in behavior and physiology. Currently, it is unknown how circadian-regulated behavior impacts immunity against infection. Two broad categories of defense against bacterial infection are resistance, control of microbial growth, and tolerance, control of the pathogenic effects of infection. Our study of behaviorally arrhythmic Drosophila circadian period mutants identified a novel link between nutrient intake and tolerance of infection with B. cepacia, a bacterial pathogen of rising importance in hospital-acquired infections. We found that infection tolerance in wild-type animals is stimulated by acute exposure to dietary glucose and amino acids. Glucose-stimulated tolerance was induced by feeding or direct injection; injections revealed a narrow window for glucose-stimulated tolerance. In contrast, amino acids stimulated tolerance only when ingested. We investigated the role of a known amino-acid-sensing pathway, the TOR (Target of Rapamycin) pathway, in immunity. TORC1 is circadian regulated and inhibition of TORC1 decreased resistance, as in vertebrates. Surprisingly, inhibition of the less well-characterized TOR complex 2 (TORC2) dramatically increased survival, through both resistance and tolerance mechanisms. This work suggests that dietary intake on the day of infection by B. cepacia can make a significant difference in long-term survival. We further demonstrate that TOR signaling mediates both resistance and tolerance of infection and identify TORC2 as a novel potential therapeutic target for increasing survival of infection.

Lymphangioleiomyomatosis: Current understanding and potential treatments

Lymphangioleiomyomatosis (LAM) is a rare neoplastic disease affecting predominantly young women. Clinical symptoms of this progressive disease include dyspnoea, cough, recurrent pneumothorax, hemoptysis and chylothorax. LAM is generally aggressive in nature and ultimately results in respiratory failure. Important hallmark features of this metastatic disease include the formation of lesions of abnormal smooth muscle cells, cystic destruction of the lung tissue and lymphangiogenesis affecting the lungs, abdomen and lymphatics. Research over the last 10-15 years has significantly enhanced our understanding of the molecular and cellular processes associated with LAM. These processes include mutational inactivation of the tuberous sclerosis complex genes, TSC1 and TSC2, activation of the mammalian target of rapamycin (mTOR) pathway, enhanced cell proliferation and migration, lymphangiogenesis, metastatic spread through the blood and lymphatic circulations, sex steroid sensitivity and dysregulated autophagy. Despite this increased knowledge there is currently no cure for LAM and treatment options remain limited. Whilst the mTOR inhibitor rapamycin has shown some benefit in patients with LAM, with stabilisation of lung function and improved quality of life, cessation of treatment results in recurrence of the disease progression. This highlights the urgent need to identify novel targets and new treatment regimens. The focus of this review is to summarise our current understanding of the cellular and molecular processes associated with LAM and highlight emerging treatments.

Lymphangioleiomyomatosis: New Treatment Perspectives

Lymphangioleiomyomatosis (LAM) is a rare multisystem disease, occurs in women, usually premenopausal, caused by the proliferation of neoplastic smooth muscle-derived cells. Mutations in the tuberous sclerosis complex genes, lead to the activation of mammalian target of rapamycin kinase (mTOR), results in proliferation of LAM cells, its increasing motility, and survival. Polycystic lung destruction, extensive involvement of lymphatic channels, chylothorax, chyloperitoneum, and renal angiomyolipomas can develop in LAM patients. The new, promising treatment strategies have been recently introduced due to discovery of the genetic and molecular mechanisms of LAM. Comprehension of the disease pathogenesis has resulted in the implementation of other therapeutic agents such as mTOR inhibitors, VEGF-D inhibitors, statins, interferon, chloroquine analogs, cyclin-dependent kinase inhibitors, matrix metalloproteinase inhibitors, aromatase inhibitors, and their combinations. The mTOR inhibitors appear to be the most important, and the efficacy of sirolimus in LAM treatment has been proved. The article discussed the new control studies with mTOR inhibitors, doxycycline, simvastatin, and combination of them in LAM patients.

Clinical features, epidemiology, and therapy of lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM) is a multisystem disease of women, characterized by proliferation of abnormal smooth muscle-like LAM cells, leading to the formation of lung cysts, fluid-filled cystic structures in the axial lymphatics (eg, lymphangioleiomyomas), and renal angiomyolipomas. LAM is caused by mutations of the TSC1 or TSC2 genes, which encode, respectively, hamartin and tuberin, two proteins with a major role in control of the mammalian target of rapamycin (mTOR) signaling pathway. LAM occurs sporadically or in association with tuberous sclerosis complex, an autosomal-dominant syndrome characterized by widespread hamartomatous lesions. LAM may present with progressive dyspnea, recurrent pneumothorax, or chylothorax. Pulmonary function tests show reduced flow rates (forced expiratory volume in the first second) and diffusion capacity. Exercise testing may reveal gas exchange abnormalities, ventilatory limitation, and hypoxemia. The severity and progression of disease may be assessed by lung histology scores, quantification of computed tomography, pulmonary function testing, 6-minute walk tests, cardiopulmonary exercise testing, and measurement of serum vascular endothelial growth factor D levels. Sirolimus and everolimus, two mTOR inhibitors, are effective in stabilizing lung function and reducing the size of chylous effusions, lymphangioleiomyo-mas, and angiomyolipomas. However, inhibition of mTOR complex 1 increases autophagy, possibly enhancing LAM cell survival. Inhibition of autophagy with hydroxychloroquine, in combination with sirolimus, has been proposed as a possible treatment for LAM. Deficiency of tuberin results in increased RhoA GTPase activity and cell survival, an effect that is mediated through mTOR complex 2 signaling. Because sirolimus and everolimus only affect the activity of mTOR complex 1, therapies targeting RhoA GTPases with simvastatin, which inhibits Rho GTPases and promotes apoptosis, are being investigated. As in the case of cancer, LAM may be best treated with multiple drugs targeting signaling pathways considered important in the pathogenesis of disease.

A vascular model of Tsc1 deficiency accelerates renal tumor formation with accompanying hemangiosarcomas

Tuberous sclerosis complex (TSC) is an autosomal disease caused by inactivating mutations in either of the tumor suppressor genes TSC1 or TSC2. TSC-associated tumor growth is present in multiple tissues and organs including brain, kidney, liver, heart, lungs, and skin. In the kidney, TSC angiomyolipomas have aberrant vascular structures with abnormal endothelial cells, suggesting a role for endothelial mTORC1 function. In the current report, a genetically engineered mouse model (GEMM) with a conditional knockout allele of Tsc1 with a Darpp32-Cre allele displayed accelerated formation of both kidney cystadenomas and paw hemangiosarcomas. All mutant mice developed hemangiosarcomas on multiple paws by 6 weeks of age. By 16 weeks of age, the average mutant hind paw was 4.0 mm in diameter, nearly double the size of control mice. Furthermore, the hemangiosarcomas and kidney cystadenomas were responsive to intraperitoneal rapamycin treatment. Immunoblotting and immunostaining for phospho-S6 (pS6) and phospho-CAD showed that the effect of rapamycin on tumor size was through inhibition of the mTOR signaling pathway. Finally, elevated VEGF mRNA levels were also observed in hemangiosarcoma specimens. Because paw hemangiosarcomas are easily detectable and scorable for size and growth, this novel mouse model enables accelerated in vivo drug testing for therapies of TSC-related tumors.

IMPLICATIONS

These findings provide a strong rationale for simultaneous use of this conditional knockout mouse as an in vivo genetic model while seeking new cancer therapies for TSC-related tumors.

Management of lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM), a multisystem disease affecting almost exclusively women, is characterized by cystic lung destruction and presents with dyspnea, recurrent pneumothoraxes, chylous effusions, lymphangioleiomyomas, and angiomyolipomas. It is caused by the proliferation of a cancer-like LAM cell that possesses a mutation in either the tuberous sclerosis complex (TSC)1 or TSC2 genes. This article reviews current therapies and new potential treatments that are currently undergoing investigation. The major development in the treatment of LAM is the discovery of two mammalian target of rapamycin (mTOR) inhibitors, sirolimus and everolimus, as effective drugs. However, inhibition of mTOR increases autophagy, which may lead to enhanced LAM cell survival. Use of autophagy inhibitors, for example, hydroxychloroquine, in combination with sirolimus is now the subject of an ongoing drug trial (SAIL trial). Another consequence of mTOR inhibition by sirolimus is an increase in Rho activity, resulting in reduced programmed cell death. From these data, the concept evolved that a combination of sirolimus with disruption of Rho activity with statins (e.g. simvastatin) may increase TSC-null cell death and reduce LAM cell survival. A combined trial of sirolimus with simvastatin is under investigation (SOS trial). Since LAM occurs primarily in women and TSC-null cell survival and tumor growth is promoted by estrogens, the inhibition of aromatase to block estrogen synthesis is currently undergoing study (TRAIL trial). Other targets, for example, estrogen receptors, mitogen-activated protein kinase inhibitors, vascular endothelial growth factor-D signaling pathway, and Src kinase, are also being studied in experimental model systems. As in the case of cancer, combination therapy may become the treatment of choice for LAM.

Hospital pharmacists' roles and attitudes in providing information on the safety of non-steroidal anti-inflammatory drugs in Thailand

BACKGROUND

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used for patients to manage pain and inflammation, especially in older adults. Failure to cope with some adverse drug reactions (ADRs) of NSAIDs could lead to more serious symptoms, therefore, providing useful information about medicine is an important step in protecting patients from developing serious ADRs. The pharmacy service should be a frequent source of medicine information for patients, however in Thailand, little is known about pharmacists' provision of safety information to patients for management and prevention of these ADRs.

OBJECTIVE

Aims of this study were to determine Thai hospital pharmacists' roles in providing drug safety information and to assess their attitudes towards the importance of giving drug safety education to patients.

SETTING

All government hospitals in north-eastern Thailand.

METHODS

This study was a cross-sectional survey. A total of 761 pharmacists in 287 hospitals in north-eastern Thailand were selected by stratified random sampling. Self-administered questionnaires were sent by post, with two reminders.

MAIN OUTCOME MEASURES

Proportion of hospital pharmacists providing ADR information on NSAIDs to patients, factors affecting this provision, and pharmacist attitudes towards drug safety education for patients.

RESULTS

The response rate was 54.8% (N = 417), the majority of respondents worked in community hospitals (57.2%). A total of 347 pharmacists (83.6%) had informed patients about ADRs, although less than half had informed patients about ADR monitoring and management (36.6% and 44.1% respectively). The proportion of time spent in direct patient contact, type of hospital, and other routine work were associated with the frequency of drug safety information provision. Pharmacists had moderately good attitudinal scores towards drug safety education (62.2 ± 5.4), with significantly higher scores found in those who provided most ADR information to patients (60.3 ± 5.2 vs. 62.6 ± 5.4, P = 0.002). The majority (82.2%) agreed that patient information leaflets should be provided.

CONCLUSIONS

Thai hospital pharmacists' provision of ADR information for NSAIDs may occur less frequently than is desirable. However, their positive attitude towards provision of ADR information suggests that drug safety education by pharmacists should be routinely provided to patients, particularly patients at high risk of NSAID use.

Therapeutic Strategies for Treatment of Pulmonary Lymphangioleiomyomatosis (LAM)

INTRODUCTION

Pulmonary lymphangioleiomyomatosis (LAM) is a rare progressive lung disease affecting almost exclusively women. Neoplastic growth of atypical smooth muscle-like cells in the lung induces destruction of lung parenchyma leading to the formation of lung cysts, rupture of which results in spontaneous pneumothorax. LAM occurs sporadically or in association with inherited hamartoma syndrome tuberous sclerosis complex (TSC). Progression of LAM often results in loss of pulmonary function and death. Increasing understanding of neoplastic LAM cell growth is driving the development of therapeutic approaches targeting the disease progression.

AREAS COVERED

This review provides background to understand the rationale for current treatments used in patients with LAM, to critically appraise the evidence for these treatments, and to discuss future treatment approaches. The literature review includes publications from PubMed and clinicaltrials.gov/.

EXPERT OPINION

Targeting mTOR activation with rapamycin analogs sirolimus and everolimus are awaiting approval by the FDA for treatment of LAM. A number of other treatment options have been investigated and are currently tested in clinical trials to target LAM cell survival and metastasis. Key remaining and poorly understood areas for development and validation of therapeutic targeting in LAM are destruction of lungs, pathological lymphangiogenesis, and hormonal regulation. Future will reveal whether they could be targeted therapeutically.

Mammalian target of rapamycin complex 1 and cyclooxygenase 2 pathways cooperatively exacerbate endometrial cancer

The underlying causes of endometrial cancer (EMC) are poorly understood, and treatment options for patients with advanced stages of the disease are limited. Mutations in the phosphatase and tensin homologue gene are frequently detected in EMC. Cyclooxygenase 2 (Cox2) and mammalian target of rapamycin complex 1 (mTORC1) are known downstream targets of the phosphatase and tensin homologue protein, and their activities are up-regulated in EMC. However, it is not clear whether Cox2 and mTORC1 are crucial players in cancer progression or whether they work in parallel or cooperatively. In this study, we used a Cox2 inhibitor, celecoxib, and an mTORC1 inhibitor, rapamycin, in mouse models of EMC and in human EMC cell lines to explore the interactive roles of Cox2 and mTORC1 signaling. We found that a combined treatment with celecoxib and rapamycin markedly reduces EMC progression. We also observed that rapamycin reduces Cox2 expression, whereas celecoxib reduces mTORC1 activity. These results suggest that Cox2 and mTORC1 signaling is cross-regulated and cooperatively exacerbate EMC.

Inhibition of mTOR signaling reduces PELP1-mediated tumor growth and therapy resistance

Proline, Glutamic acid-, and Leucine-rich Protein 1 (PELP1) is a proto-oncogene that modulates estrogen receptor (ER) signaling. PELP1 expression is upregulated in breast cancer, contributes to therapy resistance, and is a prognostic marker of poor survival. In a subset of breast tumors, PELP1 is predominantly localized in the cytoplasm and PELP1 participates in extranuclear signaling by facilitating ER interactions with Src and phosphoinositide 3-kinase (PI3K). However, the mechanism by which PELP1 extranuclear actions contributes to cancer progression and therapy resistance remains unclear. In this study, we discovered that PELP1 cross-talked with the serine/threonine protein kinase mTOR and modulated mTOR signaling. PELP1 knockdown significantly reduced the activation of mTOR downstream signaling components. Conversely, PELP1 overexpression excessively activated mTOR signaling components. We detected the presence of the mTOR signaling complex proteins in PELP1 immunoprecipitates. mTOR-targeting drugs (rapamycin and AZD8055) significantly reduced proliferation of PELP1-overexpressed breast cancer cells in both in vitro and in vivo xenograft tumor models. MCF7 cells that uniquely retain PELP1 in the cytoplasm showed resistance to hormonal therapy and mTOR inhibitors sensitized PELP1cyto cells to hormonal therapy in xenograft assays. Notably, immunohistochemical studies using xenograft tumors derived from PELP1 overexpression model cells showed increased mTOR signaling and inhibition of mTOR rendered PELP1-driven tumors to be highly sensitive to therapeutic inhibition. Collectively, our data identified the PELP1-mTOR axis as a novel component of PELP1 oncogenic functions and suggest that mTOR inhibitor(s) will be effective chemotherapeutic agents for downregulating PELP1 oncogenic functions.

mTORC1 inhibition delays growth of neurofibromatosis type 2 schwannoma

BACKGROUND

Neurofibromatosis type 2 (NF2) is a rare autosomal dominant genetic disorder, resulting in a variety of neural tumors, with bilateral vestibular schwannomas as the most frequent manifestation. Recently, merlin, the NF2 tumor suppressor, has been identified as a novel negative regulator of mammalian target of rapamycin complex 1 (mTORC1); functional loss of merlin was shown to result in elevated mTORC1 signaling in NF2-related tumors. Thus, mTORC1 pathway inhibition may be a useful targeted therapeutic approach.

METHODS

We studied in vitro cell models, cohorts of mice allografted with Nf2(-/-) Schwann cells, and a genetically modified mouse model of NF2 schwannoma in order to evaluate the efficacy of the proposed targeted therapy for NF2.

RESULTS

We found that treatment with the mTORC1 inhibitor rapamycin reduced the severity of NF2-related Schwann cell tumorigenesis without significant toxicity. Consistent with these results, in an NF2 patient with growing vestibular schwannomas, the rapalog sirolimus induced tumor growth arrest.

CONCLUSIONS

Taken together, these results constitute definitive evidence that justifies proceeding with clinical trials using mTORC1-targeted agents in selected patients with NF2 and in patients with NF2-related sporadic tumors.

Statins in lymphangioleiomyomatosis. Simvastatin and atorvastatin induce differential effects on tuberous sclerosis complex 2-null cell growth and signaling

Mutations of the tumor suppressor genes tuberous sclerosis complex (TSC)1 and TSC2 cause pulmonary lymphangioleiomyomatosis (LAM) and tuberous sclerosis (TS). Current rapamycin-based therapies for TS and LAM have a predominantly cytostatic effect, and disease progression resumes with therapy cessation. Evidence of RhoA GTPase activation in LAM-derived and human TSC2-null cells suggests that 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor statins can be used as potential adjuvant agents. The goal of this study was to determine which statin (simvastatin or atorvastatin) is more effective in suppressing TSC2-null cell growth and signaling. Simvastatin, but not atorvastatin, showed a concentration-dependent (0.5-10 μM) inhibitory effect on mouse TSC2-null and human LAM-derived cell growth. Treatment with 10 μM simvastatin induced dramatic disruption of TSC2-null cell monolayer and cell rounding; in contrast, few changes were observed in cells treated with the same concentration of atorvastatin. Combined treatment of rapamycin with simvastatin but not with atorvastatin showed a synergistic growth-inhibitory effect on TSC2-null cells. Simvastatin, but not atorvastatin, inhibited the activity of prosurvival serine-threonine kinase Akt and induced marked up-regulation of cleaved caspase-3, a marker of cell apoptosis. Simvastatin, but not atorvastatin, also induced concentration-dependent inhibition of p42/p44 Erk and mTORC1. Thus, our data show growth-inhibitory and proapoptotic effects of simvastatin on TSC2-null cells compared with atorvastatin. These findings have translational significance for combinatorial therapeutic strategies of simvastatin to inhibit TSC2-null cell survival in TS and LAM.

Platelet-derived growth factor/vascular endothelial growth factor receptor inactivation by sunitinib results in Tsc1/Tsc2-dependent inhibition of TORC1

Vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) receptors are implicated in development and tumorigenesis and dual inhibitors like sunitinib are prescribed for cancer treatment. While mammalian VEGF and PDGF receptors are present in multiple isoforms and heterodimers, Drosophila encodes one ancestral PDGF/VEGF receptor, PVR. We identified PVR in an unbiased cell-based RNA interference (RNAi) screen of all Drosophila kinases and phosphatases for novel regulators of TORC1. PVR is essential to sustain target of rapamycin complex 1 (TORC1) and extracellular signal-regulated kinase (ERK) activity in cultured insect cells and for maximal stimulation by insulin. CG32406 (henceforth, PVRAP, for PVR adaptor protein), an Src homology 2 (SH2) domain-containing protein, binds PVR and is required for TORC1 activation. TORC1 activation by PVR involves Tsc1/Tsc2 and, in a cell-type-dependent manner, Lobe (ortholog of PRAS40). PVR is required for cell survival in vitro, and both PVR and TORC1 are necessary for hemocyte expansion in vivo. Constitutive PVR activation induces tumor-like structures that exhibit high TORC1 activity. Like its mammalian orthologs, PVR is inhibited by sunitinib, and sunitinib treatment phenocopies PVR loss in hemocytes. Sunitinib inhibits TORC1 in insect cells, and sunitinib-mediated TORC1 inhibition requires an intact Tsc1/Tsc2 complex. Sunitinib similarly inhibited TORC1 in human endothelial cells in a Tsc1/Tsc2-dependent manner. Our findings provide insight into the mechanism of action of PVR and may have implications for understanding sunitinib sensitivity and resistance in tumors.

Chromatin remodeling by rosuvastatin normalizes TSC2-/meth cell phenotype through the expression of tuberin

Tuberous sclerosis complex (TSC) is a multi-systemic syndrome caused by mutations in TSC1 or TSC2 gene. In TSC2-null cells, Rheb, a member of the Ras family of GTPases, is constitutively activated. Statins inhibit 3-hydroxy-3-methylglutaryl coenzyme A reductase and block the synthesis of isoprenoid lipids with inhibition of Rheb farnesylation and RhoA geranylgeranylation. The effects of rosuvastatin on the function of human TSC2(-/-) and TSC2(-/meth) α-actin smooth muscle (ASM) cells have been investigated. The TSC2(-/-) and TSC2(-/meth) ASM cells, previously isolated in our laboratory from the renal angiomyolipoma of two TSC patients, do not express tuberin and bear loss of heterozigosity caused by a double hit on TSC2 and methylation of TSC2 promoter, respectively. Exposure to rosuvastatin affected TSC2(-/meth) ASM cell growth and promoted tuberin expression by acting as a demethylating agent. This occurred without changes in interleukin release. Rosuvastatin also reduced RhoA activation in TSC2(-/meth) ASM cells, and it required coadministration with the specific mTOR (mammalian target of rapamycin) inhibitor rapamycin to be effective in TSC2(-/-) ASM cells. Rapamycin enhanced rosuvastatin effect in inhibiting cell proliferation in TSC2(-/-) and TSC2(-/meth) ASM cells. Rosuvastatin alone did not alter phosphorylation of S6 and extracellular signal-regulated kinase (ERK), and at the higher concentration, rosuvastatin and rapamycin slightly decreased ERK phosphorylation. These results suggest that rosuvastatin may potentially represent a treatment adjunct to the therapy with mTOR inhibitors now in clinical development for TSC. In particular, rosuvastatin appears useful when the disease is originated by epigenetic defects.

Prevention of alveolar destruction and airspace enlargement in a mouse model of pulmonary lymphangioleiomyomatosis (LAM)

Pulmonary lymphangioleiomyomatosis (LAM) is a rare genetic disease characterized by neoplastic growth of atypical smooth muscle-like LAM cells, destruction of lung parenchyma, obstruction of lymphatics, and formation of lung cysts, leading to spontaneous pneumothoraces (lung rupture and collapse) and progressive loss of pulmonary function. The disease is caused by mutational inactivation of the tumor suppressor gene tuberous sclerosis complex 1 (TSC1) or TSC2. By injecting TSC2-null cells into nude mice, we have developed a mouse model of LAM that is characterized by multiple random TSC2-null lung lesions, vascular endothelial growth factor-D expression, lymphangiogenesis, destruction of lung parenchyma, and decreased survival, similar to human LAM. The mice show enlargement of alveolar airspaces that is associated with progressive growth of TSC2-null lesions in the lung, up-regulation of proinflammatory cytokines and matrix metalloproteinases (MMPs) that degrade extracellular matrix, and destruction of elastic fibers. TSC2-null lesions and alveolar destruction were differentially inhibited by the macrolide antibiotic rapamycin (which inhibits TSC2-null lesion growth by a cytostatic mechanism) and a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, simvastatin (which inhibits growth of TSC2-null lesions by a predominantly proapoptotic mechanism). Treatment with simvastatin markedly inhibited MMP-2, MMP-3, and MMP-9 levels in lung and prevented alveolar destruction. The combination of rapamycin and simvastatin prevented both growth of TSC2-null lesions and lung destruction by inhibiting MMP-2, MMP-3, and MMP-9. Our findings demonstrate a mechanistic link between loss of TSC2 and alveolar destruction and suggest that treatment with rapamycin and simvastatin together could benefit patients with LAM by targeting cells with TSC2 dysfunction and preventing airspace enlargement.

mTOR Inhibition: From Aging to Autism and Beyond

The mechanistic target of rapamycin (mTOR) is a highly conserved protein that regulates growth and proliferation in response to environmental and hormonal cues. Broadly speaking, organisms are constantly faced with the challenge of interpreting their environment and making a decision between "grow or do not grow." mTOR is a major component of the network that makes this decision at the cellular level and, to some extent, the tissue and organismal level as well. Although overly simplistic, this framework can be useful when considering the myriad functions ascribed to mTOR and the pleiotropic phenotypes associated with genetic or pharmacological modulation of mTOR signaling. In this review, I will consider mTOR function in this context and attempt to summarize and interpret the growing body of literature demonstrating interesting and varied effects of mTOR inhibitors. These include robust effects on a multitude of age-related parameters and pathologies, as well as several other processes not obviously linked to aging or age-related disease.

Targeting LKB1 signaling in cancer

The serine/threonine kinase LKB1 is a master kinase involved in cellular responses such as energy metabolism, cell polarity and cell growth. LKB1 regulates these crucial cellular responses mainly via AMPK/mTOR signaling. Germ-line mutations in LKB1 are associated with the predisposition of the Peutz-Jeghers syndrome in which patients develop gastrointestinal hamartomas and have an enormously increased risk for developing gastrointestinal, breast and gynecological cancers. In addition, somatic inactivation of LKB1 has been associated with sporadic cancers such as lung cancer. The exact mechanisms of LKB1-mediated tumor suppression remain so far unidentified; however, the inability to activate AMPK and the resulting mTOR hyperactivation has been detected in PJS-associated lesions. Therefore, targeting LKB1 in cancer is now mainly focusing on the activation of AMPK and inactivation of mTOR. Preclinical in vitro and in vivo studies show encouraging results regarding these approaches, which have even progressed to the initiation of a few clinical trials. In this review, we describe the functions, regulation and downstream signaling of LKB1, and its role in hereditary and sporadic cancers. In addition, we provide an overview of several AMPK activators, mTOR inhibitors and additional mechanisms to target LKB1 signaling, and describe the effect of these compounds on cancer cells. Overall, we will explain the current strategies attempting to find a way of treating LKB1-associated cancer.

Targeted approaches toward understanding and treating pulmonary lymphangioleiomyomatosis (LAM)

Pulmonary lymphangioleiomyomatosis (LAM) is a rare disease found almost exclusively in women that is characterized by neoplastic growth of atypical smooth muscle-like cells in the lung, destruction of lung parenchyma, and obstruction of lymphatics. These processes lead to the formation of lung cysts, rupture of which results in spontaneous pneumothorax. Progression of LAM often results in loss of pulmonary function and death. LAM affects predominantly women of childbearing age and is exacerbated by pregnancy. The only proven treatment for LAM is lung transplantation, and even then LAM cells will often return to the transplanted lung. However, methodical and targeted approaches toward understanding LAM pathophysiology have led to the discovery of new potential therapeutic avenues. For example, the mutational inactivation of tumor suppressor complex genes tuberous sclerosis complex 1 or tuberous sclerosis complex 2 has been shown to be present in lung LAM cells. These mutations occur sporadically or in association with inherited hamartoma syndrome tuberous sclerosis (TSC). Since TSC genes function as negative regulators of the mammalian target of rapamycin, a major controller of cell growth, metabolism, and survival, rapamycin analogs have recently been used to treat LAM patients with promising results. Similarly, studies focusing on the importance of estrogen in LAM progression have suggested that anti-estrogen therapy might prove to be an alternative means of treating LAM. This minireview summarizes recent progress in understanding LAM pathophysiology, including the latest preclinical and clinical studies, and insights regarding the role of hormones in LAM.

Low-dose rapamycin treatment increases the ability of human regulatory T cells to inhibit transplant arteriosclerosis in vivo

Regulatory T cells (T(reg)) are currently being tested in clinical trials as a potential therapy in cell and solid organ transplantation. The immunosuppressive drug rapamycin has been shown to preferentially promote T(reg) expansion. Here, we hypothesized that adjunctive rapamycin therapy might potentiate the ability of ex vivo expanded human T(reg) to inhibit vascular allograft rejection in a humanized mouse model of arterial transplantation. We studied the influence of combined treatment with low-dose rapamycin and subtherapeutic T(reg) numbers on the development of transplant arteriosclerosis (TA) in human arterial grafts transplanted into immunodeficient BALB/cRag2(-/-) Il2rg(-/-) mice reconstituted with allogeneic human peripheral blood mononuclear cell. In addition, we assessed the effects of the treatment on the proliferation and apoptosis of naïve/effector T cells. The combined therapy efficiently suppressed T-cell proliferation in vivo and in vitro. Neointima formation in the human arterial allografts was potently inhibited compared with each treatment alone. Interestingly, CD4(+) but not CD8(+) T lymphocytes were sensitive to T(reg) and rapamycin-induced apoptosis in vitro. Our data support the concept that rapamycin can be used as an adjunctive therapy to improve efficacy of T(reg)-based immunosuppressive protocols in clinical practice. By inhibiting TA, T(reg) and rapamycin may prevent chronic transplant dysfunction and improve long-term allograft survival.

Optimizing treatments for lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM), a multisystem disease predominantly affecting premenopausal women, is associated with cystic lung destruction and lymphatic and kidney tumors. LAM results from the proliferation of a neoplastic cell that has mutations in the tuberous sclerosis complex 1 or 2 genes, leading to activation of a critical regulatory protein, mammalian target of rapamycin. In this report, we discuss the molecular mechanisms regulating LAM cell growth and report the results of therapeutic trials employing new targeted agents. At present, inhibitors of mammalian target of rapamycin such as sirolimus appear to be the most promising therapeutic agents, although drug toxicity and development of resistance are potential problems. As the pathogenesis of LAM is being further recognized, other therapeutic agents such as matrix metalloproteinase inhibitors, statins, interferon, VEGF inhibitors, chloroquine analogs and cyclin-dependent kinase inhibitors, along with sirolimus or a combination of several of these agents, may offer the best hope for effective therapy.

Low-dose rapamycin treatment increases the ability of human regulatory T cells to inhibit transplant arteriosclerosis in vivo

Regulatory T cells (T(reg)) are currently being tested in clinical trials as a potential therapy in cell and solid organ transplantation. The immunosuppressive drug rapamycin has been shown to preferentially promote T(reg) expansion. Here, we hypothesized that adjunctive rapamycin therapy might potentiate the ability of ex vivo expanded human T(reg) to inhibit vascular allograft rejection in a humanized mouse model of arterial transplantation. We studied the influence of combined treatment with low-dose rapamycin and subtherapeutic T(reg) numbers on the development of transplant arteriosclerosis (TA) in human arterial grafts transplanted into immunodeficient BALB/cRag2(-/-) Il2rg(-/-) mice reconstituted with allogeneic human peripheral blood mononuclear cell. In addition, we assessed the effects of the treatment on the proliferation and apoptosis of naïve/effector T cells. The combined therapy efficiently suppressed T-cell proliferation in vivo and in vitro. Neointima formation in the human arterial allografts was potently inhibited compared with each treatment alone. Interestingly, CD4(+) but not CD8(+) T lymphocytes were sensitive to T(reg) and rapamycin-induced apoptosis in vitro. Our data support the concept that rapamycin can be used as an adjunctive therapy to improve efficacy of T(reg)-based immunosuppressive protocols in clinical practice. By inhibiting TA, T(reg) and rapamycin may prevent chronic transplant dysfunction and improve long-term allograft survival.

Remarkable inhibition of mTOR signaling by the combination of rapamycin and 1,4-phenylenebis(methylene)selenocyanate in human prostate cancer cells

Preclinical studies and clinical analyses have implicated the mammalian target of rapamycin (mTOR) pathway in the progression of prostate cancer, suggesting mTOR as a potential target for new therapies. mTOR, a serine/threonine kinase, belongs to two distinct signaling complexes: mTORC1 and mTORC2. We previously showed that the synthetic organoselenium compound, p-XSC, effectively inhibits viability and critical signaling molecules (e.g., androgen receptor, Akt) in androgen responsive (AR) and androgen independent (AI) human prostate cancer cells. On the basis of its inhibition of Akt, we hypothesized that p-XSC modulates mTORC2, an upstream regulator of the kinase. We further hypothesized that combining p-XSC with rapamycin, an mTORC1 inhibitor, would be an effective combinatory strategy for the inhibition of prostate cancer. The effects of p-XSC and rapamycin, alone or in combination, on viability and mTOR signaling were examined in AR LNCaP prostate cancer cells and AI C4-2 and DU145 cells. Phosphorylation of downstream targets of mTORC1 and mTORC2 was analyzed by immunoblotting. The interaction of mTORC1- and mTORC2-specific proteins with mTOR was probed through immunoprecipitation and immunoblotting. p-XSC inhibited phosphorylation of mTORC2 downstream targets, Akt and PCKα, and decreased the levels of rictor, an mTORC2-specific protein, coimmunoprecipitated with mTOR in C4-2 cells. The combination of p-XSC and rapamycin more effectively inhibited viability and mTOR signaling in C4-2, LNCaP and DU145 cells than either agent individually.

Frontier of epilepsy research - mTOR signaling pathway

Studies of epilepsy have mainly focused on the membrane proteins that control neuronal excitability. Recently, attention has been shifting to intracellular proteins and their interactions, signaling cascades and feedback regulation as they relate to epilepsy. The mTOR (mammalian target of rapamycin) signal transduction pathway, especially, has been suggested to play an important role in this regard. These pathways are involved in major physiological processes as well as in numerous pathological conditions. Here, involvement of the mTOR pathway in epilepsy will be reviewed by presenting; an overview of the pathway, a brief description of key signaling molecules, a summary of independent reports and possible implications of abnormalities of those molecules in epilepsy, a discussion of the lack of experimental data, and questions raised for the understanding its epileptogenic mechanism.

Multicenter phase 2 trial of sirolimus for tuberous sclerosis: kidney angiomyolipomas and other tumors regress and VEGF- D levels decrease

BACKGROUND

Tuberous sclerosis (TSC) related tumors are characterized by constitutively activated mTOR signaling due to mutations in TSC1 or TSC2.

METHODS

We completed a phase 2 multicenter trial to evaluate the efficacy and tolerability of the mTOR inhibitor, sirolimus, for the treatment of kidney angiomyolipomas.

RESULTS

36 adults with TSC or TSC/LAM were enrolled and started on daily sirolimus. The overall response rate was 44.4% (95% confidence intervals [CI] 28 to 61); 16/36 had a partial response. The remainder had stable disease (47.2%, 17/36), or were unevaluable (8.3%, 3/36). The mean decrease in kidney tumor size (sum of the longest diameters [sum LD]) was 29.9% (95% CI, 22 to 37; n = 28 at week 52). Drug related grade 1-2 toxicities that occurred with a frequency of >20% included: stomatitis, hypertriglyceridemia, hypercholesterolemia, bone marrow suppression (anemia, mild neutropenia, leucopenia), proteinuria, and joint pain. There were three drug related grade 3 events: lymphopenia, headache, weight gain. Kidney angiomyolipomas regrew when sirolimus was discontinued but responses tended to persist if treatment was continued after week 52. We observed regression of brain tumors (SEGAs) in 7/11 cases (26% mean decrease in diameter), regression of liver angiomyolipomas in 4/5 cases (32.1% mean decrease in longest diameter), subjective improvement in facial angiofibromas in 57%, and stable lung function in women with TSC/LAM (n = 15). A correlative biomarker study showed that serum VEGF-D levels are elevated at baseline, decrease with sirolimus treatment, and correlate with kidney angiomyolipoma size (Spearman correlation coefficient 0.54, p = 0.001, at baseline).

CONCLUSIONS

Sirolimus treatment for 52 weeks induced regression of kidney angiomyolipomas, SEGAs, and liver angiomyolipomas. Serum VEGF-D may be a useful biomarker for monitoring kidney angiomyolipoma size. Future studies are needed to determine benefits and risks of longer duration treatment in adults and children with TSC.

TRIAL REGISTRATION

Clinicaltrials.gov NCT00126672.

The management of subependymal giant cell tumors in tuberous sclerosis: a clinician's perspective

BACKGROUND

Tuberous sclerosis (TSC) is a genetic multisystem disorder associated with hamartomas in several organs including subependymal giant cell tumors (SGCT). SGCT have the potential to grow and therefore to become symptomatic and are one of the main causes of death in TSC individuals. Surgical resection is the procedure of choice for SGCT. However, the discovery of mTOR pathway upregulation in TSC-associated tumors and recent evidence that mTOR inhibitors may induce regression of SGCT open up new treatment strategies. Based on a review of the currently available literature and on personal experience, current options for the management of TSC patients and appropriate indications, taking into account benefits and risks of surgery and pharmacotherapy, are discussed.

DISCUSSION

An earlier diagnosis of SGCT in neurologically asymptomatic children may allow a precocious surgical removal of the tumor, thus minimizing surgery-related morbidity and mortality. Biologically targeted pharmacotherapy with mTOR inhibitors such as sirolimus and everolimus provides a safe and efficacious treatment option for patients with SGCT and has the potential to change the clinical management of these tumors. However, whether pharmacotherapy is sufficient to control growth or if it only delays the need for surgical removal of symptomatic SGCT remains unclear. Further studies are needed to determine the optimal levels of mTOR inhibitors that preserve maximal anti-tumor efficacy while minimizing side effects.

Mammalian target of rapamycin inhibitors for treatment in tuberous sclerosis

Tuberous sclerosis complex (TSC) is a genetic multisystem disorder that results from mutations in the TSC1 or TSC2 genes, and is associated with hamartomas in several organs, including subependymal giant cell tumors. The neurological manifestations of TSC are particularly challenging and include infantile spasms, intractable epilepsy, cognitive disabilities, and autism. The TSC1- and TSC2-encoded proteins modulate cell function via the mammalian target of rapamycin (mTOR) signaling cascade, and are key factors in the regulation of cell growth and proliferation. The mTOR pathway provides an intersection for an intricate network of protein cascades that respond to cellular nutrition, energy levels, and growth factor stimulation. In the brain, TSC1 and TSC2 have been implicated in cell body size, dendritic arborization, axonal outgrowth and targeting, neuronal migration, cortical lamination, and spine formation. The mTOR pathway represents a logical candidate for drug targeting, because mTOR regulates multiple cellular functions that may contribute to epileptogenesis, including protein synthesis, cell growth and proliferation, and synaptic plasticity. Antagonism of the mTOR pathway with rapamycin and related compounds may provide new therapeutic options for TSC patients.

Mechanisms of neurocognitive dysfunction and therapeutic considerations in tuberous sclerosis complex

PURPOSE OF REVIEW

Mendelian disorders that affect cognition provide a unique opportunity to study the mechanisms of neurodevelopmental disorders through the examination of genetic defects in animals and development of hypotheses that can be tested in human beings. Tuberous sclerosis complex (TSC) is a genetic disease that presents with epilepsy, autism, and intellectual disability. Here we review recent advances in our understanding of TSC pathogenesis and signaling pathways that may be modulated to treat the neurological symptoms.

RECENT FINDINGS

Accumulating evidence suggests that TSC patients have nontuber abnormalities that contribute to the development of the neurological phenotype- in particular, disorganization of axon tracts and deficient myelination. TSC mouse models have failed to replicate the human neuropathology entirely, but have shed light on the cellular abnormalities and the neurobehavioral phenotypes. Most importantly, cell culture and animal models have identified the mTORC1 pathway as a therapeutic target in this disease.

SUMMARY

Preclinical data strongly suggest that TSC is a disease of abnormal neuronal connectivity. The high incidence of neurodevelopmental deficits, early detection of the disease in very young ages, and availability of mTORC1 inhibitors make TSC a model for other Mendelian disorders of neurocognition and an avenue for the mechanism-based treatment trials of neurodevelopmental disorders.

Targeting the Mammalian Target of Rapamycin (mTOR) in Cancer Therapy: Lessons from Past and Future Perspectives

Over the last decade, extensive studies have been made to understand the role played by the mammalian target of rapamycin (mTOR) in cancer. Knowledge in this field has been gained from discoveries in basic research as well as from observations made in patients treated with allosteric mTOR inhibitors such as rapamycin. Despite promising preclinical studies, targeting mTOR in cancer therapy has shown limited clinical benefits so far. However, recent findings have revealed the complexity of the functions of mTOR in cancer and have helped develop new strategies to improve the anticancer efficacy of mTOR inhibitors. In particular, a complex network between mTOR and other signaling pathways has been identified that influences the anticancer efficacy of mTOR inhibitors. In addition, an emerging role of mTOR in the tumor microenvironment has been suggested. In this review, we confront the major findings that have been made in the past, both in experimental settings as well as in clinical trials. We further review the strategies that have been designed to further improve the efficacy of therapies targeting mTOR.

mTORC2 is required for proliferation and survival of TSC2-null cells

Mutational inactivation of the tumor suppressor tuberous sclerosis complex 2 (TSC2) constitutively activates mTORC1, increases cell proliferation, and induces the pathological manifestations observed in tuberous sclerosis (TS) and in pulmonary lymphangioleiomyomatosis (LAM). While the role of mTORC1 in TSC2-dependent growth has been extensively characterized, little is known about the role of mTORC2. Our data demonstrate that mTORC2 modulates TSC2-null cell proliferation and survival through RhoA GTPase and Bcl2 proteins. TSC2-null cell proliferation was inhibited not only by reexpression of TSC2 or small interfering RNA (siRNA)-induced downregulation of Rheb, mTOR, or raptor, but also by siRNA for rictor. Increased RhoA GTPase activity and P-Ser473 Akt were inhibited by siRNA for rictor. Importantly, constitutively active V14RhoA reversed growth inhibition induced by siRNA for rictor, siRNA TSC1, reexpression of TSC2, or simvastatin. While siRNA for RhoA had a modest effect on growth inhibition, downregulation of RhoA markedly increased TSC2-null cell apoptosis. Inhibition of RhoA activity downregulated antiapoptotic Bcl2 and upregulated proapoptotic Bim, Bok, and Puma. In vitro and in vivo, simvastatin alone or in combination with rapamycin inhibited cell growth and induced TSC2-null cell apoptosis, abrogated TSC2-null tumor growth, improved animal survival, and prevented tumor recurrence by inhibiting cell growth and promoting apoptosis. Our data demonstrate that mTORC2-dependent activation of RhoA is required for TSC2-null cell growth and survival and suggest that targeting both mTORC2 and mTORC1 by a combination of proapoptotic simvastatin and cytostatic rapamycin shows promise for combinational therapeutic intervention in diseases with TSC2 dysfunction.

Rapamycin reverses hypertrophic cardiomyopathy in a mouse model of LEOPARD syndrome-associated PTPN11 mutation

LEOPARD syndrome (LS) is an autosomal dominant "RASopathy" that manifests with congenital heart disease. Nearly all cases of LS are caused by catalytically inactivating mutations in the protein tyrosine phosphatase (PTP), non-receptor type 11 (PTPN11) gene that encodes the SH2 domain-containing PTP-2 (SHP2). RASopathies typically affect components of the RAS/MAPK pathway, yet it remains unclear how PTPN11 mutations alter cellular signaling to produce LS phenotypes. We therefore generated knockin mice harboring the Ptpn11 mutation Y279C, one of the most common LS alleles. Ptpn11(Y279C/+) (LS/+) mice recapitulated the human disorder, with short stature, craniofacial dysmorphia, and morphologic, histologic, echocardiographic, and molecular evidence of hypertrophic cardiomyopathy (HCM). Heart and/or cardiomyocyte lysates from LS/+ mice showed enhanced binding of Shp2 to Irs1, decreased Shp2 catalytic activity, and abrogated agonist-evoked Erk/Mapk signaling. LS/+ mice also exhibited increased basal and agonist-induced Akt and mTor activity. The cardiac defects in LS/+ mice were completely reversed by treatment with rapamycin, an inhibitor of mTOR. Our results demonstrate that LS mutations have dominant-negative effects in vivo, identify enhanced mTOR activity as critical for causing LS-associated HCM, and suggest that TOR inhibitors be considered for treatment of HCM in LS patients.

Sorafenib: rays of hope in thyroid cancer

BACKGROUND

Sorafenib (BAY 43-9006) is an inhibitor of multiple-receptor tyrosine kinases involved in tumor growth and angiogenesis, which can be advantageously administered orally. Initially used as monotherapy in advanced renal cell carcinoma, sorafenib was proven to increase progression-free survival while enhancing disease control. Clinical trials on sorafenib are at present ongoing for the treatment of various malignancies, including thyroid cancer (TC).

SUMMARY

Specifically, in two phase II studies recently conducted on papillary TC, although the respective results were not entirely compatible as regard partial response rate and progression-free survival, sorafenib demonstrated a relatively favorable benefit/risk profile. In another more recent phase II study, whose primary endpoint was the reinduction of radioactive iodine uptake at 26 weeks, although no reinduction of radioactive iodine uptake was observed, 59% had a beneficial response and 34% had stable disease. Sorafenib hence appears to be a valid alternative to conventional treatment of metastatic papillary TC refractory to radioiodine therapy.

CONCLUSIONS

Further prospective investigations are required to define the characteristics of tumor response to the drug and the factors inducing resistance to treatment. A major issue demanding immediate attention involves optimization of sorafenib treatment: this concerns multidrug combination with different tyrosine kinase inhibitors or immunomodulating agents with the aim of reducing doses and thereby improving drug tolerability and antineoplastic capability.

Rapamycin as an alternative to surgical treatment of subependymal giant cell astrocytomas in a patient with tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is associated with the potential development of benign hamartomas, including subependymal giant cell astrocytomas (SEGAs). Intracranial hypertension can be caused by SEGAs due to their propensity to block the foramen of Monro. The traditional management approach is to monitor SEGAs with periodic neuroimaging and to resect those that exhibit serial growth and/or cause clinical signs of intracranial hypertension. Recent observations suggest that rapamycin therapy may induce partial regression of SEGAs, therefore providing a potential alternative to resection. The authors present the case of an 8-year-old girl with bilateral SEGAs that led to progressive hydrocephaly and incipient signs of papilledema. Three months after initiating rapamycin therapy, the SEGAs exhibited significant reduction in size (82.6% on the left and 46.7% on the right), and the lesions remained stable 5 months later. Compared with previous case reports, similar or even greater antitumor efficacy was achieved with much lower trough levels of rapamycin (10&#x2013;15 compared with 3.3&#x2013;4.5 ng/ml, respectively). The authors discuss various aspects of rapamycin therapy and address unresolved issues that highlight the need for further prospective clinical trials.

Effect of doxycycline on proliferation, MMP production, and adhesion in LAM-related cells

Matrix metalloproteinases (MMPs) have been implicated in lung cyst formation in lymphangioleiomyomatosis (LAM). As doxycycline inhibits MMP activity in vivo, some patients take doxycycline, as one report has suggested a possible benefit in LAM. However, there have been no randomized controlled clinical trials of doxycycline for LAM, and any mechanism of action is unclear. Here, we examine previously proposed mechanisms of actions. Cell proliferation and adhesion were examined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction and Cytomatrix cell adhesion kits. Apoptosis was examined by TdT-mediated dUTP nick end labeling (TUNEL) assay. MMP-2 expression was examined by quantitative real-time PCR and zymography in doxycycline-treated ELT3 cells and tumor growth using angiomyolipoma-derived tumor xenografts in nude mice. In ELT3 cells, >or=25 microg/ml doxycycline decreased proliferation, increased apoptosis, and caused a change in cell morphology associated with redistribution of actin stress filaments. Reduction in proliferation was also seen in human angiomyolipoma-derived cells. Cell adhesion to ECM proteins was decreased by doxycycline at 50 microg/ml and prevented detachment of already adherent cells. There was no effect of doxycycline on MMP-2 expression or activity in vitro. In the xenograft model, doxycycline (30 mg*kg(-1)*day(-1)) had no effect on tumor growth, final tumor weight, or tumor lysate MMP levels. Doxycycline at doses >or= 25 microg/ml inhibited cell proliferation and adhesion, possibly by a toxic effect. Doxycycline had no effect on MMP-2 expression or activity or tumor growth in the xenograft model. Any possible in vivo effect is unlikely to be mediated by MMP-2 or reduced cell proliferation.