Diagnosis of Mosaic Tuberous Sclerosis Complex Using Next-Generation Sequencing of Subtle or Unusual Cutaneous Findings

Skin findings can be critical to determining whether a patient with lymphangioleiomyomatosis (LAM), a progressive pulmonary disease that predominantly affects adult women, has sporadic LAM or LAM in association with tuberous sclerosis complex (TSC). Three individuals with LAM underwent evaluation for TSC-associated mucocutaneous and internal findings. We used our previously published algorithm to confirm the clinical suspicion for mosaicism and guide the selection of tissue specimens and genetic workup. Next-generation sequencing of cutaneous findings was used to confirm clinical suspicion for mosaic TSC in individuals with LAM. Two individuals previously thought to have sporadic LAM were diagnosed with mosaic TSC-associated LAM upon next-generation sequencing of unilateral angiofibromas in one and an unusual cutaneous hamartoma in the other. A third individual, diagnosed with TSC in childhood, was found to have a mosaic pathogenic variant in TSC2 in cutaneous tissue from a digit with macrodactyly. Accurate diagnosis of mosaic TSC-associated LAM may require enhanced genetic testing and is important because of the implications regarding surveillance, prognosis, and risk of transmission to offspring.

A Dramatic Response to Sirolimus Therapy in a Premature Infant With Massive Cardiac Rhabdomyoma

Cardiac rhabdomyomas in neonates may cause significant cardiac risk. Recently, sirolimus has been used to treat these lesions. The dose, duration, and monitoring for therapy are unknown. A case of sirolimus use in a premature neonate is presented. No significant adverse effects were seen. Review of published cases is included. (Level of Difficulty: Advanced.)

Pneumothorax caused by cystic and nodular lung metastases from a malignant uterine perivascular epithelioid cell tumor (PEComa)

Perivascular epithelioid cell tumors (PEComas) are mesenchymal neoplasms with immunoreactivity for both melanocytic and smooth muscle markers. PEComas occur at multiple sites, and malignant PEComas can undergo metastasis, recurrence and aggressive clinical courses. Although the lung is a common metastatic site of PEComas, they usually appear as multiple nodules but rarely become cystic or cavitary. Here, we describe a female patient whose lungs manifested multiple cystic, cavity-like and nodular metastases 3 years after the resection of uterine tumors tentatively diagnosed as epithelioid smooth muscle tumors with uncertain malignant potential. This patient's subsequent pneumothorax necessitated video-assisted thoracoscopic surgery, and examination of her resected lung specimens eventually led to correcting the diagnosis, i.e., to a PEComa harboring tuberous sclerosis complex 1 (TSC1) loss-of-heterozygosity that originated in the uterus and then metastasized to the lungs. The administration of a gonadotropin-releasing hormone analogue later stabilized her clinical course. To the best of our knowledge, the present case is the first in the literature that associates PEComas with a TSC1 abnormality. Additionally, the pulmonary manifestations, including imaging appearance and pneumothorax, somewhat resembled those of lymphangioleiomyomatosis, a representative disease belonging to the PEComa family. Although PEComas are rare, clinicians, radiologists and pathologists should become aware of this disease entity, especially in the combined clinical setting of multiple cystic, cavity-like, nodular lesions on computed tomography of the chest and a past history of the tumor in the female reproductive system.

Efficacy of Everolimus for Treating Renal Angiomyolipoma with Inferior Vena Cava Thrombus Associated with Tuberous Sclerosis: A Case Report

Here we report a case of 57-year-old woman with renal angiomyolipoma associated with tuberous sclerosis complex involving inferior vena cava thrombus. We could perform less invasive nephrectomy with thrombectomy because everolimus administration reduced the inferior vena cava thrombus. To the best of our knowledge, this is the first report the use of everolimus before performing surgery to treat renal angiomyolipoma with inferior vena cava thrombus.

Intestinal Epithelial-Specific mTORC1 Activation Enhances Intestinal Adaptation After Small Bowel Resection

BACKGROUND & AIMS

Intestinal adaptation is a compensatory response to the massive loss of small intestine after surgical resection. We investigated the role of intestinal epithelial cell-specific mammalian target of rapamycin complex 1 (i-mTORC1) in intestinal adaptation after massive small bowel resection (SBR).

METHODS

We performed 50% proximal SBR on mice to study adaptation. To manipulate i-mTORC1 activity, Villin-Cre^ER transgenic mice were crossed with tuberous sclerosis complex (TSC)1^flox/flox or Raptor^flox/flox mice to inducibly activate or inactivate i-mTORC1 activity with tamoxifen. Western blot was used to confirm the activity of mTORC1. Crypt depth and villus height were measured to score adaptation. Immunohistochemistry was used to investigate differentiation and rates of crypt proliferation.

RESULTS

After SBR, mice treated with systemic rapamycin showed diminished structural adaptation, blunted crypt cell proliferation, and significant body weight loss. Activating i-mTORC1 via TSC1 deletion induced larger hyperproliferative crypts and disorganized Paneth cells without a significant change in villus height. After SBR, ablating TSC1 in intestinal epithelium induced a robust villus growth with much stronger crypt cell proliferation, but similar body weight recovery. Acute inactivation of i-mTORC1 through deletion of Raptor did not change crypt cell proliferation or mucosa structure, but significantly reduced lysozyme/matrix metalloproteinase-7-positive Paneth cell and goblet cell numbers, with increased enteroendocrine cells. Surprisingly, ablation of intestinal epithelial cell-specific Raptor after SBR did not affect adaptation or crypt proliferation, but dramatically reduced body weight recovery after surgery.

CONCLUSIONS

Systemic, but not intestinal-specific, mTORC1 is important for normal adaptation responses to SBR. Although not required, forced enterocyte mTORC1 signaling after resection causes an enhanced adaptive response.

Transcriptional and epigenetic regulation of autophagy in aging

Macroautophagy is a major intracellular degradation process recognized as playing a central role in cell survival and longevity. This multistep process is extensively regulated at several levels, including post-translationally through the action of conserved longevity factors such as the nutrient sensor TOR. More recently, transcriptional regulation of autophagy genes has emerged as an important mechanism for ensuring the somatic maintenance and homeostasis necessary for a long life span. Autophagy is increased in many long-lived model organisms and contributes significantly to their longevity. In turn, conserved transcription factors, particularly the helix-loop-helix transcription factor TFEB and the forkhead transcription factor FOXO, control the expression of many autophagy-related genes and are important for life-span extension. In this review, we discuss recent progress in understanding the contribution of these transcription factors to macroautophagy regulation in the context of aging. We also review current research on epigenetic changes, such as histone modification by the deacetylase SIRT1, that influence autophagy-related gene expression and additionally affect aging. Understanding the molecular regulation of macroautophagy in relation to aging may offer new avenues for the treatment of age-related diseases.

Binding of the pathogen receptor HSP90AA1 to avibirnavirus VP2 induces autophagy by inactivating the AKT-MTOR pathway

Autophagy is an essential component of host innate and adaptive immunity. Viruses have developed diverse strategies for evading or utilizing autophagy for survival. The response of the autophagy pathways to virus invasion is poorly documented. Here, we report on the induction of autophagy initiated by the pathogen receptor HSP90AA1 (heat shock protein 90 kDa α [cytosolic], class A member 1) via the AKT-MTOR (mechanistic target of rapamycin)-dependent pathway. Transmission electron microscopy and confocal microscopy revealed that intracellular autolysosomes packaged avibirnavirus particles. Autophagy detection showed that early avibirnavirus infection not only increased the amount of light chain 3 (LC3)-II, but also upregulated AKT-MTOR dephosphorylation. HSP90AA1-AKT-MTOR knockdown by RNA interference resulted in inhibition of autophagy during avibirnavirus infection. Virus titer assays further verified that autophagy inhibition, but not induction, enhanced avibirnavirus replication. Subsequently, we found that HSP90AA1 binding to the viral protein VP2 resulted in induction of autophagy and AKT-MTOR pathway inactivation. Collectively, our findings suggest that the cell surface protein HSP90AA1, an avibirnavirus-binding receptor, induces autophagy through the HSP90AA1-AKT-MTOR pathway in early infection. We reveal that upon viral recognition, a direct connection between HSP90AA1 and the AKT-MTOR pathway trigger autophagy, a critical step for controlling infection.

Critical role of CAV1/caveolin-1 in cell stress responses in human breast cancer cells via modulation of lysosomal function and autophagy

CAV1 (caveolin 1, caveolae protein, 22kDa) is well known as a principal scaffolding protein of caveolae, a specialized plasma membrane structure. Relatively, the caveolae-independent function of CAV1 is less studied. Autophagy is a process known to involve various membrane structures, including autophagosomes, lysosomes, and autolysosomes for degradation of intracellular proteins and organelles. Currently, the function of CAV1 in autophagy remains largely elusive. In this study, we demonstrate for the first time that CAV1 deficiency promotes both basal and inducible autophagy. Interestingly, the promoting effect was found mainly in the late stage of autophagy via enhancing lysosomal function and autophagosome-lysosome fusion. Notably, the regulatory function of CAV1 in lysosome and autophagy was found to be caveolae-independent, and acts through lipid rafts. Furthermore, the elevated autophagy level induced by CAV1 deficiency serves as a cell survival mechanism under starvation. Importantly, downregulation of CAV1 and enhanced autophagy level were observed in human breast cancer cells and tissues. Taken together, our data reveal a novel function of CAV1 and lipid rafts in breast cancer development via modulation of lysosomal function and autophagy.

Heat shock response and autophagy--cooperation and control

Protein quality control (proteostasis) depends on constant protein degradation and resynthesis, and is essential for proper homeostasis in systems from single cells to whole organisms. Cells possess several mechanisms and processes to maintain proteostasis. At one end of the spectrum, the heat shock proteins modulate protein folding and repair. At the other end, the proteasome and autophagy as well as other lysosome-dependent systems, function in the degradation of dysfunctional proteins. In this review, we examine how these systems interact to maintain proteostasis. Both the direct cellular data on heat shock control over autophagy and the time course of exercise-associated changes in humans support the model that heat shock response and autophagy are tightly linked. Studying the links between exercise stress and molecular control of proteostasis provides evidence that the heat shock response and autophagy coordinate and undergo sequential activation and downregulation, and that this is essential for proper proteostasis in eukaryotic systems.

5'-Monophosphate-activated protein kinase (AMPK) improves autophagic activity in diabetes and diabetic complications

Diabetes mellitus (DM), an endocrine disorder, will be one of the leading causes of death world-wide in about two decades. Cellular injuries and disorders of energy metabolism are two key factors in the pathogenesis of diabetes, which also become the important causes for the process of diabetic complications. AMPK is a key enzyme in maintaining metabolic homeostasis and has been implicated in the activation of autophagy in distinct tissues. An increasing number of researchers have confirmed that autophagy is a potential factor to affect or induce diabetes and its complications nowadays, which could remove cytotoxic proteins and dysfunctional organelles. This review will summarize the regulation of autophagy and AMPK in diabetes and its complications, and explore how AMPK stimulates autophagy in different diabetic syndromes. A deeper understanding of the regulation and activity of AMPK in autophagy would enhance its development as a promising therapeutic target for diabetes treatment.

Use of the mTOR inhibitor everolimus in a patient with multiple manifestations of tuberous sclerosis complex including epilepsy

Tuberous sclerosis complex (TSC) is a genetic disease in which overactivation of mechanistic target of rapamycin (mTOR) signaling leads to the growth of benign hamartomas in multiple organs, including the brain, and is associated with a high rate of epilepsy and neurological deficits. The mTOR inhibitor everolimus has been used in the treatment of subependymal giant cell astrocytomas and renal angiomyolipomas in patients with TSC. This article describes the case of a 13-year-old girl with TSC-associated epilepsy with refractory generalized seizures who initiated treatment with everolimus and experienced subsequent improvement in several TSC manifestations, including a reduction in seizure frequency from clusters of two or three daily to one every 2 to 4 weeks after 1.5 years of treatment.

Neurogenin 3-directed cre deletion of Tsc1 gene causes pancreatic acinar carcinoma

The role of tuberous sclerosis complex (TSC) in the pathogenesis of pancreatic cancers remains largely unknown. The present study shows that neurogenin 3 directed Cre deletion of Tsc1 gene induces the development of pancreatic acinar carcinoma. By cross-breeding the Neurog3-cre mice with Tsc1 (loxp/loxp) mice, we generated the Neurog3-Tsc1-/- transgenic mice in which Tsc1 gene is deleted and mTOR signaling activated in the pancreatic progenitor cells. All Neurog3-Tsc1-/- mice developed notable adenocarcinoma-like lesions in pancreas starting from the age of 100 days old. The tumor lesions are composed of cells with morphological and molecular resemblance to acinar cells. Metastasis of neoplasm to liver and lung was detected in 5% of animals. Inhibition of mTOR signaling by rapamycin significantly attenuated the growth of the neoplasm. Relapse of the neoplasm occurred within 14 days upon cessation of rapamycin treatment. Our studies indicate that activation of mTOR signaling in the pancreatic progenitor cells may trigger the development of acinar carcinoma. Thus, mTOR may serve as a potential target for treatment of pancreatic acinar carcinoma.

Everolimus and intensive behavioral therapy in an adolescent with tuberous sclerosis complex and severe behavior

BACKGROUND

Self-injury and aggression have been reported in individuals with TSC (tuberous sclerosis complex), yet few data exist about treatment. Everolimus, an mTOR inhibitor, has been FDA-approved for subependymal giant cell astrocytomas (SEGAs) and renal angiomyolipomas in TSC. However, clinical use of everolimus with direct, real-time observations of self-injury and aggression in an individual with TSC has not been reported.

METHODS

During an inpatient admission to a neurobehavioral unit, real-time measurements of behaviors and seizures were recorded. An interdisciplinary team used these data to make treatment decisions and applied behavioral and pharmacological treatments, one at a time, in order to evaluate their effects.

RESULTS

Aggression and self-injury improved with applied behavioral analysis (ABA), lithium, and asenapine. Improvements in SEGA size, facial angiofibromas, seizures, and the most stable low rates of self-injury were observed during the interval of treatment with everolimus.

CONCLUSION

Mechanism-based treatments in the setting of an evidence-based behavioral and psychopharmacological intervention program may be a model with utility for characterization and treatment of individuals with severe behavior and TSC.

Prognostic markers in renal cell carcinoma: A focus on the 'mammalian target of rapamycin' pathway

Objectives

Increased knowledge about the molecular pathways involved in tumorigenesis has led to the discovery of new prognostic molecular markers and development of novel targeted therapies for renal cell carcinoma (RCC). In this review we describe the prognostic markers of RCC and highlight the areas of recent discovery with a focus on the mammalian target of rapamycin (mTOR) pathway.

Methods

We reviewed previous reports, using PubMed with the search terms ‘renal cell carcinoma’, ‘molecular markers’, ‘prognosis’, ‘outcomes’ and ‘mammalian target of rapamycin pathway’ published in the last two decades. We created a library of 100 references and focused on presenting the recent advances in the field.

Results

Growing evidence suggests that mTOR deregulation is associated with many types of human cancer, including RCC. Consequently, temsirolimus and everolimus, which target mTOR, are approved for treating advanced RCC. There is a demand to integrate clinical, pathological and molecular markers into accurate prognostic models to provide patients with the most personalised cancer care possible.

Conclusions

The mTOR pathway is highly implicated in RCC tumorigenesis and progression, and its constituents might represent a promising prognostic tool and target for treating RCC. Combining newly discovered molecular markers with classic clinicopathological prognostics might potentially improve the management of RCC.