Cooperative benefit for the combination of rapamycin and imatinib in tuberous sclerosis complex neoplasia

Long-Term Effects of Sirolimus on Human Skin TSC2-Null Fibroblast‒Like Cells

Tuberous sclerosis complex (TSC) is an autosomal-dominant disorder characterized by hamartomatous tumors of the skin, kidneys, brain, and lungs. TSC is caused by mutations in the TSC1 and TSC2 genes, which result in hyperactivation of the mTOR, leading to dysregulated cell growth and autophagy. Rapamycin (sirolimus) shrinks TSC tumors, but the clinical benefits of sirolimus are not sustained after its withdrawal. In this study, we studied the cellular processes critical for tumor formation and growth, including cell proliferation and cell size. TSC2^-/- and TSC2^+/- cells were isolated from TSC skin tumors and normal-appearing skin, respectively. Cells were incubated with sirolimus for 72 hours. Withdrawal of sirolimus from TSC2^-/- cells resulted in a highly proliferative phenotype and caused cells to enter the S phase of the cell cycle, with persistent phosphorylation of mTOR, p70 S6 kinase, ribosomal protein S6, and 4EB-P1; decreased cyclin D kinase inhibitors; and transient hyperactivation of protein kinase B. Sirolimus modulated the estrogen- and autophagy-dependent volume of TSC2^-/- cells. These results suggest that sirolimus may decrease the size of TSC tumors by reducing TSC2^-/- cell volume, altering the cell cycle, and reprogramming TSC2-null cells.

Therapeutic paradigm of dual targeting VEGF and PDGF for effectively treating FGF-2 off-target tumors

FGF-2 displays multifarious functions in regulation of angiogenesis and vascular remodeling. However, effective drugs for treating FGF-2⁺ tumors are unavailable. Here we show that FGF-2 modulates tumor vessels by recruiting NG2⁺ pricytes onto tumor microvessels through a PDGFRβ-dependent mechanism. FGF-2⁺ tumors are intrinsically resistant to clinically available drugs targeting VEGF and PDGF. Surprisingly, dual targeting the VEGF and PDGF signaling produces a superior antitumor effect in FGF-2⁺ breast cancer and fibrosarcoma models. Mechanistically, inhibition of PDGFRβ ablates FGF-2-recruited perivascular coverage, exposing anti-VEGF agents to inhibit vascular sprouting. These findings show that the off-target FGF-2 is a resistant biomarker for anti-VEGF and anti-PDGF monotherapy, but a highly beneficial marker for combination therapy. Our data shed light on mechanistic interactions between various angiogenic and remodeling factors in tumor neovascularization. Optimization of antiangiogenic drugs with different principles could produce therapeutic benefits for treating their resistant off-target cancers.

Anti-VEGF therapy has many limitations that might be resolved by using combination treatment approaches. Here, the authors demonstrate that the dual-targeting of VEGF and PDGF is required for targeting resistant FGF2+ tumors which depend on the recruitment of pericytes on tumor microvessels.

Tuberous Sclerosis Complex Axis Controls Renal Extracellular Vesicle Production and Protein Content

The tuberous sclerosis complex (Tsc) proteins regulate the conserved mTORC1 growth regulation pathway. We identified that loss of the Tsc2 gene in mouse inner medullary collecting duct (mIMCD) cells induced a greater than two-fold increase in extracellular vesicle (EV) production compared to the same cells having an intact Tsc axis. We optimized EV isolation using a well-established size exclusion chromatography method to produce high purity EVs. Electron microscopy confirmed the purity and spherical shape of EVs. Both tunable resistive pulse sensing (TRPS) and dynamic light scattering (DLS) demonstrated that the isolated EVs possessed a heterogenous size distribution. Approximately 90% of the EVs were in the 100-250 nm size range, while approximately 10% had a size greater than 250 nm. Western blot analysis using proteins isolated from the EVs revealed the cellular proteins Alix and TSG101, the transmembrane proteins CD63, CD81, and CD9, and the primary cilia Hedgehog signaling-related protein Arl13b. Proteomic analysis of EVs identified a significant difference between the Tsc2-intact and Tsc2-deleted cell that correlated well with the increased production. The EVs may be involved in tissue homeostasis and cause disease by overproduction and altered protein content. The EVs released by renal cyst epithelia in TSC complex may serve as a tool to discover the mechanism of TSC cystogenesis and in developing potential therapeutic strategies.

Efficacy and Safety of Topical Rapamycin in Patients With Facial Angiofibromas Secondary to Tuberous Sclerosis Complex: The TREATMENT Randomized Clinical Trial

Importance

Facial angiofibromas occur in approximately 75% of individuals with tuberous sclerosis complex (TSC), causing substantial morbidity and disfigurement. Current therapies are partially effective, uncomfortable, produce scarring, and need repeating to treat recurrence.

Objective

To evaluate the efficacy and safety of topical rapamycin for TSC-related facial angiofibromas.

Design, Setting, and Participants

This prospective, multicenter, randomized, double-blind, vehicle-controlled trial with 6 monthly clinic visits enrolled 179 patients with TSC-related facial angiofibromas not treated within 6 months from May 2012 to March 2014 in 9 clinical sites in the United States and 1 in Australia.

Interventions

Patients were randomized (1:1:1) to topical formulation containing 0.3 g per 30 g (1%) rapamycin, 0.03 g per 30 g (0.1%) rapamycin, or vehicle alone. Participants applied 1.0 mL to designated areas daily at bedtime.

Main Outcomes and Measures

Angiofibroma Grading Scale (AGS) change from baseline scored from photographs by independent masked dermatologists. Safety analyses included adverse events (AEs) and serum rapamycin levels.

Results

All 179 patients randomized (99 [55.3%] female) comprised the primary analysis population (59 in the 1% rapamycin group, 63 in the 0.1% rapamycin group, and 57 in the vehicle-only group). The mean age was 20.5 years (range 3-61 years). Clinically meaningful and statistically significant improvement in facial angiofibromas was observed for both 1% and 0.1% rapamycin relative to the vehicle-only control group, and for 1% vs 0.1% rapamycin, with most of the improvement realized within the first month. At 6 months, AGS mean improvement for 1% rapamycin was 16.7 points compared with 11.0 for 0.1% rapamycin and 2.1 points for vehicle only (P < .001 for 1% and 0.1% vs vehicle only). Compared with baseline, end-of-treatment photos were rated "better" for 81.8% of patients in the 1% rapamycin group, compared with 65.5% for those in the 0.1% rapamycin group and 25.5% for those in the vehicle-only group (P < .001, all 3 pairwise comparisons). Topical rapamycin was generally well-tolerated, with no measurable systemic absorption. Apparent drug-related adverse effects were limited to 10% or less incidence of application site discomfort and/or pain, pruritus, erythema, and irritation. Nearly all AEs were mild, with no drug-related moderate, severe, or serious events.

Conclusions and Relevance

Topical rapamycin appears effective and safe for treatment of TSC-related facial angiofibromas. In this trial, the preferred dose was 1% once daily. Future studies are needed to evaluate prophylactic, early, and long-term use of topical rapamycin, durability of response, and combination therapy with oral mammalian target of rapamycin (mTOR) inhibitors.

Trial Registration

ClinicalTrials.gov Identifier: NCT01526356.

Dual roles of endothelial FGF-2-FGFR1-PDGF-BB and perivascular FGF-2-FGFR2-PDGFRβ signaling pathways in tumor vascular remodeling

Perivascular cells are important cellular components in the tumor microenvironment (TME) and they modulate vascular integrity, remodeling, stability, and functions. Here we show using mice models that FGF-2 is a potent pericyte-stimulating factor in tumors. Mechanistically, FGF-2 binds to FGFR2 to stimulate pericyte proliferation and orchestrates the PDGFRβ signaling for vascular recruitment. FGF-2 sensitizes the PDGFRβ signaling through increasing PDGFRβ levels in pericytes. To ensure activation of PDGFRβ, the FGF-2-FGFR1-siganling induces PDGF-BB and PDGF-DD, two ligands for PDGFRβ, in angiogenic endothelial cells. Thus, FGF-2 directly and indirectly stimulates pericyte proliferation and recruitment by modulating the PDGF-PDGFRβ signaling. Our study identifies a novel mechanism by which the FGF-2 and PDGF-BB collaboratively modulate perivascular cell coverage in tumor vessels, thus providing mechanistic insights of pericyte-endothelial cell interactions in TME and conceptual implications for treatment of cancers and other diseases by targeting the FGF-2-FGFR-pericyte axis.

Pericyte-fibroblast transition promotes tumor growth and metastasis

Vascular pericytes, an important cellular component in the tumor microenvironment, are often associated with tumor vasculatures, and their functions in cancer invasion and metastasis are poorly understood. Here we show that PDGF-BB induces pericyte-fibroblast transition (PFT), which significantly contributes to tumor invasion and metastasis. Gain- and loss-of-function experiments demonstrate that PDGF-BB-PDGFRβ signaling promotes PFT both in vitro and in in vivo tumors. Genome-wide expression analysis indicates that PDGF-BB-activated pericytes acquire mesenchymal progenitor features. Pharmacological inhibition and genetic deletion of PDGFRβ ablate the PDGF-BB-induced PFT. Genetic tracing of pericytes with two independent mouse strains, TN-AP-CreERT2:R26R-tdTomato and NG2-CreERT2:R26R-tdTomato, shows that PFT cells gain stromal fibroblast and myofibroblast markers in tumors. Importantly, coimplantation of PFT cells with less-invasive tumor cells in mice markedly promotes tumor dissemination and invasion, leading to an increased number of circulating tumor cells and metastasis. Our findings reveal a mechanism of vascular pericytes in PDGF-BB-promoted cancer invasion and metastasis by inducing PFT, and thus targeting PFT may offer a new treatment option of cancer metastasis.

The changing face of a rare disease: lymphangioleiomyomatosis

Lymphangioleiomyomatosis is a rare disease characterised by cystic destruction of the lung, lymphatic abnormalities and abdominal tumours. It affects almost exclusively females and can occur sporadically or in patients with tuberous sclerosis complex. In the past decade remarkable progress has been made in understanding of the pathogenesis of this disease leading to a new therapeutic approach. This review summarises recent advances regarding pathogenic mechanisms and clinical manifestations, and highlights the current and the most promising future therapeutic strategies.

Synergistic Inhibition of Tumor Necrosis Factor-Alpha-Stimulated Pro-Inflammatory Cytokine Expression in HaCaT Cells by a Combination of Rapamycin and Mycophenolic Acid

Background

Keratinocytes release various pro-inflammatory cytokines, chemokines, and adhesion molecules such as intercellular adhesion molecule 1 (ICAM-1) in response to cytokines such as tumor necrosis factor (TNF)-α and interferon (IFN)-γ. Rapamycin and mycophenolic acid (MPA) have potent immunosuppressive activity because they inhibit lymphocyte proliferation.

Objective

We investigated the effects of rapamycin and MPA on the expression of inflammation-related factors such as ICAM-1 and inducible nitric oxide synthase (iNOS), pro-inflammatory cytokines and chemokines, and related signaling pathways in TNF-α-stimulated HaCaT cells.

Methods

The viability of HaCaT cells treated with rapamycin and MPA was confirmed using MTT assay. The expression of various cytokines such as interleukin (IL)-1β, IL-6, and IL-8; inflammation-related factors such as ICAM-1 and iNOS; and the activation of mitogen activated protein kinase (MAPK) signaling pathways mediated by extracellular signal-related kinases (ERK), p38, and c-Jun N-terminal kinases (JNK) in TNF-α-stimulated HaCaT cells were confirmed using reverse transcription-polymerase chain reaction and western blotting.

Results

Combined treatment of TNF-α-induced HaCaT cells with rapamycin and MPA decreased ICAM-1 and iNOS expression and ERK and p38 activation more than treatment with either drug alone. The most significant decrease was observed with a combination of rapamycin (80 nM) and MPA (20 nM). These results show that co-treatment with these agents has a synergistic anti-inflammatory effect by blocking the activation of the ERK/p38 MAPK signaling pathway and thus suppressing the TNF-α-induced expression of ICAM-1 and iNOS.

Conclusion

The combination of rapamycin and MPA could potentially be used as a therapeutic approach in inflammatory skin diseases.

Evidence for pericyte origin of TSC-associated renal angiomyolipomas and implications for angiotensin receptor inhibition therapy

Nearly all patients with tuberous sclerosis complex (TSC) develop renal angiomyolipomas, although the tumor cell of origin is unknown. We observed decreased renal angiomyolipoma development in patients with TSC2- polycystic kidney disease 1 deletion syndrome and hypertension that were treated from an early age with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers compared with patients who did not receive this therapy. TSC-associated renal angiomyolipomas expressed ANG II type 1 receptors, platelet-derived growth factor receptor-β, desmin, α-smooth muscle actin, and VEGF receptor 2 but did not express the adipocyte marker S100 or the endothelial marker CD31. Sera of TSC patients exhibited increased vascular mural cell-secreted peptides, such as VEGF-A, VEGF-D, soluble VEGF receptor 2, and collagen type IV. These findings suggest that angiomyolipomas may arise from renal pericytes. ANG II treatment of angiomyolipoma cells in vitro resulted in an exaggerated intracellular Ca(2+) response and increased proliferation, which were blocked by the ANG II type 2 receptor antagonist valsartan. Blockade of ANG II signaling may have preventative therapeutic potential for angiomyolipomas.

The use of everolimus to target carcinogenic pathways in a patient with renal cell carcinoma and tuberous sclerosis complex: a case report

INTRODUCTION

An increased understanding of the genetic pathways involved in renal cell carcinoma has resulted in the development of various drugs that target relevant signaling cascades for the specific treatment of this disease. However, no validated predictive markers have been identified to guide the decision whether patients should receive vascular endothelial growth factor-targeted therapy or mammalian target of rapamycin-targeted therapy. We present what is, to the best of our knowledge, the first case of renal cell carcinoma in a patient with tuberous sclerosis complex who was successfully treated with everolimus.

CASE PRESENTATION

The patient was a 49-year-old Korean woman with tuberous sclerosis complex and recurrent renal cell carcinoma. The patient was treated with the tyrosine kinase inhibitor sunitinib followed by the mammalian target of rapamycin inhibitor everolimus. This treatment resulted in a prolonged response and significant clinical benefit. Notably, everolimus ameliorated the symptoms related not only to renal cell carcinoma but also to tuberous sclerosis complex.

CONCLUSION

This case provides a rationale for the use of everolimus as first-line treatment for this specific patient population in order to target the correct pathway involved in carcinogenesis.