sirolimus and Hypopigmentation

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder leading to the aberrant activation of the mammalian target of rapamycin complex 1. Although the efficacy of mammalian target of rapamycin complex 1 inhibitors against tumors in patients with TSC, including facial angiofibroma, has been well investigated, their efficacy against hypomelanotic macules in patients with TSC is unknown.. To evaluate objectively the efficacy of topical rapamycin treatment of hypomelanotic macules in patients with TSC and to elucidate the mechanisms of how rapamycin improves the macules.. We performed a prospective, baseline-controlled trial of 6 patients with TSC and hypomelanotic macules in non-sun-exposed and sun-exposed skin at the Department of Dermatology, Osaka University, from August 4, 2011, through September 27, 2012. Rapamycin gel, 0.2%, was applied to the lesions twice a day for 12 weeks. Histologic examinations and blood tests were conducted at the start and completion of treatment. Blood rapamycin levels were analyzed at completion.. Topical rapamycin treatment for hypomelanotic macules.. Objective evaluation of rapamycin treatment of hypomelanotic macules in TSC with δ-L (L indicates the brightness of the color) levels on spectrophotometry at the start and completion (12 weeks) of treatment and at 4 and 12 weeks after discontinuation of treatment (16 and 24 weeks, respectively).. Improvement of hypomelanotic macules (in δ-L values) was significant at 12 weeks (mean [SD], 2.501 [1.694]; P < .05), 16 weeks (1.956 [1.567]; P < .01), and 24 weeks (1.836 [1.638]; P < .001). Although efficacy tended to be prominent in sun-exposed skin, we did not observe significant differences (in δ-L values) between sun-exposed and non-sun-exposed skin at 12 weeks (mean [SD], 1.859 [0.629] and 3.142 [2.221], respectively), 16 weeks ( 1.372 [0.660] and 2.539 [2.037], respectively), and 24 weeks (1.201 [0.821] and 2.471 [2.064], respectively). No adverse events were observed, and rapamycin was not detected in the blood of any patient. Electron microscopic analysis of hypomelanotic macules revealed that topical rapamycin treatment significantly improved the uniformity of the melanosome numbers in the TSC melanocytes (pretreatment macules: mean [SD], 25.71 [21.90] [range, 5-63]; posttreatment macules: 42.43 [3.60] [range, 38-49]; P < .001). Moreover, rapamycin treatment induced the recovery of melanosomes in TSC-knocked-down melanocytes from depleted amounts (mean [SD], 16.43 [11.84]) to normal levels (42.83 [14.39]; P < .001).. Topical rapamycin treatment was effective and safe against hypomelanotic macules arising from TSC. This efficacy of rapamycin was corroborated as stemming from the improvement of impaired melanogenesis in TSC melanocytes.

Topics: Administration, Cutaneous; Adolescent; Adult; Antibiotics, Antineoplastic; Child; Child, Preschool; Female; Humans; Hypopigmentation; Male; Melanins; Melanosomes; Microscopy, Electron; Prospective Studies; Sirolimus; Skin Neoplasms; Spectrophotometry; Tuberous Sclerosis; Young Adult

Tuberous sclerosis complex (TSC) is a rare autosomal dominant genetic disease with many manifestations, and it involves any organ. In this study, we report a TSC patient with new type skin lesions.. A 7-month-old TSC boy with multiple cutaneous nodules was admitted in our hospital. We collected the clinical data of the patient. We performed biopsy of cutaneous nodules and whole-exome sequencing in both paraffin block tissue and blood samples.. The patient presented with a 2 month history of gradual growth multiple cutaneous nodules. He had cardiac rhabdomyoma, subependymal giant cell astrocytoma (SEGA) and hypomelanotic macules. The pathological finding of cutaneous nodules was consistent with juvenile xanthogranuloma (JXG). After 3 months of sirolimus treatment, the multiple nodules disappeared. The whole-exome sequencing identified TSC1 (c.2356C > T, p.R786*) mutation in both paraffin block tissue and blood samples. We overturned the original pathological diagnosis and finally identified JXG as a new type of skin lesions in TSC.. This is the first report on the occurrence of JXG skin lesions in TSC patient. Genetic testing is necessary in JXG. These findings expand the phenotype of skin in patients with TSC and contribute to the elucidation of JXG pathogenesis and treatment.

Topics: Genetic Testing; Humans; Hypopigmentation; Infant; Male; Sirolimus; Tuberous Sclerosis; Xanthogranuloma, Juvenile

Accumulating evidence has described the involvement of mTORC1 signaling in pigmentation regulation; however, the precise mechanism is not fully understood. Here, we generated mice with conditional deletion of the mTORC1 suppressor Tsc2 in melanocytes. It resulted in constitutive hyperactivation of mTORC1 and reduced skin pigmentation. Mechanistically, neither the number of melanocytes nor the expression of melanogenesis-related enzymes was decreased; however, endoplasmic reticulum and mitochondrial oxidative stress and lower melanization in melanosomes were observed. By contrast, abrogation of mTORC1 by rapamycin completely reversed the reduced pigmentation, and alleviation of endoplasmic reticulum stress by SMER28 or 4-phenylbutyrate (PBA) or alleviation of mitochondrial oxidative stress by administration of adenosine triphosphate partially reversed the reduced pigmentation in these mice. In addition, we showed that these mechanisms were involved in reduced pigmentation of TSC2 small interfering RNA-transfected cultured human primary melanocytes and skin lesions of patients with the TSC gene mutation.

Topics: Animals; Endoplasmic Reticulum; Humans; Hypopigmentation; Mechanistic Target of Rapamycin Complex 1; Melanins; Melanocytes; Mice; Mice, Knockout; Mitochondria; Oxidative Stress; Sirolimus; Skin Pigmentation; TOR Serine-Threonine Kinases; Tuberous Sclerosis Complex 2 Protein

Tuberous sclerosis complex (TSC) gene mutations lead to constitutive activation of the mammalian target of rapamycin (mTOR) pathway, resulting in a broad range of symptoms. Hypopigmented macules are the earliest sign. Although we have already confirmed that topical rapamycin treatment (an mTOR inhibitor) protects patients with TSC against macular hypopigmentation, the pathogenesis of such lesions remains poorly understood.. Recently emerging evidence supports a role for autophagy in skin pigmentation. Herein, we investigated the impact of autophagic dysregulation on TSC-associated hypopigmentation.. Skin samples from 10 patients with TSC, each bearing characteristic hypopigmented macules, and 6 healthy donors were subjected to immunohistochemical and electron microscopic analyses. In addition, TSC2-knockdown (KD) was investigated in human epidermal melanocytes by melanin content examination, real-time PCR, western blotting analyses, and intracellular immunofluorescence staining.. Activation of the mTOR signaling pathway decreased melanocytic pigmentation in hypopigmented macules of patients with TSC and in TSC2-KD melanocytes. In addition, LC3 expression (a marker of autophagy) and autophagosome counts increased, whereas, intracellular accumulation of autophagic degradative substrates (p62 and ubiquitinated proteins) was evident in TSC2-KD melanocytes. Furthermore, depigmentation in TSC2-KD melanocytes was accelerated by inhibiting autophagy (ATG7-KD or bafilomycin A1-pretreatment) and was completely reversed by induction of autophagy via mTOR-dependent (rapamycin) or mTOR-independent (SMER28) exposure. Finally, dysregulation of autophagy, marked by increased LC3 expression and accumulation of ubiquitinated proteins, was also observed in melanocytes of TSC-related hypopigmented macules.. Our data demonstrate that melanocytes of patients with TSC display autophagic dysregulation, which thereby reduced pigmentation, serving as the basis for the hypomelanotic macules characteristic of TSC.

Topics: Allyl Compounds; Autophagy; Epidermal Cells; Epidermis; Gene Knockdown Techniques; Humans; Hypopigmentation; Immunosuppressive Agents; Macrolides; Melanins; Melanocytes; Microscopy, Electron; Microtubule-Associated Proteins; Primary Cell Culture; Quinazolines; RNA, Small Interfering; Signal Transduction; Sirolimus; TOR Serine-Threonine Kinases; Tuberous Sclerosis; Tuberous Sclerosis Complex 2 Protein; Tumor Suppressor Proteins

Topics: Antibiotics, Antineoplastic; Female; Humans; Hypopigmentation; Male; Melanosomes; Sirolimus; Skin Neoplasms; Tuberous Sclerosis

Topics: Administration, Topical; Adolescent; Angiofibroma; Antibiotics, Antineoplastic; Facial Neoplasms; Humans; Hypopigmentation; Male; Neoplasms, Multiple Primary; Sirolimus; Tuberous Sclerosis

Topics: Administration, Topical; Child; Child, Preschool; Humans; Hypopigmentation; Male; Sirolimus; TOR Serine-Threonine Kinases; Tuberous Sclerosis

Sphingosylphosphorylcholine (SPC) acts as a potent lipid mediator and signaling molecule in various cell types. In the present study, we investigated the effects of SPC on melanogenesis and SPC-modulated signaling pathways related to melanin synthesis.. Melanin production was measured in Mel-Ab cells. A luciferase assay was used to detect transcriptional activity of the MITF promoter. Western blot analysis was performed to examine SPC-induced signaling pathways.. SPC produced significant hypopigmentation effects in a dose-dependent manner. It was found that SPC induced not only activation of Akt but also stimulation of mTOR, a downstream mediator of the Akt signaling pathway. Moreover, SPC decreased the levels of LC3 II, which is known to be regulated by mTOR. Treatment with the mTOR inhibitor rapamycin eliminated decreases in melanin and LC3 II levels by SPC. Furthermore, we found that the Akt inhibitor LY294002 restored SPC-mediated downregulation of LC3 II and inhibited the activation of mTOR by SPC.. Our data suggest that the mTOR signaling pathway is involved in SPC-modulated melanin synthesis.

Topics: Analysis of Variance; Animals; Blotting, Western; Cell Line; Chromones; Dose-Response Relationship, Drug; Hypopigmentation; Luciferases; Melanins; Mice; Microscopy, Phase-Contrast; Monophenol Monooxygenase; Morpholines; Phosphorylcholine; Proto-Oncogene Proteins c-akt; Signal Transduction; Sirolimus; Sphingosine; TOR Serine-Threonine Kinases; Transfection