Characterisation of Lipoma-Preferred Partner as a Novel Mechanotransducer in Vascular Smooth Muscle Cells.

In arteries and arterioles, a chronic increase in blood pressure raises wall tension. This continuous biomechanical strain causes a change in gene expression in vascular smooth muscle cells (VSMCs) that may lead to pathological changes. Here we have characterised the functional properties of lipoma-preferred partner (LPP), a Lin11-Isl1-Mec3 (LIM)-domain protein, which is most closely related to the mechanotransducer zyxin but selectively expressed by smooth muscle cells, including VSMCs in adult mice. VSMCs isolated from the aorta of LPP knockout (LPP-KO) mice displayed a higher rate of proliferation than their wildtype (WT) counterparts, and when cultured as three-dimensional spheroids, they revealed a higher expression of the proliferation marker Ki 67 and showed greater invasion into a collagen gel. Accordingly, the gelatinase activity was increased in LPP-KO but not WT spheroids. The LPP-KO spheroids adhering to the collagen gel responded with decreased contraction to potassium chloride. The relaxation response to caffeine and norepinephrine was also smaller in the LPP-KO spheroids than in their WT counterparts. The overexpression of zyxin in LPP-KO VSMCs resulted in a reversal to a more quiescent differentiated phenotype. In native VSMCs, i.e., in isolated perfused segments of the mesenteric artery (MA), the contractile responses of LPP-KO segments to potassium chloride, phenylephrine or endothelin-1 did not vary from those in isolated perfused WT segments. In contrast, the myogenic response of LPP-KO MA segments was significantly attenuated while zyxin-deficient MA segments displayed a normal myogenic response. We propose that LPP, which we found to be expressed solely in the medial layer of different arteries from adult mice, may play an important role in controlling the quiescent contractile phenotype of VSMCs.

Adipose and lipoma stem cells: A donor-matched comparison.

Lipomas are slow growing benign fat tumors that develop in soft tissues of the mesoderm. Thus, the specific (dys-)function of mesenchymal stem cells (MSCs) has been suggested in the development of lipomas, but details of the tumor pathogenesis remain unclear. Existing studies comparing stem cells from native adipose (adipose stem cells [ASCs]) and lipomatous tissues (LSCs) have reported contradicting findings. However, harvesting ASCs and LSCs from different individuals might have influenced proper comparison. Therefore, we aimed to characterize donor-matched ASCs and LSCs to investigate metabolic activity, proliferation, capability for tri-linear differentiation (chondrogenesis, adipogenesis, osteogenesis), and the secretome of mature adipocytes and lipomacytes. Both stem cell types did not differ in metabolic activity, but ASCs demonstrated stronger proliferation than LSCs. While there was no difference in proteoglycan accumulation during chondrogenic differentiation, adipogenesis was higher in ASCs, with more lipid vacuole formation. Conversely, LSCs showed increased osteogenesis by higher calcium deposition. Lipomacytes showed stronger secretory activity and released higher levels of certain adipokines. Our findings indicated that LSCs possessed important characteristics of MSCs, including ASCs. However, LSCs' low proliferation and adipogenic differentiation behavior did not appear to account for enhanced tissue proliferation, but the secretome of lipomacytes could contribute to lipomatous neoplasm.

Discrimination of lipoma from atypical lipomatous tumor/well-differentiated liposarcoma using magnetic resonance imaging radiomics combined with machine learning.

PURPOSE: To evaluate the diagnostic capability of radiomics in distinguishing lipoma and Atypic Lipomatous Tumors/Well-Differentiated Liposarcomas (ALT/WDL) with Magnetic Resonance Imaging (MRI). MATERIALS AND METHODS: Patients with a histopathologic diagnosis of lipoma (n = 45) and ALT/WDL (n = 20), who had undergone pre-surgery or pre-biopsy MRI, were enrolled. The MDM2 amplification was accepted as gold-standard test. The T1-weighted turbo spin echo images were used for radiomics analysis. Utility of a predefined standardized imaging protocol and a single type of 1.5 T scanner were sought as inclusion criteria. Radiomics parameters that show a certain level of reproducibility were included in the study and supplied to Support Vector Machine (SVM) as a machine learning method. RESULTS: No significant difference was found in terms of gender, location and age between the lipoma and ALT/WDL groups. Sixty-five parameters were accepted as reproducible. Fifty-seven parameters were able to distinguish the two groups significantly (AUC range 0.564-0.902). Diagnostic performance of the SVM was one of the highest among literature findings: sensitivity = 96.8% (95% CI 94.03-98.39%), specificity = 93.72% (95% CI 86.36-97.73%) and AUC = 0.987 (95% CI 0.972-0.999). CONCLUSION: Although radiomics has been proven to be useful in previous literature regarding discrimination of lipomas and ALT/WDLs, we found that its accuracy could further be improved with utility of standardized hardware, imaging protocols and incorporation of machine learning methods.

Small integral membrane protein 10 like 1 downregulation enhances differentiation of adipose progenitor cells.

Small integral membrane protein 10 like 1 (SMIM10L1) was identified by RNA sequencing as the most significantly downregulated gene in Phosphatase and Tensin Homologue (PTEN) knockdown adipose progenitor cells (APCs). PTEN is a tumor suppressor that antagonizes the growth promoting Phosphoinositide 3-kinase (PI3K)/AKT/mechanistic Target of Rapamycin (mTOR) cascade. Diseases caused by germline pathogenic variants in PTEN are summarized as PTEN Hamartoma Tumor Syndrome (PHTS). This overgrowth syndrome is associated with lipoma formation, especially in pediatric patients. The mechanisms underlying this adipose tissue dysfunction remain elusive. We observed that SMIM10L1 downregulation in APCs led to an enhanced adipocyte differentiation in two- and three-dimensional cell culture and increased expression of adipogenesis markers. Furthermore, SMIM10L1 knockdown cells showed a decreased expression of PTEN, pointing to a mutual crosstalk between PTEN and SMIM10L1. In line with these observations, SMIM10L1 knockdown cells showed increased activation of PI3K/AKT/mTOR signaling and concomitantly increased expression of the adipogenic transcription factor SREBP1. We computationally predicted an α-helical structure and membrane association of SMIM10L1. These results support a specific role for SMIM10L1 in regulating adipogenesis, potentially by increasing PI3K/AKT/mTOR signaling, which might be conducive to lipoma formation in pediatric patients with PHTS.

Lessons learnt from MDM2 fluorescence in-situ hybridisation analysis of 439 mature lipomatous lesions with an emphasis on atypical lipomatous tumour/well-differentiated liposarcoma lacking cytological atypia.

AIMS: Amplification of the murine double minute-2 (MDM2) gene, which is usually detected with fluorescence in-situ hybridisation (FISH), is the key driving event for atypical lipomatous tumours (ALTs)/well-differentiated liposarcomas (WDLs). We sought to determine the concordance between the histopathological findings and MDM2 FISH in the diagnosis of ALT/WDL, and to identify the histological features of MDM2-amplified tumours lacking classic atypia. METHODS AND RESULTS: We performed a retrospective analysis of all mature lipomatous lesions subjected to MDM2 FISH analysis at our institution. MDM2 FISH analysis was performed on 439 mature lipomatous lesions: 364 (82.9%) were negative and 75 (17%) were positive. In 17 of 75 (22.6%) ALTs/WDLs, cytological atypia was not identified on initial histological assessment, thus favouring lipoma. On review, these cases shared common histological features, consisting of a very low number of relatively small stromal cells within the tumour lobules, with mildly coarse chromatin and oval nuclei, admixed with unremarkable adipocytes in a tumour background devoid of fibroconnective septa, areas of fibrosis, or blood vessels. These cells matched the cells in which FISH showed MDM2 amplification. In contrast, 13 cases (3.5%) regarded as suspicious for ALT/WDL on the basis of histology lacked MDM2 amplification and were reclassified following the FISH findings. CONCLUSIONS: We conclude that a subset of lipoma-like ALTs/WDLs are not associated with any of the features typically described in ALT/WDL. Our study also showed that tumours >100 mm are more likely to be ALT/WDL; however, a history of recurrence or concerning clinical/radiological features was not significantly associated with classification as ALT/WDL.

Case Report: Lipoma of the Tuber Cinereum Mimicking a Pituitary Gland Abnormality in a Girl With Central Precocious Puberty.

Introduction: Magnetic Resonance Imaging (MRI) is the best approach to investigate the hypothalamic-pituitary region in children with central precocious puberty (CPP). Routine scanning is controversial in girls aged 6-8 year, due to the overwhelming prevalence of idiopathic forms and unrelated incidentalomas. Cerebral lipomas are rare and accidental findings, not usually expected in CPP. We report a girl with CPP and an unusually shaped posterior pituitary gland on SE-T1w sequences. Case Description: A 7.3-year-old female was referred for breast development started at age 7. Her past medical history and physical examination were unremarkable, apart from the Tanner stage 2 breast. X-ray of the left-hand revealed a bone age 2-years ahead of her chronological age, projecting her adult height prognosis below the mid parental height. LHRH test and pelvic ultrasound were suggestive for CPP. Routine brain MRI sequences, SE T1w and TSE T2w, showed the posterior pituitary bright spot increased in size and stretched upward. The finding was considered as an anatomical variant, in an otherwise normal brain imaging. Patient was started on treatment with GnRH analogue. At a thorough revaluation, imaging overlap with adipose tissue was suspected and a new MRI scan with 3D-fat-suppression T1w-VIBE sequences demonstrated a lipoma of the tuber cinereum, bordering a perfectly normal neurohypophysis. 3D-T2w-SPACE sequences, acquired at first MRI scan, would have provided a more correct interpretation if rightly considered. Conclusion: This is the first evidence, to our knowledge, of a cerebral lipoma mimicking pituitary gland abnormalities. Our experience highlights the importance of considering suprasellar lipomas in the MRI investigation of children with CPP, despite their rarity, should the T1w sequences show an unexpected pituitary shape. 3D-T2w SPACE sequences could be integrated into standard ones, especially when performing MRI routinely, to avoid potential misinterpretations.

PTEN regulates adipose progenitor cell growth, differentiation, and replicative aging.

The tumor suppressor phosphatase and tensin homolog (PTEN) negatively regulates the insulin signaling pathway. Germline PTEN pathogenic variants cause PTEN hamartoma tumor syndrome (PHTS), associated with lipoma development in children. Adipose progenitor cells (APCs) lose their capacity to differentiate into adipocytes during continuous culture, whereas APCs from lipomas of patients with PHTS retain their adipogenic potential over a prolonged period. It remains unclear which mechanisms trigger this aberrant adipose tissue growth. To investigate the role of PTEN in adipose tissue development, we performed functional assays and RNA-Seq of control and PTEN knockdown APCs. Reduction of PTEN levels using siRNA or CRISPR led to enhanced proliferation and differentiation of APCs. Forkhead box protein O1 (FOXO1) transcriptional activity is known to be regulated by insulin signaling, and FOXO1 was downregulated at the mRNA level while its inactivation through phosphorylation increased. FOXO1 phosphorylation initiates the expression of the lipogenesis-activating transcription factor sterol regulatory element-binding protein 1 (SREBP1). SREBP1 levels were higher after PTEN knockdown and may account for the observed enhanced adipogenesis. To validate this, we overexpressed constitutively active FOXO1 in PTEN CRISPR cells and found reduced adipogenesis, accompanied by SREBP1 downregulation. We observed that PTEN CRISPR cells showed less senescence compared with controls and the senescence marker CDKN1A (p21) was downregulated in PTEN knockdown cells. Cellular senescence was the most significantly enriched pathway found in RNA-Seq of PTEN knockdown versus control cells. These results provide evidence that PTEN is involved in the regulation of APC proliferation, differentiation, and senescence, thereby contributing to aberrant adipose tissue growth in patients with PHTS.

Imunoexpressão das proteínas EGFR e VEGF em lipomas de cavidade oral / Immunoexpression of EGFR and VEGF proteins in oral cavity lipomas

Lipomas são as neoplasias mesênquimais benignas mais comuns. Apresentam predileção pelo tronco, ombros, pescoço e axila, sendo raro nas mãos, parte inferior das pernas e pés. A região de cabeça e pescoço é responsável por 20% dos casos. A cavidade oral é responsável por 1-4% de todos os tumores, afeta de maneira semelhante o sexo feminino e masculino, acometendo ampla faixa etária. A etiopatogênia desse tumor ainda permanece desconhecida, dessa forma, essa pesquisa teve como objetivo detectar, quantificar e comparar a expressão imunoistoquímica do EGFR, VEGF e contagem microvascular (MVC) dos lipomas orais, relacionando-os com as características clínicas e morfológicas dos casos estudados. A amostra foi composta por 54 lipomas orais (33 clássicos e 21 não clássicos) e 23 casos de tecido adiposo normal. A análise da expressão imunoistoquímica de EGFR e VEGF foi fundamentada na marcação da membrana citoplasmática e/ou núcleo. O índice angiogênico foi avaliado por meio da contagem microvascular (MVC). A contagem de células foi realizada utilizando software IMAGE J®. Os dados obtidos foram analisados no software Statistical Package for Social Science. O nível se significância de 5% foi adotado para os testes estatísticos (p ≤ 0,05). A Análise da imunoexpressão das proteínas revelou para o EGFR diferença estatisticamente significativa (p=0,041) entre o lipoma clássico e o tecido adiposo normal. Com relação a contagem de microvasos, o CMV dos lipomas não clássico apresentou diferença estatisticamente significativa (p=0,018) em relação ao tecido adiposo normal. Nos lipomas não clássicos, apenas a imunoexpressão de VEGF esteve diretamente proporcional a CMV encontrado na neoplasia, com correlação do tipo moderada, positiva e significativa (p=0,010). Ademais, nos lipomas clássicos foi percebido que os adipócitos imunomarcados para EGFR estiveram diretamente proporcionais a imunoexpressão de VEGF, isso deve-se a correlação do tipo moderada, positiva e estatisticamente significativa (p = 0,005). Com base nos resultados, pode-se concluir que apesar do EGFR, VEGFR e CMV participarem do desenvolvimento neoplásico, é possível sugerir que nos lipomas, essas proteínas e o CMV não estejam primariamente envolvidos no crescimento tumoral (AU).

Lipomas are the most common benign mesenchymal neoplasms. They have a predilection for the trunk, shoulders, neck and armpit, being rare in the hands, lower legs and feet. The head and neck region accounts for 20% of cases. The oral cavity is responsible for 1-4% of all tumors, affecting females and males in a similar way, affecting a wide age range. The etiopathogenesis of this tumor remains unknown, therefore, this research aimed to detect, quantify and compare the immunohistochemical expression of EGFR, VEGF and microvascular count (MVC) of oral lipomas, relating them to the clinical and morphological characteristics of the cases studied . The sample consisted of 54 oral lipomas (33 classic and 21 non-classical) and 23 cases of normal adipose tissue. The analysis of the immunohistochemical expression of EGFR and VEGF was based on cytoplasmic membrane and/or nucleus labeling. The angiogenic index was assessed using microvascular count (MVC). Cell counting was performed using IMAGE J® software. The data obtained were analyzed using the Statistical Package for Social Science software. A significance level of 5% was adopted for statistical tests (p ≤ 0.05). Analysis of protein immunoexpression revealed a statistically significant difference (p=0.041) for EGFR between classic lipoma and normal adipose tissue. Regarding microvessel count, the CMV of non-classic lipomas showed a statistically significant difference (p=0.018) in relation to normal adipose tissue. In non-classical lipomas, only VEGF immunoexpression was directly proportional to the CMV found in the neoplasm, with a moderate, positive and significant correlation (p=0.010). Furthermore, in classical lipomas it was noticed that adipocytes immunolabeled for EGFR were directly proportional to VEGF immunoexpression, this is due to the moderate, positive and statistically significant correlation (p = 0.005). Based on the results, it can be concluded that although EGFR, VEGFR and CMV participate in neoplastic development, it is possible to suggest that in lipomas, these proteins and CMV are not primarily involved in tumor growth (AU).

Coexistence of three nevus lipomatosus cutaneus superficialis with typical, cutaneous adenolipoma-like, and dermal spindle cell lipoma-like histopathological features in a patient.

We report an unique case of a patient who showed coexistence of three nevus lipomatosus cutaneus superficialis (NLCS) with typical, cutaneous adenolipoma (AL)-like, and dermal spindle cell lipoma (SCL)-like histopathological features. A 53-year-old woman presented with a 20-year history of skin-colored and slightly elevated nodules. These lesions were separately located on the lateral side (lesion 1) and medial side (lesion 2) of her left buttock and on her right thigh (lesion 3). Microscopically, all were ill-defined dermal lesions with some subcutaneous involvement and were mostly composed of mature adipocytes. The adipocytes formed small aggregates around blood vessels in the upper dermis. Lesions 1, 2, and 3 were diagnosed as NLCS, and additional features were recognized in lesions 2 and 3. Lesion 2 revealed eccrine glands and ducts amongst the lipomatous component, as seen in cutaneous AL. Lesion 3 had scattered CD34-positive spindle cells, which is representative of dermal SCL. These appearances were considered to be on the morphological spectrum of NLCS. In all three lesions, CD34-positive cells proliferated between the upper dermal blood vessels and their peripheral mature adipocytes. This pathological finding could be principal in NLCS and might be associated with its pathogenesis.

Fat-free pleomorphic lipoma of the buccal mucosa: An immunohistochemical study and literature review.

Pleomorphic lipomas are extremely rare in the oral cavity. Due to the significant overlap of morphological findings with several benign and malignant soft tissue tumors, especially in the absence of adipocytes, the diagnosis is challenging. We reported the clinicopathological and immunohistochemical features of an uncommon case of a fat-free variant of pleomorphic lipoma in a 48-year-old female presenting clinically as a painless nodule on the buccal mucosa. Microscopically, the lesion showed atypical spindle cells, numerous floret-like giant multinucleated cells, and abundant ropey collagen fibers bundles. Immunohistochemistry showed strong positivity for vimentin and CD34. Mast cell tryptase highlighted numerous mast cells distributed throughout all tumor stroma. S-100 protein, pan-cytokeratin, desmin, α-SMA, EMA, CD68, STAT6, Bcl-2, MDM2, and CDK4 were negative. Conservative surgical excision was carried out, and no recurrence was observed after 13 months of follow-up. Careful histopathological and immunohistochemistry analysis of these lesions is recommended to ensure the correct diagnosis and provide adequate management through a conservative surgical approach. To the best of our knowledge, this is the second case of fat-free pleomorphic lipoma in the oral cavity.

Diagnostic and management challenges for MDM2-, CDK4-negative fatty tumors of the retroperitoneum.

BACKGROUND: Neoplasms of the retroperitoneum that contain a major fat component may represent either benign entities, such as lipomas or angiomyolipomas, or malignancy such as liposarcoma. Distinguishing these diagnoses has important implications for management. While liposarcomas often stain positively for MDM2 and CDK4 proteins, absence of these markers can lead to diagnostic and management challenges. METHODS: We examined three cases in our institution of fat-containing masses of the retroperitoneum that lacked MDM2 and CDK4 markers to highlight the challenges in diagnosing and managing these cases. A thorough review of the literature examining radiologic and histologic features that can be used to determine that diagnosis was conducted and summarized. RESULTS: The three cases we present represent the three main diagnostic entities that can be found in among fatty tumors of the retroperitoneum: lipoma, angiomyolipoma, and liposarcoma. While radiologic features and analysis of histology helped to inform management, these cases in conjunction with the literature also illustrate the limitations of the diagnostic work up and importance also factoring the biologic behavior of the tumor in its management. CONCLUSION: Fat-containing tumors of the retroperitoneum that do not stain for MDM2 or CDK4 can pose a diagnostic challenge. Assessing radiologic and pathologic features in conjunction with the biologic behavior of these tumors should inform their management.

CD10 (neprilysin) expression: a potential adjunct in the distinction of hibernoma from morphologic mimics.

Although the morphologic diagnosis of hibernoma is usually straightforward, some hibernomas have atypical morphologic features, mimicking atypical lipomatous tumors/well-differentiated liposarcomas (ALT/WDLs). In addition, the multivacuolated brown fat cells may be mistaken for lipoblasts by pathologists, especially those without significant soft tissue tumor exposure. Thus, we continue to receive in consultation cases of hibernoma sent for MDM2 fluorescence in situ hybridization testing to exclude ALT/WDL. Testing hibernomas for MDM2 amplification, however, adds cost and delays the final diagnosis. Recently, we have noted expression of neprilysin (CD10, CALLA), a zinc-dependent metalloproteinase involved in the inactivation of various peptide hormones, in brown fat cells, and wished to explore the potential utility of this widely available, inexpensive ancillary test in the differential diagnosis of hibernoma. Formalin-fixed, paraffin-embedded tissue sections from well-characterized cases of hibernoma (n = 48), brown fat (n = 21), ALTs/WDLs (n = 17), pleomorphic liposarcomas (PLPSs) (n = 6), lipomas (n = 5), and fat necrosis (n = 5) were immunostained for CD10, using a commercially available antibody and routine laboratory protocols. CD10 expression was evaluated in both adipocytes and in surrounding stromal cells. The hibernomas occurred in 28 men and 20 women, ranging from 11 to 76 years of age and involved the extremities (n = 25), pelvis (n = 7), abdomen/pelvis/retroperitoneum (n = 7), head and neck region (n = 6), back (n = 2), and chest (n = 1). All showed diffuse, strong CD10 expression in multivacuolated brown fat cells and in the majority of adjacent univacuolated fat cells. Brown adipose tissue from various anatomic structures showed an identical pattern of immunoreactivity. In contrast, CD10 expression was present in the adipocytes of only 3 of 17 (18%) ALTs/WDLs and was absent in lipomas and fat necrosis. Lipoblasts expressed CD10 in 3 PLPSs. Expression of CD10 by surrounding fibroblastic stromal cells was more widespread, present in 13 hibernomas, 10 ALTs/WDLs, 1 instance of fat necrosis, 6 PLPSs, and 4 examples of brown fat. We conclude that immunohistochemistry for CD10 may represent a useful, rapid and inexpensive ancillary test in the differential diagnosis of hibernoma from potential morphologic mimics, especially when morphologic features favor hibernoma. CD10 expression in adipocytes, however, should be rigorously distinguished from fibroblastic stromal cell CD10 expression, a nonspecific finding.

Reduced lipolysis in lipoma phenocopies lipid accumulation in obesity.

BACKGROUND: Elucidation of lipid metabolism and accumulation mechanisms is of paramount importance to understanding obesity and unveiling therapeutic targets. In vitro cell models have been extensively used for these purposes, yet, they do not entirely reflect the in vivo setup. Conventional lipomas, characterized by the presence of mature adipocytes and increased adipogenesis, could overcome the drawbacks of cell cultures. Also, they have the unique advantage of easily accessible matched controls in the form of subcutaneous adipose tissue (SAT) from the same individual. We aimed to determine whether lipomas are a good model to understand lipid accumulation. METHODS: We histologically compared lipomas and control SAT, followed by assessment of the lipidome using high-resolution 1H NMR spectroscopy and ESI-IT mass spectrometry. RNA-sequencing was used to obtain the transcriptome of lipomas and the matched SAT. RESULTS: We found a significant increase of small-size (maximal axis < 70 µm) and very big (maximal axis > 150 µm) adipocytes within lipomas. This suggests both enhanced adipocyte proliferation and increased lipid accumulation. We further show that there is no significant change in the lipid composition compared to matched SAT. To better delineate the pathophysiology of lipid accumulation, we considered two groups with different genetic backgrounds: (1) lipomas with HMGA2 fusions and (2) without gene fusions. To reduce the search space for genes that are relevant for lipid pathophysiology, we focused on the overlapping differentially expressed (DE) genes between the two groups. Gene Ontology analysis revealed that DE genes are enriched in pathways related to lipid accumulation. CONCLUSIONS: We show that the common shared lipid accumulation mechanism in lipoma is a reduction in lipolysis, with most gene dysregulations leading to a reduced cAMP in the adipocyte. Superficial lipomas could thus be used as a model for lipid accumulation through altered lipolysis as found in obese patients.

Neutralization of HSF1 in cells from PIK3CA-related overgrowth spectrum patients blocks abnormal proliferation.

PIK3CA-related overgrowth spectrum is caused by mosaicism mutations in the PIK3CA gene. These mutations, which are also observed in various types of cancer, lead to a constitutive activation of the PI3K/AKT/mTOR pathway, increasing cell proliferation. Heat shock transcription factor 1 (HSF1) is the major stress-responsive transcription factor. Recent findings indicate that AKT phosphorylates and activates HSF1 independently of heat-shock in breast cancer cells. Here, we aimed to investigate the role of HSF1 in PIK3CA-related overgrowth spectrum. We observed a higher rate of proliferation and increased phosphorylation of AKT and p70S6K in mutant fibroblasts than in control cells. We also found elevated phosphorylation and activation of HSF1, which is directly correlated to AKT activation. Specific AKT inhibitors inhibit HSF1 phosphorylation as well as HSF1-dependent gene transcription. Finally, we demonstrated that targeting HSF1 with specific inhibitors reduced the proliferation of mutant cells. As there is currently no curative treatment for PIK3CA-related overgrowth spectrum, our results identify HSF1 as a new potential therapeutic target.

Expression Patterns of Hypoxia-Inducible Factors, Proinflammatory, and Neuroprotective Cytokines in Neuroepithelial Tissues of Lumbar Spinal Lipomas-A Pilot Study.

OBJECTIVE: Lumbosacral lipomas (LSLs), one form of closed spinal dysraphism, are congenital disorders of the terminal spinal cord (SC). Delayed neurologic deterioration often occurs in the subsequent developmental course of the patient. Identifying the cellular and molecular factors underlying the progressive damage to neural structures is a prerequisite for developing treatment strategies for LSLs. METHODS: Nine LSL specimens obtained from the SC/lipoma interface during surgical resection were examined. Normal SC tissue served as a control. Clinical characteristics were obtained, and spinal magnetic resonance imaging was re-evaluated. Cellular marker profiles were established. Immunoreactivity (IR) of hypoxia-inducible factor 1α (HIF-1α/-2α), erythropoietin (Epo)/erythropoietin receptor (EpoR), interleukin-1ß (IL-1ß)/IL-1R1, and tumor necrosis factor α/tumor necrosis factor receptor type 1 were analyzed qualitatively and semiquantitatively by densitometry. Colabeling with cellular markers was determined by multifluorescence labeling. Cytokines were further analyzed by real-time reverse transcription polymerase chain reaction. RESULTS: LSL specimens showed significant gliosis. HIF-1α/HIF-2α-IR and Epo/Epo-IR were found at significantly higher levels in the LSL specimens, as were IL-1ß-/IL-1ß receptor type 1 (IL1-R1) and tumor necrosis factor α/tumor necrosis factor receptor type 1 (P < 0.001), than were the controls. At the messenger RNA level, cytokines appeared partially induced. Double immunofluorescence labeling confirmed the costaining of these factors with inflammatory and glial markers. CONCLUSIONS: The expression of hypoxia-related and inflammatory mediators was shown for the first time in LSL specimens. These factors might play a role in multifactorial secondary lesion cascades underlying further damage to the neural placode in closed dysraphism.

A new human adipocyte model with PTEN haploinsufficiency.

Few human cell strains are suitable and readily available as in vitro adipocyte models. We used resected lipoma tissue from a patient with germline phosphatase and tensin homolog (PTEN) haploinsufficiency to establish a preadipocyte cell strain termed LipPD1 and aimed to characterize cellular functions and signalling pathway alterations in comparison to the established adipocyte model Simpson-Golabi-Behmel-Syndrome (SGBS) and to primary stromal-vascular fraction cells. We found that both cellular life span and the capacity for adipocyte differentiation as well as adipocyte-specific functions were preserved in LipPD1 and comparable to SGBS adipocytes. Basal and growth factor-stimulated activation of the PI3 K/AKT signalling pathway was increased in LipPD1 preadipocytes, corresponding to reduced PTEN levels in comparison to SGBS cells. Altogether, LipPD1 cells are a novel primary cell model with a defined genetic lesion suitable for the study of adipocyte biology.

Diagnostic importance of clinicopathologic features and p16, CD34, MDM2 expression in differential diagnosis of adipocytic tumors.

OBJECTIVE: The aim of this study was to investigate the immunohistochemical stain profiling of adipocytic tumors. METHODS: From our archive files between the years of 2012-2018, excised, formalin-fixed and paraffin-embedded adipocytic tumors were retrospectively screened and 61 subjects were selected. The gender, age, tumor location and tumor diameter were evaluated. The cases were investigated in terms of p16, CD34, MDM2 expression and clinicopathological information. RESULTS: Of the 61 patients included in the study, we found that 2 had hibernoma, 4 had lipoblastoma, 14 had spindle cell lipoma (SCL), 10 had lipoma, 20 had atypical lipomatous tumor/well differentiated liposarcoma (ALT/WDL), and 11 had dedifferentiated liposarcoma (DDL). In terms of diameter, ALT/WDL and DDL were significantly different from the others (p=0.001, p=0.001, respectively). There was a significant difference between the groups according to the location (p=0.001). 35% (7/20) of ALT/WDLs were in the lower extremities (thighs) and 35% (7/20) were located in the retroperitoneal region. 70% of DDLs (7/11) were located in the retroperitoneum. When CD34 expression was evaluated among the groups, a significant difference was observed (p=0.001). CD34 was positive in 92.9% of SCL cases. p16 immunoreactivity was significantly different between the groups (p=0.001). p16 expression was observed in 50.5% of ALT / WDL cases and 79% of DDL cases. CONCLUSION: p16 and CD34 expression are valuable in the differential diagnosis of lipomatous tumors when radiological and clinical considerations do not help to differential diagnosis of adipocytic tumors. LEVEL OF EVIDENCE: Level IV, Therapeutic Study.

Cytoplasmic p16 Is Expressed in Normal Brown Fat and Hibernomas.

White adipose tissue browning has emerged as a putative therapy of obesity, and studies in mice have shown that Cdkn2a is implicated in white-to-brown transition. However, the role of Cdkn2a product p16 has been never studied in human brown fat tissue. The aim of the study is to investigate the expression of p16 in normal brown fat and in hibernoma, a lipoma containing brown fat-like adipocytes. Ten normal brown fat tissues and 5 hibernomas were immunohistochemically studied for p16 expression. Nearby white adipose tissue was used for comparison. All brown fat and hibernomas specimens express p16 in a cytoplasmic manner. Neighboring white adipose tissue is negative for p16 expression. Thus, cytoplasmic p16 may be associated with fat tissue browning.

Cutaneous spindle cell adenolipoma with eccrine and apocrine differentiation.

Cutaneous spindle cell adenolipoma (SCAL) is a recently described rare variant of lipoma with 11 cases reported to date. Here we report a consultation case of a 77-year-old male who presented with a nodule on the right nasolabial fold, diagnosed as apocrine fibroadenoma or sebaceous hyperplasia by an outside pathologist. The specimen revealed an ill-defined dermal tumor composed of mature adipocytes, bland spindle cells, ropey collagen, and dilated eccrine and apocrine glands and ducts in a fibromyxoid stroma. The spindle cells were positive for CD34 and negative for S100 protein and SOX10. These findings are consistent with those of cutaneous SCAL. The pathogenesis of this entity is controversial and includes a hamartomatous process, derivation from adipose tissue surrounding eccrine glands, or preexisting glands entrapment within a growing lipoma. In the present case, the glandular component is extensive and includes both eccrine and apocrine differentiation, which has not been previously described and further supports the hamartomatous nature. Awareness of this rare entity is helpful to prevent confusion with other look-alike primary and metastatic cutaneous lesions.