The Expression of Perilipin Family Proteins can be used as Diagnostic Markers of Liposarcoma and to Differentiate Subtypes

Objective: Liposarcoma is a mesenchymal malignant tumor characterized by adipocyte differentiation which is divided into four subtypes with different prognosis. Accurate histopathological diagnosis is essential for precise treatment. Perilipins, including PLIN1, PLIN2, PLIN3, PLIN4, PLIN5, is a family of lipid droplet-associated proteins that participate in lipid metabolism regulation. The role that perilipins play in sarcomas is not clear. This study aims to assess perilipins expression in subtypes of liposarcoma and various non-lipomatous sarcomas. Methods: A large set of 245 soft tissue sarcoma paraffin-embedded samples including 66 liposarcomas and 179 non-lipomatous sarcomas were collected for tissue microarray and immunohistochemistry to assess perilipins expression. Results: PLIN1 expression was shown in most liposarcomas (41/66) and was absent in non-lipomatous sarcomas (0/179). PLIN4 expression was shown in some liposarcomas (21/66) and was almost negative in non-lipomatous sarcomas (2/179). PLIN1 and PLIN4 expressions in liposarcoma were higher (both P<0.001) than those in non-lipomatous sarcoma. Both PLIN1 and PLIN4 also had a significant difference in liposarcoma subtypes (both P<0.001). PLIN2, PLIN3 and PLIN5 were widely expressed in liposarcomas, rhabdomyosarcomas, leiomyosarcomas, dermatofibrosarcoma protuberans, undifferentiated sarcomas, fibrosarcomas, Ewing's sarcomas and epithelioid sarcomas. PLIN2, PLIN3 and PLIN5 expressions were significantly different among non-lipomatous sarcoma (all P<0.01). Except for PLIN3, the expression of the other four perilipin members in liposarcoma was pairwise related. Conclusions: PLIN1 and PLIN4 can be used as diagnostic markers of liposarcoma and to differentiate liposarcoma subtypes. The combined application of whole perilipin family immunohistochemistry may help to distinguish differently differentiated sarcomas.