Background: Extraskeletal Ewing sarcoma (EES)/primitive neuroectodermal tumours (PNET) are rare soft tissue sarcomas. Prognostic factors and optimal therapy are still unconfirmed. Materials and Methods: We performed a retrospective analysis on patients to explore the clinic characteristics and prognostic factors of this rare disease. A total of 37 patients older than 15 years referred to our institute from Jan., 2002 to Jan., 2012 were reviewed. The characteristics, treatment and outcome were collected and analyzed. Results: The median age was 28 years (range 15-65); the median size of primary tumours was 8.2 cm (range 2-19). Sixteen patients (43%) had metastatic disease at the initial presentation. Wide surgical margins were achieved in 14 cases (38%). Anthracycline or platinum-based chemotherapy was performed on 29 patients (74%). Radiotherapy was delivered in 13 (35%). At a median follow-up visit of 24 months (range 2-81), the media event-free survival (EFS) and overall survival (OS) were 15.8 and 30.2 months, respectively. The 3-year EFS and OS rates were 24% and 43%, respectively. Metastases at presentation and wide surgical margins were significantly associated with OS and EFS. Tumour size was significantly associated with OS but not EFS. There were no significant differences between anthracycline and platinum based chemotherapy regarding EFS and OS. Conclusions: EES/PNET is a malignant tumour with high recurrence and frequent distant metastasis. Multimodality therapy featuring wide surgical margins, aggressive chemotherapy and adjuvant local radiotherapy is necessary for this rare disease. Platinum-based chemotherapy can be used as an adjuvant therapy.

Dysregulation of protein posttranslational modification (PTM) can lead to a variety of pathological processes, such as abnormal sperm development, malignant tumorigenesis, depression, and aging process. SIRT7 is a NAD+-dependent protein deacetylase. Besides known deacetylation, SIRT7 may also have the capacity to remove other acylation. However, the roles of SIRT7-induced other deacylation in aging are still largely unknown. Here, we found that the expression of SIRT7 was significantly increased in senescent fibroblasts and aged tissues. Knockdown or overexpression of SIRT7 can inhibit or promote fibroblast senescence. Knockdown of SIRT7 led to increased pan-lysine crotonylation (Kcr) levels in senescent fibroblasts. Using modern mass spectrometry (MS) technology, we identified 5,149 Kcr sites across 1,541 proteins in senescent fibroblasts, and providing the largest crotonylome dataset to date in senescent cells. Specifically, among the identified proteins, we found SIRT7 decrotonylated PHF5A, an alternative splicing (AS) factor, at K25. Decrotonylation of PHF5A K25 contributed to decreased CDK2 expression by retained intron (RI)-induced abnormal AS, thereby accelerating fibroblast senescence, and supporting a key role of PHF5A K25 decrotonylation in aging. Collectively, our data revealed the molecular mechanism of SIRT7-induced k25 decrotonylation of PHF5A regulating aging and provide new ideas and molecular targets for drug intervention in cellular aging and the treatment of aging-related diseases, and indicating that protein crotonylation has important implications in the regulation of aging progress.