Clinical value of fluorescence in situ hybridization with MDM2 and DDIT3 probe in diagnosis of liposarcoma / 北京大学学报(医学版)

OBJECTIVE@#To investigate the value of using MDM2 amplification probe and DDIT3 dual-color, break-apart rearrangement probe fluorescence in situ hybridization (FISH) technique in the diagnosis of liposarcoma.@*METHODS@#In the study, 62 cases of liposarcoma diagnosed in Peking University First Hospital from January 2015 to December 2019 were analysed for clinicopathological information. Of these 62 cases of liposarcoma, all were analysed for MDM2 amplification and 48 cases were analysed for DDIT3 rearrangement using a FISH technique. Our study aimed to evaluate the status of MDM2 and DDIT3 by FISH in liposarcoma and correlate it with diagnosis of different subtypes of liposarcoma. The subtypes of liposarcoma were classified according to the FISH results, combined with the relevant clinicopathological features.@*RESULTS@#The patients aged 31-89 years (mean: 59 years) with a 1.75:1 male to female ratio. Histologically, there were 20 cases of atypical lipomatous tumour/well-differentiated liposarcoma (ALT/WDLPS), 26 cases of dedifferentiated liposarcoma (DDLPS), 13 myxoid liposarcoma (MLPS) and 3 pleomorphic liposarcoma (PLPS). Tumors with DDLPS (23/26) and WDLPS (8/20) were localized retroperitoneally, while both tumours of MLPS and PLPS were localized extra-retroperitoneally, and the difference of sites among the four subtypes of liposarcoma was statistically significant (P < 0.05). Histologically, varied mucoid matrix could be observed in the four subtypes of liposarcoma, and the difference was statistically significant (P < 0.05). MDM2 gene amplification was demonstrated in all cases of ALT/WDLPS and DDLPS (100%, 20/20 and 26/26 respectively); DDIT3 gene rearrangement was noted only in MLPS (100%, 13/13); most cases of DDLPS (96.2%, 25/26) and ALT/WDLPS (83.3%, 5/6, 6 cases selected for detection) demonstrated the picture of amplification of the DDIT3 telomeric tag. According to the instructions of DDIT3 break-apart rearrangement probe, the 5' telomere probe and 3' centromere probe spanned but did not cover the DDIT3 gene itself, on the contrary, the 5' telomere probe covered the CDK4 gene, while the DDIT3 and CDK4 gene were located adjacent to each other on chromosome, therefore, when the amplification signal appeared on the telomeric tag of the DDIT3 rearrangement probe, it indeed indicated the CDK4 gene amplification rather than the DDIT3 gene rearrangement. Then the 10 cases with DDIT3 telomeric tag amplification were selected for CDK4 and DDIT3 gene amplification probe FISH tests, and all the cases showed CDK4 gene amplification (100%, 10/10) and two of the 10 cases demonstrated co-amplification of CDK4 and DDIT3 (20%, 2/10); DDIT3 polysomy detected by DDIT3 gene rearrangement probe was found in 1 case of DDLPS and 2 cases of PLPS (66.7%, 2/3) with morphology of high-grade malignant tumour and poor prognosis.@*CONCLUSION@#Our results indicate that a diagnosis of different subtype liposarcoma could be confirmed based on the application of MDM2 and DDIT3 FISH, combined with clinicopathological findings. It is also noteworthy that atypical signals should be correctly interpreted to guide correct treatment of liposarcomas.

Protective effects of EGCG against methylation changes induced by low dose radiation / 中华放射医学与防护杂志

Objective To investigate the role of epigallocatechin gallate ( EGCG) in reversing the CpG island methylation of Rad23b and Ddit3 gene promoter and its mRNA expression induced by 0?5 Gy X-rays. Methods Thirty BALB/c male mice were randomly divided into 6 groups: control group, irradiation group, low/high dose of EGCG group, low/high dose of EGCG with irradiation group. For the irradiation group, mice were fractionally exposed with 6 MV X-rays for 10 d (0?05 Gy/d × 10 d). 2 hours after the final irradiation, all mice were killed and such tissues as blood, kidney, liver, spleen, brain, and lung were collected. Methylation and expression levels of Rad23b and Ddit3 were measured by bisulfate sequencing primers ( BSP) and Real-time PCR, respectively. Results Compare to the control group, Rad23b was hypermethylated in PBMC, liver, spleen, brain and lung (t= -20?19, -14?80, -12?05,-28?42, -12?58, P<0?05) in the irradiation group. Meanwhile, its mRNA expression level was down-regulated in PBMC, liver, brain and lung (t=25?25, 17?43, 11?53, 22?85, P<0?05). Similarly, a significant hypermethylation change of Ddit3 was observed in PBMC, liver and lung after irradiation ( t=-52?89, -20?31, -3?85, P<0?05) so that the mRNA expression of Ddit3 decreased in PBMC and liver ( t = 11?89, 16?52, P < 0?05 ). Compared to the irradiation group, EGCG with different concentrations of 10, 20 mg/kg significantly reduced the methylation level of Rad23b and Ddit3 ( t =-13?39-7?99, P<0?05), and induced re-expression of mRNA (t= -34?02 - -2?89, P<0?05). This change was more notable in the irradiation group with the high dose of EGCG. Conclusions As a natural drug, EGCG may play an important role in affecting DNA methylation and hence protects DNA from radiation damage.

Diagnostic Value of MDM2 and DDIT3 Fluorescence In Situ Hybridization in Liposarcoma Classification: A Single-Institution Experience

BACKGROUND: The amplification of murine double minutes (MDM2) is the primary feature of well-differentiated liposarcomas (WDLPS) and dedifferentiated liposarcomas (DDLPS), while DDIT3 rearrangement is the main one of myxoid liposarcomas (MLPS). Our aim was to evaluate the added value of MDM2 amplification and DDIT3 rearrangement in making a diagnosis and classifying lipogenic tumors. METHODS: Eighty-two cases of liposarcoma and 60 lipomas diagnosed between 1995 and 2010 were analysed for MDM2 amplification and DDIT3 rearrangement using a fluorescence in situ hybridization (FISH). The subtypes of liposarcoma were reclassified according to the molecular results, whose results were reviewed with an analysis of the relevant histologic and immunohistochemical findings. RESULTS: One case of lipoma (1.67%) was reclassified as a WDLPS. Of the liposarcomas, 13.4% (16/82) were reclassified after the molecular testing. Five cases of MLPS were reclassified as four cases of DDLPS and one case of myxoid lipoma. Two cases of WDLPS were reclassified as one case of spindle cell lipoma and another case of myxofibrosarcoma. Four cases of DDLPS were reclassified as two cases of leiomyosarcoma, one case of angiomyolipoma and another case of fibroinflammatory lesion. Of the six cases of pleomorphic liposarcoma, five were reclassified as DDLPS. CONCLUSIONS: In our series, a critical revision of diagnosis was found at a rate of 3.5% (5/142) after a review of the lipomatous lesions. The uses of molecular testing by MDM2 and DDIT3 FISH were valuable to make an accurate subtyping of liposarcomas as well as to differentiate WDLPS from benign lipomatous tumor.