Aberrant calreticulin expression is involved in the dedifferentiation of dedifferentiated liposarcoma.

[dedifferentiated liposarcoma]

Liposarcomas are a representative group of soft tissue sarcomas with variably hampered adipogenesis , which is most exemplified by its dedifferentiated subtype . However , the factor (s ) responsible for inhibiting adipocyte differentiation remains unknown . A recent gene expression profiling study identified several unique genes that were highly expressed in dedifferentiated liposarcoma , and the gene encoding calreticulin (CALR ), a major Ca (2 +)-buffering protein that can inhibit adipocyte differentiation , was found to be overexpressed . Thus , we investigated the expression of calreticulin in 45 cases of liposarcomas , including 15 dedifferentiated tumors , at both the protein and mRNA levels . Immunohistochemically , calreticulin was consistently expressed in the dedifferentiated areas of dedifferentiated liposarcomas and commonly observed in atypical stromal cells and /or lipoblasts in the well-differentiated areas (87 %), whereas large vacuolated adipocytic cells in either the tumors or normal fat were essentially negative . These results were further supported by the findings of Western blot and quantitative RT-PCR analyses . Although abnormalities in 19 p 13 .1 -13 .2 where CALR is localized were uncommon in the dedifferentiated liposarcomas examined by fluorescence in situ hybridization , expression of miR-1257 , a putative microRNA that targets calreticulin , was suppressed in the dedifferentiated subtype . The down-regulation of calreticulin by small -interfering RNA could induce adipogenesis in dedifferentiated liposarcoma cells and reduce cell proliferation . Our results therefore suggest that aberrantly expressed calreticulin in dedifferentiated liposarcoma is involved in its dedifferenitation and /or tumor progression .

Diseases
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Diseases presenting "and the gene encoding calreticulin" symptom

dedifferentiated liposarcoma

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