Oncogenic Property of Acrogranin in Human Uterine Leiomyosarcoma: Direct Evidence of Genetic Contribution in In vivo Tumorigenesis

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Abstract
To identify potential oncogenes that contribute to the development of uterine leiomyosarcoma, we conducted a cDNA microarray analysis between normal uterine smooth muscle and uterine leiomyosarcoma. We found that acrogranin (also named PCDGF or progranulin) is overexpressed in uterine leiomyosarcoma. With immunohistochemical staining of 12 leiomyosarcoma cases, we verified acrogranin expression in tumor cells. Furthermore, the intensity of acrogranin expression correlated with high histologic grade and poor prognosis. To directly analyze the oncogenic properties of acrogranin, we established an immortalized uterine smooth muscle cell line by transfection of human telomerase reverse transcriptase into primary culture. This cell line retained the original characteristics of uterine smooth muscle cells, including spindle-shaped extension as well as expression of vimentin, estrogen receptor α, progesterone receptor, and α smooth muscle actin. Transfection of acrogranin into the immortalized uterine smooth muscle cells resulted in colony formation in soft agar, but the diameter of the colonies did not exceed 100 μm. Transfection of both acrogranin and SV40 early region (SV40ER) into the immortalized uterine smooth muscle cells resulted in an increased number of colonies and increased colony size in soft agar versus transfection of SV40ER alone. We show that only immortalized uterine smooth muscle cells expressing both acrogranin and SV40ER are capable of tumor formation in nude mice. Thus, acrogranin is overexpressed in uterine leiomyosarcoma cells, particularly in high-grade cases, and forced expression of acrogranin in immortalized uterine smooth muscle cells contributes to malignant transformation, which suggest that acrogranin plays an important role in the pathogenesis of uterine leiomyosarcoma.