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BCOR-CCNB3 fusions are frequent in undifferentiated sarcomas of male children.

Peters TL, Kumar V, Polikepahad S, Lin FY, Sarabia SF, Liang Y, Wang WL, Lazar AJ, Doddapaneni H, Chao H, Muzny DM, Wheeler DA, Okcu MF, Plon SE, Hicks MJ, López-Terrada D, Parsons DW, Roy A - Mod. Pathol. (2014)

Bottom Line: RNA-seq results were confirmed through direct RT-PCR of tumor RNA and cloning of the genomic breakpoints from tumor DNA.Five of the six tumors were soft-tissue lesions with either predominant spindle-cell morphology or spindle-cell areas interspersed with ovoid to round cells.CCNB3 immunohistochemistry showed strong nuclear positivity in five tumors before oncologic therapy, but was patchy to negative in post-treatment tumor samples.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Pathology, Texas Children's Hospital, Houston, TX, USA [2] Department of Pathology & Immunology, Baylor College of Medicine, Houston, TX, USA.

ABSTRACT
The BCOR-CCNB3 fusion gene, resulting from a chromosome X paracentric inversion, was recently described in translocation-negative 'Ewing-like' sarcomas arising in bone and soft tissue. Genetic subclassification of undifferentiated unclassified sarcomas may potentially offer markers for reproducible diagnosis and substrates for therapy. Using whole transcriptome paired-end RNA sequencing (RNA-seq) we unexpectedly identified BCOR-CCNB3 fusion transcripts in an undifferentiated spindle-cell sarcoma. RNA-seq results were confirmed through direct RT-PCR of tumor RNA and cloning of the genomic breakpoints from tumor DNA. Five additional undifferentiated sarcomas with BCOR-CCNB3 fusions were identified in a series of 42 pediatric and adult unclassified sarcomas. Genomic breakpoint analysis demonstrated unique breakpoint locations in each case at the DNA level even though the resulting fusion mRNA was identical in all cases. All patients with BCOR-CCNB3 sarcoma were males diagnosed in mid childhood (7-13 years of age). Tumors were equally distributed between axial and extra-axial locations. Five of the six tumors were soft-tissue lesions with either predominant spindle-cell morphology or spindle-cell areas interspersed with ovoid to round cells. CCNB3 immunohistochemistry showed strong nuclear positivity in five tumors before oncologic therapy, but was patchy to negative in post-treatment tumor samples. An RT-PCR assay developed to detect the fusion transcript in archival formalin-fixed tissue was positive in all six cases, with high sensitivity and specificity in both pre- and post-treated samples. This study adds to recent reports on the clinicopathologic spectrum of BCOR-CCNB3 fusion-positive sarcomas, a newly emerging entity within the undifferentiated unclassified sarcoma category and describes a simple RT-PCR assay that in conjunction with CCNB3 immunohistochemistry can be useful in diagnosing these tumors.

No MeSH data available.


Related in: MedlinePlus

CCNB3 expression in BCOR-CCNB3 positive sarcomas. Nuclear CCNB3 immunopositivity is strong and diffuse (a, b, c, and e), strong but patchy (d) and negative in T149 (f). CCNB3 expression in spermatocytes (g) serves as a control. A CIC-rearranged small round cell tumor is expectedly negative (h); however, strong patchy nuclear expression is seen in a Ewing sarcoma tumor (i). Scale bars, 100 um.
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Figure 4: CCNB3 expression in BCOR-CCNB3 positive sarcomas. Nuclear CCNB3 immunopositivity is strong and diffuse (a, b, c, and e), strong but patchy (d) and negative in T149 (f). CCNB3 expression in spermatocytes (g) serves as a control. A CIC-rearranged small round cell tumor is expectedly negative (h); however, strong patchy nuclear expression is seen in a Ewing sarcoma tumor (i). Scale bars, 100 um.

Mentions: Immunohistochemistry performed as part of the diagnostic work-up showed no specific reproducible immunophenotype. CD99 staining was weak to negative in all tumors. Staining for CCNB3, however, showed strong and diffuse nuclear positivity along with patchy cytoplasmic staining in 5 tumors (Figure 4). In one tumor diagnosed in 1993 (T149), the pre-treatment biopsy specimen stained only patchily with the CCNB3 antibody, and the post-treatment specimen was completely negative. In two other cases (T150, T236) with strong CCNB3 staining pretreatment, the post-treatment resection specimens were only patchily positive or negative. In 3 negative controls tested (2 Ewing sarcomas and 1 CIC-rearranged sarcoma), CCNB3 staining was either absent (Figure 4h) or patchy cytoplasmic, although nuclear expression could be focally seen in one Ewing sarcoma (Figure 4i).


BCOR-CCNB3 fusions are frequent in undifferentiated sarcomas of male children.

Peters TL, Kumar V, Polikepahad S, Lin FY, Sarabia SF, Liang Y, Wang WL, Lazar AJ, Doddapaneni H, Chao H, Muzny DM, Wheeler DA, Okcu MF, Plon SE, Hicks MJ, López-Terrada D, Parsons DW, Roy A - Mod. Pathol. (2014)

CCNB3 expression in BCOR-CCNB3 positive sarcomas. Nuclear CCNB3 immunopositivity is strong and diffuse (a, b, c, and e), strong but patchy (d) and negative in T149 (f). CCNB3 expression in spermatocytes (g) serves as a control. A CIC-rearranged small round cell tumor is expectedly negative (h); however, strong patchy nuclear expression is seen in a Ewing sarcoma tumor (i). Scale bars, 100 um.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4385430&req=5

Figure 4: CCNB3 expression in BCOR-CCNB3 positive sarcomas. Nuclear CCNB3 immunopositivity is strong and diffuse (a, b, c, and e), strong but patchy (d) and negative in T149 (f). CCNB3 expression in spermatocytes (g) serves as a control. A CIC-rearranged small round cell tumor is expectedly negative (h); however, strong patchy nuclear expression is seen in a Ewing sarcoma tumor (i). Scale bars, 100 um.
Mentions: Immunohistochemistry performed as part of the diagnostic work-up showed no specific reproducible immunophenotype. CD99 staining was weak to negative in all tumors. Staining for CCNB3, however, showed strong and diffuse nuclear positivity along with patchy cytoplasmic staining in 5 tumors (Figure 4). In one tumor diagnosed in 1993 (T149), the pre-treatment biopsy specimen stained only patchily with the CCNB3 antibody, and the post-treatment specimen was completely negative. In two other cases (T150, T236) with strong CCNB3 staining pretreatment, the post-treatment resection specimens were only patchily positive or negative. In 3 negative controls tested (2 Ewing sarcomas and 1 CIC-rearranged sarcoma), CCNB3 staining was either absent (Figure 4h) or patchy cytoplasmic, although nuclear expression could be focally seen in one Ewing sarcoma (Figure 4i).

Bottom Line: RNA-seq results were confirmed through direct RT-PCR of tumor RNA and cloning of the genomic breakpoints from tumor DNA.Five of the six tumors were soft-tissue lesions with either predominant spindle-cell morphology or spindle-cell areas interspersed with ovoid to round cells.CCNB3 immunohistochemistry showed strong nuclear positivity in five tumors before oncologic therapy, but was patchy to negative in post-treatment tumor samples.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Pathology, Texas Children's Hospital, Houston, TX, USA [2] Department of Pathology & Immunology, Baylor College of Medicine, Houston, TX, USA.

ABSTRACT
The BCOR-CCNB3 fusion gene, resulting from a chromosome X paracentric inversion, was recently described in translocation-negative 'Ewing-like' sarcomas arising in bone and soft tissue. Genetic subclassification of undifferentiated unclassified sarcomas may potentially offer markers for reproducible diagnosis and substrates for therapy. Using whole transcriptome paired-end RNA sequencing (RNA-seq) we unexpectedly identified BCOR-CCNB3 fusion transcripts in an undifferentiated spindle-cell sarcoma. RNA-seq results were confirmed through direct RT-PCR of tumor RNA and cloning of the genomic breakpoints from tumor DNA. Five additional undifferentiated sarcomas with BCOR-CCNB3 fusions were identified in a series of 42 pediatric and adult unclassified sarcomas. Genomic breakpoint analysis demonstrated unique breakpoint locations in each case at the DNA level even though the resulting fusion mRNA was identical in all cases. All patients with BCOR-CCNB3 sarcoma were males diagnosed in mid childhood (7-13 years of age). Tumors were equally distributed between axial and extra-axial locations. Five of the six tumors were soft-tissue lesions with either predominant spindle-cell morphology or spindle-cell areas interspersed with ovoid to round cells. CCNB3 immunohistochemistry showed strong nuclear positivity in five tumors before oncologic therapy, but was patchy to negative in post-treatment tumor samples. An RT-PCR assay developed to detect the fusion transcript in archival formalin-fixed tissue was positive in all six cases, with high sensitivity and specificity in both pre- and post-treated samples. This study adds to recent reports on the clinicopathologic spectrum of BCOR-CCNB3 fusion-positive sarcomas, a newly emerging entity within the undifferentiated unclassified sarcoma category and describes a simple RT-PCR assay that in conjunction with CCNB3 immunohistochemistry can be useful in diagnosing these tumors.

No MeSH data available.


Related in: MedlinePlus