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. 2009 Dec 15;23(24):2839–2849. doi: 10.1101/gad.1861409

Figure 2.

Figure 2.

Eμ-myc/17-19 and Eμ-myc/19b lymphomas have similar pathological and immunological features. (A) Eμ-myc/19b lymphomas are highly invasive. H&E staining of the liver, lung, and kidney showed aggressive invasion by Eμ-myc/19b tumor cells, which was highly analogous to that of the Eμ-myc/19a/20a/19b lymphomas. In particular, both perivascular and parenchymal invasion of the liver were observed. (B) Overexpression of miR-19b represses c-myc-induced apoptosis. The Eμ-myc/19b and Eμ-myc/19a/20a/19b lymphomas had similar proliferation rates to those of Eμ-myc/MSCV controls, demonstrated by Ki67 staining. However, exogenous expression of miR-19b or mir-19a/20/19b greatly decreased apoptosis in the Eμ-myc tumors, confirmed by TUNEL and H&E staining of Eμ-myc/17-19 lymph node tumors. The “starry sky” morphology of cell clusters undergoing apoptosis (black arrows), a hallmark of Eμ-myc/MSCV lymphomas, was absent in Eμ-myc/19b and Eμ-myc/19a/20a/19b tumors. (C) miR-19b and mir-17-19b preferably transform progenitor B cells. Flow cytometric immunophenotyping of representative Eμ-myc, Eμ-myc/17-19, and Eμ-myc/19 lymphomas. While the majority of Eμ-myc tumors consisted of CD19-positive and IgM-positive B cells, the Eμ-myc/19b and Eμ-myc/17-19 tumor cells bore cellular characteristics of progenitor B cells, positive for CD19 but not for surface IgM.