c-myc overexpression is not mandatory in aggressive-phase multiple myeloma with Burkitt's type translocation

Bcl-2 is a better therapeutic target than c-Myc, but attacking both could be a more effective treatment strategy for B-cell lymphoma with concurrent Bcl-2 and c-Myc overexpression

OBJECTIVE

The prognosis for diffuse large B-cell lymphomas with concomitant overexpression of c-Myc and Bcl-2 remains dismal; there is an urgent need to clarify the significance of these two oncogenes as therapeutic targets for a more effective treatment strategy.

MATERIALS AND METHODS

We established two novel cell lines, KPUM-MS3 and KPUM-UH1, from two chemoresistant patients with diffuse large B-cell lymphomas with concomitant overexpression of c-Myc and Bcl-2, and investigated the significance of c-Myc and Bcl-2 as therapeutic targets.

RESULTS

KPUM-MS3 possesses t(14;18)(q32;q21) chromosomal translocation and KPUM-UH1 bcl-2 gene amplification, both of which account for Bcl-2 overexpression. Chromosomal translocation t(8;14)(q24;q34) was found to coexist only in KPUM-UH1, overexpression of pvt-1 messenger RNA was detected only in KPUM-MS3, and reduced expression of miR-143 and miR-145 was identified in both. Working together, these abnormalities can contribute to c-Myc overexpression. Using ABT-263, an inhibitor for Bcl-2, and 10058-F4, an inhibitor for c-Myc, we found that both cell lines were more highly sensitive to cell death as a result of Bcl-2 inhibition than of c-Myc inhibition. When combined with genotoxic agents, ABT-263 exerted additive and/or synergistic cell-killing effects, while 10058-F4 showed, at most, a modest combinatory effect. Importantly, the combination of ABT-263 and 10058-F4 had a synergistic cell-killing effect on both cell lines.

CONCLUSIONS

Our data suggest that Bcl-2 is a better therapeutic target than c-Myc, but attacking both Bcl-2 and c-Myc would be an even more effective treatment strategy for diffuse large B-cell lymphomas with concurrent Bcl-2 and c-Myc overexpression.

Fine-needle aspiration cytology of a case of HIV-associated anaplastic myeloma

Plasma cell neoplasia occurs much less frequently than high-grade B-cell non-Hodgkins lymphoma in HIV-infected patients, but is nevertheless an AIDS-associated malignancy. In this report, we describe the fine-needle aspiration (FNA) findings of a mass in the left parotid region with plasmablastic features that occurred in a 41-yr-old HIV-infected homosexual man whom we diagnosed as having anaplastic myeloma. The patient had normochromic, normocytic anemia with a hematocrit of 21%, a white blood count of 2.2 x 10(9)/l with 76% neutrophils, and a CD4 count of 31%. He also had elevated levels of calcium (13.2 mg/dl), alkaline phosphatase (25,400 IU/l), blood urea nitrogen (2,600 mg/dl), and creatinine (2.5 mg/dl). Serum protein electrophoresis showed polyclonal hypergammaglobulinemia without any monoclonal component. A bone survey revealed multiple punched-out lytic lesions. FNA smears showed large plasmacytoid cells with eccentrically placed nuclei, prominent nucleoli, and moderate amounts of basophilic cytoplasm. By immunocytochemical staining, tumor cells were negative for CD19, CD20, and leukocyte-common antigen (LCA), but strongly positive for CD38 and kappa light chain. Anaplastic myeloma and plasmablastic lymphoma were considered in the differential diagnosis. Although the cytomorphologic and immunophenotypic findings of our case overlapped with those of plasmablastic lymphoma, the pattern of bone involvement with punched-out lytic lesions and absence of localization of the tumor to the mucosa of the oral cavity led us to a diagnosis of anaplastic myeloma. The patient initially received antiretroviral therapy followed by thalidomide and pulse dexamethasome therapy, but his response was poor. His HIV load increased, and his malignancy rapidly progressed with the development of multiple vertebral lesions, extraosseous extension, and eventually cord compression. He died of the disease less than 2 mo after presentation.