BACKGROUND: Multiple myeloma (MM) is a heterogeneous and ultimately fatal disease. Risk stratification using prognostic biomarkers is crucial to individualize treatments. We sought to investigate the role of CD99, a transmembrane protein highly expressed in many hematopoietic cells including subpopulations of normal and neoplastic plasma cells, for MM risk stratification. METHODS: CD99 expression was measured in paraffin samples of bone marrow and extramedullary biopsies of 170 patients with MM. Patients were divided into those with high score (moderately and strongly positive) and low score (negative and weakly positive), with all staining being cytoplasmic and/or membranous. RESULTS: High anti-CD99 immunostaining was observed in 72 of 136 (52.9%) bone marrow biopsies and 24 of 87 (27.6%) extramedullary biopsies in MM. High CD99 expression of extramedullary specimens was associated with significantly longer overall survival (OS; p=.016). High CD99 expression of extramedullary specimens was also associated with better prognosis in the nonautologous stem cell transplantation group of MM patients (p=.044). In multivariate analysis, International Staging System stage was an independent prognostic factor, whereas CD99 expression was no longer statistically significant. CONCLUSIONS: Expression of CD99 in extramedullary specimens was correlated with longer OS, suggesting that CD99 may be a helpful immunohistochemical marker for risk stratification.
Biomarkers ; Biopsy ; Bone Marrow ; Cytoplasm ; Humans ; Multiple Myeloma* ; Multivariate Analysis ; Paraffin ; Plasma Cells ; Prognosis ; Stem Cell Transplantation

CD99 signaling is crucial to a diverse range of biological functions including survival and proliferation. CD99 engagement is reported to augment activator protein-1 (AP-1) activity through mitogen-activated protein (MAP) kinase pathways in a T-lymphoblastic lymphoma cell line Jurkat and in breast cancer cell lines. In this study, we report that CD99 differentially regulated AP-1 activity in the human myeloma cell line RPMI8226. CD99 was highly expressed and the CD99 engagement led to activation of the MAP kinases, but suppressed AP-1 activity by inducing the expression of basic leucine zipper transcription factor, ATF-like (BATF), a negative regulator of AP-1 in RPMI8226 cells. By contrast, engagement of CD99 enhanced AP-1 activity and did not change the BATF expression in Jurkat cells. CD99 engagement reduced the proliferation of RPMI8226 cells and expression of cyclin 1 and 3. Overall, these results suggest novel CD99 functions in RPMI8226 cells.
Breast Neoplasms ; Cell Line* ; Cyclins ; Humans* ; Jurkat Cells ; Leucine Zippers ; Lymphoma ; Multiple Myeloma* ; Phosphotransferases ; Transcription Factor AP-1* ; Transcription Factors

Background and Objectives: MYC, also known as an oncogenic reprogramming factor, is a multifunctional transcription factor that maintains induced pluripotent stem cells (iPSCs). Although MYC is frequently upregulated in various cancers and is correlated with a poor prognosis, MYC is downregulated and correlated with a good prognosis in lung adenocarcinoma. MYC and two other MYC family genes, MYCN and MYCL, have similar structures and could contribute to tumorigenic conversion both in vitro and in vivo. Methods: and Results: We systematically investigated whether MYC family genes act as prognostic factors in various human cancers. We first evaluated alterations in the expression of MYC family genes in various cancers using the Oncomine and The Cancer Genome Atlas (TCGA) database and their mutation and copy number alterations using the TCGA database with cBioPortal. Then, we investigated the association between the expression of MYC family genes and the prognosis of cancer patients using various prognosis databases. Multivariate analysis also confirmed that co-expression of MYC/MYCL/MYCN was significantly associated with the prognosis of lung, gastric, liver, and breast cancers. Conclusions Taken together, our results demonstrate that the MYC family can function not only as an oncogene but also as a tumor suppressor gene in various cancers, which could be used to develop a novel approach to cancer treatment.

Background and Objectives: Flavonoids form the largest group of plant phenols and have various biological and pharma-cological activities. In this study, we investigated the effect of a flavonoid, 3, 4’-dihydroxyflavone (3, 4’-DHF) on osteogenic differentiation of equine adipose-derived stromal cells (eADSCs). Methods: and Results: Treatment of 3, 4’-DHF led to increased osteogenic differentiation of eADSCs by increasing phosphorylation of ERK and modulating Reactive Oxygen Species (ROS) generation. Although PD98059, an ERK inhibitor, suppressed osteogenic differentiation, another ERK inhibitor, U0126, apparently increased osteogenic differentiation of the 3, 4’-DHF-treated eADSCs, which may indicate that the effect of U0126 on bone morphogenetic protein signaling is involved in the regulation of 3, 4’-DHF in osteogenic differentiation of eADSCs. We revealed that 3, 4’-DHF could induce osteogenic differentiation of eADSCs by suppressing ROS generation and co-treatment of 3, 4’-DHF, U0126, and/or N-acetyl cysteine (NAC) resulted in the additive enhancement of osteogenic differentiation of eADSCs. Conclusions Our results showed that co-treatment of 3, 4’-DHF, U0126, and/or NAC cumulatively regulated osteo-genesis in eADSCs, suggesting that 3, 4’-DHF, a flavonoid, can provide a novel approach to the treatment of osteoporosis and can provide potential therapeutic applications in therapeutics and regenerative medicine for human and companion animals.