Interleukin-21 (IL-21) is a recently cloned cytokine with homology to IL-2, IL-4, and IL-15. In this study we examined the effects of IL-21 on human myeloma cells. We found that IL-21 induced proliferation and inhibited apoptosis of the IL-6–dependent human myeloma cell lines ANBL-6, IH-1, and OH-2. The potency of IL-21 was close to that of IL-6 in the OH-2 cell line. Neutralizing antibodies to IL-6 or the IL-6 receptor transducer chain (gp130) did not affect IL-21–induced DNA synthesis, indicating that IL-21–induced proliferation was not mediated through these proteins. Tumor necrosis factor (TNF), another stimulator of myeloma cell growth, up-regulated the expression level of IL-21 receptor (IL-21R), and combinations of TNF and IL-21 gave synergistic effects on myeloma cell proliferation. Furthermore, 4 of 9 purified samples of primary myeloma cells showed a significant increase in DNA synthesis on stimulation of the cells by IL-21. By Western blot analysis, we demonstrated that the intracellular signaling pathways of IL-21 in myeloma cells involved phosphorylation of Jak1, Stat3, and Erk1/2 (p44/42 mitogen-activated protein kinase). IL-21 is a novel growth and survival factor in multiple myeloma and may represent a target for future therapy.

Multiple myeloma is a hematological cancer that is considered incurable despite advances in treatment strategy during the last decade. Therapies targeting single pathways are unlikely to succeed due to the heterogeneous nature of the malignancy. Proliferating cell nuclear antigen (PCNA) is a multifunctional protein essential for DNA replication and repair that is often overexpressed in cancer cells. Many proteins involved in the cellular stress response interact with PCNA through the five amino acid sequence AlkB homologue 2 PCNA-interacting motif (APIM). Thus inhibiting PCNA’s protein interactions may be a good strategy to target multiple pathways simultaneously. We initially found that overexpression of peptides containing the APIM sequence increases the sensitivity of cancer cells to contemporary therapeutics. Here we have designed a cell-penetrating APIM-containing peptide, ATX-101, that targets PCNA and show that it has anti-myeloma activity. We found that ATX-101 induced apoptosis in multiple myeloma cell lines and primary cancer cells, while bone marrow stromal cells and primary healthy lymphocytes were much less sensitive. ATX-101-induced apoptosis was caspase-dependent and cell cycle phase-independent. ATX-101 also increased multiple myeloma cells’ sensitivity against melphalan, a DNA damaging agent commonly used for treatment of multiple myeloma. In a xenograft mouse model, ATX-101 was well tolerated and increased the anti-tumor activity of melphalan. Therefore, targeting PCNA by ATX-101 may be a novel strategy in multiple myeloma treatment.

Objectives. To investigate the possible long-term effects of metformin exposure on growth and development of the offspring born to mothers with polycystic ovary syndrome (PCOS). The drug passes through the placenta and can potentially influence the fetus. Patients and methods. This is a follow-up study of a randomized, controlled trial on PCOS women, randomized to metformin or placebo in pregnancy. Out of 37 children aged 7–9 years, 25 agreed to participate. Primary outcome measures were growth, body composition and metabolic parameters. Results. There were no differences in height, weight or body composition between those exposed to metformin and those exposed to placebo. We found a higher fasting glucose level in the metformin group (4.93 mmol/L vs. 4.60 mmol/L, p = 0.04). In the metformin group there was a trend towards higher systolic blood pressure (106 mmHg vs. 101 mmHg, p = 0.05) and a lower LDL cholesterol level (2.42 mmol/L vs. 2.99 mmol/L, p = 0.07). Conclusion. Metformin exposure during fetal life does not seem to influence growth and body composition at the age of 8 years. A higher fasting glucose level and a possible higher systolic blood pressure and lower LDL cholesterol level in the metformin group may be coincidental and should be further explored.

Purpose: We wanted to examine the role of the hepatocyte growth factor (HGF) receptor c-Met in multiple myeloma by applying a novel selective small molecule tyrosine kinase inhibitor, PHA-665752, directed against the receptor.