Despite recent advances in therapy, multiple myeloma, the second most common hematologic tumor in the Western world, is still incurable. Identification of substances that display a wide range of tumor-killing activities and target cancer-specific pathways constitute a basis for the development of novel therapies. In this study, we investigate the cytotoxic effect of the natural substance cnicin in multiple myeloma. Cnicin treatment reveals potent antiproliferative effects and induces cell death in cell lines and primary myeloma cells even in the presence of survival cytokines and the tumor microenvironment. Other cell lines of hematopoietic origin also succumb to cell death whereas stromal cells and endothelial cells are unaffected. We show that activation of caspases, accumulation of reactive oxygen species and downregulation of nuclear factor kappa-light-chain-enhancer of activated B cell contribute to the cytotoxic effects of cnicin. Microarray analysis reveals downregulation of Pim-2, a serine/threonine kinase. We provide evidence that Pim-2 constitutes a new survival kinase for myeloma cells in vitro and is highly expressed in malignant but not in normal plasma cells in vivo. Combining cnicin with current standard or experimental therapeutics leads to enhanced cell death. Thus, our data indicate that cnicin induces myeloma cell death via several pathways and reveals Pim-2 as a novel target. These findings provide a rational for further evaluation of cnicin as a new anti-tumor drug and underline the potential of sesquiterpene lactones in tumor therapy.

Based on a recent description of an apoptosis stimulating property for hepatocyte derived isoferritins, this investigation demonstrates that ferritin, released in vitro from hepatocytes substantially contributes to density dependent apoptosis in primary hepatocytes and is significantly (P < or = 0.05) inhibited by anti-H-ferritin antibody rH02. Furthermore, total protein release and albumin secretion rapidly decline in a time and density dependent mode under serum-free conditions, whereas ferritin secretion, which is upregulated at initial stages of primary culture is not affected by cell density. Supplementation with dexamethasone (DEX) or proliferative stimulation by epidermal growth factor (EGF) and insulin strongly suppresses density dependent apoptosis. Both regimens have previously been shown to inhibit isoferritin mediated apoptosis in hepatocytes, most likely by interrupting proapotitc mitochondrial signalling. Finally, FasL/Fas also participates in density dependent apoptosis, since apoptosis is significantly (P < or = 0.005) reduced in high density cultures supplemented with an anti-FasL antibody. This antibody has also been shown to neutralise ferritin mediated apoptosis in primary hepatocytes, suggesting a linkage of ferritin and Fas in density dependent apoptosis. In conclusion, ferritin contributes to apoptosis in primary hepatocytes in an autocrine, density dependent mode, involving Fas stimulation and proapoptotic mitochondrial signalling. With respect to liver physiology, these findings may indicate that ferritin plays a yet unrecognised role as an acute phase signalling molecule in early stages of tissue repair and liver regeneration, and may also be responsible for the limited ability to propagate human hepatocytes in culture and the limited expansion of donor cells in the recipient liver upon cell transplantation.

Previously we have demonstrated an apoptosis inducing activity for a rat hepatocyte conditioned medium (CM) presumably mediated by acidic isoferritins. Here, we present support for this assumption since isoferritins purified from different rat hepatocyte CM significantly enhanced the frequency of apoptotic cells in primary rat hepatocytes, an effect completely inhibited by a neutralizing anti-H-ferritin antibody. The apoptosis induction appears to be related to a 43 kDa ferritin subunit contained in the isoferritins released from primary hepatocytes, presumably representing a ferritin heavy/light chain heterodimer. In addition, these isoferritins immunologically crossreact with antibodies raised against placental isoferritin p43-PLF (which also contains a 43 kDa ferritin subunit) and melanoma-derived H-chain ferritin, representing ferritin isoforms which reveal immunomodulatory properties. Furthermore, p53 and FasL are upregulated upon isoferritin treatment in a time dependent mode, and apoptosis induction can be suppressed by neutralizing anti-FasL antibodies. Proapoptotic Bid is upregulated too and translocated into mitochondria in primary hepatocytes exposed to the isoferritins purified from the CM. Finally, epidermal growth factor (EGF) and dexamethasone (DEX), which counteract proapoptotic mitochondrial signalling, almost completely abolished the proapoptotic effect of the hepatocyte derived isoferritins. In conclusion, our findings demonstrate that acidic isoferritins with homology to immunomodulatory ferritin isoforms (p43-PLF, melanoma-derived-H-chain ferritin) are released from hepatocytes in vitro, and are able to stimulate upregulation of p53 and mediate apoptosis involving Fas (CD95) signalling as well as addressing the intrinsic mitochondrial proapoptotic pathway.

Purpose: Chronic lymphocytic leukemia (CLL) pathophysiology is characterized by a complex crosstalk of tumor cells with the microenvironment. In this regard, NF-kB signaling is considered as important signaling axis, with a variety of key molecules aberrantly expressed or genetically altered in patients with CLL. One of these molecules is BIRC3 (cIAP2), a central regulator of noncanonical NF-kB signaling that serves as pathway brake in the absence of microenvironmental signals. However, the contribution of BIRC3 expression to CLL progression and potential therapeutic implications is unknown. Experimental Design: We analyzed the role of BIRC3 mRNA expression in primary CLL samples in correlation to clinical datasets and used ex vivo assays to investigate functional consequences on the level of NF-kB signaling and downstream target gene regulation. For proof-of-principle experiments, we used genetically modified cell lines. Results: We demonstrate that patients with CLL with low BIRC3 expression experience a more rapid disease progression, which coincides with an enhanced activation of canonical NF-kB target genes evidenced by an increased p65/Rel-B nuclear translocation ratio. As a consequence of enhanced canonical NF-kB target gene activation, both anti-and proapoptotic Bcl-2 family members were upregulated in BIRC3 low primary CLL cells, which was associated with higher sensitivity to venetoclax treatment in vitro. Conclusions: Here we show the impact of BIRC3 expression in CLL disease progression in the absence of BIRC3 mutations and show altered canonical NF-kB target gene activation with therapeutic implications.

Chronic lymphocytic leukemia (CLL) is the most prevalent lymphoid malignancy in the elderly of the Western world. Although treatment options have improved over the past two decades, 10-15% of patients still have a poor prognosis and are often resistant to therapy. Aberrations in the p53 pathway, such as a deleted (del17p13) or mutated p53 gene, are highly enriched in this class of patients. In an extensive screen for p53-independent apoptosis inducers, actinomycin D was identified from 1496 substances and shown to induce apoptosis in primary CLL cells derived from high-risk patients including those with aberrant p53, revealing a novel p53-independent mechanism of action. Both pro-survival genes BCL2 and MCL1 are targeted by actinomycin D, in contrast to fludarabine the backbone of current treatment schedules. In the well-established TCL1 transgenic mouse model for high-risk CLL, actinomycin D treatment was more effective in reducing tumor load than fludarabine, with no evidence of resistance after three treatment cycles and an overall survival increase of over 300%. Tumor load reduction was coupled to BCL2 downregulation. Our results identify the clinically approved compound actinomycin D as a potentially valuable treatment option for CLL high-risk patients.

<p>Supplementary Figures S1-S5</p>

<p>Supplementary Figures S1-S5</p>

<div>AbstractPurpose:<p>Chronic lymphocytic leukemia (CLL) pathophysiology is characterized by a complex crosstalk of tumor cells with the microenvironment. In this regard, NF-κB signaling is considered as important signaling axis, with a variety of key molecules aberrantly expressed or genetically altered in patients with CLL. One of these molecules is BIRC3 (cIAP2), a central regulator of noncanonical NF-κB signaling that serves as pathway brake in the absence of microenvironmental signals. However, the contribution of BIRC3 expression to CLL progression and potential therapeutic implications is unknown.</p><p><b>Experimental Design:</b> We analyzed the role of BIRC3 mRNA expression in primary CLL samples in correlation to clinical datasets and used <i>ex vivo</i> assays to investigate functional consequences on the level of NF-κB signaling and downstream target gene regulation. For proof-of-principle experiments, we used genetically modified cell lines.</p>Results:<p>We demonstrate that patients with CLL with low BIRC3 expression experience a more rapid disease progression, which coincides with an enhanced activation of canonical NF-κB target genes evidenced by an increased p65/Rel-B nuclear translocation ratio. As a consequence of enhanced canonical NF-κB target gene activation, both anti- and proapoptotic Bcl-2 family members were upregulated in BIRC3^low primary CLL cells, which was associated with higher sensitivity to venetoclax treatment <i>in vitro</i>.</p>Conclusions:<p>Here we show the impact of BIRC3 expression in CLL disease progression in the absence of BIRC3 mutations and show altered canonical NF-κB target gene activation with therapeutic implications.</p></div>