Macroautophagy/autophagy, a pathway by which cellular components are sequestered and degraded in response to homeostatic and cell stress-related signals, is required to preserve hematopoietic stem and progenitor cell function. Loss of chromosomal regions carrying autophagy genes and decreased autophagy gene expression are characteristic of acute myeloid leukemia (AML) cells. Deficiency of autophagy proteins is also linked to an altered AML metabolic profile; altered metabolism has recently emerged as a potential druggable target in AML. Here, we sought to understand the mitochondria-specific changes that occur in leukemia cells after knockdown of BNIP3L/Nix or SQSTM1/p62, which are two autophagy genes involved in mitochondrial clearance and are downregulated in primary AML cells. Mitochondrial function, as measured by changes in endogenous levels of reactive oxygen species (ROS) and mitochondrial membrane potential, was altered in leukemia cells deficient in these autophagy genes. Further, these AML cells were increasingly sensitive to mitochondria-targeting drugs while displaying little change in sensitivity to DNA-targeting agents. These findings suggest that BNIP3L or SQSTM1 may be useful prognostic markers to identify AML patients suitable for mitochondria-targeted therapies.

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Background Lupus nephritis (LN) is an inflammatory disease of the kidneys affecting patients with systemic lupus erythematosus. Current immunosuppressive and cytotoxic therapies are associated with serious side effects and fail to protect 20–40% of LN patients from end-stage renal disease. In this study, we investigated whether a small heat shock protein, HSPB5, can reduce kidney inflammation and the clinical manifestations of the disease in NZB/W F1 mice. Furthermore, we investigated whether HSPB5 can enhance the effects of methylprednisolone, a standard-of-care drug in LN, in an endotoxemia mouse model. Methods NZB/W F1 mice were treated with HSPB5, methylprednisolone, or vehicle from 23 to 38 weeks of age. Disease progression was evaluated by weekly proteinuria scores. At the end of the study, the blood, urine, spleens, and kidneys were collected for the assessment of proteinuria, blood urea nitrogen, kidney histology, serum IL-6 and anti-dsDNA levels, immune cell populations, and their phenotypes, as well as the transcript levels of proinflammatory chemokine/cytokines in the kidneys. HSPB5 was also evaluated in combination with methylprednisolone in a lipopolysaccharide-induced endotoxemia mouse model; serum IL-6 levels were measured at 24 h post-endotoxemia induction. Results HSPB5 significantly reduced terminal proteinuria and BUN and substantially improved kidney pathology. Similar trends, although to a lower extent, were observed with methylprednisolone treatment. Serum IL-6 levels and kidney expression of BAFF, IL-6, IFNγ, MCP-1 (CCL2), and KIM-1 were reduced, whereas nephrin expression was significantly preserved compared to vehicle-treated mice. Lastly, splenic Tregs and Bregs were significantly induced with HSPB5 treatment. HSPB5 in combination with methylprednisolone also significantly reduced serum IL-6 levels in endotoxemia mice. Conclusions HSPB5 treatment reduces kidney inflammation and injury, providing therapeutic benefits in NZB/W F1 mice. Given that HSPB5 enhances the anti-inflammatory effects of methylprednisolone, there is a strong interest to develop HSBP5 as a therapeutic for the treatment of LN.

The matrix metalloproteinases (MMPs) are a complex family of zinc-dependent proteolytic enzymes, which collectively are capable of degrading all components of the extracellular matrix (ECM). The ECM provides structure and support for normal tissues, and acts both as a barrier to and support for cancer cell invasion and metastasis. MMPs are therefore believed to play an important role in regulating the rate of cancer progression. However, the repeated failure of MMP inhibitors in clinical trials, as well as recent discoveries of novel MMP activities and localizations, has led to a re-evaluation of the roles of MMPs to the cancer process. In colorectal cancer (CRC) the outlook following disease relapse after surgery and initial chemotherapy is poor, due both to drug resistance and further dissemination of disease. We investigated the involvement of MMPs and related molecules in this context. We have generated a series of derivatives of the human CRC cell line HT29 that are resistant to SN-38, the active metabolite of the chemotherapeutic agent irinotecan. The principal representative cell line, HT29-S, has a slower proliferation rate than parental HT29 cells, and yet forms denser outgrowths in monolayer culture. The abundance and localization of several MMPs and tissue inhibitors of metalloproteinases (TIMPs) have been assessed in both HT29 and HT29-S cells by western blotting of cytosolic and nuclear protein fractions,and by immunofluorescence. HT29-S cells showed a lower expression of MMP1, MMP7, and MMP9, but also TIMP1 and TIMP2, compared to their parental counterparts, with some differences in cellular distribution. In particular, MMP1 gave a strong nuclear signal by both methods in HT29 cells, which was strongly reduced in HT29-S. A reduction in MMP expression will allow for an increased accumulation of ECM components. This may act through integrin receptors to activate survival pathways and contribute to the chemoresistance observed in HT29-S cells, and may also facilitate the spread of cancer cells by refining the ECM framework in advanced CRC. Citation Format: Spencer I T Berg, Murray J. Cutler, Jr., Jonathan Blay. Changes in matrix metalloproteinase expression in SN-38 resistant colorectal cancer cells. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr A04.