Background: KRAS is a known oncogene driving transformation in multiple tissues. Results: We demonstrate a role for the transcription factor GLI1 in KRAS-induced transformation through regulation of the IL-6/STAT3 axis in the tumor microenvironment. Conclusion: This study defines a novel oncogenic network downstream of KRAS modulating transformation. Significance: This knowledge will contribute to the understanding of the pathogenesis of tumors driven by KRAS.

Although proinflammatory and chemotactic cytokines can profoundly affect the tumor microenvironment, and many of them have been shown to have therapeutic efficacy in preclinical models, the role of these molecules in Waldenströ m macroglobulinemia (WM) remains poorly understood. In this study, simultaneous analysis of WM patient sera and bone marrow biopsies identified a set of dysregulated cytokines including CCL5, G-CSF, and soluble IL-2 receptor, that were significantly elevated in WM patients whereas IL-8 and EGF levels were significantly lower in these patients compared with healthy controls. Interestingly, CCL5 levels positively correlated with features of disease aggressiveness such as elevated IgM levels and bone marrow involvement. IntroductionCytokines are protein mediators that are known to be involved in many biologic processes including cell growth, survival, inflammation, and differentiation. [1][2][3] In the malignant scenario, cytokines can profoundly affect tumor cells directly as well as the surrounding microenvironment, thereby impacting tumor cell biology. Therefore, understanding the composition of the cytokine milieu, particularly in the tumor microenvironment, is an important component of our understanding of the biology of malignant transformation. Targeting cytokines has been shown to have potent therapeutic efficacy in preclinical cancer models. 4,5 Despite the importance of cytokine networks in normal and disease states, only a limited number of studies have addressed the role of cytokines in the regulation of the tumor microenvironment in B-cell malignancies, and in particular, Waldenström macroglobulinemia (WM).WM is characterized by an infiltration of lymphoplasmacytic cells in the bone marrow accompanied by a high circulating monoclonal IgM protein that often leads to serum hyperviscosity. 6 Despite the introduction of multiple therapies, WM remains an incurable disease. Therefore, an understanding of the basic mechanisms underlying disease biology is fundamental to the development of novel therapies. In this study, we used a multiplex immunobead assay to simultaneously measure cytokines, chemokines, angiogenic factors, as well as growth factors and soluble receptors in the sera of WM patients and compared them with healthy donors. Our studies identify CCL5 (also known as regulated on activation, normal T-cell expressed, and secreted [RAN-TES]), G-CSF, and soluble IL-2 receptor ␣ (sIL-2R/CD25) as highly expressed in WM patient sera whereas IL-8 and EGF are down-regulated. Further analysis of CCL5 found that serum CCL5 levels correlated with expression of CCL5 in the bone marrow, IgM, IL-6 and bone marrow involvement by lymphoplasmacytic cells. Further analysis of the interplay between CCL5 and IL-6 indicated that CCL5 induced IL-6 secretion by WM stromal cells and identified the JAK/STAT signaling pathway as a mediator of IgM secretion in response to IL-6 stimulation. Therefore, therapies targeting CCL5 may provide therapeutic efficacy for WM patients by reducing IL-6 secretion by...

SP/KLF transcription factors comprise an emerging group of proteins that may behave as tumor suppressors. Incidentally, many cancers displaying alterations in certain KLF proteins are also associated with a high incidence of KRAS mutations. Therefore, we here investigate whether SP/KLF proteins suppress KRAS-mediated cell growth, and more importantly, the potential mechanisms underlying these effects. Using a comprehensive, family-wide screening of the 24 SP/KLF members, we discover that SP5, SP8, KLF2, KLF3, KLF4, KLF11, KLF13, KLF14, KLF15 and KLF16 inhibit cellular growth and suppress transformation mediated by oncogenic KRAS. Each protein in this subset of SP/KLF members individually inhibits BrdU incorporation in KRAS oncogenic mutant cancer cells. SP5, KLF3, KLF11, KLF13, KLF14 and KLF16 also increase apoptosis in these cells. Using KLF11 as a representative model for mechanistic studies, we demonstrate that this protein inhibits the ability of cancer cells to form colonies in soft agar and tumor growth in vivo. Molecular studies demonstrate that these effects of KLF11 are mediated, at least in part, through silencing cyclin A via binding to its promoter and leading to cell cycle arrest in S phase. Interestingly, similar to KLF11, KLF14 and KLF16 mechanistically share the ability to modulate the expression of cyclin A. Collectively, this study stringently defines a distinct subset of SP/KLF proteins that impairs KRAS-mediated cell growth, and that mechanistically, some members of this subset accomplish this, at least in part, through regulation of the cyclin A promoter.

Proliferative chronic myelomonocytic leukemia (pCMML), an aggressive CMML subtype, is associated with dismal outcomes. RAS pathway mutations, mainly NRASG12D, define the pCMML phenotype as demonstrated by our exome sequencing, progenitor colony assays and a Vav-Cre-NrasG12D mouse model. Further, these mutations promote CMML transformation to acute myeloid leukemia. Using a multiomics platform and biochemical and molecular studies we show that in pCMML RAS pathway mutations are associated with a unique gene expression profile enriched in mitotic kinases such as polo-like kinase 1 (PLK1). PLK1 transcript levels are shown to be regulated by an unmutated lysine methyl-transferase (KMT2A) resulting in increased promoter monomethylation of lysine 4 of histone 3. Pharmacologic inhibition of PLK1 in RAS mutant patient-derived xenografts, demonstrates the utility of personalized biomarker-driven therapeutics in pCMML.