Deletion of the chromosome 5q [del(5q)] is one of the most common cytogenetic abnormalities observed in patients with de novo myelodysplastic syndromes (MDS) and therapy-related MDS or acute myeloid leukemia (t-MDS/tAML). Emerging evidence indicates that activation of the Wnt/β-catenin pathway contributes to the development of myeloid neoplasms with del(5q). Whether β-catenin is a potential therapeutic target for myeloid neoplasms with del(5q) has yet to be evaluated. Here we report that genetic deletion of a single allele of β-catenin rescues ineffective hematopoiesis in an Apc haploinsufficient mouse model, which recapitulates several characteristic features of the pre-leukemic stage of myeloid neoplasms with a -5/del(5q). In addition, loss of a single allele of β-catenin reversed the defective self-renewal capacity of Apc-haploinsufficient hematopoietic stem cells (HSC) and reduced the frequency of apoptosis induced by Apc haploinsufficiency. Suppression of β-catenin by indomethacin or β-catenin shRNA reduced proliferation and survival of human leukemia cell lines with del(5q) but not of control leukemia cell lines in vitro; β-catenin inactivation also inhibited leukemia progression in vivo in xenograft mice reconstituted with del(5q) leukemia cell lines. Inhibition of β-catenin also stunted growth and colony-forming abilities of primary bone marrow cells from del(5q) AML patients in vitro. Overall, our data support the idea that β-catenin could serve as a therapeutic target for the treatment of myeloid neoplasms with del(5q).

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• Apc regulates the function of HSCs/HPCs largely through a b-catenin-mediated pathway.• Multiple downstream targets of Apc may be involved in the regulation of HSC self-renewal. . In assays of long-term stem cell function, the HSCs with deficiency of both Apc and b-catenin displayed a significantly enhanced self-renewal capacity compared with b-catenin-deficient and control HSCs. Our findings suggest that Apc regulates the survival, proliferation, and differentiation of HSCs/HPCs largely through a b-catenin-mediated pathway. They also indicate that multiple downstream targets of Apc including b-catenin may coordinately regulate HSC self-renewal. (Blood. 2013;121(20):4063-4072)

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<p>Supplemental Figure 1. Indo suppresses beta-catenin expression. (A) Luciferase reporter assay of beta-catenin transcription activity. (B) beta-catenin expression in MDSL and UoC-M1 cells after Indo treatment for 72 hours. *, P <0.05. Supplemental Figure 2. Indo induces apoptosis of human MDSL, UoCM1 and KG1 cell lines with a del(5q). The histograms of the flow cytometric analysis of apoptosis of leukemia cell lines treated with 100μM Indo. Supplemental Figure 3. beta-catenin suppression induces apoptosis of human MDSL, UoCM1 and KG1 cell lines with a del(5q). The histograms of the flow cytometric analysis of apoptosis of leukemia cell lines expressing PLKO or PLKO-beta-catenin shRNAs.</p>

<div>Abstract<p>Deletion of the chromosome 5q [del(5q)] is one of the most common cytogenetic abnormalities observed in patients with <i>de novo</i> myelodysplastic syndromes (MDS) and therapy-related MDS or acute myeloid leukemia (t-MDS/tAML). Emerging evidence indicates that activation of the Wnt/β-catenin pathway contributes to the development of myeloid neoplasms with del(5q). Whether β-catenin is a potential therapeutic target for myeloid neoplasms with del(5q) has yet to be evaluated. Here, we report that genetic deletion of a single allele of β-catenin rescues ineffective hematopoiesis in an <i>Apc</i> haploinsufficient mouse model, which recapitulates several characteristic features of the preleukemic stage of myeloid neoplasms with a −5/del(5q). In addition, loss of a single allele of β-catenin reversed the defective self-renewal capacity of Apc-haploinsufficient hematopoietic stem cells and reduced the frequency of apoptosis induced by Apc haploinsufficiency. Suppression of β-catenin by indomethacin or β-catenin shRNA reduced proliferation and survival of human leukemia cell lines with del(5q) but not of control leukemia cell lines <i>in vitro</i>; β-catenin inactivation also inhibited leukemia progression <i>in vivo</i> in xenograft mice reconstituted with del(5q) leukemia cell lines. Inhibition of β-catenin also stunted growth and colony-forming abilities of primary bone marrow cells from del(5q) AML patients <i>in vitro</i>. Overall, our data support the idea that β-catenin could serve as a therapeutic target for the treatment of myeloid neoplasms with del(5q). <i>Cancer Res; 77(15); 4116–26. ©2017 AACR</i>.</p></div>

Background: Autologous stem cell transplant lengthens survival in patients with multiple myeloma, but has mortality from infections and high costs. Determination of prognostic factors predicting prolonged survival prior to transplant may help determine which patients may be better candidates for autologous SCT. Here, we hypothesized that extensive skeletal involvement prior to transplant predicted for adverse transplant outcome. Methods: Patients undergoing autologous stem cell transplants from 1999 to 2003 at Rush University Medical Center were reviewed to determine if having fewer lytic lesions prior to stem cell transplant there would lead to longer disease free survival post-transplant. Patients with less than 3 lytic lesions were compared to those with more than three lytic lesions regardless of subtype of myeloma or time to transplant. 83 patients had autoSCT at RUMC during the time frame, 12 patients did not have documented skeletal surveys and one patient underwent alloSCT, so they were not included in the analysis. Of the remaining 70, 44 patients had numerous lesions while 26 had 0-2 lesions. The mean age at SCT for both groups was 55.6 years. The various subtypes of myeloma for the group of 44 patients with numerous lesion is 25 with IgG, 6 with IgA, 1 with IgD, 5 with light chain, and 7 that were not specified, and for the group of 26 patients with 0-2 lesions, 19 were IgG, 2 IgA, 4 not specified and 1 with POEMS. The average time to transplant from diagnosis was 624 days with a range of 117-2294 for the group with 0-2 lesions, and 511 days with a range of 93-7321 days for the group with numerous lesions. Results: 28/44 patients with numerous lesions had documented disease progression with a median of 27 months from transplant, with ranges of 4-74 months, while 19/26 patients with fewer lesions progressed with median of 35 months and range of 12-75 months. Prior to August 2008, 15/44 patients in the group with numerous lesions died, while 19/26 patients in the group with fewer lesions died. Analysis with Kaplan Meyer survival curves showed no difference in disease free survival and death between the two groups, with p-values of 0.34 and 0.53 respectively. The estimated 5-year survival was 60% versus 50% for pts with 0-2 lesions versus numerous lesions respectively. Conclusions: We conclude that extent of skeletal involvement defined by number of lytic lesions does not predict for transplant outcome in patients with multiple myeloma.

3608 As the population ages, the incidence of AML with complex cytogenetics continues to increase. These patients have a poor prognosis with 5% percent of patients diagnosed surviving 5 years. New strategies are needed to improve survival in AML patients. 5q deletion is present in 6–10% of cases of AML, and is a common chromosome abnormality in therapy-related AML (t-AML). 5q deletion is associated with haplo-insufficiency of the APC gene in hematopoietic stem cells and progenitors, leading to deregulation of the Wnt pathway and stabilization of beta- catenin (Wang, J Blood 2010). Loss of APC causes rapid exhaustion of hematopoietic stem cells and progenitors in vivo and leads to the accumulation of beta-catenin (Qian, Z et al JEM 2008). Beta-catenin is required for the development of leukemia stem cells in AML, but it is not required for the self-renewal of normal hematopoietic stem cells (Wang, Y et al Science 2010). Development of treatment strategies aimed at blocking the Wnt pathway through suppression of beta-catenin may improve and prolong remission rates. The UoCM1 cell line maintains the unique characteristics of del(5q) leukemia (Qian et al, PNAS 2002). Western Blot shows that the expression of beta-catenin was higher in UoCM1 cells versus REH and MV4–11 cell lines, which do not have del(5q). To block the activation of Wnt signaling, through suppression of beta-catenin, we treated UoCM1, REH and MV4–11 cells with 100uM indomethacin. The UoCM1 cells showed 30% growth inhibition while REH and MV-4 cells displayed 10% growth inhibition. The down-regulation of beta-catenin in UocM1 is confirmed by Western Blot. Curcumin is a dietary polyphenol existing in Indian spice turmeric. We showed suppression of beta-catenin by curcumin in 293T cells by luciferase assay. Next, we treated UoCM1 and MV4–11 cells with 5uM or 10 uM curcumin. The growth of UoCM1 cells was significantly inhibited by curcumin as compared to MV4–11 cells. Treatment of UoCM1 cells with 10 uM curcumin produced 87% growth inhibition, while the growth inhibition was 29% for MV4–11 cells. 5uM concentrations of curcumin caused 48% growth inhibition in UoCM1 cells versus 16% in the MV4–11 cell line. Western Blot was performed to confirm that beta-catenin is down-regulated by curcumin, in the UoCM1 cell line. In summary, blockade of the Wnt pathway through inhibition of beta-catenin suppresses cell growth in UoCM1 leukemia cells, with 5q deletion. Suppression of beta-catenin in combination with cytotoxic therapy may provide a novel means of treating leukemia in patients with a 5q deletion that both improves remission rates and prevents relapse. Disclosures: No relevant conflicts of interest to declare.