Project description:Runt-related transcription factor 3 (RUNX3) has been described as a tumor suppressor for gastric cancer and other solid malignancies. Despite its key role in physiological T-cell differentiation, there is rare information on its relevance for the development of human T-cell lymphoma or leukemia. Here we show that alterations of RUNX3 by either heterozygous deletion or methylation of its distal promoter can be observed in the tumor cells of 15/21 (71%) patients suffering from Sézary Syndrome (SS), an aggressive variant of cutaneous T-cell lymphoma. In consequence, mRNA levels of RUNX3/p46, the long isoform of RUNX3 – controlled by the proximal promoter – are significantly lower in SS tumor cells. Re-expression of RUNX3/p46 promotes apoptosis and slows down proliferation in a RUNX3/p46low cell line of cutaneous T-cell lymphoma. By this we present the first evidence that RUNX3 can act as a tumor suppressor in a human T-cell malignancy and suggest that this effect is predominantly mediated through the long isoform of this transcription factor, which has not been in the focus of previous studies.
Project description:To identify key tumour supressor miRNAs involed in MALT lymphoma pathogenesis Gastric mucosa-associated lymphoid tissue lymphoma develops in the chronically inflamed mucosa of Helicobacter pylori-infected patients. MicroRNA expression profiling of human MALT lymphoma revealed a 10-fold down-regulation of miR-203, which resulted from promoter hypermethylation and coincided with the dysregulation of the miR-203 target ABL1. Demethylating treatment of lymphoma B-cells led to an increase in miR-203 expression and concomitant ABL1 down-regulation. The lentiviral delivery of miR-203, as well as treatment with various ABL inhibitors, prevented primary MALT lymphoma cell proliferation in vitro. Finally, the treatment of tumor-bearing mice with imatinib induced MALT lymphoma regression in vivo. Our results show that MALT lymphomagenesis is epigenetically induced by miR-203 promoter methylation and identify ABL1 as a novel target for the treatment of this malignancy. 5 human fresh frozen MALT lymphoma samples were analysed and 4 human tonsil tissue samples were used as the non-tumour control
Project description:To identify key tumour supressor miRNAs involed in MALT lymphoma pathogenesis Gastric mucosa-associated lymphoid tissue lymphoma develops in the chronically inflamed mucosa of Helicobacter pylori-infected patients. MicroRNA expression profiling of human MALT lymphoma revealed a 10-fold down-regulation of miR-203, which resulted from promoter hypermethylation and coincided with the dysregulation of the miR-203 target ABL1. Demethylating treatment of lymphoma B-cells led to an increase in miR-203 expression and concomitant ABL1 down-regulation. The lentiviral delivery of miR-203, as well as treatment with various ABL inhibitors, prevented primary MALT lymphoma cell proliferation in vitro. Finally, the treatment of tumor-bearing mice with imatinib induced MALT lymphoma regression in vivo. Our results show that MALT lymphomagenesis is epigenetically induced by miR-203 promoter methylation and identify ABL1 as a novel target for the treatment of this malignancy.
Project description:Cancer-associated fibroblasts (CAFs) are a major stromal component of human breast cancers and often promote tumor proliferation, progression and malignancy. We previously established an experimental CAF (exp-CAF) cell line equipped with a potent tumor-promoting ability. It was generated through prolonged incubation of immortalized human mammary fibroblasts with human breast cancer cells in a tumor xenograft mouse model. Herein, we found that the exp-CAFs highly express Runt-related transcription factor 3 (RUNX3), while counterpart fibroblasts do not. In breast cancer patients, the proportion of RUNX3-positive stromal fibroblast-like cells tends to be higher in cancerous regions than in non-cancerous regions. These findings suggest an association of RUNX3 with CAF characteristics in human breast cancers. To investigate the functional role of RUNX3 in CAFs, the exp-CAFs with or without shRNA-directed knockdown of RUNX3 were implanted with breast cancer cells subcutaneously in immunodeficient mice. Comparison of the resulting xenograft tumors revealed that tumor growth was significantly attenuated when RUNX3 expression was suppressed in the fibroblasts. Consistently, Ki-67 and CD31 immunohistochemical staining of the tumor sections indicated reduction of cancer cell proliferation and microvessel formation in the tumors formed with the RUNX3-suppressed exp-CAFs. These results suggest that increased RUNX3 expression could contribute to the tumor-promoting ability of CAFs through mediating cancer cell growth and neoangiogenesis in human breast tumors.
Project description:Ewing sarcoma is an aggressive pediatric small round cell tumor that predominantly occurs in bone. Approximately 85% of Ewing sarcomas harbor the EWS/FLI fusion protein, which arises from a chromosomal translocation, t(11:22)(q24:q12). EWS/FLI interacts with numerous lineage-essential transcription factors to maintain mesenchymal progenitors in an undifferentiated state. We previously showed that EWS/FLI binds the osteogenic transcription factor RUNX2 and prevents osteoblast differentiation. In this study, we investigated the role of another Runt-domain protein, RUNX3, in Ewing sarcoma. RUNX3 participates in mesenchymal-derived bone formation and is a context dependent tumor suppressor and oncogene. RUNX3 was detected in all Ewing sarcoma cells examined, whereas RUNX2 was detected in only 73% of specimens. Like RUNX2, RUNX3 binds to EWS/FLI via its Runt domain. EWS/FLI prevented RUNX3 from activating the transcription of a RUNX-responsive reporter, p6OSE2. Stable suppression of RUNX3 expression in the Ewing sarcoma cell line A673 delayed colony growth in anchorage independent soft agar assays and reversed expression of EWS/FLI-responsive genes. These results demonstrate an important role for RUNX3 in Ewing sarcoma. RNA-seq to compare transcriptiome of control A673 ewing sarcoma cells stably expression a non-target or RUNX3 shRNA
Project description:Aldehyde dehydrogenase (ALDH1) activity has long been established as a pro-tumorigenic feature of many cancers, yet the identification of specific isoforms that are enriched in cancer, the mechanism of action of this isoform(s), and viable therapeutic strategies to target this pathway have long remained absent. Whereas one of the well-established functions of the ALDH1a family is the conversion of retinaldehyde into retinoic acid to activate nuclear retinoid signaling, the retinoid pathway is paradoxically hypothesized as a cell-intrinsic tumor suppressor pathway. Here we resolve this long-standing conflict by showing that while ALDH1a3 is broadly overexpressed across diverse cancer types, ALDH1a3 expressing tumor cells often lose the sensitivity to retinoid signaling. Instead, all-trans retinoic acid produced by ALDH1a3 acts in a paracrine fashion to suppress anti-tumor immunity and promote tumor growth. We further used structure-based high throughput screening to develop a series of first-in-class, therapeutically viable antagonists of ALDH1a3 with potent anti-tumor immunotherapeutic activity, an excellent pharmacological profile and no evidence of toxicity. Findings of this study resolve prior contradictions in the retinoid pathway through the development of highly specific and potent ALDH1a3 inhibitors.
Project description:The cell death receptor FAS and its ligand (FASLG) play crucial roles in the selection of B cells during the germinal center (GC) reaction. Failure to eliminate potentially harmful B cells via FAS can lead to lymphoproliferation and the development of B cell malignancies. The classic form of follicular lymphoma (FL) is a prototypic GC-derived B cell malignancy, characterized by the t(14;18)(q32;q21)IGH::BCL2 translocation and overexpression of antiapoptotic BCL2. Additional alterations were shown to be clinically relevant, including mutations in ARID1A. ARID1A is part of the SWI/SNF nucleosome remodeling complex that regulates DNA accessibility (“openness”). However, the mechanism how ARID1A mutations contribute to FL pathogenesis remains unclear. We analyzed 151 FL biopsies of patients with advanced-stage disease at initial diagnosis and found that ARID1A mutations were recurrent and mainly disruptive, with an overall frequency of 18%. Additionally, we observed that ARID1A mutant FL showed significantly lower FAS protein expression in the FL tumor cell population. Functional experiments in BCL2-translocated lymphoma cells demonstrated that ARID1A is directly involved in the regulation of FAS, and ARID1A loss leads to decreased FAS protein and gene expression. However, ARID1A loss did not affect FAS promotor openness. Instead, we identified and experimentally validated a previously unknown co-transcriptional complex consisting of RUNX3 and ETS1 that regulates FAS expression, and ARID1A loss leads to reduced RUNX3 promotor openness and gene expression. The reduced FAS levels induced by ARID1A loss rendered lymphoma cells resistant to both soluble and T cell membrane-anchored FASLG-induced apoptosis, and significantly diminished CAR T cell killing in functional experiments. In summary, we have identified a functionally and clinically relevant mechanism how FL cells can escape FAS-dependent immune surveillance, which may also impact the efficacy of T cell-based therapies, including CAR T cells.