Molecular cloning of t(2;7)(p24.3;p14.2), a novel chromosomal translocation in myelodysplastic syndrome-derived acute myeloid leukemia

Role of ELMO1 in inflammation and cancer-clinical implications

BACKGROUND

Engulfment and cell motility protein 1 (ELMO1) is a key protein for innate immunity since it is required for the clearance of apoptotic cells and pathogenic bacteria as well as for the control of inflammatory responses. ELMO1, through binding with Dock180 and activation of the Rac1 signaling pathway, plays a significant role in cellular shaping and motility. Rac-mediated actin cytoskeletal rearrangement is essential for bacterial phagocytosis, but also plays a crucial role in processes such as cancer cell invasion and metastasis. While the role of ELMO1 in bacterial infection and inflammatory responses is well established, its implication in cancer is not widely explored yet. Molecular changes or epigenetic alterations such as DNA methylation, which ultimately leads to alterations in gene expression and deregulation of cellular signaling, has been reported for ELMO1 in different cancer types.

CONCLUSIONS

In this review, we provide an updated and comprehensive summary of the roles of ELMO1 in infection, inflammatory diseases and cancer. We highlight the possible mechanisms regulated by ELMO1 that are relevant for cancer development and progression and provide insight into the possible use of ELMO1 as a diagnostic biomarker and therapeutic target.

PAN3-PSMA2 fusion resulting from a novel t(7;13)(p14;q12) chromosome translocation in a myelodysplastic syndrome that evolved into acute myeloid leukemia

Background

Acquired primary chromosomal changes in cancer are sometimes found as sole karyotypic abnormalities. They are specifically associated with particular types of neoplasia, essential in establishing the neoplasm, and they often lead to the generation of chimeric genes of pathogenetic, diagnostic, and prognostic importance. Thus, the report of new primary cancer-specific chromosomal aberrations is not only of scientific but also potentially of clinical interest, as is the detection of their gene-level consequences.

Case presentation

RNA-sequencing was performed on a bone marrow sample from a patient with myelodysplastic syndrome (MDS). The karyotype was 46,XX,t(7;13)(p14;q12)[2]/46,XX[23]. The MDS later evolved into acute myeloid leukemia (AML) at which point the bone marrow cells also contained additional, secondary aberrations. The 7;13-translocation resulted in fusion of the gene PAN3 from 13q12 with PSMA2 from 7p14 to generate an out-of-frame PAN3–PSMA2 fusion transcript whose presence was verified by RT-PCR together with Sanger sequencing. Interphase fluorescence in situ hybridization analysis confirmed the existence of the chimeric gene.

Conclusions

The novel t(7;13)(p14;q12)/PAN3–PSMA2 in the neoplastic bone marrow cells could affect two key protein complex: (a) the PAN2/PAN3 complex (PAN3 rearrangement) which is responsible for deadenylation, the process of removing the poly(A) tail from RNA, and (b) the proteasome (PSMA2 rearrangement) which is responsible for degradation of intracellular proteins. The patient showed a favorable response to decitabine after treatment with 5-azacitidine and conventional intensive chemotherapy had failed. Whether this might represent a consistent feature of MDS/AML with this particular gene fusion, remains unknown.

DEK oncoprotein regulates transcriptional modifiers and sustains tumor initiation activity in high-grade neuroendocrine carcinoma of the lung

Lung cancer shows diverse histological subtypes. Large-cell neuroendocrine cell carcinoma and small-cell lung carcinoma show similar histological features and clinical behaviors, and can be classified as high-grade neuroendocrine carcinoma (HGNEC) of the lung. Here we elucidated the molecular classification of pulmonary endocrine tumors by copy-number profiling. We compared alterations of copy number with the clinical outcome of HGNEC and identified a chromosomal gain of the DEK oncogene locus (6p22.3) that was significantly associated with poor prognosis. We further confirmed that DEK overexpression was associated with poor prognosis in a larger set of HGNEC. Downregulation of DEK by small hairpin RNA led to a marked reduction of in vitro colony formation, in vivo tumorigenicity and chemo-resistance, and was associated with loss of lung cancer stem cell markers. Gene expression profiling revealed that DEK downregulation was associated with altered expression of transcriptional regulators, which specifically include known targets of interchromosomal translocations in hematopoietic tumors, and knockdown of these epigenetic modifiers affected colony formation activity. Our study showed that DEK overexpression, partly through an increase in its gene dose, mediates the activity of global transcriptional regulators and is associated with tumor initiation activity and poor prognosis in HGNEC.