Distal-less homeobox-1 (DLX1) is a well-established non-invasive biomarker for prostate cancer (PCa) diagnosis, however, its mechanistic underpinnings in disease pathobiology are not known. Here, we reveal the oncogenic role of DLX1 and show that abrogating its function leads to reduced tumorigenesis and metastases. We observed that ~60% of advanced-stage and metastatic patients display higher DLX1 levels. Moreover, ~96% of TMPRSS2-ERG fusion-positive and ~70% of androgen receptor (AR)-positive patients show elevated DLX1, associated with aggressive disease and poor survival. Mechanistically, ERG coordinates with enhancer-bound AR and FOXA1 to drive transcriptional upregulation of DLX1 in ERG-positive background. However, in ERG-negative context, AR/AR-V7 and FOXA1 suffice to upregulate DLX1. Notably, inhibiting ERG/AR-mediated DLX1 transcription using BET inhibitor (BETi) or/and anti-androgen drugs reduce its expression and downstream oncogenic effects. Conclusively, this study establishes DLX1 as a direct-target of ERG/AR with an oncogenic role and demonstrates the clinical significance of BETi and anti-androgens for DLX1-positive patients.
Cells incurring oncogenic hits are often eliminated by cell death via built-in anti-cancer defense mechanisms, broadly termed as intrinsic tumor suppression (ITS). Identification of genetic modifiers of ITS-induced cell death would provide better understanding of inherent tumor-resistance and/or susceptibility. Using a Drosophila model of loss of a tumor suppressor-mediated epithelial tumorigenesis, here we show that perturbations in levels of stress-responsive nuclear long non-coding RNA (lncRNA) hsrω gene, promote epithelial tumorigenesis. Thus, while somatic clones with loss of a tumor suppressor, Lgl, are eliminated by JNK-induced cell death, lgl mutant somatic clones induced either in an hsrω loss-of-function heterozygous genetic background, or upon cell autonomous up- or down-regulation of hsrω in lgl somatic clones, override the JNK-mediated cell death and progress to full blown tumors. These tumors display deregulation of Hippo pathway as seen from a gain of downstream target of inhibition, Diap1, an inhibitor of cell death. We finally show that downregulation in sat III non-coding RNA, a functional analog of hsrω in humans, increases sensitivity of cancer cells to cytotoxic stress-induced cell death. lncRNA hsrω, therefore, constitutes a novel genetic modifier of ITS in Drosophila and of stress-induced cell death in human cancers.SummaryA long non-coding RNA, hsrω, is a novel regulator of JNK-mediated intrinsic tumor suppression in Drosophila.Highlightslgl clones induced in hsrω heterozygous loss-of-function genetic background escape intrinsic tumor suppression (ITS).Perturbation of hsrω in lgl mutant clones, too, leads to their escape from ITS.hsrω homeostasis required for JNK-dependent ITS.Human sat III, a functional analog of hsrω, confers stress-resistant to human cancer cells.
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