HMGA1 chromatin regulators induce transcriptional networks involved in GATA2 and proliferation during MPN progression

Abstract

Myeloproliferative neoplasms (MPN) transform to myelofibrosis (MF) and highly lethal acute myeloid leukemia (AML), although actionable mechanisms driving progression remain elusive. Here, we elucidate the role of the High Mobility Group A1 (HMGA1) chromatin regulator as a novel driver of MPN progression. HMGA1 is up-regulated in MPN with highest levels after transformation to MF or AML. To define HMGA1 function, we disrupted gene expression via CRISPR/Cas9, short hairpin RNA, or genetic deletion in MPN models. HMGA1 depletion in JAK2V617F AML cell lines disrupts proliferation, clonogenicity, and leukemic engraftment. Surprisingly, loss of just a single Hmga1 allele prevents progression to MF in JAK2V617F mice, decreasing erythrocytosis, thrombocytosis, megakaryocyte hyperplasia, and expansion of stem and progenitors, while preventing splenomegaly and fibrosis within the spleen and bone marrow. RNA- and chromatin immunoprecipitation-sequencing revealed HMGA1 transcriptional networks and chromatin occupancy at genes that govern proliferation (E2F, G2M, mitotic spindle) and cell fate, including the GATA2 master regulatory gene. Silencing GATA2 recapitulates most phenotypes observed with HMGA1 depletion whereas GATA2 re-expression partially rescues leukemogenesis. HMGA1 transactivates GATA2 through sequences near the developmental enhancer (+9.5), increasing chromatin accessibility and recruiting active histone marks. Further, HMGA1 transcriptional networks, including proliferation pathways and GATA2, are activated in human MF and MPN leukemic transformation. Importantly, HMGA1 depletion enhances responses to the JAK2 inhibitor, ruxolitinib, preventing MF and prolonging survival in murine models of JAK2V617F AML. These findings illuminate HMGA1 as a key epigenetic switch involved in MPN transformation and promising therapeutic target to treat or prevent disease progression.

HMGA1 induces FGF19 to drive pancreatic carcinogenesis and stroma formation

“…First, we found that HMGA1 expression (mRNA and protein) is higher in PDAC cell lines derived from metastatic tumors compared with those from primary tumors (65) (Supplemental Figure 1, A-E; supplemental material available online with this article; https://doi.org/10.1172/JCI151601DS1). Next, we silenced HMGA1 via lentiviral delivery of short hairpin RNAs (shRNAs) targeting 2 different sequences (49) in cell lines from primary and metastatic tumors harboring common PDAC mutations: (a) E3LZ10.7 (66), from a liver metastasis with KRAS G12D and homozygous SMAD4 deletion; (b) MIA PaCa-2 (67), from a primary PDAC with homozygous CDKN2A/p16 INK4A deletion, mutant KRAS G12C , and TP53; and (c) AsPC-1 (67), from PDAC ascites fluid with homozygous mutations in KRAS G12D , TP53 C135fs* 35 , and CDKN2A L78fs*41 . Strikingly, HMGA1 deficiency disrupted proliferation, clonogenicity, migration, invasion, and 3-dimensional (3D) sphere formation in all cell lines tested (Figure 1), indicating that HMGA1 is required for these oncogenic properties.…”

“…Overexpression of the gene encoding the chromatin regulator HMGA1 occurs in most aggressive tumors, including PDAC, where high levels portend poor differentiation and adverse outcomes . The HMGA1 gene is normally expressed during embryogenesis (30,39,51) and in adult stem cells (46,49,52), but silenced postnatally in most differentiated cells. Through alternatively spliced mRNA, HMGA1 encodes HMGA1a and HMGA1b isoforms, which bind to AT-rich sequences, bend chromatin, and recruit transcriptional complexes to modulate gene expression (31-35, 37, 39, 42, 45-47, 49, 53).…”

Pathogenic human variant that dislocates GATA2 zinc fingers disrupts hematopoietic gene expression and signaling networks

“…Although GATA2 mutational analyses revealed loss-of-function phenotypes that may underlie pathogenesis ( 30 ), GATA2 variants can partially retain or have supraphysiological activity ( 33 , 34 ). GATA2 dysregulation is also implicated in myeloproliferative neoplasms ( 35 ).…”

Establishing a prognostic model of chromatin modulators and identifying potential drug candidates in renal clear cell patients

“…According to their regulatory roles, CRs are generally classified into three categories: histone modifications, chromatin remodelers, and DNA methylation [11,12]. Aberrant expression of CRs is associated with various biological processes such as apoptosis, autophagy, and proliferation, suggesting that dysregulation of CRs may contribute to the development of multiple diseases, including cancer [13][14][15]. Therefore, CRs are expected to become new targets for treating multiple diseases.…”