HOXA9 has the hallmarks of a biological switch with implications in blood cancers

HOXA9 transcription factor is a double-edged sword: from development to cancer progression

The HOXA9 transcription factor serves as a molecular orchestrator in cancer stemness, epithelial-mesenchymal transition (EMT), metastasis, and generation of the tumor microenvironment in hematological and solid malignancies. However, the multiple modes of regulation, multifaceted functions, and context-dependent interactions responsible for the dual role of HOXA9 as an oncogene or tumor suppressor in cancer remain obscure. Hence, unravelling its molecular complexities, binding partners, and interacting signaling molecules enables us to comprehend HOXA9-mediated transcriptional programs and molecular crosstalk. However, it is imperative to understand its central role in fundamental biological processes such as embryogenesis, foetus implantation, hematopoiesis, endothelial cell proliferation, and tissue homeostasis before designing targeted therapies. Indeed, it presents an enormous challenge for clinicians to selectively target its oncogenic functions or restore tumor-suppressive role without altering normal cellular functions. In addition to its implications in cancer, the present review also focuses on the clinical applications of HOXA9 in recurrence and drug resistance, which may provide a broader understanding beyond oncology, open new avenues for clinicians for accurate diagnoses, and develop personalized treatment strategies. Furthermore, we have also discussed the existing therapeutic options and accompanying challenges in HOXA9-targeted therapies in different cancer types.

Order-of-Mutation Effects on Cancer Progression: Models for Myeloproliferative Neoplasm

In some patients with myeloproliferative neoplasms (MPN), two genetic mutations are often found: JAK2 V617F and one in the TET2 gene. Whether one mutation is present influences how the other subsequent mutation will affect the regulation of gene expression. In other words, when a patient carries both mutations, the order of when they first arose has been shown to influence disease progression and prognosis. We propose a nonlinear ordinary differential equation, the Moran process, and Markov chain models to explain the non-additive and non-commutative mutation effects on recent clinical observations of gene expression patterns, proportions of cells with different mutations, and ages at diagnosis of MPN. Combined, these observations are used to shape our modeling framework. Our key proposal is that bistability in gene expression provides a natural explanation for many observed order-of-mutation effects. We also propose potential experimental measurements that can be used to confirm or refute predictions of our models.

Exploring the expression and clinical significance of the miR-140-3p-HOXA9 axis in colorectal cancer

PURPOSE

This study aims to investigate the expression patterns and clinical significance of miR-140-3p and homeobox A9 (HOXA9) in colorectal cancer (CRC) selected by bioinformatic study, while elucidating their potential interplay.

METHODS

The microRNA expression profiles of paired colorectal cancer and matched normal tissues were retrieved from the Gene Expression Omnibus Database. Differentially expressed microRNAs and microRNA candidates were filtered and subjected to further analysis. Clinicopathological data, along with paraffin-embedded samples of colorectal tumor tissues were collected to facilitate comprehensive analysis. Expression levels of miR-140-3p and HOXA9 were quantified using qRT-PCR and immunohistochemistry. Survival rates were determined using the Kaplan-Meier method, and the COX regression model was utilized to identify independent prognostic factors that impact the overall prognosis.

RESULTS

MiR-140-3p was significantly downregulated in colorectal tumors compared to normal tissue, and HOXA9 was identified as a previously unreported potential downstream target. HOXA9 expression was elevated in tumors compared to normal tissues. Reduced miR-140-3p expression was associated with lymph node metastasis, while high HOXA9 expression correlated with both lymph node metastasis and lympho-vascular invasion. Patients with low miR-140-3p and high HOXA9 expression had a poorer prognosis. HOXA9 was identified as an independent risk factor for CRC patient survival.

CONCLUSION

The miR-140-3p-HOXA9 signaling disruption is closely linked to lymph node metastasis and unfavorable prognosis in CRC. This axis shows promise as a clinical biomarker for predicting the CRC patient survival and a potential therapeutic target.

HOXA9 Regulome and Pharmacological Interventions in Leukemia

HOXA9, an important transcription factor (TF) in hematopoiesis, is aberrantly expressed in numerous cases of both acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) and is a strong indicator of poor prognosis in patients. HOXA9 is a proto-oncogene which is both sufficient and necessary for leukemia transformation. HOXA9 expression in leukemia correlates with patient survival outcomes and response to therapy. Chromosomal transformations (such as NUP98-HOXA9), mutations, epigenetic dysregulation (e.g., MLL- MENIN -LEDGF complex or DOT1L/KMT4), transcription factors (such as USF1/USF2), and noncoding RNA (such as HOTTIP and HOTAIR) regulate HOXA9 mRNA and protein during leukemia. HOXA9 regulates survival, self-renewal, and progenitor cell cycle through several of its downstream target TFs including LMO2, antiapoptotic BCL2, SOX4, and receptor tyrosine kinase FLT3 and STAT5. This dynamic and multilayered HOXA9 regulome provides new therapeutic opportunities, including inhibitors targeting DOT1L/KMT4, MENIN, NPM1, and ENL proteins. Recent findings also suggest that HOXA9 maintains leukemia by actively repressing myeloid differentiation genes. This chapter summarizes the recent advances understanding biochemical mechanisms underlying HOXA9-mediated leukemogenesis, the clinical significance of its abnormal expression, and pharmacological approaches to treat HOXA9-driven leukemia.

Order-of-mutation effects on cancer progression: models for myeloproliferative neoplasm

In some patients with myeloproliferative neoplasms (MPN), two genetic mutations are often found, JAK2 V617F and one in the TET2 gene. Whether or not one mutation is present will influence how the other subsequent mutation affects the regulation of gene expression. When both mutations are present, the order of their occurrence has been shown to influence disease progression and prognosis. We propose a nonlinear ordinary differential equation (ODE), Moran process, and Markov chain models to explain the non-additive and non-commutative mutation effects on recent clinical observations of gene expression patterns, proportions of cells with different mutations, and ages at diagnosis of MPN. These observations consistently shape our modeling framework. Our key proposal is that bistability in gene expression provides a natural explanation for many observed order-of-mutation effects. We also propose potential experimental measurements that can be used to confirm or refute predictions of our models.

Order-of-mutation effects on cancer progression: models for myeloproliferative neoplasm

In some patients with myeloproliferative neoplasms (MPN), two genetic mutations are often found, JAK2 V617F and one in the TET2 gene. Whether or not one mutation is present will influence how the other subsequent mutation affects the regulation of gene expression. When both mutations are present, the order of their occurrence has been shown to influence disease progression and prognosis. We propose a nonlinear ordinary differential equation (ODE), Moran process, and Markov chain models to explain the non-additive and non-commutative mutation effects on recent clinical observations of gene expression patterns, proportions of cells with different mutations, and ages at diagnosis of MPN. These observations consistently shape our modeling framework. Our key proposal is that bistability in gene expression provides a natural explanation for many observed order-of-mutation effects. We also propose potential experimental measurements that can be used to confirm or refute predictions of our models.

Resolving the hematopoietic stem cell state by linking functional and molecular assays

One of the most challenging aspects of stem cell research is the reliance on retrospective assays for ascribing function. This is especially problematic for hematopoietic stem cell (HSC) research in which the current functional assay that formally establishes its HSC identity involves long-term serial transplantation assays that necessitate the destruction of the initial cell state many months before knowing that it was, in fact, an HSC. In combination with the explosion of equally destructive single-cell molecular assays, the paradox facing researchers is how to determine the molecular state of a functional HSC when you cannot concomitantly assess its functional and molecular properties. In this review, we will give a historical overview of the functional and molecular assays in the field, identify new tools that combine molecular and functional readouts in populations of HSCs, and imagine the next generation of computational and molecular profiling tools that may help us better link cell function with molecular state.