Dataset Information

The High Mobility Group A1 (HMGA1) Chromatin Architectural Factor Modulates Nuclear Stiffness in Breast Cancer Cells.

ABSTRACT: Plasticity is an essential condition for cancer cells to invade surrounding tissues. The nucleus is the most rigid cellular organelle and it undergoes substantial deformations to get through environmental constrictions. Nuclear stiffness mostly depends on the nuclear lamina and chromatin, which in turn might be affected by nuclear architectural proteins. Among these is the HMGA1 (High Mobility Group A1) protein, a factor that plays a causal role in neoplastic transformation and that is able to disentangle heterochromatic domains by H1 displacement. Here we made use of atomic force microscopy to analyze the stiffness of breast cancer cellular models in which we modulated HMGA1 expression to investigate its role in regulating nuclear plasticity. Since histone H1 is the main modulator of chromatin structure and HMGA1 is a well-established histone H1 competitor, we correlated HMGA1 expression and cellular stiffness with histone H1 expression level, post-translational modifications, and nuclear distribution. Our results showed that HMGA1 expression level correlates with nuclear stiffness, is associated to histone H1 phosphorylation status, and alters both histone H1 chromatin distribution and expression. These data suggest that HMGA1 might promote chromatin relaxation through a histone H1-mediated mechanism strongly impacting on the invasiveness of cancer cells.

SUBMITTER: Senigagliesi B

PROVIDER: S-EPMC6600462 | biostudies-literature | 2019 Jun

REPOSITORIES: biostudies-literature

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The High Mobility Group A1 (HMGA1) Chromatin Architectural Factor Modulates Nuclear Stiffness in Breast Cancer Cells.

Senigagliesi Beatrice B Penzo Carlotta C Severino Luisa Ulloa LU Maraspini Riccardo R Petrosino Sara S Morales-Navarrete Hernan H Pobega Enrico E Ambrosetti Elena E Parisse Pietro P Pegoraro Silvia S Manfioletti Guidalberto G Casalis Loredana L Sgarra Riccardo R

International journal of molecular sciences 20190604 11

Plasticity is an essential condition for cancer cells to invade surrounding tissues. The nucleus is the most rigid cellular organelle and it undergoes substantial deformations to get through environmental constrictions. Nuclear stiffness mostly depends on the nuclear lamina and chromatin, which in turn might be affected by nuclear architectural proteins. Among these is the HMGA1 (High Mobility Group A1) protein, a factor that plays a causal role in neoplastic transformation and that is able to d ...[more]

PMID: 31167352

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Project description:High Mobility Group A1 (HMGA1) is an architectural chromatin protein whose overexpression is a feature of malignant neoplasias with a causal role in cancer initiation and progression. HMGA1 promotes tumor growth by several mechanisms, including increase of cell proliferation and survival, impairment of DNA repair and induction of chromosome instability. Autophagy is a self-degradative process that, by providing energy sources and removing damaged organelles and misfolded proteins, allows cell survival under stress conditions. On the other hand, hyper-activated autophagy can lead to non-apoptotic programmed cell death. Autophagy deregulation is a common feature of cancer cells in which has a complex role, showing either an oncogenic or tumor suppressor activity, depending on cellular context and tumor stage. Here, we report that depletion of HMGA1 perturbs autophagy by different mechanisms. HMGA1-knockdown increases autophagosome formation by constraining the activity of the mTOR pathway, a major regulator of autophagy, and transcriptionally upregulating the autophagy-initiating kinase Unc-51-like kinase 1 (ULK1). Consistently, functional experiments demonstrate that HMGA1 binds ULK1 promoter region and negatively regulates its transcription. On the other hand, the increase in autophagosomes is not associated to a proportionate increase in their maturation. Overall, the effects of HMGA1 depletion on autophagy are associated to a decrease in cell proliferation and ultimately impact on cancer cells viability. Importantly, silencing of ULK1 prevents the effects of HMGA1-knockdown on cellular proliferation, viability and autophagic activity, highlighting how these effects are, at least in part, mediated by ULK1. Interestingly, this phenomenon is not restricted to skin cancer cells, as similar results have been observed also in HeLa cells silenced for HMGA1. Taken together, these results clearly indicate HMGA1 as a key regulator of the autophagic pathway in cancer cells, thus suggesting a novel mechanism through which HMGA1 can contribute to cancer progression.

Project description:PurposeThe high mobility group A1 (HMGA1) chromatin remodeling protein is required for metastatic progression and cancer stem cell properties in preclinical breast cancer models, although its role in breast carcinogenesis has remained unclear. To investigate HMGA1 in primary breast cancer, we evaluated immunoreactivity score (IRS) in tumors from a large cohort of Asian women; HMGA1 gene expression was queried from two independent Western cohorts.MethodsHMGA1 IRS was generated from breast tumors in Korean women as the product of staining intensity (weak = 1, moderate = 2, strong = 3) and percent positive cells (< 5% = 0, 5-30% = 1, 30-60% = 2, > 60% = 3), and stratified into three groups: low (< 3), intermediate (3-6), high (> 6). We assessed HMGA1 and estrogen receptor (ESR1) gene expression from two large databases (TCGA, METABRIC). Overall survival was ascertained from the METABRIC cohort.ResultsAmong 540 primary tumors from Korean women (181 ER-negative, 359 ER-positive), HMGA1 IRS was < 3 in 89 (16.5%), 3-6 in 215 (39.8%), and > 6 in 236 (43.7%). High HMGA1 IRS was associated with estrogen receptor (ER)-negativity (χ2 = 12.07; P = 0.002) and advanced nuclear grade (χ2 = 12.83; P = 0.012). In two large Western cohorts, the HMGA1 gene was overexpressed in breast cancers compared to non-malignant breast tissue (P < 0.0001), including Asian, African American, and Caucasian subgroups. HMGA1 was highest in ER-negative tumors and there was a strong inverse correlation between HMGA1 and ESR1 gene expression (Pearson r = - 0.60, P < 0.0001). Most importantly, high HMGA1 predicted decreased overall survival (P < 0.0001) for all women with breast cancer and further stratified ER-positive tumors into those with inferior outcomes.ConclusionsTogether, our results suggest that HMGA1 contributes to estrogen-independence, tumor progression, and poor outcomes. Moreover, further studies are warranted to determine whether HMGA1 could serve as a prognostic marker and therapeutic target for women with breast cancer.

Project description:Interleukin (IL)-24, a novel tumor suppressor/cytokine exhibits antitumor activity against a broad-spectrum of human cancer cells. In a recent study, we showed that IL-24 inhibited AKT in lung cancer cells. However, the molecular mechanism of AKT inhibition by IL-24 remains elusive.The high mobility group (HMG) A1 a member of the non-histone chromosomal proteins and commonly referred to as architectural transcription factor, regulates transcription of various genes involved in cell growth and survival. Overexpression of HMGA1 has been shown to be associated with tumor progression and metastasis in several cancers, including human lung cancer. A recent study demonstrated that HMGA1 activates AKT function by reducing the activity of the protein phosphatase, phosphatase 2A subunit B (PPP2R2A) via the oncogenic micro (mi) RNA-222. Based on this report we hypothesized that IL-24-mediated AKT inhibition involved the HMGA1/miR-222 axis.To test our hypothesis, in the present study we used a H1299 lung cancer cell line that expressed exogenous human IL-24 when induced with doxycycline (DOX). Induction of IL-24 expression in the tumor cells markedly reduced HMGA1 mRNA and protein levels. Using a mechanistic approach, we found that IL-24 reduced miR-222-3p and -5p levels, as determined by qRT-PCR. Associated with HMGA1 and miR-222 inhibition was a marked increase in PPP2R2A, with a concomitant decrease in phosphorylated AKTT308/S473 expression. SiRNA-mediated knockdown of HMGA1 in combination with IL-24 significantly reduced AKT T308/S473 protein expression and greatly reduced cell migration and invasion compared with individual treatments. Further combination of IL-24 and a miR-222-3p inhibitor significantly increased PPP2R2A expression.Our results demonstrate for the first time that IL-24 inhibits AKT via regulating the HMGA1/miR-222 signaling node in human lung cancer cells and acts as an effective tumor suppressor. Thus, a therapy combining IL-24 with HMGA1 siRNA or miR-222-3p inhibitor should present effective treatment of lung cancer.

Dataset Information

The High Mobility Group A1 (HMGA1) Chromatin Architectural Factor Modulates Nuclear Stiffness in Breast Cancer Cells.

Publications

The High Mobility Group A1 (HMGA1) Chromatin Architectural Factor Modulates Nuclear Stiffness in Breast Cancer Cells.

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