Reactivation of p53 by a Cytoskeletal Sensor to Control the Balance Between DNA Damage and Tumor Dissemination

ROCK inhibition reduces the sensitivity of mutant p53 glioblastoma to genotoxic stress through a Rac1-driven ROS production

Resistance to radio and chemotherapy in Glioblastoma (GBM) is correlated with its malignancy, invasiveness, and aggressiveness. The Rho GTPase pathway plays important roles in these processes, but its involvement in the GBM response to genotoxic treatments remains unsolved. Inhibition of this signaling pathway has emerged as a promising approach for the treatment of CNS injuries and diseases, proving to be a strong candidate for therapeutic approaches. To this end, Rho-associated kinases (ROCK), classic downstream effectors of small Rho GTPases, were targeted for pharmacological inhibition using Y-27632 in GBM cells, expressing the wild-type or mutated p53 gene, and exposed to genotoxic stress by gamma ionizing radiation (IR) or cisplatin (PT). The use of the ROCK inhibitor (ROCKi) had opposite effects in these cells: in cells expressing wild-type p53, ROCKi reduced survival and DNA repair capacity (reduction of γH2AX foci and accumulation of strand breaks) after stress promoted by IR or PT; in cells expressing the mutant p53 protein, both treatments promoted longer survival and more efficient DNA repair, responses further enhanced by ROCKi. The target DNA repair mechanisms of ROCK inhibition were, respectively, an attenuation of NHEJ and NER pathways in wild-type p53 cells, and a stimulation of HR and NER pathways in mutant p53 cells. These effects were accompanied by the formation of reactive oxygen species (ROS) induced by genotoxic stress only in mutant p53 cells but potentiated by ROCKi and reversed by p53 knockdown. N-acetyl-L-cysteine (NAC) treatment or Rac1 knockdown completely eliminated ROCKi's p53-dependent actions, since ROCK inhibition specifically elevated Rac-GTP levels only in mutant p53 cells. Combining IR or PT and ROCKi treatments broadens our understanding of the sensitivity and resistance of, respectively, GBM expressing wild-type or mutant p53 to genotoxic agents. Our proposal may be a determining factor in improving the efficiency and assertiveness of CNS antitumor therapies based on ROCK inhibitors. SIGNIFICANCE: The use of ROCK inhibitors in association with radio or chemotherapy modulates GBM resistance and sensitivity depending on the p53 activity, suggesting the potential value of this protein as therapeutic target for tumor pre-sensitization strategies.

Podoplanin Drives Amoeboid Invasion in Canine and Human Mucosal Melanoma

Mucosal melanoma metastasizes at an early stage of the disease in human and dog. We revealed that overexpression of podoplanin in tumor invasion fronts (IF) was related to poor prognosis of dogs with mucosal melanoma. Moreover, podoplanin expressed in canine mucosal melanoma cells promotes proliferation and aggressive amoeboid invasion by activating Rho-associated kinase (ROCK)-myosin light chain 2 (MLC2) signaling. PDPN-ROCK-MLC2 signaling plays a role in cell-cycle arrest and cellular senescence escape as a mechanism for regulating proliferation. Podoplanin induces amoeboid invasion in the IFs of mouse xenografted tumor tissues, similar to canine mucosal melanoma clinical samples. We further identified that podoplanin expression was related to poor prognosis of human patients with mucosal melanoma, and human mucosal melanoma with podoplanin-high expression enriched gene signatures related to amoeboid invasion, similar to canine mucosal melanoma. Overall, we propose that podoplanin promotes canine and human mucosal melanoma metastasis by inducing aggressive amoeboid invasion and naturally occurring canine mucosal melanoma can be a novel research model for podoplanin expressing human mucosal melanoma.

IMPLICATIONS

Podoplanin could be a new therapeutic target to restrict the metastatic dissemination of canine and human mucosal melanoma.

AMPK is a mechano-metabolic sensor linking cell adhesion and mitochondrial dynamics to Myosin-dependent cell migration

Cell migration is crucial for cancer dissemination. We find that AMP-activated protein kinase (AMPK) controls cell migration by acting as an adhesion sensing molecular hub. In 3-dimensional matrices, fast-migrating amoeboid cancer cells exert low adhesion/low traction linked to low ATP/AMP, leading to AMPK activation. In turn, AMPK plays a dual role controlling mitochondrial dynamics and cytoskeletal remodelling. High AMPK activity in low adhering migratory cells, induces mitochondrial fission, resulting in lower oxidative phosphorylation and lower mitochondrial ATP. Concurrently, AMPK inactivates Myosin Phosphatase, increasing Myosin II-dependent amoeboid migration. Reducing adhesion or mitochondrial fusion or activating AMPK induces efficient rounded-amoeboid migration. AMPK inhibition suppresses metastatic potential of amoeboid cancer cells in vivo, while a mitochondrial/AMPK-driven switch is observed in regions of human tumours where amoeboid cells are disseminating. We unveil how mitochondrial dynamics control cell migration and suggest that AMPK is a mechano-metabolic sensor linking energetics and the cytoskeleton.

Preclinical to clinical utility of ROCK inhibitors in cancer

ROCK belongs to the AGC family of Ser/Thr protein kinases that are involved in many cellular processes. ROCK-driven actomyosin contractility regulates cytoskeletal dynamics underpinning cell migration, proliferation, and survival in many cancer types. ROCK1/2 play key protumorigenic roles in several subtypes and stages of cancer development. Therefore, successfully targeting ROCK and its downstream effectors presents an interesting avenue for cancer treatment. Because local use of ROCK inhibitors will reduce the side effects of systemic administration, we propose different therapeutic strategies and latest-generation ROCK inhibitors for use in the clinic.

Amoeboid migration in health and disease: Immune responses versus cancer dissemination

Cell migration is crucial for efficient immune responses and is aberrantly used by cancer cells during metastatic dissemination. Amoeboid migrating cells use myosin II-powered blebs to propel themselves, and change morphology and direction. Immune cells use amoeboid strategies to respond rapidly to infection or tissue damage, which require quick passage through several barriers, including blood, lymph and interstitial tissues, with complex and varied environments. Amoeboid migration is also used by metastatic cancer cells to aid their migration, dissemination and survival, whereby key mechanisms are hijacked from professionally motile immune cells. We explore important parallels observed between amoeboid immune and cancer cells. We also consider key distinctions that separate the lifespan, state and fate of these cell types as they migrate and/or fulfil their function. Finally, we reflect on unexplored areas of research that would enhance our understanding of how tumour cells use immune cell strategies during metastasis, and how to target these processes.

Redox-associated messenger RNAs identify novel prognostic values and influence the tumor immune microenvironment of lung adenocarcinoma

Background: An imbalance of redox homeostasis participates in tumorigenesis, proliferation, and metastasis, which results from the production of reactive oxygen species (ROS). However, the biological mechanism and prognostic significance of redox-associated messenger RNAs (ramRNAs) in lung adenocarcinoma (LUAD) still remain unclear. Methods: Transcriptional profiles and clinicopathological information were retrieved from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) of LUAD patients. A total of 31 overlapped ramRNAs were determined, and patients were separated into three subtypes by unsupervised consensus clustering. Biological functions and tumor immune-infiltrating levels were analyzed, and then, differentially expressed genes (DEGs) were identified. The TCGA cohort was divided into a training set and an internal validation set at a ratio of 6:4. Least absolute shrinkage and selection operator regression were used to compute the risk score and determine the risk cutoff in the training set. Both TCGA and GEO cohort were distinguished into a high-risk or low-risk group at the median cutoff, and then, relationships of mutation characteristics, tumor stemness, immune differences, and drug sensitivity were investigated. Results: Five optimal signatures (ANLN, HLA-DQA1, RHOV, TLR2, and TYMS) were selected. Patients in the high-risk group had poorer prognosis, higher tumor mutational burden, overexpression of PD-L1, and lower immune dysfunction and exclusion score compared with the low-risk group. Cisplatin, docetaxel, and gemcitabine had significantly lower IC₅₀ in the high-risk group. Conclusion: This study constructed a novel predictive signature of LUAD based on redox-associated genes. Risk score based on ramRNAs served as a promising biomarker for prognosis, TME, and anti-cancer therapies of LUAD.

Concurrent silencing of TBCE and drug delivery to overcome platinum-based resistance in liver cancer

Platinum-based chemotherapy resistance is a key factor of poor prognosis and recurrence in hepatocellular carcinoma (HCC). Herein, RNAseq analysis revealed that elevated tubulin folding cofactor E (TBCE) expression is associated with platinum-based chemotherapy resistance. High expression of TBCE contributes to worse prognoses and earlier recurrence among liver cancer patients. Mechanistically, TBCE silencing significantly affects cytoskeleton rearrangement, which in turn increases cisplatin-induced cycle arrest and apoptosis. To develop these findings into potential therapeutic drugs, endosomal pH-responsive nanoparticles (NPs) were developed to simultaneously encapsulate TBCE siRNA and cisplatin (DDP) to reverse this phenomena. NPs (siTBCE + DDP) concurrently silenced TBCE expression, increased cell sensitivity to platinum treatment, and subsequently resulted in superior anti-tumor effects both in vitro and in vivo in orthotopic and patient-derived xenograft (PDX) models. Taken together, NP-mediated delivery and the co-treatment of siTBCE + DDP proved to be effective in reversing chemotherapy resistance of DDP in multiple tumor models.

Novel Green Approaches for the Preparation of Gold Nanoparticles and Their Promising Potential in Oncology

The difficulty of achieving targeted drug delivery following administration of currently marketed anticancer therapeutics is a still a concern. Metallic nanoparticles (NPs) developed through nanotechnology breakthroughs appear to be promising in this regard. Research studies pertaining to gold NPs have indicated their promising applicability in cancer diagnosis, drug delivery and therapy. These NPs have also recently paved the path for precise drug delivery and site-specific targeting. Our review paper thus highlights the scope and impact of biogenetically generated gold nanoparticles (NPs) in cancer therapy. In a critical, constructive, and methodical manner, we compare the advantages offered by gold NPs over other metal NPs. Moreover, we also focus on novel ‘greener’ strategies that have been recently explored for the preparation of gold NPs and shed light on the disadvantages of conventional NP synthesis routes. Future prospects pertaining to the use of gold NPs in oncotherapy and domains that require further investigation are also addressed.

Acquired temozolomide resistance in MGMTlow gliomas is associated with regulation of homologous recombination repair by ROCK2

It was reported that MGMT^low gliomas may still be resistant to TMZ, while the mechanisms remain poorly understood. In this study, we demonstrated that rho-associated kinase 2 (ROCK2), a cytoskeleton regulator, was highly expressed in MGMT^low recurrent gliomas, and its expression strongly correlated with poor overall survival (OS) time in a subset of MGMT^low recurrent gliomas patients with TMZ therapy. And we also found that overactive ROCK2 enhanced homologous recombination repair (HR) in TMZ-resistant (TMZ-R) glioma cell lines with low MGMT expression. Silencing ROCK2 impaired HR repair, and induced double-strand break (DSB) and eradicated TMZ-R glioma cells in culture. Notably, in MGMT^low TMZ-R models, as a key factor of HR, ataxia telangiectasia-mutated (ATM) expression was upregulated directly by hyper-activation of ROCK2 to improve HR efficiency. ROCK2 enhanced the binding of transcription factor zinc finger E-box binding homeobox 1 (ZEB1) to ATM promoter for increasing ATM expression. Moreover, ROCK2 transformed ZEB1 into a gene activator via Yes-associated protein 1 (YAP1). These results provide evidence for the use of ROCK inhibitors in the clinical therapy for MGMT^low TMZ-resistant glioma. Our study also offered novel insights for improving therapeutic management of MGMT^low gliomas.

Rho-Kinase as a Target for Cancer Therapy and Its Immunotherapeutic Potential

Cancer immunotherapy is fast rising as a prominent new pillar of cancer treatment, harnessing the immune system to fight against numerous types of cancer. Rho-kinase (ROCK) pathway is involved in diverse cellular activities, and is therefore the target of interest in various diseases at the cellular level including cancer. Indeed, ROCK is well-known for its involvement in the tumor cell and tumor microenvironment, especially in its ability to enhance tumor cell progression, migration, metastasis, and extracellular matrix remodeling. Importantly, ROCK is also considered to be a novel and effective modulator of immune cells, although further studies are needed. In this review article, we describe the various activities of ROCK and its potential to be utilized in cancer treatment, particularly in cancer immunotherapy, by shining a light on its activities in the immune system.

RhoGTPase Signalling in Cancer Progression and Dissemination

Rho GTPases are a family of small G proteins that regulate a wide array of cellular processes related to their key roles controlling the cytoskeleton. On the other hand, cancer is a multi-step disease caused by the accumulation of genetic mutations and epigenetic alterations, from the initial stages of cancer development when cells in normal tissues undergo transformation, to the acquisition of invasive and metastatic traits, responsible for a large number of cancer related deaths. In this review, we discuss the role of Rho GTPase signalling in cancer in every step of disease progression. Rho GTPases contribute to tumour initiation and progression, by regulating proliferation and apoptosis, but also metabolism, senescence and cell stemness. Rho GTPases play a major role in cell migration, and in the metastatic process. They are also involved in interactions with the tumour microenvironment and regulate inflammation, contributing to cancer progression. After years of intensive research, we highlight the importance of relevant models in the Rho GTPase field, and we reflect on the therapeutic opportunities arising for cancer patients.

A preclinical pipeline to evaluate migrastatics as therapeutic agents in metastatic melanoma

BACKGROUND

Metastasis is a hallmark of cancer and responsible for most cancer deaths. Migrastatics were defined as drugs interfering with all modes of cancer cell invasion and thus cancers' ability to metastasise. First anti-metastatic treatments have recently been approved.

METHODS

We used bioinformatic analyses of publicly available melanoma databases. Experimentally, we performed in vitro target validation (including 2.5D cell morphology analysis and mass spectrometric analysis of RhoA binding partners), developed a new traceable spontaneously metastasising murine melanoma model for in vivo validation, and employed histology (haematoxylin/eosin and phospho-myosin II staining) to confirm drug action in harvested tumour tissues.

RESULTS

Unbiased and targeted bioinformatic analyses identified the Rho kinase (ROCK)-myosin II pathway and its various components as potentially relevant targets in melanoma. In vitro validation demonstrated redundancy of several RhoGEFs upstream of RhoA and confirmed ROCK as a druggable target downstream of RhoA. The anti-metastatic effects of two ROCK inhibitors were demonstrated through in vivo melanoma metastasis tracking and inhibitor effects also confirmed ex vivo by digital pathology.

CONCLUSIONS

We proposed a migrastatic drug development pipeline. As part of the pipeline, we provide a new traceable spontaneous melanoma metastasis model for in vivo quantification of metastasis and anti-metastatic effects by non-invasive imaging.

Location, location, location: Melanoma cells "living at the edge"

Abnormal cell migration and invasion underlie metastatic dissemination, one of the major challenges for cancer treatment. Melanoma is one of the deadliest and most aggressive forms of skin cancer due in part to its migratory and metastatic potential. Cancer cells use a variety of migratory strategies regulated by cytoskeletal remodelling. In particular, we discuss the importance of amoeboid invasive melanoma strategies, since they have been identified at the edge of human melanomas. We hypothesize that the presence of amoeboid melanoma cells will favour tumor progression since they are invasive and metastatic; they support immunosuppression; they harbour cancer stem cell properties and they are involved in therapy resistance. The Rho-ROCK-Myosin II pathway is key to maintain amoeboid melanoma invasion but this pathway is further regulated by pro-tumorigenic/pro-metastatic/pro-survival signalling pathways such as JAK-STAT3, TGFβ-SMAD, NF-κB, Wnt11/5-FDZ7 and BRAF^V600E -MEK-ERK. These pathways support amoeboid behaviour and are actionable in the clinic. After melanoma wide surgical margin removal, we propose that possible remaining melanoma cells should be eradicated using anti-amoeboid therapies.

GTPases, genome, actin: A hidden story in DNA damage response and repair mechanisms

The classical small Rho GTPase (Rho, Rac, and Cdc42) protein family is mainly responsible for regulating cell motility and polarity, membrane trafficking, cell cycle control, and gene transcription. Cumulative recent evidence supports important roles for these proteins in the maintenance of genomic stability. Indeed, DNA damage response (DDR) and repair mechanisms are some of the prime biological processes that underlie several disease phenotypes, including genetic disorders, cancer, senescence, and premature aging. Many reports guided by different experimental approaches and molecular hypotheses have demonstrated that, to some extent, direct modulation of Rho GTPase activity, their downstream effectors, or actin cytoskeleton regulation contribute to these cellular events. Although much attention has been paid to this family in the context of canonical actin cytoskeleton remodeling, here we provide a contextualized review of the interplay between Rho GTPase signaling pathways and the DDR and DNA repair signaling components. Interesting questions yet to be addressed relate to the spatiotemporal dynamics of this collective response and whether it correlates with different subcellular pools of Rho GTPases. We highlight the direct and indirect targets, some of which still lack experimental validation data, likely associated with Rho GTPase activation that provides compelling evidence for further investigation in DNA damage-associated events and with potential therapeutic applications in translational medicine.

Role of Small GTPase RhoA in DNA Damage Response

Accumulating evidence has suggested a role of the small GTPase Ras homolog gene family member A (RhoA) in DNA damage response (DDR) in addition to its traditional function of regulating cell morphology. In DDR, 2 key components of DNA repair, ataxia telangiectasia-mutated (ATM) and flap structure-specific endonuclease 1 (FEN1), along with intracellular reactive oxygen species (ROS) have been shown to regulate RhoA activation. In addition, Rho-specific guanine exchange factors (GEFs), neuroepithelial transforming gene 1 (Net1) and epithelial cell transforming sequence 2 (Ect2), have specific functions in DDR, and they also participate in Ras-related C3 botulinum toxin substrate 1 (Rac1)/RhoA interaction, a process which is largely unappreciated yet possibly of significance in DDR. Downstream of RhoA, current evidence has highlighted its role in mediating cell cycle arrest, which is an important step in DNA repair. Unraveling the mechanism by which RhoA modulates DDR may provide more insight into DDR itself and may aid in the future development of cancer therapies.

WNT11-FZD7-DAAM1 signalling supports tumour initiating abilities and melanoma amoeboid invasion

Melanoma is a highly aggressive tumour that can metastasize very early in disease progression. Notably, melanoma can disseminate using amoeboid invasive strategies. We show here that high Myosin II activity, high levels of ki-67 and high tumour-initiating abilities are characteristic of invasive amoeboid melanoma cells. Mechanistically, we find that WNT11-FZD7-DAAM1 activates Rho-ROCK1/2-Myosin II and plays a crucial role in regulating tumour-initiating potential, local invasion and distant metastasis formation. Importantly, amoeboid melanoma cells express both proliferative and invasive gene signatures. As such, invasive fronts of human and mouse melanomas are enriched in amoeboid cells that are also ki-67 positive. This pattern is further enhanced in metastatic lesions. We propose eradication of amoeboid melanoma cells after surgical removal as a therapeutic strategy.

Mahogunin Ring Finger 1 Is Required for Genomic Stability and Modulates the Malignant Phenotype of Melanoma Cells

Simple Summary

Melanoma, the most aggressive skin cancer, accounts for the majority of deaths due to this disease. Therefore, identification of genes/proteins involved in melanoma genesis and/or progression is urgent. Mutations abrogating expression of Mahogunin Ring Finger 1 (MGRN1) in mice cause complex phenotypes with hyperpigmentation, and known MGRN1 interactors are important regulators of cell shape and movement. This suggests that MGRN1 may modulate the malignant phenotype of melanoma cells. Analysis of MGRN1-KO mouse melanocytes and melanoma cells showed that lack of MGRN1 leads to cell cycle defects and to a more differentiated, less aggressive phenotype, with increased adhesion to various matrices, decreased motility and high genomic instability. The higher aggressivity of MGRN1-expressing melanoma cells was confirmed in an in vivo mouse melanoma model and is consistent with higher survival of human melanoma patients expressing low levels of MGRN1. Therefore, MGRN1 appears an important determinant of the malignant phenotype of melanoma.

Abstract

The mouse mahoganoid mutation abrogating Mahogunin Ring Finger-1 (MGRN1) E3 ubiquitin ligase expression causes hyperpigmentation, congenital heart defects and neurodegeneration. To study the pathophysiology of MGRN1 loss, we compared Mgrn1-knockout melanocytes with genetically matched controls and melan-md1 (mahoganoid) melanocytes. MGRN1 knockout induced a more differentiated and adherent phenotype, decreased motility, increased the percentage of cells in the S phase of the cell cycle and promoted genomic instability, as shown by stronger γH2AX labelling, increased burden of DNA breaks and higher abundance of aneuploid cells. Lack of MGRN1 expression decreased the ability of melanocytes to cope with DNA breaks generated by oxidizing agents or hydroxyurea-induced replicative stress, suggesting a contribution of genomic instability to the mahoganoid phenotype. MGRN1 knockout in B16-F10 melanoma cells also augmented pigmentation, increased cell adhesion to collagen, impaired 2D and 3D motility and caused genomic instability. Tumors formed by Mgrn1-KO B16-F10 cells had lower mitotic indices, fewer Ki67-positive cells and showed a trend towards smaller size. In short-term lung colonization assays Mgrn1-KO cells showed impaired colonization potential. Moreover, lower expression of MGRN1 is significantly associated with better survival of human melanoma patients. Therefore, MGRN1 might be an important phenotypic determinant of melanoma cells.

First-in-Human Study of AT13148, a Dual ROCK-AKT Inhibitor in Patients with Solid Tumors

PURPOSE

AT13148 is an oral AGC kinase inhibitor, which potently inhibits ROCK and AKT kinases. In preclinical models, AT13148 has been shown to have antimetastatic and antiproliferative activity.

PATIENTS AND METHODS

The trial followed a rolling six design during dose escalation. An intrapatient dose escalation arm to evaluate tolerability and a biopsy cohort to study pharmacodynamic effects were later added. AT13148 was administered orally three days a week (Mon-Wed-Fri) in 28-day cycles. Pharmacokinetic profiles were assessed using mass spectrometry and pharmacodynamic studies included quantifying p-GSK3β levels in platelet-rich plasma (PRP) and p-cofilin and p-MLC2 levels in tumor biopsies.

RESULTS

Fifty-one patients were treated on study. The safety of 5-300 mg of AT13148 was studied. Further, the doses of 120-180-240 mg were studied in an intrapatient dose escalation cohort. The dose-limiting toxicities included hypotension (300 mg), pneumonitis, and elevated liver enzymes (240 mg), and skin rash (180 mg). The most common side effects were fatigue, nausea, headaches, and hypotension. On the basis of tolerability, 180 mg was considered the maximally tolerated dose. At 180 mg, mean C max and AUC were 400 nmol/L and 13,000 nmol/L/hour, respectively. At 180 mg, ≥50% reduction of p-cofilin was observed in 3 of 8 posttreatment biopsies.

CONCLUSIONS

AT13148 was the first dual potent ROCK-AKT inhibitor to be investigated for the treatment of solid tumors. The narrow therapeutic index and the pharmacokinetic profile led to recommend not developing this compound further. There are significant lessons learned in designing and testing agents that simultaneously inhibit multiple kinases including AGC kinases in cancer.

CDC42EP5/BORG3 modulates SEPT9 to promote actomyosin function, migration, and invasion

Fast amoeboid migration is critical for developmental processes and can be hijacked by cancer cells to enhance metastatic dissemination. This migratory behavior is tightly controlled by high levels of actomyosin contractility, but how it is coupled to other cytoskeletal components is poorly understood. Septins are increasingly recognized as novel cytoskeletal components, but details on their regulation and contribution to migration are lacking. Here, we show that the septin regulator Cdc42EP5 is consistently required for amoeboid melanoma cells to invade and migrate into collagen-rich matrices and locally invade and disseminate in vivo. Cdc42EP5 associates with actin structures, leading to increased actomyosin contractility and amoeboid migration. Cdc42EP5 affects these functions through SEPT9-dependent F-actin cross-linking, which enables the generation of F-actin bundles required for the sustained stabilization of highly contractile actomyosin structures. This study provides evidence that Cdc42EP5 is a regulator of cancer cell motility that coordinates actin and septin networks and describes a unique role for SEPT9 in melanoma invasion and metastasis.

RHOAming Through the Nucleotide Excision Repair Pathway as a Mechanism of Cellular Response Against the Effects of UV Radiation

Typical Rho GTPases include the enzymes RhoA, Rac1, and Cdc42 that act as molecular switches to regulate essential cellular processes in eukaryotic cells such as actomyosin dynamics, cell cycle, adhesion, death and differentiation. Recently, it has been shown that different conditions modulate the activity of these enzymes, but their functions still need to be better understood. Here we examine the interplay between RhoA and the NER (Nucleotide Excision Repair) pathway in human cells exposed to UVA, UVB or UVC radiation. The results show high levels and accumulation of UV-induced DNA lesions (strand breaks and cyclobutane pyrimidine dimers, CPDs) in different cells with RhoA loss of function (LoF), either by stable overexpression of negative dominant RhoA (RhoA-N19 mutant), by inhibition with C3 toxin or by transient silencing with siRNA. Cells under RhoA LoF showed reduced levels of γH2AX, p-Chk1 (Ser345) and p-p53 (Ser15) that reflected causally in their accumulation in G1/S phases, in low survival rates and in reduced cell proliferation, also in accordance with the energy of applied UV light. Even NER-deficient cells (XPA, XPC) or DNA translesion synthesis (TLS)-deficient cells (XPV) showed substantial hypersensitivity to UV effects when previously submitted to RhoA LoF. In contrast, analyses of apoptosis, necrosis, autophagy and senescence revealed that all cells displaying normal levels of active RhoA (RhoA-GTP) are more resistant to UV-promoted cell death. This work reaffirms the role of RhoA protein signaling in protecting cells from damage caused by UV radiation and demonstrates relevant communicating mechanisms between actin cytoskeleton and genomic stability.

Delineating the role of membrane blebs in a hybrid mode of cancer cell invasion in three-dimensional environments

The study of cancer cell invasion in 3D environments in vitro has revealed a variety of invasive modes, including amoeboid migration, characterized by primarily round cells that invade in a protease- and adhesion-independent manner. Here, we delineate a contractility-dependent migratory mode of primarily round breast cancer cells that is associated with extensive integrin-mediated extracellular matrix (ECM) reorganization that occurs at membrane blebs, with bleb necks sites of integrin clustering and integrin-dependent ECM alignment. We show that the spatiotemporal distribution of blebs and their utilization for ECM reorganization is mediated by functional β1 integrin receptors and other components of focal adhesions. Taken together, the work presented here characterizes a migratory mode of primarily round cancer cells in complex 3D environments and reveals a fundamentally new function for membrane blebs in cancer cell invasion.

Sirt3 Exerts Its Tumor-Suppressive Role by Increasing p53 and Attenuating Response to Estrogen in MCF-7 Cells

Estrogen (E2) is a major risk factor for the initiation and progression of malignancy in estrogen receptor (ER) positive breast cancers, whereas sirtuin 3 (Sirt3), a major mitochondrial NAD⁺-dependent deacetylase, has the inhibitory effect on the tumorigenic properties of ER positive MCF-7 breast cancer cells. Since it is unclear if this effect is mediated through the estrogen receptor alpha (ERα) signaling pathway, in this study, we aimed to determine if the tumor-suppressive function of Sirt3 in MCF-7 cells interferes with their response to E2. Although we found that Sirt3 improves the antioxidative response and mitochondrial fitness of the MCF-7 cells, it also increases DNA damage along with p53, AIF, and ERα expression. Moreover, Sirt3 desensitizes cells to the proliferative effect of E2, affects p53 by disruption of the ERα–p53 interaction, and decreases proliferation, colony formation, and migration of the cells. Our observations indicate that these tumor-suppressive effects of Sirt3 could be reversed by E2 treatment only to a limited extent which is not sufficient to recover the tumorigenic properties of the MCF-7 cells. This study provides new and interesting insights with respect to the functional role of Sirt3 in the E2-dependent breast cancers.

What does not kill you makes you stronger: surviving anti-cancer therapies by cytoskeletal remodeling and Myosin II reactivation

Myosin II and its regulator Rho-associated coiled-coil containing protein kinase (ROCK) are essential for cell invasion and metastatic dissemination. Our recent findings show that this molecular machinery is also involved in drug resistance in melanoma by playing a dual role: protection of tumor cells from reactive oxygen species (ROS) and DNA damage (intrinsic), and co-option of myeloid and lymphoid populations to establish immunosuppression (extrinsic).

Cytoskeletal Proteins in Cancer and Intracellular Stress: A Therapeutic Perspective

Cytoskeletal proteins, which consist of different sub-families of proteins including microtubules, actin and intermediate filaments, are essential for survival and cellular processes in both normal as well as cancer cells. However, in cancer cells, these mechanisms can be altered to promote tumour development and progression, whereby the functions of cytoskeletal proteins are co-opted to facilitate increased migrative and invasive capabilities, proliferation, as well as resistance to cellular and environmental stresses. Herein, we discuss the cytoskeletal responses to important intracellular stresses (such as mitochondrial, endoplasmic reticulum and oxidative stresses), and delineate the consequences of these responses, including effects on oncogenic signalling. In addition, we elaborate how the cytoskeleton and its associated molecules present themselves as therapeutic targets. The potential and limitations of targeting new classes of cytoskeletal proteins are also explored, in the context of developing novel strategies that impact cancer progression.

Myosin II Reactivation and Cytoskeletal Remodeling as a Hallmark and a Vulnerability in Melanoma Therapy Resistance

Despite substantial clinical benefit of targeted and immune checkpoint blockade-based therapies in melanoma, resistance inevitably develops. We show cytoskeletal remodeling and changes in expression and activity of ROCK-myosin II pathway during acquisition of resistance to MAPK inhibitors. MAPK regulates myosin II activity, but after initial therapy response, drug-resistant clones restore myosin II activity to increase survival. High ROCK-myosin II activity correlates with aggressiveness, identifying targeted therapy- and immunotherapy-resistant melanomas. Survival of resistant cells is myosin II dependent, regardless of the therapy. ROCK-myosin II ablation specifically kills resistant cells via intrinsic lethal reactive oxygen species and unresolved DNA damage and limits extrinsic myeloid and lymphoid immunosuppression. Efficacy of targeted therapies and immunotherapies can be improved by combination with ROCK inhibitors.

Effect of silencing of mediator of DNA damage checkpoint protein 1 on the growth of oral squamous cell carcinoma in vitro and in vivo

Mediator of DNA damage checkpoint protein 1 (MDC1) is involved in DNA damage repair and has been linked to tumor invasion, metastasis, and prognosis. This study investigated the effects of MDC1 in oral squamous cell carcinoma (OSCC) in vitro and in vivo. RNA interference-mediated knockdown of MDC1 was performed in two OSCC cell lines (Tca-8113 and KB). Real-time PCR and western blotting were performed to determine expression of mRNA and protein, respectively, of MDC1. Cell viability was assessed using the MTT assay. Colony-formation assays were performed by staining with 0.5% crystal violet. Cell migration and invasion were detected by Transwell assays. The role of MDC1 in OSCC was examined in vivo via injection of Tca-8113 cells transfected with MDC1 small interfering (si)RNA or negative-control siRNA into a mouse xenograft model of OSCC. Our results showed that MDC1 knockdown decreased cell proliferation. Inhibition of MDC1 decreased colony formation of Tca-8113 and KB cells by 62% and 68%, respectively, and MDC1 knockdown reduced the number of migratory and invasive cells compared with the control group. Moreover, the xenograft mouse model of MDC1 knockdown showed reduced tumor growth. Our study suggests that MDC1 plays a role in tumorigenesis and might be a potential target for the treatment of patients with OSCC.

Recent advances in tissue imaging for cancer research

Image analysis in clinical research has evolved at fast pace in the last decade. This review discusses basic concepts ranging from immunohistochemistry to advanced techniques such as multiplex imaging, digital pathology, flow cytometry and intravital microscopy. Tissue imaging ex vivo is still one of the gold-standards in the field due to feasibility. We describe here different protocols and applications of digital analysis providing basic and clinical researchers with an overview on how to analyse tissue images. In vivo imaging is not easily accessible to researchers; however, it provides invaluable dynamic information. Overall, we discuss a plethora of techniques that - when combined - constitute a powerful platform for basic and translational cancer research.

Overlapping and unique roles played by ROCK1 and 2 in the modulation of coding and long noncoding RNA expression

Background

Our previous study described the crucial role of Rho-associated coiled-coil containing-kinases (ROCK) in hepatocellular carcinoma (HCC). However, the potential significance of long noncoding RNA downstream of ROCK is largely unknown. Here, a comprehensive comparative bioinformatics analysis of a microarray of an MHCC-97H cell line overexpressing ROCK1 or ROCK2 was performed.

Results

Numerous lncRNAs and mRNAs were deregulated by Rho-associated coiled-coil containing kinases 1 and 2. These results were consistent with the qRT-PCR results. Compared with MHCC-97H-Con, which was transfected with a null vector, the GO analysis revealed differentially expressed mRNAs (DEmRNAs) in MHCC-97H-ROCK1 (ROCK1 was overexpressed) enriched in apoptotic cell clearance, the cyclooxygenase pathway and bone trabecula morphogenesis; the DEmRNAs in MHCC-97H-ROCK2 (ROCK2 was overexpressed) were enriched in VEGF production, chemokine-associated signaling pathways, acute inflammatory response and vasoconstriction. Compared with MHCC-97H-ROCK2, the DEmRNAs in MHCC-97H-ROCK1 were involved in the JAK-STAT cascade, the Akt signaling pathway and the activity of several different peptidases. The pathway analysis of ROCK1 and ROCK2 revealed an overlap in the VEGF signaling pathway, ECM-receptor interaction, and adhesion and differences in the PPAR signaling pathway and mismatch repair. The predicted targets of the differentially expressed lncRNA (DElncRNAs) were enriched in the p53 signaling pathway, Jak-STAT signaling pathway, etc.

Several hub DElncRNAs were identified.

Conclusions

ROCK1 and 2 modulate the expression of numerous mRNAs and lncRNAs and may participate in several signaling pathways in HCC. Several hub molecules were identified in the lncRNA-mRNA networks. Our results provide baseline data for ROCK1 and 2 regulation in HCC that might have implications for further research.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5715-0) contains supplementary material, which is available to authorized users.

Bad company: Microenvironmentally mediated resistance to targeted therapy in melanoma

This review will focus on the role of the tumor microenvironment (TME) in the development of drug resistance in melanoma. Resistance to mitogen-activated protein kinase inhibitors (MAPKi) in melanoma is observed months after treatment, a phenomenon that is often attributed to the incredible plasticity of melanoma cells but may also depend on the TME. The TME is unique in its cellular composition-it contains fibroblasts, immune cells, endothelial cells, adipocytes, and among others. In addition, the TME provides "non-homeostatic" levels of oxygen, nutrients (hypoxia and metabolic stress), and extracellular matrix proteins, creating a pro-tumorigenic niche that drives resistance to MAPKi treatment. In this review, we will focus on how changes in the tumor microenvironment regulate MAPKi resistance.

Regional Activation of Myosin II in Cancer Cells Drives Tumor Progression via a Secretory Cross-Talk with the Immune Microenvironment

ROCK-Myosin II drives fast rounded-amoeboid migration in cancer cells during metastatic dissemination. Analysis of human melanoma biopsies revealed that amoeboid melanoma cells with high Myosin II activity are predominant in the invasive fronts of primary tumors in proximity to CD206+CD163+ tumor-associated macrophages and vessels. Proteomic analysis shows that ROCK-Myosin II activity in amoeboid cancer cells controls an immunomodulatory secretome, enabling the recruitment of monocytes and their differentiation into tumor-promoting macrophages. Both amoeboid cancer cells and their associated macrophages support an abnormal vasculature, which ultimately facilitates tumor progression. Mechanistically, amoeboid cancer cells perpetuate their behavior via ROCK-Myosin II-driven IL-1α secretion and NF-κB activation. Using an array of tumor models, we show that high Myosin II activity in tumor cells reprograms the innate immune microenvironment to support tumor growth. We describe an unexpected role for Myosin II dynamics in cancer cells controlling myeloid function via secreted factors.

Increased Chromosome Aberrations in Cells Exposed Simultaneously to Simulated Microgravity and Radiation

Space radiation and microgravity (μG) are two major environmental stressors for humans in space travel. One of the fundamental questions in space biology research is whether the combined effects of μG and exposure to cosmic radiation are interactive. While studies addressing this question have been carried out for half a century in space or using simulated μG on the ground, the reported results are ambiguous. For the assessment and management of human health risks in future Moon and Mars missions, it is necessary to obtain more basic data on the molecular and cellular responses to the combined effects of radiation and µG. Recently we incorporated a μG⁻irradiation system consisting of a 3D clinostat synchronized to a carbon-ion or X-ray irradiation system. Our new experimental setup allows us to avoid stopping clinostat rotation during irradiation, which was required in all other previous experiments. Using this system, human fibroblasts were exposed to X-rays or carbon ions under the simulated μG condition, and chromosomes were collected with the premature chromosome condensation method in the first mitosis. Chromosome aberrations (CA) were quantified by the 3-color fluorescent in situ hybridization (FISH) method. Cells exposed to irradiation under the simulated μG condition showed a higher frequency of both simple and complex types of CA compared to cells irradiated under the static condition by either X-rays or carbon ions.

p53-inducible gene 3 promotes cell migration and invasion by activating the FAK/Src pathway in lung adenocarcinoma

The p53-inducible gene 3 (PIG3) is one of the p53-induced genes at the onset of apoptosis, which plays an important role in cell apoptosis and DNA damage response. Our previous study reported an oncogenic role of PIG3 associated with tumor progression and metastasis in non-small cell lung cancer (NSCLC). In this study, we further analyzed PIG3 mRNA expression in 504 lung adenocarcinoma (LUAD) and 501 lung squamous cell carcinoma (LUSC) tissues from The Cancer Genome Atlas database and we found that PIG3 expression was significantly higher in LUAD with lymph node metastasis than those without, while no difference was observed between samples with and without lymph node metastasis in LUSC. Gain and loss of function experiments were performed to confirm the metastatic role of PIG3 in vitro and to explore the mechanism involved in its oncogenic role in NSCLC metastasis. The results showed that PIG3 knockdown significantly inhibited the migration and invasion ability of NSCLC cells, and decreased paxillin, phospho-focal adhesion kinase (FAK) and phospho-Src kinase expression, while its overexpression resulted in the opposite effects. Blocking FAK with its inhibitor reverses PIG3 overexpression-induced cell motility in NSCLC cells, indicating that PIG3 increased cell metastasis through the FAK/Src/paxillin pathway. Furthermore, PIG3 silencing sensitized NSCLC cells to FAK inhibitor. In conclusion, our data revealed a role for PIG3 in inducing LUAD metastasis, and its role as a new FAK regulator, suggesting that it could be considered as a novel prognostic biomarker or therapeutic target in the treatment of LUAD metastasis.

Redox control in cancer development and progression

Cancer is the leading cause of death worldwide after cardiovascular diseases. This has been the case for the last few decades despite there being an increase in the number of cancer treatments. One reason for the apparent lack of drug effectiveness might be, at least in part, due to unspecificity for tumors; which often leads to substantial side effects. One way to improve the treatment of cancer is to increase the specificity of the treatment in accordance with the concept of individualized medicine. This will help to prevent further progression of an existing cancer or even to reduce the tumor burden. Alternatively it would be much more attractive and efficient to prevent the development of cancer in the first place. Therefore, it is important to understand the risk factors and the mechanisms of carcinogenesis in detail. One such risk factor, often associated with tumorigenesis and tumor progression, is an increased abundance of reactive oxygen species (ROS) arising from an imbalance of ROS-producing and -eliminating components. A surplus of ROS can induce oxidative damage of macromolecules including proteins, lipids and DNA. In contrast, ROS are essential for an adequate signal transduction and are known to regulate crucial cellular processes like cellular quiescence, differentiation and even apoptosis. Therefore, regulated ROS-formation at physiological levels can inhibit tumor formation and progression. With this review we provide an overview on the current knowledge of redox control in cancer development and progression.

Crosstalk between Rac1-mediated actin regulation and ROS production

The small RhoGTPase Rac1 is implicated in a variety of events related to actin cytoskeleton rearrangement. Remarkably, another event that is completely different from those related to actin regulation has the same relevance; the Rac1-mediated production of reactive oxygen species (ROS) through NADPH oxidases (NOX). Each outcome involves different Rac1 downstream effectors; on one hand, events related to the actin cytoskeleton require Rac1 to bind to WAVEs proteins and PAKs that ultimately promote actin branching and turnover, on the other, NOX-derived ROS production demands active Rac1 to be bound to a cytosolic activator of NOX. How Rac1-mediated signaling ends up promoting actin-related events, NOX-derived ROS, or both is poorly understood. Rac1 regulators, including scaffold proteins, are known to exert tight control over its functions. Hence, evidence of Rac1 regulatory events leading to both actin remodeling and NOX-mediated ROS generation are discussed. Moreover, cellular functions linked to physiological and pathological conditions that exhibit crosstalk between Rac1 outcomes are analyzed, while plausible roles in neuronal functions (and dysfunctions) are highlighted. Together, discussed evidence shed light on cellular mechanisms which requires Rac1 to direct either actin- and/or ROS-related events, helping to understand crucial roles of Rac1 dual functionality.

The receptor tyrosine kinase EphA2 promotes glutamine metabolism in tumors by activating the transcriptional coactivators YAP and TAZ

Malignant tumors reprogram cellular metabolism to support cancer cell proliferation and survival. Although most cancers depend on a high rate of aerobic glycolysis, many cancer cells also display addiction to glutamine. Glutamine transporters and glutaminase activity are critical for glutamine metabolism in tumor cells. We found that the receptor tyrosine kinase EphA2 activated the TEAD family transcriptional coactivators YAP and TAZ (YAP/TAZ), likely in a ligand-independent manner, to promote glutamine metabolism in cells and mouse models of HER2-positive breast cancer. Overexpression of EphA2 induced the nuclear accumulation of YAP and TAZ and increased the expression of YAP/TAZ target genes. Inhibition of the GTPase Rho or the kinase ROCK abolished EphA2-dependent YAP/TAZ nuclear localization. Silencing YAP or TAZ substantially reduced the amount of intracellular glutamate through decreased expression of SLC1A5 and GLS, respectively, genes that encode proteins that promote glutamine uptake and metabolism. The regulatory DNA elements of both SLC1A5 and GLS contain TEAD binding sites and were bound by TEAD4 in an EphA2-dependent manner. In patient breast cancer tissues, EphA2 expression positively correlated with that of YAP and TAZ, as well as that of GLS and SLC1A5 Although high expression of EphA2 predicted enhanced metastatic potential and poor patient survival, it also rendered HER2-positive breast cancer cells more sensitive to glutaminase inhibition. The findings define a previously unknown mechanism of EphA2-mediated glutaminolysis through YAP/TAZ activation in HER2-positive breast cancer and identify potential therapeutic targets in patients.

Complementary ACSL isoforms contribute to a non-Warburg advantageous energetic status characterizing invasive colon cancer cells

Metabolic reprogramming is one of cancer hallmarks. Here, we focus on functional differences and individual contribution of acyl coA synthetases (ACSL) isoforms to the previously described ACSL/stearoyl-CoA desaturase (ACSL1/ACSL4/SCD) metabolic network causing invasion and poor prognosis in colorectal cancer (CRC). ACSL4 fuels proliferation and migration accompanied by a more glycolytic phenotype. Conversely, ACSL1 stimulates invasion displaying a lower basal respiratory rate. Acylcarnitines elevation, polyunsaturated fatty acids (PUFA) lower levels, and monounsaturated fatty acids (MUFA) upregulation characterize the individual overexpression of ACSL1, ACSL4 and SCD, respectively. However, the three enzymes simultaneous overexpression results in upregulated phospholipids and urea cycle derived metabolites. Thus, the metabolic effects caused by the network are far from being caused by the individual contributions of each enzyme. Furthermore, ACSL/SCD network produces more energetically efficient cells with lower basal respiration levels and upregulated creatine pathway. These features characterize other invasive CRC cells, thus, ACSL/SCD network exemplifies specific metabolic adaptations for invasive cancer cells.

Microarray analyses reveal genes related to progression and prognosis of esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma is a high morbidity and mortality cancer in China. Here are few biomarkers and therapeutic targets. Our study was aimed to identify candidate genes correlated to ESCC. Oncomine, The Cancer Genome Atlas, Gene Expression Omnibus were retrieved for eligible ESCC data. Deregulated genes were identified by meta-analysis and validated by an independent dataset. Survival analyses and bioinformatics analyses were used to explore potential mechanisms. Copy number variant analyses identified upstream mechanisms of candidate genes. In our study, top 200 up/down-regulated genes were identified across two microarrays. A total of 139 different expression genes were validated in GSE53625. Survival analysis found that nine genes were closely related to prognosis. Furthermore, Gene Ontology analyses and Kyoto Encyclopedia of Genes and Genomes analyses showed that different expression genes were mainly enriched in cell division, cell cycle and cell-cell adhesion pathways. Copy number variant analyses indicated that overexpression of ECT2 and other five genes were correlated with copy number amplification. The current study demonstrated that ECT2 and other eight candidate genes were correlated to progression and prognosis of esophageal squamous cell carcinoma, which might provide novel insights to the mechanisms.

The NADPH oxidase NOX4 represses epithelial to amoeboid transition and efficient tumour dissemination

Epithelial to mesenchymal transition is a common event during tumour dissemination. However, direct epithelial to amoeboid transition has not been characterized to date. Here we provide evidence that cells from hepatocellular carcinoma (HCC), a highly metastatic cancer, undergo epithelial to amoeboid transition in physiological environments, such as organoids or three-dimensional complex matrices. Furthermore, the NADPH oxidase NOX4 inhibits this transition and therefore suppresses efficient amoeboid bleb-based invasion. Moreover, NOX4 expression is associated with E-cadherin levels and inversely correlated with invasive features. NOX4 is necessary to maintain parenchymal structures, increase cell-cell and cell-to-matrix adhesion, and impair actomyosin contractility and amoeboid invasion. Importantly, NOX4 gene deletions are frequent in HCC patients, correlating with higher tumour grade. Contrary to that observed in mesenchymal cell types, here NOX4 suppresses Rho and Cdc42 GTPase expression and downstream actomyosin contractility. In HCC patients, NOX4 expression inversely correlates with RhoC and Cdc42 levels. Moreover, low expression of NOX4 combined with high expression of either RhoC or Cdc42 is associated with worse prognosis. Therefore, loss of NOX4 increases actomyosin levels and favours an epithelial to amoeboid transition contributing to tumour aggressiveness.

Glucose availability controls ATF4-mediated MITF suppression to drive melanoma cell growth

It is well know that cancer cells have adopted an altered metabolism and that glucose is a major source of energy for these cells. In melanoma, enhanced glucose usage is favoured through the hyper-activated MAPK pathway, which suppresses OXPHOS and stimulates glycolysis. However, it has not been addressed how glucose availability impacts on melanoma specific signaling pathways that drive melanoma cell proliferation. Here we show that melanoma cells are dependent on high glucose levels for efficient growth. Thereby, glucose metabolism controls the expression of the melanoma fate transcription factor MITF, a master regulator of melanoma cell survival and proliferation, invasion and therapy resistance. Restriction of glucose availability to physiological concentrations induces the production of reactive oxygen species (ROS). Increased ROS levels lead to the up-regulation of AFT4, which in turn suppresses MITF expression by competing with CREB, an otherwise potent inducer of the MITF promoter. Our data give new insight into the complex regulation of MITF, a key regulator of melanoma biology, and support previous findings that link metabolic disorders such as hyperglycemia and diabetes with increased melanoma risk.

Modes of invasion during tumour dissemination

Cancer cell migration and invasion underlie metastatic dissemination, one of the major problems in cancer. Tumour cells exhibit a striking variety of invasion strategies. Importantly, cancer cells can switch between invasion modes in order to cope with challenging environments. This ability to switch migratory modes or plasticity highlights the challenges behind antimetastasis therapy design. In this Review, we present current knowledge on different tumour invasion strategies, the determinants controlling plasticity and arising therapeutic opportunities. We propose that targeting master regulators controlling plasticity is needed to hinder tumour dissemination and metastasis.

So You Can Teach Old Fibroblasts New Tricks

New data show that as dermal fibroblasts grow old, they increase their secretion of the WNT antagonist sFRP2 to drive melanoma cell metastasis. sFRP2 suppresses β-catenin and MITF signaling in melanoma cells, downregulating the redox regulator APE1, making melanoma cells more sensitive to oxidative stress and driving resistance to BRAF inhibitors. Thus, the aging microenvironment in elderly patient skin activates a signaling pathway that drives more aggressive melanoma cell behavior. Cancer Discov; 6(6); 581-3. ©2016 AACR.

Rho, ROCK and actomyosin contractility in metastasis as drug targets

Metastasis is the spread of cancer cells around the body and the cause of the majority of cancer deaths. Metastasis is a very complex process in which cancer cells need to dramatically modify their cytoskeleton and cope with different environments to successfully colonize a secondary organ. In this review, we discuss recent findings pointing at Rho-ROCK or actomyosin force (or both) as major drivers of many of the steps required for metastatic success. We propose that these are important drug targets that need to be considered in the clinic to palliate metastatic disease.

The cytoskeleton adaptor protein ankyrin-1 is upregulated by p53 following DNA damage and alters cell migration

The integrity of the genome is maintained by a host of surveillance and repair mechanisms that are pivotal for cellular function. The tumour suppressor protein p53 is a major component of the DNA damage response pathway and plays a vital role in the maintenance of cell-cycle checkpoints. Here we show that a microRNA, miR-486, and its host gene ankyrin-1 (ANK1) are induced by p53 following DNA damage. Strikingly, the cytoskeleton adaptor protein ankyrin-1 was induced over 80-fold following DNA damage. ANK1 is upregulated in response to a variety of DNA damage agents in a range of cell types. We demonstrate that miR-486-5p is involved in controlling G1/S transition following DNA damage, whereas the induction of the ankyrin-1 protein alters the structure of the actin cytoskeleton and sustains limited cell migration during DNA damage. Importantly, we found that higher ANK1 expression correlates with decreased survival in cancer patients. Thus, these observations highlight ANK1 as an important effector downstream of the p53 pathway.

Reactive oxygen species and tumor dissemination: Allies no longer

For decades, reactive oxygen species (ROS) linked to oxidative stress have been suggested to promote carcinogenesis. However, we and others have demonstrated a protective role for ROS in metastatic dissemination. These recent studies partly explain the large failure observed in clinical trials using antioxidants for cancer prevention.