Cancer invasion and resistance: interconnected processes of disease progression and therapy failure

Cancer invasion and anaerobic bacteria: new insights into mechanisms

There is growing evidence that altered microbiota abundance of a range of specific anaerobic bacteria are associated with cancer, including Peptoniphilus spp., Porphyromonas spp., Fusobacterium spp., Fenollaria spp., Prevotella spp., Sneathia spp., Veillonella spp. and Anaerococcus spp. linked to multiple cancer types. In this review we explore these pathogenic associations. The mechanisms by which bacteria are known or predicted to interact with human cells are reviewed and we present an overview of the interlinked mechanisms and hypotheses of how multiple intracellular anaerobic bacterial pathogens may act together to cause host cell and tissue microenvironment changes associated with carcinogenesis and cancer cell invasion. These include combined effects on changes in cell signalling, DNA damage, cellular metabolism and immune evasion. Strategies for early detection and eradication of anaerobic cancer-associated bacterial pathogens that may prevent cancer progression are proposed.

Glycogen synthase kinase 3β: the nexus of chemoresistance, invasive capacity, and cancer stemness in pancreatic cancer

The treatment of pancreatic cancer remains a significant clinical challenge due to the limited number of patients eligible for curative (R0) surgery, failures in the clinical development of targeted and immune therapies, and the pervasive acquisition of chemotherapeutic resistance. Refractory pancreatic cancer is typified by high invasiveness and resistance to therapy, with both attributes related to tumor cell stemness. These malignant characteristics mutually enhance each other, leading to rapid cancer progression. Over the past two decades, numerous studies have produced evidence of the pivotal role of glycogen synthase kinase (GSK)3β in the progression of over 25 different cancer types, including pancreatic cancer. In this review, we synthesize the current knowledge on the pathological roles of aberrant GSK3β in supporting tumor cell proliferation and invasion, as well as its contribution to gemcitabine resistance in pancreatic cancer. Importantly, we discuss the central role of GSK3β as a molecular hub that mechanistically connects chemoresistance, tumor cell invasion, and stemness in pancreatic cancer. We also discuss the involvement of GSK3β in the formation of desmoplastic tumor stroma and in promoting anti-cancer immune evasion, both of which constitute major obstacles to successful cancer treatment. Overall, GSK3β has characteristics of a promising therapeutic target to overcome chemoresistance in pancreatic cancer.

TS-2021, a third-generation oncolytic adenovirus that carried Ki67 promoter, TGF-β2 5'UTR, and IL-15 against experimental glioblastoma

Oncolytic virotherapy is a promising therapeutic approach for glioblastoma (GBM) treatment, although the outcomes are partially satisfactory. Hence, more effective strategies are needed urgently to modify therapeutic viruses to enhance their efficiency and safety in killing tumor cells and improve the survival rate of GBM patients. This study generated a new-generation oncolytic adenovirus Ad5 KT-E1A-IL-15 (TS-2021) and evaluated its antitumor efficacy. Ex vivo analyses revealed Ki67 and TGF-β2 co-localized in GBM cells. In addition, TS-2021 selectively replicated in GBM cells, which was dependent on the expression of Ki67 and TGF-β2. The immunocompetent mice model of GBM demonstrated the in vivo efficacy of TS-2021 by inhibiting tumor growth and improving survival proficiently. Notably, TS-2021 effectively reduced MMP3 expression by inactivating the MKK4/JNK pathway, thereby reducing tumor invasiveness. Altogether, the findings of the present study highlight that TS-2021 can effectively target GBM cells expressing high levels of Ki67 and TGF-β2, exerting potent antitumor effects. Additionally, it can improve efficacy and suppress tumor invasiveness by inhibiting the MKK4/JNK/MMP3 pathway. Thus our study demonstrates the efficiency of the novel TS-2021 in the mouse model and provides a potential therapeutic option for patients with GBM.

Novel HER2-targeted therapy to overcome trastuzumab resistance in HER2-amplified gastric cancer

Trastuzumab is used to treat HER2-amplified metastatic gastric cancer; however, most patients become trastuzumab-resistant within a year. Knowledge of the mechanisms underlying trastuzumab resistance is required to overcome this limitation. Here, we aimed to elucidate this resistance mechanism using four trastuzumab-resistant (TR) cell lines and investigate the efficacy of HER2-targeted therapies to overcome treatment resistance. Each TR cell line had different phenotypic characteristics. Interestingly, HER2 expression remained as high as the parental cell lines in TR cell lines, suggesting that HER2-targeted agents were still useful. As expected, three tyrosine kinase inhibitors (lapatinib, neratinib, and tucatinib) and one antibody-drug conjugate (trastuzumab deruxtecan: T-DXd) exhibited good antitumor effects against TR cell lines. We further investigated the potential biological mechanism of T-DXd. When treated with trastuzumab or T-DXd, HER2 or its downstream signals were disrupted in parental cell lines, but not in TR cell lines. Moreover, T-DXd induced the expression of pH2A.X and cPARP and caused cell cycle arrest in the S or G2-M phase in TR cell lines. T-DXd showed promising antitumor activity in both parental and TR cell lines, suggesting that it is a potential candidate for overcoming trastuzumab resistance.

Pan-cancer whole-genome comparison of primary and metastatic solid tumours

Metastatic cancer remains an almost inevitably lethal disease1-3. A better understanding of disease progression and response to therapies therefore remains of utmost importance. Here we characterize the genomic differences between early-stage untreated primary tumours and late-stage treated metastatic tumours using a harmonized pan-cancer analysis (or reanalysis) of two unpaired primary4 and metastatic5 cohorts of 7,108 whole-genome-sequenced tumours. Metastatic tumours in general have a lower intratumour heterogeneity and a conserved karyotype, displaying only a modest increase in mutations, although frequencies of structural variants are elevated overall. Furthermore, highly variable tumour-specific contributions of mutational footprints of endogenous (for example, SBS1 and APOBEC) and exogenous mutational processes (for example, platinum treatment) are present. The majority of cancer types had either moderate genomic differences (for example, lung adenocarcinoma) or highly consistent genomic portraits (for example, ovarian serous carcinoma) when comparing early-stage and late-stage disease. Breast, prostate, thyroid and kidney renal clear cell carcinomas and pancreatic neuroendocrine tumours are clear exceptions to the rule, displaying an extensive transformation of their genomic landscape in advanced stages. Exposure to treatment further scars the tumour genome and introduces an evolutionary bottleneck that selects for known therapy-resistant drivers in approximately half of treated patients. Our data showcase the potential of pan-cancer whole-genome analysis to identify distinctive features of late-stage tumours and provide a valuable resource to further investigate the biological basis of cancer and resistance to therapies.

Fiber density and matrix stiffness modulate distinct cell migration modes in a 3D stroma mimetic composite hydrogel

The peritumoral stroma is a complex 3D tissue that provides cells with myriad biophysical and biochemical cues. Histologic observations suggest that during metastatic spread of carcinomas, these cues influence transformed epithelial cells, prompting a diversity of migration modes spanning single cell and multicellular phenotypes. Purported consequences of these variations in tumor escape strategies include differential metastatic capability and therapy resistance. Therefore, understanding how cues from the peritumoral stromal microenvironment regulate migration mode has both prognostic and therapeutic value. Here, we utilize a synthetic stromal mimetic in which matrix fiber density and bulk hydrogel mechanics can be orthogonally tuned to investigate the contribution of these two key matrix attributes on MCF10A migration mode phenotypes, epithelial-mesenchymal transition (EMT), and invasive potential. We develop an automated computational image analysis framework to extract migratory phenotypes from fluorescent images and determine 3D migration metrics relevant to metastatic spread. Using this analysis, we find that matrix fiber density and bulk hydrogel mechanics distinctly contribute to a variety of MCF10A migration modes including amoeboid, single mesenchymal, clusters, and strands. We identify combinations of physical and soluble cues that induce a variety of migration modes originating from the same MCF10A spheroid and use these settings to examine a functional consequence of migration mode -resistance to apoptosis. We find that cells migrating as strands are more resistant to staurosporine-induced apoptosis than either disconnected clusters or individual invading cells. Improved models of the peritumoral stromal microenvironment and understanding of the relationships between matrix attributes and cell migration mode can aid ongoing efforts to identify effective cancer therapeutics that address cell plasticity-based therapy resistances. STATEMENT OF SIGNIFICANCE: Stromal extracellular matrix structure dictates both cell homeostasis and activation towards migratory phenotypes. However decoupling the effects of myriad biophysical cues has been difficult to achieve. Here, we encapsulate electrospun fiber segments within an amorphous hydrogel to create a fiber-reinforced hydrogel composite in which fiber density and hydrogel stiffness can be orthogonally tuned. Quantification of 3D cell migration reveal these two parameters uniquely contribute to a diversity of migration phenotypes spanning amoeboid, single mesenchymal, multicellular cluster, and collective strand. By tuning biophysical and biochemical cues to elicit heterogeneous migration phenotypes, we find that collective strands best resist apoptosis. This work establishes a composite approach to modulate fibrous topography and bulk hydrogel mechanics and identified biomaterial parameters to direct distinct 3D cell migration phenotypes.

Loss of EPS8 sensitizes non-small-cell lung carcinoma to chemotherapy-induced DNA damage

Epidermal growth factor receptor pathway substrate number 8 (EPS8) has been reported to be critical in mediating tumor progression. However, the molecular and biological consequences of EPS8 overexpression remain unclear. Here we evaluated whether EPS8 increased DNA damage repair in non-small-cell lung carcinoma (NSCLC) cells and the mechanism of EPS8-mediated DNA damage repair which influenced chemosensitivity. Serial studies of functional experiments revealed that EPS8 knockdown inhibited cell growth, induced cell-cycle arrest and increased cisplatin therapeutic effects on NSCLC. EPS8 was found to induce DNA damage repair via upregulation of phosphorylated-ATM and downregulation of the tumor suppressor p53 and G1 cell kinase inhibitor p21. Moreover, in conjunction with cisplatin, decreasing EPS8 protein levels further increased p53 protein level and inhibited ATM signaling. Transplanted tumor studies were also performed to demonstrate that EPS8 knockdown inhibited tumor growth and sensitized tumors to cisplatin treatment. In conclusion, we have described a novel molecular mechanism through which EPS8 is likely to be involved in cancer progression and chemoresistance via DNA damage repair, indicating that EPS8 expression may influence the response to chemotherapy. Therefore, targeting EPS8 may be a potential therapeutic approach for patients with NSCLC.

Deep learning-based multi-drug synergy prediction model for individually tailored anti-cancer therapies

While synergistic drug combinations are more effective at fighting tumors with complex pathophysiology, preference compensating mechanisms, and drug resistance, the identification of novel synergistic drug combinations, especially complex higher-order combinations, remains challenging due to the size of combination space. Even though certain computational methods have been used to identify synergistic drug combinations in lieu of traditional in vitro and in vivo screening tests, the majority of previously published work has focused on predicting synergistic drug pairs for specific types of cancer and paid little attention to the sophisticated high-order combinations. The main objective of this study is to develop a deep learning-based approach that integrated multi-omics data to predict novel synergistic multi-drug combinations (DeepMDS) in a given cell line. To develop this approach, we firstly created a dataset comprising of gene expression profiles of cancer cell lines, target information of anti-cancer drugs, and drug response against a large variety of cancer cell lines. Based on the principle of a fully connected feed forward Deep Neural Network, the proposed model was constructed using this dataset, which achieved a high performance with a Mean Square Error (MSE) of 2.50 and a Root Mean Squared Error (RMSE) of 1.58 in the regression task, and gave the best classification accuracy of 0.94, an area under the Receiver Operating Characteristic curve (AUC) of 0.97, a sensitivity of 0.95, and a specificity of 0.93. Furthermore, we utilized three breast cancer cell subtypes (MCF-7, MDA-MD-468 and MDA-MB-231) and one lung cancer cell line A549 to validate the predicted results of our model, showing that the predicted top-ranked multi-drug combinations had superior anti-cancer effects to other combinations, particularly those that were widely used in clinical treatment. Our model has the potential to increase the practicality of expanding the drug combinational space and to leverage its capacity to prioritize the most effective multi-drug combinational therapy for precision oncology applications.

Systematic Pan-Cancer Analysis Identifies CDK1 as an Immunological and Prognostic Biomarker

Cyclin-dependent kinase 1 (CDK1) plays an important role in cancer development, progression, and the overall process of tumorigenesis. However, no pan-cancer analysis has been reported for CDK1, and the predictive role of CDK1 in immune checkpoint inhibitors (ICIs) therapy response remains unexplored. Thus, in this study, we first investigated the potential oncogenic role of CDK1 in 33 tumors by multidimensional bioinformatics analysis based on The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) datasets. Bioinformatic analysis and immunohistochemical experiments confirmed that CDK1 is significantly upregulated in most common cancers and is strongly associated with prognosis. Further analysis indicated that CDK1 may influence tumor immunity mainly by mediating the degree of tumor infiltration of immune-associated cells, and the effect of CDK1 on immunity is diverse across tumor types in tumor microenvironment. CDK1 was also positively correlated with tumor mutational burden (TMB) and microsatellite instability (MSI) in certain cancer types, linking its expression to the assessment of possible treatment response. The results of the pan-cancer analysis study showed that the CDK1 gene was positively associated with the expression of three classes of RNA methylation regulatory proteins, and affects RNA function through multiple mechanisms of action and plays an important role in the posttranscriptional regulation of the tumor microenvironment. These findings shed light on the role of the CDK1 gene in cancer progression and provide information to further study the CDK1 gene as a potential target for pan-cancer.

Self-carried nanodrug (SCND-SIS3): A targeted therapy for lung cancer with superior biocompatibility and immune boosting effects

Transforming growth factor β (TGF-β) is a well-known key mediator for the progression and metastasis of lung carcinoma. However, cost-effective anti-TGF-β therapeutics for lung cancer remain to be explored. Specifically, the low efficacy in drug delivery greatly limits the clinical application of small molecular inhibitors of TGF-β. In the present study, specific inhibitor of Smad3 (SIS3) is developed into a self-carried nanodrug (SCND-SIS3) using the reprecipitation method, which largely improves its solubility and bioavailability while reduces its nephrotoxicity. Compared to unmodified-SIS3, SCND-SIS3 demonstrates better anti-cancer effects through inducing tumor cell apoptosis, inhibiting angiogenesis, and boosting NK cell-mediated immune responses in syngeneic Lewis Lung Cancer (LLC) mouse model. Better still, it could achieve comparable anti-cancer effect with just one-fifth the dose of unmodified-SIS3. Mechanistically, RNA-sequencing analysis and cytokine array results unveil a TGF-β/Smad3-dependent immunoregulatory landscape in NK cells. In particular, SCND-SIS3 promotes NK cell cytotoxicity by ameliorating Smad3-mediated transcriptional inhibition of Ndrg1. Furthermore, improved NK cell cytotoxicity by SCND-SIS3 is associated with higher expression of activation receptor Nkp46, and suppressed levels of Trib3 and TSP1 as compared with unmodified-SIS3. Taken together, SCND-SIS3 possesses superior anti-cancer effects with enhanced bioavailability and biocompatibility, therefore representing as a novel therapeutic strategy for lung carcinoma with promising clinical potential.

LncRNA-p21 suppresses cell proliferation and induces apoptosis in gastric cancer by sponging miR-514b-3p and up-regulating ARHGEF9 expression

The long non-coding RNA p21 (lncRNA-p21) was a tumor suppressor gene in most cancer types including gastric cancer (GC). We aimed to identify a specific lncRNA-p21-involved pathway in regulating the proliferation and apoptosis of GC cells. A lower lncRNA-p21 expression in tumors was associated with advanced disease stage and predicted worse survival of GC patients. LncRNA-p21 overexpression in GC cell line somatic gastric cancer (SGC)-7901 and human gastric cancer (HGC)-27 suppressed cell proliferation and enhanced apoptosis, while lncRNA-p21 knockdown caused the opposite effects. Through bioinformatics analysis and luciferase-based reporter assays, we identified miR-514b-3p as a sponge target of lncRNA-p21. Cdc42 guanine nucleotide exchange factor 9 (ARHGEF9), functioned as a tumor suppress factor in GC, was found as the downstream target of miR-514-3p, and their expressions were negatively correlated in GC tumor tissues. In addition, like lncRNA-p21 overexpression alone, miR-514-3p inactivation alone also led to decreased proliferation and increased apoptosis in SGC-7901 and HGC-27 cells, which were markedly attenuated by additional ARHGEF9 knockdown. Xenograft SGC-7901 cells with more lncRNA-p21 or ARHGEF9 expressions or with less miR-514-3p expression exhibited obviously slower in vivo growth than the control SGC-7901 cells in nude mice. Our study reveals a novel lncRNA-p21/miR-514b-3p/ARHGEF9 pathway that can be targeted for GC therapy.

A Network-Guided Approach to Discover Phytochemical-Based Anticancer Therapy: Targeting MARK4 for Hepatocellular Carcinoma

MAP/microtubule affinity-regulating kinase 4 (MARK4) is associated with various biological functions, including neuronal migration, cell polarity, microtubule dynamics, apoptosis, and cell cycle regulation, specifically in the G1/S checkpoint, cell signaling, and differentiation. It plays a critical role in different types of cancers. Hepatocellular carcinoma (HCC) is the one of the most common forms of liver cancer caused due to mutations, epigenetic aberrations, and altered gene expression patterns. Here, we have applied an integrated network biology approach to see the potential links of MARK4 in HCC, and subsequently identified potential herbal drugs. This work focuses on the naturally-derived compounds from medicinal plants and their properties, making them targets for potential anti-hepatocellular treatments. We further analyzed the HCC mutated genes from the TCGA database by using cBioPortal and mapped out the MARK4 targets among the mutated list. MARK4 and Mimosin, Quercetin, and Resveratrol could potentially interact with critical cancer-associated proteins. A set of the hepatocellular carcinoma altered genes is directly the part of infection, inflammation, immune systems, and cancer pathways. Finally, we conclude that among all these drugs, Gingerol and Fisetin appear to be the highly promising drugs against MARK4-based targets, followed by Quercetin, Resveratrol, and Apigenin.

Identification of Extracellular Matrix Signatures as Novel Potential Prognostic Biomarkers in Lung Adenocarcinoma

The extracellular matrix (ECM) is vital to normal cellular function and has emerged as a key factor in cancer initiation and metastasis. However, the prognostic and oncological values of ECM organization-related genes have not been comprehensively explored in lung adenocarcinoma (LUAD) patients. In this study, we included LUAD samples from The Cancer Genome Atlas (TCGA, training set) and other three validation sets (GSE87340, GSE140343 and GSE115002), then we constructed a three-gene prognostic signature based on ECM organization-related genes. The prognostic signature involving COL4A6, FGA and FSCN1 was powerful and robust in both the training and validation datasets. We further constructed a composite prognostic nomogram to facilitate clinical practice by integrating an ECM organization-related signature with clinical characteristics, including age and TNM stage. Patients with higher risk scores were characterized by proliferation, metastasis and immune hallmarks. It is worth noting that high-risk group showed higher fibroblast infiltration in tumor tissue. Accordingly, factors (IGFBP5, CLCF1 and IL6) reported to be secreted by cancer-associated fibroblasts (CAFs) showed higher expression level in the high-risk group. Our findings highlight the prognostic value of the ECM organization signature in LUAD and provide insights into the specific clinical and molecular features underlying the ECM organization-related signature, which may be important for patient treatment.

An aldehyde dehydrogenase 1A3 inhibitor attenuates the metastasis of human colorectal cancer

Metastasis is the leading cause of death for patients with colorectal cancer (CRC). The development of therapeutic regimens that selectively inhibit the biological processes involved in CRC cell dissemination is important. We used multiple Affymetrix DNA microarray hybridization datasets to identify genes related to metastasis and have significant prognostic value for patients with CRC. Quantitative real-time PCR, immunofluorescent and immunohistochemical staining were used to evaluate mRNA and protein expression. The function of aldehyde dehydrogenase 1A3 (ALDH1A3) in invasion was assessed by performing transwell assays and animal experiments. Real-time PCR, luciferase reporter assays, and western blotting were used to identify the genes regulated by ALDH1A3. Molecular docking, MTS assays, cellular thermal shift assays, isothermal titration calorimetry, microscale thermophoresis, and enzymatic activity assays were used to screen and verify the efficacy of the ALDH1A3-specific inhibitor YD1701 (dibenzo-30-crown10-ether). Finally, subcutaneous or orthotopic xenograft models were established to investigate the therapeutic potential of YD1701. Human ALDH1A3 was identified to correlate with a metastatic phenotype in CRC cells and a poor patient prognosis. Moreover, ALDH1A3 upregulated the expression of ZEB1 and SNAI2 by inhibiting miR-200 family members. The ALDH1A3-specific inhibitor YD1701 was screened, attenuated the invasion of CRC cells in vitro, and prolonged the survival of mice bearing subcutaneous or orthotopic xenografts. Our results show that ALDH1A3 promotes invasion and metastasis via the miR-200-ZEB1/SANI2 axis and is thus a plausible marker for predicting CRC progression. Inhibiting ALDH1A3 with the identified compound YD1701 might represent an effective therapeutic approach to prevent the metastasis of CRC.

Towards targeting of shared mechanisms of cancer metastasis and therapy resistance

Resistance to therapeutic treatment and metastatic progression jointly determine a fatal outcome of cancer. Cancer metastasis and therapeutic resistance are traditionally studied as separate fields using non-overlapping strategies. However, emerging evidence, including from in vivo imaging and in vitro organotypic culture, now suggests that both programmes cooperate and reinforce each other in the invasion niche and persist upon metastatic evasion. As a consequence, cancer cell subpopulations exhibiting metastatic invasion undergo multistep reprogramming that - beyond migration signalling - supports repair programmes, anti-apoptosis processes, metabolic adaptation, stemness and survival. Shared metastasis and therapy resistance signalling are mediated by multiple mechanisms, such as engagement of integrins and other context receptors, cell-cell communication, stress responses and metabolic reprogramming, which cooperate with effects elicited by autocrine and paracrine chemokine and growth factor cues present in the activated tumour microenvironment. These signals empower metastatic cells to cope with therapeutic assault and survive. Identifying nodes shared in metastasis and therapy resistance signalling networks should offer new opportunities to improve anticancer therapy beyond current strategies, to eliminate both nodular lesions and cells in metastatic transit.

Novel omics technology driving translational research in precision oncology

In this review, we summarize the current challenges faced by cancer researchers and motivate the use of novel genomics solutions. We follow this up with a comprehensive overview of three recent genomics technologies: liquid biopsy, single-cell RNA sequencing and spatial transcriptomics. We discuss a few representative protocols/assays for each technology along with their strengths, weaknesses, optimal use-cases, and their current stage of clinical deployment by summarizing trial data. We focus on how these technologies help us develop a better understanding of cancer as a rapidly evolving heterogeneous genetic disease that modulates its immediate microenvironment leading to systemic macro-level changes in the patient body. We summarize the review with a flowchart that integrates these three technologies in the existing workflows of clinicians and researchers toward robust detection, accurate diagnosis, and precision oncology.

Quantitative analysis of tumour spheroid structure

Tumour spheroids are common in vitro experimental models of avascular tumour growth. Compared with traditional two-dimensional culture, tumour spheroids more closely mimic the avascular tumour microenvironment where spatial differences in nutrient availability strongly influence growth. We show that spheroids initiated using significantly different numbers of cells grow to similar limiting sizes, suggesting that avascular tumours have a limiting structure; in agreement with untested predictions of classical mathematical models of tumour spheroids. We develop a novel mathematical and statistical framework to study the structure of tumour spheroids seeded from cells transduced with fluorescent cell cycle indicators, enabling us to discriminate between arrested and cycling cells and identify an arrested region. Our analysis shows that transient spheroid structure is independent of initial spheroid size, and the limiting structure can be independent of seeding density. Standard experimental protocols compare spheroid size as a function of time; however, our analysis suggests that comparing spheroid structure as a function of overall size produces results that are relatively insensitive to variability in spheroid size. Our experimental observations are made using two melanoma cell lines, but our modelling framework applies across a wide range of spheroid culture conditions and cell lines.

Lamellipodin-RICTOR Signaling Mediates Glioblastoma Cell Invasion and Radiosensitivity Downstream of EGFR

Glioblastoma is a tumor type of unmet need despite the development of multimodal treatment strategies. The main factors contributing to the poor prognosis of glioblastoma patients are diverse genetic and epigenetic changes driving glioblastoma persistence and recurrence. Complemented are these factors by extracellular cues mediated through cell surface receptors, which further aid in fostering pro-invasion and pro-survival signaling contributing to glioblastoma therapy resistance. The underlying mechanisms conferring this therapy resistance are poorly understood. Here, we show that the cytoskeleton regulator Lamellipodin (Lpd) mediates invasiveness, proliferation and radiosensitivity of glioblastoma cells. Phosphoproteome analysis identified the epidermal growth factor receptor (EGFR) signaling axis commonly hyperactive in glioblastoma to depend on Lpd. Mechanistically, EGFR signaling together with an interaction between Lpd and the Rapamycin-insensitive companion of mammalian target of rapamycin (RICTOR) jointly regulate glioblastoma radiosensitivity. Collectively, our findings demonstrate an essential function of Lpd in the radiation response and invasiveness of glioblastoma cells. Thus, we uncover a novel Lpd-driven resistance mechanism, which adds an additional critical facet to the complex glioblastoma resistance network.

Identification of a Putative Enhancer RNA for EGFR in Hyper-Accessible Regions in Esophageal Squamous Cell Carcinoma Cells by Analysis of Chromatin Accessibility Landscapes

Abnormal genetic and epigenetic modifications play a key role in esophageal cancer. By Assay for Transposase-Accessible Chromatin by sequencing (ATAC-seq), this study compared chromatin accessibility landscapes among two esophageal squamous cell carcinoma (ESCC) cell lines, KYSE-30 and KYSE-150, and a non-cancerous esophageal epithelial cell line, HET-1A. Data showed that hyper-accessible regions in ESCC cells contained genes related with cancer hallmarks, such as epidermal growth factor receptor (EGFR). Multi-omics analysis and digital-droplet PCR results demonstrated that several non-coding RNAs in EGFR upstream were upregulated in ESCC cells. Among them, one appeared to act as an enhancer RNA responsible for EGFR overexpression. Further motif analysis and pharmacological data suggested that AP-1 family transcription factors were able to bind the hyper-accessible regions and thus to regulate cancer cell proliferation and migration. This study discovered a putative enhancer RNA for EGFR gene and the reliance of ESCC on AP-1 transcription factor.

Radioresistance and Transcriptional Reprograming of Invasive Glioblastoma Cells

PURPOSE

Infiltrative growth pattern is a hallmark of glioblastoma (GBM). Radiation therapy aims to eradicate microscopic residual GBM cells after surgical removal of the visible tumor bulk. However, in-field recurrences remain the major pattern of therapy failure. We hypothesized that the radiosensitivity of peripheral invasive tumor cells (peri) may differ from the predominantly investigated tumor bulk.

METHODS AND MATERIALS

Invasive GBM populations were generated via debulking of the visible tumor core and serial orthotopic transplantation of peri cells, and sustained proinvasive phenotype of peri cells was confirmed in vitro by scratch assay and time lapse imaging. In parallel, invasive GBM cells were selected by transwell assay and from peri cells of patient-derived 3-dimensional spheroid cultures. Transcriptome analysis deciphered a GBM invasion-associated gene signature, and functional involvement of key pathways was validated by pharmacologic inhibition.

RESULTS

Compared with the bulk cells, invasive GBM populations acquired a radioresistant phenotype characterized by increased cell survival, reduced cell apoptosis, and enhanced DNA double-strand break repair proficiency. Transcriptome analysis revealed a reprograming of invasive cells toward augmented activation of epidermal growth factor receptor- and nuclear factor-κB-related pathways, whereas metabolic processes were downregulated. An invasive GBM score derived from this transcriptional fingerprint correlated well with patient outcome. Inhibition of epidermal growth factor receptor and nuclear factor-κB signaling resensitized invasive cells to irradiation. Invasive cells were eradicated with similar efficacy by particle therapy with carbon ions.

CONCLUSIONS

Our data indicate that invasive tumor cells constitute a phenotypically distinct and highly radioresistant GBM subpopulation with prognostic impact that may be vulnerable to targeted therapy and carbon ions.

Fibroageing: An ageing pathological feature driven by dysregulated extracellular matrix-cell mechanobiology

Ageing is a multifactorial biological process leading to a progressive decline of physiological functions. The process of ageing includes numerous changes in the cells and the interactions between cell-cell and cell-microenvironment remaining as a critical risk factor for the development of chronic degenerative diseases. Systemic inflammation, known as inflammageing, increases as a consequence of ageing contributing to age-related morbidities. But also, persistent and uncontrolled activation of fibrotic pathways, with excessive accumulation of extracellular matrix (ECM) and organ dysfunction is markedly more frequent in the elderly. In this context, we introduce here the concept of Fibroageing, that is, the propensity to develop tissue fibrosis associated with ageing, and propose that ECM is a key player underlying this process. During ageing, molecules of the ECM become damaged through many modifications including glycation, crosslinking, and accumulation, leading to matrix stiffness which intensifies ageing-associated alterations. We provide a framework with some mechanistic hypotheses proposing that stiff ECM, in addition to the well-known activation of fibrotic positive feedback loops, affect several of the hallmarks of ageing, such as cell senescence and mitochondrial dysfunction, and in this context, is a key mechanism and a driver thread of Fibroageing.

Syntaphilin downregulation facilitates radioresistance via mediating mitochondria distribution in esophageal squamous cell carcinoma

Syntaphilin (SNPH) halts mitochondrial movements and regulates proliferation-motility phenotype switching of cancer cells. We sought to investigate the significance of SNPH-mediated mitochondria distribution in radioresistant (RR) phenotype switching in esophageal squamous cell carcinoma (ESCC). RR ESCC cells were established by long-term exposure to radiation. Effects of SNPH on proliferation, migration, mitochondrial distribution, radiation-induced oxidative damage and radiosensitivity were investigated by overexpressing or silencing SNPH. The mechanisms regulating SNPH expression and the potential molecules mediating the SNPH-re-expression-induced radiosensitization were explored. SNPH expression in specimens from 156 patients was analyzed to evaluate its clinical significance. We found that RR ESCC cells had a sparse mitochondrial network and lower SNPH level. SNPH reconstitution in RR ESCC cells inhibited migration, induced proliferation and mitochondrial aggregation, exacerbated the radiation-induced oxidative damage and ultimately promoted radiosensitization. Mechanistically, ubiquitin-proteasomal degradation and histone modification contributed to SNPH downregulation in RR ESCC cells. Subsequently, we found that CREB dephosphorylation facilitated the SNPH re-expression-induced radiosensitization. Furthermore, SNPH expression was correlated with the radiotherapeutic efficacy and served as an independent prognostic factor for survival of ESCC patients. Our study revealed that low SNPH expression was a novel indicator for radioresistance, and targeting SNPH could be a promising regimen to improve the radiotherapeutic efficiency in ESCC patients.

GBP5 drives malignancy of glioblastoma via the Src/ERK1/2/MMP3 pathway

Guanylate binding proteins (GBPs), a family of interferon-inducible large GTPase, play a pivotal role in cell-autonomous immunity and tumor malignant transformation. Glioblastoma (GBM) is the most prevalent and lethal primary brain tumor in adults. Here we show that GBP5 was highly expressed in GBM cell lines and in clinical samples, especially in the mesenchymal subtype. The expression levels of GBP5 were negatively correlated with the prognosis of GBM patients. Overexpression of GBP5 promoted the proliferation, migration, and invasion of GBM cells in vitro and in vivo. In contrast, silencing GBP5 by RNA interference exhibited the opposite effects. Consequently, targeting GBP5 in GBM cells resulted in impaired tumor growth and prolonged survival time of mice with GBM tumors. We further identified that the Src/ERK1/2/MMP3 axis was essential for GBP5-promoted GBM aggressiveness. These findings suggest that GBP5 may represent a novel target for GBM intervention.

Hold on or Cut? Integrin- and MMP-Mediated Cell-Matrix Interactions in the Tumor Microenvironment

The tumor microenvironment (TME) has become the focus of interest in cancer research and treatment. It includes the extracellular matrix (ECM) and ECM-modifying enzymes that are secreted by cancer and neighboring cells. The ECM serves both to anchor the tumor cells embedded in it and as a means of communication between the various cellular and non-cellular components of the TME. The cells of the TME modify their surrounding cancer-characteristic ECM. This in turn provides feedback to them via cellular receptors, thereby regulating, together with cytokines and exosomes, differentiation processes as well as tumor progression and spread. Matrix remodeling is accomplished by altering the repertoire of ECM components and by biophysical changes in stiffness and tension caused by ECM-crosslinking and ECM-degrading enzymes, in particular matrix metalloproteinases (MMPs). These can degrade ECM barriers or, by partial proteolysis, release soluble ECM fragments called matrikines, which influence cells inside and outside the TME. This review examines the changes in the ECM of the TME and the interaction between cells and the ECM, with a particular focus on MMPs.

Resistance Mechanisms of Anti-angiogenic Therapy and Exosomes-Mediated Revascularization in Cancer

Anti-angiogenic therapies (AATs) have been widely used for cancer treatment. But the beneficial effects of AATs are short, because AAT-induced tumor revascularization facilitates the tumor relapse. In this mini-review, we described different forms of tumor neovascularization and revascularization including sprouting angiogenesis, vessel co-option, intussusceptive angiogenesis, and vasculogenic mimicry, all of which are closely mediated by vascular endothelial growth factor (VEGF), angiopoietins, matrix metalloproteinases, and exosomes. We also summarized the current findings for the resistance mechanisms of AATs including enhancement in pro-angiogenic cytokines, heterogeneity in tumor-associated endothelial cells (ECs), crosstalk between tumor cells and ECs, masking of extracellular vesicles, matrix stiffness and contributions from fibroblasts, macrophages and adipocytes in the tumor microenvironment. We highlighted the revascularization following AATs, particularly the role of exosome stimulating factors such as hypoxia and miRNA, and that of exosomal cargos such as cytokines, miRNAs, lncRNAs, and circRNAs from the tumor ECs in angiogenesis and revascularization. Finally, we proposed that renormalization of tumor ECs would be a more efficient cancer therapy than the current AATs.

Glycogen synthase kinase-3β participates in acquired resistance to gemcitabine in pancreatic cancer

Acquisition of resistance to gemcitabine is a challenging clinical and biological hallmark property of refractory pancreatic cancer. Here, we investigated whether glycogen synthase kinase (GSK)-3β, an emerging therapeutic target in various cancer types, is mechanistically involved in acquired resistance to gemcitabine in human pancreatic cancer. This study included 3 gemcitabine-sensitive BxPC-3 cell-derived clones (BxG30, BxG140, BxG400) that acquired stepwise resistance to gemcitabine and overexpressed ribonucleotide reductase (RR)M1. Treatment with GSK3β-specific inhibitor alone attenuated the viability and proliferation of the gemcitabine-resistant clones, while synergistically enhancing the efficacy of gemcitabine against these clones and their xenograft tumors in rodents. The gemcitabine-resensitizing effect of GSK3β inhibition was associated with decreased expression of RRM1, reduced phosphorylation of Rb protein, and restored binding of Rb to the E2 transcription factor (E2F)1. This was followed by decreased E2F1 transcriptional activity, which ultimately suppressed the expression of E2F1 transcriptional targets including RRM1, CCND1 encoding cyclin D1, thymidylate synthase, and thymidine kinase 1. These results suggested that GSK3β participates in the acquisition of gemcitabine resistance by pancreatic cancer cells via impairment of the functional interaction between Rb tumor suppressor protein and E2F1 pro-oncogenic transcription factor, thereby highlighting GSK3β as a promising target in refractory pancreatic cancer. By providing insight into the molecular mechanism of gemcitabine resistance, this study identified a potentially novel strategy for pancreatic cancer chemotherapy.

Adjuvant effect of low-carbohydrate diet on outcomes of patients with recurrent glioblastoma under intranasal perillyl alcohol therapy

BACKGROUND

Standard of care for glioblastoma (GB), consisting of cytotoxic chemotherapy, steroids, and high-dose radiation, induces changes in the tumor microenvironment through its effects on glucose availability, which is a determinant for tumor progression (TP). Low-carbohydrate diet (LCD) reduces the glucose levels needed to drive the Warburg effect.

METHODS

To investigate LCD's effect on GB therapy, we have begun a clinical trial using LCD as an addition to intranasal perillyl alcohol (POH) for recurrent GB (rGB) patients. This study involved 29 individuals and evaluated, over a period of 1 year, the adjuvant effect of LCD associated with POH therapy in terms of toxicity, extent of peritumoral edema, reduced corticosteroid use, seizure frequency, and overall survival. POH group (n = 14) received solely intranasal POH without specific diet regimen, whereas POH/LCD group (n = 15) received intranasal POH in combination with nutritional intervention. Patients' assessment was based on clinical reviews and magnetic resonance data.

RESULTS

In the 1-year follow-up, the POH/LCD group showed a 4.4-fold decrease in the proportion of patients who needed treatment with corticosteroids, as well as a reduction in tumor size and peritumoral edema, as compared to the POH group. While 75% of patients undergoing POH treatment experienced seizures, this fraction was reduced to 56% in the POH/LCD group. A 2.07-fold increase in the proportion of patients with stable disease, along with a 2.8-fold decrease in the proportion of patients with TP, was seen in the POH/LCD group.

CONCLUSION

The results presented in this study show that the LCD associated with intranasal POH therapy may represent a viable option as adjunctive therapy for rGB to improve survival without compromising patients' quality of life. Prospective cohort studies are needed to confirm these findings and validate the efficacy of this novel therapeutic strategy.

Intrinsic and Extrinsic Modulators of the Epithelial to Mesenchymal Transition: Driving the Fate of Tumor Microenvironment

The epithelial to mesenchymal transition (EMT) is an evolutionarily conserved process. In cancer, EMT can activate biochemical changes in tumor cells that enable the destruction of the cellular polarity, leading to the acquisition of invasive capabilities. EMT regulation can be triggered by intrinsic and extrinsic signaling, allowing the tumor to adapt to the microenvironment demand in the different stages of tumor progression. In concomitance, tumor cells undergoing EMT actively interact with the surrounding tumor microenvironment (TME) constituted by cell components and extracellular matrix as well as cell secretome elements. As a result, the TME is in turn modulated by the EMT process toward an aggressive behavior. The current review presents the intrinsic and extrinsic modulators of EMT and their relationship with the TME, focusing on the non-cell-derived components, such as secreted metabolites, extracellular matrix, as well as extracellular vesicles. Moreover, we explore how these modulators can be suitable targets for anticancer therapy and personalized medicine.

Prostaglandins regulate invasive, collective border cell migration

While prostaglandins (PGs), short-range lipid signals, regulate single cell migration, their roles in collective migration remain unclear. To address this, we use Drosophila border cell migration, an invasive, collective migration that occurs during Stage 9 of oogenesis. Pxt is the Drosophila cyclooxygenase-like enzyme responsible for PG synthesis. Loss of Pxt results in both delayed border cell migration and elongated clusters, whereas somatic Pxt knockdown causes delayed migration and compacted clusters. These findings suggest PGs act in both the border cells and nurse cells, the substrate on which the border cells migrate. As PGs regulate the actin bundler Fascin, and Fascin is required for on-time migration, we assessed whether PGs regulate Fascin to promote border cell migration. Coreduction of Pxt and Fascin results in delayed migration and elongated clusters. The latter may be due to altered cell adhesion, as loss of Pxt or Fascin, or coreduction of both, decreases integrin levels on the border cell membranes. Conversely, integrin localization is unaffected by somatic knockdown of Pxt. Together these data lead to the model that PG signaling controls Fascin in the border cells to promote migration and in the nurse cells to maintain cluster cohesion.

Naringenin Sensitizes Resistant C6 Glioma Cells with a Repressive Impact on the Migrating Ability

Background:

Glioma, the most common form of a malignant brain tumour is characterised by a poor prognosis, which is attributable to its resistance against current therapeutic approaches. Temozolomide (TMZ), a DNA alkylating agent, is the first-line drug for glioma treatment. Long-term treatment using TMZ was reported to culminate in the development of resistance with overexpression of multidrug resistance 1 gene coded protein P-glycoprotein, which in turn releases the drugs from the tumour cells.

Purpose:

Thus, to circumvent such resistance issues, the current study attempted to explore the effect of naringenin (a flavanone) with proven antiglial tumour potential, in mitigating the features of TMZ resistance.

Methods:

Colony-forming assay, invasion assay and scratch wound assay were performed among the groups, namely tumour control (C6), vehicle control (V), naringenin (NGEN)-treated, drug-resistant tumour cells (C6R), and drug resistance cells added with NGEN (C6R+NGEN), to examine the impact of NGEN on migration and invasion. The effect of NGEN on filopodia length and density during cell migration was also studied in addition to the matrix metalloproteinases (MMP-2 and MMP-9) and p-ERK levels.

Results and Conclusion:

NGEN and C6R+NGEN groups had shown significant reduction (P < .01) in length and density of filopodia, colony formation, invasion and wound healing. Further, NGEN could also modify the assessed protein levels (P < .001), which were involved in migration and invasion in sensitive and resistant cells. Our study had provided the first evidence on NGEN-induced enhanced sensitivity against TMZ resistance with profound influence as an antimigratory and anti-invasive agent.

RIP1 Is a Novel Component of γ-ionizing Radiation-Induced Invasion of Non-Small Cell Lung Cancer Cells

Abstract: Previously, we demonstrated that γ-ionizing radiation (IR) triggers the invasion/migration of A549 cells via activation of an EGFR-p38/ERK-STAT3/CREB-1-EMT pathway. Here, we have demonstrated the involvement of a novel intracellular signaling mechanism in γ-ionizing radiation (IR)-induced migration/invasion. Expression of receptor-interacting protein (RIP) 1 was initially increased upon exposure of A549, a non-small cell lung cancer (NSCLC) cell line, to IR. IR-induced RIP1 is located downstream of EGFR and involved in the expression/activity of matrix metalloproteases (MMP-2 and MMP-9) and vimentin, suggesting a role in epithelial-mesenchymal transition (EMT). Our experiments showed that IR-induced RIP1 sequentially induces Src-STAT3-EMT to promote invasion/migration. Inhibition of RIP1 kinase activity and expression blocked induction of EMT by IR and suppressed the levels and activities of MMP-2, MMP-9 and vimentin. IR-induced RIP1 activation was additionally associated with stimulation of the transcriptional factor NF-κB. Specifically, exposure to IR triggered NF-κB activation and inhibition of NF-κB suppressed IR-induced RIP1 expression, followed by a decrease in invasion/migration as well as EMT. Based on the collective results, we propose that IR concomitantly activates EGFR and NF-κB and subsequently triggers the RIP1-Src/STAT3-EMT pathway, ultimately promoting metastasis.

Glycogen Synthase Kinase 3β in Cancer Biology and Treatment

Glycogen synthase kinase (GSK)3β is a multifunctional serine/threonine protein kinase with more than 100 substrates and interacting molecules. GSK3β is normally active in cells and negative regulation of GSK3β activity via phosphorylation of its serine 9 residue is required for most normal cells to maintain homeostasis. Aberrant expression and activity of GSK3β contributes to the pathogenesis and progression of common recalcitrant diseases such as glucose intolerance, neurodegenerative disorders and cancer. Despite recognized roles against several proto-oncoproteins and mediators of the epithelial–mesenchymal transition, deregulated GSK3β also participates in tumor cell survival, evasion of apoptosis, proliferation and invasion, as well as sustaining cancer stemness and inducing therapy resistance. A therapeutic effect from GSK3β inhibition has been demonstrated in 25 different cancer types. Moreover, there is increasing evidence that GSK3β inhibition protects normal cells and tissues from the harmful effects associated with conventional cancer therapies. Here, we review the evidence supporting aberrant GSK3β as a hallmark property of cancer and highlight the beneficial effects of GSK3β inhibition on normal cells and tissues during cancer therapy. The biological rationale for targeting GSK3β in the treatment of cancer is also discussed at length.

Tunneling Nanotubes and Tumor Microtubes in Cancer

Intercellular communication among cancer cells and their microenvironment is crucial to disease progression. The mechanisms by which communication occurs between distant cells in a tumor matrix remain poorly understood. In the last two decades, experimental evidence from different groups proved the existence of thin membranous tubes that interconnect cells, named tunneling nanotubes, tumor microtubes, cytonemes or membrane bridges. These highly dynamic membrane protrusions are conduits for direct cell-to-cell communication, particularly for intercellular signaling and transport of cellular cargo over long distances. Tunneling nanotubes and tumor microtubes may play an important role in the pathogenesis of cancer. They may contribute to the resistance of tumor cells against treatments such as surgery, radio- and chemotherapy. In this review, we present the current knowledge about the structure and function of tunneling nanotubes and tumor microtubes in cancer and discuss the therapeutic potential of membrane tubes in cancer treatment.

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.

Alleviation of Multidrug Resistance by Flavonoid and Non-Flavonoid Compounds in Breast, Lung, Colorectal and Prostate Cancer

The aim of the manuscript is to discuss the influence of plant polyphenols in overcoming multidrug resistance in four types of solid cancers (breast, colorectal, lung and prostate cancer). Effective treatment requires the use of multiple toxic chemotherapeutic drugs with different properties and targets. However, a major cause of cancer treatment failure and metastasis is the development of multidrug resistance. Potential mechanisms of multidrug resistance include increase of drug efflux, drug inactivation, detoxification mechanisms, modification of drug target, inhibition of cell death, involvement of cancer stem cells, dysregulation of miRNAs activity, epigenetic variations, imbalance of DNA damage/repair processes, tumor heterogeneity, tumor microenvironment, epithelial to mesenchymal transition and modulation of reactive oxygen species. Taking into consideration that synthetic multidrug resistance agents have failed to demonstrate significant survival benefits in patients with different types of cancer, recent research have focused on beneficial effects of natural compounds. Several phenolic compounds (flavones, phenolcarboxylic acids, ellagitannins, stilbens, lignans, curcumin, etc.) act as chemopreventive agents due to their antioxidant capacity, inhibition of proliferation, survival, angiogenesis, and metastasis, modulation of immune and inflammatory responses or inactivation of pro-carcinogens. Moreover, preclinical and clinical studies revealed that these compounds prevent multidrug resistance in cancer by modulating different pathways. Additional research is needed regarding the role of phenolic compounds in the prevention of multidrug resistance in different types of cancer.

Collective cancer invasion forms an integrin-dependent radioresistant niche

Cancer fatalities result from metastatic dissemination and therapy resistance, both processes that depend on signals from the tumor microenvironment. To identify how invasion and resistance programs cooperate, we used intravital microscopy of orthotopic sarcoma and melanoma xenografts. We demonstrate that these tumors invade collectively and that, specifically, cells within the invasion zone acquire increased resistance to radiotherapy, rapidly normalize DNA damage, and preferentially survive. Using a candidate-based approach to identify effectors of invasion-associated resistance, we targeted β1 and αVβ3/β5 integrins, essential extracellular matrix receptors in mesenchymal tumors, which mediate cancer progression and resistance. Combining radiotherapy with β1 or αV integrin monotargeting in invading tumors led to relapse and metastasis in 40-60% of the cohort, in line with recently failed clinical trials individually targeting integrins. However, when combined, anti-β1/αV integrin dual targeting achieved relapse-free radiosensitization and prevented metastatic escape. Collectively, invading cancer cells thus withstand radiotherapy and DNA damage by β1/αVβ3/β5 integrin cross-talk, but efficient radiosensitization can be achieved by multiple integrin targeting.

Biomechanical modeling of invasive breast carcinoma under a dynamic change in cell phenotype: collective migration of large groups of cells

According to recent studies, cancer is an evolving complex ecosystem. It means that tumor cells are well differentiated and involved in heterotypic interactions with their microenvironment competing for available resources to proliferate and survive. In this paper, we propose a chemo-mechanical model for the growth of specific subtypes of an invasive breast carcinoma. The model suggests that a carcinoma is a heterogeneous entity comprising cells of different phenotypes, which perform different functions in a tumor. Every cell is represented by an elastic polygon changing its form and size under pressure from the tissue. The mechanical model is based on the elastic potential energy of the tissue including the effects of contractile forces within the cell perimeter and the elastic resistance to stretching or compressing the cell with respect to the reference area. A tissue can evolve via mechanisms of cell division and intercalation. The phenotype of each cell is determined by its environment and can dynamically change via an epithelial-mesenchymal transition and vice versa. The phenotype defines the cell adhesion to the adjacent tissue and the ability to divide. In this part, we focus on the forms of collective migration of large groups of cells. Numerical simulations show the different architectural subtypes of invasive carcinoma. For each communication, we examine the dynamics of the cell population and evaluate the complexity of the pattern in terms of the synergistic paradigm. The patterns are compared with the morphological structures previously identified in clinical studies.

Epigenetic inhibition of the tumor suppressor ARHI by light at night-induced circadian melatonin disruption mediates STAT3-driven paclitaxel resistance in breast cancer

Disruption of circadian time structure and suppression of circadian nocturnal melatonin (MLT) production by exposure to dim light at night (dLAN), as occurs with night shift work and/or disturbed sleep-wake cycles, is associated with a significantly increased risk of breast cancer and resistance to tamoxifen and doxorubicin. Melatonin inhibition of human breast cancer chemoresistance involves mechanisms including suppression of tumor metabolism and inhibition of kinases and transcription factors which are often activated in drug-resistant breast cancer. Signal transducer and activator of transcription 3 (STAT3), frequently overexpressed and activated in paclitaxel (PTX)-resistant breast cancer, promotes the expression of DNA methyltransferase one (DNMT1) to epigenetically suppress the transcription of tumor suppressor Aplasia Ras homolog one (ARHI) which can sequester STAT3 in the cytoplasm to block PTX resistance. We demonstrate that breast tumor xenografts in rats exposed to dLAN and circadian MLT disrupted express elevated levels of phosphorylated and acetylated STAT3, increased DNMT1, but reduced sirtuin 1 (SIRT1) and ARHI. Furthermore, MLT and/or SIRT1 administration blocked/reversed interleukin 6 (IL-6)-induced acetylation of STAT3 and its methylation of ARH1 to increase ARH1 mRNA expression in MCF-7 breast cancer cells. Finally, analyses of the I-SPY 1 trial demonstrate that elevated MT₁ receptor expression is significantly correlated with pathologic complete response following neo-adjuvant therapy in breast cancer patients. This is the first study to demonstrate circadian disruption of MLT by dLAN driving intrinsic resistance to PTX via epigenetic mechanisms increasing STAT3 expression and that MLT administration can reestablish sensitivity of breast tumors to PTX and drive tumor regression.

The extracellular matrix in tumor progression and metastasis

The extracellular matrix (ECM) constitutes the scaffold of tissues and organs. It is a complex network of extracellular proteins, proteoglycans and glycoproteins, which form supramolecular aggregates, such as fibrils and sheet-like networks. In addition to its biochemical composition, including the covalent intermolecular cross-linkages, the ECM is also characterized by its biophysical parameters, such as topography, molecular density, stiffness/rigidity and tension. Taking these biochemical and biophysical parameters into consideration, the ECM is very versatile and undergoes constant remodeling. This review focusses on this remodeling of the ECM under the influence of a primary solid tumor mass. Within this tumor stroma, not only the cancer cells but also the resident fibroblasts, which differentiate into cancer-associated fibroblasts (CAFs), modify the ECM. Growth factors and chemokines, which are tethered to and released from the ECM, as well as metabolic changes of the cells within the tumor bulk, add to the tumor-supporting tumor microenvironment. Metastasizing cancer cells from a primary tumor mass infiltrate into the ECM, which variably may facilitate cancer cell migration or act as barrier, which has to be proteolytically breached by the infiltrating tumor cell. The biochemical and biophysical properties therefore determine the rates and routes of metastatic dissemination. Moreover, primed by soluble factors of the primary tumor, the ECM of distant organs may be remodeled in a way to facilitate the engraftment of metastasizing cancer cells. Such premetastatic niches are responsible for the organotropic preference of certain cancer entities to colonize at certain sites in distant organs and to establish a metastasis. Translational application of our knowledge about the cancer-primed ECM is sparse with respect to therapeutic approaches, whereas tumor-induced ECM alterations such as increased tissue stiffness and desmoplasia, as well as breaching the basement membrane are hallmark of malignancy and diagnostically and histologically harnessed.

Immune targets in the tumor microenvironment treated by radiotherapy

Radiotherapy (RT), the major anti-cancer modality for more than half of cancer patients after diagnosis, has the advantage of local tumor control with relatively less systematic side effects comparing to chemotherapy. However, the efficacy of RT is limited by acquired tumor resistance leading to the risks of relapse and metastasis. To further enhance the efficacy of RT, with the renaissances of targeted immunotherapy (TIT), increasing interests are raised on RT combined with TIT including cancer vaccines, T-cell therapy, and antibody-based immune checkpoint blockers (ICB) such as anti-CTLA-4 and anti-PD1/PD-L1. In achieving a significant synergy between RT and TIT, the dynamics of radiation-induced response in tumor cells and stromal cells, especially the cross-talk between tumor cells and immune cells in the irradiated tumor microenvironment (ITME) as highlighted in recent literature are to be elucidated. The abscopal effect refereeing the RT-induced priming function outside of ITME could be compromised by the immune-suppressive factors such as CD47 and PD-L1 on tumor cells and Treg induced or enhanced in the ITME. Cell surface receptors temporally or permanently induced and bioactive elements released from dead cells could serve antigenic source (radiation-associated antigenic proteins, RAAPs) to the host and have functions in immune regulation on the tumor. This review is attempted to summarize a cluster of factors that are inducible by radiation and targetable by antibodies, or have potential to be immune regulators to synergize tumor control with RT. Further characterization of immune regulators in ITME will deepen our understanding of the interplay among immune regulators in ITME and discover new effective targets for the combined modality with RT and TIT.

Fenofibrate Augments the Sensitivity of Drug-Resistant Prostate Cancer Cells to Docetaxel

Metronomic agents reduce the effective doses and adverse effects of cytostatics in cancer chemotherapy. Therefore, they can enhance the treatment efficiency of drug-resistant cancers. Cytostatic and anti-angiogenic effects of fenofibrate (FF) suggest that it can be used for the metronomic chemotherapy of drug-resistant prostate tumors. To estimate the effect of FF on the drug-resistance of prostate cancer cells, we compared the reactions of naïve and drug-resistant cells to the combined treatment with docetaxel (DCX)/mitoxantrone (MTX) and FF. FF sensitized drug-resistant DU145 and PC3 cells to DCX and MTX, as illustrated by their reduced viability and invasive potential observed in the presence of DCX/MTX and FF. The synergy of the cytostatic activities of both agents was accompanied by the inactivation of P-gp-dependent efflux, dysfunction of the microtubular system, and induction of polyploidy in DCX-resistant cells. Chemical inhibition of PPARα- and reactive oxygen species (ROS)-dependent pathways by GW6471 and N-acetyl-L-cysteine, respectively, had no effect on cell sensitivity to combined DCX/FF treatment. Instead, we observed the signs of adenosine triphosphate (ATP) deficit and autophagy in DCX/FF-treated drug-resistant cells. Furthermore, the cells that had been permanently propagated under DCX- and DCX/FF-induced stress did not acquire DCX/FF-resistance. Instead, relatively slow proliferation of DCX-resistant cells was efficiently inhibited by FF. Collectively, our observations show that FF reduces the effective doses of DCX by interfering with the drug resistance and energy metabolism of prostate cancer cells. Concomitantly, it impairs the chemotherapy-induced microevolution and expansion of DCX/FF-resistant cells. Therefore, FF can be applied as a metronomic agent to enhance the efficiency of palliative chemotherapy of prostate cancer.

Docosahexaenoic acid promotes cell cycle arrest and decreases proliferation through WNT/β-catenin modulation in colorectal cancer cells exposed to γ-radiation

The effects of radiation are known to be potentiated by N-3 polyunsaturated fatty acids, which modulate several signaling pathways, but the molecular mechanisms through which these fatty acids enhance the anticancer effects of irradiation in colorectal cancer (CRC) treatment remain poorly elucidated. Here, we aimed to ascertain whether the fatty acid docosahexaenoic acid (DHA) exerts a modulating effect on the response elicited by radiation treatment (RT). Two CRC cell lines, Caco-2 and HT-29, were exposed to RT, DHA, or both (DHA + RT) for various times, and then cell viability, proliferation, and clonogenicity were assessed. Moreover, cell cycle, apoptosis, and necrosis were analyzed using flow cytometry, and the involvement of WNT/β-catenin signaling was investigated by immunofluorescence to determine nuclear β-catenin, GSK3β phosphorylation status, and TCF/LEF-activity reporter. DHA and RT applied separately diminished the viability of both HT-29 and Caco-2 cells, and DHA + RT caused a further reduction in proliferation mainly in HT-29 cells, particularly in terms of colony formation. Concomitantly, our results verified cell cycle arrest in G0/G1 phase, a reduction of cyclin D1 expression, and a decrease in GSK3β phosphorylation after the combined treatment. Furthermore, immunofluorescence quantification revealed that nuclear β-catenin was increased in RT-exposed cells, but this effect was abrogated in cells exposed to DHA + RT, and the results of TCF/LEF-activity assays confirmed that DHA attenuated the increase in nuclear β-catenin activity induced by irradiation. Our finding shows that DHA applied in combination with RT enhanced the antitumor effects of irradiation on CRC cells, and that the underlying mechanism involved the WNT/β-catenin pathway. © 2018 BioFactors, 45(1):24-34, 2019.

Cancer invasion into musculature: Mechanics, molecules and implications

Tumor invasion along structural interphases of surrounding tumor-free tissue represents a key process during tumor progression. Much attention has been devoted to mechanisms of tumor cell migration within extracellular matrix (ECM)-rich connective tissue, however a comprehensive understanding of tumor invasion into tissue of higher structural complexity, such as muscle tissue, is lacking. Muscle invasion in cancer patients is often associated with destructive growth and worsened prognosis. Here, we review biochemical, geometrical and mechanical cues of smooth and skeletal muscle tissues and their relevance for guided invasion of cancer cells. As integrating concept, muscle-organizing ECM-rich surfaces of the epi-, peri- and endomysium provide cleft-like confined spaces along interfaces between dynamic muscle cells, which provide molecular and physical cues that guide migrating cancer cells, forming a possible contribution to cancer progression.

Arf6-driven cell invasion is intrinsically linked to TRAK1-mediated mitochondrial anterograde trafficking to avoid oxidative catastrophe

Mitochondria dynamically alter their subcellular localization during cell movement, although the underlying mechanisms remain largely elusive. The small GTPase Arf6 and its signaling pathway involving AMAP1 promote cell invasion via integrin recycling. Here we show that the Arf6–AMAP1 pathway promote the anterograde trafficking of mitochondria. Blocking the Arf6-based pathway causes mitochondrial aggregation near the microtubule-organizing center, and subsequently induces detrimental reactive oxygen species (ROS) production, likely via a mitochondrial ROS-induced ROS release-like mechanism. The Arf6-based pathway promotes the localization of ILK to focal adhesions to block RhoT1–TRAK2 association, which controls mitochondrial retrograde trafficking. Blockade of the RhoT1–TRAK1 machinery, rather than RhoT1–TRAK2, impairs cell invasion, but not two-dimensional random cell migration. Weakly or non-invasive cells do not notably express TRAK proteins, whereas they clearly express their mRNAs. Our results identified a novel association between cell movement and mitochondrial dynamics, which is specific to invasion and is necessary for avoiding detrimental ROS production.

Mitochondria subcellular localization is dynamically regulated during migration. Here, the authors show that Arf6–AMAP1 dependent ILK localization at focal adhesions reduces mitochondrial retrograde trafficking in migratory cells and prevents mitochondrial aggregation and detrimental ROS production.

Novel proteins that regulate cell extension formation in fibroblasts

Cell extensions are critical structures that enable matrix remodeling in wound healing and cancer invasion but the regulation of their formation is not well-defined. We searched for new proteins that mediated cell extension formation over collagen by tandem mass tagged mass spectrometry analysis of purified extensions in 3T3 fibroblasts. Unexpectedly, importin-5, ENH isoform 1b (PDLIM5) and 26 S protease regulatory subunit 6B (PSMC4) were more abundant (> 10-fold) in membrane-penetrating cell extensions than cell bodies, which was confirmed by immunostaining and immunoblotting and also observed in human gingival fibroblasts. After siRNA knockdown of these proteins and plating cells on grid-supported floating collagen gels for 6 h, formation of cell extensions and collagen remodeling were examined. Knockdown of importin-5 reduced collagen compaction (1.9-fold), pericellular collagen degradation (~ 1.8-fold) and number of cell extensions (~ 69%). Knockdown of PSMC4 reduced collagen compaction (~ 1.5-fold), pericellular collagen degradation (~ 1.7-fold) and number of cell extensions (~ 42%). Knockdown of PDLIM5 reduced collagen compaction (~ 1.6-fold) and number of cell extensions (~ 21%). Inhibition of the TGF-β RI kinase, Smad3 or ROCK-II signaling pathways reduced the abundance of PDLIM5 in cell extensions but PSMC4 and importin-5 were reduced only by Smad3 or ROCK-II inhibitors. We conclude that these novel proteins are required for cell extension formation and their recruitment into extensions involves the Smad3 and ROCK signaling pathways.

Automated contour analysis of multi-cellular spheroids spreading through high content imaging

The morphology of 2D cell colonies has been studied to understand tumor metastasis in the past decades. However, 2D cell cultures are lacking many features of 3D tissues, and their physiological behaviors are quite different from solid tumors in vivo. In this work, we studied the multi-cellular tumor spheroid (MCTS) spreading on the substrate, which keeps parts of 3D tissue characteristics and facilitates cell tracking through 2D imaging. By using a high content imaging system (HCS), we tracked multiple spheroids in one single 96-well plate for 36 h. An automated algorithm based on Otsu's method was developed to investigate the morphological details of spheroids through the quantification of radius length and its coefficients of variation. Spheroid spreading is altered by the PIP-platin, which was a novel platinum based drug previously reported by us with an inhibitory effect on cell migration. All parameters showed dose dependent decreases when PIP-platin concentration increased, indicating the inhibition of spheroid expansion by this compound. To investigate the surface roughness of spheroids affected by the drug, we applied the Fourier parameter β and the normalized standard deviation of the radius STD _r / [Formula: see text], which were found inversely proportional to the concentrations of PIP-platin. Particularly at the low drug concentrations, the indices of contour roughness appeared to be more sensitive than spheroid sizes, which could be the potential morphological markers for high content screening of drugs.

Imaging Tunneling Membrane Tubes Elucidates Cell Communication in Tumors

Intercellular communication is a vital yet underdeveloped aspect of cancer pathobiology. This Opinion article reviews the importance and challenges of microscopic imaging of tunneling nanotubes (TNTs) in the complex tumor microenvironment. The use of advanced microscopy to characterize TNTs in vitro and ex vivo, and related extensions called tumor microtubes (TMs) reported in gliomas in vivo, has propelled this field forward. This topic is important because the identification of TNTs and TMs fills the gap in our knowledge of how cancer cells communicate at long range in vivo, inducing intratumor heterogeneity and resistance to treatment. Here we discuss the concept that TNTs/TMs fill an important niche in the ever-changing microenvironment and the role of advanced microscopic imaging to elucidate that niche.