Integrin α5β1, the Fibronectin Receptor, as a Pertinent Therapeutic Target in Solid Tumors

Unraveling the molecular basis for effective regulation of integrin α5β1 for enhanced therapeutic interventions

Cell attachment to the extracellular matrix significantly impacts the integrity of tissues and human health. The integrin α5β1 is a heterodimer of α5 and β1 subunits and has been identified as a crucial modulator in several human carcinomas. Integrin α5β1 significantly regulates cell proliferation, angiogenesis, inflammation, tumor metastasis, and invasion. This regulatory role of integrin α5β1 in tumor metastasis makes it an appealing target for cancer therapy. The majority of the drugs targeting integrin α5β1 are limited only to clinical trials. In our study, we have performed 94287 compounds screening to determine potential drugs against α5β1 integrin. We have used ATN-161 as a reference and employed combined bioinformatic methodologies, including molecular modelling, virtual screening, MM-GBSA, cell-line cytotoxicity prediction, ADMET, Density Functional Theory (DFT), Non-covalent Interactions (NCI) and molecular simulation, to identify putative integrin α5β1 inhibitors. We found Taxifolin, PD133053, and Acebutolol that possess inhibitory activity against α5β1 integrin and could act as effective drug for the cancer treatment. Taxifolin, PD133053, and Acebutolol exhibited excellent binding to the druggable pocket of integrin α5β1, and also maintained a unique binding mechanism with extra hydrophobic contacts at molecular level. Overall, our study gives new pharmacological candidates that may act as a potential drug against integrin α5β1.

Hypoxia-driven heterogeneous expression of α5 integrin in glioblastoma stem cells is linked to HIF-2α

Despite numerous molecular targeted therapies tested in glioblastoma (GBM), no significant progress in patient survival has been achieved in the last 20 years in the overall population of GBM patients except with TTfield setup associated with the standard of care chemoradiotherapy. Therapy resistance is associated with target expression heterogeneity and plasticity between tumors and in tumor niches. We focused on α5 integrin implicated in aggressive GBM in preclinical and clinical samples. To address the characteristics of α5 integrin heterogeneity we started with patient data indicating that elevated levels of its mRNA are related to hypoxia pathways. We turned on glioma stem cells which are considered at the apex of tumor formation and recurrence but also as they localize in hypoxic niches. We demonstrated that α5 integrin expression is stem cell line dependent and is modulated positively by hypoxia in vitro. Importantly, heterogeneity of expression is conserved in in vivo stem cell-derived mice xenografts. In hypoxic niches, HIF-2α is preferentially implicated in α5 integrin expression which confers migratory capacity to GBM stem cells. Hence combining HIF-2α and α5 integrin inhibitors resulted in proliferation and migration impairment of α5 integrin expressing cells. Stabilization of HIF-2α is however not sufficient to control integrin α5 expression. Our results show that AHR (aryl hydrocarbon receptor) expression is inversely related to HIF-2α and α5 integrin expressions suggesting a functional competition between the two transcription factors. Collectively, data confirm the high heterogeneity of a GBM therapeutic target, its induction in hypoxic niches by HIF-2α and suggest a new way to attack molecularly defined GBM stem cells.

Integrin mechanosensing relies on a pivot-clip mechanism to reinforce cell adhesion

Cells intricately sense mechanical forces from their surroundings, driving biophysical and biochemical activities. This mechanosensing phenomenon occurs at the cell-matrix interface, where mechanical forces resulting from cellular motion, such as migration or matrix stretching, are exchanged through surface receptors, primarily integrins, and their corresponding matrix ligands. A pivotal player in this interaction is the α5β1 integrin and fibronectin (FN) bond, known for its role in establishing cell adhesion sites for migration. However, upregulation of the α5β1-FN bond is associated with uncontrolled cell metastasis. This bond operates through catch bond dynamics, wherein the bond lifetime paradoxically increases with greater force. The mechanism sustaining the characteristic catch bond dynamics of α5β1-FN remains unclear. Leveraging molecular dynamics simulations, our approach unveils a pivot-clip mechanism. Two key binding sites on FN, namely the synergy site and the RGD (Arg-Gly-Asp) motif, act as active points for structural changes in α5β1 integrin. Conformational adaptations at these sites are induced by a series of hydrogen bond formations and breaks at the synergy site. We disrupt these adaptations through a double mutation on FN, known to reduce cell adhesion. A whole-cell finite-element model is employed to elucidate how the synergy site may promote dynamic α5β1-FN binding, resisting cell contraction. In summary, our study integrates molecular- and cellular-level modeling to propose that FN's synergy site reinforces cell adhesion through enhanced binding dynamics and a mechanosensitive pivot-clip mechanism. This work sheds light on the interplay between mechanical forces and cell-matrix interactions, contributing to our understanding of cellular behaviors in physiological and pathological contexts.

Emerging anticancer potential and mechanisms of snake venom toxins: A review

Animal-derived venom, like snake venom, has been proven to be valuable natural resources for the drug development. Previously, snake venom was mainly investigated in its pharmacological activities in regulating coagulation, vasodilation, and cardiovascular function, and several marketed cardiovascular drugs were successfully developed from snake venom. In recent years, snake venom fractions have been demonstrated with anticancer properties of inducing apoptotic and autophagic cell death, restraining proliferation, suppressing angiogenesis, inhibiting cell adhesion and migration, improving immunity, and so on. A number of active anticancer enzymes and peptides have been identified from snake venom toxins, such as L-amino acid oxidases (LAAOs), phospholipase A2 (PLA2), metalloproteinases (MPs), three-finger toxins (3FTxs), serine proteinases (SPs), disintegrins, C-type lectin-like proteins (CTLPs), cell-penetrating peptides, cysteine-rich secretory proteins (CRISPs). In this review, we focus on summarizing these snake venom-derived anticancer components on their anticancer activities and underlying mechanisms. We will also discuss their potential to be developed as anticancer drugs in the future.

Effects of syndecan-4 silencing on the extracellular matrix remodeling in anoikis-resistant endothelial cells

Anoikis is a process of programmed cell death induced by the loss of cell/matrix interactions. In previous work, we have shown that the acquisition of anoikis resistance upregulates syndecan-4 (SDC4) expression in endothelial cells. In addition, SDC4 gene silencing by microRNA interference reverses the transformed phenotype of anoikis-resistant endothelial cells. Due to this role of SDC4 in regulating the behavior of anoikis-resistant endothelial cells, we have evaluated that the functional consequences of SDC4 silencing in the extracellular matrix (ECM) remodeling in anoikis-resistant rabbit aortic endothelial cells submitted to SDC4 gene silencing (miR-Syn4-Adh-1-EC). For this, we evaluated the expression of adhesive proteins, ECM receptors, nonreceptor protein-tyrosine kinases, and ECM-degrading enzymes and their inhibitors. Altered cell behavior was monitored by adhesion, migration, and tube formation assays. We found that SDC4 silencing led to a decrease in migration and angiogenic capacity of anoikis-resistant endothelial cells; this was accompanied by an increase in adhesion to fibronectin. Furthermore, after SDC4 silencing, we observed an increase in the expression of fibronectin, collagen IV, and vitronectin, and a decrease in the expression of integrin α5β1 and αvβ3, besides that, silenced cells show an increase in Src and FAK expression. Quantitative polymerase chain reaction and Western blot analysis demonstrated that SDC4 silencing leads to altered gene and protein expression of MMP2, MMP9, and HSPE. Compared with parental cells, SDC4 silenced cells showed a decrease in nitric oxide production and eNOS expression. In conclusion, these data demonstrate that SDC4 plays an important role in ECM remodeling. In addition, our findings represent an important step toward understanding the mechanism by which SDC4 can reverse the transformed phenotype of anoikis-resistant endothelial cells.

Osteoarthritis: Insights into Diagnosis, Pathophysiology, Therapeutic Avenues, and the Potential of Natural Extracts

Osteoarthritis (OA) stands as a prevalent and progressively debilitating clinical condition globally, impacting joint structures and leading to their gradual deterioration through inflammatory mechanisms. While both non-modifiable and modifiable factors contribute to its onset, numerous aspects of OA pathophysiology remain elusive despite considerable research strides. Presently, diagnosis heavily relies on clinician expertise and meticulous differential diagnosis to exclude other joint-affecting conditions. Therapeutic approaches for OA predominantly focus on patient education for self-management alongside tailored exercise regimens, often complemented by various pharmacological interventions primarily targeting pain alleviation. However, pharmacological treatments typically exhibit short-term efficacy and local and/or systemic side effects, with prosthetic surgery being the ultimate resolution in severe cases. Thus, exploring the potential integration or substitution of conventional drug therapies with natural compounds and extracts emerges as a promising frontier in enhancing OA management. These alternatives offer improved safety profiles and possess the potential to target specific dysregulated pathways implicated in OA pathogenesis, thereby presenting a holistic approach to address the condition's complexities.

Molecular engineering of a spheroid-penetrating phage nanovector for photodynamic treatment of colon cancer cells

Photodynamic therapy (PDT) represents an emerging strategy to treat various malignancies, including colorectal cancer (CC), the third most common cancer type. This work presents an engineered M13 phage retargeted towards CC cells through pentavalent display of a disulfide-constrained peptide nonamer. The M13CC nanovector was conjugated with the photosensitizer Rose Bengal (RB), and the photodynamic anticancer effects of the resulting M13CC-RB bioconjugate were investigated on CC cells. We show that upon irradiation M13CC-RB is able to impair CC cell viability, and that this effect depends on i) photosensitizer concentration and ii) targeting efficiency towards CC cell lines, proving the specificity of the vector compared to unmodified M13 phage. We also demonstrate that M13CC-RB enhances generation and intracellular accumulation of reactive oxygen species (ROS) triggering CC cell death. To further investigate the anticancer potential of M13CC-RB, we performed PDT experiments on 3D CC spheroids, proving, for the first time, the ability of engineered M13 phage conjugates to deeply penetrate multicellular spheroids. Moreover, significant photodynamic effects, including spheroid disruption and cytotoxicity, were readily triggered at picomolar concentrations of the phage vector. Taken together, our results promote engineered M13 phages as promising nanovector platform for targeted photosensitization, paving the way to novel adjuvant approaches to fight CC malignancies.

Absolute binding free energies of the antiviral peptide ATN-161 with protein targets of SARS-CoV-2

The interactions of the antiviral pentapeptide ATN-161 with the closed and open conformations of the α5β1 integrin, the SARS-CoV-2 major protease, and the omicron variant spike protein complexed with hACE2 were studied using molecular docking and molecular dynamics simulation. Molecular docking was performed to obtain ATN-161 binding poses with these studied protein targets. Subsequently, molecular dynamics simulations were performed to verify the ligand stability at the binding site of each protein target. Pulling simulations, umbrella sampling, and weighted histogram analysis method were used to obtain the potential of mean force of each system and calculate the Gibbs free energy of binding for the ATN-161 peptide in each binding site of these protein targets. The results showed that ATN-161 binds to α5β1 integrin in its active and inactive form, binds weakly to the omicron variant spike protein complexed with hACE2, and strongly binds to the main protease target.Communicated by Ramaswamy H. Sarma.

Targeting integrin α5 in fibroblasts potentiates colorectal cancer response to PD-L1 blockade by affecting extracellular-matrix deposition

BACKGROUND

One reason patients with cancer cannot benefit from immunotherapy is the lack of immune cell infiltration in tumor tissues. Cancer-associated fibroblasts (CAFs) are emerging as central players in immune regulation that shapes tumor microenvironment (TME). Earlier we reported that integrin α5 was enriched in CAFs in colorectal cancer (CRC), however, its role in TME and cancer immunotherapy remains unclear. Here, we aimed to investigate the role for integrin α5 in fibroblasts in modulating antitumor immunity and therapeutic efficacy combined with checkpoint blockade in CRC.

METHODS

We analyzed the CRC single-cell RNA sequencing (scRNA-seq) database to define the expression of ITGA5 in CRC tumor stroma. Experimentally, we carried out in vivo mouse tumor xenograft models to confirm the targeting efficacy of combined α5β1 inhibition and anti-Programmed death ligand 1 (PD-L1) blockade and in vitro cell-co-culture assay to investigate the role of α5 in fibroblasts in affecting T-cell activity. Clinically, we analyzed the association between α5 expression and infiltrating T cells and evaluated their correlation with patient survival and immunotherapy prognosis in CRC.

RESULTS

We revealed that ITGA5 was enriched in FAP-CAFs. Both ITGA5 knockout fibroblasts and therapeutic targeting of α5 improved response to anti-PD-L1 treatment in mouse subcutaneous tumor models. Mechanistically, these treatments led to increased tumor-infiltrating CD8+ T cells. Furthermore, we found that α5 in fibroblasts correlated with extracellular matrix (ECM)-related genes and affected ECM deposition in CRC tumor stroma. Both in vivo analysis and in vitro culture and cell killing experiment showed that ECM proteins and α5 expression in fibroblasts influence T-cell infiltration and activity. Clinically, we confirmed that high α5 expression was associated with fewer CD3+ T and CD8+ T cells, and tissues with low α5 and high CD3+ T levels correlated with better patient survival and immunotherapy response in a CRC cohort with 29 patients.

CONCLUSIONS

Our study identified a role for integrin α5 in fibroblasts in modulating antitumor immunity by affecting ECM deposition and showed therapeutic efficacy for combined α5β1 inhibition and PD-L1 blockade in CRC.

Pllans-II: Unveiling the Action Mechanism of a Promising Chemotherapeutic Agent Targeting Cervical Cancer Cell Adhesion and Survival Pathways

Despite advances in chemotherapeutic drugs used against cervical cancer, available chemotherapy treatments adversely affect the patient's quality of life. For this reason, new molecules from natural sources with antitumor potential and few side effects are required. In previous research, Pllans-II, a phospholipase A2 type-Asp49 from Porthidium lansbergii lansbergii snake venom, has shown selective attack against the HeLa and Ca Ski cervical cancer cell lines. This work suggests that the cytotoxic effect generated by Pllans-II on HeLa cells is triggered without affecting the integrity of the cytoplasmic membrane or depolarizing the mitochondrial membranes. The results allow us to establish that cell death in HeLa is related to the junction blockage between α5β1 integrins and fibronectin of the extracellular matrix. Pllans-II reduces the cells' ability of adhesion and affects survival and proliferation pathways mediated by intracellular communication with the external environment. Our findings confirmed Pllans-II as a potential prototype for developing a selective chemotherapeutic drug against cervical cancer.

Extracellular pyruvate kinase M2 induces cell migration through p-Tyr42 RhoA-mediated superoxide generation and epithelial-mesenchymal transition

In the tumor microenvironment (TME), communication between cancer cells and tumor-associated macrophages (TAMs) through secreted extracellular proteins promotes cancer progression. Here, we observed that co-culturing cancer cells (4T1) and macrophage cells (Raw264.7) significantly enhanced superoxide production in both cell types. Using MALDI-TOF, we identified PKM2 as a highly secreted protein by Raw264.7 cells and bone marrow-derived monocytes. The extracellular recombinant PKM2 protein not only enhanced cancer cell migration and invasion but also increased superoxide production. Additionally, PKM2 was found to associate with the cell surface, and its binding to integrin α5/β1 receptor was inhibited by antibodies specifically targeting it. Furthermore, we investigated downstream signaling pathways involved in PKM2-induced superoxide production. We found that knock-down of RhoA and p47phox using siRNAs effectively abolished superoxide generation in response to extracellular PKM2. Notably, extracellular PKM2 triggered the phosphorylation of p47phox at Ser345 residue and RhoA at Tyr42 residue (p-Tyr42 RhoA). Moreover, extracellular PKM2 exerted regulatory control over the expression of key epithelial-mesenchymal transition (EMT) markers, including ZEB1, Snail1, vimentin, and E-cadherin. Interestingly, p-Tyr42 RhoA translocated to the nucleus, where it bound to the ZEB1 promoter region. In light of these findings, we propose that extracellular PKM2 within the TME plays a critical role in tumorigenesis by promoting cancer cell migration and invasion through RhoA/p47phox signaling pathway.

Gene expression and cell culture assays reveal cheese isolate Lactococcus lactis MC5 may influence the virulence of Staphylococcus aureus

Staphylococcus aureus (SA) can thrive in a wide variety of hosts and environments, causing clinical infections and foodborne intoxications. In Brazil, SA is commonly isolated from traditional soft cheeses, especially those prepared from unpasteurized milk. In this research, the isolate S. aureus SABRC1 was evaluated for virulence traits under different conditions, including co-inoculation with Lactococcus lactis MC5 (isolated from "Fresh Minas Cheese"), which produces antibacterial peptides. Results from experiments with Caco-2 culture indicated S. aureus SABRC1 was able to adhere (42.83 ± 1.79%) and to invade (48.57 ± 0.41%) the intestinal cells. On the other hand, L. lactis MC5 presented anti-staphylococcal activity as indicated by agar assays, and it was also able to antagonize intestinal cell invasion by S. aureus. Moreover, Reverse Transcriptase-PCR experiments showed virulence genes of S. aureus SABRC1 (hla, icaA and sea) were differentially expressed under diverse culture conditions, which included Brain Heart Infusion modified or not by the addition of glucose, sodium chloride, milk or cheese. This suggests the virulence of S. aureus SABRC1 is influenced by compounds commonly found in daily diets, and not only by its genetic repertoire, adding a novel level of complexity for controlling infection by this pathogen.

Mutant p53-ENTPD5 control of the calnexin/calreticulin cycle: a druggable target for inhibiting integrin-α5-driven metastasis

BACKGROUND

TP53, encoding the tumor suppressor p53, is frequently mutated in various cancers, producing mutant p53 proteins (mutp53) which can exhibit neomorphic, gain-of-function properties. The latter transform p53 into an oncoprotein that promotes metastatic tumor progression via downstream effectors such as ENTPD5, an endoplasmic reticulum UDPase involved in the calnexin/calreticulin cycle of N-glycoprotein biosynthesis. Elucidating the mechanisms underlying the pro-metastatic functions of the mutp53-ENTPD5 axis is crucial for developing targeted therapies for aggressive metastatic cancer.

METHODS

We analyzed pancreatic, lung, and breast adenocarcinoma cells with p53 missense mutations to study the impact of mutp53 and ENTPD5 on the N-glycoproteins integrin-α5 (ITGA5) and integrin-β1 (ITGB1), which heterodimerize to form the key fibronectin receptor. We assessed the role of the mutp53-ENTPD5 axis in integrin-dependent tumor-stroma interactions and tumor cell motility using adhesion, migration, and invasion assays, identifying and validating therapeutic intervention targets. We employed an orthotopic xenograft model of pancreatic ductal adenocarcinoma to examine in vivo targeting of mutp53-ENTPD5-mediated ITGA5 regulation for cancer therapy.

RESULTS

Mutp53 depletion diminished ITGA5 and ITGB1 expression and impaired tumor cell adhesion, migration, and invasion, rescued by ENTPD5. The mutp53-ENTPD5 axis maintained ITGA5 expression and function via the calnexin/calreticulin cycle. Targeting this axis using ITGA5-blocking antibodies, α-glucosidase inhibitors, or pharmacological degradation of mutp53 by HSP90 inhibitors, such as Ganetespib, effectively inhibited ITGA5-mediated cancer cell motility in vitro. In the orthotopic xenograft model, Ganetespib reduced ITGA5 expression and metastasis in an ENTPD5-dependent manner.

CONCLUSIONS

The mutp53-ENTPD5 axis fosters ITGA5 and ITGB1 expression and tumor cell motility through the calnexin/calreticulin cycle, contributing to cancer metastasis. ITGA5-blocking antibodies or α-glucosidase inhibitors target this axis and represent potential therapeutic options worth exploring in preclinical models. The pharmacologic degradation of mutp53 by HSP90 inhibitors effectively blocks ENTPD5-ITGA5-mediated cancer cell motility and metastasis in vivo, warranting further clinical evaluation in p53-mutant cancers. This research underscores the significance of understanding the complex interplay between mutp53, ENTPD5, and the calnexin/calreticulin cycle in integrin-mediated metastatic tumor progression, offering valuable insights for the development of potential therapeutic strategies.

Targeting integrin α5β1 in urological tumors: opportunities and challenges

Urological tumors, such as prostate cancer, renal cell carcinoma, and bladder cancer, have shown a significant rise in prevalence in recent years and account for a significant proportion of malignant tumors. It has been established that metastasis to distant organs caused by urological tumors is the main cause of death, although the mechanisms underlying metastasis have not been fully elucidated. The fibronectin receptor integrin α5β1 reportedly plays an important role in distant metastasis and is closely related to tumor development. It is widely thought to be an important cancer mediator by interacting with different ligands, mediating tumor adhesion, invasion, and migration, and leading to immune escape. In this paper, we expound on the relationship and regulatory mechanisms of integrin α5β1 in these three cancers. In addition, the clinical applications of integrin α5β1 in these cancers, especially against treatment resistance, are discussed. Last but not least, the possibility of integrin α5β1 as a potential target for treatment is examined, with new ideas for future research being proposed.

Strategic outline of interventions targeting extracellular matrix for promoting healthy longevity

The extracellular matrix (ECM), composed of interlinked proteins outside of cells, is an important component of the human body that helps maintain tissue architecture and cellular homeostasis. As people age, the ECM undergoes changes that can lead to age-related morbidity and mortality. Despite its importance, ECM aging remains understudied in the field of geroscience. In this review, we discuss the core concepts of ECM integrity, outline the age-related challenges and subsequent pathologies and diseases, summarize diagnostic methods detecting a faulty ECM, and provide strategies targeting ECM homeostasis. To conceptualize this, we built a technology research tree to hierarchically visualize possible research sequences for studying ECM aging. This strategic framework will hopefully facilitate the development of future research on interventions to restore ECM integrity, which could potentially lead to the development of new drugs or therapeutic interventions promoting health during aging.

Integrins in cancer: Emerging mechanisms and therapeutic opportunities

Integrins are vital surface adhesion receptors that mediate the interactions between the extracellular matrix (ECM) and cells and are essential for cell migration and the maintenance of tissue homeostasis. Aberrant integrin activation promotes initial tumor formation, growth, and metastasis. Recently, many lines of evidence have indicated that integrins are highly expressed in numerous cancer types and have documented many functions of integrins in tumorigenesis. Thus, integrins have emerged as attractive targets for the development of cancer therapeutics. In this review, we discuss the underlying molecular mechanisms by which integrins contribute to most of the hallmarks of cancer. We focus on recent progress on integrin regulators, binding proteins, and downstream effectors. We highlight the role of integrins in the regulation of tumor metastasis, immune evasion, metabolic reprogramming, and other hallmarks of cancer. In addition, integrin-targeted immunotherapy and other integrin inhibitors that have been used in preclinical and clinical studies are summarized.

Emerging Targets for Modulation of Immune Response and Inflammation in Stroke

The inflammatory and immunological responses play a significant role after stroke. The innate immune activation stimulated by microglia during stroke results in the migration of macrophages and lymphocytes into the brain and are responsible for tissue damage. The immune response and inflammation following stroke have no defined targets, and the intricacies of the immunological and inflammatory processes are only partially understood. Innate immune cells enter the brain and meninges during the acute phase, which can cause ischemia damage. Activation of systemic immunity is caused by danger signals sent into the bloodstream by injured brain cells, which is followed by a significant immunodepression that encourages life-threatening infections. Neuropsychiatric sequelae, a major source of post-stroke morbidity, may be induced by an adaptive immune response that is initiated by antigen presentation during the chronic period and is directed against the brain. Thus, the current review discusses the role of immune response and inflammation in stroke pathogenesis, their role in the progression of injury during the stroke, and the emerging targets for the modulation of the mechanism of immune response and inflammation that may have possible therapeutic benefits against stroke.

Inhibition of bladder cancer growth with homoharringtonine by inactivating integrin α5/β1-FAK/Src axis: A novel strategy for drug application

The application of immune checkpoint inhibitors and FGFR protein tyrosine kinase inhibitors have made a tremendous breakthrough in bladder cancer therapy. However, inadequate drug responses and drug resistance interfere with successful treatment outcomes. For a new drug to enter the market, there is a long development cycle with high costs and low success rates. Repurposing previously Food and Drug Administration (FDA)-approved medications and using novel drug discovery strategies may be an optimal approach. Homoharringtonine (HHT) has been used for hematologic malignancies for over 40 years in China and was approved by the FDA approximately 10 years ago. Many studies have demonstrated that HHT effectively inhibits the development of several types of solid tumors, although the underlying mechanisms of action are unclear. In this study, we investigated the mechanisms underlying HHT activity against bladder cancer growth. We first compared HTT with the drugs currently used clinically for bladder cancer treatment. HHT showed stronger inhibitory activity than cisplatin, carboplatin, and doxorubicin. Our in vitro and in vivo data demonstrated that HHT inhibited proliferation, colony formation, migration, and cell adhesion of bladder cancer cells and induced apoptosis and cell cycle arrest in the nanomolar concentration range. Furthermore, we revealed that HHT treatment could downregulate the MAPK/Erk and PI3k/Akt signaling pathways by inactivating the integrin α5/β1-FAK/Src axis. HHT-induced activity reduced cell-ECM interactions and cell migration, thus suppressing tumor metastasis progression. Altogether, HHT shows enormous potential as an anticancer agent and may be applied as a combination treatment strategy for bladder cancer.

Bacterial RNA virus MS2 exposure increases the expression of cancer progression genes in the LNCaP prostate cancer cell line

Bacteriophages effectively counteract diverse bacterial infections, and their ability to treat most types of cancer has been explored using phage engineering or phage-virus hybrid platforms. In the present study, it was demonstrated that the bacteriophage MS2 can affect the expression of genes associated with the proliferation and survival of LNCaP prostate epithelial cells. LNCaP cells were exposed to bacteriophage MS2 at a concentration of 1×10⁷ plaque forming units/ml for 24-48 h. After exposure, various cellular parameters, including cell viability, morphology, and changes in gene expression, were examined. MS2 affected cell viability adversely, reducing viability by 25% in the first 4 h of treatment; however, cell viability recovered within 24-48 h. Similarly, the AKT, androgen receptor, integrin α5, integrin β1, MAPK1, MAPK3, STAT3, and peroxisome proliferator-activated receptor-γ coactivator 1α genes, which are involved in various normal cellular processes and tumor progression, were significantly upregulated, whereas the expression levels of HSP90, ITGB5, ITGB3, HSP27, ITGAV, and PI3K genes were unchanged. Therefore, based on viability and gene expression changes, bacteriophage MS2 severely impaired LNCaP cells by reducing anchorage-dependent survival and androgen signaling. A caveolin-mediated endocytosis mechanism for MS2-mediated signaling in prostate cancer cells was proposed based on reports involving bacteriophages T4, M13, and MS2, and their interactions with LNCaP and PC3 cell lines.

Combination of Quercetin or/and siRNA-loaded DDAB-mPEG-PCL hybrid nanoparticles reverse resistance to Regorafenib in colon cancer cells

BACKGROUND

Colorectal cancer (CRC) is the second leading cause of cancer death. Although Regorafenib showed survival benefits in patients with CRC, reports imply the recurrence of malignant phenotype resulting from chemotherapy. Evidence demonstrated that a5β1 integrin plays an important role in the Regorafenib treatment, which, may be led to resistance. In this study, the effects of /siRNA or/ and Quercetin loaded DDAB-mPEG-PCLnanoparticles could reverse this resistance phenotype in colon cancer cells in vitro.

METHODS

Regorafenib-resistant Ls-180 colon cancer cell line was developed by long-term exposure to Regorafenib. Quercetin and Regorafenib were separately encapsulated into mPEG-PCL micelles through the nano-precipitation method and characterized by DLS. Optimized doses of Quercetin and Regorafenib were used for combination therapy of resistant cells followed cytotoxicity study using MTT. Gene expression levels of the β1 subunit of integrin were determined by the real-time method of RT-PCR.

RESULTS

Developed Regorafenib resistant LS-180 showed to have Regorafenib IC50 of 38.96 ± 1.72 µM whereas IC50 in non-resistant cells were 8.51 ± 0.29 µM, which meaningful was lower statistically compared to that of a resistant one. The β1 mRNA level of whole α5β1 integrin was significantly higher in the resistant cells compared to those of non-resistant ones. Gene expression levels in each siRNA-loaded nanoparticle and Quercetin-loaded one were lower than that in mock experiments. Finally, when these two types of nanoparticles were used to treat resistant cells, gene expression decrease of integrin indicated a greater effect that could be capable of reverse resistancy.

CONCLUSION

Results of this study demonstrated another confirmation of involving integrins in cancer resistance following chemotherapy using Regorafenib. Also, it indicated how using siRNA targeting integrin could enhance the plant derivatives like Quercetin effects to reverse resistance in vitro.

Plasma polymerized bio-interface directs fibronectin adsorption and functionalization to enhance "epithelial barrier structure" formation via FN-ITG β1-FAK-mTOR signaling cascade

BACKGROUND

Transepithelial medical devices are increasing utilized in clinical practices. However, the damage of continuous natural epithelial barrier has become a major risk factor for the failure of epithelium-penetrating implants. How to increase the "epithelial barrier structures" (focal adhesions, hemidesmosomes, etc.) becomes one key research aim in overcoming this difficulty. Directly targeting the in situ "epithelial barrier structures" related proteins (such as fibronectin) absorption and functionalization can be a promising way to enhance interface-epithelial integration.

METHODS

Herein, we fabricated three plasma polymerized bio-interfaces possessing controllable surface chemistry. Their capacity to adsorb and functionalize fibronectin (FN) from serum protein was compared by Liquid Chromatography-Tandem Mass Spectrometry. The underlying mechanisms were revealed by molecular dynamics simulation. The response of gingival epithelial cells regarding the formation of epithelial barrier structures was tested.

RESULTS

Plasma polymerized surfaces successfully directed distinguished protein adsorption profiles from serum protein pool, in which plasma polymerized allylamine (ppAA) surface favored adsorbing adhesion related proteins and could promote FN absorption and functionalization via electrostatic interactions and hydrogen bonds, thus subsequently activating the ITG β1-FAK-mTOR signaling and promoting gingival epithelial cells adhesion.

CONCLUSION

This study offers an effective perspective to overcome the current dilemma of the inferior interface-epithelial integration by in situ protein absorption and functionalization, which may advance the development of functional transepithelial biointerfaces. Tuning the surface chemistry by plasma polymerization can control the adsorption of fibronectin and functionalize it by exposing functional protein domains. The functionalized fibronectin can bind to human gingival epithelial cell membrane integrins to activate epithelial barrier structure related signaling pathway, which eventually enhances the formation of epithelial barrier structure.

ANGPTL8 links inflammation and poor differentiation, which are characteristics of malignant renal cell carcinoma

Inflammation is observed in many tumors, which affects metastasis, infiltration, and immune escape and causes poor differentiation of the cancer cells. However, the molecular basis underlying the relationship between inflammation and poor differentiation in tumors has not been identified. In this study, we demonstrate that angiopoietin-like protein-8 (ANGPTL8), which is induced by stress stimuli such as inflammation, is involved in the maintenance of the undifferentiated state of clear cell renal cell carcinoma (ccRCC) cells. ANGPTL8 is also involved in the production of chemokines that attract immune suppressor cells to the tumor microenvironment. ANGPTL8 sustains the continuous production of chemokines by activating the NF-κB signaling pathway and maintains the undifferentiated state of ccRCC cells. Finally, ANGPTL8 is induced by STAT3 signaling, which is activated by immune cells in the tumor microenvironment. These results support a role for ANGPTL8 in determining the properties of ccRCC by hampering tumor cell differentiation and establishing the tumor microenvironment.

Early diagnosis of bladder cancer by photoacoustic imaging of tumor-targeted gold nanorods

Detection and removal of bladder cancer lesions at an early stage is crucial for preventing tumor relapse and progression. This study aimed to develop a new technological platform for the visualization of small and flat urothelial lesions of high-grade bladder carcinoma in situ (CIS). We found that the integrin α5β1, overexpressed in bladder cancer cell lines, murine orthotopic bladder cancer and human bladder CIS, can be exploited as a receptor for targeted delivery of GNRs functionalized with the cyclic CphgisoDGRG peptide (Iso4). The GNRs@Chit-Iso4 was stable in urine and selectively recognized α5β1 positive neoplastic urothelium, while low frequency ultrasound-assisted shaking of intravesically instilled GNRs@Chit-Iso4 allowed the distribution of nanoparticles across the entire volume of the bladder. Photoacoustic imaging of GNRs@Chit-Iso4 bound to tumor cells allowed for the detection of neoplastic lesions smaller than 0.5 mm that were undetectable by ultrasound imaging and bioluminescence.

Polymer Thin Film Promotes Tumor Spheroid Formation via JAK2-STAT3 Signaling Primed by Fibronectin-Integrin α5 and Sustained by LMO2-LDB1 Complex

Cancer stem-like cells (CSCs) are considered promising targets for anti-cancer therapy owing to their role in tumor progression. Extensive research is, therefore, being carried out on CSCs to identify potential targets for anti-cancer therapy. However, this requires the availability of patient-derived CSCs ex vivo, which remains restricted due to the low availability and diversity of CSCs. To address this limitation, a functional polymer thin-film (PTF) platform was invented to induce the transformation of cancer cells into tumorigenic spheroids. In this study, we demonstrated the functionality of a new PTF, polymer X, using a streamlined production process. Polymer X induced the formation of tumor spheroids with properties of CSCs, as revealed through the upregulated expression of CSC-related genes. Signal transducer and activator of transcription 3 (STAT3) phosphorylation in the cancer cells cultured on polymer X was upregulated by the fibronectin-integrin α5-Janus kinase 2 (JAK2) axis and maintained by the cytosolic LMO2/LBD1 complex. In addition, STAT3 signaling was critical in spheroid formation on polymer X. Our PTF platform allows the efficient generation of tumor spheroids from cancer cells, thereby overcoming the existing limitations of cancer research.

Bioimaging Nucleic-Acid Aptamers with Different Specificities in Human Glioblastoma Tissues Highlights Tumoral Heterogeneity

Nucleic-acid aptamers are of strong interest for diagnosis and therapy. Compared with antibodies, they are smaller, stable upon variations in temperature, easy to modify, and have higher tissue-penetration abilities. However, they have been little described as detection probes in histology studies of human tissue sections. In this study, we performed fluorescence imaging with two aptamers targeting cell-surface receptors EGFR and integrin α5β1, both involved in the aggressiveness of glioblastoma. The aptamers’ cell-binding specificities were confirmed using confocal imaging. The affinities of aptamers for glioblastoma cells expressing these receptors were in the 100–300 nM range. The two aptamers were then used to detect EGFR and integrin α5β1 in human glioblastoma tissues and compared with antibody labeling. Our aptafluorescence assays proved to be able to very easily reveal, in a one-step process, not only inter-tumoral glioblastoma heterogeneity (differences observed at the population level) but also intra-tumoral heterogeneity (differences among cells within individual tumors) when aptamers with different specificities were used simultaneously in multiplexing labeling experiments. The discussion also addresses the strengths and limitations of nucleic-acid aptamers for biomarker detection in histology.

An innovative strategy to identify new targets for delivering antibodies to the brain has led to the exploration of the integrin family

Background

Increasing brain exposure of biotherapeutics is key to success in central nervous system disease drug discovery. Accessing the brain parenchyma is especially difficult for large polar molecules such as biotherapeutics and antibodies because of the blood-brain barrier. We investigated a new immunization strategy to identify novel receptors mediating transcytosis across the blood-brain barrier.

Method

We immunized mice with primary non-human primate brain microvascular endothelial cells to obtain antibodies. These antibodies were screened for their capacity to bind and to be internalized by primary non-human primate brain microvascular endothelial cells and Human Cerebral Microvascular Endothelial Cell clone D3. They were further evaluated for their transcytosis capabilities in three in vitro blood-brain barrier models. In parallel, their targets were identified by two different methods and their pattern of binding to human tissue was investigated using immunohistochemistry.

Results

12 antibodies with unique sequence and internalization capacities were selected amongst more than six hundred. Aside from one antibody targeting Activated Leukocyte Cell Adhesion Molecule and one targeting Striatin3, most of the other antibodies recognized β1 integrin and its heterodimers. The antibody with the best transcytosis capabilities in all blood-brain barrier in vitro models and with the best binding capacity was an anti-αnβ1 integrin. In comparison, commercial anti-integrin antibodies performed poorly in transcytosis assays, emphasizing the originality of the antibodies derived here. Immunohistochemistry studies showed specific vascular staining on human and non-human primate tissues.

Conclusions

This transcytotic behavior has not previously been reported for anti-integrin antibodies. Further studies should be undertaken to validate this new mechanism in vivo and to evaluate its potential in brain delivery.

The prognostic and immune infiltration role of ITGB superfamily members in non-small cell lung cancer

PURPOSE

We aimed to explore the prognostic value of integrin-β superfamily members (ITGBs) and their role in immune cell infiltration in non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

Study cases were acquired from The Cancer Genome Atlas database and The Human Protein Atlas. We then used R package and several online tools to analyze and visualize the roles of ITGBs in lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC).

RESULTS

We found that ITGBs were differentially expressed in NSCLC. In LUAD, high expression of ITGB1 and ITGB4 was an independent risk factor for poor prognosis, and ITGB7 was an independent protective factor for overall survival; in LUSC, high expression of ITGB1, 3, 5, and 6 was associated with poor prognosis, and ITGB8 was an independent protective factor for disease-specific survival. Protein-protein interaction networks for the most associated co-expressed genes revealed the following target genes of ITGBs: PTPRC, ITGAM, and ITGB2 in LUAD and FN1, PTPRC, and ITGB2 in LUSC. Gene ontology analysis revealed that functions related to adhesion, junction, and binding were highly enriched in LUAD and LUSC. ITGBs were significantly associated with immune cell infiltration and the expression of immunomodulation-related genes in LUAD and LUSC.

CONCLUSION

ITGBs were differentially expressed in NSCLC. ITGB1, 4, and 7 and ITGB1, 3, 5, 6, and 8 were found as prognostic markers in LUAD and LUSC, respectively. ITGBs were significantly associated with immune cell infiltration and the expression of immunomodulation-related genes.

Ligand-Specific Nano-Contrast Agents Promote Enhanced Breast Cancer CT Detection at 0.5 mg Au

For many cancer types, being undetectable from early symptoms or blood tests, or often detected at late stages, medical imaging emerges as the most efficient tool for cancer screening. MRI, ultrasound, X-rays (mammography), and X-ray CT (CT) are currently used in hospitals with variable costs. Diagnostic materials that can detect breast tumors through molecular recognition and amplify the signal at the targeting site in combination with state-of-the-art CT techniques, such as dual-energy CT, could lead to a more precise detection and assist significantly in image-guided intervention. Herein, we have developed a ligand-specific X-ray contrast agent that recognizes α5β1 integrins overexpressed in MDA-MB-231 breast cancer cells for detection of triple (−) cancer, which proliferates very aggressively. In vitro studies show binding and internalization of our nanoprobes within those cells, towards uncoated nanoparticles (NPs) and saline. In vivo studies show high retention of ~3 nm ligand-PEG-S-AuNPs in breast tumors in mice (up to 21 days) and pronounced CT detection, with statistical significance from saline and iohexol, though only 0.5 mg of metal were utilized. In addition, accumulation of ligand-specific NPs is shown in tumors with minimal presence in other organs, relative to controls. The prolonged, low-metal, NP-enhanced spectral-CT detection of triple (−) breast cancer could lead to breakthrough advances in X-ray cancer diagnostics, nanotechnology, and medicine.

Dynamics of integrin α5β1, fibronectin, and their complex reveal sites of interaction and conformational change

Integrin α5β1 mediates cell adhesion to the extracellular matrix by binding fibronectin (Fn). Selectivity for Fn by α5β1 is achieved through recognition of an RGD motif in the 10th type III Fn domain (Fn10) and the synergy site in the ninth type III Fn domain (Fn9). However, details of the interaction dynamics are unknown. Here, we compared synergy-site and Fn-truncation mutations for their α5β1-binding affinities and stabilities. We also interrogated binding of the α5β1 ectodomain headpiece fragment to Fn using hydrogen-deuterium exchange (HDX) mass spectrometry to probe binding sites and sites of integrin conformational change. Our results suggest the synergistic effect of Fn9 requires both specific residues and a folded domain. We found some residues considered important for synergy are required for stability. Additionally, we show decreases in fibronectin HDX are localized to a synergy peptide containing contacting residues in two β-strands, an intervening loop in Fn9, and the RGD-containing loop in Fn10, indicative of binding sites. We also identified binding sites in the α5-subunit β-propeller domain for the Fn9 synergy site and in the β1-subunit βI domain for Fn10 based on decreases in α5β1 HDX. Interestingly, the dominant effect of Fn binding was an increase in α5β1 deuterium exchange distributed over multiple sites that undergo changes in conformation or solvent accessibility and appear to be sites where energy is stored in the higher-energy, open-integrin conformation. Together, our results highlight regions important for α5β1 binding to Fn and dynamics associated with this interaction.

Solubilization and Purification of α5β1 Integrin from Rat Liver for Reconstitution into Nanodiscs

Transmembrane proteins (or integral membrane proteins) are synthesized in the endoplasmic reticulum where most of them are core glycosylated prior to folding and in some cases assembly into quaternary structures. Correctly glycosylated, folded, and assembled transmembrane proteins are then shuttled to the Golgi apparatus for additional posttranslational modifications such as complex-type glycosylations, sulfation or proteolytic clipping. At the plasma membrane, the glycosylated extracellular domains are key to communicate with the cellular environment for a variety of functions, such as binding to the extracellular matrix for cell adhesion and migration, to neighboring cells for cell-cell interaction, or to extracellular components for nutrient uptake and cell signaling. Intracellular domains are essential to mediate signaling cascades, or to connect to cytosolic adaptors for internalization and intracellular compartmentalization. Despite its importance for the understanding of molecular mechanisms of transmembrane protein function, the determination of their structures has remained a challenging task. In recent years, their reconstitution in lipid nanodiscs in combination with high resolution cryo-electron microscopy has provided novel avenues to render this process more accessible. Here, we describe detailed protocols for the solubilization of heavily glycosylated α₅β₁ integrin from rat livers, its purification and reconstitution into nanodiscs. At the plasma membrane of many cells, including tumor metastases, this essential heterodimeric transmembrane protein mediates the communication between extracellular matrix and cytosolic cytoskeleton in processes of cell adhesion and migration. We expect that the protocols that are described here will provide new opportunities for the determination of the full structure of α₅β₁ integrin, as well as for the understanding of how interacting partners can regulate function and activity of this transmembrane protein.

The involvement of a chemokine receptor antagonist CTCE-9908 and kynurenine metabolites in cancer development

Cancer is the second leading cause of mortality worldwide. Skin cancer is the most common cancer in South Africa with nearly 20,000 reported cases every year and 700 deaths. If diagnosed early, the 5-year survival rate is about 90%, however, when diagnosed late, the 5-year survival rate decreases to about 20%. Melanoma is a type of skin cancer with an estimated 5-year survival rate of approximately 90%. Neuroblastoma is a paediatric cancer with a low survival rate. Sixty percent of patients with metastatic disease do not survive 5 years after diagnosis. Despite recent advances in targeted therapies, there is a crucial need to identify reliable prognostic biomarkers which will be able to contribute to the development of more precision-based chemotherapeutic strategies to prevent tumour migration and metastasis. The compound, CTCE-9908 inhibits the binding of CXC chemokine ligand 12 (CXCL12) to the CXC chemokine receptor 4 (CXCR4) receptor leading to reduced metastasis. Kynurenine metabolites are derived tryptophan, which is an essential amino acid. Kynurenine metabolites inhibit T-cell proliferation resulting in cell growth arrest. For this reason, chemokines receptors represent potential targets for the treatment of cancer growth and metastasis. In this review paper, the role of the CXCL12/CXCR4 signalling pathway in the development of cancer is highlighted together with the current available treatments involving the CTCE-9908 compound in combination with microtubule inhibitors like paclitaxel and docetaxel.

Novel Functions of Integrins as Receptors of CD154: Their Role in Inflammation and Apoptosis

CD154, an inflammatory mediator also known as CD40 ligand, has been identified as a novel binding partner for some members of the integrin family. The αIIbβ3, specifically expressed on platelets, was the first integrin to be described as a receptor for CD154 after CD40. Its interaction with soluble CD154 (sCD154) highly contributes to thrombus formation and stability. Identifying αIIbβ3 opened the door for investigating other integrins as partners of CD154. The αMβ2 expressed on myeloid cells was shown capable of binding CD154 and contributing as such to cell activation, adhesion, and release of proinflammatory mediators. In parallel, α5β1 communicates with sCD154, inducing pro-inflammatory responses. Additional pathogenic effects involving apoptosis-preventing functions were exhibited by the CD154–α5β1 dyad in T cells, conferring a role for such interaction in the survival of malignant cells, as well as the persistence of autoreactive T cells. More recently, CD154 receptors integrated two new integrin members, αvβ3 and α4β1, with little known as to their biological significance in this context. This article provides an overview of the novel role of integrins as receptors of CD154 and as critical players in pro-inflammatory and apoptotic responses.

Modelling liver cancer microenvironment using a novel 3D culture system

The tumor microenvironment and its contribution to tumorigenesis has been a focal highlight in recent years. A two-way communication between the tumor and the surrounding microenvironment sustains and contributes to the growth and metastasis of tumors. Progression and metastasis of hepatocellular carcinoma (HCC) have been reported to be exceedingly influenced by diverse microenvironmental cues. In this study, we present a 3D-culture model of liver cancer to better mimic in vivo tumor settings. By creating novel 3D co-culture model that combines free-floating and scaffold-based 3D-culture techniques of liver cancer cells and fibroblasts, we aimed to establish a simple albeit reproducible ex vivo cancer microenvironment model that captures tumor-stroma interactions. The model presented herein exhibited unique gene expression and protein expression profiles when compared to 2D and 3D mono-cultures of liver cancer cells. Our results showed that in vivo like conditions cannot be mimicked by simply growing cancer cells as spheroids, but by co-culturing them with 3D fibroblast with which they were able to crosstalk. This was evident by the upregulation of several pathways involved in HCC, and the increase in secreted factors by co-cultured cancer cells, many of which are also involved in tumor-stroma interactions. Compared to the conventional 2D culture, the proposed model exhibits an increase in the expression of genes associated with development, progression, and poor prognosis of HCC. Our results correlated with an aggressive outcome that better mirrors in vivo HCC, and therefore, a more reliable platform for molecular understanding of HCC.

Homomultimer strategy for improvement of radiolabeled peptides and antibody fragments in tumor targeting

A homomultimeric radioligand is composed of multiple identical ligands connected to the linker and radionuclide to detect a variety of overexpressed receptors on cancer cells. Multimer strategy holds great potential for introducing new radiotracers based on peptide and monoclonal antibody (mAb) derivatives in molecular imaging and therapy. It offers a reliable procedure for the preparation of biological-based targeting with diverse affinities and pharmacokinetics. In this context, we provide a useful summary and interpretation of the main results by a comprehensive look at multimeric radiopharmaceuticals in nuclear oncology. Therefore, there will be explanations for the strategy mechanisms and the main variables affecting the biodistribution results. The discussion is followed by highlights of recent work in the targeting of various types of receptors. The consequences are expressed based on comparing some parameters between monomer and multimer counterparts in each relevant section.

Synthesis and Evaluation of a Non-Peptide Small-Molecule Drug Conjugate Targeting Integrin αVβ3

An integrin α_Vβ₃-targeting linear RGD mimetic containing a small-molecule drug conjugate (SMDC) was synthesized by combining the antimitotic agent monomethyl auristatin E (MMAE), an enzymatically cleavable Val-Ala-PABC linker with a linear conjugable RGD mimetic. The structure proposal for the conjugable RGD mimetic was suggested upon the DAD mapping analysis of a previously synthesized small-molecule RGD mimetic array based on a tyrosine scaffold. Therefore, a diversifying strategy was developed as well as a novel method for the partial hydrogenation of pyrimidines in the presence of the hydrogenolytically cleavable Cbz group. The small-molecule RGD mimetics were evaluated in an ELISA-like assay, and the structural relationships were analyzed by DAD mapping revealing activity differences induced by structural changes as visualized in dependence on special structural motifs. This provided a lead structure for generation of an SMDC containing the antimitotic drug MMAE. The resulting SMDC containing a linear RGD mimetic was tested in a cell adhesion and an in vitro cell viability assay in comparison to reference SMDCs containing cRGDfK or cRADfK as the homing device. The linear RGD SMDC and the cRGDfK SMDC inhibited adhesion of α_Vβ₃-positive WM115 cells to vitronectin with IC₅₀ values in the low µM range, while no effect was observed for the α_Vβ₃-negative M21-L cell line. The cRADfK SMDC used as a negative control was about 30-fold less active in the cell adhesion assay than the cRGDfK SMDC. Conversely, both the linear RGD SMDC and the cRGDfK SMDC are about 55-fold less cytotoxic than MMAE against the α_Vβ₃-positive WM115 cell line with IC50 values in the nM range, while the cRADfK SMDC is 150-fold less cytotoxic than MMAE. Hence, integrin binding also influences the antiproliferative activity giving a targeting index of 2.8.

Targeting HIF1-alpha/miR-326/ITGA5 axis potentiates chemotherapy response in triple-negative breast cancer

PURPOSE

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer that is frequently treated with chemotherapy. However, many patients exhibit either de novo chemoresistance or ultimately develop resistance to chemotherapy, leading to significantly high mortality rates. Therefore, increasing the efficacy of chemotherapy has potential to improve patient outcomes.

METHODS

Here, we performed whole transcriptome sequencing (both RNA and small RNA-sequencing), coupled with network simulations and patient survival data analyses to build a novel miRNA-mRNA interaction network governing chemoresistance in TNBC. We performed cell proliferation assay, Western blotting, RNAi/miRNA mimic experiments, FN coating, 3D cultures, and ChIP assays to validate the interactions in the network, and their functional roles in chemoresistance. We developed xenograft models to test the therapeutic potential of the identified key miRNA/proteins in potentiating chemoresponse in vivo. We also analyzed several patient datasets to evaluate the clinical relevance of our findings.

RESULTS

We identified fibronectin (FN1) as a central chemoresistance driver gene. Overexpressing miR-326 reversed FN1-driven chemoresistance by targeting FN1 receptor, ITGA5. miR-326 was downregulated by increased hypoxia/HIF1A and ECM stiffness in chemoresistant tumors, leading to upregulation of ITGA5 and activation of the downstream FAK/Src signaling pathways. Overexpression of miR-326 or inhibition of ITGA5 overcame FN1-driven chemotherapy resistance in vitro by inhibiting FAK/Src pathway and potentiated the efficacy of chemotherapy in vivo. Importantly, lower expression of miR-326 or higher levels of predicted miR-326 target genes was significantly associated with worse overall survival in chemotherapy-treated TNBC patients.

CONCLUSION

FN1 is central in chemoresistance. In chemoresistant tumors, hypoxia and resulting ECM stiffness repress the expression of the tumor suppressor miRNA, miR-326. Hence, re-expression of miR-326 or inhibition of its target ITGA5 reverses FN1-driven chemoresistance making them attractive therapeutic approaches to enhance chemotherapy response in TNBCs.

Site-specific N-glycan profiles of α5 β1 integrin from rat liver

BACKGROUND INFORMATION

Like most other cell surface proteins, α₅ β₁ integrin is glycosylated, which is required for its various activities in ways that mostly remain to be determined.

RESULTS

Here, we have established the first comprehensive site-specific glycan map of α₅ β₁ integrin that was purified from a natural source, i.e., rat liver. This analysis revealed striking site selective variations in glycan composition. Complex bi, tri or tetraantennary N-glycans were predominant at various proportions at most potential N-glycosylation sites. A few of these sites were non-glycosylated or contained high mannose or hybrid glycans, indicating that early N-glycan processing was hindered. Almost all complex N-glycans had fully galactosylated and sialylated antennae. Moderate levels of core fucosylation and high levels of O-acetylation of NeuAc residues were observed at certain sites. An O-linked HexNAc was found in an EGF-like domain of β₁ integrin. The extensive glycan information that results from our study was projected onto a map of α₅ β₁ integrin that was obtained by homology modeling. We have used this model for the discussion of how glycosylation might be used in the functional cycle of α₅ β₁ integrin. A striking example concerns the involvement of glycan-binding galectins in the regulation of the molecular homeostasis of glycoproteins at the cell surface through the formation of lattices or endocytic pits according to the glycolipid-lectin (GL-Lect) hypothesis.

CONCLUSION

We expect that the glycoproteomics data of the current study will serve as a resource for the exploration of structural mechanisms by which glycans control α₅ β₁ integrin activity and endocytic trafficking.

SIGNIFICANCE

Glycosylation of α₅ β₁ integrin has been implicated in multiple aspects of integrin function and structure. Yet, detailed knowledge of its glycosylation, notably the specific sites of glycosylation, is lacking. Furthermore, the α₅ β₁ integrin preparation that was analyzed here is from a natural source, which is of importance as there is not a lot of literature in the field about the glycosylation of 'native' glycoproteins. This article is protected by copyright. All rights reserved.

Time-extended exposure of gastric epithelial cells to secretome of Helicobacter pylori-activated fibroblasts induces reprogramming of gastric epithelium towards pre-cancerogenic and pro-invasive phenotype

Despite of the improvement in gastric cancer (GC) therapies patients still suffer from cancer recurrence and metastasis. Recently, the high ratio of these events combined with increased chemoresistance has been related to the asymptomatic Helicobacter pylori (Hp) infections. The limited efficiency of GC treatment strategies is also increasingly attributed to the activity of tumor stroma with the key role of cancer-associated fibroblasts (CAFs). In order to investigate the influence of Hp infection within stromal gastric tissue on cancer initiation and progression, we have exposed normal gastric epithelial cells to long-term influence of Hp-activated gastric fibroblast secretome. We have referred obtained results to this secretome influence on cancer cell lines. The invasive properties of cells were checked by time-lapse video microscopy and basement membrane assays. The expression of invasion-related factors was checked by RT-PCR, Western Blot, immunofluorescence and Elisa. Hp-activated gastric fibroblast secretome induced EMT type 3-related shifts of RGM1 cell phenotype; in particular it augmented their motility, cytoskeletal plasticity and invasiveness. These effects were accompanied by Snail1/Twist activation, the up-regulation of cytokeratin19/FAP/TNC/Integrin-β1 and MMPs, and by the induction of cMet^high/pEGFR^high phenotype. Mechanistic studies suggest that this microevolution next to TGFβ relies also on c-Met/EGFR signaling interplay and engages HGF-Integrin-Ras-dependent Twist activation leading to MMP and TNC upregulation with subsequent positive auto- and paracrine feedback loops intensifying this process. Similar shifts were detected in cancer cells exposed to this secretome. Collectively, we show that the secretome of Hp-infected fibroblasts induces reprogramming/microevolution of epithelial and cancer cells towards type 3 EMT-related invasive phenotype in a manner reciprocally reliant next to TGFβ on cMet/Integrin-β1/p-EGFR-dependent axis. Apparently, the phenotypical plasticity of Hp-activated fibroblast reprogrammed gastric epithelial cells determines their susceptibility to the pro-invasive signaling, which results in re-organization of gastric niches and provides the cues for GC promotion/progression.

Active targeting via ligand-anchored pH-responsive strontium nanoparticles for efficient nucleic acid delivery into breast cancer cells

Purpose

Gene therapy is a promising and novel therapeutic strategy for many mutated gene-associated diseases, including breast cancer. However, it poses significant biological drawbacks such as rapid clearance from the circulatory system and low cellular uptake of the exogenously delivered functional nucleic acids. The development of efficient and biocompatible carriers for genetic materials has been extensively explored in the literature, and the functionalization of nanoparticles (NPs) with cancer cell-recognizing ligands has become an attractive approach to promote tumor targetability and efficient cellular internalization via endocytosis.

Methods

This study introduced self-assembling targeting ligands, including transferrin and fibronectin with the ability to electrostatically interact with strontium nanoparticles (SNPs), and then analyzed their influence on size and zeta potential of the resultant hybrid SNPs, cellular uptake and expression efficiency of transgene-loaded hybrid NPs.

Results

Smaller ligand-coated SNPs (LCSNPs) remarkably increased gene transfection activity in both MCF-7 and 4T1 cells as well as nucleic acid localization into tumor tissues with improved tumor regression activity in a 4T1-tumor xenograft mouse model.

Conclusion

LCSNPs-mediated delivery of p53 gene and MAPK siRNA provided a proof-of-concept for the functionalized nanocarrier formulation in order to inhibit breast cancer cell growth.

Temozolomide-Acquired Resistance Is Associated with Modulation of the Integrin Repertoire in Glioblastoma, Impact of α5β1 Integrin

Despite extensive treatment, glioblastoma inevitably recurs, leading to an overall survival of around 16 months. Understanding why and how tumours resist to radio/chemotherapies is crucial to overcome this unmet oncological challenge. Primary and acquired resistance to Temozolomide (TMZ), the standard-of-care chemotherapeutic drug, have been the subjects of several studies. This work aimed to evaluate molecular and phenotypic changes occurring during and after TMZ treatment in a glioblastoma cell model, the U87MG. These initially TMZ-sensitive cells acquire long-lasting resistance even after removal of the drug. Transcriptomic analysis revealed that profound changes occurred between parental and resistant cells, particularly at the level of the integrin repertoire. Focusing on α5β1 integrin, which we proposed earlier as a glioblastoma therapeutic target, we demonstrated that its expression was decreased in the presence of TMZ but restored after removal of the drug. In this glioblastoma model of recurrence, α5β1 integrin plays an important role in the proliferation and migration of tumoral cells. We also demonstrated that reactivating p53 by MDM2 inhibitors concomitantly with the inhibition of this integrin in recurrent cells may overcome the TMZ resistance. Our results may explain some integrin-based targeted therapy failure as integrin expressions are highly switchable during the time of treatment. We also propose an alternative way to alter the viability of recurrent glioblastoma cells expressing a high level of α5β1 integrin.

Interaction between Sars-CoV-2 structural proteins and host cellular receptors: From basic mechanisms to clinical perspectives

Severe acute respiratory syndrome coronavirus 2 (Sars-CoV-2) has caused a global pandemic that has affected the lives of billions of individuals. Sars-CoV-2 primarily infects human cells by binding of the viral spike protein to angiotensin-converting enzyme 2 (ACE2). In addition, novel means of viral entry are currently being investigated, including Neuropillin 1, toll-like receptors (TLRs), cluster of differentiation 147 (CD147), and integrin α5β1. Enriched expression of these proteins across metabolic regulatory organs/tissues, including the circulatory system, liver, pancreas, and intestine contributes to major clinical complications among COVID-19 patients, particularly the development of hypertension, myocardial injury, arrhythmia, acute coronary syndrome and increased coagulation in the circulatory system during and post-infection. Pre-existing metabolic disease, such as cardiovascular disease, obesity, diabetes, and non-alcoholic fatty liver disease, is associated with increased risk of hospitalization, persistent post-infection complications and worse outcomes in patients with COVID-19. This review overviews the biological features of Sars-CoV-2, highlights recent findings that delineate the pathological mechanisms of COVID-19 and the consequent clinical diseases.

Pancreatic Cancer and Cellular Senescence: Tumor Microenvironment under the Spotlight

Pancreatic ductal adenocarcinoma (PDAC) has one of the most dismal prognoses of all cancers due to its late manifestation and resistance to current therapies. Accumulating evidence has suggested that the malignant behavior of this cancer is mainly influenced by the associated strongly immunosuppressive, desmoplastic microenvironment and by the relatively low mutational burden. PDAC develops and progresses through a multi-step process. Early in tumorigenesis, cancer cells must evade the effects of cellular senescence, which slows proliferation and promotes the immune-mediated elimination of pre-malignant cells. The role of senescence as a tumor suppressor has been well-established; however, recent evidence has revealed novel pro-tumorigenic paracrine functions of senescent cells towards their microenvironment. Understanding the interactions between tumors and their microenvironment is a growing research field, with evidence having been provided that non-tumoral cells composing the tumor microenvironment (TME) influence tumor proliferation, metabolism, cell death, and therapeutic resistance. Simultaneously, cancer cells shape a tumor-supportive and immunosuppressive environment, influencing both non-tumoral neighboring and distant cells. The overall intention of this review is to provide an overview of the interplay that occurs between senescent and non-senescent cell types and to describe how such interplay may have an impact on PDAC progression. Specifically, the effects and the molecular changes occurring in non-cancerous cells during senescence, and how these may contribute to a tumor-permissive microenvironment, will be discussed. Finally, senescence targeting strategies will be briefly introduced, highlighting their potential in the treatment of PDAC.

Decidua Parietalis Mesenchymal Stem/Stromal Cells and Their Secretome Diminish the Oncogenic Properties of MDA231 Cells In Vitro

Mesenchymal stem cells (MSCs) have been shown to suppress tumor growth, inhibit angiogenesis, regulate cellular signaling, and induce apoptosis in cancer cells. We have earlier reported that placenta-derived decidua parietalis mesenchymal stem/stromal cells (DPMSCs) not only retained their functional characteristics in the cancer microenvironment but also exhibited increased expression of anti-apoptotic genes, demonstrating their anti-tumor properties in the tumor setting. In this study, we have further evaluated the effects of DPMSCs on the functional outcome of human breast cancer cell line MDA231. MDA231 cells were exposed to DPMSCs, and their biological functions, including adhesion, proliferation, migration, and invasion, were evaluated. In addition, genomic and proteomic modifications of the MDA231 cell line, in response to the DPMSCs, were also evaluated. MDA231 cells exhibited a significant reduction in proliferation, migration, and invasion potential after their treatment with DPMSCs. Furthermore, DPMSC treatment diminished the angiogenic potential of MDA231 cells. DPMSC treatment modulated the expression of various pro-apoptotic as well as oncogenes in MDA231 cells. The properties of DPMSCs to inhibit the invasive characteristics of MDA231 cells demonstrate that they may be a useful candidate in a stem-cell-based therapy against cancer.

RGD engineered dendrimer nanotherapeutic as an emerging targeted approach in cancer therapy

A bird's eye view is now demanded in the area of cancer research to suppress the suffering of cancer patient and mediate the lack of treatment related to chemotherapy. Chemotherapy is always preferred over surgery or radiation therapy, but they never met the patient's demand of safe medication. Targeted therapy has now been in research that could hinder the unnecessary effect of drug on normal cells but could affect the tumor cells in much efficient manner. Angiogenesis is process involved in development of new blood vessel that nourishes tumor growth. Integrin receptors are over expressed on cancer cells that play vital role in angiogenesis for growth and metastasis of tumor cell. A delivery of RGD based peptide to integrin targeted site could help in its successful binding and liberation of drug in tumor vasculature. Dendrimers, in addition to its excellent pharmacokinetic properties also helps to carry targeting ligand to site of tumor by successfully conjugating with them. The aim of this review is to bring light upon the role of integrin in cancer progression, interaction of RGD to integrin receptor and more importantly the RGD-dendrimer based targeted therapy for the treatment of various cancers.

Exposure to Bacteriophages T4 and M13 Increases Integrin Gene Expression and Impairs Migration of Human PC-3 Prostate Cancer Cells

The interaction between bacteriophages and integrins has been reported in different cancer cell lines, and efforts have been undertaken to understand these interactions in tumor cells along with their possible role in gene alterations, with the aim to develop new cancer therapies. Here, we report that the non-specific interaction of T4 and M13 bacteriophages with human PC-3 cells results in differential migration and varied expression of different integrins. PC-3 tumor cells (at 70% confluence) were exposed to 1 × 10⁷ pfu/mL of either lytic T4 bacteriophage or filamentous M13 bacteriophage. After 24 h of exposure, cells were processed for a histochemical analysis, wound-healing migration assay, and gene expression profile using quantitative real-time PCR (qPCR). qPCR was performed to analyze the expression profiles of integrins ITGAV, ITGA5, ITGB1, ITGB3, and ITGB5. Our findings revealed that PC-3 cells interacted with T4 and M13 bacteriophages, with significant upregulation of ITGAV, ITGA5, ITGB3, ITGB5 genes after phage exposure. PC-3 cells also exhibited reduced migration activity when exposed to either T4 or M13 phages. These results suggest that wildtype bacteriophages interact non-specifically with PC-3 cells, thereby modulating the expression of integrin genes and affecting cell migration. Therefore, bacteriophages have future potential applications in anticancer therapies.

Integrins as attractive targets for cancer therapeutics

Integrins are transmembrane receptors that have been implicated in the biology of various human physiological and pathological processes. These molecules facilitate cell–extracellular matrix and cell–cell interactions, and they have been implicated in fibrosis, inflammation, thrombosis, and tumor metastasis. The role of integrins in tumor progression makes them promising targets for cancer treatment, and certain integrin antagonists, such as antibodies and synthetic peptides, have been effectively utilized in the clinic for cancer therapy. Here, we discuss the evidence and knowledge on the contribution of integrins to cancer biology. Furthermore, we summarize the clinical attempts targeting this family in anti-cancer therapy development.

Integrin α5 mediates intrinsic cisplatin resistance in three-dimensional nasopharyngeal carcinoma spheroids via the inhibition of phosphorylated ERK /caspase-3 induced apoptosis

Nasopharyngeal carcinoma (NPC) originates in the nasopharynx epithelium. Although concurrent chemoradiation therapy followed by chemotherapy is considered as an effective treatment, there is substantial drug resistance in locally advanced NPC patients. One major contributor to the chemoresistance includes aberrant expression of cell adhesion molecules, such as integrin α and β subunits, giving rise to cell adhesion-mediated drug resistance. Thus, the aim of this study was to investigate the effect of integrin α5 on the development of intrinsic cisplatin resistance in NPC and the associated underlying mechanisms using in vitro three-dimensional (3D) spheroid models, as well as induced cisplatin-resistant NPC (NPCcisR). We demonstrated that established 3D highly- (5-8F) and lowly- (6-10B) metastatic NPC spheroids overexpressed integrin α5 and aggravated their resistance to cisplatin. Besides, enhanced integrin α5 resulted in substantially reduced growth, corresponding to G₀/G₁ and G₂/M cell cycle arrest. In addition, 5-8FcisR and 6-10BcisR cells in 3D forms synergistically strengthened endurance of their spheroids to cisplatin treatment as observed by increased resistance index (RI) and decreased apoptosis. Mechanistically, the aberrantly expressed integrin α5 decreased drug susceptibility in NPC spheroids by inactivating ERK and inhibition of caspase-3 inducing apoptosis. Furthermore, the effect of integrin α5 inducing intrinsic resistance was verified via treatment with ATN-161, a peptide inhibitor for integrin α5β1. The results showed dramatic reduction in integrin α5 expression, reversal of ERK phosphorylation and caspase-3 cleavage, together with elevated cisplatin sensitivity, indicating regulation of innate drug resistance via integrin α5. Taken together, our findings suggest that integrin α5 could act as a promising target to enhance the chemotherapeutic sensitivity in NPC.

Characteristics of Natural Killer Cell Interaction with Trophoblast Cells During Pregnancy

BACKGROUND

Maternal natural killer cells (NK cells) are a prevailing leukocyte population in the uteroplacental bed. Current descriptions of the effect of cytokines from the placental microenvironment on the expression of receptors by trophoblast and NK cells are inadequate and contradictory. There is insufficient information about the ability of NK cells to migrate through trophoblast cells.

OBJECTIVE

To assess the impact of conditioned media obtained during culturing of placentas from the first and the third trimesters of healthy pregnancies on the phenotype of trophoblast and NK cells and impact on adhesion and transmigration of NK cells through trophoblast cell layer.

RESULTS

We established that conditioned media obtained from both first and third trimester placentas increased the intensity of CD106, CD49e, CD49a, CD31, CD51/61, and integrin β6 expression by trophoblast cells. Conditioned media obtained from first trimester placentas increased the intensity of CD11a, CD29, CD49d, CD58, CD29 expression by NK cells. The presence of conditioned media from third trimester placentas resulted in more intense CD29, CD49d, CD11a, CD29, CD49d, and CD58 expression by NK cells. Migration of NK cells through trophoblast cells in the presence of conditioned media from first trimester placentas was increased compared with the migration level in the presence of conditioned media from third trimester placentas. This may be associated with increased expression of CD18 by NK cells.

CONCLUSION

First trimester placental secretory products increase adhesion receptor expression by both trophoblast and NK cells. Under these conditions, trophoblast is capable of ensuring NK cell adhesion and transmigration.

Angiopoietin-like protein 2 decreases peritoneal metastasis of ovarian cancer cells by suppressing anoikis resistance

Peritoneal metastasis is a common mode of spread of ovarian cancer. Despite therapeutic advances, some patients have intractable peritoneal metastasis. Therefore, in-depth characterization of the molecular mechanism of peritoneal metastasis is a key imperative. Angiopoietin-like protein 2 (ANGPTL2) is an inflammatory factor which activates NF-κB signaling and plays an important role in the pathogenesis of various inflammatory diseases including cancers, such as lung and breast cancer. In this study, we examined the role of ANGPTL2 in ovarian cancer peritoneal metastasis. We observed no difference of cell proliferation between ANGPTL2-expressing and control cells. In the mouse intraperitoneal xenograft model, formation of peritoneal metastasis by ANGPTL2-expressing cells was significantly decreased compared to control. In the in vitro analysis, the expressions of integrin α5β1, α6, and β4, but not those of αvβ3, α3, α4, and β1, were significantly decreased in ANGPTL2-expressing cells compared to control cells. ANGPTL2-expressing cells showed significantly inhibited adherence to laminin compared to control. In addition, we observed upregulation of anoikis (a form of programmed cell death occurring under an anchorage-independent condition) and significant decrease in the expression of Bcl-2 in ANGPTL2-expressing cells as compared to control cells. These results suggest that ANGPTL2 expression in ovarian cancer cells represses peritoneal metastasis by suppressing anoikis resistance.

Structural insights into integrin α5β1 opening by fibronectin ligand

Integrin α₅β₁ is a major fibronectin receptor critical for cell migration. Upon complex formation, fibronectin and α₅β₁ undergo conformational changes. While this is key for cell-tissue connections, its mechanism is unknown. Here, we report cryo-electron microscopy structures of native human α₅β₁ with fibronectin to 3.1-angstrom resolution, and in its resting state to 4.6-angstrom resolution. The α₅β₁-fibronectin complex revealed simultaneous interactions at the arginine-glycine-aspartate loop, the synergy site, and a newly identified binding site proximal to adjacent to metal ion-dependent adhesion site, inducing the translocation of helix α1 to secure integrin opening. Resting α₅β₁ adopts an incompletely bent conformation, challenging the model of integrin sharp bending inhibiting ligand binding. Our biochemical and structural analyses showed that affinity of α₅β₁ for fibronectin is increased with manganese ions (Mn²⁺) while adopting the half-bent conformation, indicating that ligand-binding affinity does not depend on conformation, and α₅β₁ opening is induced by ligand-binding.