Correlation between the tumoral expression of beta3-integrin and outcome in cervical cancer patients who had undergone radiotherapy

Expression of integrin αvβ3 in medullary thyroid carcinoma

Aim: Tumor markers often remain elevated after intended curative resection of medullary thyroid carcinoma (MTC). The aim of this study was to determine the expression of αvβ3, a promising theranostics target, in MTC and its metastases.Materials & methods: Avβ3 expression was analyzed in 104 patients using a tissue microarray and correlated with clinicopathological variables and survival.Results: Cytoplasmic αvβ3 positivity was seen in 70 patients and was associated with lymph node metastases at time of initial surgery. Membranous positivity was considered positive in 30 patients and was associated with sporadic MTC.Conclusion: Avβ3 was expressed in the cytoplasm of 67% of MTC patients. Membranous expression, which is presumably most relevant for the theranostic use of αvβ3, was seen in 29%.

The Role of αvβ3 Integrin in Cancer Therapy Resistance

A relevant challenge for the treatment of patients with neoplasia is the development of resistance to chemo-, immune-, and radiotherapies. Although the causes of therapy resistance are poorly understood, evidence suggests it relies on compensatory mechanisms that cells develop to replace specific intracellular signaling that should be inactive after pharmacological inhibition. One such mechanism involves integrins, membrane receptors that connect cells to the extracellular matrix and have a crucial role in cell migration. The blockage of one specific type of integrin is frequently compensated by the overexpression of another integrin dimer, generally supporting cell adhesion and migration. In particular, integrin αvβ3 is a key receptor involved in tumor resistance to treatments with tyrosine kinase inhibitors, immune checkpoint inhibitors, and radiotherapy; however, the specific inhibition of the αvβ3 integrin is not enough to avoid tumor relapse. Here, we review the role of integrin αvβ3 in tumor resistance to therapy and the mechanisms that have been proposed thus far. Despite our focus on the αvβ3 integrin, it is important to note that other integrins have also been implicated in drug resistance and that the collaborative action between these receptors should not be neglected.

Impact of PET/CT Imaging with FDG in Locally Advanced Cervical Carcinoma-A Literature Review

Positron emission tomography (PET) and computed tomography (CT) have evolved as a pivotal diagnostic modality in the field of oncology. With its increasing application in staging and ready availability, it becomes imperative for committed radiation oncologists to possess a complete analysis and understanding of integration of molecular imaging, which can be helpful for radiation planning, while also acknowledging its possible limitations and challenges. A significant obstacle lies in the synthesis and design of tumor-specific bmolecules for diagnosing and treating cancer. The utilization of radiation in medical biochemistry and biotechnology, encompassing diagnosis, therapy, and control of biological systems, is encapsulated under the umbrella term "nuclear medicine". Notably, the application of various radioisotopes in pharmaceutics has garnered significant attention, particularly in the realm of delivery systems for drugs, DNA, and imaging agents. The present article provides a comprehensive review of use of novel techniques PET and CT with major positron-emitting radiopharmaceuticals currently in progress or utilized in clinical practice with their integration into imaging and radiation therapy.

Lipid polymer hybrid nanoparticles: a custom-tailored next-generation approach for cancer therapeutics

Lipid-based polymeric nanoparticles are the highly popular carrier systems for cancer drug therapy. But presently, detailed investigations have revealed their flaws as drug delivery carriers. Lipid polymer hybrid nanoparticles (LPHNPs) are advanced core-shell nanoconstructs with a polymeric core region enclosed by a lipidic layer, presumed to be derived from both liposomes and polymeric nanounits. This unique concept is of utmost importance as a combinable drug delivery platform in oncology due to its dual structured character. To add advantage and restrict one's limitation by other, LPHNPs have been designed so to gain number of advantages such as stability, high loading of cargo, increased biocompatibility, rate-limiting controlled release, and elevated drug half-lives as well as therapeutic effectiveness while minimizing their drawbacks. The outer shell, in particular, can be functionalized in a variety of ways with stimuli-responsive moieties and ligands to provide intelligent holding and for active targeting of antineoplastic medicines, transport of genes, and theragnostic. This review comprehensively provides insight into recent substantial advancements in developing strategies for treating various cancer using LPHNPs. The bioactivity assessment factors have also been highlighted with a discussion of LPHNPs future clinical prospects.

Integrin alpha 2 is associated with tumor progression and postoperative recurrence in non-small cell lung cancer

BACKGROUND

Integrins are transmembrane proteins that mediate cell adhesion to extracellular matrix. Whereas expression of integrin alpha 2 is associated with motility, invasiveness and cellular differentiation in various tumors, the role of integrin alpha 2 in lung cancer has not been studied in detail. The aim of this study was to determine whether and how aberrant integrin alpha 2 expression in non-small cell lung cancer leads to different outcomes.

METHODS

We measured expression of integrin alpha 2 by quantitative polymerase chain reaction in 100 samples collected from non-small cell lung cancer patients who had undergone surgical resection. We assigned patients to high and low expression groups and analyzed survival. Cellular morphology, adhesion, proliferation, migration and invasion were examined in human lung cancer cell lines.

RESULTS

Among 100 cases, 41 were female, with a median age of 71 years. High expression of integrin alpha 2 in non-small cell lung cancer was associated with lower recurrence-free survival (P = 0.004). Overexpression of integrin alpha 2 in cell lines had no effect on cell proliferation or invasion but resulted in increased cell size (1416 μm2 versus 470 μm2 in H522 cells, P < 0.001; 1822 μm2 versus 1029 μm2 in H661 cells, P = 0.02), adhesion (P < 0.001 in H522 and H661 cells) and migration (gap area filled was 71% versus 36% in H522 cells, P < 0.001; 57% versus 26% in H661 cells, P = 0.001). These changes were suppressed by E7820, an inhibitor of integrin alpha 2.

CONCLUSIONS

Integrin alpha 2 may play a significant role in lung cancer adhesion and migration, and may lead to a higher risk of recurrence.

A Small Molecule–Drug Conjugate (SMDC) Consisting of a Modified Camptothecin Payload Linked to an αVß3 Binder for the Treatment of Multiple Cancer Types

To improve tumor selectivity of cytotoxic agents, we designed VIP236, a small molecule–drug conjugate consisting of an αVβ3 integrin binder linked to a modified camptothecin payload (VIP126), which is released by the enzyme neutrophil elastase (NE) in the tumor microenvironment (TME). The tumor targeting and pharmacokinetics of VIP236 were studied in tumor-bearing mice by in vivo near-infrared imaging and by analyzing tumor and plasma samples. The efficacy of VIP236 was investigated in a panel of cancer cell lines in vitro, and in MX-1, NCI-H69, and SW480 murine xenograft models. Imaging studies with the αVβ3 binder demonstrated efficient tumor targeting. Administration of VIP126 via VIP236 resulted in a 10-fold improvement in the tumor/plasma ratio of VIP126 compared with VIP126 administered alone. Unlike SN38, VIP126 is not a substrate of P-gp and BCRP drug transporters. VIP236 presented strong cytotoxic activity in the presence of NE. VIP236 treatment resulted in tumor regressions and very good tolerability in all in vivo models tested. VIP236 represents a novel approach for delivering a potent cytotoxic agent by utilizing αVβ3 as a targeting moiety and NE in the TME to release the VIP126 payload—designed for high permeability and low efflux—directly into the tumor stroma.

The Extracellular Matrix in Soft Tissue Sarcomas: Pathobiology and Cellular Signalling

Soft tissue sarcomas are rare cancers of mesenchymal origin or differentiation comprising over 70 different histological subtypes. Due to their mesenchymal differentiation, sarcomas are thought to produce and deposit large quantities of extracellular matrix (ECM) components. Interactions between ECM ligands and their corresponding adhesion receptors such as the integrins and the discoidin domain receptors play key roles in driving many fundamental oncogenic processes including uncontrolled proliferation, cellular invasion and altered metabolism. In this review, we focus on emerging studies that describe the key ECM components commonly found in soft tissue sarcomas and discuss preclinical and clinical evidence outlining the important role that these proteins and their cognate adhesion receptors play in sarcomagenesis. We conclude by providing a perspective on the need for more comprehensive in-depth analyses of both the ECM and adhesion receptor biology in multiple histological subtypes in order to identify new drug targets and prognostic biomarkers for this group of rare diseases of unmet need.

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.

Integrins Within the Tumor Microenvironment: Biological Functions, Importance for Molecular Targeting, and Cancer Therapeutics Innovation

Many cellular functions important for solid tumor initiation and progression are mediated by members of the integrin family, a diverse family of cell attachment receptors. With recent studies emphasizing the role of the tumor microenvironment (TME) in tumor initiation and progression, it is not surprising that considerable attention is being paid to integrins. Several integrin antagonists are under clinical trials, with many demonstrating promising activity in patients with different cancers. A deeper knowledge of the functions of integrins within the TME is still required and might lead to better inhibitors being discovered. Integrin expression is commonly dysregulated in many tumors with integrins playing key roles in signaling as well as promotion of tumor cell invasion and migration. Integrins also play a major role in adhesion of circulating tumor cells to new sites and the resulting formation of secondary tumors. Furthermore, integrins have demonstrated the ability to promoting stem cell-like properties in tumor cells as well as drug resistance. Anti-integrin therapies rely heavily on the doses or concentrations used as these determine whether the drugs act as antagonists or as integrin agonists. This expert review offers the latest synthesis in terms of the current knowledge of integrins functions within the TME and as potential molecular targets for cancer therapeutics innovation.

Dysregulation of Stemness Pathways in HPV Mediated Cervical Malignant Transformation Identifies Potential Oncotherapy Targets

Human papillomavirus (HPV) infection is associated with a range of malignancies that affect anogenital and oropharyngeal sites. α-HPVs dominantly infect basal epithelial cells of mucosal tissues, where they dysregulate cell division and local immunity. The cervix is one of the mucosal sites most susceptible to HPV infections. It consists of anatomically diverse regions, and the majority of cervical intraepithelial neoplasia and cancers arise within the cervical squamo-columnar junction where undifferentiated basal progenitor cells with stem cell properties are found. The cancer stem cell theory particularly associates tumorigenesis, invasion, dissemination, and metastasis with cancer cells exhibiting stem cell properties. In this perspective, we discuss evidence of a cervical cancer stem cell niche and explore the association of stemness related genes with 5-year survival using a publicly available transcriptomic dataset of a cervical cancer cohort. We report that poor prognosis in this cohort correlates with overexpression of a subset of stemness pathway genes, a majority of which regulate the central Focal Adhesion pathway, and are also found to be enriched in the HPV infection pathway. These observations support therapeutic targeting of stemness genes overexpressed by mucosal cells infected with high-risk HPVs.

Interactions Between Tumor Biology and Targeted Nanoplatforms for Imaging Applications

Although considerable efforts have been conducted to diagnose, improve, and treat cancer in the past few decades, existing therapeutic options are insufficient, as mortality and morbidity rates remain high. Perhaps the best hope for substantial improvement lies in early detection. Recent advances in nanotechnology are expected to increase the current understanding of tumor biology, and will allow nanomaterials to be used for targeting and imaging both in vitro and in vivo experimental models. Owing to their intrinsic physicochemical characteristics, nanostructures (NSs) are valuable tools that have received much attention in nanoimaging. Consequently, rationally designed NSs have been successfully employed in cancer imaging for targeting cancer-specific or cancer-associated molecules and pathways. This review categorizes imaging and targeting approaches according to cancer type, and also highlights some new safe approaches involving membrane-coated nanoparticles, tumor cell-derived extracellular vesicles, circulating tumor cells, cell-free DNAs, and cancer stem cells in the hope of developing more precise targeting and multifunctional nanotechnology-based imaging probes in the future.

High Expression of Integrin α3 Predicts Poor Prognosis and Promotes Tumor Metastasis and Angiogenesis by Activating the c-Src/Extracellular Signal-Regulated Protein Kinase/Focal Adhesion Kinase Signaling Pathway in Cervical Cancer

Background: Cervical cancer remains a leading cause of death in women due to metastasis to distant tissues and organs. Integrins are involved in cancer metastasis. However, whether integrin α3 participates in cervical cancer metastasis is under investigation. In this study, we explored the effect and detailed mechanism through which integrin α3 regulates cervical cell migration, invasion, and angiogenesis.

Methods: First, we explored the mRNA and protein expression levels of integrin α3 in cervical cancer cell lines and tissue samples obtained from patients. After knocking down the expression of integrin α3 using shRNA, the proliferation, migration, and invasion of cervical cancer cells, as well as the possible signaling pathways involved, were investigated in vitro. In addition, tube formation, proliferation, and migration of human umbilical vein endothelial cells were tested to identify their effect on angiogenesis. Zebrafish tumor migration and nude mouse lung metastasis models were utilized for the in vivo analysis.

Results: We examined samples from 142 patients with cervical cancer and 20 normal cervixes. Integrin α3 was highly expressed in patients and predicted poor overall survival and disease-free survival. In SiHa cells, treatment with integrin α3 shRNA induced the phosphorylation of protein focal adhesion kinase and enhanced focal adhesion. These events were mediated by the activation of c-Src and extracellular signal-regulated protein kinase cascades. Consequently, integrin α3 increased the migratory ability of SiHa cells. In addition, knockdown of integrin α3 decreased the tube formation, proliferation, and migration of human umbilical vein endothelial cells, as well as the levels of matrix metalloproteinase-9, indicating its effect on angiogenesis. Stable transfection with integrin α3 shRNA reduced the migratory ability of SiHa cells in the zebrafish model and diminished lung metastasis in the xenograft mouse model.

Conclusion: Integrin α3 recruits the c-Src/extracellular signal-regulated protein kinase cascade, leading to phosphorylation of focal adhesion kinase. Moreover, it regulates focal adhesion, endowing cervical cancer cells with potentiated migratory and invasive ability, and promotes angiogenesis via matrix metalloproteinase-9. Our findings may shed light on the mechanism involved in cervical cancer metastasis and highlight integrin α3 as a candidate prognostic biomarker and therapeutic target in patients with cervical cancer.

ITGB3/CD61: a hub modulator and target in the tumor microenvironment

β3 integrin (ITGB3), also known as CD61 or GP3A, is one of the most widely studied components in the integrin family. As an adhesion receptor on the cell surface, ITGB3 participates in reprogramming tumor metabolism, shaping the stromal and immune microenvironment, facilitating epithelial to mesenchymal transition (EMT) and endothelial to mesenchymal transition (End-MT) and maintaining tumor stemness, etc. Recent studies proposed various intervention strategies against ITGB3 and have achieved promising outcomes in several types of tumor. Here, we review the adaption response and cellular crosstalk in the tumor microenvironment mediated by ITGB3, as well as its upstream and downstream signaling pathways. Lastly, we focus on the inhibitors of ITGB3, ultimately indicating that ITGB3 is a promising target in the tumor microenvironment.

Peptide-Conjugated Nanoparticles as Targeted Anti-angiogenesis Therapeutic and Diagnostic in Cancer

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Targeting angiogenesis in the microenvironment of a tumor can enable suppression of tumor angiogenesis and delivery of anticancer drugs into the tumor. Anti-angiogenesis targeted delivery systems utilizing passive targeting such as Enhanced Permeability and Retention (EPR) and specific receptor-mediated targeting (active targeting) should result in tumor-specific targeting. One targeted anti-angiogenesis approach uses peptides conjugated to nanoparticles, which can be loaded with anticancer agents. Anti-angiogenesis agents can suppress tumor angiogenesis and thereby affect tumor growth progression (tumor growth arrest), which may be further reduced with the targetdelivered anticancer agent. This review provides an update of tumor vascular targeting for therapeutic and diagnostic applications, with conventional or long-circulating nanoparticles decorated with peptides that target neovascularization (anti-angiogenesis) in the tumor microenvironment.

Integrins as A New Target for Cancer Treatment

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Despite the great progress in the development of targeted therapies for different types of cancer utilizing monoclonal antibodies (e.g., cetuximab for colorectal cancer and head and neck cancer therapy), kinase inhibitors (e.g., sorafenib for kidney cancer and gastrointestinal stromal tumours therapy), and immunomodulatory treatments (e.g., nivolumab and pembrolizumab for melanoma therapy and lung cancer therapy), there is still a need to search for new, more effective treatments.

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Integrins are responsible for intercellular adhesion and interaction with the cellular matrix. The function of integrins is related to the transduction of intracellular signals associated with adhesion, migration, cell proliferation, differentiation, and apoptosis. Molecules targeting integrins that lead to cancer cell death have been developed. The most advanced molecules studied in clinical trials are abituzumab, intetumumab and cilengitide. There are different groups of anti-integrin drugs: monoclonal antibodies (e.g., abituzumab) and other such as cilengitide, E7820 and MK-0429. These drugs have been evaluated in various cancer types. However, they have shown modest efficacy, and none of them have yet been approved for cancer treatment. Studies have shown that patient selection using biomarkers might improve the efficacy of anti-integrin cancer treatment. Many preclinical models have demonstrated promising results using integrin visualization for cancer detection and treatment efficacy monitoring; however, these strategies require further evaluation in humans.

αvβ3 Integrin Mediates Radioresistance of Prostate Cancer Cells through Regulation of Survivin

The α_vβ₃ integrin is involved in various physiologic and pathologic processes such as wound healing, angiogenesis, tumor growth, and metastasis. The impact of α_vβ₃ integrin on the radiosensitivity of prostate cancer cells and the molecular mechanism controlling cell survival in response to ionizing radiation (IR) was investigated. Both LNCaP cells stably transfected with α_vβ₃ integrin and PC-3 cells that contain endogenous β₃ integrin were used. This study demonstrated that α_vβ₃ integrin increases survival of α_vβ₃-LNCaP cells upon IR while small hairpin RNA (shRNA)-mediated knockdown of α_vβ₃ integrin in PC-3 cells sensitizes to radiation. Expression of α_vβ₃ integrin in LNCaP cells also enhances anchorage-independent cell growth while knockdown of α_vβ₃ integrin in PC-3 cells inhibits anchorage-independent cell growth. The α_vβ₃ antagonist, cRGD, significantly increases radiosensitivity in both α_vβ₃-LNCaP and PC-3 cells. Moreover, α_vβ₃ integrin prevents radiation-induced downregulation of survivin. Inhibition of survivin expression by siRNA or shRNA enhances IR-induced inhibition of anchorage-independent cell growth. Overexpression of wild-type survivin in PC-3 cells treated with α_vβ₃ integrin shRNA increases survival of cells upon IR. These findings reveal that α_vβ₃ integrin promotes radioresistance and regulates survivin levels in response to IR. IMPLICATIONS: Future translational research on targeting α_vβ₃ integrin and survivin may reveal novel approaches as an adjunct to radiotherapy for patients with prostate cancer.

Cancer-targeted delivery systems based on peptides

There is a growing interest for the discovery of new cancer-targeted delivery systems for drug delivery and diagnosis. A synopsis of the bibliographic data will be presented on bombesin, neurotensin, octreotide, Arg-Gly-Asp, luteinizing hormone-releasing hormone and other peptides. Many of them have reached the clinics for therapeutic or diagnostic purposes, and have been utilized as carriers of known cytotoxic agents such as doxorubicin, paclitaxel, cisplatin, methotrexate or dyes and radioisotopes. In our article, recent advances in the development of peptides as carriers of cytotoxic drugs or radiometals will be analyzed.

Sulfatide interacts with and activates integrin αVβ3 in human hepatocellular carcinoma cells

Integrin αVβ3 is a malignant driver of anchorage-independence and tumor angiogenesis, but its dysregulation in hepatocellular carcinoma (HCC) remains unclear. In this study, we observed that sulfatide significantly promoted integrin αV(ITGAV) expression and wound closure in HCC. We also noted that elevated sulfatide profoundly stimulated integrin αVβ3 clustering and signaling. In the cells with integrin αVβ3 clustering induced by sulfatide, integrin β3 subunit was phosphorylated. Simultaneously, focal adhesion kinase (FAK), Src and paxillin were also phosphorylated. Treatment with FAK inhibitor resulted in robust suppression of FAK-Y397 and Src-Y416 phosphorylation stimulated by sulfatide, but not suppression of integrin β3 phosphorylation. Src inhibitors repressed Src-Y416 and FAK Y861 and Y925 phosphorylation, but not FAK-Y397 and integrin β3 phosphorylation. After mutation of integrin β3 (Y773F and Y785F), FAK or Src phosphorylation failed to be stimulated by sulfatide. Moreover, β3 Y773 and Y785 phosphorylation was suppressed by insulin-like growth factor receptor knockdown even in cells stimulated by sulfatide. In assays of immunoprecipitation and immunostaining with integrin αV or β3 antibody, labeled sulfatide was found in the complex and co-localized with integrin αVβ3. Taken together, this study demonstrated that elevated sulfatide bound to integrin αVβ3 and induced clustering and phosphorylation of αVβ3 instead of matrix ligand binding, triggering outside-in signaling.

Isoprenylcysteine carboxylmethyltransferase function is essential for RAB4A-mediated integrin β3 recycling, cell migration and cancer metastasis

Isoprenylcysteine carboxylmethyltransferase (ICMT) catalyzes the post-translational modification of RAB GTPases that contain C-terminal CXC motifs. However, the functional impact of this modification on RAB proteins has not been actively explored. We found that inhibition of ICMT significantly reduced cell migration in vitro and cancer invasion and metastasis in vivo. This role of ICMT was found to be mediated by RAB4A, an essential regulator of the fast recycling of integrin β3. Integrin β3 regulates cell polarity and migration when localized appropriately to the plasma membrane, thereby having an essential role in cancer metastasis. ICMT catalyzed carboxylmethylation is critical for RAB4A activation and interaction with effectors, its localization to endosomes and recycling vesicles, and hence important for RAB4A-dependent integrin β3 recycling to plasma membrane. These findings bring attention to the effects of C-terminal carboxylmethylation on RAB GTPases and provide a rationale for targeting ICMT in the treatment of metastatic cancer.

RGD-mediated delivery of small-molecule drugs

Conjugates of cytotoxic agents with RGD peptides (Arg-Gly-Asp) addressed to α_νβ₃, α₅β₁ and α_νβ₆ integrin receptors overexpressed by cancer cells, have recently gained attention as potential selective anticancer chemotherapeutics. In this review, the design and the development of RGD conjugates coupled to different small molecules including known cytotoxic drugs and natural products will be discussed.

Alpha-enolase (ENO1) controls alpha v/beta 3 integrin expression and regulates pancreatic cancer adhesion, invasion, and metastasis

Background

We have previously shown that in pancreatic ductal adenocarcinoma (PDA) cells, the glycolytic enzyme alpha-enolase (ENO1) also acts as a plasminogen receptor and promotes invasion and metastasis formation. Moreover, ENO1 silencing in PDA cells induces oxidative stress, senescence and profoundly modifies PDA cell metabolism. Although anti-ENO1 antibody inhibits PDA cell migration and invasion, little is known about the role of ENO1 in regulating cell-cell and cell-matrix contacts. We therefore investigated the effect of ENO1 silencing on the modulation of cell morphology, adhesion to matrix substrates, cell invasiveness, and metastatic ability.

Methods

The membrane and cytoskeleton modifications that occurred in ENO1-silenced (shENO1) PDA cells were investigated by a combination of confocal microscopy and atomic force microscopy (AFM). The effect of ENO1 silencing was then evaluated by phenotypic and functional experiments to identify the role of ENO1 in adhesion, migration, and invasion, as well as in senescence and apoptosis. The experimental results were then validated in a mouse model.

Results

We observed a significant increase in the roughness of the cell membrane due to ENO1 silencing, a feature associated with an impaired ability to migrate and invade, along with a significant downregulation of proteins involved in cell-cell and cell-matrix adhesion, including alpha v/beta 3 integrin in shENO1 PDA cells. These changes impaired the ability of shENO1 cells to adhere to Collagen I and IV and Fibronectin and caused an increase in RGD-independent adhesion to vitronectin (VN) via urokinase plasminogen activator receptor (uPAR). Binding of uPAR to VN triggers integrin-mediated signals, which result in ERK1-2 and RAC activation, accumulation of ROS, and senescence. In shENO1 cancer cells, the use of an anti-uPAR antibody caused significant reduction of ROS production and senescence. Overall, a decrease of in vitro and in vivo cell migration and invasion of shENO1 PDA cells was observed.

Conclusion

These data demonstrate that ENO1 promotes PDA survival, migration, and metastasis through cooperation with integrins and uPAR.

Electronic supplementary material

The online version of this article (doi:10.1186/s13045-016-0385-8) contains supplementary material, which is available to authorized users.

Development of a novel cyclic RGD peptide for multiple targeting approaches of liposomes to tumor region

Liposomes containing cytotoxic agents and targeted with Arg-Gly-Asp based peptides have frequently been used against αvβ3 integrin on tumor neovasculature. However, like many other ligand modified liposomes these preparations suffered from enhanced uptake by the reticulo endothelial system (RES) and off-targeted interaction with integrin receptors vastly expressed in normal organs causing poor biodistribution and toxic effects. Here we mainly focus on development of a RGD-modified liposomal delivery system to enhance both targeting selectivity and tumor uptake. First, sterically stabilized liposomal doxorubicin (SSLD) prepared and decorated with cRGDfK and RGDyC peptides differ in their physical properties. Stability assessments as well as in vitro and in vivo studies revealed that increasing the peptide hydrophobicity promotes the therapeutic efficacy of RGD-SSLD in a C-26 tumor model due to decreased recognition by RES and opsonization and limited off-targeted interactions. Then a novel N-methylated RGD peptide was designed and its capability in targeting integrin presenting cells was comprehensively assessed both in vitro and in vivo. RGDf[N-methyl]C promotes the liposome internalization by HUVEC via integrin mediated endocytosis. Intravital microscopy in window chamber bearing mice illustrated the capability of RGDf[N-methyl]C-liposomes in targeting both tumor vasculature and tumor cells in murine B16F0 and human BLM tumor models. Quantitative biodistribution in mice bearing B16F0 tumor revealed its high affinity to tumor with no considerable affinity to normal organs. Treatment by high dose of RGDf[N-methyl]C-SSLD was found more effective than non-targeted SSLD and no toxic side effect was observed. In conclusion, the RGDf[N-methyl]C-liposome was found promising in targeting tumor vasculature as well as other cells inside the tumor.

Tumour but not stromal expression of β3 integrin is essential, and is required early, for spontaneous dissemination of bone-metastatic breast cancer

Although many preclinical studies have implicated β3 integrin receptors (αvβ3 and αIIbβ3) in cancer progression, β3 inhibitors have shown only modest efficacy in patients with advanced solid tumours. The limited efficacy of β3 inhibitors in patients could arise from our incomplete understanding of the precise function of β3 integrin and, consequently, inappropriate clinical application. Data from animal studies are conflicting and indicate heterogeneity with respect to the relative contributions of β3-expressing tumour and stromal cell populations in different cancers. Here we aimed to clarify the function and relative contributions to metastasis of tumour versus stromal β3 integrin in clinically relevant models of spontaneous breast cancer metastasis, with particular emphasis on bone metastasis. We show that stable down-regulation of tumour β3 integrin dramatically impairs spontaneous (but not experimental) metastasis to bone and lung without affecting primary tumour growth in the mammary gland. Unexpectedly, and in contrast to subcutaneous tumours, orthotopic tumour vascularity, growth and spontaneous metastasis were not altered in mice null for β3 integrin. Tumour β3 integrin promoted migration, protease expression and trans-endothelial migration in vitro and increased vascular dissemination in vivo, but was not necessary for bone colonization in experimental metastasis assays. We conclude that tumour, rather than stromal, β3 expression is essential and is required early for efficient spontaneous breast cancer metastasis to bone and soft tissues. Accordingly, differential gene expression analysis in cohorts of breast cancer patients showed a strong association between high β3 expression, early metastasis and shorter disease-free survival in patients with oestrogen receptor-negative tumours. We propose that β3 inhibitors may be more efficacious if used in a neoadjuvant setting, rather than after metastases are established.

Expression of integrin β1 and its significance in squamous cell carcinoma of the cervix

The aim of the present study was to examine the expression of integrin β1 in squamous cell carcinoma (SCC) of the cervix and its association with the clinicopathological features of patients. The expression of integrin β1 in 87 SCC cervical tissues and 32 normal cervical tissues was detected using an enzyme-linked immunosorbent assay, western blot analysis and the immunohistochemical streptavidin-peroxidase method. Integrin β1 expression was greater in SCC cervical tissues compared with that in normal cervical tissues (P<0.05), and its mean expression level in the SCC cervical tissues was also markedly higher compared with that in the normal cervical tissues (P<0.05). In terms of the association between the expression of integrin β1 with clinicopathological features, patients with stage IIA SCC had higher integrin β1 positive rates compared with patients with stage I SCC (P<0.05). The integrin β1 positive rates in SCC tissues with histological grade 3 were also significantly higher than that in the SCC tissues with histological grade 1 (P<0.05). Furthermore, patients with cervical SCC with lymph node metastasis showed increased integrin β1 positive expression compared with those without lymph node metastasis (P<0.05). In conclusion, the expression of integrin β1 protein in cervical SCC tissues was significantly higher than that in the normal cervical tissues, and it increased with the clinical stage and the degree of malignancy.

Photon-induced cell migration and integrin expression promoted by DNA integration of HPV16 genome

BACKGROUND

Persistent human papilloma virus 16 (HPV16) infections are a major cause of cervical cancer. The integration of the viral DNA into the host genome causes E2 gene disruption which prevents apoptosis and increases host cell motility. In cervical cancer patients, survival is limited by local infiltration and systemic dissemination. Surgical control rates are poor in cases of parametrial infiltration. In these patients, radiotherapy (RT) is administered to enhance local control. However, photon irradiation itself has been reported to increase cell motility. In cases of E2-disrupted cervical cancers, this phenomon would impose an additional risk of enhanced tumor cell motility. Here, we analyze mechanisms underlying photon-increased migration in keratinocytes with differential E2 gene status.

METHODS

Isogenic W12 (intact E2 gene status) and S12 (disrupted E2 gene status) keratinocytes were analyzed in fibronectin-based and serum-stimulated migration experiments following single photon doses of 0, 2, and 10 Gy. Quantitative FACS analyses of integrin expression were performed.

RESULTS

Migration and adhesion are increased in E2 gene-disrupted keratinocytes. E2 gene disruption promotes attractability by serum components, therefore, effectuating the risk of local infiltration and systemic dissemination. In S12 cells, migration is further increased by photon RT which leads to enhanced expression of fibronectin receptor integrins.

CONCLUSION

HPV16-associated E2 gene disruption is a main predictor of treatment-refractory cancer virulence. E2 gene disruption promotes cell motility. Following photon RT, E2-disrupted tumors bear the risk of integrin-related infiltration and dissemination.

Sine oculis homeobox homolog 1 promotes α5β1-mediated invasive migration and metastasis of cervical cancer cells

Sine oculis homeobox homolog 1 (SIX1) has been supposed to be correlated with the metastasis and poor prognosis of several malignancies. However, the effect of SIX1 on the metastatic phenotype of tumor cells and the underlying mechanisms were still unclear to date. Here we report that SIX1 can promote α5β1-mediated metastatic capability of cervical cancer cells. SIX1 promoted the expression of α5β1 integrin to enhance the adhesion capacity of tumor cells in vitro and tumor cell arrest in circulation in vivo. Moreover, higher expression of SIX1 in tumor cells resulted in the increased production of active MMP-2 and MMP-9, up-regulation of anti-apoptotic genes (BCL-XL and BCL2) and down-regulation of pro-apoptotic genes (BIM and BAX), thus promoting the invasive migration and anoikis-resistance of tumor cells. Importantly, blocking α5β1 abrogated the regulatory effect of SIX1 on the expression of these genes, and also abolished the promotional effect of SIX1 on invasive capability of tumor cells. Furthermore, knock-down of α5 could abolish the promoting effect of SIX1 on the development of metastatic lesions in both experimental and spontaneous metastasis model. Therefore, by up-regulating α5β1 expression, SIX1 not only promoted the adhesion capacity, but also augmented ECM-α5β1-mediated regulation of gene expression to enhance the metastatic potential of cervical cancer cells. These results suggest that SIX1/α5β1 might be considered as valuable marker for metastatic potential of cervical cancer cells, or a therapeutic target in cervical cancer treatment.

Multiple biomarkers in molecular oncology. I. Molecular diagnostics applications in cervical cancer detection

The screening for cervical carcinoma and its malignant precursors (cervical neoplasia) currently employs morphology-based detection methods (Papanicolaou [Pap] smear) in addition to the detection of high-risk human papillomavirus. The combination of the Pap smear with human papillomavirus testing has achieved significant improvements in sensitivity for the detection of cervical disease. Diagnosis of cervical neoplasia is dependent upon histology assessment of cervical biopsy specimens. Attempts to improve the specificity of cervical disease screening have focused on the investigation of molecular biomarkers for adjunctive use in combination with the Pap smear. Active research into the genomic and proteomic alterations that occur during human papillomavirus-induced neoplastic transformation have begun to characterize some of the basic mechanisms inherent to the disease process of cervical cancer development. This research continues to demonstrate the complexity of multiple genomic and proteomic alterations that accumulate during the tumorigenesis process. Despite this diversity, basic patterns of uncontrolled signal transduction, cell cycle deregulation, activation of DNA replication and altered extracellular matrix interactions are beginning to emerge as common features inherent to cervical cancer development. Some of these gene or protein expression alterations have been investigated as potential biomarkers for screening and diagnostics applications. The contribution of multiple gene alterations in the development of cervical cancer suggests that the application of multiple biomarker panels has the potential to develop clinically useful molecular diagnostics. In this review, the application of biomarkers for the improvement of sensitivity and specificity of the detection of cervical neoplasia within cytology specimens will be discussed.

αvβ3 Integrin and Fibroblast growth factor receptor 1 (FGFR1): Prognostic factors in a phase I-II clinical trial associating continuous administration of Tipifarnib with radiotherapy for patients with newly diagnosed glioblastoma

BACKGROUND

Based on our previous results showing the involvement of the farnesylated form of RhoB in glioblastoma radioresistance, we designed a phase II trial associating the farnesyltransferase inhibitor Tipifarnib with radiotherapy in patients with glioblastoma and studied the prognostic values of the proteins which we have previously shown control this pathway.

PATIENTS AND METHODS

Patients were treated with 200mg Tipifarnib (recommended dose (RD)) given continuously during radiotherapy. Twenty-seven patients were included in the phase II whose primary end-point was time to progression (TTP). Overall survival (OS) and biomarker analysis were secondary end-points. Expressions of αvβ3, αvβ5 integrins, FAK, ILK, fibroblast growth factor 2 (FGF2) and fibroblast growth factor receptor 1 (FGFR1) were studied by immuno-histochemistry in the tumour of the nine patients treated at the RD during the previously performed phase I and on those of the phase II patients. We evaluated the correlation of the expressions of these proteins with the clinical outcome.

RESULTS

For the phase II patients median TTP was 23.1 weeks (95%CI = [15.4; 28.2]) while the median OS was 80.3 weeks (95%CI = [57.8; 102.7]). In the pooled phase I and II population, median OS was 60.4 w (95%CI = [47.3; 97.6]) while median TTP was 18.1 w (95%CI = [16.9; 25.6]). FGFR1 over-expression (HR = 4.65; 95%CI = [1.02; 21.21], p = 0.047) was correlated with shorter TTP while FGFR1 (HR = 4.1 (95% CI = [1.09-15.4]; p = 0.036)) and αvβ3 (HR = 10.38 (95%CI = [2.70; 39.87], p = 0.001)) over-expressions were associated with reduced OS.

CONCLUSION

Association of 200mg Tipifarnib with radiotherapy shows promising OS but no increase in TTP compared to historical data. FGFR1 and αvβ3 integrin are independent bad prognostic factors of OS and TTP.

αV integrins in angiogenesis and cancer

During angiogenesis, αv integrins are overexpressed on the endothelial cell surface to facilitate the growth and survival of newly forming vessels. Accordingly, blocking αv integrin function by disrupting ligand binding can produce an antiangiogenic effect. Although the integrin ectodomain regulates ligand binding specificity, the short cytoplasmic tail facilitates intracellular signaling pathways through the recruitment and activation of specific kinases and signaling intermediates. This in turn controls endothelial cell adhesion, morphology, migration, invasion, proliferation, and survival. These same integrin-mediated signaling pathways are exploited in cancer to promote the invasiveness and survival of tumor cells and to manipulate the host microenvironment to provide ample blood vessel and stromal resources to support tumor growth and metastatic spread. Because expression of αv integrins on distinct cell types contributes to cancer growth, αv integrin antagonists have the potential to disrupt multiple aspects of disease progression.

The role of PET/CT in cervical cancer

In locally advanced cervical cancer, ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography – computed tomography (PET/CT) has become important in the initial evaluation of disease extent. It is superior to other imaging modalities for lymph node status and distant metastasis. PET-defined cervical tumor volume predicts progression-free and overall survival. Higher FDG uptake in both primary and regional lymph nodes is strongly predictive of worse outcome. FDG-PET is useful for assessing treatment response 3 months after completing concurrent chemo-radiotherapy (CRT) and predicting long-term survival, and in suspected disease recurrence. In the era of image-guided adaptive radiotherapy, accurately defining disease areas is critical to avoid irradiating normal tissue. Based on additional information provided by FDG-PET, radiation treatment volumes can be modified and higher doses to FDG-positive lymph nodes safely delivered. FDG-PET/CT has been used for image-guided brachytherapy of FDG-avid tumor volume, while respecting low doses to bladder and rectum. Despite survival improvements due to CRT in cervical cancer, disease recurrences continue to be a major problem. Biological rationale exists for combining novel non-cytotoxic agents with CRT, and drugs targeting specific molecular pathways are under clinical development. The integration of these targeted therapies in clinical trials, and the need for accurate predictors of radio-curability is essential. New molecular imaging tracers may help identifying more aggressive tumors. ⁶⁴Cu-labeled diacetyl-di(N(4)-methylthiosemicarbazone) is taken up by hypoxic tissues, which may be valuable for prognostication and radiation treatment planning. PET/CT imaging with novel radiopharmaceuticals could further impact cervical cancer treatment as surrogate markers of drug activity at the tumor microenvironment level. The present article reviews the current and emerging role of PET/CT in the management of cervical cancer.

Prognostic cell biological markers in cervical cancer patients primarily treated with (chemo)radiation: a systematic review

The aim of this study was to systematically review the prognostic and predictive significance of cell biological markers in cervical cancer patients primarily treated with (chemo)radiation. A PubMed, Embase, and Cochrane literature search was performed. Studies describing a relation between a cell biological marker and survival in ≥50 cervical cancer patients primarily treated with (chemo)radiation were selected. Study quality was assessed, and studies with a quality score of 4 or lower were excluded. Cell biological markers were clustered on biological function, and the prognostic and predictive significance of these markers was described. In total, 42 studies concerning 82 cell biological markers were included in this systematic review. In addition to cyclooxygenase-2 (COX-2) and serum squamous cell carcinoma antigen (SCC-ag) levels, markers associated with poor prognosis were involved in epidermal growth factor receptor (EGFR) signaling (EGFR and C-erbB-2) and in angiogenesis and hypoxia (carbonic anhydrase 9 and hypoxia-inducible factor-1α). Epidermal growth factor receptor and C-erbB-2 were also associated with poor response to (chemo)radiation. In conclusion, EGFR signaling is associated with poor prognosis and response to therapy in cervical cancer patients primarily treated with (chemo)radiation, whereas markers involved in angiogenesis and hypoxia, COX-2, and serum SCC-ag levels are associated with a poor prognosis. Therefore, targeting these pathways in combination with chemoradiation may improve survival in advanced-stage cervical cancer patients.

Cancer-stromal interactions: role in cell survival, metabolism and drug sensitivity

It has been known for a long time that the interaction between cancer cells and tissue microenvironment plays a major role in cancer development, progression and metastasis. The biochemical aspect of cancer-stromal interactions, however, is less appreciated. This short review article first provides a brief summary of the communications between cancer cells and the tissue microenvironment by direct cell-cell interactions and by soluble factors, and then describes several biochemical pathways that are important for the interaction between stromal and cancer cells with respect to energy metabolism, redox balance, cell survival and drug resistance. The potential therapeutic implications of abolishing stromal protective mechanisms to overcome drug resistance are also discussed.

Expression of integrins and Toll-like receptors in cervical cancer: effect of infectious agents

We hypothesized that development of cervical cancer is associated with alterations in the expression of innate immune receptors, i.e. integrins and TLRs, and that these alterations can be induced by infectious agents. We have studied the expression of these proteins in cervical biopsy tissues and cervical cancer-derived cell lines HeLa, CaSki, SiHa, C-33 A, and ME180. Immunohistochemistry analysis demonstrated an increase in integrin αv, β3, β4, and β6 expression in the epithelium during the development of cervical cancer. A clear trend towards higher expression of integrin β6 in cell lines harbouring human papillomavirus (HPV) genetic material, compared to HPV-negative C-33 A, was observed. To investigate whether bacterial infection can alter the expression of TLRs and integrins, we infected HeLa cells by two pathogens, Escherichia coli and Pseudomonas aeruginosa, using a common bacterium of the female genital tract, Lactobacillus reuteri, as a control. Infection with E. coli or P. aeruginosa, but not with L. reuteri, significantly altered the expression of TLR and integrins, particularly of TLR4 and integrin β6. Considering that both integrin β6 and TLR4 play important roles in tumorigenesis, our data suggest that bacterial infection may trigger cancer development in HPV-infected cervical epithelium.

Hypoxia, inflammation, and the tumor microenvironment in metastatic disease

Metastasis, the leading cause of cancer deaths, is an intricate process involving many important tumor and stromal proteins that have yet to be fully defined. This review discusses critical components necessary for the metastatic cascade, including hypoxia, inflammation, and the tumor microenvironment. More specifically, this review focuses on tumor cell and stroma interactions, which allow cell detachment from a primary tumor, intravasation to the blood stream, and extravasation at a distant site where cells can seed and tumor metastases can form. Central players involved in this process and discussed in this review include integrins, matrix metalloproteinases, and soluble growth factors/matrix proteins, including the connective tissue growth factor and lysyl oxidase.

Integrins in cancer: biological implications and therapeutic opportunities

The integrin family of cell adhesion receptors regulates a diverse array of cellular functions crucial to the initiation, progression and metastasis of solid tumours. The importance of integrins in several cell types that affect tumour progression has made them an appealing target for cancer therapy. Integrin antagonists, including the alphavbeta3 and alphavbeta5 inhibitor cilengitide, have shown encouraging activity in Phase II clinical trials and cilengitide is currently being tested in a Phase III trial in patients with glioblastoma. These exciting clinical developments emphasize the need to identify how integrin antagonists influence the tumour and its microenvironment.

beta1 integrin targeting to enhance radiation therapy

PURPOSE

Cell adhesion to extracellular matrix (ECM) proteins is mediated by the integrin family and has been known to modify radiation sensitivity and resistance in several cell types, including cancer cells. In particular, beta1 integrin signaling has been implicated in the progression and metastasis of various cancers and has been shown to facilitate resistance to radiation therapy.

CONCLUSION

In this mini-review, we provide a brief overview of integrin targeting in radiation therapy. We specifically focus on the updated findings of beta1 integrin-mediated signaling pathways after exposure to ionising radiation (IR) using in vitro and in vivo experimental models, which could represent promising therapeutic targets for breast cancer.

An integrin alpha(v)beta(3)-c-Src oncogenic unit promotes anchorage-independence and tumor progression

Integrins regulate adhesion-dependent growth, survival and invasion of tumor cells. In particular, expression of integrin alpha(v)beta(3) is associated with progression of a variety of human tumors. Here we reveal a previously undescribed adhesion-independent role for integrin alpha(v)beta(3) in pancreatic cancer and other carcinomas. Specifically, alpha(v)beta(3) expressed in carcinoma cells enhanced anchorage-independent tumor growth in vitro and increased lymph node metastases in vivo. These effects required recruitment of c-Src to the beta(3) integrin cytoplasmic tail, leading to c-Src activation, Crk-associated substrate (CAS) phosphorylation and tumor cell survival that, unexpectedly, was independent of cell adhesion or focal adhesion kinase (FAK) activation. Pharmacological blockade of c-Src kinase activity or decreased expression of endogenous alpha(v)beta(3) integrin or c-Src not only inhibited anchorage-independent growth but also suppressed metastasis in vivo, yet these manipulations did not affect tumor cell migration or invasion. These data define an unexpected role for an integrin as a mediator of anchorage independence, suggesting that an alpha(v)beta(3)-c-Src signaling module may account for the aggressive behavior of integrin alpha(v)beta(3)-expressing tumors in humans.

Expression order of alpha-v and beta-3 integrin subunits in the N-methyl-N-nitrosourea-induced rat mammary tumor model

We investigated the developmental time course of molecular expression of alpha(v)beta(3) subunits in a carcinogen-induced rat mammary tumor model for human ductal carcinoma in situ (DCIS). Tumors during various stages of growth (from <0.1 to >2.0 cm) were analyzed immunohistochemically for the expression of the alpha(v)beta(3) integrin and its subunits. In general, the expression profiles of these integrin subunits were directly proportional to the size of the tumor. The pattern of immunostaining revealed that anti-alpha(v)beta(3) monoclonal antibody binds to specific sites of tumor sections, forming isolated stained patches. This isolated patch pattern was found in more developed larger tumors. This could be due to the fact that the integrin molecule might be involved in migration and nesting of tumor cells into specific regions to form DCIS or intraductal carcinoma. Results also showed that the alpha(v) subunit expresses earlier than the beta(3) subunit. These data provide insight into tumor cell biology and developmental characteristics that will guide the future construction and use of targeted contrast and therapeutic agents capable of tracking, imaging, or treating a tumor at the earliest stage of formation.

The bone marrow microenvironment as a tumor sanctuary and contributor to drug resistance

The bone marrow microenvironment facilitates the survival, differentiation, and proliferation of hematopoietic cells. These cells are supported by fibroblast-like bone marrow stromal cells, osteoblasts, and osteoclasts which secrete soluble factors and extracellular matrix proteins that mediate these functions. This rich environment serves as a safe haven not only for normal and malignant hematopoietic cells, but also for epithelial tumor cells that metastasize to bone, offering protection from chemotherapeutic agents by common mechanisms. Soluble factors produced in the bone marrow, such as stromal cell-derived factor-1 and interleukin-6, mediate homing, survival, and proliferation of tumor cells, and integrin-mediated adhesion sequesters tumor cells to this protective niche. Environment-mediated drug resistance includes a combination of soluble factors and adhesion, and can be subdivided into soluble factor-mediated drug resistance and cell adhesion-mediated drug resistance. Because it is induced immediately by the microenvironment and is independent of epigenetic or genetic changes caused by the selective pressure of drug exposure, environment-mediated drug resistance is a form of de novo drug resistance. In this form of drug resistance, tumor cells are transiently and reversibly protected from apoptosis induced by both chemotherapy and physiologic mediators of cell death. This protection allows tumor cells to survive the insult of chemotherapy, leading to minimal residual disease, and thereby increases the probability for the development of acquired drug resistance.

In vivo imaging of tumour angiogenesis in mice with the alpha(v)beta (3) integrin-targeted tracer 99mTc-RAFT-RGD

PURPOSE

The molecular imaging of tumour neoangiogenesis currently represents a major field of research for the diagnostic and treatment strategy of solid tumours. Endothelial cells from tumour neovessels overexpress the alpha(v)beta(3) integrin, which selectively binds to Arg-Gly-Asp (RGD)-containing peptides. We evaluated the potential of the novel radiotracer (99m)Tc-RAFT-RGD for the non-invasive molecular imaging of alpha(v)beta(3) integrin expression in mice models of tumour development.

METHODS

(99m)Tc-RAFT-RGD, (99m)Tc-cRGD (specific control) and (99m)Tc-RAFT-RAD (non-specific control) were injected intravenously to mice bearing B16F0 or TS/A-pc tumours. In vivo whole-body tomographic imaging and post-mortem biodistribution studies were performed 60 min following tracer injection. Adjacent tumour slices were used to compare the localisation of neovessels from immunostaining and the pattern of (99m)Tc-RAFT-RGD uptake from autoradiographic ex vivo imaging.

RESULTS

Biodistribution studies indicated that (99m)Tc-RAFT-RGD tumour uptake was significantly higher than that of (99m)Tc-RAFT-RAD in B16F0 (2.4+/-0.5 vs 1.0+/-0.1%ID/g, respectively) and in TS/A-pc tumours (2.7+/-0.8 vs 0.7+/-0.1%ID/g, respectively). Immunohistochemical and autoradiographic studies indicated that (99m)Tc-RAFT-RGD intratumoural uptake preferentially occurred in angiogenic areas. Tomographic imaging allowed tumour visualisation following injection of (99m)Tc-RAFT-RGD and (99m)Tc-cRGD with similar tumour-to-contralateral muscle (T/CM) ratios in B16F0 and in TS/A-pc tumours whereas (99m)Tc-RAFT-RAD T/CM ratios did not allow tumour imaging. In accordance with the higher level of alpha(v)beta(3) integrin expression on TS/A-pc tumours than on B16F0 tumours as determined from western blot and immunoprecipitation analyses, the (99m)Tc-RAFT-RGD T/CM ratio was significantly higher in TS/A-pc than in B16F0 tumours.

CONCLUSION

(99m)Tc-RAFT-RGD allowed the in vivo imaging of alpha(v)beta(3) integrin tumour expression.

Antisense integrin alphaV and beta3 gene therapy suppresses subcutaneously implanted hepatocellular carcinomas

BACKGROUND

Integrin alphaVbeta3 plays a critical role in tumour angiogenesis and metastasis formation, and is recognized as a key therapeutic target in the treatment of cancer.

AIM

To investigate whether antisense alphaV and beta3 gene therapy has utility in the treatment of hepatocellular carcinomas.

METHODS

Antisense expression plasmids targeting integrin alphaV or beta3 were constructed, and examined by immunohistochemistry and Western blot analyses for their ability to inhibit alphaV and beta3 expression. The antisense alphaV and beta3 expression vectors, either alone or in combination, were injected into HepG2 hepatomas established subcutaneously in nude mice and tumour growth, angiogenesis and apoptosis were monitored.

RESULTS

Antisense alphaV and beta3 downregulated the alphaV and beta3 subunits expressed by human umbilical vein endothelial cells, and the alphaV subunit expressed by HepG2 cells. Gene transfer of antisense alphaV and beta3 expression vectors downregulated alphaV and beta3 in HepG2 tumours established in nude mice, inhibited tumour vascularization and growth, and enhanced tumour cell apoptosis. Antisense alphaV suppressed tumour growth more strongly than antisense beta3; however antisense therapy that simultaneously targeted both integrin subunits was more effective than the respective monotherapies. Antisense alphaV and beta3 inhibited tumour angiogenesis to similar extents, by a process that is independent of vascular endothelial growth factor.

CONCLUSIONS

Antisense gene therapy targeting alphaV integrins warrants consideration as an approach to treat hepatocellular carcinomas.

Targeting Beta-3 integrin using a linear hexapeptide labeled with a near-infrared fluorescent molecular probe

Biomolecules containing the RGD peptide sequence are known to bind integrins with high affinity. Studies of hexa-and hepta-peptides labeled with a near-infrared fluorescent probe (cypate) showed that rearranging the glycine in a linear RGD peptide sequence to form the GRD analogue favored the uptake of the GRD compound by alphavbeta3 integrin receptor (ABIR)-positive A549 tumor cells and tissue. The internalization of the GRD compound in A549 cells and tumor uptake in mice were inhibited by ABIR-avid peptides, suggesting its recognition by this receptor. Further studies with functional blocking antibodies and beta3 knockout cells revealed that beta3 integrin mediates the internalization of the cypate-GRD peptide. Molecular modeling studies supported preferential interaction of the probe with the beta3 subunit of integrins relative to the alphav subunit. The results demonstrate that the cypate-GRD peptide targets beta3 integrin, thereby providing a strategy to monitor drug delivery and efficacy, and physiopathologic processes mediated by this protein.

Beta 3 integrin expression on T cells from renal allograft recipients

Recent studies emphasize the paramount significance of beta 3 integrin in cell adhesion and homing, which may be particularly relevant in cancer progression and metastasis. In contrast, the presence and potential role of beta 3 on human T cells is practically unknown. We show that T cells can express significant amounts of alpha-beta 3 integrin (CD41/CD61), and the expression of alpha(v)-beta 3 (CD51/CD61) remains very low. T-cell beta 3 integrin is probably transferred by platelet-derived microparticles.