Retinoic acid modulates the radiosensitivity of head-and-neck squamous carcinoma cells grown in collagen gel

In Vitro Models of Head and Neck Cancer: From Primitive to Most Advanced

For several decades now, researchers have been trying to answer the demand of clinical oncologists to create an ideal preclinical model of head and neck squamous cell carcinoma (HNSCC) that is accessible, reproducible, and relevant. Over the past years, the development of cellular technologies has naturally allowed us to move from primitive short-lived primary 2D cell cultures to complex patient-derived 3D models that reproduce the cellular composition, architecture, mutational, or viral load of native tumor tissue. Depending on the tasks and capabilities, a scientific laboratory can choose from several types of models: primary cell cultures, immortalized cell lines, spheroids or heterospheroids, tissue engineering models, bioprinted models, organoids, tumor explants, and histocultures. HNSCC in vitro models make it possible to screen agents with potential antitumor activity, study the contribution of the tumor microenvironment to its progression and metastasis, determine the prognostic significance of individual biomarkers (including using genetic engineering methods), study the effect of viral infection on the pathogenesis of the disease, and adjust treatment tactics for a specific patient or groups of patients. Promising experimental results have created a scientific basis for the registration of several clinical studies using HNSCC in vitro models.

Targeting Type I Collagen for Cancer Treatment

Collagen is the most abundant protein in animals. Interactions between tumor cells and collagen influence every step of tumor development. Type I collagen is the main fibrillar collagen in the extracellular matrix and is frequently up-regulated during tumorigenesis. The binding of type I collagen to its receptors on tumor cells promotes tumor cell proliferation, epithelial-mesenchymal transition, and metastasis. Type I collagen also regulates the efficacy of tumor therapies, such as chemotherapy, radiotherapy, and immunotherapy. Furthermore, type I collagen fragments are diagnostic markers of metastatic tumors and have prognostic value. Inhibition of type I collagen synthesis has been reported to have anti-tumor effects in animal models. However, collagen has also been shown to possess anti-tumor activity. Therefore, the roles that type I collagen plays in tumor biology are complex and tumor type-dependent. In this review, we discuss the expression and regulation of synthesis of type I collagen, as well as the role up-regulated type I collagen plays in various stages of cancer progression. We also discuss the role of collagen in tumor therapy. Finally, we highlight several recent approaches targeting type I collagen for cancer treatment. This article is protected by copyright. All rights reserved.

High-throughput compound screening identifies navitoclax combined with irradiation as a candidate therapy for HPV-negative head and neck squamous cell carcinoma

Conventional chemotherapeutic agents are nonselective, often resulting in severe side effects and the development of resistance. Therefore, new molecular-targeted therapies are urgently needed to be integrated into existing treatment regimens. Here, we performed a high-throughput compound screen to identify a synergistic interaction between ionizing radiation and 396 anticancer compounds. The assay was run using five human papillomavirus (HPV)-negative head and neck squamous cell carcinoma (HNSCC) cell lines cultured on the human tumor-derived matrix Myogel. Our screen identified several compounds with strong synergistic and antagonistic effects, which we further investigated using multiple irradiation doses. Navitoclax, which emerged as the most promising radiosensitizer, exhibited synergy with irradiation regardless of the p53 mutation status in all 13 HNSCC cell lines. We performed a live cell apoptosis assay for two representative HNSCC cell lines to examine the effects of navitoclax and irradiation. As a single agent, navitoclax reduced proliferation and induced apoptosis in a dose-dependent manner, whereas the navitoclax-irradiation combination arrested cell cycle progression and resulted in substantially elevated apoptosis. Overall, we demonstrated that combining navitoclax with irradiation resulted in synergistic in vitro antitumor effects in HNSCC cell lines, possibly indicating the therapeutic potential for HNSCC patients.

Improvement of sciatic nerve regeneration using laminin-binding human NGF-beta

Background

Sciatic nerve injuries often cause partial or total loss of motor, sensory and autonomic functions due to the axon discontinuity, degeneration, and eventual death which finally result in substantial functional loss and decreased quality of life. Nerve growth factor (NGF) plays a critical role in peripheral nerve regeneration. However, the lack of efficient NGF delivery approach limits its clinical applications. We reported here by fusing with the N-terminal domain of agrin (NtA), NGF-β could target to nerve cells and improve nerve regeneration.

Methods

Laminin-binding assay and sustained release assay of NGF-β fused with NtA (LBD-NGF) from laminin in vitro were carried out. The bioactivity of LBD-NGF on laminin in vitro was also measured. Using the rat sciatic nerve crush injury model, the nerve repair and functional restoration by utilizing LBD-NGF were tested.

Findings

LBD-NGF could specifically bind to laminin and maintain NGF activity both in vitro and in vivo. In the rat sciatic nerve crush injury model, we found that LBD-NGF could be retained and concentrated at the nerve injury sites to promote nerve repair and enhance functional restoration following nerve damages.

Conclusion

Fused with NtA, NGF-β could bind to laminin specifically. Since laminin is the major component of nerve extracellular matrix, laminin binding NGF could target to nerve cells and improve the repair of peripheral nerve injuries.

Cyclooxygenase-2 dependent and independent antitumor effects induced by celecoxib in urinary bladder cancer cells

Transitional cell carcinoma of the urinary bladder is the second most common genitourinary malignancy in people in the United States. Cyclooxygenase-2 (COX-2) is overexpressed in bladder cancer. COX-2 inhibitors have had antitumor activity against bladder cancer, but the mechanisms of action are unclear. Clinically relevant concentrations of COX-2 inhibitors fail to inhibit proliferation in standard in vitro assays. In pilot experiments, different culture conditions [standard monolayer, modified monolayer, soft agar, collagen, and poly(2-hydroxyethyl methacrylate)-coated plates] were assessed to determine conditions suitable for the study of COX inhibitor growth-inhibitory effects. This was followed by studies of the effects of clinically relevant concentrations of a selective COX-2 inhibitor (celecoxib) on urinary bladder cancer cell lines (HT1376, TCCSUP, and UMUC3). Celecoxib (<or=5 micromol/L) inhibited proliferation of COX-2-expressing HT1376 cells in soft agar and modified monolayer cell culture conditions in a COX-2-dependent manner. COX-2 expression, however, did not always correlate with response to celecoxib. TCCSUP cells that express COX-2 were minimally affected by celecoxib, and UMUC3 cells that lack COX-2 expression were modestly inhibited by the drug. When UMUC3(Cox-2/Tet) cells overexpressing COX-2 under the control of tetracycline-inducible promoter were treated with celecoxib in modified monolayer cell culture, growth inhibition was found to be associated with changes in the expression of pRb. Not surprisingly, the proliferation of all cell lines was inhibited by excessively high concentrations of celecoxib. In conclusion, the modified culture conditions allowed detection of COX-2-dependent and COX-2-independent growth-inhibitory activity of celecoxib in urinary bladder cancer cells.

Promotion of peripheral nerve growth by collagen scaffolds loaded with collagen‐targeting human nerve growth factor‐β

Nerve growth factor (NGF) plays a critical role in neuronal development and regeneration. However, the lack of efficient NGF delivery system limits its clinical application. We reported that a peptide deduced from collagenase, TKKTLRT, fused with NGF-beta could develop a collagen based NGF targeting delivery system. Our results showed that this peptide could allow fused NGF-beta bind to collagen specifically. In addition, we found that the polypeptide could result in a 2.3-fold increase in the expression level and a significant improvement of bioactivity of fused NGF-beta. In the in vivo function study, collagen membranes loaded with the collagen binding NGF enhanced the nerve growth. Thus, the targeting wound repair system could be important for the repair of peripheral nerve injury.

The effect of the amelogenin fraction of enamel matrix proteins on fibroblast-mediated collagen matrix reorganization

Enamel matrix proteins (EMP), extracted from developing porcine teeth, promote not only periodontal regeneration but also cutaneous wound healing presumably via the amelogenin fraction. Because it is unclear whether the effect of EMP can be ascribed to amelogenins, we compared EMP with recombinant amelogenin in the relaxed dermal equivalent (DE) in vitro model for early wound contraction. EMP and recombinant porcine amelogenin (rP172) at 1 mg/ml were incorporated into DEs composed of human dermal fibroblasts and a type I collagen matrix. The area reduction, as a measure of contraction, as well as fibroblast numbers and TGF-beta1 levels, were quantified over 7 days in culture in the presence of 10% foetal bovine serum. Both EMP and recombinant amelogenin increased contraction (p < 0.005) and fibroblast numbers (p < 0.005) compared with controls (acetic acid vehicle and 1mg/ml porcine serum albumin) and the positive control TGF-beta1 added at 10 ng/ml. Increased contraction with EMP and recombinant amelogenin was most pronounced after the first day of incubation and was associated with elevated (p < 0.005) TGF-beta1 levels in conditioned medium. In conclusion, the amelogenin component of EMP augmented fibroblast-driven collagen matrix remodelling, at least partially, by increasing the endogenous production of TGF-beta1. These effects of EMP/amelogenin may be beneficial for cutaneous wound healing.

Radiosensitivity of human colon cancer cell enhanced by immunoliposomal docetaxel

AIM: To enhance the radiosensitivity of human colon cancer cells by docetaxel.

METHODS: Immunoliposomal docetaxel was prepared by coupling monoclonal antibody against carcinoembryonic antigen to cyanuric chloride at the PEG terminus of liposome. LoVo adenocarcinoma cell line was treated with immunoliposomal docetaxel or/and irradiation. MTT colorimetric assay was used to estimate cytotoxicity of immunoliposomal docetaxel and radiotoxicity. Cell cycle redistribution and apoptosis were determined with flow cytometry. Survivin expression in LoVo cells was verified by immunohistochemistry. D801 morphologic analysis system was used to semi-quantify immunohistochemical staining of survivin.

RESULTS: Cytotoxicity was induced by immunoliposomal docetaxel alone in a dose-dependent manner. Immunoli-posomal docetaxel yielded a cytotoxicity effect at a low dose of 2 nmol/L. With a single dose irradiation, the relative surviving fraction of LoVo cells showed a dose-dependent response, but there were no significant changes as radiation delivered from 4 to 8 Gy. Compared with liposomal docetaxel or single dose irradiation, strongly radiopotentiating effects of immunoliposomal docetaxel on LoVo cells were observed. A low dose of immunoliposomal docetaxel could yield sufficient radiosensitivity. Immunoliposomal docetaxel were achieved both specificity of the conjugated antibody and drug radiosensitization. Combined with radiation, immunoliposomal docetaxel significantly increased the percentage of G₂/M cells and induced apoptosis, but significantly decreased the percentage of cells in G₂/G₁ and S phase by comparison with liposomal docetaxel. Immunohistochemical analysis showed that the brown stained survivin was mainly in cytoplasm of LoVo cells. Semi-quantitative analysis of the survivin immunostaining showed that the expression of survivin in LoVo cells under irradiation with immunoliposomal docetaxel was significantly decreased.

CONCLUSION: Immunoliposomal docetaxel is strongly effective for target radiosensitation in LoVo colon carcinoma cells, and may offer the potential to improve local radiotherapy.

Endothelial cells increase the radiosensitivity of oropharyngeal squamous carcinoma cells in collagen gel

We assessed the radiosensitivity of human HSCO oropharyngeal squamous carcinoma cells in the presence of paracrine factors produced by human HECV umbilical vein endothelial cells. To this end the cells were embedded in separate collagen gels at the density of 1 x 10(6) cells/ml each, and the two gels were placed in a well of a six-well plate, sharing the same medium but without physical contact (two-gel model). The medium was not changed during the observation period to ensure the accumulation of soluble factors. On day 2 of culture the gels were irradiated with 0, 0.5, 1, 2 and 8 Gray (Gy) and on day 7 of culture they were disaggregated and cell survival evaluated by the MTT assay. Results were compared with proper untreated and irradiated control groups. Under these experimental conditions it was found that: (1) HSCO and HECV cells influenced reciprocally their behaviour in the two-gel model, in terms that cell survival was enhanced and inhibited, respectively; (2) as expected, HSCO cells were more radioresistant in collagen gel than in monolayer; (3) on the average the survival of HECV cells was enhanced at low radiation doses, irrespective of whether they were cultured alone or with HSCO cells in the two-gel model and (4) HSCO cells displayed a high radioresistance when irradiated alone at doses from 0.5 to 8 Gy. However, when co-cultured with HECV cells in the two-gel model, they become highly radiosensitive already at the dose of 2 Gy, while none of them survived at the dose of 8 Gy. This radiosensitizing effect was specifically induced by paracrine factors circulating in the medium, supporting the notion that stromal endothelial cells may be essential components of a metabolic circuitry supplying solid tumors with radiosensitizing factors.

Systemic Retinoic Acid Treatment Induces Sodium/Iodide Symporter Expression and Radioiodide Uptake in Mouse Breast Cancer Models

Lactating breast tissue and some breast cancers express the sodium/iodide symporter (NIS) and concentrate iodide. We recently demonstrated that all-trans retinoic acid (tRA) induces both NIS gene expression and iodide accumulation in vitro in well-differentiated human breast cancer cells (MCF-7). In the present study, we investigated the in vivo efficacy and specificity of tRA-stimulated iodide accumulation in mouse breast cancer models. Immunodeficient mice with MCF-7 xenograft tumors were treated with systemic tRA for 5 days. Iodide accumulation in the xenograft tumors was markedly increased, approximately 15-fold greater than levels without treatment, and the effects were tRA dose dependent. Iodide accumulation in other organs was not significantly influenced by tRA treatment. Significant induction of NIS mRNA and protein in the xenograft tumors was observed after tRA treatment. Iodide accumulation and NIS mRNA expression were also selectively induced in breast cancer tissues in transgenic mice expressing the oncogene, polyoma virus middle T antigen. These data demonstrate selective induction of functional NIS in breast cancer by tRA. Treatment with short-term systemic retinoic acid, followed by radioiodide administration, is a potential tool in the diagnosis and treatment of some differentiated breast cancer.