The marine natural product mimic MPM-1 is cytolytic and induces DAMP release from human cancer cell lines

Bioprospecting contributes to the discovery of new molecules with anticancer properties. Compounds with cytolytic activity and the ability to induce immunogenic cell death can be administered as intratumoral injections with the aim to activate anti-tumor immune responses by causing the release of tumor antigens as well as damage-associated molecular patterns (DAMPs) from dying cancer cells. In the present study, we report the cytolytic and DAMP-releasing efects of a new natural product mimic termed MPM-1 that was inspired by the marine Eusynstyelamides. We found that MPM-1 rapidly killed cancer cells in vitro by inducing a necrosis-like death, which was accompanied by lysosomal swelling and perturbation of autophagy in HSC-3 (human oral squamous cell carcinoma) cells. MPM-1 also induced release of the DAMPs adenosine triphosphate (ATP) and high mobility group box 1 (HMGB1) from Ramos (B-cell lymphoma) and HSC-3 cells, as well as cell surface expression of calreticulin in HSC-3 cells. This indicates that MPM-1 has the ability to induce immunogenic cell death, further suggesting that it may have potential as a novel anticancer compound

Cleavage of the urokinase receptor (uPAR) on oral cancer cells: Regulation by transforming growth factor - beta1 (TGF-beta1) and potential effects on migration and invasion

Source at https://doi.org/10.1186/s12885-017-3349-7 Background: Urokinase plasminogen activator (uPA) receptor (uPAR) is up-regulated at the invasive tumour front of human oral squamous cell carcinoma (OSCC), indicating a role for uPAR in tumour progression. We previously observed elevated expression of uPAR at the tumour-stroma interface in a mouse model for OSCC, which was associated with increased proteolytic activity. The tumour microenvironment regulated uPAR expression, as well as its glycosylation and cleavage. Both full-length- and cleaved uPAR (uPAR (II-III)) are involved in highly regulated processes such as cell signalling, proliferation, migration, stem cell mobilization and invasion. The aim of the current study was to analyse tumour associated factors and their effect on uPAR cleavage, and the potential implications for cell proliferation, migration and invasion. Methods: Mouse uPAR was stably overexpressed in the mouse OSCC cell line AT84. The ratio of full-length versus cleaved uPAR as analysed by Western blotting and its regulation was assessed by addition of different protease inhibitors and transforming growth factor - β 1(TGF- β 1). The role of uPAR cleavage in cell proliferation and migration was analysed using real-time cell analysis and invasion was assessed using the myoma invasion model. Results: We found that when uPAR was overexpressed a proportion of the receptor was cleaved, thus the cells presented both full-length uPAR and uPAR (II-III). Cleavage was mainly performed by serine proteases and urokinase plasminogen activator (uPA) in particular. When the OSCC cells were stimulated with TGF- β 1, the production of the uPA inhibitor PAI-1 was increased, resulting in a reduction of uPAR cleavage. By inhibiting cleavage of uPAR, cell migration was reduced, and by inhibiting uPA activity, invasion was reduced. We could also show that medium containing soluble uPAR (suPAR), and cleaved soluble uPAR (suPAR (II-III)), induced migration in OSCC cells with low endogenous levels of uPAR. Conclusions: These results show that soluble factors in the tumour microenvironment, such as TGF- β 1, PAI-1 and uPA, can influence the ratio of full length and uPAR (II-III) and thereby potentially effect cell migration and invasion. Resolving how uPAR cleavage is controlled is therefore vital for understanding how OSCC progresses and potentially provides new targets for therapy

Plectin as a prognostic marker in non-metastatic oral squamous cell carcinoma

Background: Oral squamous cell carcinoma (OSCC) is associated with a poor 5-year survival rate. In general, patients diagnosed with small tumors have a fairly good prognosis, but some small tumors have an aggressive behavior leading to early death. There are at present no reliable prognostic biomarkers for oral cancers. Thus, to optimize treatment for the individual patient, there is a need for biomarkers that can predict tumor behavior. Method: In the present study the potential prognostic value of plectin was evaluated by a tissue microarray (TMA) based immunohistochemical analysis of primary tumor tissue obtained from a North Norwegian cohort of 115 patients diagnosed with OSCC. The expression of plectin was compared with clinicopathological variables and 5 year survival. Results: The statistical analysis revealed that low expression of plectin in the tumor cells predicted a favorable outcome for patients with non-metastatic disease (p = 0.008). Furthermore, the expression of plectin was found to correlate (p = 0.01) with the expression of uPAR, which we have previously found to be a potential prognostic marker for T1N0 tumors. Conclusions: Our results indicate that low expression of plectin predicts a favorable outcome for patients with non-metastatic OSCC and the expression level of plectin may therefore be used in the treatment stratification for patients with early stage disease

Oral Squamous Cell Carcinoma - Role of the Plasminogen Activation System in Tumour Progression.

Oral squamous cell carcinoma (OSCC) is an aggressive and unpredictable cancer with a high tendency to recur and metastasise. Despite increasing efforts to improved treatment, the 5-year survival rate is still low. We discovered that low expression levels of the urokinase plasminogen activator receptor (uPAR) and the plasminogen activator inhibitor-1 (PAI-1) two proteins normally involved in the process of wound healing, were associated with low disease specific death in patients with early stage OSCC. PAI-1 and uPAR were therefore suggested as potential biomarkers to aid clinicians in treatment stratification. High expression of uPAR and PAI-1 was therefore implicated in the early stages of OSCC progression. In vivo studies further showed that the tumour microenvironment was involved in the induction of uPAR expression, which simultaneously resulted in enhanced activity of gelatinolytic enzymes. In vivo tumour growth in a syngeneic mouse model of OSCC did not show metastasis, however the tumour growth pattern reflected that of early stage OSCC. uPAR locates the proteolytic enzyme urokinase plasminogen activator (uPA) to the cell surface of cancer cells, and such pericellular proteolysis is thought to be required for cancer cell invasion and metastasise to distant organs. Cleavage of uPAR terminates its ability to bind uPA, however gives cells a different set of functions. These include directional migration which is also needed for cancer cells to spread. We could show that the stromal derived factor transforming growth factor-β1 (TGF-β1) up-regulated the expression of PAI-1, and furthermore down-regulated cleavage of uPAR. Taken together, the current study shows that uPAR and PAI-1 are involved in early stage of OSCC progression, and that factors in the tumour microenvironment are important regulators of both the expression and posttranslational modifications such as glycosylation and proteolytic cleavage

4-nitroquinoline 1-oxide-induced oral epithelial lesions exhibit time- and stage-dependent changes in the tumor immune microenvironment

Oral tongue squamous cell carcinoma (OTSCC) is the most common cancer of the oral cavity and is associated with high morbidity due to local invasion and lymph node metastasis. Tumor infiltrating lymphocytes (TILs) are associated with good prognosis in oral cancer patients and dictate response to treatment. Ectopic sites for immune activation in tumors, known as tertiary lymphoid structures (TLS), and tumor-associated high-endothelial venules (TA-HEVs), which are specialized lymphocyte recruiting vessels, are associated with a favorable prognosis in OSCC. Why only some tumors support the development of TLS and HEVs is poorly understood. In the current study we explored the infiltration of lymphocyte subsets and the development of TLS and HEVs in oral epithelial lesions using the 4-nitroquinoline 1-oxide (4NQO)- induced mouse model of oral carcinogenesis. We found that the immune response to 4NQO-induced oral epithelial lesions was dominated by T cell subsets. The number of T cells (CD4+, FoxP3+, and CD8+), B cells (B220+) and PNAd+ HEVs increased from the earliest to the latest endpoints. All the immune markers increased with the severity of the dysplasia, while the number of HEVs and B cells further increased in SCCs. HEVs were present already in early-stage lesions, while TLS did not develop at any timepoint. This suggests that the 4NQO model is applicable to study the dynamics of the tumor immune microenvironment at early phases of oral cancer development, including the regulation of TA-HEVs in OTSCC

Nephronectin as a matrix effector in cancer

The extracellular matrix protein nephronectin plays an important regulatory role during embryonic development, controlling renal organogenesis through integrin α8β1 association. Nephronectin has three main domains: five N-terminal epidermal growth factor-like domains, a linker region harbouring two integrin-binding motifs (RGD and LFEIFEIER), and a C-terminal MAM domain. In this review, we look into the domain-related functions of nephronectin, and tissue distribution and expression. During the last two decades it has become evident that nephronectin also plays a role during cancer progression and in particular metastasis. Nephronectin is overexpressed in both human and mouse breast cancer compared to normal breast tissue where the protein is absent. Cancer cells expressing elevated levels of nephronectin acquire increased ability to colonise distant organs. In particular, the enhancer-motif (LFEIFEIER) which is specific to the integrin α8β1 association induces viability via p38 MAPK and plays a role in colonization. Integrins have long been desired as therapeutic targets, where low efficiency and receptor redundancy have been major issues. Based on the summarised publications, the enhancer-motif of nephronectin could present a novel therapeutic target

Plectin as a prognostic marker in non-metastatic oral squamous cell carcinoma

Background: Oral squamous cell carcinoma (OSCC) is associated with a poor 5-year survival rate. In general, patients diagnosed with small tumors have a fairly good prognosis, but some small tumors have an aggressive behavior leading to early death. There are at present no reliable prognostic biomarkers for oral cancers. Thus, to optimize treatment for the individual patient, there is a need for biomarkers that can predict tumor behavior. Method: In the present study the potential prognostic value of plectin was evaluated by a tissue microarray (TMA) based immunohistochemical analysis of primary tumor tissue obtained from a North Norwegian cohort of 115 patients diagnosed with OSCC. The expression of plectin was compared with clinicopathological variables and 5 year survival. Results: The statistical analysis revealed that low expression of plectin in the tumor cells predicted a favorable outcome for patients with non-metastatic disease (p = 0.008). Furthermore, the expression of plectin was found to correlate (p = 0.01) with the expression of uPAR, which we have previously found to be a potential prognostic marker for T1N0 tumors. Conclusions: Our results indicate that low expression of plectin predicts a favorable outcome for patients with non-metastatic OSCC and the expression level of plectin may therefore be used in the treatment stratification for patients with early stage disease

Urokinase Plasminogen Activator Receptor (uPAR) and Plasminogen Activator Inhibitor-1 (PAI-1) are potential predictive biomarkers in early stage Oral Squamous Cell Carcinomas (OSCC)

Oral squamous cell carcinoma (OSCC) is often associated with metastatic disease and a poor 5 year survival rate. Patients diagnosed with small tumours generally have a more favourable outcome, but some of these small tumours are aggressive and lead to early death. To avoid harmful overtreatment of patients with favourable prognosis, there is a need for predictive biomarkers that can be used for treatment stratification. In this study we assessed the possibility to use components of the plasminogen activator (PA) system as prognostic markers for OSCC outcome and compared this to the commonly used biomarker Ki-67. A tissue-micro-array (TMA) based immunohistochemical analysis of primary tumour tissue obtained from a North Norwegian cohort of 115 patients diagnosed with OSCC was conducted. The expression of the biomarkers was compared with clinicopathological variables and disease specific death. The statistical analyses revealed that low expression of uPAR (p = 0.031) and PAI-1 (p = 0.021) in the tumour cells was significantly associated with low disease specific death in patients with small tumours and no lymph node metastasis (T1N0). The commonly used biomarker, Ki-67, was not associated with disease specific death in any of the groups of patients analysed. The conclusion is that uPAR and PAI-1 are potential predictive biomarkers in early stage tumours and that this warrants further studies on a larger cohort of patients