Effect of reoxygenation on the hypoxia-induced up-regulation of serine protease inhibitor PAI-1 in head and neck cancer cells

Matricellular proteins: Potential biomarkers in head and neck cancer

The extracellular matrix (ECM) is a complex network of diverse multidomain macromolecules, including collagen, proteoglycans, and fibronectin, that significantly contribute to the mechanical properties of tissues. Matricellular proteins (MCPs), as a family of non-structural proteins, play a crucial role in regulating various ECM functions. They exert their biological effects by interacting with matrix proteins, cell surface receptors, cytokines, and proteases. These interactions govern essential cellular processes such as differentiation, proliferation, adhesion, migration as well as multiple signal transduction pathways. Consequently, MCPs are pivotal in maintaining tissue homeostasis while orchestrating intricate molecular mechanisms within the ECM framework. The expression level of MCPs in adult steady-state tissues is significantly low; however, under pathological conditions such as inflammation and cancer, there is a substantial increase in their expression. In recent years, an increasing number of studies have focused on elucidating the role and significance of MCPs in the development and progression of head and neck cancer (HNC). During HNC progression, there is a remarkable upregulation in MCP expression. Through their distinctive structure and function, they actively promote tumor growth, invasion, epithelial-mesenchymal transition, and lymphatic metastasis of HNC cells. Moreover, by binding to integrins and modulating various signaling pathways, they effectively execute their biological functions. Furthermore, MCPs also hold potential as prognostic indicators. Although the star proteins of various MCPs have been extensively investigated, there remains a plethora of MCP family members that necessitate further scrutiny. This article comprehensively examines the functionalities of each MCP and highlights the research advancements in the context of HNC, with an aim to identify novel biomarkers for HNC and propose promising avenues for future investigations.

Spatially modulated illumination microscopy: application perspectives in nuclear nanostructure analysis

Thousands of genes and the complex biochemical networks for their transcription are packed in the micrometer sized cell nucleus. To control biochemical processes, spatial organization plays a key role. Hence the structure of the cell nucleus of higher organisms has emerged as a main topic of advanced light microscopy. So far, a variety of methods have been applied for this, including confocal laser scanning fluorescence microscopy, 4Pi-, STED- and localization microscopy approaches, as well as (laterally) structured illumination microscopy (SIM). Here, we summarize the state of the art and discuss application perspectives for nuclear nanostructure analysis of spatially modulated illumination (SMI). SMI is a widefield-based approach to using axially structured illumination patterns to determine the axial extension (size) of small, optically isolated fluorescent objects between less than or equal to 200 nm and greater than or equal to 40 nm diameter with a precision down to the few nm range; in addition, it allows the axial positioning of such structures down to the 1 nm scale. Combined with SIM, a three-dimensional localization precision of less than or equal to 1 nm is expected to become feasible using fluorescence yields typical for single molecule localization microscopy applications. Together with its nanosizing capability, this may eventually be used to analyse macromolecular complexes and other nanostructures with a topological resolution, further narrowing the gap to Cryoelectron microscopy.

This article is part of the Theo Murphy meeting issue ‘Super-resolution structured illumination microscopy (part 2)’.

Hypoxia-Induced LIN28A mRNA Promotes the Metastasis of Colon Cancer in a Protein-Coding-Independent Manner

The hypoxic microenvironment is beneficial to the metastasis but not to the proliferation of cancer cells. However, the mechanisms regarding to hypoxia differentially regulating cancer metastasis and proliferation are largely unknown. In this study, we revealed that hypoxia induced the expression of LIN28A at mRNA level but segregated LIN28A mRNAs in the P-bodies and thus inhibits the production of LIN28A protein. This unexpected finding suggests that there may be non-coding role for LIN28A mRNA in the progression of colon cancer. We further showed that the non-coding LIN28A mRNA promotes the metastasis but not proliferation of colon cancer cells in vitro and in vivo. Mechanistically, we revealed that methionyl aminopeptidase 2 (METAP2) is one of the up-regulated metastasis regulators upon over-expression of non-coding LIN28A identified by mass spectrum, and confirmed that it is non-coding LIN28A mRNA instead of LIN28A protein promotes the expression of METAP2. Moreover, we demonstrated that knockdown of DICER abolished the promotional effects of non-coding LIN28A on the metastasis and METAP2 expression. Conclusively, we showed that hypoxia induces the production of LIN28A mRNAs but segregated them into the P-bodies together with miRNAs targeting both LIN28A and METAP2, and then promotes the metastasis by positively regulating the expression of METAP2. This study uncovered a distinctive role of hypoxia in manipulating the metastasis and proliferation by differently regulating the expression of LIN28A at mRNA and protein level.

Prognostic implications of the co-detection of the urokinase plasminogen activator system and osteopontin in patients with non-small-cell lung cancer undergoing radiotherapy and correlation with gross tumor volume

BACKGROUND

The urokinase plasminogen activator system (uPA, uPAR, PAI‑1) is upregulated in cancer and high plasma levels are associated with poor prognosis. Their interaction with hypoxia-related osteopontin (OPN) which is also overexpressed in malignant tumors suggests potential clinical relevance. However, the prognostic role of the uPA system in the radiotherapy (RT) of non-small-cell lung cancer (NSCLC), particularly in combination with OPN, has not been investigated so far.

METHODS

uPA, uPAR, PAI‑1 and OPN plasma levels of 81 patients with locally advanced or metastasized NSCLC were prospectively analyzed by ELISA before RT and were correlated to clinical patient/tumor data and prognosis after RT.

RESULTS

uPAR plasma levels were higher in M1; uPA and PAI‑1 levels were higher in M0 NSCLC patients. uPAR correlated with uPA (p < 0.001) which also correlated with PAI‑1 (p < 0.001). The prognostic impact of OPN plasma levels in the RT of NSCLC was previously reported by our group. PAI‑I plasma levels significantly impacted overall (OS) and progression-free survival (PFS). Low PAI‑1 levels were associated with a significantly reduced OS and PFS with a nearly 2‑fold increased risk of death (p = 0.029) and tumor progression (p = 0.029). In multivariate analysis, PAI‑1 levels remained an independent prognostic factor for OS and PFS with a 3‑fold increased risk of death (p = 0.001). If PAI‑1 plasma levels were combined with OPN or tumor volume, we found an additive prognostic impact on OS and PFS with a 2.5- to 3‑fold increased risk of death (p = 0.01).

CONCLUSION

Our results suggest that PAI-1 but not uPA and uPAR might add prognostic information in patients with advanced NSCLC undergoing RT. High pretreatment PAI-1 plasma levels were found predominantly in M0-stage patients and indicate a favorable prognosis as opposed to OPN where high plasma levels are associated with poor survival and metastasis. In combination, PAI-1 and OPN levels successfully predicted outcome and additively correlated with prognosis. These findings support the notion of an antidromic prognostic impact of OPN and PAI-1 plasma levels in the RT of advanced NSCLC.

Oxygen regulates molecular mechanisms of cancer progression and metastasis

Oxygen is the basic molecule which supports life and it truly is "god's gift to life." Despite its immense importance, research on "oxygen biology" has never received the light of the day and has been limited to physiological and biochemical studies. It seems that in modern day biology, oxygen research is summarized in one word "hypoxia." Scientists have focused on hypoxia-induced transcriptomics and molecular-cellular alterations exclusively in disease models. Interestingly, the potential of oxygen to control the basic principles of biology like homeostatic maintenance, transcription, replication, and protein folding among many others, at the molecular level, has been completely ignored. Here, we present a perspective on the crucial role played by oxygen in regulation of basic biological phenomena. Our conclusion highlights the importance of establishing novel research areas like oxygen biology, as there is great potential in this field for basic science discoveries and clinical benefits to the society.

Plasminogen activator inhibitor-1 (PAI-1) expression in relation to hypoxia and oncoproteins in clinical cervical tumors

PURPOSE

Explore the role of plasminogen activator inhibitor-1 (PAI-1) in cervical cancer and its relationship to hypoxia and the expression of p53, Ku70/80, and cyclin D1.

MATERIAL AND METHODS

The expression of PAI-1, cyclin D1, and p53, together with tumor oxygenation, were determined in 43 consecutive patients suffering from localized cervical carcinoma. Oncoprotein expression was determined by immunohistochemistry. Tumor oxygenation was measured using a polarographic probe system, "pO2 histography."

RESULTS

PAI expression was considered negative in 32.6% and overexpressed in 18.6% of cases. Cyclin D1 showed a median expression of 5.0 (range 0-70). We observed a positive association between PAI expression and altered p53 (p = 0.049) and cyclin D1 (p = 0.020). An inverse association was detected between PAI and Ku70/80 expression (p = 0.042). Cyclin D1 staining increased according to tumor volume (r = 0.314, p = 0.009). We did not observe a significant association between PAI and hypoxia or other clinicopathological parameters.

CONCLUSION

The present results show that PAI-1 overexpression is associated with nonhomologous end-joining DNA repair down-regulation (low Ku70/80 expression) and with increased p53 and cyclin D1 expression, and they suggest that PAI-1 plays a role in the tumor behavior in cervical carcinoma.

A novel molecular marker for early detection and evaluating prognosis of gastric cancer: N-myc downstream regulated gene-1 (NDRG1)

OBJECTIVE

N-myc downstream regulated gene-1 (NDRG1) is known as a differentiation-related gene that plays important roles in cell differentiation, organ formation, and embryonic development. NDRG1 was recently found to significantly down regulate in a variety of different neoplasms. Its significance in gastric cancer has not been studied.

MATERIALS AND METHODS

NDRG1 was detected at its protein level by immunohistochemistry in formalin-fixed and paraffin-embedded sections with a total of 110 pair gastric cancer specimens including tumor and corresponding paraneoplastic tissues; NDRG1 mRNA was detected by real time-polymerase chain reaction. Meanwhile, the correlations between NDRG1 and clinicopathological factors were observed. Overexpression of NDRG1 has influence on the biological behavior of gastric cancer cell, which was detected by cell growth assay, apoptosis assay, and in vitro motility and invasion assay.

RESULTS

NDRG1 protein was down regulated in gastric cancer tissues, and the NDRG1 low expression rate was 73.6% (79/110). Moreover, NDRG1 expression has a significant inverse correlation with tumor stromal invasion, lymph node metastasis, pathological stage, but not with distant metastasis. The patients with low NDRG1 expression had a significantly shorter survival opportunity than those with high NDRG1 expression. In addition, overexpression of NDRG1 induced early apoptosis and inhibited SGC7901 cell proliferation and its motility and invasion capability.

CONCLUSIONS

NDRG1 plays a significant role in carcinogenesis and preventing the metastasis and invasion of gastric cancer cells. NDRG1 could be developed as a marker contributing to diagnosis and evaluating prognosis in gastric cancer, as well as a potential therapeutic target of gastric cancer.

MicroRNA-184 antagonizes microRNA-205 to maintain SHIP2 levels in epithelia

Despite their potential to regulate approximately one-third of the whole genome, relatively few microRNA (miRNA) targets have been experimentally validated, particularly in stratified squamous epithelia. Here we demonstrate not only that the lipid phosphatase SHIP2 is a target of miRNA-205 (miR-205) in epithelial cells, but, more importantly, that the corneal epithelial-specific miR-184 can interfere with the ability of miR-205 to suppress SHIP2 levels. This is the first example of a miRNA negatively regulating another to maintain levels of a target protein. Interfering with miR-205 function by using a synthetic antagomir, or by the ectopic expression of miR-184, leads to a coordinated damping of the Akt signaling pathway via SHIP2 induction. This was associated with a marked increase in keratinocyte apoptosis and cell death. Aggressive squamous cell carcinoma (SCC) cells exhibited elevated levels of miR-205. This was associated with a concomitant reduction in SHIP2 levels. Partial knockdown of endogenous miR-205 in SCCs markedly decreased phosphorylated Akt and phosphorylated BAD levels and increased apoptosis. We were able to increase SHIP2 levels in SCC cells after inhibition of miR-205. Therefore, miR-205 might have diagnostic value in determining the aggressivity of SCCs. Blockage of miR-205 activity with an antagomir or via ectopic expression of miR-184 could be novel therapeutic approaches for treating aggressive SCCs.

The plasminogen activator inhibitor "paradox" in cancer

Proteolysis in general and specifically the plasminogen activating system regulated by urokinase (uPA) its specific receptor, the GPI membrane anchored urokinase receptor (uPAR) and the specific plasminogen activator inhibitor 1 (PAI-1) plays a major role in tumorigenesis, tumor progression, tumor invasion and metastasis formation. This is exemplified by a body of published work showing a positive correlation between the expression of uPA or uPAR in several tumors and their malignancy. It is generally assumed that such a "pro-malignant" effect of the uPA-uPAR system is mediated by increased local proteolysis thus favoring tumor invasion, by a pro-angiogenic effect of this system and also by uPA-uPAR signaling towards the tumor thereby shifting the tumor phenotype to a more "malignant" one. However, when tumor patients are analyzed for long term survival, those with high levels of the inhibitor of the system, PAI-1 have a much worse prognosis than those with lower PAI-1 levels. This indicates that increased overall proteolysis alone cannot be made responsible for the adverse effects of the plasminogen activating system in tumors. Moreover, it becomes increasingly evident that components of the fibrinolytic system secreted by the tumor cells themselves are not solely responsible for a correlation between the plasminogen activating system and tumor malignancy; components of the plasminogen activating system secreted by stroma cells or cells of the immune system such as macrophages contribute also to the impact of fibrinolysis on malignancy. This review summarizes the evidence for the role of plasminogen activator inhibitor-1 in mediating the malignant phenotype and possible mechanism thereby trying to explain the "PAI-1 paradox in cancer" on a molecular level.