Investigation of tryptophan to kynurenine degradation in response to interferon-γ in melanoma cell lines

Background and aim

Melanoma is a fatal form of skin cancer that carries a grave prognosis if the cancer cells spread and form metastases. The Kynurenine (Kyn) pathway is activated by the enzyme indoleamine 2,3-dioxygenase 1 (IDO-1) and has been shown to have a role in tumour progression. We have previously shown that interferon-γ (IFN-γ) acts as an inducer of tryptophan (Trp) degradation to Kyn in keratinocytes of the basal layer in a 3D epidermis model. Before extending our reconstructed human epidermis model to not only contain keratinocytes but also fibroblasts and melanocytes/melanoma cells, we have in this study set out to investigate possible differences between primary adult melanocytes and six melanoma cell lines regarding the expression of the immune checkpoint inhibitors IDO-1 and programmed death ligand 1 (PD-L1) together with Kyn production.

Methods

The melanocytes and melanoma cells were stimulated with 1-20 ng/ml of IFN-γ and the levels of Trp to Kyn degradation were monitored with high-performance liquid chromatography (HPLC). To analyze the viability of the cell types after IFN-γ treatment, an MTT assay was performed. mRNA quantity of IDO-1, PD-L1 and IFN-γ receptor (IFN-GR1) was analyzed with qPCR.

Results

After 24 h, only the metastatic cell line WM-266-4 was affected by all concentrations of IFN-γ, whereas at 48 h, the higher IFN-γ concentrations gave a more pronounced effect on the viability in all cell types. Trp was detected at various levels in the culture medium from all cell types before and after IFN-γ treatment. The degradation to Kyn was detected in primary melanocytes, Mel Juso, and Mel Ho cell lines after 24 h of treatment and low levels of IFN-γ. However, the higher concentration of IFN-γ, 20 ng/ml, induced Kyn to various degrees in all cell types after 24 h. The change in mRNA quantity of IDO-1 and PD-L1 was similar in all cell types.

Conclusion

To conclude, no significant difference in upregulation of the immune checkpoint inhibitors PD-L1 and IDO-1 was seen between primary tumour and metastatic melanoma. IFN-γ stimulation of melanocytes and different stages of melanoma cell lines resulted in an increased Kyn/Trp ratio in the more aggressive melanoma cells when a high concentration was used (20 ng/ml) but when a lower concentration of IFN-γ (5 ng/ml) was used an increased Kyn/Trp ratio were detected in media from primary melanocytes and early-stage melanoma.

Manganese as a Possible Anticancer Enhancer in Docetaxel Treatment of Prostate Cancer Cells

BACKGROUND/AIM

Treatment of castration-resistant prostate cancer with docetaxel (DOC) often leads to resistance. In this study, we investigated whether manganese (Mn) has the potential to enhance treatment when combined with DOC.

MATERIALS AND METHODS

PC3 cells were exposed to DOC or Mn individually and in combination and cell viability was analysed in a dose- and time-dependent manner. Cell toxicity, cell cycle analysis and apoptotic protein levels were determined after 48 h of treatment.

RESULTS

Mn in combination with different concentrations of DOC significantly enhanced the inhibitory effect on cell viability. Although the lowest dose did not cause mitotic arrest, DOC increased toxicity, which was reduced when combined with Mn. Protein analyses indicated that Mn compensates for the suppression of death receptors when combined with a low concentration of DOC and induced non-apoptotic pathways when combined with a higher concentration.

CONCLUSION

Combining DOC and Mn may allow for a reduction in DOC concentration with the potential to reduce side effects.

Recent Advances in Molecularly Imprinted Polymers and Their Disease-Related Applications

Molecularly imprinted polymers (MIPs) and the imprinting technique provide polymeric material with recognition elements similar to natural antibodies. The template of choice (i.e., the antigen) can be almost any type of smaller or larger molecule, protein, or even tissue. There are various formats of MIPs developed for different medical purposes, such as targeting, imaging, assay diagnostics, and biomarker detection. Biologically applied MIPs are widely used and currently developed for medical applications, and targeting the antigen with MIPs can also help in personalized medicine. The synthetic recognition sites of the MIPs can be tailor-made to function as analytics, diagnostics, and drug delivery systems. This review will cover the promising clinical applications of different MIP systems recently developed for disease diagnosis and treatment.

Immunosuppression of aquatic organisms exposed to elevated levels of manganese: From global to molecular perspective

Manganese (Mn) is an essential trace metal for all organisms. However, in excess it causes toxic effects but the impact on aquatic environments has so far been highly overlooked. Manganese is abundant both in costal and deep sea sediments and becomes bioavailable (Mn²⁺) during redox conditions. This is an increasing phenomenon due to eutrophication-induced hypoxia and aggravated through the ongoing climate change. Intracellular accumulation of Mn²⁺ causes oxidative stress and activates evolutionary conserved pathways inducing apoptosis and cell cycle arrest. Here, studies are compiled on how excess of dissolved Mn suppresses the immune system of various aquatic organisms by adversely affecting both renewal of immunocytes and their functionality, such as phagocytosis and activation of pro-phenoloxidase. These impairments decrease the animal's bacteriostatic capacity, indicating higher susceptibility to infections. Increased distribution of pathogens, which is believed to accompany climate change, requires preserved immune sentinel functions and Mn can be crucial for the outcome of host-pathogen interactions.

Cell Biology of the Tardigrades: Current Knowledge and Perspectives

The invertebrate phylum Tardigrada has received much attention for containing species adapted to the most challenging environmental conditions where an ability to survive complete desiccation or freezing in a cryptobiotic state is necessary for persistence. Although research on tardigrades has a long history, the last decade has seen a dramatic increase in molecular biological ("omics") studies, most of them with the aim to reveal the biochemical mechanisms behind desiccation tolerance of tardigrades. Several other aspects of tardigrade cell biology have been studied, and we review some of them, including karyology, embryology, the role of storage cells, and the question of whether tardigrades are eutelic animals. We also review some of the theories about how anhydrobiotic organisms are able to maintain cell integrity under dry conditions, and our current knowledge on the role of vitrification and DNA protection and repair. Many aspects of tardigrade stress tolerance have relevance for human medicine, and the first transfers of tardigrade stress genes to human cells have now appeared. We expect this field to develop rapidly in the coming years, as more genomic information becomes available. However, many basic cell biological aspects remain to be investigated, such as immunology, cell cycle kinetics, cell metabolism, and culturing of tardigrade cells. Such development will be necessary to allow tardigrades to move from a nonmodel organism position to a true model organism with interesting associations with the current models C. elegans and D. melanogaster.

Manganese Inhibits Viability of Prostate Cancer Cells

BACKGROUND/AIM

Androgen deprivation therapy is usually in the initial phase a successful treatment for prostate cancer but eventually most patients develop androgen-independent metastatic disease. This study investigated if manganese (Mn) reduces viability of prostate cancer via induction of apoptosis.

MATERIALS AND METHODS

The prostate cancer cell lines PC3, DU145 and LNCaP underwent dose- and time-dependent screening of viability, analyzed by the 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay. Flow cytometry was used for the cell-cycle and apoptosis analyses. Intracellular Mn concentration was measured using inductively coupled plasma-mass spectrometry.

RESULTS

At Mn concentrations of 200-1000 μM, the effect on viability was most pronounced in PC3 followed by LNCaP cells. These cell lines also showed higher intracellular concentration of Mn compared to DU145. In all cell lines, Mn increased the proportion of cells arrested in the G₀/G₁ phase and induced apoptosis.

CONCLUSION

To our knowledge, this is the first report demonstrating Mn as a potential agent in prostate cancer therapy.

Impact of ocean acidification on antimicrobial activity in gills of the blue mussel (Mytilus edulis)

Here, we aimed to investigate potential effects of ocean acidification on antimicrobial peptide (AMP) activity in the gills of Mytilus edulis, as gills are directly facing seawater and the changing pH (predicted to be reduced from ∼8.1 to ∼7.7 by 2100). The AMP activity of gill and haemocyte extracts was compared at pH 6.0, 7.7 and 8.1, with a radial diffusion assay against Escherichia coli. The activity of the gill extracts was not affected by pH, while it was significantly reduced with increasing pH in the haemocyte extracts. Gill extracts were also tested against different species of Vibrio (V. parahaemolyticus, V. tubiashii, V. splendidus, V. alginolyticus) at pH 7.7 and 8.1. The metabolic activity of the bacteria decreased by ∼65-90%, depending on species of bacteria, but was, as in the radial diffusion assay, not affected by pH. The results indicated that AMPs from gills are efficient in a broad pH-range. However, when mussels were pre-exposed for pH 7.7 for four month the gill extracts presented significantly lower inhibit of bacterial growth. A full in-depth proteome investigation of gill extracts, using LC-Orbitrap MS/MS technique, showed that among previously described AMPs from haemocytes of Mytilus, myticin A was found up-regulated in response to lipopolysaccharide, 3 h post injection. Sporadic occurrence of other immune related peptides/proteins also pointed to a rapid response (0.5-3 h p.i.). Altogether, our results indicate that the gills of blue mussels constitute an important first line defence adapted to act at the pH of seawater. The antimicrobial activity of the gills is however modulated when mussels are under the pressure of ocean acidification, which may give future advantages for invading pathogens.

In vitro cytotoxicity evaluation of HDAC inhibitor Apicidin in pancreatic carcinoma cells subsequent time and dose dependent treatment

Apicidin is a potent histone deacetylase inhibitor (HDACI) that selectively binds to histone deacetylases (HDACs) class I and interferes with the deacetylation process, which results in modification of acetylation level of cellular proteins. The aim of the study was to investigate the potential time and dose dependent cytotoxicity of the test compound, Apicidin, in pancreatic cancer cells Capan-1 and Panc-1 as well as estimate maximal tolerable dose (MTD) of the test agent and determine EC50 using four complementary colorimetric cytotoxicity or viability assays. The cells were treated with increasing concentrations of Apicidin (0-5000nM) for 2, 4 and 6h (short term exposure) or 24, 48 and 72h (long term exposure) before conducting cytotoxic analyses with lactate dehydrogenase assay or viability analyses with sulforhodamine B (SRB), methyl tetrazolium (MTT) and crystal violet (CV) assays. In order to investigate whether Apicidin irreversibly affects the cells already during the short term exposure, the medium containing Apicidin was removed and replaced with fresh culturing medium after 6h of treatment. The cells were then incubated for additional 24, 48 or 72h before carrying out the analysis. The results obtained from cytotoxicity and viability assays indicated, that Apicidin was well tolerated by both cell lines at concentrations below 100nM at any given time point and at all applied concentrations during the short term (6h or less) treatment. Continuous prolonged term exposures (48h or greater) of the cells to Apicidin with concentration exceeding 100nM resulted in significantly increasing cytotoxicity and sustained significant loss of cell viability. Moreover, long term exposure of pancreatic cancer cells Capan-1 and Panc-1 to Apicidin concentrations exceeding 100nM showed an initial anti-proliferative effect before cytotoxicity onset. In summary, MTD was exposure time dependent and estimated to 100nM for long term treatment and to at least 5000nM for treatment not greater than 6h. EC50 concentration of Apicidin was established after long term treatment, however with some variation when comparing the different assays and cell lines. Results from this study may encourage reinvestigating the capacity of potent HDACI Apicidin as an attractive agent for interfering with the deacetylation process catalyzed by HDACs for potential pancreatic cancer intervention.

Induction of morphological changes in death-induced cancer cells monitored by holographic microscopy

We are using the label-free technique of holographic microscopy to analyze cellular parameters including cell number, confluence, cellular volume and area directly in the cell culture environment. We show that death-induced cells can be distinguished from untreated counterparts by the use of holographic microscopy, and we demonstrate its capability for cell death assessment. Morphological analysis of two representative cell lines (L929 and DU145) was performed in the culture flasks without any prior cell detachment. The two cell lines were treated with the anti-tumour agent etoposide for 1-3days. Measurements by holographic microscopy showed significant differences in average cell number, confluence, volume and area when comparing etoposide-treated with untreated cells. The cell volume of the treated cell lines was initially increased at early time-points. By time, cells decreased in volume, especially when treated with high doses of etoposide. In conclusion, we have shown that holographic microscopy allows label-free and completely non-invasive morphological measurements of cell growth, viability and death. Future applications could include real-time monitoring of these holographic microscopy parameters in cells in response to clinically relevant compounds.

Role of the protein tyrosine phosphatase SHP-1 in Interleukin-6 regulation of prostate cancer cells

BACKGROUND

Interleukin-6 (IL-6) is a multifunctional cytokine that has been implicated in the modulation of growth and progression of prostate cancer. Decreased expression of the tyrosine phosphatase SHP-1, involved in regulation of cytokine and tyrosine kinase receptor signaling, has been shown to be associated with less favorable outcome among prostate cancer patients.

METHODS

Parental LNCaP cells and an LNCaP-IL6+ subline, derived from parental LNCaP cells by continuous culture of the cells in the presence of recombinant IL-6 were used in the study. Expression of STAT3, pSTAT3, ERK, pERK, AKT, pAKT, PTEN, and SHP-1 was analyzed by immunohistochemistry, Western blots, cDNA microarray, quantitative PCRs, and reverse transcriptase PCRs. Proliferation and apoptosis of transfected cells were analyzed by caspase3/7 assay and flow cytometry.

RESULTS

Phosphorylation of ERK and STAT3 was increased in the LNCaP-IL6+ subline compared with LNCaP cells, whereas pAKT was decreased. Overexpression and inhibition experiments with SHP-1 siRNA showed that SHP-1 reduced proliferation and increased apoptosis in both cell lines. Microarray analysis revealed 80 up-regulated and 87 down-regulated SHP-1-related genes in the LNCaP-IL6+ cell line compared with LNCaP cells.

CONCLUSIONS

SHP-1 suppresses growth and increases apoptosis in both LNCaP and LNCaP-IL6+ cells, which suggests that SHP-1 could be a therapeutic target in prostate cancer, even when there is an IL-6-related growth advantage.

Immunohistochemical detection of tyrosine phosphatase SHP-1 predicts outcome after radical prostatectomy for localized prostate cancer

The protein tyrosine kinase (PTK) receptors and cytosolic signaling proteins as well as the protein tyrosine phosphatases (PTPs) have important roles in regulation of growth of the benign and malignant prostate gland. Here, we studied expression of the protein tyrosine phosphatase SHP-1 in prostate cancer cell lines and in human prostatic tissues. SHP-1 is expressed at a high level in LNCaP prostate cancer cells compared with PC3 cells. Silencing of SHP-1 expression with siRNA in LNCaP cells led to an increased rate of proliferation, whereas overexpression of SHP-1 by means of transient and stable transfection in PC3 cells led to a decrease in proliferation. Corresponding changes were observed in cyclin D1 expression. We further demonstrate that LNCaP and PC3 cells respond differently to IL-6 stimulation. SHP-1 overexpression in PC3 cells reversed IL-6 stimulation of proliferation, whereas in SHP-1-silenced LNCaP cells, IL-6 inhibition of proliferation was not affected. In addition, IL-6 treatment led to higher levels of phosphorylated STAT3 in SHP-1-silenced LNCaP cells than in control cells. Next, SHP-1 expression in human prostate cancer was analyzed by immunohistochemical staining of tissue microarrays comprising tumor specimens from 100 prostate cancer patients. We found an inverse correlation between the tumor level of SHP-1 expression and time to biochemical recurrence and clinical progression among prostate cancer patients. In conclusion, our results suggest that a decreased level of SHP-1 expression in prostate cancer cells is associated with a high proliferation rate and an increased risk of recurrence or clinical progression after radical prostatectomy for localized prostate cancer.

Alpha1-antitrypsin inhibits Moraxella catarrhalis MID protein-induced tonsillar B cell proliferation and IL-6 release

Alpha1-antitrypsin (AAT) is a major circulating and tissues inhibitor of serine proteinases implicated in the regulation of inflammation and host defence. There is now increasing evidence that AAT may also exhibit anti-inflammatory activities independent of its protease inhibitor function. This study was undertaken to investigate the effects of native (inhibitory) and polymerized (non-inhibitory) forms of AAT on MID (Moraxella IgD binding protein)-induced human tonsillar B cell activation in vitro. We found that 0.5 microg/ml MID induces B cell proliferation and stimulates IL-6 release (p<0.001) relative to non-stimulated controls. Both native and polymerized AAT (0.5 mg/ml) inhibited MID-stimulated B cell proliferation in a similar manner (by 70%, p<0.001), whereas MID-induced IL-6 release was more strongly suppressed by polymerized (9.9-fold, p<0.001) as compared to native AAT (2.8-fold, p<0.01). Electrophoretic analysis of cell culture media did not indicate any interaction between AAT and MID, and flow cytometry data showed no competition for the same receptor. The effects of AATs were observed whether added together with MID or 2h after MID-addition to cell cultures. Thus, our data demonstrate that AAT inhibits MID-induced B cell activation in vitro that is unrelated to its protease inhibitory activity and is not dependent on MID binding to the cell surface.