Acquisition of an enhanced aggressive phenotype in human lung cancer cells selected by suboptimal doses of cisplatin following cell deattachment and reattachment

Clinical importance of serum and pleural fluid prominin-1 and hypoxia-inducible factor-1α concentration in the evaluation of lymph node involvement in patients with malignant pleural effusion

Introduction

Malignant pleural effusion (MPE) and lymph node metastasis (LNM) presence are poor prognostic factors that have importance for cancer patients. The study objective was to determine whether hypoxia-inducible factor-1α (HIF-1α) and prominin-1 (CD133) in pleural fluid (P) and serum (S) could be used as biomarkers for diagnosis of lymph node involvement in patients with MPE.

Materials and methods

Fifty-six patients with MPE and 30 healthy control subjects were included. Computerized tomography (CT) and positron emission tomography (PET) were used to diagnose pleural effusion. Patients with malignant cells in pleural fluid cytological examination were included in the MPE group. Thirty-five patients with lymph node metastases on CT were included in the LNM-positive MPE group. Serum and pleural fluid HIF-1α and CD-133 concentrations were measured manually via enzyme-linked immunosorbent assay (ELISA).

Results

Serum concentrations of HIF-1α and CD133 were higher in MPE patients. It was found that CD133/HIF-1α (S) ratio was higher in the malignant patient group with positive lymph node involvement than in the negative group, while concentrations of HIF-1α (P) were lower. Pleural fluid HIF-1α and CD133/HIF-1α (S) ratio had sufficient performance in diagnosing lymphatic metastases in patients with MPE (AUC = 0.90 and 0.83, respectively).

Conclusions

In conclusion, serum HIF-1α and CD133 concentrations were higher in patients with MPE, consistent with our hypothesis. Concentrations of HIF-1α (P) and CD133/HIF-1α (S) ratio can be used as biomarkers in diagnosing lymph node involvement in MPE patients, according to this experiment.

Metal- and metalloid-based compounds to target and reverse cancer multidrug resistance

Drug resistance remains the major cause of cancer treatment failure especially at the late stage of the disease. However, based on their versatile chemistry, metal and metalloid compounds offer the possibility to design fine-tuned drugs to circumvent and even specifically target drug-resistant cancer cells. Based on the paramount importance of platinum drugs in the clinics, two main areas of drug resistance reversal strategies exist: overcoming resistance to platinum drugs as well as multidrug resistance based on ABC efflux pumps. The current review provides an overview of both aspects of drug design and discusses the open questions in the field. The areas of drug resistance covered in this article involve: 1) Altered expression of proteins involved in metal uptake, efflux or intracellular distribution, 2) Enhanced drug efflux via ABC transporters, 3) Altered metabolism in drug-resistant cancer cells, 4) Altered thiol or redox homeostasis, 5) Altered DNA damage recognition and enhanced DNA damage repair, 6) Impaired induction of apoptosis and 7) Altered interaction with the immune system. This review represents the first collection of metal (including platinum, ruthenium, iridium, gold, and copper) and metalloid drugs (e.g. arsenic and selenium) which demonstrated drug resistance reversal activity. A special focus is on compounds characterized by collateral sensitivity of ABC transporter-overexpressing cancer cells. Through this approach, we wish to draw the attention to open research questions in the field. Future investigations are warranted to obtain more insights into the mechanisms of action of the most potent compounds which target specific modalities of drug resistance.

Inhibition of Wnt/β-catenin pathway reverses multi-drug resistance and EMT in Oct4+/Nanog+ NSCLC cells

Cancer drug resistance and epithelial-mesenchymal transition (EMT), a critical process of cancer invasion and metastasis, have recently been associated with the existence of cancer stem cells (CSCs). However, there are no appropriate CSC-markers of non-small cell lung cancer (NSCLC)-associated drug resistance and EMT. It is unknown if and how the drug-resistant and EMT phenotypes in NSCLC cells link to specific stemness-related pathways. Here, we found a significant elevated expression of both Oct4 and Nanog in gefitinib-resistant NSCLC cells, which displayed multi-drug resistance (MDR) properties and exhibited EMT phenotype. Ectopic co-expression of Oct4/Nanog empowered NSCLC cells with cancer stem cell properties, including self-renewal, drug resistance, EMT and high tumorigenic capacity. Following molecular mechanism investigation indicated Oct4/Nanog-regulated drug resistance and EMT change through Wnt/β-catenin signaling activation. Moreover, silencing β-catenin abrogated Oct4/Nanog-mediated MDR and EMT process in NSCLC cells. Our findings propose Wnt/β-catenin pathway as a promising therapeutic target for the treatment of progression and metastasis of NSCLC with CSC-like signatures and epithelial-mesenchymal transition phenotype.

Oct4 upregulates osteopontin via Egr1 and is associated with poor outcome in human lung cancer

Background

Roles of cancer stem cells and early growth response gene 1 (Egr1) in carcinogenesis have been extensively studied in lung cancer. However, the role of Egr1 in the metastasis of lung cancer remains undetermined, especially in regard to stem cell-related pathways.

Methods

Egr1, osteopontin (OPN) and Oct4 expression in human lung cancer was determined by performing immunohistochemistry. Immunoblotting, ELISA, luciferase reporter assay, chromatin immunoprecipitation assay and RT-PCR were performed to validate the regulation of Oct4-Egr1-OPN axis. Moreover, the effect of Oct4-Egr1-OPN axis on lung cancer progression was evaluated by cell migration assay and mice study.

Results

We detected Oct4, Egr1, and OPN expression in clinical specimens from 79 lung cancer patients, including 72 adenocarcinomas and 7 squamous cell carcinomas. High expression of Oct4, Egr1, and OPN accounted for 53, 51, and 57% of the patients, respectively. All of the three biomarkers were positively correlated in clinical human lung cancer. Patients with high expression of OPN were significantly associated with shorter disease-free survivals than those with low expression of OPN (p < 0.05). In lung cancer cells, Oct4 transactivated the Egr1 promoter and upregulated Egr1 expression. In a human lung cancer xenograft model, Oct4-overexpressing tumors expressed elevated levels of Egr1. Furthermore, overexpression of Oct4 in lung cancer cells increased the metastatic potential.

Conclusions

Egr1 exerts a promoting effect on cancer metastasis in Oct4-overexpressing lung cancer. Thus, therapeutic strategies targeting the Oct4/Egr1/OPN axis may be further explored for the treatment of lung cancer, especially when lung cancer is refractory to conventional treatment due to cancer stem cells.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-6014-5) contains supplementary material, which is available to authorized users.

Chemotherapeutics-induced Oct4 expression contributes to drug resistance and tumor recurrence in bladder cancer

Cancer cells initially characterized as sensitive to chemotherapy may acquire resistance to chemotherapy and lead to tumor recurrence through the expansion of drug-resistant population. Acquisition of drug resistance to conventional chemotherapy is a major obstacle in the treatment of recurrent cancer. Here we investigated whether anticancer drugs induced Oct4 expression, thereby contributing to acquired drug resistance and tumor recurrence in bladder cancer. We identified a positive correlation of Oct4 expression with tumor recurrence in 122 clinical specimens of superficial high-grade (stages T1-2) bladder transitional cell carcinoma (TCC). Increased Oct4 levels in bladder tumors were associated with short recurrence-free intervals in the patients. Chemotherapy induced Oct4 expression in bladder cancer cells. Notably, treatment with cisplatin increased CD44-positive bladder cancer cells expressing Oct4, representing cancer stem-like cell subpopulation. Forced expression of Oct4 reduced, whereas knockdown of Oct4 enhanced, drug sensitivity in bladder cancer cells. Furthermore, tumor cells overexpressing Oct4 responded poorly to cisplatin in vivo. In regard to clinical relevance, inhibition of Oct4 by all-trans retinoic acid (ATRA) synergistically increased sensitivity to cisplatin in bladder cancer cells. Furthermore, the combination of cisplatin and ATRA was superior to cisplatin alone in suppressing tumor growth. Therefore, our results provide evidence that Oct4 increases drug resistance and implicate that inhibition of Oct4 may be a therapeutic strategy to circumvent drug resistance.

Dynamic proteomics reveals bimodal protein dynamics of cancer cells in response to HSP90 inhibitor

BACKGROUND

Drugs often kill some cancer cells while others survive. This stochastic outcome is seen even in clonal cells grown under the same conditions. Understanding the molecular reasons for this stochastic outcome is a current challenge, which requires studying the proteome at the single cell level over time. In a previous study we used dynamic proteomics to study the response of cancer cells to a DNA damaging drug, camptothecin. Several proteins showed bimodal dynamics: they rose in some cells and decreased in others, in a way that correlated with eventual cell fate: death or survival. Here we ask whether bimodality is a special case for camptothecin, or whether it occurs for other drugs as well. To address this, we tested a second drug with a different mechanism of action, an HSP90 inhibitor. We used dynamic proteomics to follow 100 proteins in space and time, endogenously tagged in their native chromosomal location in individual living human lung-cancer cells, following drug administration.

RESULTS

We find bimodal dynamics for a quarter of the proteins. In some cells these proteins strongly rise in level about 12 h after treatment, but in other cells their level drops or remains constant. The proteins which rise in surviving cells included anti-apoptotic factors such as DDX5, and cell cycle regulators such as RFC1. The proteins that rise in cells that eventually die include pro-apoptotic factors such as APAF1. The two drugs shared some aspects in their single-cell response, including 7 of the bimodal proteins and translocation of oxidative response proteins to the nucleus, but differed in other aspects, with HSP90i showing more bimodal proteins. Moreover, the cell cycle phase at drug administration impacted the probability to die from HSP90i but not camptothecin.

CONCLUSIONS

Single-cell dynamic proteomics reveals sub-populations of cells within a clonal cell line with different protein dynamics in response to a drug. These different dynamics correlate with cell survival or death. Bimodal proteins which correlate with cell fate may be potential drug targets to enhance the effects of therapy.

IL-6 signaling contributes to cisplatin resistance in non-small cell lung cancer via the up-regulation of anti-apoptotic and DNA repair associated molecules

Cisplatin-based chemotherapy is currently the most effective treatment regimen for non-small cell lung cancer (NSCLC), but eventually tumor resistance develops which limits its success. The potential implication of IL-6 signaling in the cisplatin resistance of NSCLC was explored by testing whether NSCLC cells with different levels of intracellular IL-6 show different responses to the cytotoxic treatment of cisplatin. When the cisplatin cytotoxicity of the IL-6 knocked down human NSCLC cells (A549IL-6si and H157IL-6si) were compared with their corresponding scramble control cells (A549sc and H157sc), higher cisplatin cytotoxicity was found in IL-6 si cells than sc cells. Subcutaneous xenograft mouse models were developed using a pair of A549sc and A549IL-6si cells. When the tumor grew to about 400 mm2, mice were treated with cisplatin and tumor regression was monitored. Higher tumor regression was detected in the A549IL-6si xenografts compared to A549sc xenografts following cisplatin treatment. Immunostaining study results from tumor tissues also supported this finding. Expression of anti-apoptotic proteins Bcl-2 and Mcl-1 and DNA repair associated molecules ATM, CHK1, TP73, p53, and ERCC1 were significantly up regulated in cisplatin-treated A549sc and H157sc cells, but no increase was detected in A549IL-6si and H157IL-6si cells. Further inhibitor studies revealed that up regulation of these molecules by IL-6 may be through activation of IL-6 downstream signaling pathways like Akt, MAPK, Stat3, and Erk. These results provide potential for combining cisplatin and inhibitors of IL-6 signaling or its downstream signaling pathway as a future therapeutic approach in preventing development of cisplatin resistant NSCLC tumors.

Photodynamic therapy with 5-aminolaevulinic acid and DNA damage: unravelling roles of p53 and ABCG2

OBJECTIVES

In spite of high sensitivity of A549 cells (p53(+/+) ) to lethal effects of photodynamic therapy with 5-aminolaevulinic acid (5-ALA/PDT), DNA damage was observed only in H1299 cells (p53(-/-) ), suggesting that p53 may exert a protective effect. Studies on human colon adenocarcinoma cell lines HCT-116, and their cognate knockouts for p53, were not entirely consistent with the assumption above. Exploring alternative explanations for such conflicting behaviour, we observed that expression of the ATP-binding cassette G2 (ABCG2), a regulator of cell component efflux, had important effects on PDT-generated DNA injury in PC3 cells (prostate) which are p53(-/-) and positive for ABCG2. Addition of an ABCG2 inhibitor in ABCG2 positive A549 (p53(+/+) ) and PC3 (p53(-/-) ) cells eliminated resistance to DNA damage.

MATERIALS AND METHODS

All cell lines investigated were incubated with 5-ALA and irradiated. Effects of PDT were evaluated assessing residual cell viability, cell-cycle profiles, PpIX localization, comet assay and Western blotting. Identical measurements were made in the presence of ABCG2 inhibitor, in cells expressing the transporter.

RESULTS

Our data show that cell aptitude to defend its DNA from PDT-induced injury was mainly ruled by ABCG2 expression. These findings, while providing helpful information in predicting effectiveness of 5-ALA/PDT, may indicate a way to shift PDT from a palliative to a more effective approach in anti-cancer therapy.

Therapy-induced enrichment of putative lung cancer stem-like cells

Tumour drug resistance is a major issue in the management of lung cancer patients as almost all lung tumours are either intrinsically resistant or quickly develop acquired resistance to chemotherapeutic drugs. Cancer drug resistance has recently been linked, at least in part, to the existence of cancer stem-like cells (CSLCs), a small sub-population of cells within the tumour that possess stem-like properties. CSLCs are often isolated by fluorescence activated cell sorting (FACS) according to the expression of certain stem-like cell membrane markers. Conflicting results regarding the specificity of particular stem cell surface markers for isolating CSLCs have, however, been recently reported. Therefore, alternative strategies enabling the identification and study of CSLCs should be considered, particularly in tumour types where appropriate stem cell markers are not well established and validated, like in lung cancer. In this article, we review data indicating therapy-selection as a valid approach for putative lung CSLCs enrichment. We believe that this strategy would be determinant for correctly assessing and characterising the sub-populations of CSLCs that are able to survive chemo or radiotherapy regimens and, at the same time, also have the ability to recapitulate and sustain tumour growth. Using therapy-induced enrichment of CSLCs may, therefore, prove to be an extremely useful method for studying CSLCs and provide new clues regarding potential therapeutic targets for their efficient elimination, which will undoubtedly play a decisive role in improving lung cancer patients' survival.

Cell trivision of hyperploid cells

Malignant transformation is likely to render cells hyperploid, primarily tetraploid. We have measured the frequency of division into three rather than two daughter cells as a function of ploidy. Such trivisions were followed in near-tetraploid uveal melanoma (UM), hypotetraploid HaCaT (<4 N), hypertriploid HeLa (>3 N), and in near-diploid (∼2 N) lung epithelial cell lines by time-lapse image analyses. A stepwise analysis of cytokinesis revealed higher frequency of cell trivisions relative to divisions in hyperploid HeLa (1:24, 4%), HaCaT (1:126, 8%), and UM (1:186, 0.5%) cells. The occurrence of trivision was significantly lower in near-diploid endothelial cells (1:1400, 0.07%). We have previously observed the phenomenon of trivision in HaCaT cells treated with heavy metal lead, and here we describe that trivision is a spontaneous process taking place without genotoxic treatment. Beside re-diploidization by trivision, the hyperploid state decreases the cell size of the daughter cells and is likely to increase the time of cytokinesis. On the basis of the results, it is hypothesized that among other cancer-related causes, hyperploidy could be related to cell trivision, could cause random aneuploidy, and could generate new cancer-specific karyotypes.

5-aminolaevulinic acid/photo-dynamic therapy and gefitinib in non-small cell lung cancer cell lines: a potential strategy to improve gefitinib therapeutic efficacy

OBJECTIVES

Often, non-small cell lung cancers (NSCLC) respond only poorly to the tyrosine kinase inhibitor (TKI) gefitinib, which targets the epidermal growth factor receptor (EGFR), these poor responders EGFRs lacking activating mutations. In this study, we have attempted to improve TKI response of NSCLC cell lines (A549 and H1299) devoid of EGFR mutations, by combination of gefitinib and 5-ALA/photodynamic therapy (PDT).

MATERIALS AND METHODS

Cells of the two lines were incubated with gefitinib (from 0.5 to 50 mm, for 48 h) then irradiated at doses ranging from 4 to 20 J/cm(2) ; 5-ALA concentration and incubation time were kept constant (1 mm for 3 h). We analysed cell viability, colony-forming efficiency, cell cycle parameters, proteasome and NF-κB activity and expression patterns of specific proteins, after individual or combined treatments.

RESULTS

Effects (antagonistic, additive or synergistic) of combination treatment were evaluated using a predictive model (combination index) for expected interactive effects and results are consistent with mutual potentiation exceeding simple additivity. Investigation of molecular mechanisms underlying cytotoxic effects indicated that combination treatment impaired proteasome function, inhibited NF-κB transcriptional activity and hampered AKT pro-survival signalling.

CONCLUSIONS

The results of this study show that poor response of cells devoid of EGFR activating mutations to TKIs, can be overcome by combining gefitinib with 5-ALA/photodynamic therapy (PDT).

A novel serum protein signature associated with resistance to epidermal growth factor receptor tyrosine kinase inhibitors in head and neck squamous cell carcinoma

BACKGROUND

Acquired resistance to tyrosine kinase inhibitors (TKIs) is becoming a major challenge in the treatment of many cancers. Epidermal growth factor receptor (EGFR) is overexpressed in squamous carcinomas, notably those of the head and neck (HNSCC), and can be targeted with several TKIs. We aimed to identify soluble proteins suitable for development as markers of EGFR TKI resistance in cancer patients to aid in early and minimally invasive assessment of therapeutic responses.

METHODS

Resistant HNSCC cell lines were generated by exposure to an EGFR TKI, gefitinib, in vitro. Cell lines were characterised for their biological behaviour in vitro (using growth inhibition assays, flow cytometry, western blots, antibody arrays and/or immunoassays) and in vivo (using subcutaneous tumour xenografts). Sera from EGFR-treated and -untreated HNSCC patients were analysed by immunoassay.

RESULTS

Two independent sublines of CAL 27 and a PJ34 subline with acquired resistance to EGFR TKIs (gefitinib, erlotinib and afatinib) were developed. Resistant cells grew as highly aggressive xenografts leading to reduced host survival rates compared with EGFR-TKI sensitive cells. This suggested a link between resistance in vitro and poor prognosis in vivo. A significant upregulation of proteins linked to tumour angiogenesis and invasion was identified in resistant cells. This 'resistance-associated protein signature' (RAPS) was detected in the sera of a small cohort of HNSCC patients and was associated with reduced survival.

CONCLUSION

We have identified a protein signature associated with EGFR-TKI resistance that may also be linked to poor prognosis and warrants further investigation as a potential clinical biomarker.