Molecular mechanisms behind the resistance of cisplatin in germ cell tumours

Glycan signatures for the identification of cisplatin‐resistant testicular cancer cell lines: Specific glycoprofiling of human chorionic gonadotropin (hCG)

Background

Testicular cancer (TC) is the most frequent type of cancer among young men aged between 15 and 34 years. TC is treated using cisplatin, but 3%–5% of TC patients fail to respond to cisplatin, with a very bad to fatal prognosis. Accordingly, it is most important to quickly and readily identify those TC patients who are resistant to cisplatin treatment.

Methods

This study seeks to investigate changes in the glycosylation associated with cisplatin resistance to TC cell lines.

Results

A specific glycoprofiling of human chorionic gonadotropin (hCG) was analysed in three TC cell lines and one cell line of female origin. A typical calibration curve for hCG glycoprofiling showed a dynamic range up to 50 ng/ml, with a limit of detection of 0.3 ng/ml and assay reproducibility represented by relative standard deviation of 3.0%. Changes in the glycan signatures on hCG were analysed in cisplatin‐sensitive cell lines and in their cisplatin‐resistant sub‐lines using an enzyme‐linked lectin assay (ELLA) protocol. An immobilised antibody was applied to a selective capture of hCG from a cytoplasmic fraction of cell lysates with final incubation using a lectin from a panel of 17 lectins.

Conclusion

The results suggest that one particular lectin Dolichos biflorus agglutinin (DBA) can selectively discriminate sensitive TC cell lines from resistant TC cell lines. Moreover, there are additional lectins which can provide useful information about the strength of cisplatin resistance.

Molecular Biology of Pediatric and Adult Male Germ Cell Tumors

Simple Summary

Although testicular germ cell tumors (TGCTs) are rare pediatric malignancies, they are the most common malignancies in young adult men. The similarities and differences between TGCTs in adults and children, taking into account the clinic presentation, biology, and molecular changes, are underexplored. In this paper, we aim to provide an overview of the molecular aspects of TGCTs, drawing a parallel between the findings in adult and pediatric groups.

Abstract

Cancer is a leading cause of death by disease in children and the second most prevalent of all causes in adults. Testicular germ cell tumors (TGCTs) make up 0.5% of pediatric malignancies, 14% of adolescent malignancies, and are the most common of malignancies in young adult men. Although the biology and clinical presentation of adult TGCTs share a significant overlap with those of the pediatric group, molecular evidence suggests that TGCTs in young children likely represent a distinct group compared to older adolescents and adults. The rarity of this cancer among pediatric ages is consistent with our current understanding, and few studies have analyzed and compared the molecular basis in childhood and adult cancers. Here, we review the major similarities and differences in cancer genetics, cytogenetics, epigenetics, and chemotherapy resistance between pediatric and adult TGCTs. Understanding the biological and molecular processes underlying TGCTs may help improve patient outcomes, and fuel further investigation and clinical research in childhood and adult TGCTs.

Evaluation of Chemotherapeutic Drugs for Treatment of (Cisplatin-Resistant) Germ Cell Cancer Cell Lines

Cisplatin resistance still remains a major obstacle in the standard chemotherapeutic approach in late-stage and metastatic testicular germ cell cancer (GCC) patients. This multifactorial and complex phenomenon arises (concomitantly) on several levels due to impaired transport, decreased adduct formation, increased DNA-repair, decreased apoptosis, or compensating pathways. Evaluation of novel therapeutic approaches and pharmacological inhibitors still remains necessary to treat cisplatin-resistant GCCs. In this chapter, we present in vitro techniques to measure cytotoxic impacts of chemotherapeutic drugs on GCC cell lines. Specifically, we will discuss the measurement of relative cell viability by XTT assay, as well as cell cycle distribution and apoptosis assay by Nicoletti- and Annexin V/PI apoptosis assay with subsequent flow cytometry, respectively, to evaluate the effects of cytotoxic treatment in GCC cell lines.

Acquisition of Cisplatin Resistance Shifts Head and Neck Squamous Cell Carcinoma Metabolism toward Neutralization of Oxidative Stress

Background: Cisplatin (CDDP) is commonly utilized in the treatment of advanced solid tumors including head and neck squamous cell carcinoma (HNSCC). Cisplatin response remains highly variable among individual tumors and development of cisplatin resistance is common. We hypothesized that development of cisplatin resistance is partially driven by metabolic reprogramming. Methods: Using a pre-clinical HNSCC model and an integrated approach to steady state metabolomics, metabolic flux and gene expression data we characterized the interaction between cisplatin resistance and metabolic reprogramming. Results: Cisplatin toxicity in HNSCC was driven by generation of intra-cellular oxidative stress. This was validated by demonstrating that acquisition of cisplatin resistance generates cross-resistance to ferroptosis agonists despite the fact that cisplatin itself does not trigger ferroptosis. Acquisition of cisplatin resistance dysregulated the expression of genes involved in amino acid, fatty acid metabolism and central carbon catabolic pathways, enhanced glucose catabolism and serine synthesis. Acute cisplatin exposure increased intra-tumoral levels of S-methyl-5-thiadenosine (MTA) precursors and metabotoxins indicative of generalized oxidative stress. Conclusions: Acquisition of cisplatin resistance is linked to metabolic recovery from oxidative stress. Although this portends poor effectiveness for directed metabolic targeting, it supports the potential for biomarker development of cisplatin effectiveness using an integrated approach.

The Warburg Effect Is Associated With Tumor Aggressiveness in Testicular Germ Cell Tumors

Testicular Germ Cell Tumors (TGCTs) are a rare group of neoplasms and the most common solid malignancy arising in young male adults. Despite the good response of these tumors to platinum-based chemotherapy, some patients are refractory to treatment and present poor clinical outcomes. During carcinogenesis and tumor development, cancer cells reprogram energy metabolism toward a hyper-glycolytic phenotype, an emerging hallmark of cancer. This phenomenon, known as the Warburg effect or aerobic glycolysis, involves overexpression of metabolism-related proteins, like glucose and monocarboxylate transporters, pH regulators and intracellular glycolytic enzymes. The metabolic profile of TGCTs is very little explored and, recently, this metabolic rewiring of cancer cells has been associated with aggressive clinicopathological characteristics of these tumors. The overexpression of monocarboxylate transporter 4 (MCT4) in TGCTs has been pointed out as a poor prognostic factor, as well as a promising therapeutic target. As a result, the main aim of the present study was to evaluate the prognostic value of key metabolism-related proteins in TGCTs. The immunohistochemical expressions of CD44 (as a monocarboxylate transporter chaperone), glucose transporter 1 (GLUT1), carbonic anhydrase IX (CAIX), hexokinase II (HKII) and lactate dehydrogenase V (LDHV) were evaluated in a series of 148 adult male patients with TGCTs and associated with clinicopathological parameters. In addition, paired normal tissues were also evaluated. The sample included 75 seminoma and 73 non-seminoma tumors. GLUT1 and CD44 expression was significantly increased in malignant samples when compared to paired normal samples. Conversely, HKII and LDHV expressions were significantly decreased in malignant samples. Concerning the clinicopathological values, CAIX expression was significantly associated with disease recurrence, while HKII expression was significantly associated with aggressive characteristics of TGCTs, including higher staging and non-seminoma histology. In conclusion, this study brings new insights on the metabolic characteristics of TGCTs, showing alterations in the expression of proteins related with the Warburg effect, as well as associations of the hyper-glycolytic and acid-resistant phenotype with aggressive clinicopathological parameters.

Metformin synergistically enhances antitumor activity of cisplatin in gallbladder cancer via the PI3K/AKT/ERK pathway

Metformin (Met) is a widely used antidiabetic drug and has demonstrated interesting anticancer effects in various cancer models, alone or in combination with chemotherapeutic drugs. The aim of the present study is to investigate the synergistic effect of Met with cisplatin (Cis) on the tumor growth inhibition of gallbladder cancer cells (GBC-SD and SGC-996) and explore the underlying mechanism. Cells were treated with Met and/or Cis and subjected to cell viability, colony formation, apoptosis, cell cycle, western blotting, xenograft tumorigenicity assay and immunohistochemistry. The results demonstrated that Met and Cis inhibited the proliferation of gallbladder cancer cells, and combination treatment with Met and Cis resulted in a combination index < 1, indicating a synergistic effect. Co-treatment with Met and Cis caused G0/G1 phase arrest by upregulating P21, P27 and downregulating CyclinD1, and induced apoptosis through decreasing the expression of p-PI3K, p-AKT, and p-ERK. In addition, pretreatment with a specific AKT activator (IGF-1) significantly neutralized the pro-apoptotic activity of Met + Cis, suggesting the key role of AKT in this process. More importantly, in nude mice model, Met and Cis in combination displayed more efficient inhibition of tumor weight and volume in the SGC-996 xenograft mouse model than Met or Cis alone. Immunohistochemistry analysis suggests the combinations greatly suppressed tumor proliferation, which is consistent with our in vitro results. In conclusion, our findings indicate that the combination therapy with Met and Cis exerted synergistic antitumor effects in gallbladder cancer cells through PI3K/AKT/ERK pathway, and combination treatment with Met and Cis would be a promising therapeutic strategy for gallbladder cancer patients.

Exploring the molecular aspects associated with testicular germ cell tumors: a review

Testicular germ cell tumors (TGCTs) represent the most common solid tumors affecting young men. They constitute a distinct entity because of their embryonic origin and their unique biological behavior. Recent preclinical data regarding biological signaling machinery as well as genetic and epigenetic mechanisms associated with molecular patterns of tumors have contribute to explain the pathogenesis and the differentiation of TGCTs and to understand the mechanisms responsible for the development of resistance to treatment. In this review, we discuss the main genetic and epigenetic events associated with TGCTs development in order to better define their role in the pathogenesis of these tumors and in cisplatin-acquired resistance.

Inhibition of the EGFR/STAT3/CEBPD Axis Reverses Cisplatin Cross-resistance with Paclitaxel in the Urothelial Carcinoma of the Urinary Bladder

PURPOSE

Cisplatin (CDDP) is frequently used in combination chemotherapy with paclitaxel for treating urothelial carcinoma of the urinary bladder (UCUB). CDDP cross-resistance has been suggested to develop with paclitaxel, thus hindering successful UCUB treatment. Therefore, elucidating the mechanisms underlying CDDP-induced anticancer drug resistance is imperative and may provide an insight in developing novel therapeutic strategy.

EXPERIMENTAL DESIGN

Loss-of-function assays were performed to elucidate the role of the EGFR and STAT3 in CDDP-induced CCAAT/enhancer-binding protein delta (CEBPD) expression in UCUB cells. Reporter and in vivo DNA-binding assays were employed to determine whether CEBPD directly regulates ATP binding cassette subfamily B member 1 (ABCB1) and ATP binding cassette subfamily C member 2 (ABCC2) activation. Finally, a xenograft animal assay was used to examine the abilities of gefitinib and S3I-201 (a STAT3 inhibitor) to reverse CDDP and paclitaxel sensitivity.

RESULTS

CEBPD expression was maintained in postoperative chemotherapy patients, and this expression was induced by CDDP even in CDDP-resistant UCUB cells. Upon CDDP treatment, CEBPD activated ABCB1 and ABCC2. Furthermore, the EGFR/STAT3 pathway contributed to CDDP-induced CEBPD expression in UCUB cells. Gefitinib and S3I-201 treatment significantly reduced the expression of CEBPD and enhanced the sensitivity of CDDP-resistant UCUB cells to CDDP and paclitaxel.

CONCLUSIONS

Our results revealed the risk of CEBPD activation in CDDP-resistant UCUB cells and suggested a therapeutic strategy for patients with UCUB or UCUB resisted to CDDP and paclitaxel by combination with either gefitinib or S3I-201. Clin Cancer Res; 23(2); 503-13. ©2016 AACR.

Nanoparticle modulation of the tumor microenvironment enhances therapeutic efficacy of cisplatin

The tumor microenvironment (TME) serves as a multidrug resistant center for tumors under the assault of chemotherapy and a physiological barrier against the penetration of therapeutic nanoparticles (NPs). Previous studies have indicated the ability for therapeutic NP to distribute into, and deplete tumor-associated fibroblasts (TAFs) for improved therapeutic outcomes. However, a drug resistant phenotype gradually arises after repeated doses of chemotherapeutic NP. Herein, the acquisition of drug resistant phenotypes in the TME after repeated cisplatin NP treatment was examined. Particularly, this study was aimed at investigating the effects of NP damaged TAFs on neighboring cells and alteration of stromal structure after cisplatin treatment. Findings suggested that while off-targeted NP damaged TAFs and inhibited tumor growth after an initial dose, chronic exposure to cisplatin NP led to elevated secretion of Wnt16 in a paracrine manner in TAFs. Wnt16 upregulation was then attributed to heightened tumor cell resistance and stroma reconstruction. Results attest to the efficacy of Wnt16 knockdown in damaged TAFs as a promising combinatory strategy to improve efficacy of cisplatin NP in a stroma-rich bladder cancer model.

Association of metallothionein expression and clinical response to cisplatin based chemotherapy in testicular germ cell tumors

INTRODUCTION

The protective roles of metallothioneins (MT) against metal toxicity suggest that MT may have a functional role in cisplatin resistance. The aim of this study was to investigate the expression of MT in specimens of germ cell tumors and compare it with clinical sensitivity to cisplatin based chemotherapy.

MATERIAL AND METHODS

Tissue blocks of primary GCT specimens obtained from 39 patients were examined immunohistochemically for MT expression. Staining intensity was evaluated according to the percentage of MT positive cells and graded as [-], [+] and [++]. The staining characteristics were compared with the clinical response to chemotherapy.

RESULTS

Of the 39 tumors, 3 evidenced no MT expression while 26 and 10 specimens showed [+] and [++] staining, respectively. Although seminomas tend to stain weaker than non-seminomas, the difference of staining between them was not significant (p = 0.19). Of the 39 patients, 23 underwent cisplatin based chemotherapy. Of those, 6 progressed and 17 achieved complete remission. Of the non-responders, 5 showed [+] and 1 showed [++] staining. Six of the responders showed [+], 10 had [++] and 1 showed no staining. No association was found between MT staining and chemo-sensitivity (p = 0.53).

CONCLUSIONS

MT expression in primary germ cell tumors did not differ between responding and non-responding patients and therefore may not be useful in predicting response to chemotherapy.

Thioredoxin and glutaredoxin-mediated redox regulation of ribonucleotide reductase

Ribonucleotide reductase (RNR), the rate-limiting enzyme in DNA synthesis, catalyzes reduction of the different ribonucleotides to their corresponding deoxyribonucleotides. The crucial role of RNR in DNA synthesis has made it an important target for the development of antiviral and anticancer drugs. Taking account of the recent developments in this field of research, this review focuses on the role of thioredoxin and glutaredoxin systems in the redox reactions of the RNR catalysis.

The PDGFRβ-AKT pathway contributes to CDDP-acquired resistance in testicular germ cell tumors

PURPOSE

We examined whether PI3K-AKT or extracellular signal-regulated kinase (ERK) signaling pathways could play a role in the development of cisplatin (CDDP) resistance in testicular germ cell tumor (TGT) cells.

EXPERIMENTAL DESIGN

We compared AKT and ERK activation levels in CDDP-sensitive testicular tumor cells and in their corresponding CDDP-resistant-derived cells. We also analyzed these pathways in orthotopic testicular tumors and human patient samples.

RESULTS

Our results indicated that there was overactivation of AKT in CDDP-resistant cells compared with sensitive cells, but no effect on activated ERK levels. We observed an increase in mRNA and protein levels for platelet-derived growth factor (PDGF) receptor β and PDGF-B ligand. These were responsible for AKT overactivation in CDDP-resistant cells. When PDGFRβ levels were decreased by short hairpin RNA (shRNA) treatment or its activation was blocked by pazopanib, CDDP-resistant cells behaved like sensitive cells. Moreover, CDDP-resistant cells were more sensitive to incubation with PDGFRβ inhibitors such as pazopanib or sunitinib than sensitive cells, a finding consistent with these cells being dependent on this signaling pathway. We also found overexpression of PDGFRβ and pAKT in CDDP-resistant choriocarcinoma orthotopic tumor versus their CDDP-sensitive counterparts. Finally, we found high PDGFRβ levels in human testicular tumors, and overexpression in CDDP-resistant testicular choriocarcinomas compared with the CDDP-sensitive and nontreated tumors.

CONCLUSIONS

The PDGFRβ-AKT pathway plays a critical role in the development of CDDP resistance in testicular tumoral cells.

Germ cell cancer presenting as gastrointestinal bleeding and developing brain metastases: case report and review of the literature

This paper describes a rare case of germ cell cancer with duodenum, brain and lung metastases. The patient presented with melena and left testicle enlargement. Orchiectomy revealed mixed germ cell cancer, enteroscopy revealed duodenal choriocarcinoma, and chest x-ray and computed tomography (CT) showed bilateral lung metastases. The patient received and tolerated cisplatinum-based chemotherapy, and responded well. However, he developed seizures 3 months later. MRI showed brain metastases and he was treated with whole-brain radiation. One month later, he developed progressive dyspnea. Chest CT showed worsening lung metastases. He received second-line chemotherapy, but died due to multiorgan failure. Germ cell cancer with nonpulmonary metastases has poor prognosis and the management of these patients requires a multimodal approach. Head CT should be considered as routine screening for all germ cell cancer patients on initial diagnosis and brain MRI should be considered for high-risk patients (with an embryo- or choriocarcinoma histology, dramatically elevated β-human chorionic gonadotropin and lung involvement).

The physical and chemical stability of cisplatin (Teva) in concentrate and diluted in sodium chloride 0.9%

Aim of the study

The subject of study was the stability of cisplatin in concentrate in glass vials and diluted in polyethylene (PE) bags stored at 15–25°C for up to 30 days.

Material and methods

Original vials of cisplatin injection (1 mg/ml, Teva) were stored at room temperature and subjected to re-piercing after 1, 2, 3, 7, 14, 21, 28 and 30 days following the initial piercing. Cisplatin infusions at nominal concentrations of 0.1 mg/ml were prepared in 0.9% sodium chloride (1000 ml) in PE bags. Chemical stability was measured by means of a stability-indicating high-performance liquid chromatography (HPLC) assay. Physical stability was assessed by visual inspection in normal light.

Results

The concentration of cisplatin at each sampling time in the analysed solutions remained within 92.0–100.7% of initial concentration, regardless of the container. No changes in colour or turbidity were observed in any of the vials or prepared solutions.

Conclusions

Cisplatin, both undiluted in glass containers and diluted with NaCl 0.9% in PE bags, remains stable (< 10% degradation) for at least 30 days at room temperature when protected from light.

Purification and biochemical characterization of a novel protein-tongue cancer chemotherapy resistance-associated protein1 (TCRP1)

Multidrug resistance is a major obstacle to successful treatment of oral squamous cell carcinoma (OSCC). Lately, we found a novel human gene named tongue cancer chemotherapy resistance-associated protein1 (TCRP1) in the tongue cancer multi-drug resistance cell line (Tca8113/PYM) established by us. In this study, we focus on recombinant expression, purification, and biochemical characterization of TCRP1. After molecular cloning and purification of the gene encoding the 24-kDa protein, a mouse polyclonal antibody against TCRP1 was prepared, and the specialty of the antibody was confirmed by Western blot. The cell proliferation was evaluated by MTS assay and DNA damage was determined by comet assay, the results indicated that this protein especially mediated the cell's resistance to cisplatin; it was associated with its role of providing protection against DNA damage. We also found that TCRP1 expression was increased in cisplatin-resistant carcinoma cell lines (Tca/PYM and A549/DDP), but not in cisplatin-sensitive MDR cell lines (MCF-7/5-Fu), compared with their parental counterparts by Western blot analysis. Immunofluorescence and immunohistochemical analysis showed TCRP1 is mainly expression in cytoplasmic, the Mann-Whitney U test exhibited that TCRP1 positive patients predicted the worst sensitive with cisplatin of OSCC patients. All these findings suggest that TCRP1 is a novel cisplatin-resistant protein which is mainly localized in the cytoplasm and can mediate cisplatin resistance against DNA damage; the expression level of TCRP1 in patients with OSCC may be useful as an indicator of therapeutic efficacy of the sensitivity to cisplatin.

Spontaneous metastasis in mouse models of testicular germ-cell tumours

Testicular germ-cell tumours (TGCTs) are the most common cancer in young men; the incidence is increasing worldwide and they have an unusually high rate of metastasis. Despite significant work on TGCTs and their metastases in humans, absence of a mouse model of spontaneous metastasis has greatly limited our understanding of the mechanisms by which metastatic potential is acquired and on their modes of dissemination. We report a new model of spontaneous TGCT metastasis in the 129 family of mice and provide evidence that these are true metastases derived directly from primary testicular cancers rather than independently from ectopic stem cells. These putative metastases (pMETs) occur at similar frequencies among TGCT-affected males in six genetically distinct TGCT-susceptible strains and were largely found in anatomical sites that are consistent with patterns of TGCT metastasis in humans. Various lines of evidence support their pluripotency and germ-cell origin, including presence of multiple endodermal, mesodermal and ectodermal derivatives as well as cells showing OCT4 and SSEA-1 pluripotency markers. In addition, pMETs were never found in males that did not have a TGCT, suggesting that metastases are derived from primary tumours. Finally, pMETS and primary TGCTs shared several DNA copy number variants suggesting a common cellular and developmental origin. Together, these results provide the first evidence for spontaneous TGCT metastasis in mice and show that these metastases originate from primary TGCTs rather than independently from ectopic stem cells.

The use of thiols by ribonucleotide reductase

Ribonucleotide reductase (RNR) catalyzes the rate-limiting de novo synthesis of 2'-deoxyribonucleotides from the corresponding ribonucleotides and thereby provides balanced deoxyribonucleotide pools required for error-free DNA replication and repair. The essential role of RNR in DNA synthesis and the use of DNA as genetic material has made it an important target for the development of anticancer and antiviral agents. The most well known feature of the universal RNR reaction in all kingdoms of life is the involvement of protein free radicals. Redox-active cysteines, thiyl radicals, and thiol redox proteins of the thioredoxin superfamily play major roles in the catalytic mechanism. The involvement of cysteine residues in catalysis is common to all three classes of RNR. Taking account of the recent progress in this field of research, this review focuses on the use of thiols in the redox mechanism of RNR enzymes.