Molecular portrait of cisplatin induced response in human testis cancer cell lines based on gene expression profiles

Molecular Characterization of Patients with Cryptorchidism: Preliminary Search for an Expression Profile Related to That of Testicular Germ-Cell Tumors

Cryptorchidism (CO) is a risk factor for the development of testicular germ-cell tumors (TGCT). This is supported by reports showing the persistence of gonocytes in CO patients. These cells are proposed to be related to the development of germ-cell neoplasia in situ (GCNIS), which is considered the precursor stage/lesion of TGCT. Therefore, it is proposed that some patients with CO could express some molecular markers related to TGCT. In this study, we analyzed testicular tissue samples from CO, TGCT, and controls. We determined the expression of POU5F1, PLAP, and KIT by immunohistochemistry and that of the hsa-miR-371-373 cluster, hsa-miR-367, and LATS2, PTEN, and IGFR1 genes by RT-qPCR. We then carried out a bioinformatic analysis to identify other possible candidate genes as tumor biomarkers. We found that 16.7% (2/12) of the CO patients presented increased expression of POU5F1, KIT, PLAP, hsa-miR-371-373, and hsa-miR-367 and decreased expression of LATS2 and IGF1R. Finally, the genes ARID4B, GALNT3, and KPNA6 were identified as other possible candidate tumor biomarkers. This is the first report describing the expression of the hsa-miR-371-373 cluster, hsa-miR-367, LATS2, and IGF1R in the testicular tissues of two CO patients with cells immune-positive to POU5F1, PLAP, and KIT, which is similar to what is observed in TGCT.

Sinapic acid alleviates cisplatin-induced acute kidney injury by mitigating oxidative stress and apoptosis

Cisplatin is an anticancer agent with many side effects such as nephrotoxicity, as well as being widely used in the treatment of many tumor types. Sinapic acid has antioxidant, anti-inflammatory, antihyperglycemic, and antiapoptotic effects. This study aimed to investigate the possible beneficial effects of sinapic acid against cisplatin-induced nephrotoxicity. Twenty-eight Wistar albino male rats were used. The groups are as follows: control, cisplatin, cisplatin + sinapic acid, and sinapic acid groups (n = 7). The control group received 1 ml of single-dose intraperitoneal saline on the first day of the study. The cisplatin group was given a single dose of 7 mg/kg cisplatin intraperitoneal. Animals in the cisplatin + sinapic acid group were given sinapic acid for 7 days 25 mg/kg, 3 days after oral gavage administration of 7 mg/kg cisplatin intraperitoneal. The sinapic acid group was given 25 mg/kg/day of sinapic acid by oral gavage for 7 days after the 3rd day of the study. The kidney of the rats was examined by stereological, immunohistochemical, histopathological, and biochemical methods. According to the stereological findings of the study, while the volume of the glomerulus cortex and filtration gap increased, the volume of the medulla decreased, and there was no significant difference in tubular volume in the CP group compared to the control group. The volume of the glomerulus, cortex, and filtration gap of the cisplatin + sinapic acid group was significantly reduced compared to the cisplatin group (p˂0.05). Histopathologically, it was observed the enlargement of the filtration gap, tubular dilatation, atrophy, renal fibrosis, deterioration of the microvilli, and necrosis in the tubular epithelial cells in the cisplatin group. In the cisplatin + sinapic acid group, these pathologies decreased compared to the cisplatin group. Compared to the control group, caspase-3 expression, urea, creatine, and malondialdehyde increased, while Bcl-2 and catalase decreased in the cisplatin group. However, caspase-3 expression, urea, creatine, and malondialdehyde were decreased, while Bcl-2 and catalase increased in the cisplatin + sinapic acid group compared to the cisplatin group. The results of our study showed that sinapic acid reduced the nephrotoxicity induced by cisplatin.

Estrogen- and estrogen receptor (ER)-mediated cisplatin chemoresistance in cancer

Cisplatin is a platinum-based chemotherapeutic drug used in the standard treatment of various solid cancers including testicular, bladder, head and neck, cervical and ovarian cancer. Although successful clinical responses are observed in patients following initial cisplatin treatment, resistance to cisplatin ultimately develops in most patients, leading to therapeutic failure. Multiple molecular mechanisms contributing to cisplatin resistance in cancer cells have been identified to date. In this review, we discuss the effect of estrogen, estrogen receptors (ERs) and estrogen-related receptors (ERRs) on cisplatin resistance in various cancer types. We highlight that estrogen treatment or increased expression of ERs or ERRs are generally associated with higher cisplatin resistance in cancer in vitro, mostly due to decreased caspase activity, increased anti-apoptotic protein levels such as BCL-2, higher drug efflux and higher levels of antioxidant enzymes. Targeted inhibition of ERs or estrogen production in combination with cisplatin treatment thus can be a useful strategy to overcome chemoresistance in certain cancer types. Estrogen levels and ER status can also be considered to identify cancer patients with a high potential of therapy response against cisplatin. A better mechanistic understanding of the involvement of estrogen, ERs and ERRs in the development of cisplatin resistance is needed to improve the management of cancer treatment.

Ameliorating potential and fertility enhancing activities of nutritional dietary supplementation of D-Ribose -l-Cysteine in cisplatin induced oligoasthenoteratozoospermia and seminiferous epithelium degeneration in adult male Sprague-Dawley rats

Background

Cisplatin (CN) is considered as a cytotoxic agent and DNA synthesis inhibitor. D-Ribose-l-Cysteine (DRLC) is an active ingredient of riboceine, help cells to produce glutathione on body demand.

Aim

Current study focused on ameliorating potential and fertility enhancing activities of D-Ribose–l-Cysteine in cisplatin induced oligoasthenoteratozoospermia and seminiferous epithelium degeneration.

Materials and method

Sixty (60) male rats randomized into six groups of ten (n = 10) rats each. Group A (control) received 2.0 ml distilled water, group B received single dose of 8 mg/kg bwt CN, group C received 30 mg/kg bwt DRLC, group D received single dose of 8 mg/kg CN follow by 30 mg/kg bwt DRLC, group E received single dose of 8 mg/kg CN and vitamin C, group F received single dose of 8 mg/kg cisplatin follow by DRLC + Vit.C for 56 days. Parameters tested include: Sperm parameters, testosterone (TT), luteinizing hormone (LH), Follicle stimulating Hormone, (FSH), Prolactin, and testicular 17β-HSD activity, Blood hydroperoxide (BHP), Malondialdehyde (MDA), Superoxide Dismutase (SOD), Glutathione (GSH) and Catalase (CAT), testicular histology and fertility test.

Results

Cisplatin significantly reduced testicular volume, body weight, sperm quality, fertility indices, TT, FSH, LH, 17β-HSD, SOD, GSH, CAT, diameter and cross-sectional area of seminiferous tubules, spermatogenesis score. And elevate prolactin, testicular injury score, BHP and MDA compared with control group. Cisplatin only treated rats showed degenerated seminiferous epithelium with empty lumen. Intervention of D-Ribose-Cysteine ameliorated toxic impacts of CN on testis and improved the male fertility.

Conclusion

D-Ribose-l-Cysteine therefore, preserves testicular integrity and functions thereby, preventing the deleterious impact of CN.

The Enigmatic Role of TP53 in Germ Cell Tumours: Are We Missing Something?

The cure rate of germ cell tumours (GCTs) has significantly increased from the late 1970s since the introduction of cisplatin-based therapy, which to date remains the milestone for GCTs treatment. The exquisite cisplatin sensitivity has been mainly explained by the over-expression in GCTs of wild-type TP53 protein and the lack of TP53 somatic mutations; however, several other mechanisms seem to be involved, many of which remain still elusive. The findings about the role of TP53 in platinum-sensitivity and resistance, as well as the reported evidence of second cancers (SCs) in GCT patients treated only with surgery, suggesting a spectrum of cancer predisposing syndromes, highlight the need for a deepened understanding of the role of TP53 in GCTs. In the following report we explore the complex role of TP53 in GCTs cisplatin-sensitivity and resistance mechanisms, passing through several recent genomic studies, as well as its role in GCT patients with SCs, going through our experience of Center of reference for both GCTs and cancer predisposing syndromes.

Differential gene expression in cisplatin-resistant and -sensitive testicular germ cell tumor cell lines

Testicular germ cell tumors (TGCTs) represent a well curable malignity due to their exceptional response to cisplatin (CDDP). Despite remarkable treatment results, approximately 5% of TGCT patients develop CDDP resistance and die. Exceptional curability makes TGCTs a highly valuable model system for studying the molecular mechanisms of CDDP sensitivity. Our study was aimed at revealing difference in gene expression between the CDDP-resistant and -sensitive TGCT cell lines, and hence at identifying candidate genes that could serve as potential biomarkers of CDDP response. Using gene expression array, we identified 281 genes that are differentially expressed in CDDP-resistant compared to -sensitive TGCT cell lines. The expression of 25 genes with the highest fold change was validated by RT-qPCR. Of them, DNMT3L, GAL, IGFBP2, IGFBP7, L1TD1, NANOG, NTF3, POU5F1, SOX2, WNT6, ZFP42, ID2, PCP4, SLC40A1 and TRIB3, displayed comparable expression change in gene expression array and RT-qPCR, when all CDDP-resistant TGCT cell lines were pairwise combined with all -sensitive ones. Products of the identified genes are pluripotency factors, or are involved in processes, such as cell metabolism, proliferation or migration. We propose that, after clinical validation, these genes could serve as prognostic biomarkers for early detection of CDDP response in TGCT patients.

Testicular cancer: Determinants of cisplatin sensitivity and novel therapeutic opportunities

Testicular cancer (TC) is the most common solid tumor among men aged between 15 and 40 years. TCs are highly aneuploid and the 12p isochromosome is the most frequent chromosomal abnormality. The mutation rate is of TC is low, with recurrent mutations in KIT and KRAS observed only at low frequency in seminomas. Overall cure rates are high, even in a metastatic setting, resulting from excellent cisplatin sensitivity of TCs. Factors contributing to the observed cisplatin sensitivity include defective DNA damage repair and a hypersensitive apoptotic response to DNA damage. Nonetheless, around 10-20% of TC patients with metastatic disease cannot be cured by cisplatin-based chemotherapy. Resistance mechanisms include downregulation of OCT4 and failure to induce PUMA and NOXA, elevated levels of MDM2, and hyperactivity of the PI3K/AKT/mTOR pathway. Several pre-clinical approaches have proven successful in overcoming cisplatin resistance, including specific targeting of PARP, MDM2 or AKT/mTOR combined with cisplatin. Finally, patient-derived xenograft models hold potential for mechanistic studies and pre-clinical validation of novel therapeutic strategies in TC. While clinical trials investigating targeted drugs have been disappointing, pre-clinical successes with chemotherapy and targeted drug combinations fuel the need for further investigation in clinical setting.

Cisplatin treatment of testicular cancer patients introduces long-term changes in the epigenome

BACKGROUND

Cisplatin-based chemotherapy (CBCT) is part of standard treatment of several cancers. In testicular cancer (TC) survivors, an increased risk of developing metabolic syndrome (MetS) is observed. In this epigenome-wide association study, we investigated if CBCT relates to epigenetic changes (DNA methylation) and if epigenetic changes render individuals susceptible for developing MetS later in life. We analyzed methylation profiles, using the MethylationEPIC BeadChip, in samples collected ~ 16 years after treatment from 279 Norwegian TC survivors with known MetS status. Among the CBCT treated (n = 176) and non-treated (n = 103), 61 and 34 developed MetS, respectively. We used two linear regression models to identify if (i) CBCT results in epigenetic changes and (ii) epigenetic changes play a role in development of MetS. Then we investigated if these changes in (i) and (ii) links to genes, functional networks, and pathways related to MetS symptoms.

RESULTS

We identified 35 sites that were differentially methylated when comparing CBCT treated and untreated TC survivors. The PTK6-RAS-MAPk pathway was significantly enriched with these sites and infers a gene network of 13 genes with CACNA1D (involved in insulin release) as a network hub. We found nominal MetS-associations and a functional gene network with ABCG1 and NCF2 as network hubs.

CONCLUSION

Our results suggest that CBCT has long-term effects on the epigenome. We could not directly link the CBCT effects to the risk of developing MetS. Nevertheless, since we identified differential methylation occurring in genes associated with conditions pertaining to MetS, we hypothesize that epigenomic changes may also play a role in the development of MetS in TC survivors. Further studies are needed to validate this hypothesis.

Complex alternative splicing of human Endonuclease V mRNA, but evidence for only a single protein isoform

Endonuclease V (ENDOV) is a ribonuclease with affinity for inosine which is the deamination product of adenosine. The genomes of most organisms, including human, encode ENDOV homologs, yet knowledge about in vivo functions and gene regulation is sparse. To contribute in this field, we analyzed mRNA and protein expression of human ENDOV (hENDOV). Analyses of public sequence databases revealed numerous hENDOV transcript variants suggesting extensive alternative splicing. Many of the transcripts lacked one or more exons corresponding to conserved regions of the ENDOV core domain, suggesting that these transcripts do not encode for active proteins. Three complete transcripts were found with open reading frames encoding 282, 308 and 309 amino acids, respectively. Recombinant hENDOV 308 and hENDOV 309 share the same cleavage activity as hENDOV 282 which is the variant that has been used in previous studies of hENDOV. However, hENDOV 309 binds inosine-containing RNA with stronger affinity than the other isoforms. Overexpressed GFP-fused isoforms were found in cytoplasm, nucleoli and arsenite induced stress granules in human cells as previously reported for hENDOV 282. RT-qPCR analysis of the 3’-termini showed that hENDOV 308 and hENDOV 309 transcripts are more abundant than hENDOV 282 transcripts in immortalized cell lines, but not in primary cells, suggesting that cells regulate hENDOV mRNA expression. In spite of the presence of all three full-length transcripts, mass spectrometry analyses identified peptides corresponding to the hENDOV 309 isoform only. This result suggests that further studies of human ENDOV should rather encompass the hENDOV 309 isoform.

IL-2 Induces Transient Arrest in the G1 Phase to Protect Cervical Cancer Cells from Entering Apoptosis

Interleukin 2 (IL-2) has been used for the treatment of different types of cancer that express the IL-2 receptor (IL-2R). However, the effect of IL-2 on cervical cancer cells is unknown. IL-2R is present in normal cells of the immune system but not in the healthy cervix. We report that IL-2R is expressed in cervical cancer cells. IL-2 decreases cervical cancer cell proliferation via transient arrest of the G1 phase, which does not result in apoptosis or senescence. IL-2 upregulates the expression of p53 and p21 and downregulates cyclin D. In addition, we report the resistance of cervical cancer cells to treatments that induce apoptosis in HeLa and INBL cells. When arrested cells were treated with cisplatin, the cytokine protected cells from apoptosis induced by cisplatin. The effects of IL-2 on the cell cycle do not induce cellular senescence or activate the proapoptotic protein Bax. The cell arrest induced by IL-2 is conferring protection to cells against apoptosis.

Mechanisms of cisplatin sensitivity and resistance in testicular germ cell tumors

Testicular germ cell tumors (TGCTs) are a cancer pharmacology success story with a majority of patients cured even in the highly advanced and metastatic setting. Successful treatment of TGCTs is primarily due to the exquisite responsiveness of this solid tumor to cisplatin-based therapy. However, a significant percentage of patients are, or become, refractory to cisplatin and die from progressive disease. Mechanisms for both clinical hypersensitivity and resistance have largely remained a mystery despite the promise of applying lessons to the majority of solid tumors that are not curable in the metastatic setting. Recently, this promise has been heightened by the realization that distinct (and perhaps pharmacologically replicable) epigenetic states, rather than fixed genetic alterations, may play dominant roles in not only TGCT etiology and progression but also their curability with conventional chemotherapies. In this review, it discusses potential mechanisms of TGCT cisplatin sensitivity and resistance to conventional chemotherapeutics.

Molecular Mechanisms of Cisplatin Chemoresistance and Its Circumventing in Testicular Germ Cell Tumors

PURPOSE OF REVIEW

Testicular germ cell tumors (TGCTs) represent the most common solid tumors affecting young men. Majority of TGCTs respond well to cisplatin-based chemotherapy. However, patients with refractory disease have limited treatment modalities associated with poor prognosis. Here, we discuss the main molecular mechanisms associated with acquired cisplatin resistance in TGCTs and how their understanding might help in the development of new approaches to tackle this clinically relevant problem. We also discuss recent data on the strategies of circumventing the cisplatin resistance from different tumor types potentially efficient also in TGCTs.

RECENT FINDINGS

Recent data regarding deregulation of various signaling pathways as well as genetic and epigenetic mechanisms in cisplatin-resistant TGCTs have contributed to understanding of the mechanisms related to the resistance to cisplatin-based chemotherapy in these tumors. Understanding of these mechanisms enabled explaining why majority but not all TGCTs patients are curable with cisplatin-based chemotherapy. Moreover, it could lead to the development of more effective treatment of refractory TGCTs and potentially other solid tumors resistant to platinum-based chemotherapy. This review provides additional insights into mechanisms associated with cisplatin resistance in TGCTs, which is a complex phenomenon, and there is a need for novel modalities to overcome it.

Activity profile of the cisplatin analogue PN149 in different tumor cell lines

The efficacy of the anticancer drug cisplatin is restricted by tumor cell resistance and occurrence of severe side effects. One strategy to overcome these limitations is the development of new, improved platinum drugs. Previous investigations showed that platinum(IV)-nitroxyl complexes are able to circumvent cisplatin resistance in bladder cancer cells. In the present study the mode of action of the platinum(IV)-nitroxyl complex PN149 was investigated in the bladder cancer cell line RT112 and the renal cell carcinoma cell line A498 on the molecular and cellular level. Gene expression analysis showed that PN149 induced genes related to DNA damage response (RRM2B, GADD45A), cell cycle regulation (CDKN1A, PLK3, PPM1D) as well as those coding for the pro-apoptotic factors PUMA and Noxa. These findings on the transcriptional level were confirmed on the functional level revealing that PN149 treatment increased levels of p53 and resulted in cell cycle arrest and drug-induced cytotoxicity via induction of apoptosis. Regarding the expression of oxidative-stress sensitive genes, PN149 induced FTH1, GCLC, HMOX1 and TXNRD1 but relevant effects were restricted to RT112 cells treated with 50 µM. The pro-inflammatory IL-8 was induced by PN149 in RT112 but not A498 cells indicating a cell-type specific activation. Taken together, PN149 possessed promising activity in different tumor cell lines rendering it an interesting alternative to cisplatin in chemotherapy.

Protective effects of amifostine, curcumin and caffeic acid phenethyl ester against cisplatin-induced testis tissue damage in rats

Cisplatin is an effective antineoplastic drug that is usually used to treat a number of different types of cancer in the clinic. One of the most notable side effects of cisplatin use is infertility. The present study was designed to determine the non-oxidative testicular effects caused by the use of cisplatin in rats. The rats were randomly allocated to the experimental groups. The untreated rats represented the control group (group I) and the treatment groups were as follows: cisplatin alone (group II), cisplatin+amifostine (group III), cisplatin+curcumin (group IV), and cisplatin+caffeic acid phenethyl ester (CAPE; group V). The present study observed that following cisplatin administration, the expression of nuclear factor-κB (NF-κβ)/p65, caspase-3 and 8-deoxyguanosine (8-OHdG) increased in germinal epithelium and Leydig cells. However, the expression of these markers decreased in groups III–V, most notably in the group treated with amifostine. cisplatin induced-damage was countered by amifostine and curcumin. The results revealed that the activation of NF-κB, caspase-3 and 8-OHdG had a significant role in cisplatin-induced testicular toxicity. Thus, amifostine, curcumin and, to a lesser extent, CAPE have the potential for use as therapeutic adjuvants in cisplatin-induced testis injury.

Genome-Wide miRNA Screening for Genes Bypassing Oncogene-Induced Senescence

MicroRNAs are small noncoding RNAs that regulate gene expression by binding to sequences within the 3'-UTR of mRNAs. Genome-wide screens have proven powerful in associating genes with certain phenotypes or signal transduction pathways and thus are valuable tools to define gene function. Here we describe a genome-wide miRNA screening strategy to identify miRNAs that are required to bypass oncogene-induced senescence.

Cell-to-Cell Variation in p53 Dynamics Leads to Fractional Killing

Many chemotherapeutic drugs kill only a fraction of cancer cells, limiting their efficacy. We used live-cell imaging to investigate the role of p53 dynamics in fractional killing of colon cancer cells in response to chemotherapy. We found that both surviving and dying cells reach similar levels of p53, indicating that cell death is not determined by a fixed p53 threshold. Instead, a cell's probability of death depends on the time and levels of p53. Cells must reach a threshold level of p53 to execute apoptosis, and this threshold increases with time. The increase in p53 apoptotic threshold is due to drug-dependent induction of anti-apoptotic genes, predominantly in the inhibitors of apoptosis (IAP) family. Our study underlines the importance of measuring the dynamics of key players in response to chemotherapy to determine mechanisms of resistance and optimize the timing of combination therapy.

Dissecting microRNA-mediated regulation of stemness, reprogramming, and pluripotency

Increasing evidence indicates that microRNAs (miRNAs), endogenous short non-coding RNAs 19–24 nucleotides in length, play key regulatory roles in various biological events at the post-transcriptional level. Embryonic stem cells (ESCs) represent a valuable tool for disease modeling, drug discovery, developmental studies, and potential cell-based therapies in regenerative medicine due to their unlimited self-renewal and pluripotency. Therefore, remarkable progress has been made in recent decades toward understanding the expression and functions of specific miRNAs in the establishment and maintenance of pluripotency. Here, we summarize the recent knowledge regarding the regulatory roles of miRNAs in self-renewal of pluripotent ESCs and during cellular reprogramming, as well as the potential role of miRNAs in two distinct pluripotent states (naïve and primed).

Probiotics modulated gut microbiota suppresses hepatocellular carcinoma growth in mice

The beneficial roles of probiotics in lowering the gastrointestinal inflammation and preventing colorectal cancer have been frequently demonstrated, but their immunomodulatory effects and mechanism in suppressing the growth of extraintestinal tumors remain unexplored. Here, we adopted a mouse model and metagenome sequencing to investigate the efficacy of probiotic feeding in controlling s.c. hepatocellular carcinoma (HCC) and the underlying mechanism suppressing the tumor progression. Our result demonstrated that Prohep, a novel probiotic mixture, slows down the tumor growth significantly and reduces the tumor size and weight by 40% compared with the control. From a mechanistic point of view the down-regulated IL-17 cytokine and its major producer Th17 cells, whose levels decreased drastically, played critical roles in tumor reduction upon probiotics feeding. Cell staining illustrated that the reduced Th17 cells in the tumor of the probiotic-treated group is mainly caused by the reduced frequency of migratory Th17 cells from the intestine and peripheral blood. In addition, shotgun-metagenome sequencing revealed the crosstalk between gut microbial metabolites and the HCC development. Probiotics shifted the gut microbial community toward certain beneficial bacteria, including Prevotella and Oscillibacter, that are known producers of antiinflammatory metabolites, which subsequently reduced the Th17 polarization and promoted the differentiation of antiinflammatory Treg/Tr1 cells in the gut. Overall, our study offers novel insights into the mechanism by which probiotic treatment modulates the microbiota and influences the regulation of the T-cell differentiation in the gut, which in turn alters the level of the proinflammatory cytokines in the extraintestinal tumor microenvironment.

Non-coding RNA in Spermatogenesis and Epididymal Maturation

Testicular germ and somatic cells express many classes of small ncRNAs, including Dicer-independent PIWI-interacting RNAs, Dicer-dependent miRNAs, and endogenous small interfering RNA. Several studies have identified ncRNAs that are highly, exclusively, or preferentially expressed in the testis and epididymis in specific germ and somatic cell types. Temporal and spatial expression of proteins is a key requirement of successful spermatogenesis and large-scale gene transcription occurs in two key stages, just prior to transcriptional quiescence in meiosis and then during spermiogenesis just prior to nuclear silencing in elongating spermatids. More than 60 % of these transcripts are then stockpiled for subsequent translation. In this capacity ncRNAs may act to interpret and transduce cellular signals to either maintain the undifferentiated stem cell population and/or drive cell differentiation during spermatogenesis and epididymal maturation. The assignation of specific roles to the majority of ncRNA species implicated as having a role in spermatogenesis and epididymal function will underpin fundamental understanding of normal and disease states in humans such as infertility and the development of germ cell tumours.

Cisplatin resistance in germ cell tumours: models and mechanisms

Recent years have led to a better understanding of the mechanisms underlying cisplatin response and resistance in germ cell tumours (GCT), and several promising targets have been identified. Two main mechanisms of the responsiveness to DNA damaging agents have been postulated. Firstly, GCT readily activate a DNA damage response, but show deficits in several damage repair pathways. In particular, they have been found to have defects in interstrand crosslink repair and in homologous recombination (HR). Secondly, GCT, especially embryonal carcinoma (EC) cells, show a hypersensitive apoptotic response to DNA damage, which activates p53, and leads to up-regulation of the pro-apoptotic factors Noxa, Puma and Fas in non-resistant EC. These cells fail to activate p21 which induces a G1/S arrest, but accumulate in G2/M phase. In the absence of functional p53, family members like p73 and GTAp63 might be important in initiating this response. Mechanisms involved in cisplatin resistance are as follows: down-regulation of Oct4 (e.g. as a result of hypoxia, treatment with retinoic acid or exposure to cisplatin) and failure to induce Puma and Noxa; changes in the expression levels of micro-RNAs such as miR-17/-106b, miR-302a, or miR-371 to -373; elevated levels of MDM2 and cytoplasmic translocation of p21 by phosphorylation; and activation of the PDGFRβ/PI3K/pAKT pathway. Several approaches to overcome resistance have been successfully examined in vitro and in vivo, including PARP inhibitors, especially in cells showing deficient HR-repair; stabilization of p53 using nutlin-3; inhibition of several components of the PI3K/pAKT pathway using small molecules; and DNA demethylation by 5-azacytidine or 5-aza-deoxy-cytidine, among others. Many of these substances deserve further exploration, alone or in combination with DNA damaging agents, and the most promising approaches should be taken forward to clinical testing. Targeted therapy based on mechanistic insights holds the promise to turn cisplatin-resistant GCT into a curable disease.

Cisplatin induces resistance by triggering differentiation of testicular embryonal carcinoma cells

Although testicular germ cell tumors are generally quite responsive to treatment with cisplatin, a small fraction of them acquire resistance during therapy. Even when cisplatin treatment is successful the patient is often left with a residual teratoma at the site of the primary tumor suggesting that cisplatin may trigger differentiation in some tumors. Using the human embryonal carcinoma cell line NTera2/D1, we confirmed that exposure to the differentiating agent retinoic acid produced a reduction in pluripotency markers NANOG and POU5F1 (Oct3/4) and an acute concentration-dependent increase in resistance to both cisplatin and paclitaxel that reached as high as 18-fold for cisplatin and 61-fold for paclitaxel within four days. A two day exposure to cisplatin also produced a concentration-dependent decrease in the expression of the NANOG and POU5F1 and increased expression of three markers whose levels increase with differentiation including Nestin, SCG10 and Fibronectin. In parallel, exposure to cisplatin induced up to 6.2-fold resistance to itself and 104-fold resistance to paclitaxel. Paclitaxel did not induce differentiation or resistance to either itself or cisplatin. Neither retinoic acid nor cisplatin induced resistance in cervical or prostate cancer cell lines or other germ cell tumor lines in which they failed to alter the expression of NANOG and POU5F1. Forced expression of NANOG prevented the induction of resistance to cisplatin by retinoic acid. We conclude that cisplatin can acutely induce resistance to itself and paclitaxel by triggering a differentiation response in pluripotent germ cell tumor cells.

Protective Role of GnRH Antagonist on Chemotherapy-induced Spermatogenesis Disorder: A Morphological Study

PURPOSE

Anti cancer drugs is one of the most important chemotherapeutic factors which can influence spermatogenesis process and germinal epithelium. Since dividing cells are mainly affected by anticancer drugs, the aim of the present study is to investigate the preventive effect of GnRH antagonist on spermatogenic defect produced by anticancer drugs.

METHODS

In the present study thirty adult male mice aging 6-8 weeks were divided into 3 groups as: Control, Experimental 1 and Experimental 2. Experimental 1 group received Cisplatin for 5 days as 2.5 mg/kg intraperitoneally and Experimental 2 group received 0.25 mg/kg cetrorelix (GnRH antagonist) one week before cisplatin treatment and continued for 3 weeks. The mice in all groups were sacrificed 35 days after the last injection and testis specimens were fixed in boueins, formaldehyde fixative and 2.5% Glutaraldehide then prepared for light and electron microscopic examination.

RESULTS

Light microscopy (LM) study showed that the number of spermatogonial cells, thickness of germinal epithelium, was decreased in Experimental 1group. Electron microscopy revealed that in this group several intercellular spaces appeared between spermatogenic cells and secretory granules in interstitial cells was increased. There were several vacuolated mitochondria and destroyed organelles in spermatogonial cells but in Experimental 2 group condition was similar to control group.

CONCLUSION

These results indicate that the cetrorelix administration before cancer treatment may protect germinal epithelium against side effects of cisplatin.

Metal dyshomeostasis and inflammation in Alzheimer's and Parkinson's diseases: possible impact of environmental exposures

A dysregulated metal homeostasis is associated with both Alzheimer's (AD) and Parkinson's (PD) diseases; AD patients have decreased cortex and elevated serum copper levels along with extracellular amyloid-beta plaques containing copper, iron, and zinc. For AD, a putative hepcidin-mediated lowering of cortex copper mechanism is suggested. An age-related mild chronic inflammation and/or elevated intracellular iron can trigger hepcidin production followed by its binding to ferroportin which is the only neuronal iron exporter, thereby subjecting it to lysosomal degradation. Subsequently raised neuronal iron levels can induce translation of the ferroportin assisting and copper binding amyloid precursor protein (APP); constitutive APP transmembrane passage lowers the copper pool which is important for many enzymes. Using in silico gene expression analyses, we here show significantly decreased expression of copper-dependent enzymes in AD brain and metallothioneins were upregulated in both diseases. Although few AD exposure risk factors are known, AD-related tauopathies can result from cyanobacterial microcystin and β-methylamino-L-alanine (BMAA) intake. Several environmental exposures may represent risk factors for PD; for this disease neurodegeneration is likely to involve mitochondrial dysfunction, microglial activation, and neuroinflammation. Administration of metal chelators and anti-inflammatory agents could affect disease outcomes.

Acute hypersensitivity of pluripotent testicular cancer-derived embryonal carcinoma to low-dose 5-aza deoxycytidine is associated with global DNA Damage-associated p53 activation, anti-pluripotency and DNA demethylation

Human embryonal carcinoma (EC) cells are the stem cells of nonseminoma testicular germ cells tumors (TGCTs) and share remarkable similarities to human embryonic stem (ES) cells. In prior work we found that EC cells are hypersensitive to low nanomolar doses of 5-aza deoxycytidine (5-aza) and that this hypersensitivity partially depended on unusually high levels of the DNA methyltransferase, DNMT3B. We show here that low-dose 5-aza treatment results in DNA damage and induction of p53 in NT2/D1 cells. In addition, low-dose 5-aza results in global and gene specific promoter DNA hypomethylation. Low-dose 5-aza induces a p53 transcriptional signature distinct from that induced with cisplatin in NT2/D1 cells and also uniquely downregulates genes associated with pluripotency including NANOG, SOX2, GDF3 and Myc target genes. Changes in the p53 and pluripotency signatures with 5-aza were to a large extent dependent on high levels of DNMT3B. In contrast to the majority of p53 target genes upregulated by 5-aza that did not show DNA hypomethylation, several other genes induced with 5-aza had corresponding decreases in promoter methylation. These genes include RIN1, SOX15, GPER, and TLR4 and are novel candidate tumors suppressors in TGCTs. Our studies suggest that the hypersensitivity of NT2/D1 cells to low-dose 5-aza is multifactorial and involves the combined activation of p53 targets, repression of pluripotency genes, and activation of genes repressed by DNA methylation. Low-dose 5-aza therapy may be a general strategy to treat those tumors that are sustained by cells with embryonic stem-like properties.GEO NUMBER FOR THE MICROARRAY DATA: GSE42647.

Degenerative effect of Cisplatin on testicular germinal epithelium

PURPOSE

The present study was designed to explore the effect of intraperitoneal administration of cisplatin in germinal epithelium of mice. There are few reports on the side effect of cisplatin on spermatogenesis when are used as anticancer drug. Therefore, in the present study the effect of cisplatin on spermatogenesis was evaluated by electron microscopy.

METHODS

Twenty balb/c mice aging 6-8 weeks was used in this study. The mice were divided into two groups, control and cysplatin treated. cysplatin was injected for five days as 2.5 mg /kg. The mice were sacrificed after 5 weeks and testicular specimens were removed, fixed in boueins, formaldeyd fixative and 2.5% Glutaraldehide then prepared for light and electron microscopic study.

RESULTS

Observation with optic microscope in treated group thickness of germinal epithelium was reduced a lot and increased the number of apoptotic cells. In some seminiferous tubules only sertoli cells were observed and nucleus of spermatogony cells was hetrochromatin. The electron microscopic observations showed some irregularity waviness and thickening in basal layer. Also myoid cells of this group were thick and contracted. In this group many apoptotic cells and damaged organelles were seen.

CONCLUSION

It was indicated that cisplatin affected testicular germinal epithelium by both cytotoxic effect and induction of apoptosis.

Cisplatin resistance: a cellular self-defense mechanism resulting from multiple epigenetic and genetic changes

Cisplatin is one of the most effective broad-spectrum anticancer drugs. Its effectiveness seems to be due to the unique properties of cisplatin, which enters cells via multiple pathways and forms multiple different DNA-platinum adducts while initiating a cellular self-defense system by activating or silencing a variety of different genes, resulting in dramatic epigenetic and/or genetic alternations. As a result, the development of cisplatin resistance in human cancer cells in vivo and in vitro by necessity stems from bewilderingly complex genetic and epigenetic changes in gene expression and alterations in protein localization. Extensive published evidence has demonstrated that pleiotropic alterations are frequently detected during development of resistance to this toxic metal compound. Changes occur in almost every mechanism supporting cell survival, including cell growth-promoting pathways, apoptosis, developmental pathways, DNA damage repair, and endocytosis. In general, dozens of genes are affected in cisplatin-resistant cells, including pathways involved in copper metabolism as well as transcription pathways that alter the cytoskeleton, change cell surface presentation of proteins, and regulate epithelial-to-mesenchymal transition. Decreased accumulation is one of the most common features resulting in cisplatin resistance. This seems to be a consequence of numerous epigenetic and genetic changes leading to the loss of cell-surface binding sites and/or transporters for cisplatin, and decreased fluid phase endocytosis.

RNA processing and modification protein, carbon catabolite repression 4 (Ccr4), arrests the cell cycle through p21-dependent and p53-independent pathway

Ccr4d is a new member of the Ccr4 (carbon catabolite repression 4) family of proteins that are implicated in the regulation of mRNA stability and translation through mRNA deadenylation. However, Ccr4d is not believed to be involved in mRNA deadenylation. Thus, its biological function and mechanistic activity remain to be determined. Here, we report that Ccr4d is broadly expressed in various normal tissues, and the expression of Ccr4d is markedly down-regulated during cell cycle progression. We showed that Ccr4d inhibits cell proliferation and induces cell cycle arrest at G(1) phase. Our experiments further revealed that Ccr4d regulates the expression of p21 in a p53-independent manner. Mechanistic studies indicated that Ccr4d strongly bound to the 3'-UTR of p21 mRNA, leading to the stabilization of p21 mRNA. Interestingly, we found that the expression of Ccr4d is down-regulated in various tumor tissues. Collectively, our data indicate that Ccr4d functions as an anti-proliferating protein through the induction of cell cycle arrest via a p21-dependent and p53-independent pathway and suggest that Ccr4d might have an important role in carcinogenesis.

Paternal Benzo[a]pyrene Exposure Modulates MicroRNA Expression Patterns in the Developing Mouse Embryo

Little attention has been given to how microRNA expression is affected by environmental contaminants exposure. We investigate the effects of paternal exposure to benzo[a]pyrene (B[a]P) on miRNA expression in the developing mouse embryo. Male mice were exposed to B[a]P (150 mg/kg i.p.), and their sperm was used four days later in in-vitro fertilization experiments. Twenty embryos each from 2-, 8-cell and the blastocyst stage were used for genome-wide miRNA expression profiling. Paternal exposure to B[a]P affected the expression of several miRNAs, and the target genes for some of the dysregulated miRNAs were enriched in many different pathways that are likely to be relevant for the developing mouse embryo. By linking the miRNA target genes to publicly available databases, we identified some miRNA target genes that may serve as global markers of B[a]P-mediated genotoxic stress. The dysregulated miRNAs may provide valuable knowledge about potential transgenerational effects of sublethal exposure to chemicals.

Spata22, a novel vertebrate-specific gene, is required for meiotic progress in mouse germ cells

The N-ethyl-N-nitrosourea-induced repro42 mutation, identified by a forward genetics strategy, causes both male and female infertility, with no other apparent phenotypes. Positional cloning led to the discovery of a nonsense mutation in Spata22, a hitherto uncharacterized gene conserved among bony vertebrates. Expression of both transcript and protein is restricted predominantly to germ cells of both sexes. Germ cells of repro42 mutant mice express Spata22 transcript, but not SPATA22 protein. Gametogenesis is profoundly affected by the mutation, and germ cells in repro42 mutant mice do not progress beyond early meiotic prophase, with subsequent germ cell loss in both males and females. The Spata22 gene is essential for one or more key events of early meiotic prophase, as homologous chromosomes of mutant germ cells do not achieve normal synapsis or repair meiotic DNA double-strand breaks. The repro42 mutation thus identifies a novel mammalian germ cell-specific gene required for meiotic progression.

Micro-RNA expression in cisplatin resistant germ cell tumor cell lines

Background

We compared microRNA expression patterns in three cisplatin resistant sublines derived from paternal cisplatin sensitive germ cell tumor cell lines in order to improve our understanding of the mechanisms of cisplatin resistance.

Methods

Three cisplatin resistant sublines (NTERA-2-R, NCCIT-R, 2102EP-R) showing 2.7-11.3-fold increase in drug resistance after intermittent exposure to increasing doses of cisplatin were compared to their parental counterparts, three well established relatively cisplatin sensitive germ cell tumor cell lines (NTERA-2, NCCIT, 2102EP). Cells were cultured and total RNA was isolated from all 6 cell lines in three independent experiments. RNA was converted into cDNA and quantitative RT-PCR was run using 384 well low density arrays covering almost all (738) known microRNA species of human origin.

Results

Altogether 72 of 738 (9.8%) microRNAs appeared differentially expressed between sensitive and resistant cell line pairs (NTERA-2R/NTERA-2 = 43, NCCIT-R/NCCIT = 53, 2102EP-R/2102EP = 15) of which 46.7-95.3% were up-regulated (NTERA-2R/NTERA-2 = 95.3%, NCCIT-R/NCCIT = 62.3%, 2102EP-R/2102EP = 46.7%). The number of genes showing differential expression in more than one of the cell line pairs was 34 between NTERA-2R/NTERA-2 (79%) and NCCIT-R/NCCIT (64%), and 3 and 4, respectively, between these two cell lines and 2102EP-R/2102EP (about 27%). Only the has-miR-10b involved in breast cancer invasion and metastasis and has-miR-512-3p appeared to be up-regulated (2-3-fold) in all three cell lines. The hsa-miR-371-373 cluster (counteracting cellular senescence and linked with differentiation potency), as well as hsa-miR-520c/-520h (inhibiting the tumor suppressor p21) were 3.9-16.3 fold up-regulated in two of the three cisplatin resistant cell lines. Several new micro-RNA species missing an annotation towards cisplatin resistance could be identified. These were hsa-miR-512-3p/-515/-517/-518/-525 (up to 8.1-fold up-regulated) and hsa-miR-99a/-100/-145 (up to 10-fold down-regulated).

Conclusion

Examining almost all known human micro-RNA species confirmed the miR-371-373 cluster as a promising target for explaining cisplatin resistance, potentially by counteracting wild-type P53 induced senescence or linking it with the potency to differentiate. Moreover, we describe for the first time an association of the up-regulation of micro-RNA species such as hsa-miR-512-3p/-515/-517/-518/-525 and down-regulation of hsa-miR-99a/-100/-145 with a cisplatin resistant phenotype in human germ cell tumors. Further functional analyses are warranted to gain insight into their role in drug resistance.

miRNA in pluripotent stem cells

Embryonic stem cells and induced pluripotent stem cells are characterized by their ability to self-renew and differentiate into any cell type. The molecular mechanism behind this process is a complex interplay between the transcriptional factors with epigenetic regulators and signaling pathways. miRNAs are an integral part of this regulatory network, with essential roles in pluripotent maintenance, proliferation and differentiation. miRNAs are a class of small noncoding RNAs that target protein-encoding mRNA to inhibit translation and protein synthesis. Discovered close to 20 years ago, miRNAs have rapidly emerged as key regulatory molecules in several critical cellular processes across species. Recent studies have begun to clarify the specific role of miRNA in regulatory circuitries that control self-renewal and pluripotency of both embryonic stem cells and induced pluripotent stem cells. These advances suggest a critical role for miRNAs in the process of reprogramming somatic cells to pluripotent cells.

Stability of the LATS2 tumor suppressor gene is regulated by tristetraprolin

LATS2 is a tumor suppressor gene implicated in the control of cell growth and the cell cycle. Here, we investigated the post-transcriptional regulation of LATS2 expression by tristetraprolin (TTP). Our results show that the expression level of LATS2 is inversely correlated with TTP expression in human cancer cell lines. Overexpression of TTP reduced the expression level of LATS2. Conversely, treatment with small interfering RNA against TTP increased the expression level of LATS2 through stabilization of LATS2 mRNA and suppressed the proliferation of A549 human lung cancer cells. LATS2 mRNA contains AU-rich elements (AREs) within the 3'-untranslated region, and TTP destabilized a luciferase mRNA containing LATS2 ARE. In addition, RNA electrophoretic mobility shift assay revealed that TTP directly bound to the ARE of LATS2 mRNA. These results establish LATS2 mRNA as a physiological target of TTP and suggest the possibility that TTP controls cell growth through regulation of LATS2 mRNA stability.

Alterations in gene expression profiles correlated with cisplatin cytotoxicity in the glioma U343 cell line

Gliomas are the most common tumors in the central nervous system, the average survival time of patients with glioblastoma multiforme being about 1 year from diagnosis, in spite of harsh therapy. Aiming to study the transcriptional profiles displayed by glioma cells undergoing cisplatin treatment, gene expression analysis was performed by the cDNA microarray method. Cell survival and apoptosis induction following treatment were also evaluated. Drug concentrations of 12.5 to 300 μM caused a pronounced reduction in cell survival rates five days after treatment, whereas concentrations higher than 25 μM were effective in reducing the survival rates to ~1%. However, the maximum apoptosis frequency was 20.4% for 25 μM cisplatin in cells analyzed at 72 h, indicating that apoptosis is not the only kind of cell death induced by cisplatin. An analysis of gene expression revealed 67 significantly (FDR < 0.05) modulated genes: 29 of which down- and 38 up-regulated. These genes belong to several classes (metabolism, protein localization, cell proliferation, apoptosis, adhesion, stress response, cell cycle and DNA repair) that may represent several affected cell processes under the influence of cisplatin treatment. The expression pattern of three genes (RHOA, LIMK2 and TIMP2) was confirmed by the real time PCR method.

Telomere shortening sensitizes cancer cells to selected cytotoxic agents: in vitro and in vivo studies and putative mechanisms

Background

Telomere/telomerase system has been recently recognized as an attractive target for anticancer therapy. Telomerase inhibition results in tumor regression and increased sensitivity to various cytotoxic drugs. However, it has not been fully established yet whether the mediator of these effects is telomerase inhibition per se or telomere shortening resulting from inhibition of telomerase activity. In addition, the characteristics and mechanisms of sensitization to cytotoxic drugs caused by telomerase inhibition has not been elucidated in a systematic manner.

Methodology/Principal Findings

In this study we characterized the relative importance of telomerase inhibition versus telomere shortening in cancer cells. Sensitization of cancer cells to cytotoxic drugs was achieved by telomere shortening in a length dependent manner and not by telomerase inhibition per se. In our system this sensitization was related to the mechanism of action of the cytotoxic drug. In addition, telomere shortening affected also other cancer cell functions such as migration. Telomere shortening induced DNA damage whose repair was impaired after administration of cisplatinum while doxorubicin or vincristine did not affect the DNA repair. These findings were verified also in in vivo mouse model. The putative explanation underlying the phenotype induced by telomere shortening may be related to changes in expression of various microRNAs triggered by telomere shortening.

Conclusions/Significance

To our best knowledge this is the first study characterizing the relative impact of telomerase inhibition and telomere shortening on several aspects of cancer cell phenotype, especially related to sensitivity to cytotoxic drugs and its putative mechanisms. The microRNA changes in cancer cells upon telomere shortening are novel information. These findings may facilitate the development of telomere based approaches in treatment of cancer.

Octyl methoxycinnamate modulates gene expression and prevents cyclobutane pyrimidine dimer formation but not oxidative DNA damage in UV-exposed human cell lines

Octyl methoxycinnamate (OMC) is one of the most widely used sunscreen ingredients. To analyze biological effects of OMC, an in vitro approach was used implying ultraviolet (UV) exposure of two human cell lines, a primary skin fibroblast (GM00498) and a breast cancer (MCF-7) cell lines. End points include cell viability assessment, assay of cyclobutane pyrimidine dimers (CPDs) and oxidated DNA lesions using alkaline elution and lesion-specific enzymes, and gene expression analysis of a panel of 17 DNA damage–responsive genes. We observed that OMC provided protection against CPDs, and the degree of protection correlated with the OMC-mediated reduction in UV dose. No such protection was found with respect to oxidative DNA lesions. Upon UV exposure in the presence of OMC, the gene expression studies showed significant differential changes in some of the genes studied and the expression of p53 protein was also changed. For some genes, the change in expression seemed to be delayed in time by OMC. The experimental approach applied in this study, using a panel of 17 genes in an in vitro cellular system together with genotoxicity assays, may be useful in the initial screening of active ingredients in sunscreens.

Suppression of annexin A11 in ovarian cancer: implications in chemoresistance

Ovarian cancer patients treated with cisplatin-based chemotherapy often develop acquired cisplatin resistance and, consequently, cancer recurrence. We have previously reported that annexin A11 is associated with cisplatin resistance and related to tumor recurrence in ovarian cancer patients. In this study, we used small interfering RNA to suppress annexin A11 expression in ovarian cancer cells followed by various in vitro assays. We showed that knockdown of annexin A11 expression reduced cell proliferation and colony formation ability of ovarian cancer cells. Epigenetic silencing of annexin A11 conferred cisplatin resistance to ovarian cancer cells. Through a comprehensive time course study of cisplatin response in ovarian cancer cells with/without suppression of annexin A11 expression using whole-genome oligonucleotide microarrays, we identified a set of differentially expressed genes associated with annexin A11 expression and some patterns of gene expressions in response to cisplatin exposure. These identified genes/patterns were further validated by real-time polymerase chain reaction and immunoblot analysis. Many of them such as HMOX1, TGFBI, LY6D, S100P, EIF4EBP2, DHRS2, and PCSK9 have been involved in apoptosis, cell cycling/proliferation, cell adhesion/migration, transcription regulation, and signal transduction. In addition, immunohistochemistry analyses indicated that annexin A11 immunointensity inversely correlated with HMOX1 immunoreactivity in 142 ovarian cancer patients. In contrast to annexin A11, HMOX1 immunoreactivity positively correlated with in vitro cisplatin resistance in ovarian cancers. Collectively, annexin A11 is directly involved in cell proliferation and cisplatin resistance of ovarian cancer. Manipulation of annexin A11 and its associated genes may represent a novel therapeutic strategy in human ovarian cancers.

The expression of COX-2, hTERT, MDM2, LATS2 and S100A2 in different types of non-small cell lung cancer (NSCLC)

Several studies have reported different expression levels of certain genes in NSCLC, mostly related to the stage and advancement of the tumours. We investigated 65 stage I-III NSCLC tumours: 32 adenocarcinomas (ADC), 26 squamous cell carcinomas (SCC) and 7 large cell carcinomas (LCC). Using the real-time reverse transcription polymerase chain reaction (RT-PCR), we analysed the expression of the COX-2, hTERT, MDM2, LATS2 and S100A2 genes and researched the relationships between the NSCLC types and the differences in expression levels. The differences in the expression levels of the LATS2, S100A2 and hTERT genes in different types of NSCLC are significant. hTERT and COX-2 were over-expressed and LATS2 under-expressed in all NSCLC. We also detected significant relative differences in the expression of LATS2 and MDM2, hTERT and MDM2 in different types of NSCLC. There was a significant difference in the average expression levels in S100A2 for ADC and SCC. Our study shows differences in the expression patterns within the NSCLC group, which may mimic the expression of the individual NSCLC type, and also new relationships in the expression levels for different NSCLC types.

Biology of testicular germ cell tumors

Germ cell tumors are derived from cells of the germ cell lineage and are the most common solid malignancies to affect young Caucasian men between the ages of 15 and 40 years. All testicular germ cell tumors develop from the same precursor lesion, intratubular germ cell neoplasia unclassified, which in turn is thought to arise from malignant transformation of a primordial germ cell or gonocyte. These tumors are characterized by extreme chemosensitivity and are considered a model for curative disease. In spite of this, a small subset of patients with metastatic disease fail to achieve a complete response with cisplatin-based chemotherapy or relapse from complete remission. Understanding the molecular biology may help the design of new therapies for those patients with a poor prognosis and could also improve the treatment of cancer in general. Current understanding of the role of genetic and epigenetic factors in the etiology of germ cell tumors and the biochemical mechanisms underlying chemotherapy sensitivity and resistance is discussed in detail in this review.

LATS2 tumour specific mutations and down-regulation of the gene in non-small cell carcinoma

LATS2 is a new member of the LATS tumour suppressor family. The human LATS2 gene is located at chromosome 13q11-12, a hot spot (67%) for loss of heterozygosity (LOH) in non-small cell lung cancer (NSCLC). We screened 129 non-small cell lung cancer samples and 13 lung cancer cell lines, initially for mutations in the LATS2 gene and subsequently for mutations in P53 and K-RAS genes. Either polymorphisms or mutations were identified in over 50 percent of analysed tumours. A novel missense mutation, S1073R, and a large deletion of 8 amino acids in the PAPA-repeat region were detected in 9 and 2 NSCLC tumours, respectively. Those mutations were not identified in the 13 lung cancer cell lines. Mutations were tumour specific and were absent from adjacent normal tissue and healthy controls. Down-regulation of the LATS2 gene was observed in most NSCLC tumours but was not related to any mutation or polymorphism. Tumours with a LATS2 mutation often also harbour a P53 but not K-RAS gene mutation and were mostly in an advanced stage of development, with regional lymph node involvement.