The association of CCND1 overexpression and cisplatin resistance in testicular germ cell tumors and other cancers

Combined single cell and spatial transcriptome analysis reveals cellular heterogeneity of hedgehog pathway in gastric cancer

Gastric cancer (GC) is one of the most common and deadly malignancies in the world. Abnormal activation of hedgehog pathway is closely related to tumor development and progression. However, potential therapeutic targets for GC based on the hedgehog pathway have not been clearly identified. In the present study, we combined single-cell sequencing data and spatial transcriptomics to deeply investigate the role of hedgehog pathway in GC. Based on a comprehensive scoring algorithm, we found that fibroblasts from GC tumor tissues were characterized by a highly enriched hedgehog pathway. By analyzing the development process of fibroblasts, we found that CCND1 plays an important role at the end stage of fibroblast development, which may be related to the formation of tumor-associated fibroblasts. Based on spatial transcriptome data, we deeply mined the role of CCND1 in fibroblasts. We found that CCND1-negative and -positive fibroblasts have distinct characteristics. Based on bulk transcriptome data, we verified that highly infiltrating CCND1 + fibroblasts are a risk factor for GC patients and can influence the immune and chemotherapeutic efficacy of GC patients. Our study provides unique insights into GC and hedgehog pathways and also new directions for cancer treatment strategies.

LASS2 enhances chemosensitivity to cisplatin by inhibiting PP2A-mediated β-catenin dephosphorylation in a subset of stem-like bladder cancer cells

BACKGROUND

The benefits of first-line, cisplatin-based chemotherapy for muscle-invasive bladder cancer are limited due to intrinsic or acquired resistance to cisplatin. Increasing evidence has revealed the implication of cancer stem cells in the development of chemoresistance. However, the underlying molecular mechanisms remain to be elucidated. This study investigates the role of LASS2, a ceramide synthase, in regulating Wnt/β-catenin signaling in a subset of stem-like bladder cancer cells and explores strategies to sensitize bladder cancer to cisplatin treatment.

METHODS

Data from cohorts of our center and published datasets were used to evaluate the clinical characteristics of LASS2. Flow cytometry was used to sort and analyze bladder cancer stem cells (BCSCs). Tumor sphere formation, soft agar colony formation assay, EdU assay, apoptosis analysis, cell viability, and cisplatin sensitivity assay were used to investigate the functional roles of LASS2. Immunofluorescence, immunoblotting, coimmunoprecipitation, LC-MS, PCR array, luciferase reporter assays, pathway reporter array, chromatin immunoprecipitation, gain-of-function, and loss-of-function approaches were used to investigate the underlying mechanisms. Cell- and patient-derived xenograft models were used to investigate the effect of LASS2 overexpression and a combination of XAV939 on cisplatin sensitization and tumor growth.

RESULTS

Patients with low expression of LASS2 have a poorer response to cisplatin-based chemotherapy. Loss of LASS2 confers a stem-like phenotype and contributes to cisplatin resistance. Overexpression of LASS2 results in inhibition of self-renewal ability of BCSCs and increased their sensitivity to cisplatin. Mechanistically, LASS2 inhibits PP2A activity and dissociates PP2A from β-catenin, preventing the dephosphorylation of β-catenin and leading to the accumulation of cytosolic phospho-β-catenin, which decreases the transcription of the downstream genes ABCC2 and CD44 in BCSCs. Overexpression of LASS2 combined with a tankyrase inhibitor (XAV939) synergistically inhibits tumor growth and restores cisplatin sensitivity.

CONCLUSIONS

Targeting the LASS2 and β-catenin pathways may be an effective strategy to overcome cisplatin resistance and inhibit tumor growth in bladder cancer patients.

Long non-coding RNA PVT1 (PVT1) affects the expression of CCND1 and promotes doxorubicin resistance in osteosarcoma cells

Background

Acquired drug-resistance is the major risk factor for poor prognosis and short-term survival in patients with osteosarcoma (OS). Accumulating evidence has revealed that long noncoding RNAs (lncRNAs), including plasmacytoma variant translocation 1 (PVT1), play potential regulatory roles in the malignant development of OS. Considering the subcellular distribution of PVT1 as both nuclear and cytoplasmic lncRNA, a thorough exploration of its extensive mechanisms becomes essential.

Methods

The GEO database was utilized for the acquisition of gene expression data, which was subsequently analyzed to fulfill the research objectives. The subcellular localization of PVT1 in OS cells was determined using fluorescence in situ hybridization (FISH) and quantitative real-time polymerase chain reaction (qRT-PCR). Additionally, the sensitivity of OS cells to doxorubicin was comprehensively evaluated through measurements of cell viability, site-specific proliferation capacity, and the relative expression abundance of multidrug resistance-related proteins (MRPs). In order to investigate the differential response of OS cells with varying levels of PVT1 expression to doxorubicin, pulmonary metastasis mice models were established for in vivo studies. Molecular interactions were further examined using the dual-luciferase assay and RNA immunoprecipitation assay (RIP) to analyze the binding sites of miR-15a-5p and miR-15b-5p on PVT1 and G1/S-specific cyclinD1 (CCND1) mRNA. Furthermore, the chromatin immunoprecipitation (ChIP) and dual-luciferase assay were employed to assess the transcriptional activation of the proto-oncogene c-myc (MYC) on the CCND1 promoter and identify the corresponding binding sites.

Results

In doxorubicin resistant OS cells, transcription levels of PVT1, MYC and CCND1 were significantly higher than those in original cells. In vivo experiments demonstrated that OS cells rich in PVT1 expression exhibited enhanced tumorigenicity and resistance to doxorubicin. In vitro experiments, it has been observed that overexpression of PVT1 in OS cells is accompanied by an upregulation of CCND1, thereby facilitating resistance to doxorubicin. Nonetheless, this PVT1-induced resistance can be effectively attenuated by the knockdown of CCND1. Mechanistically, PVT1 functions as a competitive endogenous RNA (ceRNA) that influences the expression of CCND1 by inhibiting the degradation function of miR-15a-5p and miR-15b-5p on CCND1 mRNA. Additionally, as a neighboring gene of MYC, PVT1 plays a role in maintaining MYC protein stability, which further enhances MYC-dependent CCND1 transcriptional activity.

Conclusion

The resistance of OS cells to doxorubicin is facilitated by PVT1, which enhances the expression of CCND1 through a dual mechanism. This findings offer a novel perspective for comprehending the intricate regulatory mechanisms of long non-coding RNA in influencing the expression of coding genes.

KLHL29-mediated DDX3X degradation promotes chemosensitivity by abrogating cell cycle checkpoint in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is a heterogeneous breast cancer subtype and accounts for approximately 15-20% of breast cancer cases. In this study, we identified KLHL29, which is an understudied member of the Kelch-like gene family, as a crucial tumor suppressor that regulates chemosensitivity in TNBC. KLHL29 expression was significantly downregulated in breast cancer tissues compared with adjacent normal tissues, and low levels of KLHL29 were associated with unfavorable prognoses. Ectopic KLHL29 suppressed, while depleting KLHL29 promoted, the growth, proliferation, migration, and invasion of TNBC. Mechanistically, KLHL29 recruited the CUL3 E3-ligase to the RNA-binding protein DDX3X, leading to the proteasomal degradation of the latter. This downregulation of DDX3X resulted in the destabilization of CCND1 mRNA and the consequent cell cycle arrest at G0/G1 phase. Remarkably, the DDX3X inhibitor RK33 combined with platinum-based chemotherapy can synergistically suppress TNBC that usually expresses low levels of KLHL29 and high levels of DDX3X using cancer cell-derived xenograft and patient-derived organoids models. Altogether, we uncovered the potential role for the KLHL29-DDX3X signaling cascade in the regulation of TNBC progression, thus providing a promising combination strategy for overcoming TNBC chemoresistance.

Unveiling the genomic landscape of possible metastatic malignant transformation of teratoma secondary to cisplatin-chemotherapy: a Tempus gene analysis-based case report literature review

In this case report, we describe a patient who developed metastatic liver cancer of unknown primary origin one year following the surgical removal of a retroperitoneal adenocarcinoma. The retroperitoneal adenocarcinoma is considered a malignant transformation of teratoma (MTT), given the patient's distant history of testicular tumor excised 25 years prior and treated with chemotherapy. Despite no primary tumor being identified, the leading primary hypothesis is that the liver metastasis stemmed from the resected retroperitoneal adenocarcinoma from one year prior. We theorize that the patient's cisplatin-based chemotherapy 25 years ago may have triggered the MTT, as documented in the existing literature. Using TEMPUS gene testing on both the retroperitoneal adenocarcinoma and the recently discovered liver metastasis, we identified several genes with variants of unknown significance (VUS) that could potentially be linked to cisplatin chemotherapy resistance. While we cannot conclude that this patient definitively underwent MTT, it remains the most plausible explanation. Future research should investigate both the validity of the genes we have uncovered with respect to cisplatin resistance, as well as other genes associated with cisplatin resistance to further understand the pathogenesis of cisplatin resistance for better prediction of treatment response. As the world of medicine shifts towards individualized therapies and precision medicine, reporting and analyzing genetic mutations derived from tumors remains imperative. Our case report aims to contribute to the growing database of defined mutations and underscores the immense potential of genetic analysis in directing personalized treatment options.

Breaking the Mold: Epigenetics and Genomics Approaches Addressing Novel Treatments and Chemoresponse in TGCT Patients

Testicular germ-cell tumors (TGCT) have been widely recognized for their outstanding survival rates, commonly attributed to their high sensitivity to cisplatin-based therapies. Despite this, a subset of patients develops cisplatin resistance, for whom additional therapeutic options are unsuccessful, and ~20% of them will die from disease progression at an early age. Several efforts have been made trying to find the molecular bases of cisplatin resistance. However, this phenomenon is still not fully understood, which has limited the development of efficient biomarkers and precision medicine approaches as an alternative that could improve the clinical outcomes of these patients. With the aim of providing an integrative landscape, we review the most recent genomic and epigenomic features attributed to chemoresponse in TGCT patients, highlighting how we can seek to combat cisplatin resistance through the same mechanisms by which TGCTs are particularly hypersensitive to therapy. In this regard, we explore ongoing treatment directions for resistant TGCT and novel targets to guide future clinical trials. Through our exploration of recent findings, we conclude that epidrugs are promising treatments that could help to restore cisplatin sensitivity in resistant tumors, shedding light on potential avenues for better prognosis for the benefit of the patients.

Overcoming Chemotherapy Resistance in Germ Cell Tumors

Testicular germ cell tumors (GCTs) are highly curable malignancies. Excellent survival rates in patients with metastatic disease can be attributed to the exceptional sensitivity of GCTs to cisplatin-based chemotherapy. This hypersensitivity is probably related to alterations in the DNA repair of cisplatin-induced DNA damage, and an excessive apoptotic response. However, chemotherapy fails due to the development of cisplatin resistance in a proportion of patients. The molecular basis of this resistance appears to be multifactorial. Tracking the mechanisms of cisplatin resistance in GCTs, multiple molecules have been identified as potential therapeutic targets. A variety of therapeutic agents have been evaluated in preclinical and clinical studies. These include different chemotherapeutics, targeted therapies, such as tyrosine kinase inhibitors, mTOR inhibitors, PARP inhibitors, CDK inhibitors, and anti-CD30 therapy, as well as immune-checkpoint inhibitors, epigenetic therapy, and others. These therapeutics have been used as single agents or in combination with cisplatin. Some of them have shown promising in vitro activity in overcoming cisplatin resistance, but have not been effective in clinical trials in refractory GCT patients. This review provides a summary of current knowledge about the molecular mechanisms of cisplatin sensitivity and resistance in GCTs and outlines possible therapeutic approaches that seek to overcome this chemoresistance.

Effects of trans-(±)-kusunokinin on chemosensitive and chemoresistant ovarian cancer cells

Ovarian cancer ranks eighth in cancer incidence and mortality among women worldwide. Cisplatin-based chemotherapy is commonly used for patients with ovarian cancer. However, the clinical efficacy of cisplatin is limited due to the occurrence of adverse side effects and development of cancer chemoresistance during treatment. Trans-(±)-kusunokinin has been previously reported to inhibit cell proliferation and induce cell apoptosis in various cancer cell types, including breast, colon and cholangiocarcinoma. However, the potential effects of (±)-kusunokinin on ovarian cancer remains unknown. In the present study, chemosensitive ovarian cancer cell line A2780 and chemoresistant ovarian cancer cell lines A2780cis, SKOV-3 and OVCAR-3 were treated with trans-(±)-kusunokinin to investigate its potential effects. MTT, colony formation, apoptosis and multi-caspase assays were used to determine cytotoxicity, the ability of single cells to form colonies, induction of apoptosis and multi-caspase activity, respectively. Moreover, western blot analysis was performed to determine the proteins level of topoisomerase II, cyclin D1, CDK1, Bax and p53-upregulated modulator of apoptosis (PUMA). The results demonstrated that trans-(±)-kusunokinin exhibited the strongest cytotoxicity against A2780cis cells with an IC50 value of 3.4 µM whilst also reducing the colony formation of A2780 and A2780cis cells. Trans-(±)-kusunokinin also induced the cells to undergo apoptosis and increased multi-caspase activity in A2780 and A2780cis cells. This compound significantly downregulated topoisomerase II, cyclin D1 and CDK1 expression, but upregulated Bax and PUMA expression in both A2780 and A2780cis cells. In conclusion, trans-(±)-kusunokinin suppressed ovarian cancer cells through the inhibition of colony formation, cell proliferation and the induction of apoptosis. This pure compound could be a potential targeted therapy for ovarian cancer treatment in the future. However, studies in an animal model and clinical trial need to be performed to support the efficacy and safety of this new treatment.

Molecular and clinical determinants of response and resistance to rucaparib for recurrent ovarian cancer treatment in ARIEL2 (Parts 1 and 2)

ARIEL2 (NCT01891344) is a single-arm, open-label phase 2 study of the PARP inhibitor (PARPi) rucaparib in relapsed high-grade ovarian carcinoma. In this post hoc exploratory biomarker analysis of pre- and post-platinum ARIEL2 samples, RAD51C and RAD51D mutations and high-level BRCA1 promoter methylation predict response to rucaparib, similar to BRCA1/BRCA2 mutations. BRCA1 methylation loss may be a major cross-resistance mechanism to platinum and PARPi. Genomic scars associated with homologous recombination deficiency are irreversible, persisting even as platinum resistance develops, and therefore are predictive of rucaparib response only in platinum-sensitive disease. The RAS, AKT, and cell cycle pathways may be additional modulators of PARPi sensitivity.

Systematic Investigation of DNA Methylation Associated With Platinum Chemotherapy Resistance Across 13 Cancer Types

Background: Platinum resistance poses a significant problem for oncology clinicians. As a result, the role of epigenetics and DNA methylation in platinum-based chemoresistance has gained increasing attention from researchers in recent years. A systematic investigation of aberrant methylation patterns related to platinum resistance across various cancer types is urgently needed.

Methods: We analyzed the platinum chemotherapy response-related methylation patterns from different perspectives of 618 patients across 13 cancer types and integrated transcriptional and clinical data. Spearman’s test was used to evaluate the correlation between methylation and gene expression. Cox analysis, the Kaplan-Meier method, and log-rank tests were performed to identify potential risk biomarkers based on differentially methylated positions (DMPs) and compare survival based on DMP values. Support vector machines and receiver operating characteristic curves were used to identify the platinum-response predictive DMPs.

Results: A total of 3,703 DMPs (p value < 0.001 and absolute delta beta >0.10) were identified, and the DMP numbers of each cancer type varied. A total of 39.83% of DMPs were hypermethylated and 60.17% were hypomethylated in platinum-resistant patients. Among them, 405 DMPs (Benjamini and Hochberg adjusted p value < 0.05) were found to be associated with prognosis in tumor patients treated with platinum-based regimens, and 664 DMPs displayed the potential to predict platinum chemotherapy response. In addition, we defined six DNA DMPs consisting of four gene members (mesothelin, protein kinase cAMP-dependent type II regulatory subunit beta, msh homeobox 1, and par-6 family cell polarity regulator alpha) that may have favorable prognostic and predictive values for platinum chemotherapy.

Conclusion: The methylation-transcription axis exists and participates in the complex biological mechanism of platinum resistance in various cancers. Six DMPs and four associated genes may have the potential to serve as promising epigenetic biomarkers for platinum-based chemotherapy and guide clinical selection of optimal treatment.

Targeting of Deregulated Wnt/β-Catenin Signaling by PRI-724 and LGK974 Inhibitors in Germ Cell Tumor Cell Lines

The majority of patients with testicular germ cell tumors (GCTs) can be cured with cisplatin-based chemotherapy. However, for a subset of patients present with cisplatin-refractory disease, which confers a poor prognosis, the treatment options are limited. Novel therapies are therefore urgently needed to improve outcomes in this challenging patient population. It has previously been shown that Wnt/β-catenin signaling is active in GCTs suggesting that its inhibitors LGK974 and PRI-724 may show promise in the management of cisplatin-refractory GCTs. We herein investigated whether LGK-974 and PRI-724 provide a treatment effect in cisplatin-resistant GCT cell lines. Taking a genoproteomic approach and utilizing xenograft models we found the increased level of β-catenin in 2 of 4 cisplatin-resistant (CisR) cell lines (TCam-2 CisR and NCCIT CisR) and the decreased level of β-catenin and cyclin D1 in cisplatin-resistant NTERA-2 CisR cell line. While the effect of treatment with LGK974 was limited or none, the NTERA-2 CisR exhibited the increased sensitivity to PRI-724 in comparison with parental cell line. Furthermore, the pro-apoptotic effect of PRI-724 was documented in all cell lines. Our data strongly suggests that a Wnt/β-catenin signaling is altered in cisplatin-resistant GCT cell lines and the inhibition with PRI-724 is effective in NTERA-2 CisR cells. Further evaluation of Wnt/β-catenin pathway inhibition in GCTs is therefore warranted.

Germline and Somatic Genetic Variants in the p53 Pathway Interact to Affect Cancer Risk, Progression, and Drug Response

Insights into oncogenesis derived from cancer susceptibility loci (SNP) hold the potential to facilitate better cancer management and treatment through precision oncology. However, therapeutic insights have thus far been limited by our current lack of understanding regarding both interactions of these loci with somatic cancer driver mutations and their influence on tumorigenesis. For example, although both germline and somatic genetic variation to the p53 tumor suppressor pathway are known to promote tumorigenesis, little is known about the extent to which such variants cooperate to alter pathway activity. Here we hypothesize that cancer risk-associated germline variants interact with somatic TP53 mutational status to modify cancer risk, progression, and response to therapy. Focusing on a cancer risk SNP (rs78378222) with a well-documented ability to directly influence p53 activity as well as integration of germline datasets relating to cancer susceptibility with tumor data capturing somatically-acquired genetic variation provided supportive evidence for this hypothesis. Integration of germline and somatic genetic data enabled identification of a novel entry point for therapeutic manipulation of p53 activities. A cluster of cancer risk SNPs resulted in increased expression of prosurvival p53 target gene KITLG and attenuation of p53-mediated responses to genotoxic therapies, which were reversed by pharmacologic inhibition of the prosurvival c-KIT signal. Together, our results offer evidence of how cancer susceptibility SNPs can interact with cancer driver genes to affect cancer progression and identify novel combinatorial therapies. SIGNIFICANCE: These results offer evidence of how cancer susceptibility SNPs can interact with cancer driver genes to affect cancer progression and present novel therapeutic targets.

Nanocarrier-delivered small interfering RNA for chemoresistant ovarian cancer therapy

Ovarian cancer is the fifth leading cause of cancer-related death in women in the United States. Because success in early screening is limited, and most patients with advanced disease develop resistance to multiple treatment modalities, the overall prognosis of ovarian cancer is poor. Despite the revolutionary role of surgery and chemotherapy in curing ovarian cancer, recurrence remains a major challenge in treatment. Thus, improving our understanding of the pathogenesis of ovarian cancer is essential for developing more effective treatments. In this review, we analyze the underlying molecular mechanisms leading to chemotherapy resistance. We discuss the clinical benefits and potential challenges of using nanocarrier-delivered small interfering RNA to treat chemotherapy-resistant ovarian cancer. We aim to elicit collaborative studies on nanocarrier-delivered small interfering RNA to improve the long-term survival rate and quality of life of patients with ovarian cancer. This article is categorized under: RNA Methods > RNA Nanotechnology Regulatory RNAs/RNAi/Riboswitches > RNAi: Mechanisms of Action.

Loss of Mediator complex subunit 13 (MED13) promotes resistance to alkylation through cyclin D1 upregulation

Alkylating drugs are among the most often used chemotherapeutics. While cancer cells frequently develop resistance to alkylation treatments, detailed understanding of mechanisms that lead to the resistance is limited. Here, by using genome-wide CRISPR-Cas9 based screen, we identify transcriptional Mediator complex subunit 13 (MED13) as a novel modulator of alkylation response. The alkylation exposure causes significant MED13 downregulation, while complete loss of MED13 results in reduced apoptosis and resistance to alkylating agents. Transcriptome analysis identified cyclin D1 (CCND1) as one of the highly overexpressed genes in MED13 knock-out (KO) cells, characterized by shorter G1 phase. MED13 is able to bind to CCND1 regulatory elements thus influencing the expression. The resistance of MED13 KO cells is directly dependent on the cyclin D1 overexpression, and its down-regulation is sufficient to re-sensitize the cells to alkylating agents. We further demonstrate the therapeutic potential of MED13-mediated response, by applying combinatory treatment with CDK8/19 inhibitor Senexin A. Importantly, the treatment with Senexin A stabilizes MED13, and in combination with alkylating agents significantly reduces viability of cancer cells. In summary, our findings identify novel alkylation stress response mechanism dependent on MED13 and cyclin D1 that can serve as basis for development of innovative therapeutic strategies.

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.

miR-20b-5p functions as tumor suppressor microRNA by targeting cyclinD1 in colon cancer

MicroRNA functions as an oncogenic regulator or tumor suppressor in various human tumors. Although bioinformatics analysis suggested that miRNA-20b-5p may be associated with the tumorigenesis, its role in colon cancer remains elusive. To investigate the role of miRNA-20b-5p, HCT116 cell, a human colon cancer cell line used in therapeutic research and drug screenings, was chosen as a model system for our in vitro studies. We first carried out bioinformatics and microarray analysis. To gain further mechanism insight, flow cytometry was performed to determine cell apoptosis and cell cycle, and western blot or immunohistochemistry were employed to check the expression of CCND1/CDK/FOXM1 axis in HCT116 cells. In addition, wound-healing migration assay and transwell assay were conducted to uncover the effect of miR-20b-5p on tumor migration and invasion. Finally, we examined the role of miR-20b-5p by subcutaneous xenograft mouse models. Our data have shown that miRNA-20b-5p inhibited the cell cycle, migration, and invasion in HCT116 cells, but had no effect on cell apoptosis. CyclinD1 (CCND1) was identified as a direct target of miR-20b-5p. Overexpression of miRNA-20b-5p downregulated CCND1 level in HCT-116 cells. Mechanically, the inhibition of cell cycle, migration, and invasion of CC cells mediated by miRNA-20b-5p are through regulating the CCND1/CDK4/FOXM1 axis. Furthermore, miRNA-20b-5p inhibited the tumorigenesis in Balb/c nude mice CC xenograft models. Our data demonstrated that miR-20b-5p may serve as a tumor suppressor in colon cancer by negatively regulating CCND1, implying that miR-20b-5p could be a potential therapeutic target for the treatment of colon cancer.

Cisplatin Resistance in Testicular Germ Cell Tumors: Current Challenges from Various Perspectives

Testicular germ cell tumors share a marked sensitivity to cisplatin, contributing to their overall good prognosis. However, a subset of patients develop resistance to platinum-based treatments, by still-elusive mechanisms, experiencing poor quality of life due to multiple (often ineffective) interventions and, eventually, dying from disease. Currently, there is a lack of defined treatment opportunities for these patients that tackle the mechanism(s) underlying the emergence of resistance. Herein, we aim to provide a multifaceted overview of cisplatin resistance in testicular germ cell tumors, from the clinical perspective, to the pathobiology (including mechanisms contributing to induction of the resistant phenotype), to experimental models available for studying this occurrence. We provide a systematic summary of pre-target, on-target, post-target, and off-target mechanisms putatively involved in cisplatin resistance, providing data from preclinical studies and from those attempting validation in clinical samples, including those exploring specific alterations as therapeutic targets, some of them included in ongoing clinical trials. We briefly discuss the specificities of resistance related to teratoma (differentiated) phenotype, including the phenomena of growing teratoma syndrome and development of somatic-type malignancy. Cisplatin resistance is most likely multifactorial, and a combination of therapeutic strategies will most likely produce the best clinical benefit.

Therapeutic Challenges for Cisplatin-Resistant Ovarian Germ Cell Tumors

The majority of patients with advanced ovarian germ cell cancer are treated by cisplatin-based chemotherapy. Despite adequate first-line treatment, nearly one third of patients relapse and almost half develop cisplatin-resistant disease, which is often fatal. The treatment of cisplatin-resistant disease is challenging and prognosis remains poor. There are limited data on the efficacy of specific chemotherapeutic regimens, high-dose chemotherapy with autologous progenitor cell support and targeted therapies. The inclusion of patients in clinical trials is strongly recommended, especially in clinical trials on the most frequent male germ cell tumors, to offer wider therapeutic opportunities. Here, we provide an overview of current and potential new treatment options including combination chemotherapy, high-dose chemotherapy and molecular targeted therapies, for patients with cisplatin-resistant ovarian germ cell tumors.

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.

The dual PI3K/mTOR inhibitor BEZ235 restricts the growth of lung cancer tumors regardless of EGFR status, as a potent accompanist in combined therapeutic regimens

Background

Lung cancer is the most common cause of cancer-related mortality worldwide despite diagnostic improvements and the development of targeted therapies, notably including epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs). The phosphoinositide 3-kinase (PI3K)/AKT/mechanistic target of rapamycin (mTOR) signaling has been shown to contribute to tumorigenesis, tumor progression, and resistance to therapy in most human cancer types, including lung cancer. Here, we explored the therapeutic effects of co-inhibition of PI3K and mTOR in non-small-cell lung cancer (NSCLC) cells with different EGFR status.

Methods

The antiproliferative activity of a dual PI3K/mTOR inhibitor BEZ235 was examined by the WST-1 assay and the soft agar colony-formation assay in 2 normal cell lines and 12 NSCLC cell lines: 6 expressing wild-type EGFR and 6 expressing EGFR with activating mutations, including exon 19 deletions, and L858R and T790 M point mutations. The combination indexes of BEZ235 with cisplatin or an EGFR-TKI, BIBW2992 (afatinib), were calculated. The mechanisms triggered by BEZ235 were explored by western blotting analysis. The anti-tumor effect of BEZ235 alone or combined with cisplatin or BIBW2992 were also studied in vivo.

Results

BEZ235 suppressed tumor growth in vitro and in vivo by inducing cell-cycle arrest at G1 phase, but without causing cell death. It also reduced the expression of cyclin D1/D3 by regulating both its transcription and protein stability. Moreover, BEZ235 synergistically enhanced cisplatin-induced apoptosis in NSCLC cells by enhancing or prolonging DNA damage and BIBW2992-induced apoptosis in EGFR-TKI–resistant NSCLC cells containing a second TKI-resistant EGFR mutant.

Conclusions

The dual PI3K/mTOR inhibition by BEZ235 is an effective antitumor strategy for enhancing the efficacy of chemotherapy or targeted therapy, even as a monotherapy, to restrict tumor growth in lung cancer treatment.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1282-0) contains supplementary material, which is available to authorized users.

The potential of brentuximab vedotin, alone or in combination with current clinical therapies, in the treatment of testicular germ cell tumors

Testicular germ cell tumors (TGCTs) are the commonest tumors in young men. With the advancement of chemotherapies, most TGCTs are successfully cured, even when diagnosed at an advanced and metastatic stage. However, a proportion of often young patients, median age 35-40, with advanced disease are not cured and will inevitably die. Therefore, there is an unmet need in this small population of young patients who are candidates for experimental approaches. We investigated a new therapeutic option for this group of patients, aiming to significantly improve their outcome. In recent years, many targeted therapies have been developed which demonstrated high efficacy and low toxicity. Brentuximab vedotin, a monomethyl auristatin E conjugated CD30 antibody, targets CD30 to kill cancer cells. As a large proportion of TGCTs express CD30, in particular embryonal carcinomas, we investigated in vitro the efficacy of brentuximab vedotin in treating TGCTs as a single therapy and in combination with commonly used chemotherapy drugs. We determined CD30 expression levels in 12 TGCT cell lines, including three cisplatin resistant sublines. In general, the efficiency of cancer cell inhibition by brentuximab vedotin correlates with CD30 expression, but there were some exceptions. We also determined the efficacy of brentuximab vedotin in combination with commonly used chemotherapy drugs and found synergistic/additive effects with etoposide, paclitaxel and SN-38. However, cisplatin, the most commonly used chemotherapy drug in TGCT treatment, exhibited antagonism and we showed that cisplatin selectively kills CD30 positive cells. We also found that certain agents, which have been reported to induce CD30 expression in other human malignant diseases, including DNA demethylation drugs, methotrexate and CD30 ligands, were unable to enhance CD30 expression or brentuximab vedotin efficacy in TGCT cells. This study will help to design clinical trials using brentuximab vedotin for the treatment of TGCTs, either as a single agent or in combination with current clinical therapies.

Combined analysis and validation for DNA methylation and gene expression profiles associated with prostate cancer

BACKGROUND

Prostate cancer (PCa) is a malignancy cause of cancer deaths and frequently diagnosed in male. This study aimed to identify tumor suppressor genes, hub genes and their pathways by combined bioinformatics analysis.

METHODS

A combined analysis method was used for two types of microarray datasets (DNA methylation and gene expression profiles) from the Gene Expression Omnibus (GEO). Differentially methylated genes (DMGs) were identified by the R package minfi and differentially expressed genes (DEGs) were screened out via the R package limma. A total of 4451 DMGs and 1509 DEGs, identified with nine overlaps between DMGs, DEGs and tumor suppressor genes, were screened for candidate tumor suppressor genes. All these nine candidate tumor suppressor genes were validated by TCGA (The Cancer Genome Atlas) database and Oncomine database. And then, the gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes pathway (KEGG) enrichment analyses were performed by DAVID (Database for Annotation, Visualization and Integrated Discovery) database. Protein-protein interaction (PPI) network was constructed by STRING and visualized in Cytoscape. At last, Kaplan-Meier analysis was performed to validate these genes.

RESULTS

The candidate tumor suppressor genes were IKZF1, PPM1A, FBP1, SMCHD1, ALPL, CASP5, PYHIN1, DAPK1 and CASP8. By validation in TCGA database, PPM1A, DAPK1, FBP1, PYHIN1, ALPL and SMCHD1 were significant. The hub genes were FGFR1, FGF13 and CCND1. These hub genes were identified from the PPI network, and sub-networks revealed by these genes were involved in significant pathways.

CONCLUSION

In summary, the study indicated that the combined analysis for identifying target genes with PCa by bioinformatics tools promote our understanding of the molecular mechanisms and underlying the development of PCa. And the hub genes might serve as molecular targets and diagnostic biomarkers for precise diagnosis and treatment of PCa.

Novel genetic alterations and their impact on target therapy response in head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) is highly variable by tumor site, histologic type, molecular characteristics, and clinical outcome. During recent years, emerging targeted therapies have been focused on driver genes. HNSCC involves several genetic alterations, such as co-occurrence, multiple feedback loops, and cross-talk communications. These different kinds of genetic alterations interact with each other and mediate targeted therapy response. In the current review, it is emphasized that future treatment strategy in HNSCC will not solely be based on "synthetic lethality" approaches directed against overactivated genes. More importantly, biologic, genetic, and epigenetic alterations of HNSCC will be taken into consideration to guide the therapy. The emerging genetic alterations in HNSCC and its effect on targeted therapy response are discussed in detail. Hopefully, novel combination regimens for the treatment of HNSCC can be developed.

Identification of mTOR inhibitor-resistant genes in cutaneous squamous cell carcinoma

Purpose

The PI3K/AKT/mTOR pathway is frequently activated in various squamous cell carcinomas (SCCs). Although mTOR inhibitors are suggested as effective treatments in immunosuppressed patients with metastatic SCC, they are still not proven to be favorable in treating skin SCC patients not undergoing immunosuppressive therapy. Moreover, the exact mechanism of the mTOR signaling pathway in SCC has not yet been identified. In this study, we aimed to determine the genes associated with mTOR inhibitors in skin SCC.

Materials and methods

The identification of cell viability according to concentration of everolimus and Western blot was done. To analyze the global gene expression profiles, A431 and HSC-1 cells were treated with dimethyl sulfoxide (DMSO) or 100 nM of everolimus for 72 hours. Furthermore, differentially expressed genes (DEGs) were identified using Affymetrix analysis. To identify the gene network associated with everolimus resistance in SCC cells, pathway analysis was performed using the Ingenuity Pathway Analysis (IPA) tool.

Results

The effects of cell death with respect to the mTOR inhibitor concentration were observed in the HSC-1 cell line; however, the mTOR inhibitor did not show effective cytotoxic activity in the A431 cell line. p-mTOR concentration also diminished with respect to everolimus concentrations in the HSC-1 cell line. Moreover, the microarray results showed that the MYC/CCND1/TP73/NUPR1/SBD/ERBB2/CDKN2B genes were related to mTOR inhibitor resistance. However, CCND1 gene overexpression was most closely related to mTOR inhibitor resistance.

Conclusion

We identified mTOR inhibitor resistance genes, and our findings may help select therapeutic targets in skin SCC.

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.

Evaluation of the Role Played by Cyclin D1 as a Diagnostic and Prognostic Marker in the Progression of Oral Carcinogenesis

Abstract

Cyclin D1 is linked with the development and progression of oral squamous cell carcinoma (OSCC). This case-control study was directed to characterise the immunoreactivity of the protein cyclin D1 and its correlation with the clinicopathological parameters of patients with OSCC and potentially malignant disorders (PMD). A group of patients with OSCC were followed up after treatment, and the cyclin D1 expression was reviewed for correlation of cyclin D1 expression with prognosis of the patients.

Methodology

Sixty individuals were included in this study: OSCC (20), PMD (20) and Control (20). Immunohistochemistry assay was evaluated. The clinicopathological parameters were correlated with the staining intensity of cyclin D1. The results were subjected to Pearson's correlation test.

Results

Age, gender and site showed no statistically significant correlation with cyclin D1 expression in OSCC and PMD. The cyclin D1 score did not show a significant difference with histopathological diagnosis of OSCC. Cyclin D1 was not expressed in 60% of the Control and 30% PMD cases while the expression of cyclin D1 was seen in 100% of OSCC cases although cyclin D1 score did not show a statistically significant association in the prognosis of the disease among the OSCC patients.

Downregulation of AGR2, p21, and cyclin D and alterations in p53 function were associated with tumor progression and chemotherapy resistance in epithelial ovarian carcinoma

Anterior gradient 2 protein belongs to a family of chaperone‐like proteins, namely protein disulfide isomerase. Generally, AGR2 is highly expressed in mucus‐secreting cells and endocrine organs, and in this study, we aimed to evaluate AGR2 and cell cycle molecules in epithelial ovarian cancer and its implications on prognosis. One hundred seventy‐five patient's samples that were diagnosed with primary epithelial ovarian carcinoma were selected. All the patients were treated with platinum‐taxane standard chemotherapy after surgery and CA125 serum levels were routinely determined. Four‐micrometer‐thick sections were processed by immunohistochemistry using an automated immunostainer, Ventana BenchMark AutoStainer with AGR2, cyclin D1, p21WAF1, and p53. Forty‐nine of 167 cases (29.3%) showed strong to moderate cytoplasmic marking of AGR2, and 118 (70.7%) had weak to negative expression. The absence of the AGR2 protein was observed in high‐grade serous carcinoma (P < .001) and significantly associated with disease‐free survival (DFS; P = .034). The expression of G1‐S phase‐regulatory proteins showed loss of p21 in high‐grade serous carcinoma (P < .001) and was related with poor DFS (P = .003). Strong and diffuse immunoexpression of p53 plus complete absence of p53 staining was interpreted as likely indicating a TP53 gene mutation. This result showed worse DFS alone (P = .012) and combined with low levels of AGR2 (P = .005). The expression profile of AGR2 and cell cycle proteins here presented was showed as good prognosis marker in epithelial ovarian cancer. This finding suggests AGR2 and as putative biomarker of disease progression in chemotherapy‐treated high‐grade serous carcinoma patients.

Identification of genes and pathways associated with MDR in MCF-7/MDR breast cancer cells by RNA-seq analysis

Multidrug resistance (MDR) is a major problem in the treatment of breast cancer. In the present study, next-generation sequencing technology was employed to identify differentially expressed genes in MCF-7/MDR cells and MCF-7 cells, and aimed to investigate the underlying molecular mechanisms of MDR in breast cancer. Differentially expressed genes between MCF-7/MDR and MCF-7 cells were selected using software; a total of 2085 genes were screened as differentially expressed in MCF-7/MDR cells. Furthermore, gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed using the DAVID database. Finally, a protein-protein interaction network was constructed and the hub genes in the network were analyzed using the STRING database. GO annotation demonstrated that the differentially expressed genes were enriched in various biological processes, including ‘regulation of cell differentiation’, ‘cell development’, ‘neuron development’, ‘movement of cell or subcellular component’ and ‘cell morphogenesis involved in neuron differentiation’. Cellular component analysis by GO revealed that differentially expressed genes were enriched in ‘plasma membrane region’ and ‘extracellular matrix’ terms. Furthermore, KEGG analysis demonstrated that the target genes were enriched in various pathways, including ‘cell adhesion molecules (CAMs)’, ‘calcium signaling pathway’, ‘tight junction’, ‘Wnt signaling pathway’ and ‘pathways in cancer’ terms. A protein-protein interaction network demonstrated that certain hub genes, including cyclin D1, nitric oxide synthase 3 (NOS3), NOTCH3, brain-derived neurotrophic factor (BDNF), paired box 6, neuropeptide Y, phospholipase C β (PLCB) 4, PLCB2 and actin α cardiac muscle 1, may be associated with MDR in breast cancer. Subsequently, RT-qPCR confirmed that the expression of these 9 hub genes was higher in MCF-7/MDR cells compared with MCF-7 cells, consistent with the RNA-sequencing analysis. Additionally, a Cell Counting Kit-8 assay demonstrated that specific inhibitors of NOS3 and BDNF/neurotrophic receptor tyrosine kinase, type 2 signaling reduced the IC₅₀ of MCF-7/MDR cells in response to various anticancer drugs, including adriamycin, cisplatin and 5-fluorouracil. The results of the present study provide novel insights into the mechanism underlying MDR in MCF-7 cells and may identify novel targets for the treatment of breast cancer.

Post-transcriptional Regulation of Genes Related to Biological Behaviors of Gastric Cancer by Long Noncoding RNAs and MicroRNAs

Noncoding RNAs play critical roles in regulating protein-coding genes and comprise two major classes: long noncoding RNAs (lncRNAs) and microRNAs (miRNAs). LncRNAs regulate gene expression at transcriptional, post-transcriptional, and epigenetic levels via multiple action modes. LncRNAs can also function as endogenous competitive RNAs for miRNAs and indirectly regulate gene expression post-transcriptionally. By binding to the 3'-untranslated regions (3'-UTR) of target genes, miRNAs post-transcriptionally regulate gene expression. Herein, we conducted a review of post-transcriptional regulation by lncRNAs and miRNAs of genes associated with biological behaviors of gastric cancer.

Identifying differential networks based on multi-platform gene expression data

Exploring how the structure of a gene regulatory network differs between two different disease states is fundamental for understanding the biological mechanisms behind disease development and progression. Recently, with rapid advances in microarray technologies, gene expression profiles of the same patients can be collected from multiple microarray platforms. However, previous differential network analysis methods were usually developed based on a single type of platform, which could not utilize the common information shared across different platforms. In this study, we introduce a multi-view differential network analysis model to infer the differential network between two different patient groups based on gene expression profiles collected from multiple platforms. Unlike previous differential network analysis models that need to analyze each platform separately, our model can draw support from multiple data platforms to jointly estimate the differential networks and produce more accurate and reliable results. Our simulation studies demonstrate that our method consistently outperforms other available differential network analysis methods. We also applied our method to identify network rewiring associated with platinum resistance using TCGA ovarian cancer samples. The experimental results demonstrate that the hub genes in our identified differential networks on the PI3K/AKT/mTOR pathway play an important role in drug resistance.

Efficacy of targeted drugs in germ cell cancer cell lines with differential cisplatin sensitivity

Testicular germ cell tumors (TGCTs) are the most common malignancies in men between the age of 15 and 35. Although cisplatin-based chemotherapy is highly effective in advanced disease, approximately 20% of patients have an unfavorable prognosis due to primary or acquired cisplatin resistance. For these patients, new therapeutic options are urgently needed. In numerous tumor entities, combinations of monoclonal antibodies or kinase inhibitors with chemotherapy exerted promising preclinical or clinical results, which have led to new treatment concepts. This prompted us to investigate the activity of different targeted agents alone or in combination with cisplatin in a panel of TGCT cell lines.

Enantiomerically pure β-dipeptide derivative induces anticancer activity against human hormone-refractory prostate cancer through both PI3K/Akt-dependent and -independent pathways

The use of peptides that target cancer cells and induce anticancer activities through various mechanisms is developing as a potential anticancer strategy. KUD983, an enantiomerically pure β-dipeptide derivative, displays potent activity against hormone-refractory prostate cancer (HRPC) PC-3 and DU145 cells with submicromolar IC₅₀. KUD983 induced G1 arrest of the cell cycle and subsequent apoptosis associated with down-regulation of several related proteins including cyclin D1, cyclin E and Cdk4, and the de-phosphorylation of RB. The levels of nuclear and total c-Myc protein, which could increase the expression of both cyclin D1 and cyclin E, were profoundly inhibited by KUD983. Furthermore, it inhibited PI3K/Akt and mTOR/p70S6K/4E-BP1 pathways, the key signaling in multiple cellular functions. The transient transfection of constitutively active myristylated Akt (myr-Akt) cDNA significantly rescued KUD983-induced caspase activation but did not blunt the inhibition of mTOR/p70S6K/4E-BP1 signaling cascade suggesting the presence of both Akt-dependent and -independent pathways. Moreover, KUD983-induced effect was enhanced with the down-regulation of anti-apoptotic Bcl-2 members (e.g., Bcl-2, and Mcl-1) and IAP family members (e.g., survivin). Notably, KUD983 induced autophagic cell death using confocal microscopic examination, tracking the level of conversion of LC3-I to LC3-II and flow cytometric detection of acidic vesicular organelles-positive cells. In conclusion, the data suggest that KUD983 is an anticancer β-dipeptide against HRPCs through the inhibition of cell proliferation and induction of apoptotic and autophagic cell death. The suppression of signaling pathways regulated by c-Myc, PI3K/Akt and mTOR/p70S6K/4E-BP1 and the collaboration with down-regulation of Mcl-1 and survivin may explain KUD983-induced anti-HRPC mechanism.

Investigation of the anti-cancer effect of quercetin on HepG2 cells in vivo

Quercetin, a natural polyphenolic flavonoid compound, can inhibit the growth of several malignant cancers. However, the mechanism still remains unclear. Our previous findings have suggested that quercetin can significantly inhibit HepG2 cell proliferation and induce cell apoptosis in vitro. It can also affect cell cycle distribution and significantly decrease cyclin D1 expression. In this study, we investigated the anti-cancer effect of quercetin on HepG2 tumor-bearing nude mice and its effect on cyclin D1 expression in the tumor tissue. First, the nude murine tumor model was established by subcutaneous inoculation of HepG2 cells, then quercetin was administered intraperitoneally, and the mice injected with saline solution were used as controls. The daily behavior of the tumor-bearing mice was observed and differences in tumor growth and survival rate were monitored. The expression of cyclin D1 in isolated tumor sections was evaluated by immunohistochemistry. We found that HepG2 tumor became palpable in the mice one-week post-inoculation. Tumors in the control group grew rapidly and the daily behavior of the mice changed significantly, including listlessness, poor feeding and ataxia. The mice in quercetin-treated group showed delayed tumor growth, no significant changes in daily behavior, and the survival rate was significantly improved. Finally, we observed increased tumor necrosis and a lighter cyclin D1 staining with reduced staining areas. Our findings thus suggest that quercetin can significantly inhibit HepG2 cell proliferation, and this effect may be achieved through the regulation of cyclin D1 expression.

Testicular germ cell tumor genomics

PURPOSE OF REVIEW

Testicular germ cell tumors (TGCTs) are a model for curable cancer because of exquisite chemosensitivity and incorporation of multimodal therapy. Nevertheless, our ability to predict metastases in early-stage disease and responders to chemotherapy in advanced disease is limited. Treatment options for cisplatin-resistant disease are sparse. A further understanding of TGCT biology may allow for more precise patient counseling and identify novel therapies in patients with cisplatin-resistant disease.

RECENT FINDINGS

Adult TGCTs are characterized by frequent chromosomal anomalies and low rates of somatic mutations. Large-scale integrated molecular analysis of early-stage TGCT patients is actively underway. In addition to ubiquitous gain of isochromosome 12p, current molecular studies have confirmed mutations of previously described genes (i.e., KIT and KRAS) and described novel mutations. Analysis of cisplatin-resistant cases has identified high rates of alterations within the TP53-MDM2 axis and a high proportion of patients with potentially actionable targets, including TP53-MDM2, PI3 kinase, and MAPK signaling pathway alterations. The role of epigenetics in TGCT development and prognosis is also being further characterized.

SUMMARY

Further molecular characterization of TGCT may allow for avoidance of unnecessary treatment in patients with early-stage disease and also provide new treatment options in patients with cisplatin-resistant disease.

Acquired resistance of pancreatic cancer cells to cisplatin is multifactorial with cell context-dependent involvement of resistance genes

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal of malignancies, in large measure, due to the propensity of PDAC cells to acquire resistance to chemotherapeutic agents. A better understanding of the molecular basis of acquired resistance is a major focus of contemporary PDAC research. We report here the results of a study to independently develop cisplatin resistance in two distinct parental PDAC cell lines, AsPC1 and BxPC3, and to subsequently examine the molecular mechanisms associated with the acquired resistance. Cisplatin resistance in both resistant cell lines was found to be multifactorial and to be associated with mechanisms related to drug transport, drug inactivation, DNA damage response, DNA repair and the modulation of apoptosis. Our results demonstrate that the two resistant cell lines employed alternative molecular strategies in acquiring resistance dictated, in part, by pre-existing molecular differences between the parental cell lines. Collectively, our findings indicate that strategies to inhibit or reverse acquired resistance of PDAC cells to cisplatin, and perhaps other chemotherapeutic agents, may not be generalized but will require individual molecular profiling and analysis to be effective.

LncRNA HOTAIR promotes cisplatin resistance in gastric cancer by targeting miR-126 to activate the PI3K/AKT/MRP1 genes

Altered expression of long noncoding RNAs (lncRNAs) has shown to associate with human cancer development and progression and drug resistance. LncRNA HOX antisense intergenic RNA (HOTAIR) regulates chromatin state and highly expressed in various human cancers. This study analyzed HOTAIR expression in gastric cancer cells and tissues and then assessed the effects of HOTAIR on modulation of gastric cancer cell sensitivity to cisplatin and the underlying molecular events. The data showed that HOTAIR was significantly upregulated in cisplatin-resistant gastric cancer cells and tissues compared with control cells and noncancerous gastric tissues. Overexpression of HOTAIR enhanced gastric cancer cell proliferation, promoted cell cycle G1/S transition, but decreased tumor cell apoptosis. Furthermore, HOTAIR was shown to directly bind to and inhibit miR-126 expression and then to promote VEGFA and PIK3R2 expression and activate the PI3K/AKT/MRP1 pathway. In conclusion, the data demonstrated that high HOTAIR expression acted as a competitive endogenous RNA to promote cisplatin resistance in gastric cancer. Further study will evaluate HOTAIR expression as a biomarker to predict treatment response of cisplatin and explore inhibition of HOTAIR expression as a novel strategy for anti-cisplatin resistance in human gastric cancer.

Rapamycin inhibits prostate cancer cell growth through cyclin D1 and enhances the cytotoxic efficacy of cisplatin

Prostate cancer is the most common malignancy in Western men and hormone refractory cancer (HRPC) kills most of the patients. Chemo-resistance is a major obstacle for the treatment of prostate cancer. Platinum-complexes have been used to treat a number of malignancies including prostate cancer. However, it has limited effect to prostate cancer and with significant toxicity at higher doses. In recent years, increasing numbers of new agents targeting cancer specific pathways have become available and with low toxic side-effects. Rapamycin (Sirolimus) is an mTORC1 inhibitor, which inhibits the PI3K/Akt/mTOR signaling pathway, which is commonly altered in prostate cancer. We determined the expression of cyclin D1 and phosphorylated-mTOR proteins in association with the response to rapamycin in two androgen sensitive (22RV1 and LNCaP) and two androgen independent (DU145 and PC3) prostate cancer cell lines and found that the base-line and changes of cyclin D1 level, but not the expression level of p-mTOR, correlated with rapamycin sensitivity. We evaluated the cell killing effect of combined rapamycin and cisplatin treatment and showed that the combination had a more than additive effect in both androgen dependent and independent prostate cancer cells, which may be partially explained by the reduction of cyclin D1 expression by rapamycin. We also evaluated a range of combined treatment schedules, simultaneously or sequentially and found that continuous rapamycin treatment after a short cisplatin exposure was effective. The clinical application of these findings for prostate cancer treatment should be further investigated.

Cyclin D1 depletion induces DNA damage in mantle cell lymphoma lines

Elevated cyclin D1 (CCND1) expression levels in mantle cell lymphoma (MCL) are associated with aggressive clinical manifestations related to chemoresistance, but little is known about how this important proto-oncogene contributes to the resistance of MCL. Here, we showed that RNA interference-mediated depletion of CCND1 increased caspase-3 activities and induced apoptosis in the human MCL lines UPN-1 and JEKO-1. In vitro and xenotransplant studies revealed that the toxic effect of CCND1 depletion in MCL cells was likely due to increase in histone H2AX phosphorylation, a DNA damage marker. DNA fiber analysis suggested deregulated replication initiation after CCND1 depletion as a potential cause of DNA damage. Finally, in contrast to depletion or inhibition of cyclin-dependent kinase 4, CCND1 depletion increased chemosensitivity of MCL cells to replication inhibitors hydroxyurea and cytarabine. Our findings have an important implication for CCND1 as a potential therapeutic target in MCL patients who are refractory to standard chemotherapy.

The genomic landscape of testicular germ cell tumours: from susceptibility to treatment

The genomic landscape of testicular germ cell tumour (TGCT) can be summarized using four overarching hypotheses. Firstly, TGCT risk is dominated by inherited genetic factors, which determine nearly half of all disease risk and are highly polygenic in nature. Secondly KIT-KITLG signalling is currently the major pathway that is implicated in TGCT formation, both as a predisposition risk factor and a somatic driver event. Results from genome-wide association studies have also consistently suggested that other closely related pathways involved in male germ cell development and sex determination are associated with TGCT risk. Thirdly, the method of disease formation is unique, with tumours universally stemming from a noninvasive precursor lesion, probably of fetal origin, which lies dormant through childhood into adolescence and then eventually begins malignant growth in early adulthood. Formation of a 12p isochromosome, a hallmark of TGCT observed in nearly all tumours, is likely to be a key triggering event for malignant transformation. Finally, TGCT have been shown to have a distinctive somatic mutational profile, with a low rate of point mutations contrasted with frequent large-scale chromosomal gains. These four hypotheses by no means constitute a complete model that explains TGCT tumorigenesis, but advances in genomic technologies have enabled considerable progress in describing and understanding the disease. Further advancing our understanding of the genomic basis of TGCT offers a clear opportunity for clinical benefit in terms of preventing invasive cancer arising in young men, decreasing the burden of chemotherapy-related survivorship issues and reducing mortality in the minority of patients who have treatment-refractory disease.

Identification of selective cytotoxic and synthetic lethal drug responses in triple negative breast cancer cells

Background

Triple negative breast cancer (TNBC) is a highly heterogeneous and aggressive type of cancer that lacks effective targeted therapy. Despite detailed molecular profiling, no targeted therapy has been established. Hence, with the aim of gaining deeper understanding of the functional differences of TNBC subtypes and how that may relate to potential novel therapeutic strategies, we studied comprehensive anticancer-agent responses among a panel of TNBC cell lines.

Method

The responses of 301 approved and investigational oncology compounds were measured in 16 TNBC cell lines applying a functional profiling approach. To go beyond the standard drug viability effect profiling, which has been used in most chemosensitivity studies, we utilized a multiplexed readout for both cell viability and cytotoxicity, allowing us to differentiate between cytostatic and cytotoxic responses.

Results

Our approach revealed that most single-agent anti-cancer compounds that showed activity for the viability readout had no or little cytotoxic effects. Major compound classes that exhibited this type of response included anti-mitotics, mTOR, CDK, and metabolic inhibitors, as well as many agents selectively inhibiting oncogene-activated pathways. However, within the broad viability-acting classes of compounds, there were often subsets of cell lines that responded by cell death, suggesting that these cells are particularly vulnerable to the tested substance. In those cases we could identify differential levels of protein markers associated with cytotoxic responses. For example, PAI-1, MAPK phosphatase and Notch-3 levels associated with cytotoxic responses to mitotic and proteasome inhibitors, suggesting that these might serve as markers of response also in clinical settings. Furthermore, the cytotoxicity readout highlighted selective synergistic and synthetic lethal drug combinations that were missed by the cell viability readouts. For instance, the MEK inhibitor trametinib synergized with PARP inhibitors. Similarly, combination of two non-cytotoxic compounds, the rapamycin analog everolimus and an ATP-competitive mTOR inhibitor dactolisib, showed synthetic lethality in several mTOR-addicted cell lines.

Conclusions

Taken together, by studying the combination of cytotoxic and cytostatic drug responses, we identified a deeper spectrum of cellular responses both to single agents and combinations that may be highly relevant for identifying precision medicine approaches in TNBC as well as in other types of cancers.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-016-0517-3) contains supplementary material, which is available to authorized users.

Paradoxical roles of cyclin D1 in DNA stability

Maintenance of DNA integrity is vital for all of the living organisms. Consequence of DNA damaging ranges from, introducing harmless synonymous mutations, to causing disease-associated mutations, genome instability, and cell death. A cell cycle protein cyclin D1 is an established cancer-driving protein. However, contribution of cyclin D1 to cancer formation and cancer survival is not entirely known. In cancer tissues, overexpression of cyclin D1 is associated with both cancer genome instability, and resistance to DNA-damaging cancer drugs. Emerging evidence indicated that cyclin D1 may play novel direct roles in regulating DNA repair. Here we provide an insight how cyclin D1 expression may contribute to DNA repair and chromosome instability, and how these functions may facilitate cancer formation, and drug resistance.

Misexpression of cyclin D1 in embryonic germ cells promotes testicular teratoma initiation

Testicular teratomas result from anomalies in embryonic germ cell development. In the 129 family of inbred mouse strains, teratomas arise during the same developmental period that male germ cells normally enter G1/G0 mitotic arrest and female germ cells initiate meiosis (the mitotic:meiotic switch). Dysregulation of this switch associates with teratoma susceptibility and involves three germ cell developmental abnormalities seemingly critical for tumor initiation: delayed G1/G0 mitotic arrest, retention of pluripotency, and misexpression of genes normally restricted to embryonic female and adult male germ cells. One misexpressed gene, cyclin D1 (Ccnd1), is a known regulator of cell cycle progression and an oncogene in many tissues. Here, we investigated whether Ccnd1 misexpression in embryonic germ cells is a determinant of teratoma susceptibility in mice. We found that CCND1 localizes to teratoma-susceptible germ cells that fail to enter G1/G0 arrest during the mitotic:meiotic switch and is the only D-type cyclin misexpressed during this critical developmental time frame. We discovered that Ccnd1 deficiency in teratoma-susceptible mice significantly reduced teratoma incidence and suppressed the germ cell proliferation and pluripotency abnormalities associated with tumor initiation. Importantly, Ccnd1 expression was dispensable for somatic cell development and male germ cell specification and maturation in tumor-susceptible mice, implying that the mechanisms by which Ccnd1 deficiency reduced teratoma incidence were germ cell autonomous and specific to tumorigenesis. We conclude that misexpression of Ccnd1 in male germ cells is a key component of a larger pro-proliferative program that disrupts the mitotic:meiotic switch and predisposes 129 inbred mice to testicular teratocarcinogenesis.

Genome-wide transcriptional regulation of estrogen receptor targets in fallopian tube cells and the role of selective estrogen receptor modulators

Background

The fallopian tube epithelium is one of the potential sources of high-grade serous ovarian cancer (HGSC). The use of estrogen only hormone replacement therapy increases ovarian cancer (OVCA) risk. Despite estrogen’s influence in OVCA, selective estrogen receptor modulators (SERMs) typically demonstrate only a 20 % response rate. This low response could be due to a variety of factors including the loss of estrogen receptor signaling or the role of estrogen in different potential cell types of origin. The response of fallopian tube epithelium to SERMs is not known, and would be useful when determining therapeutic options for tumors arising from this cell type, such as HGSC.

Results

Using normal murine derived oviductal epithelial cells (mouse equivalent to the fallopian tube) estrogen receptor expression was confirmed and interaction with its ligand, estradiol, triggered mRNA and protein induction of progesterone receptor (PR). The SERMs 4-hydroxytamoxifen, raloxifene and desmethylarzoxifene, functioned as estrogen receptor antagonists in oviductal cells. Cellular proliferation and migration assays suggested that estradiol does not significantly impact cellular migration and increased proliferation. Further, using RNAseq, the oviduct specific transcriptional genes targets of ER when stimulated by estradiol and 4-hydroxytamoxifen signaling were determined and validated. The RNA-seq revealed enrichment in proliferation, anti-apoptosis, calcium signaling and steroid signaling processes. Finally, the ER and PR receptor status of a panel of HGSC cell lines was investigated including Kuramochi, OVSAHO, OVKATE, OVCAR3, and OVCAR4. OVSAHO demonstrated receptor expression and response, which highlights the need for additional models of ovarian cancer that are estrogen responsive.

Conclusions

Overall, the fallopian tube has specific gene targets of estrogen receptor and demonstrates a tissue specific response to SERMs consistent with antagonistic action.

Electronic supplementary material

The online version of this article (doi:10.1186/s13048-016-0213-3) contains supplementary material, which is available to authorized users.

Association between the Cyclin D1 G870A polymorphism and the susceptibility to and prognosis of upper aerodigestive tract squamous cell carcinomas: an updated meta-analysis

PURPOSE

Several publications have investigated the association between the Cyclin D1 G to A substitution at nucleotide 870 (CCND1 G870A) polymorphism and squamous cell carcinoma (SCC) of the upper aerodigestive tract (UADT), but their conclusions still remain controversial. We conducted a meta-analysis to precisely evaluate this association.

PATIENTS AND METHODS

We electronically searched the Chinese National Knowledge Infrastructure, PubMed, and Embase (up to January 2015) databases for case-control studies on the association between the CCND1 G870A polymorphism and SCC of the UADT, and 23 studies were included in total.

RESULTS

The meta-analysis results showed that there was a significant association between the CCND1 G870A polymorphism and the risk of SCC of the UADT (AA vs GG: odds ratio [OR] =1.33, 95% confidence interval [CI] =1.01-1.74, P<0.001 for heterogeneity; GA/AA vs GG: OR =1.24, 95% CI =1.01-1.51, P<0.001 for heterogeneity; AA vs

GA/GG

OR =1.16, 95% CI =0.97-1.39, P<0.001 for heterogeneity; allele A vs allele G: OR =1.14, 95% CI =1.00-1.30, P<0.001 for heterogeneity; GA vs GG: OR =1.18, 95% CI =0.98-1.42, P<0.001 for heterogeneity). However, when analyzing prognosis, allele G was a potential risk factor for poor tumor differentiation (AA vs

GA/GG

OR =2.60, 95% CI =1.15-5.86, P=0.836 for heterogeneity) and reduced disease-free intervals (OR =2.08, 95% CI =1.17-3.69, P=0.134 for heterogeneity). In the subgroup analysis, the cancer susceptibility of Asian groups, population-based control groups, nasopharyngeal cancer groups, and esophageal SCC groups were more likely to be affected by the CCND1 G870A polymorphism. No significant publication bias was found in our analysis (P=0.961 for Egger's test and P=0.245 for Begg's test).

CONCLUSION

The results of the present meta-analysis suggest that the variant CCND1 870A allele might confer an elevated risk of SCC of the UADT, particularly among Asians and individuals who have esophageal or nasopharyngeal cancers. Moreover, the CCND1 870A allele might also confer better tumor differentiation grades and longer disease-free intervals.

Molecular biology of testicular germ cell tumors

Testicular germ cell tumors (TGCTs) are the most common solid tumors in young adult men. They constitute a unique pathology because of their embryonic and germ origin and their special behavior. Genetic predisposition, environmental factors involved in their development and genetic aberrations have been under study in many works throughout the last years trying to explain the susceptibility and the transformation mechanism of TGCTs. Despite the high rate of cure in this type of tumors because its particular sensitivity to cisplatin, there are tumors resistant to chemotherapy for which it is needed to find new therapies. In the present work, it has been carried out a literature review on the most important molecular aspects involved in the onset and development of such tumors, as well as a review of the major developments regarding prognostic factors, new prognostic biomarkers and the possibility of new targeted therapies.

High frequency of the SDK1:AMACR fusion transcript in Chinese prostate cancer

Chromosomal rearrangements and fusion genes play important roles in tumor development and progression. Four high-frequency prostate cancer (CaP) specific fusion genes, SDK1:AMACR, RAD50:PDLIM4, CTAGE5:KHDRBS3 and USP9Y:TTTY15 have been reported in Chinese CaP samples through a transcriptome sequencing study. We previously reported that USP9Y:TTTY15 is a transcription-mediated chimeric RNA, which is expressed in both tumor and non-malignant samples, and here we attempted to confirm the existence of the other three fusion genes SDK1:AMACR, RAD50:PDLIM and CTAGE5:KHDRBS3. We detected SDK1:AMACR fusion transcript in 23 of 100 Chinese CaP samples, but did not detect RAD50:PDLIM4 and CTAGE5:KHDRBS3 transcripts in any of those samples. SDK1:AMACR fusion transcript is Chinese CaP specific, which was neither detected in non-malignant prostate tissues adjacent to cancer from Chinese patient nor in CaP samples from UK patients. However, we did not detect genomic rearrangement of SDK1 gene by fluorescence in situ hybridization analysis, indicating that SDK1:AMACR is also a transcription-mediated chimeric RNA. Quantitative analysis demonstrated that high level AMACR expression was associated with SDK1:AMACR fusion status (P=0.004), suggesting that SDK1:AMACR fusion transcript may promote prostate carcinogenesis through increasing AMACR expression. However, the fusion status was not significantly correlated with any poor disease progression clinical features. The identification of the SDK1:AMACR fusion transcript in CaP cases from China but not from UK further supports our previous observation that different genetic alterations contribute to CaP in China and Western countries, although many genetic changes are also shared. Further studies are required to establish if CaPs with SDK1:AMACR represent a distinct subtype.

Semi-comprehensive analysis of gene amplification in gastric cancers using multiplex ligation-dependent probe amplification and fluorescence in situ hybridization

The prognosis of patients with gastric carcinomas at an advanced stage still remains dismal, and therefore novel therapeutic modalities are urgently needed. Since the successful targeting of amplified ERBB2 with a humanized monoclonal antibody, the amplified genes of other receptor tyrosine kinases such as EGFR, FGFR2, and MET, as well as those of other cell regulator genes, are being considered as candidate targets of molecular therapy. The aim of the present study was to determine the amplification status of 26 genes, which are frequently amplified in solid cancers, in advanced gastric cancers. A total of 93 formalin-fixed and paraffin-embedded advanced gastric cancer tissues were examined by multiple ligation-dependent probe amplification, and 32 cases with 'gain' or 'amplified' status of 16 genes were further examined for the respective gene amplification by fluorescence in situ hybridization (FISH) and for the respective protein overexpression by immunohistochemistry. The frequencies of gene amplifications in advanced gastric cancers were as follows: ERBB2 (13 cases, 14%), FGFR2 (7 cases, 8%), MYC (7 cases, 8%), TOP2A (7 cases, 8%), MET (4 cases, 4%), MDM2 (4 cases, 4%), CCND1 (3 cases, 3%), FGF10 (2 cases, 3%), and EGFR (1 case, 1%). Amplification of the receptor tyrosine kinases genes occurred in a mutually exclusive manner except for one tumor in which ERBB2 and FGFR2 were both amplified but in different cancer cells. Co-amplification of ERBB2 and MYC, and EGFR and CCND1, in single nuclei but on different amplicons, was confirmed in one case each. Attempts at correlating the FISH status with the immunohistochemical staining pattern showed variable results from complete concordance to no correlation. In conclusion, combination of multiple ligation-dependent probe amplification and FISH analysis is a feasible approach for obtaining the semi-comprehensive genetic information that is necessary for personalized molecular targeted therapy.