Identification of HERC5 and its potential role in NSCLC progression: HERC5 in Micrometastatic Lung Cancer

HERC5 downregulation in non-small cell lung cancer is associated with altered energy metabolism and metastasis

BACKGROUND

Metastasis is the leading cause of cancer-related death in non-small cell lung cancer (NSCLC) patients. We previously showed that low HERC5 expression predicts early tumor dissemination and a dismal prognosis in NSCLC patients. Here, we performed functional studies to unravel the mechanism underlying the "metastasis-suppressor" effect of HERC5, with a focus on mitochondrial metabolism pathways.

METHODS

We assessed cell proliferation, colony formation potential, anchorage-independent growth, migration, and wound healing in NSCLC cell line models with HERC5 overexpression (OE) or knockout (KO). To study early tumor cell dissemination, we used these cell line models in zebrafish experiments and performed intracardial injections in nude mice. Mass spectrometry (MS) was used to analyze protein changes in whole-cell extracts. Furthermore, electron microscopy (EM) imaging, cellular respiration, glycolytic activity, and lactate production were used to investigate the relationships with mitochondrial energy metabolism pathways.

RESULTS

Using different in vitro NSCLC cell line models, we showed that NSCLC cells with low HERC5 expression had increased malignant and invasive properties. Furthermore, two different in vivo models in zebrafish and a xenograft mouse model showed increased dissemination and metastasis formation (in particular in the brain). Functional enrichment clustering of MS data revealed an increase in mitochondrial proteins in vitro when HERC5 levels were high. Loss of HERC5 leads to an increased Warburg effect, leading to improved adaptation and survival under prolonged inhibition of oxidative phosphorylation.

CONCLUSIONS

Taken together, these results indicate that low HERC5 expression increases the metastatic potential of NSCLC in vitro and in vivo. Furthermore, HERC5-induced proteomic changes influence mitochondrial pathways, ultimately leading to alterations in energy metabolism and demonstrating its role as a new potential metastasis suppressor gene.

Harnessing neutrophil plasticity for HCC immunotherapy

Neutrophils, until recently, have typically been considered a homogeneous population of terminally differentiated cells with highly conserved functions in homeostasis and disease. In hepatocellular carcinoma (HCC), tumour-associated neutrophils (TANs) are predominantly thought to play a pro-tumour role, promoting all aspects of HCC development and progression. Recent developments in single-cell technologies are now providing a greater insight and appreciation for the level of cellular heterogeneity displayed by TANs in the HCC tumour microenvironment, which we have been able to correlate with other TAN signatures in datasets for gastric cancer, pancreatic ductal adenocarcinoma (PDAC) and non-small cell lung cancer (NSCLC). TANs with classical pro-tumour signatures have been identified as well as neutrophils primed for anti-tumour functions that, if activated and expanded, could become a potential therapeutic approach. In recent years, therapeutic targeting of neutrophils in HCC has been typically focused on impairing the recruitment of pro-tumour neutrophils. This has now been coupled with immune checkpoint blockade with the aim to stimulate lymphocyte-mediated anti-tumour immunity whilst impairing neutrophil-mediated immunosuppression. As a result, neutrophil-directed therapies are now entering clinical trials for HCC. Pharmacological targeting along with ex vivo reprogramming of neutrophils in HCC patients is, however, in its infancy and a greater understanding of neutrophil heterogeneity, with a view to exploit it, may pave the way for improved immunotherapy outcomes. This review will cover the recent developments in our understanding of neutrophil heterogeneity in HCC and how neutrophils can be harnessed to improve HCC immunotherapy.

Prospects and feasibility of synergistic therapy with radiotherapy, immunotherapy, and DNA methyltransferase inhibitors in non-small cell lung cancer

The morbidity and mortality of lung cancer are increasing, seriously threatening human health and life. Non-small cell lung cancer (NSCLC) has an insidious onset and is not easy to be diagnosed in its early stage. Distant metastasis often occurs and the prognosis is poor. Radiotherapy (RT) combined with immunotherapy, especially with immune checkpoint inhibitors (ICIs), has become the focus of research in NSCLC. The efficacy of immunoradiotherapy (iRT) is promising, but further optimization is necessary. DNA methylation has been involved in immune escape and radioresistance, and becomes a game changer in iRT. In this review, we focused on the regulation of DNA methylation on ICIs treatment resistance and radioresistance in NSCLC and elucidated the potential synergistic effects of DNA methyltransferases inhibitors (DNMTis) with iRT. Taken together, we outlined evidence suggesting that a combination of DNMTis, RT, and immunotherapy could be a promising treatment strategy to improve NSCLC outcomes.

Predictive and Prognostic Biomarkers for Lung Cancer Bone Metastasis and Their Therapeutic Value

Lung cancer is the leading cause of cancer-related death worldwide. Bone metastasis, which usually accompanies severe skeletal-related events, is the most common site for tumor distant dissemination and detected in more than one-third of patients with advanced lung cancer. Biopsy and imaging play critical roles in the diagnosis of bone metastasis; however, these approaches are characterized by evident limitations. Recently, studies regarding potential biomarkers in the serum, urine, and tumor tissue, were performed to predict the bone metastases and prognosis in patients with lung cancer. In this review, we summarize the findings of recent clinical research studies on biomarkers detected in samples obtained from patients with lung cancer bone metastasis. These markers include the following: (1) bone resorption-associated markers, such as N-terminal telopeptide (NTx)/C-terminal telopeptide (CTx), C-terminal telopeptide of type I collagen (CTx-I), tartrate-resistant acid phosphatase isoform 5b (TRACP-5b), pyridinoline (PYD), and parathyroid hormone related peptide (PTHrP); (2) bone formation-associated markers, including total serum alkaline phosphatase (ALP)/bone specific alkaline phosphatase(BAP), osteopontin (OP), osteocalcin (OS), amino-terminal extension propeptide of type I procollagen/carboxy-terminal extension propeptide of type I procollagen (PICP/PINP); (3) signaling markers, including epidermal growth factor receptor/Kirsten rat sarcoma/anaplastic lymphoma kinase (EGFR/KRAS/ALK), receptor activator of nuclear factor κB ligand/receptor activator of nuclear factor κB/osteoprotegerin (RANKL/RANK/OPG), C-X-C motif chemokine ligand 12/C-X-C motif chemokine receptor 4 (CXCL12/CXCR4), complement component 5a receptor (C5AR); and (4) other potential markers, such as calcium sensing receptor (CASR), bone sialoprotein (BSP), bone morphogenetic protein 2 (BMP2), cytokeratin 19 fragment/carcinoembryonic antigen (CYFRA/CEA), tissue factor, cell-free DNA, long non-coding RNA, and microRNA. The prognostic value of these markers is also investigated. Furthermore, we listed some clinical trials targeting hotspot biomarkers in advanced lung cancer referring for their therapeutic effects.

DNA methylation in lung cancer patients: Opening a "window of life" under precision medicine

DNA methylation is a work of adding a methyl group to the 5th carbon atom of cytosine in DNA sequence under the catalysis of DNA methyltransferase (DNMT) to produce 5-methyl cytosine. Some current studies have elucidated the mechanism of lung cancer occurrence and causes of lung cancer progression and metastasis from the perspective of DNA methylation. Moreover, many studies have shown that smoking can change the methylation status of some gene loci, leading to the occurrence of lung cancer, especially central lung cancer. This review mainly introduces the role of DNA methylation in the pathogenesis, early diagnosis and screening, progression and metastasis, treatment, and prognosis of lung cancer, as well as the latest progress. We point out that methylation markers, sample tests, and methylation detection limit the clinical application of DNA methylation. If the liquid biopsy is to become the main force in lung cancer diagnosis, it must make efficient use of limited samples and improve the sensitivity and specificity of the tests. In addition, we also put forward our views on the future development direction of DNA methylation.

Disease-related blood-based differential methylation in cystic fibrosis and its representation in lung cancer revealed a regulatory locus in PKP3 in lung epithelial cells

Cystic fibrosis (CF) is a monogenic disease, characterized by massive chronic lung inflammation. The observed variability in clinical phenotypes in monozygotic CF twins is likely associated with the extent of inflammation. This study sought to investigate inflammation-related aberrant DNA methylation in CF twins and to determine to what extent acquired methylation changes may be associated with lung cancer.

Blood-based genome-wide DNA methylation analysis was performed to compare the DNA methylomes of monozygotic twins, from the European CF Twin and Sibling Study with various degrees of disease severity. Putatively inflammation-related and differentially methylated positions were selected from a large lung cancer case-control study and investigated in blood by targeted bisulphite next-generation-sequencing. An inflammation-related locus located in the Plakophilin-3 (PKP3) gene was functionally analysed regarding promoter and enhancer activity in presence and absence of methylation using luciferase reporter assays.

We confirmed in a unique cohort that monozygotic twins, even if clinically discordant, have only minor differences in global DNA methylation patterns and blood cell composition. Further, we determined the most differentially methylated positions, a high proportion of which are blood cell-type-specific, whereas others may be acquired and thus have potential relevance in the context of inflammation as lung cancer risk factors. We identified a sequence in the gene body of PKP3 which is hypermethylated in blood from CF twins with severe phenotype and highly variably methylated in lung cancer patients and controls, independent of known clinical parameters, and showed that this region exhibits methylation-dependent promoter activity in lung epithelial cells.

Downregulation of HERC5 E3 ligase attenuates the ubiquitination of CtBP1 to inhibit apoptosis in colorectal cancer cells

The Homologous to E6AP C-terminus (HECT) domain and RCC1-like domain-containing (HERC) proteins can function as tumour suppressors and as oncogenes, depending on the cancer type. However, the expression patterns of HERCs in colorectal cancer (CRC) cells are unclear. Here, we show that only HERC1 and HERC5 are downregulated in CRC tumours, and we focus our study on revealing HERC5-mediating signalling because the change in downregulation is much more obvious for HERC5 than for HERC1. We demonstrate that HERC5 recruits an adaptor protein, CREB binding protein (CRB), to ubiquitinate C-terminal binding protein 1 (CtBP1) in noncancerous colon cells. The downregulation of HERC5 in CRC cells attenuates the ubiquitination of CtBP1, which then accumulates and assembles into a transcriptional complex with histone deacetylase 1 (HDAC1) and a transcription factor c-MYC. This transcriptional complex binds to the promoters of three proapoptotic genes, Bcl2 associated X (BAX), Bcl2 interacting killer (BIK) and p53upregulated modulator of apoptosis (PUMA), and inhibits their expression, thereby suppressing apoptotic signalling and promoting tumourigenesis. Overexpression of HERC5, downregulation of CtBP1 or blocking of the CtBP1 function with its inhibitors (NSC95397 and 4-methylthio-2-oxobutyric acid [MTOB]) significantly prevents CRC cell proliferation in vitro and tumour growth in vivo. Combining NSC95397 (or MTOB) with chemotherapeutic drugs (oxaliplatin or capecitabine) gives a much stronger inhibition of cell proliferation and tumour growth compared to their single treatments. Collectively, our results reveal that downregulation of HERC5 E3 ligase attenuates the ubiquitination of CtBP1 to inhibit apoptosis. Therefore, CtBP1 may be a promising target in CRC chemotherapy.

Claudin-6 is down-regulated in gastric cancer and its potential pathway

Claudins are indispensible in modulating the permeability of epithelial and endothelial cells and in the maintenance of cell polarity. In order to verify the function of claudin-6 in the development of gastric cancer, we investigated claudin-6 expression in different gastric disease tissues. Moreover, we further explored whether overexpression of claudin-6 altered proliferation, apoptosis, migration, invasiveness, differentiation in BGC-823 cells and the potential mechanism. Immunohistochemistry was performed to detect the in situ expression of claudin-6 in different gastric disease tissues; moreover, cell culture, real-time PCR and western blot were used to evaluate the effect of overexpression of claudin-6 in vitro and the related mechanism. The results of immunohistochemical staining showed that the positivity of claudin-6 was significantly higher in superficial gastritis than that in gastric cancer. Overexpression of claudin-6 induced differentiation of BGC-823 cells by inhibiting the JNK pathway. However, it had no effect on proliferation, apoptosis, migration or invasiveness in vitro. The expression of claudin-6 was decreased in gastric cancer. Overexpression of claudin-6 induced differentiation of gastric cancer cells by inhibiting the JNK pathway.

Brain Metastasis Cell Lines Panel: A Public Resource of Organotropic Cell Lines

Spread of cancer to the brain remains an unmet clinical need in spite of the increasing number of cases among patients with lung, breast cancer, and melanoma most notably. Although research on brain metastasis was considered a minor aspect in the past due to its untreatable nature and invariable lethality, nowadays, limited but encouraging examples have questioned this statement, making it more attractive for basic and clinical researchers. Evidences of its own biological identity (i.e., specific microenvironment) and particular therapeutic requirements (i.e., presence of blood-brain barrier, blood-tumor barrier, molecular differences with the primary tumor) are thought to be critical aspects that must be functionally exploited using preclinical models. We present the coordinated effort of 19 laboratories to compile comprehensive information related to brain metastasis experimental models. Each laboratory has provided details on the cancer cell lines they have generated or characterized as being capable of forming metastatic colonies in the brain, as well as principle methodologies of brain metastasis research. The Brain Metastasis Cell Lines Panel (BrMPanel) represents the first of its class and includes information about the cell line, how tropism to the brain was established, and the behavior of each model in vivo. These and other aspects described are intended to assist investigators in choosing the most suitable cell line for research on brain metastasis. The main goal of this effort is to facilitate research on this unmet clinical need, to improve models through a collaborative environment, and to promote the exchange of information on these valuable resources.

HERC Ubiquitin Ligases in Cancer

HERC proteins are ubiquitin E3 ligases of the HECT family. The HERC subfamily is composed of six members classified by size into large (HERC1 and HERC2) and small (HERC3-HERC6). HERC family ubiquitin ligases regulate important cellular processes, such as neurodevelopment, DNA damage response, cell proliferation, cell migration, and immune responses. Accumulating evidence also shows that this family plays critical roles in cancer. In this review, we provide an integrated view of the role of these ligases in cancer, highlighting their bivalent functions as either oncogenes or tumor suppressors, depending on the tumor type. We include a discussion of both the molecular mechanisms involved and the potential therapeutic strategies.

Alternative splicing of LSD1+8a in neuroendocrine prostate cancer is mediated by SRRM4

Neuroendocrine prostate cancer (NEPC) is the most virulent form of prostate cancer. Importantly, our recent work examining metastatic biopsy samples demonstrates NEPC is increasing in frequency. In contrast to prostate adenocarcinomas that express a luminal gene expression program, NEPC tumors express a neuronal gene expression program. Despite this distinction, the diagnosis of NEPC is often challenging, demonstrating an urgent need to identify new biomarkers and therapeutic targets. Our prior work demonstrated that the histone demethylase LSD1 (KDM1A) is important for survival of prostate adenocarcinomas, but little was known about LSD1's role in NEPC. Recently, a neural-specific transcript variant of LSD1-LSD1+8a-was discovered and demonstrated to activate neuronal gene expression in neural cells. The splicing factor SRRM4 was previously shown to promote LSD1+8a splicing in neuronal cells, and SRRM4 promotes NEPC differentiation and cell survival. Therefore, we sought to determine if LSD1+8a might play a role in NEPC and whether LSD1+8a splicing was linked to SRRM4. To investigate a potential role for LSD1+8a in NEPC, we examined a panel of prostate adenocarcinoma and NEPC patient-derived xenografts and metastatic biopsies. LSD1+8a was expressed exclusively in NEPC samples and correlated significantly with elevated expression of SRRM4. Using SRRM4-overexpressing cell lines, we determined that SRRM4 mediates alternative splicing of LSD1+8a. Finally, using gain of function studies, we confirmed that LSD1+8a and SRRM4 co-regulate target genes distinct from canonical LSD1. Our findings suggest further study of the interplay between SRRM4 and LSD1+8a and mechanisms by which LSD1+8a regulates gene expression in NEPC is warranted.

Drug resistance in topoisomerase-targeting therapy

Drug resistance is a well-known phenomenon that occurs when initially responsive to chemotherapy cancer cells become tolerant and elude further effectiveness of anticancer drugs. Based on their mechanism of action, anticancer drugs can be divided into cytotoxic-based agents and target-based agents. An important role among the therapeutics of the second group is played by drugs targeting topoisomerases, nuclear enzymes critical to DNA function and cell survival. These enzymes are cellular targets of several groups of anticancer agents which generate DNA damage in rapidly proliferating cancer cells. Drugs targeting topoisomerase I are mostly analogs of camtothecin, a natural compound isolated from the bark of a tree growing in China. Drugs targeting topoisomerase II are divided into poisons, such as anthracycline antibiotics, whose action is based on intercalation between DNA bases, and catalytic inhibitors that block topoisomerase II at different stages of the catalytic cycle. Unfortunately, chemotherapy is often limited by the induction of drug resistance. Identifying mechanisms that promote drug resistance is critical for the improvement of patient prognosis. Cancer drug resistance is a complex phenomenon that may be influenced by many factors. Here we discuss various mechanisms by which cancer cells can develop resistance to topoisomerase-directed drugs, which include enhanced drug efflux, mutations in topoisomerase genes, hypophosphorylation of topoisomerase II catalytic domain, activation of NF-κB transcription factor and drug inactivation. All these events may lead to the ineffective induction of cancer cell death. Attempts at circumventing drug resistance through the inhibition of cellular efflux pumps, use of silencing RNAs or inhibition of some important mechanisms, which can allow cancer cells to survive therapy, are also presented.

Efficacy and adverse events of five targeted agents in the treatment of advanced or metastatic non-small-cell lung cancer: A network meta-analysis of nine eligible randomized controlled trials involving 5,059 patients

Recently, targeted agents were reported to improve overall survival, progression-free survival (PFS), response rate, and quality of life compared with cytotoxic chemotherapies, which provides hope for the treatment of non-small-cell lung cancer (NSCLC). The network meta-analysis is applied to compare the efficacies and adverse events of five targeted agents (erlotinib, gefitinib, vandetanib, dacomitinib, and icotinib) for advanced or metastatic NSCLC. Nine eligible randomized controlled trials from PubMed and Cochrane Library database were included. Weighted mean difference, odds ratio, and surface under the cumulative ranking curve (SUCRA) values were evaluated for the efficacy and adverse events of the five targeted agents in the treatment of NSCLC. With regard to efficacy, the overall response rate (ORR) of advanced or metastatic NSCLC patients treated with gefitinib was relatively higher than those treated with placebo. Compared with patients treated with placebo, the disease control rate (DCR) of patients treated with erlotinib and with gefitinib was relatively higher. Furthermore, in terms of PFS and DCR, the SUCRA value of icotinib was the highest among the five targeted drugs. With regard to ORR, the SUCRA value of gefitinib was the highest among the five targeted drugs. In terms of fatigue, rash, and cough, erlotinib had the lowest SUCRA value, whereas vandetanib exhibited the lowest SUCRA value in terms of diarrhea. Our study suggests that the efficacies of gefitinib and icotinib for advanced or metastatic NSCLC were comparatively better, whereas the toxicities of erlotinib and vandetanib were relatively greater.

Mycoplasma hyorhinis reduces sensitivity of human lung carcinoma cells to Nutlin-3 and promotes their malignant phenotype

PURPOSE

MDM2 inhibitors are promising anticancer agents that induce cell cycle arrest and tumor cells death via p53 reactivation. We examined the influence of Mycoplasma hyorhinis infection on sensitivity of human lung carcinoma cells NCI-H292 to MDM2 inhibitor Nutlin-3. In order to unveil possible mechanisms underlying the revealed effect, we investigated gene expression changes and signal transduction networks activated in NCI-H292 cells in response to mycoplasma infection.

METHODS

Sensitivity of NCI-Н292 cells to Nutlin-3 was estimated by resazurin-based cell viability assay. Genome-wide transcriptional profiles of NCI-H292 and NCI-Н292^Myc.h cell lines were determined using Illumina Human HT-12 v3 Expression BeadChip. Search for key transcription factors and key node molecules was performed using the geneXplain platform. Ability for anchorage-independent growth was tested by soft agar colony formation assay.

RESULTS

NCI-Н292^Myc.h cells were shown to be 1.5- and 5.2-fold more resistant to killing by Nutlin-3 at concentrations of 15 and 30 µM than uninfected NCI-Н292 cells (P < 0.05 and P < 0.001, respectively). Transcriptome analysis revealed differential expression of multiple genes involved in cancer progression and metastasis as well as epithelial-mesenchymal transition (EMT). Moreover, we have shown experimentally that NCI-Н292^Myc.h cells were more capable of growing and dividing without binding to a substrate. The most likely mechanism explaining the observed changes was found to be TLR4- and IL-1b-mediated activation of NF-κB pathway.

CONCLUSIONS

Our results provide evidence that mycoplasma infection is an important factor modulating the effect of MDM2 inhibitors on cancer cells and is able to induce EMT-related changes.

The Evolving Landscape of Brain Metastasis

Metastasis, involving the spread of systemic cancer to the brain, results in neurologic disability and death. Current treatments are largely palliative in nature; improved therapeutic approaches represent an unmet clinical need. However, recent experimental and clinical advances challenge the bleak long-term outcome of this disease. Encompassing key recent findings in epidemiology, genetics, microenvironment, leptomeningeal disease, neurocognition, targeted therapy, immunotherapy, and prophylaxis, we review preclinical and clinical studies to provide a comprehensive picture of contemporary research and the management of secondary brain tumors.

Reactive Astrocytes in Brain Metastasis

Brain metastasis, the secondary growth of malignant cells within the central nervous system (CNS), exceeds the incidence of primary brain tumors (i.e., gliomas) by tenfold and are seemingly on the rise owing to the emergence of novel targeted therapies that are more effective in controlling extracranial disease relatively to intracranial lesions. Despite the fact that metastasis to the brain poses a unmet clinical problem, with afflicted patients carrying significant morbidity and a fatal prognosis, our knowledge as to how metastatic cells manage to adapt to the tissue environment of the CNS remains limited. Answering this question could pave the way for novel and more specific therapeutic modalities in brain metastasis by targeting the specific makeup of the brain metastatic niche. In regard to this, astrocytes have emerged as the major host cell type that cancer cells encounter and interact with during brain metastasis formation. Similarly to other CNS disorders, astrocytes become reactive and respond to the presence of cancer cells by changing their phenotype and significantly influencing the outcome of disseminated cancer cells within the CNS. Here, we summarize the current knowledge on the contribution of reactive astrocytes in brain metastasis by focusing on the signaling pathways and types of interactions that play a crucial part in the communication with cancer cells and how these could be translated into innovative therapies.

The genomic and epigenomic landscape in thymic carcinoma

Thymic carcinoma (TC) is a rare cancer whose genomic features have been examined in only a limited number of patients of European descent. Here, we characterized both genomic and epigenomic aberrations by whole exome sequencing, RNA sequencing, methylation array and copy number analyses in TCs from Asian patients and compared them with those in TCs from USA/European patients. Samples analyzed were 10 pairs of snap-frozen surgical specimens of cancerous and non-cancerous thymic tissue. All 10 cases were Japanese patients treated at the National Cancer Center Hospital, Japan, between 1994 and 2010. Mutational signature analysis indicated that the accumulation of age-related mutations drive TC development. We identified recurrent somatic mutations in TET2, CYLD, SETD2, TP53, FBXW7, HRAS and RB1, and no mutations in GTF2I, supporting the hypothesis that TC and thymoma are distinguishable by their genetic profiles. TCs with TET2 mutations had more hypermethylated genes than those without, and hyper-methylation was associated with downregulation of gene expression. Focal genome copy number gains, associated with elevated gene expression, were observed at the KIT (which is known to drive thymic carcinogenesis) and AHNAK2 gene loci. Taken together, the results suggest that the molecular processes leading to TC depend on the accumulation of genetic and epigenetic aberrations. In addition, epigenetic dysregulation as a result of the TET2 mutation was observed in a subset of TCs.

New and Old Genes Associated with Primary and Established Responses to Cisplatin and Topotecan Treatment in Ovarian Cancer Cell Lines

Low efficiency of chemotherapy in ovarian cancer results from the development of drug resistance. Cisplatin (CIS) and topotecan (TOP) are drugs used in chemotherapy of this cancer. We analyzed the development of CIS and TOP resistance in ovarian cancer cell lines. Incubation of drug sensitive cell lines (W1 and A2780) with cytostatic drugs was used to determine the primary response to CIS and TOP. Quantitative polymerase chain reaction (Q-PCR) was performed to measure the expression levels of the genes. We observed decreased expression of the MCTP1 gene in all resistant cell lines. We observed overexpression of the S100A3 and HERC5 genes in TOP-resistant cell lines. Increased expression of the S100A3 gene was also observed in CIS-resistant A2780 sublines. Overexpression of the C4orf18 gene was observed in CIS- and TOP-resistant A2780 sublines. A short time of exposure to CIS led to increased expression of the ABCC2 gene in the W1 and A2780 cell lines and increased expression of the C4orf18 gene in the A2780 cell line. A short time of exposure to TOP led to increased expression of the S100A3 and HERC5 genes in both sensitive cell lines, increased expression of the C4orf18 gene in the A2780 cell line and downregulation of the MCTP1 gene in the W1 cell line. Our results suggest that changes in expression of the MCTP1, S100A3 and C4orf18 genes may be related to both CIS and TOP resistance. Increased expression of the HERC5 gene seems to be important only in TOP resistance.

Microarray-based detection and expression analysis of new genes associated with drug resistance in ovarian cancer cell lines

PURPOSE

The present study is to discover a new genes associated with drug resistance development in ovarian cancer.

METHODS

We used microarray analysis to determine alterations in the level of expression of genes in cisplatin- (CisPt), doxorubicin- (Dox), topotecan- (Top), and paclitaxel- (Pac) resistant variants of W1 and A2780 ovarian cancer cell lines. Immunohistochemistry assay was used to determine protein expression in ovarian cancer patients.

RESULTS

We observed alterations in the expression of 22 genes that were common to all three cell lines that were resistant to the same cytostatic drug. The level of expression of 13 genes was upregulated and that of nine genes was downregulated. In the CisPt-resistant cell line, we observed downregulated expression of ABCC6, BST2, ERAP2 and MCTP1; in the Pac-resistant cell line, we observe upregulated expression of ABCB1, EPHA7 and RUNDC3B and downregulated expression of LIPG, MCTP1, NSBP1, PCDH9, PTPRK and SEMA3A. The expression levels of three genes, ABCB1, ABCB4 and IFI16, were upregulated in the Dox-resistant cell lines. In the Top-resistant cell lines, we observed increased expression levels of ABCG2, HERC5, IFIH1, MYOT, S100A3, SAMD4A, SPP1 and TGFBI and decreased expression levels of MCTP1 and PTPRK. The expression of EPHA7, IFI16, SPP1 and TGFBI was confirmed at protein level in analyzed ovarian cancer patients..

CONCLUSIONS

The expression profiles of the investigated cell lines indicated that new candidate genes are related to the development of resistance to the cytostatic drugs that are used in first- and second-line chemotherapy of ovarian cancer.

Functional and pathological relevance of HERC family proteins: a decade later

The HERC gene family encodes proteins with two characteristic domains in their sequence: the HECT domain and the RCC1-like domain (RLD). In humans, the HERC family comprises six members that can be divided into two groups based on their molecular mass and domain structure. Whereas large HERCs (HERC1 and HERC2) contain one HECT and more than one RLD, small HERCs (HERC3-6) possess single HECT and RLD domains. Accumulating evidence shows the HERC family proteins to be key components of a wide range of cellular functions, including neurodevelopment, DNA damage repair, cell growth and immune response. Considering the significant recent advances made regarding HERC functionality, an updated review summarizing the progress is greatly needed at 10 years since the last HERC review. We provide an integrated view of HERC function and go into detail about its implications for several human diseases such as cancer and neurological disorders.

HERC5 is a prognostic biomarker for post-liver transplant recurrent human hepatocellular carcinoma

BACKGROUND AND AIMS

Orthotopic liver transplantation (OLT) can be an effective treatment option for certain patients with early stage hepatocellular carcinoma (HCC) meeting Milan, UCSF, or Hangzhou criteria. However, HCC recurrence rates post-OLT range from 20 to 40 %, with limited follow-up options. Elucidating genetic drivers common to primary and post-OLT recurrent tumors may further our understanding and help identify predictive biomarkers of recurrence-both to ultimately help manage clinical decisions for patients undergoing OLT.

METHODS

Whole exome and RNA sequencing in matched primary and recurrent tumors, normal adjacent tissues, and blood from four Chinese HCC patients was conducted. SiRNA knockdown and both qRT-PCR and Western assays were performed on PLCPRF5, SNU449 and HEPG2 cell lines; immunohistochemistry and RNA Sequencing were conducted on the primary tumors of Chinese HCC patients who experienced tumor recurrence post-OLT (n = 9) or did not experience tumor recurrence (n = 12).

RESULTS

In three independent HCC studies of patients undergoing transplantation (n = 21) or surgical resection (n = 242, n = 44) of primary tumors (total n = 307), HERC5 mRNA under-expression correlated with shorter: time to tumor recurrence (p = 0.007 and 0.02) and overall survival (p = 0.0063 and 0.023), even after adjustment for relevant clinical variables. HERC5 loss drives CCL20 mRNA and protein over-expression and associates with regulatory T cell infiltration as measured by FOXP3 expression. Further, matched primary and recurrent tumors from the 4 HCC patients indicated clonal selection advantage of Wnt signaling activation and CDKN2A inactivation.

CONCLUSIONS

HERC5 plays a crucial role in HCC immune evasion and has clinical relevance as a reproducible prognostic marker for risk of tumor recurrence and survival in patients.