Integrative network analysis reveals USP7 haploinsufficiency inhibits E-protein activity in pediatric T-lineage acute lymphoblastic leukemia (T-ALL).

USP7, which encodes a deubiquitylating enzyme, is among the most frequently mutated genes in pediatric T-ALL, with somatic heterozygous loss-of-function mutations (haploinsufficiency) predominantly affecting the subgroup that has aberrant TAL1 oncogene activation. Network analysis of > 200 T-ALL transcriptomes linked USP7 haploinsufficiency with decreased activities of E-proteins. E-proteins are also negatively regulated by TAL1, leading to concerted down-regulation of E-protein target genes involved in T-cell development. In T-ALL cell lines, we showed the physical interaction of USP7 with E-proteins and TAL1 by mass spectrometry and ChIP-seq. Haploinsufficient but not complete CRISPR knock-out of USP7 showed accelerated cell growth and validated transcriptional down-regulation of E-protein targets. Our study unveiled the synergistic effect of USP7 haploinsufficiency with aberrant TAL1 activation on T-ALL, implicating USP7 as a haploinsufficient tumor suppressor in T-ALL. Our findings caution against a universal oncogene designation for USP7 while emphasizing the dosage-dependent consequences of USP7 inhibitors currently under development as potential cancer therapeutics.

Dysregulated Kras/YY1/ZNF322A/Shh transcriptional axis enhances neo-angiogenesis to promote lung cancer progression.

Angiogenesis enhances cancer metastasis and progression, however, the roles of transcription regulation in angiogenesis are not fully defined. ZNF322A is an oncogenic zinc-finger transcription factor. Here, we demonstrate a new mechanism of Kras mutation-driven ZNF322A transcriptional activation and elucidate the interplay between ZNF322A and its upstream transcriptional regulators and downstream transcriptional targets in promoting neo-angiogenesis. Methods: Luciferase activity, RT-qPCR and ChIP-qPCR assays were used to examine transcription regulation in cell models. In vitro and in vivo angiogenesis assays were conducted. Immunohistochemistry, Kaplan-Meier method and multivariate Cox regression assays were performed to examine the clinical correlation in tumor specimens from lung cancer patients. Results: We validated that Yin Yang 1 (YY1) upregulated ZNF322A expression through targeting its promoter in the context of Kras mutation. Reconstitution experiments by knocking down YY1 under KrasG13V activation decreased KrasG13V-promoted cancer cell migration, proliferation and ZNF322A promoter activity. Knockdown of YY1 or ZNF322A attenuated angiogenesis in vitro and in vivo. Notably, we validated that ZNF322A upregulated the expression of sonic hedgehog (Shh) gene which encodes a secreted factor that activates pro-angiogenic responses in endothelial cells. Clinically, ZNF322A protein expression positively correlated with Shh and CD31, an endothelial cell marker, in 133 lung cancer patient samples determined using immunohistochemistry analysis. Notably, patients with concordantly high expression of ZNF322A, Shh and CD31 correlated with poor prognosis. Conclusions: These findings highlight the mechanism by which dysregulation of Kras/YY1/ZNF322/Shh transcriptional axis enhances neo-angiogenesis and cancer progression in lung cancer. Therapeutic strategies that target Kras/YY1/ZNF322A/Shh signaling axis may provide new insight on targeted therapy for lung cancer patients.

Cinobufagin Triggers Defects in Spindle Formation and Cap-Dependent Translation in Liver Cancer Cells by Inhibiting the AURKA-mTOR-eIF4E Axis.

Cinobufagin is a Na+/K+-ATPase (NKA) inhibitor with excellent anticancer effects to prolong the survival of patients. The purpose of the present study was to clarify the underlying mechanism of the anticancer effects of cinobufagin using overexpression or inhibition of aurora kinase A (AURKA) signaling. First, high expression of Na+/K+-ATPase alpha 1 subunit (ATP1A1) and AURAK resulted in increased malignant transformation in hepatocellular carcinoma (HCC) patients using the cancer genome atlas (TCGA) data and tissue samples. After treatment with cinobufagin, we successfully screened 202, 249, and 335 changing expression proteins in Huh-7 cells under normal, overexpression, and inhibition of AURKA using tandem mass tags (TMT)-labeled quantitative proteomics coupled to 2D liquid chromatography-tandem mass spectrometry (LC-MS/MS). Bioinformatics analysis revealed that these molecules were closely associated with chromosome segregation, DNA damage, and regulation of translation processes. We further confirmed that cinobufagin induced DNA damage and chromosome segregation disorders and suppresses translational processing in oncogenes by decreasing the expression of AURKA, mechanistic target of rapamycin kinase (mTOR), p-mTOR, p-extracellular regulated protein kinases (ERK), eukaryotic translation initiation factor 4E (eIF4E), and p-eIF4E, while increasing the expression of p-eukaryotic translation initiation factor 4E binding protein 1 (4E-BP1) (S65, T37, T46, T45) and increasing the interaction between eIF4 and 4E-BP1. Our results suggested that cinobufagin performed an antitumor effects in liver cancer cells by inhibiting the AURKA-mTOR-eIF4E axis.

DriverDBv3: a multi-omics database for cancer driver gene research.

An integrative multi-omics database is needed urgently, because focusing only on analysis of one-dimensional data falls far short of providing an understanding of cancer. Previously, we presented DriverDB, a cancer driver gene database that applies published bioinformatics algorithms to identify driver genes/mutations. The updated DriverDBv3 database (http://ngs.ym.edu.tw/driverdb) is designed to interpret cancer omics' sophisticated information with concise data visualization. To offer diverse insights into molecular dysregulation/dysfunction events, we incorporated computational tools to define CNV and methylation drivers. Further, four new features, CNV, Methylation, Survival, and miRNA, allow users to explore the relations from two perspectives in the 'Cancer' and 'Gene' sections. The 'Survival' panel offers not only significant survival genes, but gene pairs synergistic effects determine. A fresh function, 'Survival Analysis' in 'Customized-analysis,' allows users to investigate the co-occurring events in user-defined gene(s) by mutation status or by expression in a specific patient group. Moreover, we redesigned the web interface and provided interactive figures to interpret cancer omics' sophisticated information, and also constructed a Summary panel in the 'Cancer' and 'Gene' sections to visualize the features on multi-omics levels concisely. DriverDBv3 seeks to improve the study of integrative cancer omics data by identifying driver genes and contributes to cancer biology.

YY1-Activated Long Noncoding RNA SNHG5 Promotes Glioblastoma Cell Proliferation Through p38/MAPK Signaling Pathway.

Background: Glioma is considered one of the most prevalent and lethal brain tumors. Glioblastoma (GBM) is a main subtype of glioma. Long non-coding RNAs (lncRNAs) are identified as a new class of biomarkers and therapeutic targets for treatment of GBM. Objective: In the present study, we focused on exploring the function and potential mechanistic regulation of lncRNA small nucleolar RNA host gene 5 (SNHG5) in GBM. Methods: Gene expression was determined by qRT-PCR or western blot, as appropriate. CCK-8 and EdU assays, flow cytometry analysis and caspase 3 activity assay were conducted to evaluate several cellular processes in GBM cells. The relationship between YY1 and SNHG5 was assessed via ChIP and luciferase reporter assays. Results: SNHG5 was highly expressed in GBM. Loss- and gain-of-function assays revealed that SNHG5 promoted GBM cell proliferation and inhibited cell apoptosis in GBM. Mechanism experiments proved Yin Yang 1 (YY1) as transcriptional activator of SNHG5 in GBM. More importantly, we found that SNHG5 played the oncogenic role in GBM by activating p38/MAPK signaling pathway. Conclusion: YY1-induced SNHG5 promoted the cell proliferation in GBM via p38/MAPK signaling pathway. The findings expanded our understanding of SNHG5 as an oncogene in GBM.

A CATH domain functional family based approach to identify putative cancer driver genes and driver mutations.

Tumour sequencing identifies highly recurrent point mutations in cancer driver genes, but rare functional mutations are hard to distinguish from large numbers of passengers. We developed a novel computational platform applying a multi-modal approach to filter out passengers and more robustly identify putative driver genes. The primary filter identifies enrichment of cancer mutations in CATH functional families (CATH-FunFams) - structurally and functionally coherent sets of evolutionary related domains. Using structural representatives from CATH-FunFams, we subsequently seek enrichment of mutations in 3D and show that these mutation clusters have a very significant tendency to lie close to known functional sites or conserved sites predicted using CATH-FunFams. Our third filter identifies enrichment of putative driver genes in functionally coherent protein network modules confirmed by literature analysis to be cancer associated. Our approach is complementary to other domain enrichment approaches exploiting Pfam families, but benefits from more functionally coherent groupings of domains. Using a set of mutations from 22 cancers we detect 151 putative cancer drivers, of which 79 are not listed in cancer resources and include recently validated cancer associated genes EPHA7, DCC netrin-1 receptor and zinc-finger protein ZNF479.

Apoptotic Effects of Linum album Extracts on AGS Human Gastric Adenocarcinoma Cells and ZNF703 Oncogene Expression

Introduction: Linum album is a medicinal plant endemic in Iran that is very important pharmaceutically. The present study concerns the effect of different extracts of L. album on ZNF703 gene expression and apoptosis in human gastric carcinoma AGS cells. Method and material: Hydro alchoholic L. album extracts from various plant sources were produced by Maceration. AGS cells were treated with different concentrations (200, 400, 600, 800 and 1000 µg/ml) and the cytotoxicity potency was assessed after 24 h by MTT assay. Then, quantitative real time PCR was conducted for ZNF703 gene expression in AGS cells. Also, cell apoptosis/necrosis was assessed with the aid of Annexin V/PI staining and quantification by flow cytometry. Results: L. album extracts exerted dose-dependent toxicity in the AGS cell line. The mRNA levels of ZNF703 gene expression were significantly decreased with rhizome, fruit at fruiting, leaf and stem at anthesis (P<0.001), and leaf and stem at fruiting extracts as compared to the controls (P<0.01). Also, the number of apoptotic cells was increased from 2.70% (statistically significant; p<0.05) in untreated AGS cells to 44%, following treatment with the leaf and stem at anthesis example. Discussion: Our findings revealed that the L. album extracts can induce apoptosis and might modulate cytotoxicity by down regulating ZNF703 gene expression in AGS cells. Therefore, this extract could be a good candidate for inhibiting cancer cell growth, especially that of gastric cancer. In addition, ZNF703 may have potential as a therapeutic target.

Chemoprevention and Treatment of Pancreatic Cancer: Update and Review of the Literature.

BACKGROUND: Pancreatic ductal adenocarcinoma is one of the most lethal types of cancer with a 5-year survival rate of around 7%. Due to the relatively poor prognosis, the potential need of an effective chemoprevention is highly needed. SUMMARY: Different risk factors like smoking or hereditary tumour syndromes should be known for early detection of pancreatic intraepithelial neoplasia. Chemopreventive dietary agents include curcumin, capsaicin and flavonoid, whereas potential chemopreventive drugs compromise aspirin, metformin or statins. This review aims to give an overview on potential risk factors for the development of pancreatic cancer. Furthermore, we try to summarise known chemopreventive agents to support the fight against this lethal disease. Key Messages: On the one hand, there are natural agents that exhibit preventive properties and can lead to the prohibition of pancreatic cancer. On the other hand, there are drugs and agents that are currently used in other contexts and are thus already approved and studied in terms of their mechanisms of effects and the related secondary effects.

Onco-proteogenomics: Multi-omics level data integration for accurate phenotype prediction.

The overall goal of translational oncology is to identify molecular alterations indicative of cancer or of responsiveness to specific therapeutic regimens. While next-generation sequencing has played a pioneering role in this quest, the latest advances in proteomic technologies promise to provide a holistic approach to the further elucidation of tumor biology. Genetic information may be written in DNA and flow from DNA to RNA to protein, according to the central dogma of molecular biology, but the observed phenotype is dictated predominantly by the DNA protein coding region-derived proteotype. Proteomics holds the potential to bridge the gap between genotype and phenotype, because the powerful analytical tool of mass spectrometry has reached a point of maturity to serve this purpose effectively. This integration of "omics" data has given birth to the novel field of onco-proteogenomics, which has much to offer to precision medicine and personalized patient management. Here, we review briefly how each "omics" technology has individually contributed to cancer research, discuss technological and computational advances that have contributed to the realization of onco-proteogenomics, and summarize current and future translational applications.

Spica Prunellae extract suppresses the growth of human colon carcinoma cells by targeting multiple oncogenes via activating miR-34a.

Spica Prunellae is the spike of the herb Prunella vulgaris L. in traditional Chinese medicine which is often used for the treatment of various cancers including colorectal cancer. In the present study, we found that a key tumor suppressor, microRNA-34a (miR-34a) is involved in the antitumor activity for Spica Prunellae. Human colon carcinoma HCT-8 cells treated with an ethanol extract of Spica Prunellae (EESP) had significantly decreased cell proliferation and viability, in a dose-dependent manner. Flow cytometry analysis with Annexin V/PI staining analysis revealed that EESP treatment could induce apoptosis of HCT-8 cells. The level of miR-34a was upregulated in HCT-8 cells following EESP treatment, whereas expression levels of its target genes Notch1, Notch2 and Bcl-2 were downregulated. Inhibition of miR-34a rescued the expression of these target genes. These results revealed that Spica Prunellae can suppress the growth of HCT-8 cells by targeting Notch1, Notch2 and Bcl-2 via activation of miR-34a.

BDNF: An Oncogene or Tumor Suppressor?

Neurotrophins are a family of growth factors that are vital to the proper development of the central nervous system. Their effects on cells are governed by the expression and activation of the tyrosine kinase receptors TrkA, TrkB and TrkC. TrkB has been immensely implicated in mediating neuronal migration, development and differentiation. It has also been shown to protect several neuronal cell types from an array of cytotoxic stressors after activation by its conjugate ligand brain-derived neurotrophic factor (BDNF). Over the past two decades, it has been shown that TrkB and BDNF are up-regulated in many types of cancers, conferring aggressive phenotypes underpinned by their resistance to several standard chemotherapeutic agents. This resistance to chemotherapy is modulated by the downstream targets of the TrkB receptor which include the well-characterized PI3K /Akt growth pathway, a hallmark of uncontrolled cancer cell growth and proliferation. Pre-clinical efforts to develop inhibitors of this receptor are promising, and such inhibitors also seem to sensitize cancer cells to standard chemotherapies. However, new evidence suggests that BDNF overexpression in the hypothalamus has immunoaugmenting properties, eliciting an increased anti-tumor immune response and reducing the activity of several proteins that would normally confer resistance to chemotherapeutic agents. In the current work, we provide a global analysis of the physiological consequences of TrkB receptor activation in vitro and discuss the dynamic consequences of TrkB activation in vivo. Finally, we propose a clinically-feasible option for increasing BDNF expression in the hypothalamus to more readily utilize the oncolytic effects of BDNF.

Silencing of Agrobacterium tumefaciens oncogenes ipt and iaaM induces resistance to crown gall disease in plum but not in apricot.

BACKGROUND: In this study, two vectors with short-length chimeric transgenes were used to produce Prunus rootstocks resistant to crown gall disease through RNA-interference-mediated gene silencing of the Agrobacterium tumefaciens oncogenes ipt and iaaM. RESULTS: Transgenic plum and apricot lines were produced with efficiencies of up to 7.7 and 1.1% respectively. An in vitro evaluation method allowed identification of susceptible lines and reduction in the number of lines to be evaluated in the greenhouse. Five transgenic plum lines, expressing transgene-derived small interfering RNA (siRNA) and low levels of transgene hairpin RNA (hpRNA), showed a significant reduction in the development of the disease after infection with Agrobacterium strains C58 and A281 under greenhouse conditions. However, unexpectedly, all transgenic apricot lines were gall susceptible. The infection of apricot plants with a binary vector containing only the 6b oncogene demonstrated that the expression of this gene is involved in the induction of tumours in the apricot species. CONCLUSION: RNAi-mediated gene silencing can be used for inducing crown gall resistance in plum rootstocks. These could be used to graft non-genetically modified commercial fruit cultivars reducing, or eliminating, the disease symptoms. © 2017 Society of Chemical Industry.

Targeted Cancer Therapy: Vital Oncogenes and a New Molecular Genetic Paradigm for Cancer Initiation Progression and Treatment.

It has been declared repeatedly that cancer is a result of molecular genetic abnormalities. However, there has been no working model describing the specific functional consequences of the deranged genomic processes that result in the initiation and propagation of the cancer process during carcinogenesis. We no longer need to question whether or not cancer arises as a result of a molecular genetic defect within the cancer cell. The legitimate questions are: how and why? This article reviews the preeminent data on cancer molecular genetics and subsequently proposes that the sentinel event in cancer initiation is the aberrant production of fused transcription activators with new molecular properties within normal tissue stem cells. This results in the production of vital oncogenes with dysfunctional gene activation transcription properties, which leads to dysfunctional gene regulation, the aberrant activation of transduction pathways, chromosomal breakage, activation of driver oncogenes, reactivation of stem cell transduction pathways and the activation of genes that result in the hallmarks of cancer. Furthermore, a novel holistic molecular genetic model of cancer initiation and progression is presented along with a new paradigm for the approach to personalized targeted cancer therapy, clinical monitoring and cancer diagnosis.

ZMYND11 links histone H3.3K36me3 to transcription elongation and tumour suppression.

Recognition of modified histones by 'reader' proteins plays a critical role in the regulation of chromatin. H3K36 trimethylation (H3K36me3) is deposited onto the nucleosomes in the transcribed regions after RNA polymerase II elongation. In yeast, this mark in turn recruits epigenetic regulators to reset the chromatin to a relatively repressive state, thus suppressing cryptic transcription. However, much less is known about the role of H3K36me3 in transcription regulation in mammals. This is further complicated by the transcription-coupled incorporation of the histone variant H3.3 in gene bodies. Here we show that the candidate tumour suppressor ZMYND11 specifically recognizes H3K36me3 on H3.3 (H3.3K36me3) and regulates RNA polymerase II elongation. Structural studies show that in addition to the trimethyl-lysine binding by an aromatic cage within the PWWP domain, the H3.3-dependent recognition is mediated by the encapsulation of the H3.3-specific 'Ser 31' residue in a composite pocket formed by the tandem bromo-PWWP domains of ZMYND11. Chromatin immunoprecipitation followed by sequencing shows a genome-wide co-localization of ZMYND11 with H3K36me3 and H3.3 in gene bodies, and its occupancy requires the pre-deposition of H3.3K36me3. Although ZMYND11 is associated with highly expressed genes, it functions as an unconventional transcription co-repressor by modulating RNA polymerase II at the elongation stage. ZMYND11 is critical for the repression of a transcriptional program that is essential for tumour cell growth; low expression levels of ZMYND11 in breast cancer patients correlate with worse prognosis. Consistently, overexpression of ZMYND11 suppresses cancer cell growth in vitro and tumour formation in mice. Together, this study identifies ZMYND11 as an H3.3-specific reader of H3K36me3 that links the histone-variant-mediated transcription elongation control to tumour suppression.

Genistein downregulates onco-miR-1260b and inhibits Wnt-signalling in renal cancer cells.

BACKGROUND: Wnt-signalling has an important role in renal cancer and it is modulated by genistein in other cancers. Recently, microRNAs (miRNAs) have emerged as new regulators of gene expression. Thus, we focused on miRNAs to examine the regulatory mechanism of genistein on the Wnt-signalling pathway in renal cell carcinoma (RCC). METHODS: Initially, we investigated the effect of genistein on Wnt-signalling (TOPflash reporter assay (TCF reporter assays)) in renal cancer cells, and using microarray identified candidate miRNAs whose expression was decreased by genistein. We performed functional analyses and investigated the relationship between miRNA expression and renal cancer patient outcomes. We also did 3'UTR luciferase assays to look at direct miRNA regulation of Wnt-signalling-related genes. RESULTS: Genistein promoted apoptosis while inhibiting RCC cell proliferation and invasion. Genistein also decreased TCF reporter activity in RCC cells. We found that miR-1260b was highly expressed and significantly downregulated by genistein in RCC cells. The expression of miR-1260b was significantly higher in renal cancer tissues compared with normal, and significantly related to overall shorter survival. In addition, miR-1260b promoted renal cancer cell proliferation and invasion in RCC cells. The 3'UTR luciferase activity of target genes (sFRP1, Dkk2, Smad4) was significantly decreased and their protein expression significantly upregulated in miR-1260b inhibitor-transfected renal cancer cells. CONCLUSION: Our data suggest that genistein inhibited Wnt-signalling by regulating miR-1260b expression in renal cancer cells.

Aristolochic acid-associated urothelial cancer in Taiwan.

Aristolochic acid, a potent human carcinogen produced by Aristolochia plants, is associated with urothelial carcinoma of the upper urinary tract (UUC). Following metabolic activation, aristolochic acid reacts with DNA to form aristolactam (AL)-DNA adducts. These lesions concentrate in the renal cortex, where they serve as a sensitive and specific biomarker of exposure, and are found also in the urothelium, where they give rise to a unique mutational signature in the TP53 tumor-suppressor gene. Using AL-DNA adducts and TP53 mutation spectra as biomarkers, we conducted a molecular epidemiologic study of UUC in Taiwan, where the incidence of UUC is the highest reported anywhere in the world and where Aristolochia herbal remedies have been used extensively for many years. Our study involves 151 UUC patients, with 25 patients with renal cell carcinomas serving as a control group. The TP53 mutational signature in patients with UUC, dominated by otherwise rare A:T to T:A transversions, is identical to that observed in UUC associated with Balkan endemic nephropathy, an environmental disease. Prominent TP53 mutational hotspots include the adenine bases of (5')AG (acceptor) splice sites located almost exclusively on the nontranscribed strand. A:T to T:A mutations also were detected at activating positions in the FGFR3 and HRAS oncogenes. AL-DNA adducts were present in the renal cortex of 83% of patients with A:T to T:A mutations in TP53, FGFR3, or HRAS. We conclude that exposure to aristolochic acid contributes significantly to the incidence of UUC in Taiwan, a finding with significant implications for global public health.

Oncogene interactions are required for glioma development and progression as revealed by a tissue specific transgenic mouse model.

The aggressive and invasive nature of brain tumors has hampered progress in the design and implementation of efficacious therapies. The recent success of targeted therapies in other tumor types makes this an attractive area for research yet complicating matters is the ability of brain tumors to circumvent the targeted pathways to develop drug resistance. Effective therapies will likely need to target more than one signaling pathway or target multiple nodes within a given pathway. Key to identifying these targets is the elucidation of the driver and passenger molecules within these pathways. Animal models provide a useful tool with many advantages in the study of these pathways. These models provide a means to dissect the critical components of tumorigenesis, as well as serve as agents for preclinical testing. This review focuses on the use of the RCAS/tv-a mouse model of brain tumors and describes their unique ability to provide insight into the role of oncogene cooperation in tumor development and progression.

[Yin-yang relationship between oncogene and antioncogene].

OBJECTIVE: Oncogene and antioncogene play contrary effects on the cell growth and proliferation controlling process, and cancer occurs when the presence of imbalance expression between them. That means there is yin-yang relationship between oncogene (yang) and antioncogene (yin), and also inside both of them. Taking the oncogene myc and antioncogene p53 for example, the yin gene p53 acts, in the yin side, to promote cell apoptosis and inhibit cell growth, while in the yang side, it facilitates for repairing the injured DNA to keep cell survival; the yang gene myc, promoting cell growth and proliferation in the yang side and inducing cell apoptosis in the yin side. To elucidate the yin-yang reactions between oncogene and antioncogene would be of important significance in the all-round and profound research of cancer.

Gene expression profiling during early folliculogenesis in the mouse ovary.

OBJECTIVE: To evaluate genes involved in ovarian primordial-to-primary follicle transition. DESIGN: Experimental animal study. SETTING: Research institute. ANIMAL(S): Day-2 and day-4 female Swiss mice. INTERVENTION(S): We conducted a complementary DNA array study using ovarian messenger RNAs from day-2 and day-4 mice. MAIN OUTCOME MEASURE(S): The expression profiles of 1,176 genes in neonatal mouse ovaries on day 2 and day 4, which contain primordial and primary follicles, respectively, were compared. RESULT(S): Twenty-six percent of genes were differentially expressed between day-2 and day-4 ovaries, with 19% being up-regulated and 7% down-regulated in day 4. Analysis of differentially expressed genes revealed that the primordial-to-primary follicle stage transition is associated with induction in the expression of mainly growth factors, immune-related factors, hormone and hormone receptors, and signal transducers. The transition is also associated with proliferation of granulosa cells and absence of apoptosis. In addition, our studies demonstrated that the primary follicles express estrogen receptor beta and are responsive to estrogen actions in vitro in terms of increase in the number of primary follicles and granulosa cell proliferation. CONCLUSION(S): The transition of primordial to primary follicles is associated with the participation of multiple pathways in regulating gene expression.