Molecular genetic alterations of c-myc oncogene in superficial and locally advanced bladder cancer

The mechanism of USP43 in the development of tumor: a literature review

Ubiquitination of the proteins is crucial for governing protein degradation and regulating fundamental cellular processes. Deubiquitinases (DUBs) have emerged as significant regulators of multiple pathways associated with cancer and other diseases, owing to their capacity to remove ubiquitin from target substrates and modulate signaling. Consequently, they represent potential therapeutic targets for cancer and other life-threatening conditions. USP43 belongs to the DUBs family involved in cancer development and progression. This review aims to provide a comprehensive overview of the existing scientific evidence implicating USP43 in cancer development. Additionally, it will investigate potential small-molecule inhibitors that target DUBs that may have the capability to function as anti-cancer medicines.

Genetic insights into bladder cancer: the impact of SIRT1 gene polymorphism

Bladder cancer (BC) has shown a significant global health concern with distinct pathological, genetic, and epigenetic characteristics. Its prevalence is influenced by various risk factors, including age, gender, and genetic predisposition. This study investigates the association between BC and the Sirtuin 1 (SIRT1) gene polymorphism rs369274325 in the Turkish population. Genomic DNA was isolated from peripheral blood samples and genotyping of rs369274325 polymorphism in SIRT 1 was investigated in 200 individuals (in 100 Turkish bladder cancer patients and 100 healthy individuals as the control group.) by real-time PCR. Demographic information, smoking and alcohol consumption status was analyzed by statistical analysis. Statistical analysis was performed by Pearson's Chi-square test. Smoking and alcohol consumption were significantly higher in BC patients compared to controls (p < 0.00018 and p < 0.0001, respectively). The genotypic distribution of SIRT1 rs369274325 did not show a significant difference between BC patients and controls (p = 0.5550). BC, influenced by genetic and environmental factors, has been linked to various gene mutations. SIRT1, involved in diverse physiological processes, is proposed to play a role in BC. However, our study did not find a significant association between SIRT1 rs369274325 polymorphism and BC in the Turkish population.

USP43 stabilizes c-Myc to promote glycolysis and metastasis in bladder cancer

A hallmark of tumor cells, including bladder cancer (BLCA) cells, is metabolic reprogramming toward aerobic glycolysis (Warburg effect). The classical oncogene MYC, which is crucial in regulating glycolysis, is amplified and activated in BLCA. However, direct targeting of the c-Myc oncoprotein, which regulates glycolytic metabolism, presents great challenges and necessitates the discovery of a more clarified regulatory mechanism to develop selective targeted therapy. In this study, a siRNA library targeting deubiquitinases identified a candidate enzyme named USP43, which may regulate glycolytic metabolism and c-Myc transcriptional activity. Further investigation using functional assays and molecular studies revealed a USP43/c-Myc positive feedback loop that contributes to the progression of BLCA. Moreover, USP43 stabilizes c-Myc by deubiquitinating c-Myc at K148 and K289 primarily through deubiquitinase activity. Additionally, upregulation of USP43 protein in BLCA increased the chance of interaction with c-Myc and interfered with FBXW7 access and degradation of c-Myc. These findings suggest that USP43 is a potential therapeutic target for indirectly targeting glycolytic metabolism and the c-Myc oncoprotein consequently enhancing the efficacy of bladder cancer treatment.

Downregulation of HINFP induces senescence-associated secretory phenotype to promote metastasis in a non-cell-autonomous manner in bladder cancer

Transcription dysregulation is a salient characteristic of bladder cancer (BC), but no appropriate therapeutic target for it has been established. Here, we found that heterogeneous downregulation of histone H4 transcription factor (HINFP) was associated with senescence in BC tissues and that lower HINFP expression could predict an unfavorable outcome in BC patients. Knockout of HINFP transcriptionally inhibited H1F0 and H1FX to trigger DNA damage, consequently inducing cell senescence to repress the proliferation and growth of BC cells. However, the senescence-associated secretory phenotype, characterized by increases in MMP1/3, enhances the invasion and metastasis of non-senescent BC cells. Histone deacetylase inhibitors (HDACis) could efficiently eliminate the senescent cells induced by HINFP knockout to suppress the invasion and metastasis of BC cells. Our study suggests that HDACis, widely used in multiple cancer types in a clinical context, may also benefit BC patients with metastases induced by cell senescence.

Synthesizing artificial devices that redirect cellular information at will

Natural signaling circuits could be rewired to reprogram cells with pre-determined procedures. However, it is difficult to link cellular signals at will. Here, we describe signal-connectors—a series of RNA devices—that connect one signal to another signal at the translational level. We use them to either repress or enhance the translation of target genes in response to signals. Application of these devices allows us to construct various logic gates and to incorporate feedback loops into gene networks. They have also been used to rewire a native signaling pathway and even to create novel pathways. Furthermore, logical AND gates based on these devices and integration of multiple signals have been used successfully for identification and redirection of the state of cancer cells. Eventually, the malignant phenotypes of cancers have been reversed by rewiring the oncogenic signaling from promoting to suppressing tumorigenesis. We provide a novel platform for redirecting cellular information.

Cells respond to signals from their surrounding environment. External signals activate a sequence of events inside the cell that can change how it behaves. These events are often called signaling pathways and they typically change the cell’s behavior by changing the activity of its genes.

A major objective of the field of genetic engineering is to customize or artificially create new signaling pathways to make cells behave in certain ways. The ability to control a cell’s behavior is likely to have a major impact on human health and medicine. For instance, it may be possible to reprogram signaling events in cancer cells so that they die rather than grow rapidly.

Researchers are developing artificial genetic devices to manipulate signaling pathways. Molecules of ribonucleic acid (or RNA) are widely used to design such devices. In nature, RNA molecules are highly versatile: messenger RNA molecules carry genetic information in a form that can be translated into protein, while other RNA molecules fine-tune gene expression and perform a host of other roles. RNA is apt for artificial devices because it can be tailored to detect signals and convert this information into a predictable outcome, such as turning specific genes on or off.

In 2016, researchers constructed an RNA device to control the expression of genes in response to particular signals. However, this device was too large to deliver efficiently inside cells. Now, Liu, Li, Chen et al. – including some of the researchers involved the 2016 study – design smaller RNA devices to overcome this limitation. Each new device consists of two RNA components: one that recognizes the signal, and another that recognizes the messenger RNA of a target gene. Together the two components trigger the desired change in gene expression in response to a specific signal.

The devices were shown to have multiple uses such as making new connections in a signaling pathway and creating new signaling networks. Furthermore, Liu, Li, Chen et al. engineered one device such that it was able to specifically turn off genes in a particular signaling pathway that allows human bladder cancer cells to divide. By silencing these genes, the cancer cells were less able to grow.

These newly developed RNA devices should allow other researchers to customize cellular information and may have future therapeutic applications as well.

PIK3CA hypomethylation plays a key role in activation of the PI3K/AKT pathway in esophageal cancer in Chinese patients

AIM

To investigate the role of PIK3CA oncogene in tumorigenesis and development of esophageal cancer in Chinese patients at the levels of genetic mutation and epigenetics.

METHODS

Seventy six esophageal tumor samples and corresponding adjacent normal tissues were collected, and the genomic DNA was extracted. Mutations in the 9th and 20th exons of PIK3CA gene were detected using conventional sequencing. PIK3CA methylation rates in two selected CpG islands (CpG island 1 and 2) were detected using sub-bisulfate modified sequencing. P110α and pAKT expression levels were detected with Western blotting.

RESULTS

In PIK3CA gene of the tumor tissues, G1633C (E545Q) mutation was detected in the 9th exon with a rate of 3.95% (3/76), whereas mutation was not found in the 20th exon. Nor mutation did occur in PIK3CA gene of the adjacent normal tissues. The methylation rate of the CpG island 1 had no significant difference between the tumor and adjacent tissues (0.77%±0.009% vs 0.89%±0.008%), but the methylation rate of the CpG island 2 in the esophageal tumors was significantly lower than that in the adjacent tissues (6.00%±2.80% vs 10.45%±5.51%). Furthermore, the rate of methylation of the CpG island 2 in TNM stage III and IV esophageal cancer (3.84%±2.08%) was significantly lower than in stage I (8.52%±2.55%) and stage II (6.42%±2.36%). PIK3CA gene hypomethylation in esophageal cancer was significantly correlated with high expression of p110α.

CONCLUSION

PIK3CA gene hypomethylation plays a key role in the tumorigenesis and development of esophageal cancer in Chinese patients, while the mutations of PIK3CA gene have little effect on the development of esophageal cancer.

The Myc oncoprotein as a therapeutic target for human cancer

Myc expression is deregulated in a wide range of human cancers and is often associated with aggressive, poorly differentiated tumors. The Myc protein is a transcription factor that regulates a variety of cellular processes including cell growth and proliferation, cell-cycle progression, transcription, differentiation, apoptosis, and cell motility. Potential strategies that either inhibit the growth promoting effect of Myc and/or activate its pro-apoptotic function are presently being explored. In this review, we give an overview of Myc activation in human tumors and discuss current strategies aimed at targeting Myc for cancer treatment. Such therapies could have potential in combination with mechanistically different cytotoxic drugs to combat and eradicate tumors cells.

Microsatellite instability as an indicator of malignant progression in laryngeal premalignancy

BACKGROUND

Microsatellite instability (MSI) is considered a novel marker of genetic instability, and preliminary studies have shown that it may provide useful information in assessing the risk of malignant progression in preinvasive lesions.

METHODS

We analyzed MSI in serial biopsy specimens from 10 patients with preinvasive laryngeal lesions and corresponding metachronous laryngeal cancers compared with biopsy specimens of similar lesions without malignant transformation from 20 subjects in a match-paired analysis. MSI was determined by assessing the status of 14 microsatellite markers (chromosome loci: 2p16, 3q21-24, 4q12, 9p21, 13q14, 16q22.1, 17p12 and 21q21) in DNA biopsy specimens.

RESULTS

MSI(+) (aberration at two or more loci) was detected in seven of 10 patients with premalignant lesions progressed to carcinoma, whereas only four of the 20 biopsy specimens from control subjects showed an unstable phenotype (p < .01). Interestingly, preinvasive laryngeal lesions with MSI at hMSH2/hMSH6 loci frequently had instability at one or more additional loci and were considered as MSI(+) (overall in eight of 12 cases: six premalignant lesions progressed to cancer and one without progression of the original laryngeal lesion, p < .01). The immunohistochemical analysis of the hMSH2 protein expression in our series, however, did not suggest its involvement in laryngeal carcinogenesis.

CONCLUSIONS

Our study indicates that MSI is more common in preneoplastic laryngeal lesions progressing to cancer, thus suggesting that microsatellite status assessment may be useful in determining the risk of malignant progression in patients with preinvasive laryngeal lesions for whom chemopreventive and multiple endoscopic protocols can be attempted.

High-throughput tissue microarray analysis ofCMYC amplificationin urinary bladder cancer

Alterations of chromosome 8, preferentially deletions of 8p and gains of 8q, belong to the most frequent cytogenetic changes in bladder cancer. CMYC on 8q24 is a candidate oncogene in this region. Little is known about the clinical significance of CMYC copy number changes in urinary bladder cancer because its frequency is low and a limited numbers of tumors were analyzed so far. To investigate the impact of CMYC alterations on tumor progression and patient prognosis in bladder cancer, we applied FISH to a tissue microarray containing 2317 bladder cancer samples. Presence of CMYC copy number increase was associated with advanced stage and high grade. CMYC amplifications were seen in 3 of 467 pTa (0.6%), 10 of 247 pT1 (4%) and 11 of 201 pT2-4 urothelial carcinomas (5.5%; p < 0.0001), as well as in 1 of 123 G1 (0.8%), 8 of 470 G2 (1.7%) and 17 of 365 G3 urothelial carcinomas (4.7%; p < 0.0001). CMYC gains were present in 49 of 467 pTa (10.5%), 39 of 247 pT1 (15.8%) and 43 of 201 pT2-4 urothelial carcinoma (21.4%; p < 0.0001), as well as in 7 of 123 G1 (5.7%), 56 of 470 G2 (11.9%) and 72 of 365 G3 urothelial carcinomas (19.7%; p < 0.0001). CMYC copy number changes were unrelated to prognosis of bladder cancer patients. We conclude that alterations of the CMYC gene, including copy number gains and amplifications, are linked to genetically unstable bladder cancers that are characterized by a high histologic grade and/or invasive growth. Patient prognosis was not affected by CMYC gene copy number changes.

Molecular analysis of PTEN and MXI1 in primary bladder carcinoma

Loss of heterozygosity (LOH) on 10q is associated with late-stage events in urothelial neoplastic progression. The tumor suppressor gene PTEN, which is mutated or homozygously deleted in numerous cancers, maps to a region of 10q within the reported region of minimal loss in bladder tumors. In two recent studies alterations in the PTEN gene occur at a low frequency in bladder tumors displaying 10q LOH. We have screened 35 late-stage bladder tumors for mutations in PTEN and MXI1, both genes mapping to chromosome 10q. Using single-strand conformation polymorphism analysis, we identified 6 tumors harboring mutations in PTEN and 2 additional tumors displaying homozygous deletion at this locus. No MXI1 mutations were identified within the same tumor panel. Of 16 bladder tumor cell lines analyzed, 2 showed homozygous deletion of PTEN and 3 harbored point mutations resulting in an amino acid change. Two cell lines harbored missense mutations in MXI1. We report a significantly higher frequency of PTEN alterations in bladder carcinoma (23%) than was previously recorded, with no accompanying mutations in the MXI1 gene.

DNA copy number changes in Schistosoma-associated and non-Schistosoma-associated bladder cancer

DNA copy number changes were investigated in 69 samples of schistosoma-associated (SA) and non-schistosoma-associated (NSA) squamous cell carcinoma (SCC) and transitional cell carcinoma (TCC) of the bladder by comparative genomic hybridization (CGH). DNA copy number changes were detected in 47 tumors. SA tumors had more changes than NSA tumors (mean, 7 vs. 4), whereas the number of changes in SCC and TCC tumors was similar. SA tumors displayed more gains than losses (1.7:1), whereas NSA tumors showed an equal number of gains and losses. Changes that were observed at similar frequencies in SCC and TCC, irrespective of the schistosomal status, included gains and high-level amplifications at 1q, 8q, and 20q and losses in 9p and 13q. These changes may be involved in a common pathway for bladder tumor development and progression independent of schistosomal status or histological subtype. Losses in 3p and gains at 5p were seen only in SCC (P < 0.01) and losses in 5q were more frequent in SA-SCC than in other tumors (P < 0.05). However, changes that were more frequent in TCC than those in SCC included gains at 17q (P < 0.01) and losses in 4q (P < 0.05) and 6q (P < 0.01). Gains and high-level amplifications at 5p were seen only in SA-SCC (P < 0. 01), whereas gains and high-level amplifications with minimal common overlapping regions at 11q13 were more frequently seen both in SA-SCC and SA-TCC tumors (P < 0.01). In addition to the above mentioned alterations, several other changes were also seen at lower frequencies. The variations in the DNA copy number changes observed in TCC, SCC, SA, and NSA bladder carcinomas suggest that these tumors have different genetic pathways.

DNA methylation at mammalian replication origins

In Escherichia coli, DNA methylation regulates both origin usage and the time required to reassemble prereplication complexes at replication origins. In mammals, at least three replication origins are associated with a high density cluster of methylated CpG dinucleotides, and others whose methylation status has not yet been characterized have the potential to exhibit a similar DNA methylation pattern. One of these origins is found within the approximately 2-kilobase pair region upstream of the human c-myc gene that contains 86 CpGs. Application of the bisulfite method for detecting 5-methylcytosines at specific DNA sequences revealed that this region was not methylated in either total genomic DNA or newly synthesized DNA. Therefore, DNA methylation is not a universal component of mammalian replication origins. To determine whether or not DNA methylation plays a role in regulating the activity of origins that are methylated, the rate of remethylation and the effect of hypomethylation were determined at origin beta (ori-beta), downstream of the hamster DHFR gene. Remethylation at ori-beta did not begin until approximately 500 base pairs of DNA was synthesized, but it was then completed by the time that 4 kilobase pairs of DNA was synthesized (<3 min after release into S phase). Thus, DNA methylation cannot play a significant role in regulating reassembly of prereplication complexes in mammalian cells, as it does in E. coli. To determine whether or not DNA methylation plays any role in origin activity, hypomethylated hamster cells were examined for ori-beta activity. Cells that were >50% reduced in methylation at ori-beta no longer selectively activated ori-beta. Therefore, at some loci, DNA methylation either directly or indirectly determines where replication begins.