SUN2: A potential therapeutic target in cancer

Observational, causal relationship and shared genetic basis between cholelithiasis and gastroesophageal reflux disease: evidence from a cohort study and comprehensive genetic analysis

OBJECTIVE

Cholelithiasis and gastroesophageal reflux disease (GERD) contribute to significant health concerns. We aimed to investigate the potential observational, causal, and genetic relationships between cholelithiasis and GERD.

DESIGN

The observational correlations were assessed based on the prospective cohort study from UK Biobank. Then, by leveraging the genome-wide summary statistics of cholelithiasis (N = 334,277) and GERD (N = 332,601), the bidirectional causal associations were evaluated using Mendelian randomization (MR) analysis. Subsequently, a series of genetic analyses was used to assess the genetic correlation, shared loci, and genes between cholelithiasis and GERD.

RESULTS

The prospective cohort analyses revealed a significantly increased risk of GERD in individuals with cholelithiasis (hazard ratio [HR] = 1.99; 95% confidence interval [CI], 1.89-2.10) and a higher risk of cholelithiasis among patients with GERD (HR = 2.30; 95% CI, 2.18-2.44). The MR study indicated the causal effect of genetic liability to cholelithiasis on the incidence of GERD (odds ratio [OR] = 1.08; 95% CI, 1.05-1.11) and the causal effect of genetic predicted GERD on cholelithiasis (OR = 1.15; 95% CI, 1.02-1.31). In addition, cholelithiasis and GERD exhibited a strong genetic association. Cross-trait meta-analyses identified 5 novel independent loci shared between cholelithiasis and GERD. Three shared genes, including SUN2, CBY1, and JOSD1, were further identified as novel risk genes.

CONCLUSION

The elucidation of the shared genetic basis underlying the phenotypic relationship of these 2 complex phenotypes offers new insights into the intrinsic linkage between cholelithiasis and GERD, providing a novel research direction for future therapeutic strategy and risk prediction.

Regulation of ovarian cancer by protein post-translational modifications

Ovarian cancer is one of the predominant gynecologic malignancies worldwide, ranking as the fifth leading cause of cancer-induced mortality among women globally. Post-translational modifications (PTMs) refer to the enzyme-catalyzed attachment of functional groups to proteins, thereby inducing structural and functional alterations. Recent evidence suggests that PTMs play multifaceted roles in the pathogenesis of ovarian cancer, influencing processes such as cell cycle, metabolism reprogramming, chemoresistance, and immune responses against cancer. Accordingly, a comprehensive understanding of the diverse PTMs in ovarian cancer is imperative for decoding the complex molecular mechanisms that drive cancer progression. This review discusses the latest developments in the study of protein PTMs in ovarian cancer and introduces pharmacological approaches that target these modifications as therapeutic strategies.

Gene Expression Aberrations in Alcohol-Associated Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the most prevalent primary liver cancer, ranking as the sixth most common cancer worldwide and the fourth leading cause of cancer-related deaths. Most HCC cases originate from cirrhotic livers, typically due to chronic liver diseases, such as hepatitis B (HBV) and hepatitis C (HCV) infections, and alcoholism. HCC cells often harbor numerous somatic mutations that are implicated in HCC development, but epigenetic factors, such as miRNA interference, can also affect HCC initiation and progress. miRNA-221 has been explored as a factor affecting HCC development in HCC of viral etiology, but little is known about its effects on gene expression in alcohol-associated HCC. This study aimed to explore potentially similar gene expression aberrations underlying viral and alcohol-induced HCC. We analyzed available transcriptome data from non-tumor hepatocytes and viral-induced HCC tissues. The most notable differences in gene expression associated with miRNA-221 between non-tumor hepatocytes and viral-induced HCC involved NTF-3 and MYBL1 genes. To assess these data in alcohol-induced HCC, we examined 111 tissue samples: tumor tissue and cirrhotic tissue samples from 37 HCC patients and 37 samples from non-tumor liver tissue using RT-Q PCR. We found no significant difference in NTF-3 expression, but MYBL1 expression was significantly lower in HCC tissue compared to non-tumor hepatocytes and cirrhotic tissue. Our findings highlight the importance of the MYBL1 gene in HCC development and emphasize the need for diverse approaches in evaluating tumor mechanisms.

Emerin deficiency drives MCF7 cells to an invasive phenotype

During metastasis, cancer cells traverse the vasculature by squeezing through very small gaps in the endothelium. Thus, nuclei in metastatic cancer cells must become more malleable to move through these gaps. Our lab showed invasive breast cancer cells have 50% less emerin protein resulting in smaller, misshapen nuclei, and higher metastasis rates than non-cancerous controls. Thus, emerin deficiency was predicted to cause increased nuclear compliance, cell migration, and metastasis. We tested this hypothesis by downregulating emerin in noninvasive MCF7 cells and found emerin knockdown causes smaller, dysmorphic nuclei, resulting in increased impeded cell migration. Emerin reduction in invasive breast cancer cells showed similar results. Supporting the clinical relevance of emerin reduction in cancer progression, our analysis of 192 breast cancer patient samples showed emerin expression inversely correlates with cancer invasiveness. We conclude emerin loss is an important driver of invasive transformation and has utility as a biomarker for tumor progression.

Emerin deficiency drives MCF7 cells to an invasive phenotype

During metastasis, cancer cells traverse the vasculature by squeezing through very small gaps in the endothelium. Thus, nuclei in metastatic cancer cells must become more malleable to move through these gaps. Our lab showed invasive breast cancer cells have 50% less emerin protein resulting in smaller, misshapen nuclei, and higher metastasis rates than non-cancerous controls. Thus, emerin deficiency was predicted to cause increased nuclear compliance, cell migration, and metastasis. We tested this hypothesis by downregulating emerin in noninvasive MCF7 cells and found emerin knockdown causes smaller, dysmorphic nuclei, resulting in increased impeded cell migration. Emerin reduction in invasive breast cancer cells showed similar results. Supporting the clinical relevance of emerin reduction in cancer progression, our analysis of 192 breast cancer patient samples showed emerin expression inversely correlates with cancer invasiveness. We conclude emerin loss is an important driver of invasive transformation and has utility as a biomarker for tumor progression.

Decoding dynamic miRNA:ceRNA interactions unveils therapeutic insights and targets across predominant cancer landscapes

Competing endogenous RNAs play key roles in cellular molecular mechanisms through cross-talk in post-transcriptional interactions. Studies on ceRNA cross-talk, which is particularly dependent on the abundance of free transcripts, generally involve large- and small-scale studies involving the integration of transcriptomic data from tissues and correlation analyses. This abundance-dependent nature of ceRNA interactions suggests that tissue- and condition-specific ceRNA dynamics may fluctuate. However, there are no comprehensive studies investigating the ceRNA interactions in normal tissue, ceRNAs that are lost and/or appear in cancerous tissues or their interactions. In this study, we comprehensively analyzed the tumor-specific ceRNA fluctuations observed in the three highest-incidence cancers, LUAD, PRAD, and BRCA, compared to healthy lung, prostate, and breast tissues, respectively. Our observations pertaining to tumor-specific competing endogenous RNA (ceRNA) interactions revealed that, in the cases of lung adenocarcinoma (LUAD), prostate adenocarcinoma (PRAD), and breast invasive carcinoma (BRCA), 3,204, 1,233, and 406 ceRNAs, respectively, engage in post-transcriptional intercommunication within tumor tissues, in contrast to their absence in corresponding healthy samples. We also found that 90 ceRNAs are shared by the three cancer types and that these ceRNAs participate in ceRNA interactions in tumor tissues compared to those in normal tissues. Among the 90 ceRNAs that directly interact with miRNAs, we uncovered a core network of 165 miRNAs and 63 ceRNAs that should be considered in RNA-targeted and RNA-mediated approaches in future studies and could be used in these three aggressive cancer types. More specifically, in this core interaction network, ceRNAs such as GALNT7, KLF9, and DAB2 and miRNAs like miR-106a/b-5p, miR-20a-5p, and miR-519d-3p may have potential as common targets in the three critical cancers. In contrast to conventional methods that construct ceRNA networks using differentially expressed genes compared to normal tissues, our proposed approach identifies ceRNA players by considering their context within the ceRNA:miRNA interactions. Our results have the potential to reveal distinct and common ceRNA interactions in cancer types and to pinpoint critical RNAs, thereby paving the way for RNA-based strategies in the battle against cancer.

FBXO2 targets glycosylated SUN2 for ubiquitination and degradation to promote ovarian cancer development

SAD1/UNC84 domain protein-2 (SUN2) plays a tumor suppressor role in various types of cancer by inhibiting cancer cell proliferation, migration and promoting apoptosis. However, the post-translational regulation of SUN2 and the cellular mechanism responsible for its proteasomal degradation remains largely unknown. Here, we show that FBXO2, an E3 ubiquitin ligase of the F-box proteins (FBPs) family targets glycosylated SUN2 for ubiquitination and degradation via the ubiquitin-proteasome system (UPS). By integrating the Cancer Genome Atlas (TCGA), Gene Expression Omnibus (GEO), and the Encyclopedia of Cancer Cell Lines (CCLE) databases, we revealed that FBXO2 was selectively highly expressed in ovarian cancer (OV) tissues and cells. Patients with relatively high FBXO2 expression levels were associated with worse prognosis. Manipulation of the expression of FBXO2 affecting ovarian cancer cell proliferation, migration/invasion in vitro, and tumor growth in mice in vivo. The transcription factor SOX6 promoted FBXO2 expression by recognizing a putative response element localized on the promoter region of FBXO2. Abnormally highly expressed FBXO2 recognized and targeted glycosylated SUN2 protein for ubiquitination-depended degradation to prevent cell apoptosis, promote cell proliferation, and ultimately promote the progression of OV. Thus, we revealed a new SOX6-FBXO2-SUN2 axis that contributed to the development of OV, and targeting this axis may represent an effective OV treatment strategy.

Prostate Cancer Susceptibility Loci Identified in GATA2 and ZMIZ1 in Chinese Population

Background

Common genetic risk variants for prostate cancer (PCa) have been identified at approximately 170 loci using genome-wide association studies (GWAS), most of which were identified in European populations. Recently, GWAS were applied to a large Japanese cohort and identified 12 novel susceptibility loci associated with PCa risk. In this study, we aim to investigate PCa susceptibility loci in the Chinese population. The study data will be used to promote PCa risk control in China.

Methods

A total of 235 PCa patients and 252 control subjects (all unrelated) were enrolled in this case-control PCa study. Nine single nucleotide polymorphisms (SNPs) were genotyped in GATA2 (rs73862213, rs2335052, and rs10934857), ZMIZ1 (rs704017, rs77911174, and rs3740259), and SUN2 (rs78397383, rs5750680, and rs138705) genes. The associations between the candidate SNPs and PCa were analyzed using multiple-factor logistic regression and haplotype analysis.

Results

The allele frequency distributions of rs73862213 and rs2335052 in the GATA2 gene and rs704017 and rs77911174 in the ZMIZ1 gene were found to be significantly different between PCa cases and controls. Haplotype analysis revealed that the G-C-A haplotype of the GATA2 gene (order of SNPs: rs73862213-rs2335052-rs10934857) and the G-G-G haplotype of the ZMIZ1 gene (order of SNPs: rs704017-rs77911174-rs3740259) were associated with increased PCa risk. None of the SUN2 haplotypes were associated with PCa.

Conclusions

Our study data indicates that the minor alleles of rs73862213 and rs2335052 in the GATA2 gene and rs704017 and rs77911174 in the ZMIZ1 gene were associated with increased PCa risk. These findings greatly extended our knowledge of the etiology of PCa.

Elevated Sad1 and UNC84 Domain Containing 2 (SUN2) level inhibits cell growth and aerobic glycolysis in oral cancer through reducing the expressions of glucose transporter 1 (GLUT1) and lactate dehydrogenase A (LDHA)

Background/purpose

Oral cancer is a malignant tumor accompanied by high morbidity, mortality, and poor prognosis. Therefore, it is urgent to explore the percise regulation mechanisms underlying oral cancer. Sad1 and UNC84 Domain Containing 2 (SUN2) was considered as a tumor suppressor in some cancers. The purpose of the study was to define the role of SUN2 in oral cancer progression.

Materials and methods

Tumor tissues and paired paracancerous healthy tissues from 56 oral cancer patients were collected. Cell viability was measured using MTT assay. The colony formation assay was applied to determine cell proliferation ability. The mRNA and protein levels were assessed by qRT-PCR and Western blot, respectively.

Results

SUN2 expression was decreased in oral cancer tissues and cell models. SUN2 overexpression suppressed the growth of oral cancer cells, while the down-regulation of SUN2 promoted cell growth. SUN2 overexpression restrained the glucose uptake, lactate production, and ATP level of oral cancer cells, whereas down-regulation of SUN2 promoted glycolysis. Besides, elevated SUN2 inhibited the glucose transporter 1 (GLUT1) and lactate dehydrogenase A (LDHA) levels. However, SUN2 knockdown increased the levels of GLUT1 and LDHA.

Conclusion

SUN2 was decreased in oral cancer in vivo and in vitro. SUN2 overexpression suppressed cell growth and glycolysis via reducing the levels of GLUT1 and LDHA in oral cancer.

A CRISPR Test for Detection of Circulating Nuclei Acids

Emerging CRISPR-based nucleic acid detection shows great promise in molecular diagnosis of diseases. CRISPR-Cas12a can sensitively and specifically detect human papillomavirus (HPV) DNA in anal swabs. However, the current CRISPR-Cas12a system needs auxiliary and expensive equipment, which limit its application as a point-of-care (POC) diagnostic tool. This study aimed to develop CRISPR-Cas12a as a POC test to directly target plasma for circulating HPV DNA detection by immediately reading results with naked eyes. Cell-cultured supernatants of either HPV16- or 18-positive cancer cells were treated with lysis buffer followed by isothermal amplification without DNA isolation. Cas12a, crRNA, and fluorescent-biotin reporters were incubated with the lysates. Our data showed that integrating CRISPR-Cas12a with lateral-flow strips could directly and specifically detect HPV16 and 18 in the liquid samples with the same limit of detection (0.24 fM) as did polymerase chain reaction but requiring less time. Furthermore, the CRISPR-Cas12a system could rapidly detect presence of HPV16 and HPV18 in plasma samples of 13 of 14 and 3 of 10 the patients with histopathological diagnosis of cervical cancer, respectively. Therefore, a CRISPR-Cas12a-based POC system was developed for conveniently detecting circulating nuclei acid targets in body fluids without requiring technical expertise and ancillary machineries.