The Multifaceted Roles of RCC1 in Tumorigenesis

RCC1 regulation of subcellular protein localization via Ran GTPase drives pancreatic ductal adenocarcinoma growth

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignancy, with limited therapeutic options. Here, we evaluated the role of regulator of chromosome condensation 1 (RCC1) in PDAC. RCC1 functions as a guanine exchange factor for GTP-binding nuclear protein Ran (Ran) GTPase and is involved in nucleocytoplasmic transport. RCC1 RNA expression is elevated in PDAC tissues compared to normal pancreatic tissues and correlates with poor prognosis. RCC1 silencing by RNAi and CRISPR-Cas9 knockout (KO) results in reduced proliferation in 2-D and 3-D cell cultures. RCC1 knockdown (KD) reduced migration and clonogenicity, enhanced apoptosis, and altered cell cycle progression in human PDAC and murine cells from LSL-KrasG12D/+; LSL-Trp53R172H/+; Pdx1-Cre (KPC) tumors. Mechanistically, RCC1 KO shows widespread transcriptomic alterations including regulation of PTK7, a co-receptor of the Wnt signaling pathway. RCC1 KD disrupted subcellular Ran localization and the Ran gradient. Nuclear and cytosolic proteomics revealed altered subcellular proteome localization in Rcc1 KD KPC-tumor-derived cells and several altered metabolic biosynthesis pathways. In vivo, RCC1 KO cells show reduced tumor growth potential when injected as sub-cutaneous xenografts. Finally, RCC1 KD sensitized PDAC cells to gemcitabine chemotherapy treatment. This study reveals the role of RCC1 in pancreatic cancer as a novel molecular vulnerability that could be exploited to enhance therapeutic response.

Transcriptomic data support phylogenetic congruence and reveal genomic changes associated with the repeated evolution of annualism in aplocheiloid killifishes (Cyprinodontiformes)

Repeated evolution of novel life histories that are correlated with ecological variables offers opportunities to study convergence in genetic, developmental, and metabolic features. Nearly half of the 800 species of Aplocheiloid killifishes, a clade of teleost fishes with a circumtropical distribution, are "annual" or seasonal species that survive in ephemeral bodies of water that desiccate and are unfeasible for growth, reproduction, or survival for weeks to months every year. But the repeated evolution of adaptations that are key features of the annual life history among these fishes remains poorly known without a robust phylogenetic framework. We present a large-scale phylogenomic reconstruction of aplocheiloid killifishes evolution using newly sequenced transcriptomes obtained from a diversity of killifish lineages representing putative independent origins of annualism. Ancestral state estimation shows that developmental dormancy (diapause), a key trait of the killifish annual life cycle, may have originated up to seven times independently among African and South American lineages. To further explore the genetic basis of this unique trait, we measure changes in evolutionary rates among orthologous genes across the killifish tree of life by quantifying codon evolution using dN/dS ratios. We show that some genes have higher dN/dS ratios in lineages leading to species with annual life history. Many of them constitute key developmental genes or nuclear-encoded metabolic genes that control oxidative phosphorylation. Lastly, we compare these genes with higher ω to genes previously associated to developmental dormancy and metabolic shifts in killifishes and other vertebrates, and thereby identify molecular evolutionary signatures of repeated transitions to extreme environments.

HSPA12A promotes c-Myc lactylation-mediated proliferation of tubular epithelial cells to facilitate renal functional recovery from kidney ischemia/reperfusion injury

Proliferation of renal tubular epithelial cells (TEC) is essential for restoring tubular integrity and thereby to support renal functional recovery from kidney ischemia/reperfusion (KI/R) injury. Activation of transcriptional factor c-Myc promotes TEC proliferation following KI/R; however, the mechanism regarding c-Myc activation in TEC is incompletely known. Heat shock protein A12A (HSPA12A) is an atypic member of HSP70 family. In this study, we found that KI/R decreased HSPA12A expression in mouse kidneys and TEC, while ablation of HSPA12A in mice impaired TEC proliferation and renal functional recovery following KI/R. Gain-of-functional studies demonstrated that HSPA12A promoted TEC proliferation upon hypoxia/reoxygenation (H/R) through directly interacting with c-Myc and enhancing its nuclear localization to upregulate expression of its target genes related to TEC proliferation. Notably, c-Myc was lactylated in TEC after H/R, and this lactylation was enhanced by HSPA12A overexpression. Importantly, inhibition of c-Myc lactylation attenuated the HSPA12A-induced increases of c-Myc nuclear localization, proliferation-related gene expression, and TEC proliferation. Further experiments revealed that HSPA12A promoted c-Myc lactylation via increasing the glycolysis-derived lactate generation in a Hif1α-dependent manner. The results unraveled a role of HSPA12A in promoting TEC proliferation and facilitating renal recovery following KI/R, and this role of HSPA12A was achieved through increasing lactylation-mediated c-Myc activation. Therefore, targeting HSPA12A in TEC might be a viable strategy to promote renal functional recovery from KI/R injury in patients.

Targeting guanine nucleotide exchange factors for novel cancer drug discovery

INTRODUCTION

Guanine nucleotide exchange factors (GEFs) regulate the activation of small GTPases (G proteins) of the Ras superfamily proteins controlling cellular functions. Ras superfamily proteins act as 'molecular switches' that are turned 'ON' by guanine exchange. There are five major groups of Ras family GTPases: Ras, Ran, Rho, Rab and Arf, with a variety of different GEFs regulating their GTP loading. GEFs have been implicated in various diseases including cancer. This makes GEFs attractive targets to modulate signaling networks controlled by small GTPases.

AREAS COVERED

In this review, the roles and mechanisms of GEFs in malignancy are outlined. The mechanism of guanine exchange activity by GEFs on a small GTPase is illustrated. Then, some examples of GEFs that are significant in cancer are presented with a discussion on recent progress in therapeutic targeting efforts using a variety of approaches.

EXPERT OPINION

Recently, GEFs have emerged as potential therapeutic targets for novel cancer drug development. Targeting small GTPases is challenging; thus, targeting their activation by GEFs is a promising strategy. Most GEF-targeted drugs are still in preclinical development. A deeper biological understanding of the underlying mechanisms of GEF activity and utilizing advanced technology are necessary to enhance drug discovery for GEFs in cancer.

Targeting RCC1 to block the human soft-tissue sarcoma by disrupting nucleo-cytoplasmic trafficking of Skp2

Soft-tissue sarcomas (STS) emerges as formidable challenges in clinics due to the complex genetic heterogeneity, high rates of local recurrence and metastasis. Exploring specific targets and biomarkers would benefit the prognosis and treatment of STS. Here, we identified RCC1, a guanine-nucleotide exchange factor for Ran, as an oncogene and a potential intervention target in STS. Bioinformatics analysis indicated that RCC1 is highly expressed and correlated with poor prognosis in STS. Functional studies showed that RCC1 knockdown significantly inhibited the cell cycle transition, proliferation and migration of STS cells in vitro, and the growth of STS xenografts in mice. Mechanistically, we identified Skp2 as a downstream target of RCC1 in STS. Loss of RCC1 substantially diminished Skp2 abundance by compromising its protein stability, resulting in the upregulation of p27Kip1 and G1/S transition arrest. Specifically, RCC1 might facilitate the nucleo-cytoplasmic trafficking of Skp2 via direct interaction. As a result, the cytoplasmic retention of Skp2 would further protect it from ubiquitination and degradation. Notably, recovery of Skp2 expression largely reversed the phenotypes induced by RCC1 knockdown in STS cells. Collectively, this study unveils a novel RCC1-Skp2-p27Kip1 axis in STS oncogenesis, which holds promise for improving prognosis and treatment of this formidable malignancy.

Molecular mechanisms underlying the regulation of tumour suppressor genes in lung cancer

Tumour suppressor genes play a cardinal role in the development of a large array of human cancers, including lung cancer, which is one of the most frequently diagnosed cancers worldwide. Therefore, extensive studies have been committed to deciphering the underlying mechanisms of alterations of tumour suppressor genes in governing tumourigenesis, as well as resistance to cancer therapies. In spite of the encouraging clinical outcomes demonstrated by lung cancer patients on initial treatment, the subsequent unresponsiveness to first-line treatments manifested by virtually all the patients is inherently a contentious issue. In light of the aforementioned concerns, this review compiles the current knowledge on the molecular mechanisms of some of the tumour suppressor genes implicated in lung cancer that are either frequently mutated and/or are located on the chromosomal arms having high LOH rates (1p, 3p, 9p, 10q, 13q, and 17p). Our study identifies specific genomic loci prone to LOH, revealing a recurrent pattern in lung cancer cases. These loci, including 3p14.2 (FHIT), 9p21.3 (p16INK4a), 10q23 (PTEN), 17p13 (TP53), exhibit a higher susceptibility to LOH due to environmental factors such as exposure to DNA-damaging agents (carcinogens in cigarette smoke) and genetic factors such as chromosomal instability, genetic mutations, DNA replication errors, and genetic predisposition. Furthermore, this review summarizes the current treatment landscape and advancements for lung cancers, including the challenges and endeavours to overcome it. This review envisages inspired researchers to embark on a journey of discovery to add to the list of what was known in hopes of prompting the development of effective therapeutic strategies for lung cancer.

CFDP1 regulates the stability of pericentric heterochromatin thereby affecting RAN GTPase activity and mitotic spindle formation

The densely packed centromeric heterochromatin at minor and major satellites is comprised of H3K9me2/3 histones, the heterochromatin protein HP1α, and histone variants. In the present study, we sought to determine the mechanisms by which condensed heterochromatin at major and minor satellites stabilized by the chromatin factor CFDP1 affects the activity of the small GTPase Ran as a requirement for spindle formation. CFDP1 colocalized with heterochromatin at major and minor satellites and was essential for the structural stability of centromeric heterochromatin. Loss of CENPA, HP1α, and H2A.Z heterochromatin components resulted in decreased binding of the spindle nucleation facilitator RCC1 to minor and major satellite repeats. Decreased RanGTP levels as a result of diminished RCC1 binding interfered with chromatin-mediated microtubule nucleation at the onset of mitotic spindle formation. Rescuing chromatin H2A.Z levels in cells and mice lacking CFDP1 through knock-down of the histone chaperone ANP32E not only partially restored RCC1-dependent RanGTP levels but also alleviated CFDP1-knockout-related craniofacial defects and increased microtubule nucleation in CFDP1/ANP32E co-silenced cells. Together, these studies provide evidence for a direct link between condensed heterochromatin at major and minor satellites and microtubule nucleation through the chromatin protein CFDP1.

Comprehensive analysis of prognostic value and immune infiltration of Regulator of Chromosome Condensation 2 in lung adenocarcinoma

Background: Lung adenocarcinoma (LUAD) incidence and mortality take the leading place of most malignancies. Previous studies have revealed the regulator of chromosome condensation 1 (RCC1) family members played an essential role during tumorigenesis. However, its biological functions in LUAD still need further investigation. Methods: Several databases were applied to explore potential effects of RCC1 family members on LUAD, such as Oncomine, GEPIA, and cBioPortal. Real-time PCR and immunohistochemistry were used to verify the expression of RCC2 in stage I LUAD. H1975 and A549 were selected to explore the biological function of RCC2 in cellular malignant phenotype. Results: The expressions of RCC1 and RCC2 showed marked differences in malignant tissue compared to lung tissue. The higher the expression levels of RCC1 or RCC2 in LUAD patients, the shorter their overall survival (OS). In normal lung tissues, RCC1 expression was highly enriched in alveolar cells and endothelial cells. Compare with RCC1, RCC2 expression in normal lung tissue was significantly enriched in macrophages, B cells and granulocytes. Additionally, RCC2 expression level was correlated with multiple immune cell infiltration in LUAD. Moreover, the mutation or different sCNA status of RCC2 exerted influence on multiple immune cell infiltration distribution. We found that the upregulation of RCC1 and RCC2 were obviously related to TP53 mutation. GSEA analysis revealed that RCC2 was involved in the process of DNA replication, nucleotide excision repair and cell cycle, which might affect tumor progression through P53 signaling pathway. We further elucidated that downregulation of RCC2 could dramatically repress the migration and invasion of LUAD cells. Conclusions: The study demonstrated that RCC1 and RCC2 expression were markedly increased in early-stage of LUAD. Patients with high expression of RCC1 or RCC2 had a worse prognosis. Based on our analysis, RCC1 and RCC2 might exert influence on LUAD process through DNA replication, nucleotide excision repair and cell cycle, as well as cells migration and invasion. Different from RCC1, RCC2 also involved in immune infiltration. These analyses provided a novel insight into the identification of diagnostic biomarker.

Regulator of Chromosome Condensation (RCC1) a novel therapeutic target in pancreatic ductal adenocarcinoma drives tumor progression via the c-Myc-RCC1-Ran axis

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignancy with limited therapeutic options. Here we for the first time evaluated the role of regulator of chromosome condensation 1 (RCC1) in PDAC subsistence and drug resistance. RCC1 expression was found to be elevated in PDAC tissues in comparison with normal pancreatic tissues and was linked to poor prognosis. RCC1 silencing in a panel of PDAC cells by RNA interference and CRISPR-Cas9 resulted in reduced cellular proliferation in 2D and 3D cultures. RCC1 KD reduced migratory and clonogenic ability, enhanced apoptosis, and altered cell cycle distribution in human PDAC cells as well as cells isolated from the LSL-Kras G12D/+; LSL-Trp53 R172H/+ ;Pdx1-Cre (KPC) mouse tumors. Subcutaneous cell-derived xenografts show significantly attenuated growth of RCC1 KO tumors. Mechanistically, RCC1 knockdown resulted in disruption of subcellular Ran distribution indicating that stable nuclear Ran localization is critical for PDAC proliferation. Nuclear and cytosolic proteomic analysis revealed altered subcellular proteome in RCC1 KD KPC-tumor-derived cells. Altered cytoplasmic protein pathways include several metabolic pathways and PI3K-Akt signaling pathway. Pathways enriched in altered nuclear proteins include cell cycle, mitosis, and RNA regulation. RNA sequencing of RCC1 KO cells showed widespread transcriptional alterations. Upstream of RCC1, c-Myc activates the RCC1-Ran axis, and RCC1 KO enhances the sensitivity of PDAC cells to c-Myc inhibitors. Finally, RCC1 knockdown resulted in the sensitization of PDAC cells to Gemcitabine. Our results indicate that RCC1 is a potential therapeutic target in PDAC that warrants further clinical investigations.

RCC1 functions as a tumor facilitator in clear cell renal cell carcinoma by dysregulating cell cycle, apoptosis, and EZH2 stability

BACKGROUND

RCC1 functions as a pivotal guanine nucleotide exchange factor and was reported to be involved in mitosis, the assembly of the nuclear envelope, nucleocytoplasmic transport in cell physiological processes. Recent studies reported that RCC1 could regulate immunological pathways and promote the growth of some malignant solid tumors. However, the prognostic value and exact function of RCC1 remain unknown in patients with clear cell renal cell carcinoma (cRCC).

METHODS

The UALCAN and KM plotter portals were used to analyze the expression profile and related tumor prognosis of RCC1 in ccRCC using data from TCGA. The expression profile of RCC1 was also confirmed in clinical samples using qRT-PCR, western blotting, and immunohistochemistry. The role of RCC1 on ccRCC cells in vitro was confirmed by a series of functional assays. Animal experiments were performed to verify the suppressive effect of RCC1 knockdown on tumor growth in vivo. The correlation of RCC1 expression with that of EZH2 was explored in clinical samples using IHC. The interaction between RCC1 and EZH2 was further verified using a CO-IP assay and a protein stability assay.

RESULTS

RCC1 was upregulated in ccRCC tissues compared with normal tissues in TCGA dataset and paired clinical samples. RCC1 promoted ccRCC progression by accelerating the cell cycle and suppressing apoptosis. In addition, RCC1 could bind EZH2 and regulate its expression at the posttranscriptional level. RCC1 and EZH2 expression showed a strong correlation in clinical samples. Further investigation proved that RCC1 regulated EZH2 protein stability through the ubiquitin-proteasome pathway.

CONCLUSIONS

RCC1 could be a potential therapeutic target in ccRCC. The RCC1/EZH2 axis takes part in the development of ccRCC.

TFRC-RNA interactions show the regulation of gene expression and alternative splicing associated with IgAN in human renal tubule mesangial cells

Introduction: IgA nephropathy (IgAN) is the most common primary glomerular disease (PGD) which could progress to renal failure and is characterized by aberrant IgA immune complex deposition. Transferrin receptor1 (TFRC), an IgA receptor, is a potential RNA binding protein (RBP) which regulates expression of genes positively associated with the cell cycle and proliferation and is involved in IgAN. Molecular mechanisms by which TFRC affects IgAN development remain unclear. Methods: In this study, TFRC was overexpressed in human renal tubular mesangial cells (HRMCs) and RNA-sequencing (RNA-seq) and improved RNA immunoprecipitation sequencing (iRIP-seq) were performed. The aim was to identify potential RNA targets of TFRC at transcriptional and alternative splicing (AS) levels. Results: TFRC-regulated AS genes were enriched in mRNA splicing and DNA repair, consistent with global changes due to TFRC overexpression (TFRC-OE). Expression of TFRC-regulated genes potentially associated with IgAN, including CENPH, FOXM1, KIFC1, TOP2A, FABP4, ID1, KIF20A, ATF3, H19, IRF7, and H1-2, and with AS, CYGB, MCM7 and HNRNPH1, were investigated by RT-qPCR and iRIP-seq data analyzed to identify TFRC-bound RNA targets. RCC1 and RPPH1 were found to be TFRC-bound RNA targets involved in cell proliferation. Discussion: In conclusion, molecular TFRC targets were identified in HRMCs and TFRC found to regulate gene transcription and AS. TFRC is considered to have potential as a clinical therapeutic target.

COLD REGULATED GENE 27 and 28 Antagonize the Transcriptional Activity of the RVE8/LNK1/LNK2 Circadian Complex

Many molecular and physiological processes in plants occur at a specific time of day. These daily rhythms are coordinated in part by the circadian clock, a timekeeper that uses daylength and temperature to maintain rhythms of approximately 24 hours in various clock-regulated phenotypes. The circadian MYB-like transcription factor REVEILLE 8 (RVE8) interacts with its transcriptional coactivators NIGHT LIGHT INDUCIBLE AND CLOCK REGULATED 1 (LNK1) and LNK2 to promote the expression of evening-phased clock genes and cold tolerance factors. While genetic approaches have commonly been used to discover connections within the clock and between clock elements and other pathways, here we used affinity purification coupled with mass spectrometry to identify time-of-day-specific protein interactors of the RVE8-LNK1/LNK2 complex in Arabidopsis (Arabidopsis thaliana). Among the interactors of RVE8/LNK1/LNK2 were COLD REGULATED GENE 27 (COR27) and COR28, which coprecipitated in an evening-specific manner. In addition to COR27 and COR28, we found an enrichment of temperature-related interactors that led us to establish a previously uncharacterized role for LNK1 and LNK2 in temperature entrainment of the clock. We established that RVE8, LNK1, and either COR27 or COR28 form a tripartite complex in yeast (Saccharomyces cerevisiae) and that the effect of this interaction in planta serves to antagonize transcriptional activation of RVE8 target genes, potentially through mediating RVE8 protein degradation in the evening. Together, these results illustrate how a proteomic approach can be used to identify time-of-day-specific protein interactions. Discovery of the RVE8-LNK-COR protein complex indicates a previously unknown regulatory mechanism for circadian and temperature signaling pathways.

Synergistic effect of HDAC inhibitor Chidamide with Cladribine on cell cycle arrest and apoptosis by targeting HDAC2/c-Myc/RCC1 axis in acute myeloid leukemia

BACKGROUND

More effective targeted therapy and new combination regimens are needed for Acute myeloid leukemia (AML), owing to the unsatisfactory long-term prognosis of the disease. Here, we investigated the synergistic effect and the mechanism of a histone deacetylase inhibitor, Chidamide in combination with Cladribine, a purine nucleoside antimetabolite analog in the disease.

METHODS

Cell counting kit-8 assays and Chou-Talalay's combination index were used to examine the synergistic effect of Chidamide and Cladribine on AML cell lines (U937, THP-1, and MV4-11) and primary AML cells. PI and Annexin-V/PI assays were used to detect the cell cycle effect and apoptosis effect, respectively. Global transcriptome analysis, RT-qPCR, c-MYC Knockdown, western blotting, co-immunoprecipitation, and chromatin immunoprecipitation assays were employed to explore the molecule mechanisms.

RESULTS

The combination of Chidamide with Cladribine showed a significant increase in cell proliferation arrest, the G0/G1 phase arrest, and apoptosis compared to the single drug control in AML cell lines along with upregulated p21^Waf1/Cip1 expression and downregulated CDK2/Cyclin E2 complex, and elevated cleaved caspase-9, caspase-3, and PARP. The combination significantly suppresses the c-MYC expression in AML cells, and c-MYC knockdown significantly increased the sensitivity of U937 cells to the combination compared to single drug control. Moreover, we observed HDAC2 interacts with c-Myc in AML cells, and we further identified that c-Myc binds to the promoter region of RCC1 that also could be suppressed by the combination through c-Myc-dependent. Consistently, a positive correlation of RCC1 with c-MYC was observed in the AML patient cohort. Also, RCC1 and HDAC2 high expression are associated with poor survival in AML patients. Finally, we also observed the combination significantly suppresses cell growth and induces the apoptosis of primary cells in AML patients with AML1-ETO fusion, c-KIT mutation, MLL-AF6 fusion, FLT3-ITD mutation, and in a CMML-BP patient with complex karyotype.

CONCLUSIONS

Our results demonstrated the synergistic effect of Chidamide with Cladribine on cell growth arrest, cell cycle arrest, and apoptosis in AML and primary cells with genetic defects by targeting HDAC2/c-Myc/RCC1 signaling in AML. Our data provide experimental evidence for the undergoing clinical trial (Clinical Trial ID: NCT05330364) of Chidamide plus Cladribine as a new potential regimen in AML.

Ran GTPase and Its Importance in Cellular Signaling and Malignant Phenotype

Ran is a member of the Ras superfamily of proteins, which primarily regulates nucleocytoplasmic trafficking and mediates mitosis by regulating spindle formation and nuclear envelope (NE) reassembly. Therefore, Ran is an integral cell fate determinant. It has been demonstrated that aberrant Ran expression in cancer is a result of upstream dysregulation of the expression of various factors, such as osteopontin (OPN), and aberrant activation of various signaling pathways, including the extracellular-regulated kinase/mitogen-activated protein kinase (ERK/MEK) and phosphatidylinositol 3-kinase/Protein kinase B (PI3K/Akt) pathways. In vitro, Ran overexpression has severe effects on the cell phenotype, altering proliferation, adhesion, colony density, and invasion. Therefore, Ran overexpression has been identified in numerous types of cancer and has been shown to correlate with tumor grade and the degree of metastasis present in various cancers. The increased malignancy and invasiveness have been attributed to multiple mechanisms. Increased dependence on Ran for spindle formation and mitosis is a consequence of the upregulation of these pathways and the ensuing overexpression of Ran, which increases cellular dependence on Ran for survival. This increases the sensitivity of cells to changes in Ran concentration, with ablation being associated with aneuploidy, cell cycle arrest, and ultimately, cell death. It has also been demonstrated that Ran dysregulation influences nucleocytoplasmic transport, leading to transcription factor misallocation. Consequently, patients with tumors that overexpress Ran have been shown to have a higher malignancy rate and a shorter survival time compared to their counterparts.

Systematic pan-cancer analysis on the expression and role of regulator of chromatin condensation 1/small nucleolar RNA host gene 3/small nucleolar RNA host gene 12

Regulator of chromatin condensation 1 (RCC1) is the major guanine nucleotide exchange factor of RAN GTPase, which plays a key role in various biological processes such as cell cycle and DNA damage repair. Small nucleolar RNA host gene 3 (SNHG3) and small nucleolar RNA host gene12 are long-stranded non-coding RNAs (lncRNAs) and are located on chromatin very close to the sequence of Regulator of chromatin condensation 1. Many studies have shown that they are aberrantly expressed in tumor tissues and can affect the proliferation and viability of cancer cells. Although the effects of Regulator of chromatin condensation 1/small nucleolar RNA host gene 3/small nucleolar RNA host gene12 on cellular activity have been reported, respectively, their overall analysis on the pan-cancer level has not been performed. Here, we performed a comprehensive analysis of Regulator of chromatin condensation 1/small nucleolar RNA host gene 3/small nucleolar RNA host gene12 in 33 cancers through the Cancer Genome Atlas and Gene Expression Database. The results showed that Regulator of chromatin condensation 1/small nucleolar RNA host gene 3/small nucleolar RNA host gene12 were highly expressed in a variety of tumor tissues compared to normal tissues. The expression of Regulator of chromatin condensation 1/small nucleolar RNA host gene 3/small nucleolar RNA host gene12 in BRCA, LGG and LIHC was associated with TP53 mutations. In addition, Regulator of chromatin condensation 1/small nucleolar RNA host gene 3/small nucleolar RNA host gene12 expression was closely associated with the prognosis of patients with multiple tumors. Immunocorrelation analysis indicated that Regulator of chromatin condensation 1/small nucleolar RNA host gene 3/small nucleolar RNA host gene12 showed a correlation with multiple immune cell infiltration. The results of enrichment analysis suggested that Regulator of chromatin condensation 1/small nucleolar RNA host gene 3/small nucleolar RNA host gene12 was involved in the regulation of cell cycle, apoptosis and other pathways. We found that these effects were mainly mediated by Regulator of chromatin condensation 1, while the trend of small nucleolar RNA host gene 3/small nucleolar RNA host gene12 regulation was also consistent with regulator of chromatin condensation 1. The important role played by Regulator of chromatin condensation 1 in tumor diseases was further corroborated by the study of adjacent lncRNAs.These findings provide new and comprehensive insights into the role of Regulator of chromatin condensation 1/small nucleolar RNA host gene 3/small nucleolar RNA host gene12 in tumor development and show their potential as clinical monitoring and therapy.

Identification of RCC1-LCK as a novel fusion gene in pediatric erythroid sarcoma

Erythroid sarcoma is a very rare subtype of myeloid sarcoma with undetermined biological features. Here, we present an infant with a multifocal erythroid sarcoma, diagnosed because the tumor cells were positive for glycophorin A. After acute myeloid leukemia-oriented chemotherapy and surgical resection followed by cord blood transplantation, he has successfully maintained complete remission without any late effects. Total transcriptome analysis of the tumor identified a novel fusion gene, RCC1-LCK, and high LCK expression levels, suggesting that LCK overexpression was involved in leukemogenesis in this case.

SaRCC1, a Regulator of Chromosome Condensation 1 (RCC1) Family Protein Gene from Spartina alterniflora, Negatively Regulates Salinity Stress Tolerance in Transgenic Arabidopsis

A regulator of chromosome condensation 1 (RCC1) family protein has been functionally characterized to be involved in various cellular processes. In this study, one RCC1 gene named SaRCC1 was cloned from the full-length cDNA library of Spartinaalterniflora. The open reading frame (ORF) of SaRCC1 was 1440 bp, and it encoded 479 amino acids with a calculated molecular mass of 51.65 kDa. Multiple amino acid sequence alignments showed that SaRCC1 had high identity with other plant RCC1s, and the phylogenetic analysis indicated that SaRCC1 had a closer affinity to Zea mays RCC1 family protein (ZmRCC1). SaRCC1 gene was induced under salt stress conditions, and its encoded protein was located in peroxisome. In order to further investigate the function of SaRCC1, transgenic Arabidopsis plants ectopically both sense-overexpressing and antisense-overexpressing SaRCC1 were generated. SaRCC1-overexpressing lines exhibited an increased salt and ABA hypersensitivity and reduced resistance to salinity stress. On the other hand, the transcripts of some stress-responsive genes in the SaRCC1 transgenic plants were affected in response to salinity stress. Our results provide evidence for the involvement of SaRCC1, negatively regulating salt stress responses by affecting stress-related gene expression in Arabidopsis.

The intricate roles of RCC1 in normal cells and cancer cells

RCC1 (regulator of chromosome condensation 1) is a highly conserved chromatin-binding protein and the only known guanine-nucleotide exchange factor of Ran (a nuclear Ras homolog). RCC1 plays an essential role in the regulation of cell cycle-related activities such as nuclear envelope formation, nuclear pore complex and spindle assembly, and nucleocytoplasmic transport. Over the last decade, increasing evidence has emerged highlighting the potential relevance of RCC1 to carcinogenesis, especially cervical, lung, and breast cancer. In this review, we briefly discuss the roles of RCC1 in both normal and tumor cells based on articles published in recent years, followed by a brief overview of future perspectives in the field.

Variant identification in BARD1, PRDM9, RCC1, and RECQL in patients with ovarian cancer by targeted next-generation sequencing of DNA pools

Several ovarian cancer susceptibility genes have been discovered, but more are likely to exist. In this study, we aimed to analyze knowledge-based selected genes, i.e., BARD1, PRDM9, RCC1, and RECQL, in which pathogenic germline variants have been reported in patients with breast and/or ovarian cancer. As deep sequencing of DNA samples remains costly, targeted next-generation sequencing of DNA pools was utilized to screen the exons of BARD1, PRDM9, RCC1, and RECQL in ~400 Polish ovarian cancer cases. 25 pools of 16 samples (including several duplicated samples with known variants) were sequenced on the NovaSeq6000 and analyzed with SureCall (Agilent) application. The set of variants was filtrated to exclude spurious variants, and, subsequently, the identified rare genetic variants were validated using Sanger sequencing. No pathogenic mutation was found within the analyzed cohort of ovarian cancer patients. Validation genotyping of filtered rare silent and missense variants revealed that the majority of them were true alterations, especially those with a higher mutation quality value. The high concordance (R2=0.95) of population allele frequency for 44 common SNPs in the European control population (gnomAD) and our experiment confirmed the reliability of pooled sequencing. Mutations in BARD1, PRDM9, RCC1, and RECQL do not contribute substantially to the risk of ovarian cancer. Pooled DNA sequencing is a cost-effective and reliable method for the initial screening of candidate genes; however, it still requires validation of identified rare variants.

CmRCC1 Gene From Pumpkin Confers Cold Tolerance in Tobacco by Modulating Root Architecture and Photosynthetic Activity

Low-temperature stress is the main limiting factor of cucurbit crop cultivation as it affects crop yield and quality. The identification of genes involved in cold tolerance is a crucial aspect of pumpkin rootstock breeding. Here, we examined the function of a pumpkin Regulator of Chromosome Condensation 1 (CmRCC1) gene in the root development and cold stress responses of tobacco (Nicotiana benthamiana). CmRCC1 expression was differentially induced in pumpkin root, stem, and leaf under cold stress. Transient transformation showed that CmRCC1 is located in the nucleus. CmRCC1 overexpression in tobacco increased the gravitropic set-point angle in lateral roots, as well as root diameter and volume. The expression of auxin polar transport factors, PIN1 and PIN3, decreased and increased in CmRCC1-overexpressed plants, respectively. Yeast two-hybrid verification and luciferase complementation imaging assay showed that CmRCC1 interacts with CmLAZY1. Furthermore, the decreases in maximum quantum yield of PS II, the effective quantum yield of PS II, and electron transfer rate and the increases in quantum yield of nonregulated energy dissipation and malondialdehyde content were compromised in transgenic plants compared with wild-type plants under cold stress. The results suggest that CmRCC1 plays an important role in the regulation of root architecture and positively modulates cold tolerance.

Integrative and Comprehensive Pancancer Analysis of Regulator of Chromatin Condensation 1 (RCC1)

Regulator of Chromatin Condensation 1 (RCC1) is the only known guanine nucleotide exchange factor that acts on the Ras-like G protein Ran and plays a key role in cell cycle regulation. Although there is growing evidence to support the relationship between RCC1 and cancer, detailed pancancer analyses have not yet been performed. In this genome database study, based on The Cancer Genome Atlas, Genotype-Tissue Expression and Gene Expression Omnibus databases, the potential role of RCC1 in 33 tumors' entities was explored. The results show that RCC1 is highly expressed in most human malignant neoplasms in contrast to healthy tissues. RCC1 expression is closely related to the prognosis of a broad variety of tumor patients. Enrichment analysis showed that some tumor-related pathways such as "cell cycle" and "RNA transport" were involved in the functional mechanism of RCC1. In particular, the conducted analysis reveals the relation of RCC1 to multiple immune checkpoint genes and suggests that the regulation of RCC1 is closely related to tumor infiltration of cancer-associated fibroblasts and CD8⁺ T cells. Coherent data demonstrate the association of RCC1 with the tumor mutation burden and microsatellite instability in various tumors. These findings provide new insights into the role of RCC1 in oncogenesis and tumor immunology in various tumors and indicate its potential as marker for therapy prognosis and targeted treatment strategies.