Phosphorylation of nucleophosmin at threonine 234/237 is associated with HCC metastasis

Histone Chaperones and Digestive Cancer: A Review of the Literature

BACKGROUND

The global burden of digestive cancer is expected to increase. Therefore, crucial for the prognosis of patients with these tumors is to identify early diagnostic markers or novel therapeutic targets. There is accumulating evidence connecting histone chaperones to the pathogenesis of digestive cancer. Histone chaperones are now broadly defined as a class of proteins that bind histones and regulate nucleosome assembly. Recent studies have demonstrated that multiple histone chaperones are aberrantly expressed and have distinct roles in digestive cancers.

OBJECTIVE

The purpose of this review is to present the current evidence regarding the role of histone chaperones in digestive cancer, particularly their mechanism in the development and progression of esophageal, gastric, liver, pancreatic, and colorectal cancers. In addition, the prognostic significance of particular histone chaperones in patients with digestive cancer is discussed.

METHODS

According to PRISMA guidelines, we searched the PubMed, Embase, and MEDLINE databases to identify studies on histone chaperones and digestive cancer from inception until June 2022.

RESULTS

A total of 104 studies involving 21 histone chaperones were retrieved.

CONCLUSIONS

This review confirms the roles and mechanisms of selected histone chaperones in digestive cancer and suggests their significance as potential prognostic biomarkers and therapeutic targets. However, due to their non-specificity, more research on histone chaperones should be conducted in the future to elucidate novel strategies of histone chaperones for prognosis and treatment of digestive cancer.

Proteomic analysis reveals USP7 as a novel regulator of palmitic acid-induced hepatocellular carcinoma cell death

Nutrient surplus and consequent free fatty acid accumulation in the liver cause hepatosteatosis. The exposure of free fatty acids to cultured hepatocyte and hepatocellular carcinoma cell lines induces cellular stress, organelle adaptation, and subsequent cell death. Despite many studies, the mechanism associated with lipotoxicity and subsequent cell death still remains poorly understood. Here, we have used the proteomics approach to circumvent the mechanism for lipotoxicity using hepatocellular carcinoma cells as a model. Our quantitative proteomics data revealed that ectopic lipids accumulation in cells severely affects the ubiquitin-proteasomal system. The palmitic acid (PA) partially lowered the expression of deubiquitinating enzyme USP7 which subsequently destabilizes p53 and promotes mitotic entry of cells. Our global phosphoproteomics analysis also provides strong evidence of an altered cell cycle checkpoint proteins' expression that abrogates early G2/M checkpoints recovery with damaged DNA and induced mitotic catastrophe leading to hepatocyte death. We observe that palmitic acid prefers apoptosis-inducing factor (AIF) mediated cell death by depolarizing mitochondria and translocating AIF to the nucleus. In summary, the present study provides evidence of PA-induced hepatocellular death mediated by deubiquitinase USP7 downregulation and subsequent mitotic catastrophe.

Palbociclib Promotes Dephosphorylation of NPM/B23 at Threonine 199 and Inhibits Endometrial Cancer Cell Growth

Endometrial cancer incidence rates are growing, especially in countries with rapid socioeconomic transitions. Despite recent advances in chemotherapy, hormone therapy, and targeted therapy, advanced/recurrent disease remains a clinical challenge. Palbociclib—a selective inhibitor of cyclin-dependent kinases (CDK) 4/6—has therapeutic potential against estrogen receptor (ER)-positive and HER2-negative breast cancer. However, the question as to whether it can be clinically useful in endometrial cancer remains open. Here, we show that combined treatment with palbociclib and megesterol acetate exerts synergistic antiproliferative effects against endometrial cancer cells. Treatment of cancer cells with palbociclib suppressed NPM/B23 phosphorylation at threonine 199 (Thr199). We further demonstrated that CDK6 acts as a NPM/B23 kinase. Palbociclib-induced NPM/B23 dephosphorylation sensitized endometrial cancer cells to megesterol acetate through the upregulation of ERα expression. Immunohistochemistry revealed an overexpression of phospho-NPM/B23 (Thr199) in human endometrial cancer, and phospho-NPM/B23 (Thr199) expression levels were inversely associated with Erα in clinical specimen. In a xenograft tumor model, the combination of palbociclib and megesterol acetate successfully inhibited tumor growth. Taken together, our data indicate that palbociclib promoted NPM/B23 dephosphorylation at Thr199—an effect mediated by disruption of CDK6 kinase activity. We conclude that palbociclib holds promise for the treatment of endometrial cancer when used in combination with megesterol acetate.

Nucleophosmin in leukemia: Consequences of anchor loss

Nucleophosmin (NPM), one of the most abundant nucleolar proteins, has crucial functions in ribosome biogenesis, cell cycle control, and DNA-damage repair. In human cells, NPM occurs mainly in oligomers. It functions as a chaperone, undergoes numerous interactions and forms part of many protein complexes. Although NPM role in carcinogenesis is not fully elucidated, a variety of tumor suppressor as well as oncogenic activities were described. NPM is overexpressed, fused with other proteins, or mutated in various tumor types. In the acute myeloid leukemia (AML), characteristic mutations in NPM1 gene, leading to modification of NPM C-terminus, are the most frequent genetic aberration. Although multiple mutation types of NPM are found in AML, they are all characterized by aberrant cytoplasmic localization of the mutated protein. In this review, current knowledge of the structure and function of NPM is presented in relation to its interaction network, in particular to the interaction with other nucleolar proteins and with proteins active in apoptosis. Possible molecular mechanisms of NPM mutation-driven leukemogenesis and NPM therapeutic targeting are discussed. Finally, recent findings concerning the immunogenicity of the mutated NPM and specific immunological features of AML patients with NPM mutation are summarized.

O-GlcNAc-induced nuclear translocation of hnRNP-K is associated with progression and metastasis of cholangiocarcinoma

O‐GlcNAcylation is a key post‐translational modification that modifies the functions of proteins. Associations between O‐GlcNAcylation, shorter survival of cholangiocarcinoma (CCA) patients, and increased migration/invasion of CCA cell lines have been reported. However, the specific O‐GlcNAcylated proteins (OGPs) that participate in promotion of CCA progression are poorly understood. OGPs were isolated from human CCA cell lines, KKU‐213 and KKU‐214, using a click chemistry‐based enzymatic labeling system, identified using LC‐MS/MS, and searched against an OGP database. From the proteomic analysis, a total of 21 OGPs related to cancer progression were identified, of which 12 have not been previously reported. Among these, hnRNP‐K, a multifaceted RNA‐ and DNA‐binding protein known as a pre‐mRNA‐binding protein, was one of the most abundantly expressed, suggesting its involvement in CCA progression. O‐GlcNAcylation of hnRNP‐K was further verified by anti‐OGP/anti‐hnRNP‐K immunoprecipitations and sWGA pull‐down assays. The perpetuation of CCA by hnRNP‐K was evaluated using siRNA, which revealed modulation of cyclin D1, XIAP, EMT markers, and MMP2 and MMP7 expression. In native CCA cells, hnRNP‐K was primarily localized in the nucleus; however, when O‐GlcNAcylation was suppressed, hnRNP‐K was retained in the cytoplasm. These data signify an association between nuclear accumulation of hnRNP‐K and the migratory capabilities of CCA cells. In human CCA tissues, expression of nuclear hnRNP‐K was positively correlated with high O‐GlcNAcylation levels, metastatic stage, and shorter survival of CCA patients. This study demonstrates the significance of O‐GlcNAcylation on the nuclear translocation of hnRNP‐K and its impact on the progression of CCA.

Comparative proteomics of side population cells derived from human hepatocellular carcinoma cell lines with varying metastatic potentials

Metastasis and recurrence following surgery are major reasons for the high mortality rate and poor prognosis associated with hepatocellular carcinoma (HCC). Cancer stem cells (CSCs) are thought to be able to cause cancer, and to be the primary cause of tumor recurrence and metastasis. The underlying mechanisms of the metastatic potential of CSCs is poorly understood. In the present study, side population (SP) cells were isolated from 4 HCC cell lines, and their self-renewal and migratory abilities were compared. The results demonstrate that SP cells from different cell lines exhibited similar self-renewal abilities but different metastatic potentials. Furthermore, the overall proteomes of the SP cells were systematically quantified. This revealed 11 and 19 differentially expressed proteins (DEPs), upregulated and downregulated, respectively, associated with increased metastatic potential. These proteins were involved in the ‘regulation of mRNA processing’ and ‘cytoskeleton organization’ biological processes. The majority of the proteins were involved in ‘cell proliferation’, ‘migration’ and ‘invasion of cancer’, and may promote HCC metastasis in a synergistic manner. The AKT and nuclear factor-κB signaling pathways may contribute to the regulation of HCC metastasis through regulating the DEPs in SP cells. To the best of our knowledge, the present study is the first to demonstrate the overall proteome difference among SP cells from the different HCC cell lines with different metastatic potentials. The present study provides novel information regarding the metastatic potential of CSCs, which will facilitate further investigation of the topic.

Sulfatase-1 overexpression indicates poor prognosis in urothelial carcinoma of the urinary bladder and upper tract

Urothelial carcinoma (UC), arising from the urothelium of the urinary tract, can occur in the upper (UTUC) and the urinary bladder (UBUC). A representative molecular aberration for UC characteristics and prognosis remains unclear. Data mining of Gene Expression Omnibus focusing on UBUC, we identified sulfatase-1 (SULF1) upregulation is associated with UC progression. SULF1 controls the sulfation status of heparan sulfate proteoglycans and plays a role in tumor growth and metastasis, while its role is unexplored in UC. To first elucidate the clinical significance of SULF1 transcript expression, real-time quantitative RT-PCR was performed in a pilot study of 24 UTUC and 24 UBUC fresh samples. We identified that increased SULF1 transcript abundance was associated with higher primary tumor (pT) status. By testing SULF1 immunoexpression in independent UTUC and UBUC cohorts consisted of 340 and 295 cases, respectively, high SULF1 expression was significantly associated with advanced pT and nodal status, higher histological grade and presence of vascular invasion in both UTUC and UBUC. In multivariate survival analyses, high SULF1 expression was independently associated with worse DSS (UTUC hazard ratio [HR] = 3.574, P < 0.001; UBUC HR = 2.523, P = 0.011) and MeFS (UTUC HR = 3.233, P < 0.001; UBUC HR = 1.851, P = 0.021). Furthermore, depletion of SULF1 expression by using RNA interference leaded to impaired cell proliferative, migratory, and invasive abilities in vitro. In addition, we further confirmed oncogenic role of SULF1 with gain-of function experiments. In conclusion, our findings implicate the oncogenic role of SULF1 expression in UC, suggesting SULF1 as a prognostic and therapeutic target of UC.

MCM10 overexpression implicates adverse prognosis in urothelial carcinoma

Urothelial carcinoma (UC) occurs in the upper urinary tract (UTUC) and the urinary bladder (UBUC). The molecular pathogenesis of UC has not been fully elucidated. Through data mining of a published transcriptome of UBUC (GSE31684), we identified Minichromosome Maintenance Complex Component 2 (MCM2) and MCM10 as the two most significantly upregulated genes in UC progression among the MCM gene family, the key factors for the initiation of DNA replication. To validate the clinical significance of MCM2 and MCM10, immunohistochemistry, evaluated by H-score, was used in a pilot study of 50 UTUC and 50 UBUC samples. Only a high expression level of MCM10 predicted worse disease-specific survival (DSS) and inferior metastasis-free survival (MeFS) for both UTUC and UBUC. Correspondingly, evaluation of MCM10 mRNA expression in 36 UTUCs and 30 UBUCs showed significantly upregulated levels in high stage UC, suggesting its role in tumor progression. Evaluation of 340 UTUC and 296 UBUC tissue samples, respectively, demonstrated that high MCM10 immunoexpression was significantly associated with advanced primary tumors, nodal status, and the presence of vascular invasion in both groups of UCs. In multivariate Cox regression analyses, adjusted for standard clinicopathological features, MCM10 overexpression was independently associated with DSS (UTUC hazard ratio [HR]=2.401, P = 0.013; UBUC HR=4.323, P=0.001) and with MeFS (UTUC HR=3.294, P<0.001; UBUC HR=1.972, P=0.015). In vitro, knockdown of MCM10 gene significantly suppressed cell proliferation in both J82 and TCCSUP cells. In conclusion, MCM10 overexpression was associated with unfavorable clinicopathological characteristics and independent negative prognostic effects, justifying its potential theranostic value in UC.

Assessment of lymphocyte proliferation for diagnostic purpose: Comparison of CFSE staining, Ki-67 expression and 3H-thymidine incorporation

The capability of lymphocytes to respond to antigenic or mitogenic stimulation is an important feature in the diagnosis of various immunodeficiencies and immune disorders. We used large cohorts of both immune compromised patients and healthy controls to measure lymphocyte proliferations by means of three methods: CFSE staining, Ki-67 expression and ³H-thymidine incorporation. The advantages and disadvantages of each method was then evaluated for use in routine clinical diagnostic. The statistical analysis was performed between the outcomes and the correlation between all three methods was computed. CFSE and Ki-67 assay correlated well with the r=0.767, correlation between Ki-67 expression and ³H-thymidine incorporation was 0.546 and correlation between CFSE staining and ³H-thymidine incorporation was 0.337. The differences between these three methods concerning complexity, sensitivity and reliability as well as the financial aspects are discussed hereafter. CFSE and its analogues provide the cheapest and reasonable choice for measuring lymphocyte proliferation, while Ki-67 represents a more expensive, but more sensitive and robust method. The original ³H-thymidine assay does not bring any advantages and cannot compare to the competition presented by modern flow cytometric methods available today.