A Genome-Wide Association Study Reveals Two Genetic Markers for Chondromalacia

OBJECTIVE

It is unknown why some athletes develop chondromalacia and others do not, even when accounting for similar workloads between individuals. Genetic differences between individuals may be a contributing factor. The purpose of this work was to screen the entire genome for genetic markers associated with chondromalacia.

DESIGN

Genome-wide association (GWA) analyses were performed utilizing data from the Kaiser Permanente Research Board (KPRB) and the UK Biobank. Chondromalacia cases were identified based on electronic health records from KPRB and UK Biobank. GWA analyses from both cohorts were tested for chondromalacia using a logistic regression model adjusting for sex, height, weight, age of enrollment, and race/ethnicity using allele counts for single-nucleotide polymorphisms (SNPs). The data from the 2 GWA studies (KPRB and UK Biobank) were combined in a meta-analysis.

RESULTS

There were a total of 3,872 combined cases of chondromalacia from the KPRB and the UK Biobank cohorts. Genome-wide significant associations with chondromalacia were found for rs144449054 in the ARHGAP15 gene (OR = 3.70 [2.32-5.90]; P = 1.4 × 10^-8) and rs188900564 in the MAGEC2 (OR = 2.07 [1.61-2.65]; P = 3.7 × 10^-9).

CONCLUSIONS

Genetic markers in ARHGAP15 and MAGEC2 appear to be associated with chondromalacia and are potential risk factors that deserve further validation regarding molecular mechanisms.

Generation of TRIM28 Knockout K562 Cells by CRISPR/Cas9 Genome Editing and Characterization of TRIM28-Regulated Gene Expression in Cell Proliferation and Hemoglobin Beta Subunits

TRIM28 is a scaffold protein that interacts with DNA-binding proteins and recruits corepressor complexes to cause gene silencing. TRIM28 contributes to physiological functions such as cell growth and differentiation. In the chronic myeloid leukemia cell line K562, we edited TRIM28 using CRISPR/Cas9 technology, and the complete and partial knockout (KO) cell clones were obtained and confirmed using quantitative droplet digital PCR (ddPCR) technology. The amplicon sequencing demonstrated no off-target effects in our gene editing experiments. The TRIM28 KO cells grew slowly and appeared red, seeming to have a tendency towards erythroid differentiation. To understand how TRIM28 controls K562 cell proliferation and differentiation, transcriptome profiling analysis was performed in wild-type and KO cells to identify TRIM28-regulated genes. Some of the RNAs that encode the proteins regulating the cell cycle were increased (such as p21) or decreased (such as cyclin D2) in TRIM28 KO cell clones; a tumor marker, the MAGE (melanoma antigen) family, which is involved in cell proliferation was reduced. Moreover, we found that knockout of TRIM28 can induce miR-874 expression to downregulate MAGEC2 mRNA via post-transcriptional regulation. The embryonic epsilon-globin gene was significantly increased in TRIM28 KO cell clones through the downregulation of transcription repressor SOX6. Taken together, we provide evidence to demonstrate the regulatory network of TRIM28-mediated cell growth and erythroid differentiation in K562 leukemia cells.

Identification of MAGEC2/CT10 as a High Calcium-Inducible Gene in Triple-Negative Breast Cancer

The expression of the melanoma/cancer-testis antigen MAGEC2/CT10 is restricted to germline cells, but like most cancer-testis antigens, it is frequently upregulated in advanced breast tumors and other malignant tumors. However, the physiological cues that trigger the expression of this gene during malignancy remain unknown. Given that malignant breast cancer is often associated with skeletal metastasis and co-morbidities such as cancer-induced hypercalcemia, we evaluated the effect of high Ca²⁺ on the calcium-sensing receptor (CaSR) and potential mechanisms underlying the survival of triple-negative breast cancer (TNBC) cells at high Ca²⁺. We show that chronic exposure of TNBC cells to high Ca²⁺ decreased the sensitivity of CaSR to Ca²⁺ but stimulated tumor cell growth and migration. Furthermore, high extracellular Ca²⁺ also stimulated the expression of early response genes such as FOS/FOSB and a unique set of genes associated with malignant tumors, including MAGEC2. We further show that the MAGEC2 proximal promoter is Ca²⁺ inducible and that FOS/FOSB binds to this promoter in a Ca²⁺- dependent manner. Finally, downregulation of MAGEC2 strongly inhibited the growth of TNBC cells in vitro. These data suggest for the first time that MAGEC2 is a high Ca²⁺ inducible gene and that aberrant expression of MAGEC2 in malignant TNBC tissues is at least in part mediated by an increase in circulating Ca²⁺via the AP-1 transcription factor.

MAGEC2 Correlates With Unfavorable Prognosis And Promotes Tumor Development In HCC Via Epithelial-Mesenchymal Transition

Purpose

Although MAGEC2 was first cloned from a human hepatocellular carcinoma (HCC) cDNA library by serum screening, the detailed attributes of MAGEC2 in HCC have rarely been elucidated.

Patients and methods

In this study, The Cancer Genome Atlas (TCGA) and the Gene Expression Omnibus (GEO) databases were consulted to analyse the expression of MAGEC2 mRNA in liver cancer. Immunohistochemistry (IHC) analysis was performed to detect MAGEC2 expression in HCC, and the relationship between MAGEC2 expression and the clinicopathological characteristics of HCC patients was evaluated. Then, we employed the short hairpin (sh)RNA-mediated knockdown of MAGEC2 in HCC cell lines to explore the function of MAGEC2 in HCC development. Finally, the expression of epithelial-mesenchymal transition (EMT) markers in HCC xenografts and clinical samples was investigated.

Results

The results showed a remarkably higher level of MAGEC2 expression in HCC tissues than in noncancerous tissues, and MAGEC2 expression could be used as an independent prognostic factor for overall survival in HCC. Moreover, sh-MAGEC2 inhibited a series of HCC malignant behaviours both in vitro and in vivo. Finally, decreased MAGEC2 expression and low levels of EMT markers were detected in sh-MAGEC2 xenografts, while increased MAGEC2 expression and high levels of EMT markers were observed in invasive and metastatic HCC samples.

Conclusion

Taken together, our data imply that MAGEC2 is a novel prognostic marker for HCC and that MAGEC2 significantly promotes HCC tumourigenesis by inducing EMT. Targeting MAGEC2 may provide a promising therapeutic strategy for HCC treatment.

Post-transcriptional regulation of cancer/testis antigen MAGEC2 expression by TRIM28 in tumor cells

BACKGROUND

Cancer/testis antigen MAGEC2 (also known as HCA587) is highly expressed in a wide variety of tumors and plays an active role in promoting growth and metastasis of tumor cells. However, little is known for the regulation of MAGEC2 expression in cancer cells.

METHODS

Western blotting and quantitative RT-PCR were performed to analyze MAGEC2 expression. Co-immunoprecipitation assay was applied for detecting the endogenous interaction of MAGEC2 and TRIM28 in tumor cells. Overexpression and knockdown assays were used to examine the effects of TRIM28 on the expression of MAGEC2 protein. Immunohistochemistry (IHC) staining was performed in hepatocellular carcinoma patients to evaluate the association between the expression of MAGEC2 and TRIM28. Proteasome inhibitors MG132 or PS-341 and lysosome inhibitor Chloroquine (CQ) were used to inhibit proteasomal or lysosomal-mediated protein degradation respectively.

RESULTS

We demonstrate that MAGEC2 interacts with TRIM28 in melanoma cells and MAGEC2 expression in tumor cells depends on the expression of TRIM28. The expression level of MAGEC2 protein was significantly reduced when TRIM28 was depleted in tumor cells, and no changes were observed in MAGEC2 mRNA level. Furthermore, expression levels of MAGEC2 and TRIM28 are positively correlated in MAGEC2-positive human hepatocellular carcinoma tissues (p = 0.0011). Mechanistic studies indicate that the regulatory role of TRIM28 on MAGEC2 protein expression in tumor cells depends on proteasome-mediated pathway.

CONCLUSIONS

Our findings show that TRIM28 is necessary for MAGEC2 expression in cancer cells, and TRIM28 may serve as a new potential target for immunotherapy of cancer.

Study on Attenuating Angiogenesis and Epithelial-Mesenchymal Transition (EMT) of Non-Small Cell Lung Carcinoma (NSCLC) by Regulating MAGEC2

OBJECTIVE

To investigate the role of MAGE family member C2 in angiogenesis and epithelial-mesenchymal transition of non-small cell lung carcinoma.

METHODS

The Cancer Genome Atlas data set was analyzed to filter the highly expressed gene melanoma antigen family C2 in non-small cell lung carcinoma. Quantitative reverse transcription-polymerase chain reaction was performed to verify the overexpression of melanoma antigen family C2 in non-small cell lung carcinoma cell lines. Melanoma antigen family C2 complementary DNA and short hairpin RNA (shRNA) were transfected into SK-MES-1 cells to regulate melanoma antigen family C2 expression. Cell Counting Kit-8 assay, flow cytometry, wound healing assay, and Transwell assay were performed to investigate the effect of melanoma antigen family C2 on proliferation, apoptosis, migration, and invasion of SK-MES-1 cell line. Western blot was used to detect the expression of epithelial-mesenchymal transition markers. Enzyme-linked immunosorbent assay was performed to investigate the secretion of vascular endothelial growth factor, and tube formation assay was conducted to explore the effect of melanoma antigen family C2 on angiogenesis ability of the tumor. Tumor xenograft on nude mice and immunohistochemical/hematoxylin and eosin staining were also performed to detect the influence of melanoma antigen family C2 on growth and metastasis of non-small cell lung carcinoma cells.

RESULTS

Melanoma antigen family C2 was highly expressed in non-small cell lung carcinoma cells; melanoma antigen family C2 promoted the expression of epithelial-mesenchymal transition-related proteins as well as enhance the secretion of vascular endothelial growth factor and promote angiogenesis; melanoma antigen family C2 promoted proliferation, migration, and invasion and suppressed apoptosis of non-small cell lung carcinoma cells. It could also facilitate growth and metastasis of non-small cell lung carcinoma in vivo.

CONCLUSION

Melanoma antigen family C2 was a critical factor of angiogenesis and epithelial-mesenchymal transition in non-small cell lung carcinoma.

Antibodies Against Immune Checkpoint Molecules Restore Functions of Tumor-Infiltrating T Cells in Hepatocellular Carcinomas

BACKGROUND & AIMS

Ligand binding to inhibitory receptors on immune cells, such as programmed cell death 1 (PD-1) and cytotoxic T-lymphocyte associated protein 4 (CTLA4), down-regulates the T-cell-mediated immune response (called immune checkpoints). Antibodies that block these receptors increase antitumor immunity in patients with melanoma, non-small-cell lung cancer, and renal cell cancer. Tumor-infiltrating CD4⁺ and CD8⁺ T cells in patients with hepatocellular carcinoma (HCC) have been found to be functionally compromised. We analyzed HCC samples from patients to determine if these inhibitory pathways prevent T-cell responses in HCCs and to find ways to restore their antitumor functions.

METHODS

We collected HCC samples from 59 patients who underwent surgical resection from November 2013 through May 2017, along with tumor-free liver tissues (control tissues) and peripheral blood samples. We isolated tumor-infiltrating lymphocytes (TIL) and intra-hepatic lymphocytes. We used flow cytometry to quantify expression of the inhibitory receptors PD-1, hepatitis A virus cellular receptor 2 (TIM3), lymphocyte activating 3 (LAG3), and CTLA4 on CD8⁺ and CD4⁺ T cells from tumor, control tissue, and blood; we studied the effects of antibodies that block these pathways in T-cell activation assays.

RESULTS

Expression of PD-1, TIM3, LAG3, and CTLA4 was significantly higher on CD8⁺ and CD4⁺ T cells isolated from HCC tissue than control tissue or blood. Dendritic cells, monocytes, and B cells in HCC tumors expressed ligands for these receptors. Expression of PD-1, TIM3, and LAG3 was higher on tumor-associated antigen (TAA)-specific CD8⁺ TIL, compared with other CD8⁺ TIL. Compared with TIL that did not express these inhibitory receptors, CD8⁺ and CD4⁺ TIL that did express these receptors had higher levels of markers of activation, but similar or decreased levels of granzyme B and effector cytokines. Antibodies against CD274 (PD-ligand1 [PD-L1]), TIM3, or LAG3 increased proliferation of CD8⁺ and CD4⁺ TIL and cytokine production in response to stimulation with polyclonal antigens or TAA. Importantly, combining antibody against PD-L1 with antibodies against TIM3, LAG3, or CTLA4 further increased TIL functions.

CONCLUSIONS

The immune checkpoint inhibitory molecules PD-1, TIM3, and LAG3 are up-regulated on TAA-specific T cells isolated from human HCC tissues, compared with T cells from tumor-free liver tissues or blood. Antibodies against PD-L1, TIM3, or LAG3 restore responses of HCC-derived T cells to tumor antigens, and combinations of the antibodies have additive effects. Strategies to block PD-L1, TIM3, and LAG3 might be developed for treatment of primary liver cancer.

Establishment of MAGEC2-knockout cells and functional investigation of MAGEC2 in tumor cells

Cancer/testis antigen MAGEC2, a member of the type I melanoma‐associated antigen family, is expressed in a wide variety of cancer types but not in normal somatic cells. MAGEC2 has long been recognized as a tumor‐specific target, however, its functions remain largely unknown. In this study, we established MAGEC2‐knockout A375 melanoma cell lines using the CRISPR/Cas9 system. Seven clonal cell lines were generated by using four single guide RNAs targeting the coding region of the MAGEC2 gene, which produced indels that abolished MAGEC2 protein expression. To identify the differentially expressed protein profiles associated with MAGEC2 loss, isobaric tag for relative quantitation‐based comparative proteomics experiments were carried out on the MAGEC2‐knockcout and control A375 cells. Mining of the proteomics data identified a total 224 (61.6% upregulated and 38.4% downregulated) proteins to be significantly altered in expression level in MAGEC2‐knockcout cells. Ingenuity Pathway Analysis indicated that the significantly altered proteins were involved in critical neoplasia‐related biological functions such as cell death, proliferation, and movement. Gene ontology analysis identified “apoptosis signaling” as the top‐most upregulated pathway associated with MAGEC2 loss. We showed that knockout or knockdown of the MAGEC2 gene sensitized melanoma cells to tumor necrosis factor‐α‐induced apoptosis. Interestingly, actin‐based motility by Rho and RhoA signaling, known to promote cell migration, were also identified as the top downregulated pathways in MAGEC2‐knockout A375 cells. In short, our study provides a suitable cell model for exploring the biological functions of MAGEC2 in malignant cells, and sheds light on the molecular pathway by which MAGEC2 promotes tumor development.