c-Myc Protein Expression Research Articles

Circular RNA PVT1 Regulates Cell Proliferation, Migration, and Apoptosis by Stabilizing c-Myc and Downstream Target CXCR4 Expression in Acute Myeloid Leukemia

This study aimed to investigate the role and mechanism of circular RNA PVT1 (circPVT1) in patients with acute myeloid leukemia (AML). The expression of circPVT1 in 23 patients with de novo AML (not acute promyelocytic leukemia, not APL) and cell lines were detected by RT-qPCR. Loss of function assays were carried out to explore the influence of silenced circPVT1 on the proliferation, migration, and apoptosis in the THP-1 cell line. CCK-8 assays, trans-well assays, and annexin V/PI staining assays were performed to assess proliferation, migration, and apoptosis, respectively. CircPVT1 was highly expressed in AML patients and myeloid cell lines compared to healthy controls. Higher expression of circPVT1 was related to shorter overall survival (OS) and relapse-free survival (RFS) in AML patients. Cell viability and migration were inhibited and apoptosis was increased when circPVT1 was knocked down in THP-1 cells. Knockdown of circPVT1 resulted in marked suppression of c-Myc protein with no significant change in mRNA levels. We also found that circPVT1 knockdown markedly increased the phosphorylation of c-Myc Thr-58, which was responsible for c-Myc degradation. Silencing of c-Myc caused a significant decrease in CXCR4 mRNA and protein expression, whereas the overexpression of c-Myc caused the opposite result, suggesting that CXCR4 is a target molecule of c-Myc. Finally, we found that overexpression of c-Myc could partially reverse circPVT1 knockdown-induced anti-tumor effects on THP-1 cells in vitro. Our findings showed that circPVT1 was highly expressed in AML patients and was related to shorter OS and RFS. CircPVT1 may exert an oncogenic effect in THP-1 cells by stabilizing c-Myc protein expression and downstream target CXCR4 expression. These data indicate that circPVT1 may be a promising therapeutic target for AML.

HPV E6 promotes cell proliferation of cervical cancer cell by accelerating accumulation of RBM15 dependently of autophagy inhibition.

The mechanism of m6A modification in HPV-related cervical cancer remains unclear. This study explored the role of methyltransferase components in HPV-related cervical cancer and the mechanism. The levels of methyltransferase components and autophagy, ubiquitylation of RBM15 protein and the co-localization of lysosomal markers LAMP2A and RBM15 were measured. CCK-8 assay, flow cytometry, clone formation experiment and immunofluorescence assay were conducted to measure cell proliferation. The mouse tumor model was developed to study the cell growth in vivo. The binding of RBM15 to c-myc mRNA and m6A modifcation of c-myc mRNA were analyzed. The expressions of METTL3, RBM15 and WTAP were higher in HPV-positivecervical cancer cell lines than those in HPV-negativecells, especially RBM15. HPV-E6 knock-down inhibited the expression of RBM15 protein and promoted its degradation, but couldn't change its mRNA level. Autophagy inhibitor and proteasome inhibitor could reverse those effects. HPV-E6 siRNA could not enhance ubiquitylation modification of RBM15, but could enhance autophagy and the co-localization of RBM15 and LAMP2A. RBM15 overexpression could enhance cell proliferation, block the inhibitory effects of HPV-E6 siRNA on cell growth, and these effects could be reserved by cycloeucine. RBM15 could bind to c-myc mRNA, resulting in an increase to m6A level and protein expression of c-myc, which could be blocked by cycloeucine. HPV-E6 can downregulate autophagy, inhibit the degradation of RBM15 protein, induce the accumulation of intracellular RBM15, and increase the m6A modification on c-myc mRNA, resulting in an increase of c-myc protein and a growth promotion for cervical cancer cells.

DNA-PKcs as an upstream mediator of OCT4-induced MYC activation in small cell lung cancer

Small cell lung cancer (SCLC) is a neuroendocrine tumor noted for the rapid development of both metastases and resistance to chemotherapy. High mutation burden, ubiquitous loss of TP53 and RB1, and a mutually exclusive amplification of MYC gene family members contribute to genomic instability and make the development of new targeted agents a challenge. Previously, we reported a novel OCT4-induced MYC transcriptional activation pathway involving c-MYC, pOCT4S111, and MAPKAPK2 in progressive neuroblastoma, also a neuroendocrine tumor. Using tumor microarray analysis of clinical samples and preclinical models, we now report a correlation in expression between these proteins in SCLC. In correlating c-MYC protein expression with genomic amplification, we determined that some SCLC cell lines exhibited high c-MYC without genomic amplification, implying amplification-independent MYC activation. We then confirmed direct interaction between OCT4 and DNA-PKcs and identified specific OCT4 and DNA-PKcs binding sites. Knock-down of both POU5F1 (encoding OCT4) and PRKDC (encoding DNA-PKcs) resulted in decreased c-MYC expression. Further, we confirmed binding of OCT4 to the promoter/enhancer region of MYC. Together, these data establish the presence of a DNA-PKcs/OCT4/c-MYC pathway in SCLCs. We then disruptively targeted this pathway and demonstrated anticancer activity in SCLC cell lines and xenografts using both DNA-PKcs inhibitors and a protein-protein interaction inhibitor of DNA-PKcs and OCT4. In conclusion, we demonstrate here that DNA-PKcs can mediate high c-MYC expression in SCLCs, and that this pathway may represent a new therapeutic target for SCLCs with high c-MYC expression.

Berberine targets KIF20A and CCNE2 to inhibit the progression of nonsmall cell lung cancer via the PI3K/AKT pathway.

Nonsmall cell lung cancer (NSCLC) is the main type of lung cancer, accounting for approximately 85%. Berberine (BBR), a commonly used traditional Chinese medicine, has been reported to exhibit a potential antitumor effect in various cancers. In this research, we explored the function of BBR and its underlying mechanisms in the development of NSCLC. Cell Counting Kit-8 (CCK-8), 5-ethynyl-20-deoxyuridine (EdU), colony formation assays, flow cytometry, and transwell invasion assay were employed to determine cell growth, the apoptotic rate, cell invasion of NSCLC cells, respectively. Western blot was applied for detecting the protein expression of c-Myc, matrix metalloprotease 9 (MMP9), kinesin family member 20A (KIF20A), cyclin E2 (CCNE2), and phosphatidylinositol-3-kinase/protein kinase B (PI3K/AKT) pathway-related proteins. Glycolysis was evaluated by detecting glucose consumption, lactate production, and adenosine triphosphate/adenosine diphosphate (ATP/ADP) ratio with the matched kits. Real-time quantitative polymerasechain reaction(RT-qPCR) was conducted to analyze the level of KIF20A and CCNE2. Tumor model was established to evaluate the function of BBR on tumor growth in NSCLC in vivo. In addition, immunohistochemistry assay was employed to detect the level of KIF20A, CCNE2, c-Myc, and MMP9 in mice tissues. BBR exhibited suppressive effects on the progression of NSCLC, as evidenced by inhibiting cell growth, invasion, glycolysis, and facilitating cell apoptosis in H1299 and A549 cells. KIF20A and CCNE2 were upregulated in NSCLC tissues and cells. Moreover, BBR treatment significantly decreased the expression of KIF20A and CCNE2. KIF20A or CCNE2 downregulation could repress cell proliferation, invasion, glycolysis, and induce cell apoptosis in both H1299 and A549 cells. The inhibition effects of BBR treatment on cell proliferation, invasion, glycolysis, and promotion effect on cell apoptosis were rescued by KIF20A or CCNE2 overexpression in NSCLC cells. The inactivation of PI3K/AKT pathway caused by BBR treatment in H1299 and A549 cells was restored by KIF20A or CCNE2 upregulation. In vivo experiments also demonstrated that BBR treatment could repress tumor growth by regulating KIF20A and CCNE2 and inactivating the PI3K/AKT pathway. BBR treatment showed the suppressive impact on the progression of NSCLC by targeting KIF20A and CCNE2, thereby inhibiting the activation of the PI3K/AKT pathway.

Euonymus sachalinensis Induces Apoptosis by Inhibiting the Expression of c-Myc in Colon Cancer Cells.

We hypothesized that Euonymus sachalinensis (ES) induces apoptosis by inhibiting the expression of c-Myc in colon cancer cells, and this study proved that the methanol extract of ES has anticancer effects in colon cancer cells. ES belongs to the Celastraceae family and is well known for its medicinal properties. Extracts of species belonging to this family have been used to treat diverse diseases, including rheumatoid arthritis, chronic nephritis, allergic conjunctivitis, rhinitis, and asthma. However, ES has been targeted because there are currently few studies on the efficacy of ES for various diseases, including cancer. ES lowers cell viability in colon cancer cells and reduces the expression of c-Myc protein. We confirm that the protein level of apoptotic factors such as PARP and Caspase 3 decrease when ES is treated with Western blot, and confirm that DNA fragments occur through TUNEL assay. In addition, it is confirmed that the protein level of oncogenes CNOT2 and MID1IP1 decrease when ES is treated. We have also found that ES enhances the chemo-sensitivity of 5-FU in 5-FU-resistant cells. Therefore, we confirm that ES has anticancer effects by inducing apoptotic cell death and regulating the oncogenes CNOT2 and MID1IP1, suggesting its potential for use in the treatment of colon cancer.

Abstract 4480: Treatment of PTEN/PI3K co-mutated endometrial adenocarcinoma with multitarget small molecule inhibitors

Abstract Introduction: The objective of this study is to assess the feasibility and safety of treating endometrial adenocarcinoma (EC) with multitarget inhibitors which orthogonally target known oncogenic kinases and epigenetic regulators. The Molecular Targeted Therapeutics Laboratory has developed nanomolar potent multitarget small molecule chemotypes that inhibit the PI3K/Akt/mTOR pathway, cancer-associated kinases, and epigenetic regulatory proteins such as BRD4 in vitro and in vivo. Methods: Two EC cell lines (AN3-CA, RL95-2) were treated with varying concentrations of triple PI3K/BRD4/CDK4/6/9 inhibitor LCI132 and dual PI3K/CDK4/6/9 inhibitors LCI133 and LCI136 for 48 hours; and cell viability assays were performed with IC50 determination. EC cells were treated with multitarget inhibitors and other indicated inhibitors of PI3K, BET, CDK4/6, and CDK9 for 24 hours; and lysates were prepared accordingly for Western blot (WB) and qRT-PCR analyses. Flow cytometry was conducted for cell cycle and apoptosis assays. Results: In cell-free assays, LCI132 is a nanomolar inhibitor of PI3K/BRD4/CDK4/6/9, LCI133 is a picomolar inhibitor of CDK9, and LCI136 is a nanomolar inhibitor of PI3K and CDK9. LCI133 demonstrated nanomolar potency towards AN3-CA (IC50 248 nM) and RL95-2 (IC50 105 nM). LCI136 demonstrated nanomolar potency towards AN3-CA (IC50 631 nM) and RL95-2 (IC50 728 nM). WB demonstrated 24-hour treatment of FBXW7mut AN3-CA with LCI132 inhibited AKT phosphorylation but an increase in c-MYC protein expression. A corresponding increase in c-Myc gene expression at 24 hours was confirmed on qRT-PCR. In FBXW7wt RL95-2, LCI132 decreased c-Myc protein expression. LCI132 demonstrated dose-dependent G1 arrest, and dose-dependent pre-apoptotic and apoptotic activity. Conclusions: Dual-target inhibitors LCI133 and LCI136 are nanomolar potent in AN3-CA and RL95-2 EC cell lines, suggesting a role of CDK9 inhibition of PTEN/PI3K co-mutated EC. Preliminary studies demonstrate an upregulation of MYC gene and protein expression in FBXW7mut EC but not FBXW7wt, and the role of FBXW7 as a predictive biomarker in treatment of PTEN/PIK3R1 co-mutated EC warrants further investigation. Citation Format: Ritchie Delara, Cody McHale, Dhananjaya Pal, Krishnaiah Maddeboina, R. Wendel Naumann, Erin Crane, Jubilee Brown, Donald Durden. Treatment of PTEN/PI3K co-mutated endometrial adenocarcinoma with multitarget small molecule inhibitors. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4480.

Abstract 6285: Preclinical efficacy of CDK7 inhibitor-based combinations in cellular models of advanced myeloproliferative neoplasms (MPN)

Abstract Advanced MPN are characterized by driver mutations in JAK2, c-MPL or calreticulin (CALR) gene, with hyperactive JAK-STAT5/3 and NFkB signaling. Co-occurrence of mutations in chromatin/transcriptional regulators, including DNMT3A, TET2, ASXL1, EZH2, SRSF2, RUNX1 and TP53, creates the dysregulated transcriptome, which is responsible for the increased growth, survival and therapy-refractoriness in MPN blastic phase (BP). Treatment with JAK inhibitors (JAKis), e.g., ruxolitinib, venetoclax and hypomethylating agents are ineffective in improving survival in MPN-BP. CDK7 is the crucial catalytic component of the general transcript initiation factors TFIIH, which is recruited to the transcription start-sites along with RNA-pol II (RNAP2) to initiate transcription. Complexed with cyclin H, CDK7 phosphorylates CDK1, 2, 4 and 6, as well as serine 5 and 7 in the C terminal domain (CTD) of RNAP2, thus facilitating transcript initiation. CDK7 also phosphorylates CDK9, which in turn phosphorylates serine 2 of the CTD of RNAP2, and phosphorylates and inactivates the negative elongation factors, thus enabling productive mRNA transcript elongation of growth and survival promoting oncogenes. In MPN-BP, these include RUNX1, Bcl-xL, MCL1, CDK4/6, PIM1 and MYC. CRISPR-gRNA dependency-screen (DepMap) demonstrated that CDK7 is a dependency in the Advanced-AML cell lines, SET2 and HEL cells. Present studies demonstrate that treatment with ATP-competitive, covalent CDK7 inhibitors (CDK7i) SY-1365, and its clinical grade counterpart SY-5609, dose-dependently inhibits cell cycle, growth and induces lethality in SET2 and HEL as well as patient-derived (PD), CD34+ MPN-sAML cells. ChIP-Seq analysis showed that SY-1365 treatment caused log2 fold-reduction in p-Ser2-RNAP2 occupancy on the DNA of MYC, PIM1 and MCL1 genes in HEL cells. RNA-Seq analysis showed that SY1365 treatment caused negative enrichment of gene-sets of MYC and E2F targets, as well as inflammatory response, IL6-JAK-STAT3 and mTORC1 signaling. SY-1365 treatment also dose-dependently depleted protein expressions of p-Ser5 RNAP2, p-Ser2 RNAP2, c-Myc, c-Myb, RUNX1, PU.1, MCL1 and Bcl-xL, while inducing cleavage of PARP protein. As compared to the parental JAKi-sensitive, in vitro generated JAKi-persister/resistant (P/R) SET2/RuxP cells were significantly more sensitive to SY-1365-induced apoptosis. Co-treatment with CDK7i and ruxolitinib or the BET inhibitor OTX015 was synergistically lethal in PD MPN-BP cells (n=7). In an aggressive xenograft model of HEL-GFP/Luc cells in NSG mice, compared to the vehicle control, monotherapy with SY5609 significantly reduced the MPN sAML burden and improved survival of the NSG mice without causing host toxicity. These findings demonstrate promising activity and support the rationale to further evaluate the in vivo efficacy of CDK7i-based combinations against advanced MPN. Citation Format: Christopher P. Mill, Warren C. Fiskus, Christine E. Birdwell, John A. Davis, Kaberi Das, Kapil N. Bhalla. Preclinical efficacy of CDK7 inhibitor-based combinations in cellular models of advanced myeloproliferative neoplasms (MPN) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6285.

LncRNA SNHG12 promotes proliferation and migration of hepatic progenitor cells via the Wnt/β-catenin pathway.

Hepatic progenitor cells (HPCs) play an important role in the treatment of chronic liver disease. To investigate the effect and mechanism of long noncoding RNAs/small nucleolar RNA host gene 12 (lncRNA SNHG12) on the proliferation and migration of the HPC cell line WB-F344. Hepatic progenitor cells were divided into a no-treatment group (sham), empty vector transfection of plasmid pcDNA3.1 (NC vector), pcDNA3.1-SNHG12 (SNHG12), negative short hairpin RNA (sh-NC), SNHG12 shRNA (sh-SNHG12), and pcDNA3.1-SNHG12+salinomycin intervention (SNHG12+salinomycin) groups. Cell proliferation, cell cycle and migration ability, as well as albumin (ALB), alpha-fetoprotein (AFP), â-catenin, cyclin D1, and c-Myc protein expression in each group were determined using Cell Counting Kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU), flow cytometry, transwell migration assays, enzyme-linked immunosorbent assay (ELISA), and western blot. The overexpression of lncRNA SNHG12 significantly upregulated proliferation, migration and cell cycle progression of WB-F344 cells. Furthermore, the overexpression of lncRNA SNHG12 increased the level of ALB, and the protein expression of â-catenin, cyclin D1 and c-Myc in the cell line, while decreasing the level of AFP. Conversely, the knockdown of lncRNA SNHG12 displayed the opposite effects. The inhibition of the Wnt/â-catenin signaling pathway with salinomycin significantly downregulated the â-catenin, cyclin D1 and c-Myc protein expression in WB-F344 cells. The lncRNA SNHG12 promotes the proliferation and migration of WB-F344 cells via activating the Wnt/â-catenin pathway.

Correlation between expression of Lin28B and C-myc in patients with laryngeal squamous cell carcinoma and clinicopathological features and prognosis.

Laryngeal squamous cell carcinoma (LSCC) is a common malignant tumor of head and neck. Screening of target genes for malignant tumor therapy is one of the focuses of cancer research, with proto-oncogene and tumor suppressor gene as the breakthrough. It has become an urgent need to find the target gene related to the treatment and prognosis of LSCC.This study aims to explore the role of Lin28B and C-myc in LSCC by detecting the expressions of these two proteins and analyze the correlation between the expression of Lin28B and C-myc and clinicopathological features and prognosis of LSCC. We detected the expression of Lin28B and C-myc proteins in 102 specimens of LSCC and 90 specimens of adjacent tissues by immunochemistry, and analyzed the correlation between Lin28B and C-myc protein expressions in LSCC as well as the correlation between the expressions of the two proteins and the clinicopathological features of LSCC. At the same time, the Kaplan-Meier method was used to analyze the relation between Lin28B and C-myc protein levels with the postoperative survival rate of LSCC patients. The protein levels of Lin28B and C-myc in the LSCC tissnes were significantly higher than those in the adjacent tissues (both P<0.05),and there was a positive correlation between the expression of Lin28B and C-myc in LSCC (r＝0.476, P<0.05). The expression of Lin28B protein was closely related to age, lymph node metastasis, clinical stage, tumor size, and pathological differentiation of LSCC patients (all P<0.05). while the expression of C-myc protein was closely related to lymph node metastasis, clinical stage, tumor size, and pathological differentiation of LSCC patients (all P<0.05). A relevant survival analysis showed that in patients with higher level of Lin28B (P＝0.001) or C-myc protein (P<0.001), the postoperative survival rate was relatively low. Lin28B and C-myc proteins are highly expressed in LSCC with a positive correlation. Furthermore, they are closely related to lymph node metastasis, clinical stage, tumor size, pathological differentiation and prognosis, suggesting that both Lin28B and C-myc might be involved in the occurrence and development of LSCC.

Chronic PFOA exposure in vitro causes acquisition of multiple tumor cell characteristics in rat liver cells

Perfluorooctanoic acid (PFOA) is tumorigenic in rats and mice and potentially tumorigenic in humans. Here, we studied long-term PFOA exposure with an in vitro transformation model using the rat liver epithelial cell, TRL 1215. Cells were cultured in 10 μM (T10), 50 μM (T50) and 100 μM (T100) PFOA for 38 weeks and compared to passage-matched control cells. T100 cells showed morphological changes, loss of cell contact inhibition, formation of multinucleated giant and spindle-shaped cells. T10, T50, and T100 cells showed increased LC50 values 20%, 29% to 35% above control with acute PFOA treatment, indicating a resistance to PFOA toxicity. PFOA-treated cells showed increases in Matrix metalloproteinase-9 secretion, cell migration, and developed more and larger colonies in soft agar. Microarray data showed Myc pathway activation at T50 and T100, associating Myc upregulation with PFOA-induced morphological transformation. Western blot confirmed that PFOA produced significant increases in c-MYC protein expression in a time- and concentration-related manner. Tumor invasion indicators MMP-2 and MMP-9, cell cycle regulator cyclin D1, and oxidative stress protein GST were all significantly overexpressed in T100 cells. Taken together, chronic in vitro PFOA exposure produced multiple cell characteristics of malignant progression and differential gene expression changes suggestive of rat liver cell transformation.

Oncogenic PKA signaling increases c-MYC protein expression through multiple targetable mechanisms.

Genetic alterations that activate protein kinase A (PKA) are found in many tumor types. Yet, their downstream oncogenic signaling mechanisms are poorly understood. We used global phosphoproteomics and kinase activity profiling to map conserved signaling outputs driven by a range of genetic changes that activate PKA in human cancer. Two signaling networks were identified downstream of PKA: RAS/MAPK components and an Aurora Kinase A (AURKA)/glycogen synthase kinase (GSK3) sub-network with activity toward MYC oncoproteins. Findings were validated in two PKA-dependent cancer models: a novel, patient-derived fibrolamellar carcinoma (FLC) line that expresses a DNAJ-PKAc fusion and a PKA-addicted melanoma model with a mutant type I PKA regulatory subunit. We identify PKA signals that can influence both de novo translation and stability of the proto-oncogene c-MYC. However, the primary mechanism of PKA effects on MYC in our cell models was translation and could be blocked with the eIF4A inhibitor zotatifin. This compound dramatically reduced c-MYC expression and inhibited FLC cell line growth in vitro. Thus, targeting PKA effects on translation is a potential treatment strategy for FLC and other PKA-driven cancers.

Abstract A022: Role of imaging mass cytometry in studying hepatoblastoma vascular invasion

Abstract Introduction: Hepatoblastoma (HB) is the most common liver cancer in children with a survival rate of less than 50% in patients with high-risk disease, especially those with vascular invasion (VI). Patients with VI receive aggressive therapies that are toxic and ineffective; therefore, a better understanding of the biomarkers and biology of VI in HB is urgently needed. Methods: Using imaging mass cytometry (IMC) we analyzed 18 pre-validated protein targets on two of our formalin-fixed paraffin embedded (FFPE) HB patient samples; one with VI and one without VI. For confirmation of the proteins of interest, we performed immunohistochemistry (IHC) on primary and metastatic lesions from a separate patient. We performed RNA sequencing of one of our primary liver tumor and two sub-clones of that tumor, one inside an intrahepatic vessel and one sample representing tumor vessel thrombus. Results: By IMC, we found that protein expression of c-Myc and YAP-1 are increased in the areas of VI as the tumor invades the neighboring blood vessel. YAP-1 and c-Myc expression were low in the patient without VI. When examining the IHC of the separate patient with metastatic lung disease, we noted clear nuclear positivity of YAP-1 and c-Myc in the metastatic cells, compared to the negative nature of the primary liver tumor. Our RNA sequencing data showed that the average gene expression of c-Myc of the tumor in intrahepatic vessel and tumor vessel thrombus was 1.61 times higher than the primary tumor. The tumor found in the intrahepatic vessel and tumor vessel was found to have 1.29 times higher expression of Yap-1 compared to the primary tumor. Conclusions: YAP-1 and c-Myc had higher expression in hepatoblastoma as the tumor cells progress to invade the vasculature and metastasize. YAP-1 and c-Myc expression appears to play a role in vascular invasion that is maintained when tumors grow in the metastatic sites. Citation Format: Andres F. Espinoza, Roma Patel, Sarah Woodfield, Sanjeev A. Vasudevan. Role of imaging mass cytometry in studying hepatoblastoma vascular invasion [abstract]. In: Proceedings of the AACR Special Conference: Cancer Metastasis; 2022 Nov 14-17; Portland, OR. Philadelphia (PA): AACR; Cancer Res 2022;83(2 Suppl_2):Abstract nr A022.

Effect of wheat-grain moxibustion on Wnt/β-catenin signaling pathway in bone marrow cell in mice with bone marrow inhibition

To observe the effect of wheat-grain moxibustion at "Dazhui" (GV 14), "Zusanli" (ST 36) and "Sanyinjiao" (SP 6) on Wnt/β-catenin signaling pathway in bone marrow cell in mice with bone marrow inhibition, and to explore the possible mechanism of wheat-grain moxibustion in treating bone marrow inhibition. Forty-five SPF male CD1(ICR) mice were randomly divided into a blank group, a model group and a wheat-grain moxibustion group, 15 mice in each group. The bone marrow inhibition model was established by intraperitoneal injection of 80 mg/kg of cyclophosphamide (CTX). The mice in the wheat-grain moxibustion group were treated with wheat-grain moxibustion at "Dazhui" (GV 14), "Zusanli" (ST 36) and "Sanyinjiao" (SP 6), 3 moxa cones per acupoint, 30 s per moxa cone, once a day, for 7 consecutive days. The white blood cell count (WBC) was measured before modeling, before intervention and 3, 5 d and 7 d into intervention. After intervention, the general situation of mice was observed; the number of nucleated cells in bone marrow was detected; the serum levels of interleukin-3 (IL-3), interleukin-6 (IL-6) and granulocyte macrophage colony stimulating factor (GM-CSF) were measured by ELISA; the protein and mRNA expression of β-catenin, cyclinD1 and C-Myc in bone marrow cells was measured by Western blot and real-time PCR method. Compared with the blank group, the mice in the model group showed sluggish reaction, unstable gait, decreased body weight, and the WBC, number of nucleated cells in bone marrow as well as serum levels of IL-3, IL-6, GM-CSF were decreased (P<0.01), and the protein and mRNA expression of β-catenin, cyclinD1 and C-Myc was decreased (P<0.01). Compared with the model group, the mice in the wheat-grain moxibustion group showed better general condition, and WBC, the number of nucleated cells in bone marrow as well as serum levels of IL-3, IL-6, GM-CSF were increased (P<0.01, P<0.05), and the protein and mRNA expression of β-catenin, cyclinD1 and C-Myc was increased (P<0.05). Wheat-grain moxibustion shows therapeutic effect on bone marrow inhibition, and its mechanism may be related to activating Wnt/β-catenin signaling pathway in bone marrow cells, improving bone medullary hematopoiesis microenvironment and promoting bone marrow cell proliferation.

Wogonin Restrains the Malignant Progression of Lung Cancer Through Modulating MMP1 and PI3K/AKT Signaling Pathway.

Wogonin, a natural flavonoid compound, represses cancer cell growth and induces cancer cell apoptosis in diverse malignancies. However, the function of Wogonin in lung cancer cells and its regulatory mechanism deserve to be identified. A549 and H460 cells were treated with Wogonin, and the cell growth, apoptosis, migration and invasion were measured by CCK-8 and EdU, flow cytometry and Transwell assays. The targeted genes of Wogonin and lung cancer were identified from the TCMSP and Genecards databases, respectively. The STRING database and Cytoscape software were used to establish a PPI network and screen hub genes. GO and KEGG analysis was conducted to explore the functions and signal pathways related to the hub genes. MMP1 expression in lung cancer was analyzed using the UALCAN databases, and GSEA was performed utilizing LinkedOmics. Gelatin zymography assay was used to detect MMP1 activity. MMP1 mRNA expression was detected by qRT-PCR. Besides, MMP1, p-AKT and c-Myc protein were detected by Western Blot assay. Wogonin could suppress the proliferation, migration and invasion of A549 and H460 cells and induce apoptosis. GO and KEGG enrichment analysis revealed the hub genes were mostly enriched in re-entry into the mitotic cell cycle and apoptosis. The expression of MMP1 was markedly upregulated in lung squamous cell carcinoma, lung adenocarcinoma tissues, and lung cancer cell lines. Wogonin could significantly inhibit MMP1 expression and activity, and overexpression of MMP1 significantly reversed the effect of Wogonin on the malignant phenotypes of A549 and H460 cells. Wogonin inhibited the expression of p-AKT and c-Myc protein by regulating MMP1. Wogonin can repress lung cancer cells' growth and metastatic potential and promote cell apoptosis via repressing MMP1 expression and modulating PI3K/AKT signaling pathway.

Loss of N-acetylglucosaminyl transferase V is involved in the impaired osteogenic differentiation of bone marrow mesenchymal stem cells.

The imbalance of bone resorption and bone formation causes osteoporosis (OP), a common skeletal disorder. Decreased osteogenic activity was found in the bone marrow cultures from N-acetylglucosaminyl transferase V (MGAT5)-deficient mice. We hypothesized that MGAT5 was associated with osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and involved in the pathological mechanisms of osteoporosis. To test this hypothesis, the mRNA and protein expression levels of MGAT5 were determined in bone tissues of ovariectomized (OVX) mice, a well-established OP model, and the role of MGAT5 in osteogenic activity was investigated in murine BMSCs. As expected, being accompanied by the loss of bone mass density and osteogenic markers (runt-related transcription factor 2, osteocalcin and osterix), a reduced expression of MGAT5 in vertebrae and femur tissues were found in OP mice. In vitro, knockdown of Mgat5 inhibited the osteogenic differentiation potential of BMSCs, as evidenced by the decreased expressions of osteogenic markers and less alkaline phosphatase and alizarin red S staining. Mechanically, knockdown of Mgat5 suppressed the nuclear translocation of β-catenin, thereby downregulating the expressions of downstream genes c-myc and axis inhibition protein 2, which were also associated with osteogenic differentiation. In addition, Mgat5 knockdown inhibited bone morphogenetic protein (BMP)/transforming growth factor (TGF)-β signaling pathway. In conclusion, MGAT5 may modulate the osteogenic differentiation of BMSCs via the β-catenin, BMP type 2 (BMP2) and TGF-β signals and involved in the process of OP.

Association of Kaiso and partner proteins in oral squamous cell carcinoma

Objectives:1. Identification of protein expression and subcellular localization of E-cadherin (E-cad), p120 catenin (P120ctn), and Kaiso in oral cancer (OC). 2. To study the protein expression of cyclin D1 and c-Myc (Kaiso targets) and determine their relationship with the expression and localization of Kaiso. MethodsHistological grading was performed in accordance with Broder's criteria. Expression and localization data for E-cad, p120ctn, Kaiso, cyclin D1, and c-Myc were acquired using immunohistochemistry. Data were analyzed using SPSS version 21. The chi-square test was used to measure the statistical significance of associations, with p < 0.05 as statistically significant. ResultsOf 47 OC cases, 36% showed low E-cad expression and 34% showed low p120ctn. Low Kaiso expression was recognized in 78% of tumor specimens. Aberrant cytoplasmic localization of p120ctn was seen in 80.8% cases. Cytoplasmic Kaiso localization was appreciated in 87% of tumor tissues, whereas 29.7% lacked any nuclear Kaiso. Kaiso expression was significantly associated with the expression of cyclin D1 but not with c-Myc. ConclusionThe present study identified a change in the localization of Kaiso in OC. The significance of this in relation to OC and tumor prognosis needs to be investigated with further studies using larger sample sizes and more sensitive molecular tools.

Abstract B030: Combined inhibition of BET proteins and PARP promotes impaired DNA damage repair response and cell cycle dysregulation in preclinical models of bladder cancer

Abstract Background: Bladder cancer (BC) remains a common and deadly malignancy, with a projected 81,180 new diagnoses and 17,100 deaths in the United States in 2022. According to the MSK/TCGA Bladder Cancer dataset, mutations in DNA damage response (DDR) genes that are part of the homologous recombination (HR) pathway occurred in up to 55% of patients, representing a potential therapeutic target in BC. In previous work, we used UNC’s EpiG Diamond compound library to show that, as a class, inhibition of the methyl-lysine reader bromodomain and extra-terminal domain (BET) proteins potently abrogate BC cell line viability. Here, we evaluated mechanisms related to HR inhibition that could explain pan-BET inhibitor OTX-015’s potency in BC. Methods: 5637 and J82 BC cells were treated with 1 µM OTX-015 or 0.1% DMSO control for 48-hours, total RNA was extracted, and then bulk RNA-sequencing (RNA-seq) was performed on an Illumina NovaSeq 6000 (Novogene, Sacramento, CA). Expression data was analyzed using Geneious Prime v2022.2.1 (Biomatters, San Diego, CA). Cells were then treated with 1 μM OTX-015, 5 μM of the PARP inhibitor olaparib, or combination for gene and protein expression analysis. Gene expression changes in BRCA1, BRCA2, PALB2, and RAD51, as well as MYC as a positive control, were confirmed by RT-PCR in biological triplicates after 48-hour incubation, normalized to an SDHA housekeeper and compared to a 0.1% DMSO control. Western blotting evaluated OTX-015 and olaparib effects on BRCA1, BRCA2, c-MYC, PALB2, and RAD51 protein expression after 72-hour incubation, using a GAPDH loading control and compared to a 0.1% DMSO control. Last, cells were treated with the same treatment schema for 24-72 hours, fixed with methanol, stained with propidium iodide (25 μg/mL), and flow cytometry evaluated effects on cell cycle using a ThermoFisher Attune NxT and FlowJo v10.8.1 (BD Life Sciences, Ashland, OR). Results: Bulk RNA-seq analyses revealed significantly altered expression of HR pathway genes in 5637 and J82 cells treated with OTX-015±olaparib. In 5637 cells, OTX-015 alone significantly reduced BRCA1, BRCA2, PALB2 and RAD51 expression, (n=3; P&amp;lt;0.001 for all), but only PALB2 and RAD51 expression was significantly reduced after combination treatment (n=3; P&amp;lt;0.001 for both). In J82 cells, OTX-015 alone and combination treatment significantly reduced BRCA1, PALB2 and RAD51 expression, (n=3; P&amp;lt;0.001 for all). Similarly, both OTX-015 and combination treatment resulted in reduced BRCA1, c-MYC, PALB2 and RAD51 protein expression in both cell lines. In both cell lines, combination treatment resulted in a substantially increased G2/M fraction at 48 hours compared to 0.1% DMSO (5637 cells: 62.9% vs 12.6% G2/M; J82 cells: 28.2% vs 17.8% G2/M). Conclusions: These data indicate that OTX-015-mediated inhibition of RAD51 and PALB2 could be responsible for impaired HR. Cell cycle data revealed a G2/M stall, rather than an S phase stall, suggesting mechanisms independent from impaired HR could be responsible for cell cycle dysregulation. Citation Format: Ryan M. Kemper, Manfred Meng, Daniel J. Crona. Combined inhibition of BET proteins and PARP promotes impaired DNA damage repair response and cell cycle dysregulation in preclinical models of bladder cancer. [abstract]. In: Proceedings of the AACR Special Conference: Cancer Epigenomics; 2022 Oct 6-8; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2022;82(23 Suppl_2):Abstract nr B030.

Design, synthesis, and biological evaluation of novel benzimidazolyl isoxazole derivatives as potential c-Myc G4 stabilizers to suppress c-Myc transcription and myeloma growth

The c-Myc oncogene is one of the most frequently deregulated driver genes in human cancer, and its rearrangement is closely associated with the development of multiple myeloma (MM). However, c-Myc is a disordered protein that lacks adequate binding pockets on its surface and has a half-life of only 20 to 30 minutes, so it is challenging to design small-molecule inhibitors. The guanine-rich nuclease hypersensitive element III1 (NHEIII1) upstream of the P1 promoter of the c-Myc gene can form intramolecular parallel G-quadruplexes (G4) structures. It has been established that c-Myc G4 controls 85-90% of the transcriptional activation of the c-Myc, which represents one of the most sought-after drug targets in cancer. Therefore, targeting c-Myc G4 to inhibit c-Myc protein would be a potential strategy for the treatment of MM. Herein, a series of benzimidazolyl isoxazole derivatives (EP1-EP19) were designed and synthesized. Among them, compound EP12 exhibited better RPMI-8226 cell inhibition activity (IC50 = 6.16 µM). Moreover, compound EP12 induced apoptosis and inhibited the expression of c-Myc mRNA and c-Myc protein at 5 µM. Circular dichroism (CD) and molecular dynamics (MD) simulation studies indicated that compound EP12 could firmly stabilize c-Myc G4. Accordingly, compound EP12 displayed potent anti-MM activities in vitro and might be a potential c-Myc G4 small molecular stabilizer to warrant further investigation.

Discovery of Anthranilic Acid Derivatives as Difluoromethylornithine Adjunct Agents That Inhibit Far Upstream Element Binding Protein 1 (FUBP1) Function.

Polyamine biosynthesis is regulated by ornithine decarboxylase (ODC), which is transcriptionally activated by c-Myc. A large library was screened to find molecules that potentiate the ODC inhibitor, difluoromethylornithine (DFMO). Anthranilic acid derivatives were identified as DFMO adjunct agents. Further studies identified the far upstream binding protein 1 (FUBP1) as the target of lead compound 9. FUBP1 is a single-stranded DNA/RNA binding protein and a master controller of specific genes including c-Myc and p21. We showed that 9 does not inhibit 3H-spermidine uptake yet works synergistically with DFMO to limit cell growth in the presence of exogenous spermidine. Compound 9 was also shown to inhibit the KH4 FUBP1-FUSE interaction in a gel shift assay, bind to FUBP1 in a ChIP assay, reduce both c-Myc mRNA and protein expression, increase p21 mRNA and protein expression, and deplete intracellular polyamines. This promising hit opens the door to new FUBP1 inhibitors with increased potency.

Asparagine Bioavailability Regulates the Translation of MYC oncogene in Lymphoid Malignancies

Non-essential amino acids are becoming increasingly important in cancer metabolism because of their roles beyond protein translation. These include providing precursors for macromolecule biosynthesis, serving as substrates for epigenetic modifications, regulating redox states, and modulating cell signaling. Acute lymphoblastic leukemia (ALL) is one such example where asparagine is shown to be conditionally essential for cancer growth and proliferation. Exploiting this metabolic vulnerability, L-Asparaginase (ASNase) has been used in the clinic to successfully treat ALL patients through depleting the circulating asparagine. Our investigation into the mechanism of resistance to ASNase in ALL cells yielded a striking correlation between asparagine bioavailability and c-MYC protein levels. c-MYC is a key transcription factor and has been shown to regulate the transcription of more than 10% of genes, including many metabolic genes, to meet the demands of tumor growth and progression. In addition, it has a well-documented role in normal hematopoiesis and hematological malignancies, including ALL, where high c-MYC levels have been shown to be a marker for leukemic initiation and growth. Using asparagine auxotrophic ALL cells that do not express asparagine synthetase (ASNS), the asparagine biosynthesis enzyme, we found that c-MYC protein levels were acutely depleted when asparagine was withdrawn from the tissue culture medium. However, c-MYC protein levels were sustained when ASNS cDNA was re-introduced into these cells. These results indicate the possibility of a reciprocal association between metabolism and a critical oncogene MYC. We also discovered that asparagine depletion inhibited the translation of c-MYC without changing its mRNA expression or altering the rate of protein degradation. Mechanistic Target of Rapamycin Complex 1 (mTORC1) and General Controlled Nonderepressible 2 (GCN2) are the two central molecular components involved in amino acid sensing and translation control. Asparagine starvation notably caused a decrease in global protein synthesis, mediated by suppression of mTORC1 and simultaneous activation of GCN2. Our studies using small molecule inhibitors and polysome profiling showed that repression of c-MYC mRNA translation is not due to the activation of the GCN2 pathway or a consequence of global translation suppression. In addition, both the '5' and '3' untranslated regions (UTRs) were not required for this inhibitory effect on c-MYC mRNA translation during asparagine depletion. Our results suggest that while asparagine depletion causes a defect in global translation at the initiation step, its effect on MYC mRNA translation is possibly due to elongation stalling. While ASNase can efficiently deplete circulating asparagine, its clinical applications are limited to ALL due to its low-level expression of ASNS. However, aspartate, a critical substrate for asparagine biosynthesis, can be pharmacologically targeted using electron transport chain (ETC) inhibitors. Our studies in ASNase-resistant ALL and lymphomas showed that while asparagine depletion alone did not affect c-MYC protein expression, co-treatment with ETC inhibitors (phenformin) showed a significant decrease in c-MYC protein levels. We extended this observation to test the synergy of ASNase and phenformin to treat an orthotopic MYC-driven B-cell lymphoma model. While either of the single treatments only modestly reduced the tumor burden, the double treatment showed the most significant reduction in the tumor burden, which correlated with a significant reduction of c-MYC protein expression. These results suggest that perturbing the asparagine biosynthesis pathway can be clinically employed to inhibit c-MYC protein expression and improve therapeutic outcomes. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal