Anchorage-independent Growth Ability Research Articles

Chronic exposure to hexavalent chromium induces esophageal tumorigenesis via activating the Notch signaling pathway.

Hexavalent chromium Cr(VI), as a well-established carcinogen, contributes to tumorigenesis for many human cancers, especially respiratory and digestive tumors. However, the potential function and relevant mechanism of Cr(VI) on the initiation of esophageal carcinogenesis are largely unknown. Here, immortalized human esophageal epithelial cells (HEECs) were induced to be malignantly transformed cells, termed HEEC-Cr(VI) cells, via chronic exposure to Cr(VI), which simulates the progress of esophageal tumorigenesis. In vitro and in vivo experiments demonstrated that HEEC-Cr(VI) cells obtain the ability of anchorage-independent growth, greater proliferative capacity, cancer stem cell properties, and the capacity to form subcutaneous xenografts in BALB/c nude mice when compared to their parental cells, HEECs. Additionally, HEEC-Cr(VI) cells exhibited weakened cell motility and enhanced cell adhesion. Interestingly, HEECs with acute exposure to Cr(VI) failed to display those malignant phenotypes of HEEC-Cr(VI) cells, suggesting that Cr(VI)‍-induced malignant transformation, but not Cr(VI) itself, is the cause for the tumor characteristics of HEEC-Cr(VI) cells. Mechanistically, chronic exposure to Cr(VI) induced abnormal activation of Notch signaling, which is crucial to maintaining the capacity for malignant proliferation and stemness of HEEC-Cr(VI) cells. As expected, N-‍[N-‍(3,5-difluorophenacetyl)‍-L-alanyl]‍-S-phenylglycine t-butyl ester (DAPT), an inhibitor for the Notch pathway, drastically attenuated cancerous phenotypes of HEEC-Cr(VI) cells. In conclusion, our study clarified the molecular mechanism underlying Cr(VI)‍-induced esophageal tumorigenesis, which provides novel insights for further basic research and clinical therapeutic strategies about Cr(VI)‍-associated esophageal cancer.

TRIM65 promotes renal cell carcinoma through ubiquitination and degradation of BTG3

As a typical E3 ligase, TRIM65 (tripartite motif containing 65) is involved in the regulation of antiviral innate immunity and the pathogenesis of certain tumors. However, the role of TRIM65 in renal cell carcinoma (RCC) and the underlying mechanism has not been determined yet. In this study, we identified TRIM65 as a novel oncogene in RCC, which enhanced the tumor cell proliferation and anchorage-independent growth abilities both in vitro and in vivo. Moreover, we found that TRIM65-regulated RCC proliferation mainly via direct interaction with BTG3 (BTG anti-proliferation factor 3), which in turn induced the K48-linked ubiquitination and subsequent degradation through K41 amino acid. Furthermore, TRIM65 relieved G2/M phase cell cycle arrest via degradation of BTG3 and regulated downstream factors. Further studies revealed that TRIM65 acts through TRIM65-BTG3-CyclinD1 axis and clinical sample IHC chip data indicated a negative correction between TRIM65 and BTG3. Taken together, our findings demonstrated that TRIM65 promotes RCC cell proliferation via regulation of the cell cycle through degradation of BTG3, suggesting that TRIM65 may be a promising target for RCC therapy.

Additive Cytotoxic and Colony-Formation Inhibitory Effects of Aspirin and Metformin on PI3KCA-Mutant Colorectal Cancer Cells.

Human malignancies are one of the major health-related issues throughout the world and are anticipated to rise in the future. Despite huge investments made in anticancer drug development, limited success has been obtained and the average number of FDA approvals per year is declining. So, an increasing interest in drug repurposing exists. Metformin (MET) and aspirin (ASP) possess anticancer properties. This work aims to test the effect of these two drugs in combination on colorectal cancer (CRC) cells in vitro. The effects of MET and/or ASP on cell proliferation, viability, migratory ability, anchorage-independent growth ability (colony formation), and nutrient uptake were determined in two (HT-29 and Caco-2) human CRC cell lines. Individually, MET and ASP possessed antiproliferative, cytotoxic, and antimigratory effects and reduced colony formation in HT-29 cells (BRAF- and phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit α (PI3KCA)-mutant), although MET did not affect either 3H-deoxy-D-glucose or 14C-butyrate uptake and lactate production, and ASP caused only a small decrease in 14C-butyrate uptake. Moreover, in these cells, the combination of MET and ASP resulted in a tendency to an increase in the cytotoxic effect and in a potentiation of the inhibitory effect on colony formation, although no additive antiproliferative and antimigratory effects, and no effect on nutrient uptake and lactate production were observed. In contrast, MET and ASP, both individually and in combination, were almost devoid of effects on Caco-2 cells (BRAF- and PI3KCA-wild type). We suggest that inhibition of PI3K is the common mechanism involved in the anti-CRC effect of both MET, ASP and their combination and, therefore, that the combination of MET + ASP may especially benefit PI3KCA-mutant CRC cases, which currently have a poor prognostic.

Characterization of BRAFThr599dup Mutation as a Targetable Driver Mutation Identified in Lung Adenocarcinoma by Comprehensive Genomic Profiling.

Understanding the function of BRAF mutants is crucial for determining the best treatment strategy. This study aimed to characterize a rare BRAF variant, BRAFThr599dup, which was identified in a patient with lung adenocarcinoma (LUAD) by comprehensive genomic profiling. We report a case of LUAD with BRAFThr599dup treated with dabrafenib and trametinib. We conditionally expressed wild-type BRAF, BRAFV600E, or BRAFThr599dup in Ba/F3 cells and BEAS-2B cells. Ba/F3 cells carrying double-mutant BRAF (BRAFThr599dup/R509H, BRAFV600E/R509H, or BRAFK601E/R509H) that lacked the dimerizing ability were also established. Knockout of endogenous BRAF or CRAF in Ba/F3-BRAFThr599dup cells and Ba/F3-BRAFV600E cells was performed using the CRISPR/Cas9 system. Cell viability, mitogen-activated protein kinase (MAPK) signaling activity, and sensitivity to dabrafenib and trametinib were evaluated. The patient was revealed to have BRAFThr599dup-positive tumor cells as a predominant clone, and dabrafenib and trametinib treatment showed modest efficacy. In Ba/F3 cells, both BRAFThr599dup and BRAFV600E similarly caused interleukin-3-independent proliferation and activated the MAPK pathway. Moreover, BRAFThr599dup and BRAFV600E similarly caused a significant increase in the anchorage-independent growth ability of BEAS-2B cells. Along with Ba/F3-BRAFV600E cells, Ba/F3-BRAFThr599dup cells were highly sensitive to a monomer-specific BRAF inhibitor, dabrafenib, with a half-maximal inhibitory concentration value of 29.7 nM. In the absence of wild-type BRAF, wild-type CRAF, or an intact dimer interface, the ability to induce oncogenic addiction and MAPK pathway activation in Ba/F3-BRAFThr599dup cells was not affected, which was in contrast to the findings in the BRAFK601E/R509H double-mutant model. BRAFThr599dup is a potent driver oncogene that activates the MAPK pathway without the requirement for dimerization in vitro. Because BRAFThr599dup has been recurrently reported across various cancer types, our findings should be further investigated both mechanistically and clinically.

Effects of the SEMA4B gene on hexavalent chromium [Cr(VI)]-induced malignant transformation of human bronchial epithelial cells.

Our previous study identified the potential of SEMA4B methylation level as a biomarker for hexavalent chromium [Cr(VI)] exposure. This study aimed to investigate the role of the SEMA4B gene in Cr(VI)-mediated malignant transformation of human bronchial epithelial (BEAS-2B) cells. In our population survey of workers, the geometric mean [95% confidence intervals (CIs)] of Cr in blood was 3.80 (0.42, 26.56) μg/L. Following treatment with various doses of Cr(VI), it was found that 0.5μM had negligible effects on the cell viability of BEAS-2B cells. The expression of SEMA4B was observed to decrease in BEAS-2B cells after 7days of treatment with 0.5μM Cr(VI), and this downregulation continued with increasing passages of Cr(VI) treatment. Chronic exposure to 0.5μM Cr(VI) enhanced the anchorage-independent growth ability of BEAS-2B cells. Furthermore, the use of a methylation inhibitor suppressed the Cr(VI)-mediated anchorage-independent growth in BEAS-2B cells. Considering that Cr levels exceeding 0.5μM can be found in human blood due to occupational exposure, the results suggested a potential carcinogenic risk associated with occupational Cr(VI) exposure through the promotion of malignant transformation. The in vitro study further demonstrated that Cr(VI) exposure might inhibit the expression of the SEMA4B gene to promote the malignant transformation of BEAS-2B cells.

Generation of Novel Immunocompetent Mouse Cell Lines to Model Experimental Metastasis of High-Risk Neuroblastoma.

NB, being a highly metastatic cancer, is one of the leading causes of cancer-related deaths in children. Increased disease recurrence and clinical resistance in patients with metastatic high-risk NBs (HR-NBs) result in poor outcomes and lower overall survival. However, the paucity of appropriate in vivo models for HR-NB metastasis has limited investigations into the underlying biology of HR-NB metastasis. This study was designed to address this limitation and develop suitable immunocompetent models for HR-NB metastasis. Here, we developed several highly metastatic immunocompetent murine HR-NB cell lines. Our newly developed cell lines show 100% efficiency in modeling experimental metastasis in C57BL6 mice and feature metastasis to the sites frequently observed in humans with HR-NB (liver and bone). In vivo validation demonstrated their specifically gained metastatic phenotype. The in vitro characterization of the cell lines showed increased cell invasion, acquired anchorage-independent growth ability, and resistance to MHC-I induction upon IFN-γ treatment. Furthermore, RNA-seq analysis of the newly developed cells identified a differentially regulated gene signature and an enrichment of processes consistent with their acquired metastatic phenotype, including extracellular matrix remodeling, angiogenesis, cell migration, and chemotaxis. The presented newly developed cell lines are, thus, suitable and promising tools for HR-NB metastasis and microenvironment studies in an immunocompetent system.

Role of Histamine and Related Signaling in Kaposi's Sarcoma-Associated Herpesvirus Pathogenesis and Oncogenesis.

Although Kaposi's sarcoma-associated herpesvirus (KSHV) has been reported to cause several human cancers including Kaposi's sarcoma (KS) and primary effusion lymphoma (PEL), the mechanisms of KSHV-induced tumorigenesis, especially virus-host interaction network, are still not completely understood, which therefore hinders the development of effective therapies. Histamine, together with its receptors, plays an important role in various allergic diseases by regulating different inflammation and immune responses. Our previous data showed that antagonists targeting histamine receptors effectively repressed KSHV lytic replication. In the current study, we determined that histamine treatment increased cell proliferation and anchorage-independent growth abilities of KSHV-infected cells. Furthermore, histamine treatment affected the expression of some inflammatory factors from KSHV-infected cells. For clinical relevance, several histamine receptors were highly expressed in AIDS-KS tissues when compared to normal skin tissues. We determined that histamine treatment promoted KSHV-infected lymphoma progression in immunocompromised mice models. Therefore, besides viral replication, our data indicate that the histamine and related signaling are also involved in other functions of KSHV pathogenesis and oncogenesis.

Abstract 3753: miR-567 modulates the progression of melanoma cells and functions of macrophages

Abstract Purpose: Target therapy and immunotherapy are advancements in the treatment of melanoma; unfortunately, a subset of patients does not benefit or produces drug resistance. Therefore, an alternative strategy should be investigated to further improve clinical benefits. Macrophages are the abundant immune cells related to the progression of melanoma and resistance to drugs. In this study, we explored the novel roles of miR-567 in the progression of melanoma and effects of macrophages. Methods: miR-567 expression in nevus and melanoma tissues was analyzed by in situ hybridization. miR-567 was transfected into melanoma cells to investigate its biological effects through functional assays such as proliferation, colony formation, soft agar, and migration assays. In addition, miR-567-related signal transduction pathways in the melanoma cells were studied by western blot and next-generation sequencing analyses. Different phenotypes of macrophages polarized from THP-1 monocyte cells were used as in vitro model to investigate the effects of miR-567 on macrophages. Results: Our results showed that miR-567 expression levels were decreased in melanoma cells compared to melanocyte cells. Consistently, expression of miR-567 was 0.403-fold lower in melanoma tissues (n=118) as compared to nevus tissues (n=40). In addition, the receiver operating characteristic presented that the area under the curve value of miR-567 is 0.9495. Importantly, higher expression of miR-567 enhanced the overall survival of melanoma patients. Overexpression of miR-567 significantly reduced proliferation, survival, anchorage-independent growth, migratory, and invasive abilities of melanoma cells and BRAF-inhibitor resistant cells. Furthermore, our results demonstrated that IGF1R, E2F1, and Cyclin B2 are direct targets of miR-567 and knockdown of these genes attenuated proliferation and survival of melanoma cells. Interestingly, introduction of miR-567 downregulated MAPK/ERK and PI3K/AKT pathways in melanoma cells and regulated multiple pathways related to immune response. Of note, overexpression of miR-567 reduced the promoting melanoma growth induced by M2 or melanoma-associated macrophages, indicating the involvement of miR-567 in regulation of macrophages. Conclusion: miR-567 could be served not only as biomarkers but also as potential molecular target for prevention of melanoma progression. Citation Format: Mai-Huong Thi Nguyen, Chen-Huan Lin, Yu-Chi Huang, Mu-Shiun Tsai, Ming-Hong Chen, Azusa Miyashita, Satoshi Fukushima, Nianhan Ma. miR-567 modulates the progression of melanoma cells and functions of macrophages. [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 3753.

SPRR3 Contributes to Aggressiveness of Pancreatic Cancer Cells via NF-κB Signaling Pathway.

Pancreatic cancer remains a deadly solid tumor with worst survival, and a better understanding of the mechanisms of carcinogenesis of pancreatic cancer is critical to promote the survival of patients with pancreatic cancer. qPCR and western blot assay were used to determine the expression of SPRR3 in pancreatic cancer. Anchorage-independent growth ability, BrdU labeling, Transwell assay, and in vivo experiment were used to examine the functions of SPRR3 in aggressiveness of pancreatic cancer. Luciferase reporter assay, nucleoplasmic-separation technique, qPCR, and western blot assay were used to investigate the mechanism of SPRR3 regulating aggressiveness of pancreatic cancer. Our results showed that SPRR3 was significantly increased in pancreatic cancer, which resulted in poor survival for patients with pancreatic cancer. Further analysis showed that overexpression of SPRR3 contributed to anchorage-independent growth ability, growth rate, and invasion ability of pancreatic cancer cells. While, knockdown of SPRR3 showed the reverse results. Mechanistically, overexpression of SPRR3 can promote the transcription of NF-κB pathway, nuclear accumulation of p65, and mRNA levels of NF-κB pathway downstream genes. But, knockdown of SPRR3 induced the reverse results. The above findings clarified the important roles of SPRR3 in the progression of pancreatic cancer through NF-κB pathway. And targeting SPRR3 might be an effective strategy to therapy pancreatic cancer.

LncRNA HOTAIR functions and therapeutic perspectives.

Long non-coding RNAs (lncRNAs) exert central pathophysiological roles through the regulation of gene expression both at transcriptional and post-transcriptional levels. The characterization of lncRNAs’ interactome is disclosing several new mechanisms that control disease onset and progression thus opening the way to the development of new pioneering therapeutic approaches. Regarding the lncRNA HOTAIR, found upregulated in several cancers and in liver fibrosis, it has been proved as a potential therapeutic target. HOTAIR acts as a ceRNA for several miRNAs and it directly interacts with chromatin remodelling complexes (e.g. PRC2 and LSD1/NuRD complexes). In this regard, we recently reported the transcription factor SNAIL-mediated recruitment of HOTAIR/PRC2 complex on specific chromatin sites causing epithelial genes’ repression through epigenetic chromatin modifications. Conversely, HOTAIR is repressed by the liver-enriched transcriptional factor HNF4a that binds to both HOTAIR promoter and distant enhancer and impairs the formation of a chromatin loop between these genomic regions.In a therapeutic perspective, we design and validated the first example of a dominant negative lncRNA molecule (HOTAIR-sbid) that covers the HOTAIR portion involved in the interaction with SNAIL while is devoid of the domain of interaction with EZH2. Functionally, HOTAIR-sbid expression impairs SNAIL/EZH2/endogenous HOTAIR interaction; thus, PRC2 complex is not recruited on SNAIL-target chromatin sites (i.e. epithelial genes’ promoters). Accordingly, the cells rescue an epithelial phenotype, reduce EMT and, in turn, migratory, invasive and anchorage independent growth abilities. This approach promises high level of specificity and limited off-target effects. Future investigations should enhance RNAs’ stability and should design strategies for the delivery of these molecules to specific target cells.

HMMR promotes peritoneal implantation of gastric cancer by increasing cell–cell interactions

BackgroundDistant metastasis is the prominent factor for cancer-induced death of gastric cancer in which peritoneum is one of the dominating targets of gastric cancer metastasis. However, there is still a lack of effective predictive indicators and treatment methods for gastric cancer patients with peritoneal metastasis.MethodsA clustering assay was used to investigate the cell aggregates formation ability. While the soft agar assay and anoikis assay were performed to detect the anchorage-independent growth and anoikis-resistant ability respectively. Luciferase activity assay, western blotting and immunofluorescence were used to explore the effect of HMMR on AKT signaling activity. The peritoneal implantation model was examined to explore the role of HMMR in vivo.ResultsSilencing of HMMR expression markedly reduced the peritoneal metastasis of gastric cancer cells through reducing cell–cell interactions. Mechanistically, HA-HMMR could activate Akt signaling, thus succeeding in distant colonization and metastatic outgrowth. Importantly, inducible depletion of HMMR significantly abrogates peritoneal implantation of gastric cancer in vitro and in vivo.ConclusionOur study highlights that HMMR promotes peritoneal implantation of gastric cancer. A better understanding of HMMR’s functions and mechanism might provide a novel therapeutic target and prognostic marker for metastatic gastric cancer.

Intermedin (adrenomedullin 2) promotes breast cancer metastasis via Src/c-Myc-mediated ribosome production and protein translation.

Breast cancer is the most frequently diagnosed cancer and is the leading cause of cancer-associated mortality in women worldwide. Intermedin (IMD, also known as Adrenomedullin 2, ADM2) is an endogenous peptide that belongs to the calcitonin gene-related peptide family and has been reported to play important roles in several types of cancers, including breast cancer. In this study, we sought to investigate how IMD affects the behavior of breast cancer cells, the underlying mechanism of these effects, and whether blockade of IMD has a therapeutic effect against breast cancer. Transcriptome sequencing (RNA-Seq), cell biological experiments, Western blotting, immunoprecipitation, and animal tumor models were used. IMD expression was significantly increased in breast cancer samples, and the IMD level was positively correlated with lymph node metastasis and Ki67 expression. Cell biological experiments showed that IMD promoted the anchorage-independent growth, migration, and invasive ability of breast cancer cells. Inhibiting IMD activity with an anti-IMD monoclonal antibody blocked these tumor-promoting effects. In addition, blockade of IMD reduced in situ tumor growth and significantly decreased lung metastasis of 4T1 breast cancer in vivo. IMD induced Src kinase phosphorylation, which triggered the transcription of c-Myc, a major oncoprotein controlling the expression of genes that encode ribosomal components. Our data suggest that IMD is involved in breast cancer cell invasion and metastasis, potentially through increasing ribosome biogenesis and protein translation via the Src/c-Myc signaling pathway. These results suggest that IMD may be a novel target for the treatment of breast cancer.

Fusion HBx from HBV integrant affects hepatocarcinogenesis through deregulation of ER stress response

Hepatitis B virus (HBV) infection is a major cause of hepatocellular carcinoma (HCC) worldwide. HBV X protein (HBx) is potentially the most oncogenic among HBV-encoding proteins, while HBV integration, which is frequently observed in HCC, contributes to HCC development. However, the molecular mechanism underlying HBV-induced hepatocarcinogenesis remains unclear. In this study, we identified the fusion HBx, the HBx-human fusion protein derived from HBV integrant, in Hep3B cells and investigated its role in hepatocarcinogenesis. The identified full-length fusion mRNA was 3,725 bp in length, and the fusion HBx, which consisted of 1–140 amino acids of HBx followed by 61 amino acids from the human genome, was translated from the fusion mRNA. The fusion HBx knockdown resulted in reduced cell proliferation and invasion, and loss of tumor development in nude mice. Moreover, the fusion HBx, but not wild HBx, provided anchorage-independent growth ability in soft agar although its transactivation ability was abrogated. Microarray analysis revealed that fusion HBx deregulated endoplasmic reticulum (ER) stress response by modifying ATF3, ATF4, and ATF6 transcription. Interestingly, the effects of fusion HBx on ER stress signaling pathway were similar to those of C-terminal truncated HBx, but significantly different from those of wild HBx. Our findings suggest that the fusion HBx plays a significant role in hepatocarcinogenesis by modifying ER stress response and could be an attractive target for the treatment of HBV-induced HCC.

CPT1A-mediated fatty acid oxidation promotes cell proliferation via nucleoside metabolism in nasopharyngeal carcinoma

As the first rate-limiting enzyme in fatty acid oxidation (FAO), CPT1 plays a significant role in metabolic adaptation in cancer pathogenesis. FAO provides an alternative energy supply for cancer cells and is required for cancer cell survival. Given the high proliferation rate of cancer cells, nucleotide synthesis gains prominence in rapidly proliferating cells. In the present study, we found that CPT1A is a determining factor for the abnormal activation of FAO in nasopharyngeal carcinoma (NPC) cells. CPT1A is highly expressed in NPC cells and biopsies. CPT1A dramatically affects the malignant phenotypes in NPC, including proliferation, anchorage-independent growth, and tumor formation ability in nude mice. Moreover, an increased level of CPT1A promotes core metabolic pathways to generate ATP, inducing equivalents and the main precursors for nucleotide biosynthesis. Knockdown of CPT1A markedly lowers the fraction of 13C-palmitate-derived carbons into pyrimidine. Periodic activation of CPT1A increases the content of nucleoside metabolic intermediates promoting cell cycle progression in NPC cells. Targeting CPT1A-mediated FAO hinders the cell cycle G1/S transition. Our work verified that CPT1A links FAO to cell cycle progression in NPC cellular proliferation, which supplements additional experimental evidence for developing a therapeutic mechanism based on manipulating lipid metabolism.

Using VBIM Technique to Discover ARMC4/ODAD2 as a Novel Negative Regulator of NF-κB and a New Tumor Suppressor in Colorectal Cancer.

Since nuclear factor (NF) κB plays pivotal roles in inflammation and cancer, understanding its regulation holds great promise for disease therapy. Using the powerful validation-based insertional mutagenesis (VBIM) technique established by us previously, we discovered armadillo repeat-containing protein 4 (ARMC4)/outer dynein arm docking complex subunit 2 (ODAD2), a rarely studied protein known to date, as a novel negative regulator of NF-κB in colorectal cancer (CRC). High expression of ARMC4 downregulated the expression of NF-κB-dependent genes, dramatically reduced NF-κB activity, cellular proliferation, anchorage-independent growth, and migratory ability in vitro, and significantly decreased xenograft tumor growth in vivo. Co-immunoprecipitation experiments demonstrated that ARMC4 forms a complex with NF-κB. Importantly, the lower ARMC4 expression in patient tumors than normal tissues indicates its potential tumor suppressor function in CRC. Collectively, we uncovered a completely new facet of ARMC4 function by identifying it as a novel NF-κB negative regulator, thus uncovering ARMC4 as a potential new therapeutic target in CRC.

HBXIP induces anoikis resistance by forming a reciprocal feedback loop with Nrf2 to maintain redox homeostasis and stabilize Prdx1 in breast cancer

Anoikis resistance is an essential prerequisite for tumor metastasis, but the underlying molecular mechanisms remain unknown. Herein, we report that the oncoprotein hepatitis B X-interacting protein (HBXIP) is prominently upregulated in breast cancer cells following ECM detachment. Altering HBXIP expression can impair the anchorage-independent growth ability of tumor cells. Mechanistically, HBXIP, which binds to Kelch-like ECH-associated protein 1 (Keap1) to activate nuclear factor E2-related factor 2 (Nrf2), contains a cis-acting antioxidant response element (ARE) in the gene promoter and is a target gene of Nrf2. The HBXIP/Nrf2 axis forms a reciprocal positive feedback loop that reinforces the expression and tumor-promoting actions of each protein. In response to ECM detachment, Nrf2 reduces reactive oxygen species (ROS) accumulation, protects the mitochondrial membrane potential and increases cellular ATP, GSH and NADPH levels to maintain breast cancer cell survival. Meanwhile, the reinforcement of HBXIP induced by Nrf2 inhibits JNK1 activation by inhibiting ubiquitin-mediated degradation of Prdx1, which also plays an essential role in promoting ECM-detached cell survival. Furthermore, a strong positive correlation was identified between HBXIP expression and Prdx1 expression in clinical breast cancer tissues and TCGA Pan-Cancer Atlas clinical data of breast invasive carcinoma based on the cBioPortal cancer genomics database. Co-expression of HBXIP and Prdx1 predicts a poor prognosis for breast cancer patients. Collectively, our findings reveal a significant mechanism by which the HBXIP/Nrf2 feedback loop contributes to anoikis resistance by maintaining redox homeostasis and inhibiting JNK1 activation and support the likely therapeutic value of the HBXIP/Nrf2 axis in breast cancer patients.

Malignant growth of arsenic-transformed cells depends on activated Akt induced by reactive oxygen species

ABSTRACT Arsenic is an identified carcinogen for humans.In this study, chronic exposure of human hepatocyte L-02 to low-doses of inorganic arsenic caused cell malignant proliferation. Meanwhile, compared with normal L-02 cells, arsenic-transformed malignant cells, L-02-As displayed more ROS and significantly higher Cyclin D1 expression as well as aerobic glycolysis. Moreover, Akt activation is followed by the upregulation of Cyclin D1 and HK2 expression in L-02-As cells, since inhibition of Akt activity by Ly294002 attenuated the colony formation in soft agar and decreased the levels of Cyclin D1 and HK2. In addition, scavenging of ROS by NAC resulted in a decreased expression of phospho-Akt, HK2 and Cyclin D1, and attenuates the ability of anchorage-independent growth ofL-02-As cells, suggested that ROS mediated the Akt activation in L-02-As cells. In summary, our results demonstrated that ROS contributes to the malignant phenotype of arsenic-transformed human hepatocyte L-02-As via the activation of Akt pathway.

Abstract 2406: The essential role of ATP binding to the mitochondrial protein ATAD3A in driving oncogenesis of head and neck squamous cell carcinoma

Abstract Head and neck squamous cell carcinoma (HNSCC) represents only 4% of all cancers in the US, but the adverse impact of this disease on health quality is dramatic. There has been little improvement in HNSCC treatment outcomes in decades, and a better understanding of the molecular biology of HNSCC is urgently needed to facilitate the design of anti-HNSCC therapies. The mitochondrial ATPase family AAA-domain containing protein 3A (ATAD3A) has been demonstrated as an oncogene in breast and lung cancer. However, nothing has been reported regarding its role in HNSCC. We report here that loss of ATAD3A expression inhibits HNSCC cell growth as evidenced by reduced cell proliferation and decreased the ability of colony formation and anchorage-independent growth in soft agar, whereas gain of ATAD3A expression counteracts the observed effects. Overexpression of a Walker A dead mutant of ATAD3A (ATAD3AK358) leads to a suppression in HNSCC cell growth and lipids synthesis, suggesting a potent dominant-negative effect of defective ATP-binding of ATAD3A. In line with the in vitro data, overexpression of ATAD3A facilities tumor growth in an orthotopic mouse model of HNSCC. In contrast, inhibition of ATAD3A function by knockout of ATAD3A or expression of ATAD3AK358 induces significant repression of tumor growth. These findings indicate that the mitochondrial protein ATAD3A plays an oncogenic role in HNSCC, and abrogating its ATP-binding ability may represent a promising regimen for better treatment of patients with HNSCC. Citation Format: Liwei Lang, Tiffany Lam, Alex Chen, Chole Shay, Yong Teng. The essential role of ATP binding to the mitochondrial protein ATAD3A in driving oncogenesis of head and neck squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2406.

MiR-190 promotes malignant transformation and\xa0progression of human urothelial cells through CDKN1B/p27 inhibition

BackgroundAlthough miR-190 has been reported to be related to human diseases, especially in the development and progression of cancer, its expression in human bladder cancer (BC) and potential contribution to BC remain unexplored.MethodsRT-qPCR was used to verify the expression level of miR-190 and CDKN1B. Flow cytometry (FCM) assays were performed to detect cell cycle. Soft agar assay was used to measure anchorage-independent growth ability. Methylation-Specific PCR, Dual-luciferase reporter assay and Western blotting were used to elucidate the potential mechanisms involved.ResultsOur studies revealed that downregulation of the p27 (encoded by CDKN1B gene) protein is an important event related to miR-190, promoting the malignant transformation of bladder epithelial cells. miR-190 binds directly to CDKN1B 3’-UTR and destabilizes CDKN1B mRNA. Moreover, miR-190 downregulates TET1 by binding to the TET1 CDS region, which mediates hypermethylation of the CDKN1B promoter, thereby resulting in the downregulation of CDKN1B mRNA. These two aspects led to miR-190 inhibition of p27 protein expression in human BC cells. A more in-depth mechanistic study showed that c-Jun promotes the transcription of Talin2, the host gene of miR-190, thus upregulating the expression of miR-190 in human BC cells.ConclusionsIn this study, we found that miR-190 plays an important role in the development of BC. Taken together, these findings indicate that miR-190 may promote the malignant transformation of human urothelial cells by downregulating CDKN1B, which strengthens our understanding of miR-190 in regulating BC cell transformation.

EML4-ALK induces cellular senescence in mortal normal human cells and promotes anchorage-independent growth in hTERT-transduced normal human cells

BackgroundChromosomal inversions involving anaplastic lymphoma kinase (ALK) and echinoderm microtubule associated protein like 4 (EML4) generate a fusion protein EML4-ALK in non-small cell lung cancer (NSCLC). The understanding of EML4-ALK function can be improved by a functional study using normal human cells.MethodsHere we for the first time conduct such study to examine the effects of EML4-ALK on cell proliferation, cellular senescence, DNA damage, gene expression profiles and transformed phenotypes.ResultsThe lentiviral expression of EML4-ALK in mortal, normal human fibroblasts caused, through its constitutive ALK kinase activity, an early induction of cellular senescence with accumulated DNA damage, upregulation of p16INK4A and p21WAF1, and senescence-associated β-galactosidase (SA-β-gal) activity. In contrast, when EML4-ALK was expressed in normal human fibroblasts transduced with telomerase reverse transcriptase (hTERT), which is activated in the vast majority of NSCLC, the cells showed accelerated proliferation and acquired anchorage-independent growth ability in soft-agar medium, without accumulated DNA damage, chromosome aberration, nor p53 mutation. EML4-ALK induced the phosphorylation of STAT3 in both mortal and hTERT-transduced cells, but RNA sequencing analysis suggested that the different signaling pathways contributed to the different phenotypic outcomes in these cells. While EML4-ALK also induced anchorage-independent growth in hTERT-immortalized human bronchial epithelial cells in vitro, the expression of EML4-ALK alone did not cause detectable in vivo tumorigenicity in immunodeficient mice.ConclusionsOur data indicate that the expression of hTERT is critical for EML4-ALK to manifest its in vitro transforming activity in human cells. This study provides the isogenic pairs of human cells with and without EML4-ALK expression.