Anchorage-independent Colony Formation Research Articles

The long noncoding RNA MANCR to promote and stabilize triple negative breast cancer.

e13150 Background: Cancer remains a leading cause of death worldwide, despite many advances in cancer treatment over the past decade. Triple Negative Breast Cancer (TNBC) is among the highest with a poor prognosis. Early diagnosis and modern treatment regimens for breast cancer (BC) have led to a high disease-free survival rate. Still, survival decreases significantly for patients with metastatic disease. Long non-coding RNAs are among a recent class of epigenetic regulators that function in the nucleus to support the stability of the cells and maintain the fidelity of chromatin interactions. Our laboratory discovered the long noncoding RNA MANCR (LINC00704) as being upregulated in human BC tumors and this is indicative of a worse survival rate than in patients with low MANCR-expressing tumors. MANCR is aberrantly expressed in TNBC cells, and these cells are highly dependent on MANCR to retain their tumorigenic characteristics. Methods: Our functional in vitro studies in MDA-MB-231 TNBC cells used GapmerRs to knockdown MANCR. For in vivo studies, TNBC cells were injected into the 4th mammary fat pad of mice, allowed initial tumor formation, and then treated the animals with 2 nmol/g of a negative control or MANCR targeting GapmeR. We also identified genome interaction sites at single nucleotide resolution by chromatin isolation by RNA purification (ChIRP)-seq to determine the mechanism of MANCR activity in TNBC cells. Results: We found that MANCR knockdown promotes DNA damage and decreases cell proliferation, migration, anchorage-independent colony formation, transwell invasion, and overall survival. Additionally, targeting MANCR in animals with existing tumors drastically inhibited tumor growth and the end-point tumor mass over time. The MANCR GapmeR treatment also inhibited the ability of TNBC cells to circulate and disseminate to distant organs. After performing ChIRP-seq in the MDA-MB-231 cells, we identified 988 genome-wide binding sites that exhibit MANCR interactions, of which 79% are intergenic and 21% are genic regions. Furthermore, 127 MANCR ChIRP peaks were found to overlap with fragile sites in the genome, indicating MANCR provides stability to these sites. Conclusions: These data suggest that targeting MANCR has therapeutic potential for patients with “MANCR-high” TNBC tumors by disrupting genome stability. Indeed, our in vivo studies demonstrate that “MANCR-high” TNBC tumors require MANCR to rapidly grow and promote disease progression. Lastly, many of the MANCR-chromatin interactions identified were found in intergenic regions and overlap with fragile sites within the genome. Collectively these data strongly indicate that MANCR stabilizes the TNBC genome, and disrupting genome stability by targeting MANCR has therapeutic potential.

USP3 inhibition is Active Against Chemo-resistant Hepatocellular Carcinoma Anchorage-independent Growth via Suppressing Wnt/β-catenin.

USPs are a family of enzymes that regulate protein degradation, and their dysregulation has been implicated in the development and progression of cancer. This study aimed to determine whether ubiquitin-specific proteases 3 (USP3) could be a potential target for therapy in hepatocellular carcinoma (HCC), particularly in resistant HCC. This study systematically investigated the role of USP3 in HCC, with a focus on chemo-resistant HCC cells. The level of USP3 from clinical samples was measured using an ELISA assay. Cell proliferation, apoptosis, migration, and anchorage-independent colony formation assays were performed. Transfection was performed to knock down USP3 expression and measure β-catenin activity, and real-time PCR was used to measure levels of MYC and CYCLIN D1 genes. USP3 protein was upregulated in HCC tissues, but its upregulation was not associated with clinicopathology. USP3 knockdown had a similar inhibitory effect on growth in both sensitive and resistant HCC cells, did not affect migration, and induced apoptosis in sensitive but not resistant HCC cells. Furthermore, USP3 knockdown was more effective in suppressing anchorage-independent colony formation in chemoresistant HCC cells compared to their chemo-sensitive counterparts. Pearson correlation coefficient analysis revealed a strong positive correlation between USP3 and CTNNB1, and consistently, USP3 knockdown reduced the levels and activities of β-catenin in HCC cells. Using a Wnt activator (lithium) in rescue studies significantly reversed the inhibitory effects of USP3 knockdown. The findings suggest that inhibiting USP3 is an effective strategy against cancer stem cells and chemo-resistant HCC cells.

Dexrazoxane inhibits the growth of esophageal squamous cell carcinoma by attenuating SDCBP/MDA-9/syntenin-mediated EGFR-PI3K-Akt pathway activation

Syndecan-binding protein (SDCBP) was reported to stimulate the advancement of esophageal squamous cell carcinoma (ESCC) and could potentially be a target for ESCC treatment. There is a growing corpus of research on the anti-tumor effects of iron chelators; however, very few studies have addressed the involvement of dexrazoxane in cancer. In this study, structure-based virtual screening was employed to select drugs targeting SDCBP from the Food and Drug Administration (FDA)-approved drug databases. The sepharose 4B beads pull-down assay revealed that dexrazoxane targeted SDCBP by interacting with its PDZ1 domain. Additionally, dexrazoxane inhibited ESCC cell proliferation and anchorage-independent colony formation via SDCBP. ESCC cell apoptosis and G2 phase arrest were induced as measured by the flow cytometry assay. Subsequent research revealed that dexrazoxane attenuated the binding ability between SDCBP and EGFR in an immunoprecipitation assay. Furthermore, dexrazoxane impaired EGFR membrane localization and inactivated the EGFR/PI3K/Akt pathway. In vivo, xenograft mouse experiments indicated that dexrazoxane suppressed ESCC tumor growth. These data indicate that dexrazoxane might be established as a potential anti-cancer agent in ESCC by targeting SDCBP.

Abstract 3033: Oncogenic ETS transcription factors avoid repression by EZH2 and FOXO1 in prostate cancer and Ewing sarcoma

Abstract ETS transcription factors play roles throughout development, aiding in hematopoiesis, blood vessel formation and cell fate. The ETS family is composed of 28 members, all of which share an ETS DNA-binding domain. Chromosomal rearrangements that lead to the overexpression of specific ETS promote oncogenic transformation and tumor development. More than half of prostate tumors are driven by aberrant expression of an ETS protein. Our lab has demonstrated that oncogenic ETS form essential interactions with a ubiquitous RNA-binding protein, EWS, to promote prostate tumorigenesis. A similar mechanism exists in Ewing sarcoma (ES). ES tumors are driven by the expression EWS/ETS fusion proteins. This project focuses on the similarities and differences between oncogenic ETS in prostate cancer and EWS/ETS fusions in Ewing sarcoma. We compared biological functions of the most common oncogenic ETS in prostate cancer, ERG, and the most common fusion in ES, EWS/FLI1. Both ERG and EWS/FLI1 promoted migration and clonogenic survival in normal prostate epithelial cell lines, RWPE1 and PNT2. These data suggest that the EWS-ERG complex and EWS/FLI1 fusion protein can function similarly in prostate cells. Knockdown of endogenous EWS/FLI1 in the ES cell line, A673, reduced anchorage-independent colony formation in soft agar. Rescue with exogenous EWS/FLI1 or EWS/ERG restored colony formation relative to control. Wildtype ERG was unable to rescue colony formation in A673. This suggests that ERG and EWS/FLI1 function differently in A673 cells. Pulldown assays from A673 lysates reveal that ERG interacts with EZH2 and FOXO1. Our lab has established that ERG acts as a transcriptional repressor through the formation of an ERG-EZH2-PRC2 complex. Others demonstrate that FOXO1 represses ERG activity by reducing its recruitment to the target sites. Both the N-terminal truncation of ERG and phosphorylation of ERG at S96 disrupted these interactions and rescued anchorage independent growth in A673 ES cells. These data suggest that EWS/ETS fusions avoid transcriptional repression in Ewing tumors due to loss of the N-terminus of the ETS protein. Citation Format: Nicholas F. Downing, Kaitlyn M. Mills, Peter C. Hollenhorst. Oncogenic ETS transcription factors avoid repression by EZH2 and FOXO1 in prostate cancer and Ewing sarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3033.

Non-chemotherapy adjuvant agents in TP53 mutant Ewing sarcoma

Ewing sarcoma (EWS) is a malignant tumor arising in bone or soft tissue that occurs in adolescent and young adult patients as well as adults later in life. Although non-metastatic EWS is typically responsive to treatment when newly diagnosed, relapsed cases have an unmet need for which no standard treatment approach exists. Recent phase III clinical trials for EWS comparing 7 vs 5 chemotherapy drugs have failed to improve survival. To extend the durability of remission for EWS, we investigated 3 non-chemotherapy adjuvant therapy drug candidates to be combined with chemotherapy. The efficacy of these adjuvant drugs was investigated via anchorage-dependent growth assays, anchorage-independent soft-agar colony formation assays and EWS xenograft mouse models. Enoxacin and entinostat were the most effective adjuvant drug in both long-term in vitro and in vivo adjuvant studies. In the context that enoxacin is an FDA-approved antibiotic, and that entinostat is an investigational agent not yet FDA-approved, we propose enoxacin as an adjuvant drug for further preclinical and clinical investigation in EWS patients.

Abstract 5012: Characterizing the functional significance of PDGFRAK385I and PDGFRAK385L extracellular domain mutations in the newly defined myxoid glioneuronal tumor

Abstract In 2021, the World Health Organization (WHO) approved new diagnostic guidelines that stratify central nervous system (CNS) tumors based on molecular, transcriptomic, and epigenetic analysis instead of relying solely on phenotypic characterization and added twenty-two new CNS tumor entities based on these guidelines. Our focus is on one of these newly defined entities—myxoid glioneuronal tumors—a slow growing, mucinous glial tumor defined by a pathognomonic dinucleotide substitution in the extracellular domain of PDGFRA p.K385I/L. PDGFRA p.K385I/L remains a variant of unknown significance, however, constitutive activation of PDGFRA is well established as a pharmacologically actionable, oncogenic driver present in a variety of tumor types. Here we report the functional characterization of PDGFRAK385I and PDGFRAK385L by assessing transforming potential using Ba/F3 cells and immortalized human astrocytes. Our results demonstrate that both p.K385I and K385L substitutions are oncogenic, driving cytokine-independent Ba/F3 cell growth and anchorage-independent colony formation. Western blot analysis of downstream cellular signaling pathways in the absence of PDGF-ligand further confirm the activating nature of these mutations, showing robust phosphorylation of PDGFRA and constitutive phosphorylation of downstream signaling effectors ERK1/2, SHP2, and STAT3. To assess whether PDGFRAK385I and PDGFRAK385L are pharmacologically actionable, we tested multiple tyrosine kinase inhibitors with known activity against PDGFRA aberrant cancers using our mutant-transformed PDGFRA Ba/F3 cells. We found that the PDGFRAK385I and PDGFRAK385L mutants were sensitive to inhibitors axitinib, AZD-3229, and avapritinib at therapeutically relevant concentrations. Further, these mutants showed resistance to imatinib, nilotinib, and crenolanib underscoring the importance of pharmacogenomic investigation. No appreciable difference in sensitivity or resistance profiles was observed between the two mutants. In summary, our findings indicate that these previously uncharacterized p.K385I/L extracellular domain mutations in PDGFRA are oncogenic and represent a pharmacologically actionable target that could be harnessed to increase therapeutic options in the setting of myxoid glioneuronal tumors. Citation Format: Catherine Z. Beach, Romel Somwar, Matthew D. Wood, Monika A. Davare. Characterizing the functional significance of PDGFRAK385I and PDGFRAK385L extracellular domain mutations in the newly defined myxoid glioneuronal tumor. [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 5012.

Abstract 1176: Quantitative integration of PIK3CA hotspots and paralogy identifies occult oncogenic mutants in PIK3CD

Abstract The majority of somatic variants identified by tumor genomic profiling are low frequency alterations of unknown biologic and clinical significance. To facilitate the systematic identification of likely oncogenic versus benign somatic mutations, there has been a growing interest in harnessing additional computationally amenable metrics such as sequence paralogy. Here, we developed a novel paralogy-directed computational methodology called Enriched Paralogy to identify Occult Cancer Hotspots (EPOCH), which calculates the significance of mutational recurrence at aligned positions in evolutionarily related genes to prioritize likely oncogenic mutations for in depth functional characterization. We validated the utility of EPOCH using sequencing data from a cohort of 52,676 tumor/normal pairs, with a focus on identifying likely oncogenic mutations in the well characterized PIK3CA (p110α) class 1a PI3K isoform and the lesser characterized PIK3CD (p110δ) isoform. p110δ mutants nominated as likely oncogenic by EPOCH induced AKT pathway activation, enhanced anchorage-independent colony formation, and demonstrated allele-specific dependencies on p85 regulatory protein binding. The potency of PI3K inhibitors against p110δ mutants was at best equal to or less than wildtype p110δ. In sum, we present the novel algorithm EPOCH that integrates paralogy to extend the utility of current recurrence-based precision oncology predictions and to automate the functional interpretation of less common mutations. Our work identifies novel oncogenic and targetable p110δ mutants and supports the inclusion of PIK3CD in targeted sequencing panels despite the relative rarity of mutations in this gene. The therapeutic studies herein also provide the rationale for the development and clinical testing of isoform- or mutant-specific p110δ inhibitors for patients with rare, yet druggable, oncogenic p110δ mutations. Citation Format: Arijh Elzein, Alexander N. Gorelick, Ino de Bruijn, Barry S. Taylor, Aphrothiti J. Hanrahan, David B. Solit. Quantitative integration of PIK3CA hotspots and paralogy identifies occult oncogenic mutants in PIK3CD [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 1176.

Abstract 3564: SNAI2 enhances oncogenesis in malignant peripheral nerve sheath tumors

Abstract Background: MPNSTs are highly aggressive soft tissue sarcomas. Recurrent genetic mutations have been linked to its tumorigenesis, including the loss of functional polycomb repressive complex 2 (PRC2). This results in an altered transcription landscape characterized by the global loss of methylation on histone H3 lysine 27 (H3K27me3) and increased super-enhancer (SE) -associated histone acetylation. We have previously identified SNAI2 as a core SE-driven transcription factor (TF) that is essential for the growth of MPNST. Although SNAI2 is known to be critical for oncogenic processes, including epithelial-to-mesenchymal transition (EMT) and dedifferentiation, its role in maintaining MPNST survival through transcriptomic and epigenetic regulation has not been explored. Methods: Using CRISPR mediated knockout (KO), we targeted the SNAI2 DNA binding domain and confirmed KO via western blot, followed by in vitro phenotypic characterization, including 2D growth assays, anchorage-independent colony formation assays, and scratch assays. Additionally, an integrative analysis of SNAI2 genomic distribution and the transcriptomic effect of its KO was performed using chromatin immunoprecipitation coupled with DNA sequencing (ChIPseq) and RNA sequencing (RNAseq). Finally, an inducible re-expression system was employed to examine the effects on the chromatin landscape with SNAI2 rescue. Results: Genetic loss of SNAI2 slowed the growth of MPNST cells by 50% in comparison to the control. In vitro tumorigenic assays revealed that SNAI2 KO diminished the cells’ capacity in invasion but not in anchorage-independent cell growth. Analysis of the RNAseq results revealed that SNAI2 loss upregulated 790 genes and downregulated 1623 genes (log2fold change> 1, p<0.01), indicating a dominant transcriptional activation role. Gene Set Enrichment Analysis of these SNAI2-regulated genes revealed upregulation of hallmark Myc targets (normalized enrichment score (NES)=2.6, FDR=0.0), whilst genes involved in response to alpha interferon proteins were downregulated (NES=-1.87, FDR=0.002). Interestingly, genes defining EMT were upregulated (NES=1.6, FDR=0.006) in cells upon SNAI2 loss, contrasting its known repressive role in this biological process in other systems. Through integrative analysis of the RNAseq and ChIPseq data, we demonstrate SNAI2 binding to promoters of its regulated targets. Downstream targets of interest include CRELD1, a gene involved in cell adhesion, where SNAI2 KO caused loss of promoter binding and gene downregulation (p<0.001). Conclusion: SNAI2 is an essential SE-driven TF in MPNST cells. Transcriptomic and genomic profiling of SNAI2 through loss- and gain-of-function experiments revealed that it is a critical TF that is involved in key biological processes. Future efforts will focus on designing methods to employ targeted degradation of this essential TF and test preclinical efficacy in treating MPNST. Citation Format: Hilda Jafarah, Béga Murray, Jack Shern, Xiyuan Zhang. SNAI2 enhances oncogenesis in malignant peripheral nerve sheath tumors. [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 3564.

Targeting mitochondrial transcription factor A sensitizes pancreatic cancer cell to gemcitabine

BackgroundThe survival of pancreatic cancer cells, particularly cancer stem cells which are responsible for tumor relapse, depends on mitochondrial function. Mitochondrial transcription factor A (TFAM) is critical for the regulation of mitochondrial DNA and thus mitochondrial function. However, the possible involvement of TFAM in pancreatic cancer is unknown. MethodsHuman samples were obtained from pancreatic cancers and their adjacent tissues; human pancreatic cell lines were cultured in RPMI1640 medium. TFAM expressions in pancreatic tissues and cultured cells were determined using immunohistochemistry, ELISA, and reverse transcription polymerase chain reaction (RT-PCR). The effect of TFAM on cell growth, migration, colony formation and apoptosis were evaluated. Mitochondrial biogenesis in pancreatic cancer and normal cells were examined. ResultsThe majority of pancreatic cancer tissues exhibited higher TFAM expression compared to the adjacent counterparts. Consistently, TFAM mRNA and protein levels were higher in pancreatic cancer cell lines than in immortalized normal pancreatic epithelial cells. There was no difference on TFAM level between gemcitabine-sensitive and resistant pancreatic cancer cells. Functional analysis demonstrated that TFAM overexpression activated pancreatic normal and tumor cells whereas TFAM inhibition effectively inhibited the growth of pancreatic cancer cells. TFAM inhibition enhanced gemcitabine's cytotoxicity and suppressed growth, anchorage-independent colony formation and survival of gemcitabine-resistant pancreatic cancer cells. Mechanistic studies showed that TFAM inhibition resulted in remarkable mitochondrial dysfunction and energy crisis followed by oxidative stress. The basal mitochondrial biogenesis level correlated well with TFAM level in pancreatic cancer cells. ConclusionsTFAM played essential roles in pancreatic cancer via regulating mitochondrial functions which highlighted the therapeutic value of inhibiting TFAM to overcome gemcitabine resistance.

Orobol, 3′-hydroxy-genistein, suppresses the development and regrowth of cutaneous SCC

Chronic solar ultraviolet exposure is a major risk factor for cutaneous squamous cell carcinoma (cSCC), which is the second most common type of skin cancer. Our previous data showed that total protein and phosphorylation levels of T-LAK cell-originated protein kinase (TOPK) were enhanced in solar-simulated light (SSL)-induced skin carcinogenesis and overexpressed in actinic keratosis (AK) and cSCC human skin tissues compared to those in matched normal skin. Thus, targeting TOPK activity could be a helpful approach for treating cSCC. Our data showed that orobol directly binds to TOPK in an ATP-independent manner and inhibits TOPK kinase activity. Furthermore, orobol inhibited anchorage-independent colony formation by SCC12 cells in a dose-dependent manner. After discontinuing the treatment, patients commonly return to tumor-bearing conditions; therefore, therapy or intermittent dosing of drugs must be continued indefinitely. Thus, to examine the efficacy of orobol against the development and regrowth of cSCC, we established mouse models including prevention, and therapeutic models on the chronic SSL-irradiated SKH-1 hairless mice. Early treatment with orobol attenuates chronic SSL-induced cSCC development. Furthermore, orobol showed therapeutic efficacy after the formation of chronic SSL irradiation-induced tumor. In the mouse model with intermittent dosing of orobol, our data showed that re-application of orobol is effective for reducing tumor regrowth after discontinuation of treatment. Moreover, oncogenic protein levels were significantly attenuated by orobol treatment in the SSL-stimulated human skin. Thus, we suggest that orobol, as a promising TOPK inhibitor, could have an effective clinical approach to prevent and treat the development and regrowth of cSCC.

Veratramine Inhibits the Cell Cycle Progression, Migration, and Invasion via ATM/ATR Pathway in Androgen-Independent Prostate Cancer.

Prostate cancer (PC) is the second leading cause of cancer-related death among men. Treatment of PC becomes difficult after progression because PC that used to be androgen-dependent becomes androgen-independent prostate cancer (AIPC). Veratramine, an alkaloid extracted from the root of the Veratrum genus, has recently been reported to have anticancer effects that work against various cancers; however, its anticancer effects and the underlying mechanism of action in PC remain unknown. We investigated the anticancer effects of veratramine on AIPC using PC3 and DU145 cell lines, as well as a xenograft mouse model. The antitumor effects of veratramine were evaluated using the CCK-8, anchorage-independent colony formation, trans-well, wound healing assays, and flow cytometry in AIPC cell lines. Microarray and proteomics analyses were performed to investigate the differentially expressed genes and proteins induced by veratramine in AIPC cells. A xenograft mouse model was used to confirm the therapeutic response and in vivo efficacy of veratramine. Veratramine dose dependently reduced the proliferation of cancer cells both in vitro and in vivo. Moreover, veratramine treatment effectively suppressed the migration and invasion of PC cells. The immunoblot analysis revealed that veratramine significantly downregulated Cdk4/6 and cyclin D1 via the ATM/ATR and Akt pathways, both of which induce a DNA damage response that eventually leads to G1 phase arrest. In this study, we discovered that veratramine exerted antitumor effects on AIPC cells. We demonstrated that veratramine significantly inhibited the proliferation of cancer cells via G0/G1 phase arrest induced by the ATM/ATR and Akt pathways. These results suggest that veratramine is a promising natural therapeutic agent for AIPC.

Silibinin induces oral cancer cell apoptosis and reactive oxygen species generation by activating the JNK/c-Jun pathway.

Background: Oral cancer is one of the most prevalent malignant tumors worldwide. Silibinin has been reported to exert therapeutic effects in various cancer models. However, its mechanism of action in oral cancer remains unclear. We aimed to examine the molecular processes underlying the effects of silibinin in oral cancer in vitro and in vivo as well as its potential anticancer effects. Next, we investigated the molecular processes underlying both in vitro and in vivo outcomes of silibinin treatment on oral cancer. Methods: To investigate the effects of silibinin on the growth of oral cancer cells, cell proliferation and anchorage-independent colony formation tests were conducted on YD10B and Ca9-22 oral cancer cells. The effects of silibinin on the migration and invasion of oral cancer cells were evaluated using transwell assays. Flow cytometry was used to examine apoptosis, cell cycle distribution, and accumulation of reactive oxygen species (ROS). The molecular mechanism underlying the anticancer effects of silibinin was explored using immunoblotting. The in vivo effects of silibinin were evaluated using a Ca9-22 xenograft mouse model. Results: Silibinin effectively suppressed YD10B and Ca9-22 cell proliferation and colony formation in a dose-dependent manner. Moreover, it induced cell cycle arrest in the G0/G1 phase, apoptosis, and ROS generation in these cells. Furthermore, silibinin inhibited the migration and invasion abilities of YD10B and Ca9-22 cells by regulating the expression of proteins involved in the epithelial-mesenchymal transition. Western blotting revealed that silibinin downregulated SOD1 and SOD2 and triggered the JNK/c-Jun pathway in oral cancer cells. Silibinin significantly inhibited xenograft tumor growth in nude mice, with no obvious toxicity. Conclusions: Silibinin considerably reduced the development of oral cancer cells by inducing apoptosis, G0/G1 arrest, ROS generation, and activation of the JNK/c-Jun pathway. Importantly, silibinin effectively suppressed xenograft tumor growth in nude mice. Our findings indicate that silibinin may be a promising option for the prevention or treatment of oral cancer.

Proteome derangement in malignant epithelial cells and its stroma following exposure to 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone.

Discovering novel changes in the proteome of malignant lung epithelial cells and/or the tumor-microenvironment is paramount for diagnostic, prognostic, and/or therapy development. A time-dependent 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced mouse lung tumor model was used to screen the proteome of lung tumors. NNK-transformed human lung epithelial BEAS-2B cells were then established to evaluate the epithelial cell-specific protein changes. A duration-dependent increase of tumor burden was observed in NNK-treated mice, 2/12 (17%), 8/12 (67%), 9/12 (75%), and 10/10 (100%) at weeks 8, 12, 16, and 20 after the NNK exposure, respectively. A total of 25 differentially expressed proteins (≥ twofold change), predominantly structural, signaling, and metabolic proteins, were detected by two-dimensional difference gel electrophoresis and identified by mass spectrometry. Calregulin, ezrin, histamine releasing factor (HRF), and inorganic pyrophosphatase 1 (PPA1) exhibited changes and were further confirmed via immunoblotting. In addition, immunohistochemistry (IHC) analysis indicated upregulated E-cadherin and decreased vimentin expression in epithelial cells of tumor tissues. Acquisition of a neoplastic phenotype in NNK-transformed BEAS-2B cells was demonstrated by enhanced wound closure and increased anchorage independent colony formation. In transformed BEAS-2B cells, protein expression of E-cadherin, ezrin, and PPA1 (but not calregulin and HRF) was upregulated, as was observed in tumor tissues IHC staining using mouse lung tumor tissues further revealed that HRF upregulation was not lung epithelial cell specific. Altogether, tumorigenesis after NNK exposure may be initiated by protein dysregulation in lung epithelial cells together with proteome derangement derived from other cell types existing in the tumor-microenvironment.

TMET-15. CYTOCHROME C OXIDASE MEDIATES CELLULAR IRON HOMEOSTASIS AND RADIORESISTANCE IN GLIOBLASTOMA

Abstract Defining the molecular mechanism(s) responsible for the adaptive radioresistance in glioblastoma (GBM) is necessary for the development of effective treatment options. The cellular labile iron pool (LIP) is very important for determining the cellular response to radiation, as it contributes to radiation-induced production of reactive oxygen species (ROS). Recently, cytochrome c oxidase (CcO), a mitochondrial heme-containing enzyme also involved in regulating ROS production, was found to be involved in GBM chemoresistance. However, the role of LIP and CcO in GBM radioresistance is not known. Herein, we tested the hypothesis that CcO-mediated alterations in the level of labile iron contribute to adaptive radioresistance. Using an in vitro model of GBM adaptive radioresistance, we found an increase in CcO activity in radioresistant cells that associated with a decrease in the cellular LIP (4.1-fold), decrease in lipid peroxidation (2-fold), and a switch in the CcO subunit 4 (COX4) isoform expression, from COX4-2 to COX4-1. Furthermore, knockdown of COX4-1 in radioresistant GBM cells decreased CcO activity and restored radiosensitivity, whereas overexpression of COX4-1 in radiosensitive cells increased CcO activity and rendered the cells radioresistant. We further observed that radioresistant cells has increased expression of mitoferrin-1, a protein that facilitates the incorporation of iron into mitochondria. Overexpression of mitoferrin-1 in glioma cells increases the activity of mitochondrial protein complexes, decreases the cellular labile iron pool (p< 0.05), and decreases the production of 4-hydroxy nonenal (4-HNE), a lipid peroxidation product. Furthermore, overexpression of mitoferrin-1 significantly increases the anchorage independent colony formation in soft agar assay (p< 0.01). Moreover, mitoferrin-1 overexpressing cells implanted orthotopically in the brain of nude mice significantly decreased survival compared to wild type (p < 0.01). These results indicate that manipulation of cellular and mitochondrial iron homeostasis may provide a strategy to improve therapeutic outcome in patients with GBM.

A novel glycosylated indolocarbazole derivative LCS1269 effectively inhibits growth of human cancer cells in vitro and in vivo through driving of both apoptosis and senescence by inducing of DNA damage and modulating of AKT/mTOR/S6K and ERK pathways

In recent decades, indolocarbazole glycosides containing sugar moieties have attracted attention due to their diverse anti-tumor activities. In the present study, a series of new indolo [2,3-a]pyrrolo [3,4-c]carbazole derivatives were synthesized for the first time. First of all, we have shown that compound 6e (LCS1269) had the most pronounced effect on inhibiting tumor growth in the transferable solid and non-solid murine tumors as compared with other synthesized indolocarbazole derivatives. The results of the in vivo nude mice xenoraft study also confirmed that LCS1269 treatment strongly suppressed the growth of human colon cancer SW620 xenografts. It is important to note that the antiproliferative activity of LCS1269 against three human cancer cell lines (MCF-7, HCT-116 and A549) was considerably higher than that against the non-tumor cell lines (immortalized breast cells and normal embryonic fibroblasts). Furthermore, the treatment of MCF-7, HCT-116 and A549 cells with LCS1269 caused the statistically significant inhibition of anchorage-dependent and anchorage-independent colony formation. We further revealed that LCS1269 treatment of investigated human cancer cells resulted in the DNA damage and G2/M cell cycle arrest followed by the decrease of mitochondrial membrane potential with subsequent initiation of intrinsic apoptosis and the triggering of senescence via p53-dependent mechanisms. In addition, our western blotting findings and molecular docking data suppose that LCS1269 could at least partially attenuate cancer cells growth by modulation of AKT/mTOR/S6K and ERK signaling pathways. Therefore, we concluded that LCS1269 might be the promising compound for implementation and probable use in the clinical practice.

Abstract 5951: Synergistic efficacy of sulforaphane and progesterone against endometrial cancer

Abstract Introduction: Worldwide, endometrial cancer (EC) is the most common gynecological malignancy with increasing rate of incidence and mortality. While progesterone-based hormone therapy is a well-accepted conservative therapeutic option for EC patients, loss of progesterone receptor (PR) in long-term treatment leading to hormonal resistance and disease recurrence is still an area of concern. We demonstrated potent anti-cancerous activity of sulforaphane against EC in vitro and in vivo and hypothesized that it will activate PR and overcome progesterone therapy limitations. The purpose of this study was to evaluate the interaction of sulforaphane and progesterone against EC. Methods: The in vitro synergistic interaction between sulforaphane and progesterone was investigated with isobologram analysis of plotting MTT metabolic viability assay results of EC cells treated with drugs individually and in combination using CompuSyn software. ATP, soft-agar colony formation and invasion assays were performed to evaluate the combined drug effects on cell viability, anchorage independent colony formation and invasion properties, respectively. Mitochondrial membrane potential and caspase-3 activity were measured by JC-1 and caspase-3 detection ELISA kit, respectively. Protein expression was accessed by western blot. Progesterone resistant EC cells were developed by treating cells with 30µM of progesterone for more than 3 months. Results: Sulforaphane demonstrated strong synergy or additive effects with progesterone in the EC cell lines tested. Sulforaphane in combination with progesterone significantly decreased levels of cellular ATP, anchorage-independent colony formation, invasion and mitochondrial membrane potential. Furthermore, combination of sulforaphane and progesterone increased caspase-3 activity as compared to individual drug or controls, suggesting induction of apoptosis. Western blot results demonstrated an increased expression of cleaved PARP, with reduced expression of total caspase-3 and PCNA in the combination groups as compared to control and individual drugs. Sulforaphane alone or in combination showed increased expression of PR-A while it had minimal effects on PR-B. Further, in all EC cell lines, the combination of sulforaphane and progesterone demonstrated upregulation of PR-A/PR-B ratio. The progesterone resistant cells demonstrated less sensitivity to progesterone as compared to parent cell lines, however it was found to be sensitive to sulforaphane. Conclusions: Sulforaphane demonstrated synergistic activity with progesterone leading to increased apoptosis and reduced proliferation. Furthermore, sulforaphane exhibited potent toxicity to progesterone resistance cells. Sulforaphane in combination with progesterone could overcome progesterone therapy limitation by re-activation of PR. Funding: Administrative Suppl (P30CA225520) and PHF (GRF00005456) Citation Format: Rajani Rai, Swati Choudhary, Doris M. Benbrook, Vishal Chandra. Synergistic efficacy of sulforaphane and progesterone against endometrial cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5951.

Abstract 228: Depletion of stem-loop binding protein and elevation of polyadenylation of histone 3.1 contribute to malignant cell transformation induced by bisphenol A

Abstract Introduction: Bisphenol A (BPA) is a pervasive chemical exposure in the US and has been linked to adverse health effects in humans and mainly identified as an endocrine disruptor. However, recent studies suggests that all plastics including our daily usages for food/drink containers may leach chemicals if they are scratched or heated or stored long term and strongly suggests that at certain exposure levels of BPA in these products, may cause cancers including breast, lung, and ovarian cancers in humans. Although there are few studies about breast, lung and ovarian cancers, with BPA exposure there is an urgent need to focus on the BPA’s carcinogenic activity in the lung. Because lung cancers can progress to life threatening events and short life span once it is diagnosed, identifying the mechanism that specifically inhibits/prevents lung cancers invasion and related morbidity is of tremendous importance for reducing mortality. Therefore, in this study, we investigated the carcinogenicity of BPA using human bronchial epithelial cells. Experimental methods: To determine whether BPA alters canonical histone mRNA processing in vitro, we measured levels of polyadenylation (polyA) of canonical histone (H)3.1 mRNA as well as protein expression of Stem-loop binding protein (SLBP), and H3 protein in human bronchial epithelial BEAS-2B cells exposed to various concentrations of BPA for 96 h. Furthermore, BEAS-2B cells were chronically exposed to low doses of BPA, the cell transformation assay was performed in an anchorage-independent growth and colony formation was assessed. Arsenic was used as a positive control because our laboratory previously demonstrated that arsenic-induced polyA of H3.1 mRNA, by depletion of SLBP in vitro and that polyA of H3.1 mRNA enhanced tumor formation in nude mice. Results: Our results showed that exposure of BEAS-2B cells to BPA depleted SLBP, induced polyA of canonical histone mRNAs, and upregulated H3 protein. The results from real-time quantitative PCR showed that BPA exposure increased level of polyA H3.1 mRNA. Furthermore, our findings from an anchorage-independent growth assay also indicate that exposure of BEAS-2B cells to low doses of BPA induced malignant cell transformation. Conclusions: The present study demonstrated that chronic exposure of the cells to BPA causes malignant cell transformation, indicating that BPA is a potent human carcinogen to induce lung cancer. Our study also demonstrated that the loss of SLBP and gain of polyA H3.1 mRNA play an important role in BPA-induced carcinogenesis. Citation Format: Arul Veerappan, Zhou Zhang, Max Costa. Depletion of stem-loop binding protein and elevation of polyadenylation of histone 3.1 contribute to malignant cell transformation induced by bisphenol A [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 228.

Modification of ERα by UFM1 Increases Its Stability and Transactivity for Breast Cancer Development.

The post-translational modification (e.g., phosphorylation) of estrogen receptor α (ERα) plays a role in controlling the expression and subcellular localization of ERα as well as its sensitivity to hormone response. Here, we show that ERα is also modified by UFM1 and this modification (ufmylation) plays a crucial role in promoting the stability and transactivity of ERα, which in turn promotes breast cancer development. The elevation of ufmylation via the knockdown of UFSP2 (the UFM1-deconjugating enzyme in humans) dramatically increases ERα stability by inhibiting ubiquitination. In contrast, ERα stability is decreased by the prevention of ufmylation via the silencing of UBA5 (the UFM1-activating E1 enzyme). Lys171 and Lys180 of ERα were identified as the major UFM1 acceptor sites, and the replacement of both Lys residues by Arg (2KR mutation) markedly reduced ERα stability. Moreover, the 2KR mutation abrogated the 17β-estradiol-induced transactivity of ERα and the expression of its downstream target genes, including pS2, cyclin D1, and c-Myc; this indicates that ERα ufmylation is required for its transactivation function. In addition, the 2KR mutation prevented anchorage-independent colony formation by MCF7 cells. Most notably, the expression of UFM1 and its conjugating machinery (i.e., UBA5, UFC1, UFL1, and UFBP1) were dramatically upregulated in ERα-positive breast cancer cell lines and tissues. Collectively, these findings implicate a critical role attributed to ERα ufmylation in breast cancer development by ameliorating its stability and transactivity.

IDH1 Mutation Induces HIF-1α and Confers Angiogenic Properties in Chondrosarcoma JJ012 Cells.

Chondrosarcoma is a group of primary bone cancers that arise from transformed cells of chondrocytic lineage. Tumor recurrence and metastasis are devastating for patients with chondrosarcoma since there are no effective treatment options. IDH mutations occur in over 50% of tumors from patients with conventional or dedifferentiated chondrosarcomas and represent an attractive target for therapy. However, their role in the pathogenesis of chondrosarcoma remains largely unknown. In this study, we sought to determine the association of IDH mutation and HIF-1α in chondrosarcoma. We used the chondrosarcoma JJ012 cell line and its derived CRISPR/Cas9 mutant IDH1 (IDH1mut) knockout (KO) cells. RNA-Seq data analysis revealed downregulation of several HIF-1α target genes upon loss of IDH1mut. This was associated with reduced HIF-1α levels in the IDH1mut KO cells and tumors. Loss of IDH1mut also attenuated the expression of angiogenic markers in tumor tissues and abrogated the angiogenic capacity of JJ012 cells. Moreover, we observed that exogenous expression of HIF-1α significantly promoted anchorage-independent colony-formation by IDH1mut KO cells. These results suggest IDH1 mutation confers angiogenic and tumorigenic properties of JJ012 cells by inducing HIF-1α. Thus, the HIF pathway represents a promising candidate for combinatorial regimens to target IDH1 mutated chondrosarcomas.

Anti-Proliferative and Pro-Apoptotic Effects Of Dipsacus Asperoides in a Cellular Model for Triple-Negative Breast Cancer

Background: Triple negative breast cancer (TNBC) lacks expressions of estrogen receptor-α (ER-α), progesterone receptor (PR) and amplified human epidermal growth factor receptor-2 (HER-2). Current treatment for TNBC includes anthracyclin, taxol and cisplatin-based conventional chemotherapy and survival pathway PARP, PI3K, AKT and mTOR selective targeted therapy. These treatments exhibit dose-limiting systemic toxicity and presence of drug resistant cancer stem cells, which highlight the need for identification of efficacious testable alternatives that are not toxic to non-tumorigenic cells. Dipsacus asperoides (DA) is a Chinese nutritional herb and its root represents a common ingredient in Chinese herbal formulations used in women for estrogen related health issues, osteoporosis and breast diseases. This study aims to investigate the growth inhibitory effects of DA, and to detect mechanisms for its efficacy. Methods: Human mammary carcinoma derived triple negative MDA-MB-231 cell line represented the TNBC model. Non-fractionated aqueous extract from DA represented the test agent. Anchorage dependent growth, anchorage independent (AI) colony formation and cell cycle progression quantified growth inhibition. Western blot-based analysis for inhibition of RAS, PI3K and AKT and RB signaling identified mechanistic leads. Results: Treatment with DA induced a dose dependent cytostatic growth arrest (IC50:15 µg/ml; IC90: 30 µg/ml), reduced AI growth and inhibited cell cycle progression via G2/M arrest. DA affected the RAS, PI3K, AKT and RB signaling pathways, and functioned as a natural inhibitor of cyclin dependent kinase 4/6. Cellular apoptosis paralleled increase in pro-apoptotic Caspase 3/7 activity. Conclusion: These results demonstrate that DA inhibited growth, affected cell cycle progression, induced apoptosis and inhibited cancer cell survival pathways. This study validates a mechanism-based approach to identifying testable substitutes for secondary prevention/therapy of TNBC.