Reduced Tumor Formation Research Articles

Long noncoding RNA CERS6-AS1 modulates glucose metabolism and tumor progression in hepatocellular carcinoma by promoting the MDM2/p53 signaling pathway

Hepatocellular carcinoma (HCC) is one of the most serious malignant cancers and has a high fatality rate. However, clinical strategies for the effective treatment of HCC remain lacking. Long non-coding RNAs (lncRNAs) with aberrant expression have been closely correlated with the occurrence and development of HCC. Here we investigated the underlying mechanism of the lncRNA CERS6-AS1 in HCC progression. The expression and prognosis of CERS6-AS1 in HCC patients was explored using The Cancer Genome Atlas. PCR analysis was utilized to measure the expression of CERS6-AS1 in tissues and cell lines. Transwell, wound healing, proliferation and glycolysis assays were conducted to evaluate the function of CERS6-AS1 on HCC cell functions. Bioinformation methods and luciferase assays were used to screen and verify potential target miRNAs and genes. A subcutaneous tumorigenesis model was constructed in nude mice to assess the effect of CERS6-AS1 on tumorigenesis in vivo. CERS6-AS1 was highly expressed in HCC tissues and cell lines. Upregulated CERS6-AS1 expression was remarkably correlated with poor prognosis of HCC patients. High CERS6-AS1 expression facilitated cell growth, invasion and glycolysis of HCC cells. Bioinformatics analyses combining with PCR analysis identified miR-30b-3p as the potential target of CERS6-AS1, and MDM2 mRNA was verified as the target of miR-30b-3p. The expression of miR-30b-3p was negatively correlated with CERS6-AS1, whereas MDM2 was positively associated with CERS6-AS1. Mechanistic studies showed that CERS6-AS1 may sponge miR-30b-3p to elevate MDM2, thus promoting the MDM2-mediated ubiquitin-dependent degradation of the p53 tumor suppressor. MDM2 overexpression or miR-30b-3p inhibitors blocked the inhibitory effect of CERS6-AS1 knockdown on proliferation, migration and glycolysis. CERS6-AS1 depletion reduced tumor formation in the in vivo mouse model. The CERS6-AS1/miR-30b-3p/MDM2/p53 signaling axis may play key roles in regulating HCC progression. CERS6-AS1 may exert as a novel biomarker or therapeutic target for HCC.

Alternative splicing variant of NRP/B promotes tumorigenesis of gastric cancer

Gastrointestinal cancer is associated with a high mortality rate. Here, we report that the splice variant of NRP/B contributes to tumorigenic activity in highly malignant gastric cancer through dissociation from the tumor repressor, HDAC5. NRP/B mRNA expression is significantly higher in the human gastric cancer tissues than in the normal tissues. Further, high levels of both the NRP/B splice variant and Lgr5, but not the full-length protein, are found in highly tumorigenic gastric tumor cells, but not in non-tumorigenic cells. The loss of NRP/B markedly inhibits cell migration and invasion, which reduces tumor formation in vivo. Importantly, the inhibition of alternative splicing increases the levels of NRP/B-1 mRNA and protein in AGS cells. The ectopic expression of full-length NRP/B exhibits tumor-suppressive activity, whereas NRP/B-2 induces the noninvasive human gastric cancer cells tumorigenesis. The splice variant NRP/B-2 which loses the capacity to interact with tumor repressors promoted oncogenic activity, suggesting that the BTB/POZ domain in the N-terminus has a crucial role in the suppression of gastric cancer. Therefore, the regulation of alternative splicing of the NRP/B gene is a potential novel target for the treatment of gastrointestinal cancer.

Abstract 3991: Ts65Dn Down syndrome mice reveal a potential therapeutic vulnerability in a BBN bladder cancer model and subset of bladder cancer cell lines

Abstract Trisomy 21, Down Syndrome, results in a constellation of symptoms including increased risk for leukemia. In contrast, mounting evidence indicates that people with Down Syndrome have lower rates of numerous solid tumors, particularly carcinogen driven cancers, even when adjusted for age. The mechanisms that dictate why this occurs are not well understood but could potentially yield actionable targets for treating or preventing cancer formation. We hypothesized Ts65Dn mice, a murine model of Down Syndrome, would be protected against BCa formation and could be evaluated as a genetic basis for the discovery of novel therapeutic targets in bladder cancer. Using the well characterized N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN) chemical carcinogen bladder cancer model we initiated tumors in Ts65Dn and WT mice. After 16 weeks BBN exposure, TS65Dn mice were found to have smaller bladder tumors by weight with a trend toward lower stages as compared to WT animals. RNA-sequencing was used to assess broad genomic changes in the tumors. Reactome analysis of the RNA-sequencing data indicated pathways associated with mitosis and the cell cycle were most affected in Ts65Dn mice, including downregulation of pathways associated with Aurora Kinase B (AURKB). AURKB is a pro-tumorigenic kinase known to enhance cell survival and proliferation. Bioinformatics analysis indicates that while AURKB is broadly expressed in most tissues, it is potently upregulated in bladder cancers, offering a potential therapeutic target. Using the AURKB specific inhibitor barasertib-HQPA we evaluated drug sensitivity in a set of BCa cell lines. Cell lines associated with a basal subtype gene signature (5637, HT-1376) were largely susceptible to barasertib with IC50 values in nM concentrations, whereas other BCa cell lines (HTB-5, T24) had IC50 values nearly 1,000X higher. We next assessed histone H3 phosphorylation, a known substrate of AURKB, to validate drug efficacy. Interestingly, inhibition of histone H3 phosphorylation was noted in all cell lines at nM concentrations, indicating that while barasertib is functionally active in both sets of cells, the anti-proliferative activity is not dependent upon phosphorylation of histone H3, but rather other factors that we have yet to determine. In conclusion, we have found Ts65Dn mice have reduced tumor formation when exposed to the BCa carcinogen BBN and furthermore, have identified AURKB as a potential therapeutic target. Use of Ts65Dn mice may be a relevant model for identifying potentially undefined tumorigenic agents in multiple cancers including bladder. Citation Format: Binh Vo, Erika Abbott, Carolyn J. Vivian, Xena Moore, Ganeshkumar Rajendran, Katie Dennis, Benjamin L. Woolbright, Scott J. Weir, John A. Taylor. Ts65Dn Down syndrome mice reveal a potential therapeutic vulnerability in a BBN bladder cancer model and subset of bladder cancer cell lines [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 3991.

Abstract 3570: Prospects for personalized cancer vaccines: The oncolytic and immunotherapeutic HSV-1(VC2) virus expressing an ovalbumin (OVA) antigen elicits robust anti-OVA immune responses

Abstract Cancers result from unique cellular transformation events resulting in the expression of cancer antigens that vary widely among different types of cancers. Ideally, a personalized cancer treatment approach needs to target specific cancer antigen. Efforts to induce specific immune responses against tumor associated antigens (TAAs) include the expression of TAAs through viral vectors capable of expressing multiple antigens. We have previously shown that the HSV-1(VC2) vaccine vector can induce potent antitumor immune responses utilizing the B16F10-derived syngeneic melanoma mouse model. To investigate whether heterologous antigens expressed by this vaccine vector could elicit potent immune responses, we generated the recombinant virus VC2-OVA that expresses the ovalbumin antigen (OVA) fused in-frame at the amino terminus of the viral VP26 protein. Western blot analysis of infected cells in cell culture showed efficient expression of the OVA-VP26 protein. The anti-tumor efficacy of the VC2-OVA virus was tested in the B16cOVA and E.G7-OVA mouse models that constitutively express the OVA antigen to test whether this vaccine can either prevent the formation of new tumors (prophylactic modality) or reduce tumor metastasis (therapeutic modality). In addition, we evaluated the differences between intradermal, subcutaneous, and intramuscular routes of vaccination with VC2-OVA. Treatment with VC2-OVA resulted in significant reduction of tumor formation and metastasis in both the prophylactic and therapeutic modalities. Importantly, the anti-tumor efficacy was dependent on the specific mouse tumor model. Further, we found that subcutaneous and intradermal was superior to intramuscular vaccination. The VC2 virus is available as a bacterial artificial chromosome allowing for the rapid isolation of recombinant VC2-derived virus expressing multiple tumor antigens. Therefore, these results demonstrate that the VC2 vaccine virus can be used to produce personalized cancer vaccines targeting specific TAAs. Citation Format: Ifeanyi K. Uche, Brent Stanfield, Jared Rudd, Konstantin Kousoulas, Paul J. Rider. Prospects for personalized cancer vaccines: The oncolytic and immunotherapeutic HSV-1(VC2) virus expressing an ovalbumin (OVA) antigen elicits robust anti-OVA immune responses [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 3570.

Reduction of Tumor Formation in GABARAP Knockout Mice is Associated with Absence of H-ras Mutation

GABARAP gene has an essential role in the autophagic process through its involvement in the maturation of the autophagosome. The role of GABARAP in tumorigenesis is not yet clarified. It is ubiquitously expressed in all tested normal tissues, while its expression in tumors is divers. Autophagy could induce by Oncogenic Ras to handle the metabolic stress and support cell survival. In this study, we found that GABARAP knockout mice exhibited significantly less tumor formation than wild-type mice after 7,12-dimethylbenz(a)anthracene treatment. Different types of tumor developed in the mice (skin, mammary, lymphoma and liver tumors). Furthermore, the tumor occurrence started earlier in wild-type mice compared to GABARAP knockout animals, and the tumor sizes in wild-type mice were obviously larger in most of induced tumors compared to the tumors formed in GABARAP KO mice. No H-ras mutation detected in the tumors of GABARAP knockout mice compared to 5 mutations in 14 tumors of the wild-type mice which revealed by mutation analysis of tumors induced by DMBA. In conclusion, the absence of H-ras mutation in DMBA-induced tumors of GABARAP KO mice indicates the significance of GABARAP gene in tumor progression that need further studies to clarify the exact role.

Biglycan as a potential regulator of tumorgenicity and immunogenicity in K-RAS-transformed cells

ABSTRACT The extracellular matrix component biglycan (BGN) plays an essential role in various physiological and pathophysiological processes. A deficient BGN expression associated with reduced immunogenicity was found in HER-2/neu-overexpressing cells. To determine whether BGN is suppressed by oncogene-driven regulatory networks, the expression and function of BGN was analyzed in murine and human BGNlow/BGNhigh K-RASG12V-transformed model systems as well as in different patients’ datasets of colorectal carcinoma (CRC) lesions. K-RAS-mutated CRC tissues expressed low BGN mRNA and protein levels when compared to normal colon epithelial cells, which was associated with a reduced patients’ survival. Transfection of BGN in murine and human BGNlow K-RAS-expressing cells resulted in a reduced growth and migration of BGNhigh vs BGNlow K-RAS cells. In addition, increased MHC class I surface antigens as a consequence of an enhanced antigen processing machinery component expression was found upon restoration of BGN, which was confirmed by RNA-sequencing of BGNlow vs. BGNhigh K-RAS models. Furthermore, a reduced tumor formation of BGNhigh versus BGNlow K-RAS-transformed fibroblasts associated with an enhanced MHC class I expression and an increased frequency of tumor-infiltrating lymphocytes in tumor lesions was found. Our data provide for the first time an inverse link between BGN and K-RAS expression in murine and human K-RAS-overexpressing models and CRC lesions associated with altered growth properties, reduced immunogenicity and worse patients’ outcome. Therefore, reversion of BGN might be a novel therapeutic option for K-RAS-associated malignancies.

Timosaponin A3 Inhibits Palmitate and Stearate through Suppression of SREBP-1 in Pancreatic Cancer

Timosaponin A3 (TA3) was demonstrated as a potent anticancer chemical by several studies. Although the effects of inhibiting growth, metastasis, and angiogenesis in various cancer cells were demonstrated through multiple mechanisms, the pharmacological mechanism of TA3 shown in pancreatic cancer (PC) is insufficient compared to other cancers. In this study, we aimed to explore the key molecular mechanisms underlying the growth inhibitory effects of TA3 using PC cells and a xenograft model. First, from the microarray results, we found that TA3 regulated INSIG-1 and HMGCR in BxPC-3 cells. Furthermore, we showed that inhibition of sterol regulatory element-binding protein-1 (SREBP-1) by TA3 reduced the fatty acid synthases FASN and ACC, thereby controlling the growth of BxPC-3 cells. We also tried to find mechanisms involved with SREBP-1, such as Akt, Gsk3β, mTOR, and AMPK, but these were not related to SREBP-1 inhibition by TA3. In the BxPC-3 xenograft model, the TA3 group had more reduced tumor formation and lower toxicity than the gemcitabine group. Interestingly, the level of the fatty acid metabolites palmitate and stearate were significantly reduced in the tumor tissue in the TA3 group. Overall, our study demonstrated that SREBP-1 was a key transcription factor involved in pancreatic cancer growth and it remained a precursor form due to TA3, reducing the adipogenesis and growth in BxPC-3 cells. Our results improve our understanding of novel mechanisms of TA3 for the regulation of lipogenesis and provide a new approach to the prevention and treatment of PC.

Trident cold atmospheric plasma blocks three cancer survival pathways to overcome therapy resistance

Therapy resistance is responsible for most cancer-related death and is mediated by the unique ability of cancer cells to leverage metabolic conditions, signaling molecules, redox status, and other pathways for their survival. Interestingly, many cancer survival pathways are susceptible to disturbances in cellular reactive oxygen species (ROS) and may therefore be disrupted by exogenous ROS. Here, we explore whether trident cold atmospheric plasma (Tri-CAP), a gas discharge with exceptionally low-level ROS, could inhibit multiple cancer survival pathways together in a murine cell line model of therapy-resistant chronic myeloid leukemia (CML). We show that Tri-CAP simultaneously disrupts three cancer survival pathways of redox deregulation, glycolysis, and proliferative AKT/mTOR/HIF-1α signaling in this cancer model. Significantly, Tri-CAP blockade induces a very high rate of apoptotic death in CML cell lines and in primary CD34+ hematopoietic stem and progenitor cells from CML patients, both harboring the therapy-resistant T315I mutation. In contrast, nonmalignant controls are minimally affected by Tri-CAP, suggesting it selectively targets resistant cancer cells. We further demonstrate that Tri-CAP elicits similar lethality in human melanoma, breast cancer, and CML cells with disparate, resistant mechanisms and that it both reduces tumor formation in two mouse models and improves survival of tumor-bearing mice. For use in patients, administration of Tri-CAP may be extracorporeal for hematopoietic stem cell transplantation therapy, transdermal, or through its activated solution for infusion therapy. Collectively, our results suggest that Tri-CAP represents a potent strategy for disrupting cancer survival pathways and overcoming therapy resistance in a variety of malignancies.

Clone competition as a mechanism to reduce tumor formation.

With age, clones carrying somatic mutations in well-known cancer driver genes progressively populate adult tissues, yet cancer transformation is rare. In a recent issue of Nature, Colom etal. showed that competition between mutated clones with different fitness could act as a tumor-protective mechanism.

GLRX3, a novel cancer stem cell-related secretory biomarker of pancreatic ductal adenocarcinoma

BackgroundCancer stem cells (CSCs) are implicated in carcinogenesis, cancer progression, and recurrence. Several biomarkers have been described for pancreatic ductal adenocarcinoma (PDAC) CSCs; however, their function and mechanism remain unclear.MethodIn this study, secretome analysis was performed in pancreatic CSC-enriched spheres and control adherent cells for biomarker discovery. Glutaredoxin3 (GLRX3), a novel candidate upregulated in spheres, was evaluated for its function and clinical implication.ResultsPDAC CSC populations, cell lines, patient tissues, and blood samples demonstrated GLRX3 overexpression. In contrast, GLRX3 silencing decreased the in vitro proliferation, migration, clonogenicity, and sphere formation of cells. GLRX3 knockdown also reduced tumor formation and growth in vivo. GLRX3 was found to regulate Met/PI3K/AKT signaling and stemness-related molecules. ELISA results indicated GLRX3 overexpression in the serum of patients with PDAC compared to that in healthy controls. The sensitivity and specificity of GLRX3 for PDAC diagnosis were 80.0 and 100%, respectively. When GLRX3 and CA19–9 were combined, sensitivity was significantly increased to 98.3% compared to that with GLRX3 or CA19–9 alone. High GLRX3 expression was also associated with poor disease-free survival in patients receiving curative surgery.ConclusionOverall, these results indicate GLRX3 as a novel diagnostic marker and therapeutic target for PDAC targeting CSCs.

ACTL6A suppresses p21Cip1 tumor suppressor expression to maintain an aggressive mesothelioma cancer cell phenotype

Mesothelioma is a poor prognosis cancer of the mesothelial lining that develops in response to exposure to various agents including asbestos. Actin-Like Protein 6A (ACTL6A, BAF53a) is a SWI/SNF regulatory complex protein that is elevated in cancer cells and has been implicated as a driver of cancer cell survival and tumor formation. In the present study, we show that ACTL6A drives mesothelioma cancer cell proliferation, spheroid formation, invasion, and migration, and that these activities are markedly attenuated by ACTL6A knockdown. ACTL6A expression reduces the levels of the p21Cip1 cyclin-dependent kinase inhibitor and tumor suppressor protein. DNA binding studies show that ACTL6A interacts with Sp1 and p53 binding DNA response elements in the p21Cip1 gene promoter and that this is associated with reduced p21Cip1 promoter activity and p21Cip1 mRNA and protein levels. Moreover, ACTL6A suppression of p21Cip1 expression is required for maintenance of the aggressive mesothelioma cancer cell phenotype suggesting that p21Cip1 is a mediator of ACTL6A action. p53, a known inducer of p21Cip1 expression, is involved ACTL6A in regulation of p21Cip1 in some but not all mesothelioma cells. In addition, ACTL6A knockout markedly reduces tumor formation and this is associated with elevated tumor levels of p21Cip1. These findings suggest that ACTL6A suppresses p21Cip1 promoter activity to reduce p21Cip1 protein as a mechanism to maintain the aggressive mesothelioma cell phenotype.

Cytotoxic capacity of a novel glycosylated antitumor ether lipid in chemotherapy-resistant high grade serous ovarian cancer in vitro and in vivo

Chemotherapy resistant high grade serous ovarian cancer remains a clinically intractable disease with a high rate of mortality. We tested a novel glycosylated antitumor ether lipid called l-Rham to assess the in vitro and in vivo efficacy on high grade serous ovarian cancer cell lines and patient samples. l-Rham effectively kills high grade serous ovarian cancer cells grown as 2D or 3D cultures in a dose and time dependent manner. l-Rham efficacy was tested in vivo in a chicken allantoic membrane/COV362 xenograft model, where l-Rham activity was as effective as paclitaxel in reducing tumor weight and metastasis. The efficacy of l-Rham to reduce OVCAR3 tumor xenografts in NRG mice was assessed in low and high tumor burden models. l-Rham effectively reduced tumor formation in the low tumor burden group, and blocked ascites formation in low and high tumor burden animals. l-Rham demonstrates efficacy against OVCAR3 tumor and ascites formation in vivo in NRG mice, laying the foundation for further development of this drug class for the treatment of high grade serous ovarian cancer patients.

Abstract LB192: Sulforaphane suppression of Prmt5 and Mep50 function suppresses the mesothelioma cancer stem cell phenotype

Abstract Mesothelioma is an aggressive and fatal cancer of the mesothelial lining which is caused by asbestos exposure. The current treatment strategy is surgical resection followed by chemotherapy, but this is marginally successful and leads to drug resistant and recurrent disease. Mesothelioma cancer stem cells (MCS cells) comprise an important subpopulation of highly aggressive mesothelioma tumor cells that maintain tumor formation and mediate drug resistance. Our goal is to identify proteins that maintain the MCS cell and non-stem cancer cell survival as therapy targets. Protein arginine methyltransferase 5 (PRMT5) functions with the MEP50 cofactor to catalyze symmetric dimethylation of specific arginine resides in histones 3 and 4 to silence tumor suppressor gene expression and enhance cancer cell survival. Our studies show that loss of PRMT5 or MEP50 reduces H4R3me2s formation in MCS cells and that this is associated with a reduction in MCS cell spheroid formation, invasion and migration. Additionally, treatment with sulforaphane (SFN), a promising diet-derived cancer prevention and therapy agent, reduces PRMT5/MEP50 level and H4R3me2s formation, and suppresses the MCS cell phenotype. Moreover, forced expression of PRMT5/MEP50 antagonizes SFN suppression of the MCS cell phenotype, suggesting that loss of PRMT5/MEP50 is required for SFN action. SFN treatment also markedly reduces tumor formation and this is associated with reduced PRMT5/MEP50 expression and H4R3me2s formation. These findings suggest that SFN suppresses PRMT5/MEP50 function to attenuate the MCS cell phenotype and reduce tumor formation, and that SFN may be a useful mesothelioma prevention and therapy agent. Citation Format: Geraldine C. Ezeka, Gautam Adhikary, Sivaveera Kandasamy, Joseph Friedberg, Richard Eckert. Sulforaphane suppression of Prmt5 and Mep50 function suppresses the mesothelioma cancer stem cell phenotype [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 LB192.

Abstract LB212: The VGLL4 tumor suppressor inhibits transglutaminase-2 dependent YAP1-TEAD signaling to attenuate the cancer phenotype

Abstract Epidermal squamous cell carcinoma (SCC) is among the most common and aggressive forms of cancer. We previously showed that the pro-cancer transcription factor, YAP1, drives an aggressive SCC cancer phenotype by binding to nuclear TEAD transcription factors to activate pro-cancer gene expression. Vestigial-like protein 4 (VGLL4) is a tumor suppressor that is downregulated in epithelial cancers. It binds to TEAD factors to displace YAP1 binding to reduce YAP1-dependent transcription and target gene expression. The present study shows that VGLL4 overexpression reduces SCC cell TEAD-dependent transcription to reduce expression of mRNA and protein encoding YAP1-target genes (CTGF, CYR61, CCND1), and pro-cancer collagen genes (COL1A2, COL3A1) leading to reduced cell proliferation, spheroid formation, invasion and migration. Identical results were observed in response to transient and stable VGLL4 overexpression. Similarly, VGLL4 expression reduces YAP1 activity in tumors leading to reduced YAP1 target and pro-cancer collagen gene expression and reduced and EMT marker proteins levels which is associated with reduced tumor formation. Loss of YAP1 responsive gene expression appears to be essential for VGLL4 attenuation of the aggressive phenotype, as forced overexpression of CCND1 or COL1A2 antagonizes VGLL4 action. These findings suggest VGLL4 functions as a tumor suppressor in SCC by repressing YAP1/TEAD signaling and consequently attenuating the SCC phenotype. Citation Format: McKayla B. Mickle, Gautam Adhikary, Wen Xu, Suruchi Shrestha, Richard L. Eckert. The VGLL4 tumor suppressor inhibits transglutaminase-2 dependent YAP1-TEAD signaling to attenuate the cancer phenotype [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 LB212.

PAK1 inhibition reduces tumor size and extends the lifespan of mice in a genetically engineered mouse model of Neurofibromatosis Type 2 (NF2).

Neurofibromatosis Type II (NF2) is an autosomal dominant cancer predisposition syndrome in which germline haploinsufficiency at the NF2 gene confers a greatly increased propensity for tumor development arising from tissues of neural crest derived origin. NF2 encodes the tumor suppressor, Merlin, and its biochemical function is incompletely understood. One well-established function of Merlin is as a negative regulator of group A serine/threonine p21-activated kinases (PAKs). In these studies we explore the role of PAK1 and its closely related paralog, PAK2, both pharmacologically and genetically, in Merlin-deficient Schwann cells and in a genetically engineered mouse model (GEMM) that develops spontaneous vestibular and spinal schwannomas. We demonstrate that PAK1 and PAK2 are both hyper activated in Merlin-deficient murine schwannomas. In preclinical trials, a pan Group A PAK inhibitor, FRAX-1036, transiently reduced PAK1 and PAK2 phosphorylation in vitro, but had insignificant efficacy in vivo. NVS-PAK1-1, a PAK1 selective inhibitor, had a greater but still minimal effect on our GEMM phenotype. However, genetic ablation of Pak1 but not Pak2 reduced tumor formation in our NF2 GEMM. Moreover, germline genetic deletion of Pak1 was well tolerated, while conditional deletion of Pak2 in Schwann cells resulted in significant morbidity and mortality. These data support the further development of PAK1-specific small molecule inhibitors and the therapeutic targeting of PAK1 in vestibular schwannomas and argue against PAK1 and PAK2 existing as functionally redundant protein isoforms in Schwann cells.

Study on the correlation between the expression of basic transcription factor 3 (BTF3) and the efficacy and prognosis of patients with malignant melanoma (MM).

e21554 Background: BTF3 is an RNA polymerase II transcription factor, studies have confirmed that BTF3 is abnormally expressed in several types of tumors and closely related to the proliferation and prognosis of gastrointestinal tumors. However, the function of BTF3 in MM remains unknown. The present study aim to detect the expression and proliferation of BTF3，to explore the correlation between the BTF3 expression and the efficacy and prognosis of MM patients. Methods: We explored the effect of BTF3 through silencing BTF3 expression by siRNA transfection with lentivirus in human melanoma cell lines. The cell proliferation, cell cycle and apoptosis were determined by methyl-thaizolyl-tetrazolium assay, flow cytometry and western blot, respectively. Then we investigated the effect of BTF3 in nude mice by tumor formation experiment. The expression of BTF3 was determined by immunohistochemistry (IHC) from 32 patients with different subtypes of MM during October 2014 to October 2020. Among them, 28 cases could be resected (stage I-III), 4 cases could not be resected (stage III-IV). Cutaneous MM 7 cases, Acral MM 14 cases, mucosal MM 9 cases, unknown primary MM 2 cases. The correlation of BTF3 expression and RFS (recurrence-free survival) /OS (overall survival) in 28 patients with resected MM was explored by Student’s t test. Results: The increased viability of negative control virus infection group was 4.706 times than that of BTF3-siRNA group. Compared with the former, BTF3-siRNA group had more cells in G1 and S phase (P< 0.05) and more apoptotic cells (P< 0.05). BTF3-siRNA reduced tumor formation in the nude mice (P<0.01). The relative IHC scores of BTF3 was 5.50±3.19 in tumor tissues (the higher the score, the higher the expression of BTF3), 6.52±4.13 in adjacent noncancerous tissues. The expression of BTF3 in different subtypes of MM tissues are shown in the table. In the median follow-up time of 27 months (6-68 months), 13 cases survived without recurrence or metastasis, 10 cases survived with recurrence or metastasis, 8 cases died. In 28 resectable MM patients, the median RFS/OS of high BTF3 expression (IHC score>5) and low expression (IHC score:0-4) were 18.57 / 24.62 months and 20.42 / 22.78 months. The corresponding RFS/OS P values of patients with high and low expression were 0.323 and 0.607. Conclusions: The study suggests that BTF3 play a role in the proliferation, cell cycle regulation, apoptosis and tumorigenicity of MM. Preliminary small-sample retrospective clinical study did not suggest that BTF3 was related to the efficacy and prognosis of patients, which needs to be further verified by large-sample prospective studies.[Table: see text]

VGLL4 inhibits YAP1/TEAD signaling to suppress the epidermal squamous cell carcinoma cancer phenotype.

Epidermal squamous cell carcinoma (SCC) develops in response to ultraviolet light exposure and is among the most common cancers. The transglutaminase 2 cancer cell survival protein stimulates the activity of the YAP1/TEAD transcription complex to drive the expression of genes that promote aggressive epidermal SCC cell invasion, migration, and tumor formation. Therefore, we are interested in mechanisms that may inhibit these events. Vestigial-like protein-4 (VGLL4) is a transcription cofactor/tumor suppressor that inhibits several pro-cancer pathways including YAP1 signaling. Our present studies show that VGLL4 inhibits YAP1/TEAD-dependent transcription to reduce the expression of YAP1 target genes (CCND1, CYR61, and CTGF) and pro-cancer collagen genes (COL1A2and COL3A1). We further show that loss of these YAP1 regulated genes is required for VGLL4 suppression of the cancer cell phenotype, as forced CCND1 or COL1A2 expression partially restores the aggressive cancer phenotype in VGLL4 expressing cells. Consistent with these findings, VGLL4 expression reduces tumor formation, and this is associated with reduced CCND1, CYR61, CTGF, COL1A2, and COL1A3 mRNA and protein levels, and reduced EMT marker expression. These findings indicate that VGLL4 suppresses the malignant epidermal SCC cancer phenotype by inhibiting YAP1/TEAD-dependent pro-cancer signaling.

Sulforaphane inhibits PRMT5 and MEP50 function to suppress the mesothelioma cancer cell phenotype.

Mesothelioma is a highly aggressive cancer of the mesothelial lining that is caused by exposure to asbestos. Surgical resection followed by chemotherapy is the current treatment strategy, but this is marginally successful and leads to drug-resistant disease. We are interested in factors that maintain the aggressive mesothelioma cancer phenotype as therapy targets. Protein arginine methyltransferase 5 (PRMT5) functions in concert with the methylosome protein 50 (MEP50) cofactor to catalyze symmetric dimethylation of key arginine resides in histones 3 and 4 which modifies the chromatin environment to alter tumor suppressor and oncogene expression and enhance cancer cell survival. Our studies show that PRMT5 or MEP50 loss reduces H4R3me2s formation and that this is associated with reduced cancer cell spheroid formation, invasion, and migration. Treatment with sulforaphane (SFN), a diet-derived anticancer agent, reduces PRMT5/MEP50 level and H4R3me2s formation and suppresses the cancer phenotype. We further show that SFN treatment reduces PRMT5 and MEP50 levels and that this reduction is required for SFN suppression of the cancer phenotype. SFN treatment also reduces tumor formation which is associated with reduced PRMT5/MEP50 expression and activity. These findings suggest that SFN may be a useful mesothelioma treatment agent that operates, at least in part, via suppression of PRMT5/MEP50 function.

Loss of mitochondrial aconitase promotes colorectal cancer progression via SCD1-mediated lipid remodeling

ObjectiveMitochondrial aconitase (ACO2) is an essential enzyme that bridges the TCA cycle and lipid metabolism. However, its role in cancer development remains to be elucidated. The metabolic subtype of colorectal cancer (CRC) was recently established. We investigated ACO2's potential role in CRC progression through mediating metabolic alterations. MethodsWe compared the mRNA and protein expression of ACO2 between paired CRC and non-tumor tissues from 353 patients. Correlations between ACO2 levels and clinicopathological features were examined. CRC cell lines with knockdown or overexpression of ACO2 were analyzed for cell proliferation and tumor growth. Metabolomics and stable isotope tracing analyses were used to study the metabolic alterations induced by loss of ACO2. ResultsACO2 decreased in >50% of CRC samples compared with matched non-tumor tissues. Decreased ACO2 levels correlated with advanced disease stage (P < 0.001) and shorter patient survival (P < 0.001). Knockdown of ACO2 in CRC cells promoted cell proliferation and tumor formation, while ectopic expression of ACO2 restrained tumor growth. Specifically, blockade of ACO2 caused a reduction in TCA cycle intermediates and suppression of mitochondrial oxidative phosphorylation, resulting in an increase in glycolysis and elevated citrate flux for fatty acid and lipid synthesis. Increased citrate flux induced upregulation of stearoyl-CoA desaturase (SCD1), which enhanced lipid desaturation in ACO2-deficent cells to favor colorectal cancer growth. Pharmacological inhibition of SCD selectively reduced tumor formation of CRC with ACO2 deficiency. ConclusionsOur study demonstrated that the rewiring metabolic pathway maintains CRC survival during compromised TCA cycles and characterized the therapeutic vulnerability of lipid desaturation in a meaningful subset of CRC with mitochondrial dysfunction.

Functionalized graphene oxide as a nanocarrier for multiple suppressive miRNAs to inhibit human intrahepatic cholangiocarcinoma

AbstractThe restoration of suppressed miRNAs is a promising therapeutic approach for treating tumors; however, efficient delivery remains a challenge. Herein, we aimed to develop a polyethylenimine (PEI) functionalized graphene oxide nanosheets (GO‐PEI) as a suppressive miRNA delivery system to treat human intrahepatic cholangiocarcinoma (ICC). We found that the GO‐PEI complex possessed excellent transfection efficacy and acceptable toxicity. Furthermore, using our miRNA array analysis and The Cancer Genome Atlas (TCGA) dataset, we selected four miRNAs (miR‐194‐5p, miR‐125b‐5p, miR‐122‐5p, and let‐7c‐5p) that are remarkably downregulated in ICC samples compared to that in adjacent tissues. The GO‐PEI complexed with the four miRNAs (GO‐PEI‐4miR) achieved a higher miRNA transfection efficiency than Lipo2000, as verified by quantitative reverse transcription polymerase chain reaction (qRT‐PCR) assays, immunofluorescence, and flow cytometry analyses. In addition, in vitro experiments revealed that GO‐PEI‐4miR remarkably restored the repressed miRNAs, thereby significantly repressing tumor sphere formation, colony formation, drug resistance, and markedly inhibiting the target genes of these miRNAs and cancer stem cell‐related markers. Furthermore, both tumor weights and bioluminescent imaging analysis indicated that the GO‐PEI‐4miR significantly reduced tumor formation in vivo. Taken together, these results demonstrate that GO‐PEI could be a potential delivery system for multiple repressive miRNAs in ICC therapy.