Repression of LSD1 potentiates homologous recombination-proficient ovarian cancer to PARP inhibitors through down-regulation of BRCA1/2 and RAD51.

Poly (ADP-ribose) polymerase inhibitors (PARPi) are selectively active in ovarian cancer (OC) with homologous recombination (HR) deficiency (HRD) caused by mutations in BRCA1/2 and other DNA repair pathway members. We sought molecular targeted therapy that induce HRD in HR-proficient cells to induce synthetic lethality with PARPi and extend the utility of PARPi. Here, we demonstrate that lysine-specific demethylase 1 (LSD1) is an important regulator for OC. Importantly, genetic depletion or pharmacological inhibition of LSD1 induces HRD and sensitizes HR-proficient OC cells to PARPi in vitro and in multiple in vivo models. Mechanistically, LSD1 inhibition directly impairs transcription of BRCA1/2 and RAD51, three genes essential for HR, dependently of its canonical demethylase function. Collectively, our work indicates combination with LSD1 inhibitor could greatly expand the utility of PARPi to patients with HR-proficient tumor, warranting assessment in human clinical trials.

NDR1 activates CD47 transcription by increasing protein stability and nuclear location of ASCL1 to enhance cancer stem cell properties and evasion of phagocytosis in small cell lung cancer.

Small cell lung cancer (SCLC) is one of the most malignant types of lung cancer. Cancer stem cell (CSC) and tumor immune evasion are critical for the development of SCLC. We previously reported that NDR1 enhances breast CSC properties. NDR1 might also have a role in the regulation of immune responses. In the current study, we explore the function of NDR1 in the control of CSC properties and evasion of phagocytosis in SCLC. We find that NDR1 enhances the enrichment of the ALDEFLUORhigh and CD133high population, and promotes sphere formation in SCLC cells. Additionally, NDR1 upregulates CD47 expression to enhance evasion of phagocytosis in SCLC. Furthermore, the effects of NDR1 enhanced CD47 expression and evasion of phagocytosis are more prominent in CSC than in non-CSC. Importantly, NDR1 promotes ASCL1 expression to enhance NDR1-promoted CSC properties and evasion of phagocytosis in SCLC cells. Mechanically, NDR1 enhances protein stability and the nuclear location of ASCL1 to activate the transcription of CD47 in SCLC. Finally, CD47-blocking antibody can be used to target NDR1 enhanced CSC properties and evasion of phagocytosis by suppressing EGFR activation in SCLC. In summary, our data indicate that NDR1 could be a critical factor for modulating CSC properties and phagocytosis in SCLC.

NDR1 increases NOTCH1 signaling activity by impairing Fbw7 mediated NICD degradation to enhance breast cancer stem cell properties.

BACKGROUND: The existence of breast cancer stem cells (BCSCs) causes tumor relapses, metastasis and resistance to conventional therapy in breast cancer. NDR1 kinase, a component of the Hippo pathway, plays important roles in multiple biological processes. However, its role in cancer stem cells has not been explored. The purpose of this study was to investigate the roles of NDR1 in modulating BCSCs. METHODS: The apoptosis was detected by Annexin V/Propidium Iodide staining and analyzed by flow cytometry. BCSCs were detected by CD24/44 or ALDEFLUOR staining and analyzed by flow cytometry. The proliferation ability of BCSCs was evaluated by sphere formation assay. The expression of interested proteins was detected by western blot analysis. The expression of HES-1 and c-MYC was detected by real-time PCR. Notch1 signaling activation was detected by luciferase reporter assay. Protein interaction was evaluated by immunoprecipitation. Protein degradation was evaluated by ubiquitination analysis. The clinical relevance of NDR1 was analyzed by Kaplan-Meier Plotter. RESULTS: NDR1 regulates apoptosis and drug resistance in breast cancer cells. The upregulation of NDR1 increases CD24low/CD44high or ALDEFLUORhigh population and sphere-forming ability in SUM149 and MCF-7 cells, while downregulation of NDR1 induces opposite effects. NDR1 increased the expression of the Notch1 intracellular domain (NICD) and activated the transcription of its downstream target (HES-1 and c-MYC). Critically, both suppression of Notch pathway activation by DAPT treatment or downregulation of Notch1 expression by shRNA reverses NDR1 enhanced BCSC properties. Mechanically, NDR1 interactes with both NICD or Fbw7 in a kinase activity-independent manner. NDR1 reduces the proteolytic turnover of NICD by competing with Fbw7 for NICD binding, thereby leading to Notch pathway activation. Furthermore, NDR1 might function as a hub to modulate IL-6, TNF-α or Wnt3a induced activation of Notch1 signaling pathway and enrichment of breast cancer stem cells. Moreover, we find that the elevation of NDR1 expression predictes poor survival (OS, RFS, DMFS and PPS) in breast cancer. CONCLUSION: Our study revealed a novel function of NDR1 in regulating BCSC properties by activating the Notch pathway. These data might provide a potential strategy for eradicating BCSC to overcome tumor relapses, metastasis and drug resistance.

DHODH and cancer: promising prospects to be explored.

Human dihydroorotate dehydrogenase (DHODH) is a flavin-dependent mitochondrial enzyme catalyzing the fourth step in the de novo pyrimidine synthesis pathway. It is originally a target for the treatment of the non-neoplastic diseases involving in rheumatoid arthritis and multiple sclerosis, and is re-emerging as a validated therapeutic target for cancer therapy. In this review, we mainly unravel the biological function of DHODH in tumor progression, including its crucial role in de novo pyrimidine synthesis and mitochondrial respiratory chain in cancer cells. Moreover, various DHODH inhibitors developing in the past decades are also been displayed, and the specific mechanism between DHODH and its additional effects are illustrated. Collectively, we detailly discuss the association between DHODH and tumors in recent years here, and believe it will provide significant evidences and potential strategies for utilizing DHODH as a potential target in preclinical and clinical cancer therapies.

Cytoplasmic SHMT2 drives the progression and metastasis of colorectal cancer by inhibiting ß-catenin degradation.

Introduction: Serine hydroxymethyltransferase 2 (SHMT2) plays a critical role in serine-glycine metabolism to drive cancer cell proliferation. However, the nonmetabolic function of SHMT2 in tumorigenesis, especially in human colorectal cancer (CRC) progression, remains largely unclear. Methods: SHMT2 expression in human CRC cells was identified by western blot and immunofluorescence assay. The CRC cell proliferation, migration, and invasion after SHMT2 knockdown or overexpression were explored through in vitro and in vivo assays. Immunofluorescence, mRNA-seq, co-immunoprecipitation, chromatin immunoprecipitation-qPCR and immunohistochemistry assays were used to investigate the underlying mechanisms behind the SHMT2 nonmetabolic function. Results: We demonstrated that SHMT2 was distributed in the cytoplasm and nucleus of human CRC cells. SHMT2 knockdown resulted in the significant inhibition of CRC cell proliferation, which was not restored by serine, glycine, or formate supplementation. The invasion and migration of CRC cells were suppressed after SHMT2 knockdown. Mechanistically, SHMT2 interacted with ß-catenin in the cytoplasm. This interaction inhibited the ubiquitylation-mediated degradation of ß-catenin and subsequently modulated the expression of its target genes, leading to the promotion of CRC cell proliferation and metastasis. Notably, the lysine 64 residue on SHMT2 (SHMT2K64) mediated its interaction with ß-catenin. Moreover, transcription factor TCF4 interacted with ß-catenin, which in turn increased SHMT2 expression, forming an SHMT2/ß-catenin positive feedback loop. In vivo xenograft experiments confirmed that SHMT2 promoted the growth and metastasis of CRC cells. Finally, the level of SHMT2 was found to be significantly increased in human CRC tissues. The SHMT2 level was correlated with an increased level of ß-catenin, associated with CRC progression and predicted poor patient survival. Conclusion: Taken together, our findings reveal a novel nonmetabolic function of SHMT2 in which it stabilizes ß-catenin to prevent its ubiquitylation-mediated degradation and provide a potential therapeutic strategy for CRC therapy.

Synergistic antitumor effect of 5-fluorouracil with the novel LSD1 inhibitor ZY0511 in colorectal cancer.

BACKGROUND: Lysine-specific histone demethylase 1 (LSD1) is a potential target of cancer therapy. In the present study, we aimed to investigate the combined antitumor activity of a novel LSD1 inhibitor (ZY0511) with 5-fluorouracil (5-FU) and elucidate the underlying mechanism in colorectal cancer (CRC). METHODS: We evaluated LSD1 expression in CRC tissues from patients who received 5-FU treatment. The synergistic antitumor effect of 5-FU with ZY0511 against human CRC cells was detected both in vitro and in vivo. The underlying mechanism was explored based on mRNA sequencing (mRNA-seq) technology. RESULTS: Overexpression of LSD1 was observed in human CRC tissues, and correlated with CRC development and 5-FU resistance. ZY0511, a novel LSD1 inhibitor, effectively inhibited CRC cells proliferation, both in vitro and in vivo. Notably, the combination of ZY0511 and 5-FU synergistically reduced CRC cells viability and migration in vitro. It also suppressed Wnt/ß-catenin signaling and DNA synthesis pathways, which finally induced apoptosis of CRC cells. In addition, the combination of ZY0511 with 5-FU significantly reduced CRC xenograft tumor growth, along with lung and liver metastases in vivo. CONCLUSIONS: Our findings identify LSD1 as a potential marker for 5-FU resistance in CRC. ZY0511 is a promising candidate for CRC therapy as it potentiates 5-FU anticancer effects, thereby providing a new combinatorial strategy for treating CRC.

Reprogramming of lipid metabolism in cancer-associated fibroblasts potentiates migration of colorectal cancer cells.

Metabolic interaction between cancer-associated fibroblasts (CAFs) and colorectal cancer (CRC) cells plays a major role in CRC progression. However, little is known about lipid alternations in CAFs and how these metabolic reprogramming affect CRC cells metastasis. Here, we uncover CAFs conditioned medium (CM) promote the migration of CRC cells compared with normal fibroblasts CM. CAFs undergo a lipidomic reprogramming, and accumulate more fatty acids and phospholipids. CAFs CM after protein deprivation still increase the CRC cells migration, which suggests small molecular metabolites in CAFs CM are responsible for CRC cells migration. Then, we confirm that CRC cells take up the lipids metabolites that are secreted from CAFs. Fatty acids synthase (FASN), a crucial enzyme in fatty acids synthesis, is significantly increased in CAFs. CAF-induced CRC cell migration is abolished by knockdown of FASN by siRNA or reducing the uptake of fatty acids by CRC cells by sulfo-N-succinimidyloleate sodium in vitro and CD36 monoclonal antibody in vivo. To conclude, our results provide a new insight into the mechanism of CRC metastasis and suggest FASN of CAFs or CD36 of CRC cells may be potential targets for anti-metastasis treatment in the future.

ZY0511, a novel, potent and selective LSD1 inhibitor, exhibits anticancer activity against solid tumors via the DDIT4/mTOR pathway.

Lysine-specific demethylase1 (LSD1) plays a crucial role in cancer and has become a promising target for cancer therapy. However, the mechanism underlying the role of LSD1 in oncogenesis is poorly understood, and more effective LSD1 inhibitors are needed. Here we report the biological activity of a novel LSD1 inhibitor named ZY0511. ZY0511 specifically inhibited LSD1 activity and the proliferation of various human cancer cells especially the HeLa and HCT116 cells. ZY0511 significantly increased the expression of DDIT4, a known mTORC1 suppressor, which was a direct downstream target of LSD1 confirmed by ChIP-PCR. ZY0511-induced LSD1 inhibition upregulated the expression of DDIT4 by altering histone H3K4 methylation levels at its promoter, thus suppressing mTORC1 activity. Knockdown of DDIT4 attenuated the anticancer effect of ZY0511. Intraperitoneal administration of ZY0511 significantly prevented the growth of HCT116 and HeLa xenografts in mice and showed no detectable toxicity. Moreover, DDIT4 expression was correlated with the sensitivity of human cancer cells to chemotherapy. Taken together, ZY0511 showed therapeutic potential for solid tumors, the induction of DDIT4 may be used as a predictive biomarker of LSD1 inhibitors.

LC­MS/MS metabolome analysis detects the changes in the lipid metabolic profiles of dMMR and pMMR cells.

The DNA mismatch repair (MMR) system plays an important role in the initiation, diagnosis and treatments of colorectal cancer (CRC). Compared to CRC patients deficient in DNA MMR (dMMR), CRC patients proficient in DNA MMR (pMMR) have higher metastasis, short survival and poor response to chemotherapy and immunotherapy. It is well­known that a high­fat diet can cause CRC, and lipid metabolism is closely related to the development and metastasis of CRC. However, there have been few studies that address the difference in lipid metabolism between dMMR and pMMR CRC. Liquid chromatography­tandem mass spectrometry (LC/MS) is an advanced technique that can perform the analysis of lipid metabolites and the roles of lipids present in low abundance in cell signaling and membrane stability. In the present study, we used the LC/MS technique to analyze the difference in the lipid metabolic profiles between dMMR cell lines (HCT116, DLD1, LoVo and HCT15) and pMMR cell lines (SW480, SW620, HT29 and NCM460). The results revealed that, among the 19 classes and 157 intact lipid species identified by the LC/MS analysis, the levels of most phospholipids were lower in dMMR cells than pMMR cells. Higher levels of phosphatidylcholine (PC; 16:0/18:1) and phosphatidic acid (PA; 18:0/18:0) were observed in pMMR cells than in dMMR cells. Furthermore, our results revealed that SCD1 and PLD1, the key enzymes involved in lipid metabolism associated with metastasis, are higher in pMMR cells than dMMR cells. To the best of our knowledge, we are the first to reveal that the levels of metastasis­associated lipids and key enzymes in lipid metabolism were higher in the CRC patients with pMMR compared with the CRC patients with dMMR. This study identified potential anti­metastatic targets in the therapy of patients with pMMR, and also personalized therapy for the patients with pMMR.

1H-NMR-based metabolic profiling of a colorectal cancer CT-26 lung metastasis model in mice.

Lung metastasis is an important cause for the low 5-year survival rate of colorectal cancer patients. Understanding the metabolic profile of lung metastasis of colorectal cancer is important for developing molecular diagnostic and therapeutic approaches. We carried out the metabonomic profiling of lung tissue samples on a mouse lung metastasis model of colorectal cancer using 1H-nuclear magnetic resonance (1H-NMR). The lung tissues of mice were collected at different intervals after marine colon cancer cell line CT-26 was intravenously injected into BALB/c mice. The distinguishing metabolites of lung tissue were investigated using 1H-NMR-based metabonomic assay, which is a highly sensitive and non-destructive method for biomarker identification. Principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were applied to analyze 1H-NMR profiling data to seek potential biomarkers. All of the 3 analyses achieved excellent separations between the normal and metastasis groups. A total of 42 metabolites were identified, ~12 of which were closely correlated with the process of metastasis from colon to lung. These altered metabolites indicated the disturbance of metabolism in metastatic tumors including glycolysis, TCA cycle, glutaminolysis, choline metabolism and serine biosynthesis. Our findings firstly identified the distinguishing metabolites in mouse colorectal cancer lung metastasis models, and indicated that the metabolite disturbance may be associated with the progression of lung metastasis from colon cancer. The altered metabolites may be potential biomarkers that provide a promising molecular approach for clinical diagnosis and mechanistic study of colorectal cancer with lung metastasis.

Tissue metabolic profiling of human gastric cancer assessed by (1)H NMR.

BACKGROUND: Gastric cancer is the fourth most common cancer and the second most deadly cancer worldwide. Study on molecular mechanisms of carcinogenesis will play a significant role in diagnosing and treating gastric cancer. Metabolic profiling may offer the opportunity to understand the molecular mechanism of carcinogenesis and help to identify the potential biomarkers for the early diagnosis of gastric cancer. METHODS: In this study, we reported the metabolic profiling of tissue samples on a large cohort of human gastric cancer subjects (n = 125) and normal controls (n = 54) based on (1)H nuclear magnetic resonance ((1)H NMR) together with multivariate statistical analyses (PCA, PLS-DA, OPLS-DA and ROC curve). RESULTS: The OPLS-DA model showed adequate discrimination between cancer tissues and normal controls, and meanwhile, the model excellently discriminated the stage-related of tissue samples (stage I, 30; stage II, 46; stage III, 37; stage IV, 12) and normal controls. A total of 48 endogenous distinguishing metabolites (VIP > 1 and p < 0.05) were identified, 13 of which were changed with the progression of gastric cancer. These modified metabolites revealed disturbance of glycolysis, glutaminolysis, TCA, amino acids and choline metabolism, which were correlated with the occurrence and development of human gastric cancer. The receiver operating characteristic diagnostic AUC of OPLS-DA model between cancer tissues and normal controls was 0.945. And the ROC curves among different stages cancer subjects and normal controls were gradually improved, the corresponding AUC values were 0.952, 0.994, 0.998 and 0.999, demonstrating the robust diagnostic power of this metabolic profiling approach. CONCLUSION: As far as we know, the present study firstly identified the differential metabolites in various stages of gastric cancer tissues. And the AUC values were relatively high. So these results suggest that the metabolic profiling of gastric cancer tissues has great potential in detecting this disease and helping to understand its underlying metabolic mechanisms.

Characterization of a stem cell population in lung cancer cell line Glc-82.

OBJECTIVES: A side population (SP) of cells can be separated from diverse cancer cell lines by a fluorescence-activated cell sorter (FACS) and show stem cell-like characteristics. To gain more information about SP phenotypes, we performed a series of characterizations of SP cells. METHODS: We isolated SP cells from the lung cancer cell line Glc-82 via FACS. Their capability of multilineage differentiation, self-renewal and tumorigenicity were examined both in vitro and in vivo. Their sensitivity to anticancer drugs was also detected by Methyl-thiazol-diphenyl tetrazolium assay. The expression of cell surface molecules including ABCG2, HERs and CD133 was analyzed with a flow cytometer. RESULTS: SP cells made up an average of 14.5% of the total cell population and were more tumorigenic than non-SP cells in vivo. The growth rate of SP cells was higher than that of the unsorted cells and non-SP cells, and the repopulation of SP cells occurred more rapidly. Moreover, the SP cells expressed elevated levels of ABCG2 protein and showed augmented resistance to multiple chemotherapeutic and targeted drugs, when compared to non-SP cells. In addition, the expression of epidermal growth factor receptor protein and CD133 were higher in SP cells than in non-SP cells. CONCLUSIONS: We suggest that the SP cells in the Glc-82 cell line are enriched with cancer stem cells.