Sphingosine 1-Phosphate Signaling and Metabolism in Chemoprevention and Chemoresistance in Colon Cancer

Xianlian Jiedu Decoction alleviates colorectal cancer by regulating metabolic profiles, intestinal microbiota and metabolites

BACKGROUND

Xianlian Jiedu Decoction (XLJDD) has been used for the treatment of colorectal cancer (CRC) for several decades because of the prominent efficacy of the prescription. Despite the clear clinical efficacy of XLJDD, the anti-CRC mechanism of action is still unclear.

PURPOSE

The inhibitory effect and mechanism of XLJDD on CRC were investigated in the azoxymethane/dextran sulfate sodium (AOM/DSS)-induced mice.

METHODS

The AOM/DSS-induced mice model was adopted to evaluate the efficacy after administering the different doses of XLJDD. The therapeutic effects of XLJDD in treating AOM/DSS-induced CRC were investigated through histopathology, immunofluorescence and ELISA analysis methods. In addition, metabolomics profile and 16S rRNA analysis were used to explore the effective mechanisms of XLJDD on CRC.

RESULTS

The results stated that the XLJDD reduced the number of tumor growth on the inner wall of the colon and the colorectal weight/length ratio, and suppressed the disease activity index (DAI) score, meanwhile XLJDD also increased body weight, colorectal length, and overall survival rate. The treatment of XLJDD also exhibited the ability to lower the level of inflammatory cytokines in serum and reduce the expression levels of β-catenin, COX-2, and iNOS protein in colorectal tissue. The findings suggested that XLJDD has anti-inflammatory properties and may provide relief for those suffering from inflammation-related conditions. Mechanistically, XLJDD improved gut microbiota dysbiosis and associated metabolic levels of short chain fatty acids (SCFAs), sphingolipid, and glycerophospholipid. This was achieved by reducing the abundance of Turicibacter, Clostridium_sensu_stricto_1, and the levels of sphinganine, LPCs, and PCs. Additionally, XLJDD increased the abundance of Enterorhabdus and Alistipes probiotics, as well as the content of butyric acid and isovaleric acid.

CONCLUSION

The data presented in this article demonstrated that XLJDD can effectively inhibit the occurrence of colon inner wall tumors by reducing the level of inflammation and alleviating intestinal microbial flora imbalance and metabolic disorders. It provides a scientific basis for clinical prevention and treatment of CRC.

UHPLC-HRMS-based Multiomics to Explore the Potential Mechanisms and Biomarkers for Colorectal Cancer

BACKGROUND

Understanding the metabolic changes in colorectal cancer (CRC) and exploring potential diagnostic biomarkers is crucial for elucidating its pathogenesis and reducing mortality. Cancer cells are typically derived from cancer tissues and can be easily obtained and cultured. Systematic studies on CRC cells at different stages are still lacking. Additionally, there is a need to validate our previous findings from human serum.

METHODS

Ultrahigh-performance liquid chromatography tandem high-resolution mass spectrometry (UHPLC-HRMS)-based metabolomics and lipidomics were employed to comprehensively measure metabolites and lipids in CRC cells at four different stages and serum samples from normal control (NR) and CRC subjects. Univariate and multivariate statistical analyses were applied to select the differential metabolites and lipids between groups. Biomarkers with good diagnostic efficacy for CRC that existed in both cells and serum were screened by the receiver operating characteristic curve (ROC) analysis. Furthermore, potential biomarkers were validated using metabolite standards.

RESULTS

Metabolite and lipid profiles differed significantly among CRC cells at stages A, B, C, and D. Dysregulation of glycerophospholipid (GPL), fatty acid (FA), and amino acid (AA) metabolism played a crucial role in the CRC progression, particularly GPL metabolism dominated by phosphatidylcholine (PC). A total of 46 differential metabolites and 29 differential lipids common to the four stages of CRC cells were discovered. Eight metabolites showed the same trends in CRC cells and serum from CRC patients compared to the control groups. Among them, palmitoylcarnitine and sphingosine could serve as potential biomarkers with the values of area under the curve (AUC) more than 0.80 in the serum and cells. Their panel exhibited excellent performance in discriminating CRC cells at different stages from normal cells (AUC = 1.00).

CONCLUSIONS

To our knowledge, this is the first research to attempt to validate the results of metabolism studies of serum from CRC patients using cell models. The metabolic disorders of PC, FA, and AA were closely related to the tumorigenesis of CRC, with PC being the more critical factor. The panel composed of palmitoylcarnitine and sphingosine may act as a potential biomarker for the diagnosis of CRC, aiding in its prevention.

METTL5 promotes gastric cancer progression via sphingomyelin metabolism

BACKGROUND

The treatment of gastric cancer (GC) has caused an enormous social burden worldwide. Accumulating studies have reported that N6-methyladenosine (m6A) is closely related to tumor progression. METTL5 is a m6A methyltransferase that plays a pivotal role in maintaining the metabolic stability of cells. However, its aberrant regulation in GC has not been fully elucidated.

AIM

To excavate the role of METTL5 in the development of GC.

METHODS

METTL5 expression and clinicopathological characteristics were analyzed via The Cancer Genome Atlas dataset and further verified via immunohistochemistry, western blotting and real-time quantitative polymerase chain reaction in tissue microarrays and clinical samples. The tumor-promoting effect of METTL5 on HGC-27 and AGS cells was explored in vitro by Cell Counting Kit-8 assays, colony formation assays, scratch healing assays, transwell assays and flow cytometry. The tumor-promoting role of METTL5 in vivo was evaluated in a xenograft tumor model. The EpiQuik m6A RNA Methylation Quantification Kit was used for m6A quantification. Next, liquid chromatography-mass spectrometry was used to evaluate the association between METTL5 and sphingomyelin metabolism, which was confirmed by Enzyme-linked immunosorbent assay and rescue tests. In addition, we investigated whether METTL5 affects the sensitivity of GC cells to cisplatin via colony formation and transwell experiments.

RESULTS

Our research revealed substantial upregulation of METTL5, which suggested a poor prognosis of GC patients. Increased METTL5 expression indicated distant lymph node metastasis, advanced cancer stage and pathological grade. An increased level of METTL5 correlated with a high degree of m6A methylation. METTL5 markedly promotes the proliferation, migration, and invasion of GC cells in vitro. METTL5 also promotes the growth of GC in animal models. METTL5 knockdown resulted in significant changes in sphingomyelin metabolism, which implies that METTL5 may impact the development of GC via sphingomyelin metabolism. In addition, high METTL5 expression led to cisplatin resistance.

CONCLUSION

METTL5 was found to be an oncogenic driver of GC and may be a new target for therapy since it facilitates GC carcinogenesis through sphingomyelin metabolism and cisplatin resistance.

The emerging roles of sphingosine 1-phosphate and SphK1 in cancer resistance: a promising therapeutic target

Cancer chemoresistance is a problematic dilemma that significantly restrains numerous cancer management protocols. It can promote cancer recurrence, spreading of cancer, and finally, mortality. Accordingly, enhancing the responsiveness of cancer cells towards chemotherapies could be a vital approach to overcoming cancer chemoresistance. Tumour cells express a high level of sphingosine kinase-1 (SphK1), which acts as a protooncogenic factor and is responsible for the synthesis of sphingosine-1 phosphate (S1P). S1P is released through a Human ATP-binding cassette (ABC) transporter to interact with other phosphosphingolipids components in the interstitial fluid in the tumor microenvironment (TME), provoking communication, progression, invasion, and tumor metastasis. Also, S1P is associated with several impacts, including anti-apoptotic behavior, metastasis, mesenchymal transition (EMT), angiogenesis, and chemotherapy resistance. Recent reports addressed high levels of S1P in several carcinomas, including ovarian, prostate, colorectal, breast, and HCC. Therefore, targeting the S1P/SphK signaling pathway is an emerging therapeutic approach to efficiently attenuate chemoresistance. In this review, we comprehensively discussed S1P functions, metabolism, transport, and signaling. Also, through a bioinformatic framework, we pointed out the alterations of SphK1 gene expression within different cancers with their impact on patient survival, and we demonstrated the protein-protein network of SphK1, elaborating its sparse roles. Furthermore, we made emphasis on different machineries of cancer resistance and the tight link with S1P. We evaluated all publicly available SphK1 inhibitors and their inhibition activity using molecular docking and how SphK1 inhibitors reduce the production of S1P and might reduce chemoresistance, an approach that might be vital in the course of cancer treatment and prognosis.

The Effect of Silencing the Genes Responsible for the Level of Sphingosine-1-phosphate on the Apoptosis of Colon Cancer Cells

Sphingosine-1-phosphate (S1P) and ceramides (Cer) are engaged in key events of signal transduction, but their involvement in the pathogenesis of colorectal cancer is not conclusive. The aim of our study was to investigate how the modulation of sphingolipid metabolism through the silencing of the genes involved in the formation (SPHK1) and degradation (SGPL1) of sphingosine-1-phosphate would affect the sphingolipid profile and apoptosis of HCT-116 human colorectal cancer cells. Silencing of SPHK1 expression decreased S1P content in HCT-116 cells, which was accompanied by an elevation in sphingosine, C18:0-Cer, and C18:1-Cer, increase in the expression and activation of Caspase-3 and -9, and augmentation of apoptosis. Interestingly, silencing of SGLP1 expression increased cellular content of both the S1P and Cer (C16:0-; C18:0-; C18:1-; C20:0-; and C22:0-Cer), yet inhibited activation of Caspase-3 and upregulated protein expression of Cathepsin-D. The above findings suggest that modulation of the S1P level and S1P/Cer ratio regulates both cellular apoptosis and CRC metastasis through Cathepsin-D modulation. The cellular ratio of S1P/Cer seems to be a crucial component of the above mechanism.

HOXC11 drives lung adenocarcinoma progression through transcriptional regulation of SPHK1

Lung adenocarcinoma (LUAD) is a fatal threat to human health, while the mechanism remains unclear, and the therapy brings limited therapeutic effects. Transcription factor Homeobox C11 (HOXC11) was previously proved to be related to hind limbs and metanephric development during the embryonic phase, and its role in tumors has been gradually recognized. Our study found that HOXC11 overexpressed in LUAD and was associated with worse overall survival. Moreover, its expression in lung cancer was regulated by IκB kinase α (IKKα), a pivotal kinase in NF-κB signaling, which was related to the ubiquitination of HOXC11. We further proved that HOXC11 could enhance the ability of proliferation, migration, invasion, colony formation, and the progression of the cell cycle in LUAD cells. Meanwhile, it also accelerated the formation of subcutaneous and lung metastases tumors. In contrast, loss of HOXC11 in LUAD cells significantly inhibited these malignant phenotypes. At the same time, HOXC11 regulated the expression of sphingosine kinase 1 (SPHK1) by directly binding to its promoter region. Therefore, we conclude that HOXC11 impacts the development of LUAD and facilitates lung cancer progression by promoting the expression of SPHK1.

Seasonal Changes in Serum Metabolites in Multiple Sclerosis Relapse

Multiple sclerosis (MS) is a debilitating chronic disease of unknown etiology. There are limited treatment options due to an incomplete understanding of disease pathology. The disease is shown to have seasonal exacerbation of clinical symptoms. The mechanisms of such seasonal worsening of symptoms remains unknown. In this study, we applied targeted metabolomics analysis of serum samples using LC-MC/MC to determine seasonal changes in metabolites throughout the four seasons. We also analyzed seasonal serum cytokine alterations in patients with relapsed MS. For the first time, we can demonstrate seasonal changes in various metabolites in MS compared to the control. More metabolites were affected in MS in the fall season followed by spring, while summer MS was characterized by the smallest number of affected metabolites. Ceramides were activated in all seasons, suggesting their central role in the disease pathogenesis. Substantial changes in glucose metabolite levels were found in MS, indicating a potential shift to glycolysis. An increased serum level of quinolinic acid was demonstrated in winter MS. Histidine pathways were affected, suggesting their role in relapse of MS in the spring and fall. We also found that spring and fall seasons had a higher number of overlapping metabolites affected in MS. This could be explained by patients having a relapse of symptoms during these two seasons.

The central role of Sphingosine kinase 1 in the development of neuroendocrine prostate cancer (NEPC): A new targeted therapy of NEPC

Background

Neuroendocrine prostate cancer (NEPC) is often diagnosed as a sub‐type from the castration‐resistant prostate cancer (CRPC) recurred from the second generation of anti‐androgen treatment and is a rapidly progressive fatal disease. The molecular mechanisms underlying the trans‐differentiation from CRPC to NEPC are not fully characterized, which hampers the development of effective targeted therapy.

Methods

Bioinformatic analyses were conducted to determine the clinical correlation of sphingosine kinase 1 (SphK1) in CRPC progression. To investigate the transcriptional regulation SphK1 and neuroendocrine (NE) transcription factor genes, both chromosome immunoprecipitation and luciferase reporter gene assays were performed. To demonstrate the role of SphK1 in NEPC development, neurosphere assay was carried out along with several biomarkers determined by quantitative PCR and western blot. Furthermore, in vivo NEPC xenograft models and patient‐derived xenograft (PDX) model were employed to determine the effect of SphK1 inhibitors and target validation.

Results

Significant prevalence of SphK1 in NEPC development is observed from clinical datasets. SphK1 is transcriptionally repressed by androgen receptor‐RE1‐silencing transcription factor (REST) complex. Furthermore, sphingosine 1‐phosphate produced by SphK1 can modulate REST protein turnover via MAPK signaling pathway. Also, decreased REST protein levels enhance the expression of NE markers in CRPC, enabling the transition to NEPC. Finally, specific SphK1 inhibitors can effectively inhibit the growth of NEPC tumors and block the REST protein degradation in PDX.

Conclusions

SphK1 plays a central role in NEPC development, which offers a new target for this lethal cancer using clinically approved SphK1 inhibitors.

Determining the Anticancer Activity of Sphingosine Kinase Inhibitors Containing Heteroatoms in Their Tail Structure

Sphingosine kinase (SK) enzyme, a central player of sphingolipid rheostat, catalyzes the phosphorylation of sphingosine to the bioactive lipid mediator sphingosine 1 phosphate (S1P), which regulates cancer cell proliferation, migration, differentiation, and angiogenesis through its extracellular five G protein-coupled S1P receptors (S1PR_1–5). Recently, several research studies on SK inhibitors have taken place in order use them for the development of novel anticancer-targeted therapy. In this study, we designed and synthesized analog derivatives of known SK1 inhibitors, namely RB005 and PF-543, by introducing heteroatoms at their tail structure, as well as investigated their anticancer activities and pharmacokinetic parameters in vitro. Compounds 1–20 of RB005 and PF-543 derivatives containing an aliphatic chain or a tail structure of benzenesulfonyl were synthesized. All compounds of set 1 (1–10) effectively reduced cell viability in both HT29 and HCT116 cells, whereas set 2 derivatives (11–20) showed poor anticancer effect. Compound 10, having the highest cytotoxic effect (48 h, HT29 IC₅₀ = 6.223 µM, HCT116 IC₅₀ = 8.694 µM), induced HT29 and HCT116 cell death in a concentration-dependent manner through the mitochondrial apoptotic pathway, which was demonstrated by increased annexin V-FITC level, and increased apoptotic marker cleaved caspase-3 and cleaved PARP. Compound 10 inhibited SK1 by 20%, and, thus, the S1P level decreased by 42%. Unlike the apoptosis efficacy, the SK1 inhibitory effect and selectivity of the PF-543 derivative were superior to that of the RB005 analog. As a result, compounds with an aliphatic chain tail exhibited stronger apoptotic effects. However, this ability was not proportional to the degree of SK inhibition. Compound 10 increased the protein phosphatase 2A (PP2A) activity (1.73 fold) similar to FTY720 (1.65 fold) and RB005 (1.59 fold), whereas compounds 11 and 13 had no effect on PP2A activation. Since the PP2A activity increased in compounds with an aliphatic chain tail, it can be suggested that PP2A activation has an important effect on anticancer and SK inhibitory activities.

Identification and validation of a prognostic risk-scoring model based on sphingolipid metabolism-associated cluster in colon adenocarcinoma

Colon adenocarcinoma (COAD) is the primary factor responsible for cancer-related mortalities in western countries, and its development and progression are affected by altered sphingolipid metabolism. The current study aimed at investigating the effects of sphingolipid metabolism-related (SLP) genes on multiple human cancers, especially on COAD. We obtained 1287 SLP genes from the GeneCard and MsigDb databases along with the public transcriptome data and the related clinical information. The univariate Cox regression analysis suggested that 26 SLP genes were substantially related to the prognosis of COAD, and a majority of SLP genes served as the risk genes for the tumor, insinuating a potential pathogenic effect of SLP in COAD development. Pan-cancer characterization of SLP genes summarized their expression traits, mutation traits, and methylation levels. Subsequently, we focused on the thorough research of COAD. With the help of unsupervised clustering, 1008 COAD patients were successfully divided into two distinct subtypes (C1 and C2). C1 subtype is characterized by a poor prognosis, activation of SLP pathways, high expression of SLP genes, disordered carcinogenic pathways, and immune microenvironment. Based on the clusters of SLP, we developed and validated a novel prognostic model, consisting of ANO1, C2CD4A, EEF1A2, GRP, HEYL, IGF1, LAMA2, LSAMP, RBP1, and TCEAL2, to quantitatively evaluate the clinical outcomes of COAD. The Kaplain-Meier survival curves and ROC curves highlighted the accuracy of our SLP model in both internal and external cohorts. Compared to normal colon tissues, expression of C2CD4A was detected to be significantly higher in COAD; whereas, expression levels of EEF1A2, IGF1, and TCEAL2 were detected to be significantly lower in COAD. Overall, our research emphasized the pathogenic role of SLP in COAD and found that targeting SLP might help improve the clinical outcomes of COAD. The risk model based on SLP metabolism provided a new horizon for prognosis assessment and customized patient intervention.

Knockdown of OLR1 weakens glycolytic metabolism to repress colon cancer cell proliferation and chemoresistance by downregulating SULT2B1 via c-MYC

Chemoresistance is one of the major problems of colon cancer treatment. In tumors, glycolytic metabolism has been identified to promote cell proliferation and chemoresistance. However, the molecular mechanisms underlying glycolytic metabolism and chemoresistance in colon cancer remains enigmatic. Hence, this research was designed to explore the mechanism underlying the OLR1/c-MYC/SULT2B1 axis in the regulation of glycolytic metabolism, to affect colon cancer cell proliferation and chemoresistance. Colon cancer tissues and LoVo cells were attained, where OLR1, c-MYC, and SULT2B1 expression was detected by immunohistochemistry, RT-qPCR, and western blot analysis. Next, ectopic expression and knockdown assays were implemented in LoVo cells. Cell proliferation was detected by MTS assay and clone formation. Extracellular acidification, glucose uptake, lactate production, ATP/ADP ratio, and GLUT1 and LDHA expression were measured to evaluate glycolytic metabolism. Then, the transfected cells were treated with chemotherapeutic agents to assess drug resistance by MTS experiments and P-gp and SMAD4 expression by RT-qPCR. A nude mouse model of colon cancer transplantation was constructed for in vivo verification. The levels of OLR1, c-MYC, and SULT2B1 were upregulated in colon cancer tissues and cells. Mechanistically, OLR1 increased c-MYC expression to upregulate SULT2B1 in colon cancer cells. Moreover, knockdown of OLR1, c-MYC, or SULT2B1 weakened glycolytic metabolism, proliferation, and chemoresistance of colon cancer cells. In vivo experiments authenticated that OLR1 knockdown repressed the tumorigenesis and chemoresistance in nude mice by downregulating c-MYC and SULT2B1. Conclusively, knockdown of OLR1 might diminish SULT2B1 expression by downregulating c-MYC, thereby restraining glycolytic metabolism to inhibit colon cancer cell proliferation and chemoresistance.

S1P signaling, its interactions and cross-talks with other partners and therapeutic importance in colorectal cancer

Sphingosine-1-Phosphate (S1P) plays an important role in normal physiology, inflammation, initiation and progression of cancer. Deregulation of S1P signaling causes aberrant proliferation, affects survival, leads to angiogenesis and metastasis. Sphingolipid rheostat is crucial for cellular homeostasis. Discrepancy in sphingolipid metabolism is linked to cancer and drug insensitivity. Owing to these diverse functions and being a potent mediator of tumor growth, S1P signaling might be a suitable candidate for anti-tumor therapy or combination therapy. In this review, with a focus on colorectal cancer we have summarized the interacting partners of S1P signaling pathway, its therapeutic approaches along with the contribution of S1P signaling to various cancer hallmarks.

Functional Expression, Purification and Identification of Interaction Partners of PACRG

PACRG (Parkin co-regulated gene) shares a bi-directional promoter with the Parkinson’s disease-associated gene Parkin, but the physiological roles of PACRG have not yet been fully elucidated. Recombinant expression methods are indispensable for protein structural and functional studies. In this study, the coding region of PACRG was cloned to a conventional vector pQE80L, as well as two cold-shock vectors pCold II and pCold-GST, respectively. The constructs were transformed into Escherichia coli (DE3), and the target proteins were overexpressed. The results showed that the cold-shock vectors are more suitable for PACRG expression. The soluble recombinant proteins were purified with Ni²⁺ chelating column, glutathione S-transferase (GST) affinity chromatography and gel filtration. His₆ pull down assay and LC-MS/MS were carried out for identification of PACRG-binding proteins in HEK293T cell lysates, and a total number of 74 proteins were identified as potential interaction partners of PACRG. GO (Gene ontology) enrichment analysis (FunRich) of the 74 proteins revealed multiple molecular functions and biological processes. The highest proportion of the 74 proteins functioned as transcription regulator and transcription factor activity, suggesting that PACRG may play important roles in regulation of gene transcription.

Incorporation of natural assumption to deal with cancer

The current state of the art for the use of natural ingredients for cancer therapy is by reviewing the publications and findings associated with cancer research with the employment of flavonoids. Cancer is the most furious disease making fear in the eyes of mankind. Though various treatment methods are prevalent, the patient's choices are shifting from synthetic treatment strategy to the natural ones. The plant-based metabolites are used very often in our life as a food additive and also as a medicine for primary health care. The safety profile and its efficacy add on advantage for the incorporation of the natural products separately or in combination as a remedy for cancer. Flavonoids, the plant-based metabolites are proven for their anti-inflammatory, anti-oxidant, and anti-cancer properties. Their chemotherapeutic and chemosensitizing power had made it interesting for the researchers to dig more on the health benefits of the flavonoids and incorporating it in a holistic approach, with its natural benefits to relieve the pain and the symptoms of the patient suffering from various medical conditions. The predominant approach for the management of cancer is by following safe and effective treatment modality. In this review, we mentioned the benefits of the flavonoids for the management of various cancers and its potency as a chemotherapeutic agent and as the chemosensitizer. Our mother nature had given remedies to cure various diseases in both human beings and animals by it; we just need to find out the sources and access to them.

USP2-Related Cellular Signaling and Consequent Pathophysiological Outcomes

Ubiquitin specific protease (USP) 2 is a multifunctional deubiquitinating enzyme. USP2 modulates cell cycle progression, and therefore carcinogenesis, via the deubiquitination of cyclins and Aurora-A. Other tumorigenic molecules, including epidermal growth factor and fatty acid synthase, are also targets for USP2. USP2 additionally prevents p53 signaling. On the other hand, USP2 functions as a key component of the CLOCK/BMAL1 complex and participates in rhythmic gene expression in the suprachiasmatic nucleus and liver. USP2 variants influence energy metabolism by controlling hepatic gluconeogenesis, hepatic cholesterol uptake, adipose tissue inflammation, and subsequent systemic insulin sensitivity. USP2 also has the potential to promote surface expression of ion channels in renal and intestinal epithelial cells. In addition to modifying the production of cytokines in immune cells, USP2 also modulates the signaling molecules that are involved in cytokine signaling in the target cells. Usp2 knockout mice exhibit changes in locomotion and male fertility, which suggest roles for USP2 in the central nervous system and male genital tract, respectively. In this review, we summarize the cellular events with USP2 contributions and list the signaling molecules that are upstream or downstream of USP2. Additionally, we describe phenotypic differences found in the in vitro and in vivo experimental models.