Odd-chain fatty acids as novel histone deacetylase 6 (HDAC6) inhibitors

Enrichment of C17:0-rich saturated fatty acids from sheep tail fat for adjuvant therapy of non-small-cell lung cancer

Heptadecanoic acid (C17:0), an odd-chain saturated fatty acid (OCSFA) in ruminant lipid, has been demonstrated to be potential for treating cancers. Our results also showed that sheep tail fat (STF) with higher level of C17:0-containing saturated fatty acids (SFAs) whereas lower level of oleic acid (C18:1), performed remarkable inhibition against non-small-cell lung cancer (NSCLC) cells. To enrich the content of C17:0, a C17:0-rich SFA concentrate (HRSC) was prepared from STF by solvent crystallization and urea complexation methods (hexane/STF = 3.5/1, 4 °C for 8 h, and 80% ethanol/urea/free fatty acids = 8/1/1, 4 °C for 6 h). The content of C17:0 was up from 3.02 to 6.34% and the recovery was 4.17%. Biological experiments showed that HRSC exerted better antiproliferative effect against NSCLC cells. Moreover, HRSC performed enhanced inhibitory effect in A549 cell xenograft mouse model. Therefore, HRSC has the potential to be applied in adjuvant therapy for NSCLC.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01504-w.

C15:0 and C17:0 partially mediate the association of milk and dairy products with bladder cancer risk

The relationship between saturated fatty acids (SFA) and bladder cancer (BC) risk has been conflicting. Our aim was to investigate the relationship between erythrocyte membrane SFA and BC risk. A total of 404 participants were enrolled in the study (including 112 cases and 292 controls). A validated food frequency questionnaire was used to assess the food intake. The constitutive composition of fatty acids in the erythrocyte membrane was measured by gas chromatography. After adjustment for BC risk factors, SFA had no significant association with BC risk. However, C18:0 was positively linked with BC risk with an odds ratio (OR; 95% CI) of 2.99 (1.37-6.53). In contrast, very-long-chain saturated fatty acids (VLCSFA), especially C24:0, were negatively related to BC risk with an OR (95% CI) of 0.28 (0.12-0.65) for VLCSFA and 0.33 (0.15-0.75) for C24:0. Higher total odd-chain SFA (C15:0 and C17:0) were associated with a lower risk of BC with OR (95% CI) of 0.18 (0.076-0.44), 0.18 (0.068-0.47), 0.34 (0.14-0.81), respectively. After subgroup analysis, the protective effects C15:0 and C17:0 were still remained. Receiver operating characteristic analysis displayed that the combination of C15:0 and C17:0 indexes increased the accurate predictive rate of BC risk. Further mediation effect analysis showed that C15:0 and C17:0 could be used as partial mediation effectors for milk and dairy products and bladder carcinogenesis. Overall, the combination of odd-chain SFA (C15:0 and C17:0) in the erythrocyte membrane could serve as a reliable mediator and predictor, indicating a relationship between a high intake of milk and dairy products and a lower risk of BC.

The role of volatile organic compounds for assessing characteristics and severity of non-cystic fibrosis bronchiectasis: an observational study

Background

Hypoxic conditions and Pseudomonas aeruginosa (P. aeruginosa) infection are significant factors influencing the prognosis and treatment of patients with bronchiectasis. This study aimed to explore the potential for breath analysis to detect hypoxic conditions and P. aeruginosa infection in bronchiectasis patients by analyzing of volatile organic compounds (VOCs) in exhaled breath condensate (EBC).

Methods

EBC samples were collected from stable bronchiectasis patients and analyzed using solid phase microextraction-gas chromatography-mass spectrometry (SPME-GCMS). The association of VOCs with bronchiectasis patients' phenotypes including hypoxic conditions and P. aeruginosa isolation was analyzed, which may relate to the severity of bronchiectasis disease.

Results

Levels of 10-heptadecenoic acid, heptadecanoic acid, longifolene, and decanol in the hypoxia group were higher compared to the normoxia group. Additionally, the levels of 13-octadecenoic acid, octadecenoic acid, phenol, pentadecanoic acid, and myristic acid were increased in P. aeruginosa (+) group compared to the P. aeruginosa (-) group. Subgroup analysis based on the bronchiectasis severity index (BSI)reveled that the levels of 10-heptadecenoic acid, heptadecanoic acid, decanol, 13-octadecenoic acid, myristic acid, and pentadecanoic acid were higher in the severe group compared to the moderate group. Multivariate linear regression showed that 10-heptadecenoic acid and age were independent prognostic factors for bronchiectasis patients with hypoxia. Furthermore, octadecenoic acid, phenol and gender were identified as independent prognostic factors for bronchiectasis patients with P. aeruginosa isolation.

Conclusion

The study provides evidence that specific VOCs in EBC are correlated with the severity of bronchiectasis, and 10-heptadecenoic acid is shown to be a predictive marker for hypoxia condition in bronchiectasis patients.

Association between dietary intake of saturated fatty acid subgroups and breast cancer risk

The impact of dietary saturated fatty acids (SFAs) on breast cancer risk may vary depending on their carbon chain lengths, attributable to the discrepancy in their dietary sources and biological activities. The associations between SFA subgroups classified by chain length and breast cancer risk remain controversial. In this case-control study, we aimed to investigate the association between the dietary intake of SFA subgroups, classified by chain lengths, and odds of breast cancer in China. This study included 1661 cases of breast cancer (confirmed as primary and histologically) and 1674 frequency-matched controls. Face-to-face interviews were used to collect basic information, while dietary intake information was obtained by a food frequency questionnaire. The unconditional logistic regression model was used to calculate the odds ratios (ORs) and 95% confidence intervals (95% CIs). All SFA subgroups were inversely associated with odds of breast cancer. The adjusted ORs (95% CIs) were 0.78 (0.61-0.99) for medium-chain SFAs, 0.50 (0.31-0.83) for long even-chain SFAs, 0.69 (0.54-0.88) for long odd-chain, and 0.67 (0.48-0.95) for very long-chain SFAs, respectively. In the restricted cubic spline (RCS) models, a non-linear M-shaped association was observed between long odd-chain SFAs and odds of breast cancer (Pnon-linearity = 0.007). However, the associations of medium-chain SFAs, long even-chain SFAs, and very long-chain SFAs did not reach statistical significance (Pnon-linearity > 0.05). No significant interactions were observed between all these four subgroups of SFAs and menopausal status or BMI. Our findings emphasize the significance of elucidating the associations of dietary SFAs according to chain lengths, providing insights into the etiology as well as the potential benefits of SFA-rich food intake in reducing the risk of breast cancer. Further prospective cohort studies and intervention studies are warranted to confirm these findings and identify the underlying mechanisms of the association between dietary SFAs and breast cancer.

Urinary fatty acid biomarkers for prostate cancer detection

The lack of accuracy in the current prostate specific antigen (PSA) test for prostate cancer (PCa) screening causes around 60-75% of unnecessary prostate biopsies. Therefore, alternative diagnostic methods that have better accuracy and can prevent over-diagnosis of PCa are needed. Researchers have examined various potential biomarkers for PCa, and of those fatty acids (FAs) markers have received special attention due to their role in cancer metabolomics. It has been noted that PCa metabolism prefers FAs over glucose substrates for continued rapid proliferation. Hence, we proposed using a urinary FAs based model as a non-invasive alternative for PCa detection. Urine samples collected from 334 biopsy-designated PCa positive and 232 biopsy-designated PCa negative subjects were analyzed for FAs and lipid related compounds by stir bar sorptive extraction coupled with gas chromatography/mass spectrometry (SBSE-GC/MS). The dataset was split into the training (70%) and testing (30%) sets to develop and validate logit models and repeated for 100 runs of random data partitioning. Over the 100 runs, we confirmed the stability of the models and obtained optimal tuning parameters for developing the final FA based model. A PSA model using the values of the patients' PSA test results was constructed with the same cohort for the purpose of comparing the performances of the FA model against PSA test. The FA final model selected 20 FAs and rendered an AUC of 0.71 (95% CI = 0.67-0.75, sensitivity = 0.48, and specificity = 0.83). In comparison, the PSA model performed with an AUC of 0.51 (95% CI = 0.46-0.66, sensitivity = 0.44, and specificity = 0.71). The study supports the potential use of urinary FAs as a stable and non-invasive alternative test for PCa diagnosis.

Analyzing the fatty acid composition of goat milk and its HDAC inhibitory effects: A rational approach towards understanding the epigenetic impacts of goat milk

Goat milk is a rich source of fatty acids. This study intended to assess the inhibitory potential of goat milk and its extracted fatty acids on histone deacetylases (HDACs). Palmitic acid (C16:0) is the most prevalent saturated fatty acid in goat milk. Goat milk also contains a substantial amount of monounsaturated fatty acids, with oleic acid (C18:1) being the most abundant one. Additionally, the fatty acid profile of goat milk reveals the presence of polyunsaturated fatty acids, including linoleic acid (C18:2) and α-linolenic acid (C18:3n3). Interestingly, the fat extracted from goat milk showed a greater ability to inhibit HDAC enzymes in comparison to the whole milk. These findings, at least to the best of my knowledge, showed the HDAC inhibitory properties of goat milk for the first time, presenting new opportunities for the development of fatty acid-based epigenetic-targeted food products derived from goat milk.

Pentadecanoic Acid (C15:0), an Essential Fatty Acid, Shares Clinically Relevant Cell-Based Activities with Leading Longevity-Enhancing Compounds

Pentadecanoic acid (C15:0) is an essential odd-chain saturated fatty acid with broad activities relevant to protecting cardiometabolic, immune, and liver health. C15:0 activates AMPK and inhibits mTOR, both of which are core components of the human longevity pathway. To assess the potential for C15:0 to enhance processes associated with longevity and healthspan, we used human cell-based molecular phenotyping assays to compare C15:0 with three longevity-enhancing candidates: acarbose, metformin, and rapamycin. C15:0 (n = 36 activities in 10 of 12 cell systems) and rapamycin (n = 32 activities in 12 of 12 systems) had the most clinically relevant, dose-dependent activities. At their optimal doses, C15:0 (17 µM) and rapamycin (9 µM) shared 24 activities across 10 cell systems, including anti-inflammatory (e.g., lowered MCP-1, TNFα, IL-10, IL-17A/F), antifibrotic, and anticancer activities, which are further supported by previously published in vitro and in vivo studies. Paired with prior demonstrated abilities for C15:0 to target longevity pathways, hallmarks of aging, aging rate biomarkers, and core components of type 2 diabetes, heart disease, cancer, and nonalcoholic fatty liver disease, our results support C15:0 as an essential nutrient with activities equivalent to, or surpassing, leading longevity-enhancing candidate compounds.

The Histone Deacetylase Inhibitory Potential of Chicken Egg Yolk Fat and Their Fatty Acid Composition

Histone deacetylation is a key biochemical event associated with transcriptional regulation. Histone deacetylases (HDACs) mediate the deacetylation of histones. Fatty acids have been reported to function as histone deacetylase inhibitors (HDACi). The present instigation reports the HDAC inhibitory activity of egg yolks and egg yolk-derived fat of country and farm chicken for the first time. Egg yolks and fatty acids derived from both country (CCEF) and farm chicken (FCEF) demonstrated significant HDAC enzyme activity inhibition. Furthermore, egg yolks, CCEF, and FCEF exhibited DPPH free radical scavenging effects. The analysis of fatty acid profiles revealed varying degrees of saturated, mono-, and polyunsaturated fatty acids in the egg yolks. Palmitic acid (C16 : 0) was found to be the most abundant saturated fatty acid in both CCEF and FCEF. Among the monounsaturated fatty acids, oleic acid (C18 : 1) was the most abundant in both CCEF and FCEF. In terms of polyunsaturated fatty acids, a significant difference was observed in the content of linoleic acid (C18 : 2), an omega-6 fatty acid, and docosahexaenoic acid (C22 : 6), an omega-3 fatty acid, between CCEF and FCEF. These findings present exciting prospects for the development of histone deacetylase inhibitors based on egg yolk fat.

Efficient Biosynthesis of Odd-Chain Fatty Acids via Regulating the Supply and Consumption of Propionyl-CoA in Schizochytrium sp

Odd chain fatty acids (OCFAs) are high-value-added compounds with great application in the field of food and medicine. As an oleaginous microorganism, Schizochytrium sp. has the potential to produce OCFAs efficiently. Propionyl-CoA is used as a precursor to synthesize OCFAs through the fatty acid synthetase (FAS) pathway, so its flow direction determines the yield of OCFAs. Here, different substrates were assessed to promote propionyl-CoA supply for OCFA accumulation. Moreover, the methylmalonyl-CoA mutase (MCM) was identified as the key gene responsible for propionyl-CoA consumption, which promotes the propionyl-CoA to enter into the tricarboxylic acid cycle rather than the FAS pathway. As one of the classic B₁₂-dependent enzymes, the activity of MCM can be inhibited in the absence of B₁₂. As expected, the OCFA accumulation was greatly increased. However, the removal of B₁₂ caused growth limitation. Furthermore, the MCM was knocked out to block the consumption of propionyl-CoA and to maintain cell growth; results showed that the engineered strain achieved the OCFAs titer of 2.82 g/L, which is 5.76-fold that of wild type. Last, a fed-batch co-feeding strategy was developed, resulting in the highest reported OCFAs titer of 6.82 g/L. This study provides guidance for the microbial production of OCFAs.

Heptadecanoic Acid Is Not a Key Mediator in the Prevention of Diet-Induced Hepatic Steatosis and Insulin Resistance in Mice

Epidemiological studies found that the intake of dairy products is associated with an increased amount of circulating odd-chain fatty acids (OCFA, C15:0 and C17:0) in humans and further indicate that especially C17:0 is associated with a lower incidence of type 2 diabetes. However, causal relationships are not elucidated. To provide a mechanistic link, mice were fed high-fat (HF) diets supplemented with either milk fat or C17:0 for 20 weeks. Cultured primary mouse hepatocytes were used to distinguish differential effects mediated by C15:0 or C17:0. Despite an induction of OCFA after both dietary interventions, neither long-term milk fat intake nor C17:0 supplementation improved diet-induced hepatic lipid accumulation and insulin resistance in mice. HF feeding with milk fat actually deteriorates liver inflammation. Treatment of primary hepatocytes with C15:0 and C17:0 suppressed JAK2/STAT3 signaling, but only C15:0 enhanced insulin-stimulated phosphorylation of AKT. Overall, the data indicate that the intake of milk fat and C17:0 do not mediate health benefits, whereas C15:0 might be promising in further studies.

Free Fatty Acids from Cow Urine DMSO Fraction Induce Cell Death in Breast Cancer Cells without Affecting Normal GMSCs

Objective: The objective of this study was to explore the biological relevance of free fatty acids derived from cow urine DMSO fraction (CUDF) by employing in vitro and in silico approaches. Background: Metabolic heterogeneity at the intra- and intercellular levels contributes to the metabolic plasticity of cancer cells during drug-induced response. Free fatty acid (FFA) availability at intra- and intercellular levels is related to tumor heterogeneity at interpatient and xeno-heterogeneity levels. Methods: We collected fresh urine from healthy cows and subjected it to fractionation in DMSO using drying, vortexing, and centrifugation. Finally, the sterile filtrate of cow urine DMSO fraction (CUDF) was evaluated for antiproliferative and proapoptotic effects in MCF-7 and ZR-75-1 breast cancer cells using routine cell-based assays. Intracellular metabolites were studied with the help of a novel in-house vertical tube gel electrophoresis (VTGE) method to reveal the nature of CUDF components in MCF-7 cells. Identified intracellular FFAs were studied for their molecular interactions with targeted receptor histone deacetylase (HDAC) using molecular docking and molecular dynamics (MD) simulations. Results: CUDF showed a significant reduction in cell viability and cell death in MCF-7 and ZR-75-1 breast cancer cells. Interestingly, FFAs tetracosanedioic acid, 13Z-docosenoic acid (erucic acid), nervonic acid, 3-hydroxy-tetradecanoic acid, and 3-hydroxcapric acid were found inside the treated MCF-7 cancer cells. These FFAs, including tetracosanedioic acid, indicated a specific affinity to HDAC at their inhibitory sites, similar to trichostatin A, a known inhibitor. Conclusions: This study reports on FFAs derived from CUDF as potential antiproliferative and pro-cell death agents against breast cancer cells. MD simulations hinted at tetracosanedioic acid and other FFAs as inhibitors of HDAC that could explain the observed effects of FFAs in cancer cells.

Fatty acids as histone deacetylase inhibitors: old biochemistry tales in a new life sciences town

Histone acetylation is a key epigenetic event. Although the keywords fatty acids, histones, and histone acetylation have a long history in biochemistry, these topics continue to attract much attention among researchers. The acetylation of histones is controlled by the activities of histone acetyltransferases (HATs) and histone deacetylases (HDACs). An imbalance in the activities of HATs and HDACs is common in a range of human cancers. Histone deacetylase inhibitors (HDACi) can restore dysregulated histone acetylation profiles in cancer cells and have been identified as promising anti-cancer therapeutics. Short-chain fatty acids mediate anti-cancer effects by inhibiting the activity of HDACs. Recent studies have identified odd-chain fatty acids as novel HDACi. This review summarizes recent findings regarding fatty acids as HDACi in cancer therapy. Teaser: Inhibition of histone deacetylase (HDAC) activity by fatty acids.

Heptadecanoic Acid, an Odd-Chain Fatty Acid, Induces Apoptosis and Enhances Gemcitabine Chemosensitivity in Pancreatic Cancer Cells

Odd-chain saturated fatty acids generally serve as specific biomarkers of dietary components and dairy intake, some of which have anticancer properties. This study was performed to assess the anticancer effects of heptadecanoic acid (HDNA) in human pancreatic carcinoma cells. MTT (thiazolyl blue tetrazolium bromide) assay showed that HDNA exerted stronger cytotoxic effects than pentadecanoic acid, palmitic acid (16:0), stearic acid (18:0), oleic acid (18:1), and linoleic acid (18:2) on both Panc-1 and MIA PaCa-2 pancreatic cancer cells. In addition, HDNA reduced colony formation and induced apoptosis in these pancreatic cancer cells as indicated by Hoechst 33342 staining, Annexin V/propidium iodide staining, cell cycle analysis, and Western blotting analysis in a dose-dependent manner. Moreover, HDNA synergistically reduced cell viability and promoted apoptosis when combined with gemcitabine (GEM), a chemotherapeutic agent commonly used in the treatment of pancreatic cancer. GEM-resistant MIA PaCa-2 (GR-MIA PaCa-2) cells with a resistance indices (RI) value of 215.09 [RI = half-maximal inhibitory concentration (IC₅₀) of GR-MIA PaCa-2 cells/IC₅₀ of MIA PaCa-2 cells] were established, and the efficacy of HDNA on GEM chemosensitivity was confirmed. Surprisingly, HDNA exhibited even higher antiproliferative efficacy against GR-MIA PaCa-2 cells (IC₅₀ = 71.45 ± 6.37 μM) than parental MIA PaCa-2 cells (IC₅₀ = 77.47 ± 2.10 μM). Finally, HDNA treatment inhibited the Hippo pathway and induced apoptosis of GR-MIA PaCa-2 cells. These findings suggest the beneficial effects of a HDNA-rich diet during pancreatic cancer treatments.

Systems biology strategy and experimental validation to uncover the pharmacological mechanism of Xihuang Pill in treating non-small cell lung cancer

BACKGROUND

Non-small cell lung cancer (NSCLC) accounts for almost 85% of lung cancer-related deaths worldwide. Xihuang Pill (XHP) is a representative anticancer Chinese patented medicine used to treat NSCLC in China. However, to date, a systematic analysis of XHP's antitumour effects and its impact on the immune microenvironment has not been performed.

PURPOSE

Based on the systems biology strategy and experimental validation, the present study aimed to investigate the pharmacological mechanisms involved in treating NSCLC with XHP.

METHODS

A subcutaneous tumour model was established to evaluate XHP's tumour-inhibitory effect in BALB/c nude mice. RNA sequencing (RNA-seq) and bioinformatics analysis were conducted to identify differentially expressed genes (DEGs) and signalling pathways related to XHP treatment. Network analysis based on network pharmacology and protein-to-protein networks was applied to identify the compounds and genes targeted by XHP. External data from the TCGA-NSCLC cohort were used to verify the clinical significance of XHP-targeted genes in NSCLC. The expression of survival-related candidate genes after XHP treatment was verified via qPCR. The protein expression of calcium voltage-gated channel subunit alpha 1C (CACNA1C) in different NSCLC cell lines was analysed in the Human Protein Atlas database (HPA) and DepMap Portal. Using the Estimation of STromal and Immune cells in MAlignant Tumour tissues using Expression data (ESTIMATE) algorithm and the single-sample gene set enrichment analysis (ssGSEA) algorithm uncovered the role of CACNA1C in the NSCLC tumour microenvironment (TME).

RESULTS

XHP (2 g/kg/d) significantly inhibited the growth of transplanted A549 tumours. RNA-seq identified a total of 529 DEGs (189 upregulated and 340 downregulated). In addition, 542 GO terms, 41 significant KEGG pathways, 9 upregulated hallmarks pathways, and 18 downregulated hallmark pathways were enriched. These GO terms and signalling pathways were closely related to cell proliferation, immunity, energy metabolism, and the inflammatory response of NSCLC. In addition, XHP's network pharmacology analysis identified 301 compounds and 1,432 target genes. A comprehensive strategic analysis identified CACNA1C as a promising gene by which XHP targets and regulates the TME of NSCLC, benefiting patient survival. CACNA1C expression was positively correlated with both the immune score and stromal score but negatively correlated with the tumour purity score. Additionally, CACNA1C expression was significantly correlated with the infiltration levels of 15 types of immune cells and the expression levels of 6 well-known checkpoint genes.

CONCLUSIONS

Our results show that by regulating the pathways associated with cell proliferation and immunity, XHP can suppress cancer cell growth in NSCLC. Additionally, XHP may increase the expression of CACNA1C to suppress immune cell infiltration and regulate the expression of checkpoint-related genes, thereby improving the overall survival of NSCLC patients.

Metabolic reprogramming enables the auxiliary diagnosis of breast cancer by automated breast volume scanner

Breast cancer is the leading cause of female cancer-related deaths worldwide. New technologies with enhanced sensitivity and specificity for early diagnosis and monitoring of postoperative recurrence are in critical demand. Automatic breast full volume scanning system (ABVS) is an emerging technology used as an alternative imaging method for breast cancer screening. Despite its improved detection rate of malignant tumors, ABVS cannot accurately stage breast cancer preoperatively in 30–40% of cases. As a major hallmark of breast cancer, the characteristic metabolic reprogramming may provide potential biomarkers as an auxiliary method for ABVS.

Objective

The objective of this study was to identify differential metabolomic signatures between benign and malignant breast tumors and among different subtypes of breast cancer patients based on untargeted metabolomics and improve breast cancer detection rate by combining key metabolites and ABVS.

Methods

Untargeted metabolomics approach was used to profile serum samples from 70 patients with different subtypes of breast cancer and benign breast tumor to determine specific metabolomic profiles through univariate and multivariate statistical data analysis.

Results

Metabolic profiles correctly distinguished benign and malignant breast tumors patients, and a total of 791 metabolites were identified. There were 54 different metabolites between benign and malignant breast tumors and 17 different metabolites between invasive and non-invasive breast cancer. Notably, the missed diagnosis rate of ABVS could be reduced by differential metabolite analysis. Moreover, the diagnostic performance analyses of combined metabolites (pelargonic acid, N-acetylasparagine, and cysteine-S-sulfate) with ABVS performance gave a ROC area under the curve of 0.967 (95% CI: 0.926, 0.993).

Conclusions

Our study identified metabolic features both in benign and malignant breast tumors and in invasive and non-invasive breast cancer. Combined ultrasound ABVS and a panel of differential serum metabolites could further improve the accuracy of preoperative diagnosis of breast cancer and guide surgical therapy.

HDAC6: A unique HDAC family member as a cancer target

BACKGROUND

HDAC6, a structurally and functionally distinct member of the HDAC family, is an integral part of multiple cellular functions such as cell proliferation, apoptosis, senescence, DNA damage and genomic stability, all of which when deregulated contribute to carcinogenesis. Among several HDAC family members known so far, HDAC6 holds a unique position. It differs from the other HDAC family members not only in terms of its subcellular localization, but also in terms of its substrate repertoire and hence cellular functions. Recent findings have considerably expanded the research related to the substrate pool, biological functions and regulation of HDAC6. Studies in HDAC6 knockout mice highlighted the importance of HDAC6 as a cell survival player in stressful situations, making it an important anticancer target. There is ample evidence stressing the importance of HDAC6 as an anti-cancer synergistic partner of many chemotherapeutic drugs. HDAC6 inhibitors have been found to enhance the effectiveness of conventional chemotherapeutic drugs such as DNA damaging agents, proteasome inhibitors and microtubule inhibitors, thereby highlighting the importance of combination therapies involving HDAC6 inhibitors and other anti-cancer agents.

CONCLUSIONS

Here, we present a review on HDAC6 with emphasis on its role as a critical regulator of specific physiological cellular pathways which when deregulated contribute to tumorigenesis, thereby highlighting the importance of HDAC6 inhibitors as important anticancer agents alone and in combination with other chemotherapeutic drugs. We also discuss the synergistic anticancer effect of combination therapies of HDAC6 inhibitors with conventional chemotherapeutic drugs.

Effects of Combined Pentadecanoic Acid and Tamoxifen Treatment on Tamoxifen Resistance in MCF−7/SC Breast Cancer Cells

Estrogen receptors are indicators of breast cancer adaptability to endocrine therapies, such as tamoxifen. Deficiency or absence of estrogen receptor α (ER−α) in breast cancer cells results in reduced efficacy of endocrine therapy. Here, we investigated the effect of combined tamoxifen and pentadecanoic acid therapy on ER−α−under−expressing breast cancer cells. Drug resistance gene expression patterns were determined by RNA sequencing analysis and in vitro experiments. For the first time, we demonstrate that the combined treatment of pentadecanoic acid, an odd−chain fatty acid, and tamoxifen synergistically suppresses the growth of human breast carcinoma MCF−7 stem cells (MCF−7/SCs), which were found to be tamoxifen−resistant and showed reduced ER−α expression compared with the parental MCF−7 cells. In addition, the combined treatment synergistically induced apoptosis and accumulation of sub−G1 cells and suppressed epithelial−to−mesenchymal transition (EMT). Exposure to this combination induces re−expression of ER−α at the transcriptional and protein levels, along with suppression of critical survival signal pathways, such as ERK1/2, MAPK, EGFR, and mTOR. Collectively, decreased ER−α expression was restored by pentadecanoic acid treatment, resulting in reversal of tamoxifen resistance. Overall, pentadecanoic acid exhibits the potential to enhance the efficacy of endocrine therapy in the treatment of ER−α−under−expressing breast cancer cells.

Design, synthesis and antitumor activity study of a gemcitabine prodrug conjugated with a HDAC6 inhibitor

Gemcitabine, as a first-line antitumor drug, has attracted extensive attention. However the occurrence of drug resistance limits its clinical utilization. In this paper, a gemcitabine prodrug GZ was designed and synthesized by conjugation of gemcitabine with a newly reported HDAC6 selective inhibitor pentadecanoic acid. GZ displayed high cytotoxicity to nine cancer cell lines with IC₅₀ values in the low micromolar range. In vivo, GZ displayed superior antitumor activity to gemcitabine in a 4T1 tumor xenograft model without obvious pathological damage to important organs of mice. Our study showed that compound GZ is a potential gemcitabine prodrug, which is worthy of further antitumor activity exploration.

Pentadecanoylcarnitine is a newly discovered endocannabinoid with pleiotropic activities relevant to supporting physical and mental health

As an emerging dietary essential fatty acid, pentadecanoic acid (C15:0) is expected to have bioactive metabolites with broad health benefits. Here, we evaluated pentadecanoylcarnitine, an endogenous C15:0 metabolite, for dose dependent cell-based activities, including measurement of its effects on 148 clinically relevant biomarkers across twelve primary human cell systems mimicking various disease states. Mechanisms of action for pentadecanoylcarnitine were also assessed across 78 cell-based target assays. Pentadecanoylcarnitine had dose-dependent anti-inflammatory activities, including lower IL-1α, ITAC, MCP-1, and IP-10, across five cell systems relevant to treating cardiovascular, immune, neoplastic, pulmonary, and skin diseases. Targeted assays showed pentadecanoylcarnitine as a full-acting cannabinoid 1 and 2 receptor agonist (EC50 3.7 and 3.2 µM, 111% and 106% maximum activity compared to the positive control, respectively). Pentadecanoylcarnitine also had 5-HT1A and 5-HT1B receptor agonist and histamine H1 and H2 receptor antagonist activities. In summary, pentadecanoylcarnitine, a second discovered full-acting endocannabinoid, had broad pleiotropic activities relevant to regulating inflammation, pain, mood, and sleep. This study's findings further the need to evaluate the potential health impacts of C15:0 nutritional deficiencies caused by population-wide avoidance of all dietary saturated fats, including C15:0.

Integrative Multi-Omics Analysis for the Determination of Non-Muscle Invasive vs. Muscle Invasive Bladder Cancer: A Pilot Study

Objectives: The molecular landscape of non-muscle-invasive (NMIBC) and muscle-invasive (MIBC) bladder cancer based on molecular characteristics is essential but poorly understood. In this pilot study we aimed to identify a multi-omics signature that can distinguish MIBC from NMIBC. Such a signature can assist in finding potential mechanistic biomarkers and druggable targets. Methods: Patients diagnosed with NMIBC (n = 15) and MIBC (n = 11) were recruited at a tertiary-care hospital in Nanjing from 1 April 2021, and 31 July 2021. Blood, urine and stool samples per participant were collected, in which the serum metabolome, urine metabolome, gut microbiome, and serum extracellular vesicles (EV) proteome were quantified. The differences of the global profiles and individual omics measure between NMIBC vs. MIBC were assessed by permutational multivariate analysis and the Mann–Whitney test, respectively. Logistic regression analysis was used to assess the association of each identified analyte with NMIBC vs. MIBC, and the Spearman correlation was used to investigate the correlations between identified analytes, where both were adjusted for age, sex and smoking status. Results: Among 3168 multi-omics measures that passed the quality control, 159 were identified to be differentiated in NMIBC vs. MIBC. Of these, 46 analytes were associated with bladder cancer progression. In addition, the global profiles showed significantly different urine metabolome (p = 0.029), gut microbiome (p = 0.036), and serum EV (extracellular vesicles) proteome (p = 0.039) but not serum metabolome (p = 0.059). We also observed 17 (35%) analytes that had been developed as drug targets. Multiple interactions were obtained between the identified analytes, whereas for the majority (61%), the number of interactions was at 11–20. Moreover, unconjugated bilirubin (p = 0.009) and white blood cell count (p = 0.006) were also shown to be different in NMIBC and MIBC, and associated with 11 identified omics analytes. Conclusions: The pilot study has shown promising to monitor the progression of bladder cancer by integrating multi-omics data and deserves further investigations.

Broader and safer clinically-relevant activities of pentadecanoic acid compared to omega-3: Evaluation of an emerging essential fatty acid across twelve primary human cell-based disease systems

A growing body of evidence supports that pentadecanoic acid (C15:0), an odd-chain saturated fat found in butter, is an essential fatty acid that is necessary in the diet to support long-term metabolic and heart health. Here, dose dependent and clinically relevant cell-based activities of pure C15:0 (FA15TM) were compared to eicosapentaenoic acid (EPA), a leading omega-3 fatty acid, as well as to an additional 4,500 compounds. These studies included 148 clinically relevant biomarkers measured across 12 primary human cell systems, mimicking various disease states, that were treated with C15:0 at four different concentrations (1.9 to 50 μM) and compared to non-treated control systems. C15:0 was non-cytotoxic at all concentrations and had dose dependent, broad anti-inflammatory and antiproliferative activities involving 36 biomarkers across 10 systems. In contrast, EPA was cytotoxic to four cell systems at 50 μM. While 12 clinically relevant activities were shared between C15:0 and EPA at 17 μM, C15:0 had an additional 28 clinically relevant activities, especially anti-inflammatory, that were not present in EPA. Further, at 1.9 and 5.6 μM, C15:0 had cell-based properties similar to bupropion (Pearson’s scores of 0.78), a compound commonly used to treat depression and other mood disorders. At 5.6 μM, C15:0 mimicked two antimicrobials, climabazole and clarithromycin (Pearson’s scores of 0.76 and 0.75, respectively), and at 50 μM, C15:0 activities matched that of two common anti-cancer therapeutics, gemcitabine and paclitaxel (Pearson’s scores of 0.77 and 0.74, respectively). In summary, C15:0 had dose-dependent and clinically relevant activities across numerous human cell-based systems that were broader and safer than EPA, and C15:0 activities paralleled common therapeutics for mood disorders, microbial infections, and cancer. These studies further support the emerging role of C15:0 as an essential fatty acid.

Sphingolipids and Lymphomas: A Double-Edged Sword

Lymphomas are a highly heterogeneous group of hematological neoplasms. Given their ethiopathogenic complexity, their classification and management can become difficult tasks; therefore, new approaches are continuously being sought. Metabolic reprogramming at the lipid level is a hot topic in cancer research, and sphingolipidomics has gained particular focus in this area due to the bioactive nature of molecules such as sphingoid bases, sphingosine-1-phosphate, ceramides, sphingomyelin, cerebrosides, globosides, and gangliosides. Sphingolipid metabolism has become especially exciting because they are involved in virtually every cellular process through an extremely intricate metabolic web; in fact, no two sphingolipids share the same fate. Unsurprisingly, a disruption at this level is a recurrent mechanism in lymphomagenesis, dissemination, and chemoresistance, which means potential biomarkers and therapeutical targets might be hiding within these pathways. Many comprehensive reviews describing their role in cancer exist, but because most research has been conducted in solid malignancies, evidence in lymphomagenesis is somewhat limited. In this review, we summarize key aspects of sphingolipid biochemistry and discuss their known impact in cancer biology, with a particular focus on lymphomas and possible therapeutical strategies against them.