Epigenetic reprogramming in cancer: From diagnosis to treatment

Disruption of the epigenetic program of gene expression is a hallmark of cancer that initiates and propagates tumorigenesis. Altered DNA methylation, histone modifications and ncRNAs expression are a feature of cancer cells. The dynamic epigenetic changes during oncogenic transformation are related to tumor heterogeneity, unlimited self-renewal and multi-lineage differentiation. This stem cell-like state or the aberrant reprogramming of cancer stem cells is the major challenge in treatment and drug resistance. Given the reversible nature of epigenetic modifications, the ability to restore the cancer epigenome through the inhibition of the epigenetic modifiers is a promising therapy for cancer treatment, either as a monotherapy or in combination with other anticancer therapies, including immunotherapies. Herein, we highlighted the main epigenetic alterations, their potential as a biomarker for early diagnosis and the epigenetic therapies approved for cancer treatment.

Assessment of metabolic, mineral, and cytotoxic profile in pineapple leaves of different commercial varieties: A new eco-friendly and inexpensive source of bioactive compounds

Pineapple is among the most produced and consumed fruits worldwide, and consequently, its agroindustrial production/processing generates high amounts of agricultural waste, which are routinely discarded. Thus, it is crucial to seek alternatives to reuse this agricultural waste that are in high availability. Therefore, this work aims to evaluate the chemical composition of a specific residue (leaves) of seven commercial varieties of pineapples, to attribute high added value uses, and to evaluate its potential as a source of secondary metabolites and minerals. Thereby, twenty-eight metabolites were annotated by UPLC-QTOF-MS^E, including amino acids, organic acids, and phenolic compounds. The following minerals were quantitatively assessed by ICP-OES: Zn (5.30-19.77 mg kg^-1), Cr, Cd, Mn (50.80-113.98 mg kg^-1), Cu (1.05-4.01 mg kg^-1), P (1030.77-6163.63 mg kg^-1) and Fe (9.06-70.17 mg kg^-1). In addition, Cr and Cd (toxic materials) present concentration levels below the limit of quantification of the analytical method (LOQ_Cr and LOQ_Cd = 0.02 mg kg^-1) for all samples. The multivariate analysis was conceived from the chemical profile, through the tools of PCA (principal component analysis) and HCA (hierarchical cluster analysis). The results show that pineapple leaves have similarities and differences concerning their chemical composition. In addition, the cytotoxicity assays of the extracts against tumor and non-tumor strains shows that the extracts were non-toxic. This fact can corroborate and enhance the prospection of new uses and applications of agroindustrial co-products from pineapple, enabling the evaluation and use in different types of industries, such as pharmacological, cosmetic, and food, in addition to the possibility of being a potential source of bioactive compounds.

Long Non-coding RNAs and CRISPR-Cas Edition in Tumorigenesis

Long non-coding RNAs (lncRNAs) are one of the most abundant and heterogeneous transcripts with key roles in chromatin remodeling and gene regulation at the transcriptional and post-transcriptional levels. Due to their role in cell growth and differentiation, lncRNAs have emerged as an important biomarker in cancer diagnosis, prognosis, and targeted treatment. Recent studies have focused on elucidating lncRNA function during malignant transformation, tumor progression and drug resistance. The advent of the CRISPR system has made it possible to precisely edit complex genomic loci such as lncRNAs. Thus, we summarized the advances in CRISPR-Cas approaches for functional studies of lncRNAs including gene knockout, knockdown, overexpression and RNA targeting in tumorigenesis and drug resistance. Additionally, we highlighted the perspectives and potential applications of CRISPR approaches to treat cancer, as an emerging and promising target therapy.

HPV infection and 5mC/5hmC epigenetic markers in penile squamous cell carcinoma: new insights into prognostics

BACKGROUND

Penile cancer is one of the most aggressive male tumors. Although it is preventable, the main etiologic causes are lifestyle behaviors and viral infection, such as human papillomavirus (HPV). Long-term epigenetic changes due to environmental factors change cell fate and promote carcinogenesis, being an important marker of prognosis. We evaluated epidemiological aspects of penile squamous cell carcinoma (SCC) and the prevalence of HPV infection using high-risk HPV (hrHPV) and p16^INK4A expression of 224 participants. Global DNA methylation was evaluated through 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC).

RESULTS

The incidence of HPV was 53.2% for hrHPV and 22.32% for p16^INK4a. hrHPV was not related to systemic or lymph node metastasis and locoregional recurrence, nor influenced the survival rate. P16^INK4a seems to be a protective factor for death, which does not affect metastasis or tumor recurrence. Lymph node and systemic metastases and locoregional recurrence increase the risk of death. An increased 5mC mark was observed in penile SCC regardless of HPV infection. However, there is a reduction of the 5hmC mark for p16^INK4a + (P = 0.024). Increased 5mC/5hmC ratio (> 1) was observed in 94.2% of penile SCC, irrespective of HPV infection. Despite the increase in 5mC, it seems not to affect the survival rate (HR = 1.06; 95% CI 0.33-3.38).

CONCLUSIONS

P16^INK4a seems to be a good prognosis marker for penile SCC and the increase in 5mC, an epigenetic mark of genomic stability, may support tumor progression leading to poor prognosis.

Pisosterol Induces G2/M Cell Cycle Arrest and Apoptosis via the ATM/ATR Signaling Pathway in Human Glioma Cells

BACKGROUND

Pisosterol, a triterpene derived from Pisolithus tinctorius, exhibits potential antitumor activity in various malignancies. However, the molecular mechanisms that mediate the pisosterol-specific effects on glioma cells remain unknown.

OBJECTIVE

This study aimed to evaluate the antitumoral effects of pisosterol on glioma cell lines.

METHODS

The 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) and trypan blue exclusion assays were used to evaluate the effect of pisosterol on cell proliferation and viability in glioma cells. The effect of pisosterol on the distribution of the cells in the cell cycle was performed by flow cytometry. The expression and methylation pattern of the promoter region of MYC, ATM, BCL2, BMI1, CASP3, CDK1, CDKN1A, CDKN2A, CDKN2B, CHEK1, MDM2, p14ARF and TP53 was analyzed by RT-qPCR, western blotting and bisulfite sequencing PCR (BSP-PCR).

RESULTS

Here, it has been reported that pisosterol markedly induced G2/M arrest and apoptosis and decreased the cell viability and proliferation potential of glioma cells in a dose-dependent manner by increasing the expression of ATM, CASP3, CDK1, CDKN1A, CDKN2A, CDKN2B, CHEK1, p14ARF and TP53 and decreasing the expression of MYC, BCL2, BMI1 and MDM2. Pisosterol also triggered both caspase-independent and caspase-dependent apoptotic pathways by regulating the expression of Bcl-2 and activating caspase-3 and p53.

CONCLUSION

It has been, for the first time, confirmed that the ATM/ATR signaling pathway is a critical mechanism for G2/M arrest in pisosterol-induced glioma cell cycle arrest and suggests that this compound might be a promising anticancer candidate for further investigation.

Synthesis of alkynylated 1,2,4-oxadiazole/1,2,3-1H-triazole glycoconjugates: Discovering new compounds for use in chemotherapy against lung carcinoma and Mycobacterium tuberculosis

A total of forty-three compounds were synthesized, including thirty-two new ones. Among those compounds, seventeen were selected and tested on human tumor cell lines: PC-3 (prostate adenocarcinoma), HCT-116 (colorectal tumor), NCIH-460 (lung carcinoma), SKMEL-103 (melanoma) and AGP-01 (gastric tumor). Alkynylated 1,2,4-oxadiazoles 2m, 3g and 3k exhibited antiproliferative activities against NCIH-460 in culture. Alkynylated N-cyclohexyl-1,2,4-oxadiazoles 3a-m and bis-heterocycle glucoglycero-1,2,3-triazole-N-cyclohexyl-1,2,4-oxadiazole derivatives 5a-k and 6-11 were evaluated for their in vitro efficacy towards Mycobacterium tuberculosis (Mtb) H₃₇Ra and H₃₇Rv strains. In general, glycerosugars conjugated to 1,2,4-oxadiazole via a 1,2,3-triazole linkage (5a, 5e, 5j, 5k, and 7) showed in vitro inhibitory activity against Mtb (H₃₇Rv). The largest molecules bis-triazoles 10 and 11, proved inactive against TB. Probably, the absence of the N-cyclohexyl group in compound 8 and 1,2,4-oxadiazole nucleus in compound 9 were responsible for its low activity. Glucoglycero-triazole-oxadiazole derivatives 5e (10 μM) and 7 (23.9 μM) were the most promising antitubercular compounds, showing a better selective index than when tested against RAW 264.7 and HepG2 cells. Vero cell were used to investigate cytotoxicity of compounds 5a, 5h, 5j, 5k, and these compounds showed good cell viability. Further, in silico studies were performed for most active compounds (5e and 7) with potential drug targets, DprE1 and InhA of Mtb to understand possible interactions aided with molecular dynamic simulation (100ns).

Synthesis of hybrids thiazole–quinoline, thiazole–indole and their analogs: in vitro anti-proliferative effects on cancer cell lines, DNA binding properties and molecular modeling

A quinoline–thiazole hybrid was synthesized, which showed cytotoxicity against the HL-60 cell line. Electrochemical and spectroscopic experiments suggested DNA as the biological target.

Antitumor Potential of the Isoflavonoids (+)- and (-)-2,3,9-Trimethoxypterocarpan: Mechanism-of-Action Studies

Synthetically derived samples of (+)-(6aS,11aS)-2,3,9-trimethoxypterocarpan [(+)-1] and its enantiomer [(-)-1], both of which are examples of naturally occurring isoflavonoids, were evaluated, together with the corresponding racemate, as cytotoxic agents against the HL-60, HCT-116, OVCAR-8, and SF-295 tumor cell lines. As a result it was established that compound (+)-1 was particularly active with OVCAR-8 cells being the most sensitive and responding in a dose-dependent manner. A study of cell viability and drug-induced morphological changes revealed the compound causes cell death through a mechanism characteristic of apoptosis. Finally, a computational study of the interactions of compound (+)-1 and (S)-monastrol, an established, synthetically derived, potent, and cell-permeant inhibitor of mitosis, with the kinesin-type protein Eg5 revealed that both bind to this receptor in a similar manner. Significantly, compound (+)-1 binds with greater affinity, an effect attributed to the presence of the associated methoxy groups.

β-Cyclodextrin complex improves the bioavailability and antitumor potential of cirsiliol, a flavone isolated from Leonotis nepetifolia (Lamiaceae)

Cirsiliol is a flavone found in many Lamiaceae species with high cytotoxic activity against tumor cell lines. Although cirsiliol is being used in cancer therapy, its pharmacological potential is limited by its low solubility and bioavailability. In this paper, a cirsiliol-β-cyclodextrin inclusion complex was developed in order to increase its solubility and bioavailability. The formation of inclusion complex was proved by scanning electron microscopy, Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) and solubility increment was verified through the ultraviolet-visible (UV-Vis) method. The cytotoxic effect against tumor cells (PC3, HCT-116 and HL-60 human cell lines, and S-180 murine cell line) and the antitumor activity in mice bearing sarcoma S-180 were also investigated. The inclusion complex was obtained with 71.45% of total recovery and solubility 2.1 times higher compared to the compound in its free form. This increment in solubility was responsible by a tumor growth inhibition potentiation (1.5 times greater compared to compound in its free form). In addition, this study showed that cirsiliol and its inclusion complex in β-cyclodextrin have strong antitumor potential at low doses without promoting side effects commonly observed for conventional drugs as doxorubicin.

Explaining urokinase type plasminogen activator inhibition by amino-5-hydroxybenzimidazole and two naphthamidine-based compounds through quantum biochemistry

Urokinase plasminogen activator (uPA) is a biomarker and therapeutic target for several cancer types whose inhibition has been shown to slow tumor growth and metastasis.

Effect of diterpenoid kaurenoic acid on genotoxicity and cell cycle progression in gastric cancer cell lines

The goal of our study was to evaluate the effect of kaurenoic acid, obtained from copaiba oil resin, in gastric cancer (GC) and a normal mucosa of stomach (MNP01) cell lines. The compound was tested at concentrations of 2.5, 5, 10, 30 and 60μg/mL. Comet and micronucleus assays were used to access its potential genotoxicity in vitro. Moreover, we evaluated the effect of kaurenoic acid in cell cycle progression and in the transcription of genes involved in the control of the cell cycle: MYC, CCND1, BCL2, CASP3, ATM, CHK2 and TP53. Kaurenoic acid induced an increase on cell DNA damage or micronucleus frequencies on GC cell lines in a dose-dependent manner. The GC and MNP01 cell lines entering DNA synthesis and mitosis decreased significantly with kaurenoic acid treatment, and had an increased growth phase compared with non-treated cells. The treatment induced apoptosis (or necrosis) even at a concentration of 2.5μg/mL in relation to non-treated cells. GC cell lines presented reduced MYC, CCND1, BCL2 and CASP3 transcription while ATM, CHK2 and TP53 increased in transcription in relation to non-treated cells, especially at a concentration above 10μg/mL. The gene transcription in the MNP01 (non-treated non-cancer cell line) was designated as a calibrator for all the GC cell lines. In conclusion, our results showed that kaurenoic acid obtained from Copaifera induces DNA damage and increases the micronuclei frequency in a dose-dependent manner in GC cells, with a significant genotoxicity observed above the concentration of 5μg/mL. Moreover, this compound seems to be able to induce cell cycle arrest and apoptosis in GC cells.