15-Hydroxy-8(17),13(E)-labdadiene-19-carboxylic acid (HLCA) inhibits proliferation and induces cell cycle arrest and apoptosis in ovarian cancer cells

Anticancer diterpenes of African natural products: Mechanistic pathways and preclinical developments

BACKGROUND

The African continent is home to five biodiversity hotspots, boasting an immense wealth of medicinal flora, fungi and marine life. Diterpenes extracted from such natural products have compelling cytotoxic activities that warrant further exploration for the drug market, particularly in cancer therapy, where mortality rates remain elevated worldwide.

PURPOSE

To demonstrate the potential of African natural products on the global stage for cancer therapy development and provide an in-depth analysis of the current literature on the activity of cancer cytotoxic diterpenes from African natural sources (to our knowledge, the first of its kind); not only to reveal the most promising candidates for clinical development, but to demonstrate the importance of preserving the threatened ecosystems of Africa.

METHODS

A comprehensive search by means of the PRISMA strategy was conducted using electronic databases, namely Web of Science, PubMed, Google Scholar and ScienceDirect. The search terms employed were 'diterpene & mechanism & cancer' and 'diterpene & clinical & cancer'. The selection process involved assessing titles in English, Portuguese and Spanish, adhering to predefined eligibility criteria. The timeframe for inclusion spanned from 2010 to 2023, resulting in 218 relevant papers. Chemical structures were visualized using ChemDraw 21.0, PubChem was utilized to search for CID numbers.

RESULTS

Despite being one of the richest biodiverse zones in the world, African natural products are proportionally underreported compared to Asian countries or otherwise. The diterpenes andrographolide (Andrographis paniculata), forskolin (Coleus forskohlii), ent-kauranes from Isodon spp., euphosorophane A (Euphorbia sororia), cafestol & kahweol (Coffea spp.), macrocylic jolkinol D derivatives (Euphorbia piscatoria) and cyathane erinacine A (Hericium erinaceus) illustrated the most encouraging data for further cancer therapy exploration and development.

CONCLUSIONS

Diterpenes from African natural products have the potential to be economically significant active pharmaceutical and medicinal ingredients, specifically focussed on anticancer therapeutics.

Squamabietenols A-F, undescribed abietane-O-abietane dimeric diterpenoids from the ornamental conifer Juniperus squamata and their ATP-citrate lyase inhibitory activities

Six undescribed naturally occurring abietane-O-abietane dimers (squamabietenols A-F) together with one 3,4-seco-totarane-type, a pimarane-type, and 17 related known mono-/dimeric diterpenoids were isolated and characterized from the needles and twigs of the ornamental conifer Juniperus squamata. The undescribed structures and their absolute configurations were established by extensive spectroscopic methods, GIAO NMR calculations with DP4+ probability analyses, and ECD calculations. Squamabietenols A and B showed significant inhibitory effects against ATP-citrate lyase (ACL, a novel drug target for hyperlipidemia and other metabolic disorders), with IC₅₀ values of 8.82 and 4.49 μM, respectively. A molecular docking study corroborated the findings by highlighting the interactions between the bioactive compounds and the ACL enzyme (binding affinities: -7.1 to -9.0 kcal/mol). The unique abietane-O-abietane dimeric diterpenoids are quite rare in the vegetable kingdom, and they are of chemotaxonomic significance for the Cupressaceae family.

AGA induces sub-G1 cell cycle arrest and apoptosis in human colon cancer cells through p53-independent/p53-dependent pathway

BACKGROUND

Despite the advancement in chemotherapeutic drugs for colon cancer treatment, it is still a life-threatening disease worldwide due to drug resistance. Therefore, an urgently needed to develop novel drugs for colon cancer therapies. AGA is a combination of traditional Chinese medicine Antler's extract (A), Ganoderma lucidum (G), and Antrodia camphorata (A); it contains a lot of biomolecules like polysaccharides, fatty acids, and triterpenoids that are known to exerting anti-oxidative, anti-inflammatory, anti-microbial and anti-tumor activities in oral cancer. In this study, we investigate AGA anti-proliferative, anti-metastatic and apoptotic activity to explore its anti-cancer activity against colon cancer cells and its underlying mechanism.

METHOD

Here, in-vitro studies were performed to determine the antiproliferative activity of AGA through MTT and colony formation assays. Wound healing and transwell migration assay were used to evaluate the metastasis. Flow cytometry and protein expression were used to investigate the involved molecular mechanism by evaluating the cell cycle and apoptosis. The in-vivo anti-cancerous activity of AGA was assessed by xenograft mice model of colon cancer cells.

RESULTS

We found that AGA significantly inhibited the proliferative capacity and metastasis of colon cancer cells in-vitro. In addition, AGA induced cell cycle arrest in the sub-G1 phase through upregulating p21 and downregulating CDK2, CDK6 in SW620, and CDK4 in SW480 and HT29, respectively. Annexin-v assay indicated that colon cancer cells had entered early and late apoptosis after treatment with AGA. Furthermore, a mechanistic protein expressions study revealed that AGA in p53-dependent and independent regulated the apoptosis of colon cancer by downregulating the p53 protein expression in SW620 and SW480 cells but upregulating in a dose-dependent manner in HT29 cells and increasing the expression of Bax and caspase-9 to inhibit the colon cancer cells. In vivo study, we found that AGA significantly reduced the xenograft tumor growth in NOD/SCID mice with no adverse effect on the kidney and liver.

CONCLUSION

Collectively, AGA has the potential to inhibit colon cancer through inhibiting proliferation, migration, and cell cycle kinase by upregulating p21 protein expression and promoting the apoptotic protein in a p53-dependent and independent manner.

Downregulated Dual-Specificity Protein Phosphatase 1 in Ovarian Carcinoma: A Comprehensive Study With Multiple Methods

Introduction: We aimed to explore the abnormal expression of dual-specificity protein phosphatase 1 (DUSP1) and its latent molecular mechanisms in ovarian carcinoma (OVCA).

Materials and Methods: Two clinical cohorts collected from two different hospitals were used to evaluate the expression of DUSP1 protein in OVCA tissues. RNA-sequencing and microarray datasets were utilised to verify DUSP1 expression at mRNA levels in both OVCA tissues and in the peripheral blood of OVCA patients. Furthermore, an integrated calculation was performed to pool the standard mean difference (SMD) from each cohort in order to comprehensively assess the expression of DUSP1 in OVCA. Furthermore, we examined the relationship among DUSP1, tumour microenvironment (TME), and chemotherapy resistance in OVCA. Moreover, we used pathway enrichment analysis to explore the underlying mechanisms of DUSP1 in OVCA.

Results: A pooled SMD of −1.19 (95% CI [−2.00, −0.38], p = 0.004) with 1,240 samples revealed that DUSP1 was downregulated in OVCA at both mRNA and protein levels. The area under the receiver operating characteristic curve of 0.9235 indicated the downregulated DUSP1 in peripheral blood may have a non-invasive diagnostic value in OVCA. Through six algorithms, we identified that DUSP1 may related to tumour-infiltrating T cells and cancer associated fibroblasts (CAFs) in OVCA. Pathway enrichment demonstrated that DUSP1 might participate in the mitogen-activated protein kinase (MAPK) signalling pathway. Furthermore, DUSP1 may have relations with chemotherapy resistance, and a favourable combining affinity was observed in the paclitaxel-DUSP1 docking model.

Conclusion: DUSP1 was downregulated in OVCA, and this decreasing trend may affect the infiltration of CAFs. Finally, DUSP1 may have a targeting relation with paclitaxel and participate in MAPK signaling pathways.

Exosome Component 4 Promotes Epithelial Ovarian Cancer Cell Proliferation, Migration, and Invasion via the Wnt Pathway

Background

Of gynecologic malignancies, ovarian cancer is the leading cause of death, mainly due to the lack of sensitive tumor markers, which means it almost always presents at an advanced stage. Exosome Component 4 (EXOSC4) is involved in RNA degradation, but its role in epithelial ovarian cancer (EOC) is unclear.

Methods

The expression levels of EXOSC4 in EOC and normal ovarian tissue specimens were determined by immunohistochemical staining. The overall survival (OS) and progression-free survival (PFS) of patients with EOC were evaluated after patients were classified into high and low EXOSC4 expression groups, and the Cox regression model was established to identify independent predictors of patient prognosis. The effects of EXOSC4 on proliferation, colony formation, migration, and invasion were examined in the SKOV-3 and HO8910 cell lines by lentivirus-mediated shRNA knockdown. Flow cytometry was used to detect cell cycle changes. The mRNA levels of cyclin D1, CDK4, and c-myc were detected by RT-PCR. The protein expression levels of β-catenin, cyclin D1, CDK4, c-myc, vimentin, N-cadherin, and E-cadherin were assessed by western blot. Wnt/β-catenin activation was measured by TCF/LEF reporter assay.

Results

EXOSC4 was significantly elevated in EOC tissues and cell lines. High EXOSC4 expression was correlated with the International Federation of Gynecology and Obstetrics (FIGO) stage and pathological grade, and identified as an independent predictor of shorter OS and PFS. EXOSC4 knockdown suppressed proliferation, migration, and invasion in EOC cell lines. Cells were arrested at G0/G1 phase after EXOSC4 knockdown. The mRNA levels of cyclin D1, CDK4, and c-myc were decreased. β-catenin, cyclin D1, CDK4, c-myc, vimentin, and N-cadherin protein expression levels were reduced, while those of E-cadherin was increased. Wnt/β-catenin activity was suppressed after the EXOSC4 knockdown.

Conclusions

EXOSC4 is involved in EOC. Knockdown of EXOSC4 can inhibit the proliferation, migration, and invasion ability of EOC by suppressing the Wnt pathway. EXOSC4 is expected to be a novel biomarker and molecular target in EOC.