Improving SERS biosensors for the analysis of ovarian cancer-derived small extracellular vesicles.

Small extracellular vesicles (sEVs) are lipid bilayer vesicles that carry key molecules (e.g., proteins, DNAs, RNAs, and lipids) for cell-to-cell communication, being regarded as promising biomarkers for cancer diagnosis. However, the detection of sEVs is still challenging due to their unique characteristics such as size and phenotype heterogeneity. The surface-enhanced Raman scattering (SERS) assay is a promising tool for sEV analysis as it shows the advantages of robustness, high sensitivity, and specificity. Previous studies proposed different "sandwich" immunocomplex assembling strategies and various capturing probes for sEV detection by the SERS assay. However, no studies have reported the effect of immunocomplex assembling strategies and capturing probes on the analysis of sEVs using this assay. Hence, to achieve the highest performance of the SERS assay for analysing ovarian cancer-derived sEVs, we first assessed the presence of ovarian cancer markers such as EpCAM on cancer cells and sEVs by using flow cytometry and immunoblotting. We found that cancer cells and their derived sEVs present EpCAM and therefore EpCAM was used to functionalise SERS nanotags for the comparison study of "sandwich" immunocomplex assembling strategies. Then, we compared three types of capturing probes (magnetic beads conjugated with anti-CD9, CD63, or CD81 antibodies) for sEV detection. Our study showed the strategy of pre-mixing of sEVs with SERS nanotags and the anti-CD9 capturing probe would achieve the best performance with the minimum detection of sEVs down to 1.5 × 105 particles per µL and with high specificity in distinguishing sEVs from different ovarian cancer cell lines. We further profiled the surface protein biomarkers (EpCAM, CA125, and CD24) on ovarian cancer-derived sEVs in both PBS and plasma (sEVs spiked in healthy plasma) using the improved SERS assay, showing high sensitivity and specificity. As such, we anticipate that our improved SERS assay has the potential to be used clinically as one of the effective detection methods of ovarian cancer.

CPF impedes cell cycle re-entry of quiescent lung cancer cells through transcriptional suppression of FACT and c-MYC.

Blockade of cell cycle re-entry in quiescent cancer cells is a strategy to prevent cancer progression and recurrence. We investigated the action and mode of action of CPF mixture (Coptis chinensis, Pinellia ternata and Fructus trichosanthis) in impeding a proliferative switch in quiescent lung cancer cells. The results indicated that CPF impeded cell cycle re-entry in quiescent lung cancer cells by reduction of FACT and c-MYC mRNA and protein levels, with concomitant decrease in H3K4 tri-methylation and RNA polymerase II occupancy at FACT and c-MYC promoter regions. Animals implanted with quiescent cancer cells that had been exposed to CPF had reduced tumour volume/weight. Thus, CPF suppresses proliferative switching through transcriptional suppression of FACT and the c-MYC, providing a new insight into therapeutic target and intervention method in impeding cancer recurrence.

Apigenin impedes cell cycle progression at G2 phase in prostate cancer cells.

As a natural flavone, apigenin is abundantly present in vegetables, fruits, oregano, tea, chamomile, wheat sprout and is regarded as a major component of the Mediterranean diet. Apigenin is known to inhibit proliferation in different cancer cell lines by inducing G2/M arrest, but it is unclear whether this action is predominantly imposed on G2 or M phases. In this study, we demonstrate that apigenin arrests prostate cancer cells at G2 phase by flow cytometric analysis of prostate cancer cells co-stained for phospho-Histone H3 and DNA. Concurrently, apigenin also reduces the mRNA and protein levels of the key regulators that govern G2-M transition. Further analysis using chromatin immunoprecipitation (ChIP) confirmed the diminished transcriptional activities of the genes coding for these regulators. Unravelling the inhibitory effect of apigenin on G2-M transition in cancer cells provides the mechanistic understanding of its action and supports the potential for apigenin as an anti-cancer agent.

Agrimol B present in Agrimonia pilosa Ledeb impedes cell cycle progression of cancer cells through G0 state arrest.

Cancer recurrence poses a significant challenge. At the cellular level, recurrence takes place as a result of reactivation of dormant cancer cells residing at G0 phase. The aim of the study was to identify compounds that can trap prostate and lung cancer cells in G0 phase from a new Chinese herb recipe, Astringent recipe, consisting of Radix Paeoniae Alba, Agrimonia pilosa Ledeb, Fructus Mume, Fritillaria thunbergii Miq., Ganoderma Lucidum Karst, and Astragalus membranaceus (Fisch.) Bunge. Astringent recipe impeded cell cycle progression in prostate and lung cancer cells by rounding them up at G0 phase by flow cytometric analysis of cancer cells stained with Hoechst 33342 and Pyronin Y, respectively, for DNA and RNA. The anti-cancer efficacy of the recipe was found to be attributable to Agrimonia pilosa Ledeb. Further study established that agrimol B, a polyphenol derived from Agrimonia pilosa Ledeb, contributed to the activity of the herb. The action of agrimol B on the cancer cells was likely derived from its effect on c-MYC, SKP2 and p27 by immunoblotting and immunofluorescence. Oral administration of Agrimonia pilosa Ledeb or agrimol B reduced growth of prostate cancer cell xenograft in animal. In conclusion, Agrimol B can enrich for prostate and lung cancer cells in G0 state and influence key regulators that govern G0 status.

Transcriptional regulation of G2/M regulatory proteins and perturbation of G2/M Cell cycle transition by a traditional Chinese medicine recipe.

ETHNOPHARMACOLOGICAL RELEVANCE: Hedyotis diffusa Willd. (H) and Scutellaria barbata D.Don (S) are ancient anti-cancer Chinese herb medicines. When combined, known as HS, it is one of the most commonly prescribed Chinese Medicines for cancer patients today in China. AIM OF THE STUDY: The prevention of disease progression is a dominant concern for the growing number of men with prostate cancer. The purpose of this work is to evaluate the action and mode of action of Chinese Medicine recipe HS in inhibiting prostate cancer progression in preclinical models. METHODS: Effects of HS were analyzed in prostate cancer cell lines by evaluating proliferation, cell cycle profile, DNA damage and key regulators responsible for G2 to M phase transition. The transcriptional activities of these regulators were determined by RT-PCR and ChIP. The efficacy of HS in vitro was validated in an animal model. RESULTS: HS treatment was observed to reduce DNA content and accumulated prostate cancer cells at the G2/M phase. Immunolabeling for phospho-Histone H3 in association with nocodazole to capture mitotic cells confirmed that HS impeded G2 to M transition. After excluding DNA damage-induced G2 arrest, it was revealed that HS reduced expression of Cyclin B1, CDK1, PLK1 and Aurora A at both protein and mRNA levels, with concomitant reduction of H3K4 tri-methylation at their promoter-regions. Animals that received oral administration of HS with a dosage relevant to clinical application showed reduced tumor volume and weight with a reduction of Cyclin B1, CDK1, PLK1 and Aurora A protein levels. CONCLUSIONS: HS acts by impeding the G2 to M transition of prostate cancer cells. It is likely that the mode of action is transcriptionally suppressing proteins governing mitotic entry, without eliciting significant DNA damage.

p27(Kip1) signaling: Transcriptional and post-translational regulation.

p27(Kip1) is an inhibitor of a broad spectrum of cyclin-dependent kinases (CDKs), and the loss of a single p27(Kip1) allele is thereby sufficient to increase tumor incidence via CDK-mediated cell cycle entry. As such, down-regulation of p27(Kip1) protein levels, in particular nuclear expressed p27(Kip1), is implicated in both disease progression and poor prognosis in a variety of cancers. p27(Kip1) expression is positively regulated by the transcription factor MENIN, and inhibited by oncogenic transcription factors MYC and PIM. However, regulation of p27(Kip1) protein expression and function is predominantly through post-translational modifications that alter both the cellular localization and the extent of E3 ubiquitin ligase-mediated degradation. Phosphorylation of p27(Kip1) at Thr(187) and Ser(10) is a prerequisite for its degradation via the E3 ubiquitin ligases SKP2 (nuclear) and KPC (cytoplasmic), respectively. Additionally, Ser(10) phosphorylated p27(Kip1) is predominantly localized in the cytoplasm due to the nuclear export protein CRM1. Another E3 ubiquitin ligase, PIRH2, degrades p27(Kip1) in both the cytoplasm and nucleus independent of phosphorylation state. As such, inhibition of cell cycle entry and progression in a variety of cancers may be achieved with therapies designed to correct p27(Kip1) localization and/or block its degradation.