Rationale for combination of paclitaxel and CDK4/6 inhibitor in ovarian cancer therapy - non-mitotic mechanisms of paclitaxel

Chemotherapy-Induced Alopecia by Docetaxel: Prevalence, Treatment and Prevention

Docetaxel is a commonly used taxane chemotherapeutic agent in the treatment of a variety of cancers, including breast cancer, ovarian cancer, prostate cancer, non-small cell lung cancer, gastric cancer, and head and neck cancer. Docetaxel exerts its anti-cancer effects through inhibition of the cell cycle and induction of proapoptotic activity. However, docetaxel also impacts rapidly proliferating normal cells in the scalp hair follicles (HFs), rendering the HFs vulnerable to docetaxel-induced cell death and leading to chemotherapy-induced alopecia (CIA). In severe cases, docetaxel causes persistent or permanent CIA (pCIA) when hair does not grow back completely six months after chemotherapy cessation. Hair loss has severe negative impacts on patients' quality of life and may even compromise their compliance with treatment. This review discusses the notable prevalence of docetaxel-induced CIA and pCIA, as well as their prevention and management. At this moment, scalp cooling is the standard of care to prevent CIA. Treatment options to promote hair regrowth include but are not limited to minoxidil, photobiomodulation (PBMT), and platelet-rich plasma (PRP). In addition, a handful of current clinical trials are exploring additional agents to treat or prevent CIA. Research models of CIA, particularly ex vivo human scalp HF organ culture and in vivo mouse models with human scalp xenografts, will help expedite the translation of bench findings of CIA prevention and/or amelioration to the clinic.

Epigenomic Profiling Advises Therapeutic Potential of Leukotriene Receptor Inhibitors for a Subset of Triple-Negative Breast Tumors

Triple-negative breast cancer (TNBC) is the most aggressive molecular subtype, with a poor survival rate compared to others subtypes. For a long time, chemotherapy was the only systemic treatment for TNBC, and the identification of actionable molecular targets might ultimately improve the prognosis for TNBC patients. We performed a genome-wide analysis of DNA methylation at CpG islands on a collection of one hundred ten breast carcinoma samples and six normal breast tissue samples using reduced representation bisulfite sequencing with the XmaI restriction enzyme (XmaI-RRBS) and identified a subset of TNBC samples with significant hypomethylation at the LTB4R/LTB4R2 genes' CpG islands, including CpG dinucleotides covered with cg12853742 and cg21886367 HumanMethylation 450K microarray probes. Abnormal DNA hypomethylation of this region in TNBC compared to normal samples was confirmed by bisulfite Sanger sequencing. Gene expression generally anticorrelates with promoter methylation, and thus, the promoter hypomethylation detected and confirmed in our study might be revealed as an indirect marker of high LTB4R/LTB4R2 expression using a simple methylation-sensitive PCR test. Analysis of RNA-seq expression and DNA methylation data from the TCGA dataset demonstrates that the expression of the LTB4R and LTB4R2 genes significantly negatively correlates with DNA methylation at both CpG sites cg12853742 (R = -0.4, p = 2.6 × 10-6; R = -0.21, p = 0.015) and cg21886367 (R = -0.45, p = 7.3 × 10-8; R = -0.24, p = 0.005), suggesting the upregulation of these genes in tumors with abnormal hypomethylation of their CpG island. Kaplan-Meier analysis using the TCGA-BRCA gene expression and clinical data revealed poorer overall survival for TNBC patients with an upregulated LTB4R. To this day, only the leukotriene inhibitor LY255283 has been tested on an MCF-7/DOX cell line, which is a luminal A breast cancer molecular subtype. Other studies compare the effects of Montelukast and Zafirlukast (inhibitors of the cysteinyl leukotriene receptor, which is different from LTB4R/LTB4R2) on the MDA-MB-231 (TNBC) cell line, with high methylation and low expression levels of LTB4R. In our study, we assess the therapeutic effects of various drugs (including leukotriene receptor inhibitors) with the DepMap gene effect and drug sensitivity data for TNBC cell lines with hypomethylated and upregulated LTB4R/LTB4R2 genes. LY255283, Minocycline, Silibinin, Piceatannol, Mitiglinide, 1-Azakenpaullone, Carbetocin, and Pim-1-inhibitor-2 can be considered as candidates for the additional treatment of TNBC patients with tumors demonstrating LTB4R/LTB4R2 hypomethylation/upregulation. Finally, our results suggest that the epigenetic status of leukotriene B4 receptors is a novel, potential, predictive, and prognostic biomarker for TNBC. These findings might improve individualized therapy for TNBC patients by introducing new therapeutic adjuncts as anticancer agents.

Inhibiting MEK1 R189 citrullination enhances the chemosensitivity of docetaxel to multiple tumour cells

Drug resistance is still a big challenge for cancer patients. We previously demonstrated that inhibiting peptidylarginine deiminase 2 (PADI2) enzyme activity with Cl-amine increases the efficacy of docetaxel (Doc) on tamoxifen-resistant breast cancer cells with PADI2 expression. However, it is not clear whether this effect applies to other tumour cells. Here, we collected four types of tumour cells with different PADIs expression and fully evaluated the inhibitory effect of the combination of PADIs inhibitor (BB-Cla) and Doc in vitro and in vivo on tumour cell growth. Results show that inhibiting PADIs combined with Doc additively inhibits tumour cell growth across the four tumour cells. PADI2-catalysed citrullination of MEK1 Arg 189 exists in the four tumour cells, and blocking the function of MEK1 Cit189 promotes the anti-tumour effect of Doc in these tumour cells. Further analysis shows that inhibiting MEK1 Cit189 decreases the expression of cancer cell stemness factors and helps prevent cancer cell stemness maintenance. Importantly, this combined treatment can partially restore the sensitivity of chemotherapy-resistant cells to docetaxel or cisplatin in tumour cells. Thus, our study provides an experimental basis for the combined therapeutic approaches using docetaxel- and PADIs inhibitors-based strategies in tumour treatment. This article is part of the Theo Murphy meeting issue 'The virtues and vices of protein citrullination'.