No abstract

The majority of patients with prostate cancer treated with docetaxel develop resistance to it. To better understand the mechanism behind the acquisition of resistance, we conducted single-cell RNA-sequencing (scRNA-seq) of docetaxel-sensitive and -resistant variants of DU145 and PC3 prostate cancer cell lines. Overall, sensitive and resistant cells clustered separately. Differential gene expression analysis between resistant and sensitive cells revealed 182 differentially expressed genes common to both prostate cancer cell lines. A subset of these genes gave a gene expression profile in the resistant transcriptome-like–sensitive cells similar to the resistant cells. Exploration for functional gene pathways identified 218 common pathways between the two cell lines. Protein ubiquitination was the most differentially regulated pathway and was enriched in the resistant cells. Transcriptional regulator analysis identified 321 potential regulators across both cell lines. One of the top regulators identified was nuclear protein 1 (NUPR1). In contrast to the single-cell analysis, bulk analysis of the cells did not reveal NUPR1 as a promising candidate. Knockdown and overexpression of NUPR1 in the prostate cancer cells demonstrated that NUPR1 confers docetaxel resistance in both cell lines. Collectively, these data demonstrate the utility of scRNA-seq to identify regulators of drug resistance. Furthermore, NUPR1 was identified as a mediator of prostate cancer drug resistance, which provides the rationale to explore NUPR1 and its target genes for reversal of docetaxel resistance. Implications: Using single-cell sequencing of prostate cancer, we show that NUPR1 plays a role in docetaxel resistance.

Integrins that contain an integrin alpha V subunit contribute to multiple functions that promote cancer progression. The goal of this study was to determine if abituzumab (DI17E6, EMD 525797), a humanized monoclonal antibody (mAb) against integrin alpha V impacts, prostate cancer (PCa) progression. To evaluate this, PCa cells were treated with DI17E6 and its effects on proliferation, apoptosis, cell cycle, adhesion, detachment, migration, invasion and phosphorylation of downstream targets, including FAK, Akt and ERK were determined. DI17E6 promoted detachment and inhibited adhesion of PCa cells to several extracellular matrix (ECM) proteins and cells found in the bone microenvironment, but had no impact on cell viability, cell cycle and caspase 3/7 activity. DI17E6 inhibited migration and invasion of PCa cells. Additionally, DI7E6 decreased phosphorylation of FAK, Akt and ERK. These results indicate that inhibition of integrin alpha V with DI17E6 inhibits several pro-metastatic phenotypes of PCa cells and therefore provide a rationale for further evaluation of DI17E6 for diminishing PCa progression. Implications This work identifies that therapeutic targeting of integrins containing an alpha V integrin unit inhibits cancer progression and thus may be of clinical benefit.

Prostate cancer bone metastases are unique in that that majority of them induce excessive mineralized bone matrix, through undefined mechanisms, as opposed to most other cancers that induce bone resorption. Parathyroid hormone-related protein (PTHrP) is produced by prostate cancer cells and intermittent PTHrP exposure has bone anabolic effects suggesting PTHrP could contribute to the excess bone mineralization. Wnts are bone productive factors produced by prostate cancer cells and the Wnt inhibitor DKK1 has been shown to promote prostate cancer progression. These findings, in conjunction with the observation that PTHrP expression increases and DKK1 expression decreases as prostate cancer progresses led to the hypothesis that PTHrP could be a negative regulator of DKK1 expression in prostate cancer cells, and hence allow the osteoblastic activity of Wnts to be realized. To test this, we first demonstrated that PTHrP downregulated DKK1 mRNA and protein expression. We then found through multiple mutated DKK1 promoter assays that PTHrP, through c-Jun activation, downregulated the DKK1 promoter through a TCF-response element site. Furthermore, chromatin immunoprecipitation (ChIP) and reChIP assays revealed that PTHrP-mediated this effect through inducing c-Jun to bind to a transcriptional activator complex consisting of β-catenin that binds the most proximal DKK1 promoter TCF-response element. Together, these results demonstrate a novel signaling linkage between PTHrP and Wnt signaling pathways that results in downregulation of a Wnt inhibitor allowing for Wnt activity that could contribute the osteoblastic nature of prostate cancer.

Highly neutralizing SARS-CoV-2-specific human monoclonal antibodies isolated from memory B cells are broadly reactive and reactivity depends on V region somatic mutations.