Prostate cancer (PCa) is a very complex disease that is a major cause of death in men worldwide. Currently, PCa dependence on the androgen receptor (AR) has resulted in use of AR antagonists and anti-androgen therapies that reduce endogenous steroid hormone production. However, within two to three years of receiving first line androgen deprivation therapy, the majority of patients diagnosed with PCa progress to castration resistant prostate cancer (CRPC). There is an urgent need for therapies that are more durable than antagonism of the AR axis. Studies of Runt-related transcription factors (RUNX) and their heterodimerization partner, Core-Binding Factor Subunit b (CBFβ), are revealing that the RUNX family are drivers of CRPC. In this review, we describe what is presently understood about RUNX members in PCa, including what regulates and is regulated by RUNX proteins, and the role of RUNX proteins in the tumor microenvironment and AR signaling. We discuss the implications for therapeutically targeting RUNX, the potential for RUNX as PCa biomarkers, and the current pressing questions in the field.
Manumycin A (MA) is a well-tolerated natural antibiotic showing pleiotropic anticancer effects in various preclinical in vitro and in vivo models. Anticancer drugs may themselves act as stressors to induce the cellular adaptive mechanism that can minimize their cytotoxicity. Heat shock proteins (HSPs) as cytoprotective factors can counteract the deleterious effects of various stressful stimuli. In this study, we examined whether the anticancer effects of MA can be counteracted by the mechanism related to HSPs belonging to the HSPA (HSP70) family. We found that MA caused cell type-specific alterations in the levels of HSPAs. These changes included concomitant upregulation of the stress-inducible (HSPA1 and HSPA6) and downregulation of the non-stress-inducible (HSPA2) paralogs. However, neither HSPA1 nor HSPA2 were necessary to provide protection against MA in lung cancer cells. Conversely, the simultaneous repression of several HSPA paralogs using pan-HSPA inhibitors (VER-155008 or JG-98) sensitized cancer cells to MA. We also observed that genetic ablation of the heat shock factor 1 (HSF1) transcription factor, a main transactivator of HSPAs expression, sensitized MCF7 cells to MA treatment. Our study reveals that inhibition of HSF1-mediated heat shock response (HSR) can improve the anticancer effect of MA. These observations suggest that targeting the HSR- or HSPA-mediated adaptive mechanisms may be a promising strategy for further preclinical developments.
The clinical success of combined androgen deprivation therapy (ADT) and radiation therapy (RT) in prostate cancer (PCa) created interest in understanding the mechanistic links between androgen receptor (AR) signaling and the DNA damage response (DDR). Convergent data have led to a model where AR both regulates, and is regulated by, the DDR. Integral to this model is that the AR regulates the transcription of DDR genes both at steady state and in response to ionizing radiation (IR). In this study, we sought to determine which immediate transcriptional changes are induced by IR in an AR-dependent manner. Using PRO-seq to quantify changes in nascent RNA transcription in response to IR, the AR antagonist enzalutamide, or the combination of the two, we find that enzalutamide treatment significantly decreased expression of canonical AR target genes but had no effect on DDR gene sets in PCa cells. Surprisingly, we also found that the AR is not a primary regulator of DDR genes either in response to IR or at steady state in asynchronously growing PCa cells. Our data indicate that the clinical benefit of ADT and RT is not due to the direct regulation of DDR gene transcription by AR.
Cluster of differentiation (CD81) is a type of protein, which is encoded by CD81 gene. Beside that CD81 is also known under other names such as Target of the Antiproliferative Antibody 1 (TAPA-1) and Tetraspanin-28 (TSPAN28). Location of CD81 is known to be on chromosome 11 (11p15.5), where it contains 15-20 bases in length. It is expressed mostly in cells of testis, ovary, endometrium, placenta, bone marrow, smooth muscles and others. The main function of the CD81 protein is to mediate signal transduction events, which are important for cells' development, activation, growth and motility. The CD81 gene is also known as a candidate for many malignancies because of its location. The characteristic feature of CD81 is that it is highly hydrophobic and contains a short N-and C-terminal cytoplasmic domains together with cytoplasmic cysteines, potential sites of palmitoylation as well as four transmembrane domains where they together hold the protein in a cell membrane. There are two CD81 isoforms, isoform 1 and isoform 2. Isoforms of CD81 are usually found in a tumor-suppressor region where they have a great impact on tumor development. There has always been a high interest in research on CD81 function in viral disease development. In fact, it is known that CD81 contributes in the development of diseases such as hepatitis C, malaria and various types of cancer. Since the complete effect of CD81 is unknown, further research and scientific methodology could potentially discover all possible functions and mechanisms regulated by the CD81 protein in human body.
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