Prostate cancer stem-like cells proliferate slowly and resist etoposide-induced cytotoxicity via enhancing DNA damage response

Chromatin Organization Governs Transcriptional Response and Plasticity of Cancer Stem Cells

Chromatin organization regulates transcription to influence cellular plasticity and cell fate. We explored whether chromatin nanoscale packing domains are involved in stemness and response to chemotherapy. Using an optical spectroscopic nanosensing technology we show that ovarian cancer-derived cancer stem cells (CSCs) display upregulation of nanoscale chromatin packing domains compared to non-CSCs. Cleavage under targets and tagmentation (CUT&Tag) sequencing with antibodies for repressive H3K27me3 and active H3K4me3 and H3K27ac marks mapped chromatin regions associated with differentially expressed genes. More poised genes marked by both H3K4me3 and H3K27me3 were identified in CSCs vs. non-CSCs, supporting increased transcriptional plasticity of CSCs. Pathways related to Wnt signaling and cytokine-cytokine receptor interaction were repressed in non-CSCs, while retinol metabolism and antioxidant response were activated in CSCs. Comparative transcriptomic analyses showed higher intercellular transcriptional heterogeneity at baseline in CSCs. In response to cisplatin, genes with low baseline expression levels underwent the highest upregulation in CSCs, demonstrating transcriptional plasticity under stress. Epigenome targeting drugs downregulated chromatin packing domains and promoted cellular differentiation. A disruptor of telomeric silencing 1-like (Dot1L) inhibitor blocked transcriptional plasticity, reversing stemness. These findings support that CSCs harbor upregulated chromatin packing domains, contributing to transcriptional and cell plasticity that epigenome modifiers can target.

3-Acetyl-11-keto-β-boswellic acid (AKBA) induced antiproliferative effect by suppressing Notch signaling pathway and synergistic interaction with cisplatin against prostate cancer cells

Studies on the assessment of anticancer efficacy of plant-derived phytochemicals by targeting signaling pathways have drawn a lot of attention recently for human health. Multiple investigations have proposed an involvement of Notch pathway in the processes of cancer angiogenesis and metastasis, and drug resistance. Moreover, overexpression of Notch signaling is associated with increased prostate cancer (PrCa) cell growth and development. A number of chemotherapeutic agents are reported to become resistant over a period of time and have severe side effects. To increase efficacy and lessen drug-induced toxicity, a variety of bioactive compounds have been utilized alone or as adjuncts to traditional chemotherapy. Therefore, in the present study, the potential of AKBA in inhibiting the proliferation of PrCa cells by modulating Notch signaling components and its efficacy in combination with cisplatin was investigated. The results exhibited a substantial reduction in cell survival (IC50 = 25.28 µM at 24 h and 16.50 µM at 48 h) and cellular alterations in AKBA-treated PrCa cells. Additionally, AKBA caused nuclear condensation, increased reactive oxygen species (ROS) generation, mitochondrial membrane depolarization, and caspase activation, ultimately leading to apoptosis in PrCa cells. Moreover, AKBA-elicited apoptosis was evidenced by an augmentation in the Bax to Bcl2 ratio. AKBA was also found to induce G0/G1 arrest which was substantiated by reduced cyclin D1 and CDK4 expression levels concomitantly with increased expression of p21 and p27 genes. Intriguingly, AKBA demonstrated significant downregulation of Notch signaling mediators. Furthermore, the isobolograms of the combination treatment indicated that AKBA has the potential to synergistically enhance the cytotoxic efficacy of cisplatin in DU145 cells, as evidenced by CI < 1 across all tested combinations. Overall, the results of this study suggest strong antiproliferative, apoptotic, and chemo-sensitizing potential of AKBA. Thus, AKBA holds a promising drug candidature warranting further investigation as a probable therapeutic option for both the prevention and treatment of PrCa and other solid tumors.

Role of Autophagy and AMPK in Cancer Stem Cells: Therapeutic Opportunities and Obstacles in Cancer

Cancer stem cells represent a resilient subset within the tumor microenvironment capable of differentiation, regeneration, and resistance to chemotherapeutic agents, often using dormancy as a shield. Their unique properties, including drug resistance and metastatic potential, pose challenges for effective targeting. These cells exploit certain metabolic processes for their maintenance and survival. One of these processes is autophagy, which generally helps in energy homeostasis but when hijacked by CSCs can help maintain their stemness. Thus, it is often referred as an Achilles heel in CSCs, as certain cancers tend to depend on autophagy for survival. Autophagy, while crucial for maintaining stemness in cancer stem cells (CSCs), can also serve as a vulnerability in certain contexts, making it a complex target for therapy. Regulators of autophagy like AMPK (5' adenosine monophosphate-activated protein kinase) also play a crucial role in maintaining CSCs stemness by helping CSCs in metabolic reprogramming in harsh environments. The purpose of this review is to elucidate the interplay between autophagy and AMPK in CSCs, highlighting the challenges in targeting autophagy and discussing therapeutic strategies to overcome these limitations. This review focuses on previous research on autophagy and its regulators in cancer biology, particularly in CSCs, addresses the remaining unanswered questions, and potential targets for therapy are also brought to attention.

Molecular panorama of therapy resistance in prostate cancer: a pre-clinical and bioinformatics analysis for clinical translation

Prostate cancer (PCa) is a malignant disorder of prostate gland being asymptomatic in early stages and high metastatic potential in advanced stages. The chemotherapy and surgical resection have provided favourable prognosis of PCa patients, but advanced and aggressive forms of PCa including CRPC and AVPC lack response to therapy properly, and therefore, prognosis of patients is deteriorated. At the advanced stages, PCa cells do not respond to chemotherapy and radiotherapy in a satisfactory level, and therefore, therapy resistance is emerged. Molecular profile analysis of PCa cells reveals the apoptosis suppression, pro-survival autophagy induction, and EMT induction as factors in escalating malignant of cancer cells and development of therapy resistance. The dysregulation in molecular profile of PCa including upregulation of STAT3 and PI3K/Akt, downregulation of STAT3, and aberrant expression of non-coding RNAs are determining factor for response of cancer cells to chemotherapy. Because of prevalence of drug resistance in PCa, combination therapy including co-utilization of anti-cancer drugs and nanotherapeutic approaches has been suggested in PCa therapy. As a result of increase in DNA damage repair, PCa cells induce radioresistance and RelB overexpression prevents irradiation-mediated cell death. Similar to chemotherapy, nanomaterials are promising for promoting radiosensitivity through delivery of cargo, improving accumulation in PCa cells, and targeting survival-related pathways. In respect to emergence of immunotherapy as a new tool in PCa suppression, tumour cells are able to increase PD-L1 expression and inactivate NK cells in mediating immune evasion. The bioinformatics analysis for evaluation of drug resistance-related genes has been performed.

DNA Repair and Therapeutic Strategies in Cancer Stem Cells

First-line cancer treatments successfully eradicate the differentiated tumour mass but are comparatively ineffective against cancer stem cells (CSCs), a self-renewing subpopulation thought to be responsible for tumour initiation, metastasis, heterogeneity, and recurrence. CSCs are thus presented as the principal target for elimination during cancer treatment. However, CSCs are challenging to drug target because of numerous intrinsic and extrinsic mechanisms of drug resistance. One such mechanism that remains relatively understudied is the DNA damage response (DDR). CSCs are presumed to possess properties that enable enhanced DNA repair efficiency relative to their highly proliferative bulk progeny, facilitating improved repair of double-strand breaks induced by radiotherapy and most chemotherapeutics. This can occur through multiple mechanisms, including increased expression and splicing fidelity of DNA repair genes, robust activation of cell cycle checkpoints, and elevated homologous recombination-mediated DNA repair. Herein, we summarise the current knowledge concerning improved genome integrity in non-transformed stem cells and CSCs, discuss therapeutic opportunities within the DDR for re-sensitising CSCs to genotoxic stressors, and consider the challenges posed regarding unbiased identification of novel DDR-directed strategies in CSCs. A better understanding of the DDR mediating chemo/radioresistance mechanisms in CSCs could lead to novel therapeutic approaches, thereby enhancing treatment efficacy in cancer patients.

Interplay of Developmental Hippo-Notch Signaling Pathways with the DNA Damage Response in Prostate Cancer

Prostate cancer belongs in the class of hormone-dependent cancers, representing a major cause of cancer incidence in men worldwide. Since upon disease onset almost all prostate cancers are androgen-dependent and require active androgen receptor (AR) signaling for their survival, the primary treatment approach has for decades relied on inhibition of the AR pathway via androgen deprivation therapy (ADT). However, following this line of treatment, cancer cell pools often become resistant to therapy, contributing to disease progression towards the significantly more aggressive castration-resistant prostate cancer (CRPC) form, characterized by poor prognosis. It is, therefore, of critical importance to elucidate the molecular mechanisms and signaling pathways underlying the progression of early-stage prostate cancer towards CRPC. In this review, we aim to shed light on the role of major signaling pathways including the DNA damage response (DDR) and the developmental Hippo and Notch pathways in prostate tumorigenesis. We recapitulate key evidence demonstrating the crosstalk of those pathways as well as with pivotal prostate cancer-related 'hubs' such as AR signaling, and evaluate the clinical impact of those interactions. Moreover, we attempt to identify molecules of the complex DDR-Hippo-Notch interplay comprising potentially novel therapeutic targets in the battle against prostate tumorigenesis.

Pathways Related to the Anti-Cancer Effects of Metabolites Derived from Cerrado Biome Native Plants: An Update and Bioinformatics Analysis on Oral Squamous Cell Carcinoma

BACKGROUND

Oral cancer is a significant health problem worldwide. Oral squamous cell carcinoma (OSCC) is a malignant neoplasm of epithelial cells that mostly affects different anatomical sites in the head and neck and derives from the squamous epithelium or displays similar morphological characteristics. Generally, OSCC is often the end stage of several changes in the stratified squamous epithelium, which begin as epithelial dysplasia and progress by breaking the basement membrane and invading adjacent tissues. Several plant-based drugs with potent anti-cancer effects are considered inexpensive treatments with limited side effects for cancer and other diseases.

OBJECTIVE

The aim of this review is to explore whether some Brazilian plant extracts or constituents exhibit anti-tumorigenic activity or have a cytotoxic effect on human oral carcinoma cells.

METHODS

Briefly, OSCC and several metabolites derived from Brazilian plants (i.e., flavonoids, vinblastine, irinotecan, etoposide and paclitaxel) were used as keywords to search the literature on PubMed, GenBank and GeneCards.

RESULTS

The results showed that these five chemical compounds found in Cerrado Biome plants exhibit anti-neoplastic effects. Evaluating the compounds revealed that they play a main role in the regulation of cell proliferation.

CONCLUSION

Preserving and utilising the biodiversity of our planet, especially in unique ecosystems, such as the Cerrado Biome, may prove essential to preserving and promoting human health in modern contexts.

The Contributions of Prostate Cancer Stem Cells in Prostate Cancer Initiation and Metastasis

Research in the last decade has clearly revealed a critical role of prostate cancer stem cells (PCSCs) in prostate cancer (PC). Prostate stem cells (PSCs) reside in both basal and luminal layers, and are the target cells of oncogenic transformation, suggesting a role of PCSCs in PC initiation. Mutations in PTEN, TP53, and RB1 commonly occur in PC, particularly in metastasis and castration-resistant PC. The loss of PTEN together with Ras activation induces partial epithelial–mesenchymal transition (EMT), which is a major mechanism that confers plasticity to cancer stem cells (CSCs) and PCSCs, which contributes to metastasis. While PTEN inactivation leads to PC, it is not sufficient for metastasis, the loss of PTEN concurrently with the inactivation of both TP53 and RB1 empower lineage plasticity in PC cells, which substantially promotes PC metastasis and the conversion to PC adenocarcinoma to neuroendocrine PC (NEPC), demonstrating the essential function of TP53 and RB1 in the suppression of PCSCs. TP53 and RB1 suppress lineage plasticity through the inhibition of SOX2 expression. In this review, we will discuss the current evidence supporting a major role of PCSCs in PC initiation and metastasis, as well as the underlying mechanisms regulating PCSCs. These discussions will be developed along with the cancer stem cell (CSC) knowledge in other cancer types.

Biological indicators of chemoresistance: an ex vivo analysis of γH2AX and p53 expression in feline injection-site sarcomas

Background

The response of soft tissue sarcomas to cytotoxic chemotherapy is inconsistent. Biomarkers of chemoresistance or chemosensitivity are needed in order to identify appropriate patients for treatment. Given that many chemotherapeutics kill cells through direct DNA interactions, we hypothesized that upregulation of DNA damage response mechanisms would confer resistance to cytotoxic chemotherapy in sarcomas. To study this, we used spontaneously-occurring feline injection-site sarcomas (FISS).

Methods

γH2AX and p53 expression were determined in biopsy samples of FISS. γH2AX expression was determined via immunohistochemistry whereas p53 expression was determined via qRT-PCR. Cell lines derived from these sarcoma biopsies were then treated with carboplatin (N = 11) or doxorubicin (N = 5) and allowed to grow as colonies. Colony forming-ability of cells exposed to chemotherapy was compared to matched, untreated cells and expressed as percent survival relative to controls. ImageJ was used for quantification. A mixed model analysis was performed to determine if an association existed between relative survival of the treated cells and γH2AX or p53 expression in the original tumors. Cell lines were validated via vimentin expression or growth as subcutaneous sarcomas in nude mice.

Results

An association was detected between γH2AX expression and relative survival in cells exposed to carboplatin (P = 0.0250). In the 11 FISS tumors evaluated, γH2AX expression ranged from 2.2 to 18.8% (mean, 13.3%). Cells from tumors with γH2AX expression higher than the sample population mean had fourfold greater relative survival after carboplatin exposure than cells from tumors with γH2AX expression less than the mean. There was no association between relative survival after carboplatin exposure and p53 expression (P = 0.1608), and there was no association between relative survival after doxorubicin exposure and either γH2AX (P = 0.6124) or p53 (P = 0.8645) expression. Four cell lines were validated via growth as sarcomas in nude mice. Vimentin expression was confirmed in the other 7 cell lines.

Conclusions

γH2AX expression, but not wild type p53, may potentially serve as a biomarker of resistance to platinum therapeutics in soft tissue sarcomas. To further investigate this finding, prospective, in vivo studies are indicated in animal models.

Identification of a histone family gene signature for predicting the prognosis of cervical cancer patients

Heterogeneity in terms of tumor characteristics, prognosis, and survival among cancer patients is an unsolved issue. Here, we systematically analyzed the aberrant expression patterns of cervical cancer using RNA-Seq data from The Cancer Genome Atlas (TCGA). We incorporated gene profiling, molecular signatures, functional and pathway information with gene set enrichment and protein-protein interaction (PPI) network analysis, to identify sub-networks of genes. Those identified genes relating to DNA replication and DNA repair-mediated signaling pathways associated with systemic lupus erythematosus (SLE). Next, we combined cross-validated prognostic scores to build an integrated prognostic model for survival prediction. The combined approach revealed that the DNA repair-mediated including the functional interaction module of 18 histone genes (Histone cluster 1 H2A, B and H4), were significantly correlated with the survival rate. Furthermore, five of these histone genes were highly expressed in three cervical cancer cohorts from the Oncomine database. Comparison of high and low histone variant-expressing human cervical cancer cell lines revealed different responses to DNA damage, suggesting protective functions of histone genes against DNA damage. Collectively, we provide evidence that two SLE-associated gene sets (HIST1H2BD and HIST1H2BJ; and HIST1H2BD, HIST1H2BJ, HIST1H2BH, HIST1H2AM and HIST1H4K) can be used as prognostic factors for survival prediction among cervical cancer patients.

Curcumin suppresses proliferation and in vitro invasion of human prostate cancer stem cells by ceRNA effect of miR-145 and lncRNA-ROR

Many studies have demonstrated that curcumin can effectively inhibit the proliferation, invasion, and tumorigenesis of prostate cancer cells in vitro and in vivo. In this study, CD44⁺/CD133⁺ human prostate cancer stem cells (HuPCaSCs) were isolated from the prostate cancer cell lines Du145 and 22RV1. Curcumin treatment of these cells resulted in the inhibition of in vitro proliferation and invasion, and cell cycle arrest. The expression levels of cell cycle proteins (Ccnd1 and Cdk4) and stem cell markers (Oct4, CD44, and CD133) were decreased in curcumin-treated HuPCaSCs. Microarray analysis and northern blotting assays indicated that miR-145 was overexpressed in curcumin-treated HuPCaSCs. Insights of the mechanism of competitive endogenous RNAs (ceRNAs) were gained from bioinformatic analysis, bioinformatics analysis and luciferase activity assays showed that the lncRNA-ROR and Oct4 mRNA both contain miR-145 binding sites, and Oct4 and lncRNA-ROR directly compete for microRNA binding. Curcumin induced high miR-145 expression and inhibited the expression of lncRNA-ROR. The tumorigenicity of curcumin- treated HuPCaSCs in nude mice was significantly reduced. In summary, reducing the expression of endogenous lncRNA-ROR could effectively increase the available concentration of miR-145 in HuPCaSCs, where miR-145 prevents cell proliferation by decreasing Oct4 expression. In particular, we hypothesized that lncRNA-ROR may act as a ceRNA, effectively becoming a sink for miR-145, thereby activating the derepression of core transcription factors Oct4. Thus, curcumin suppresses the proliferation, in vitro invasion, and tumorigenicity of HuPCaSCs through ceRNA effect of miR-145 and lncRNA-ROR caused.

Effect of etoposide-induced alteration of the Mdm2-Rb signaling pathway on cellular senescence in A549 lung adenocarcinoma cells

The present study aimed to investigate the effect of various concentrations of etoposide (VP-16) on the E3 ubiquitin-protein ligase Mdm2 (Mdm2)-retinoblastoma (Rb) signaling pathway in the cellular senescence of A549 lung adenocarcinoma cells. A549 cells were randomly divided into the following four groups: Control group (no treatment), group 1 (1 µmol/l VP-16), group 2 (5 µmol/l VP-16) and group 3 (25 µmol/l VP-16). Each group was cultured for 48 h after treatment prior to observation of the alterations to cellular morphology. The cell cycle distribution of each group was also detected by flow cytometry. In addition, the activity of cellular senescence-associated β-galactosidase, and the expression of Mdm2 and phosphorylated (p-) Rb protein, was measured. The percentage of senescent cells was significantly higher following VP-16 treatment compared with the control group. The percentage of G₁ phase cells, and p-Rb protein and Mdm2 protein expression were also significantly different following VP-16 treatment compared with the control group. VP-16 increased the activity of β-galactosidase in the A459 cells. VP-16 also decreased the expression level of Mdm2 and p-Rb protein and inhibited cell cycle progression in G₁. These results indicate that VP-16 induces the cellular senescence of A549 cells via the Mdm2-Rb signaling pathway. However, further investigations are required to validate the mechanisms underlying these effects of VP-16.

Multidrug-resistant cancer cells and cancer stem cells hijack cellular systems to circumvent systemic therapies, can natural products reverse this?

Chemotherapy is one of the most effective and broadly used approaches for cancer management and many modern regimes can eliminate the bulk of the cancer cells. However, recurrence and metastasis still remain a major obstacle leading to the failure of systemic cancer treatments. Therefore, to improve the long-term eradication of cancer, the cellular and molecular pathways that provide targets which play crucial roles in drug resistance should be identified and characterised. Multidrug resistance (MDR) and the existence of tumor-initiating cells, also referred to as cancer stem cells (CSCs), are two major contributors to the failure of chemotherapy. MDR describes cancer cells that become resistant to structurally and functionally unrelated anti-cancer agents. CSCs are a small population of cells within cancer cells with the capacity of self-renewal, tumor metastasis, and cell differentiation. CSCs are also believed to be associated with chemoresistance. Thus, MDR and CSCs are the greatest challenges for cancer chemotherapy. A significant effort has been made to identify agents that specifically target MDR cells and CSCs. Consequently, some agents derived from nature have been developed with a view that they may overcome MDR and/or target CSCs. In this review, natural products-targeting MDR cancer cells and CSCs are summarized and clustered by their targets in different signaling pathways.

A new model of multi-visceral and bone metastatic prostate cancer with perivascular niche targeting by a novel endothelial specific adenoviral vector

While modern therapies for metastatic prostate cancer (PCa) have improved survival they are associated with an increasingly prevalent entity, aggressive variant PCa (AVPCa), lacking androgen receptor (AR) expression, enriched for cancer stem cells (CSCs), and evidencing epithelial-mesenchymal plasticity with a varying extent of neuroendocrine transdifferentiation. Parallel work revealed that endothelial cells (ECs) create a perivascular CSC niche mediated by juxtacrine and membrane tethered signaling. There is increasing interest in pharmacological metastatic niche targeting, however, targeted access has been impossible. Here, we discovered that the Gleason 7 derived, androgen receptor negative, IGR-CaP1 cell line possessed some but not all of the molecular features of AVPCa. Intracardiac injection into NOD/SCID/IL2Rg -/- (NSG) mice produced a completely penetrant bone, liver, adrenal, and brain metastatic phenotype; noninvasively and histologically detectable at 2 weeks, and necessitating sacrifice 4-5 weeks post injection. Bone metastases were osteoblastic, and osteolytic. IGR-CaP1 cells expressed the neuroendocrine marker synaptophysin, near equivalent levels of vimentin and e-cadherin, all of the EMT transcription factors, and activation of NOTCH and WNT pathways. In parallel, we created a new triple-targeted adenoviral vector containing a fiber knob RGD peptide, a hexon mutation, and an EC specific ROBO4 promoter (Ad.RGD.H5/3.ROBO4). This vector was expressed in metastatic microvessels tightly juxtaposed to IGR-CaP1 cells in bone and visceral niches. Thus, the combination of IGR-CaP1 cells and NSG mice produces a completely penetrant metastatic PCa model emulating end-stage human disease. In addition, the metastatic niche access provided by our novel Ad vector could be therapeutically leveraged for future disease control or cure.

Stem cells and the role of ETS transcription factors in the differentiation hierarchy of normal and malignant prostate epithelium

Prostate cancer is the most common cancer of men in the UK and accounts for a quarter of all new cases. Although treatment of localised cancer can be successful, there is no cure for patients presenting with invasive prostate cancer and there are less treatment options. They are generally treated with androgen-ablation therapies but eventually the tumours become hormone resistant and patients develop castration-resistant prostate cancer (CRPC) for which there are no further successful or curative treatments. This highlights the need for new treatment strategies. In order to prevent prostate cancer recurrence and treatment resistance, all the cell populations in a heterogeneous prostate tumour must be targeted, including the rare cancer stem cell (CSC) population. The ETS transcription factor family members are now recognised as a common feature in multiple cancers including prostate cancer; with aberrant expression, loss of tumour suppressor function, inactivating mutations and the formation of fusion genes observed. Most notably, the TMPRSS2-ERG gene fusion is present in approximately 50% of prostate cancers and in prostate CSCs. However, the role of other ETS transcription factors in prostate cancer is less well understood. This review will describe the prostate epithelial cell hierarchy and discuss the evidence behind prostate CSCs and their inherent resistance to conventional cancer therapies. The known and proposed roles of the ETS family of transcription factors in prostate epithelial cell differentiation and regulation of the CSC phenotype will be discussed, as well as how they might be targeted for therapy.

Amplification of MUC1 in prostate cancer metastasis and CRPC development

Evidence supports the upregulation of MUC1 in prostate cancer (PC). However, this has not been thoroughly investigated. We report here an association of MUC1 upregulation with PC metastasis and the development of castration resistant PC (CRPC). MUC1 expression was specifically increased in DU145 cell-derived PC stem-like cells (PCSLCs) in comparison to their non-PCSLCs counterparts. While immunohistochemistry staining of 34 primary PCs revealed variability in MUC1 expression, Nanostring technology demonstrated elevated MUC1 mRNA levels in 4 of 7 PCs compared to their normal matched tissues. By analyzing MUC1 mRNA levels and gene copy number (GCN) using the OncomineTM database, elevations in MUC1 mRNA in 82 metastases versus 280 primary PCs and in MUC1 GCN in 37 metastases over 181 primary tumors were demonstrated. Analysis of genomic datasets within cBioPortal revealed increases in MUC1 GCN in 2% (6/333) of primary PCs, 6% (9/150) of metastatic PCs, and 33% (27/82) of CRPCs; in comparison, the respective increase in androgen receptor (AR) GCN was 1%, 63%, and 56%, revealing a specific increase in MUC1 GCN for CRPC. Furthermore, a 25-gene MUC1 network was amplified in 52% of CRPCs compared to 69% of CRPCs displaying increases in an AR co-regulator group. While genomic alterations in the MUC1 network largely overlap with those in the AR group, 18 CRPCs (66.7% being neuroendocrine PC) showed genomic alterations only in the MUC1 network. Moreover, genomic alterations in the MUC1 network correlated with PC relapse. Collectively, our observations suggest a combination therapy involving MUC1-based immunotherapy and androgen deprivation.

Individual and Combined Expression of DNA Damage Response Molecules PARP1, γH2AX, BRCA1, and BRCA2 Predict Shorter Survival of Soft Tissue Sarcoma Patients

DNA damage response (DDR) molecules are protective against genotoxic stresses. DDR molecules are also involved in the survival of cancer cells in patients undergoing anti-cancer therapies. Therefore, DDR molecules are potential markers of cancer progression in addition to being potential therapeutic targets. In this study, we evaluated the immunohistochemical expression of PARP1, γH2AX, BRCA1, and BRCA2 and their prognostic significance in 112 cases of soft tissue sarcoma (STS). The expression of PARP1, γH2AX, BRCA1, and BRCA2 were significantly associated with each other and were associated with higher tumor stage and presence of distant metastasis. The expression of PARP1, γH2AX, and BRCA2 were significantly associated with shorter disease-specific survival (DSS) and event-free survival (EFS) by univariate analysis. BRCA1 expression was associated with shorter DSS. Multivariate analysis revealed the expression of PARP1 and γH2AX to be independent indicators of poor prognosis of DSS and EFS. BRCA2 expression was an independent indicator of poor prognosis of DSS. In addition, the combined expressional patterns of PARP1, γH2AX, BRCA1, and BRCA2 (CSddrm) were independent prognostic predictors of DSS (P < 0.001) and EFS (P = 0.016). The ten-year DSS rate of the CSddrm-low, CSddrm-intermediate, and CSddrm-high subgroups were 81%, 26%, and 0%, respectively. In conclusion, this study demonstrates that the individual and combined expression patterns of the DDR molecules PARP1, γH2AX, BRCA1, and BRCA2 could be predictive of the prognosis of STS patients and suggests that controlling the activity of these DDR molecules could be employed in new therapeutic stratagems for the treatment of STS.

DNA damage is a feature of feline injection-site sarcoma

Feline injection-site sarcoma (FISS) is commonly treated with surgery and radiation therapy. Despite aggressive therapy, FISS has a high recurrence rate. The true benefit of adjuvant chemotherapy is not known. DNA damage response mechanisms help protect against genomic instability but can also promote chemoresistance. In order to determine whether DNA damage is a feature of FISS, we evaluated tumour tissues with γH2AX immunohistochemistry. H2AX is phosphorylated to form γH2AX following DNA double strand breaks. Seventeen FISS specimens were evaluated prospectively. DNA damage ranged from 2.18 to33.7%, with a median of 16.2%. Significant differences were noted between cats (P < 0.0001). Mitotic index ranged from 0 to 57 with a median of 13 and did not correlate with γH2AX positivity (P = 0.2). Further studies are needed to determine if γH2AX expression may predict chemosensitivity and have independent value as a prognostic factor.

Prostate Cancer Stem-like Cells Contribute to the Development of Castration-Resistant Prostate Cancer

Androgen deprivation therapy (ADT) has been the standard care for patients with advanced prostate cancer (PC) since the 1940s. Although ADT shows clear benefits for many patients, castration-resistant prostate cancer (CRPC) inevitably occurs. In fact, with the two recent FDA-approved second-generation anti-androgens abiraterone and enzalutamide, resistance develops rapidly in patients with CRPC, despite their initial effectiveness. The lack of effective therapeutic solutions towards CRPC largely reflects our limited understanding of the underlying mechanisms responsible for CRPC development. While persistent androgen receptor (AR) signaling under castration levels of serum testosterone (<50 ng/mL) contributes to resistance to ADT, it is also clear that CRPC evolves via complex mechanisms. Nevertheless, the physiological impact of individual mechanisms and whether these mechanisms function in a cohesive manner in promoting CRPC are elusive. In spite of these uncertainties, emerging evidence supports a critical role of prostate cancer stem-like cells (PCSLCs) in stimulating CRPC evolution and resistance to abiraterone and enzalutamide. In this review, we will discuss the recent evidence supporting the involvement of PCSLC in CRPC acquisition as well as the pathways and factors contributing to PCSLC expansion in response to ADT.

Metastasis initiating cells in primary prostate cancer tissues from transurethral resection of the prostate (TURP) predicts castration-resistant progression and survival of prostate cancer patients

BACKGROUND

We previously reported that the activation of RANK and c-Met signaling components in both experimental mouse models and human prostate cancer (PC) specimens predicts bone metastatic potential and PC patient survival. This study addresses whether a population of metastasis-initiating cells (MICs) known to express a stronger RANKL, phosphorylated c-Met (p-c-Met), and neuropilin-1 (NRP1) signaling network than bystander or dormant cells (BDCs) can be detected in PC tissues from patients subjected to transurethral resection of the prostate (TURP) for urinary obstruction prior to the diagnosis of PC with or without prior hormonal manipulation, and whether the relative abundance of MICs over BDCs could predict castration-resistant progression and PC patient survival.

METHODS

We employed a multiplexed quantum-dot labeling (mQDL) protocol to detect and quantify MICs and BDCs at the single cell level in TURP tissues obtained from 44 PC patients with documented overall survival and castration resistance status.

RESULTS

PC tissues with a higher number of MICs and an activated RANK signaling network, including increased expression of RANKL, p-c-Met, and NRP1 compared to BDCs, were found to correlate with the development of castration resistance and overall survival.

CONCLUSIONS

The assessment of PC cells with MIC and BDC phenotypes in primary PC tissues from hormone-naïve patients can predict the progression to castration resistance and the overall survival of PC patients.

Expression of DNA Damage Response Molecules PARP1, γH2AX, BRCA1, and BRCA2 Predicts Poor Survival of Breast Carcinoma Patients

BACKGROUND: Poly(ADP-ribose) polymerase 1 (PARP1), γH2AX, BRCA1, and BRCA2 are conventional molecular indicators of DNA damage in cells and are often overexpressed in various cancers. In this study, we aimed, using immunohistochemical detection, whether the co-expression of PARP1, γH2AX, BRCA1, and BRCA2 in breast carcinoma (BCA) tissue can provide more reliable prediction of survival of BCA patients. MATERIALS AND METHODS: We investigated immunohistochemical expression and prognostic significance of the expression of PARP1, γH2AX, BRCA1, and BRCA2 in 192 cases of BCAs. RESULTS: The expression of these four molecules predicted earlier distant metastatic relapse, shorter overall survival (OS), and relapse-free survival (RFS) by univariate analysis. Multivariate analysis revealed the expression of PARP1, γH2AX, and BRCA2 as independent poor prognostic indicators of OS and RFS. In addition, the combined expressional pattern of BRCA1, BRCA2, PARP1, and γH2AX (CSbbph) was an additional independent prognostic predictor for OS (P < .001) and RFS (P < .001). The 10-year OS rate was 95% in the CSbbph-low (CSbbph scores 0 and 1) subgroup, but that was only 35% in the CSbbph-high (CSbbph score 4) subgroup. CONCLUSION: This study has demonstrated that the individual and combined expression patterns of PARP1, γH2AX, BRCA1, and BRCA2 could be helpful in determining an accurate prognosis for BCA patients and for the selection of BCA patients who could potentially benefit from anti-PARP1 therapy with a combination of genotoxic chemotherapeutic agents.

Insights into Chemoresistance of Prostate Cancer

Prostate cancer (PCa) remains the most prevalent malignancy among males in the western world. Though hormonal therapies through chemical or surgical castration have been proposed many years ago, heretofore, such mainstay for the treatment on advanced PCa has not fundamentally changed. These therapeutic responses are temporary and most cases will eventually undergo PCa recurrence and metastasis, or even progress to castration-resistant prostate cancer (CRPC) due to persistent development of drug resistance. Prostate cancer stem cells (PCSCs) are a small population of cells, which possess unlimited self-renewal capacities, and can regenerate tumorigenic progenies, and play an essential role in PCa therapy resistance, metastasis and recurrence. Nowadays advanced progresses have been made in understanding of PCSC properties, roles of androgen receptor signaling and ATP-binding cassette sub-family G member 2 (ABCG2), as well as roles of genomic non-coding microRNAs and key signaling pathways, which have led to the development of novel therapies which are active against chemoresistant PCa and CRPC. Based on these progresses, this review is dedicated to address mechanisms underlying PCa chemoresistance, unveil crosstalks among pivotal signaling pathways, explore novel biotherapeutic agents, and elaborate functional properties and specific roles of chemoresistant PCSCs, which may act as a promising target for novel therapies against chemoresistant PCa.