Evasion of apoptosis is a major contributing factor to the development of chemo- and radiotherapy resistance. Therefore, activation of non-apoptotic programmed cell death (PCD) could be an effective alternative against apoptosis-resistant cancers. In this study, we demonstrated in vitro and in vivo that metformin can induce pyroptosis, a non-apoptotic PCD, in esophageal squamous cell carcinoma (ESCC), a commonly known chemo-refractory cancer, especially at its advanced stages. Proline-, glutamic acid- and leucine-rich protein-1 (PELP1) is a scaffolding oncogene and upregulated PELP1 in advanced stages of ESCC is highly associated with cancer progression and patient outcomes. Intriguingly, metformin treatment leads to gasdermin D (GSDMD)-mediated pyroptosis, which is abrogated by forced expression of PELP1. Mechanistically, metformin induces pyroptosis of ESCC by targeting miR-497/PELP1 axis. Our findings suggest that metformin and any other pyroptosis-inducing reagents could serve as alternative treatments for chemo- and radiotherapy refractory ESCC or other cancers sharing the same pyroptosis mechanisms.

Although androgen deprivation therapy (ADT) serves as the primary treatment option for localized or metastatic prostate cancer, most cases eventually develop into castration-resistant prostate cancer (CRPC). However, androgen receptor (AR) continues to be functional in CRPC through various mechanisms, including the development of AR splicing variants, especially ARV7. Since it lacks the ligand binding domain but retains the intact DNA binding domain, ARV7 is constitutively active, which makes ARV7-positive prostate cancer responsive to neither abiraterone nor enzalutamide. In this study, we explored the effect of resveratrol on ARV7 transcriptional activity and the potential for development of resveratrol as a treatment for ARV7-positive prostate cancer. First, we ectopically expressed ARV7 in PC3 cells, an AR-negative prostate cancer cell line, and demonstrated that resveratrol is capable of inhibiting ARV7 transcriptional activity by downregulating ARV7 protein levels. Of note, resveratrol does not affect the mRNA levels of ARV7 nor its nuclear translocation. Next, we demonstrated that resveratrol is capable of downregulating the levels of the endogenously expressed ARV7 as well as AR target gene mRNAs in 22RV1 prostate cancer cells. Mechanistically, resveratrol downregulates ARV7 by enhancing ARV7 polyubiquitination and subsequent proteasome-mediated degradation. These findings suggest that resveratrol could be a potential treatment for ARV7-positive CPRC.

In recent years, long non-coding RNAs (lncRNAs) are of great importance in development of different types of tumors, while the function of lncRNA ZFAS1 is rarely discussed in esophageal squamous cell carcinoma (ESCC). Therefore, we performed this study to explore the expression of exosomal lncRNA ZFAS1 and its molecular mechanism on ESCC progression.

Despite the initial benefit from treating ERBB2-positive breast cancer with tyrosine kinase inhibitor lapatinib, resistance develops inevitably. Since the expression of protein tyrosine phosphatase receptor-type O (PTPRO), a member of the R3 subfamily of receptor protein tyrosine phosphatases (PTPs), is inversely correlated with the aggressiveness of multiple malignancies, we decided to explore the correlation between PTPRO and lapatinib resistance in ERBB2-positive breast cancer. Results of immunohistochemical (IHC) staining and the correlation analysis between the expression levels of PTPRO and the clinicopathological parameters indicate that PTPRO is downregulated in cancer tissues as compared with normal tissues and negatively associated with differentiation, tumor size, tumor depth, as well as the expression of ERBB2 and Ki67. Results from Kaplan-Meier analyses indicate that lower expression of PTPRO is correlated with shorter relapse-free survival for patients with ERBB2-positive breast cancer, and multivariable Cox regression analysis found that PTPRO can potentially serve as an independent prognostic indicator for ERBB2-positive breast cancer. Results from both human breast cancer cells with PTPRO knockdown or overexpression and mouse embryonic fibroblasts (MEFs) which derived from Ptpro +/+ and Ptpro -/- mice with then stably transfected plasmid FUGW-Erbb2 consistently demonstrated the essentiality of PTPRO in the lapatinib-mediated anticancer process. Our findings suggest that PTPRO is not only able to serve as an independent prognostic indicator, but upregulating PTPRO can also reverse the lapatinib resistance of ERBB2-positive breast cancer.

Chimeric RNAs (chiRNAs) play many previously unrecognized roles in different diseases including cancer. They can not only be used as biomarkers for diagnosis and prognosis of various diseases but also serve as potential therapeutic targets. In order to better understand the roles of chiRNAs in pathogenesis, we inserted human sequences into mouse genome and established a knockin mouse model of the tamoxifen-inducible expression of ASTN2-PAPPA antisense chimeric RNA (A-PaschiRNA). Mice carrying the A-PaschiRNA knockin gene do not display any apparent abnormalities in growth, fertility, histological, hematopoietic, and biochemical indices. Using this model, we dissected the role of A-PaschiRNA in chemical carcinogen 4-nitroquinoline 1-oxide (4NQO)-induced carcinogenesis of esophageal squamous cell carcinoma (ESCC). To our knowledge, we are the first to generate a chiRNA knockin mouse model using the Cre-loxP system. The model could be used to explore the roles of chiRNA in pathogenesis and potential targeted therapies.

Hypercholesterolemia is a prevalent metabolic disorder that has been implicated in the development of steroid-targeted cancers. However, the link between hypercholesterolemia and urinary bladder cancer (UBC), a non-steroid-targeted cancer, remains unresolved. Here we show that diet-induced and Ldlr deficiency-induced hypercholesterolemia enhances both UBC stemness and progression. Inhibition of intestinal cholesterol absorption by ezetimibe reversed diet-induced hypercholesterolemia and cancer stemness. As a key component in hypercholesterolemic sera, oxidized low-density lipoprotein (ox-LDL), but not native low-density lipoprotein-cholesterol or metabolite 27-hydroxycholesterol, increased cancer stemness through its receptor CD36. Depletion of CD36, ectopic expression of an ox-LDL binding-disabled mutant form of CD36(K164A), and the neutralization of ox-LDL and CD36 via neutralizing antibodies all reversed ox-LDL-induced cancer stemness. Mechanistically, ox-LDL enhanced the interaction of CD36 and JAK2, inducing phosphorylation of JAK2 and subsequently activating STAT3 signaling, which was not mediated by JAK1 or Src in UBC cells. Finally, ox-LDL levels in serum predicted poor prognosis, and the ox-LDLhigh signature predicted worse survival in patients with UBC. These findings indicate that ox-LDL links hypercholesterolemia with UBC progression by enhancing cancer stemness. Lowering serum ox-LDL or targeting the CD36/JAK2/STAT3 axis might serve as a potential therapeutic strategy for UBCs with hypercholesterolemia. Moreover, elevated ox-LDL may serve as a biomarker for UBC. SIGNIFICANCE: This study demonstrates how hypercholesterolemia-induced oxidized LDL promotes urinary bladder cancer stemness via a CD36/STAT3 signaling axis, highlighting these factors as biomarkers and potential therapeutic targets of aggressive disease.

Lung cancer is the most commonly diagnosed cancer worldwide and it is also the most leading cause of cancer-related deaths. Although multiple generations of targeted therapeutic drugs such as gefitinib and afatinib specifically targeting the epidermal growth factor receptor (EGFR) pathway are currently available for lung cancer treatment, none of them can escape their eventual drug-resistance. As a key component of Cordyceps Sinensis and widely used in traditional Chinese medicines (TCM), cordycepin (CD) has attracted increasing attention to both scientists and clinicians. We aimed to explore the potential in developing cordycepin (CD) as an anti-lung cancer drug. A systematic analysis was conducted on a panel of non-small cell lung cancer (NSCLC) cell lines to identify the cells sensitive to CD. We found that CD can affect different aspects of lung cancer development including proliferation, migration, invasion, cell cycle, and apoptosis. We then explored the underlying molecular mechanisms of CD-mediated NSCLC cell apoptosis by conducting a series of in vitro and in vivo experiments. We found that in addition to affecting different stages of NSCLC development including tumor growth, migration, and invasion, the CD is capable of inhibiting NSCLC cell cycle progression and inducing cancer cell apoptosis without apparent adverse effect on normal lung cells. Furthermore, we found that the cells containing EGFR mutations are more sensitive to CD treatment than those without. Mechanistically, CD induces NSCLC cell apoptosis by interacting with and activating AMP-activated protein kinase (AMPK). More importantly, we found that the potency of CD's anticancer effect both in vitro and in vivo is comparable to afatinib and even better than gefitinib. Our findings suggest that CD either by itself or in combination with the currently available targeted therapeutic drugs might be additional therapeutic options for drug-resistance NSCLC treatment.

Although the newly developed second-generation anti-androgen drug enzalutamide can repress prostate cancer progression significantly, it only extends the survival of prostate cancer patients by 4-6 months mainly due to the occurrence of enzalutamide resistance. Most of the previous studies on AR antagonist resistance have been focused on AR signaling. Therefore, the non-AR pathways on enzalutamide resistance remain largely unknown. By using C4-2, CWR22Rv1 and LNCaP cell lines, as well as mice bearing CWR22Rv1 xenografts treated with either enzalutamide or metformin alone or in combination, we demonstrated that metformin is capable of reversing enzalutamide resistance and restores sensitivity of CWR22Rv1 xenografts to enzalutamide. We showed that metformin alleviated resistance to enzalutamide by inhibiting EMT. Furthermore, based on the effect of metformin on the activation of STAT3 and expression of TGF-β1, we propose that metformin exerts its effects by targeting the TGF-β1/STAT3 axis. These findings suggest that combination of metformin with enzalutamide could be a more efficacious therapeutic strategy for the treatment of castration-resistant prostate cancer.

High tumor recurrence is frequently observed in patients with urinary bladder cancers (UBCs), with the need for biomarkers of prognosis and drug response. Chemoresistance and subsequent recurrence of cancers are driven by a subpopulation of tumor initiating cells, namely cancer stem-like cells (CSCs). However, the underlying molecular mechanism in chemotherapy-induced CSCs enrichment remains largely unclear. In this study, we found that during gemcitabine treatment lncRNA-Low Expression in Tumor (lncRNA-LET) was downregulated in chemoresistant UBC, accompanied with the enrichment of CSC population. Knockdown of lncRNA-LET increased UBC cell stemness, whereas forced expression of lncRNA-LET delayed gemcitabine-induced tumor recurrence. Furthermore, lncRNA-LET was directly repressed by gemcitabine treatment-induced overactivation of TGFβ/SMAD signaling through SMAD binding element (SBE) in the lncRNA-LET promoter. Consequently, reduced lncRNA-LET increased the NF90 protein stability, which in turn repressed biogenesis of miR-145 and subsequently resulted in accumulation of CSCs evidenced by the elevated levels of stemness markers HMGA2 and KLF4. Treatment of gemcitabine resistant xenografts with LY2157299, a clinically relevant specific inhibitor of TGFβRI, sensitized them to gemcitabine and significantly reduced tumorigenecity in vivo. Notably, overexpression of TGFβ1, combined with decreased levels of lncRNA-LET and miR-145 predicted poor prognosis in UBC patients. Collectively, we proved that the dysregulated lncRNA-LET/NF90/miR-145 axis by gemcitabine-induced TGFβ1 promotes UBC chemoresistance through enhancing cancer cell stemness. The combined changes in TGFβ1/lncRNA-LET/miR-145 provide novel molecular prognostic markers in UBC outcome. Therefore, targeting this axis could be a promising therapeutic approach in treating UBC patients.

MiR-150, a major modulator negatively regulating the development and differentiation of various immune cells, is widely involved in orchestrating inflammation. In transplantation immunity, miR-150 can effectively induce immune tolerance, although the underlying mechanisms have not been fully elucidated. In the current study, we found that miR-150 is elevated after blocking CD28/B7 co-stimulatory signaling pathway and impaired IL-2 production by targeting ARRB2. Further investigation suggested that miR-150 not only repressed the level of ARRB2/PDE4 directly but also prevented AKT/ARRB2/PDE4 trimer recruitment into the lipid raft by inhibiting the activities of PI3K and AKT through the cAMP-PKA-Csk signaling pathway. This leads to the interruption of cAMP degradation and subsequently results in inhibition of the NF-kB pathway and reduced production of both IL-2 and TNF. In conclusion, our study demonstrated that miR-150 can effectively prevent CD28/B7 co-stimulatory signaling transduction, decrease production of inflammatory cytokines, such as IL-2 and TNF, and elicit the induction of immune tolerance. Therefore, miR-150 could become a novel potential therapeutic target in transplantation immunology.

Genetic factors contribute to more than 40% of prostate cancer risk, and mutations in BRCA1 and BRCA2 are well-established risk factors. By using target capture-based deep sequencing to identify potential pathogenic germline mutations, followed by Sanger sequencing to determine the loci of the mutations, we identified a novel pathogenic BRCA2 mutation caused by a cytosine-to-guanine base substitution at position 4211, resulting in protein truncation (p.Ser1404Ter), which was confirmed by immunohistochemistry. Analysis of peripheral blood also identified benign polymorphisms in BRCA2 (c.7397T>C, p.Val2466Ala) and SRD5A2 (c.87G>C, p.Lys29Asn). Analysis of tumor tissues revealed seven somatic mutations in prostate tumor tissue and nine somatic mutations in esophageal squamous carcinoma tissue (single nucleotide polymorphisms, insertions, and deletions). Five-year follow-up results indicate that ADT combined with radiotherapy successfully treated the prostate cancer. To our knowledge, we are the first to report the germline BRCA2 mutation c.4211C>G (p.Ser1404Ter) in prostate cancer. Combined ADT and radiotherapy may be effective in treating other patients with prostate cancer caused by this or similar mutations.

Stargardt disease-4 (STGD4) is an autosomal dominant complex, genetically heterogeneous macular degeneration/dystrophy (MD) disorder. In this paper, we used targeted next generation sequencing and multiple molecular dynamics analyses to identify and characterize a disease-causing genetic variant in four generations of a Chinese family with STGD4-like MD. We found a novel heterozygous missense mutation, c.734T>C (p.L245P) in the PROM1 gene. Structurally, this mutation most likely impairs PROM1 protein stability, flexibility, and amino acid interaction network after changing the amino acid residue Leucine into Proline in the basic helix-loop-helix leucine zipper domain. Molecular dynamic simulation and principal component analysis provide compelling evidence that this PROM1 mutation contributes to disease causativeness or susceptibility variants in patients with STGD4-like MD. Thus, this finding defines new approaches in genetic characterization, accurate diagnosis, and prevention of STGD4-like MD.

Neuroendocrine prostate cancer (NEPC) is a more aggressive subtype of castration-resistant prostate cancer (CRPC). Although it is well established that PHF8 can enhance prostate cancer cell proliferation, whether PHF8 is involved in prostate cancer initiation and progression is relatively unclear. By comparing the transgenic adenocarcinoma of the mouse prostate (TRAMP) mice with or without Phf8 knockout, we systemically examined the role of PHF8 in prostate cancer development. We found that PHF8 plays a minimum role in initiation and progression of adenocarcinoma. However, PHF8 is essential for NEPC because not only is PHF8 highly expressed in NEPC but also animals without Phf8 failed to develop NEPC. Mechanistically, PHF8 transcriptionally upregulates FOXA2 by demethylating and removing the repressive histone markers on the promoter region of the FOXA2 gene, and the upregulated FOXA2 subsequently regulates the expression of genes involved in NEPC development. Since both PHF8 and FOXA2 are highly expressed in NEPC tissues from patients or patient-derived xenografts, the levels of PHF8 and FOXA2 can either individually or in combination serve as NEPC biomarkers and targeting either PHF8 or FOXA2 could be potential therapeutic strategies for NEPC treatment. © 2020 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.