Shao-Chun Wang

Poly(ADP-ribose) polymerase (PARP) inhibitors (PARPis) are used to treat BRCA -mutated (BRCAm) cancer patients; however, resistance has been observed. Therefore, biomarkers to indicate PARPi resistance and combination therapy to overcome that are urgently needed. We identified a high prevalence of activated FGF receptor 3 (FGFR3) in BRCAm triple-negative breast cancer (TNBC) cells with intrinsic and acquired PARPi resistance. FGFR3 phosphorylated PARP1 at tyrosine 158 (Y158) to recruit BRG1 and prolong chromatin-loaded MRE11, thus promoting homologous recombination (HR) to enhance PARPi resistance. FGFR inhibition prolonged PARP trapping and synergized with PARPi in vitro and in vivo. High-level PARP1 Y158 phosphorylation (p-Y158) positively correlated with PARPi resistance in TNBC patient–derived xenograft models, and in PARPi-resistant TNBC patient tumors. These findings reveal that PARP1 p-Y158 facilitates BRG1-mediated HR to resolve the PARP-DNA complex, and PARP1 p-Y158 may indicate PARPi resistance that can be relieved by combining FGFR inhibitors (FGFRis) with PARPis. In summary, we show that FGFRi restores PARP trapping and PARPi antitumor efficacy in PARPi-resistant breast cancer by decreasing HR through the PARP1 p-Y158/BRG1/MER11 axis, suggesting that PARP1 p-Y158 is a biomarker for PARPi resistance that can be overcome by combining FGFRis with PARPis.

Background: MicroRNAs (miRNAs) are epigenetic regulators of T cell maturation and exhaustion. However, the mechanisms by which miRNAs influence T cell function in tumor environments remain unclear. This study focuses on miR-379-5p, which counteracts T cell exhaustion and enhances antitumor responses. Methods: Native CD8⁺ T cells were isolated from the blood of healthy donors and subjected to chronic stimulation to induce exhaustion. RNA sequencing and miRNA sequencing were performed to identify differentially expressed miRNAs. These miRNAs underwent bioinformatics analyses, including DESeq enrichment, immune cell infiltration assessment, and patient prognostic outcomes in The Cancer Genome Atlas data sets to assess their potential involvement in T cell exhaustion and antitumor immunity. The biological functions of miRNA on T cell differentiation, cytotoxic killing, and immune checkpoint regulation were investigated using in vitro assays, OT-I B16F10-OVA models, and patient-derived tumor organoids. Results: MiR-379-5p is downregulated in exhausted T cells and negatively associated with exhausted tumor-infiltrating lymphocytes in advanced tumors. It correlates positively with better survival outcomes in breast cancer, cervical cancer and melanoma. In CD8⁺ T cells, miR-379-5p reduces the expression of immune checkpoint proteins T cell immunoglobulin and mucin-domain containing-3 (TIM3) and T cell immunoreceptor with Ig and ITIM domains (TIGIT) by targeting their 3’ untranslated region. Overexpression of miR-379-5p in CD8⁺ T cell promotes differentiation into memory-like T effector cells and enhances cytotoxic killing of cancer cells. The transcription factor nuclear receptor subfamily 4 group A member 1 (NR4A1) with increased expression in exhausted T cells and negatively regulates miR-379, restoring immune checkpoint expression and suppressing cancer-killing ability. In contrast, OT-I T cells expressing ectopic miR-379-5p show increased cytotoxicity against B16F10-OVA tumors in mice. Autologous T cells isolated from patients with breast cancer transduced with miR-379-5p significantly improve killing of tumor organoids derived from the same patients. Conclusions: MiR-379-5p acts as an epigenetic tumor suppressor by enhancing CD8⁺ T cell effector functions and suppressing T cell exhaustion. MiR-379-5p could represent a novel marker and strategy for cancer immunotherapy, offering promising avenues for enhancing antitumor immune responses.

T‐cell‐based immunotherapy holds promise for eliminating cancer through T‐cell activation. However, prolonged interaction between T cells and tumors and the presence of immunosuppressive factors can diminish T‐cell cytotoxicity, leading to treatment failure. Here, ribonuclease 1 (RNase1), which degrades RNA, reduced the expression of effector cytokines and increases immune checkpoint protein levels, inducing T‐cell dysfunction. RNase1 expression is positively associated with exhausted T‐cell gene signatures and immune checkpoint proteins across several cancer types. Cancer cells expressing RNase1 are resistant to CD8⁺ T‐cell‐mediated killing. RNase1 promotes tumor growth in immunocompetent, but not in immunodeficient, mouse models and inhibits CD8⁺ T‐cell activity in vivo. Mechanistically, RNase1 enters T cells and deactivates signal transducer and activator of transcription 1 (STAT1), causing T‐cell dysfunction. Loss of RNase1‐STAT1 interaction restores CD8⁺ T‐cell cytotoxicity. Notably, a study has found RNase1 might activate CD4⁺ T cells to inhibit breast cancer growth, while another has indicated it causes immunosuppression in liver cancer. The current research shows that RNase1 does not impact CD4⁺ T cells in vivo. Overall, the study supports the immunosuppressive role of RNase1 in cancer of negatively regulating STAT1 to impair CD8⁺ T‐cell cytotoxicity. Targeting the RNase1‐STAT1 interaction could prevent CD8⁺ T‐cell dysfunction in RNase1‐highly expressing cancer patients.

The intricately orchestrated progression of mammary tissue development involves the precise coordination of gland differentiation and cellular proliferation. Nevertheless, the understanding of the role and regulatory mechanisms governing the DNA replication machinery in mammary gland development remains limited. Given the essential role of DNA replication in the viability of living cells, any genetic disturbance to its replicative function, in any form, will impede organ development. This circumstance poses a technical challenge in elucidating the potential function of cell proliferation in mammary morphogenesis. PCNA is crucial in DNA replication, playing a pivotal role in the development of complete eukaryotic organisms. The phosphorylation of PCNA at tyrosine 211 (Y211) has been demonstrated to play a significant role in supporting replication forks and, consequently, cell proliferation. Therefore, the utilization of a knock-in mouse model, wherein the Y211 residue of PCNA is replaced with phenylalanine (211F), presents an opportunity to evaluate the impact of reduced cell proliferation potential on mammary gland development. Interestingly, the lack of Y211 phosphorylation did not significantly impact the rates of proliferation or cell death in the mammary gland. In contrast, the absence of Y211PCNA led to an increased, rather than reduced, growth of the mammary gland. This was evident in assessments of gland length and the number of terminal end buds (TEBs) in both postnatal and virgin mammary glands. Notably, this observation correlated with an elevation in tissue stemness within the 211F glands compared to the WT glands. Additionally, it was consistent with the greater body weight gains observed in 211F pups compared to WT pups during the weaning period. Our findings unveil an unexpected aspect that may carry significance for mammary development. This newfound is associated with the regulation of a central component within the DNA replication machinery, providing insights into the intricate interplay governing mammary tissue expansion. Keyword: mammary gland; PCNA; phosphorylation

Tumor-secreted factors contribute to the development of a microenvironment that facilitates the escape of cancer cells from immunotherapy. In this study, we conduct a retrospective comparison of the proteins secreted by hepatocellular carcinoma (HCC) cells in responders and non-responders among a cohort of ten patients who received Nivolumab (anti-PD-1 antibody). Our findings indicate that non-responders have a high abundance of secreted RNase1, which is associated with a poor prognosis in various cancer types. Furthermore, mice implanted with HCC cells that overexpress RNase1 exhibit immunosuppressive tumor microenvironments and diminished response to anti-PD-1 therapy. RNase1 induces the polarization of macrophages towards a tumor growth-promoting phenotype through activation of the anaplastic lymphoma kinase (ALK) signaling pathway. Targeting the RNase1/ALK axis reprograms the macrophage polarization, with increased CD8⁺ T- and Th1- cell recruitment. Moreover, simultaneous targeting of the checkpoint protein PD-1 unleashes cytotoxic CD8⁺ T-cell responses. Treatment utilizing both an ALK inhibitor and an anti-PD-1 antibody exhibits enhanced tumor regression and facilitates long-term immunity. Our study elucidates the role of RNase1 in mediating tumor resistance to immunotherapy and reveals an RNase1-mediated immunosuppressive tumor microenvironment, highlighting the potential of targeting RNase1 as a promising strategy for cancer immunotherapy in HCC.

The Coronavirus Disease 2019 (COVID-19) pandemic continues to infect people worldwide. While the vaccinated population has been increasing, the rising breakthrough infection persists in the vaccinated population. For living with the virus, the dietary guidelines to prevent virus infection are worthy of and timely to develop further. Tannic acid has been demonstrated to be an effective inhibitor of coronavirus and is under clinical trial. Here we found that two other members of the tannins family, oligomeric proanthocyanidins (OPCs) and punicalagin, are also potent inhibitors against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection with different mechanisms. OPCs and punicalagin showed inhibitory activity against omicron variants of SARS-CoV-2 infection. The water extractant of the grape seed was rich in OPCs and also exhibited the strongest inhibitory activities for viral entry of wild-type and other variants in vitro. Moreover, we evaluated the inhibitory activity of grape seed extractants (GSE) supplementation against SARS-CoV-2 viral entry in vivo and observed that serum samples from the healthy human subjects had suppressive activity against different variants of SARS-CoV-2 Vpp infection after taking GSE capsules. Our results suggest that natural tannins acted as potent inhibitors against SARS-CoV-2 infection, and GSE supplementation could serve as healthy food for infection prevention.

The COVID-19 pandemic continues to infect people worldwide. While the vaccinated population has been increasing, the rising breakthrough infection persists in the vaccinated population. For living with the virus, the dietary guidelines to prevent virus infection are worthy of and timely to develop further. Tannic acid has been demonstrated to be an effective inhibitor of coronavirus and is under clinical trial. Here we found that two other members of the tannins family, oligomeric proanthocyanidins (OPCs) and punicalagin, are also potent inhibitors against SARS-CoV-2 infection with different mechanisms. OPCs and punicalagin showed inhibitory activity against omicron variants of SARS-CoV-2 infection. The water extractant of the grape seed was rich in OPCs and also exhibited the strongest inhibitory activities for viral entry of wild-type and other variants in vitro. Moreover, we evaluated the inhibitory activity of grape seed extractants (GSE) supplementation against SARS-CoV-2 viral entry in vivo and observed that serum samples from the healthy human subjects had suppressive activity against different variants of SARS-CoV-2 vpp infection after taking GSE capsules. Our results suggest that natural tannins acted as potent inhibitors against SARS-CoV-2 infection, and GSE supplementation could serve as healthy food for infection prevention. Highlights OPCs and Punicalagin had inhibitory activity against omicron variants of SARS-CoV-2 infection. OPCs serve as a dual inhibitor of the viral Mpro and the cellular TMPRSS2 protease. Punicalagin possesses the most potent activity to suppress the Mpro and block the interaction of the viral spike protein and human ACE2. OPCs-enriched grape seed extractant exhibited inhibitory activities for viral entry of wild-type and other variants of SARS-CoV-2. The daily intake of grape seed extractants may be able to prevent SARS-CoV-2 infection.

Poly(ADP-ribose) polymerase (PARP) inhibitors have demonstrated promising clinical activity in multiple cancers. However, resistance to PARP inhibitors remains a substantial clinical challenge. In the present study, we report that anaplastic lymphoma kinase (ALK) directly phosphorylates CDK9 at tyrosine-19 to promote homologous recombination (HR) repair and PARP inhibitor resistance. Phospho-CDK9-Tyr19 increases its kinase activity and nuclear localization to stabilize positive transcriptional elongation factor b and activate polymerase II-dependent transcription of HR-repair genes. Conversely, ALK inhibition increases ubiquitination and degradation of CDK9 by Skp2, an E3 ligase. Notably, combination of US Food and Drug Administration-approved ALK and PARP inhibitors markedly reduce tumor growth and improve survival of mice in PARP inhibitor-/platinum-resistant tumor xenograft models. Using human tumor biospecimens, we further demonstrate that phosphorylated ALK (p-ALK) expression is associated with resistance to PARP inhibitors and positively correlated with p-Tyr19-CDK9 expression. Together, our findings support a biomarker-driven, combinatorial treatment strategy involving ALK and PARP inhibitors to induce synthetic lethality in PARP inhibitor-/platinum-resistant tumors with high p-ALK–p-Tyr19-CDK9 expression.

Malignant brain tumors consist of malignancies originated primarily within the brain and the metastatic lesions disseminated from other organs. In spite of intensive studies, malignant brain tumors remain to be a medical challenge. Patient-derived organoid (PDO) can recapitulate the biological features of the primary tumor it was derived from and has emerged as a promising drug-screening model for precision therapy. Here we show a proof-of-concept based on early clinical study entailing the organoids derived from the surgically resected tumors of 26 patients with advanced malignant brain tumors enrolled during December 2020 to October 2021. The tumors included nine glioma patients, one malignant meningioma, one primary lymphoma patient, and 15 brain metastases. The primary tumor sites of the metastases included five from the lungs, three from the breasts, two from the ovaries, two from the colon, one from the testis, one of melanoma origin, and one of chondrosarcoma. Out of the 26 tissues, 13 (50%) organoids were successfully generated with a culture time of about 2 weeks. Among these patients, three were further pursued to have the organoids derived from their tumor tissues tested for the sensitivity to different therapeutic drugs in parallel to their clinical care. Our results showed that the therapeutic effects observed by the organoid models were consistent to the responses of these patients to their treatments. Our study suggests that PDO can recapitulate patient responses in the clinic with high potential of implementation in personalized medicine of malignant brain tumors.