Dutta, Shamit K.

Abstract Background Renal cell carcinoma (RCC) was historically considered to be less responsive to radiation therapy (RT) compared to other cancer indications. However, advancements in precision high-dose radiation delivery through single-fraction and multi-fraction stereotactic ablative radiotherapy (SABR) have led to better outcomes and reduced treatment-related toxicities, sparking renewed interest in using RT to treat RCC. Moreover, numerous studies have revealed that certain therapeutic agents including chemotherapies can increase the sensitivity of tumors to RT, leading to a growing interest in combining these treatments. Here, we developed a rational combination of two radiosensitizers in a tumor-targeted liposomal formulation for augmenting RT in RCC. The objective of this study is to assess the efficacy of a tumor-targeted liposomal formulation combining the mTOR inhibitor everolimus (E) with the survivin inhibitor YM155 (Y) in enhancing the sensitivity of RCC tumors to radiation. Experimental Design: We slightly modified our previously published tumor-targeted liposomal formulation to develop a rational combination of E and Y in a single liposomal formulation (EY-L) and assessed its efficacy in RCC cell lines in vitro and in RCC tumors in vivo. We further investigated how well EY-L sensitizes RCC cell lines and tumors toward radiation and explored the underlying mechanism of radiosensitization. Results EY-L outperformed the corresponding single drug-loaded formulations E-L and Y-L in terms of containing primary tumor growth and improving survival in an immunocompetent syngeneic mouse model of RCC. EY-L also exhibited significantly higher sensitization of RCC cells towards radiation in vitro than E-L and Y-L. Additionally, EY-L sensitized RCC tumors towards radiation therapy in xenograft and murine RCC models. EY-L mediated induction of mitotic catastrophe via downregulation of multiple cell cycle checkpoints and DNA damage repair pathways could be responsible for the augmentation of radiation therapy. Conclusion Taken together, our study demonstrated the efficacy of a strategic combination therapy in sensitizing RCC to radiation therapy via inhibition of DNA damage repair and a substantial increase in mitotic catastrophe. This combination therapy may find its use in the augmentation of radiation therapy during the treatment of RCC patients.

BACKGROUND: CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/clustered regularly interspaced short palindromic repeat-associated 9) technology-mediated genome editing has significantly improved the targeted inactivation of genes in vitro and in vivo in many organisms. Neuropilins play crucial roles in zebrafish heart regeneration, heart failure in mice, and electrical remodeling after myocardial infarction in rats. But the cell-specific functions of nrp1 have not been described before. In this study, we have investigated the role of nrp1 isoforms, including nrp1a and nrp1b , in cardiomyocytes during cardiac injury and regeneration in adult zebrafish hearts. METHODS: In this study, we have reported a novel CRISPR-based vector system for conditional tissue-specific gene ablation in zebrafish. Specifically, the cardiac-specific cmlc2 promoter drives Cas9 expression to silence the nrp1 gene in cardiomyocytes in a heat-shock inducible manner. This vector system establishes a unique tool to regulate the gene knockout in both the developmental and adult stages and hence widens the possibility of loss-of-function studies in zebrafish at different stages of development and adulthood. Using this approach, we investigated the role of neuropilin isoforms nrp1a and nrp1b in response to cardiac injury and regeneration in adult zebrafish hearts. RESULTS: We observed that both the isoforms ( nrp1a and nrp1b ) are upregulated after the cryoinjury. Interestingly, the nrp1b knockout significantly delayed heart regeneration and impaired cardiac function in the adult zebrafish after cryoinjury, demonstrated by reduced heart rate, ejection fractions, and fractional shortening. In addition, we show that the knockdown of nrp1b but not nrp1a induces activation of the cardiac remodeling genes in response to cryoinjury. CONCLUSIONS: To our knowledge, this study is novel where we have reported a heat-shock–mediated conditional knockdown of nrp1a and nrp1b isoforms using CRISPR/Cas9 technology in the cardiomyocyte in zebrafish and furthermore have identified a crucial role for the nrp1b isoform in zebrafish cardiac remodeling and eventually heart function in response to injury.

Abstract Purpose: Although renal cell carcinoma (RCC) is relatively more resistant to radiation therapy (RT) compared to other cancer indications, recent advances in single-fraction and multi-fraction stereotactic ablative radiotherapy (SABR) made it possible to achieve better outcome and reduce treatment related toxicities. In addition, with studies demonstrating that certain therapeutic agents including chemotherapies can act as radiosensitizers, the idea of combining radiotherapy with those agents are being actively pursued. Among them, mammalian target of rapamycin (mTOR) inhibitor everolimus (E) and survivin inhibitor YM155 (Y) are of special interest since they target multiple RT-resistance mechanisms simultaneously. Additionally, YM155 has been shown to help in overcoming resistance to mTOR inhibitors in various cancer including RCC. Hence, the present study aims to evaluate the efficacy of a tumor-targeted liposomal formulation combining everolimus and YM155 (EY-L) in sensitizing RCC tumors towards radiation. Experimental Design: Previously we developed a tumor-targeted liposomal formulation and used it successfully to deliver multiple drugs for the treatment of RCC in both immune-deficient and immune-competent mouse models. Here we developed a similar formulation combining everolimus and YM155 (EY-L) and assessed its efficacy in RCC cell lines in vitro and in RCC tumors in vivo. We further evaluated the efficacy of EY-L in sensitizing RCC cell lines and tumors towards radiation in vitro using clonogenic assay and in vivo in RCC xenografts in immunodeficient mice and murine RCC models in immunocompetent mice. Results: EY-L (2 mg/kg E, 1.4 mg/kg Y, twice a week intravenous administration) was better than E-L or Y-L, the corresponding single drug loaded formulations in containing the primary tumor growth and improving survival in an immunocompetent syngeneic mouse model of RCC. Furthermore, EY-L leads to significantly higher sensitization of RCC cells towards radiation in vitro than E-L or Y-L. Finally, EY-L was able to sensitize RCC tumors towards radiation therapy in both RCC xenograft and murine RCC model. Conclusion: Taken together, our study demonstrated the efficacy of a strategic combination therapy in sensitizing RCC to radiation therapy using in vitro clonogenic assay and in vivo radiosensitization studies in multiple RCC tumor models. Citation Format: Krishnendu Pal, Vijay S. Madamsetty, Hari K. Rachamala, Shamit K. Dutta, Enfeng Wang, Debabrata Mukhopadhyay. Combined inhibition of mammalian target of rapamycin (mTOR) and survivin augments radiation therapy in renal cell carcinoma [abstract]. In: Proceedings of the AACR Special Conference: Advances in Kidney Cancer Research; 2023 Jun 24-27; Austin, Texas. Philadelphia (PA): AACR; Cancer Res 2023;83(16 Suppl):Abstract nr B026.

Abstract Purpose: Pancreatic ductal adenocarcinoma (PDAC) is a predominantly fatal common malignancy with inadequate treatment options. Glycogen synthase kinase 3β (GSK-3β) is an emerging target in human malignancies including PDAC. Experimental Design: Pancreatic cancer cell lines and patient-derived xenografts were treated with a novel GSK-3 inhibitor 9-ING-41 alone or in combination with chemotherapy. Activation of the DNA damage response pathway and S-phase arrest induced by gemcitabine were assessed in pancreatic tumor cells with pharmacologic inhibition or siRNA depletion of GSK-3 kinases by immunoblotting, flow cytometry, and immunofluorescence. Results: 9-ING-41 treatment significantly increased pancreatic tumor cell killing when combined with chemotherapy. Inhibition of GSK-3 by 9-ING-41 prevented gemcitabine-induced S-phase arrest suggesting an impact on the ATR-mediated DNA damage response. Both 9-ING-41 and siRNA depletion of GSK-3 kinases impaired the activation of ATR leading to the phosphorylation and activation of Chk1. Mechanistically, depletion or knockdown of GSK-3 kinases resulted in the degradation of the ATR-interacting protein TopBP1, thus limiting the activation of ATR in response to single-strand DNA damage. Conclusions: These data identify a previously unknown role for GSK-3 kinases in the regulation of the TopBP1/ATR/Chk1 DNA damage response pathway. The data also support the inclusion of patients with PDAC in clinical studies of 9-ING-41 alone and in combination with gemcitabine.

PLEXIND1 is upregulated in several cancers, including pancreatic ductal adenocarcinoma (PDAC). It is an established mediator of semaphorin signaling, and neuropilins are its known coreceptors. Herein, we report data to support the proposal that PLEXIND1 acts as a transforming growth factor beta (TGFβ) coreceptor, modulating cell growth through SMAD3 signaling. Our findings demonstrate that PLEXIND1 plays a pro-tumorigenic role in PDAC cells with oncogenic KRAS (KRASmut). We show in KRASmut PDAC cell lines (PANC-1, AsPC-1,4535) PLEXIND1 downregulation results in decreased cell viability (in vitro) and reduced tumor growth (in vivo). Conversely, PLEXIND1 acts as a tumor suppressor in the PDAC cell line (BxPC-3) with wild-type KRAS (KRASwt), as its reduced expression results in higher cell viability (in-vitro) and tumor growth (in vivo). Additionally, we demonstrate that PLEXIND1-mediated interactions can be selectively disrupted using a peptide based on its C-terminal sequence (a PDZ domain-binding motif), an outcome that may possess significant therapeutic implications. To our knowledge, this is the first report showing that (1) PLEXIND1 acts as a TGFβ coreceptor and mediates SMAD3 signaling, and (2) differential roles of PLEXIND1 in PDAC cell lines correlate with KRASmut and KRASwt status.

Vascular permeability factor/vascular endothelial growth factor A (VEGF) is a central regulator of angiogenesis and potently promotes vascular permeability. VEGF plays a key role in the pathologies of heart disease, stroke, and cancer. Therefore, understanding the molecular regulation of VEGF signaling is an important pursuit. Rho GTPase proteins play various roles in vasculogenesis and angiogenesis. While the functions of RhoA and RhoB in these processes have been well defined, little is known about the role of RhoC in VEGF-mediated signaling in endothelial cells and vascular development. Here, we describe how RhoC modulates VEGF signaling to regulate endothelial cell proliferation, migration and permeability. We found VEGF stimulation activates RhoC in human umbilical vein endothelial cells (HUVECs), which was completely blocked after VEGF receptor 2 (VEGFR-2) knockdown indicating that VEGF activates RhoC through VEGFR-2 signaling. Interestingly, RhoC knockdown delayed the degradation of VEGFR-2 compared to control siRNA treated HUVECs, thus implicating RhoC in VEGFR-2 trafficking. In light of our results suggesting VEGF activates RhoC through VEGFR-2, we sought to determine whether RhoC regulates vascular permeability through the VEGFR-2/phospholipase Cγ (PLCγ) /Ca 2+ /eNOS cascade. We found RhoC knockdown in VEGF-stimulated HUVECs significantly increased PLC-γ1 phosphorylation at tyrosine 783, promoted basal and VEGF-stimulated eNOS phophorylation at serine 1177, and increased calcium flux compared with control siRNA transfected HUVECs. Taken together, our findings suggest RhoC negatively regulates VEGF-induced vascular permeability. We confirmed this finding through a VEGF-inducible zebrafish model of vascular permeability by observing significantly greater vascular permeability in RhoC morpholino (MO)-injected zebrafish than control MO-injected zebrafish. Furthermore, we showed that RhoC promotes endothelial cell proliferation and negatively regulates endothelial cell migration. Our data suggests a scenario in which RhoC promotes proliferation by upregulating -catenin in a Wnt signaling-independent manner, which in turn, promotes Cyclin D1 expression and subsequently drives cell cycle progression.

Vascular endothelial growth factor A (VEGF) signals primarily through its cognate receptor VEGFR-2 to control vasculogenesis and angiogenesis. Dysregulation of these physiological processes contributes to the pathologies of heart disease, stroke, and cancer. Protein kinase D (PKD) plays a crucial role in the regulation of angiogenesis by modulating endothelial cell proliferation and migration. In human umbilical vein endothelial cells (HUVEC) and human blood outgrowth endothelial cells (BOEC), knockdown of PKD-1 or PKD-2 downregulates VEGFR-2 and significantly inhibits VEGF-induced endothelial cell proliferation and migration. We sought to determine the molecular mechanism through which PKD modulates VEGFR-2 expression. Based on bioinformatics data, activating enhancer binding protein 2 (AP2) binding sites exist within the VEGFR-2 promoter. Thus, we hypothesized PKD may downregulate VEGFR-2 through AP2-mediated transcriptional repression of the VEGFR-2 promoter. Indeed, AP2β binds the VEGFR-2 promoter upon PKD knockdown in HUVEC as evident by chromatin immunoprecipitation assay. Luciferase reporter assays using serial deletions of AP2β binding sites within the VEGFR-2 promoter revealed transcriptional activity negatively correlated with the number of AP2β binding sites, thus confirming negative regulation of VEGFR-2 transcription by AP2β. Next, using siRNA, we demonstrated that upregulation of AP2β decreased VEGFR-2 expression and loss of AP2β enhanced VEGFR-2 expression. In vivo studies confirmed this finding as we observed increased VEGFR-2 immunostaining in the dorsal horn of the spinal cord of embryonic day 13 AP2β knockout mice. We hypothesize that PKD directly regulates AP2β function by serine phosphorylation and ongoing studies are being conducted to determine phosphorylation sites in AP2β directly regulated by PKD. Taken together, we demonstrate AP2β negatively regulates VEGFR-2 transcription and VEGFR-2 is a major downstream target of PKD. Our findings describing how PKD regulates angiogenesis may contribute to the development of therapies to improve the clinical outcome of patients afflicted by heart disease, stroke, and cancer.

Despite recent advancements, effective treatment for pancreatic ductal adenocarcinoma (PDAC) has remained elusive. The overall survival rate in PDAC patients has been dismally low due to resistance to standard therapies. In fact, the failure of monotherapies to provide long-term survival benefits in patients led to ascension of several combination therapies for PDAC treatment. However, these combination therapies provided modest survival improvements while increasing treatment-related adverse side effects. Hence, recent developments in drug delivery methods hold the potential for enhancing therapeutic benefits by offering cocktail drug loading and minimizing chemotherapy-associated side effects. Nanoformulations-aided deliveries of anticancer agents have been a success in recent years. Yet, improving the tumor-targeted delivery of drugs to PDAC remains a major hurdle. In the present paper, we developed several new tumor-targeted dual intervention-oriented drug-encapsulated (DIODE) liposomes. We successfully formulated liposomes loaded with gemcitabine (G), paclitaxel (P), erlotinib (E), XL-184 (c-Met inhibitor, X), and their combinations (GP, GE, and GX) and evaluated their in vitro and in vivo efficacies. Our novel DIODE liposomal formulations improved median survival in comparison with gemcitabine-loaded liposomes or vehicle. Our findings are suggestive of the importance of the targeted delivery for combination therapies in improving pancreatic cancer treatment.

Schematic representation demonstrating the fabrication and in vivo evaluation of an immune-modulatory nano-formulation consisting of irinotecan and curcumin in immune-competent mouse models of pancreatic adenocarcinoma.