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Photoimmunotherapy (PIT), carried out using an Ab conjugated to the near infrared dye IRDye700DX, is achieving significant success in target-specific elimination of cells. Fibroblast activation protein alpha (FAP-α) is an important target in cancer because of its expression by cancer-associated fibroblasts (CAFs) as well as by some cancer cells. Cancer-associated fibroblasts that express FAP-α have protumorigenic and immune suppressive functions. Using immunohistochemistry of human breast cancer tissue microarrays, we identified an increase of FAP-α

Supplementary Movie S1 from Image-Guided Enzyme/Prodrug Cancer Therapy

Supplementary methods and figures S1-S8. (S1): Glutamine dependency and induction of apoptosis on glutamine withdrawal in breast cancer cells. (S2): Cytotoxicity of AOA in breast cancer cells. (S3): Myc regulation of transaminases and glutamine dependency in mouse tumor cell lines. (S4): NMR spectra of AOA-treated compared to vehicle-treated SUM159 cells. (S5): Cell cycle arrest and BrdU incorporation after AOA treatment in SUM149 cells; irreversible growth arrest by AOA in SUM149 and 159 cells; partial rescue of cell death due to glutamine withdrawal by exogenous aspartate in breast cancer cell lines. (S6): Western blot analysis showing change in ER stress markers, energy metabolism and apoptosis by AOA treatment in SUM149, SUM159 and MDA-MB-231 cells. (S7): Tumor growth inhibition by AOA in MCF-7, SUM149 and SUM159 xenografts; immunohistochemistry analysis of cleaved caspase 3 in AOA treated tumors; quantitation of ER stress markers in AOA treated tumors. (S8): Effect of AOA in combination with paclitaxel or carboplatin in SUM149 and SUM159 xenografts; up regulation of c-myc in carboplatin and paclitaxel treated MDA-MB-231 xenografts.

Supplemental Figure S1. Real time optical imaging after 4 weeks of To3B graft growth in the hind leg muscle of a nude mouse indicating that a tdT fluorescent signal was observed only after i.p. administration of 100 μg of DEX 24 hr prior to imaging the live animal.

Supplemental Figure S3. Induction of tdT fluorescence occurred at an early time during tumor growth and was dependent on the tumor type in the s.c. model of pancreatic cancer.

Purpose: Glutamine addiction in c-MYC–overexpressing breast cancer is targeted by the aminotransferase inhibitor, aminooxyacetate (AOA). However, the mechanism of ensuing cell death remains unresolved.Experimental Design: A correlation between glutamine dependence for growth and c-MYC expression was studied in breast cancer cell lines. The cytotoxic effects of AOA, its correlation with high c-MYC expression, and effects on enzymes in the glutaminolytic pathway were investigated. AOA-induced cell death was assessed by measuring changes in metabolite levels by magnetic resonance spectroscopy (MRS), the effects of amino acid depletion on nucleotide synthesis by cell-cycle and bromodeoxyuridine (BrdUrd) uptake analysis, and activation of the endoplasmic reticulum (ER) stress–mediated pathway. Antitumor effects of AOA with or without common chemotherapies were determined in breast cancer xenografts in immunodeficient mice and in a transgenic MMTV-rTtA-TetO-myc mouse mammary tumor model.Results: We established a direct correlation between c-MYC overexpression, suppression of glutaminolysis, and AOA sensitivity in most breast cancer cells. MRS, cell-cycle analysis, and BrdUrd uptake measurements indicated depletion of aspartic acid and alanine leading to cell-cycle arrest at S-phase by AOA. Activation of components of the ER stress–mediated pathway, initiated through GRP78, led to apoptotic cell death. AOA inhibited growth of SUM159, SUM149, and MCF-7 xenografts and c-myc–overexpressing transgenic mouse mammary tumors. In MDA-MB-231, AOA was effective only in combination with chemotherapy.Conclusions: AOA mediates its cytotoxic effects largely through the stress response pathway. The preclinical data of AOA's effectiveness provide a strong rationale for further clinical development, particularly for c-MYC–overexpressing breast cancers. Clin Cancer Res; 21(14); 3263–73. ©2015 AACR.

Supplementary Data from Image-Guided Enzyme/Prodrug Cancer Therapy

The dire effects of cancer-induced cachexia undermine treatment and contribute to decreased survival rates. Therapeutic options for this syndrome are limited, and therefore efforts to identify signs of precachexia in cancer patients are necessary for early intervention. The applications of molecular and functional imaging that would enable a whole-body “holistic” approach to this problem may lead to new insights and advances for diagnosis and treatment of this syndrome. Here we have developed a myoblast optical reporter system with the purpose of identifying early cachectic events. We generated a myoblast cell line expressing a dual tdTomato:GFP construct that was grafted onto the muscle of mice-bearing human pancreatic cancer xenografts to provide noninvasive live imaging of events associated with cancer-induced cachexia (i.e., weight loss). Real-time optical imaging detected a strong tdTomato fluorescent signal from skeletal muscle grafts in mice with weight losses of only 1.2% to 2.7% and tumor burdens of only approximately 79 to 170 mm3. Weight loss in cachectic animals was also associated with a depletion of lipid, cholesterol, valine, and alanine levels, which may provide informative biomarkers of cachexia. Taken together, our findings demonstrate the utility of a reporter system that is capable of tracking tumor-induced weight loss, an early marker of cachexia. Future studies incorporating resected tissue from human pancreatic ductal adenocarcinoma into a reporter-carrying mouse may be able to provide a risk assessment of cachexia, with possible implications for therapeutic development. Cancer Res; 76(6); 1441–50. ©2015 AACR.

Supplementary Movie Legend from Molecular Imaging of CXCR4 Receptor Expression in Human Cancer Xenografts with [64Cu]AMD3100 Positron Emission Tomography

PDF file - 48K, POX mRNA increases in MDA-MB-231 HRE-EGFP breast cancer cells exposed to hypoxia

Supplementary Methods, Figures 1-3 from Molecular Imaging of CXCR4 Receptor Expression in Human Cancer Xenografts with [64Cu]AMD3100 Positron Emission Tomography

PDF file - 205K, Hypoxia-induced POX expression is independent of HIF-1alpha and HIF-2alpha

PDF file - 77K, Western blot confirms the knockdown of POX by siRNA in HT29 cells

PDF file - 282K, Upregulation of POX does not induce apoptosis under hypoxia

Supplementary Movie 1 from Molecular Imaging of CXCR4 Receptor Expression in Human Cancer Xenografts with [64Cu]AMD3100 Positron Emission Tomography

PDF file - 191K, Hypoxia upregulates POX expression in TK10 and Hs-578-T cell lines through AMPK activation

PDF file - 124K

The chemokine receptor CXCR4 and its cognate ligand CXCL12 are pivotal for establishing metastases from many tumor types. Thus, CXCR4 may offer a cell surface target for molecular imaging of metastases, assisting diagnosis, staging, and therapeutic monitoring. Furthermore, noninvasive detection of CXCR4 status of a primary tumor may provide an index of the metastatic potential of the lesion. Here, we report the development and evaluation of [64Cu]AMD3100, a positron-emitting analogue of the stem cell mobilizing agent plerixafor to image CXCR4 in human tumor xenografts preselected for graded expression of this receptor. This imaging method was evaluated in lung metastases derived from human MDA-MB-231 breast cancer cells. Ex vivo biodistribution studies, performed to validate the in vivo imaging data, confirmed the ability of [64Cu]AMD3100 to image CXCR4 expression. Our findings show the feasibility of imaging CXCR4 by positron emission tomography using a clinically approved agent as a molecular scaffold. Cancer Res; 70(10); 3935–44. ©2010 AACR.

Fibroblast activation protein-α (FAP-α) is a transmembrane serine protease that is attracting significant interest as it is expressed by a subgroup of cancer-associated fibroblasts that play a role in immune suppression and cancer metastasis. FAP-α is also expressed by some cancer cells, such as melanoma, colorectal and breast cancer cells. Triple negative breast cancer (TNBC) is an aggressive cancer that urgently requires identification of novel targets for therapy. To expand our understanding of the functional roles of FAP-α in TNBC we engineered a human TNBC cell line, MDA-MB-231, to stably overexpress FAP-α and characterized changes in metabolism by 1H magnetic resonance spectroscopy, cell proliferation, migration characterized by wound healing, and invasion. FAP-α overexpression resulted in significant alterations in myoinositol, choline metabolites, creatine, and taurine, as well as a significant increase of migration and invasion, although proliferation remained unaltered. The increase of migration and invasion are consistent with the known activities of FAP-α as an exopeptidase and endopeptidase/gelatinase/collagenase in tissue remodeling and repair, and in cell migration. We additionally determined the effects of FAP-α overexpression on the human fibrosarcoma HT1080 cell line that showed increased migration, accompanied by limited changes in metabolism that identified the dependency of the metabolic changes on cell type. These metabolic data identify a previously unknown role of FAP-α in modifying cancer cell metabolism in the TNBC cell line studied here that may provide new insights into its functional roles in cancer progression.

Alpha-particle radiotherapy has already been shown to be impervious to most resistance mechanisms. However, in established (i.e. large, vascularized) soft-tissue lesions, the diffusion-limited penetration depths of radiolabeled antibodies and/or nanocarriers (up to 50-80µm) combined with the short range of α-particles (4-5 cell diameters) may result in only partial tumor irradiation potentially limiting treatment efficacy. To address this challenge, we combined carriers with complementary intratumoral microdistributions of the delivered α-particles. We use the α-particle generator Actinium-225 (225Ac), and we combine (1) a tumor-responsive liposome that upon tumor uptake releases in the interstitium a highly-diffusing form of its radioactive payload (225Ac-DOTA), which may penetrate the deeper parts of tumors where antibodies do not reach, with (2) a separately administered, less-penetrating radiolabeled-antibody irradiating the tumor perivascular regions from where liposome contents clear too fast. Methods: On a murine model with orthotopic HER2-positive BT474 breast cancer xenografts, the biodistributions of each carrier were evaluated, and the control of tumor growth was monitored after administration of the same total radioactivity of 225Ac delivered (1) by the 225Ac-DOTA-encapsulating liposomes, (2) by the 225Ac-DOTA-SCN-labeled-trastuzumab, and (3) by both carriers at equally split radioactivities. Results: Tumor growth inhibition was significantly more pronounced when the same total injected radioactivity was divided between the two separate carriers, as compared to the growth delay by the same total injected radioactivity when delivered by either of the carriers alone. The combined carriers enabled more uniform intratumoral microdistributions of α-particles, at a tumor delivered dose that was lower than the dose delivered by the antibody alone. Significance: This strategy demonstrates that more uniform microdistributions of the delivered α-particles within established solid tumors improve efficacy even at lower tumor delivered doses. Augmentation of antibody-targeted α-particle therapies with tumor-responsive liposomes may address partial tumor irradiation improving therapeutic effects.

Biguanide drugs (metformin and phenformin) have drawn interest for potential cancer treatments, and laboratory studies show that some cancer cells are selectively sensitive to growth-inhibitory effects of biguanides. Examining metabolic pathways affected by biguanide treatments in cancer cells that are highly sensitive to biguanides, we found that biguanide treatment depletes cellular levels of both aspartate and NAD+. Experiments to replenish these metabolites or block steps of the aspartate-malate shuttle suggest that depletion of both metabolites, rather than either aspartate of NAD+ individually, is critical for growth-inhibitory effects of biguanide exposure. Even in sensitive cancer cells, though, biguanide treatment alone over a broad range of doses only inhibits cell replication without significantly affecting cell viability. Noting that clinical observations of biguanide efficacy have used combinations of agents that typically include cisplatin, we found that biguanide treatment at a cytostatic level substantially decreases survival of lung cancer and breast cancer cells when co-treated with cisplatin at doses that alone are also non-cytotoxic. This striking enhancement of cisplatin toxicity by biguanides depends on reductions of levels of NAD+ and aspartate, since addition of either of these metabolites prevented this potentiation of cisplatin cytotoxicity. Thus, biguanide drugs can have cytotoxic effects when used in combination with other cancer drugs, such as cisplatin, and depleting cellular levels of NAD+ and aspartate is critical for enhancing the cytotoxicity of cisplatin by biguanide drugs in sensitive cancer cells.

Small interfering RNA (siRNA) is ideal for gene silencing through a sequence-specific RNA interference process. The redundancy and complexity of molecular pathways in cancer create a need for multiplexed targeting that can be achieved with multiplexed siRNA delivery. Here, we delivered multiplexed siRNA with a PSMA-targeted biocompatible dextran nanocarrier to downregulate CD46 and PD-L1 in PSMA expressing prostate cancer cells. The selected gene targets, PD-L1 and CD46, play important roles in the escape of cancer cells from immune surveillance. PSMA, abundantly expressed by prostate cancer cells, allowed the prostate cancer-specific delivery of the nanocarrier. The nanocarrier was modified with acid cleavable acetal bonds for a rapid release of siRNA. Cell imaging and flow cytometry studies confirmed the PSMA-specific delivery of CD46 and PD-L1 siRNA to high PSMA expressing PC-3 PIP cells. Immunoblot, qRT-PCR and flow cytometry methods confirmed the downregulation of CD46 and PD-L1 following treatment with multiplexed siRNA.

BackgroundDistinguishing between some benign lipomas (BLs), atypical lipomatous tumors (ALTs), and dedifferentiated liposarcomas (DDLs) can be challenging due to overlapping magnetic resonance imaging characteristics, and poorly understood molecular mechanisms underlying the malignant transformation of liposarcomas.PurposeTo identify metabolic biomarkers of the lipomatous tumor spectrum by examining human tissue specimens using high-resolution 1H magnetic resonance spectroscopy (MRS).Materials and methodsIn this prospective study, human tissue specimens were obtained from participants who underwent surgical resection for radiologically-indeterminate lipomatous tumors between November 2016 and May 2019. Tissue specimens were obtained from normal subcutaneous fat (n=9), BLs (n=10), ALTs (n=7) and DDLs (n=8). Extracts from specimens were examined with high-resolution MRS at 17.6T. Computational modeling of pattern recognition-based cluster analysis was utilized to identify significant differences in metabolic signatures between the lipomatous tumor types.ResultsSignificant differences between BLs and ALTs were observed for multiple metabolites, including leucine, valine, branched chain amino acids, alanine, acetate, glutamine, and formate. DDLs were distinguished from ALTs by increased glucose and lactate, and increased phosphatidylcholine. Multivariate principal component analysis showed clear clustering identifying distinct metabolic signatures of the tissue types.ConclusionMetabolic signatures identified in 1H MR spectra of lipomatous tumors provide new insights into malignant progression and metabolic targeting. The metabolic patterns identified provide the foundation of developing noninvasive MRS or PET imaging biomarkers to distinguish between BLs, ALTs, and DDLs.

(1) Background: MDSCs play an active role in the immune surveillance escape of cancer cells. Because MDSCs in mice are CD11b+Gr1+, near-infrared photoimmunotherapy (NIR-PIT) using the NIR dye IR700 conjugated to an MDSC-binding antibody provides an opportunity for targeted elimination of MDSCs. (2) Methods: The efficacy of Gr1-IR700-mediated NIR-PIT was evaluated in vitro using magnetically separated CD11b+Gr1+ MDSCs from spleens of 4T1-luc tumor-bearing (TB) mice. For in vivo evaluation, spleens of Gr1-IR700-injected 4T1-luc TB mice were irradiated with NIR light, and splenocyte viability was determined using CCK-8 assays. Metabolic profiling of NIR-PIT-irradiated spleens was performed using 1H MRS. (3) Results: Flow cytometric analysis confirmed a ten-fold increase in splenic MDSCs in 4T1-luc TB mice. Gr1-IR700-mediated NIR-PIT eliminated tumor-induced splenic MDSCs in culture. Ex vivo fluorescence imaging revealed an 8- and 9-fold increase in mean fluorescence intensity (MFI) in the spleen and lungs of Gr1-IR700-injected compared to IgG-IR700-injected TB mice. Splenocytes from Gr1-IR700-injected TB mice exposed in vivo to NIR-PIT demonstrated significantly lower viability compared to no light exposure or untreated control groups. Significant metabolic changes were observed in spleens following NIR-PIT. (4) Conclusions: Our data confirm the ability of NIR-PIT to eliminate splenic MDSCs, identifying its potential to eliminate MDSCs in tumors to reduce immune suppression. The metabolic changes observed may identify potential biomarkers of splenic MDSC depletion as well as potential metabolic targets of MDSCs.

Highly cytotoxic α-particle radiotherapy delivered by tumor-selective nanocarriers is evaluated on metastatic Triple Negative Breast Cancer (TNBC). On vascularized tumors, the limited penetration of nanocarriers (

Levodopa (L-DOPA), a precursor of dopamine, is commonly prescribed for the treatment of the Parkinson’s disease (PD). However, oral administration of levodopa results in a high level of homocysteine in the peripheral circulation, thereby elevating the risk of cardiovascular disease, and limiting its clinical application. Here, we report a non-invasive method to deliver levodopa to the brain by delivering L-DOPA-loaded sub-50 nm nanoparticles via brain-lymphatic vasculature. The hydrophilic L-DOPA was successfully encapsulated into nanoparticles of tannic acid (TA)/polyvinyl alcohol (PVA) via hydrogen bonding using the flash nanocomplexation (FNC) process, resulting in a high L-DOPA-loading capacity and uniform size in a scalable manner. Pharmacodynamics analysis in a PD rat model demonstrated that the levels of dopamine and tyrosine hydroxylase, which indicate the dopaminergic neuron functions, were increased by 2- and 4-fold, respectively. Movement disorders and cerebral oxidative stress of the rats were significantly improved. This formulation exhibited a high degree of biocompatibility as evidenced by lack of induced inflammation or other pathological changes in major organs. This antioxidative and drug-delivery platform administered through the brain-lymphatic vasculature shows promise for clinical treatment of the PD.

Distinguishing between some benign lipomas (BLs), atypical lipomatous tumors (ALTs), and dedifferentiated liposarcomas (DDLs) can be challenging due to overlapping magnetic resonance imaging characteristics, and poorly understood molecular mechanisms underlying the malignant transformation of liposarcomas.To identify metabolic biomarkers of the lipomatous tumor spectrum by examining human tissue specimens using high-resolutionIn this prospective study, human tissue specimens were obtained from participants who underwent surgical resection for radiologically-indeterminate lipomatous tumors between November 2016 and May 2019. Tissue specimens were obtained from normal subcutaneous fat (n=9), BLs (n=10), ALTs (n=7) and DDLs (n=8). Extracts from specimens were examined with high-resolution MRS at 17.6T. Computational modeling of pattern recognition-based cluster analysis was utilized to identify significant differences in metabolic signatures between the lipomatous tumor types.Significant differences between BLs and ALTs were observed for multiple metabolites, including leucine, valine, branched chain amino acids, alanine, acetate, glutamine, and formate. DDLs were distinguished from ALTs by increased glucose and lactate, and increased phosphatidylcholine. Multivariate principal component analysis showed clear clustering identifying distinct metabolic signatures of the tissue types.Metabolic signatures identified in

Highlights • Developed a hypoxia theranostic imaging strategy to eliminate hypoxic cells. • Hypoxic cell elimination resulted in fewer cancer associated fibroblasts (CAFs) • Collagen 1 fiber patterns were altered with hypoxic cell elimination. • cDNA nanoparticles with HRE driven prodrug enzyme expression can target hypoxia., Hypoxia is frequently observed in human prostate cancer, and is associated with chemoresistance, radioresistance, metastasis, and castrate-resistance. Our purpose in these studies was to perform hypoxia theranostics by combining in vivo hypoxia imaging and hypoxic cancer cell targeting in a human prostate cancer xenograft. This was achieved by engineering PC3 human prostate cancer cells to express luciferase as well as a prodrug enzyme, yeast cytosine deaminase, under control of hypoxic response elements (HREs). Cancer cells display an adaptive response to hypoxia through the activation of several genes mediated by the binding of hypoxia inducible factors (HIFs) to HRE in the promoter region of target gene that results in their increased transcription. HIFs promote key steps in tumorigenesis, including angiogenesis, metabolism, proliferation, metastasis, and differentiation. HRE-driven luciferase expression allowed us to detect hypoxia in vivo to time the administration of the nontoxic prodrug 5-fluorocytosine that was converted by yeast cytosine deaminase, expressed under HRE regulation, to the chemotherapy agent 5-fluorouracil to target hypoxic cells. Conversion of 5-fluorocytosine to 5-fluorouracil was detected in vivo by 19F magnetic resonance spectroscopy. Morphological and immunohistochemical staining and molecular analyses were performed to characterize tumor microenvironment changes in cancer-associated fibroblasts, cell viability, collagen 1 fiber patterns, and HIF-1α. These studies expand our understanding of the effects of eliminating hypoxic cancer cells on the tumor microenvironment and in reducing stromal cell populations such as cancer-associated fibroblasts.

Background Cachexia is a major cause of morbidity in pancreatic ductal adenocarcinoma (PDAC) patients. Our purpose was to understand the impact of PDAC‐induced cachexia on brain metabolism in PDAC xenograft studies, to gain new insights into the causes of cachexia‐induced morbidity. Changes in mouse and human plasma metabolites were characterized to identify underlying causes of brain metabolic changes. Methods We quantified metabolites, detected with high‐resolution 1H magnetic resonance spectroscopy, in the brain and plasma of normal mice (n = 10) and mice bearing cachexia (n = 10) or non‐cachexia (n = 9) inducing PDAC xenografts as well as in human plasma obtained from normal individuals (n = 24) and from individuals with benign pancreatic disease (n = 20) and PDAC (n = 20). Statistical significance was defined as a P value ≤0.05. Results The brain metabolic signature of cachexia‐inducing PDAC was characterized by a significant depletion of choline of −27% and −21% as well as increases of glutamine of 13% and 9% and formate of 21% and 14%, relative to normal controls and non‐cachectic tumour‐bearing mice, respectively. Good to moderate correlations with percent weight change were found for choline (r = 0.70), glutamine (r = −0.58), and formate (r = −0.43). Significant choline depletion of −38% and −30%, relative to normal controls and non‐cachectic tumour‐bearing mice, respectively, detected in the plasma of cachectic mice likely contributed to decreased brain choline in cachectic mice. Similarly, relative to normal controls and patients with benign disease, choline levels in human plasma samples of PDAC patients were significantly lower by −12% and −20% respectively. A comparison of plasma metabolites from PDAC patients with and without weight loss identified significant changes in glutamine metabolism. Conclusions Disturbances in metabolites of the choline/cholinergic and glutamine/glutamate/glutamatergic neurotransmitter pathways may contribute to morbidity. Metabolic normalization may provide strategies to reduce morbidity. The human plasma metabolite changes observed may lead to the development of companion diagnostic markers to detect PDAC and PDAC‐induced cachexia.

Twist (TWIST1) is a gene required for cell fate specification in embryos and its expression in mammary epithelium can initiate tumorigenesis through the epithelial-mesenchymal transition. To identify downstream target genes of Twist in breast cancer, we performed microarray analysis on the transgenic breast cancer cell line, MCF-7/Twist. One of the targets identified was choline kinase whose upregulation resulted in increased cellular phosphocholine and total choline containing compounds-a characteristic observed in highly aggressive metastatic cancers. To study the interactions between Twist, choline kinase, and their effect on the microenvironment, we used

Multinuclear ex vivo magnetic resonance spectroscopy (MRS) of cancer cells, xenografts, human cancer tissue, and biofluids is a rapidly expanding field that is providing unique insights into cancer. Starting from the 1970s, the field has continued to evolve as a stand-alone technology or as a complement to in vivo MRS to characterize the metabolome of cancer cells, cancer-associated stromal cells, immune cells, tumors, biofluids and, more recently, changes in the metabolome of organs induced by cancers. Here, we review some of the insights into cancer obtained with ex vivo MRS and provide a perspective of future directions. Ex vivo MRS of cells and tumors provides opportunities to understand the role of metabolism in cancer immune surveillance and immunotherapy. With advances in computational capabilities, the integration of artificial intelligence to identify differences in multinuclear spectral patterns, especially in easily accessible biofluids, is providing exciting advances in detection and monitoring response to treatment. Metabolotheranostics to target cancers and to normalize metabolic changes in organs induced by cancers to prevent cancer-induced morbidity are other areas of future development.

Photoimmunotherapy (PIT) using an antibody conjugated to a near infrared dye IR700 is achieving significant success in target-specific elimination of cells. Fibroblast activation protein alpha (FAP-α) is an important target in cancer because of its expression by cancer associated fibroblasts (CAFs) as well as by some cancer cells. CAFs that express FAP-α have protumorigenic and immune suppressive functions. Using immunohistochemistry of human breast cancer tissue microarrays, we identified an increase of FAP-α+ CAFs in invasive breast cancer tissue compared to adjacent normal tissue. We found FAP-α expression increased in fibroblasts co-cultured with cancer cells. In proof-of-principle studies, we engineered human FAP-α overexpressing MDA-MB-231 and HT-1080 cancer cells and murine FAP-α overexpressing NIH-3T3 fibroblasts to evaluate several anti-FAP-α antibodies and selected AF3715 based on its high binding-affinity with both human and mouse FAP-α. After conjugation of AF3715 with the phthalocyanine dye IR700, the resultant antibody conjugate, FAP-α-IR700, was evaluated in cells and tumors for its specificity and effectiveness in eliminating FAP-α expressing cell populations with PIT. FAP-α-IR700-PIT resulted in effective FAP-α-specific cell killing in the engineered cancer cells and in two patient-derived CAFs in a dose-dependent manner. Following an intravenous injection, FAP-α-IR700 retention was three-fold higher than IgG-IR700 in FAP-α overexpressing tumors, and two-fold higher compared to wild-type tumors. FAP-α-IR700-PIT resulted in significant growth inhibition of tumors derived from FAP-α overexpressing human cancer cells. A reduction of endogenous FAP-α+ murine CAFs was identified at 7 days after FAP-α-IR700-PIT. FAP-α-targeted NIR-PIT presents a promising strategy to eliminate FAP-α+ CAFs.

Partial and/or heterogeneous irradiation of established (i.e., large, vascularized) tumors by α-particles that exhibit only a 4-5 cell-diameter range in tissue, limits the therapeutic effect, since regions not being hit by the high energy α-particles are likely not to be killed. This study aims to mechanistically understand a delivery strategy to uniformly distribute α-particles within established solid tumors by simultaneously delivering the same α-particle emitter by two diverse carriers, each killing a different region of the tumor: (1) the cancer-agnostic, but also tumor-responsive, liposomes engineered to best irradiate tumor regions far from the vasculature, and (2) a separately administered, antibody, targeting any cancer-cell's surface marker, to best irradiate the tumor perivascular regions. We demonstrate that on a prostate specific membrane antigen (PSMA)-expressing prostate cancer xenograft mouse model, for the same total injected radioactivity of the α-particle emitter Actinium-225, any radioactivity split ratio between the two carriers resulted in better tumor growth inhibition compared to the tumor inhibition when the total radioactivity was delivered by any of the two carriers alone. This finding was due to more uniform tumor irradiation for the same total injected radioactivity. The killing efficacy was improved even though the tumor-absorbed dose delivered by the combined carriers was lower than the tumor-absorbed dose delivered by the antibody alone. Studies on spheroids with different receptor-expression, used as surrogates of the tumors' avascular regions, demonstrated that our delivery strategy is valid even for as low as 1+ (ImmunoHistoChemistry score) PSMA-levels. The findings presented herein may hold clinical promise for those established tumors not being effectively eradicated by current α-particle radiotherapies.

The complexity of modern in vivo magnetic resonance imaging (MRI) methods in oncology has dramatically changed in the last 10 years. The field has long since moved passed its (unparalleled) ability to form images with exquisite soft-tissue contrast and morphology, allowing for the enhanced identification of primary tumors and metastatic disease. Currently, it is not uncommon to acquire images related to blood flow, cellularity, and macromolecular content in the clinical setting. The acquisition of images related to metabolism, hypoxia, pH, and tissue stiffness are also becoming common. All of these techniques have had some component of their invention, development, refinement, validation, and initial applications in the preclinical setting using in vivo animal models of cancer. In this review, we discuss the genesis of quantitative MRI methods that have been successfully translated from preclinical research and developed into clinical applications. These include methods that interrogate perfusion, diffusion, pH, hypoxia, macromolecular content, and tissue mechanical properties for improving detection, staging, and response monitoring of cancer. For each of these techniques, we summarize the 1) underlying biological mechanism(s); 2) preclinical applications; 3) available repeatability and reproducibility data; 4) clinical applications; and 5) limitations of the technique. We conclude with a discussion of lessons learned from translating MRI methods from the preclinical to clinical setting, and a presentation of four fundamental problems in cancer imaging that, if solved, would result in a profound improvement in the lives of oncology patients. Level of Evidence: 5 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2019;50:1377-1392.

Hypoxia in cancers has evoked significant interest since 1955 when Thomlinson and Gray postulated the presence of hypoxia in human lung cancers, based on the observation of necrosis occurring at the diffusion limit of oxygen from the nearest blood vessel, and identified the implication of these observations for radiation therapy. Coupled with discoveries in 1953 by Gray and others that anoxic cells were resistant to radiation damage, these observations have led to an entire field of research focused on exploiting oxygenation and hypoxia to improve the outcome of radiation therapy. Almost 65 years later, tumor heterogeneity of nearly every parameter measured including tumor oxygenation, and the dynamic landscape of cancers and their microenvironments are clearly evident, providing a strong rationale for cancer personalized medicine. Since hypoxia is a major cause of extracellular acidosis in tumors, here, we have focused on the applications of imaging to understand the effects of hypoxia in tumors and to target hypoxia in theranostic strategies. Molecular and functional imaging have critically important roles to play in personalized medicine through the detection of hypoxia, both spatially and temporally, and by providing new understanding of the role of hypoxia in cancer aggressiveness. With the discovery of the hypoxia-inducible factor (HIF), the intervening years have also seen significant progress in understanding the transcriptional regulation of hypoxia-induced genes. These advances have provided the ability to silence HIF and understand the associated molecular and functional consequences to expand our understanding of hypoxia and its role in cancer aggressiveness. Most recently, the development of hypoxia-based theranostic strategies that combine detection and therapy are further establishing imaging-based treatment strategies for precision medicine of cancer.

Metastatic dissemination continues to be a major cause of prostate cancer (PCa) mortality, creating a compelling need to understand factors that play a role in the metastatic cascade. Since hypoxia plays an important role in PCa aggressiveness, we characterized patterns of hypoxia in the primary tumor and metastatic environments of a human PCa xenograft. We previously developed and characterized an imaging strategy based on the hypoxia response element (HRE)–driven expression of long-lived enhanced green fluorescent protein (EGFP) and short-lived luciferase (luc) fused to the oxygen-dependent degradation domain in human PCa PC-3 cells. Both reporter proteins were placed under the transcriptional control of a five–tandem repeat HRE sequence. PC-3 cells also constitutively expressed the tdTomato red fluorescent protein, allowing cancer cell detection in vivo. This “timer” strategy can provide information on the temporal evolution of HIF activity and hypoxia in tumors. Here, for the first time, we performed in vivo and ex vivo imaging of this dual HIF reporter system in PC-3 metastatic tumors implanted orthotopically in the prostate and PC-3 nonmetastatic tumors implanted subcutaneously. We observed distinct patterns of EGFP and luc expression in subcutaneous and orthotopic tumors, and in metastatic nodules, that provide new insights into the presence of hypoxia at primary and metastatic tumor sites, and of the role of hypoxia in metastasis.

Biomimetic nanoparticles (NPs) combine the flexibility and reproducibility of synthetic materials with the functionality of biological materials. Here, we developed and characterized biomimetic poly (lactic-co-glycolic acid) (PLGA) NPs coated with human cancer cell membrane fractions (CCMFs) to form CCMF coated PLGA (CCMF-PLGA) NPs. We evaluated the ability of these CCMF-PLGA NPs to disrupt cancer cell-stromal cell interactions, and to induce an immune response. Western blot analysis verified the plasma membrane purity of CCMFs. Confocal fluorescence microscopy and flow cytometry confirmed the presence of intact membrane-associated proteins including CXCR4 and CD44 following membrane derivation and coating. CCMFs and CCMF-PLGA NPs were capable of inhibiting cancer cell migration towards human mammary fibroblasts. Intravenous injection of CCMF-PLGA NPs significantly reduced experimental metastasis in vivo. Following immunization of Balb/c mice, near-infrared fluorescence imaging confirmed the migration of NPs to proximal draining lymph nodes. A higher percentage of CD8(+) and CD4(+) cytotoxic T-lymphocyte populations were observed in spleens and lymph nodes of CCMF-PLGA NP-immunized mice. Splenocytes isolated from CCMF-PLGA NP-immunized mice had the highest number of interferon gamma producing L cells as detected by the ELISpot assay. CCMF-PLGA NPs hold promise for disrupting cancer cell-stromal cell interactions, and for priming the immune system in cancer immunotherapy.

A diverse biomedical workforce is essential to achieve excellence in patient care, clinical translational, and basic research. Diversity, equity, and inclusion challenges in cancer molecular represent a combination of the challenges facing the science, technology, engineering, and mathematics (STEM) field, and challenges in Radiology and Nuclear Medicine. Although there is a growing awareness of conscious and unconscious bias that negatively affect the cancer imaging world, many challenges remain such as overcoming barriers to entry into the pipeline, avoiding program dropout, and providing long-term career prospect. The COVID-19 pandemic has resulted in a significant setback and further highlighted problems faced by women and underrepresented minorities. In this perspective, we have identified some of the challenges faced and highlighted ongoing and future initiatives to address these challenges.

PurposeThe inhibition of immune checkpoints such as programmed cell death ligand-1 (PD-L1/CD274) with antibodies is providing novel opportunities to expose cancer cells to the immune system. Antibody based checkpoint blockade can, however, result in serious autoimmune complications because normal tissues also express immune checkpoints. As sequence-specific gene-silencing agents, the availability of siRNA has significantly expanded the specificity and range of “druggable” targets making them promising agents for precision medicine in cancer. Here, we have demonstrated the ability of a novel biodegradable dextran based theranostic nanoparticle (NP) to deliver siRNA downregulating PD-L1 in tumors. Optical imaging highlighted the importance of NP delivery and accumulation in tumors to achieve effective downregulation with siRNA NPs, and demonstrated low delivery and accumulation in several PD-L1 expressing normal tissues.MethodsThe dextran scaffold was functionalized with small molecules containing amine groups through acetal bonds. The NP was decorated with a Cy5.5 NIR probe allowing visualization of NP delivery, accumulation, and biodistribution. MDA-MB-231 triple negative human breast cancer cells were inoculated orthotopically or subcutaneously to achieve differences in vascular delivery in the tumors. Molecular characterization of PD-L1 mRNA and protein expression in cancer cells and tumors was performed with qRT-PCR and immunoblot analysis.ResultsThe PD-L1 siRNA dextran NPs effectively downregulated PD-L1 in MDA-MB-231 cells. We identified a significant correlation between NP delivery and accumulation, and the extent of PD-L1 downregulation, with in vivo imaging. The size of the NP of ~ 20 nm allowed delivery through leaky tumor vasculature but not through the vasculature of high PD-L1 expressing normal tissue such as the spleen and lungs.ConclusionsHere we have demonstrated, for the first time, the feasibility of downregulating PD-L1 in tumors using siRNA delivered with a biodegradable dextran polymer that was decorated with an imaging reporter. Our data demonstrate the importance of tumor NP delivery and accumulation in achieving effective downregulation, highlighting the importance of imaging in siRNA NP delivery. Effective delivery of these siRNA carrying NPs in the tumor but not in normal tissues may mitigate some of the side-effects of immune checkpoint inhibitors by sparing PD-L1 inhibition in these tissues.

In magnetic resonance metabolic imaging, signal from the water content is frequently used for normalization to derive quantitative or semi-quantitative values of metabolites in vivo or ex vivo tumors and tissues. Ex vivo high-resolution metabolic characterization of tumors with magnetic resonance spectroscopy (MRS) provides valuable information that can be used to drive the development of noninvasive MRS biomarkers and to identify metabolic therapeutic targets. Variability in the water content between tumor and normal tissue can result in over or underestimation of metabolite concentrations when assuming a constant water content. Assuming a constant water content can lead to masking of differences between malignant and normal tissues both in vivo and ex vivo. There is a critical need to develop biomarkers to detect pancreatic cancer and to develop novel treatments. Our purpose here was to determine the differences in water content between pancreatic tumors and normal pancreatic tissue as well as other organs to accurately quantify metabolic differences when using the water signal for normalization. Our data identify the importance of factoring the differences in water content between tumors and organs. High-resolution proton spectra of tumors and pancreatic tissue extracts normalized to the water signal, assuming similar water content, did not reflect the significantly increased total choline observed in tumors in vivo without factoring the differences in water content. We identified significant differences in the collagen 1 content between Panc1 and BxPC3 pancreatic tumors and the pancreas that can contribute to the differences in water content that were observed.

Triple-negative breast cancer (TNBC) is an aggressive tumor with limited treatment options and poor prognosis. We applied the in vivo phage display technology to isolate peptides homing to the immunosuppressive cellular microenvironment of TNBC as a strategy for non-malignant target discovery. We identified a cyclic peptide (CSSTRESAC) that specifically binds to a vitamin D receptor, protein disulfide-isomerase A3 (PDIA3) expressed on the cell surface of tumor-associated macrophages (TAM), and targets breast cancer in syngeneic TNBC, non-TNBC xenograft, and transgenic mouse models. Systemic administration of CSSTRESAC to TNBC-bearing mice shifted the cytokine profile toward an antitumor immune response and delayed tumor growth. Moreover, CSSTRESAC enabled ligand-directed theranostic delivery to tumors and a mathematical model confirmed our experimental findings. Finally, in silico analysis showed PDIA3-expressing TAM in TNBC patients. This work uncovers a functional interplay between a cell surface vitamin D receptor in TAM and antitumor immune response that could be therapeutically exploited.

Introduction: Our ongoing studies are focused on characterizing metabolic changes induced in the organs of mice with cachexia-inducing Pa04C human pancreatic cancer xenografts. Because pancreatic cancer cells are glutamine dependent [1], we downregulated the glutamine transporter SLC1A5 in Pa04C cells to determine if metabolic changes induced in the spleen and pancreas by Pa04C tumors were normalized when SLC1A5 was downregulated in these tumors. Metabolic patterns were characterized using high-resolution quantitative 1H magnetic resonance spectroscopy (MRS) of spleen and pancreas tissue obtained from normal mice and mice with Pa04C tumors and mice with Pa04C tumors with SLC1A5 downregulated. Method: Patient derived cachexia-inducing Pa04C pancreatic cancer cells were lentivirally transduced to express shRNA to stably downregulate SLC1A5. Mice were euthanized once tumors were ~500 mm3, the spleen and pancreas were excised and snap frozen. Snap frozen spleen (normal n= 5, Pa04C n= 11, Pa04C_SLC1A5 n= 10) and pancreas (normal n= 4, Pa04C n= 16, Pa04C_SLC1A5 n= 10) tissue samples were pulverized for dual phase extraction. The aqueous phase was used for 1H MRS analysis. Topspin 3.5 software was used for data processing and analyses. Results and Discussion: Significant downregulation of SLC1A5 mRNA and protein was confirmed in Pa04C_SLC1A5 cells and tumors. SLC1A5 downregulation resulted in significant growth delay and attenuation of weight loss. A comparison of normal mice vs empty vector/wild type tumor (EV/WT) bearing mice identified significant changes in succinate, aspartate and fumarate in the spleen, lactate, acetate, pyruvate, methionine, asparagine, creatine, choline phosphocholine, uracil, histidine and phenylalanine in the pancreas, with leucine, isoleucine, valine, alanine, glutamate, glutamine, glutathione, glycerophosphocholine, glycine, glucose and tyrosine commonly altered in the spleen and pancreas. A comparison of normal vs Pa04C_ SLC1A5 tumor bearing mice identified similar metabolic changes in the spleen and pancreas but these were reduced. Fumarate did not change in the spleen, and of the metabolic changes common to spleen and pancreas, glutamine did not change when tumor SLC1A5 was downregulated. Metabolite changes induced only in the pancreas were also similar to normal vs EV/WT with the exception of a change in glutamine with SLC1A5 downregulation and no change in lactate. Our data highlight the profound metabolic changes in spleen and pancreas metabolism that occur with growth of a cachexia-inducing pancreatic cancer xenograft, and the impact on these metabolic patterns as a result of downregulating the glutamine transporter in these cancer cells. The metabolic patterns identified in the spleen and pancreas may provide novel targets to reduce the morbidity from cachexia. Reference: 1. Son J et al, Nature. 2013;496(7443):101-5. Citation Format: Raj Kumar Sharma, Santosh Kumar Bharti, Balaji Krishnamachary, Yelena Mironchik, Paul Winnard Jr., Marie-France Penet, Zaver M. Bhujwalla. Metabolic changes in the spleen and pancreas induced by PDAC xenografts with or without glutamine transporter downregulation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6353.

Cancer-induced cachexia is commonly observed in pancreatic cancer. The syndrome induces significant weight loss and leads to morbidity, intolerance to chemotherapy, and mortality. While performing metabolic characterization of the brain and plasma of mice with a cachexia-inducing human pancreatic cancer xenograft we identified significant changes in glutamine metabolism [1] that led us to investigate the effects of altering tumor glutamine metabolism on weight loss. We genetically engineered cachexia inducing Pa04C cells to express shRNA downregulating the glutamine transporter SLC1A5. Tumors derived from Pa04C cells with downregulated SLC1A5 (CSh cells and tumors) exhibited significantly delayed tumor growth compared to empty vector (EV) or wild type (WT) tumors, but escaped growth delay approximately 60 days after inoculation, although SLC1A5 mRNA and protein remained significantly downregulated. Despite tumor growth, mouse weight reduction was significantly attenuated at matched EV and CSh tumor volumes. We next sought to investigate if tumors derived from cells isolated from escaped CSh tumor (TSh cells and tumors) continued to exhibit growth delay and attenuated weight loss when re-inoculated in mice. Quantitative transcriptome profiling by RNA-seq was performed to determine differentially expressed genes in CSh and TSh cells compared to EV cells. Method: EV, CSh or TSh cells were inoculated subcutaneously in male mice. Tumor volumes and weights of tumor bearing mice were recorded until tumors were harvested at ~ 500 mm3 for molecular characterization. RNA was isolated in triplicate from EV, CSh and TSh cells. Transcriptomic analysis was performed by RNA sequencing on a NovaSeq 6000 PE150 platform. All bioinformatics analysis was performed with assistance from the NOVOGENE informatics group. Results: Tumors derived from TSh cells did not exhibit any growth delay unlike tumors derived from CSh cells. SLC1A5 expression remained downregulated in TSh cells and tumors. Despite the loss of growth delay, mice with TSh tumors continued to exhibit attenuated weight loss identifying, suggesting the glutamine transporter as a potential treatment strategy to reduce cachexia. Transcriptomic analysis allowed us to identify the adaptive changes that occurred in CSh tumors that allowed these tumors to escape growth delay despite SLC1A5 downregulation. Transcriptomic differences between TSh and CSh cells were primarily in pathways related to amino acid metabolism, inflammation and the extracellular matrix. These transcriptomic differences allow the identification of novel targets that can be used in combination with glutamine transporter downregulation to arrest the growth of pancreatic cancer cells in vivo. Supported by NIH R35 CA209960 and R01 CA193365. 1) J Cachexia Sarcopenia Muscle. 2020 Dec; 11(6): 1487-1500. Citation Format: Balaji Krishnamachary, Ishwarya Sivakumar, Yelena Mironchik, Raj Kumar Sharma, Santosh Kumar Bharti, Marie-France Penet, Paul Winnard, Eibhlin Goggins, Jiefu Jin, Anirban Maitra, Michael G. Goggins, Zaver M. Bhujwalla. Downregulation of glutamine transporter stably and significantly attenuates weight loss by a cachexia-inducing pancreatic cancer xenograft [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6305.

Small interfering RNA are suitable for gene silencing through a sequence-specific RNA interference process. The redundancy and complexity of molecular pathways in cancer create a need for multiplexed targeting that can be achieved with multiplexed siRNA delivery. Here we delivered multiplexed siRNA with a PSMA-targeted biocompatible dextran nanoparticle (NP) to downregulate CD46 and PD-L1 siRNA in PSMA expressing prostate cancer cells. The multiplexed gene targets selected, PD-L1 and CD46, play important roles in the escape of cancer cells from immune surveillance. PSMA is abundantly expressed by prostate cancer cells allowing prostate cancer specific delivery of the NPs. The NP was decorated with acid cleavable amine functional groups through acetal bonds that undergo degradation under acidic conditions providing rapid release of siRNA. Cell imaging and flow cytometry studies confirmed PSMA-specific delivery of CD46 and PD-L1 siRNA to high PSMA expressing PC-3 PIP cells. Immunoblot, qRT-PCR and flow cytometry confirmed downregulation of CD46 and PD-L1 following treatment with multiplexed siRNA at a concentration of 50 nM. These studies pave the way for delivering multiplexed siRNA to tumors in vivo to unmask tumors to the immune system using PSMA targeted biocompatible NPs. Citation Format: Zhihang Chen, Balaji Krishnamachary, Yelena Mironchik, Sangeeta R. Banerjee, Martin G. Pomper, Zaver M. Bhujwalla. Prostate-specific membrane antigen (PSMA) targeted multiplexed siRNA-mediated gene silencing of CD46 and PD-L1 in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5070.

Background Harnessing the power of the immune system by using immune checkpoint inhibitors has resulted in some of the most exciting advances in cancer treatment. The full potential of this approach has, however, not been fully realized for treating many cancers such as pancreatic and breast cancer. Cancer metabolism influences many aspects of cancer progression including immune surveillance. An expanded understanding of how cancer metabolism can directly impact immune checkpoints may allow further optimization of immunotherapy. We therefore investigated, for the first time, the relationship between the overexpression of choline kinase-α (Chk-α), an enzyme observed in most cancers, and the expression of the immune checkpoint PD-L1. Methods We used small interfering RNA to downregulate Chk-α, PD-L1, or both in two triple-negative human breast cancer cell lines (MDA-MB-231 and SUM-149) and two human pancreatic ductal adenocarcinoma cell lines (Pa09C and Pa20C). The effects of the downregulation were studied at the genomic, proteomic, and metabolomic levels. The findings were compared with the results obtained by the analysis of public data from The Cancer Genome Atlas Program. Results We identified an inverse dependence between Chk-α and PD-L1 at the genomic, proteomic, and metabolomic levels. We also found that prostaglandin-endoperoxide synthase 2 (COX-2) and transforming growth factor beta (TGF-β) play an important role in this relationship. We independently confirmed this relationship in human cancers by analyzing data from The Cancer Genome Atlas Program. Conclusions Our data identified previously unknown roles of PD-L1 in cancer cell metabolic reprogramming, and revealed the immunosuppressive increased PD-L1 effect of Chk-α downregulation. These data suggest that PD-L1 regulation of metabolism may be mediated through Chk-α, COX-2, and TGF-β. The observations provide new insights that can be applied to the rational design of combinatorial therapies targeting immune checkpoints and cancer metabolism.

Enhanced vascular permeability in tumors plays an essential role in nanoparticle delivery. Prostate-specific membrane antigen (PSMA) is overexpressed on the epithelium of aggressive prostate cancers (PCs). Here, we evaluated the feasibility of increasing the delivery of PSMA-targeted magnetic nanoparticles (MNPs) to tumors by enhancing vascular permeability in PSMA(+) PC tumors with PSMA-targeted photodynamic therapy (PDT). Method: PSMA(+) PC3 PIP tumor-bearing mice were given a low-molecular-weight PSMA-targeted photosensitizer and treated with fluorescence image-guided PDT, 4 h after. The mice were then given a PSMA-targeted MNP immediately after PDT and monitored with fluorescence imaging and T2-weighted magnetic resonance imaging (T2-W MRI) 18 h, 42 h, and 66 h after MNP administration. Untreated PSMA(+) PC3 PIP tumor-bearing mice were used as negative controls. Results: An 8-fold increase in the delivery of the PSMA-targeted MNPs was detected using T2-W MRI in the pretreated tumors 42 h after PDT, compared to untreated tumors. Additionally, T2-W MRIs revealed enhanced peripheral intra-tumoral delivery of the PSMA-targeted MNPs. That finding is in keeping with two-photon microscopy, which revealed higher vascular densities at the tumor periphery. Conclusion: These results suggest that PSMA-targeted PDT enhances the delivery of PSMA-targeted MNPs to PSMA(+) tumors by enhancing the vascular permeability of the tumors.