Biology subjects

Koong, A. C.

Publications and source records attributed to Koong, A. C..

11 recordsLinked to original sources

bioRxiv2026

CD4+ T-Cells Drive Triple Negative Breast Cancer Recurrence via Non-Canonical TGFβ Signaling

Radiation therapy is a cornerstone of breast cancer treatment and reduces recurrence overall. However, patients with triple negative breast cancer (TNBC) continue to experience recurrence at higher rates than patients with other subtypes, especially when immunocompromised. While CD8 T-cells are known to mitigate recurrence, the role of CD4+ T-cell subsets in shaping the irradiated microenvironment remains unclear. We show that irradiated mammary tissue from mice accumulates CD4+ T-cells and exhibits a TGF{beta}-enriched cytokine milieu coincident with macrophage infiltration. We demonstrate that Th2-polarized CD4+ T-cells promote invasion of TNBC cells and macrophages through secretion of TGF{beta}. Neutralization of TGF{beta} significantly reduces this invasive phenotype. Mechanistically, Th2-conditioned media induces Tgfb1 expression in both TNBC cells and macrophages, establishing a TGF{beta}-dependent feed-forward amplification loop. In TNBC cells, Th2-derived TGF{beta} activates non-canonical signaling characterized by increased p38 MAPK and NF-{kappa}B phosphorylation, linking cytokine exposure to pro-invasive behavior. Together, these findings identify Th2-derived TGF{beta} as a driver of pro-invasive tumor reprogramming and suggest that interruption of Th2-TGF{beta} signaling may prevent recurrence following therapy.

cancer biology↗

bioRxiv2026

Concurrent Stereotactic Body Radiation Therapy and KRAS Inhibition Synergistically Improve Pre-clinical Pancreatic Cancer Treatment

Pancreatic ductal adenocarcinoma (PDAC) is one of the most challenging cancers to treat due to the dismal survival rate, poor post-treatment outcome and profound resistance to a wide range of therapies. With mutant KRAS being a key driver, small molecule inhibitors targeting KRAS or pan-RAS (KRASi) have demonstrated exciting preclinical and early clinical anti-tumor efficacy, and the pan-RAS(ON) inhibitor daraxonrasib (RMC-6236) recently achieved Phase 3 clinically meaningful improvements in patient survival compared to chemotherapy. But resistance to RAS/KRAS inhibitor inevitably develops, which limits and compromises the treatment outcome. In this study, we investigated the combination of stereotactic body radiation therapy (SBRT) and KRAS inhibition (MRTX1133 and daraxonrasib) in the treatment of preclinical PDAC models. We found that this combination strategy synergistically suppresses PDAC cell growth in vitro and enhances tumor control while minimizing local recurrence in orthotopically implanted KPC (LSL-KrasG12D/+;Trp53R172H/+;Pdx1-Cre) murine PDAC tumors in vivo. As radiation therapy (RT) induces ferroptosis in multiple cancer types and mutant KRAS promotes various anti-ferroptotic mechanisms, we tested the role of ferroptosis in promoting tumor-control efficacy. Intriguingly, the addition of a ferroptosis inhibitor, liproxstatin-1, to the combination therapy significantly abrogated the in vivo synergism between SBRT and KRAS inhibition, suggesting that treatment-induced ferroptosis at least partially drives the synergistic efficacy of this combination strategy. Our study indicates that this SBRT-KRASi combination has the potential to overcome treatment resistance and improve outcomes in PDAC patients. These data directly support the design of a planned multi-center Phase 2 clinical trial with this combination strategy in locally advanced PDAC.

cancer biology↗

bioRxiv2025

FLASH Radiotherapy Mitigates Radiation-Induced Lymphopenia and Prevents Immunosuppression via Chk1-STAT3 Axis Modulation in a Preclinical Thoracic Irradiation Model

Background and AimsRadiation-induced lymphopenia (RIL) is a frequent side effect of conventional radiation therapy (CONV RT), due to the high radiosensitivity of circulating lymphocytes. Ultra-high dose rate "FLASH" RT may preferentially spare normal tissue while maintaining tumor control. This study evaluates the impact of single-fraction and multi-fraction thoracic FLASH RT on lymphocyte preservation, apoptosis, and immunosuppressive signaling in mice. MethodsWe compared the immunological impact of thoracic FLASH RT and CONV RT in C57BL/6 mice using single-fraction (17 Gy) and multi-fraction (2 Gy x 5) regimens using the Mobetron (IntraOp). Longitudinal blood sampling was performed at multiple time-points post-irradiation through facial vein bleed with flow cytometry analysis for CD4+, CD8+, CD19+, and NK cells to assess lymphocyte counts, apoptotic lymphocytes through Annexin V staining, and immune suppression by examining regulatory T cells (Tregs) and PD-1/PD-L1 expression. Mechanistic studies included immunofluorescence and Western blot analyses of splenic tissues to evaluate Chk1 and STAT3 signaling pathways. ResultsIn single-fraction RT, FLASH significantly reduced lung and heart fibrosis (p < 0.0001) at 28 weeks post-RT. The FLASH effect was also seen acutely on circulating immune cells, with significantly reduced lymphocyte apoptosis and accelerated recovery of CD4, CD8, CD3, NK, and B cell populations compared to CONV RT in both single-fraction and multi-fraction regimens. Conversely, CONV RT induced long-lasting increases in Tregs and sustained PD-1 and PD-L1 expression on T- and B-cells at 2- and 5-months post-irradiation in both fractionation regimens. Within the spleen, we also found CONV RT induced sustained activation of the Chk1-STAT3 pathway in CD45+ immune cells, which correlates with increased PD-1/PD-L1 expression. ConclusionFLASH RT mitigates RIL, reduces lymphocyte apoptosis, and prevents long-term immunosuppression by reduced activation of the Chk1-STAT3 pathway. These findings suggest FLASH RT may confer immunological advantages over CONV RT to enhance therapeutic efficacy.

cancer biology↗

bioRxiv2025

A spatial atlas of chemoradiation therapy in pancreatic cancer identifies cellular and microenvironmental determinants of persister populations

The molecular pathways involved in the response to radiation therapy in pancreatic ductal adenocarcinoma (PDAC) remain poorly understood. We aimed to elucidate the adaptive mechanisms and cellular interactions within PDAC to radiation therapy (RT). We constructed a transcriptomic landscape of the cellular subtypes and spatially resolved neighborhoods from 50 patient samples, including 16 longitudinally matched single cell RNA sequencing and 34 spatial transcriptomics specimens. To resolve shortcomings of cell-type mixtures in spatial data, we developed a novel statistical method called SpaCCI (spatially aware analysis of cell-cell interactions) to profile cell-cell interactions and ligand-receptor enrichment. This revealed CXCL12/TGF{beta}-driven persister cell niches where activated fibroblasts reprogram tumor- associated macrophages and spatially exclude stress-response CD8 T cells after RT. Persister cancer cells displayed transcriptional evidence of recalcitrance to metal-induced cell death pathways of ferroptosis and cuproptosis which were recapitulated in preclinical models. Our study reveals the selective pressures experienced by PDAC following RT that may help provide insight for future multimodal therapeutic strategies.

cancer biology↗

bioRxiv2024

Discordance in acute gastrointestinal toxicity between synchrotron-based proton and linac-based electron ultra-high dose rate irradiation

PurposeProton FLASH has been investigated using cyclotron and synchrocyclotron beamlines but not synchrotron beamlines. We evaluated the impact of dose rate (ultra-high [UHDR] vs. conventional [CONV]) and beam configuration (shoot-through [ST] vs. spread-out-Bragg-peak [SOBP]) on acute radiation-induced gastrointestinal toxicity (RIGIT) in mice. We also compared RIGIT between synchrotron-based protons and linac-based electrons with matched mean dose rates. Methods and MaterialsWe administered abdominal irradiation (12-14 Gy single fraction) to female C57BL/6J mice with an 87 MeV synchrotron-based proton beamline (2 cm diameter field size as a lateral beam). Dose rates were 0.2 Gy/s (S-T pCONV), 0.3 Gy/s (SOBP pCONV), 150 Gy/s (S-T pFLASH), and 230 Gy/s (SOBP pFLASH). RIGIT was assessed by the jejunal regenerating crypt assay and survival. We also compared responses to proton [pFLASH and pCONV] with responses to electron CONV (eCONV, 0.4 Gy/s) and electron FLASH (eFLASH, 188-205 Gy/s). ResultsThe number of regenerating jejunal crypts at each matched dose was lowest for pFLASH (similar between S-T and SOBP), greater and similar between pCONV (S-T and SOBP) and eCONV, and greatest for eFLASH. Correspondingly, mice that received pFLASH SOBP had the lowest survival rates (50% at 50 days), followed by pFLASH S-T (80%), and pCONV SOBP (90%), but 100% of mice receiving pCONV S-T survived (log-rank P = 0.047 for the four groups). ConclusionsOur findings are consistent with an increase in RIGIT after synchrotron-based pFLASH versus pCONV. This negative proton-specific FLASH effect versus linac-based electron irradiation underscores the importance of understanding the physical and biological factors that will allow safe and effective clinical translation.

cancer biology↗

bioRxiv2024

Redefining FLASH RT: the impact of mean dose rate and dose per pulse in the gastrointestinal tract

BackgroundThe understanding of how varying radiation beam parameter settings affect the induction and magnitude of the FLASH effect remains limited. PurposeWe sought to evaluate how the magnitude of radiation-induced gastrointestinal (GI) toxicity (RIGIT) depends on the interplay between mean dose rate (MDR) and dose per pulse (DPP). MethodsC57BL/6J mice were subjected to total abdominal irradiation (11-14 Gy single fraction) under conventional irradiation (low DPP and low MDR, CONV) and various combinations of DPP and MDR up to ultra-high-dose-rate (UHDR) beam conditions. The effects of DPP were evaluated for DPPs of 1-6 Gy while the total dose and MDR were kept constant; the effects of MDR were evaluated for the range 0.3- 1440 Gy/s while the total dose and DPP were kept constant. RIGIT was quantified in non-tumor-bearing mice through the regenerating crypt assay and survival assessment. Tumor response was evaluated through tumor growth delay. ResultsWithin each tested total dose using a constant MDR (>100 Gy/s), increasing DPP led to better sparing of regenerating crypts, with a more prominent effect seen at 12 and 14 Gy TAI. However, at fixed DPPs >4 Gy, similar sparing of crypts was demonstrated irrespective of MDR (from 0.3 to 1440 Gy/s). At a fixed high DPP of 4.7 Gy, survival was equivalently improved relative to CONV for all MDRs from 0.3 Gy/s to 104 Gy/s, but at a lower DPP of 0.93 Gy, increasing MDR produced a greater survival effect. We also confirmed that high DPP, regardless of MDR, produced the same magnitude of tumor growth delay relative to CONV using a clinically relevant melanoma mouse model. ConclusionsThis study demonstrates the strong influence that the beam parameter settings have on the magnitude of the FLASH effect. Both high DPP and UHDR appeared independently sufficient to produce FLASH sparing of GI toxicity, while isoeffective tumor response was maintained across all conditions.

cancer biology↗

bioRxiv2023

Innate immune receptor C5aR1 regulates cancer cell fate and can be targeted to improve radiotherapy in tumours with immunosuppressive microenvironments

An immunosuppressive microenvironment causes poor tumour T-cell infiltration and is associated with reduced patient overall survival in colorectal cancer. How to improve treatment responses in these tumours is still a challenge. Using an integrated screening approach to identify cancer-specific vulnerabilities, we identify complement receptor C5aR1 as a druggable target which when inhibited improves radiotherapy even in tumours displaying immunosuppressive features and poor CD8+ T-cell infiltration. While C5aR1 is well-known for its role in the immune compartment, we find that C5aR1 is also robustly expressed on malignant epithelial cells, highlighting potential tumour-cell specific functions. C5aR1 targeting results in increased NF-{kappa}B-dependent apoptosis specifically in tumours and not normal tissues; indicating that in malignant cells, C5aR1 primarily regulates cell fate. Collectively, these data reveal that increased complement gene expression is part of the stress response mounted by irradiated tumours and that targeting C5aR1 can improve radiotherapy even in tumours displaying immunosuppressive features.

cancer biology↗

bioRxiv2021

Aberrant BCMA Signaling Promotes Tumor Growth by Altering Protein Translation Machinery, a Therapeutic Target for the Treatment of Relapse/Refractory Multiple Myeloma

Recent T Cell therapies have been effective in the treatment of hematological cancers. However, immunotoxicity and treatment relapse pose significant clinical challenges. Here, we revealed distinctive requirement for neutralizing TNF receptor ligands APRIL and BAFF in MM and DLBCL. Furthermore, we investigated the use of BCMA decoy receptor (sBCMA-Fc) as a therapeutic inhibitor of ARPIL and BAFF. While wild-type sBCMA-Fc successfully blocked APRIL signaling with picomolar binding affinity, inhibiting tumor growth in MM models, it lacked efficacy in inhibiting DLBCL progression due to its weak binding for BAFF. To expand the therapeutic utility of sBCMA-Fc, using a protein engineering approach, we generated an affinity enhanced mutant sBCMA-Fc fusion molecule (sBCMA-Fc V3) with 4-folds and 500-folds enhancement in binding to APRIL and BAFF respectively. The sBCMA-Fc V3 clone significantly enhanced antitumor activity against both MM and DLBCL. Importantly, sBCMA-Fc V3 was proven to be a viable clinical candidate by showing adequate toxicity profile and on-target mechanism of action in nonhuman primates. SUMMARYThis study demonstrates the dichotomous function of APRIL and BAFF in MM and DLBCL, that can be safely targeted by an engineered fusion protein designed to trap APRIL and BAFF with ultra-high binding affinity.

cancer biology↗

bioRxiv2020

Stress-induced tyrosine phosphorylation of RtcB modulates IRE1 activity and signaling outputs.

Endoplasmic Reticulum (ER) stress is a hallmark of various diseases, which is dealt with through the activation of an adaptive signaling pathway named the Unfolded Protein Response (UPR). This response is mediated by three ER-resident sensors and the most evolutionary conserved, IRE1 signals through its cytosolic kinase and endoribonuclease (RNase) activities. IRE1 RNase activity can either catalyze the initial step of XBP1 mRNA unconventional splicing or degrade a number of RNAs through Regulated IRE1- Dependent Decay (RIDD). The balance between these two activities plays an instrumental role in cells life and death decisions upon ER stress. Until now, the biochemical and biological outputs of IRE1 RNase activity have been well documented, however, the precise mechanisms controlling whether IRE1 signaling is adaptive or pro-death (terminal) remain unclear. This prompted us to further investigate those mechanisms and we hypothesized that XBP1 mRNA splicing and RIDD activity could be co-regulated by the IRE1 RNase regulatory network. We showed that a key nexus in this pathway is the tRNA ligase RtcB which, together with IRE1, is responsible for XBP1 mRNA splicing. We demonstrated that RtcB is tyrosine phosphorylated by c-Abl and dephosphorylated by PTP1B. Moreover, we identified RtcB Y306 as a key residue which, when phosphorylated, perturbs RtcB interaction with IRE1, thereby attenuating XBP1 mRNA splicing and favoring RIDD. Our results demonstrate that the IRE1 RNase regulatory network is dynamically fine-tuned by tyrosine kinases and phosphatases upon various stresses and that the nature of the stress determines cell adaptive or death outputs.

biochemistry↗

bioRxiv2019

FLASH irradiation enhances the therapeutic index of abdominal radiotherapy in mice

Peritoneal metastases are the leading cause of morbidity and mortality in ovarian cancer. Despite current surgery, chemotherapy and targeted therapies, the majority of patients diagnosed with advanced epithelial ovarian cancer develop recurrent disease and overall survival rates remain poor. It is known that ovarian cancer is a radiosensitive tumor. Historically, total abdominal irradiation (TAI) was used as an effective postsurgical adjuvant therapy in the management of chemotherapy sensitive and resistant ovarian cancer. However, TAI fell out of favor due to high toxicity, particularly of the gastrointestinal tract. We have developed a preclinical irradiation platform that allows for total abdominal ultrahigh dose rate FLASH irradiation. We demonstrate that TAI-FLASH reduces radiation-induced intestinal injury in both healthy and tumor-bearing mice compared to conventional dose rate (CONV) irradiation. Single high dose TAI-FLASH reduced mortality from gastrointestinal syndrome, spared gut function and epithelial integrity, and decreased cell death in crypt base columnar cells. Importantly, FLASH and CONV irradiation had similar efficacy in the reduction of ovarian cancer peritoneal metastases. These findings suggest that FLASH irradiation may be an effective strategy to enhance the therapeutic index of radiotherapy for the treatment of metastatic ovarian cancer in women.

cancer biology↗

bioRxiv2019

Microenvironmental adaptations drive obesity-associated pancreatic cancer

Obesity is a major modifiable risk factor for pancreatic ductal adenocarcinoma (PDAC), yet how and when obesity contributes to PDAC progression is not well understood. Leveraging an autochthonous mouse model, we demonstrate a causal and reversible role for obesity in early PDAC progression, showing that obesity markedly enhances tumorigenesis, while genetic or dietary induction of weight loss intercepts cancer development. Bulk and single cell molecular analyses of human and murine samples define microenvironmental consequences of obesity that promote tumor development rather than new driver gene mutations. We observe increased inflammation and fibrosis and also provide evidence for significant pancreatic islet cell adaptation in obesity-associated tumors. Specifically, we identify aberrant islet beta cell expression of the peptide hormone cholecystokinin (CCK) in tumors as an adaptive response to obesity. Furthermore, beta cell CCK expression promotes oncogenic Kras-driven pancreatic ductal tumorigenesis. Our studies argue that PDAC progression is driven by local obesity-associated changes in the tumor microenvironment - rather than systemic effects - and implicate endocrine-exocrine signaling beyond insulin in PDAC development. Furthermore, our demonstration that these obesity-associated adaptations are reversible supports the use of anti-obesity strategies to intercept PDAC early during progression.

cancer biology↗