Cellular and Molecular Bioengineering

Integrins are heterodimeric cell surface receptors that govern cell-cell interactions, which in turn can influence multiscale processes: cell migration, extracellular matrix remodeling and tissue formation. These processes occur over timescales which range from milliseconds to days. While various strategies exist to study integrin function across biological scales from cell to tissue, they are often chronic and fail to target specific cell-cell interactions acutely. We engineered cells to rapidly alter cell behavior by downregulating the surface population of 5{beta}1 integrins through hot-wired clathrin-mediated endocytosis. This method allows for inducible, specific internalization of 5{beta}1 integrins, achieving acute downregulation across various cell lines in 5-30 minutes. We show that induced internalization of 5{beta}1 decreases the cell area, causes uptake of extracellular fibronectin, and decreases the rate of tumor spheroid compaction. This targeted control of multiscale processes by rapid downregulation of this important class of cell surface receptors demonstrates that hot-wired endocytosis is a useful tool to acutely modulate cell biology.

BackgroundColorectal cancer (CRC) remains a significant global health burden, with KRAS mutations driving [~]40% of cases. Efficacy of recently approved, mutant-specific KRAS inhibitors is limited by intrinsic and adaptive resistance mechanisms. Pan-RAS inhibitors, such as ADT-007, offer broader therapeutic potential by targeting multiple RAS isoforms. Here, we evaluate ADT-007 in 3D bioprinted organoid tumors (BOTs) generated from KRAS-mutant and RAS wild-type (WT) CRC cell lines. MethodsPotency and selectivity of ADT-007 were compared to bortezomib, a proteasome inhibitor, and YM155, a survivin inhibitor, using high-content imaging and ATP-based luminescence assays. Mechanistic studies assessed impact on RAS activation and downstream signaling. ResultsADT-007 exhibited high potency and selectivity in KRAS-mutant BOTs, reducing tumor burdens >30% at nanomolar concentrations, and demonstrated superior selectivity over bortezomib and YM155 with minimal cytotoxicity in RAS-WT BOTs. Mechanistic analysis confirmed ADT-007 inhibited RAS activation and downstream signaling, leading to selective apoptosis induction in KRAS-mutant CRC cells. ConclusionsThe selective potency and specificity of ADT-007 warrants further investigation of pan-RAS inhibitors for treating RAS-driven cancers. This study also underscores the translational utility of 3D BOT models for preclinical drug response assessment. Further validation in patient-derived BOTs is necessary to evaluate potential of ADT-007 in clinical settings.

Colorectal cancer (CRC) tumors start as precancerous polyps on the inner lining of the colon or rectum, where they are exposed to the mechanics of colonic peristalsis. Our previous work leveraged a custom-built peristalsis bioreactor to demonstrate that colonic peristalsis led to cancer stem cell enrichment in colorectal cancer cells. However, this malignant mechanotransductive response was confined to select CRC lines that harbored an oncogenic mutation in the KRAS gene. In this work, therefore, we explored the involvement of activating KRAS mutations on peristalsis-associated mechanotransduction in CRC. Peristalsis enriched the cancer stem cell marker LGR5 in KRAS mutant (G13D, etc.) lines, in a Wnt-independent manner. Conversely, LGR5 enrichment in wild type KRAS lines exposed to peristalsis were minimal. LGR5 enrichment downstream of peristalsis translated to increased tumorigenicity in vivo in KRAS mutant vs. wild type lines. Differences in mechanotransduction response was additionally apparent via unbiased gene set enrichment analysis, where many unique pathways were enriched in wild type vs. mutant lines, in response to peristalsis. Interestingly, peristalsis also triggered {beta}-catenin nuclear localization independent of Wnt, particularly in KRAS mutant lines. The central involvement of KRAS in the mechanotransductive responses was validated via gain and loss of function strategies. {beta}-catenin activation and LGR5 enrichment downstream of peristalsis converged to the activation of the MEK/ERK kinase cascade, that remains active in cells that harbor oncogenic KRAS mutations. Taken together, our results demonstrated that oncogenic KRAS mutations conferred a unique peristalsis-associated mechanotransduction response to colorectal cancer cells, resulting in cancer stem cell enrichment and increased tumorigenicity. These mechanosensory connections can be leveraged in improving the sensitivity of emerging therapies that target oncogenic KRAS.

Carcinomas commonly recur and progress rapidly after a period of remission following platinum-based therapy. This clinical scenario suggests that surviving drug-resistant tumor cells are dormant or slow cycling before re-entering a rapid growth phase. Remodeling of the recurrent tumor microenvironment (TME) contributes to high rates of metastasis, but little is known about differences in TME remodeling before therapy and after recurrence. This study explores selection for cisplatin-resistant subpopulations of A549 lung adenocarcinoma cells in culture to derive populations for modeling features of the recurrent TME. A cisplatin dose of 25 M killed approximately 80% of the cells while sparing enough cells to allow re-expansion of sufficient cell numbers for downstream experimentation. Expanded cisplatin-resistant derivatives (Cis-R A549) exhibited features of mesenchymal transition (EMT) such as cellular hypertrophy, loss of cell-cell contacts, and upregulation of alpha smooth muscle actin mRNA. In 3D culture, Cis-R A549 spheroids were loosely aggregated and dysmorphic in comparison to the compact and spherical parent A549 spheroids. The Ki67 index of Cis-R A549 in 2D and 3D spheroid culture was markedly lower than parent A549, suggesting a state of pseudo-dormancy with slow cycling. Cis-R A549 upregulated multiple genes associated with the evolution of a more aggressive TME and displayed significantly increased proangiogenic capacity in a microphysiological model of tumor angiogenesis. This study establishes a methodological framework for engineering the recurrent TME with drug-resistant cancer cell line derivatives selected via high-dose exposure in culture. Increased angiogenesis induced by Cis-R A549 suggests that anti-angiogenic therapy may be more beneficial in the setting of recurrent disease following first-line therapies.

Cancer treatment is shifting towards precise medicine informed by tumor genetics and structural features. In recent years, it has become increasingly recognized that patient tumors--even those of the same tissue origin--can differ substantially between patients and respond differently to treatment. Given this, it is necessary to design therapies that target the heterogeneity of tumors. When investigating novel therapeutics in the laboratory, conventional cell culture models do not adequately recapitulate this heterogeneity and therefore may not accurately represent drug responses. Recent advances in miniaturized organ-on-a-chip models have been able to generate more complex microenvironments for in vitro studies. However, many of these models do not resemble the scale of clinically relevant tumors and pose a high barrier to use because they are technically complex. To facilitate mechanistic studies of the tumor microenvironment (TME), we designed T-SLICE, a chip made using commercially available elastomers and designed to fit in a standard 6-well plate. This simple 3-D tumor model incorporates microfluidic principles into a fully customizable TME, wherein cells drive the formation of biochemical gradients akin to those observed within a real tumor. In T-SLICE, spheroids are seeded atop a monolayer of fibroblasts situated between two closely spaced coverslips (300-700 {micro}m). The restrictive gap height limits the permeation of oxygen (O2) and hinders the removal of carbon dioxide (CO2) and metabolic waste, which leads to the generation of tumor-like hypoxic gradients. We demonstrate that T-SLICE establishes cell-driven oxygen gradients leading to the formation of a hypoxic core, with further impacts on cellular viability, mitochondrial membrane potential (MMP), and proliferation. T-SLICE cultures can be imaged live or fixed and stained for immunohistochemistry (IHC). These features of T-SLICE make it an accessible and faithful model of a tumors heterogeneity and open the possibility for more faithful testing of novel therapeutics in the context of a realistic TME.

Bone provides a favorable niche for breast cancer colonization and metastatic progression. Breast cancer cells are attracted to the bone microenvironment where they induce bone cells to resorb bone, which enhances tumor cell proliferation in a positive feedback loop often referred to as the vicious cycle. While this phenomenon is established, the molecular interactions between cancer cells and bone cells are not well defined. CXCL5/CXCR2 signaling has recently been shown to promote breast cancer colonization to the bone. Here, we investigate the effects of osteoblasts and osteocytes on breast cancer cell proliferation in engineered two- and three-dimensional models. We observed that osteoblasts and osteocytes induce proliferative effects on cancer cells. Specifically, bone cells increase cancer proliferation in 2D culture and osteoblasts increase cancer growth more than osteocytes in 3D models. Moreover, osteocyte interaction with cancer cells in 3D models are stiffness dependent. We show that these effects depend on the CXCL5/CXCR2 signaling axis. Taken together, we demonstrate that osteoblasts drive cancer growth in a bone metastatic niche and that this effect can be rescued with CXCL5/CXCR2 inhibition.

Mucus is an impregnable barrier for drug delivery across the epithelia for treatment of mucosal-associated diseases. While current carriers are promising for mucus penetration, their surface chemistries do not possess chemical complexity to probe and identify optimal physicochemical properties desired for mucus penetration. As initial study, we use M13 phage display presenting random peptides to select peptides that can facilitate permeation through hyperconcentrated mucin. Here, a net-neutral charge, hydrophilic peptide was identified to facilitate transport of phage and fluorophore conjugates through mucin barrier compared to controls. This initial finding warrants further study to understand how composition and spatial distribution of physicochemical properties of peptides can be optimized to improve transport across the mucus barrier.

Drug resistance remains a major challenge in cancer treatment by contributing to recurrence and metastasis. Fractional killing, in which only a subset of cells undergo apoptosis after drug exposure, is a key contributor to this resistance and is influenced by genetic and nongenetic heterogeneity within the tumor microenvironment. Solid tumors display substantial variation in extracellular matrix stiffness, providing evidence that the mechanical context of cancer and stromal cells may play an important role in therapeutic response. Here, we investigated how substrate stiffness affects the dynamics of apoptosis and the mechanisms behind differences in the cell death response to doxorubicin (DOX). HeLa cells cultured on stiffer substrates exhibited enhanced caspase-3/7 activation and increased apoptotic cell death, whereas cells on soft substrates showed markedly reduced apoptotic signaling and improved survival. Although substrate stiffness altered cytoskeletal organization, pharmacological disruption of actin polymerization or actomyosin contractility did not influence nuclear DOX accumulation, indicating that cytoskeletal mechanics were not the primary factor in the stiffness-dependent sensitivity. Instead, flow cytometry revealed that substrate stiffness modulates cell-cycle distribution, with soft substrates enriched in the G1 population and a reduced fraction of cells in the DOX-sensitive S phase. Synchronizing cells at the G1/S phase boundary eliminated stiffness-dependent differences in apoptotic activation, demonstrating that cell-cycle state is a dominant driver of stiffness-mediated fractional killing. These findings highlight a mechanistic link between extracellular matrix mechanics and chemotherapeutic response by suggesting that microenvironment-regulated cell-cycle dynamics contribute to drug resistance in mechanically heterogeneous tumors.

Cell adhesion and polarization are fundamental processes in tissue organization and mechanosensitive signaling. Here, we demonstrate that activation of the borate transporter NaBC1 enhances myoblast adhesion and polarization by modulating integrin expression and actin cytoskeleton dynamics. Using C2C12 myoblasts cultured on fibronectin-functionalized substrates, we show that NaBC1 stimulation induces the formation of more and larger focal adhesions, promotes early cell spreading, and reduces retrograde actin flow, indicative of molecular clutch engagement. This enhanced adhesive state is accompanied by the transcriptional and protein-level upregulation of fibronectin-binding integrins (5{beta}1, v{beta}3), and by their spatial colocalization with NaBC1 at the cell membrane. Furthermore, FITC-labelled boron accumulates in focal adhesions and intracellular compartments such as mitochondria, lysosomes, and the ER, suggesting a role for boron in both adhesion and subcellular signaling. These effects are fibronectin-specific and are abrogated in cells exposed to mutant fibronectins and laminin-111 (unable to activate the molecular clutch). Altogether, our results identify the boron transporter NaBC1 as a modulator of myoblast adhesion and mechanotransduction acting in close cooperation with fibronectin-binding integrins.

Pancreatic ductal adenocarcinoma (PDAC) is the 4th leading cause of cancer-related deaths in the U.S., despite only being the 11th most common cancer. The high mortality rates of PDAC can be partially attributed to the tumor microenvironment. Unlike most carcinomas, PDAC is characterized by a strong desmoplastic reaction, or a fibrotic stiffening of the extracellular matrix (ECM) in response to chronic inflammation. The desmoplastic reaction is mediated by cancer-associated fibroblasts that deposit ECM proteins (collagens, laminins, fibronectin, etc.) and secrete matrix-remodeling proteins in the tumor parenchyma. Within the past decade, the enzyme quiescin sulfhydryl oxidase 1 (QSOX1) has gained recognition as a significant contributor to solid tumor pathogenesis, but its biological role remains uncertain. QSOX1 is a disulfide bond-generating catalyst that participates in oxidative protein folding in the mammalian cell. Current studies show that inhibiting or knocking down QSOX1 reduces pancreatic cancer cell migration and invasion, alters ECM deposition and organization, and decreases overall tumor growth in mice. However, it is unclear which features of the tumor microenvironment modulate QSOX1 and cause its overexpression in cancer. In this study, we explored potential regulators of QSOX1 expression and secretion by testing two major features of PDAC: hypoxia and mechanical stiffness. To induce hypoxia, we exposed pancreatic cancer cells to atmospheric (low O2) and chemical (CoCl2) hypoxia for up to 48 hours. QSOX1 gene and protein expression did not change in response to hypoxia. Substratum stiffness was modulated using polyacrylamide gels to represent the dynamic pathological range of elastic moduli found in PDAC tissue. We discovered that QSOX1 levels were decreased on softer surfaces compared to conventional tissue culture plastic. This paper presents new results and challenges prior findings on QSOX1 regulation in pancreatic tumor cells.

Systemic chemotherapeutics target cancer cells but are also known to impact other cells away from the tumor. Questions remain whether systemic chemotherapy crosses the blood-brain barrier and causes inflammation in the periphery that impacts the central nervous system (CNS) downstream. The meningeal lymphatics are a critical component that drain cerebrospinal fluid from the CNS to the cervical lymph nodes for immunosurveillence. To develop new tools for understanding chemotherapy-mediated effects on the meningeal lymphatics, we present two novel models that examine cellular and tissue level changes. Our in vitro tissue engineered model of a meningeal lymphatic vessel lumen, using a simple tissue culture insert system with both lymphatic endothelial and meningeal cells, examines cell disruption. Our ex vivo model culturing mouse meningeal layers probes structural changes and remodeling, correlating to an explant tissue level. To gain a holistic understanding, we compare our in vitro and ex vivo models to in vivo studies for validation and a three-tier methodology for examining the chemotherapeutic response of the meningeal lymphatics. We have demonstrated that the meningeal lymphatics can be disrupted by systemic chemotherapy but show differential responses to platinum and taxane chemotherapies, emphasizing the need for further study of off-target impacts in the CNS.

PurposeAfter stromal injury to the cornea, the release of growth factors and pro-inflammatory cytokines promotes the activation of quiescent keratocytes into a migratory fibroblast and/or fibrotic myofibroblast phenotype. Persistence of the myofibroblast phenotype can lead to corneal fibrosis and scarring, which are leading causes of blindness worldwide. This study aims to establish comprehensive transcriptional profiles for cultured corneal keratocytes, fibroblasts, and myofibroblasts to gain insights into the mechanisms through which these phenotypic changes occur. MethodsPrimary rabbit corneal keratocytes were cultured in either defined serum-free media (SF), fetal bovine serum (FBS) containing media, or in the presence of TGF-{beta}1 to induce keratocyte, fibroblast, or myofibroblast phenotypes, respectively. Bulk RNA sequencing followed by bioinformatic analyses was performed to identify significant differentially expressed genes (DEGs) and enriched biological pathways for each phenotype. ResultsGenes commonly associated with keratocytes, fibroblasts, or myofibroblasts showed high relative expression in SF, FBS, or TGF-{beta}1 culture conditions, respectively. Differential expression and functional analyses revealed novel DEGs for each cell type, as well as enriched pathways indicative of differences in proliferation, apoptosis, extracellular matrix (ECM) synthesis, cell-ECM interactions, cytokine signaling, and cell mechanics. ConclusionsOverall, these data demonstrate distinct transcriptional differences among cultured corneal keratocytes, fibroblasts, and myofibroblasts. We have identified genes and signaling pathways that may play important roles in keratocyte differentiation, including many related to mechanotransduction and ECM biology. Our findings have revealed novel molecular markers for each cell type, as well as possible targets for modulating cell behavior and promoting physiological corneal wound healing.

Obesity is a leading risk factor of pancreatic ductal adenocarcinoma (PDAC) that contributes to poor disease prognosis and outcomes. Retrospective studies have identified this link, but interactions surrounding obesity and PDAC are still unclear. Research has shifted to contributions of fibrosis (desmoplasia) on malignancy, which involves increased deposition of collagens and other extracellular matrix (ECM) molecules and increased ECM crosslinking, all of which contribute to increased tissue stiffening. However, fibrotic stiffening is underrepresented as a model feature in current PDAC models. Fibrosis is shared between PDAC and obesity, and can be leveraged for in vitro model design, as current animal obesity models of PDAC are limited in their ability to isolate individual components of fibrosis to study cell behavior. In the current study, methacrylated type I collagen (PhotoCol(R)) was photo-crosslinked to pathological stiffness levels to recapitulate fibrotic ECM stiffening. PANC-1 cells were encapsulated within PhotoCol(R), and the tumor-tissue constructs were prepared to represent normal (healthy) ([~]600 Pa) and pathological ([~]2000 Pa) tissues. Separately, human mesenchymal stem cells were differentiated into adipocytes representing lean (2D differentiation) and obese fat tissue (3D collagen matrix differentiation), and conditioned media was applied to PANC-1 tumor-tissue constructs. Conditioned media from obese adipocytes showed increased vimentin expression, a hallmark of invasiveness and progression, that was not seen after exposure to media from lean adipocytes or control media. Characterization of the obese adipocyte secretome suggested that some PANC-1 differences may arise from increased interleukin-8 and -10 compared to lean adipocytes. Additionally, high matrix stiffness associated induced an amoeboid morphology in PANC-1 cells that was not present at low stiffness. Amoeboid morphology is an accessory to epithelial-to-mesenchymal transition and is used to navigate complex ECM environments. This plasticity has greater implications for treatment efficacy of metastatic cancers. Overall, this work 1) highlights the importance of investigating PDAC-obesity interactions to study the effects on disease progression and persistence, 2) establishes PhotoCol(R) as a matrix material that can be leveraged to study amoeboid morphology and invasion in PDAC, and 3) emphasizes the importance of integrating both biophysical and biochemical interactions associated within both pathologies for in vitro PDAC models.

Breast cancer progression is marked by extracellular matrix (ECM) remodeling, including increased stiffness, faster stress relaxation, and elevated collagen levels. In vitro experiments have revealed a role for each of these factors to individually promote malignant behavior, but their combined effects remain unclear. To address this, we developed alginate-collagen hydrogels with independently tunable stiffness, stress relaxation, and collagen density. We show that these combined tumor-mimicking ECM cues reinforced invasive morphologies and promoted spheroid invasion in breast cancer and mammary epithelial cells. High stiffness and low collagen density in slow-relaxing matrices led to the greatest cell migration speed and displacement. RNA-seq revealed Sp1 target gene enrichment in response to both individual and combined ECM cues, with a greater enrichment observed under multiple cues. Notably, high expression of Sp1 target genes upregulated by fast stress relaxation correlated with poor patient survival. Mechanistically, we found that phosphorylated-Sp1 (T453) was increasingly located in the nucleus in stiff and/or fast relaxing matrices, which was regulated by PI3K and ERK1/2 signaling, as well as actomyosin contractility. This study emphasizes how multiple ECM cues in complex microenvironments reinforce malignant traits and supports an emerging role for Sp1 as a mechanoresponsive transcription factor.

During corneal wound healing, stromal keratocytes transform into a repair phenotype that is driven by the release of cytokines, like transforming growth factor-beta 1 (TGF-{beta}1) and platelet-derived growth factor-BB (PDGF-BB). Previous work has shown that TGF-{beta}1 promotes the myofibroblast differentiation of corneal keratocytes in a manner that depends on PDGF signaling. In addition, changes in mechanical properties are known to regulate the TGF-{beta}1-mediated differentiation of cultured keratocytes. While PDGF signaling acts synergistically with TGF-{beta}1 during myofibroblast differentiation, how treatment with multiple growth factors affects stiffness-dependent differences in keratocyte behavior is unknown. Here, we treated primary corneal keratocytes with PDGF-BB and TGF-{beta}1 and cultured them on polyacrylamide (PA) substrata of different stiffnesses. In the presence of TGF-{beta}1 alone, the cells underwent stiffness-dependent myofibroblast differentiation. On stiff substrata, the cells developed robust stress fibers, exhibited high levels of -SMA staining, formed large focal adhesions (FAs), and exerted elevated contractile forces, whereas cells in a compliant microenvironment showed low levels of -SMA immunofluorescence, formed smaller focal adhesions, and exerted decreased contractile forces. When the cultured keratocytes were treated simultaneously with PDGF-BB however, increased levels of -SMA staining and stress fiber formation were observed on compliant substrata, even though the cells did not exhibit elevated contractility or focal adhesion size. Pharmacological inhibition of PDGF signaling disrupted the myofibroblast differentiation of cells cultured on substrata of all stiffnesses. These results indicate that treatment with PDGF-BB can decouple molecular markers of myofibroblast differentiation from the elevated contractile phenotype otherwise associated with these cells, suggesting that crosstalk in the mechanotransductive signaling pathways downstream of TGF-{beta}1 and PDGF-BB can regulate the stiffness-dependent differentiation of cultured keratocytes. Statement of SignificanceIn vitro experiments have shown that changes in ECM stiffness can regulate the differentiation of myofibroblasts. Typically, these assays involve the use of individual growth factors, but it is unclear how stiffness-dependent differences in cell behavior are affected by multiple cytokines. Here, we used primary corneal keratocytes to show that treatment with both TGF-{beta}1 and PDGF-BB disrupts the dependency of myofibroblast differentiation on substratum stiffness. In the presence of both growth factors, keratocytes on soft substrates exhibited elevated -SMA immunofluorescence without a corresponding increase in contractility or focal adhesion formation. This result suggests that molecular markers of myofibroblast differentiation can be dissociated from the elevated contractile behavior associated with the myofibroblast phenotype, suggesting potential crosstalk in mechanotransductive signaling pathways downstream of TGF-{beta}1 and PDGF-BB.

To recapitulate prostate cancer metastasis, DU145 cells were cultured in a hyaluronic acid-based, bioorthogonally constructed, protease-degradable hydrogel. In the presence of covalently conjugated integrin-binding peptide (GRGDSP), DU145 cells formed tumoroids and exhibited small protrusions. Upon addition of soluble transforming growth factor beta 1 (TGF{beta}1), cells underwent morphological changes to form extended interconnected cellular networks. Contrarily, in RGD-free hydrogels, cells maintained spherical structures even in the presence of TGF{beta}1. In RGD-conjugated hydrogels, TGF{beta}1 induced nuclear localization of SMAD2/3, upregulating a wide range of TGF{beta}1 target genes and proteins. Prolonged exposure to TGF{beta}1 led to matrix remodeling and induced epithelial-to-mesenchymal transition in DU145 cells, with loss of epithelial markers and gain of mesenchymal markers. TGF{beta}RI/ALK5 inhibitor SB-431542 attenuated TGF{beta}1-induced morphological changes, abrogated nuclear localization of SMAD2/3, and restored the expression of key epithelial markers. Our findings highlight the cooperative role of TGF{beta}1 signaling and integrin binding peptide in the acquisition of aggressive phenotype and promoting tumor progression. TEASERPhysiologically relevant 3D cell culture platforms enabled mechanistic investigation of growth factor signaling related to prostate cancer metastasis.

Endometriosis is a painful gynaecological condition characterized by ectopic growth of endometrial cells outside of the uterus. Little is known about the mechanisms by which endometrial fragments invade tissues. This is partially due to a lack of suitable experimental models. In this study, we show that a spheroid 3D model, but not single cells mimic the collective endometrial fragment-like invasion through the extracellular matrix. This model reveals that collagen I, the main constituent of surgical scars, significantly increases the rate of lesion formation by healthy endometrial stromal cells (St-T1b) in vitro compared to the basement membrane-like matrix Matrigel. Stromal cell invasion of collagen I requires MMPs, whereas collective migration of endometriotic epithelial 12Z cells involves Rac-signalling. We show that inhibiting ROCK signalling responsible for actomyosin contraction increases the lesion-size. Moreover, endometriotic epithelial 12Z cells, but not eutopic stromal cells St-T1b migrate on Matrigel. The rate of this migration is decreased by the microRNA miR-200b and increased by miR-145. Our 3D model offers a facile approach to dissect how endometrial fragments invade tissues and is an important step toward developing new personalized therapeutics for endometriosis. Moreover, our model is a suitable tool to screen small molecule drugs and microRNA-based therapeutics.

Small-cell-lung-cancer (SCLC) has the worst prognosis of all lung cancers because of a high incidence of relapse after therapy. We developed a bioengineered 3-dimensional (3D) SCLC co-culture organoid as a phenotypic tool to study SCLC tumor kinetics and SCLC-fibroblast interactions during relapse. We used functionalized alginate microbeads as a scaffold to mimic lung alveolar architecture and co-cultured SCLC cell lines with primary adult lung fibroblasts (ALF). We found that SCLCs in the model proliferated extensively, invaded the microbead scaffold and formed tumors within just 7 days. We compared the bioengineered tumors with patient tumors and found them to recapitulate the pathology and immunophenotyping of the patient tumors better than the PDX model developed from the same SCLC cell line. When treated with standard chemotherapy drugs, etoposide and cisplatin, the organoid recapitulated relapse after chemotherapy. Co-culture of the SCLC cells with ALFs revealed that the fibroblasts play a key role in inducing faster and more robust SCLC cell regrowth in the model. This was a paracrine effect as conditioned medium from the same fibroblasts was responsible for this accelerated cell regrowth. This model is also amenable to high throughput phenotypic or targeted drug screening to find new therapeutics for SCLC.

Most early breast precancer lesions, termed ductal carcinoma in situ (DCIS), contain microcalcifications (MCs), which are calcium-containing pathological minerals. The most common type of MCs is calcium phosphate crystals, mainly carbonated apatite; it is associated with either benign or malignant lesions. In-vitro studies indicate that the crystal properties of apatite MCs can affect breast cancer progression. A less common type of MCs is calcium oxalate dihydrate (COD), which is almost always found in benign lesions. We developed a 3D tumor model of multicellular spheroids of human precancer cells containing synthetic MC analogs that link the crystal properties of MCs with the progression of breast precancer to invasive cancer. We show that apatite crystals induce proliferation and Her2 overexpression in DCIS cells. This tumor-triggering effect is increased when the carbonate fraction in the MCs decreases. COD crystals, in contrast, do not induce proliferation and reduce Her2 expression, even compared with control spheroids with no added MC analogs. This finding suggests that COD is not randomly located only in benign lesions--it may actively contribute to suppressing precancer progression in its surroundings. Our model provides an easy-to-manipulate platform to better understand the interactions between breast precancer cells and MCs. A better understanding of the effect of the crystal properties of MCs on precancer progression will potentially provide new directions for better precancer prognosis and treatment.

IntroductionCancer progression is driven not only by tumor cells but also by interactions between the extracellular matrix (ECM), stromal cells, and immune cells within the tumor microenvironment (TME). Cancer-associated fibroblasts (CAFs) are major drivers of ECM remodeling, assembling ECM with aberrant organization. Extra domain A fibronectin (EDA-FN), a cellular FN containing an extra type III domain, is upregulated in the TME. EDA-FN regulates cellular behavior and has been associated with poor patient prognosis. Macrophages are among the most abundant immune cells within the TME, where they contribute to TME remodeling and inflammation to promote cancer cell invasion and metastasis. However, how tumor-associated matrix-specific cues regulate macrophage behavior remains largely understudied. PurposeHere, we developed a fibroblast-derived matrix platform that captures the structural imprint of tumor-associated EDA-enriched matrices and investigated how matrix-specific cues regulate macrophage behavior in the absence of ongoing soluble factor cues. MethodHuman mammary fibroblasts (HMFs) preconditioned in incubated low-serum media (lNC, or control) and MDA-MB231 metastatic breast cancer cell-conditioned media (mTCM) were cultured on polyacrylamide gels of 2 kPa and 20 kPa, respectively, followed by decellularization. Matrix organization, including fiber alignment, width, and intrafibrillar spacing, was quantified from confocal images. Decellularized EDA-FN-enriched matrices were subsequently reseeded with macrophages to assess macrophage morphology, phenotype, and matrix interactions. ResultsThe combined effects of tumor-derived soluble factors and pathological stiffness induced a CAF-like phenotype in HMFs, accompanied by cytoskeletal reorganization and microarchitectural alterations of EDA-FN-enriched matrices. Tumor-associated matrices exhibited increased alignment, narrower fiber width, and enlarged intrafibrillar spacing compared to control matrices. These aberrant, tumor-associated matrix-derived features were associated with altered macrophage behavior, including heterogeneous morphology, enhanced localized EDA-FN matrix loss beneath the cell body, and a hybrid phenotype with a shift toward a CD206-dominant profile. ConclusionsThese findings demonstrate the feasibility of obtaining EDA-FN-enriched matrices to isolate matrix-specific cues for investigating macrophage-ECM interactions. Furthermore, this platform can be leveraged to identify matrix-targeting therapeutic approaches for modulating macrophage function within the TME.