Back to the Future: Spatiotemporal Determinants of NK Cell Antitumor Function

NK cells play a crucial role in host protection during tumorigenesis. Throughout tumor development, however, NK cells become progressively dysfunctional through a combination of dynamic tissue-specific and systemic factors. While a number of immunosuppressive mechanisms present within the tumor microenvironment have been characterized, few studies have contextualized the spatiotemporal dynamics of these mechanisms during disease progression and across anatomical sites. Understanding how NK cell immunosuppression evolves in these contexts will be necessary to optimize NK cell therapy for solid and metastatic cancers. Here, we outline the spatiotemporal determinants of antitumor NK cell regulation, including heterogeneous tumor architecture, temporal disease states, diverse cellular communities, as well as the complex changes in NK cell states produced by the sum of these higher-order elements. Understanding of the signals encountered by NK cells across time and space may reveal new therapeutic targets to harness the full potential of NK cell therapy for cancer.

Butyrate and Metformin Affect Energy Metabolism Independently of the Metabolic Phenotype in the Tumor Therapy Model

The BALB/c cell transformation assay (BALB-CTA) considers inter- and intra-tumor heterogeneities and affords the possibility of a direct comparison between untransformed and malignant cells. In the present study, we established monoclonal cell lines that originate from the BALB-CTA and mimic heterogeneous tumor cell populations, in order to investigate phenotype-specific effects of the anti-diabetic drug metformin and the short-chain fatty acid butyrate. Growth inhibitory effects were measured with a ViCell XR cell counter. The BALB/c tumor therapy model (BALB-TTM) was performed, and the extracellular glucose level was measured in the medium supernatant. Using a Seahorse Analyzer, the metabolic phenotypes of four selected clones were characterized, and effects on energy metabolism were investigated. Anti-carcinogenic effects and reduced glucose uptake after butyrate application were observed in the BALB-TTM. Metabolic characterization of the cell clones revealed three different phenotypes. Surprisingly, treatment with metformin or butyrate induced opposite metabolic shifts with similar patterns in all cell clones tested. In conclusion, the BALB-TTM is a relevant model for mechanistic cancer research, and the generation of monoclonal cell lines offers a novel possibility to investigate specific drug effects in a heterogeneous tumor cell population. The results indicate that induced alterations in energy metabolism seem to be independent of the original metabolic phenotype.

Radiomic Analysis of the Heterogeneous Tumor and Surrounding Parenchyma Based on DCE-MRI Decomposition to Predict HER2 Expression in Breast Cancer

Background Human epidermal growth factor receptor-2 (HER2) correlates with cancer heterogeneity, and the identification of HER2 expression is invasive immunohistochemistry in the clinic. To determine whether noninvasive predictors of HER2 expression are implied in the dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI).Methods 189/47 breast cancer patients collected from The Cancer Imaging Archive (TCIA) were used as a cross-validation/test group. A convex analysis of mixtures (CAM) was conducted to decompose heterogeneous tissues inside and outside the tumor. Their DCE-MRI images were decomposed into relatively homogeneous subregions with different contrast enhancement patterns. The predictor of HER2 expression was composed of radiomic features acquired from intratumoural or peritumoural subregions. The area under the curve (AUC) of receiver operating characteristic (ROC) was used to assess the predictive power.Results The predictor formed in the undecomposed tumor was used as a baseline for comparison (AUC=0.691±0.072/0.625±0.056 in cross-validation/test group). The intratumoural subregion with a contrast enhancement pattern corresponding to the plateau of signal intensity formed a more robust predictor (AUC=0.816±0.059/0.785±0.067, P=0.0128/0.0389). Peritumoral parenchyma of <20 mm from the tumor margin was also researched (AUC=0.589±0.083/0.524±0.064). The peritumoural subregion with a contrast enhancement pattern corresponding to steady enhancement also formed a helpful predictor compared to the undecomposed parenchyma (AUC=0.702±0.068/0.681±0.042, P=0.0128/0.0389). The best predictor was formed when two predictors from subregions were fused together (AUC=0.851±0.057/0.812±0.045, P=0.0011/0.0397).Conclusions A subregion rather than a heterogeneous tumor itself provided a more accurate predictor of HER2 expression. Radiomic predictors from intratumoural and peritumoural subregions were complementary to each other.

Construction of enzalutamide-resistant cell model of prostate cancer and preliminary screening of potential drug-resistant genes

Among many factors of causing castration-resistant prostate cancer (CRPC) progression, a growing number of evidences have shown androgen receptors play a critical role. Therefore, blocking androgen receptor remains a therapeutic goal of CRPC. However, resistance to androgen receptor inhibitors, for example, enzalutamide, limits therapeutic efficacy for many patients. In this study, to develop an enzalutamide-resistant cell model for molecular mechanism investigation of enzalutamide-resistance, we continuously treated C4-2B cells with multiplied concentrations of enzalutamide. The IC50 of resistant cells was identified as 14.7705 µM, and the resistance index was calculated as 12.4. In addition, we verified the resistance of resistant cells through experiments in vivo and found the genes in androgen receptor signaling pathway (androgen receptor, Jagged1, Notch1) and those in androgen receptor alternative signaling pathways behaved the opposite. For some of the former, their mRNA and protein expression reduced markedly while for the latter, for example, CXCR7, AKT, STAT3, FOXP3, they rose dramatically in the expression level of protein and mRNA. More importantly, the tumor volume, tumor wet weight, PSA and VEGF secretion level, positive staining rate of Ki67 nuclei in resistant strain heterogeneous tumor treated with enzalutamide were significantly higher than those of maternal cell heterogeneous tumor treated with enzalutamide, whereas no obvious difference was detected between resistant strain heterogeneous tumor treated with enzalutamide and those of the resistant strain treated with reference drug. Finally, we identified 654 differentially expression genes and 2 compounds (atracurium besilate, methotrexates) associated with the amelioration of enzalutamide-resistance. Overall, we successfully established an enzalutamide-resistance cell model and screened out some resistance genes and candidate small molecule drugs.

Optimizing proton minibeam radiotherapy by interlacing and heterogeneous tumor dose on the basis of calculated clonogenic cell survival

Proton minibeam radiotherapy (pMBRT) is a spatial fractionation method using sub-millimeter beams at center-to-center (ctc) distances of a few millimeters to widen the therapeutic index by reduction of side effects in normal tissues. Interlaced minibeams from two opposing or four orthogonal directions are calculated to minimize side effects. In particular, heterogeneous dose distributions applied to the tumor are investigated to evaluate optimized sparing capabilities of normal tissues at the close tumor surrounding. A 5 cm thick tumor is considered at 10 cm depth within a 25 cm thick water phantom. Pencil and planar minibeams are interlaced from two (opposing) directions as well as planar beams from four directions. An initial beam size of σ0 = 0.2 mm (standard deviation) is assumed in all cases. Tissue sparing potential is evaluated by calculating mean clonogenic cell survival using a linear-quadratic model on the calculated dose distributions. Interlacing proton minibeams for homogeneous irradiation of the tumor has only minor benefits for the mean clonogenic cell survival compared to unidirectional minibeam irradiation modes. Enhanced mean cell survival, however, is obtained when a heterogeneous dose distribution within the tumor is permitted. The benefits hold true even for an elevated mean tumor dose, which is necessary to avoid cold spots within the tumor in concerns of a prescribed dose. The heterogeneous irradiation of the tumor allows for larger ctc distances. Thus, a high mean cell survival of up to 47% is maintained even close to the tumor edges for single fraction doses in the tumor of at least 10 Gy. Similar benefits would result for heavy ion minibeams with the advantage of smaller minibeams in deep tissue potentially offering even increased tissue sparing. The enhanced mean clonogenic cell survival through large ctc distances for interlaced pMBRT with heterogeneous tumor dose distribution results in optimum tissue sparing potential. The calculations show the largest enhancement of the mean cell survival in normal tissue for high-dose fractions. Thus, hypo-fractionation or even single dose fractions become possible for tumor irradiation. A widened therapeutic index at big cost reductions is offered by interlaced proton or heavy ion minibeam therapy.

Response to Immune Checkpoint Inhibitors in Recurrent or Metastatic Esophageal Squamous Cell Carcinoma May Be Affected by Tumor Sites

<b><i>Introduction:</i></b> Heterogeneous tumor response has been reported in cancer patients treated with immune checkpoint inhibitors (ICIs). This study investigated whether the tumor site is associated with the response to ICIs in patients with recurrent or metastatic esophageal squamous cell carcinoma (ESCC). <b><i>Methods:</i></b> Patients with ESCC who had measurable tumors in the liver, lung, or lymph node (LN) according to the response evaluation criteria in solid tumors (RECIST) 1.1 and received ICIs at 2 medical centers in Taiwan were enrolled. In addition to RECIST 1.1, tumor responses were determined per individual organ basis according to organ-specific criteria modified from RECIST 1.1. Fisher test or χ² test was used for statistical analysis. <b><i>Results:</i></b> In total, 37 patients were enrolled. The overall response rate per RECIST 1.1 was 13.5%. Measurable tumors in the LN, lung, and liver were observed in 26, 17, and 13 patients, respectively. The organ-specific response rates were 26.9%, 29.4%, and 15.4% for the LN, lung, and liver tumors, respectively (<i>p</i> = 0.05). The organ-specific disease control rates were 69.2%, 52.9%, and 21.1% for the LN, lung, and liver tumors, respectively (<i>p</i> = 0.024). Five (27.8%) among 18 patients harboring at least 2 involved organs had heterogeneous tumor response. <b><i>Conclusion:</i></b> The response and disease control to ICIs may differ in ESCC tumors located at different metastatic sites, with a lesser likelihood of response and disease control in metastatic liver tumors than in tumors located at the LNs and lung.

A 3D printed in vitro bone model for the assessment of molecular and cellular cues in metastatic neuroblastoma

From PSc to CSc: modeling heterogeneous tumor microenvironments of the neuroblastoma bone metastatic niche.