MRI of the tumor microenvironment

A predictive model using MRI and clinicopathologic features for breast cancer recurrence in young women treated with upfront surgery

OBJECTIVES

To identify preoperative breast MR imaging and clinicopathological variables related to recurrence and develop a risk prediction model for recurrence in young women with breast cancer treated with upfront surgery.

METHODS

This retrospective study analyzed 438 consecutive women with breast cancer aged 35 years or younger between January 2007 and December 2016. Breast MR images before surgery were independently reviewed by breast radiologists blinded to patient outcomes. The clinicopathological data including patient demographics, clinical features, and tumor characteristics were reviewed. Univariate and multivariate logistic regression analyses were used to identify the independent factors associated with recurrence. The risk prediction model for recurrence was developed, and the discrimination and calibration abilities were assessed.

RESULTS

Of 438 patients, 95 (21.7%) developed recurrence after a median follow-up of 65 months. Tumor size at MR imaging (HR = 1.158, p = 0.006), multifocal or multicentric disease (HR = 1.676, p = 0.017), and peritumoral edema on T2WI (HR = 2.166, p = 0.001) were identified as independent predictors of recurrence, while adjuvant endocrine therapy (HR = 0.624, p = 0.035) was inversely associated with recurrence. The prediction model showed good discrimination ability in predicting 5-year recurrence (C index, 0.707 in the development cohort; 0.686 in the validation cohort) and overall recurrence (C index, 0.699 in the development cohort; 0.678 in the validation cohort). The calibration plot demonstrated an excellent correlation (concordance correlation coefficient, 0.903).

CONCLUSION

A prediction model based on breast MR imaging and clinicopathological features showed good discrimination to predict recurrence in young women with breast cancer treated with upfront surgery, which could contribute to individualized risk stratification.

CLINICAL RELEVANCE STATEMENT

Our prediction model, incorporating preoperative breast MR imaging and clinicopathological features, predicts recurrence in young women with breast cancer undergoing upfront surgery, facilitating personalized risk stratification and informing tailored management strategies.

KEY POINTS

Younger women with breast cancer have worse outcomes than those diagnosed at more typical ages. The described prediction model showed good discrimination performance in predicting 5-year and overall recurrence. Incorporating better risk stratification tools in this population may help improve outcomes.

Mitochondrial-Stem Cell Connection: Providing Additional Explanations for Understanding Cancer

The cancer paradigm is generally based on the somatic mutation model, asserting that cancer is a disease of genetic origin. The mitochondrial-stem cell connection (MSCC) proposes that tumorigenesis may result from an alteration of the mitochondria, specifically a chronic oxidative phosphorylation (OxPhos) insufficiency in stem cells, which forms cancer stem cells (CSCs) and leads to malignancy. Reviewed evidence suggests that the MSCC could provide a comprehensive understanding of all the different stages of cancer. The metabolism of cancer cells is altered (OxPhos insufficiency) and must be compensated by using the glycolysis and the glutaminolysis pathways, which are essential to their growth. The altered mitochondria regulate the tumor microenvironment, which is also necessary for cancer evolution. Therefore, the MSCC could help improve our understanding of tumorigenesis, metastases, the efficiency of standard treatments, and relapses.

pH-regulated single cell migration

Over the last two decades, extra- and intracellular pH have emerged as fundamental regulators of cell motility. Fundamental physiological and pathological processes relying on appropriate cell migration, such as embryonic development, wound healing, and a proper immune defense on the one hand, and autoimmune diseases, metastatic cancer, and the progression of certain parasitic diseases on the other, depend on surrounding pH. In addition, migrating single cells create their own localized pH nanodomains at their surface and in the cytosol. By this means, the migrating cells locally modulate their adhesion to, and the re-arrangement and digestion of, the extracellular matrix. At the same time, the cytosolic nanodomains tune cytoskeletal dynamics along the direction of movement resulting in concerted lamellipodia protrusion and rear end retraction. Extracellular pH gradients as found in wounds, inflamed tissues, or the periphery of tumors stimulate directed cell migration, and long-term exposure to acidic conditions can engender a more migratory and invasive phenotype persisting for hours up to several generations of cells after they have left the acidic milieu. In the present review, the different variants of pH-dependent single cell migration are described. The underlying pH-dependent molecular mechanisms such as conformational changes of adhesion molecules, matrix protease activity, actin (de-)polymerization, and signaling events are explained, and molecular pH sensors stimulated by H+ signaling are presented.

On the Importance of Acidity in Cancer Cells and Therapy

Cancer cells are associated with high glycolytic activity, which results in acidification of the tumor microenvironment. The occurrence of this stressful condition fosters tumor aggressiveness, with the outcome of invasiveness and metastasis that are linked to a poor clinical prognosis. Acidosis can be both the cause or consequence of alterations in the functions and expressions of transporters involved in intracellular acidity regulation. This review aims to explore the origin of acidity in cancer cells and the various mechanisms existing in tumors to resist, survive, or thrive in the acidic environment. It highlights the difficulties in measuring the intracellular pH evolution that impedes our understanding of the many regulatory and feedback mechanisms. It finally presents the consequences of acidity on tumor development as well as the friend or foe role of acidity in therapy.

Predicting pathological complete response to neoadjuvant chemotherapy in breast cancer patients: use of MRI radiomics data from three regions with multiple machine learning algorithms

OBJECTIVE

To construct a multi-region MRI radiomics model for predicting pathological complete response (pCR) in breast cancer (BCa) patients who received neoadjuvant chemotherapy (NACT) and provide a theoretical basis for the peritumoral microenvironment affecting the efficacy of NACT.

METHODS

A total of 133 BCa patients who received NACT, including 49 with confirmed pCR, were retrospectively analyzed. The radiomics features of the intratumoral region, peritumoral region, and background parenchymal enhancement (BPE) were extracted, and the most relevant features were obtained after dimensional reduction. Then, combining different areas, multivariate logistic regression analysis was used to select the optimal feature set, and six different machine learning models were used to predict pCR. The optimal model was selected, and its performance was evaluated using receiver operating characteristic (ROC) analysis. SHAP analysis was used to examine the relationship between the features of the model and pCR.

RESULTS

For signatures constructed using three individual regions, BPE provided the best predictions of pCR, and the diagnostic performance of the intratumoral and peritumoral regions improved after adding the BPE signature. The radiomics signature from the combination of all the three regions with the XGBoost machine learning algorithm provided the best predictions of pCR based on AUC (training set: 0.891, validation set: 0.861), sensitivity (training set: 0.882, validation set: 0.800), and specificity (training set: 0.847, validation set: 0.84). SHAP analysis demonstrated that LZ_log.sigma.2.0.mm.3D_glcm_ClusterShade_T12 made the greatest contribution to the predictions of this model.

CONCLUSION

The addition of the BPE MRI signature improved the prediction of pCR in BCa patients who received NACT. These results suggest that the features of the peritumoral microenvironment are related to the efficacy of NACT.

Utility of 1.5 Tesla MRI Scanner in the Management of Small Sample Sizes Driven from 3D Breast Cell Culture

The aim of this work was to use and optimize a 1.5 Tesla magnetic resonance imaging (MRI) system for three-dimensional (3D) images of small samples obtained from breast cell cultures in vitro. The basis of this study was to design MRI equipment to enable imaging of MCF-7 breast cancer cell cultures (about 1 million cells) in 1.5 and 2 mL glass tubes and/or bioreactors with an external diameter of less than 20 mm. Additionally, the development of software to calculate longitudinal and transverse relaxation times is described. Imaging tests were performed using a clinical MRI scanner OPTIMA 360 manufactured by GEMS. Due to the size of the tested objects, it was necessary to design additional receiving circuits allowing for the study of MCF-7 cell cultures placed in glass bioreactors. The examined sample's volume did not exceed 2.0 mL nor did the number of cells exceed 1 million. This work also included a modification of the sequence to allow for the analysis of T1 and T2 relaxation times. The analysis was performed using the MATLAB package (produced by MathWorks). The created application is based on medical MR images saved in the DICOM3.0 standard which ensures that the data analyzed are reliable and unchangeable in an unintentional manner that could affect the measurement results. The possibility of using 1.5 T MRI systems for cell culture research providing quantitative information from in vitro studies was realized. The scanning resolution for FOV = 5 cm and the matrix was achieved at a level of resolution of less than 0.1 mm/pixel. Receiving elements were built allowing for the acquisition of data for MRI image reconstruction confirmed by images of a phantom with a known structure and geometry. Magnetic resonance sequences were modified for the saturation recovery (SR) method, the purpose of which was to determine relaxation times. An application in MATLAB was developed that allows for the analysis of T1 and T2 relaxation times. The relaxation times of cell cultures were determined over a 6-week period. In the first week, the T1 time value was 1100 ± 40 ms, which decreased to 673 ± 59 ms by the sixth week. For T2, the results were 171 ± 10 ms and 128 ± 12 ms, respectively.

Severely polarized extracellular acidity around tumour cells

Extracellular pH impacts many molecular, cellular and physiological processes, and hence is tightly regulated. Yet, in tumours, dysregulated cancer cell metabolism and poor vascular perfusion cause the tumour microenvironment to become acidic. Here by leveraging fluorescent pH nanoprobes with a transistor-like activation profile at a pH of 5.3, we show that, in cancer cells, hydronium ions are excreted into a small extracellular region. Such severely polarized acidity (pH <5.3) is primarily caused by the directional co-export of protons and lactate, as we show for a diverse panel of cancer cell types via the genetic knockout or inhibition of monocarboxylate transporters, and also via nanoprobe activation in multiple tumour models in mice. We also observed that such spot acidification in ex vivo stained snap-frozen human squamous cell carcinoma tissue correlated with the expression of monocarboxylate transporters and with the exclusion of cytotoxic T cells. Severely spatially polarized tumour acidity could be leveraged for cancer diagnosis and therapy.

Excited state properties of 5-fluoro-4-thiouridine derivative†

The excited state properties of thionated 5-fluorouridine (2',3',5'-tri-O-acetyl-5-fluoro-4-thiouridine; ta5F4TUrd), synthesized with Lawesson's reagent, have been intensively investigated with nanosecond transient absorption spectroscopy, time-resolved thermal lensing, near-infrared emission, and quantum chemical calculation. The intrinsic triplet lifetime of ta5F4TUrd was determined to be4.2 ± 0.7 μs in acetonitrile, and the formation quantum yield of the excited triplet state was as large as0.79 ± 0.01 . The quenching rate constants of the triplet ta5F4TUrd by the dissolved oxygen molecule and by the self-quenching process were found to be nearly equal to the diffusion-controlled rate of acetonitrile. The quantum yield of the singlet molecular oxygen produced through energy transfer between the triplet ta5F4TUrd and the dissolved oxygen,Φ Δ , was successfully determined to be0.61 ± 0.02 under the oxygen-saturated condition. From the oxygen concentration dependence of theΦ Δ value, the fraction of triplet ta5F4TUrd quenched by dissolved oxygen which gives rise to the 1 O2 * formation,S Δ , was successfully obtained to be0.78 ± 0.01 , which was the largest among the thionucleobases and the thionucleosides reported so far. This could be due to the lower energy and/or the ππ* character of the triplet state.

Evaluation of the Prognostic Value of Pretherapeutic Magnetic Resonance Imaging in Predicting Soft Tissue Sarcoma Radiation Response: A Retrospective Study from a Large Institutional Sarcoma Imaging Database

Background: RT-induced hyalinization/fibrosis was recently evidenced as a significant independent predictor for complete response to neoadjuvant radiotherapy (RT) and survival in patients with soft tissue sarcoma (STS). Purpose: Non-invasive predictive markers of histologic response after neoadjuvant RT of STS are expected. Materials and Methods: From May 2010 to April 2017, patients with a diagnosis of STS who underwent neoadjuvant RT for limb STS were retrieved from a single center prospective clinical imaging database. Tumor Apparent Diffusion Coefficients (ADC) and areas under the time-intensity perfusion curve (AUC) were compared with the histologic necrosis ratio, fibrosis, and cellularity in post-surgical specimens. Results: We retrieved 29 patients. The median ADC value was 134.3 × 10-3 mm2/s. ADC values positively correlated with the post-treatment tumor necrosis ratio (p = 0.013). Median ADC values were lower in patients with less than 50% necrosis and higher in those with more than 50% (120.3 × 10-3 mm2/s and 202.0 × 10-3 mm2/s, respectively (p = 0.020). ADC values higher than 161 × 10-3 mm2/s presented a 95% sensitivity and a 55% specificity for the identification of tumors with more than 50% tumor necrosis ratio. Tumor-to-muscle AUC ratios were associated with histologic fibrosis (p = 0.036). Conclusions: ADC and perfusion AUC correlated, respectively, with radiation-induced tumor necrosis and fibrosis.

Chemical Reactions in Living Systems

The term "in vivo ("in the living") chemistry" refers to chemical reactions that take place in a complex living system such as cells, tissue, body liquids, or even in an entire organism. In contrast, reactions that occur generally outside living organisms in an artificial environment (e.g., in a test tube) are referred to as in vitro. Over the past decades, significant contributions have been made in this rapidly growing field of in vivo chemistry, but it is still not fully understood, which transformations proceed efficiently without the formation of by-products or how product formation in such complex environments can be characterized. Potential applications can be imagined that synthesize drug molecules directly within the cell or confer new cellular functions through controlled chemical transformations that will improve the understanding of living systems and develop new therapeutic strategies. The guiding principles of this contribution are twofold: 1) Which chemical reactions can be translated from the laboratory to the living system? 2) Which characterization methods are suitable for studying reactions and structure formation in complex living environments?

The Value of Amide Proton Transfer MRI in the Diagnosis of Malignant and Benign Urinary Bladder Lesions: Comparison With Diffusion-Weighted Imaging

BACKGROUND

Conventional magnetic resonance imaging (MRI) has certain limitations in distinguishing between malignant and benign urinary bladder (UB) lesions. Amide proton transfer (APT) imaging may provide more diagnostic information than diffusion-weighted imaging (DWI) to distinguish between malignant and benign UB.

PURPOSE

To investigate the potential of APT imaging in the diagnosis of malignant and benign UB lesions and to compare its diagnostic efficacy with that of conventional DWI.

STUDY TYPE

Prospective.

SUBJECTS

Eighty patients with UB lesions.

FIELD STRENGTH/SEQUENCE

A 3.0 T/turbo spin echo (TSE) T1-weighted and T2-weighted imaging, single-shot echo planar DWI, and three-dimensional TSE APT imaging.

ASSESSMENT

Patients underwent radical cystectomy or transurethral resection of the bladder lesions within 2 weeks after CT urography and MRI examination. APT signal intensity in UB lesions was quantified by the asymmetric magnetization transfer ratio (MTRasym ). MTRasym and apparent diffusion coefficient (ADC) values were measured and compared between malignant and benign UB lesions.

STATISTICAL TESTS

Kolmogorov-Smirnov test, Student's t test or Mann-Whitney U test, Spearman rank correlation coefficient, area under the receiver operating characteristic (ROC) curve (AUC), Delong test, and intraclass correlation coefficient (ICC). The significance threshold was set at P < 0.05.

RESULTS

Thirty-two patients had pathologically confirmed benign UB lesions, including 2 bladder leiomyomas, 1 submucosal amyloidosis, 1 inflammatory myofibroblastic tumor, and 28 inflammatory lesions, and 48 patients had pathologically confirmed urothelial carcinoma. Urothelial carcinomas showed significantly higher MTRasym values (1.53% [0.74%] vs. 0.85% [0.23%]) and significantly lower ADC values (1.24 ± 0.34 × 10-3  mm2 /s vs. 1.43 ± 0.22 × 10-3  mm2 /s) than benign UB lesions. The MTRasym value (AUC = 0.928) was significantly better in differentiating urothelial carcinoma from benign UB lesions than the ADC value (AUC = 0.722).

DATA CONCLUSION

APT imaging may have value in discriminating malignant from benign UB lesions and has better diagnostic performance than DWI.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY: Stage 2.

Potential of Alkalization Therapy for the Management of Metastatic Pancreatic Cancer: A Retrospective Study

Current treatments for patients with pancreatic cancer offer limited benefits. In this study, we applied alkalization therapy, which was efficacious for other solid tumors at our clinic, to stage 4 pancreatic cancer patients, and investigated its effect on disease prognosis. Patients with metastatic pancreatic cancer who were treated at Karasuma Wada Clinic in Kyoto, Japan, between January 2011 and April 2022, were included in the study. All patients received alkalization therapy (a combination of an alkaline diet, bicarbonate, and citric acid administration), alongside standard chemotherapy. Urine samples were collected to assess urine pH as a marker of whole-body alkalization. In the 98 patients analyzed, the median overall survival (OS) from the time of diagnosis was 13.2 months. Patients with a mean urine pH of 7.5 or greater had a median OS of 29.9 months, compared with 15.2 months for those with a mean urine pH of 6.5 to 7.5, and 8.0 months for those with a mean urine pH of less than 6.5, which suggests a trend of a longer OS in patients with a higher urine pH (p = 0.0639). Alkalization therapy may offer a viable approach to extending the survival of stage 4 pancreatic cancer patients, who typically have an unfavorable prognosis.

Longitudinal dynamic contrast-enhanced MRI radiomic models for early prediction of response to neoadjuvant systemic therapy in triple-negative breast cancer

Early prediction of neoadjuvant systemic therapy (NAST) response for triple-negative breast cancer (TNBC) patients could help oncologists select individualized treatment and avoid toxic effects associated with ineffective therapy in patients unlikely to achieve pathologic complete response (pCR). The objective of this study is to evaluate the performance of radiomic features of the peritumoral and tumoral regions from dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) acquired at different time points of NAST for early treatment response prediction in TNBC. This study included 163 Stage I-III patients with TNBC undergoing NAST as part of a prospective clinical trial (NCT02276443). Peritumoral and tumoral regions of interest were segmented on DCE images at baseline (BL) and after two (C2) and four (C4) cycles of NAST. Ten first-order (FO) radiomic features and 300 gray-level-co-occurrence matrix (GLCM) features were calculated. Area under the receiver operating characteristic curve (AUC) and Wilcoxon rank sum test were used to determine the most predictive features. Multivariate logistic regression models were used for performance assessment. Pearson correlation was used to assess intrareader and interreader variability. Seventy-eight patients (48%) had pCR (52 training, 26 testing), and 85 (52%) had non-pCR (57 training, 28 testing). Forty-six radiomic features had AUC at least 0.70, and 13 multivariate models had AUC at least 0.75 for training and testing sets. The Pearson correlation showed significant correlation between readers. In conclusion, Radiomic features from DCE-MRI are useful for differentiating pCR and non-pCR. Similarly, predictive radiomic models based on these features can improve early noninvasive treatment response prediction in TNBC patients undergoing NAST.

Molecular Basis for Mambalgin-2 Interaction with Heterotrimeric α-ENaC/ASIC1a/γ-ENaC Channels in Cancer Cells

Cancer progression is characterized by microenvironmental acidification. Tumor cells adapt to low environmental pH by activating acid-sensing trimeric ion channels of the DEG/ENaC family. The α-ENaC/ASIC1a/γ-ENaC heterotrimeric channel is a tumor-specific acid-sensing channel, and its targeting can be considered a new strategy for cancer therapy. Mambalgin-2 from the Dendroaspis polylepis venom inhibits the α-ENaC/ASIC1a/γ-ENaC heterotrimer more effectively than the homotrimeric ASIC1a channel, initially proposed as the target of mambalgin-2. Although the molecular basis of such mambalgin selectivity remained unclear. Here, we built the models of the complexes of mambalgin-2 with the α-ENaC/ASIC1a/γ-ENaC and ASIC1a channels, performed MD and predicted the difference in the binding modes. The importance of the 'head' loop region of mambalgin-2 for the interaction with the hetero-, but not with the homotrimeric channel was confirmed by site-directed mutagenesis and electrophysiology. A new mode of allosteric regulation of the ENaC channels by linking the thumb domain of the ASIC1a subunit with the palm domain of the γ-ENaC subunit was proposed. The data obtained provide new insights into the regulation of various types of acid-sensing ion channels and the development of new strategies for cancer treatment.

Characterization of the Intracellular Acidity Regulation of Brain Tumor Cells and Consequences for Therapeutic Optimization of Temozolomide

A well-known feature of tumor cells is high glycolytic activity, leading to acidification of the tumor microenvironment through extensive lactate production. This acidosis promotes processes such as metastasis, aggressiveness, and invasiveness, which have been associated with a worse clinical prognosis. Moreover, the function and expression of transporters involved in regulation of intracellular pH might be altered. In this study, the capacity of tumor cells to regulate their intracellular pH when exposed to a range of pH from very acidic to basic was characterized in two glioma cell lines (F98 and U87) using a new recently published method of fluorescence imaging. Our results show that the regulation of acidity in tumors is not the same for the two investigated cell lines; U87 cells are able to reduce their intracellular acidity, whereas F98 cells do not exhibit this property. On the other hand, F98 cells show a higher level of resistance to acidity than U87 cells. Intracellular regulation of acidity appears to be highly cell-dependent, with different mechanisms activated to preserve cell integrity and function. This characterization was performed on 2D monolayer cultures and 3D spheroids. Spatial heterogeneities were exhibited in 3D, suggesting a spatially modulated regulation in this context. Based on the corpus of knowledge available in the literature, we propose plausible mechanisms to interpret our results, together with some new lines of investigation to validate our hypotheses. Our results might have implications on therapy, since the activity of temozolomide is highly pH-dependent. We show that the drug efficiency can be enhanced, depending on the cell type, by manipulating the extracellular pH. Therefore, personalized treatment involving a combination of temozolomide and pH-regulating agents can be considered.

Conditionally Active, pH-Sensitive Immunoregulatory Antibodies Targeting VISTA and CTLA-4 Lead an Emerging Class of Cancer Therapeutics

Immune checkpoints and other immunoregulatory targets can be difficult to precisely target due to expression on non-tumor immune cells critical to maintaining immune homeostasis in healthy tissues. On-target/off-tumor binding of therapeutics results in significant pharmacokinetic and pharmacodynamic problems. Target-mediated drug disposition (TMDD) significantly limits effective intratumoral drug levels and adversely affects anti-tumor efficacy. Target engagement outside the tumor environment may lead to severe immune-related adverse events (irAEs), resulting in a narrowing of the therapeutic window, sub-optimal dosing, or cessation of drug development altogether. Overcoming these challenges has become tractable through recent advances in antibody engineering and screening approaches. Here, we review the discovery and development of conditionally active antibodies with minimal binding to target at physiologic pH but high-affinity target binding at the low pH of the tumor microenvironment by focusing on the discovery and improved properties of pH-dependent mAbs targeting two T cell checkpoints, VISTA and CTLA-4.

Acid-adapted cancer cells alkalinize their cytoplasm by degrading the acid-loading membrane transporter anion exchanger 2, SLC4A2

Acidic environments reduce the intracellular pH (pHi) of most cells to levels that are sub-optimal for growth and cellular functions. Yet, cancers maintain an alkaline cytoplasm despite low extracellular pH (pHe). Raised pHi is thought to be beneficial for tumor progression and invasiveness. However, the transport mechanisms underpinning this adaptation have not been studied systematically. Here, we characterize the pHe-pHi relationship in 66 colorectal cancer cell lines and identify the acid-loading anion exchanger 2 (AE2, SLC4A2) as a regulator of resting pHi. Cells adapt to chronic extracellular acidosis by degrading AE2 protein, which raises pHi and reduces acid sensitivity of growth. Acidity inhibits mTOR signaling, which stimulates lysosomal function and AE2 degradation, a process reversed by bafilomycin A1. We identify AE2 degradation as a mechanism for maintaining a conducive pHi in tumors. As an adaptive mechanism, inhibiting lysosomal degradation of AE2 is a potential therapeutic target.

A snapshot of the vast array of diamagnetic CEST MRI contrast agents

Since the inception of CEST MRI in the 1990s, a number of compounds have been identified as suitable for generating contrast, including paramagnetic lanthanide complexes, hyperpolarized atom cages and, most interesting, diamagnetic compounds. In the past two decades, there has been a major emphasis in this field on the identification and application of diamagnetic compounds that have suitable biosafety profiles for usage in medical applications. Even in the past five years there has been a tremendous growth in their numbers, with more and more emphasis being placed on finding those that can be ultimately used for patient studies on clinical 3 T scanners. At this point, a number of endogenous compounds present in tissue have been identified, and also natural and synthetic organic compounds that can be administered to highlight pathology via CEST imaging. Here we will provide a very extensive snapshot of the types of diamagnetic compound that can generate CEST MRI contrast, together with guidance on their utility on typical preclinical and clinical scanners and a review of the applications that might benefit the most from this new technology.

Effects of alkalization therapy on hepatocellular carcinoma: a retrospective study

Background

In hepatocellular carcinoma (HCC) patients, is difficult to prevent recurrence even when remission is achieved. In addition, even with the advent of drugs that are effective for the treatment of HCC, a satisfactory extension of patient survival has not been achieved. To overcome this situation, we hypothesized that the combination of alkalization therapy with standard treatments will improve the prognosis of HCC. We here report the clinical results of HCC patients treated with alkalization therapy at our clinic.

Patients and methods

Patients with HCC treated at Karasuma Wada Clinic (in Kyoto, Japan), from January 1, 2013, to December 31, 2020 were analyzed. Overall survival (OS) from both the time of diagnosis and the start of alkalization therapy for each patient was compared. The mean urine pH was also calculated as a surrogate marker of tumor microenvironment pH, and OS from the start of alkalization therapy was compared between patients with a mean urine pH of ≥ 7.0 and those with a mean urine pH of < 7.0.

Results

Twenty-three men and six women were included in the analysis, with a mean age at diagnosis of 64.1 years (range: 37-87 years). Seven of the 29 patients had extrahepatic metastases. Patients were divided into two groups according to their mean urine pH after the initiation of alkalization therapy: 12 of the 29 patients had a mean urine pH of ≥ 7.0, and 17 had a mean urine pH of < 7.0. The median OS from diagnosis was 95.6 months (95% confidence interval [CI] = 24.7-not reached), and from the start of alkalization therapy was 42.3 months (95% CI = 8.93-not reached). The median OS from the start of alkalization therapy in patients with a urine pH of ≥ 7.0 was not reached (n = 12, 95% CI = 3.0-not reached), which was significantly longer than that in patients with a pH of < 7.0 (15.4 months, n = 17, 95% CI = 5.8-not reached, p < 0.05).

Conclusions

The addition of alkalization therapy to standard therapies may be associated with more favorable outcomes in HCC patients with increased urine pH after alkalization therapy.

Label-Free Chemically and Molecularly Selective Magnetic Resonance Imaging

Biomedical imaging, especially molecular imaging, has been a driving force in scientific discovery, technological innovation, and precision medicine in the past two decades. While substantial advances and discoveries in chemical biology have been made to develop molecular imaging probes and tracers, translating these exogenous agents to clinical application in precision medicine is a major challenge. Among the clinically accepted imaging modalities, magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) exemplify the most effective and robust biomedical imaging tools. Both MRI and MRS enable a broad range of chemical, biological and clinical applications from determining molecular structures in biochemical analysis to imaging diagnosis and characterization of many diseases and image-guided interventions. Using chemical, biological, and nuclear magnetic resonance properties of specific endogenous metabolites and native MRI contrast-enhancing biomolecules, label-free molecular and cellular imaging with MRI can be achieved in biomedical research and clinical management of patients with various diseases. This review article outlines the chemical and biological bases of several label-free chemically and molecularly selective MRI and MRS methods that have been applied in imaging biomarker discovery, preclinical investigation, and image-guided clinical management. Examples are provided to demonstrate strategies for using endogenous probes to report the molecular, metabolic, physiological, and functional events and processes in living systems, including patients. Future perspectives on label-free molecular MRI and its challenges as well as potential solutions, including the use of rational design and engineered approaches to develop chemical and biological imaging probes to facilitate or combine with label-free molecular MRI, are discussed.

Delivery of Chemotherapy Agents and Nucleic Acids with pH-Dependent Nanoparticles

With less than one percent of systemically injected nanoparticles accumulating in tumors, several novel approaches have been spurred to direct and release the therapy in or near tumors. One such approach depends on the acidic pH of the extracellular matrix and endosomes of the tumor. With an average pH of 6.8, the extracellular tumor matrix provides a gradient for pH-responsive particles to accumulate, enabling greater specificity. Upon uptake by tumor cells, nanoparticles are further exposed to lower pHs, reaching a pH of 5 in late endosomes. Based on these two acidic environments in the tumor, various pH-dependent targeting strategies have been employed to release chemotherapy or the combination of chemotherapy and nucleic acids from macromolecules such as the keratin protein or polymeric nanoparticles. We will review these release strategies, including pH-sensitive linkages between the carrier and hydrophobic chemotherapy agent, the protonation and disruption of polymeric nanoparticles, an amalgam of these first two approaches, and the release of polymers shielding drug-loaded nanoparticles. While several pH-sensitive strategies have demonstrated marked antitumor efficacy in preclinical trials, many studies are early in their development with several obstacles that may limit their clinical use.

Profiling of immune responses by lactate modulation in cervical cancer reveals key features driving clinical outcome

Cervical cancer is still an important problem perplexing health management in developing countries. Previous studies have shown that cervical cancer cells show markers of aerobic glycolysis, suggesting that these tumors may secrete lactic acid. Through the biological characterization of lactate gene in tumor and its relationship with immune cells in tumor microenvironment, a lactate scoring system capable of evaluating cancer prognosis was constructed to explore the molecular mechanism of lactate metabolism disorder affecting prognosis. 29 hub genes in this study were differentially expressed in cervical cancer, including 24 genes related to lactate metabolism, LDHA in Lactate dehydrogenase (LDH) group, SLC16A3 in Monocarboxylate transporters (MCT) group and three Histone lactation modification related genes (EP300, ACAT1, ACACA). More importantly, we found that from an epigenetic point of view, histone lactation plays an important role in the pathogenesis and prognosis of cervical cancer. Mainly affect the prognosis of the disease through changes in the infiltration of plasmacytoid Dendritic Cell (pDC) and Central Memory T cell (Tcm) in the tumor immune microenvironment. Lactate inhibition may be a useful tool for anticancer therapy.

How Warburg-Associated Lactic Acidosis Rewires Cancer Cell Energy Metabolism to Resist Glucose Deprivation

Lactic acidosis, a hallmark of solid tumour microenvironment, originates from lactate hyperproduction and its co-secretion with protons by cancer cells displaying the Warburg effect. Long considered a side effect of cancer metabolism, lactic acidosis is now known to play a major role in tumour physiology, aggressiveness and treatment efficiency. Growing evidence shows that it promotes cancer cell resistance to glucose deprivation, a common feature of tumours. Here we review the current understanding of how extracellular lactate and acidosis, acting as a combination of enzymatic inhibitors, signal, and nutrient, switch cancer cell metabolism from the Warburg effect to an oxidative metabolic phenotype, which allows cancer cells to withstand glucose deprivation, and makes lactic acidosis a promising anticancer target. We also discuss how the evidence about lactic acidosis' effect could be integrated in the understanding of the whole-tumour metabolism and what perspectives it opens up for future research.

Acidity-mediated induction of FoxP3+ regulatory T cells

Glucose limitation and increased lactic acid levels are consequences of the elevated glycolytic activity of tumor cells, and constitute a metabolic barrier for the function of tumor infiltrating effector immune cells. The immune-suppressive functions of regulatory T cells (Tregs) are unobstructed in lactic-acid rich environments. However, the impact of lactic acid on the induction of Tregs remains unknown. We observed increased TGFβ-mediated induction of Forkhead box P3⁺ (FoxP3⁺ ) cells in the presence of extracellular lactic acid, in a glycolysis-independent, acidity-dependent manner. These CD4⁺ FoxP3⁺ cells expressed Treg-associated markers, including increased expression of CD39, and were capable of exerting suppressive functions. Corroborating these results in vivo, we observed that neutralizing the tumor pH by systemic administration of sodium bicarbonate (NaBi) decreased Treg abundance. We conclude that acidity augments Treg induction and propose that therapeutic targeting of acidity in the tumor microenvironment (TME) might reduce Treg-mediated immune suppression within tumors.

Recent Developments in the Study of the Microenvironment of Cancer and Drug Delivery

Cancer is characterized by disrupted molecular variables caused by cells that deviate from regular signal transduction. The uncontrolled segment of such cancerous cells annihilates most of the tissues that contact them. Gene therapy, immunotherapy, and nanotechnology advancements have resulted in novel strategies for anticancer drug delivery. Furthermore, diverse dispersion of nanoparticles in normal stroma cells adversely affects the healthy cells and disrupts the crosstalk of tumour stroma. It can contribute to cancer cell progression inhibition and, conversely, to acquired resistance, enabling cancer cell metastasis and proliferation. The tumour's microenvironment is critical in controlling the dispersion and physiological activities of nano-chemotherapeutics which is one of the targeted drug therapy. As it is one of the methods of treating cancer that involves the use of medications or other substances to specifically target and kill off certain subsets of malignant cells. A targeted therapy may be administered alone or in addition to more conventional methods of care like surgery, chemotherapy, or radiation treatment. The tumour microenvironment, stromatogenesis, barriers and advancement in the drug delivery system across tumour tissue are summarised in this review.

Evaluation of functional and metabolic tumor volume using voxel-wise analysis in childhood rhabdomyosarcoma

BACKGROUND

Cross-sectional imaging-based morphological characteristics of pediatric rhabdomyosarcoma have failed to predict outcomes.

OBJECTIVE

To evaluate the feasibility and possible value of generating tumor sub-volumes using voxel-wise analysis of metabolic and functional data from positron emission tomography/magnetic resonance imaging (PET/MR) or PET/computed tomography (CT) and MRI in rhabdomyosarcoma.

MATERIALS AND METHODS

Thirty-four examinations in 17 patients who received PET/MRI or PET/CT plus MRI were analyzed. The volume of interest included total tumor volume before and after therapy. Apparent diffusion coefficients (ADC) and standard uptake values (SUV) were determined voxel-wise. Voxels were assigned to three different groups based on ADC and SUV: "viable tumor tissue," "intermediate tissue" or "possible necrosis." In a second approach, data were grouped into three clusters using the Gaussian mixture model. The ratio of these clusters to total tumor volume and changes due to chemotherapy were correlated with clinical and histopathological data.

RESULTS

After chemotherapy, the proportion of voxels in the different groups changed significantly. A significant reduction of the proportion of voxels assigned to cluster 1 was found, from a mean of 36.4% to 2.5% (P < 0.001). There was a significant increase in the proportion of voxels in cluster 3 following chemotherapy from 24.8% to 81.6% (P = 0.02). The proportion of voxels in cluster 2 differed depending on the presence or absence of tumor recurrence, falling from 48% to 10% post-chemotherapy in the group with no tumor recurrence (P < 0.05) and from 29% to 23% (P > 0.05) in the group with tumor recurrence.

CONCLUSION

Voxel-wise evaluation of multimodal data in rhabdomyosarcoma is feasible. Our initial results suggest that the different distribution of sub-volumes before and after therapy may have prognostic significance.

Trimethine Cyanine Dyes as NA-Sensitive Probes for Visualization of Cell Compartments in Fluorescence Microscopy

We propose symmetrical cationic trimethine cyanine dyes with β-substituents in the polymethine chain based on modified benzothiazole and benzoxazole heterocycles as probes for the detection and visualization of live and fixed cells by fluorescence microscopy. The spectral-luminescent properties of trimethine cyanines have been characterized for free dyes and in the presence of nucleic acids (NA) and globular proteins. The studied cyanines are low to moderate fluorescent when free, but in the presence of NA, they show an increase in emission intensity up to 111 times; the most pronounced emission increase was observed for the dyes T-2 in the presence of dsDNA and T-1 with RNA. Spectral methods showed the binding of all dyes to nucleic acids, and different interaction mechanisms have been proposed. The ability to visualize cell components of the studied dyes has been evaluated using different human cell lines (MCF-7, A2780, HeLa, and Hs27). We have shown that all dyes are cell-permeant staining nucleus components, probably RNA-rich nucleoli with background fluorescence in the cytoplasm, except for the dye T-5. The dye T-5 selectively stains some structures in the cytoplasm of MCF-7 and A2780 cells associated with mitochondria or lysosomes. This effect has also been confirmed for the normal type of cell line-human foreskin fibroblasts (Hs27). The costaining of dye T-5 with MitoTracker CMXRos Red demonstrates specificity to mitochondria at a concentration of 0.1 μM. Colocalization analysis has shown signals overlapping of dye T-5 and MitoTracker CMXRos Red (Pearson's Coefficient value = 0.92 ± 0.04). The photostability study shows benzoxazole dyes to be up to ∼7 times more photostable than benzothiazole ones. Moreover, studied benzoxazoles are less cytotoxic at working concentrations than benzothiazoles (67% of cell viability for T-4, T-5 compared to 12% for T-1, and ∼30% for T-2, T-3 after 24 h). Therefore, the benzoxazole T-4 dye is proposed for nucleic acid detection in vitro and intracellular fluorescence imaging of live and fixed cells. In contrast, the benzoxazole dye T-5 is proposed as a good alternative to commercial dyes for mitochondria staining in the green-yellow region of the spectrum.

Diagnostic performance of gliomas grading and IDH status decoding A comparison between 3D amide proton transfer APT and four diffusion-weighted MRI models

BACKGROUND

The focus of neuro-oncology research has changed from histopathologic grading to molecular characteristics, and medical imaging routinely follows this change.

PURPOSE

To compare the diagnostic performance of amide proton transfer (APT) and four diffusion models in gliomas grading and isocitrate dehydrogenase (IDH) genotype.

STUDY TYPE

Prospective.

POPULATION

A total of 62 participants (37 males, 25 females; mean age, 52 ± 13 years) whose IDH genotypes were mutant in 6 of 14 grade II gliomas, 8 of 20 of grade III gliomas, and 4 of 28 grade IV gliomas.

FIELD STRENGTH/SEQUENCE

APT imaging using sampling perfection with application optimized contrasts by using different flip angle evolutions (SPACE) and DWI with q-space Cartesian grid sampling were acquired at 3 T.

ASSESSMENT

The ability of diffusion kurtosis imaging, diffusion kurtosis imaging, neurite orientation dispersion and density imaging (NODDI), mean apparent propagator (MAP), and APT imaging for glioma grade and IDH status were assessed, with histopathological grade and genetic testing used as a reference standard. Regions of interest (ROIs) were drawn by two neuroradiologists after consensus.

STATISTICAL TESTS

T-test and Mann-Whitney U test; one-way analysis of variance (ANOVA); receiver operating curve (ROC) and area under the curve (AUC); DeLong test. P value < 0.05 was considered statistically significant.

RESULTS

Compared with IDH-mutant gliomas, IDH-wildtype gliomas showed a significantly higher mean, 5th-percentile (APT₅ ), and 95th-percentile from APTw, the 95th-percentile value of axial, mean, and radial diffusivity from DKI, and 95th-percentile value of isotropic volume fraction from NODDI, and no significantly different parameters from DTI and MAP (P = 0.075-0.998). The combined APT model showed a significantly wider area under the curve (AUC 0.870) for IDH status, when compared with DKI and NODDI. APT₅ was significantly different between two of the three groups (glioma II vs. glioma III vs. glioma IV: 1.35 ± 0.75 vs. 2.09 ± 0.93 vs. 2.71 ± 0.81).

DATA CONCLUSION

APT has higher diagnostic accuracy than DTI, DKI, MAP, and NODDI in glioma IDH genotype. APT₅ can effectively identify both tumor grading and IDH genotyping, making it a promising biomarker for glioma classification.

EVIDENCE LEVEL

1 TECHNICAL EFFICACY: Stage 2.

pH-Sensitive Targeting of Tumors with Chemotherapy-Laden Nanoparticles: Progress and Challenges

Accumulating chemotherapeutic drugs such as doxorubicin within a tumor while limiting the drug dose to normal tissues is a central goal of drug delivery with nanoparticles. Liposomal products such as Doxil® represent one of the marked successes of nanoparticle-based strategies. To replicate this success for cancer treatment, many approaches with nanoparticles are being explored in order to direct and release chemotherapeutic agents to achieve higher accumulation in tumors. A promising approach has been stimulus-based therapy, such as the release of chemotherapeutic agents from the nanoparticles in the acidic environments of the tumor matrix or the tumor endosomes. Upon reaching the acidic environments of the tumor, the particles, which are made up of pH-dependent polymers, become charged and release the entrapped chemotherapy agents. This review discusses recent advances in and prospects for pH-dependent histidine-based nanoparticles that deliver chemotherapeutic agents to tumors. The strategies used by investigators include an array of histidine-containing peptides and polymers which form micelles, mixed micelles, nanovesicles, polyplexes, and coat particles. To date, several promising histidine-based nanoparticles have been demonstrated to produce marked inhibition of tumor growth, but challenges remain for successful outcomes in clinical trials. The lessons learned from these histidine-containing particles will provide insight in the development of improved pH-dependent polymeric delivery systems for chemotherapy.

Research and Development of Preclinical Overhauser-Enhanced Magnetic Resonance Imaging

Significance: Imaging free radicals, including reactive oxygen species and reactive nitrogen species, can be useful for understanding the pathology of diseases in animal disease models, as they are related to various physiological functions or diseases. Among the methods used for imaging free radicals, Overhauser-enhanced magnetic resonance imaging (OMRI) has a short image acquisition time and high spatial resolution. Therefore, OMRI is used to obtain various biological parameters. In this study, we review the methodology for improving the biological OMRI system and its applications. Recent Advances: The sensitivity of OMRI systems has been enhanced significantly to allow the visualization of various biological parameters, such as redox state, partial oxygen pressure, and pH, in different body parts of small animals, using spin probes. Furthermore, both endogenous free radicals and exogenous free radicals present in drugs can be visualized using OMRI. Critical Issues: To acquire accurate biological parameters at a high resolution, it is essential to increase the electron paramagnetic resonance (EPR) excitation efficiency and achieve a high enhancement factor. In addition, the size and magnetic field strength also need to be optimized for the measurement target. Future Directions: The advancement of in vivo OMRI techniques will be useful for understanding the pathology, diagnosis, and evaluation of therapeutic effects of drugs in various disease models. Antioxid. Redox Signal. 37, 1094-1110.

Nucleic acid-triggered tumoral immunity propagates pH-selective therapeutic antibodies through tumor-driven epitope spreading

Important roles of humoral tumor immunity are often pointed out; however, precise profiles of dominant antigens and developmental mechanisms remain elusive. We systematically investigated the humoral antigens of dominant intratumor immunoglobulin clones found in human cancers. We found that approximately half of the corresponding antigens were restricted to strongly and densely negatively charged polymers, resulting in simultaneous reactivities of the antibodies to both densely sulfated glycosaminoglycans (dsGAGs) and nucleic acids (NAs). These anti-dsGAG/NA antibodies matured and expanded via intratumoral immunological driving force of innate immunity via NAs. These human cancer-derived antibodies exhibited acidic pH-selective affinity across both antigens and showed specific reactivity to diverse spectrums of human tumor cells. The antibody-drug conjugate exerted therapeutic effects against multiple cancers in vivo by targeting cell surface dsGAG antigens. This study reveals that intratumoral immunological reactions propagate tumor-oriented immunoglobulin clones and demonstrates a new therapeutic modality for the universal treatment of human malignancies.

Early diagnosis of spinal tuberculosis by magnetic resonance: perfusion weighted imaging in a rabbit model

BACKGROUND

This study aimed to analyze the application value of magnetic resonance (MR)-perfusion weighted imaging (PWI) in the early imaging diagnosis of rabbit spinal tuberculosis.

METHODS

Spinal tuberculosis model was established using ATCC25177 Mycobacterium tuberculosis strain in the lumbar spine of rabbits. Forty rabbits were divided into 2 groups: rabbits in the experiment group were injected with 0.2 ml of 5.0 mg/ml tuberculosis suspension (n = 30) and those in the control group were injected with 0.2 ml of normal saline (n = 10) after vertebrae drilling surgery. Routine MRI and MR-PWI were performed at 4, 6, and 8 weeks after surgery. The statistical difference in terms of perfusion parameter values in the early MR-PWI scan of spinal tuberculosis between two groups was analyzed. The receiver operating characteristic (ROC) curve analysis was conducted for the accuracy of MR-PWI parameters in the early diagnosis of spinal tuberculosis.

RESULTS

Except time to peak, the other perfusion parameters in the experiment group were all increased with time. In addition, the difference between the two groups, as well as the differences at each time point was statistically significant (all P < 0.05). First-pass enhancement rate (Efirst), early enhancement rate (Ee), peak height (PH), maximum slope of increase (MSI), maximum signal enhancement rate (Emax) and signal enhancement rate (SER) showed high values in early diagnosing spinal tuberculosis.

CONCLUSION

The parameters including Efirst, Ee, PH, MSI, Emax and SER may provide valuable imaging evidence for the early diagnosis of spinal tuberculosis in clinical application.

Dual-Mode Tumor Imaging Using Probes That Are Responsive to Hypoxia-Induced Pathological Conditions

Hypoxia in solid tumors is associated with poor prognosis, increased aggressiveness, and strong resistance to therapeutics, making accurate monitoring of hypoxia important. Several imaging modalities have been used to study hypoxia, but each modality has inherent limitations. The use of a second modality can compensate for the limitations and validate the results of any single imaging modality. In this review, we describe dual-mode imaging systems for the detection of hypoxia that have been reported since the start of the 21st century. First, we provide a brief overview of the hallmarks of hypoxia used for imaging and the imaging modalities used to detect hypoxia, including optical imaging, ultrasound imaging, photoacoustic imaging, single-photon emission tomography, X-ray computed tomography, positron emission tomography, Cerenkov radiation energy transfer imaging, magnetic resonance imaging, electron paramagnetic resonance imaging, magnetic particle imaging, and surface-enhanced Raman spectroscopy, and mass spectrometric imaging. These overviews are followed by examples of hypoxia-relevant imaging using a mixture of probes for complementary single-mode imaging techniques. Then, we describe dual-mode molecular switches that are responsive in multiple imaging modalities to at least one hypoxia-induced pathological change. Finally, we offer future perspectives toward dual-mode imaging of hypoxia and hypoxia-induced pathophysiological changes in tumor microenvironments.

Effects of pH alterations on stress- and aging-induced protein phase separation

Upon stress challenges, proteins/RNAs undergo liquid–liquid phase separation (LLPS) to fine-tune cell physiology and metabolism to help cells adapt to adverse environments. The formation of LLPS has been recently linked with intracellular pH, and maintaining proper intracellular pH homeostasis is known to be essential for the survival of organisms. However, organisms are constantly exposed to diverse stresses, which are accompanied by alterations in the intracellular pH. Aging processes and human diseases are also intimately linked with intracellular pH alterations. In this review, we summarize stress-, aging-, and cancer-associated pH changes together with the mechanisms by which cells regulate cytosolic pH homeostasis. How critical cell components undergo LLPS in response to pH alterations is also discussed, along with the functional roles of intracellular pH fluctuation in the regulation of LLPS. Further studies investigating the interplay of pH with other stressors in LLPS regulation and identifying protein responses to different pH levels will provide an in-depth understanding of the mechanisms underlying pH-driven LLPS in cell adaptation. Moreover, deciphering aging and disease-associated pH changes that influence LLPS condensate formation could lead to a deeper understanding of the functional roles of biomolecular condensates in aging and aging-related diseases.

Identification of human LDHC4 as a potential target for anticancer drug discovery

One of the distinct hallmarks of cancer cells is aerobic glycolysis (Warburg effect). Lactate dehydrogenase A (LDHA) is thought to play a key role in aerobic glycolysis and has been extensively studied, while lactate dehydrogenase C (LDHC), an isoform of LDHA, has received much less attention. Here we showed that human LDHC was significantly expressed in lung cancer tissues, overexpression of Ldhc in mice could promote tumor growth, and knock-down of LDHC could inhibit the proliferation of lung cancer A549 cells. We solved the first crystal structure of human LDHC4 and found that the active-site loop of LDHC4 adopted a distinct conformation compared to LDHA4 and lactate dehydrogenase B4 (LDHB4). Moreover, we found that (ethylamino) (oxo)acetic acid shows about 10 times selective inhibition against LDHC4 over LDHA4 and LDHB4. Our studies suggest that LDHC4 is a potential target for anticancer drug discovery and (ethylamino) (oxo)acetic acid provides a good start to develop lead compounds for selective drugs targeting LDHC4.

Review and consensus recommendations on clinical APT-weighted imaging approaches at 3T: Application to brain tumors

Amide proton transfer-weighted (APTw) MR imaging shows promise as a biomarker of brain tumor status. Currently used APTw MRI pulse sequences and protocols vary substantially among different institutes, and there are no agreed-on standards in the imaging community. Therefore, the results acquired from different research centers are difficult to compare, which hampers uniform clinical application and interpretation. This paper reviews current clinical APTw imaging approaches and provides a rationale for optimized APTw brain tumor imaging at 3 T, including specific recommendations for pulse sequences, acquisition protocols, and data processing methods. We expect that these consensus recommendations will become the first broadly accepted guidelines for APTw imaging of brain tumors on 3 T MRI systems from different vendors. This will allow more medical centers to use the same or comparable APTw MRI techniques for the detection, characterization, and monitoring of brain tumors, enabling multi-center trials in larger patient cohorts and, ultimately, routine clinical use.

Radiometal-Based PET/MRI Contrast Agents for Sensing Tumor Extracellular pH

Acidosis is a useful biomarker for tumor diagnoses and for evaluating early response to anti-cancer treatments. Despite these useful applications, there are few methods for non-invasively measuring tumor extracellular pH, and none are routinely used in clinics. Responsive MRI contrast agents have been developed, and they undergo a change in MRI signal with pH. However, these signal changes are concentration-dependent, and it is difficult to accurately measure the concentration of an MRI contrast agent in vivo. PET/MRI provides a unique opportunity to overcome this concentration dependence issue by using the PET component to report on the concentration of the pH-responsive MRI agent. Herein, we synthesized PET/MRI co-agents based on the design of a pH-dependent MRI agent, and we have correlated pH with the r₁ relaxivity of the MRI co-agent. We have also developed a procedure that uses PET radioactivity measurements and MRI R₁ relaxation rate measurements to determine the r₁ relaxivity of the MRI co-agent, which can then be used to estimate pH. This simultaneous PET/MRI procedure accurately measured pH in solution, with a precision that depended on the concentration of the MRI co-agent. We used our procedure to measure extracellular pH in a subcutaneous flank model of MIA PaCa-2 pancreatic cancer. Although the PET co-agents were stable in serum, post-imaging studies showed evidence that the PET co-agents were degraded in vivo. These results showed that tumor acidosis can be evaluated with simultaneous PET/MRI, although improvements are needed to more precisely measure MRI R₁ relaxation rates, and ensure the in vivo stability of the agents.

Targeted contrast agents and activatable probes for photoacoustic imaging of cancer

Photoacoustic (PA) imaging has emerged as a powerful technique for the high resolution visualization of biological processes within deep tissue. Through the development and application of exogenous targeted contrast agents and activatable probes that can respond to a given cancer biomarker, researchers can image molecular events in vivo during cancer progression. This information can provide valuable details that can facilitate cancer diagnosis and therapy monitoring. In this tutorial review, we provide a step-by-step guide to select a cancer biomarker and subsequent approaches to design imaging agents for in vivo use. We envision this information will be a useful summary to those in the field, new members to the community, and graduate students taking advanced imaging coursework. We also highlight notable examples from the recent literature, with emphasis on the molecular designs and their in vivo PA imaging performance. To conclude, we provide our outlook and future perspective in this exciting field.

Melatonin: Regulation of Prion Protein Phase Separation in Cancer Multidrug Resistance

The unique ability to adapt and thrive in inhospitable, stressful tumor microenvironments (TME) also renders cancer cells resistant to traditional chemotherapeutic treatments and/or novel pharmaceuticals. Cancer cells exhibit extensive metabolic alterations involving hypoxia, accelerated glycolysis, oxidative stress, and increased extracellular ATP that may activate ancient, conserved prion adaptive response strategies that exacerbate multidrug resistance (MDR) by exploiting cellular stress to increase cancer metastatic potential and stemness, balance proliferation and differentiation, and amplify resistance to apoptosis. The regulation of prions in MDR is further complicated by important, putative physiological functions of ligand-binding and signal transduction. Melatonin is capable of both enhancing physiological functions and inhibiting oncogenic properties of prion proteins. Through regulation of phase separation of the prion N-terminal domain which targets and interacts with lipid rafts, melatonin may prevent conformational changes that can result in aggregation and/or conversion to pathological, infectious isoforms. As a cancer therapy adjuvant, melatonin could modulate TME oxidative stress levels and hypoxia, reverse pH gradient changes, reduce lipid peroxidation, and protect lipid raft compositions to suppress prion-mediated, non-Mendelian, heritable, but often reversible epigenetic adaptations that facilitate cancer heterogeneity, stemness, metastasis, and drug resistance. This review examines some of the mechanisms that may balance physiological and pathological effects of prions and prion-like proteins achieved through the synergistic use of melatonin to ameliorate MDR, which remains a challenge in cancer treatment.

Heat Modulation of Intrinsic MR Contrasts for Tumor Characterization

(1) Background: The longitudinal relaxation time (T1), transverse relaxation time (T2), water proton chemical shift (CS), and apparent diffusion coefficient (ADC) are MR quantities that change with temperature. In this work, we investigate heat-induced intrinsic MR contrast types to add salient information to conventional MR imaging to improve tumor characterization. (2) Methods: Imaging tests were performed in vivo using different rat tumor models. The rats were cooled/heated to steady-state temperatures from 26–36 °C and quantitative measurements of T1, T2, and ADC were obtained. Temperature maps were measured using the proton resonance frequency shift (PRFS) method during the heating and cooling cycles. (3) Results: All tissue samples show repeatable relaxation parameter measurement over a range of 26–36 °C. Most notably, we observed a more than 3.3% change in T1/°C in breast adenocarcinoma tumors compared to a 1% change in benign breast fibroadenoma lesions. In addition, we note distinct values of T2/°C change for rat prostate carcinoma cells compared to benign tissue. (4) Conclusion: These findings suggest the possibility of improving MR imaging visualization and characterization of tissue with heat-induced contrast types. Specifically, these results suggest that the temporal thermal responses of heat-sensitive MR imaging contrast mechanisms in different tissue types contain information for improved (i) characterization of tumor/tissue boundaries for diagnostic and therapy purposes, and (ii) characterization of salient behavior of tissues, e.g., malignant versus benign tumors.

The role of tumor acidification in aggressiveness, cell dissemination and treatment resistance of oral squamous cell carcinoma

AIMS

To investigate the role of tumor acidification in cell behavior, migration, and treatment resistance of oral squamous cell carcinoma (OSCC).

MAIN METHODS

The SCC4 and SCC25 cell lines were exposed to acidified (pH 6.8) cell culture medium for 7 days. Alternatively, a long-term acidosis was induced for 21 days. In addition, to mimic dynamic pH fluctuation of the tumor microenvironment, cells were reconditioned to neutral pH after experimental acidosis. This study assessed cell proliferation and viability by sulforhodamine B and flow cytometry. Individual and collective cell migration was analyzed by wound healing, time lapse, and transwell assays. Modifications of cell phenotype, EMT induction and stemness potential were investigated by qRT-PCR, western blot, and immunofluorescence. Finally, resistance to chemo- and radiotherapy of OSCC when exposed to acidified environmental conditions (pH 6.8) was determined.

KEY FINDINGS

The exposure to an acidic microenvironment caused an initial reduction of OSCC cells viability, followed by an adaptation process. Acidic adapted cells acquired a mesenchymal-like phenotype along with increased migration and motility indexes. Moreover, tumoral extracellular acidity was capable to induce cellular stemness and to increase chemo- and radioresistance of oral cancer cells.

SIGNIFICANCE

In summary, the results showed that the acidic microenvironment leads to a more aggressive and treatment resistant OSCC cell population.

Expression of Proton-Sensitive GPR31, GPR151, TASK1 and TASK3 in Common Skin Tumors

TWIK-related acid-sensitive potassium channels TASK1 and TASK3, as well as the G-protein-coupled receptors GPR31 and GPR151, are proton-sensitive membrane proteins. They can be activated or inhibited by low extracellular pH (pHe), which is a hallmark of the tumor microenvironment in solid tumors. However, the role of these channels in the development of skin tumors is still unclear. In this study, we investigated the expression profiles of TASK1, TASK3, GPR31 and GPR151 in squamous cell carcinomas (SCCs), basal cell carcinomas (BCCs), nevus cell nevi (NCN), and malignant melanomas (MMs). We performed immunohistochemistry using paraffin-embedded tissue samples from patients and found that most skin tumors express TASK1/3 and GPR31/151. The results show that BCCs are often negative for GPR31/151 as well as for TASK1/3, while nearly all SCCs express these markers. MMs and NCN show similar expression patterns. However, some tumors show a decreasing TASK1/3 expression in deeper dermal tumor tissue, while GPCRs were expressed more evenly. The lower frequency of GPR31/151 and TSAK1/3 expression in BCCs when compared to SCCs is a novel histological feature distinguishing these two entities. Moreover, BCCs also show lower expression of GPR31/151 and TASK1/3 as compared to NCN and MMs.

A reciprocal feedback of miR-548ac/YB-1/Snail induces EndMT of HUVECs during acidity microenvironment

Background

Researches indicated the process of Endothelial-Mesenchymal-Transition (EndMT) of vascular endothelial cells (ECs) was critically involved in the progression of tumor. ECs demonstrated functional and phenotypic heterogeneity when located under different microenvironments. The extracellular pH of tumor tissues was acidic compared to that of normal tissues. However, there was still unclear whether the acidic microenvironment affected the EndMT of vascular ECs.

Methods

Human Umbilical Vein Endothelial Cell (HUVECs) was cultured under the normal or acidic medium to evaluate the alteration of morphology, migration, permeability, and EndMT markers. Microarray assay was adopted to analyze the differential expression of miRNAs in the acidity-treated HUVECs. Gain- and loss- of function experiments were performed to evaluate the functional role of miRNA-548ac on acidity-induced EndMT of HUVECs. Luciferase reporter and Chromatin-immunoprecipitation assays were conducted to assess the downstream pathway of miRNA-548ac in acidity-induced EndMT of HUVECs.

Results

Our results showed that HUVECs demonstrated mesenchymal transition under acidic conditions with the increase of migration, permeability, and expression of α-SMA and Vimentin, but the expression of vascular endothelial cadherin (VE-cadherin) and CD31 were reduced. In addition, the acidity-treated HUVECs remarkably facilitated the transmigration of pancreatic cancer cells. The expression of miRNA-548ac was significantly decreased in the acidity-treated HUVECs. Moreover, overexpression of miR-548ac inhibited the EndMT of HUVECs and consequently impeded the transmigration of pancreatic cancer cells. The miR-548ac inhibited the expression of YB-1 by binding to the 3’UTR of its mRNA, and YB-1 promoted the translation of Snail which was a critical regulator of EndMT. What’s more, Snail transcriptionally inhibited the expression of miR-548ac through binding to the promoter of its host gene.

Conclusions

Our data implicated that the acidic microenvironment promoted the EndMT of HUVECs by the miR-548ac/YB-1/Snail axis, which could contribute to the metastasis of pancreatic cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02388-8.

Bispecific Aptamer Sensor toward T-Cell Leukemia Detection in the Tumor Microenvironment

The current detection methods of malignant cells are mainly based on the high expression levels of certain surface proteins on these cells. However, many of the same surface marker proteins are also expressed in normal cells. Growing evidence suggests that the molecular signatures of the tumor microenvironment (TME) are related to the biological state of a diseased cell. Exploiting the unique molecular signature of the TME, we have designed a molecular sensing agent consisting of a molecular switch that can sense the elevated concentration of a small molecule in the TME and promote precise recognition of a malignant cell. We accomplished this by designing and developing a bispecific aptamer that takes advantage of a high concentration of adenosine 5'-triphosphate in the TME. Thus, we report a prototype of a bispecific aptamer molecule, which serves as a dual detection platform and recognizes tumor cells only when a given metabolite concentration is elevated in the TME. This system overcomes hurdles in detecting tumor cells solely based on the elevated expression of cell surface markers, providing a universal platform for tumor targeting and sensing.

A SERS-Active Electrospun Polymer Mesh for Spatially Localized pH Measurements of the Cellular Microenvironment

Extracellular pH (pHe) is an important chemical factor in many cellular processes and disease pathologies. The routine sampling of pHe in vitro could lead to innovative advances in therapeutics. To this end, we have fabricated a novel gold-coated polymer mesh, which facilitates the real-time measurement of pHe via surface-enhanced Raman scattering (SERS). In this proof of concept study, we apply our SERS sensor to measure metabolically induced changes in the pHe of carcinoma-derived cell line HepG2/C3A. We demonstrate that gold-coated polyurethane electrospun nanofibers (AuNF) have strong and reproducible SERS spectra of surface-adsorbed analytes. By functionalizing AuNF with pH-responsive reporter 4-mercaptobenzoic acid (MBA), we have developed an accurate pH SERS sensor for the extracellular microenvironment. We cultured HepG2/C3A on the surface of MBA-AuNF and measured an acidic shift in pHe at the cell-fiber interface. Following exposure to staurosporine, an apoptosis-inducing drug, we observed changes in the HepG2/C3A cellular morphology indicative of controlled cell death, and detected an increase in the pHe of HepG2/C3A. These results demonstrate how subtle changes in pHe, induced by the metabolic activity of cells, can be measured with our novel SERS sensor MBA-AuNF. The excellent pH measurement performance of MBA-AuNF provides a unique platform to study extracellular pH on the microscale and will help to deepen our understanding of pHe in disease pathology.

Di[12]aneN3-Functionalized Green Fluorescent Protein Chromophore for GFP Luminescence Simulation and Efficient Gene Transfection In Vitro and In Vivo

Although a plethora of gene carriers have been developed for potential gene therapy, imageable stimuli-responsive gene vectors with fast access to the nucleus, high biocompatibility, and transfection efficiency are still scarce. Herein, we report the design and synthesis of four dendrite-shaped cationic liposomes, MPA-HBI-R/DOPE (R: n-butyl, 1; n-octyl, 2; n-dodecyl, 3; palmyl, 4), prepared via esterification of 4-alkoxybenzylideneimidazolinone containing aliphatic chains of different lengths (HBI-R), the green fluorescent protein (GFP) chromophore, with a di[12]aneN₃ unit. Liposomes were fabricated via the self-assembly of MPA-HBI-R, assisted with 1,2-dioleoyl-sn-glycerol-3-phosphorylethanolamine (DOPE). These liposomes (MPA-HBI-R/DOPE) exhibited efficient DNA condensation, pH-responsive degradation, excellent cellular biocompatibility (up to 150 μM), and high transfection efficiency. Molecular docking experiments were also used to verify the optimal interaction between MPA-HBI-R and DNA, as well as the fluorescence enhancements. In particular, MPA-HBI-2/DOPE delivered DNA into the nucleus in less than an hour, and its luciferase transfection activity was more than 10 times that by Lipo2000, across multiple cell lines. The GFP chromophore conjugation allowed trackable intracellular delivery and release of DNA in real time via fluorescence imaging. Furthermore, efficient red fluorescent protein (RFP) transfection in zebrafish, with an efficiency of more than 6 times that by Lipo2000, was also achieved. The results not only realized, for the first time, the combination of gene delivery and GFP-simulated light emission, allowing fluorescent tracking and highly efficient gene transfection, but also offered valuable insights into the use of biomimetic chromophore for the development of the next-generation nonviral vectors.

Machine learning classification of texture features of MRI breast tumor and peri-tumor of combined pre- and early treatment predicts pathologic complete response

Purpose

This study used machine learning classification of texture features from MRI of breast tumor and peri-tumor at multiple treatment time points in conjunction with molecular subtypes to predict eventual pathological complete response (PCR) to neoadjuvant chemotherapy.

Materials and method

This study employed a subset of patients (N = 166) with PCR data from the I-SPY-1 TRIAL (2002–2006). This cohort consisted of patients with stage 2 or 3 breast cancer that underwent anthracycline–cyclophosphamide and taxane treatment. Magnetic resonance imaging (MRI) was acquired pre-neoadjuvant chemotherapy, early, and mid-treatment. Texture features were extracted from post-contrast-enhanced MRI, pre- and post-contrast subtraction images, and with morphological dilation to include peri-tumoral tissue. Molecular subtypes and Ki67 were also included in the prediction model. Performance of classification models used the receiver operating characteristics curve analysis including area under the curve (AUC). Statistical analysis was done using unpaired two-tailed t-tests.

Results

Molecular subtypes alone yielded moderate prediction performance of PCR (AUC = 0.82, p = 0.07). Pre-, early, and mid-treatment data alone yielded moderate performance (AUC = 0.88, 0.72, and 0.78, p = 0.03, 0.13, 0.44, respectively). The combined pre- and early treatment data markedly improved performance (AUC = 0.96, p = 0.0003). Addition of molecular subtypes improved performance slightly for individual time points but substantially for the combined pre- and early treatment (AUC = 0.98, p = 0.0003). The optimal morphological dilation was 3–5 pixels. Subtraction of post- and pre-contrast MRI further improved performance (AUC = 0.98, p = 0.00003). Finally, among the machine-learning algorithms evaluated, the RUSBoosted Tree machine-learning method yielded the highest performance.

Conclusion

AI-classification of texture features from MRI of breast tumor at multiple treatment time points accurately predicts eventual PCR. Longitudinal changes in texture features and peri-tumoral features further improve PCR prediction performance. Accurate assessment of treatment efficacy early on could minimize unnecessary toxic chemotherapy and enable mid-treatment modification for patients to achieve better clinical outcomes.

Tumor Sphericity Predicts Response in Neoadjuvant Chemotherapy for Invasive Breast Cancer

This retrospective study examined magnetic resonance imaging (MRI)–derived tumor sphericity (SPH) as a quantitative measure of breast tumor morphology, and investigated the association between SPH and reader-assessed morphological pattern (MP). In addition, association of SPH with pathologic complete response was evaluated in patients enrolled in an adaptively randomized clinical trial designed to rapidly identify new agents for breast cancer. All patients underwent MRI examinations at multiple time points during the treatment. SPH values from pretreatment (T0) and early-treatment (T1) were investigated in this study. MP on T0 dynamic contrast-enhanced MRI was ranked from 1 to 5 in 220 patients. Mean SPH values decreased with the increased order of MP. SPH was higher in patients with pathologic complete response than in patients without (difference at T0: 0.04, 95% confidence interval [CI]: 0.02–0.05, P < .001; difference at T1: 0.03, 95% CI: 0.02–0.04, P < .001). The area under the receiver operating characteristic curve was estimated as 0.61 (95% CI, 0.57–0.65) at T0 and 0.58 (95% CI, 0.55–0.62) at T1. When the analysis was performed by cancer subtype defined by hormone receptor (HR) and human epidermal growth factor receptor 2 (HER2) status, highest area under the receiver operating characteristic curve were observed in HR−/HER2+: 0.67 (95% CI, 0.54–0.80) at T0, and 0.63 (95% CI, 0.51–0.76) at T1. Tumor SPH showed promise to quantify MRI MPs and as a biomarker for predicting treatment outcome at pre- or early-treatment time points.

DiSpect: Displacement spectrum imaging of flow and tissue perfusion using spin-labeling and stimulated echoes

PURPOSE

We propose a new method, displacement spectrum (DiSpect) imaging, for probing in vivo complex tissue dynamics such as motion, flow, diffusion, and perfusion. Based on stimulated echoes and image phase, our flexible approach enables observations of the spin dynamics over short (milliseconds) to long (seconds) evolution times.

METHODS

The DiSpect method is a Fourier-encoded variant of displacement encoding with stimulated echoes, which encodes bulk displacement of spins that occurs between tagging and imaging in the image phase. However, this method fails to capture partial volume effects as well as blood flow. The DiSpect variant mitigates this by performing multiple scans with increasing displacement-encoding steps. Fourier analysis can then resolve the multidimensional spectrum of displacements that spins exhibit over the mixing time. In addition, repeated imaging following tagging can capture dynamic displacement spectra with increasing mixing times.

RESULTS

We demonstrate properties of DiSpect MRI using flow phantom experiments as well as in vivo brain scans. Specifically, the ability of DiSpect to perform retrospective vessel-selective perfusion imaging at multiple mixing times is highlighted.

CONCLUSION

The DiSpect variant is a new tool in the arsenal of MRI techniques for probing complex tissue dynamics. The flexibility and the rich information it provides open the possibility of alternative ways to quantitatively measure numerous complex spin dynamics, such as flow and perfusion within a single exam.

Cancer-Associated Fibroblasts in the Breast Tumor Microenvironment

Years of investigation have shed light on a theory in which breast tumor epithelial cells are under the effect of the stromal microenvironment. This review aims to discuss recent findings concerning the phenotypic and functional characteristics of cancer associated fibroblasts (CAFs) and their involvement in tumor evolution, as well as their potential implications for anti-cancer therapy. In this manuscript, we reviewed that CAFs play a fundamental role in initiation, growth, invasion, and metastasis of breast cancer, and also serve as biomarkers in the clinical diagnosis, therapy, and prognosis of this disease.