Tumor acidosis-induced DNA damage response and tetraploidy enhance sensitivity to ATM and ATR inhibitors.

Tumor acidosis is associated with increased invasiveness and drug resistance. Here, we take an unbiased approach to identify vulnerabilities of acid-exposed cancer cells by combining pH-dependent flow cytometry cell sorting from 3D colorectal tumor spheroids and transcriptomic profiling. Besides metabolic rewiring, we identify an increase in tetraploid cell frequency and DNA damage response as consistent hallmarks of acid-exposed cancer cells, supported by the activation of ATM and ATR signaling pathways. We find that regardless of the cell replication error status, both ATM and ATR inhibitors exert preferential growth inhibitory effects on acid-exposed cancer cells. The efficacy of a combination of these drugs with 5-FU is further documented in 3D spheroids as well as in patient-derived colorectal tumor organoids. These data position tumor acidosis as a revelator of the therapeutic potential of DNA repair blockers and as an attractive clinical biomarker to predict the response to a combination with chemotherapy.

The Role of microRNAs in Gene Expression and Signaling Response of Tumor Cells to an Acidic Environment.

Many tumors are characterized by marked extracellular acidosis due to increased glycolytic metabolism, which affects gene expression and thereby tumor biological behavior. At the same time, acidosis leads to altered expression of several microRNAs (Mir7, Mir183, Mir203, Mir215). The aim of this study was to analyze whether the acidosis-induced changes in cytokines and tumor-related genes are mediated via pH-sensitive microRNAs. Therefore, the expression of Il6, Nos2, Ccl2, Spp1, Tnf, Acat2, Aox1, Crem, Gls2, Per3, Pink1, Txnip, and Ypel3 was examined in acidosis upon simultaneous transfection with microRNA mimics or antagomirs in two tumor lines in vitro and in vivo. In addition, it was investigated whether microRNA expression in acidosis is affected via known pH-sensitive signaling pathways (MAPK, PKC, PI3K), via ROS, or via altered intracellular Ca2+ concentration. pH-dependent microRNAs were shown to play only a minor role in modulating gene expression. Individual genes (e.g., Ccl2, Txnip, Ypel3) appear to be affected by Mir183, Mir203, or Mir215 in acidosis, but these effects are cell line-specific. When examining whether acid-dependent signaling affects microRNA expression, it was found that Mir203 was modulated by MAPK and ROS, Mir7 was affected by PKC, and Mir215 was dependent on the intracellular Ca2+ concentration. Mir183 could be increased by ROS scavenging. These correlations could possibly result in new therapeutic approaches for acidotic tumors.

The Role of MicroRNA Expression for Proliferation and Apoptosis of Tumor Cells: Impact of Hypoxia-Related Acidosis.

The metabolic microenvironment in tumors is characterized by hypoxia and acidosis. Extracellular pH sometimes decreases to even below 6.0. Previous experiments showed that tissue pH has an impact on tumor cell proliferation and apoptosis. However, the mechanism of how cell cycle progression is affected by decreased pH is not fully understood yet. One possible mechanism includes changes in the expression of miRNAs. The aim of this study was to analyze the impact of pH-regulated miRNAs (miR-183 and miR-215) on proliferation, apoptosis, and necrosis of tumor cells. Therefore, AT1 prostate and Walker-256 mammary carcinoma cells were transfected with the miRNAs or with the respective antagomirs and incubated at pH 7.4 and 6.6 for 24 h. AT1 cells underwent a G0/G1 cell cycle arrest under acidic conditions and showed a marked reduction of the number of actively DNA-synthesizing cells. In Walker-256 cells, acidosis induced a reduction of apoptosis and additionally a significant increase in necrotic cell death. Transfection of tumor cells with miR-183 or miR-215, which were significantly downregulated under acidic conditions, had no impact on cell death of AT1 or Walker-256 cells. Overexpression of miR-183, which is also downregulated by acidosis, intensified G0/G1 cell cycle arrest in AT1 cells. Previous studies revealed that hypoxia-related tumor acidosis affects the expression of different small noncoding RNAs. However, not all of these acidosis-regulated miRNAs seem to have an impact on proliferation, apoptosis, and necrosis of tumor cells. While miR-215 had no influence, miR-183 seems to be an interesting candidate that could amplify the impact of extracellular acidosis on malignant behavior of tumor cells.

Functional Impact of Acidosis-Regulated MicroRNAs on the Migration and Adhesion of Tumor Cells.

Tumor tissue shows special features in metabolism in contrast to healthy tissue. Besides a distinctive oxygen deficiency, tumors often show a reduced extracellular pH (acidosis) resulting from an intensified glycolysis not only under hypoxic but also under normoxic conditions (Warburg effect). As shown in previous studies, cell migration is increased in AT1 prostate carcinoma cells after incubation at pH 6.6, and this leads to an increased number of lung metastases in vivo. However, the signaling pathway causing these functional changes is still unknown. Possible mediators could be acidosis-regulated microRNAs (miR-7, miR-183, miR-203, miR-215). The aim of the study was therefore to analyze whether a change in the expression of these microRNAs has an impact on the tumor cell migration and adhesion. Studies were performed with AT1 rat prostate cancer cells which were incubated for 24 h at pH 7.4 or 6.6. Keeping AT1 tumor cells at low pH increased the migratory capacity by about 100%. But also the decrease of miR-203 and miR-215 expression (at normal pH) led to an increase in migration velocity by 50%. In contrast, cell adhesion was increased by about 75% at low pH. However, an increase in miR-215 expression at pH 6.6 reduced the adhesion by trend. These results clearly indicated that the extracellular pH has an impact on migration and adhesion of tumor cells. In this mechanism, pH-regulated microRNAs could play a role since changes in the expression of these microRNAs (especially miR-203) are also able to modulate the migratory behavior.

The Warburg Effect: Historical Dogma Versus Current Rationale.

Contrary to Warburg's original thesis, accelerated aerobic glycolysis is not a primary and permanent consequence of dysfunctional mitochondria compensating for a poor ATP yield per mole glucose. Instead, the Warburg effect is an essential part of a "selfish" metabolic reprogramming, which results from the interplay between (normoxic or hypoxic) HIF-1 overexpression, oncogene activation (cMyc, Ras), loss of function of tumor suppressors (mutant p53, mutant PTEN, microRNAs and sirtuins with suppressor functions), activated (PI3K/Akt/mTORC1, Ras/Raf/Mek/Erk/c-Myc) or deactivated (AMPK) signaling pathways, components of the tumor microenvironment, and HIF-1 cooperations with epigenetic mechanisms. Molecular and functional processes of the Warburg effect include (a) considerably accelerated glycolytic fluxes; (b) adequate ATP generation per unit time to maintain energy homeostasis; (c) backup and diversion of glycolytic intermediates facilitating the biosynthesis of nucleotides, nonessential amino acids, lipids, and hexosamines; (d) inhibition of pyruvate entry into mitochondria; (e) excessive formation and accumulation of lactate which stimulates tumor growth and suppression of antitumor immunity (in addition, lactate can serve as an energy source for normoxic cancer cells, contributes to extracellular acidosis, and thus drives malignant progression and resistances to conventional therapies); (f) maintenance of the cellular redox homeostasis and low ROS formation; and (g) HIF-1 overexpression, mutant p53, and mutant PTEN which inhibit mitochondrial biogenesis and functions, thus negatively impacting cellular respiration rate. The glycolytic switch is an early event in oncogenesis and primarily supports cell survival. All in all, the Warburg effect, i.e., aerobic glycolysis in the presence of oxygen and - in principle - functioning mitochondria, constitutes a major driver of the cancer progression machinery, resistance to conventional therapies, and - finally - poor patient outcome.

Carbonic Anhydrase IX Inhibitors as Candidates for Combination Therapy of Solid Tumors.

Combination therapy is becoming imperative for the treatment of many cancers, as it provides a higher chance of avoiding drug resistance and tumor recurrence. Among the resistance-conferring factors, the tumor microenvironment plays a major role, and therefore, represents a viable target for adjuvant therapeutic agents. Thus, hypoxia and extracellular acidosis are known to select for the most aggressive and resilient phenotypes and build poorly responsive regions of the tumor mass. Carbonic anhydrase (CA, EC 4.2.1.1) IX isoform is a surficial zinc metalloenzyme that is proven to play a central role in regulating intra and extracellular pH, as well as modulating invasion and metastasis processes. With its strong association and distribution in various tumor tissues and well-known druggability, this protein holds great promise as a target to pharmacologically interfere with the tumor microenvironment by using drug combination regimens. In the present review, we summarized recent publications revealing the potential of CA IX inhibitors to intensify cancer chemotherapy and overcome drug resistance in preclinical settings.

Tumor pH and metastasis: a malignant process beyond hypoxia.

Tumors often show, compared to normal tissues, a markedly decreased extracellular pH resulting from anaerobic or aerobic glycolysis in combination with a reduced removal of acidic metabolites. Several studies indicate that acidosis induces (independently from hypoxia) hematogenous and lymphatic spread of tumor cells worsening the long-term prognosis of tumor patients. This review gives an overview on the impact of low pH on different steps of metastasis including (a) local tumor cell invasion and angiogenesis, (b) intravasation of tumor cells and detachment into the circulation, and (c) adherence of circulating tumor cells, transmigration and invasion in the new host tissue. The review describes pH-dependent cellular mechanisms fostering these steps such as epithelial-to-mesenchymal transition (EMT), activation of cell migration, degradation of the extracellular matrix, or angiogenesis. The review discusses mechanisms of tumor cells for proton sensing including acid-sensitive ion channels (ASICs, TRPs) or ion transporters (NHE1) and G protein coupled H+-sensors. Finally, the review describes several intracellular signaling cascades activated by H+ sensing mechanisms leading to transcriptional, post-transcriptional, or functional changes in the cell relevant for the metastatic spread. From these studies, different therapeutical approaches are described to overcome tumor acidosis or to interfere with the signaling cascades to reduce the metastatic potential of tumors.

Imaging tumor acidosis: a survey of the available techniques for mapping in vivo tumor pH.

Cancer cells are characterized by a metabolic shift in cellular energy production, orchestrated by the transcription factor HIF-1α, from mitochondrial oxidative phosphorylation to increased glycolysis, regardless of oxygen availability (Warburg effect). The constitutive upregulation of glycolysis leads to an overproduction of acidic metabolic products, resulting in enhanced acidification of the extracellular pH (pHe ~ 6.5), which is a salient feature of the tumor microenvironment. Despite the importance of pH and tumor acidosis, there is currently no established clinical tool available to image the spatial distribution of tumor pHe. The purpose of this review is to describe various imaging modalities for measuring intracellular and extracellular tumor pH. For each technique, we will discuss main advantages and limitations, pH accuracy and sensitivity of the applied pH-responsive probes and potential translatability to the clinic. Particular attention is devoted to methods that can provide pH measurements at high spatial resolution useful to address the task of tumor heterogeneity and to studies that explored tumor pH imaging for assessing treatment response to anticancer therapies.

Fatal Alliance of Hypoxia-/HIF-1α-Driven Microenvironmental Traits Promoting Cancer Progression.

Inhospitable conditions within the tumor microenvironment (TME) are a characteristic feature ('hallmark') of most solid malignancies. Regional tumor hypoxia is a primary deficiency since it plays a key role in malignant progression. Severe hypoxia is often associated with other detrimental conditions in the TME as a consequence of hypoxia-/HIF-1α-induced (with/without oncogene-direction and/or reciprocal interaction of cancer cells with TME cells) metabolic re-programming, exorbitant extracellular adenosine (ADO) generation and VEGF overexpression/VEGF-R activation. Re-programming of the tumor metabolism inter alia includes a 'selfish' upregulation of aerobic glycolysis/glycolytic flux ('Warburg effect'), a strongly enhanced glutaminolysis in tumor cells, ketogenesis in cancer-associated fibroblasts, and an acceleration of the tryptophan uptake/intensified catabolism yielding kynurenine, which can support the malignant phenotype. Aerobic glycolysis and glutaminolysis result in lactate accumulation (up to 40 mM), and together with the enhanced ketogenesis and CO2/carbonic acid production lead to extracellular acidosis (pHe < 6.8). These traits of the TME individually or collectively operate towards cancer progression via e.g. promotion of genetic instability and mutation, resistance to apoptosis, clonal selection, limitless cell survival and sustained proliferation, continuous angiogenesis and tumor growth, local invasion and distant metastasis, anti-tumor immunosuppression and resistance to therapy.

The critical role of calcineurin/NFAT (C/N) pathways and effective antitumor prospect for colorectal cancers.

Transcription factors (TFs) like a nuclear factor of activated T-cells (NFAT) and its controller calcineurin are highly expressed in primary intestinal epithelial cells (IECs) due to delamination, damage by tumor-associated flora and selective activation in the intestinal tract tumor are crucial in the progression and growth of colorectal cancer (CRC). This study sought to summarize the current findings concerning the dysregulated calcineurin/NFAT (C/N) signaling involved in CRC initiation and progression. These signalings include proliferation, T-cell functions, and glycolysis with high lactate production that remodels the acidosis, which genes in tumor cells provide an evolutionary advantage, or even increased their attack phenotype. Moreover, the relationship between C/N and gut microbiome in CRC, especially role of NFAT and toll-like receptor signaling in regulating intestinal microbiota are also discussed. Furthermore, this review will discuss the proteins and genes relating to C/N induced acidosis in CRC, which includes ASIC2 regulated C/N1 and TFs associated with the glycolytic by-product that affect T-cell functions and CRC cell growth. It is revealed that calcineurin or NFAT targeting to antitumor, selective calcineurin inhibition or targets in NFAT signaling may be useful for clinical treatment of CRC. This can further aid in the identification of specific targets via cancer patient-personalized approach. Future studies should be focused on targeting to C/N or TLR signaling by the combination of therapeutic agents to regulate T-cell functions and gut microbiome for activating potent anticancer property with the prospect of potentiating the antitumor therapy for CRC.

Benzotriazine Di-Oxide Prodrugs for Exploiting Hypoxia and Low Extracellular pH in Tumors.

Extracellular acidification is an important feature of tumor microenvironments but has yet to be successfully exploited in cancer therapy. The reversal of the pH gradient across the plasma membrane in cells that regulate intracellular pH (pHi) has potential to drive the selective uptake of weak acids at low extracellular pH (pHe). Here, we investigate the dual targeting of low pHe and hypoxia, another key feature of tumor microenvironments. We prepared eight bioreductive prodrugs based on the benzotriazine di-oxide (BTO) nucleus by appending alkanoic or aminoalkanoic acid sidechains. The BTO acids showed modest selectivity for both low pHe (pH 6.5 versus 7.4, ratios 2 to 5-fold) and anoxia (ratios 2 to 8-fold) in SiHa and FaDu cell cultures. Related neutral BTOs were not selective for acidosis, but had greater cytotoxic potency and hypoxic selectivity than the BTO acids. Investigation of the uptake and metabolism of representative BTO acids confirmed enhanced uptake at low pHe, but lower intracellular concentrations than expected for passive diffusion. Further, the modulation of intracellular reductase activity and competition by the cell-excluded electron acceptor WST-1 suggests that the majority of metabolic reductions of BTO acids occur at the cell surface, compromising the engagement of the resulting free radicals with intracellular targets. Thus, the present study provides support for designing bioreductive prodrugs that exploit pH-dependent partitioning, suggesting, however, that that the approach should be applied to prodrugs with obligate intracellular activation.

Therapeutic implications of tumor interstitial acidification.

Interstitial acidification is a hallmark of solid tumor tissues resulting from the combination of different factors, including cellular buffering systems, defective tissue perfusion and high rates of cellular metabolism. Besides contributing to tumor pathogenesis and promoting tumor progression, tumor acidosis constitutes an important intrinsic and extrinsic mechanism modulating therapy sensitivity and drug resistance. In fact, pharmacological properties of anticancer drugs can be affected not only by tissue structure and organization but also by the distribution of the interstitial tumor pH. The acidic tumor environment is believed to create a chemical barrier that limits the effects and activity of many anticancer drugs. In this review article we will discuss the general protumorigenic effects of acidosis, the role of tumor acidosis in the modulation of therapeutic efficacy and potential strategies to overcome pH-dependent therapy-resistance.

A comparison of exogenous and endogenous CEST MRI methods for evaluating in vivo pH.

PURPOSE: Extracellular pH (pHe) is an important biomarker for cancer cell metabolism. Acido-chemical exchange saturation transfer (CEST) MRI uses the contrast agent iopamidol to create spatial maps of pHe. Measurements of amide proton transfer exchange rates (kex ) from endogenous CEST MRI were compared to pHe measurements by exogenous acido-CEST MRI to determine whether endogenous kex could be used as a proxy for pHe measurements. METHODS: Spatial maps of pHe and kex were obtained using exogenous acidoCEST MRI and an endogenous CEST MRI analyzed with the omega plot method, respectively, to evaluate mouse kidney, a flank tumor model, and a spontaneous lung tumor model. The pHe and kex results were evaluated using pixelwise comparisons. RESULTS: The kex values obtained from endogenous CEST measurements did not correlate with the pHe results from exogenous CEST measurements. The kex measurements were limited to fewer pixels and had a limited dynamic range relative to pHe measurements. CONCLUSION: Measurements of kex with endogenous CEST MRI cannot substitute for pHe measurements with acidoCEST MRI. Whereas endogenous CEST MRI may still have good utility for evaluating some specific pathologies, exogenous acido-CEST MRI is more appropriate when evaluating pathologies based on pHe values. Magn Reson Med 79:2766-2772, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

A drug screening assay on cancer cells chronically adapted to acidosis.

BACKGROUND: Drug screening for the identification of compounds with anticancer activity is commonly performed using cell lines cultured under normal oxygen pressure and physiological pH. However, solid tumors are characterized by a microenvironment with limited access to nutrients, reduced oxygen supply and acidosis. Tumor hypoxia and acidosis have been identified as important drivers of malignant progression and contribute to multicellular resistance to different forms of therapy. Tumor acidosis represents an important mechanism mediating drug resistance thus the identification of drugs active on acid-adapted cells may improve the efficacy of cancer therapy. METHODS: Here, we characterized human colon carcinoma cells (HCT116) chronically adapted to grow at pH 6.8 and used them to screen the Prestwick drug library for cytotoxic compounds. Analysis of gene expression profiles in parental and low pH-adapted cells showed several differences relating to cell cycle, metabolism and autophagy. RESULTS: The screen led to the identification of several compounds which were further selected for their preferential cytotoxicity towards acid-adapted cells. Amongst 11 confirmed hits, we primarily focused our investigation on the benzoporphyrin derivative Verteporfin (VP). VP significantly reduced viability in low pH-adapted HCT116 cells as compared to parental HCT116 cells and normal immortalized epithelial cells. The cytotoxic activity of VP was enhanced by light activation and acidic pH culture conditions, likely via increased acid-dependent drug uptake. VP displayed the unique property to cause light-dependent cross-linking of proteins and resulted in accumulation of polyubiquitinated proteins without inducing inhibition of the proteasome. CONCLUSIONS: Our study provides an example and a tool to identify anticancer drugs targeting acid-adapted cancer cells.

Selective Recruitment of Antibodies to Cancer Cells and Immune Cell-mediated Killing via In Situ Click Chemistry.

Many current cancer immunotherapies function by redirecting immune system components to recognize cancer biomarkers and initiate a cytotoxic attack. The lack of a universal tumor biomarker limits the therapeutic potential of these approaches. However, one feature characteristic of nearly all solid tumors is extracellular acidity. This inherent acidity provides the basis for targeted drug delivery via the pH-low insertion peptide (pHLIP), which selectively accumulates in tumors in vivo due to a pH-dependent membrane insertion propensity. Previously, we established that we could selectively decorate cancer cells with antigen-pHLIP conjugates to facilitate antibody recruitment and subsequent killing by engineered effector cells via antibody-depended cellular cytotoxicity (ADCC). Here, we present a novel strategy for opsonizing antibodies on target cell surfaces using click chemistry. We utilize pHLIP to facilitate selective tetrazine - trans-cyclooctene ligation of human IgGs to the cancer cell surface and induce ADCC. We demonstrate that our approach activates the primary ADCC signaling pathway via CD16a (FcγRIIIa) receptors on effector cells and induces the killing of cancer cell targets by engineered NK cells.

Tumor perfusion enhancement by microbubbles ultrasonic cavitation reduces tumor glycolysis metabolism and alleviate tumor acidosis.

The tumor microenvironment is increasingly acknowledged as a critical contributor to cancer progression, mediating genetic and epigenetic alterations. Beyond diverse cellular interactions from the microenvironment, physicochemical factors such as tumor acidosis also significantly affect cancer dynamics. Recent research has highlighted that tumor acidosis facilitates invasion, immune escape, metastasis, and resistance to therapies. Thus, noninvasive measurement of tumor acidity and the development of targeted interventions represent promising strategies in oncology. Techniques like contrast-enhanced ultrasound (CEUS) can effectively assess blood perfusion, while ultrasound-stimulated microbubble cavitation (USMC) has proven to enhance tumor blood perfusion. We therefore aimed to determine whether CEUS assesses tumor acidity and whether USMC treatment can modulate tumor acidity. Firstly, we tracked CEUS perfusion parameters in MCF7 tumor models and compared them with in vivo tumor pH recorded by pH microsensors. We found that the peak intensity and area under curve of tumor contrast-enhanced ultrasound correlated well with tumor pH. We further conducted USMC treatment on MCF7 tumor-bearing mice, tracked changes of tumor blood perfusion and tumor pH in different perfusion regions before and after the USMC treatment to assess its impact on tumor acidity and optimize therapeutic ultrasound pressure. We discovered that USMC with 1.0 Mpa significantly improved tumor blood perfusion and tumor pH. Furthermore, tumor vascular pathology and PGI2 assays indicated that improved tumor perfusion was mainly due to vasodilation rather than angiogenesis. More importantly, analysis of glycolysis-related metabolites and enzymes demonstrated USMC treatment can reduce tumor acidity by reducing tumor glycolysis. These findings support that CEUS may serve as a potential biomarker to assess tumor acidity and USMC is a promising therapeutic modality for reducing tumor acidosis.

Modulation of mitochondrial function by extracellular acidosis in tumor cells and normal fibroblasts: Role of signaling pathways.

In many tumors pronounced extracellular acidosis resulting from glycolytic metabolism is found. Since several environmental stress factors affect the mitochondrial activity the aim of the study was to analyze the impact of acidosis on cellular oxygen consumption and which signaling pathways may be involved in the regulation. In two tumor cell lines and normal fibroblasts cellular oxygen consumption rate (OCR) and mitochondrial function were measured after 3 h at pH 6.6. Besides the activation of ERK1/2, p38 and PI3K signaling in the cytosolic and mitochondrial compartment, the mitochondrial structure and proteins related to mitochondria fission were analyzed. The acidic extracellular environment increased OCR in tumor cells but not in fibroblasts. In parallel, the mitochondrial membrane potential increased at low pH. In both tumor lines (but not in fibroblasts), the phosphorylation of ERK1/2 and PI3K/Akt was significantly increased, and both cascades were involved in OCR modulation. The activation of signaling pathways was located predominantly in the mitochondrial compartment of the cells. At low pH, the mitochondrial structure in tumor cells showed structural changes related to elongation whereas mitochondria fragmentation was reduced indicating mitochondria fusion. However, these morphological changes were not related to ERK1/2 or PI3K signaling. Acidic stress seems to induce an increased oxygen consumption, which might further aggravate tumor hypoxia. Low pH also induces mitochondria fusion that is not mediated by ERK1/2 or PI3K signaling. The mechanism by which these signaling cascades modulate the respiratory activity of tumor cells needs further investigation.

Tumoral acidosis promotes adipose tissue depletion by fostering adipocyte lipolysis.

OBJECTIVE: Tumour progression drives profound alterations in host metabolism, such as adipose tissue depletion, an early event of cancer cachexia. As fatty acid consumption by cancer cells increases upon acidosis of the tumour microenvironment, we reasoned that fatty acids derived from distant adipose lipolysis may sustain tumour fatty acid craving, leading to the adipose tissue loss observed in cancer cachexia. METHODS: To evaluate the pro-lipolytic capacities of acid-exposed cancer cells, primary mouse adipocytes from subcutaneous and visceral adipose tissue were exposed to pH-matched conditioned medium from human and murine acid-exposed cancer cells (pH 6.5), compared to naive cancer cells (pH 7.4). To further address the role of tumoral acidosis on adipose tissue loss, a pH-low insertion peptide was injected into tumour-bearing mice, and tumoral acidosis was neutralised with a sodium bicarbonate buffer. Prolipolytic mediators were identified by transcriptomic approaches and validated on murine and human adipocytes. RESULTS: Here, we reveal that acid-exposed cancer cells promote lipolysis from subcutaneous and visceral adipocytes and that dampening acidosis in vivo inhibits adipose tissue depletion. We further found a set of well-known prolipolytic factors enhanced upon acidosis adaptation and unravelled a role for ß-glucuronidase (GUSB) as a promising new actor in adipocyte lipolysis. CONCLUSIONS: Tumoral acidosis promotes the mobilization of fatty acids derived from adipocytes via the release of soluble factors by cancer cells. Our work paves the way for therapeutic approaches aimed at tackling cachexia by targeting the tumour acidic compartment.

The antagonist of ß-adrenergic receptor propranolol inhibits T cell lymphoma growth and enhances antitumor efficacy of cisplatin in vivo: A role of modulated apoptosis, glucose metabolism, pH regulation, and antitumor immune response.

Accumulating evidence has shown a vital role of stress-regulatory hormones, including epinephrine, in the progression of numerous cancers, including T cell lymphoma. Further, the antitumor and chemosensitizing potential of propranolol, an inexpensive ß-adrenergic receptor antagonist has also been reported against breast, colon, ovarian, and pancreatic cancers. However, in vivo antitumor and chemopotentiating activity of propranolol have not yet been examined against malignancies of hematological origin, including T cell lymphoma. Therefore, the present study is designed to evaluate the antitumor and chemopotentiating action of propranolol in a T cell lymphoma murine model. In this study, T cell lymphoma-bearing mice were treated with vehicle alone (PBS) or containing propranolol followed by administration of with or without cisplatin. The progression of the tumor was assessed along with analysis of tumor cell apoptosis, glucose metabolism, pH regulation, and antitumor immune response. The apoptosis was estimated by cellular and nuclear morphology analysis through Wright-Giemsa, annexin-V, and DAPI staining. ELISA was used to detect the epinephrine level in serum. The glucose, lactate, and NO levels were measured in the tumor ascitic fluid by calorimetric methods. RT-PCR and Western blot were used to assess the levels of various crucial regulators at gene and protein levels, respectively. Our results showed that propranolol exerts antitumor as well as chemopotentiating ability in DL-bearing mice by altering apoptosis, glycolysis, acidification of TME, and immunosuppression.

An enzyme-instructed self-assembly system induces tumor acidosis via sequential-dual effect for cancer selective therapy.

The acidosis anti-tumor therapy, based on the altered energy metabolism pathway of tumor cells, has been proposed as an attractive method for cancer selective treatment. However, the strategy of inducing tumor acidosis by using a single drug to simultaneously inhibit both lactate efflux and consumption has not been reported yet. Herein, an in situ enzyme-instructed self-assembly (EISA) system was rationally fabricated to induce tumor acidosis apoptosis for cancer selective therapy. Depending on the sequential effect of the in situ EISA system, the targeted drug was successively distributed on the membrane and intracellular, inhibiting MCT4 mediated lactate efflux and mitochondrial tricarboxylic acid (TCA) cycle mediated lactate consumption, respectively. Through the dual obstruction of lactate metabolism to trigger tumor acidosis, the in situ EISA nanomedicine showed selective growth and migration inhibition against cancer cells. In addition, the nanomedicine also displayed a radio-sensitization effect in vitro due to causing the mitochondrial dysfunction, and exhibited a prominent synergistic chemo-radiotherapy anti-tumor performance in vivo. Accordingly, this work demonstrated that the in situ EISA system could endow the LND with sequential-dual effects to induce tumor acidosis, which may provide an enlightening strategy for anticancer drug delivery and cancer selective therapy. STATEMENT OF SIGNIFICANCE: With the help of the sequential effect of in situ EISA , the serial attack of LND against different targets was effectively realized to induce tumor acidosis and combined chemo-radiotherapy, implying the importance of the relationship between structure and function, which could offer a distinctive inspiration for future drug delivery system design and anti-tumor application.