Synergistic Effect of Motivation for the Elderly and Support for Going Out II: Measures to Induce Elderly Men to Go Out.

BACKGROUND: The second demonstration experiment of supporting elderly people going out with the Choisoko system was conducted. The first study showed that for women, friends, shopping, convenience, and events are factors that have the potential to be effective motivational factors for encouraging these women to go out. On the other hand, these factors did not lead to any behavioral change in men. Since there are approximately 15 million men over the age of 65 in Japan, behavioral changes in the entire elderly population will not occur without guidance for elderly men to go out. METHODS: Sixteen elderly men and forty-seven elderly women participated. Interestingly, men are far more passionate about games than women. Therefore, we hypothesized that a preference for games could be a hint as to how we might encourage older men to go out. Then, a second demonstration experiment was conducted, and we analyzed the relationship between six game preferences and the frequency of going out. RESULTS: Among gaming preferences, men with gaming preferences such as Philanthropists, Achievers, and Free Spirits showed a tendency to go out. CONCLUSIONS: These stimuli may have the potential to be factors that may encourage elderly men to go out.

Synergistic Effect of Motivation for the Elderly and Support for Going out.

Maintaining a social environment that enables going out freely is important for older people and aids the prevention of frailty syndrome. However, losing a driver's license can increase the long-term care needs of older people. Therefore, outing support systems are important. However, the utilization rate of these systems is currently relatively low. We conducted a demonstration experiment among older people aged 70 years and over, living in Iruma City, Saitama Japan, by implementing the Choisoko outing support system developed by Aisin Co., Ltd., in conjunction with an approach for improving motivation. Using this system, elderly people were able to go shopping freely whenever they chose, without a driver's license. Participants in the demonstration experiment exhibited higher Functional Independence Measure scores after the intervention, irrespective of whether or not they used the Choisoko system. The number of uses per person increased over time, and the subjective well-being of Choisoko users improved. However, few male participants engaged with the system. Although improving motivation is important for inducing positive behaviors and enabling the elderly to go out, motivation-improving factors differ between men and women.

The NOTCH-FOXM1 Axis Plays a Key Role in Mitochondrial Biogenesis in the Induction of Human Stem Cell Memory-like CAR-T Cells.

Recent studies have shown that stem cell memory T (TSCM) cell-like properties are important for successful adoptive immunotherapy by the chimeric antigen receptor-engineered-T (CAR-T) cells. We previously reported that both human and murine-activated T cells are converted into stem cell memory-like T (iTSCM) cells by coculture with stromal OP9 cells expressing the NOTCH ligand. However, the mechanism of NOTCH-mediated iTSCM reprogramming remains to be elucidated. Here, we report that the NOTCH/OP9 system efficiently converted conventional human CAR-T cells into TSCM-like CAR-T, "CAR-iTSCM" cells, and that mitochondrial metabolic reprogramming played a key role in this conversion. NOTCH signaling promoted mitochondrial biogenesis and fatty acid synthesis during iTSCM formation, which are essential for the properties of iTSCM cells. Forkhead box M1 (FOXM1) was identified as a downstream target of NOTCH, which was responsible for these metabolic changes and the subsequent iTSCM differentiation. Like NOTCH-induced CAR-iTSCM cells, FOXM1-induced CAR-iTSCM cells possessed superior antitumor potential compared with conventional CAR-T cells. We propose that NOTCH- or FOXM1-driven CAR-iTSCM formation is an effective strategy for improving cancer immunotherapy. SIGNIFICANCE: Manipulation of signaling and metabolic pathways important for directing production of stem cell memory-like T cells may enable development of improved CAR-T cells.

Gold-nanofève surface-enhanced Raman spectroscopy visualizes hypotaurine as a robust anti-oxidant consumed in cancer survival.

Gold deposition with diagonal angle towards boehmite-based nanostructure creates random arrays of horse-bean-shaped nanostructures named gold-nanofève (GNF). GNF generates many electromagnetic hotspots as surface-enhanced Raman spectroscopy (SERS) excitation sources, and enables large-area visualization of molecular vibration fingerprints of metabolites in human cancer xenografts in livers of immunodeficient mice with sufficient sensitivity and uniformity. Differential screening of GNF-SERS signals in tumours and those in parenchyma demarcated tumour boundaries in liver tissues. Furthermore, GNF-SERS combined with quantum chemical calculation identified cysteine-derived glutathione and hypotaurine (HT) as tumour-dominant and parenchyma-dominant metabolites, respectively. CD44 knockdown in cancer diminished glutathione, but not HT in tumours. Mechanisms whereby tumours sustained HT under CD44-knockdown conditions include upregulation of PHGDH, PSAT1 and PSPH that drove glycolysis-dependent activation of serine/glycine-cleavage systems to provide one-methyl group for HT synthesis. HT was rapidly converted into taurine in cancer cells, suggesting that HT is a robust anti-oxidant for their survival under glutathione-suppressed conditions.

Cystathionine ß-synthase and PGRMC1 as CO sensors.

Heme oxygenase (HO) is a mono-oxygenase utilizing heme and molecular oxygen (O2) as substrates to generate biliverdin-IXα and carbon monoxide (CO). HO-1 is inducible under stress conditions, while HO-2 is constitutive. A balance between heme and CO was shown to regulate cell death and survival in many experimental models. However, direct molecular targets to which CO binds to regulate cellular functions remained to be fully examined. We have revealed novel roles of CO-responsive proteins, cystathionine ß-synthase (CBS) and progesterone receptor membrane component 1 (PGRMC1), in regulating cellular functions. CBS possesses a prosthetic heme that allows CO binding to inhibit the enzyme activity and to regulate H2S generation and/or protein arginine methylation. On the other hand, in response to heme accumulation in cells, PGRMC1 forms a stable dimer through stacking interactions of two protruding heme molecules. Heme-mediated PGRMC1 dimerization is necessary to interact with EGF receptor and cytochromes P450 that determine cell proliferation and xenobiotic metabolism. Furthermore, CO interferes with PGRMC1 dimerization by dissociating the heme stacking, and thus results in modulation of cell responses. This article reviews the intriguing functions of these two proteins in response to inducible and constitutive levels of CO with their pathophysiological implications.

The EGF Receptor Promotes the Malignant Potential of Glioma by Regulating Amino Acid Transport System xc(-).

Extracellular free amino acids contribute to the interaction between a tumor and its microenvironment through effects on cellular metabolism and malignant behavior. System xc(-) is composed of xCT and CD98hc subunits and functions as a plasma membrane antiporter for the uptake of extracellular cystine in exchange for intracellular glutamate. Here, we show that the EGFR interacts with xCT and thereby promotes its cell surface expression and function in human glioma cells. EGFR-expressing glioma cells manifested both enhanced antioxidant capacity as a result of increased cystine uptake, as well as increased glutamate, which promotes matrix invasion. Imaging mass spectrometry also revealed that brain tumors formed in mice by human glioma cells stably overexpressing EGFR contained higher levels of reduced glutathione compared with those formed by parental cells. Targeted inhibition of xCT suppressed the EGFR-dependent enhancement of antioxidant capacity in glioma cells, as well as tumor growth and invasiveness. Our findings establish a new functional role for EGFR in promoting the malignant potential of glioma cells through interaction with xCT at the cell surface. Cancer Res; 76(10); 2954-63. ©2016 AACR.

Haem-dependent dimerization of PGRMC1/Sigma-2 receptor facilitates cancer proliferation and chemoresistance.

Progesterone-receptor membrane component 1 (PGRMC1/Sigma-2 receptor) is a haem-containing protein that interacts with epidermal growth factor receptor (EGFR) and cytochromes P450 to regulate cancer proliferation and chemoresistance; its structural basis remains unknown. Here crystallographic analyses of the PGRMC1 cytosolic domain at 1.95 Å resolution reveal that it forms a stable dimer through stacking interactions of two protruding haem molecules. The haem iron is five-coordinated by Tyr113, and the open surface of the haem mediates dimerization. Carbon monoxide (CO) interferes with PGRMC1 dimerization by binding to the sixth coordination site of the haem. Haem-mediated PGRMC1 dimerization is required for interactions with EGFR and cytochromes P450, cancer proliferation and chemoresistance against anti-cancer drugs; these events are attenuated by either CO or haem deprivation in cancer cells. This study demonstrates protein dimerization via haem-haem stacking, which has not been seen in eukaryotes, and provides insights into its functional significance in cancer.

Impacts of CD44 knockdown in cancer cells on tumor and host metabolic systems revealed by quantitative imaging mass spectrometry.

CD44 expressed in cancer cells was shown to stabilize cystine transporter (xCT) that uptakes cystine and excretes glutamate to supply cysteine as a substrate for reduced glutathione (GSH) for survival. While targeting CD44 serves as a potentially therapeutic stratagem to attack cancer growth and chemoresistance, the impact of CD44 targeting in cancer cells on metabolic systems of tumors and host tissues in vivo remains to be fully determined. This study aimed to reveal effects of CD44 silencing on alterations in energy metabolism and sulfur-containing metabolites in vitro and in vivo using capillary electrophoresis-mass spectrometry and quantitative imaging mass spectrometry (Q-IMS), respectively. In an experimental model of xenograft transplantation of human colon cancer HCT116 cells in superimmunodeficient NOG mice, snap-frozen liver tissues containing metastatic tumors were examined by Q-IMS. As reported previously, short hairpin CD44 RNA interference (shCD44) in cancer cells caused significant regression of tumor growth in the host liver. Under these circumstances, the CD44 knockdown suppressed polyamines, GSH and energy charges not only in metastatic tumors but also in the host liver. In culture, HCT116 cells treated with shCD44 decreased total amounts of methionine-pool metabolites including spermidine and spermine, and reactive cysteine persulfides, suggesting roles of these metabolites for cancer growth. Collectively, these results suggest that CD44 expressed in cancer accounts for a key regulator of metabolic interplay between tumor and the host tissue.

Bevacizumab terminates homeobox B9-induced tumor proliferation by silencing microenvironmental communication.

BACKGROUND: Homeobox B9 (HOXB9), a transcriptional factor, regulates developmental processes and tumor progression and has recently been recognized as one of important transcriptional factors related to angiogenesis. This study aimed to investigate the role of HOXB9 in tumorigenesis and angiogenesis. METHODS: We examined the expression of HOXB9 in colorectal cancer using qPCR and in situ hybridization. We also examined the effect of HOXB9 overexpression in colorectal cancer using a proliferation assay, ELISA, a multiplex assay, and xenograft models. The clinical significance of HOXB9 was statistically evaluated in resected specimens. RESULTS: HOXB9 was expressed in colorectal cancer specimens. HOXB9 induced angiogenesis and tumor proliferation in vitro, which resulted in high tumorigenicity in vivo and poor overall survival. Bevacizumab, an anti-vascular endothelial growth factor (VEGF) antibody, remarkably suppressed tumor proliferation by inhibiting angiogenesis in HOXB9-overexpressing xenografts, and it improved overall survival and provided prolonged progression-free survival in HOXB9-overexpressing patients. A comprehensive multiplex assay of the supernatant of cancer cells co-cultured with human vascular endothelial cells and fibroblasts indicated significantly higher interleukin-6 (IL6) levels than those in the supernatant of monocultured cells. HOXB9 overexpression in clinical specimens was significantly correlated with increased IL6 expression. An IL6-neutralizing antibody inhibited VEGF secretion and tumor proliferation in the co-culture system. CONCLUSIONS: HOXB9 promotes the secretion of angiogenic factors, including VEGF, to induce tumor proliferation through microenvironmental production of cytokines including IL6 signaling. Moreover, silencing of VEGF or IL6 terminates cytokine release in tumor microenvironment. Thus, HOXB9 and IL6 may be potential biomarkers for bevacizumab treatment.

Reduced methylation of PFKFB3 in cancer cells shunts glucose towards the pentose phosphate pathway.

Haem oxygenase (HO)-1/carbon monoxide (CO) protects cancer cells from oxidative stress, but the gas-responsive signalling mechanisms remain unknown. Here we show using metabolomics that CO-sensitive methylation of PFKFB3, an enzyme producing fructose 2,6-bisphosphate (F-2,6-BP), serves as a switch to activate phosphofructokinase-1, a rate-limiting glycolytic enzyme. In human leukaemia U937 cells, PFKFB3 is asymmetrically di-methylated at R131 and R134 through modification by protein arginine methyltransferase 1. HO-1 induction or CO results in reduced methylation of PFKFB3 in varied cancer cells to suppress F-2,6-BP, shifting glucose utilization from glycolysis toward the pentose phosphate pathway. Loss of PFKFB3 methylation depends on the inhibitory effects of CO on haem-containing cystathionine ß-synthase (CBS). CBS modulates remethylation metabolism, and increases NADPH to supply reduced glutathione, protecting cells from oxidative stress and anti-cancer reagents. Once the methylation of PFKFB3 is reduced, the protein undergoes polyubiquitination and is degraded in the proteasome. These results suggest that the CO/CBS-dependent regulation of PFKFB3 methylation determines directional glucose utilization to ensure resistance against oxidative stress for cancer cell survival.

Microscopic imaging mass spectrometry assisted by on-tissue chemical derivatization for visualizing multiple amino acids in human colon cancer xenografts.

Imaging MS combined with CE/MS serves as a method to provide semi-quantitative and spatial information of small molecular metabolites in tissue slices. However, not all metabolites including amino acids have fully been visualized, because of low-ionization efficiency in MALDI MS. This study aimed to acquire semi-quantitative spatial information for multiple amino acids in frozen tissue slices. As a derivatization reagent, p-N,N,N-trimethylammonioanilyl N'-hydroxysuccinimidyl carbamate iodide (TAHS) was applied to increase their ionization efficiency and detection sensitivity. Semi-quantitative MALDI-imaging MS allowed us to visualize and quantify free amino acid pools in human colon cancer xenografts using a model of liver metastases in super-immunodeficient NOD/scid/γ(null) mice (NOG mice). Because the m/z values of several TAHS-derivatized amino acids overlap with those of the 2,5-dihydroxybenzoic acid background and other endogenous compounds, we imaged them with tandem MS. The results indicated that regional contents of glutamate, glutamine, glycine, leucine/isoleucine/hydroxyproline, phenylalanine, and alanine were significantly elevated in metastatic tumors versus parenchyma of tumor-bearing livers. On-tissue TAHS derivatization thus serves as a useful method to detect alterations in many amino acid levels in vivo, thereby enabling understanding of the spatial alterations of these metabolites under varied disease conditions including cancer.

Lewis lung carcinoma progression is facilitated by TIG-3 fibroblast cells.

BACKGROUND: The interactions of tumor cells with stromal fibroblasts influence tumor biology, but the exact mechanisms involved are still unclear. In the present study, we evaluated the effects of a human lung fibroblast cell line, TIG-3, on Lewis lung carcinoma (LLC) cells both in vitro and in vivo. MATERIALS AND METHODS: LLC and TIG-3 cells were co-cultured/co-implanted in vitro and in vivo. Cell invasion was assayed. Local tumor growth, as well as lung metastasis, were evaluated after subcutaneous cell co-implantation into NOD/SCID/γ-null (NOG) mice. LLC, and TIG-3 cells were pre-treated with either SB431542, a small molecule TGF-ß receptor antagonist, or siRNA for transforming growth factor (TGF)-ß before co-culture or co-implantation, and the effects of pre-treatments were compared both in cell culture and in mice. RESULTS: Subcutaneous LLC tumor growth (L group) in NOG mice was significantly increased by co-implantation of TIG-3 cells (L+T group) at four weeks. The number of macroscopic lung metastases was also significantly increased in the L+T group in comparison to the L group. In vitro cell invasion was significantly increased in the L+T group in comparison to the L group. In vitro expression of phosphorylated-SMAD3 was significantly increased in the L+T group in comparison to the L group. Furthermore, pre-treatment with either SB431542 or siRNA for TGF-ß reduced the invasiveness both in culture and in mice. CONCLUSION: This study suggested that in vitro as well as in vivo progression of LLC was facilitated by co-culture/co-implantation with TIG-3 cells, and that this process was at least in part dependent on TGF-ß-mediated interactions.

Energy management by enhanced glycolysis in G1-phase in human colon cancer cells in vitro and in vivo.

UNLABELLED: Activation of aerobic glycolysis in cancer cells is well known as the Warburg effect, although its relation to cell- cycle progression remains unknown. In this study, human colon cancer cells were labeled with a cell-cycle phase-dependent fluorescent marker Fucci to distinguish cells in G1-phase and those in S + G2/M phases. Fucci-labeled cells served as splenic xenograft transplants in super-immunodeficient NOG mice and exhibited multiple metastases in the livers, frozen sections of which were analyzed by semiquantitative microscopic imaging mass spectrometry. Results showed that cells in G1-phase exhibited higher concentrations of ATP, NADH, and UDP-N-acetylglucosamine than those in S and G2-M phases, suggesting accelerated glycolysis in G1-phase cells in vivo. Quantitative determination of metabolites in cells synchronized in S, G2-M, and G1 phases suggested that efflux of lactate was elevated significantly in G1-phase. By contrast, ATP production in G2-M was highly dependent on mitochondrial respiration, whereas cells in S-phase mostly exhibited an intermediary energy metabolism between G1 and G2-M phases. Isogenic cells carrying a p53-null mutation appeared more active in glycolysis throughout the cell cycle than wild-type cells. Thus, as the cell cycle progressed from G2-M to G1 phases, the dependency of energy production on glycolysis was increased while the mitochondrial energy production was reciprocally decreased. IMPLICATIONS: These results shed light on distinct features of the phase-specific phenotypes of metabolic systems in cancer cells.

Alternative splicing of CD44 mRNA by ESRP1 enhances lung colonization of metastatic cancer cell.

In cancer metastasis, various environmental stressors attack the disseminating cells. The successful colonization of cancer cells in secondary sites therefore requires the ability of the cells to avoid the consequences of such exposure to the stressors. Here we show that orthotopic transplantation of a CD44 variant isoform-expressing (CD44v(+)) subpopulation of 4T1 breast cancer cells, but not that of a CD44v(-) subpopulation, in mice results in efficient lung metastasis accompanied by expansion of stem-like cancer cells. Such metastasis is dependent on the activity of the cystine transporter xCT, and the stability of this protein is controlled by CD44v. We find that epithelial splicing regulatory protein 1 regulates the expression of CD44v, and knockdown of epithelial splicing regulatory protein 1 in CD44v(+) cells results in an isoform switch from CD44v to CD44 standard (CD44s), leading to reduced cell surface expression of xCT and suppression of lung colonization. The epithelial splicing regulatory protein 1-CD44v-xCT axis is thus a potential therapeutic target for the prevention of metastasis.

Modulation of glucose metabolism by CD44 contributes to antioxidant status and drug resistance in cancer cells.

An increased glycolytic flux accompanied by activation of the pentose phosphate pathway (PPP) is implicated in chemoresistance of cancer cells. In this study, we found that CD44, a cell surface marker for cancer stem cells, interacts with pyruvate kinase M2 (PKM2) and thereby enhances the glycolytic phenotype of cancer cells that are either deficient in p53 or exposed to hypoxia. CD44 ablation by RNA interference increased metabolic flux to mitochondrial respiration and concomitantly inhibited entry into glycolysis and the PPP. Such metabolic changes induced by CD44 ablation resulted in marked depletion of cellular reduced glutathione (GSH) and increased the intracellular level of reactive oxygen species in glycolytic cancer cells. Furthermore, CD44 ablation enhanced the effect of chemotherapeutic drugs in p53-deficient or hypoxic cancer cells. Taken together, our findings suggest that metabolic modulation by CD44 is a potential therapeutic target for glycolytic cancer cells that manifest drug resistance.

The cytostatic effects of lovastatin on ACC-MESO-1 cells.

BACKGROUND: Malignant pleural mesothelioma is known to be widely resistant to therapy, and new treatment strategies are needed. Statins are small molecules that suppress the production of multiple hydrophobic substrates in the mevalonate pathway. Although still controversial, statins may decrease the risk of certain cancers such as colon cancer, lung cancer, and prostate cancer. Since the evaluations of the direct effect of statins on malignant mesothelioma are still few, the present study was done to evaluate the effects of lovastatin on ACC-MESO-1 cells in vivo and to investigate the potential mechanisms involved in vitro. MATERIALS AND METHODS: The in vivo effect of lovastatin was evaluated using an NOD/SCID/γnull (NOG) mouse model of human malignant mesothelioma using ACC-MESO-1 cells. Lovastatin was also applied to ACC-MESO-1 cells in vitro and the effects were observed. RESULTS: Lovastatin administration reduced primary tumor and metastasis in the NOG mouse model of human malignant mesothelioma. In vitro studies showed that lovastatin administration induced cytostatic effects as per reduced cell viability and cell migration in ACC-MESO-1 cells. These effects were suggested to be dependent on autophagic changes rather than apoptosis. Furthermore, induction of autophagic changes by lovastatin in ACC-MESO-1 cells was independent of mTOR, and was considered to be dependent at least in part on Rac/phospholipase C/ inositol 1,4,5-triphosphate axis. CONCLUSIONS: These results suggest that it may be possible to utilize statins, or other pharmacological agents that are known to induce mTOR-independent autophagy, as an adjunct to standard treatments in malignant mesothelioma.

Semi-quantitative analyses of metabolic systems of human colon cancer metastatic xenografts in livers of superimmunodeficient NOG mice.

Analyses of energy metabolism in human cancer have been difficult because of rapid turnover of the metabolites and difficulties in reducing time for collecting clinical samples under surgical procedures. Utilization of xenograft transplantation of human-derived colon cancer HCT116 cells in spleens of superimmunodeficient NOD/SCID/IL-2Rγ(null) (NOG) mice led us to establish an experimental model of hepatic micrometastasis of the solid tumor, whereby analyses of the tissue sections collected by snap-frozen procedures through newly developed microscopic imaging mass spectrometry (MIMS) revealed distinct spatial distribution of a variety of metabolites. To perform intergroup comparison of the signal intensities of metabolites among different tissue sections collected from mice in fed states, we combined matrix-assisted laser desorption/ionization time-of-flight imaging mass spectrometry (MALDI-TOF-IMS) and capillary electrophoresis-mass spectrometry (CE-MS), to determine the apparent contents of individual metabolites in serial tissue sections. The results indicated significant elevation of ATP and energy charge in both metastases and the parenchyma of the tumor-bearing livers. To note were significant increases in UDP-N-acetyl hexosamines, and reduced and oxidized forms of glutathione in the metastatic foci versus the liver parenchyma. These findings thus provided a potentially important method for characterizing the properties of metabolic systems of human-derived cancer and the host tissues in vivo.

CD44 variant regulates redox status in cancer cells by stabilizing the xCT subunit of system xc(-) and thereby promotes tumor growth.

CD44 is an adhesion molecule expressed in cancer stem-like cells. Here, we show that a CD44 variant (CD44v) interacts with xCT, a glutamate-cystine transporter, and controls the intracellular level of reduced glutathione (GSH). Human gastrointestinal cancer cells with a high level of CD44 expression showed an enhanced capacity for GSH synthesis and defense against reactive oxygen species (ROS). Ablation of CD44 induced loss of xCT from the cell surface and suppressed tumor growth in a transgenic mouse model of gastric cancer. It also induced activation of p38(MAPK), a downstream target of ROS, and expression of the gene for the cell cycle inhibitor p21(CIP1/WAF1). These findings establish a function for CD44v in regulation of ROS defense and tumor growth.

Paradoxical ATP elevation in ischemic penumbra revealed by quantitative imaging mass spectrometry.

Local responses of energy metabolism during brain ischemia are too heterogeneous to decipher redox distribution between anoxic core and adjacent salvageable regions such as penumbra. Imaging mass spectrometry combined by capillary electrophoresis/mass spectrometry providing quantitative metabolomics revealed spatio-temporal changes in adenylates and NADH in a mouse middle-cerebral artery occlusion model. Unlike the core where ATP decreased, the penumbra displayed paradoxical elevation of ATP despite the constrained blood supply. It is noteworthy that the NADH elevation in the ischemic region is clearly demarcated by the ATP-depleting core. Results suggest that metabolism in ischemic penumbra does not respond passively to compromised circulation, but actively compensates energy charges.

Phosphorescence-assisted microvascular O(2) measurements reveal alterations of oxygen demand in human metastatic colon cancer in the liver of superimmunodeficient NOG mice.

We aimed to examine metabolism of human cancer in vivo and utilized superimmunodeficient NOG mice as an experimental model of hepatic metastasis, where human colon cancer cell line HCT116 transfected with Venus, the mutant GFP was injected intrasplenically. The mice were pretreated with Pd-porphyrin to quantify local O(2) tension through intravital phosphorescence assay. In this model, a majority of metastatic foci occurred in periportal regions but not in central regions. At 1 week after the transplantation, a PO(2) drop in periportal regions was minimal without any notable decrease in microvascular blood flow. Under these conditions, there was a negative correlation between the size of metastatic foci and the lobular O(2) consumption, suggesting that the tumor O(2) consumption is smaller than that in the residual liver. At 2 weeks, portal PO(2) was significantly smaller than controls, while the central PO(2) was not comparably decreased, indicating that metastatic foci increased the O(2) consumption, while the residual liver decreased it. These results suggest metastatic tumors derived from human colon cancer exhibit notable aerobic metabolism during their developmental process, compromising respiration of the rest of the tissue regenerated during tumor development.