Usefulness of the preoperative inflammation-based prognostic score and the ratio of visceral fat area to psoas muscle area on predicting survival for surgically resected adenocarcinoma of the esophagogastric junction.

BACKGROUND: Sarcopenic obesity is associated with gastrointestinal cancer prognosis through systemic inflammation. However, in patients with adenocarcinoma of the esophagogastric junction (AEG), the relationship between the inflammation-based prognostic score (IBPS), muscle loss, visceral fat mass, and prognosis has not been sufficiently evaluated. We investigated the prognostic value of the preoperative IBPS and the visceral fat area ratio to the psoas muscle area (V/P ratio) in patients with AEG undergoing surgery. METHODS: We retrospectively analyzed 92 patients with AEG who underwent surgery. The prognostic value of the preoperative neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio (PLR), lymphocyte-to-monocyte ratio, systemic inflammation response index, C-reactive protein-to-albumin ratio, prognostic nutritional index, modified Glasgow Prognostic Score, and V/P ratio at the third lumbar vertebra was investigated using univariate and multivariate survival analyses. RESULTS: Multivariate analysis revealed that a high pathological stage (p = 0.0065), high PLR (p = 0.0421), and low V/P ratio (p = 0.0053) were independent prognostic factors for poor overall survival (OS). When restricted to patients with body mass index (BMI) ≥ 25 kg/m2, a high V/P ratio was a poor prognostic factor (p = 0.0463) for OS. Conversely, when restricted to patients with BMI < 25 kg/m2, a low V/P ratio was a poor prognostic factor (p = 0.0021) for OS. CONCLUSIONS: Both PLR and V/P ratios may be useful prognostic biomarkers in surgical cases of AEG. V/P ratio and BMI may provide an accurate understanding of the muscle and fat mass's precise nature and may help predict AEG prognosis.

Efficacy of thoracic endovascular aortic repair for aorto-esophageal fistula due to esophageal cancer: a systematic review and meta-analysis.

Aorto-esophageal fistula (AEF) due to esophageal cancer (EC) is a life-threatening condition characterized by sudden hemorrhage, which often causes sudden death. To evaluate the efficacy and safety of thoracic endovascular aortic repair (TEVAR) for AEF due to EC, we performed a systematic review and meta-analysis. We searched the MEDLINE (PubMed) databases, the Cochrane Library databases, Ichushi-Web (the databases of the Japan Medical Abstract Society), and CiNii (Academic information search service of the National Institute of Information from Japan) from January 2000 to November 2023 for articles about TEVAR for an emergent aortic hemorrhage (salvage TEVAR [S-TEVAR]), and the prophylactic procedure (P-TEVAR). Six studies (140 cases) were eligible for meta-analysis. The 90-day mortality of S-TEVAR and P-TEVAR was 40% (95% CI 23-60, I2 = 36%) and 8% (95% CI 3-17, I2 = 0%), respectively. Post-S-TEVAR hemorrhagic and infectious complications were 17% (95% CI 3-57, I2 = 71%) and 20% (95% CI 5-57, I2 = 66%), respectively. Post-P-TEVAR hemorrhagic and infectious complications were 2% (95% CI 0-10, I2 = 0%) and 3% (95% CI 1-12, I2 = 0%), respectively. TEVAR for AEF due to EC may be a useful therapeutic option to manage or prevent hemorrhagic oncological emergencies.

Anticancer effect of a pyrrole-imidazole polyamide-triphenylphosphonium conjugate selectively targeting a common mitochondrial DNA cancer risk variant in cervical cancer cells.

Cervical cancer remains a major threat to women's health, especially in countries with limited medical resources, and new drugs are needed to improve patient survival and minimize adverse effects. Here, we examine the effects of a triphenylphosphonium (TPP)-conjugated pyrrole-imidazole polyamide (CCC-h1005) targeting the common homoplasmic mitochondrial DNA (mtDNA) cancer risk variant (ATP6 8860A>G) on the survival of cervical cancer cell lines, cisplatin-resistant HeLa cells and patient-derived cervical clear cell carcinoma cells as models of cervical cancer treatment. We found that CCC-h1005 induced death in these cells and suppressed the growth of xenografted HeLa tumors with no severe adverse effects. These results suggest that PIP-TPP designed to target mtDNA cancer risk variants can be used to treat many cervical cancers harboring high copies of the target variant, providing a foundation for clinical trials of this class of molecules for treating cervical cancer and other types of cancers.

Infiltration of Gastric Cancer Stroma by Tumor-Infiltrating Lymphocytes Correlates with Mechanistic Target of Rapamycin Signaling.

INTRODUCTION: We investigated whether the infiltration of tumor-infiltrating lymphocytes (TILs) in gastric cancer (GC), as evaluated by hematoxylin and eosin (H&E) staining, could be a prognostic marker. We also explored on the relationship between TILs and mechanistic target of rapamycin (mTOR) and how it regulates immune effector responses in GC. METHODS: A total of 183 patients with available data on TIL were included. TIL infiltration was evaluated using H&E staining. We also conducted immunohistochemistry to determine mTOR expression. RESULTS: Positive TIL infiltration was defined as TILs ≥20%. There were 72 (39.3%) and 111 (60.7%) positive and negative cases, respectively. TILs positivity significantly correlated with both absence of lymph node metastasis (p = 0.037) and negative p-mTOR expression (p = 0.040). TIL infiltration correlated with a significantly better overall (p = 0.046) and disease-free (p = 0.020) survival. CONCLUSION: mTOR possibly suppresses TIL infiltration in GC. H&E staining is an effective tool for evaluating the immune status of GC patients. H&E staining may be used in clinical practice to monitor treatment response in GC.

Significance of Lipopolysaccharides in Gastric Cancer and Their Potential as a Biomarker for Nivolumab Sensitivity.

Lipopolysaccharides are a type of polysaccharide mainly present in the bacterial outer membrane of Gram-negative bacteria. Recent studies have revealed that lipopolysaccharides contribute to the immune response of the host by functioning as a cancer antigen. We retrospectively recruited 198 patients with gastric cancer who underwent surgery. The presence of lipopolysaccharides was determined using immunohistochemical staining, with the intensity score indicating positivity. The relationship between lipopolysaccharides and CD8, PD-L1, TGFBI (a representative downstream gene of TGF-ß signaling), wnt3a, and E-cadherin (epithelial-mesenchymal transition marker) was also investigated. Thereafter, we identified 20 patients with advanced gastric cancer receiving nivolumab and investigated the relationship between lipopolysaccharides and nivolumab sensitivity. After staining for lipopolysaccharides in the nucleus of cancer cells, 150 negative (75.8%) and 48 positive cases (24.2%) were found. The lipopolysaccharide-positive group showed increased cancer stromal TGFBI expression (p < 0.0001) and PD-L1 expression in cancer cells (p = 0.0029). Lipopolysaccharide positivity was significantly correlated with increased wnt3a signaling (p = 0.0028) and decreased E-cadherin expression (p = 0.0055); however, no significant correlation was found between lipopolysaccharide expression and overall survival rate (p = 0.71). In contrast, high TGFBI expression in the presence of LPS was associated with a worse prognosis than that in the absence of LPS (p = 0.049). Among cases receiving nivolumab, the lipopolysaccharide-negative and -positive groups had disease control rates of 66.7% and 11.8%, respectively (p = 0.088). Lipopolysaccharide positivity was associated with wnt3a, TGF-ß signaling, and epithelial-mesenchymal transition and was considered to tend to promote therapeutic resistance to nivolumab.

Preoperative evaluation of oral hygiene may predict the overall survival of patients with esophageal cancer.

BACKGROUND: Previously, the association between tooth loss and prognosis after esophagectomy was reported; however, the presence of periodontal disease has not been assessed. This study investigated the association between the degree of oral hygiene, as evaluated by tooth loss and periodontal disease, and the prognosis of patients with esophageal cancer. METHODS: A total of 163 esophageal cancer patients who underwent surgery with perioperative oral care and examination were enrolled. We assessed the periodontal pocket depth for the presence of periodontal disease and established a periodontal pocket index, defined as the sum of the periodontal pocket depth of the remaining tooth divided by the total count of the remaining teeth. Patients were divided into three groups: Group A (tooth loss < 13 and periodontal pocket index < 3.67); Group B (tooth loss < 13 and periodontal pocket index ≥ 3.67); and Group C (tooth loss ≥ 13). Overall survival and cancer-specific survival were analyzed, and a multivariate analysis was performed. RESULTS: There was a significant difference in the 5-year overall survival rates between the groups (A:B:C = 74.8%:62.8%:50.5%; p = 0.0098), but not in the 5-year cancer-specific survival rates (A:B:C = 80.2%:64.2%:62.2%; p = 0.0849). In multivariate analysis, oral hygiene (tooth loss < 13 and periodontal pocket index ≥ 3.67 + tooth loss ≥ 13; p = 0.041) was a significant independent poor prognostic factor for overall survival. CONCLUSIONS: Oral evaluation, focusing on tooth loss and periodontal disease, is meaningful in predicting the long-term prognosis of postoperative esophageal cancer patients.

Suppression of non-small-cell lung cancer A549 tumor growth by an mtDNA mutation-targeting pyrrole-imidazole polyamide-triphenylphosphonium and a senolytic drug.

Certain somatic mutations in mtDNA were associated with tumor progression and frequently found in a homoplasmic state. We recently reported that pyrrole-imidazole polyamide conjugated with the mitochondria-delivering moiety triphenylphosphonium (PIP-TPP) targeting an mtDNA mutation efficiently induced apoptosis in cancer cells with the mutation but not normal cells. Here, we synthesized the novel PIP-TPP, CCC-021-TPP, targeting ND6 14582A > G homoplasmic missense mutation that is suggested to enhance metastasis of non-small-cell lung cancer A549 cells. CCC-021-TPP did not induce apoptosis but caused cellular senescence in the cells, accompanied by a significant induction of antiapoptotic BCL-XL. Simultaneous treatment of A549 cells with CCC-021-TPP and the BCL-XL selective inhibitor A-1155463 resulted in apoptosis induction. Importantly, the combination induced apoptosis and suppressed tumor growth in an A549 xenografted model. These results highlight the potential of anticancer therapy with PIP-TPPs targeting mtDNA mutations to induce cell death even in apoptosis-resistant cancer cells when combined with senolytics.

Cell-Free Synthesis of Human Endothelin Receptors and Its Application to Ribosome Display.

Engineering G-protein-coupled receptors (GPCRs) for improved stability or altered function is of great interest, as GPCRs consist of the largest protein family, are involved in many important signaling pathways, and thus, are one of the major drug targets. Here, we report the development of a high-throughput screening method for GPCRs using a reconstituted in vitro transcription-translation (IVTT) system. Human endothelin receptor type-B (ETBR), a class A GPCR that binds endothelin-1 (ET-1), a 21-residue peptide hormone, was synthesized in the presence of nanodisc (ND) composed of a phospholipid, 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (POPG). The ET-1 binding of ETBR was significantly reduced or was undetectable when other phospholipids were used for ND preparation. However, when functional ETBR purified from Sf9 cells was reconstituted into NDs, ET-1 binding was observed with two different phospholipids tested, including POPG. These results suggest that POPG likely supports the folding of ETBR into its functional form in the IVTT system. Using the same conditions as ETBR, whose three-dimensional structure has been solved, human endothelin receptor type-A (ETAR), whose three-dimensional structure remains unsolved, was also synthesized in its functional form. By adding POPG-ND to the IVTT system, both ETAR and ETBR were successfully subjected to ribosome display, a method of in vitro directed evolution that facilitates the screening of up to 1012 mutants. Finally, using a mock library, we showed that ribosome display can be applied for gene screening of ETBR, suggesting that high-throughput screening and directed evolution of GPCRs is possible in vitro.

ASO Author Reflections: Impact of the Ratio of the Visceral Fat Area (VFA) to Psoas Muscle Area (PMA) (V/P Ratio) on Survival for Patients with Surgically Resected Esophageal Cancer.

PAST: The true impact of co-occurring muscle mass reduction and fat accumulation on patients with surgically resected esophageal cancer (EC) remains controversial. PRESENT: The current study defined reduction in muscle mass and excess body adiposity as the ratio of the visceral fat area (VFA) to the psoas muscle area (V/P ratio) on the same axial computed tomography slice at the third lumbar vertebra (L3). A high V/P ratio was associated with greater age (p = 0.03), higher body mass index (BMI) (p < 0.001), larger VFA (p < 0.001), and increased age-adjusted Charlson comorbidity index (ACCI) (p = 0.005). Multivariate analysis showed a high V/P ratio to be an independent prognostic factor for poor overall survival (OS) of EC patients who underwent surgery (p = 0.003). The prognostic value of the V/P ratio still was significant for EC patients with a BMI lower than 25 kg/m2. FUTURE: A high V/P ratio was an independent prognostic factor for OS of EC patients who underwent surgery, even BMI-defined non-obese EC patients. The V/P ratio as a surrogate marker of relative muscle mass reduction and fat accumulation may have prognostic value for EC patients regardless of body composition differences.

Impact of the Ratio of Visceral Fat Area (VFA) to Psoas Muscle Area (PMA) (V/P Ratio) on Survival for Surgically Resected Esophageal Cancer.

BACKGROUND: The synergic effects of muscle mass reduction with excess body adiposity in surgically resected esophageal cancer (EC) patients remains controversial, especially in non-obese patients. METHODS: One hundred and six patients with EC who underwent surgery between 2006 and 2014 were included in this study. Reduction in muscle mass and excess body adiposity were defined as the ratio of visceral fat area (VFA) to psoas muscle area (PMA) (V/P ratio) on the same axial computed tomography (CT) slice at the third lumbar vertebra (L3). RESULTS: A high V/P ratio was associated with greater age (p = 0.03), higher body mass index (BMI) (p < 0.001), higher VFA (p < 0.001), and increased age-adjusted Charlson comorbidity index (ACCI) (p = 0.005). Multivariate analysis revealed a high V/P ratio to be an independent prognostic factor for poor overall survival (OS) in EC patients who underwent surgery (p = 0.003). The prognostic value of the V/P ratio was still significant in EC patients with a BMI < 25. CONCLUSIONS: A high V/P ratio was associated with poor survival in surgically resected EC patients, even in non-obese patients. The V/P ratio as a surrogate marker of relative muscle mass reduction and fat accumulation may have prognostic value in EC patients regardless of body composition differences.

PROX1 Was Associated with LGR5 and Wnt Signaling and Contributed to Poor Prognosis in Gastric Cancer.

INTRODUCTION: We investigated whether the expression of prospero homeobox protein-1 (PROX1) in gastric cancer (GC) could be a prognostic marker. We also focused on the relationship between PROX1 and LGR5 and Wnt/ß-catenin activity in GC. METHODS: A total of 196 patients who underwent potentially curative surgery were collected and reviewed retrospectively. Immunohistochemistry was conducted and evaluated the expression PROX1, LGR5, Wnt3a, and ß-catenin expression. And we evaluated the relationship between PROX1 expression and clinicopathological features. RESULTS: The PROX1 low-expression group consisted of 105 patients (53.6%) and the high-expression group consisted of 91 patients (46.4%). For LGR5 expression, 76 patients (38.8%) were classified as low-expression, and 120 patients (61.2%) were classified as high-expression. The PROX1 low-expression group was significantly younger (p = 0.0095), had more intestinal type (p = 0.014), and had smaller tumor size (p = 0.013). The PROX1 high-expression group was significantly correlated with high LGR5 expression (p < 0.0001) and high Wnt3a expression (p = 0.012). In addition, there were significantly more cases of postoperative recurrence in the PROX1 high-expression group (p = 0.013). CONCLUSION: Our findings demonstrate that PROX1 correlated with the cancer stemness markers LGR5 and Wnt3a signaling in GC and had a poor prognosis including postoperative recurrence.

Preoperative Risk Factors and Prognostic Impact of Postoperative Complications Associated with Total Gastrectomy.

INTRODUCTION: We evaluated the risk factors for patients with gastric cancer (GC) undergoing total gastrectomy (TG) that predict postoperative complications, including anastomotic leakage, postoperative pneumonia, and heart disease. METHODS: We collected 106 patients who received TG for GC between May 2009 and May 2017 at Gunma University Graduate School of Medicine, including clinicopathologic, surgical, postoperative complication, laboratory test, and physiologic test data. RESULTS: Of 106 patients, 92 (86.8%) had no complications, and 14 (13.2%) had complications. Univariate analyses revealed that a high American Society of Anaesthesiologists physical status (ASA-PS) and neutrophil-lymphocyte ratio (NLR) of ≥3.5 significantly correlated with postoperative complications. Multivariate analyses showed that high ASA-PS was an independent prognostic factor of postoperative complications. The cancer recurrence rate was 34.8% in the noncomplication group and 71.4% in the complication group. CONCLUSION: Patients with postoperative complications are prone to recurrence and poor prognosis. For patients with high-risk GC with poor ASA-PS and high NLR, more thorough perioperative management is essential.

Mitochondria: Endosymbiont bacteria DNA sequence as a target against cancer.

As the energy factory for the cell, the mitochondrion, through its role of adenosine triphosphate production by oxidative phosphorylation, can be regarded as the guardian of well regulated cellular metabolism; the integrity of mitochondrial functions, however, is particularly vulnerable in cancer due to the lack of superstructures such as histone and lamina folds to protect the mitochondrial genome from unintended exposure, which consequently elevates risks of mutation. In cancer, mechanisms responsible for enforcing quality control surveillance for identifying and eliminating defective mitochondria are often poorly regulated, and certain uneliminated mitochondrial DNA (mtDNA) mutations and polymorphisms can be advantageous for the proliferation, progression, and metastasis of tumor cells. Such pathogenic mtDNA aberrations are likely to increase and occasionally be homoplasmic in cancer cells and, intriguingly, in normal cells in the proximity of tumor microenvironments as well. Distinct characteristics of these abnormalities in mtDNA may provide a new path for cancer therapy. Here we discuss a promising novel therapeutic strategy, using the sequence-specific properties of pyrrole-imidazole polyamide-triphenylphosphonium conjugates, against cancer for clearing abnormal mtDNA by reactivating mitochondrial quality control surveillance.

A PI polyamide-TPP conjugate targeting a mtDNA mutation induces cell death of cancer cells with the mutation.

Mitochondrial DNA (mtDNA) mutations occur frequently in cancer cells, and some of them are often homoplasmic. Targeting such mtDNA mutations could be a new method for killing cancer cells with minimal impact on normal cells. Pyrrole-imidazole polyamides (PIPs) are cell-permeable minor groove binders that show sequence-specific binding to double-stranded DNA and inhibit the transcription of target genes. PIP conjugated with the lipophilic triphenylphosphonium (TPP) cation can be delivered to mitochondria without uptake into the nucleus. Here, we investigated the feasibility of the use of PIP-TPP to target a mtDNA mutation in order to kill cancer cells that harbor the mutation. We synthesized hairpin-type PIP-TPP targeting the A3243G mutation and examined its effects on the survival of HeLa cybrid cells with or without the mutation (HeLamtA3243G cells or HeLamtHeLa cells, respectively). A surface plasmon resonance assay demonstrated that PIP-TPP showed approximately 60-fold higher binding affinity for the mutant G-containing synthetic double-stranded DNA than for the wild-type A-containing DNA. When added to cells, it localized in mitochondria and induced mitochondrial reactive oxygen species production, extensive mitophagy, and apoptosis in HeLamtA3243G cells, while only slightly exerting these effects in HeLamtHeLa cells. These results suggest that PIP-TPPs targeting mtDNA mutations could be potential chemotherapeutic drugs to treat cancers without severe adverse effects.

Targeting the mutant PIK3CA gene by DNA-alkylating pyrrole-imidazole polyamide in cervical cancer.

PIK3CA is the most frequently mutated oncogene in cervical cancer, and somatic mutations in the PIK3CA gene result in increased activity of PI3K. In cervical cancer, the E545K mutation in PIK3CA leads to elevated cell proliferation and reduced apoptosis. In the present study, we designed and synthesized a novel pyrrole-imidazole polyamide-seco-CBI conjugate, P3AE5K, to target the PIK3CA gene bearing the E545K mutation, rendered possible by nuclear access and the unique sequence specificity of pyrrole-imidazole polyamides. P3AE5K interacted with double-stranded DNA of the coding region containing the E545K mutation. When compared with conventional PI3K inhibitors, P3AE5K demonstrated strong cytotoxicity in E545K-positive cervical cancer cells at lower concentrations. PIK3CA mutant cells exposed to P3AE5K exhibited reduced expression levels of PIK3CA mRNA and protein, and subsequent apoptotic cell death. Moreover, P3AE5K significantly decreased the tumor growth in mouse xenograft models derived from PIK3CA mutant cells. Overall, the present data strongly suggest that the alkylating pyrrole-imidazole polyamide P3AE5K should be a promising new drug candidate targeting a constitutively activating mutation of PIK3CA in cervical cancer.

A linear five-ring pyrrole-imidazole polyamide-triphenylphosphonium conjugate targeting a mitochondrial DNA mutation efficiently induces apoptosis of HeLa cybrid cells carrying the mutation.

Somatic mutations in mitochondrial DNA may provide a new avenue for cancer therapy due to their associations to a number of cancers and a tendency of homoplasmicity. In consideration of mitochondrial features and its relatively small genome size, a nucleotide-based targeting approach is a considerably more promising option. To explore the efficacy of short linear N-methylpyrrole-N-methylimidazole polyamide (PI polyamide), we synthesized a five-ring short PI polyamide that provided sequence-specific homing for the A3243G mitochondrial mutation upon conjugation with triphenylphosphonium cation (TPP). This PI polyamide-TPP was able to induce cytotoxicity in HeLamtA3243G cybrid cells, while preserving preferential binding for oligonucleotides containing the A3243G motif from melting temperature assays. The PI polyamide-TPP also localized in the mitochondria in HeLamtA3243G cells and induced mitochondrial reactive oxygen species production, mitophagy and apoptosis in a mutation-specific fashion compared to the wild-type HeLamtHeLa cybrids; normal human dermal fibroblasts were also relatively unaffected to suggest discriminating selectivity for the mutant mitochondria, offering a novel outlook for cancer therapy via mitochondrial homing of short linear PIP-TPPs.

Bottom-up Creation of an Artificial Cell Covered with the Adhesive Bacterionanofiber Protein AtaA.

The bacterial cell surface structure has important roles for various cellular functions. However, research on reconstituting bacterial cell surface structures is limited. This study aimed to bottom-up create a cell-sized liposome covered with AtaA, the adhesive bacterionanofiber protein localized on the cell surface of Acinetobacter sp. Tol 5, without the use of the protein secretion and assembly machineries. Liposomes containing a benzylguanine derivative-modified phospholipid were decorated with a truncated AtaA protein fused to a SNAP-tag expressed in a soluble fraction in Escherichia coli. The obtained liposome showed a similar surface structure and function to that of native Tol 5 cells and adhered to both hydrophobic and hydrophilic solid surfaces. Furthermore, this artificial cell was able to drive an enzymatic reaction in the adhesive state. The developed artificial cellular system will allow for analysis of not only AtaA, but also other cell surface proteins under a cell-mimicking environment. In addition, AtaA-decorated artificial cells may inspire the development of biotechnological applications that require immobilization of cells onto a variety of solid surfaces, in particular, in environments where the use of genetically modified organisms is prohibited.

High expression of forkhead box protein C2 is associated with aggressive phenotypes and poor prognosis in clinical hepatocellular carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) is one of the major causes of tumor death; thus, the identification of markers related to its diagnosis and prognosis is critical. Previous studies have revealed that epithelial-to-mesenchymal transition (EMT) is involved in tumor invasion and metastasis, and the forkhead box protein C2 (FOXC2) has been shown to promote tumor cell proliferation, invasion, and EMT. In the present study, we examined the clinicopathological significance of FOXC2 and EMT-related markers in clinical HCC specimens and identified factors related to the diagnosis and prognosis of HCC. METHODS: The expression of FOXC2 and EMT-related markers was evaluated by immunohistochemistry in 84 cases of hepatocellular carcinoma. RESULTS: A high expression of FOXC2 was observed in 26 of 84 cases, and expression was significantly correlated with background liver cirrhosis, poor tumor differentiation, high serum AFP, and elevated cell proliferation markers. In addition, this high expression was related to the induction of the Cadherin switch and vimentin expression and was an independent predictor for poor prognosis. CONCLUSION: The high expression of FOXC2 in HCC is correlated with tumor malignancy and poor prognosis, suggesting that FOXC2 may be an important prognostic factor for HCC.

Hydrophobic structure of hairpin ten-ring pyrrole-imidazole polyamides enhances tumor tissue accumulation/retention in vivo.

To examine the hydrophobic structure of PI polyamides on tumor accumulation in vivo, PI polyamide-fluorescein conjugates 1-5 with the distinct number of N-methylimidazole (Im) units were synthesized. There existed an inverse relationship between the Im unit number of the compounds and their hydrophobicity. Compound 1 with one Im unit and 3 with three Im units accumulated and retained preferentially in tumor tissues compared to 5 with five Im units. These results suggest the importance of a PI polyamide's primary structure, which partly contributes to its hydrophobic property, on its accumulation and/or retention in tumor tissues in vivo.