Molecular imaging of aberrant crypt foci in the human colon targeting glutathione S-transferase P1-1

Role of the intestinal microbiota and diet in the onset and progression of colorectal and breast cancers and the interconnection between both types of tumours

Colorectal cancer (CRC) is among the leading causes of mortality in adults of both sexes worldwide, while breast cancer (BC) is among the leading causes of death in women. In addition to age, gender, and genetic predisposition, environmental and lifestyle factors exert a strong influence. Global diet, including alcohol consumption, is one of the most important modifiable factors affecting the risk of CRC and BC. Western dietary patterns promoting high intakes of xenobiotics from food processing and ethanol have been associated with increased cancer risk, whereas the Mediterranean diet, generally leading to a higher intake of polyphenols and fibre, has been associated with a protective effect. Gut dysbiosis is a common feature in CRC, where the usual microbiota is progressively replaced by opportunistic pathogens and the gut metabolome is altered. The relationship between microbiota and BC has been less studied. The estrobolome is the collection of genes from intestinal bacteria that can metabolize oestrogens. In a dysbiosis condition, microbial deconjugating enzymes can reactivate conjugated-deactivated oestrogens, increasing the risk of BC. In contrast, intestinal microorganisms can increase the biological activity and bioavailability of dietary phytochemicals through diverse microbial metabolic transformations, potentiating their anticancer activity. Members of the intestinal microbiota can increase the toxicity of xenobiotics through metabolic transformations. However, most of the microorganisms involved in diet-microbiota interactions remain poorly characterized. Here, we provide an overview of the associations between microbiota and diet in BC and CRC, considering the diverse types and heterogeneity of these cancers and their relationship between them and with gut microbiota.

Urokinase-type plasminogen activator blockade ameliorates experimental colitis in mice

Although several angiogenesis-related factors are reportedly involved in the pathogenesis of ulcerative colitis (UC), the mechanisms by which they contribute to disease are unclear. We first examined the expression of angiogenesis-related factors in inflamed colorectal tissue of UC patients using antibody array, and identified the 5 factors with highest expression, which included matrix metalloproteinase-8, urokinase-type plasminogen activator (uPA), angiostatin/plasminogen, hepatocyte growth factor and endoglin. Subsequent real-time PCR experiments using additional colorectal tissues revealed that uPA mRNA levels were significantly higher in inflamed tissues than in non-inflamed tissues, and significantly correlated with the severity of UC. Mirror section immunohistochemistry revealed that uPA was expressed in the neutrophils of inflamed colorectal tissues. We administered dextran sulfate sodium (DSS) in drinking water to uPA knockout (uPA^-/-) mice, and found that the disease activity index in uPA^-/- mice was marginally lower and the histological score in uPA^-/- mice was significantly lower than those in wild-type mice, suggesting the importance of uPA in colitis. When an uPA-selective inhibitor, UK122, was administered to DSS-treated C57BL6J mice, the disease activity index and histological score in those mice were significantly lower compared with control mice. Multiple cytokine/chemokine assay using colorectal tissues from uPA^-/- and UK122-treated mice revealed significantly lowered level of RANTES. In conclusion, uPA was highly expressed in neutrophils of the inflamed mucosa of UC patients, and the expression level correlated with the severity of UC. Genetic uPA deletion or pharmacological uPA blockade significantly ameliorated colitis in mice, concomitant with downregulation of RANTES.

Improving reactivity of naphthalimide-based GST probe by imparting TPP cation: Development and application for live cell imaging

Glutathione S-transferases (GSTs) are a superfamily of multifunctional enzymes comprising multiple classes and subtypes. This paper describes the synthesis and characterization of TPPBN-1, a naphthalimide derivative conjugated with a triphenylphosphonium (TPP) cation. When 4-bromonaphthalimide (BrNaph), a previously characterized GST substrate, was conjugated to a TPP cation, the conjugate showed increased reactivity towards most alpha- and mu-class GSTs, particularly the GSTA2 subtype, compared to the parent compound, but hardly towards Pi-class GSTs. Using this probe with enhanced reactivity, the enzymatic activity of endogenous GSTA1/2 in HepG2 cells was visualized by confocal fluorescence microscopy. The results demonstrated that modification with TPP cations, which are often used as tags for targeting mitochondria, can be used to enhance the reactivity of probes for specific GST subtypes.

TIMP1 promotes cell proliferation and invasion capability of right-sided colon cancers via the FAK/Akt signaling pathway

Although right-sided colorectal cancer (CRC) shows a worse prognosis than left-sided CRC, the underlying mechanism remains unclear. We established patient-derived organoids (PDOs) from left- and right-sided CRCs and directly compared cell proliferation and invasion capability between them. We then analyzed the expression of numerous genes in signal transduction pathways to clarify the mechanism of the differential prognosis. Cell proliferation activity and invasion capability in right-sided cancer PDOs were significantly higher than in left-sided cancer PDOs and normal PDOs, as revealed by Cell Titer Glo and transwell assays, respectively. We then used quantitative RT-PCR to compare 184 genes in 30 pathways among right-sided and left-sided cancer and normal PDOs and found that the TIMP1 mRNA level was highest in right-sided PDOs. TIMP1 protein levels were upregulated in right-sided PDOs compared with normal PDOs but was downregulated in left-sided PDOs. TIMP1 knockdown with shRNA significantly decreased cell proliferation activity and invasion capability in right-sided PDOs but not in left-sided PDOs. Moreover, TIMP1 knockdown significantly decreased pFAK and pAkt expression levels in right-sided PDOs but not in left-sided PDOs. A database analysis of The Cancer Genome Atlas revealed that TIMP1 expression in right-sided CRCs was significantly higher than in left-sided CRCs. Kaplan-Meier survival analysis showed significantly shorter overall survival in high-TIMP1 patients versus low-TIMP1 patients with right-sided CRCs but not left-sided CRCs. Our data suggest that TIMP1 is overexpressed in right-sided CRCs and promotes cell proliferation and invasion capability through the TIMP1/FAK/Akt pathway, leading to a poor prognosis. The TIMP1/FAK/Akt pathway can be a target for therapeutic agents in right-sided CRCs.

Pi-class Glutathione S-transferase (GSTP1)-selective fluorescent probes for multicolour imaging with various cancer-associated enzymes

Pi-class glutathione S-transferase (GSTP1) is highly expressed in a wide variety of human cancer tissues compared to the corresponding normal counterpart. Therefore, GSTP1 is a potential target enzyme for overcoming resistance to chemotherapeutic agents or visualizing specific lesions such as cancer. Here, we present orange and red fluorescence-emitting probes selective for GSTP1. Carbofluorescein and TokyoMagenta fluorophores were modified with a previously described GSTP1-selective chromogenic compound to generate orange and red fluorescence probes, respectively. Of these probes, Ps-CF , the orange fluorescence-emitting probe, was confirmed to be highly specific for detecting GSTP1 exogenously or endogenously expressed in various cancer cells. Additionally, it was demonstrated that Ps-CF is applicable for the simultaneous detection of GSTP1 and another cancer-associated enzymes by using a green fluorescence emitting γ-glutamyl transpeptidase (GGT) probe. In conclusion, the fluorescent probes developed in this study enable the simultaneous detection of multiple tumour markers such as GSTP1 with other cancer-associated enzymes by the concurrent use of spectrally distinguished fluorescent probes, potentially broadening the scope of cancer detection.

Recent Advances in Molecular Imaging of Colorectal Tumors

BACKGROUND

Recent endoscopic studies have revealed that small colorectal tumors are often overlooked during colonoscopy, indicating that more sensitive detection methods are needed.

SUMMARY

Molecular imaging has received considerable attention as a new endoscopic technique with high sensitivity. It generally employs a fluorescence-labeled compound that specifically binds to a molecule on the tumor. Fluorescent probes for molecular imaging are largely classified as 2 types: a fluorescence-labeled antibody targeting a molecule specifically expressed on the tumor cell surface such as epidermal growth factor receptor or vascular endothelial growth factor (VEGF); and a fluorescence-labeled small molecule compound targeting a molecule specifically expressed in tumor cells including c-Met, glutathione S-transferase, γ-glutamyltranspeptidase, cathepsin, or endothelin A receptor. These probes successfully detected colorectal tumors in several animal studies. Moreover, 3 recent human clinical trials evaluating endoscopic molecular imaging for colorectal tumors have been reported. In one study, a Cy5-labeled synthetic peptide against c-Met was developed, and fluorescent endoscopic observation with this probe detected a greater number of colorectal adenomas than with white light observation. Another trial used IR800-labeled anti-VEGF antibody, which sensitively detected human colorectal adenomas by fluorescent endoscopy. Last, a fluorescent probe with synthetic peptide against BRAF-positive cells was able to visualize sessile serrated lesions. The fluorescent probes accumulated at very high levels in colorectal tumor cells but at lower levels in surrounding nonneoplastic mucosa. Key Messages: We expect that molecular imaging techniques with fluorescent probes will soon lead to the establishment of a highly sensitive endoscopic method for colorectal tumor detection.

Dysplastic Aberrant Crypt Foci: Biomarkers of Early Colorectal Neoplasia and Response to Preventive Intervention

The discovery of aberrant crypt foci (ACF) more than three decades ago not only enhanced our understanding of how colorectal tumors form, but provided new opportunities to detect lesions prior to adenoma development and intervene in the colorectal carcinogenesis process even earlier. Because not all ACF progress to neoplasia, it is important to stratify these lesions based on the presence of dysplasia and establish early detection methods and interventions that specifically target dysplastic ACF (microadenomas). Significant progress has been made in characterizing the morphology and genetics of dysplastic ACF in both preclinical models and humans. Image-based methods have been established and new techniques that utilize bioactivatable probes and capture histologic abnormalities in vivo are emerging for lesion detection. Successful identification of agents that target dysplastic ACF holds great promise for intervening even earlier in the carcinogenesis process to maximize tumor inhibition. Future preclinical and clinical prevention studies should give significant attention to assessing the utility of dysplastic ACF as the earliest identifiable biomarker of colorectal neoplasia and response to therapy.See all articles in this Special Collection Honoring Paul F. Engstrom, MD, Champion of Cancer Prevention.

Cancer-associated adipocytes promote pancreatic cancer progression through SAA1 expression

Although pancreatic cancer often invades peripancreatic adipose tissue, little information is known about cancer-adipocyte interaction. We first investigated the ability of adipocytes to de-differentiate to cancer-associated adipocytes (CAAs) by co-culturing with pancreatic cancer cells. We then examined the effects of CAA-conditioned medium (CAA-CM) on the malignant characteristics of cancer cells, the mechanism underlying those effects, and their clinical relevance in pancreatic cancer. When 3T3-L1 adipocytes were co-cultured with pancreatic cancer cells (PANC-1) using the Transwell system, adipocytes lost their lipid droplets and changed morphologically to fibroblast-like cells (CAA). Adipocyte-specific marker mRNA levels significantly decreased but those of fibroblast-specific markers appeared, characteristic findings of CAA, as revealed by real-time PCR. When PANC-1 cells were cultured with CAA-CM, significantly higher migration/invasion capability, chemoresistance, and epithelial-mesenchymal transition (EMT) properties were observed compared with control cells. To investigate the mechanism underlying these effects, we performed microarray analysis of PANC-1 cells cultured with CAA-CM and found a 78.5-fold higher expression of SAA1 compared with control cells. When the SAA1 gene in PANC-1 cells was knocked down with SAA1 siRNA, migration/invasion capability, chemoresistance, and EMT properties were significantly attenuated compared with control cells. Immunohistochemical analysis on human pancreatic cancer tissues revealed positive SAA1 expression in 46/61 (75.4%). Overall survival in the SAA1-positive group was significantly shorter than in the SAA1-negative group (P = .013). In conclusion, we demonstrated that pancreatic cancer cells induced de-differentiation in adipocytes toward CAA, and that CAA promoted malignant characteristics of pancreatic cancer via SAA1 expression, suggesting that SAA1 is a novel therapeutic target in pancreatic cancer.

Expression Patterns of Xenobiotic-Metabolizing Enzymes in Tumor and Adjacent Normal Mucosa Tissues among Patients with Colorectal Cancer: The ColoCare Study

BACKGROUND

Xenobiotic-metabolizing enzymes (XME) play a critical role in the activation and detoxification of several carcinogens. However, the role of XMEs in colorectal carcinogenesis is unclear.

METHODS

We investigated the expression of XMEs in human colorectal tissues among patients with stage I-IV colorectal cancer (n = 71) from the ColoCare Study. Transcriptomic profiling using paired colorectal tumor and adjacent normal mucosa tissues of XMEs (GSTM1, GSTA1, UGT1A8, UGT1A10, CYP3A4, CYP2C9, GSTP1, and CYP2W1) by RNA microarray was compared using Wilcoxon rank-sum tests. We assessed associations between clinicopathologic, dietary, and lifestyle factors and XME expression with linear regression models.

RESULTS

GSTM1, GSTA1, UGT1A8, UGT1A10, and CYP3A4 were all statistically significantly downregulated in colorectal tumor relative to normal mucosa tissues (all P ≤ 0.03). Women had significantly higher expression of GSTM1 in normal tissues compared with men (β = 0.37, P = 0.02). By tumor site, CYP2C9 expression was lower in normal mucosa among patients with rectal cancer versus colon cancer cases (β = -0.21, P = 0.0005). Smokers demonstrated higher CYP2C9 expression levels in normal mucosa (β = 0.17, P = 0.02) when compared with nonsmokers. Individuals who used NSAIDs had higher GSTP1 tumor expression compared with non-NSAID users (β = 0.17, P = 0.03). Higher consumption of cooked vegetables (>1×/week) was associated with higher CYP3A4 expression in colorectal tumor tissues (β = 0.14, P = 0.007).

CONCLUSIONS

XMEs have lower expression in colorectal tumor relative to normal mucosa tissues and may modify colorectal carcinogenesis via associations with clinicopathologic, lifestyle, and dietary factors.

IMPACT

Better understanding into the role of drug-metabolizing enzymes in colorectal cancer may reveal biological differences that contribute to cancer development, as well as treatment response, leading to clinical implications in colorectal cancer prevention and management.

A highly selective fluorogenic substrate for imaging glutathione S-transferase P1: development and cellular applicability in epigenetic studies

Pi-class glutathione S-transferase (GSTP1) is a molecular marker enzyme whose expression level is altered in various malignant tumour tissues. Herein, we report the first highly selective fluorogenic GSTP1 substrate, Ps-TG, and its membrane-permeable derivative Ps-TAc, for specific visualization of intracellular GSTP1 activity in cancer cells or epigenetically regulated GSTP1 expression.

4-Bromo-1,8-naphthalimide derivatives as fluorogenic substrates for live cell imaging of glutathione S-transferase (GST) activity

Fluorogenic substrates are used to visualize the activity of cancer-associated enzymes and to interpret biological events. Certain types of glutathione S-transferase (GST), such as Pi class GST (referred to as GSTP1), are more highly expressed in a wide variety of human cancer tissues compared to their corresponding normal tissues. Pi class GST is thus a cancer cell molecular marker and potential target for overcoming resistance to chemotherapy. Here, we report that 4-bromo-1,8-naphthalimide (BrNaph) is a practical fluorogenic GST substrate. We have found that HE-BrNaph, an N-hydroxyethyl derivative, shows remarkable fluorescence enhancement upon GST-catalyzed S_NAr replacement of the bromo group with a glutathionyl group. This substitution was highly selective and occurred only in the presence of GSH/GSTs; no non-enzymatic reaction was observed. We demonstrated that HE-BrNaph allows visualization of GST activity in living cells and enables to distinguish cancer cells from normal cells. Further, various N-substitutions in BrNaph retain susceptibility to enzymatic activity and isozyme selectivity, suggesting the applicability of BrNaph derivatives. Thus, BrNaph and its derivatives are GST substrates useful for fluorescence imaging and the intracellular detection of GSTP1 activity in living cells.

Association of Glutathione S-transferase gene polymorphism with bladder Cancer susceptibility

BACKGROUND

We conducted a meta-analysis to evaluate the relationship between the glutathione S-transferase μ1 (GSTM1)- and glutathione S-transferase θ1 (GSTT1)- null genotypes and susceptibility to bladder cancer.

METHODS

We identified association reports from the databases of PubMed, Embase, the Cochrane Library and the China Biological Medicine Database (CBM disc) on July 1, 2017 and synthesized eligible investigations. Results were expressed using odds ratios (ORs) for dichotomous data, and we also calculated 95% confidence intervals (CIs).

RESULTS

In this meta-analysis, we found that the GSTM1-null genotype was associated with bladder cancer risk in the overall population, and individually in whites, Africans and Asians (overall population: OR = 1.40, 95% CI: 1.31-1.48, P<0.00001; whites: OR = 1.39, 95% CI: 1.26-1.54, P<0.00001; Africans: OR = 1.54, 95% CI: 1.16-2.05, P = 0.003; Asians: OR = 1.45, 95% CI: 1.33-1.59, P<0.00001). The GSTT1-null genotype was associated with bladder cancer risk in the overall population, but not in whites, in Africans or Asians (overall population: OR = 1.11, 95% CI: 1.01-1.22, P = 0.03; whites: OR = 1.16, 95% CI: 0.99-1.36, P = 0.07; Africans: OR = 1.07, 95% CI: 0.65-1.76, P = 0.79; Asians: OR = 1.05, 95% CI: 0.91-1.22, P = 0.51). Interestingly, a dual-null GSTM1-GSTT1 genotype was associated with bladder cancer risk in the overall population and in Asians (overall population: OR = 1.48, 95% CI: 1.15-1.92, P = 0.002; Asians: OR = 1.62, 95% CI: 1.15-2.28, P = 0.006). In conclusion, the GSTM1-null, GSTT1-null and dual-null GSTM1-GSTT1 genotypes might be associated with the onset of bladder cancer, but additional genetic-epidemiological studies should be conducted to explore this association further.

Molecular imaging within the lower gastrointestinal tract: From feasibility to future

Molecular imaging is based on the labelling of defined molecular targets through the utilization of fluorescently linked probes and their subsequent detection with high-resolution endoscopic devices, thereby enabling visualization of single molecules including receptors. Whereas early studies have used molecular imaging for improved visualization and detection of early dysplasia and cancer as well as for assessing intestinal inflammation and inflammation-associated cancer within the gastrointestinal (GI) tract, more recent studies have impressively demonstrated that molecular imaging can also be used to characterize and visualize the molecular fingerprint of cancer and inflammation in vivo and in real time. With this, molecular imaging can be used to guide expression-tailored individualized therapy. With the rapid expansion and diversification of the repertoire of biological agents utilized in inflammatory bowel disease and cancer, this approach is gaining increasing attention. Within this review, we first summarize the technical components commonly used for molecular imaging and then review preclinical and clinical studies and evolving clinical applications on molecular imaging within the lower GI tract. Molecular imaging has the potential to significantly change endoscopic diagnosis and subsequent targeted therapy of gastrointestinal cancer and chronic gastrointestinal diseases.

A systematic review and meta-analyses of the relationship between glutathione S-transferase gene polymorphisms and renal cell carcinoma susceptibility

BACKGROUND

Association of GSTM1- and GSTT1-null genotypes, GSTP1 A/G gene polymorphism with renal cell carcinoma (RCC) susceptibility was detected, and the relationship between the GSTM1/GSTT1-null genotype and clinical TNM stages of RCC was assessed, using meta-analysis method.

METHODS

Association investigations according to eligibility criteria were searched and identified from the databases of Cochrane Library, PubMed, and Embase from establishment time of databases to July 1, 2017, and eligible reports were analyzed by meta-analysis. 95% confidence intervals (CI) were also detected, and odds ratios (OR) was used to express the results for dichotomous data.

RESULTS

This meta-analysis indicated that there was no an association between GSTM1-null genotype, GSTT1-null genotype, GSTP1 A/G gene polymorphism and RCC risk in the overall population of Caucasians or Asians. The dual GSTM1-GSTT1-null genotype was also not associated with RCC in the overall population of Caucasians. Interestingly, there was an association between the dual GSTM1-GSTT1-null genotype and the susceptibility of RCC in Asians. Relationship of the GSTM1-null genotype with clinical TNM stage of RCC was not observed in the overall population of Asians or Caucasians. In this meta-analysis, no association between the GSTT1-null genotype and clinical TNM stage of RCC was observed in Caucasians or Asians. Interestingly, GSTT1-null genotype was detected to be associated with the clinical TNM stages in patients with RCC in the overall population.

CONCLUSION

The dual GSTM1-GSTT1-null genotype is detected to be associated with the onset of RCC in Asians, and there is an association between the GSTT1-null genotype and the clinical TNM stages in patients with RCC in the overall population.

A Novel Theranostic Combination of Near-infrared Fluorescence Imaging and Laser Irradiation Targeting c-KIT for Gastrointestinal Stromal Tumors

It is difficult to distinguish gastrointestinal stromal tumors (GISTs) from other types of submucosal tumors under conventional gastrointestinal endoscopy. We aimed to detect GISTs by molecular fluorescence imaging using a near-infrared (NIR) photosensitizer (IR700)-conjugated anti-c-KIT antibody and to treat GISTs by photoimmunotherapy with NIR irradiation as a non-invasive theranostic procedure. We also investigated the therapeutic mechanisms. Methods: Human GIST cell lines GIST-T1 and GIST-882M were incubated with IR700-conjugated anti-c-KIT antibody, IR700-12A8, and observed by confocal laser microscopy. Mice with GIST-T1 xenografts or rats with orthotopic xenografts were injected with IR700-12A8 or AF488-conjugated antibody, and observed under IVIS or autofluorescence imaging (AFI) endoscopy. GIST cells were treated with IR700-12A8 and NIR light in vitro and vivo, and cell viability, histology and apoptosis were evaluated. Results: Strong red fluorescence of IR700-12A8 was observed on the cell membrane of GIST cells and was gradually internalized into the cytoplasm. Tumor-specific accumulation of IR700-12A8 was observed in GIST-T1 xenografts in mice. Under AFI endoscopy, a strong fluorescence signal was observed in orthotopic GIST xenografts in rats through the normal mucosa covering the tumor. The percentage of dead cells significantly increased in a light-dose-dependent manner and both acute necrotic and late apoptotic cell death was observed with annexin/PI staining. Cleaved PARP expression was significantly increased after IR700-12A8-mediated NIR irradiation, which was almost completely reversed by NaN₃. All xenograft tumors (7/7) immediately regressed and 4/7 tumors completely disappeared after IR700-12A8-mediated NIR irradiation. Histologic assessment and TUNEL staining revealed apoptosis in the tumors. Conclusion: NIR fluorescence imaging using IR700-12A8 and subsequent NIR irradiation could be a very effective theranostic technology for GIST, the underlying mechanism of which appears to involve acute necrosis and supposedly late apoptosis induced by singlet oxygen.