Unique Genomic Alterations and Microbial Profiles Identified in Patients With Gastric Cancer of African, European, and Asian Ancestry: A Novel Path for Precision Oncology

OBJECTIVE

Here, we characterize differences in the genetic and microbial profiles of GC in patients of African (AFR), European, and Asian ancestry.

BACKGROUND

Gastric cancer (GC) is a heterogeneous disease with clinicopathologic variations due to a complex interplay of environmental and biological factors, which may affect disparities in oncologic outcomes..

METHODS

We identified 1042 patients with GC with next-generation sequencing data from an institutional Integrated Mutation Profiling of Actionable Cancer Targets assay and the Cancer Genomic Atlas group. Genetic ancestry was inferred from markers captured by the Integrated Mutation Profiling of Actionable Cancer Targets and the Cancer Genomic Atlas whole exome sequencing panels. Tumor microbial profiles were inferred from sequencing data using a validated microbiome bioinformatics pipeline. Genomic alterations and microbial profiles were compared among patients with GC of different ancestries.

RESULTS

We assessed 8023 genomic alterations. The most frequently altered genes were TP53 , ARID1A , KRAS , ERBB2 , and CDH1 . Patients of AFR ancestry had a significantly higher rate of CCNE1 alterations and a lower rate of KRAS alterations ( P < 0.05), and patients of East Asian ancestry had a significantly lower rate of PI3K pathway alterations ( P < 0.05) compared with other ancestries. Microbial diversity and enrichment did not differ significantly across ancestry groups ( P > 0.05).

CONCLUSIONS

Distinct patterns of genomic alterations and variations in microbial profiles were identified in patients with GC of AFR, European, and Asian ancestry. Our findings of variation in the prevalence of clinically actionable tumor alterations among ancestry groups suggest that precision medicine can mitigate oncologic disparities.

Optimal Timing of Laparoscopic Cholecystectomy After Conservative Therapy for Acute Cholecystitis

Background/Aim

According to the Tokyo Guidelines 2018, the operation for acute cholecystitis is recommended to be performed as early as possible. However, there are cases in which early surgeries cannot be performed due to complications of patients or facility conditions, resulting in elective surgery. Hence, we retrospectively analyzed elective surgery cases in this study.

Patients and Methods

There were 345 patients who were underwent laparoscopic cholecystectomy (LC) at our hospital from January 2019 to December 2020 in this retrospective study. A total of 83 patients underwent LC more than 3 days after conservative treatment. The elective LC patients were divided into the Early group (4-90 days after onset, n=36) and the Delayed group [91 days or more (13 weeks or more) after onset, n=31], excluding 16 patients who underwent percutaneous transhepatic gallbladder drainage.

Results

As for operative time, there was a significant difference between the Delayed and Early groups (91.2 vs. 117 minutes, p=0.0108). And also, there was a significant difference in the postoperative hospital stay, which was significantly shorter in the Delayed group than in the Early group (3.4 vs. 5.9 days, p=0.0436). Although there were no significant differences in either conversion rates or complication rates, both of these were decreasing in the Delayed group. In particular, there were no complications in the Delayed group.

Conclusion

When the conservative treatment for acute cholecystitis precedes and precludes urgent/early LC within 3 days, delaying LC for at least 91 days (13 weeks or more) after onset could reduce operative time and postoperative hospital stay. Moreover, there would be no complications after LC, and the rates of conversion during LC may be kept low.

Abstract 5890: Distinct differences in microbial enrichment and diversity identified between gastric and gastroesophageal junction adenocarcinoma

Objective: The microbiome is associated with the pathogenesis and progression of disease in gastric cancer (GC). Eradication of Helicobacter pylori has reduced overall GC incidence, however, gastroesophageal cancer (GEJC) continues to increase. While there are oncologic differences between GEJC and GC, distinctions based on microbial profiles are unknown. In this study, we characterize differences in the microbial profiles of GEJC and GC.

Methods: 562 patients with microsatellite stable GC (n=303) and GEJC (n=259) who had an institutional Integrated Mutation Profiling of Actionable Cancer Targets assay on the primary tumor were included in the study. A validated microbiome bioinformatics pipeline that is generalizable across multiple next generation sequencing platforms was utilized to compare microbial enrichment and alpha diversity between GC and GEJC, defined by type 1-3 Siewert classification.

Results: Over 20 unique microbial species were enriched in GC when compared to GEJC, including Helicobacter and Lymphocryptovirus (Table 1). Prevotella had increased incidence in GEJC (OR:1.57,95%CI:1.02,2.41). Siewert type 2 and 3 GEJC had a significantly lower alpha diversity compared to GC. There was no significant difference in alpha diversity between GC and Siewert type 1 GEJC.

Conclusion: There are distinct differences in microbial enrichment and alpha diversity between GEJC and GC. Helicobacter and Lymphocryptovirus, the genus family for Epstein Bar Virus, were noted to have the highest odds ratios in the GC group. Our findings showing the reduced incidence of microbes in GEJC which are the current targets of GC screening, prevention, and therapy, have implications in evaluating optimal preventative and treatment strategies in GEJC.

Table 1. Microbes with enrichment in gastric cancer (GC) when compared to gastroesophageal cancer (GEJC) Microbes OR (95% Confidence Interval) p-value Helicobacter 85.40 (5.191, 1404.81) 0.002 Lymphocryptovirus 6.83 (2.3120,.17) 0.001 Pelagibacterium 6.01 (1.71, 21.06) 0.005 Gluconacetobacter 5.14 (1.70, 15.53) 0.004 Myxococcus 5.14 (1.70, 15.53) 0.004 Kribbella 4.48 (1.46, 13.74) 0.009 Celeribacter 3.46 (1.43, 8.37) 0.006 Halomonas 3.46 (1.43, 8.37) 0.006 Nakamurella 3.35 (1.46, 7.71) 0.004 Nitrobacter 2.91 (1.40, 6.05) 0.004 Pseudogulbenkiania 2.80 (1.30, 6.03) 0.009 Mycobacteroides 2.78 (1.33, 5.81) 0.006 Polaromonas 2.70 (1.49, 4.90) 0.001 Meiothermus 2.54 (1.41, 4.57) 0.002 Sphingopyxis 2.44 (1.33, 4.46) 0.004 Mesorhizobium 2.38 (1.32, 4.30) 0.004 Staphylococcus 2.23 (1.37, 3.62) 0.001 Thermus 2.13 (1.22, 3.70) 0.008 Mycolicibacterium 1.99 (1.29, 3.07) 0.002 Mycobacterium 1.95 (1.23, 3.08) 0.005 Lactobacillus 1.94 (1.17, 3.22) 0.01

Citation Format: Miseker Abate, Harrison Drebin, Shoji Shimada, Santosh Vardhana, Smita Sihag, Vivian E. Strong, Chad Vanderbilt. Distinct differences in microbial enrichment and diversity identified between gastric and gastroesophageal junction adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5890.

Unique microbial profile identified in patients with gastric cancer with pathologic response to neoadjuvant chemotherapy

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Background: Microbial dysbiosis has been shown to be associated with the pathogenesis of gastric cancer (GC). However, the relationship between the GC microbiome and response to systemic therapy, such as neoadjuvant chemotherapy (NAC), is largely unknown. This study aims to explore changes in the microbiome after neoadjuvant chemotherapy, by analyzing the microbial profile of patients who received NAC and comparing differences among those with varied pathologic response to therapy. Methods: A microbiome bioinformatics pipeline using multiple next generation sequencing platforms was developed and used for analysis. GC tissue from patients who received NAC (n=101) and those who did not (n=85) were acquired at the time of surgical resection. Shannon alpha diversity plot and enrichment analyses by odds ratio were used to compare the microbial differences of the treatment cohorts. The microbial profiles of patients with pathologic response to NAC (>20% response) were characterized. Results: Of patients who received NAC, 66 (65.3%) experienced a greater than 20% response to NAC, and 35 (34.6%) demonstrated a 20% or lower response. Patients with a pathologic response to NAC were enriched for Rhizobium, Streptomyces, Comamonas, Sphingomonas, Micrococcus, Mycobacterium, Thauera, Hyphomicrobium, and Sinorhizobium (OR>4). There were no statistically significant differences in alpha diversity (p>0.05). Conclusions: Our results demonstrate that patients with a greater than 20% pathologic response to NAC have a distinct microbial enrichment compared to those with a poor pathologic response. Given the variable NAC treatment responses in GC, understanding unique microbial signatures in tumors will provide the landscape to explore key microbial contributors to GC NAC treatment response that may improve our understanding of treatment response variability among patients. [Table: see text]

Differences in genomic profiles of gastric adenocarcinoma in the US and Japan

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Background: Although epidemiological and clinical differences in gastric cancer (GC) between the US and Japan have been reported, genetic differences have not been clarified. We aimed to characterize molecular differences in GC between the two countries. Methods: We collected data between January 2010 and December 2019 from a prospectively maintained database of GC at our US and Japanese centers. After matching clinicopathological backgrounds, including age, sex, clinical T and N status, and tumor location, the genomic profiles of the primary site were compared for 58 patients in each group undergoing surgical resection and had MSK-IMPACT (MSK-Integrated Mutation Profiling of Actionable Cancer Targets), a tumor-normal next generation sequencing assay that can detect alterations in exons and select introns of 505 genes. The MSI sensor algorithm was used to assess microsatellite instability. Genomic alterations were filtered for driver variants using OncoKB, and genes were consolidated into pathways using curated pathway templates from the Cancer Genome Atlas. Results: The clinicopathological characteristics were well matched between 58 patients in each cohort. In the entire cohort, the most commonly altered genes were: TP53 (45%), ARID1A (24%), and ERBB2 (17%) in the US cohort, and TP53 (50%), ARID1A (19%), and ERBB2 (17%) in the Japanese cohort. Although KMT2D was more frequently altered in the US cohort (19% vs. 2%), the two cohorts had no significant differences in other altered genes and gene pathways. The tumor with MSI high was found more frequently in the US cohort (22.4% vs. 5.2%, p = 0.01). Among the MSI-normal tumors, the tumor mutational burden (US: 3.5 muts/Mb and Japanese: 4.1 muts/Mb) and the fraction genome altered (US: 0.37 and Japanese: 0.28) did not significantly differ between the two groups. Additionally, no genes or pathways were significantly enriched in either group. Patterns of mutual exclusivity and co-occurrence amongst genes and pathways were also similar between the two groups. Conclusions: In this original genomic comparison of US and Japanese gastric cancers, matching clinicopathological backgrounds, Japanese and US gastric cancers are remarkably similar at the genomic level, with the possible exception of MSI-high tumor that appear to be more frequent in the US.

Novel "resect and analysis" approach for T2 colorectal cancer with use of artificial intelligence

BACKGROUND AND AIMS

Because of a lack of reliable preoperative prediction of lymph node involvement in early-stage T2 colorectal cancer (CRC), surgical resection is the current standard treatment. This leads to overtreatment because only 25% of T2 CRC patients turn out to have lymph node metastasis (LNM). We assessed a novel artificial intelligence (AI) system to predict LNM in T2 CRC to ascertain patients who can be safely treated with less-invasive endoscopic resection such as endoscopic full-thickness resection and do not need surgery.

METHODS

We included 511 consecutive patients who had surgical resection with T2 CRC from 2001 to 2016; 411 patients (2001-2014) were used as a training set for the random forest-based AI prediction tool, and 100 patients (2014-2016) were used to validate the AI tool performance. The AI algorithm included 8 clinicopathologic variables (patient age and sex, tumor size and location, lymphatic invasion, vascular invasion, histologic differentiation, and serum carcinoembryonic antigen level) and predicted the likelihood of LNM by receiver-operating characteristics using area under the curve (AUC) estimates.

RESULTS

Rates of LNM in the training and validation datasets were 26% (106/411) and 28% (28/100), respectively. The AUC of the AI algorithm for the validation cohort was .93. With 96% sensitivity (95% confidence interval, 90%-99%), specificity was 88% (95% confidence interval, 80%-94%). In this case, 64% of patients could avoid surgery, whereas 1.6% of patients with LNM would lose a chance to receive surgery.

CONCLUSIONS

Our proposed AI prediction model has a potential to reduce unnecessary surgery for patients with T2 CRC with very little risk. (Clinical trial registration number: UMIN 000038257.).

A technique for constructing diverting loop ileostomy to prevent outlet obstruction after rectal resection and total colectomy: a retrospective single-center study

PURPOSE

Preventing outlet obstruction associated with a diverting stoma is important. Previously, we constructed a diverting loop ileostomy with the proximal limb of the small intestine on the caudal side, namely the oral inferior (OI) method. However, to address the issue of twisting and stenosis of the small intestine, we recently constructed a diverting loop ileostomy with the proximal limb on the cranial side, namely the oral superior (OS) method. We compared the incidence of outlet obstruction between the two methods.

METHODS

The subjects of this retrospective study were 133 patients who underwent colorectal resection or total colectomy, with D2 or more lymph node dissection and diverting loop ileostomy construction, between April, 2001 and December, 2018, at our hospital. The OI method was performed in 54 patients and the OS method was performed in 79 patients.

RESULTS

In the OS group, a history of laparotomy, neoadjuvant therapy, clinical stage III, and the use of anti-adhesion materials were more common, whereas blood loss and the incidence of outlet obstruction were significantly lower. Multivariate analysis identified only OS placement as a significant factor for reducing the incidence of outlet obstruction.

CONCLUSION

When constructing a diverting loop ileostomy, placing the proximal limb on the cranial side is important.

Impact of non-curative endoscopic submucosal dissection on short- and long-term outcome of subsequent laparoscopic gastrectomy for pT1 gastric cancer

BACKGROUND

The feasibility and oncological safety of non-curative endoscopic submucosal dissection (ESD) prior to additional gastrectomy for early gastric cancer (EGC) are still unclear. The aim of this study was to evaluate the impact of non-curative ESD on short- and long-term outcomes of subsequent laparoscopic gastrectomy (LG) for pathological T1 (pT1) EGC.

METHODS

We retrospectively investigated 422 patients who underwent LG for pT1 EGC between January 2007 and December 2017 at our center. Eighty-five of these patients underwent ESD with curative intent before surgery. Using propensity-score matching for sex, age, body mass index, American society of anesthesiologists score, history of previous abdominal surgery, tumor location, mucosal/submucosal infiltration, histology, lymph node metastasis, extent of lymph node dissection, operative method, lymphatic invasion, and venous invasion, the clinicopathologic and survival data of these patients were compared.

RESULTS

The median follow-up period was 60 (range 2-168) months. Using propensity-score matching from a total of 422 patients, 75 patients were selected in the Non-ESD and the ESD cohorts each. There were no significant differences in terms of characteristics and clinicopathological findings between the two groups. Furthermore, there were no significant differences in postoperative morbidity (13.3% vs. 17.3%; P = 0.497) and mortality (1.3% vs. 0%; P = 0.316). Both the 5-year overall survival ratio (88.8% vs. 86.9%; P = 0.757) and 5-year disease-specific survival ratio (97.1% vs. 98.4%; P = 0.333) were similar in the two groups.

CONCLUSION

Short- and long-term outcomes of LG in patients with pT1 EGC are not related to preoperative ESD history. Even for non-curative resections, ESD prior to surgery is feasible in terms of oncological and surgical outcomes in pT1 EGC.

[Complete Response of Liver Metastases from a HER2-Positive Gastric Cancer Treated with Combined S-1/Trastuzumab Chemotherapy]

A 74-year-old man with upper abdominal pain and anorexia was referred to our hospital in December 2013. Based on computed tomography(CT)and gastroendoscopy findings, the patient was diagnosed as having advanced gastric cancer with multiple liver metastases(S3, S5, and S6 lesions). Because of high pyloric stenosis, distal gastrectomy Roux-en-Y reconstruction was performed in mid-December 2013. Histopathological findings of the patient were L, Ant-Gre, 35×60 mm, type 2, pT4a(SE), tub2>tub1, int, INF b, ly2, v1(VB), pPM0(95mm), pDM0(15mm), pN0(0/2), HER2(IHC 3+). Postop- eratively, the patient received combined S-1/trastuzumab chemotherapy toward the end of January 2014. The clinical response was PR after 2 courses and clinical CR(cCR)after 4 courses. Because hand-foot syndrome caused by S-1 was prolonged, the dosage was completed in 11 courses. He remains alive 4.5 years after surgery without recurrence. Although ToGA examination showed that trastuzumab was effective for HER 2-positive unresectable gastric cancer, few reported cases showed progression to cCR after the treatment followed by a regimen of trastuzumab without CDDP, and they had good prognosis. Furthermore, in this case, the liver metastases showed complete response without CDDP. Thus, trastuzumab might be a chemotherapy option for patients who have difficulty using platinum analogs, including the elderly patients.

Cartilage wear patterns in severe osteoarthritis of the trapeziometacarpal joint: a quantitative analysis

OBJECTIVE

The present quantitative study aimed to assess the three-dimensional (3-D) cartilage wear patterns of the first metacarpal and trapezium in the advanced stage of osteoarthritis (OA) and compare cartilage measurements with radiographic severity.

DESIGN

Using 19 cadaveric trapeziometacarpal (TMC) joints, 3-D cartilage surface models of the first metacarpal and trapezium were created with a laser scanner, and 3-D bone surface model counterparts were similarly created after dissolving the cartilage. These two models were superimposed, and the interval distance on the articular surface as the cartilage thickness was measured. All measurements were obtained in categorized anatomic regions on the articular surface of the respective bone, and we analyzed the 3-D wear patterns on the entire cartilage surface. Furthermore, we compared measurements of cartilage thickness with radiographic OA severity according to the Eaton grading system using Pearson correlation coefficients (r).

RESULTS

In the first metacarpal, the cartilage thickness declined volarly (the mean cartilage thickness of the volar region was 0.32 ± 0.16 mm, whereas that of the dorsal region was 0.53 ± 0.18 mm). Conversely, the cartilage evenly degenerated throughout the articular surface of the trapezium. Measurements of the categorized regions where cartilage thinning was remarkable exhibited statistical correlations with radiographic staging (r = -0.48 to -0.72).

CONCLUSIONS

Our findings indicate that cartilage wear patterns differ between the first metacarpal and trapezium in the late stage of OA. There is a need for further studies on cartilage degeneration leading to symptomatic OA in the TMC joint.

High Serum CA19-9 Concentration Predicts Poor Prognosis in Elderly Patients with Stage IV Colorectal Cancer

BACKGROUND/AIM

The optimal treatment strategy for elderly patients with stage IV colorectal cancer (CRC) remains controversial due to limited research data. The purpose of this study was to evaluate treatment results and to clarify the prognostic factors, especially poor prognosis factors, in elderly patients with stage IV CRC.

METHODS

We retrospectively reviewed the data of 82 elderly patients (aged ≥75 years) with stage IV CRC who underwent surgical treatment at our hospital between April 2001 and March 2017. Factors that affected prognosis and the ability to undergo treatment were analyzed via multivariate analysis.

RESULTS

The median overall survival (OS) in the patients with high pretreatment serum carbohydrate antigen 19-9 (CA19-9) concentration (> 370 U/mL) was significantly worse than in those with lower serum CA19-9 concentration (0-370 U/mL) (8.5 vs. 19.2 months, p = 0.0059). In univariate analysis, age (≥80 years) (p = 0.014), performance status of 1-3 (p = 0.028), and high pretreatment serum CA19-9 concentration (p = 0.014) were significant prognostic factors for poor OS. By contrast, resection of the primary tumor (p = 0.024), chemotherapy (p < 0.0001), and resection of distant metastasis (p = 0.0005) were significant prognostic factors for favorable OS. Multivariate analysis showed that a high pretreatment serum CA19-9 concentration was an independent prognostic factor for poor OS (p = 0.01). Meanwhile, resection of the primary tumor (p = 0.033), chemotherapy (p < 0.0001), and resection of distant metastasis (p = 0.0008) were prognostic factors for favorable OS.

CONCLUSIONS

A high pretreatment serum CA19-9 concentration (> 370 U/mL) was a reliable predictive factor for poor prognosis, and aggressive treatments should be performed carefully in these patients. Moreover, various treatments, including surgery and chemotherapy, might improve OS in elderly patients with stage IV CRC.

A novel 5HT3 receptor-IGF1 mechanism distinct from SSRI-induced antidepressant effects

Depression is a common mental disorder affecting around 350 million people worldwide. Although selective serotonin reuptake inhibitors (SSRIs) are the most widely used antidepressants, a significant proportion of depressed patients do not achieve remission with SSRIs. In this study, we show that a serotonin type 3 receptor (5HT3R) agonist induces antidepressant effects as well as hippocampal neurogenesis independent of fluoxetine (a commonly used SSRI). Notably, our histological analysis reveals that 5HT3R and insulin-like growth factor 1 (IGF1) are expressed in the same neurons in the subgranular zone of the hippocampal dentate gyrus. Furthermore, our in vivo microdialysis analysis shows that 5HT3R regulates hippocampal extracellular IGF1 levels, and we also show that 5HT3R-dependent hippocampal neurogenesis is mediated by increased IGF1 levels. Altogether, our findings suggest a novel 5HT3R-IGF1 mechanism that is distinct from fluoxetine-induced responses and that provides a new therapeutic target for depression, especially bringing significant benefits for SSRI-resistant depressed patients.

Impact of obesity on short- and long-term outcomes of laparoscopy assisted distal gastrectomy for gastric cancer

BACKGROUND

Laparoscopy assisted distal gastrectomy (LADG) for gastric cancer has been rapidly adopted for the treatment of both early and advanced gastric cancers which need lymph node dissection, but remains difficult procedure, especially in patients with obesity. We evaluated the impact of obesity on short- and long-term outcomes of LADG for gastric cancer.

METHODS

We retrospectively investigated 243 patients who underwent LADG for gastric cancer between January 2007 and December 2014. The patients were classified based on their body mass index (BMI) into the Obese (BMI ≥ 25) and Non-Obese (BMI < 25) Groups. Patient characteristics, clinicopathologic and operative findings, and short- and long-term outcomes were investigated and compared between the groups.

RESULTS

The groups did not differ in age, sex, American Society of Anesthesiologists score, the presence of comorbidities, or pathologic stage. Operative time (265 ± 46.6 vs. 244 ± 55.6 min; P = 0.007) and estimated blood loss (113 ± 101.4 vs. 66.5 ± 95.2 ml; P = 0.007) were greater in the Obese Group. Fewer lymph nodes were retrieved in the Obese Group (38 ± 23.7 vs. 47.5 ± 24.3; P = 0.004). No differences were evident in postoperative complication rate (20% vs. 17%; P = 0.688) or the duration of postoperative hospital stay (9 ± 8.5 vs. 9 ± 5.1 days; P = 0.283) between the two groups. In the Obese Group, the 5-year overall survival rate was significantly lower than in the Non-Obese Group (67.6% vs. 90.3%; P = 0.036). Furthermore, 5-year disease-specific survival was significantly lower in the Obese Group than in the Non-Obese Group (72.7% vs. 94.9%; P = 0.015).

CONCLUSIONS

LADG in patients with obesity could be performed as safe as in patients without obesity, with comparable postoperative results. But obesity may be a poor prognostic factor in gastric cancer.

Fecal Volume after Laparoscopic Low Anterior Resection Predicts Anastomotic Leakage

BACKGROUND/AIM

Anastomotic leakage (AL) is a major complication after laparoscopic low anterior resection (Lap-LAR). Many surgeons encounter AL following severe postoperative diarrhea. However, little is known about the relationship between postoperative fecal volume and AL. This study determined whether postoperative fecal volume can predict AL.

METHODS

A retrospective assessment was performed with data from 176 patients with rectal cancers who underwent Lap-LAR between April 2011 and August 2015. A transanal tube was routinely placed in all cases. The fecal volume from the transanal tube was measured daily. The total fecal volume for 3 days after surgery was compared between the AL and non-AL groups.

RESULTS

AL occurred in 11 patients. There were 3 patients with a fecal volume ≥1,000 mL for 3 days after surgery. AL occurred in these 3 patients. In patients with a fecal volume <1,000 mL, the total fecal volume was significantly greater in the AL group than that in the non-AL group (p = 0.0003). The cut-off value of the total fecal volume in AL was 118 mL.

CONCLUSIONS

The volume of fecal discharge for 3 days after surgery is associated with the incidence of AL, and a fecal volume ≥118 mL may be a reliable predictor for AL.

14-3-3ζ-Mediated Stimulation of Oxidative Phosphorylation Exacerbates Oxidative Damage Under Hypothermic Oxygenated Conditions in Human Renal Tubular Cells (HK-2)

Cellular survival and death are at least partially regulated by the phosphorylation of proteins. A chaperon protein, 14-3-3ζ, regulates the activity of many proteins by covering the phosphorylation site within a 14-3-3 binding motif. Therefore, regulation of 14-3-3ζ activity may affect the fate of cells subjected to cold preservation and/or hypothermic oxygenated conditions. The present study assessed whether 14-3-3ζ protects cells from hypothermic oxygenation-induced injury and clarified its role in mitochondrial functions. Human renal tubular cell line HK-2 or 14-3-3ζ-overexpressed HK-2 (ζHK-2) cells were subjected to 72 hours of normoxic cold preservation in UW solution with or without antioxidants and hydroperoxides. Cellular death, adenosine triphosphate (ATP) content, and MTT catabolism were evaluated. Deferoxamine treatment reduced cellular death and augmented ATP content in both cell types. These indices were higher in ζHK-2, regardless of deferoxamine treatment. Exposure to hydroperoxides did not affect cellular death in either cell type, whereas hydroperoxide supplementation significantly reduced ATP content, except for low-dose hydrogen peroxide in HK-2 cells. MTT assay at normal state showed higher values in ζHK-2 cells, whereas it was impaired by hydroperoxides in both cell types. These results suggest that accumulation of hydroperoxides as a byproduct of the augmented oxidative phosphorylation by 14-3-3ζ overexpression causes mitochondrial dysfunction. In conclusion, despite possessing many potentially protective functions, 14-3-3ζ exacerbates cellular injury under hypothermic oxygenated conditions. 14-3-3ζ accelerates mitochondrial functions together with iron-dependent oxidative damage. Although further investigations are necessary, upregulation of 14-3-3ζ could be a method to maintain mitochondrial function under hypothermic oxygenated conditions, as shown in hypothermic machine preservation of renal grafts, when appropriate antioxidant treatment is administered.

Characterization by Electron Spin Resonance Spectroscopy of Reactive Oxygen Species Generated by Titanium Dioxide and Hydrogen Peroxide

The influence of reactive oxygen species (ROS) on the surface modification of titanium implants and osseointegration is unclear. The aim of this study was to evaluate the ability of titanium dioxide (TiO2) to generate ROS in the presence of H2O2 and to determine whether any ROS thus generated play a role in osseointegration, as measured by electron spin resonance (ESR) spin-trapping with 5,5-dimethyl-1-pyrolline- N-oxide (DMPO). We demonstrate that TiO2 together with H2O2 generated hydroxyl radicals (HO•), as shown by a time-dependent increase in the spin concentration of the ESR signal for the DMPO-OH spin adduct, indicating HO• generation. Interestingly, irradiated TiO2 with H2O2 generated the superoxide (O2•-), as shown by an increase in the spin concentration of the signal for the DMPO-OOH spin adduct, indicating O2•- generation during the period of irradiation (0–5 min). These results suggest that ROS generated from the TiO2 layer may be involved in creating appropriate conditions for the osseointegration of dental implants into alveolar bone tissues.