Prognostic Impact of Stromal Profiles Educated by Gastric Cancer.

BACKGROUND: Cancer-associated fibroblasts exhibit diversity and have several subtypes. The underlying relationship between the diversity of cancer-associated fibroblasts and their effect on gastric cancer progression remains unclear. In this study, mesenchymal stem cells were differentiated into cancer-associated fibroblasts with gastric cancer cell lines; clinical specimens were used to further investigate the impact of cancer-associated fibroblast diversity on cancer progression. METHODS: Nine gastric cancer cell lines (NUGC3, NUGC4, MKN7, MKN45, MKN74, FU97, OCUM1, NCI-N87, and KATOIII) were used to induce mesenchymal stem cell differentiation into cancer-associated fibroblasts. The cancer-associated fibroblasts were classified based on ACTA2 and PDPN expression. Cell function analysis was used to examine the impact of cancer-associated fibroblast subtypes on cancer cell phenotype. Tissue samples from 97gastric patients who underwent gastrectomy were used to examine the clinical significance of each subtype classified according to cancer-associated fibroblast expression. RESULTS: Co-culture of mesenchymal stem cells with nine gastric cancer cell lines revealed different subtypes of ACTA2 and PDPN expression in differentiated cancer-associated fibroblasts. Cancer-associated fibroblast subtypes with high ACTA2 plus PDPN expression levels significantly increased gastric cancer cell migration, invasion, and proliferation. The cancer-associated fibroblast subtype with ACTA2 plus PDPN expression was an independent prognostic factor along with lymph node metastasis for patients who had gastric cancer and were undergoing surgery. CONCLUSIONS: Cancer-associated fibroblasts are educated by gastric cancer cells during the development of cancer-associated fibroblast diversity. Differentiated cancer-associated fibroblasts with distinct expression patterns could affect gastric cancer progression and enable prognostic stratification for gastric cancer.

Clinical significance of postoperative complications after pancreatic surgery in time-to-complication and length of postoperative hospital stay: a retrospective study.

PURPOSE: We retrospectively analyzed pancreatectomy patients and examined the occurrence rate and timing of postoperative complications (time-to-complication; TTC) and their impact on the length of postoperative hospital stay (POHS) to clarify their characteristics, provide appropriate postoperative management, and improve short-term outcomes in the future. METHODS: A total of 227 patients, composed of 118 pancreaticoduodenectomy (PD) and 109 distal pancreatectomy (DP) cases, were analyzed. We examined the frequency of occurrence, TTC, and POHS of each type of postoperative complication, and these were analyzed for each surgical procedure. Complications of the Clavien-Dindo (CD) classification Grade II or higher were considered clinically significant. RESULTS: Clinically significant complications were observed in 70.3% and 36.7% of the patients with PD and DP, respectively. Complications occurred at a median of 10 days in patients with PD and 6 days in patients with DP. Postoperative pancreatic fistula (POPF) occurred approximately 7 days postoperatively in both groups. For the POHS, in cases without significant postoperative complications (CD ≤ I), it was approximately 22 days for PD and 11 days for DP. In contrast, when any complications occurred, POHS increased to 30 days for PD and 19 days for DP (each with additional 8 days), respectively. In particular, POPF prolonged the hospital stay by approximately 11 days for both procedures. CONCLUSION: Each postoperative complication after pancreatectomy has its own characteristics in terms of the frequency of occurrence, TTC, and impact on POHS. A correct understanding of these factors will enable timely therapeutic intervention and improve short-term outcomes after pancreatectomy.

Dynamics of perioperative pancreatic exocrine function in patients undergoing reconstruction after gastrectomy for gastric cancer.

BACKGROUND: Each method of reconstruction after gastrectomy results in a change in the digestive and absorptive status. However, there are few reports on the changes in pancreatic exocrine function after gastrectomy. We conducted this study to investigate the dynamics of pancreatic exocrine function after gastrectomy according to the method of reconstruction performed. METHODS: The subjects of this study were 45 patients who underwent pancreatic exocrine function tests preoperatively and postoperatively, from among all patients who underwent gastrectomy for gastric cancer at our hospital between September, 2020 and March, 2022. We assessed pancreatic exocrine function using the Pancreatic Function Diagnostant (PFD) test. RESULT: The mean preoperative PFD test result values for the distal gastrectomy (DG) Billroth I reconstruction (B-I) group and the DG Roux-en-Y reconstruction (R-Y) group were 62.6 and 67.3 (p = 0.36), respectively, and the mean postoperative PFD test result values for each group were 65.8 and 46.9 (p = 0.0094), respectively. A significant decrease in postoperative pancreatic function was observed in the DG R-Y group but not in the DG B-I group. The logistic regression analysis identified that age and the R-Y group were significantly correlated with a 10% decrease in the PFD value after gastrectomy. CONCLUSIONS: Our study suggests that R-Y reconstruction may result in more impaired pancreatic exocrine function than B-I reconstruction.

Differences in glycemic trends due to reconstruction methods after proximal gastrectomy from the perspective of continuous glucose-monitoring.

PURPOSE: In recent years, clinicians have focused on the importance of preventing hypoglycemia. We evaluated the impact of different reconstruction procedures after proximal gastrectomy on glycemic variability in non-diabetic patients with gastric cancer. METHODS: This prospective observational study was conducted between April 2020 and March 2023. Flash continuous glucose-monitoring, a novel method for assessing glycemic control, was used to evaluate the glycemic profiles after gastrectomy. A flash continuous glucose-monitoring sensor was placed subcutaneously at the time of discharge, and glucose trends were evaluated for 2 weeks. RESULTS: The anastomotic methods for proximal gastrectomy were esophagogastrostomy in 10 patients and double-tract reconstruction in 10 patients. The time below this range (glucose levels < 70 mg/dL) was significantly higher in the double-tract reconstruction group than in the esophagogastrostomy group (p = 0.049). A higher nocturnal time below this range was significantly correlated with an older age and double-tract reconstruction (p = 0.025 and p = 0.025, respectively). CONCLUSION: These findings provide new insights into reconstruction methods after proximal gastrectomy by assessing postoperative hypoglycemia in non-diabetic patients with gastric cancer.

Changes in and clinical utility of maximum phonation time and repetitive saliva swallowing test scores after esophagectomy.

BACKGROUND: Postoperative pneumonia in patients with esophageal cancer occurs due to swallowing dysfunction and aspiration. Recently, maximum phonation time (MPT) assessment and repetitive saliva swallowing test (RSST) have been focused on as swallowing function assessment methods that can identify patients as high risk for pneumonia. We aimed to evaluate the clinical utility of MPT assessment and RSST in patients undergoing oncological esophagectomy. METHODS: In total, 47 consecutive patients who underwent esophagectomy for esophageal cancer between August 2020 and July 2023 were eligible. The perioperative changes in MPTs and RSST scores were examined. In addition, univariate and multivariate analyses were performed to identify the predictive factors of postoperative pneumonia. RESULTS: The median MPTs before surgery and on postoperative days (PODs) 3, 6, and 10 were 18.4, 7.2, 10.6, and 12.4 s, respectively; postoperative MPTs were significantly lower than preoperative MPT. In addition, the MPT of POD 6 was significantly longer than that of POD 3 (P < 0.05). Meanwhile, there were no significant changes in perioperative RSST scores. Overall, 8 of 47 patients (17.0%) developed pneumonia postoperatively. A short MPT on POD 6 was one of the independent predictive factors for the incidence of postoperative pneumonia (odds ratio: 12.6, 95% confidence interval: 1.29-123, P = 0.03) in the multivariate analysis. CONCLUSIONS: The MPT significantly decreased after esophagectomy. However, the RSST score did not. The MPT on POD6 can be a predictor of postoperative pneumonia.

Analysis of surgical outcomes and risk factors for anastomotic leakage following trans-hiatal resection of esophagogastric junction cancer.

BACKGROUND: The trans-hiatal lower esophagectomy is considered less invasive than the trans-thoracic esophagectomy for resection of esophagogastric junction (EGJ) cancer. However, the optimal procedure remains controversial and should be determined while considering both oncological and safety aspects. METHODS: This retrospective study comprised 124 patients that underwent curative resection for EGJ cancer. The study analysis included 93 patients with tumor centers located within 2 cm of the EGJ. Clinicopathological findings and surgical outcomes were compared between patients treated using trans-hiatal and trans-thoracic approaches. RESULTS: Sixty-three patients underwent lower esophagectomy using the trans-hiatal approach (TH-G). The remaining 30 patients underwent esophagectomy using the trans-thoracic approach (TT-E). The TH-G group were older, had a lower prevalence of lymphatic spread, shorter length of esophageal invasion, and shorter operative duration compared to the TT-E group. Although no significant differences in the frequency of postoperative complications, a higher proportion of patients in the TH-G group developed anastomotic leakage (16% vs. 7%, p = 0.33). Univariate and multivariate analyses demonstrated that cardiac comorbidity was an independent risk factor for anastomotic leakage (odds ratio, 5.24; 95% CI, 1.06-25.9; P < 0.05) in TH-G group. Further examination revealed that preoperative cardiothoracic ratio (CTR) with 50% or greater could be surrogate marker as risk factor for anastomotic leakage in TH-G group (35% vs. 7.5%, p < 0.05). CONCLUSIONS: The trans-hiatal approach can be used for resection of EGJ cancer. However, special attention should be paid to the prevention of anastomotic leakage in patients with cardiac comorbidities or a large preoperative CTR.

[A Case of Delayed-Onset Acute Interstitial Nephritis following Nivolumab Treatment in a Patient with Advanced Esophagogastric Junction Cancer].

An 81-year-old man with advanced esophagogastric junction cancer with paraaortic lymph node metastasis was treated with S-1 plus oxaliplatin and nivolumab combination chemotherapy. Subsequently, conversion surgery was performed, and the patient was discharged without postoperative complications. Two months after discharge, the patient developed fever, fatigue, and anorexia. Intravenous antibiotic therapy was started; however, the symptoms did not improve. Urine biochemical tests revealed significantly elevated N-acetyl-ß-D-glucosaminidase and ß-microglobulin levels, and acute interstitial nephritis was suspected. Steroid therapy was initiated, and the patient's symptoms improved. A renal biopsy performed at the same time the nivolumab treatment was initiated led to the diagnosis of immune-related interstitial nephritis, a probable adverse event of the treatment. Although immune-related adverse events associated with immune checkpoint inhibitors are typically colitis, interstitial pneumonia, and endocrine disturbances, we observed severe interstitial nephritis in the patient. Clinicians should also consider the possible occurrence of immune-related adverse events >2 months after administering treatment.

[A case of primary peritoneal cancer diagnosed with a duodenal stricture].

A 69-year-old female patient visited the previous hospital with anorexia and vomiting. She had weight loss and emaciation and was admitted to the hospital with a duodenal stenosis diagnosis due to superior mesenteric artery syndrome by computed tomography (CT). Conservative treatment with nutritional therapy was performed, but with no improvement;thus, the patient was referred to our hospital. We re-examined the patient to determine the cause of her disease. CT and magnetic resonance imaging findings revealed peritoneal thickening of the pelvic floor, suggesting malignant disease such as peritoneal dissemination. Therefore, we performed diagnostic laparoscopy and harvested peritoneal tissue. She was diagnosed with primary peritoneal carcinoma by histopathological examination and immunohistochemical staining techniques. Thereafter, she underwent chemotherapy for primary peritoneal cancer at the gynecology department of our hospital but died of the primary disease. Primary peritoneal cancer is frequently diagnosed by abdominal distention and abdominal pain due to ascites accumulation. We report this case because of the rarity of primary peritoneal cancer triggered by duodenal stricture.

[Long-Term Prognosis of Patients with Biliary Tract Cancer Undergoing Pancreaticoduodenectomy].

We divided the patients with biliary tract cancer who underwent pancreaticoduodenectomy(PD)at our hospital into the 5-year recurrence-free and recurrence groups and investigated the prognostic factors. Additionally, we investigated the efficacy of adjuvant chemotherapy in patients with and without lymph node (LN) metastasis. There was no significant difference between the two groups for patient characteristics and perioperative factors. However, patients with LN metastasis tended to have a higher recurrence rate. For patients without LN metastasis, the median overall survival(OS)was not significantly different between the patients who received and did not receive adjuvant chemotherapy. For patients with LN metastasis, although it was not significantly different(p=0.234), the OS of patients who received adjuvant therapy was more than 3 times than that of patients who did not(58.6 months and 18.4 months, respectively). For patients with biliary tract cancer who underwent PD, positive LN metastasis may be a poor prognostic factor, and adjuvant therapy may possibly improve prognosis.

Prognostic Significance of Hiatal Hernia in Patients with Gastric Cancer Located within the Upper-Third of the Stomach.

BACKGROUND: Gastric cancers located within the upper-third of the stomach (UGC), especially the esophagogastric junction GC (EGJGC), have distinct clinicopathological features due to their potential for multidirectional lymphatic spread. In this study, we investigated the clinical significance of hiatal hernias (HH) in patients with UGC, including EGJGC. METHODS: In this retrospective study, we assessed status of HH in 147 patients with UGC who underwent curative resection at our hospital and examined the correlation between the presence of HH (+) and multiple clinicopathological factors. RESULTS: Thirty-four patients (23%) were HH (+). However, we found no significant correlation between HH (+) and clinicopathological factors. HH (+) patients frequently developed lymph node recurrences. Prognosis was significantly better in patients with UGC and HH (-), compared to those with UGC and HH (+). Similarly, EGJGC patients who were HH (-) showed superior survival compared to HH (+) patients. Multivariate analysis found that the HH (+) (p = 0.004), histological type (p = 0.029), and nodal stage (p = 0.034) were independent prognostic factors. CONCLUSIONS: The presence of HH might affect lymphatic spread of tumor cells, and consequently prognosis of patients with UGC. Therefore, special attention is needed in developing surgical and postoperative strategies for such patients with UGC who are HH (+).

The impact of histological type on the accuracy of preoperative N staging in patients with gastric cancer.

BACKGROUND: The low accuracy of preoperative diagnosis of lymph node metastasis in gastric cancer (GC) complicates decisions on patient indication for neoadjuvant chemotherapy. METHODS: We investigated the use of preoperative clinical diagnosis of lymph node involvement (cN) in GC patients compared with postoperative pathological diagnosis. RESULTS: In a series of 265 patients enrolled at the University of Yamanashi Hospital, the overall sensitivity was 44.4% and specificity was 93.4% of CT for detecting lymph node metastasis. The positive and negative predictive values were 80.0% and 73.8%, respectively. The negative predictive value was lower for undifferentiated adenocarcinoma than that for differentiated adenocarcinoma (64.9% vs. 78.7%, p = 0.034). In cT2 ≤ and cN2 ≤ GC, overdiagnosis of lymph node metastasis was significantly more frequent in patients with differentiated (50.0%) than in undifferentiated (13.3%) adenocarcinoma (p = 0.046). CONCLUSIONS: Diagnostic accuracy of lymph node involvement depended on histological type and cT-stage. Thus, considering preoperative histological type in GC, it may be useful to decide treatment plan.

Validity of additional surgical resection by comparing the operative risk with the stratified lymph node metastatic risk in patients with early gastric cancer after endoscopic submucosal dissection.

BACKGROUND: Treatment guidelines for early gastric cancer (EGC) recommend additional gastrectomy for lesions which do not achieve curative resection after ESD, due to the potential risk of lymph node metastasis (LNM). However, many cases are found to have no LNMs, and additional gastrectomy itself can be a considerable risk especially in elderly patients. METHODS: We retrospectively stratified the risk of LNM according to the total number of four LNM risk factors (RFs) that resulted in non-curative resection for ESD in 861 EGC patients who underwent gastrectomy. Next, we compared this stratification risk to the surgical risk based on the National Clinical Database (NCD) risk calculator in 58 patients who underwent additional gastrectomy. RESULTS: As the total number of LNM RFs increased, the frequency of LNM also increased significantly (0/1RF 0.76%, 2RFs 15.08%, 3RFs 33.87%, 4RFs 50.00%; p < 0.01). The estimated frequency of LNM was found to be lower than the predicted value of in-hospital mortality rate based on the NCD risk calculator in 25.0% of 0/1RF patients. CONCLUSION: These findings indicate, at least, that we should discuss the indication of additional gastrectomy individually for each patient from both perspectives of LNM and surgical risks.

Long-term outcomes after surgical resection in patients with stage IV colorectal cancer: a retrospective study of 129 patients at a single institution.

BACKGROUND AND PURPOSE: Approximately 20% of all patients with colorectal cancer (CRC) are diagnosed at more advanced stages with synchronous distant metastasis, and the prognosis in these patients is usually poor. The aim of this study was to determine the factors that can identify subgroup(s) of patients with stage IV CRC who could benefit from curative (R0) resection of both primary and metastatic lesions. PATIENTS AND METHODS: A total of 126 patients with stage IV CRC who underwent surgical resection of primary tumor were retrospectively analyzed. Among these patients, 26 cases of R0 resection were further examined subsequently. Information on various clinicopathological factors of the patients were obtained from hospital records. Overall survival was estimated using the Kaplan-Meier method, and log-rank tests were used to compare survival distribution. All the factors with P < 0.05 in univariate analysis were analyzed in the Cox proportional hazards model. RESULTS: CEA negativity, left-sided tumor, R0 resection, differentiated histology, and nodal staging less than N1 were independent factors that predicted better prognosis in all the 126 patients with stage IV CRC. Tumor depth of T3 or less was significantly correlated with better survival in patients who had undergone R0 resection. CONCLUSION: Our findings demonstrate that it is possible to select patients in whom surgical resection would yield better prognosis, from a variety of patient subgroups with stage IV CRC.

[Efficacy of Surgery and Adjuvant Chemotherapy for Distal Cholangiocarcinoma].

INTRODUCTION: Surgery alone shows an insufficient result for distal cholangiocarcinoma, and postoperative adjuvant chemotherapy is commonly used. However, no definite opinion has yet been accepted. SUBJECTS AND METHODS: A group of 46 patients who underwent surgery for distal bile duct cancer and who received adjuvant chemotherapy including gemcitabine (GEM)(Group A)and surgery alone group(Group S)were compared for disease-free survival(DFS)and overall survival (OS). RESULTS: Although the median DFS was 718 days in Group A and 367 days in Group S(p=0.306)and the median OS was 1,171 days in Group A and 859 days in Group S(p=0.07), no significant difference was observed; however, the prognosis improved. CONCLUSION: Postoperative adjuvant chemotherapy may improve prognosis.

PD-L1 expression is mainly regulated by interferon gamma associated with JAK-STAT pathway in gastric cancer.

Despite multidisciplinary treatment for patients with advanced gastric cancer, their prognosis remains poor. Therefore, the development of novel therapeutic strategies is urgently needed, and immunotherapy utilizing anti-programmed death 1/-programmed death ligand-1 mAb is an attractive approach. However, as there is limited information on how programmed death ligand-1 is upregulated on tumor cells within the tumor microenvironment, we examined the mechanism of programmed death ligand-1 regulation with a particular focus on interferon gamma in an in vitro setting and in clinical samples. Our in vitro findings showed that interferon gamma upregulated programmed death ligand-1 expression on solid tumor cells through the JAK-signal transducer and activator of transcription pathway, and impaired the cytotoxicity of tumor antigen-specific CTL against tumor cells. Following treatment of cells with anti-programmed death ligand-1 mAb after interferon gamma-pre-treatment, the reduced anti-tumor CTL activity by interferon gamma reached a higher level than the non-treatment control targets. In contrast, programmed death ligand-1 expression on tumor cells also significantly correlated with epithelial-mesenchymal transition phenotype in a panel of solid tumor cells. In clinical gastric cancer samples, tumor membrane programmed death ligand-1 expression significantly positively correlated with the presence of CD8-positive T cells in the stroma and interferon gamma expression in the tumor. The results suggest that gastric cancer patients with high CD8-positive T-cell infiltration may be more responsive to anti-programmed death 1/-programmed death ligand-1 mAb therapy.

Current Ventilator and Oxygen Management during General Anesthesia: A Multicenter, Cross-sectional Observational Study.

BACKGROUND: Intraoperative oxygen management is poorly understood. It was hypothesized that potentially preventable hyperoxemia and substantial oxygen exposure would be common during general anesthesia. METHODS: A multicenter, cross-sectional study was conducted to describe current ventilator management, particularly oxygen management, during general anesthesia in Japan. All adult patients (16 yr old or older) who received general anesthesia over 5 consecutive days in 2015 at 43 participating hospitals were identified. Ventilator settings and vital signs were collected 1 h after the induction of general anesthesia. We determined the prevalence of potentially preventable hyperoxemia (oxygen saturation measured by pulse oximetry of more than 98%, despite fractional inspired oxygen tension of more than 0.21) and the risk factors for potentially substantial oxygen exposure (fractional inspired oxygen tension of more than 0.5, despite oxygen saturation measured by pulse oximetry of more than 92%). RESULTS: A total of 1,786 patients were found eligible, and 1,498 completed the study. Fractional inspired oxygen tension was between 0.31 and 0.6 in 1,385 patients (92%), whereas it was less than or equal to 0.3 in very few patients (1%). Most patients (83%) were exposed to potentially preventable hyperoxemia, and 32% had potentially substantial oxygen exposure. In multivariable analysis, old age, emergency surgery, and one-lung ventilation were independently associated with increased potentially substantial oxygen exposure, whereas use of volume control ventilation and high positive end-expiratory pressure levels were associated with decreased potentially substantial oxygen exposure. One-lung ventilation was particularly a strong risk factor for potentially substantial oxygen exposure (adjusted odds ratio, 13.35; 95% CI, 7.24 to 24.60). CONCLUSIONS: Potentially preventable hyperoxemia and substantial oxygen exposure are common during general anesthesia, especially during one-lung ventilation. Future research should explore the safety and feasibility of a more conservative approach for intraoperative oxygen therapy.

Upregulation of thioredoxin-1 in activated human NK cells confers increased tolerance to oxidative stress.

Adoptive transfer of immune cells, such as T lymphocytes and NK cells, has potential to control cancer growth. However, this can be counteracted by immune escape mechanisms within the tumor microenvironment, including those mediated by reactive oxygen species (ROS). Here, we determined the levels of anti-oxidant molecules in NK cells and their capacity to overcome ROS-induced immune suppression. We investigated the effect of H2O2 on resting NK cells, IL-2-activated NK cells and NK cells expanded by coculture with the K562 leukemia cell line genetically modified to express membrane-bound IL-15 and 4-1BB ligand (K562-mb15-41BBL). Expression of anti-oxidant and anti-apoptotic genes was evaluated by expression array, and protein levels of anti-oxidant molecules by Western blot. Activated NK cells, IL-2-activated NK cells and NK cells expanded by K562-mb15-41BBL were significantly more resistant to H2O2-induced cell death than resting NK. Thioredoxin-1 (TXN1) and peroxiredoxin-1 (PRDX1) were also up-regulated in activated NK cells. Moreover, H2O2-induced cell death after IL-2 activation was significantly induced in the presence of an anti-TXN1-neutralising antibody. Collectively, these data document that activated NK cells can resist to H2O2-induced cell death by up-regulation of TXN1.

[The Mechanism of HLA Class I and PD-L1 Expression of Cancer Cells in Tumor Microenvironment].

HLA class I and PD-L1expressed on cancer cells play a pivotal role in the CTL recognition mechanism against cancer cells in the tumor microenvironment. It is well known that IFN-g upregulates PD-L1as well as HLA class I expression in cancer cells, and it is suggested that TILs, including CTL, produce IFN-g in the tumor microenvironment. Therefore, there is a possibility that IFN-g produced by activated TILs upregulate both HLA class I and PD-L1expression in cancer cells in the tumor microenvironment. We propose that the anti-tumor effect of CTL could be enhanced if the inhibition of CTL recognition mechanism against cancer cells via the PD-1/PD-L1pathway is canceled by anti-PD-1or anti-PD-L1antibody.

The MAPK pathway is a predominant regulator of HLA-A expression in esophageal and gastric cancer.

Downregulation of HLA class I expression may contribute to a poor prognosis in cancer patients. There is limited information about epigenetic and oncogenic regulation of HLA class I, and multiple mechanisms may be involved. In the current study, we examined the relationship between the HER2-signaling pathway (MAPK and PI3K-Akt) and the expression of HLA class I and Ag-processing machinery (APM) components. A panel of gastric and esophageal cancer cell lines was treated with wortmannin as an Akt-signal inhibitor; the MAPK signal inhibitor PD98059; lapatinib, which inhibits both the epidermal growth factor receptor and HER2 tyrosine kinase; or siRNA for MAPK. The levels of HER2-signaling molecules, APM components, and HLA class I were evaluated by Western blot, quantitative PCR, and flow cytometry. Resected gastric tumor tissues (n = 102) were analyzed for p-Erk and HLA class I expression by immunohistochemistry. As a result, inhibition of the MAPK pathway induced upregulation of HLA-A02 and HLA-A24 expression in parallel with an increase in APM components and enhanced target sensitivity to tumor Ag-specific CTL lysis. HLA-A expression was predominantly regulated by the MAPK pathway, but it was also influenced, in part, by the Akt pathway. There was a strong inverse correlation between p-Erk expression and HLA class I expression in clinical tumor samples. In conclusion, HLA-A expression is predominantly regulated by the MAPK pathway in gastric and esophageal cancer.

Therapeutic potential of highly cytotoxic natural killer cells for gastric cancer.

To develop more effective therapies for patients with advanced gastric cancer, we examined the potential of ex vivo expanded natural killer (NK) cells. We assessed the expression of ligands for NK Group 2 Member D (NKG2D, an important NK activation molecule) in primary tumors from 102 patients with gastric cancer by immunohistochemistry and determined their prognostic value. We then examined the in vitro and in vivo cytotoxicity of NK cells from healthy donors and patients with gastric cancer. The cytotoxicity of resting and of interleukin (IL)-2-activated NK cells was compared to that of NK cells expanded for 7 days by coculture with the K562-mb15-4.1BBL cell line. As a result, the expression of NKG2D ligands in primary tumors was correlated with favorable presenting features and outcomes, suggesting that gastric cancer may be sensitive to NK cell cytotoxicity. Although resting NK cells showed minimal cytotoxicity against gastric cancer cells, K562-mb15-4.1BBL-expanded NK cells were highly cytotoxic and significantly more powerful than IL-2-activated NK cells. Cytotoxicity was correlated with NKG2D ligand expression and could be modulated by mitogen-activated protein kinase and AKT-PI3 kinase inhibitors. The cytotoxicity of expanded NK cells against HER2-positive gastric cancer cells could be increased by Herceptin and further augmented by Lapatinib. Finally, expanded NK cells exhibited strong antitumor activity in immunodeficient mice engrafted with a gastric cancer cell line. In conclusion, gastric cancer tumors express NKG2D ligands and are highly susceptible to killing by NK cells stimulated by K562-mb15-4.1BBL. These results provide a strong rationale for clinical testing of these NK cells in patients and suggest their use to augment the effects of antibody therapy.