Long-term Survival with a Rare Advanced Primary Gastrointestinal Malignant Melanoma Treated with Laparoscopic Surgery/Immune Checkpoint Inhibitor.

Targeted therapies for malignant melanoma have improved patients' prognoses. A primary gastrointestinal malignant melanoma is very rare, with no standard treatment strategy. We treated a 78-year-old Japanese female with advanced primary gastrointestinal melanoma of the descending colon and gallbladder. We administered a multidisciplinary treatment: surgical resection of the descending colon and gallbladder tumors, resection of the metastatic lymph nodes behind the pancreas head, and immune checkpoint antibody-blockade therapy (nivolumab) for ~4 years. PET/CT demonstrated no recurrent lesion for > 3 years. Multidisciplinary therapies (e.g., surgery, chemotherapy, radiotherapy, target therapy, and immune checkpoint antibody-blockade therapy) can successfully treat primary gastrointestinal malignant melanoma.

Antitumor activity of pan-HER inhibitors in HER2-positive gastric cancer.

Molecularly targeted therapy has enabled outstanding advances in cancer treatment. Whereas various anti-human epidermal growth factor receptor 2 (HER2) drugs have been developed, trastuzumab is still the only anti-HER2 drug presently available for gastric cancer. In this study, we propose novel treatment options for patients with HER2-positive gastric cancer. First, we determined the molecular profiles of 12 gastric cancer cell lines, and examined the antitumor effect of the pan-HER inhibitors afatinib and neratinib in those cell lines. Additionally, we analyzed HER2 alteration in 123 primary gastric cancers resected from Japanese patients to clarify possible candidates with the potential to respond to these drugs. In the drug sensitivity analysis, both afatinib and neratinib produced an antitumor effect in most of the HER2-amplified cell lines. However, some cells were not sensitive to the drugs. When the molecular profiles of the cells were compared based on the drug sensitivities, we found that cancer cells with lower mRNA expression levels of IGFBP7, a tumor suppressor gene that inhibits the activation of insulin-like growth factor-1 receptor (IGF-1R), were less sensitive to pan-HER inhibitors. A combination therapy consisting of pan-HER inhibitors and an IGF-1R inhibitor, picropodophyllin, showed a notable synergistic effect. Among 123 clinical samples, we found 19 cases of HER2 amplification and three cases of oncogenic mutations. In conclusion, afatinib and neratinib are promising therapeutic options for the treatment of HER2-amplified gastric cancer. In addition to HER2 amplification, IGFBP7 might be a biomarker of sensitivity to these drugs, and IGF-1R-targeting therapy can overcome drug insensitiveness in HER2-amplified gastric cancer.

Arterial stiffness in junior high school students: Longitudinal observations.

BACKGROUND: Early atherosclerotic change is found even in childhood, and there is an urgent need to clarify the factors causing childhood atherosclerosis and take preventive measures. Early detection of the contributing risk factors is crucial to facilitate preventive measures. Pulse wave velocity (PWV) is a widely used technique for the assessment of atherosclerosis in children. METHODS: Lifestyle questionnaire, brachio-ankle PWV (baPWV) and anthropometric data were obtained from junior high school students in an urban area of Japan between 2006 and 2008, from seventh to ninth grades. RESULTS: Mean baPWV increased from 867.4 ± 99.5 m/s to 944.5 ± 117.5 m/s in boys, and from 864.0 ± 99.5 m/s to 923.0 ± 101.3 m/s in girls. Obese students had higher baPWV than non-obese students in both genders across each grade. On logistic regression analysis of ninth grade student data, high baPWV was dependent on systolic blood pressure (SBP), time watching television (TV) and symptoms of depression and anxiety, whereas low baPWV was dependent on time playing video games, light exercise, sleep and indoor play, as well as good friendship and motivation. CONCLUSION: Systolic blood pressure, time watching TV, and symptoms of depression and anxiety may contribute to arterial stiffness and be related to obesity in junior high school students.

High Maternal Age and Low Pre-Pregnancy Body Mass Index Correlate with Lower Birth Weight of Male Infants.

In Japan, the percentage of leanness has been increasing in young women, and the percentage of low birth weight infants (< 2,500 g) has increased. Moreover, the average age of primiparas rose 3.5 years during the last 30 years. The purpose of this study was to clarify the relationship between maternal age and the influence of maternal pre-pregnancy physique on the neonatal physique of infants. Questionnaires were issued to the participants and collected when they submitted their gestational notifications at their local ward office in Kyoto Prefecture. After delivery, we obtained information on the course of the pregnancy and the neonatal physique of the infants from the participant's maternal passbooks. A total of 454 mothers (age 20 ≥) were analyzed: 161 young mothers (aged 20 to 29 years), 185 mothers (aged 30 to 34 years), and 108 older mothers (age ≥ 35). Overall, the mean rate of leanness (pre-pregnancy BMI < 18.5) was 23.8%. We found that birth weight was significantly lower in female infants, born to lean young mothers, compared to non-lean young mothers, whereas no significant difference was detected in other mothers (age ≥ 30), irrespective of pre-pregnancy BMI. By contrast, male infants, born to older lean mothers (age ≥ 35), showed significantly lower birth weight. Thus, maternal pre-pregnancy BMI exerts differential effects on the fetal growth (neonatal physique), depending on the maternal age and the sex of infants. We need to improve BMI in pre-pregnancy women, especially those in the twenties and 35 years old or over.

Effects of implementing an "enhanced recovery after surgery" program on patients undergoing resection of hepatocellular carcinoma.

PURPOSE: To evaluate the effects of implementing an "enhanced recovery after surgery" (ERAS) program on the feasibility, safety, and effectiveness of extensive and potentially curative liver resection for hepatocellular carcinoma (HCC). METHODS: We compared clinicopathologic factors, surgical factors, and outcomes of patients who underwent extended hepatectomy (defined as resection of more than two sections) for HCC, before and after the introduction of an ERAS program. RESULTS: Operating times and postoperative hospital stay were significantly shorter, and total volume infused during surgery was significantly lower, for the ERAS group than for the control group. Although the ERAS group had a significantly lower percentage of patients with retention of abdominal drainage, this group had a higher frequency of abdominal paracentesis in patients without intraoperative abdominal drainage. Oral dietary intake and the ability to walk steadily resumed significantly earlier in the ERAS group. Postoperative serum concentrations of albumin and cholinesterase were significantly higher in the ERAS group than in the control group. CONCLUSIONS: The ERAS program was feasible and effective for patients with chronic liver disease undergoing extended liver resection for HCC, because it allowed earlier oral dietary intake and promoted faster postoperative recovery.

Antitumor effect of afatinib, as a human epidermal growth factor receptor 2-targeted therapy, in lung cancers harboring HER2 oncogene alterations.

Human epidermal growth factor receptor 2 (HER2) is a member of the HER family of proteins containing four receptor tyrosine kinases. It plays an important role in the pathogenesis of certain human cancers. In non-small-cell lung cancer (NSCLC), HER2 amplification or mutations have been reported. However, little is known about the benefit of HER2-targeted therapy for NSCLCs harboring HER2 alterations. In this study, we investigated the antitumor effect of afatinib, an irreversible epidermal growth factor receptor (EGFR)-HER2 dual inhibitor, in lung cancers harboring HER2 oncogene alterations, including novel HER2 mutations in the transmembrane domain, which we recently identified. Normal bronchial epithelial cells, BEAS-2B, ectopically overexpressing wild-type HER2 or mutants (A775insYVMA, G776VC, G776LC, P780insGSP, V659E, and G660D) showed constitutive autophosphorylation of HER2 and activation of downstream signaling. They were sensitive to afatinib, but insensitive to gefitinib. Furthermore, we examined the antitumor activity of afatinib and gefitinib in several NSCLC cell lines, and investigated the association between their genetic alterations and sensitivity to afatinib treatment. In HER2-altered NSCLC cells (H2170, Calu-3, and H1781), afatinib downregulated the phosphorylation of HER2 and EGFR as well as their downstream signaling, and induced an antiproliferative effect through G1 arrest and apoptotic cell death. In contrast, HER2- or EGFR-non-dependent NSCLC cells were insensitive to afatinib. In addition, these effects were confirmed in vivo by using a xenograft mouse model of HER2-altered lung cancer cells. Our results suggest that afatinib is a therapeutic option as a HER2-targeted therapy for NSCLC harboring HER2 amplification or mutations.

Prospectively Isolated Human Bone Marrow Cell-Derived MSCs Support Primitive Human CD34-Negative Hematopoietic Stem Cells.

Hematopoietic stem cells (HSCs) are maintained in a specialized bone marrow (BM) niche, which consists of osteoblasts, endothelial cells, and a variety of mesenchymal stem/stromal cells (MSCs). However, precisely what types of MSCs support human HSCs in the BM remain to be elucidated because of their heterogeneity. In this study, we succeeded in prospectively isolating/establishing three types of MSCs from human BM-derived lineage- and CD45-negative cells, according to their cell surface expression of CD271 and stage-specific embryonic antigen (SSEA)-4. Among them, the MSCs established from the Lineage(-) CD45(-) CD271(+) SSEA-4(+) fraction (DP MSC) could differentiate into osteoblasts and chondrocytes, but they lacked adipogenic differentiation potential. The DP MSCs expressed significantly higher levels of well-characterized HSC-supportive genes, including IGF-2, Wnt3a, Jagged1, TGFß3, nestin, CXCL12, and Foxc1, compared with other MSCs. Interestingly, these osteo-chondrogenic DP MSCs possessed the ability to support cord blood-derived primitive human CD34-negative severe combined immunodeficiency-repopulating cells. The HSC-supportive actions of DP MSCs were partially carried out by soluble factors, including IGF-2, Wnt3a, and Jagged1. Moreover, contact between DP MSCs and CD34-positive (CD34(+) ) as well as CD34-negative (CD34(-) ) HSCs was important for the support/maintenance of the CD34(+/-) HSCs in vitro. These data suggest that DP MSCs might play an important role in the maintenance of human primitive HSCs in the BM niche. Therefore, the establishment of DP MSCs provides a new tool for the elucidation of the human HSC/niche interaction in vitro as well as in vivo.

Human collagen XV is a prominent histopathological component of sinusoidal capillarization in hepatocellular carcinogenesis.

BACKGROUND: Increased expression of collagen XV has been reported in hepatocellular carcinogenesis in mice. The aim of this study was to confirm the previous murine findings in human hepatocellular carcinoma (HCC) specimens, along with the histopathological distribution of collagen XV in tumoral tissues. METHODS: Sixty-three primary HCC specimens were examined. Immunostaining of collagen XV and quantitative reverse transcriptional PCR of COL15A1, which encodes collagen XV, were performed. RESULTS: Positive staining of collagen XV was observed in all tumoral regions, regardless of differentiation level or pathological type of HCC, along the sinusoid-like endothelium, whereas collagen XV was not expressed in any non-tumoral region. The intensity score of collagen XV immunostaining and the mRNA value of COL15A1 were significantly correlated. COL15A1 expression in tumors was 3.24-fold higher than in non-tumoral regions. Multivariate analysis showed that COL15A1 expression was significantly higher in the absence of hepatitis virus and moderately differentiated HCC. CONCLUSIONS: COL15A1 mRNA was up-regulated in HCC and collagen XV was expressed along the sinusoid-like endothelium of HCC but not in non-tumoral regions, which implies that collagen XV contributes to the capillarization of HCC.

Acquisition of cancer stem cell-like properties in non-small cell lung cancer with acquired resistance to afatinib.

Afatinib is an irreversible epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI) that is known to be effective against the EGFR T790M variant, which accounts for half of the mechanisms of acquired resistance to reversible EGFR-TKIs. However, acquired resistance to afatinib was also observed in clinical use. Thus, elucidating and overcoming the mechanisms of resistance are important issues in the treatment of non-small cell lung cancer. In this study, we established various afatinib-resistant cell lines and investigated the resistance mechanisms. EGFR T790M mutations were not detected using direct sequencing in established resistant cells. Several afatinib-resistant cell lines displayed MET amplification, and these cells were sensitive to the combination of afatinib plus crizotinib. As a further investigation, a cell line that acquired resistance to afatinib plus crizotinib, HCC827-ACR, was established from one of the MET amplified-cell lines. Several afatinib-resistant cell lines including HCC827-ACR displayed epithelial-to-mesenchymal transition (EMT) features and epigenetic silencing of miR-200c, which is a suppresser of EMT. In addition, these cell lines also exhibited overexpression of ALDH1A1 and ABCB1, which are putative stem cell markers, and resistance to docetaxel. In conclusion, we established afatinib-resistant cells and found that MET amplification, EMT, and stem cell-like features are observed in cells with acquired resistance to EGFR-TKIs. This finding may provide clues to overcoming resistance to EGFR-TKIs.

Maternal Body Mass Index Correlates with the Neonatal Physique of Male Infants.

Recently, in Japan, the percentage of leanness has risen in young women, and the average birth weight has decreased. An increase in the risk of low birth weight has been reported in lean expectant mothers. In this study, we aimed to clarify the relationship between mother's physique at the beginning of pregnancy and the infant's physique, by focusing on sex differences. The participants were 3,722 mothers who attended health checkups for 18-month-old infants in an urban Japanese city. The participants were limited to those with full-term births, thereby excluding the influence of gestational length. A total of 1,287 mothers, with 621 boys and 666 girls, were analyzed. Public health professionals interviewed the mothers, and transferred the required information from their maternity passbooks. We examined the physical characteristics of the mothers and their infants. Partial correlation analysis, adjusted by gestational length and the mother's age at delivery, was applied to study the association between the mother's BMI and the infant's physique at birth. In the primipara group, only the boys showed significant positive correlation between the mother's BMI and the birth weight (P = 0.025) and the Kaup index (P = 0.035). In the pluripara group, only the boys showed significant positive correlation between the mother's BMI and the head circumference (P = 0.035). Thus, mother's physique may have a stronger influence on the physique of male infants, compared to female infants. The growth-promoting effect of the mother's physique is more apparent in the infants born to the pluripara.

Preclinical evaluation of microRNA-34b/c delivery for malignant pleural mesothelioma.

The microRNA-34s (miR-34s) have p53 response elements in their 5'-flanking regions and demonstrate tumor-suppressive functions. In malignant pleural mesothelioma (MPM), we previously reported that expression of miR-34b and miR-34c (miR-34b/c) was frequently downregulated by methylation in MPM cell lines and primary tumors. The forced overexpression of miR-34b/c showed significant antitumor effects with the induction of apoptosis in MPM cells. In this study, we examined the in vivo antitumor effects of miR-34b/c using adenovirus vector on MPM. We subcutaneously transplanted NCI-H290, a human MPM cell line, into BALB/C mice and injected adenovirus vector expressing miR-34b/c, luciferase driven by the cytomegalovirus promoter (Ad-miR-34b/c or Ad-Luc), or PBS control into tumors over 5mm in diameter. A statistically significant growth inhibition of the tumor volume was observed in the Ad-miR-34b/c group from day 6 onward compared to the Ad-Luc group. The inhibition rate of Ad-miR-34b/c, compared to the tumor volume treated with Ad-Luc, was 58.6% on day 10 and 54.7% on day13. Our results indicate that adenovirus-mediated miR-34b/c gene therapy could be useful for the clinical treatment of MPM.

Multiple enteric muco-submucosal elongated polyps causing intussusception.

A 20-year-old woman presented to our hospital with abdominal pain. Abdominal computed tomography revealed multiple masses in the upper jejunum, which were suspected as lipomas. Partial resection of the small intestine, including the masses, was performed on the same day due to intussusception secondary to the masses. Pathological examination revealed that the masses consisted of mucosa and edematous submucosa with multiple dilated blood vessels and lymphatic ducts without muscularis propria. The masses were diagnosed as multiple muco-submucosal elongated polyps (MSEP), a type of non-neoplastic polyp. MSEP was originally named colonic MSEP, but with the development of endoscopic techniques and imaging tests, similar polyps have been reported to occur not only in the colon but also in the entire intestinal tract. In this case, multiple MSEPs in the upper jejunum caused intussusception. As reported cases of multiple lesions causing intussusception are few, our case may help to clarify the pathogenesis of this disease.

Dietary intervention with cooking instructions and self-monitoring of the diet in free-living hypertensive men.

The control of blood pressure (BP) is important in the prevention of cardiovascular diseases. This study was conducted to evaluate the effect of a dietary educational program for free-living, high-normal, and stage 1 or 2 hypertensive men. The participants were volunteers aged 40-75 years who agreed to the intervention. They were divided into two groups: 39 men for the intervention group and 32 men for the control group. BP, urinary sodium and potassium excretion, dietary and lifestyle data, and nonfasting venous blood sample were collected at baseline and after the intervention period. The intervention was designed to decrease sodium level with an emphasis on a decrease in the consumption of salted foods and to increase potassium level with an emphasis on an increase in the consumption of fruit and vegetables through cooking instructions and self-monitoring of the diet. At the baseline, there were no significant differences observed between the groups, except the diastolic BP. In the intervention group, a greater decrease in the urinary sodium-to-potassium excretion ratio was observed, compared with the control group (net difference 0.6, P = .029). The systolic and diastolic BP (mm Hg) decreased in the intervention group (149.0-143.0, P = .073; 93.0-87.0, P = .002), but no changes were observed in the control group (145.0-143.0, P = .231; 84.9-85.3, P = .381). In the intervention group, the urinary sodium-to-potassium excretion ratio was significantly improved by focusing on cooking instructions and self-monitoring of the diet.

Silenced expression of NFKBIA in lung adenocarcinoma patients with a never-smoking history.

Nuclear factor of κ-light polypeptide gene enhancer in B cells inhibitor α (NFKBIA), which is a tumor suppressor gene, was found to be silenced in lung adenocarcinomas. We examined NFKBIA expression, mutations in the EGFR and K-ras genes, and EML4-ALK fusion in 101 resected lung adenocarcinoma samples from never-smokers. NFKBIA expression was evaluated using immunohistochemistry. NFKBIA expression was negative in 16 of the 101 samples (15.8%). EGFR and K-ras mutations and EML4-ALK fusion were detected in 61 (60.5%), 1 (1.0%), and 2 (2.0%) of the 101 samples, respectively, in a completely mutually exclusive manner. Negative NFKBIA expression was observed significantly more frequently among the tumors with none of the three genetic alterations compared to those with such alterations (p = 0.009). In addition, negative NFKBIA expression was significantly more frequent among the EGFR-wild type samples compared to the EGFR-mutant samples (p = 0.013). In conclusion, NFKBIA expression was silenced in adenocarcinomas without EGFR/K-ras mutations or EML4-ALK fusion, suggesting that the silencing of NFKBIA may play an important role in the carcinogenesis of adenocarcinomas independent of EGFR/K-ras mutations or EML4-ALK fusion.

Predictors and outcome of early recurrence after resection of hepatic metastases from colorectal cancer.

PURPOSE: This study aimed to investigate the risk factors for early recurrence in patients who had undergone curative resection of colorectal liver metastases (CRLM) and to evaluate the outcome after recurrence. METHODS: A total of 119 patients were divided into 2 groups: an early recurrence group (n = 54) who had recurrence within 2 years of curative resection of CRLM and a 2-year recurrence-free group (n = 65) who remained disease-free for at least 2 years following surgery. RESULTS: During the initial 5-year period after surgery, 4 out of 65 patients (6%) in the 2-year recurrence-free group and 29 out of 54 patients (54%) in the early recurrence group died. Multivariate analysis showed that postoperative morbidity was an independent predictor of early recurrence after curative resection of CRLM. CONCLUSIONS: Early recurrence is the leading cause of death within 5 years after curative resection of CRLM. Postoperative morbidity increases the risk of early recurrence in these patients. A reduction in perioperative morbidity may, therefore, improve the outcome of curative resection, as well as reducing medical costs.

Wedge Resection for Duodenal Gastrointestinal Stromal Tumors: Surgical Management and the Clinicopathological Outcome.

We analyzed the clinicopathological characteristics of six patients with duodenal gastrointestinal stromal tumor (dGIST) resected in our hospital between 2005 and 2020. The patients (5 males, 1 female) were aged from 43 to 83 years old (mean: 63.7 years old). With respect to the preoperative diagnosis, one patient was diagnosed with dGIST by a biopsy, and five patients were diagnosed with suspected dGIST by esophagogastroduodenoscopy (EGD). The tumor locations were the third portion in four cases, second portion in one, and fourth portion in one. The pathological stages were I in four patients, II in one, and IIIB in one. All patients were discharged 12.8 days (10-15 days) postoperatively without complications, such as pancreatic fistula or suture deficiency. Regarding the prognosis, all patients are alive without recurrence. The wedge resection is a reasonable option for resection of dGIST and should be routinely considered if technically feasible.

Ileal perforation induced by acute radiation injury under gefitinib treatment.

Enteritis is one of the side effects of radiotherapy to the abdominal cavity. Radiation enteritis involves damage to mucous membranes in the acute phase and to stromal tissues in the late phase. Perforation of the intestine tends to occur in the late phase, and rarely in the acute phase. However, we describe here a case of intestinal perforation occurring in the acute phase after irradiation in a patient who received gefitinib treatment. Gefitinib, one of the epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs), is widely used to treat non-small cell lung cancer (NSCLC) patients, but is simultaneously known to inhibit wound healing. We suspect that gefitinib may affect regeneration of the small intestinal mucosa injured by irradiation. A 76-year-old woman had NSCLC with metastases to the 5th lumbar, sacral, and right iliac bones. To control the pain from bone metastasis, anterior-posterior opposing portal irradiation (total 35 Gy) was started, and was completed over 22 days. On day 25 after starting radiotherapy, the patient began to take gefitinib. On day 35, she presented with acute peritonitis, and an emergency laparotomy was performed. The terminal ileum was affected by radiation enteritis and there were two pin-hole perforations. In the surgical specimen, no cancerous lesions were detected, and immunohistochemical staining of phosphorylated EGFR (pEGFR) was negative. pEGFR has an important role in mucous membrane repair after irradiation. Intestinal perforation in the acute phase of radiation enteritis may be associated with impaired mucosal repair mechanisms due to the use of an EGFR-TKI such as gefitinib, as evidenced by the absence of pEGFR.

Aberrant methylation of p21 gene in lung cancer and malignant pleural mesothelioma.

Suppression of p21 has been implicated in the genesis and progression of many human malignancies. DNA methylation is an important mechanism of gene silencing in human malignancies. In this study, we examined the expression status and aberrant methylaion of p21 in lung cancers and malignant pleural mesotheliomas (MPM). We used 12 small cell lung cancer (SCLC) cell lines, 13 non-small cell lung cancer (NSCLC) cell lines, 50 primary NSCLCs, 6 MPM cell lines and 10 primary MPMs. The expression and methylation of p21 was examined by reverse transcription-PCR (RT-PCR), Western blotting and methylation-specific PCR (MSP) assay. Loss of p21 protein expression was observed in 7 SCLC cell lines (58.3%), 5 NSCLC cell lines (38.5%) and 3 MPM cell lines (50%) while mRNA expression was lost in 2 SCLC cell lines (16.7%), 2 NSCLC cell lines (15.4%) and none of the MPM cell lines. Aberrant methylation of p21 was found in 8.3% of SCLC cell lines, 30.2% of NSCLCs and 6.3% of MPMs. Among primary NSCLCs, methylation in adenocarcinomas was significantly more frequent than in squamous cell carcinomas. Loss of p21 expression was frequently observed in lung cancers and MPMs and aberrant methylation was one of the mechanisms of suppression of p21, especially in NSCLCs.

Impact of endoscopic and histological evaluations of two different types of mesh plug for a groin hernia model.

PURPOSE: The biological responses to mesh in vivo have been evaluated in some papers, but the in vivo condition of mesh and plugs have not been sufficiently evaluated. This study evaluated the endoscopic observations and histological assessments of mesh plugs using swine models. METHODS: An artificial abdominal hernia was established in the porcine abdomen, and repaired using three different sizes of two types of plug, Proloop (ATRIUM Medical Corporation, Hudson, NH, USA) or Perfix (BARD Medical Division, Covington, GA, USA). The in vivo conditions of each plug were periodically observed using a laparoscope. Moreover, a histological evaluation of the plugs was performed 3 months after implantation. RESULTS: The laparoscopic observation revealed that inversion of the plugs occurred in 10 out of 18 cases repaired with Perfix, while no case repaired with Proloop inverted. The large and medium sizes of Perfix plugs were inclined by an average of more than 30°. In addition, the triangular shape of Perfix plugs was broken and the vertical/horizontal ratio was enlarged during the observation period, while Proloop plugs shrank both vertically and horizontally. The inflammatory cell count was significantly lower within the Proloop plugs than within Perfix plugs. CONCLUSION: Proloop plugs are apparently superior because they are stable even 3 months after implantation.

In vitro and in vivo radiosensitization with AZD6244 (ARRY-142886), an inhibitor of mitogen-activated protein kinase/extracellular signal-regulated kinase 1/2 kinase.

PURPOSE: The mitogen-activated protein (MAP) kinase pathway is important for cell proliferation, survival, and differentiation, and is frequently up-regulated in cancers. The MAP kinase pathway is also activated after exposure to ionizing radiation. We investigated the effects of AZD6244 (ARRY-142886), an inhibitor of MAP kinase/extracellular signal-regulated kinase 1/2, on radiation response. EXPERIMENTAL DESIGN: The effects of AZD6244 on the in vitro radiosensitivity of human cancer cell lines (A549, MiaPaCa2, and DU145) were evaluated using clonogenic assays. DNA damage repair was evaluated using gammaH2AX, and mitotic catastrophe was measured using nuclear fragmentation. Cell cycle effects were measured with flow cytometry. Growth delay was used to evaluate the effects of AZD6244 on in vivo tumor radiosensitivity. RESULTS: Exposure of each cell line to AZD6244 before irradiation resulted in an increase in radiosensitivity with dose enhancement factors at a surviving fraction of 0.1, ranging from 1.16 to 2.0. No effects of AZD6244 on radiation-induced apoptosis or persistence of gammaH2AX foci after irradiation were detected. Cells treated with AZD6244 had an increased mitotic index and decreased Chk1 phosphorylation at 1 and 2 hours after irradiation. Mitotic catastrophe was increased in cells receiving AZD6244 and irradiation compared with the single treatments. In vivo studies revealed that AZD6244 administration to mice bearing A549 tumor xenografts resulted in a greater than additive increase in radiation-induced tumor growth delay (dose enhancement factor of 3.38). CONCLUSIONS: These results indicate that AZD6244 can enhance tumor cell radiosensitivity in vitro and in vivo and suggest that this effect involves an increase in mitotic catastrophe.