p53-armed oncolytic adenovirus induces autophagy and apoptosis in KRAS and BRAF-mutant colorectal cancer cells.

Colorectal cancer (CRC) cells harboring KRAS or BRAF mutations show a more-malignant phenotype than cells with wild-type KRAS and BRAF. KRAS/BRAF-wild-type CRCs are sensitive to epidermal growth factor receptor (EGFR)-targeting agents, whereas KRAS/BRAF-mutant CRCs are resistant due to constitutive activation of the EGFR-downstream KRAS/BRAF signaling pathway. Novel therapeutic strategies to treat KRAS/BRAF mutant CRC cells are thus needed. We recently demonstrated that the telomerase-specific replication-competent oncolytic adenoviruses OBP-301 and p53-armed OBP-702 exhibit therapeutic potential against KRAS-mutant human pancreatic cancer cells. In this study, we evaluated the therapeutic potential of OBP-301 and OBP-702 against human CRC cells with differing KRAS/BRAF status. Human CRC cells with wild-type KRAS/BRAF (SW48, Colo320DM, CACO-2), mutant KRAS (DLD-1, SW620, HCT116), and mutant BRAF (RKO, HT29, COLO205) were used in this study. The antitumor effect of OBP-301 and OBP-702 against CRC cells was analyzed using the XTT assay. Virus-mediated modulation of apoptosis, autophagy, and the EGFR-MEK-ERK and AKT-mTOR signaling pathways was analyzed by Western blotting. Wild-type and KRAS-mutant CRC cells were sensitive to OBP-301 and OBP-702, whereas BRAF-mutant CRC cells were sensitive to OBP-702 but resistant to OBP-301. Western blot analysis demonstrated that OBP-301 induced autophagy and that OBP-702 induced autophagy and apoptosis in human CRC cells. In BRAF-mutant CRC cells, OBP-301 and OBP-702 suppressed the expression of EGFR, MEK, ERK, and AKT proteins, whereas mTOR expression was suppressed only by OBP-702. Our results suggest that p53-armed oncolytic virotherapy is a viable therapeutic option for treating KRAS/BRAF-mutant CRC cells via induction of autophagy and apoptosis.

[A Case of Pathological Complete Response Induced by Preoperative Gemcitabine plus S-1 with Concurrent Radiation Therapy Followed by Gemcitabine plus S-1 Therapy in Borderline Resectable Pancreatic Cancer].

The patient was a 69-year-old man. He visited our hospital with a complaint of right back pain. An abdominal CT scan confirmed a hypovascular mass 35 mm in diameter in the pancreatic head. He was diagnosed with pancreatic head cancer (cT3, cN0, cM0, cStage ⅡA, borderline resectable-A). Gemcitabine plus S-1(GS)-based chemoradiation therapy(CRT) was performed, followed by 6 courses of GS therapy. Tumor markers were almost normalized, and subtotal stomach-preserving pancreaticoduodenectomy was performed. Histopathological examination of the resected specimen revealed highly atrophic pancreatic tissue with fibrosis and no evidence of residual cancer cells (pathological complete response). The patient remains disease-free 36 months after surgery. There are few reports of pancreatic cancer with pCR after GS-based chemoradiation therapy and subsequent GS therapy. We therefore report this case together with a review of the literature.

[A Case of a Huge, Mixed-Type IPMC with Suspected Rupture of the Omental Bursa That Was Effectively Treated with Gemcitabine plus Nab-Paclitaxel].

A 53-year-old woman was referred to our hospital because of upper abdominal pain and expansion of the pancreatic main duct. Enhanced computed tomography revealed expansion of the main pancreatic duct from the head to the tail; in addition, a 30 mm cystic tumor was observed in the pancreatic head and a 56 mm tumor was observed in the ventral side of the pancreatic body. Endoscopy revealed fistula formation in the duodenum of the Vater papilla on the oral side. The patient was diagnosed with an intraductal papillary mucinous carcinoma(IPMC). In addition, PET-CT revealed accumulation of FDG in the ventral side of the pancreatic body, and a disseminated nodule in the omental bursa was suspected. We administered 6 courses of gemcitabine plus nab-paclitaxel therapy, after which, the tumor in the ventral side of the pancreatic body disappeared. We then performed sub-stomach-preserving pancreatoduodenectomy. The results of abdominal cavity washing cytology were negative, and there were no disseminated nodules in the omental bursa. Therefore, we could perform R0 excision.

Enhanced accumulation of tau in doubly transgenic mice expressing mutant betaAPP and presenilin-1.

Abeta amyloidosis and tauopathy are characteristic changes in the brain of Alzheimer's disease. Although much evidence suggests that Abeta deposit is a critical initiation factor, the pathological pathway between Abeta amyloidosis and tau accumulation remains unclear. Tau accumulation was examined in the doubly transgenic mouse (APP-PS) expressing betaAPP(KM670/671NL) (Tg2576) and presenilin-1 L286V (PS-1 L286Vtg). Accelerated and enhanced Abeta amyloid deposits were detected from 8 weeks. Tau accumulation appeared at 4.5 months and markedly increased in dystrophic neurites around Abeta amyloid. Accumulated tau was phosphorylated, conformationally altered, and argyrophilic. Expression of tau and accumulation of sarkosyl-insoluble phosphorylated tau were increased in APP-PS brains compared with those of Tg2576 mice. Straight or twisted tubules mimicking paired helical filament were revealed at electron microscopic level in 16-month-old APP-PS. These findings suggest that mutant presenilin-1 accelerated Abeta-induced tauopathy and further promoted fibril formation of tau.