Suppressive effect of sulindac on branch duct-intraductal papillary mucinous neoplasms

Implications of glutathione-S transferase P1 in MAPK signaling as a CRAF chaperone: In memory of Dr. Irving Listowsky

Glutathione-S transferase P1 (GSTP1) is one of the glutathione-S transferase isozymes that belong to a family of phase II metabolic isozymes. The unique feature of GSTP1 compared with other GST isozymes is its relatively high expression in malignant tissues. Thus, clinically, GSTP1 serves as a tumor marker and as a refractory factor against certain types of anticancer drugs through its primary function as a detoxifying enzyme. Additionally, recent studies have identified a chaperone activity of GSTP1 involved in the regulation the function of various intracellular proteins, including factors of the growth signaling pathway. In this review, we will first describe the function of GSTP1 and then extend the details onto its role in the mitogen-activated protein kinase signal pathway, referring to the results of our recent study that proposed a novel autocrine signal loop formed by the CRAF/GSTP1 complex in mutated KRAS and BRAF cancers. Finally, the possibilities of new therapeutic approaches for these cancers by targeting this complex will be discussed.

Chemoprevention of pancreatic cancer by inhibition of glutathione-S transferase P1

Pancreatic cancer is among the most refractory malignancies with poor prognosis. Thus, preventive approaches, in addition to the development of novel therapeutic strategies are essential for this type of cancer. KRAS mutations occur very early in the development of pancreatic cancers and could be targeted for its prevention, yet specific inhibitors for mutated KRAS are lacking. Accordingly, Glutathione-S Transferase p1 (GSTP1), which we recently found to be an autocrine stimulator of mutated KRAS signaling, is predicted to be an alternative target for chemoprevention of pancreatic cancer. In this study, chemopreventive effects of O-Hexadecyl-γ-glutamyl-S-benzyl-cysteinyl-D-phenyl glycine-Ethylester (HGBPE), which we previously synthesized to inhibit GSTP1 activity, was analyzed for its effect on the prevention of a rat pancreatic carcinogenesis model induced by 7,12-dimethyl-benzanthracene (DMBA). Rats administered with DMBA were grouped into five cohorts. In the treated group I, which was treated neither with HGBPE nor vehicle, sequential appearance of precancerous lesions, ductal complexes, and adenocarcinoma was confirmed as previously reported. We also confirmed in this group that mutations of KRAS and expression of GSTP1 simultaneously occurred in the ductal complex. To rats of groups II and IV, HGBPE was administered, and vehicle to those of group III and V. In groups of II and IV, the incidence of both ductal complex and adenocarcinoma were significantly lower than those in groups III and V. These data clearly suggest the efficacy of HGBP as a potential chemopreventive agent for pancreatic cancer.

Effect of low-dose aspirin use on pancreatic cancer development and morphological changes on imaging in IPMN: A long-term cohort study

Background

Aspirin use may reduce the incidence of pancreatic cancer (PC), but no data are available regarding its chemopreventive effects on intraductal papillary mucinous neoplasm (IPMN). We aimed to determine whether low-dose aspirin (LDA) reduces PC development and morphological changes on imaging in IPMN patients.

Methods

A cohort of 448 IPMN patients periodically followed up with imaging tests was analyzed. We used one-to-two propensity score matching to adjust for differences between an LDA group (n = 63) and a non-LDA group (n = 385). Outcomes included increasing cyst diameter, increasing main pancreatic duct (MPD) diameter, mural nodule (MN) appearance and PC development.

Results

After matching, 63 LDA and 126 non-LDA patients were selected. During follow-up (median, 5.5 years), no significant differences were found in increasing cyst diameter, MN appearance, or PC development. However, there were significantly fewer cases of increasing MPD diameter in the LDA group (4.8% vs. 12.7%; p = 0.02). After adjustment for age and sex, LDA still decreased the risk of increasing MPD diameter (hazard ratio, 0.17; p = 0.02).

Conclusion

Our results do not support a chemopreventive effect of LDA on PC development. However, LDA reduces further MPD dilation in IPMN patients.

Intraductal papillary mucinous neoplasm of the pancreas - epidemiology, risk factors, diagnosis, and management

Intraductal papillary mucinous neoplasm (IPMN) is one of the most common cystic neoplasms of the pancreas. It is a heterogeneous disease and can be divided into ductal types and morphological subtypes. The incidence of IPMN is increasing, likely due to the widespread use of cross-sectional imaging and a growing elderly population. IPMN poses an increasing demand on the health care system. Current guidelines provide indications for surgery and recommendations for surveillance, but management of IPMN is still challenging in routine clinical practice. In this article, we review current knowledge about IPMN and provide future directions for improving diagnosis and management.

Branch-type intraductal papillary mucinous neoplasms: an update

BACKGROUND/AIMS

Branch-type intraductal papillary mucinous neoplasms (BT-IPMNs) are a subset of non-inflammatory mucinous lesions of the pancreas. Selected BT-IPMNs can be managed conservatively by surveillance because of their lower malignant potential. This review aims to update the reader on advances in our knowledge of BT-IPMNs since the consensus guidelines published in 2006.

METHODS

A Pubmed search for BT-IPMNs was undertaken and relevant papers were reviewed.

RESULTS

Due to the relative scarcity of this condition, still little is known about the natural history, the best method of surveillance or the surgical and non-surgical options.

CONCLUSION

A national database of BT-IPMNs would enable a large enough cohort of patients to be followed up and valid conclusions drawn regarding the best method of treatment or surveillance. and IAP.

Phospho-sulindac (OXT-328) combined with difluoromethylornithine prevents colon cancer in mice

The nonsteroidal anti-inflammatory drug (NSAID) sulindac and the ornithine decarboxylase (ODC) antagonist difluoromethylornithine (DFMO), individually and together, are effective inhibitors of colon carcinogenesis. However, chronic use of sulindac is associated with significant side effects. We evaluated the chemopreventive efficacy of phospho-sulindac (P-S, OXT-328), an apparently safe derivative of sulindac, together with DFMO, in HT-29 human colon cancer xenografts. Nude mice were divided into four groups as follows: group 1 received vehicle (corn oil); group 2 received P-S (100 mg/kg/d) by oral gavage; group 3 received DFMO (2% in drinking water); and group 4 received P-S (100 mg/kg/d) by gavage plus DFMO (2% in drinking water; P-S/DFMO). Eighteen days after implantation, compared with controls, tumor volume was inhibited 65.9% by P-S, 52.9% by DFMO, and 70.9% by P-S/DFMO (P < 0.01 for all). P-S/DFMO reduced cell proliferation 27.1% and increased apoptosis 38.9% compared with controls (P < 0.05 for both). Compared with controls, P-S reduced the levels of thioredoxin-1 (Trx-1) and thioredoxin reductase (TrxR), whereas DFMO reduced polyamine content (putrescine and spermidine) and TrxR levels. Importantly, P-S/DFMO decreased putrescine and spermidine levels and the expression of Trx-1, TrxR, and cyclooxygenase (COX) 2. Of these molecular targets, TrxR most consistently correlated with tumor growth. Study results show that P-S/DFMO is an efficacious drug combination for colon cancer prevention and also show the safety of P-S, which may overcome the limiting side effects of conventional sulindac. P-S/DFMO has an intricate mechanism of action extending beyond polyamines and including the thioredoxin system, an emerging regulator of chemoprevention. P-S/DFMO merits further evaluation.