Chemotherapy for advanced pancreatic cancer: Past, present, and future

Carrier-free Janus nano-prodrug based on camptothecin and gemcitabine: Reduction-triggered drug release and synergistic in vitro antiproliferative effect in multiple cancer cells

A carrier-free and reduction-degradable Janus prodrug, termed as CPT-SS-GEM, was fabricated by redox-sensitive disulfide bond linked gemcitabine and camptothecin. This amphiphilic prodrug showed high drug loading capacity, 42.6% of CPT and 32.2% of GEM, respectively. Benefiting from its amphiphilic property, CPT-SS-GEM prodrug could self-assemble into Janus nano-prodrug in water without aid of any excipient. The morphology of the nano-prodrug was spherical particle confirmed by TEM. The rapid drug release from the nano-prodrug proceeded in a reduction-dependent manner, more than 90% of the native CPT and GEM were released in the mimic microenvironment of tumor cells (pH 6.5 PBS containing 2 mM DTT) within a period of 3 h. The concurrent and ratio-metric release of CPT and GEM endowed the Janus nano-prodrug CPT-SS-GEM with pronounced in vitro synergistic antiproliferative effect in multiple cancer cell lines when the inhibition rate of cancer cell proliferation exceeded 50%, including A549, NCI-H460, HCT116, HT-29, and MCF-7/ADR. The combination index values showed as followings, 1.04-0.4 (A549), 0.24-0.60 (NCI-H460), 0.42-0.16 (HCT116), 1.98-0.15 (HT-29), 0.36-0.19 (MCF-7/ADR). Taken together, the carrier-free, redox-sensitive Janus nano-prodrug CPT-SS-GEM is a promising candidate as synergistic combination of chemotherapeutics.

Biotin conjugated organic molecules and proteins for cancer therapy: A review

The main transporter for biotin is sodium dependent multivitamin transporter (SMVT), which is overexpressed in various aggressive cancer cell lines such as ovarian (OV 2008, ID8), leukemia (L1210FR), mastocytoma (P815), colon (Colo-26), breast (4T1, JC, MMT06056), renal (RENCA, RD0995), and lung (M109) cancer cell lines. Furthermore, its overexpression was found higher to that of folate receptor. Therefore, biotin demand in the rapidly growing tumors is higher than normal tissues. Several biotin conjugated organic molecules has been reported here for selective delivery of the drug in cancer cell. Biotin conjugated molecules are showing higher fold of cytotoxicity in biotin positive cancer cell lines than the normal cell. Nanoparticles and polymer surface modified drugs and biotin mediated cancer theranostic strategy was highlighted in this review. The cytotoxicity and selectivity of the drug in cancer cells has enhanced after biotin conjugation.

Autophagy Induced by CX-4945, a Casein Kinase 2 Inhibitor, Enhances Apoptosis in Pancreatic Cancer Cell Lines

OBJECTIVES

Pancreatic cancer is the most lethal malignancy with only a few effective chemotherapeutic drugs. Because the inhibition of casein kinase 2 (CK2) has been reported as a novel therapeutic strategy for many cancers, we investigated the effects of CK2 inhibitors in pancreatic cancer cell lines.

METHODS

The BxPC3, 8902, MIA PaCa-2 human pancreatic cancer cell lines, and CX-4945, a novel CK2 inhibitor, were used. Autophagy was analyzed by acridine orange staining, fluorescence microscope detection of punctuate patterns of GFP-tagged LC3 and immunoblotting for LC3. Cell survival, cell cycle, and apoptosis analysis was performed.

RESULTS

CX-4945 induced significant inhibition of proliferation and triggered autophagy in pancreatic cancer cells. This suppression of proliferation was caused by the direct inhibition of CK2α, which was required for autophagy and apoptosis in pancreatic cancer cells. CX-4945 suppressed cell cycle progression in G2/M and induced apoptosis. The inhibition of CX-4945-induced autophagy was rescued by 3-methyladenine or small interfering RNA against Atg7, which attenuated apoptosis in pancreatic cancer cells.

CONCLUSIONS

CX-4945, a potent and selective inhibitor of CK2, effectively induces autophagy and apoptosis in pancreatic cancer cells, indicating that the induction of autophagy by CX-4945 may have an important role in the treatment of pancreatic cancer.

Modular polymer-caged nanobins as a theranostic platform with enhanced magnetic resonance relaxivity and pH-responsive drug release

‘Clickable’ polymer-caged nanobins enable the combination of GdIII MRI contrast agents and an anticancer drug (gemcitabine, GMC) into a single theranostic platform. The resulting GdIII-conjugated, GMC-loaded PCNs (GdIII-PCNGMC) exhibit significant enhancements in r 1 relaxivity, drug uptake, and pH-sensitive drug release.

A review of kinases implicated in pancreatic cancer

The current 5-year survival rate of pancreatic cancer is about 3% and the median survival less than 6 months because the chemotherapy and radiation therapy presently available provide only marginal benefit. Clearly, pancreatic cancer requires new therapeutic concepts. Recently, the kinase inhibitors imatinib and gefitinib, developed to treat chronic myelogenous leukaemia and breast cancer, respectively, gave very good results. Kinases are deregulated in many diseases, including cancer. Given that phosphorylation controls cell survival signalling, strategies targeting kinases should obviously improve cancer treatment. The purpose of this review is to summarize the present knowledge on kinases potentially usable as therapeutic targets in the treatment of pancreatic cancer. All clinical trials using available kinase inhibitors in monotherapy or in combination with chemotherapeutic drugs failed to improve survival of patients with pancreatic cancer. To detect kinases relevant to this disease, we undertook a systematic screening of the human kinome to define a 'survival kinase' catalogue for pancreatic cells. We selected 56 kinases that are potential therapeutic targets in pancreatic cancer. Preclinical studies using combined inhibition of PAK7, MAP3K7 and CK2 survival kinases in vitro and in vivo showed a cumulative effect on apoptosis induction. We also observed that these three kinases are rather specific of pancreatic cancer cells. In conclusion, if kinase inhibitors presently available are unfortunately not efficient for treating pancreatic cancer, recent data suggest that inhibitors of other kinases, involved more specifically in pancreatic cancer development, might, in the future, become interesting therapeutic targets.

Combined inhibition of PAK7, MAP3K7 and CK2alpha kinases inhibits the growth of MiaPaCa2 pancreatic cancer cell xenografts

A panel of kinases whose inhibition increased apoptosis of pancreatic adenocarcinoma cells in vitro was recently established. The aim of this work was to observe in a mouse xenograft model whether inhibition of these kinases would alter pancreatic tumor growth. Rate of apoptosis, caspase-3 activity and cell viability were assessed in two pancreatic cancer cell lines, MiaPaCa2 and BxPC3, after inhibiting selected kinases by transfection of specific siRNAs. For in vivo experiments, MiaPaCa2 cells were injected into the pancreas of nude mice, where they formed tumors. Inhibition of kinases was obtained by repeated intraperitoneal (i.p.) injections of modified O-Methyl (OMe) siRNAs specific for the selected kinases. Tumor volumes were assessed after 21 days. Among selected kinases, PAK7, MAP3K7 and CK2alpha were those whose inhibition increased apoptosis the most in vitro. Simultaneous inhibition of two of them increased apoptosis up to five times. Moreover, inhibiting these kinases had little effect on 10 non-pancreatic cell lines, suggesting pancreatic specificity. In vivo, OMe-siRNAs induced significant but incomplete inhibition of kinase expression (45-75%). Nevertheless, such inhibition resulted in a twofold increase in caspase-3 activity in tumors and a strong reduction in tumor volume (about 75%). In vivo inhibition by OMe-siRNAs of three survival kinases apparently specific for pancreatic cancer cells, PAK7, MAP3K7 and CK2alpha, decreases significantly the growth of xenografted MiaPaCa2 cells. This strategy is therefore of potential clinical interest.

Pancreatic cancer: an update

Pancreatic cancer is refractory to most chemotherapy. For many years, the only active agent for this disease was gemcitabine, which has very modest activity. Two new regimens, gemcitabine plus erlotinib and gemcitabine plus capecitabine, have recently demonstrated statistically significant survival improvements compared with single-agent gemcitabine. Several key negative studies have also been reported recently. This review discusses recent trials that have changed the standard of care for patients with advanced pancreatic cancer.

The role of nucleoside transporters in cancer chemotherapy with nucleoside drugs

Nucleoside analogs are important components of treatment regimens for various malignancies. Nucleoside-specific membrane transporters mediate plasma membrane permeation of physiologic nucleosides and most nucleoside analogs, for which the initial event is cellular conversion of nucleosides to active agents. Understanding of the roles of nucleoside transporters in nucleoside drug toxicity and resistance will provide opportunities for potentiating anticancer efficacy and avoiding resistance. Because transportability is a possible determinant of toxicity and resistance of many nucleoside analogs, nucleoside transporter abundance might be a prognostic marker to assess drug resistance. Elucidation of the structural determinants of nucleoside analogs for interaction with transporter proteins as well as the structural features of transporter proteins required for permeant interaction and translocation will lead to "transportability guidelines" for the rational design and therapeutic application of nucleoside analogs as anticancer drugs. It should eventually be possible to develop clinical assays that predict sensitivity and/or resistance to nucleoside anti-cancer drugs and thus to identify those patient populations that will most likely benefit from optimal nucleoside analog treatments. This review discusses recent results from structure/function studies of human nucleoside transporters, the role of nucleoside transport processes in the cytotoxicity and resistance of several anticancer nucleoside analogs and strategies to improve the nucleoside transporter-related anticancer effects of nucleoside analogs.

Phase II study of gemcitabine in children with solid tumors of mesenchymal and embryonic origin

The therapeutic benefit and side-effect profile of gemcitabine in adults with relapsed solid tumors is well known. So far, few data are available about its significance in pediatric relapsed solid tumors. To determine the efficacy and tolerability of gemcitabine in children, the drug was administered by intravenous short-term infusion over 30 min at a dose of 1200 mg/m2 weekly for 3 weeks as one cycle in children with relapsed solid tumor of embryonic or mesenchymal origin. From May 2003 to September 2004, 14 male and six female patients (2-23, median 15.8 years) were recruited for this prospective open-label phase II study (two-step Simon design). The patients suffered from rhabdomyosarcoma (n=8), Ewing's sarcoma (n=4), osteosarcoma (n=2), neuroblastoma (n=3), hepatoblastoma (n=2) and nephroblastoma (n=1). Median duration of therapy was 27.5 days (7-99), corresponding to 4.0 (2-11) infusions of gemcitabine. Two patients (neuroblastoma and Ewing) had stable disease documented for 69 and 70 days, whereas no objective responses were observed. In 34/94 administered infusions; doses had to be reduced or omitted for grade 3-4 hematotoxicity. Minimal activity was observed in this cohort of children with a wide spectrum of mesenchymal and embryonic tumors. Given the relatively low dose of gemcitabine administered, this study does not exclude the possibility of activity at higher doses. Secondly, the tolerability of gemcitabine in children was consistent with that expected in adults. For further studies in this population, we recommend the use of gemcitabine in combination with other agents.

Techniques and results of neurolysis for chronic pancreatitis and pancreatic cancer pain

Chronic abdominal pain can be associated with benign and malignant disease. Pain associated with pancreatic cancer and chronic pancreatitis can be severely debilitating, with significant impairment in quality of life. Frequently, chronic abdominal pain is not adequately responsive to conventional medical therapies, including nonsteroidal anti-inflammatory drugs and opioids. For this reason, alternative methods to alleviate pain have been developed. Celiac plexus neurolysis and celiac block involve injecting an agent at the celiac axis, with the goal of either selectively destroying the celiac plexus or temporarily blocking visceral afferent nociceptors to alleviate chronic abdominal pain. Agents most commonly used for this purpose include alcohol or phenol for neurolysis and bupivacaine and triamcinolone for temporary block. Methods to administer such agents to the celiac ganglion include CT imaging, percutaneous ultrasound, fluoroscopy, endoscopic ultrasound, or surgery (ganglionectomy). Response rates and complications vary depending on technique but are relatively low. This review highlights the techniques of celiac plexus neurolysis and celiac block and their status in the treatment of chronic pancreatitis and pancreatic cancer pain.

Probing the human kinome for kinases involved in pancreatic cancer cell survival and gemcitabine resistance

Except for gemcitabine, chemotherapeutic agents are ineffective with pancreatic adenocarcinoma because this cancer is resistant to apoptosis induction. Involvement of specific kinases in such resistance is likely. We developed a systematic strategy to screen the human kinome and select kinases whose inhibition in pancreatic cancer cells can increase 1) spontaneous apoptosis or 2) gemcitabine-induced apoptosis. The pancreatic adenocarcinoma cell line MiaPaCa-2 was transfected with 645 pairs of siRNAs directed to all human kinases. The same experiment was conducted in cells treated with 150 microM gemcitabine. Apoptosis was measured after 2 days and the results were normalized for cell viability. A panel of 56 kinases whose inhibition increased spontaneous apoptosis by at least 50% was established. Ten of them gave similar results on Panc1 and BxPC3 pancreatic adenocarcinoma cell lines. A panel of 83 kinases whose inhibition increased gemcitabine-induced apoptosis by 50% or more was also established. Twelve kinases appeared in both panels. A cumulative increase in apoptosis was observed when inhibiting simultaneously several kinases. Such a systematic approach allowed characterization of all kinases involved in pancreatic cancer cell survival and resistance to gemcitabine. Inhibitors of these kinases, used alone or in combination, might improve the treatment of pancreatic adenocarcinoma.

Update on pancreatic cancer and alcohol-associated risk

Ductal adenocarcinoma of the pancreas is characterized by extremely aggressive behavior, with an overall 5-year survival of <4%. Because conventional and specifically tailored therapeutic regimens have little impact on patient survival, epidemiological and molecular research aims at identifying and reducing risk factors. Cigarette smoking, obesity, diabetes mellitus, and chronic pancreatitis are amenable to medical prevention or therapy. Heavy alcohol consumption is an inconsistent single risk factor for pancreatic cancer but may promote carcinogenesis by increasing the risk of diabetes mellitus or chronic pancreatitis. For various agents, the key carcinogenic effect is probably an inflammatory response in the pancreatic tissue. On the molecular level, mutations of oncogenes and tumor suppressor genes, as well as various epigenetic alterations, such as overexpression of growth factors and their receptors, are important in tumorigenesis. Complete and safe surgical resection, together with adjuvant therapy, offers prolonged survival, with 5-year survival rates of approximately 25%. However, for unresectable or disseminated disease, which constitutes the vast majority of cases, treatment is palliative. Despite increasing knowledge about the molecular pathology of pancreatic cancer and despite advances in treatment, the overall course of the disease is dismal, and reinforced efforts to reduce incidence and improve outcome are needed desperately.