Marked antitumor effect of NK012, a SN-38-incorporating micelle formulation, in a newly developed mouse model of liver metastasis resulting from gastric cancer

Multifunctional approaches utilizing polymeric micelles to circumvent multidrug resistant tumors

The concerns impeding the success of chemotherapy in cancer is descending efficacy of drugs due to the development of multiple drug resistance (MDR). The current efforts employed to overcome MDR have failed or are limited to only preliminary in-vitro investigations. Nanotechnology is at the forefront of the drug delivery research, playing pivotal role in chemotherapy and diagnosis, thereby providing innovative approaches for the management of the disease with minimal side effects. Recently, polymeric micelles (PMs) have witnessed significant developments in cancer therapy. PMs are self-assembled colloidal particles, with a hydrophilic head and a long hydrophobic tail, which enhance the solubility, permeability and bioavailability of drugs, due to the unique features of reaching higher concentration in the biological system, above critical micellar concentration. One of the effective approaches to improve the efficacy of chemotherapy and overcome drug resistance would be to employ multifunctional approach (combination of stimuli-responsive, utilization of drug resistance modulators and combination therapy) using PMs as drug delivery systems. Actively targeted, stimuli-sensitive and multifunctional approaches involve using single and/or combination of approaches (pH-responsive, temperature regulated, reduction-sensitive, ultrasound etc.) to combat drug resistant. The review will describe PMs, types of copolymers used in PMs, preparation and characterization of PMs. A comprehensive list of PMs tested in clinical trials is discussed. Lastly, this review covers stimuli-sensitive and multifunctional approaches to overcome MDR in cancer utilizing PMs.

MACC1 and HGF are associated with survival in patients with gastric cancer

Metastasis-associsated in colon cancer 1 (MACC1), a newly identified oncogene, promotes tumor cell proliferation and invasion. In the present study, the expression of MACC1, hepatocyte growth factor (HGF) and its receptor, MET proto-oncogene (c-Met), was investigated in human gastric cancer tissues and adjacent normal tissues by immunohistochemistry. The association between the expression levels of the proteins and the clinicopathological parameters of the tumors were statistically analyzed. Furthermore, lentiviral particles expressing MACC1 were used to infect the hepatic satellite cell (HSC) line LX2. The expression of α-smooth muscle actin (SMA), HGF, matrix metallopeptidase (MMP)-2 and MMP-9 in human HSCs was examined by western blotting and reverse transcription-quantitative polymerase chain reaction. Transwell assays were used to measure the effect of MACC1-infected or non-infected HSCs on the migration and invasion abilities of MKN45 and MKN74 gastric carcinoma cells in vitro. The results demonstrated that positive protein expression of MACC1, HGF and c-Met was significantly higher in human gastric cancer tissues compared with adjacent normal tissues. Positive expression of MACC1 and c-Met in gastric cancer tissues had no correlation with the sex, age, tumor location and peritoneal metastasis of patients, but was significantly correlated with tumor size, depth of tumor invasion, lymph node metastasis, TNM stage, histological differentiation, and overall (5 years) and disease-free survival (5 years). Positive expression of each MACC1, HGF and c-Met protein was demonstrated to be positively correlated with each other in human gastric cancer tissues. Western blotting results confirmed that MACC1 protein was overexpressed in MACC1-overexpressing lentivirus-infected HSCs. Overexpression of MACC1 significantly increased HGF, MMP-2, MMP-9 and α-SMA expression levels in HSCs. Results from the Transwell assays indicated an increase in the number of MKN45 or MKN74 cells migrating towards MACC1-overexpressing HSCs, compared with control HSCs. These findings suggested that MACC1 may regulate the expression of HGF, MMP-2 and MMP-9 in HSCs, and may thus promote migration and invasion of gastric carcinoma cells. MACC1, HGF and c-Met might cooperatively participate in the malignant progression of gastric cancer. In conclusion, MACC1 might serve as a useful molecular target for the diagnosis, treatment and prognosis of gastric cancer.

Bioresponsive polymer coated drug nanorods for breast cancer treatment

Ineffective drug release at the target site is among the top challenges for cancer treatment. This reflects the facts that interaction with the physiological condition can denature active ingredients of drugs, and low delivery to the disease microenvironment leads to poor therapeutic outcomes. We hypothesize that depositing a thin layer of bioresponsive polymer on the surface of drug nanoparticles would not only protect drugs from degradation but also allow the release of drugs at the target site. Here, we report a one-step process to prepare bioresponsive polymer coated drug nanorods (NRs) from liquid precursors using the solvent diffusion method. A thin layer (10.3 ± 1.4 nm) of poly(ε-caprolactone) (PCL) polymer coating was deposited on the surface of camptothecin (CPT) anti-cancer drug NRs. The mean size of PCL-coated CPT NRs was 500.9 ± 91.3 nm length × 122.7 ± 10.1 nm width. The PCL polymer coating was biodegradable at acidic pH 6 as determined by Fourier transform infrared spectroscopy. CPT drugs were released up to 51.5% when PCL coating dissolved into non-toxic carboxyl and hydroxyl groups. Trastuzumab (TTZ), a humanized IgG monoclonal antibody, was conjugated to the NR surface for breast cancer cell targeting. Combination treatments using CPT and TTZ decreased the HER-2 positive BT-474 breast cancer cell growth by 66.9 ± 5.3% in vitro. These results suggest effective combination treatments of breast cancer cells using bioresponsive polymer coated drug delivery.

Structural modifications in polymeric micelles to impart multifunctionality for improved drug delivery

Polymeric micelles are macromolecular nanoconstructs which are formed by self-assembly of synthetic amphiphilic block copolymers. These copolymers could be chemically modified to expand their functionality and hence obtain a multifunctional micelle which could serve several functions simultaneously, for example, long circulation time along with active targeting, smart polymeric micelles providing on-demand drug release for example, pH responsive micelles, redox- and light-sensitive micelles, charge-conversion micelles and core/shell cross-linked micelles. Additionally, micelles could be tailored to carry a contrast agent or siRNA/miRNA along with the drug for greater clinical benefit. The focus of the current commentary would be to highlight such chemical modifications which impart multifunctionality to a single carrier and discuss challenges involved in clinical translation of these multifunctional micelles.

Synthesis, characterization and targeting chemotherapy for ovarian cancer of trastuzumab-SN-38 conjugates

Antibody-drug conjugates (ADCs), combining monoclonal antibody with high cytotoxicity chemotherapeutic drug (warhead), have been successfully applied for clinical cancer therapy. Linker technology to select and design linker connecting warhead with antibody, is critical to the success of therapeutic ADCs. In this study, three kinds of linkers were designed to connect SN-38, the bioactive metabolite of the anticancer drug irinotecan (CPT-11), which is 100-1000 times more potent than CPT-11, with the anti-HER2 antibody trastuzumab to prepare three different ADC conjugates (T-SN38 A, B and C). Meanwhile, we compared the anti-ovarian cancer effect of these three T-SN38 conjugates with trastuzumab in vitro and in vivo. Our in vitro results showed that T-SN38 A, B and C (drug-to-antibody ratio, DAR=3.7, 3.2, 3.4) were 2 to 3 times as cytotoxic as SN-38, and the IC50 for these three conjugates on SKOV-3 cell line at 72 h were 5.2 ± 0.3, 4.4 ± 0.7, and 5.1 ± 0.4 nM respectively. In our in vivo studies, T-SN38 conjugates had well targeting ability for tumor tissue and all three of them had much higher anti-ovarian cancer potency than trastuzumab. Among of them, T-SN38 B, which coupled SN-38 with trastuzumab by a carbonate bond, has the best anti-ovarian cancer potency. In conclusion, the novel HER2-targeting ADCs T-SN38 have great potential for HER2-positive ovarian cancer. Moreover, the SN-38-Linkers designed in this study can also be used to connect with other antibodies for the therapy of other cancers.