g(m3)-ganglioside and Colorectal-Neoplasms

Colorectal cancer (CRC) is an aggressive malignancy with very limited therapeutic approaches. Drug resistance develops as a frequent characteristic in many patients with CRC, which leads to a decrease in the therapeutic efficacy of anticancer agents. Our previous evidences showed that bound polyphenol from millet bran (BPIS) possesses the potential of inhibiting cancer cell proliferation, and its main anticancer components are ferulic acid (FA) and p-coumaric acid (p-CA). In the present study, we found that BPIS significantly increases the sensitivity of human drug-resistant CRC cell line to oxaliplatin (OXA), a commonly used chemotherapy drug against CRC. Mechanistically, we indicated that BPIS significantly impairs the expression of a gene encoding multidrug resistance protein 1 (MDR1), a well-known permeability glycoprotein (P-gp), by preventing ganglioside GM3 catabolism. Neuraminidase 3 (NEU3) is a key enzyme catalyzing the conversion of ganglioside GM3 to ceramide trihexosides (Gb3), whose expression is increased in drug-resistant HCT-116/L cells. BPIS treatment increased GM3 level, but reduced Gb3 and P-gp levels by inhibiting NEU3 expression, which subsequently boosted the chemotherapy sensitivity of drug-resistant HCT-116/L cells to OXA. These findings reveal that BPIS increases the chemo-sensitivity by remodeling NEU3-mediated ganglioside GM3 catabolism, and it may be applied as a novel drug for facilitating the effectiveness of chemotherapeutic agents in CRC.

Topics: Antineoplastic Agents; Cells, Cultured; Colorectal Neoplasms; G(M3) Ganglioside; Humans; Millets; Oxaliplatin; Polyphenols

The simple ganglioside GM3 has been shown to have anti-proliferative effects in several in vitro and in vivo cancer models. Although the exogenous ganglioside GM3 has an inhibitory effect on cancer cell proliferation, the exact mechanism by which it prevents cell proliferation remains unclear. Previous studies showed that MDM2 is an oncoprotein that controls tumorigenesis through both p53-dependent and p53-independent mechanisms, and tumor suppressor phosphatase and tensin homolog deleted on chromosome 10 (PTEN), a dual-specificity phosphatase that antagonizes phosphatidylinositol 3-kinase (PI-3K)/AKT signaling, is capable of blocking MDM2 nuclear translocation and destabilizing the MDM2 protein. Results from our current study show that GM3 treatment dramatically increases cyclin-dependent kinase (CDK) inhibitor (CKI) p21(WAF1) expression through the accumulation of p53 protein by the PTEN-mediated inhibition of the PI-3K/AKT/MDM2 survival signaling in HCT116 colon cancer cells. Moreover, the data herein clearly show that ganglioside GM3 induces p53-dependent transcriptional activity of p21(WAF1), as evidenced by the p21(WAF1) promoter-driven luciferase reporter plasmid (full-length p21(WAF1) promoter and a construct lacking the p53-binding sites). Additionally, ganglioside GM3 enhances expression of CKI p27(kip1) through the PTEN-mediated inhibition of the PI-3K/AKT signaling. Furthermore, the down-regulation of the cyclin E and CDK2 was clearly observed in GM3-treated HCT116 cells, but the down-regulation of cyclin D1 and CDK4 was not. On the contrary, suppression of PTEN levels by RNA interference restores the enhanced expression of p53-dependent p21(WAF1) and p53-independent p27(kip1) through inactivating the effect of PTEN on PI-3K/AKT signaling modulated by ganglioside GM3. These results suggest that ganglioside GM3-stimulated PTEN expression modulates cell cycle regulatory proteins, thus inhibiting cell growth. We conclude that ganglioside GM3 represents a modulator of cancer cell proliferation and may have potential for use in colorectal cancer therapy.

Topics: Antineoplastic Agents; Cell Cycle; Cell Line, Tumor; Cell Membrane; Cell Proliferation; Colorectal Neoplasms; Cyclin-Dependent Kinase Inhibitor p21; Cyclin-Dependent Kinase Inhibitor p27; Down-Regulation; G(M3) Ganglioside; Humans; Intracellular Signaling Peptides and Proteins; Phosphoinositide-3 Kinase Inhibitors; Proto-Oncogene Proteins c-akt; PTEN Phosphohydrolase; RNA Interference; RNA, Small Interfering; Transcription, Genetic; Tumor Suppressor Protein p53

Various tumor-associated antigens have been identified as carbohydrates bound to lipids or to proteins expressed on tumor cell membranes. We prepared tumor-specific immunoliposomes by coupling anticarbohydrate antibodies, such as antiganglioside G(M3) antibody (DH2) or anti-Le(x) antibody (SH1), to polyethylene glycol (PEG)-coated liposomes. In vitro and in vivo targetability of anti-G(M3) and anti-Le(x) immunoliposomes to B16BL6 mouse melanoma cells and HRT-18 human colorectal adenocarcinoma cells were monitored with a fluorescence microscopy, and analyzed by biodistribution assay of the immunoliposome in mice bearing the tumor tissues. The antibody coupling to the PEG liposomes did not greatly diminish the circulation time of the liposome in the C57BL/6 mouse model. In vitro cytotoxicity of doxorubicin encapsulated in liposomes was enhanced by antibody coupling, but still behind free doxorubicin. However, in vivo antitumor therapeutic efficacy of doxorubicin encapsulated in the immunoliposomes was far greater than the free drug or in conventional liposomes. Doxorubicin encapsulated in anti-G(M3) immunoliposomes was able to reduce in vivo tumor growth and metastasis of B16BL6 mouse melanoma cells more greatly than any other formulations of the drug. This study suggests that tumor-associated antigens can be good target molecules for tumor-specific delivery of liposomal drugs or other synthetic drug delivery systems.

Topics: Animals; Antibodies, Monoclonal; Antigens, Neoplasm; Antineoplastic Agents; Colorectal Neoplasms; Doxorubicin; Drug Carriers; G(M3) Ganglioside; Humans; Immunotoxins; Lewis X Antigen; Liposomes; Melanoma, Experimental; Mice; Tumor Cells, Cultured