[In vivo siRNA delivery to tumor cells and its application to cancer gene therapy]

Effect of siRNA-mediated down-regulation of receptor for advanced glycation end products on expression of matrix metalloproteinase-1 and tissue inhibitor of metalloproteinase-1 in rat hepatic stellate cells and hepatic fibrosis

AIM: To investigate the effect of small interfering RNA (siRNA)-mediated down-regulation of receptor for advanced glycation end products (RAGE) on the expression of matrix metalloproteinase-1 (MMP-1) and tissue inhibitor of metalloproteinase-1 (TIMP-1) in primary rat hepatic stellate cells (HSCs) and hepatic fibrosis (HF).

METHODS: In in vitro experiment, primary rat HSCs were cultured and isolated. The pAKD-GR126 vector carrying siRNA targeting RAGE was constructed and transfected to primary rat HSCs. Blank cells and cells transfected with unspecific siRNA vector pAKD-NC were used as controls. In in vivo experiment, liver fibrosis was induced in SD rats with CCl₄. pAKD-GR126 was transfected to liver fibrosis rats at different doses via the tail vein. A blank group, a liver fibrosis model group and an unspecific siRNA vector pAKD-NC-transfected group were used as controls. Real-time PCR and Western blot were used to detect the expression of RAGE, MMP-1 and TIMP-1. The histological changes of the liver were observed by HE and Masson staining methods.

RESULTS: The mRNA and protein expression of RAGE and TIMP-1 in pAKD-GR126-transfected primary HSCs was significantly lower than that in the blank group and unspecific siRNA vector pAKD-NC-transfected group (P < 0.05 for all). However, the level of MMP-1 in pAKD-GR126-transfected primary HSCs was significantly higher than that in the blank group and pAKD-NC-transfected group (P < 0.05 for all). In vivo, the mRNA and protein expression of RAGE and TIMP-1 was significantly lower and that of MMP-1 was significantly higher in the low-, medium-, and high-dose RAGE siRNA groups than in the liver fibrosis model group (P < 0.05 for all). Compared with the liver fibrosis model group, liver fibrosis was significantly milder in the low-, medium-, and high-dose RAGE siRNA groups, especially the high-dose group.

CONCLUSION: RAGE specific siRNA could decrease the expression of RAGE and TIMP-1, increase the expression of MMP-1 in primary rat HSCs and HF rats, and reduce the degree of rat hepatic fibrosis.

Prospective of colon cancer treatments and scope for combinatorial approach to enhanced cancer cell apoptosis

Colorectal cancer is the leading cause of cancer-related mortality in the western world. It is also the third most common cancer diagnosed in both men and women in the United States with a recent estimate for new cases of colorectal cancer in the year 2012 being around 103,170. Various risk factors for colorectal cancer include life-style, diet, age, personal and family history, and racial and ethnic background. While a few cancers are certainly preventable but this does not hold true for colon cancer as it is often detected in its advanced stage and generally not diagnosed until symptoms become apparent. Despite the fact that several options are available for treating this cancer through surgery, chemotherapy, radiation therapy, immunotherapy, and nutritional-supplement therapy, but the success rates are not very encouraging when used alone where secondary complications appear in almost all these therapies. To maximize the therapeutic-effects in patients, combinatorial approaches are essential. In this review we have discussed the therapies previously and currently available to patients diagnosed with colorectal-cancer, focus on some recent developments in basic research that has shaded lights on new therapeutic-concepts utilizing macrophages/dendritic cells, natural killer cells, gene delivery, siRNA-, and microRNA-technology, and specific-targeting of tyrosine kinases that are either mutated or over-expressed in the cancerous cell to treat these cancer. Potential strategies are discussed where these concepts could be applied to the existing therapies under a comprehensive approach to enhance the therapeutic effects.

Further evaluation of a novel nano-scale gene vector for in vivo transfection of siRNA

In this research, a lipid-cationic polymer (LCP) containing the side-chain branching of brassidic acid was synthesized using chemical methods. As a gene vector for small interfering ribonucleic acid (siRNA) transfection, the efficiency and biosafety of LCP were preliminarily evaluated to investigate its possible application on tumor gene therapy. The toxicity, side-effects, and biosafety of LCP were investigated in animals based on the results of in vitro experiments. The siRNA against cyclooxygenase-2 (COX-2) was transfected by LCP to interfere with the COX-2 expression in nude-transplanted tumors. Hematoxylin and eosin stains, immunohistochemistry, reverse transcription-polymerase chain reaction, and Western blot were performed to evaluate the efficiency of LCP for siRNA transfection. The animal toxicity experiment showed that a high concentration of LCP had a low toxic effect on animals and did not induce allergic or pyrogenic reactions. The results from the in vivo transfection indicated that LCP could efficiently transfect siRNA and silence the target gene expression. The LCP gene vector for siRNA transfection is highly efficient during in vivo transfection and had low toxicity. From all aspects of tumor gene therapy and basic research, LCP is valuable for scientific research and medical applications.

Knockdown of focal adhesion kinase reverses colon carcinoma multicellular resistance

Chemotherapy resistance in solid tumors is broad and encompasses diverse unrelated drugs. Three-dimensional multicellular spheroids (MCSs) are a good model for studying in vitro drug resistance. In the current study, we investigated the role of focal adhesion kinase (FAK) in 5-fluorouracil (5-FU) chemoresistance in colon carcinoma MCS culture cells. The expression of FAK was inhibited significantly by specific small hairpin RNA targeting FAK. The suppression of FAK expression did not affect the growth of spheroid cells. However, silencing of FAK combined with 5-FU treatment significantly decreased the 50% inhibitory concentration (IC(50)) of 5-FU and markedly increased the population of apoptosis cells, which was associated with the reduction of the levels of Akt and nuclear factor-kappa B (NF-kappaB). Moreover, knockdown of FAK could inhibit tumor growth and increase the sensitivity of the tumor to 5-FU in the nude mouse xenograft. These results indicate that while not affecting cellular proliferation in the absence of 5-FU, RNA interference targeting FAK potentiated 5-FU-induced cytotoxicity in vitro and in vivo, and partially reversed multicellular resistance, which may contribute to its chemosensitizing effect through efficiently suppressing Akt/NF-kappaB activity.

Gene therapy for hepatic fibrosis

Hepatic fibrosis is a common pathological process of chronic liver diseases, characterized by increased synthesis and relatively low degradation of extracellular matrix (ECM) resulting from their dynamic imbalance. Recent progress in molecular biology techniques has made it possible to treat hepatic fibrosis with gene therapy. At present, the commonly used method is to induce the expression of exogenous genes by transducing enough therapeutic genes into injured liver to delay or cure liver fibrosis.