Effects of siRNA targeting c-Myc and VEGF on human colorectal cancer Volo cells

Overexpression of Hypermethylated Homeobox A11 (HOXA11) Inhibits Tumor Cell Growth and Induces Apoptosis in Cervical Cancer

This study aimed to elucidate the potential of Homeobox A11 (HOXA11) as a therapeutic target and a diagnostic methylation marker for cervical cancer. Gene expression analysis using cDNA microarray in cervical cancer cell lines revealed significantly reduced expression of the HOXA11 gene. Subsequent investigation of HOXA11 promoter methylation in samples from normal individuals and invasive cervical cancer patients showed over 53.2% higher methylation in cancer scrapes compared to normal scrapes. Furthermore, overexpression of HOXA11, which is downregulated in cervical cancer, strongly suppressed cell growth in cervical cancer cell lines, HeLa and HT3. Additionally, we performed transferase dUTP nick end labeling assay and confirmed that the inhibition of cervical cancer cell proliferation occurred via apoptosis. Mechanistically, overexpression of HOXA11 led to mitochondrial apoptosis characterized by PARP cleavage due to increased c-Myc and enhanced cytochrome C secretion into the cytoplasm. These findings suggest that HOXA11 could potentially serve as a methylation marker for diagnosing cervical cancer and as a novel therapeutic target for its treatment.

Anti-c-myc RNAi-Based Onconanotherapeutics

Overexpression of the c-myc proto-oncogene features prominently in most human cancers. Early studies established that inhibiting the expression of oncogenic c-myc, produced potent anti-cancer effects. This gave rise to the notion that an appropriate c-myc silencing agent might provide a broadly applicable and more effective form of cancer treatment than is currently available. The endogenous mechanism of RNA interference (RNAi), through which small RNA molecules induce gene silencing by binding to complementary mRNA transcripts, represents an attractive avenue for c-myc inhibition. However, the development of a clinically viable, anti-c-myc RNAi-based platform is largely dependent upon the design of an appropriate carrier of the effector nucleic acids. To date, organic and inorganic nanoparticles were assessed both in vitro and in vivo, as carriers of small interfering RNA (siRNA), DICER-substrate siRNA (DsiRNA), and short hairpin RNA (shRNA) expression plasmids, directed against the c-myc oncogene. We review here the various anti-c-myc RNAi-based nanosystems that have come to the fore, especially between 2005 and 2020.

MYC Participates in Lipopolysaccharide-Induced Sepsis via Promoting Cell Proliferation and Inhibiting Apoptosis

OBJECTIVE

This study aimed to explore the potential mechanism of MYC proto-oncogene, BHLH Transcription Factor (MYC) gene, on sepsis.

MATERIALS AND METHODS

In this experimental study, rat-derived H9C2 cardiomyocyte cells were cultured in vitro, followed by lipopolysaccharide (LPS) treatment with different concentration gradients. The cholecystokinin octapeptide (CCK-8) assay, enzyme-linked immunoassay (ELISA) assay, quantitative reverse transcription polymerase chain reaction (qRT-PCR), cell transfection, Western blot and flow cytometry were used to observe the cellular apoptosis and proliferation of cells in both treated LPS groups and normal control group.

RESULTS

The result of CCK-8 assay showed that silencing MYC inhibited cellular proliferation of sepsis in absence or presence of LPS treatment. ELISA assay showed that the expressions of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) were decreased in MYC silenced group, but they were increased after LPS treatment. Moreover, Flow cytometry assay showed that MYC silencing contributed to the apoptosis of sepsis cells. Furthermore, the expression of inflammatory factors showed that MYC silencing elevated the expression of inflammation factors.

CONCLUSION

MYC might take part in the process of LPS induced sepsis through suppressing apoptosis and inducing cell proliferation. Moreover, MYC might reduce inflammation during the progression of LPS induced sepsis.

Hepatitis B Virus X Protein and Hepatocarcinogenesis

Chronic hepatitis B virus (HBV) infection is one of the most associated factors in hepatocarcinogenesis. HBV is able to integrate into the host genome and encode the multi-functional hepatitis B virus x protein (HBx). Although the mechanism between HBx and carcinogenesis is still elusive, recent studies have shown that HBx was able to influence various signaling pathways, as well as epigenetic and genetic processes. This review will examine and summarize recent literature about HBx’s role in these various processes.

miR-320b suppresses cell proliferation by targeting c-Myc in human colorectal cancer cells

BACKGROUND

MicroRNAs (miRNAs) are small noncoding RNAs that potentially play a critical role in tumorigenesis. Mounting evidence indicates that one specific miRNA: miR-320b is down regulated in numerous human cancers, including colorectal cancer (CRC); making the hypothesis that miR-320b may play a key role in tumorigenesis plausible. However, its role in carcinogenesis remains poorly defined. The goal of this study is to better clarify the role of miR-320b in tumor growth of CRC.

METHODS

Quantitative reverse-transcription polymerase chain reaction (qRT-PCR) was conducted to detect the expression of miR-320b in CRC tissues and 5 CRC cell lines. The effect of miR-320b on cell proliferation was analyzed in vitro and in vivo. Furthermore, a luciferase reporter assay was performed to measure the target effects of miR-320b. Lastly, the messenger RNA (mRNA) and protein levels of the gene c-MYC were measured in CRC cell lines and tissues by qRT-PCR, and confirmed via Western blot and Immunohistochemical (IHC) staining.

RESULTS

The results presented here showed that miR-320b expression was down regulated in both CRC tissues and cells. Overexpression of miR-320b in CRC cells was statistically correlated with a decrease of cell growth in vitro and in vivo, while c-MYC was identified as a target gene of miR-320b in CRC. Furthermore, it was found that up-regulation of c-Myc can attenuate the effects induced by miR-320b.

CONCLUSIONS

Our identification of c-MYC as a target gene of miR-320b provides new insights into the pathophysiology of CRC proliferation, and identifies miR-320b as a novel therapeutic target for the treatment of CRC.

Simultaneous silencing of VEGF and KSP by siRNA cocktail inhibits proliferation and induces apoptosis of hepatocellular carcinoma Hep3B cells

Background

Vascular endothelial growth factor (VEGF) is involved in the growth of new blood vessels that feed tumors and kinesin spindle protein (KSP) plays a critical role in mitosis involving in cell proliferation. Simultaneous silencing of VEGF and KSP, an attractive and viable approach in cancer, leads on restricting cancer progression. The purpose of this study is to examine the therapeutic potential of dual gene targeted siRNA cocktail on human hepatocellular carcinoma Hep3B cells.

Results

The predesigned siRNAs could inhibit VEGF and KSP at mRNA level. siRNA cocktail showed a further downregulation on KSP mRNA and protein levels compared to KSP-siRNA or VEGF-siRNA, but not on VEGF expression. It also exhibited greater suppression on cell proliferation as well as cell migration or invasion capabilities and induction of apoptosis in Hep3B cells than single siRNA simultaneously. This could be explained by the significant downregulation of Cyclin D1, Bcl-2 and Survivin. However, no sigificant difference in the mRNA and protein levels of ANG2, involving inhibition of angiogenesis was found in HUVECs cultured with supernatant of Hep3B cells treated with siRNA cocktail, compared to that of VEGF-siRNA.

Conclusion

Silencing of VEGF and KSP plays a key role in inhibiting cell proliferation, migration, invasion and inducing apoptosis of Hep3B cells. Simultaneous silencing of VEGF and KSP using siRNA cocktail yields promising results for eradicating hepatocellular carcinoma cells, a new direction for liver cancer treatment.

c-Myc plays part in drug resistance mediated by bone marrow stromal cells in acute myeloid leukemia

Acute myeloid leukemia (AML) is a malignant and aggressive disease not sensitive to chemotherapy. The dynamic interaction between AML cells and bone marrow (BM) microenvironment plays a critical role in response of this disease to chemotherapy. It is reported that mesenchymal stromal cells (MSC) are essential component of bone marrow microenvironment which affects the survival of AML cells. The aim of our research is to elucidate the mechanism of drug resistance of AML cells associated with MSC. We found that adhesion of AML cell lines U937, KG1a and primary AML cells to MSC inhibited cytotoxic drug-induced apoptosis. Western blot showed that c-Myc of AML cells cocultured with stroma was up-regulated. Treatment with 10058-F4, a small molecule inhibitor of MYC-MAX heterodimerization, or c-Myc siRNA significantly induced apoptosis. Western blot analysis further showed that inhibition of c-Myc induced expression of caspases-3, cleavage of PARP and reduced expression of Bcl-2, Bcl-xL and vascular endothelial growth factor (VEGF). Thus, we conclude that MSCs protected leukemia cells from apoptosis, at least in part, through c-Myc dependent mechanisms, and that c-Myc contributed to microenvironment-mediated drug resistance in AML. In summary, we declared that c-Myc is a potential therapeutic target for overcoming drug resistance in AML.