Original Article
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World J Gastroenterol. Nov 7, 2014; 20(41): 15275-15288
Published online Nov 7, 2014. doi: 10.3748/wjg.v20.i41.15275
Differential control of growth, apoptotic activity and gene expression in human colon cancer cells by extracts derived from medicinal herbs, Rhazya stricta and Zingiber officinale and their combination
Ayman I Elkady, Rania Abd El Hamid Hussein, Osama A Abu-Zinadah
Ayman I Elkady, Osama A Abu-Zinadah, Department of Biological Sciences, Faculty of Sciences, King Abdulaziz University, Jeddah 21589, Saudi Arabia
Ayman I Elkady, Zoology Department, Faculty of Science, Alexandria University, Alexandria, Egypt
Rania Abd El Hamid Hussein, Department of Clinical Nutrition, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah 21589, Saudi Arabia
Rania Abd El Hamid Hussein, Gamal Abd El Nasser Hospital, Alexandria, Egypt
Author contributions: Elkady AI designed and performed the research; Abu-Zinadah OA contributed analytic tools; Elkady AI and Hussein RAEH analyzed the data; and Elkady AI and Hussein RAEH wrote the paper.
Supported by Funding from the Deanship of Scientific Research, King Abdulaziz University, No. 1431/130/159
Correspondence to: Dr. Osama A Abu-Zinadah, Professor of Cell Biology and Histology, Department of Biological Sciences, Faculty of Sciences, King Abdulaziz University, Jeddah 21589, Saudi Arabia. oaboznada@kau.edu.sa
Telephone: +966-2-692662 Fax: +966-2-6952290
Received: March 3, 2014
Revised: June 29, 2014
Accepted: July 11, 2014
Published online: November 7, 2014
Processing time: 252 Days and 5.8 Hours
Abstract

AIM: To investigate the effects of extracts from Rhazya stricta (R. stricta) and Zingiber officinale (Z. officinale) on human colorectal cancer cells.

METHODS: Human colorectal cancer cells (HCT116) were subjected to increasing doses of crude alkaloid extracts from R. stricta (CAERS) and crude flavonoid extracts from Z. officinale (CFEZO). Cells were then harvested after 24, 48 or 72 h and cell viability was examined by trypan blue exclusion dye test; clonogenicity and soft agar colony-forming assays were also carried out. Nuclear stain (Hoechst 33342), acridine orange/ethidium bromide double staining, agarose gel electrophoresis and comet assays were performed to assess pro-apoptotic potentiality of the extracts. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR), using gene-specific primers and Western blot analyses were performed to assess the impact of CAERS and CFEZO on the expression levels of key regulatory proteins in HCT116 cells.

RESULTS: Treatment with a combination of CAERS and CFEZO synergistically suppressed the proliferation, colony formation and anchorage-independent growth of HCT116 cells. Calculated IC50, after 24, 48 and 72 h, were 70, 90 and 130 μg/mL for CAERS, 65, 85 and 120 μg/mL for CFEZO and 20, 25 and 45 μg/mL for both agents, respectively. CAERS- and CFEZO-treated cells exhibited morphologic and biochemical features of apoptotic cell death. The induction of apoptosis was associated with the release of mitochondrial cytochrome c, an increase in the Bax/Bcl-2 ratio, activation of caspases 3 and 9 and cleavage of poly ADP-ribose polymerase. CAERS and CFEZO treatments downregulated expression levels of anti-apoptotic proteins including Bcl-2, Bcl-X, Mcl-1, survivin and XIAP, and upregulated expression levels of proapoptotic proteins such as Bad and Noxa. CAERS and CFEZO treatments elevated expression levels of the oncosuppressor proteins, p53, p21 and p27, and reduced levels of the oncoproteins, cyclin D1, cyclin/cyclin-dependent kinase-4 and c-Myc.

CONCLUSION: These data suggest that a combination of CAERS and CFEZO is a promising treatment for the prevention of colon cancer.

Keywords: Apoptosis; Colorectal cancer; Oncogenes; Phytochemicals; Tumor suppressor proteins

Core tip: Many medicinal plants represent a cornerstone for chemoprevention of colorectal cancer (CRC). Nonetheless, monotherapy with these agents has been unsatisfactory; therefore attention has turned towards therapies combining these plant-based extracts. In this study, we found that a combination of crude alkaloid and flavonoid extracts prepared from the medicinal herbs Rhazya stricta and Zingiber officinale, respectively, acted synergistically to suppress proliferation, induce apoptosis and modulate expression levels of cell cycle regulatory proteins in CRC cells. These results provide a foundation and rationale for exploiting these extracts for the prevention of CRC.