Reversing Multidrug Resistance in Chemo-resistant Human Lung Adenocarcinoma (A549/DOX) Cells by Algerian Propolis Through Direct Inhibiting the P-gp Efflux-pump, G0/G1 Cell Cycle Arrest and Apoptosis Induction

BACKGROUND

Lung cancer is one of the most common malignancies with the highest incidence and mortality rate worldwide. Multidrug Resistance (MDR) continues to pose a major challenge for the clinicians and pharmacologists to effectively treat this disease. A new approach using natural substances with moderate or low cytotoxic properties become a promising hope for reversing multidrug resistance due to pgp- overexpression.

OBJECTIVE

This study aims to explore the efficacy of Algerian propolis in reversing multidrug resistance and sensitizing chemo-resistant lung cancer cells (A549/DOX) to chemotherapy with DOX.

METHODS

Resistant lung adenocarcinoma A549/DOX cell line was developed and used as in vitro model for MDR. Cell viability, Annexin V-PI apoptosis assay and cell cycle progression were tested to evaluate the reversal effect of propolis alone or in combination with DOX. Caspases 3, 8 and 9 assays were conducted to determine the type of apoptotic pathway. To investigate the mechanisms of MDR reversal agents, intracellular accumulation of DOX and P-gp-pump activity were investigated.

RESULTS

Our results showed that the obtained chemo-resistant cells were 13-fold more resistant to DOX than the parental A549 cells. Propolis showed dramatically cell growth inhibition on A549/DOX cells (The IC50 was 50.44± 0.07µg/ml). The killing effect of propolis was due to G0/G1 cell cycle arrest and apoptosis induction. After 24hours treatment, propolis at 100 µg/ml caused cells accumulation in G0/G1 phase and increased with 50, 65-fold the percentage of apoptotic population sub-G. Annexin V-PI assay showed that propolis induces apoptosis with 53.57-fold at 100 µg/ml. It induced intrinsic apoptotic pathway by increasing caspase-3 (22.15-fold) and caspase-9 (16.73-fold) activities. The direct approach to investigate the mechanisms of reversal agents is to detect the accumulation of P-gp substrates in resistant cells. Our results indicated that resistant cells poorly accumulated Doxorubicin and rhodamine 123 (7-fold lower) when compared to parental A549 cells, suggesting that chemo-resistant cells overexpress P-gp which pump DOX out of cells. Propolis inhibited in a concentration-dependent manner, the pgp efflux-pump, enhancing thereby the intracellular level of DOX with 5.48- fold against 3.33 fold obtained with verapamil, the conventional P-gp inhibitor.

CONCLUSION

Taken together, Algerian propolis reverses multidrug resistance in resistant human lung adenocarcinoma cells through direct inhibiting the transport function of pgp-pump resulting in enhancing intracellular DOX-accumulation, G0/G1 cell cycle arrest and apoptosis induction. Thus, propolis could be developed as a chemotherapeutic agent for reversing multidrug resistance.

Artepillin C Induces Selective Oxidative Stress and Inhibits Migration and Invasion in a Comprehensive Panel of Human Cervical Cancer Cell Lines

BACKGROUND

Artepillin C (3,5-diprenyl-4-hydroxycinnamic acid) is the main bioactive component of Brazilian green propolis, and possesses, among other things, anticancer properties. However, to the best of our knowledge, there are no studies of artepillin C in cervical cancer.

METHOD

To explore a new therapeutic candidate for cervical cancer, we have evaluated the effects of artepillin C on cellular viability in a comprehensive panel of human cervical cancer-derived cell lines including HeLa (human papillomavirus/HPV 18-positive), SiHa (HPV 16-positive), CaSki (HPV 16- and 18-positive) and C33A (HPV-negative) cells compared to a spontaneously immortalized human epithelial cell line (HaCaT).

RESULTS

Our results demonstrated that artepillin C had a selective effect on cellular viability and could induce apoptosis possibly by intrinsic pathway, likely a result of oxidative stress, in all cancer-derived cell lines but not in HaCaT. Additionally, artepillin C was able to inhibit the migration and invasion of cancer cells.

CONCLUSION

Thus, artepillin C appears to be a promising new candidate as an anticancer drug for cervical cancer induced by different HPV types.

Dentinal Tubule Disinfection with Propolis & Two Extracts of Azadirachta indica Against Candida albicans Biofilm Formed on Tooth Substrate

Aim:

This study evaluates the disinfection of dentinal tubules using Propolis, Azadirachta indica (alcoholic and aqueous extracts), 2% chlorhexidine gel and calcium hydroxide against Candida albicans biofilm formed on tooth substrate.

Materials & Method:

One hundred and five human teeth were infected with Candida albicans for 2 days. Samples were divided into 7 groups. Group I- Propolis, Group II- Alcoholic extract of Azadirachta indica, Group III- Aqueous extract of Azadirachta indica, Group IV- 2% Chlorhexidine, Group V- Calcium hydroxide, Group VI- Ethanol and Group VII- Saline (negative control). At the end of 1,3 and 5 days, the antimicrobial efficacy of medicaments against Candida albicans was assessed at the depths of 200 µm and 400 µm.

Results:

The overall percentage inhibition of fungal growth (at 200 µm and 400 µm depth) was 99.2% with 2% chlorhexidine gel. There was no statistical difference between propolis, alcoholic extract of Azadirachta indica (neem) and 2% chlorhexidine.

Conclusion:

Propolis and alcoholic extract of Azadirachta indica performed equally well as that of 2% Chlorhexidine.

Comparative Evaluation of Antimicrobial Efficacy of MTAD, 3% NaOCI and Propolis Against E Faecalis

Aim

The present study sought to compare the antimicrobial efficacy of 3% NaOCl, Biopure MTAD (Tulsa Dentsply, Tulsa, OK) and Brazilian ethanolic extract of propolis (EEP) against Enterococcus faecalis (E. faecalis).

Methodology

The study utilized 55 extracted human permanent teeth with single root canal. The samples were decoronated, instrumented and sterilized. The teeth were infected with E faecalis for 48 hours. The teeth were divided randomly into 3 groups according to the irrigants used and kept in contact with the respective irrigant for 5 minutes. All the samples were incubated in brain heart infusion (BHI) broth for 96 hours. Disinfection of the samples was determined based on presence or absence of turbidity in the BHI broth 96 hours later. Statistical analysis was done using Chi-square test.

Results

All the samples treated with MTAD showed complete absence of turbidity, while all the 15 teeth treated with propolis showed presence of turbidity, 8 out of 15 teeth treated with NaOCl showed presence of turbidity. Statistical analysis of the data using chi-square test showed significant difference between the groups (P < 0.05).

Conclusion

The study concluded that MTAD was more effective than 3% NaOCl and propolis against E. faecalis.