The pro-apoptotic role of autophagy in breast cancer

BACKGROUND

Autophagy is a catabolic process that has a vital role in cancer progression and treatment. Current chemotherapeutic agents, which target autophagy, result in growth inhibition in many cancer types. In this study, we examined the role of autophagy in breast cancer (BCa) patients as well as BCa cell lines.

METHODS

Tissue microarray was used to detect the expression of an autophagy marker, LC3B in BCa patients (normal/hyperplasia=8; grade-I=15, grade-II=84, and grade-III=27) and BCa cell lines. To modulate the activation of autophagy, we used novel herbal compound nimocinol acetate (NA) in BCa cell lines and the anticancer activity was measured by phenotypic and molecular analysis.

RESULTS

LC3B is highly expressed in tumours as compared with normal tissues. Activation of LC3B in NA-treated BCa (MCF-7 and MDA-MB-231) cells was evident as compared with other autophagy makers. Further, our results confirmed that NA-transcriptionally regulates LC3B (as confirmed by mRNA levels and reporter assay), which resulted in the formation of acidic autophagy vesicles and autolysosomes in BCa cells. Nimocinol acetate inhibited mTOR-mediated pro-survival signalling that resulted in inhibition of growth in BCa cells without affecting normal breast epithelial cells. Downregulation of LC3B expression by siRNA significantly inhibited the anticancer effects of NA in BCa cells.

CONCLUSIONS

Together, our results suggest that LC3B is highly expressed in BCa tissues and increasing the threshold of LC3B activation dictates the pro-apoptotic function, which in turn, suppresses the growth of BCa cells. Nimocinol acetate could be a potential agent for treatment of BCa.

Malaria and Nutritional Status in Children Living on the Coast of Kenya

The relationship between malnutrition and malaria is controversial. On one hand, malaria may cause malnutrition, while on the other, malnutrition itself may modulate susceptibility to the disease. We investigated the association between Plasmodium falciparum malaria and malnutrition in a cohort of children living on the coast of Kenya. The study involved longitudinal follow‐up for clinical malaria episodes and anthropometric measurements at four cross‐sectional surveys. We used Poisson regression analysis to investigate the association between malaria and nutritional status. Compared to baseline (children with a WAZ or HAZ score of ≥−2), the crude incidence rate ratios (IRRs) for malaria in children with low HAZ or WAZ scores (<−2) during the period prior to assessment were 1.17 (95% CI 0.91–1.50; 0 = 0.21) and 0.94 (0.71–1.25; 0.67), respectively, suggesting no association between malaria and the subsequent development of PEM. However, we found that age was acting as an effect modifier in the association between malaria and malnutrition. The IRR for malaria in children 0–2 years old who were subsequently characterized as wasted was 1.65 (1.10–2.20; P = 0.01), and a significant overall relationship between malaria and low‐HAZ was found on regression analysis when adjusting for the interaction with age (IRR 1.89; 1.01–3.53; P < 0.05). Although children living on the coast of Kenya continue to suffer clinical episodes of uncomplicated malaria throughout their first decade, the association between malaria and malnutrition appears to be limited to the first 2 years of life.

Simultaneous expression and detection of multiple retroviral constructs in haematopoietic cells after bone marrow transplantation

Due to the complexity and redundancy of molecular processes governing the development and function of haematopoietic cells, experimental procedures allowing simultaneous alteration in gene expression of multiple genes in vivo are needed. Here, we describe a protocol allowing for simultaneous transduction of haematopoietic stem cells (HSC) with two different replication incompetent retroviral expression vectors followed by transplantation of lethally irradiated recipient mice. These bicistronic retroviral vectors carried genes for the enhanced green and yellow florescent proteins (EGFP and EYFP) respectively. Spleen cells from reconstituted animals were stained for common lymphocyte and myeloid markers, then analysed on a two-laser, 488 and 635 nm, flow cytometer equipped with a 510/20-nm bandpass filter for FL1, a 550/30-nm bandpass filter for FL2 and a 530-nm short-pass dichroic mirror. It was demonstrated that cells expressing EGFP, EYFP or combinations thereof could be distinguished and analysed for staining with PerCP- and APC-conjugated reagents. We found that a sizable proportion of cells (70%) from reconstituted animals expressed EGFP and/or EYFP and that expression of these genes did not affect lymphoid or myeloid development. We also demonstrated that the alternative optical configuration allowed for conventional multiparameter flow cytometric analyses.

Cytokine mRNA expression and iron status in children living in a malaria endemic area

Iron deficiency has been reported to affect both malaria pathogenesis and cell-mediated immune responses; however, it is unclear whether the protection afforded by iron deficiency is mediated through direct effects on the parasite, through immune effector functions or through both. We have determined cytokine mRNA expression levels in 59 children living in a malaria endemic area on the coast of Kenya who we selected on the basis of their biochemical iron status. Real-time quantitative reverse transcriptase polymerase chain reaction analysis of cytokine mRNA levels of peripheral blood mononuclear cells (PBMC) obtained from these children showed an association between interleukin-4 (IL-4) mRNA levels and all the biochemical indices of iron that we measured. Furthermore, IL-10 mRNA was higher in parasite blood smear-positive children than in blood smear-negative children irrespective of their iron status. This study suggests that IL-4 expression by PBMC may be affected by iron status.