Vitamin B12 enhances the antitumor activity of 1,25-dihydroxyvitamin D3 via activation of caspases and targeting actin cytoskeleton.

BACKGROUND: 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) is an effective anticancer agent, and when combined with other agents it shows superior activities. Vitamin B12 has been shown to contribute to increasing the effectiveness of anticancer drugs when used in combination. Thus, the current study aimed at investigating the anticancer potential of the combination of 1,25(OH)2D3 and vitamin B12. METHODS: MTT assay was used to determine the cytotoxic activity of combining 1,25(OH)2D3 and vitamin B12 against six different cancer cell lines and one normal cell line. The surviving fraction after clonogenic assay was measured, and the effects of 1,25(OH)2D3/B12 combination on the activity of different caspases, cell adhesion, actin cytoskeleton, cell morphology, and percentage of polarized cells were evaluated. RESULTS: Vitamin B12 did not cause cytotoxicity, however, it enhanced the cytotoxicity of 1,25(OH)2D3 against cancer cells. The cytotoxic effects of 1,25(OH)2D3 and its combination with vitamin B12 was not evident in the normal mammary MCF10A cell line indicating cancer cell-specificity. The cytotoxic effects of 1,25(OH)2D3/B12 combination occurred in a dose-dependent manner and was attributed to apoptosis induction which was mediated by caspase 4 and 8. Moreover, 1,25(OH)2D3/B12-treated cells showed enhanced inhibition of clonogenic tumor growth, reduced cell adhesion, reduced cell area, reduced percentage of cell polarization, and disorganized actin cytoskeleton resulting in reduced migratory phenotype when compared to cells treated with 1,25(OH)2D3 alone. CONCLUSION: 1,25(OH)2D3 and vitamin B12 exhibited synergistic anticancer effects against different cancer cell lines. The combination therapy of 1,25(OH)2D3 and vitamin B12 may provide a potential adjunctive treatment option for some cancer types.

mRNA localization is linked to translation regulation in the Caenorhabditis elegans germ lineage.

Caenorhabditis elegans early embryos generate cell-specific transcriptomes despite lacking active transcription, thereby presenting an opportunity to study mechanisms of post-transcriptional regulatory control. We observed that some cell-specific mRNAs accumulate non-homogenously within cells, localizing to membranes, P granules (associated with progenitor germ cells in the P lineage) and P-bodies (associated with RNA processing). The subcellular distribution of transcripts differed in their dependence on 3'UTRs and RNA binding proteins, suggesting diverse regulatory mechanisms. Notably, we found strong but imperfect correlations between low translational status and P granule localization within the progenitor germ lineage. By uncoupling translation from mRNA localization, we untangled a long-standing question: Are mRNAs directed to P granules to be translationally repressed, or do they accumulate there as a consequence of this repression? We found that translational repression preceded P granule localization and could occur independently of it. Further, disruption of translation was sufficient to send homogenously distributed mRNAs to P granules. These results implicate transcriptional repression as a means to deliver essential maternal transcripts to the progenitor germ lineage for later translation.

Biological activity and apoptotic signaling pathway of C11-functionalized cephalostatin 1 analogues.

Cephalostatin 1, a potent anti-cancer agent, is a natural bis-steroidal alkaloid that causes cell death in the subnanomolar to picomolar ranges via an atypical apoptosis pathway. Although cephalostatin 1 is a highly effective anticancer drug, its availability limits its utilization. We previously reported the synthesis of two 12'α-hydroxy derivatives of cephalostatin 1 that induce cell death by activating the ER stress apoptosis signaling pathway. For the current work, we synthesized six C11-functionalized cephalostatin 1 analogues (CAs) to evaluate their biological activity. For the cytotoxic compounds, the induced apoptotic pathway was investigated. The C11-functionalized cephalostatin 1 analogues 5 and 6 (CA5 and CA6) were found to exhibit cytotoxic activity against K-562 leukemia cells, MCF-7 breast cancer cells and DU-145 prostate cancer cells, while the remaining four analogues did not show anti-tumor activities against any of the cell lines. Our results indicated that CA5 and CA6 induced cell death via the atypical ER-dependent apoptosis pathway; they increased the expression of Smac/DIABLO, an inhibitor of inhibitors of apoptosis (IAPs), which in turn facilitated the activation of different caspases including the ER-caspase 4 without cytochrome c release from mitochondria. CA5 and CA6 are promising anticancer agents due to their low GI50, the remarkable apoptosis pathway they induce which can overcome chemoresistance, and their very low toxicity to normal cells making them cephalostatin 1 utilizable alternatives.

Alu DNA Polymorphism of Human Tissue Plasminogen Activator (tPA) Gene in Diabetic Jordanian Patients

Background: Hypercoagulability and hypofibrinolysis are among the symptoms exhibited by diabetic patients. Our study aimed to address the polymorphic nature of Alu DNA fragment in the human tissue plasminogen activator gene within diabetes mellitus (DM) Jordanian patients. Methods: Genomic DNA was isolated from 76 DM patients and 60 non-diabetic Jordanian individuals, and the Alu fragment was amplified using PCR. Results: The results showed that 80% of the non-diabetic Jordanian subjects were homozygotes for the deletion of the Alu fragment (Alu-/-), 16.7% were homozygotes for its insertion (Alu+/+), and 3.3% were heterozygotes (Alu+/-). Besides, 36.8% of the diabetic patients exhibited the Alu-/- or Alu+/- genotype, and 26.3% were Alu+/+. The Alu-/- genotype occurred less frequently in the diabetic individuals. Conclusion: The high frequency of the Alu-/- genotype constitutes a protective deletion with respect to DM within the normal subjects.

Cephalostatin 1 analogues activate apoptosis via the endoplasmic reticulum stress signaling pathway.

The current study was conducted to compare the cytotoxicity of two stereospecific cephalostatin 1 analogues (CAs) against several human normal cell types and cancer cell lines and to determine their cytotoxic mechanism. Both CA analogues induced apoptosis and were cytotoxic with 50% growth inhibition (GI50) at ~1µM or less in six human cancer cell lines but neither analogue at 10µM killed more than 14% of any of three types of normal human cells suggesting their cytotoxicity is cancer-specific. CA treatment inhibited clonogenic tumor growth and activated caspase 3 and 9 but not caspase 8. CA-induced apoptosis was inhibited by the pan caspase inhibitor indicating the importance of caspase activation. CA treatment released smac/DIABLO but not cytochrome c from mitochondria and induced phosphorylation of eIF-2 and the activation of procaspase 4 in cancer cells, similar to cell treatment with thapsigargin, a known endoplasmic reticulum (ER) stress inducer. Finally, cells pretreated with a caspase 4 inhibitor were resistant to CA-induced apoptosis. In conclusion, both CAs induced apoptosis by triggering ER stress. Because of their ease of synthesis and low GI50, these cephalostatin analogues represent promising anticancer drugs.