Crosstalk between aldehyde dehydrogenase-1 and chemoresistance in breast cancer: Insights into the role of vitamin D3

Piperine enhances doxorubicin sensitivity in triple-negative breast cancer by targeting the PI3K/Akt/mTOR pathway and cancer stem cells

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer that lacks an actionable target with limited treatment options beyond conventional chemotherapy. Therapeutic failure is often encountered due to inherent or acquired resistance to chemotherapy. Previous studies implicated PI3K/Akt/mTOR signaling pathway in cancer stem cells (CSCs) enrichment and hence chemoresistance. The present study aimed at investigating the potential effect of piperine (PIP), an amide alkaloid isolated from Piper nigrum, on enhancing the sensitivity of TNBC cells to doxorubicin (DOX) in vitro on MDA-MB-231 cell line and in vivo in an animal model of Ehrlich ascites carcinoma solid tumor. Results showed a synergistic interaction between DOX and PIP on MDA-MB-231 cells. In addition, the combination elicited enhanced suppression of PI3K/Akt/mTOR signaling that paralleled an upregulation in this pathway's negative regulator, PTEN, along with a curtailment in the levels of the CSCs surrogate marker, aldehyde dehydrogenase-1 (ALDH-1). Meanwhile, in vivo investigations demonstrated the potential of the combination regimen to enhance necrosis while downregulating PTEN and curbing PI3K levels as well as p-Akt, mTOR, and ALDH-1 immunoreactivities. Notably, the combination failed to change cleaved poly-ADP ribose polymerase levels suggesting a pro-necrotic rather than pro-apoptotic mechanism. Overall, these findings suggest a potential role of PIP in decreasing the resistance to DOX in vitro and in vivo, likely by interfering with the PI3K/Akt/mTOR pathway and CSCs.

Emerging perspectives: unraveling the anticancer potential of vitamin D3

Vitamin D3, a fat-soluble vitamin known for its critical function in calcium homeostasis and bone health, is gaining interest for its anticancer properties. Observational studies have suggested a negative relationship between vitamin D levels and the incidence of some malignancies throughout the years, prompting substantial investigation to find its anticancer effects. The purpose of this comprehensive review is to investigate the diverse function of vitamin D3 in cancer prevention and therapy. We explored the molecular mechanism underlying its effects on cancer cells, which range from cell cycle control and death to angiogenesis and immune response modulation. Insights from in vitro and in vivo studies provide valuable evidence supporting its anticancer potential. Furthermore, we look at epidemiological and clinical studies that investigate the relationship between vitamin D3 levels and cancer risk or treatment results. Vitamin D3 supplementation's safety profile and cost-effectiveness increase its attractiveness as an adjuvant therapy in conjunction with traditional treatment regimens. Our critical review of the current literature provides an in-depth understanding of vitamin D3's anticancer effect, covering the obstacles and possibilities in realizing its promise for cancer prevention and therapy. The findings of this study might pave the way for the development of innovative treatment techniques that take use of the advantages of vitamin D3 to fight cancer and improve patient care. As research progresses, a better understanding of vitamin D3's anticancer processes will surely simplify its incorporation into personalized cancer care techniques, hence enhancing patient outcomes in the battle against cancer.

Combinations of Calcitriol with Anticancer Treatments for Breast Cancer: An Update

Preclinical, clinical, and epidemiological studies indicate that vitamin D3 (VD) deficiency is a risk factor for the development of breast cancer. Underlying mechanisms include the ability of calcitriol to induce cell differentiation, inhibit oncogenes expression, and modify different signaling pathways involved in the control of cell proliferation. In addition, calcitriol combined with different kinds of antineoplastic drugs has been demonstrated to enhance their beneficial effects in an additive or synergistic fashion. However, a recognized adjuvant regimen based on calcitriol for treating patients with breast cancer has not yet been fully established. Accordingly, in the present work, we review and discuss the preclinical and clinical studies about the combination of calcitriol with different oncological drugs, aiming to emphasize its main therapeutic benefits and opportunities for the treatment of this pathology.

Insight Into Nicotinamide Adenine Dinucleotide Homeostasis as a Targetable Metabolic Pathway in Colorectal Cancer

Tumour cells modify their cellular metabolism with the aim to sustain uncontrolled proliferation. Cancer cells necessitate adequate amounts of NAD and NADPH to support several enzymes that are usually overexpressed and/or overactivated. Nicotinamide adenine dinucleotide (NAD) is an essential cofactor and substrate of several NAD-consuming enzymes, such as PARPs and sirtuins, while NADPH is important in the regulation of the redox status in cells. The present review explores the rationale for targeting the key enzymes that maintain the cellular NAD/NADPH pool in colorectal cancer and the enzymes that consume or use NADP(H).

Thymoquinone upregulates miR-125a-5p, attenuates STAT3 activation, and potentiates doxorubicin antitumor activity in murine solid Ehrlich carcinoma

In breast cancer, there has been evidence of atypical activation of signal transduction and activators of transcription 3 (STAT3). Thymoquinone (TQ) exerts its anti-neoplastic effect through diverse mechanisms, including STAT3 inhibition. The tumor suppressor, microRNA-125a-5p was reported to be downregulated in various breast cancer cells. Therefore, we investigated the influence of TQ and/or doxorubicin on microRNA-125a-5p and its correlation with STAT3 activation as well as tumor growth in mice bearing solid Ehrlich tumors. We found that TQ markedly suppressed inducible and constitutive phosphorylation of STAT3 in tumor tissue without affecting STAT5. Moreover, it attenuated tumor growth, downregulated STAT3 downstream target proteins, and increased the apoptotic activities of caspase-3 and -9. Interestingly, TQ-elicited synergism of doxorubicin anti-neoplastic activity was coupled with upregulation of tumoral microRNA-125a-5p. Taken together, the current findings raise the potential of TQ as a promising chemomodulatory adjuvant to augment mammary carcinoma sensitivity to doxorubicin.

Newly-identified Pathways Relating Vitamin D to Carcinogenesis: A Review

BACKGROUND

The epidemiological relationship between vitamin D levels and cancer has been thoroughly investigated. Published data from large studies appear to corroborate a significant relationship between higher serum vitamin D concentrations and improved survival. Mechanistic reviews on commonly-studied cancers - including breast cancer, colon cancer and melanoma - focus predominantly on data from older studies. In outlining avenues for future research, we believe there is utility in summarizing novel findings introduced to the literature.

MATERIALS AND METHODS

In this narrative review, we used MEDLINE, PUBMED and Cochrane databases to identify mechanistic studies published from January 1, 2015 onwards exploring this topic.

RESULTS

Twenty-five mechanistic studies were included in this review. It was found that vitamin D plays a critical role in both direct (i.e. tumor gene expression, proliferation, invasiveness, sensitivity to chemotherapy etc.) and indirect (i.e. effects on the tumor microenvironment and immunomodulation) tumor suppression mechanisms.

CONCLUSION

These newly-identified pathways warrant further research, with the hopes that we may understand how and when vitamin D supplementation can be integrated into precision medicine therapeutics for cancers of the breast, colon and skin. Cancer care providers should consider recommendations to screen for vitamin D deficiency in this population.