Novel nonsecosteroidal VDR ligands with phenyl-pyrrolyl pentane skeleton for cancer therapy

Novel Nonsecosteroidal Vitamin D Receptor Modulator Combined with Gemcitabine Enhances Pancreatic Cancer Therapy through Remodeling of the Tumor Microenvironment

In a pancreatic tumor microenvironment, activated pancreatic stellate cells (PSCs) produce extracellular matrix (ECM) to form a barrier to drug penetration. Moreover, the interaction between cancer cells and activated PSCs promotes the tumor growth. Vitamin D receptor (VDR), as a key regulator to promote the recovery of PSCs to the resting state, is an attractive therapeutic target for pancreatic cancer. Herein, we reported the design and synthesis of 57 nonsecosteroidal VDR modulators based on the skeleton of phenyl-pyrrolyl pentane. Among them, compounds C4, I5, and I8 exhibited excellent VDR affinity and effective inhibition of the activation of PSCs, as well as potent suppression of the interaction between cancer cells and PSCs in vitro. In vivo, compound I5 combined with gemcitabine achieved efficacious antitumor activity without causing hypercalcemia. In conclusion, the compounds designed in our study can remodel the tumor microenvironment and are expected to be candidates for the treatment of pancreatic cancer.

Discovery of novel nonsteroidal VDR agonists with novel diarylmethane skeleton for the treatment of breast cancer

Vitamin D receptor (VDR) is recognized as a potential target for the treatment of breast cancer which is the most common malignancy among women in the world. In this study, a series of nonsecosteroidal VDR agonists with a novel diarylmethane skeleton was designed, synthesized and the anti-tumor activities of these compounds were determined. Compound 28 was identified as the most effective agents in reducing the viability of MCF-7 cells, with a low IC₅₀ via the inhibition of cell cycle and induction of apoptosis by regulating the expression of p21, Bcl2 and Bax. In addition, compound 28 showed high VDR-binding affinity and displayed significant VDR-agonistic activities. Further investigation revealed that compound 28 inhibited tumor growth in an orthotopic breast-tumor model without causing hypercalcemia which is the main side effect of secosteroidal VDR modulators. In summary, these findings discovered novel VDR modulators as promising candidates for cancer chemotherapy.

Further Developments of the Phenyl-Pyrrolyl Pentane Series of Nonsteroidal Vitamin D Receptor Modulators as Anticancer Agents

The vitamin D₃ receptor (VDR), which belongs to the nuclear-receptor superfamily, is a potential molecular target for anticancer-drug discovery. In this study, a series of nonsteroidal vitamin D mimics with phenyl-pyrrolyl pentane skeletons with therapeutic potentials in cancer treatment were synthesized. Among them, 11b and 11g were identified as the most effective agents in reducing the viability of four cancer-cell lines, particularly those of breast-cancer cells, with IC₅₀ values in the submicromolar-concentration range. In addition, 11b and 11g possessed VDR-binding affinities and displayed significant partial VDR-agonistic activities determined by dual-luciferase-reporter assays and human-leukemia-cell-line (HL-60)-differentiation assays. Furthermore, 11b and 11g inhibited tumor growth in an orthotopic breast-tumor model via inhibition of cell proliferation and induction of cell apoptosis. More importantly, 11b and 11g exhibited favorable pharmacokinetic behavior in vivo and did not increase serum calcium levels or cause any other apparent side effects. In summary, 11b and 11g act as novel VDR modulators and may be promising candidates for cancer chemotherapy.