Orexin 2 receptor as a potential target for immunotoxin and antibody-drug conjugate cancer therapy

Synthesis of Pyrrolo[3,4-b]pyridin-5-ones via Ugi-Zhu Reaction and In Vitro-In Silico Studies against Breast Carcinoma

An Ugi-Zhu three-component reaction (UZ-3CR) coupled in a one-pot manner to a cascade process (N-acylation/aza Diels-Alder cycloaddition/decarboxylation/dehydration) was performed to synthesize a series of pyrrolo[3,4-b]pyridin-5-ones in 20% to 92% overall yields using ytterbium triflate as a catalyst, toluene as a solvent, and microwaves as a heat source. The synthesized molecules were evaluated in vitro against breast cancer cell lines MDA-MB-231 and MCF-7, finding that compound 1f, at a concentration of 6.25 μM, exhibited a potential cytotoxic effect. Then, to understand the interactions between synthesized compounds and the main proteins related to the cancer cell lines, docking studies were performed on the serine/threonine kinase 1 (AKT1) and Orexetine type 2 receptor (Ox2R), finding moderate to strong binding energies, which matched accurately with the in vitro results. Additionally, molecular dynamics were performed between proteins related to the studied cell lines and the three best ligands.

Orexin A affects HepG2 human hepatocellular carcinoma cells glucose metabolism via HIF-1α-dependent and -independent mechanism

Orexins are hypothalamic neuropeptides that regulate feeding, reward, wakefulness and energy homeostasis. The present study sought to characterize the involvement of orexin A in glucose metabolism in HepG2 human hepatocellular carcinoma cells, and investigated the role of hypoxia-inducible factor-1α (HIF-1α) in the response. HepG2 cells were exposed to different concentrations of orexin A (10⁻⁹ to 10⁻⁷ M) in vitro, without or with the orexin receptor 1 (OX1R) inhibitor (SB334867), HIF-1α inhibitor (YC-1) or a combination of both inhibitors. Subsequently, OX1R, HIF-1α expression and localization, glucose uptake, glucose transporter 1 (GLUT1) expression and ATP content were measured. We further investigated the intracellular fate of glucose by measuring the gene expression of pyruvate dehydrogenase kinase 1 (PDK1), lactate dehydrogenase (LDHA) and pyruvate dehydrogenase B (PDHB), as well as metabolite levels including lactate generation and mitochondrial pyruvate dehydrogenase (PDH) activity. The activity of phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway was also assessed. Our results showed that the expression of OX1R was predominantly located in the nucleus in HepG2 cells. Orexin A oxygen-independently promoted the mRNA and protein expression of HIF-1α as well as its nuclear accumulation in HepG2 cells and the elevated HIF-1α protein was associated, at least partly, with the activation of the PI3K/Akt/mTOR pathway. Orexin A stimulated GLUT1 expression, glucose uptake as well as ATP generation in HepG2 cells via OX1R acting through the HIF-1α pathway. Moreover, orexin A inhibited LDHA, PDK1 expression and lactate production, stimulated PDHB expression and PDH enzyme activity independent of HIF-1α. Our results indicated that orexin signaling facilitated the glucose flux into mitochondrial oxidative metabolism rather than glycolysis in HepG2 cells. These findings provide new insight into the regulation of glucose metabolism by orexin A in hepatocellular carcinoma cells.

Elevated Expression of Ox2R in Cervical Cancers and Placentas of Uyghur Women in Xinjiang, China

Objective:

Cervical cancer is one of the major causes of mortality of Uyghur women in Xinjiang, China. Although increased expression of orexin receptor (OxR), known to be strongly expressed in human placenta, has a proven relation to some cancers, there have been few studies of cervical cancer. Thus, we explored this question by evaluating the expression of orexin receptor as a biomarker for screening early stage of cervical cancer in Uyghur women with highest occurrence rate of cervical cancer in China.

Study Design:

We used polymerase chain reaction (PCR) and immunohistochemical staining to determine the expression of both Ox1R and Ox2R in cervical cancer and cervicitis biopsies collected from Uyghur women infected with human papilloma virus (HPV)16. The expression rate was compared between cervical cancers of low, intermediate and high differentiation and cervicitis.

Results:

Although there was no significant difference in the expression rate of Ox1R between groups, Ox2R was significantly overexpressed in cervical cancer patients when compared to the cervicitis group. Ox1R was negative in normal human placenta while Ox2R was positive.

Conclusions:

While expression of Ox1R had no correlation with invasion or metastatic potential, Ox2R demonstrated elevation in cervical cancer with heterogeneity in groups with different metastatic potential, in the human placenta as well, implying that it might serve as an indicator of invasive capacity along with other indices.