Emerging novel mechanisms of action for nitric oxide in cancer progression

Nitric-Oxide Synthase trafficking inducer (NOSTRIN) is an emerging negative regulator of colon cancer progression

Background

NOSTRIN, abundantly expressed in colon, was reported to be anti-angiogenic, anti-invasive and anti-inflammatory. NOSTRIN expression was inversely related to survival of pancreatic ductal adeno-carcinoma patients. Yet its function and regulatory mechanism in CRC remains elusive.

Methods

NOSTRIN’s influence on EMT of CRC cells were analysed using realtime PCR array containing the functional EMT-transcriptome followed by western blotting. Regulation of oncogenic potential of CRC cells by NOSTRIN was elucidated using soft agar colony formation, trans-well invasion, wound healing and colonosphere formation assays. Biochemical assays were used to reveal mechanism of NOSTRIN function. Human CRC tissue array was used to test NOSTRIN mark in control and CRC disease stages.

Results

We showed here that CRC cell lines with less NOSTRIN expression has more invasive and migratory potential. NOSTRIN affected EMT-associated transcriptome of CRC cells by down regulating 33 genes that were functionally annotated to transcription factors, genes important for cell growth, proliferation, migration, cell adhesion and cytoskeleton regulators in CRC cells. NOSTRIN over-expression significantly reduced soft agar colony formation, wound healing and cell invasion. In line with this, RNA interference of Nostrin enhanced metastatic potential of CRC cells. Furthermore, stable overexpression of NOSTRIN in CRC cell line not only curtailed its ability to form colonosphere but also decreased expression of stemness markers CD133, CD44 and EpCAM. NOSTRIN’s role in inhibiting self-renewal was further confirmed using BrdU incorporation assay. Interestingly, NOSTRIN formed immune-complex with Cdk1 in CRC cells and aided in increase of inhibitory Y15 and T14 phosphorylation of Cdk1 that halts cytokinesis. These ex vivo findings were substantiated using human colon cancer tissue array containing cDNAs from patients’ samples with various stages of disease progression. Significant decrease in NOSTRIN expression was found with initiation and progression of advanced colon cancer disease stages.

Conclusion

We illustrate function of a novel molecule, NOSTRIN in curtailing EMT and maintenance of CRC cell stemness. Our data validates importance of NOSTRIN mark during onset and disease progression of CRC indicating its diagnostic potential.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09670-6.

Microwave-Assisted Synthesis of Schiff Base Metal–Ligand Complexes with Copper and Nickel Centres for Electrochemical In Vitro Sensing of Nitric Oxide in an Aqueous Solution

Nitric oxide (NO), the smallest signalling molecule known in the human body, keeps blood vessels dilated, controls blood pressure, and has numerous other health regulatory effects. The use of Schiff base complexes incorporated onto electrodes to make electrochemical sensors has been explored as an effective method for the determination and quantification of nitric oxide in aqueous solutions. Schiff base ligands were complexed with Cu and Ni metal centres using the microwave synthesis method to produce metal–ligand complexes with enhanced capabilites for NO detection. The electrical current generated at the anode is directly proportional to NO concentrations in the solution through its oxidation to HNO3. Various characterisation techniques were implemented to verify the integrity of each step of metal–ligand synthesis as well as the final product produced, using FT-IR, UV-VIS, and TGA. The as-synthesised Schiff base complexes were electrodeposited on screen-printed carbon electrodes (SPCE) and electrochemically evaluated in a 0.1 M PBS. Furthermore, metal complexes were screened for their in vitro activity towards NO detection in an aqueous solution (PBS). The results show that the investigated sensors (SPCE/Ni-BPND and SPCE/Cu-BPND) respond positively toward NO detection. It was, therefore, identified that the two sensors also do not differ significantly in terms of precision, sensitivity, and lowest detection limit. The sensor strategies demonstrate the NO limits of detection of 0.22 µM and 0.09 µM, and they also demonstrate sensitivity values of 16.3 µA/µM and 13.1 µA/µM for SPCE/Cu-BPND and SPCE/Ni-BPND sensors, respectively.

Greener Synthesis of Antiproliferative Furoxans via Multicomponent Reactions

Prostate and bladder cancers are commonly diagnosed malignancies in men. Several nitric oxide donor compounds with strong antitumor activity have been reported. Thus, continuing with our efforts to explore the chemical space around bioactive furoxan moiety, multicomponent reactions were employed for the rapid generation of molecular diversity and complexity. We herein report the use of Ugi and Groebke-Blackburn-Bienaymé multicomponent reactions under efficient, safe, and environmentally friendly conditions to synthesize a small collection of nitric-oxide-releasing molecules. The in vitro antiproliferative activity of the synthesized compounds was measured against two different human cancer cell lines, LNCaP (prostate) and T24 (bladder). Almost all compounds displayed antiproliferative activity against both cancer cell lines, providing lead compounds with nanomolar GI₅₀ values against the cancer bladder cell line with selectivity indices higher than 10.

Anti-inflammatory and anti-proliferative activities of chemical constituents from fungus Biscogniauxia whalleyi SWUF13-085

The fungus Biscogniauxia whalleyi SWUF13-085 from the Graphostomataceae family was studied for potential anti-inflammatory and anticancer agents. A diverse array of natural products was identified. Six of which were undescribed compounds, including xylariterpenoids L-N, (1R,2S,6R,7S)-1,2-dihydroxy-α-bisabolol, 6-[(1R)-1-hydroxy-1-methyl-2-propenyl]-4-methoxy-3-methyl-2H-pyran-2-one and (1R*,4S*,5S*,7S*,10R*)-guaia-11 (12)-en-7,10-diol. Several of the isolated compounds such as bergamotene, guaiane and phthalide derivatives showed activity in both the inhibition of nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophage cells with IC₅₀ values in the range of 2.48-10.82 μg/mL and anti-proliferation against HeLa cells with IC₅₀ values in the range of 8.64-31.16 μg/mL. While compounds such as cerebrosides A and C only exhibited inhibitory effects on NO production with IC₅₀ values in the range of 4.45-10.28 μg/mL.

A Novel Prodrug of a nNOS Inhibitor with Improved Pharmacokinetic Potential

Under different pathological conditions, aberrant induction of neuronal nitric oxide synthase (nNOS) generates overproduction of NO that can cause irreversible cell damage. The aim of this study was to develop an amidoxime prodrug of a potent nNOS inhibitor, the benzhydryl acetamidine. We synthesized the benzhydryl acetamidoxime, which was evaluated in vitro to ascertain the potential NOS inhibitory activity, as well as conducting bioconversion into the parent acetamidine. The prodrug was also profiled for in vitro physicochemical properties, by determining the lipophilicity, passive permeation through the human gastrointestinal tract and across the blood-brain barrier by PAMPA, and chemical, enzymatic, and plasma stability. The obtained data demonstrate that the amidoxime prodrug shows an improved pharmacokinetic profile with respect to the acetamidine nNOS inhibitor, thus suggesting that it could be a promising lead compound to treat all those pathological conditions in which nNOS activity is dysregulated.

Relevance of iNOS expression in tumor growth and maintenance of cancer stem cells in a bladder cancer model

The expression of inducible nitric oxide (NO) synthase (iNOS) in human bladder cancer (BC) is a poor prognostic factor associated with invasion and tumor recurrence. Here, we evaluated the relevance of iNOS expression in BC progression and in cancer stem cell (CSC) maintenance in a murine BC model. Also, iNOS expression and CSC markers were analyzed in human BC samples. iNOS inhibitors (L-NAME or 1400W) or shRNA were used on murine BC model with different iNOS expressions and invasiveness grades: MB49 (iNOS+, non-muscle invasive (NMI)) and MB49-I (iNOS++, muscle invasive (MI)), in order to analyzed cell proliferation, tumor growth, angiogenesis, number of CSC, and pluripotential marker expression. iNOS, SOX2, Oct4, and Nanog expressions were also analyzed in human BC samples by qPCR and immunohistochemistry. iNOS inhibtion reduced parameters associated with tumor progression and reduced the number of CSC, wich resulted higher in MB49-I than in MB49, in concordance with the higher expression of SOX2, Oct4, and Nanog. The expression of SOX2 was notoriously diminished, when iNOS was inhibited only in the MI cell line. Similar results were observed in human samples, where MI tumors expressed higher levels of iNOS and pluripotential genes, in comparison to NMI tumors with a positive correlation between those and iNOS, suggesting that iNOS expression is associated with CSC. iNOS plays an important role in BC progression and CSC maintenance. Its inhibition could be a potential therapeutic target to eradicate CSC, responsible for tumor recurrences. KEY MESSAGES: • iNOS expression is involved in bladder tumor development, growth, and angiogenesis. • iNOS expression is involved in bladder cancer stem cell generation and maintenance, playing an important role regulating their self-renewal capacity, especially in muscle invasive murine bladder cancer cells. • iNOS expression is higher in human muscle invasive tumors, in association with a high expression of pluripotential genes, especially of SOX2.

Role of nitric oxide in the response to photooxidative stress in prostate cancer cells

A continuous state of oxidative stress during inflammation contributes to the development of 25% of human cancers. Epithelial and inflammatory cells release reactive oxygen species (ROS) and reactive nitrogen species (RNS) that can damage DNA. ROS/RNS have biological implications in both chemoresistance and tumor recurrence. As several clinically employed anticancer drugs can generate ROS/RNS, we have addressed herein how inducible nitric oxide synthase and nitric oxide (iNOS/^•NO) affect the molecular pathways implicated in the tumor response to oxidative stress. To mimic the oxidative stress associated with chemotherapy, we used a photosensitizer (pheophorbide a) that can generate ROS/RNS in a controlled manner. We investigated how iNOS/^•NO modulates the tumor response to oxidative stress by involving the NF-κB and Nrf2 molecular pathways. We found that low levels of iNOS induce the development of a more aggressive tumor population, leading to survival, recurrence and resistance. By contrast, high levels of iNOS/^•NO sensitize tumor cells to oxidative treatment, causing cell growth arrest. Our analysis showed that NF-κB and Nrf2, which are activated in response to oxidative stress, communicate with each other through RKIP. For this critical role, RKIP could be an interesting target for anticancer drugs. Our study provides insight into the complex signaling response of cancer cells to oxidative treatments as well as new possibilities for the rational design of new therapeutic strategies.