NRON mediates the degradation of tat protein to participate in HIV-1 infection. Interestingly, our study observed the down-regulation of NRON in triple-negative breast cancer (TNBC) tissues compared with paired adjacent healthy tissues. In contrast, lncRNA snaR was up-regulated in TNBC tissues and was inversely correlated with NRON. Expression levels of snaR increased, while expression levels of NRON decreased along with the increase of clinical stages. The snaR overexpression resulted in promoted cancer cell proliferation but did not significantly affect NRON expression. NRON overexpression inhibited cancer cell proliferation and down-regulated snaR. The snaR overexpression reduced the effects of NRON overexpression. We therefore conclude that NRON may down-regulate lncRNA snaR to inhibit cancer cell proliferation in TNBC.

Background: Circular RNAs (circRNAs) have been proven to function as pivotal regulators in cancer occurrence and progression. However, the function of circ_0006404 (circRNA Forkhead box O3 (circFOXO3)in prostate cancer (PCa) is poorly understood. Methods: The enrichment of circ_0006404, FOXO3, microRNA-1299 (miR-1299) and cofilin 2 (CFL2) was measured by quantitative real-time polymerase chain reaction (qRT-PCR). The viability, metastasis and proliferation were determined by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, transwell and colony formation assays, respectively. Flow cytometry was used to assess cell cycle progression and apoptosis. Circ_0006404/miRNAs interactions were explored using Circular RNA Interactome database, while TargetScan software was used for seeking the targets of miR-1299. Dual-luciferase reporter assay, RNA-pull down and RNA immunoprecipitation (RIP) assays were conducted to verify the target interaction between miR-1299 and circ_0006404 or CFL2. CFL2 protein level was analyzed by Western blot assay. Animal experiments were performed to test the role of circ_0006404 in PCa tumor growth in vivo. Results: Circ_0006404 level was notably elevated in PCa. Circ_0006404 contributed to the viability, metastasis and proliferation and impaired the apoptosis of PCa cells. Circ_0006404 directly targeted miR-1299, and miR-1299 silencing largely reversed circ_0006404 interference-induced influences in PCa cells. CFL2 directly bound to miR-1299, and miR-1299-induced effects in PCa cells were largely attenuated by CFL2 overexpression. CFL2 was regulated by circ_0006404/miR-1299 axis in PCa cells. Circ_0006404 promoted PCa progression via miR-1299/CFL2 axis in vivo. Conclusion: Circ_0006404 accelerated the survival, motility and proliferation while impeded the apoptosis of PCa cells via miR-1299/CFL2 axis. Circ_0006404 might be a stable potential bio-marker for PCa diagnosis and treatment.

Hematopoietic progenitor kinase 1 (HPK1) belongs to the mitogen activated protein kinase kinase kinase kinase (MAP4K) family of serine/threonine kinases, which have been associated with the incidence and progression of a variety of gastrointestinal malignant tumors in humans. However, the potential association between HPK1 expression and breast cancer, particularly invasive ductal carcinoma‑not otherwise specified (IDC‑NOS) development, has not yet been examined. To address this gap, the present study aimed to evaluate HPK1 expression in IDC‑NOS samples and to determine a relationship with clinical prognostic indicators, such as the expression levels of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2), as well as overall survival of the patients with IDC‑NOS. HPK1 mRNA and protein expression in samples from 148 patients with IDC‑NOS were detected using immunohistochemistry, western blotting and reverse transcription‑quantitative polymerase chain reaction. A total of 54 out of 148 (36.5%) samples were HPK1‑positive, and 100 out of 148 (67.6%) were ER‑positive. Of the latter, 28% (28/100) were HPK1‑positive, and a significant negative association of HPK1 expression with ER positivity was observed (P=0.002; r=‑0.254). In addition, 43.2% (64/148) and 32.4% (48/100) of IDC‑NOS tissues were PR‑ or HER2‑positive, respectively; however, neither indicator correlated with HPK1 (P=0.109 and P=0.558, respectively). HPK1 expression, axillary lymph node metastasis and tumor‑node‑metastasis (TNM) stage were identified as independent factors of overall survival (OS) in the ER‑positive group (P<0.05), and HPK1 positivity was associated with increased OS (P=0.048). HPK1 mRNA levels did not differ between IDC‑NOS and normal adjacent breast tissues, whereas HPK1 protein levels were lower in IDC‑NOS (P<0.05). These results suggested that HPK1 protein may be a potentially effective IDC-NOS therapeutic target.