(1) Background: Shikonin, the main ingredient in Chinese herbal medicine, is described as a novel angiogenesis inhibitor, and its anticancer effects have already been studied. Shikonin and its derivatives induce apoptosis and suppress metastasis, which further enhance the effectiveness of chemotherapy. However, their mechanism of function has not been completely elucidated on human renal cancer cells. (2) Methods: In our study, CAKI-2 and A-498 cells were treated with increasing concentrations (2.5–40 µM) of shikonin, when colony formation ability and cytotoxic activity were tested. The changes in the expression of the main targets of apoptotic pathways were measured by RT-qPCR and Western blot. The intracellular levels of miR-21 and miR-155 were quantified by RT-qPCR. (3) Results: Shikonin exerted a dose-dependent effect on the proliferation of the cell lines examined. In 5 µM concentration of shikonin in vitro elevated caspase-3 and -7 levels, the proteins of the Ras/MAPK and PI3K/AKT pathways were activated. However, no significant changes were detected in the miR-21 and miR-155 expressions. (4) Conclusions: Our findings indicated that shikonin causes apoptosis of renal cancer cells by activating the Ras/MAPK and PI3K/AKT pathways. These effects of shikonin on renal cancer cells may bear important potential therapeutic implications for the treatment of renal cancer.

Background: MicroRNAs (miRNAs) play a regulatory role in various human cancers. The roles of hsa-miR-15a-5p, hsa-miR-99b-5p, and hsa-miR-181a-5p have not been fully explored in the angiogenesis of renal cell carcinoma (RCC). Aims: The present study aimed to evaluate the expression of these miRNAs in tumorous and adjacent healthy tissues of RCC. Methods: Paired tumorous and adjacent normal kidney tissues from 20 patients were studied. The expression levels of hsa-miR-15b-5p, hsa-miR-99b-5p, and hsa-miR-181a-5p were quantified by TaqMan miRNA Assays. Putative targets were analyzed by qRT-PCR. Results: Significant downregulation of all three miRNAs investigated was observed in tumorous samples compared to adjacent normal kidney tissues. Spearman analysis showed a negative correlation between the expression levels of miRNAs and the pathological grades of the patients. Increased expression of vascular endothelial growth factor-A (VEGF-A) and hypoxia-inducible factor-1α (HIF-1α), a tissue inhibitor of metalloproteinases-1 (TIMP-1), was observed in tumorous samples compared to adjacent normal tissues. Depletion of tissue inhibitors of metalloproteinase-2 (TIMP-2) and metalloproteinase-2 (MMP-2) was detected compared to normal adjacent tissues. The examined miRNAs might function as contributing factors to renal carcinogenesis. However, more prospective studies are warranted to evaluate the potential role of miRNAs in RCC angiogenesis.

Background: Programmed cell death protein-1 (PD-1) and its ligands, PD-L1 and PD-L2, constitute a central immune checkpoint pathway that regulates T-cell activity and tumor immune escape, while their relationship with STAT signaling remains incompletely understood in ccRCC. Methods: We analyzed 27 paired ccRCC and adjacent non-tumorous human kidney tissue samples. mRNA levels of PD-1, PD-L1, PD-L2, STAT1, and STAT3 were quantified by RT-qPCR. In addition, representative human ccRCC cell lines (CAKI-2 and A-498) were treated with IFN-γ to assess the time-dependent modulation of immune checkpoint molecules and STAT pathway activation. Results: PD-L1 and PD-L2 were significantly upregulated in tumor tissues compared with adjacent normal kidney tissue. Exploratory observation suggests grade dependent increase. Whereas PD-1 was predominantly downregulated, IFN-γ treatment induced a rapid transcriptional upregulation of PD-L1 and PD-L2 in RCC cell lines, with maximal protein accumulation observed at 72 h. STAT1, but not STAT3, exhibited dynamic induction following IFN-γ stimulation, showing temporal association with PD-L1 and PD-L2 upregulation, indicating cell-line-specific regulatory effects. Correlation analyses confirmed a strong correlation between PD-1 and its ligands, whereas STAT1 and STAT3 expression showed no direct association with PD-L1 or PD-L2 levels in cancer samples. Conclusions: Our findings demonstrate that PD-L1 and PD-L2 are frequently upregulated in ccRCC and dynamically regulated by IFN-γ/STAT1-dependent signaling. Our results provide additional insight into the mechanisms of immune escape and underscore the potential of integrated profiling of PD-1 ligands and STAT signaling to guide personalized immunotherapeutic strategies in ccRCC.

Background: Shikonin, a natural compound derived from Lithospermum erythrorhizon, exhibits anticancer properties by inducing apoptosis in various tumor types, including clear cell renal cell carcinoma (ccRCC) cell lines CAKI-2 and A-498. This study investigates the mechanisms underlying shikonin-induced apoptosis, focusing on microRNAs miR-15b, miR-99b, and miR-181a in ccRCC. Materials and Methods: ccRCC cells were treated with 5 µM shikonin. Expression levels of miR-15b, miR-99b, and miR-181a were measured by TaqMan PCR. Apoptosis-related targets (AKT3, PDCD4, FOXO1, FOXO3, JNK1, and LAMTOR3) were identified in silico and validated by qRT-PCR and Western blot. Spearman’s correlation was used to evaluate miRNA–target relationships. Ingenuity Pathway Analysis explored relevant pathways. Results: Shikonin decreased miR-15b, miR-99b, and miR-181a levels in CAKI-2 cells, whereas these miRNAs were increased in A-498 cells, demonstrating cell-line-specific effects. qRT-PCR and Western blot confirmed changes in target expression, suggesting regulation by these miRNAs. In A-498 cells, miR-181a expression positively correlated with the studied target levels during 24–72 h of treatment, indicating that its potential regulatory role may be cell-type-dependent. MiR-15b and miR-99b showed linear correlations with targets in both cell lines, but expression patterns differed, suggesting direct regulation alongside potential involvement in additional pathways contributing to shikonin-induced apoptosis. Conclusions: Shikonin induces apoptosis in renal cancer cells by modulating the MAPK/ERK pathway and through cell-line-specific, cell-type-dependent regulation of miR-15b, miR-99b, and miR-181a. These findings highlight the importance of cell-type-dependent miRNA regulation and underscore the therapeutic potential of shikonin in ccRCC.

Immunotherapy has become one of the primary forms of cancer treatment. The inhibition of immune checkpoint molecules, including indoleamine 2,3-dioxygenase (IDO), is a promising approach for immunotherapy. Phosphatase and tensin homolog (PTEN) is well known as a tumor suppressor that antagonizes oncogenic signaling molecules/pathways and plays a key role in the prognosis and (immuno)therapy of the disease. In this study, twenty healthy and tumorous renal tissue pairs were investigated, and the mRNA (RT-qPCR) and protein (Western blot) expression of IDO and PTEN were analyzed. In two cancer cell lines (CAKI-2; A-498), the protein of IDO and PTEN was measured followed by IDO induction with interferon alpha-2 (IFN-α2). According to our results, a significantly higher mRNA expression of IDO and PTEN was found in tumorous tissues compared to the adjacent healthy kidney specimens. The mRNA expression of IDO and PTEN showed a positive correlation in 80% of the sample pairs. Western blot results confirmed the protein expression of both IDO and PTEN. In the cell lines, immunocytochemistry showed that IDO is inducible with IFN-α2. In summary, our results suggest that IDO expression may play a role in the development of renal cancer, and IDO as well as PTEN might be potential biomarkers for patients with RCC.

Background: Uveal melanoma is the most common intraocular malignancy in adults with a poor prognosis. Although local therapies are effective, treatment options for advanced disease remain limited. Combination strategies using chemotherapeutic agents and natural compounds, such as quercetin, are in focus for their potential to enhance antitumor efficiency and overcome resistance. Methods: The effects of doxorubicin, quercetin, and their combination were investigated in uveal melanoma cell lines. Cell viability was determined by an MTT assay, and apoptosis and cell cycle distribution by flow cytometry. Invasion assays were performed to evaluate metastatic potential, while modifications in signaling pathways were analyzed by Western blotting and qPCR. Results: Both doxorubicin and quercetin significantly reduced cell viability and induced apoptotic and necrotic cell death. The combination treatment demonstrated additional inhibitory effects in both cell lines, shown by increased SubG1 populations, reduced invasive capacity, and modulation of signaling pathways. Cell cycle analysis indicated treatment-induced growth inhibition. Notably, pathway modifications varied between cell lines, suggesting heterogeneous responses. Conclusions: Quercetin may potentiate certain antitumor effects of doxorubicin in uveal melanoma, particularly by reducing post-treatment invasiveness and modulating certain PI3K/AKT pathway-related proteins. These results support the possibility of quercetin-based combination therapies, although further molecular and in vivo studies are required.