Lymphovascular invasion (LVI) and lymph node metastasis are conventional pathological factors associated with an unfavorable prognosis of urothelial carcinoma of the upper urinary tract (UC-UUT), but little is known about the molecular mechanisms underlying LVI and nodal metastasis in this disease. Rac1 small GTPase (Rac1) is essential for tumor metastasis. Activated GTP-bound Rac1 (Rac1 activity) plays a key role in activating downstream effectors known as Pak (21-activated kinase), which are key regulators of cytoskeletal remolding, cell motility, and cell proliferation, and thus have a role in both carcinogenesis and tumor invasion.

Background: The system L amino acid transporter (LAT) has an important role in the transport of various amino acids, and there have been reports about the relation of this system to cancer. Although LATs are highly expressed in the kidneys, little is known about their influence on human renal cancer. Methods: To clarify the role of LATs in human clear cell renal cell carcinoma (RCC), we investigated the expression of mRNAs for LAT1, LAT2, LAT3, LAT4, and 4F2hc in clear cell RCC tissues. The mRNAs of these five genes were analyzed by the real-time reverse transcription polymerase chain reaction in matched sets of tumor and non-tumor tissues obtained at operation from 82 Japanese patients with clear cell RCC. We also measured phosphorylated S6 ribosomal protein (Ser-235/236) proteins levels in 18 paired tumor and non-tumor tissues of the patients by Western blotting. Results: Expression of LAT1 mRNA was significantly increased in tumor tissue compared with non-tumor tissue, while expression of LAT2 and LAT3 mRNAs was reduced. There was no difference in the expression of LAT4 and 4F2hc mRNAs between tumor and non-tumor tissues. Increased expression of LAT1 mRNA was associated with less differentiated tumors, local invasion, microscopic vascular invasion, and metastasis. Kaplan-Meier survival analysis showed that a higher serum LAT1 mRNA level was associated with a shorter overall survival time. Phosphorylated S6 ribosomal protein levels were associated with metastatic potential. LAT1 mRNA levels positively correlated with phosphorylated S6 ribosomal protein proteins levels in primary tumors. Conclusions: These findings suggest that LAT1 mRNA is related to the invasive and progressive potential of clear cell RCC.

The Ran small GTPase (Ran) is involved in the regulation of nuclear transport, microtubule nucleation and dynamics, and spindle assembly. To address the question of whether Ran protein is associated with the progression of renal cell carcinoma (RCC), we compared by Western blotting the Ran protein levels in surgical RCC specimens from 180 consecutive Japanese patients with those in the corresponding nontumor tissue from the same patient. We also examined the Ran protein levels in tumors of different grades and stages. Ran proteins were more abundant in RCC tumor tissues than in nontumor tissues (p < 0.0001). High Ran expression was associated with higher grade, local invasion, and metastasis (p < 0.0001). Kaplan‐Meier plots linked high Ran protein expression to a shorter overall survival in all cases (p < 0.0001) and a shorter disease‐free survival in those without metastasis at radical or partial nephrectomy (M0; 131 cases, p < 0.0001). Ran protein expression was an independent factor influencing overall survival univariate analysis (p < 0.0001) and disease‐free survival by multivariate analysis (p < 0.05). Our findings suggest that Ran is associated with the progression of RCC.

Hepcidin has an important role in iron metabolism. We investigated whether hepcidin was involved in renal cell carcinoma (RCC).

Renal cell carcinoma (RCC) is an immunogenic and proangiogenic cancer. Although antivascular endothelial growth factor (VEGF) therapies achieve impressive responses in some patients, many tumors eventually develop resistance to such therapy. The B7 family molecules such as CTLA‐4, PD‐1, and PD‐L1 are pivotal players in immune checkpoints that positively or negatively regulate various immune responses. Recently, immunotherapy based on blocking immune checkpoints with anti‐CTLA4, anti‐PD‐1, or anti‐PD‐L1 antibodies has been proposed as a potential new approach to the treatment of metastatic RCC. Higher expression of PD‐L1 and B7‐H4 in the tumors is associated with a poor prognosis in RCCs, however, the clinical impact of serum levels of B7 family molecules has not been elucidated in patients with metastatic RCCs receiving VEGF‐targeted agents. We assessed the preoperative serum levels of B7 family molecules, including CD80, CD86, PD‐1, PD‐L1, B7‐H3, B7‐H4, and CTLA‐4, and CD28 in RCC patients, and determined their relations with various clinicopathological characteristics. Elevated preoperative serum levels of PD‐L1 and B7‐H4 were correlated with less differentiated tumors, higher invasive and metastatic potential, a worse response to anti‐VEGF therapy, and shorter overall survival. These findings suggested that investigating preoperative serum levels of PD‐L1 and B7‐H4 might not only be useful to assess the biological aggressiveness of RCCs, but also to predict the efficacy of anti‐VEGF therapy and the eventual prognosis, indicating the future design of clinical trials of therapies targeting immune checkpoint in advanced RCCs.