Renal Cell Carcinoma Associated With TSC/MTOR Genomic Alterations: An Update on its Expanding Spectrum and an Approach to Clinicopathologic Work-up

Study on the synthesis, characterization, and antitumor mechanism investigation of QZQ-01115 via targeting sphingosine kinase 2

Sphingosine kinase 2 (SphK2) is an oncogenic enzyme that plays an essential role in the development of oral squamous cell carcinoma (OSCC). Therefore, development of SphK2 inhibitors is of great significance for the treatment of OSCC. In this study, we synthesized a series of thiazolidinediones and screened compounds with good inhibitory activity against CAL-27 using cytotoxicity assay. The compounds were further investigated in vitro using a series of in vitro experiments such as Western blot and qPCR were used to investigate the in vivo anti-tumor mechanisms, and in vivo investigation was applied by using a nude mouse ectopic tumor model. The results showed that four new compounds were successfully synthesized, and among which the compound named QZQ-01115 showed the best inhibitory activity against CAL-27 at the concentration of 5.84 ± 0.042 μM. Further mechanistic studies showed that QZQ-01115 could inhibit the proliferation, migration and invasion of CAL-27 cells at a concentration of 4 μM-6 μM. QZQ-01115 affected the PI3K/AKT signaling pathway by influencing the levels of S1P and ceramides in CAL-27, which in turn affected the mTOR/p70S6K, resulting in the blockage of protein synthesis and the blockage of cell cycle at the G0/G0 level. Apoptosis was promoted by down-regulating Bcl-2 and up-regulating Bax. The in vivo results showed that QZQ-01115 reduced the volume and weight of xenograft tumors in nude mice. The induction of apoptosis by QZQ-01115 was further determined by HE staining and immunohistochemical analysis. These results suggest that QZQ-01115 may be a potential candidate for the treatment of OSCC.

Decoding the genetic puzzle: Mutations in key driver genes of pancreatic neuroendocrine tumors

Although pancreatic neuroendocrine tumors (PanNETs) are less common than other pancreatic tumors, they show significant differences in clinical behavior, genetics, and treatment responses. The understanding of the molecular pathways of PanNETs has gradually improved with advances in sequencing technology. Mutations in MEN1 (the most frequently varied gene) may result in the deletion of the tumor suppressor menin, affecting gene regulation, DNA repair, and chromatin modification. Changes in ATRX and DAXX involve chromatin remodeling, telomere stability and are associated with the alternative lengthening of telomeres (ALT) pathway and aggressive tumors. VHL mutations emphasize the roles of hypoxia and angiogenesis. Mutations in PTEN, TSC1/TSC2, and AKT1-3 often disrupt the mTOR pathway, complicating the genetic landscape of PanNETs. Understanding these genetic alterations and their impact on the PI3K/AKT/mTOR axis help to investigate new targeted therapies, which in turn can improve patient prognosis. This review aims to clarify PanNET pathogenesis through key mutations and their clinical relevance.

Genetic validation of a TSC2 immunohistochemistry assay in TSC/mTOR-pathway altered renal tumors

Pathogenic mutations in the genes associated with tuberous sclerosis complex (TSC)/mTOR pathway are linked to histologically diverse renal cell neoplasms, including eosinophilic solid and cystic renal cell carcinoma (ESC RCC), low grade oncocytic tumor (LOT), eosinophilic vacuolated tumor (EVT), and xanthomatous giant cell renal cell carcinoma (XGC RCC). Here, we validate a TSC2 immunohistochemistry (IHC) assay by comparison to genomic data in these neoplasms. Automated TSC2 IHC was performed on formalin-fixed paraffin embedded (FFPE) tissues from 38 genetically-confirmed TSC/mTOR-associated renal tumors (6 ESCs, 16 EVTs, 13 LOTs, 2 XGC and 1 clear cell RCC) and visually scored in a semi-dichotomous fashion compared to internal control tissue. The positive predictive value (PPV) of TSC2 protein loss for underlying pathogenic mutation in TSC2 was 92% (11/12), while the negative predictive value (NPV) of intact TSC2 by IHC for lack of underlying pathogenic mutation in TSC2 was 81% (21/26). Intact TSC2 by IHC was 95% (21/22) specific for absence of underlying pathogenic TSC2 mutation. All the cases lacking TSC2 mutation with intact TSC2 protein had an underlying mutation in TSC1, MTOR or PIK3CA. Loss of TSC2 was 77% (10/13) sensitive for underlying TSC2 truncation mutations and 33% (1/3) sensitive for underlying TSC2 missense mutations. Overall, 73% (8/11) tumors with TSC2 IHC loss and underlying pathogenic alterations in TSC2 showed heterogeneous protein loss, with rare interspersed positively staining tumor cells. These data support TSC2 IHC as a potentially useful assay for the diagnostic workup of renal tumors suspected to belong to the TSC/mTOR-associated subgroups.

The Spectrum of Renal "TFEopathies": Flipping the mTOR Switch in Renal Tumorigenesis

The mammalian target of Rapamycin complex 1 (mTORC1) is a serine/threonine kinase that couples nutrient and growth factor signaling to the cellular control of metabolism and plays a fundamental role in aberrant proliferation in cancer. mTORC1 has previously been considered an "on/off" switch, capable of phosphorylating the entire pool of its substrates when activated. However, recent studies have indicated that mTORC1 may be active toward its canonical substrates, eukaryotic translation initiation factor 4E-binding protein 1 (4EBP1) and S6 kinase (S6K), involved in mRNA translation and protein synthesis, and inactive toward TFEB and TFE3, transcription factors involved in the regulation of lysosome biogenesis, in several pathological contexts. Among these conditions are Birt-Hogg-Dubé syndrome (BHD) and, recently, tuberous sclerosis complex (TSC). Furthermore, increased TFEB and TFE3 nuclear localization in these syndromes, and in translocation renal cell carcinomas (tRCC), drives mTORC1 activity toward the canonical substrates, through the transcriptional activation of the Rag GTPases, thereby positioning TFEB and TFE3 upstream of mTORC1 activity toward 4EBP1 and S6K. The expanding importance of TFEB and TFE3 in the pathogenesis of these renal diseases warrants a novel clinical grouping that we term "TFEopathies." Currently, there are no therapeutic options directly targeting TFEB and TFE3, which represents a challenging and critically required avenue for cancer research.

Frequency and clinicopathologic features of renal low-grade oncocytic tumour and eosinophilic vacuolated tumour: reclassification of 605 eosinophilic tumours including patients managed with active surveillance

AIMS

Low-grade oncocytic tumour (LOT) and eosinophilic vacuolated tumour (EVT) are recently described emerging entities, which demonstrate distinct features but are not yet recognised as separate neoplasms in the fifth WHO classification. Published series to date have been largely multi-institutional and based on surgically resected tumours. This study aims to determine the frequency, clinicopathologic features and outcome of LOT and EVT in a single institutional series of oncocytic/eosinophilic renal neoplasms, including patients managed with active surveillance and non-surgical intervention.

METHODS AND RESULTS

Cases were identified from a consecutive institutional series of in-house renal tumours diagnosed on biopsy and/or nephrectomy (2003-2023). Tumours with a diagnosis or differential diagnosis of oncocytoma, chromophobe renal cell carcinoma or oncocytic neoplasm not otherwise specified (including LOT, EVT and tumours with overlapping hybrid features) were retrospectively reviewed and classified/reclassified.In total, 605 oncocytic/eosinophilic renal neoplasms were reviewed, among which 33 LOT (5.5%) and 5 EVT (0.8%) were identified. LOT were CK7+, CD117- and GATA3+ (94%). EVT were CD117+, CK7 focal+ (80%) and cathepsin K+ (80%). At the median follow-up of 34 months (range 2-253) and 56 months (range 8-90) for LOT and EVT, respectively, there was no evidence of recurrence following ablation/surgical resection, metastasis or death from disease for all patients, including the 22 managed with active surveillance (20 LOT and 2 EVT).

CONCLUSIONS

LOT and EVT comprised a minority of oncocytic renal neoplasms in this series. We report a large institutional series including patients managed non-surgically, with no adverse outcome, adding to the existing literature indicating a benign outcome.