Papillary renal cell carcinoma: current and controversial issues

Papillary renal cell carcinoma revisited: impact of the World Health Organization 2022 classification on prognostication

OBJECTIVES

To investigate the impact of the revised papillary renal cell carcinoma (PRCC) classification and evaluate its validity with regard to oncological outcome stratification.

PATIENTS AND METHODS

Identifying 527 patients with PRCC who underwent surgical resection from 1995 to 2022, a tissue microarray was constructed for immunohistochemical and molecular characterisation. Re-classification according to the World Health Organization (WHO) 2022 criteria and nuclear grading according to the WHO/International Society of Urological Pathologists criteria were done. In addition to the revised subtype, alleged clinicopathological prognosticators were analysed with respect to progression-free (PFS) and cancer-specific survival (CSS).

RESULTS

Initially, 247 (46.9%) cases were Type 1, 234 (44.4%) were Type 2, and 46 (8.7%) were papillary not-otherwise-specified. According to the revised criteria, 29.9% of Type 1 and 57.7% of Type 2 PRCC cases were re-classified. Re-classified from Type 1 included more indolent tumours while from Type 2 PRCC many molecularly defined tumours were newly identified. After re-classification, still 373 tumours remained with distinct histomorphological features of Type 1 (254 [70%]) and Type 2 (119 [42.2%]) PRCC. Furthermore, significant differences in survival outcomes were obtained when the revised criteria was used particularly for tumours of ≤4 cm. For a median (interquartile range) follow-up of 79 (38.2-132.8) months, the 5-year PFS was 97% for Type 1, 80% for Type 2, 75% for transcription factor for immunoglobulin heavy-chain enhancer 3 (TFE3)-rearranged, and 43.5% for fumarate hydratase-deficient RCC. No disease progression was observed in patients with papillary renal neoplasm with reverse polarity.

CONCLUSION

The revised WHO 2022 classification enhanced prognostic accuracy for PRCC particularly for small tumours. Retaining previous subtypes may confer further clinical as well as prognostic value.

Urologic Imaging of the Kidneys: Cancers and Mimics

Renal cell carcinoma (RCC) is a growing problem in global oncology, with a steadily increasing incidence, especially in developed regions. Its different histologic subtypes present different challenges in diagnosis and management. Advanced imaging techniques have a crucial role in distinguishing between these subtypes by highlighting unique radiographic features such as exophytic growth patterns, cystic components, and enhancement patterns. Practical suggestions discussed in this review include using chemical shift MRI to differentiate fat-poor angiomyolipomas from RCC, recognizing specific imaging markers such as pseudo-capsule in papillary RCC, and understanding the implications of negative pixel count in computed tomography scans.

Cytologic diagnosis of papillary renal neoplasm with reverse polarity

BACKGROUND

Papillary renal neoplasm with reverse polarity is a recently recognized low-grade neoplasm with a favorable prognosis. To date, its cytologic features have not been well documented.

METHODS

Two patients with papillary renal neoplasm with reverse polarity sampled by fine needle aspiration and core needle biopsy are described, one of whom is under active surveillance without clinical progression and the other is alive and well 16 years after partial nephrectomy.

RESULTS

The cytologic features included a mix of papillae and dispersed cells with abundant oncocytic cytoplasm and round, bland nuclei apically displaced away from the papillary core. Immunohistochemistry showed positive staining for GATA3 in both cases. Molecular studies on one of the cases showed a KRAS p.G12V mutation.

CONCLUSIONS

The cytologic features of this distinctive, indolent neoplasm are important to recognize because patients with papillary renal neoplasm with reverse polarity may be excellent candidates for partial nephrectomy or even active surveillance.

Androgen Receptor and Non-Coding RNAs' Interaction in Renal Cell Carcinoma

Renal cell carcinoma (RCC), the most prevalent among the urogenital cancers, accounts for around 3% of new cancer cases worldwide. Significantly, the incidence of RCC has doubled in developed world countries, ranking it as the sixth most common cancer in males, who represent two-thirds of RCC cases. Males with RCC exhibit a higher mortality rate and tend to develop a more aggressive form of the disease than females. Sex-related risk factors, including lifestyle and biological variations, explain this difference. The androgen receptor (AR) oncogenic signaling pathway has been extensively studied among the biological factors that affect RCC. Recent advancements in high-throughput RNA sequencing techniques have underscored the significant roles played by noncoding-RNAs (ncRNAs), previously dismissed as "junk". The oncogenic potential of AR is manifested through its dysregulation of the ncRNAs' availability and function, promoting RCC tumorigenesis. This review offers a summary of the most recent findings on the role and molecular mechanisms of the AR in dysregulating the ncRNAs that play a role in the progression of RCC and the possibility of utilizing ncRNAs to target AR as a potential therapeutic strategy.

The Evolving Molecular Landscape and Actionable Alterations in Urologic Cancers

The genetic landscape of urologic cancers has evolved with the identification of actionable mutations that impact diagnosis, prognosis, and therapeutic strategies. This narrative review consolidates existing literature on genetic mutations across key urologic cancers, including bladder, renal, prostate, upper tract urothelial, testicular, and penile. The review highlights mutations in DNA damage repair genes, such as BRCA1/2 and PTEN, as well as pathway alterations like FGFR and PD-L1 overexpression. These mutations influence tumor behavior and therapeutic outcomes, emphasizing the need for precision oncology approaches. Molecular profiling, through tools like next-generation sequencing, has revolutionized patient care by enabling targeted treatment strategies, especially in cancers with distinct molecular subtypes such as luminal or basal bladder cancer and clear cell renal carcinoma. Emerging therapies, including FGFR inhibitors and immune checkpoint blockade, offer new treatment avenues, although resistance mechanisms remain a challenge. We also emphasize the importance of biomarker identification for personalized management, especially in metastatic settings where treatment intensification is often required. Future research is needed to further elucidate our understanding of the genetics affecting urologic cancers, which will help develop novel, individualized therapies to enhance oncologic outcomes.

Complete response to fifth-line anti-PD-1 rechallenge in fumarate hydratase-mutated papillary renal cell carcinoma

Fumarate hydratase (FH) mutated papillary renal cell carcinoma is an aggressive variant of kidney cancer that poorly responds to conventional targeted therapies and immunotherapy. Here, we present the 10-year follow-up of a heavily pre-treated patient with several lines of therapy, achieving a remarkable complete response to anti-PD-1 rechallenge. In addition, we highlight a common immune-related adverse event of anti-PD-1, eosinophilia, as a possible biomarker of response and using TCGA data analysis, provide proof-of-concept for tumor expression of the eosinophil-related gene SIGLEC8, as a promising powerful predictor of prognosis for papillary renal cell carcinoma patients.

Contemporary review of papillary renal cell carcinoma-current state and future directions

Historically, papillary renal cell carcinoma (PRCC) was divided into two types, type 1 and type 2, based solely on morphology. However, it is apparent that PRCC is far more complex and represents a histological, clinical, and molecular spectrum. There has been a significant evolution in our understanding of PRCC, highlighted by the recognition of new and molecularly defined entities that were previously included in PRCC type 2. This contemporary review addresses the evolving concepts regarding the PRCC, including why it is no longer needed to subtype PRCC, the current molecular landscape, prognostic parameters, and PRCC variants, including biphasic PRCC, papillary renal neoplasm with reverse polarity, and Warthin-like PRCC. Pathologists should also be aware of the potential mimickers of both low-grade and high-grade PRCCs as well as some new and emerging entities that may show papillary growth that should be excluded in the diagnostic workup. The evolving knowledge of PRCC biomarkers, morphologic patterns, and PRCC variants could also have important implications for clinical management. Lastly, the heterogeneity within the PRCC spectrum needs to be further studied, aiming to better stratify PRCC for appropriate clinical management and systemic therapy.

Decreased risk of renal cell carcinoma in patients with type 2 diabetes treated with sodium glucose cotransporter-2 inhibitors

Patients with type 2 diabetes (T2D) are at a higher risk of developing renal cell carcinoma (RCC) than the general population. In vitro and in vivo investigations of the effects of sodium glucose cotransporter-2 inhibitors (SGLT2I) have shown a significantly reduced risk of RCC. However, the impact of these drugs on the incidence of RCC in the human population is unclear. This study aimed to examine the association between SGLT2I use and RCC risk in patients with T2D. We undertook a nationwide retrospective cohort study using the Health and Welfare Data Science Center database (2016-2020). The primary outcome was the risk of incident RCC by estimating hazard ratios (HRs) and 95% confidence intervals (CIs). Multiple Cox regression modeling was applied to analyze the association between SGLT2I use and RCC risk in patients with T2D. In a cohort of 241,772 patients with T2D who were using SGLT2Is and 483,544 participants who were not, 220 and 609 RCC cases, respectively, were recorded. The mean follow-up period of the study subjects was 2 years. There was a decreased risk of RCC for SGLT2I users after adjusting for the index year, sex, age, comorbidities, and concurrent medication (adjusted HR 0.68; 95% CI, 0.58-0.81). The sensitivity test for the propensity score 1:1-matched analyses showed similar results (adjusted HR 0.67; 95% CI, 0.55-0.81). The subgroup analysis revealed consistent results for sex, age (<70 years), and comorbidity with chronic kidney disease. The present study indicates that SGLT2I therapy significantly decreases RCC risk in patients with T2D. This finding was also consistent among the sensitivity test and subgroup analysis for those with or without chronic kidney disease/hypertension.

Mechanism of lncRNA SNHG16 on kidney clear cell carcinoma cells by targeting miR-506-3p/ETS1/RAS/ERK molecular axis

Objective

This study aimed to investigate the mechanism of long noncoding ribonucleic acid (lncRNA) SNHG16 on kidney clear cell carcinoma (KIRC) cells by targeting miR-506-3p/ETS proto-oncogene 1, transcription factor (ETS1)/RAS/Extracellular regulated protein kinases (ERK) molecular axis, thus to provide reference for clinical diagnosis and treatment of KIRC in the future.

Methods

Thirty-six patients with KIRC were enrolled in this study, and their carcinoma tissues and adjacent tissues were obtained for the detection of SNHG16/miR-506-3p/ETS1/RAS/ERK expression. Then, over-expressed SNHG16 plasmid and silenced plasmid were transfected into KIRC cells to observe the changes of their biological behavior.

Results

SNHG16 and ETS1 were highly expressed while miR-506- 3p was low expressed in KIRC tissues; the RAS/ERK signaling pathway was significantly activated in KIRC tissues (P < 0.05). After SNHG16 silence, KIRC cells showed decreased proliferation, invasion and migration capabilities and increased apoptosis rate; correspondingly, increase in SNHG16 expression achieved opposite results (P < 0.05). Finally, in the rescue experiment, the effects of elevated SNHG16 on KIRC cells were reversed by simultaneous increase in miR-506-3p, and the effects of miR-506-3p were reversed by ETS1. Activation of the RAS/ERK pathway had the same effect as increase in ETS1, which further worsened the malignancy of KIRC. After miR-506-3p increase and ETS1 silence, the RAS/ERK signaling pathway was inhibited (P < 0.05). At last, the rescue experiment (co-transfection) confirmed that the effect of SNHG16 on KIRC cells is achieved via the miR-506-3p/ETS1/RAS/ERK molecular axis.

Conclusion

SNHG16 regulates the biological behavior of KIRC cells by targeting the miR-506-3p/ETS1/RAS/ERK molecular axis.

Development and validation of prognostic nomograms for adult with papillary renal cell carcinoma: A retrospective study

OBJECTIVE

The aim of the study was to create two consensus nomograms for predicting Overall Survival (OS) and Cancer-Specific Survival (CSS) in adults with papillary Renal Cell Carcinoma (pRCC).

METHODS

Using the Surveillance, Epidemiology, and End Results databases, a retrospective analysis of 1,074 adults with pRCC from 2004 to 2015 was performed. These patients were then randomly divided into two independent cohorts with a ratio of 7:3 (training cohort: 752; validation cohort: 322). In a retrospective analysis of 752 patients from the training cohort, independent prognostic variables affecting OS and CSS were found. R software was used to create prognostic nomograms based on the findings of Cox regression analysis. The performance of the nomograms was assessed using the Concordance Index (C-index), the Area Under Curve (AUC), a calibration curve, and Decision Curve Analysis (DCA). Data from the 107 postoperative pRCC patients at the Affiliated Hospital of Xuzhou Medical University were used for external validation of the nomogram.

RESULTS

For OS and CSS, the C-indices and AUCs of the training cohort and the validation cohort indicated that the model had excellent discrimination. The DCA demonstrated that the model was clinically applicable, and the calibration curves in the internal and external validations showed that the model's accuracy was high.

CONCLUSION

The authors developed and validated a prognostic nomogram that accurately predicted the 3-, 5-, and 8-year OS and CSS of adults with pRCC. Clinicians can use this knowledge to direct the clinical management and counseling of patients with pRCC.

The prognostic role of histomorphological subtyping in nonmetastatic papillary renal cell carcinoma after curative surgery: is subtype really irrelevant? A propensity score matching analysis of a multi-institutional real life data

BACKGROUND AND AIM

The role of histomorphological subtyping is an issue of debate in papillary renal cell carcinoma (papRCC). This multi-institutional study investigated the prognostic role of histomorphological subtyping in patients undergoing curative surgery for nonmetastatic papRCC.

PATIENTS AND METHODS

A total of 1,086 patients undergoing curative surgery were included from a retrospectively collected multi-institutional nonmetastatic papRCC database. The patients were divided into 2 groups based on histomorphological subtyping (type 1, n = 669 and type 2, n = 417). Furthermore, a propensity score-matching (PSM) cohort in 1:1 ratio (n = 317 for each subtype) was created to reduce the effect of potential confounding variables. The primary outcome of the study, the predictive role of histomorphological subtyping on the prognosis (recurrence free survival [RFS], cancer specific survival [CSS] and overall survival [OS]) in nonmetastatic papRCC after curative surgery, was investigated in both overall and PSM cohorts.

RESULTS

In overall cohort, type 2 group were older (66 vs. 63 years, P = 0.015) and more frequently underwent radical nephrectomy (37.4% vs. 25.6%, P < 0.001) and lymphadenectomy (22.3% vs. 15.1%, P = 0.003). Tumor size (4.5 vs. 3.8 cm, P < 0.001) was greater, and nuclear grade (P < 0.001), pT stage (P < 0.001), pN stage (P < 0.001), VENUSS score (P < 0.001) and VENUSS high risk (P < 0.001) were significantly higher in type 2 group. 5-year RFS (89.6% vs. 74.2%, P < 0.001), CSS (93.9% vs. 84.2%, P < 0.001) and OS (88.5% vs. 78.5%, P < 0.001) were significantly lower in type 2 group. On multivariable analyses, type 2 was a significant predictor for RFS (HR:1.86 [95%CI:1.33-2.61], P < 0.001) and CSS (HR:1.91 [95%CI:1.20-3.04], P = 0.006), but not for OS (HR:1.27 [95%CI:0.92-1.76], P = 0.150). In PSM cohort balanced with age, gender, symptoms at diagnosis, pT and pN stages, tumor grade, surgical margin status, sarcomatoid features, rhabdoid features, and presence of necrosis, type 2 increased recurrence risk (HR:1.75 [95%CI: 1.16-2.65]; P = 0.008), but not cancer specific mortality (HR: 1.57 [95%CI: 0.91-2.68]; P = 0.102) and overall mortality (HR: 1.01 [95%CI: 0.68-1.48]; P = 0.981) CONCLUSIONS: This multiinstitutional study suggested that type 2 was associated with adverse histopathologic outcomes, and predictor of RFS and CSS after surgical treatment of nonmetastatic papRCC, in overall cohort. In propensity score-matching cohort, type 2 remained the predictor of RFS. Eventhough 5th WHO classification for renal tumors eliminated histomorphological subtyping, these findings suggest that subtyping is relevant from the point of prognostic view.

Novel molecular classification and prognosis of papillary renal cell carcinoma based on a large-scale CRISPR-Cas9 screening and machine learning

Papillary renal cell carcinoma (PRCC) is a highly heterogeneous cancer, and PRCC patients with advanced/metastatic subgroup showed obviously shorter survival compared to other kinds of renal cell carcinomas. However, the molecular mechanism and prognostic predictors of PRCC remain unclear and are worth deep studying. The aim of this study is to identify novel molecular classification and construct a reliable prognostic model for PRCC. The expression data were retrieved from TCGA, GEO, GTEx and TARGET databases. CRISPR data was obtained from Depmap database. The key genes were selected by the intersection of CRISPR-Cas9 screening genes, differentially expressed genes, and genes with prognostic capacity in PRCC. The molecular classification was identified based on the key genes. Drug sensitivity, tumor microenvironment, somatic mutation, and survival were compared among the novel classification. A prognostic model utilizing multiple machine learning algorithms based on the key genes was developed and tested by independent external validation set. Our study identified three clusters (C1, C2 and C3) in PRCC based on 41 key genes. C2 had obviously higher expression of the key genes and lower survival than C1 and C3. Significant differences in drug sensitivity, tumor microenvironment, and mutation landscape have been observed among the three clusters. By utilizing 21 combinations of 9 machine learning algorithms, 9 out of 41 genes were chosen to construct a robust prognostic signature, which exhibited good prognostic ability. SERPINH1 was identified as a critical gene for its strong prognostic ability in PRCC by univariate and multiple Cox regression analyses. Quantitative real-time PCR and Western blot demonstrated that SERPINH1 mRNA and protein were highly expressed in PRCC cells compared with normal human renal cells. This study exhibited a new molecular classification and prognostic signature for PRCC, which may provide a potential biomarker and therapy target for PRCC patients.

Reclassifying Papillary, Oncocytic and Chromophobe Renal Tumours Based on the 5 < sup > th < /sup > Who Classification 2022

OBJECTIVE

The classification of renal tumors is expanding with the addition of new molecular entities in the 5th World Health Organization classification. Apart from this, the major updates in the definition of papillary renal cell carcinoma are that these tumors are no longer subtyped into type 1 and type 2. In oncocytic tumors, the new molecularly defined renal tumors, emerging and novel entities need to be considered in the diagnosis of oncocytic and chromophobe renal tumors.

MATERIAL AND METHODS

This is a retrospective study to review and reclassify papillary, oncocytic, and chromophobe renal tumors based on the new WHO classification and correlate with clinical data, gross, microscopic features, and immunohistochemistry markers.

RESULTS

A total of thirteen cases were reviewed and the tumor grade was changed for three out of four cases of papillary renal cell carcinoma and a single case was recategorized and graded. In nine cases of oncocytic and chromophobe renal tumors, the diagnoses were modified in 3 cases.

CONCLUSION

Newly defined molecular renal tumors require advanced immunohistochemistry markers and molecular tests. This poses diagnostic challenges to pathologists practicing in low resource settings where molecular tests are not available.

Prognostication for surgically treated papillary renal cell carcinoma: which model is the optimal choice?

Tweetable abstract Surgically treated papillary renal cell carcinoma shows distinct prognosis and needs specific prognostic models for counseling, follow-up and high-risk patient identification. Our goal is to summarize and compare currently recommended models.

Papillary Renal Cell Carcinoma: Demographics, Survival Analysis, Racial Disparities, and Genomic Landscape

Papillary renal cell carcinoma (PRCC) is the second most common histological subtype of renal cell cancer. This research aims to present a large database study highlighting the demographic, clinical, and pathological factors, racial disparities, prognosis, and survival of PRCC. The clinical and demographic data were extracted from the Surveillance, Epidemiology, and End Results (SEER) database, and molecular data was cured from the Catalogue Of Somatic Mutations in Cancer (COSMIC) database. PRCC had a median age of diagnosis at 64 years, with a higher incidence in men (77%), and Whites (68%). 70.3% of cases were Grades I-IV (13, 53, 31, and 3%, respectively). In patients with known data, 85% were localized to the kidney, and 84% of cases were 7 cm in size. No metastasis occurred in 97% of the known data. The most common treatment offered was surgical resection (9%). The 5-year overall survival was 79%, with patients undergoing surgery having a 90.6% 5-year survival. Multivariable analysis revealed age > 60 years, Black race, poor histologic differentiation, distant metastases, and tumor size > 10 cm as independent risk factors for mortality. The most common mutations identified from the COSMIC database were MET, KMT2D, KMT2C, ARID1A, and SPEN. PRCC affects male individuals in the sixth decade of life. Increased age, Black race, distant metastases, and tumors > 10 cm are associated with a worse prognosis. Surgical resection offers a favorable survival outcome. Next-generation sequencing (NGS) could identify potentially targetable alterations and future personalized therapeutic approaches.

ABCC2 brush-border expression predicts outcome in papillary renal cell carcinoma: a multi-institutional study of 254 cases

AIMS

Papillary renal cell carcinoma (PRCC) histologic subtyping is no longer recommended in the 2022 WHO classification. Currently, WHO/ISUP nucleolar grade is the only accepted prognostic histologic parameter for PRCC. ABCC2, a renal drug transporter, has been shown to significantly predict outcomes in PRCC. In this study we evaluated the prognostic significance of ABCC2 IHC staining patterns in a large, multi-institutional PRCC cohort and assessed the association of these patterns with ABCC2 mRNA expression.

METHODS AND RESULTS

We assessed 254 PRCCs for ABCC2 IHC reactivity patterns that were stratified into negative, cytoplasmic, brush-border <50%, and brush-border ≥50%. RNA in situ hybridization (ISH) was used to determine the transcript level of each group. Survival analysis was performed with SPSS and GraphPad software. RNA-ISH showed that the ABCC2 group with any brush-border staining was associated with a significant increase in the transcript level, when compared to the negative/cytoplasmic group (P = 0.034). Both ABCC2 groups with brush-border <50% (P = 0.024) and brush-border ≥50% (P < 0.001) were also associated with worse disease-free survival (DFS) in univariate analysis. Multivariate analysis showed that only ABCC2 IHC brush-border (<50% and ≥50%) reactivity groups (P = 0.037 and P = 0.003, respectively), and high-stage disease (P < 0.001) had a DFS of prognostic significance. In addition, ABCC2 brush-border showed significantly worse DFS in pT1a (P = 0.014), pT1 (P = 0.013), ≤4 cm tumour (P = 0.041) and high stage (P = 0.014) groups, while a similar analysis with high WHO/ISUP grade in these groups was not significant.

CONCLUSION

ABCC2 IHC brush-border expression in PRCC correlates with significantly higher gene expression and also independently predicts survival outcomes.

Ex Vivo Drug Testing in Patient-derived Papillary Renal Cancer Cells Reveals EGFR and the BCL2 Family as Therapeutic Targets

BACKGROUND

Immune checkpoint inhibitors and antiangiogenic agents are used for first-line treatment of advanced papillary renal cell carcinoma (pRCC) but pRCC response rates to these therapies are low.

OBJECTIVE

To generate and characterise a functional ex vivo model to identify novel treatment options in advanced pRCC.

DESIGN, SETTING, AND PARTICIPANTS

We established patient-derived cell cultures (PDCs) from seven pRCC samples from patients and characterised them via genomic analysis and drug profiling.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Comprehensive molecular characterisation in terms of copy number analysis and whole-exome sequencing confirmed the concordance of pRCC PDCs with the original tumours. We evaluated their sensitivity to novel drugs by generating drug scores for each PDC.

RESULTS AND LIMITATIONS

PDCs confirmed pRCC-specific copy number variations such as gains in chromosomes 7, 16, and 17. Whole-exome sequencing revealed that PDCs retained mutations in pRCC-specific driver genes. We performed drug screening with 526 novel and oncological compounds. Whereas exposure to conventional drugs showed low efficacy, the results highlighted EGFR and BCL2 family inhibition as the most effective targets in our pRCC PDCs.

CONCLUSIONS

High-throughput drug testing on newly established pRCC PDCs revealed that inhibition of EGFR and BCL2 family members could be a therapeutic strategy in pRCC.

PATIENT SUMMARY

We used a new approach to generate patient-derived cells from a specific type of kidney cancer. We showed that these cells have the same genetic background as the original tumour and can be used as models to study novel treatment options for this type of kidney cancer.

Free-fatty acid receptor-1 (FFA1/GPR40) promotes papillary RCC proliferation and tumor growth via Src/PI3K/AKT/NF-κB but suppresses migration by inhibition of EGFR, ERK1/2, STAT3 and EMT

BACKGROUND

Papillary renal cell carcinoma (pRCC) is a highly metastatic genitourinary cancer and is generally irresponsive to common treatments used for the more prevalent clear-cell (ccRCC) subtype. The goal of this study was to examine the novel role of the free fatty-acid receptor-1 (FFA1/GPR40), a cell-surface expressed G protein-coupled receptor that is activated by medium-to-long chained dietary fats, in modulation of pRCC cell migration invasion, proliferation and tumor growth.

METHODS

We assessed the expression of FFA1 in human pRCC and ccRCC tumor tissues compared to patient-matched non-cancerous controls, as well as in RCC cell lines. Using the selective FFA1 agonist AS2034178 and the selective FFA1 antagonist GW1100, we examined the role of FFA1 in modulating cell migration, invasion, proliferation and tumor growth and assessed the FFA1-associated intracellular signaling mechanisms via immunoblotting.

RESULTS

We reveal for the first time that FFA1 is upregulated in pRCC tissue compared to patient-matched non-cancerous adjacent tissue and that its expression increases with pRCC cancer pathology, while the inverse is seen in ccRCC tissue. We also show that FFA1 is expressed in the pRCC cell line ACHN, but not in ccRCC cell lines, suggesting a unique role in pRCC pathology. Our results demonstrate that FFA1 agonism promotes tumor growth and cell proliferation via c-Src/PI3K/AKT/NF-κB and COX-2 signaling. At the same time, agonism of FFA1 strongly inhibits migration and invasion, which are mechanistically mediated via inhibition of EGFR, ERK1/2 and regulators of epithelial-mesenchymal transition.

CONCLUSIONS

Our data suggest that FFA1 plays oppositional growth and migratory roles in pRCC and identifies this receptor as a potential target for modulation of pathogenesis of this aggressive cancer.

A New Treatment Landscape for RCC: Association of the Human Microbiome with Improved Outcomes in RCC

Microbes play different roles in metabolism, local or systemic inflammation, and immunity, and the human microbiome in tumor microenvironment (TME) is important for modulating the response to immunotherapy in cancer patients. Renal cell carcinoma (RCC) is an immunogenic tumor, and immunotherapy is the backbone of its treatment. Correlations between the microbiome and responsiveness to immune checkpoint inhibitors have been reported. This review summarizes the recent therapeutic strategies for RCC and the effects of TME on the systemic therapy of RCC. The current understanding and advances in microbiome research and the relationship between the microbiome and the response to immunotherapy for RCC are also discussed. Improving our understanding of the role of the microbiome in RCC treatment will facilitate the development of microbiome targeting therapies to modify the tumor microbiome and improve treatment outcomes.

Papillary renal neoplasm with reverse polarity: A clinicopathological and molecular genetic characterization of 16 cases with expanding the morphologic spectrum and further support for a novel entity

Papillary renal neoplasm with reverse polarity (PRNRP) is a recently described, rare renal tumor that differs clinically, morphologically, and molecularly from papillary renal cell carcinoma (RCC). To further characterize the pathological spectrum of this rare tumor, in this study, we retrospectively identified 16 cases of PRNRP from three institutions to comprehensively investigate the clinicopathological and molecular genetic features, using immunohistochemistry (IHC), fluorescence in-situ hybridization (FISH), and targeted next-generation sequencing (NGS). The patients included nine men and seven women, with age ranging from 47 to 80 years (median = 67.5 years, mean = 65 years). The tumor size ranged from 0.4 to 9.5 cm in the greatest dimension (median = 1.8 cm, mean = 2.6 cm). Most tumors (12/16) were incidentally identified by imaging studies. By AJCC stage, 15 were categorized as pT1 and 1 was pT2. Follow-up showed no recurrences, metastases, or disease-related deaths in all the 16 patients. Grossly, 14 cases demonstrated at least a partially cystic appearance. Microscopically, all PRNRPs except 1 (case 13) were composed predominantly of thin, branching papillary architecture covered by a single layer of cuboidal cells with finely granular cytoplasm, and low-grade nuclei typically located toward the apical surface away from the basement. Case 13 consisted mostly of solid, densely packed tubules with only a minor papillary component (5%). Other commonly seen histological features included hyalinized or edematous papillae (n = 11), lymphocyte aggregation in fibrovascular cores (n = 10), mast cell infiltration (n = 8), and intralesional hemorrhage (n = 7). Uncommonly seen histological features included lymphoid cuff (n = 4), hemosiderin deposition (n = 5), foci of clear cell change (n = 4), intracytoplasmic vacuoles (n = 4), eosinophilic hobnail cells (n = 2), and infarct-type necrosis (n = 1). Two PRNRPs were concurrent with ipsilateral clear cell papillary RCC and clear cell RCC, respectively. By IHC, the tumors were consistently positive for GATA3, CK7, and PAX8. Fourteen out of 16 tumors showed a basolateral-membranous E-cadherin expression pattern, and 12/16 cases were positive for 34βE12.The expression of AMACR, CD10, and vimentin was either absent or only weak and focal. By targeted NGS, 13/14 evaluated PRNRPs harbored KRAS missense mutations involving c.35G>T resulting in p.G12V (7/13), c.35G>A resulting in p.G12D (4/13), and c.34G>T resulting in p.G12C (2/13). By FISH, 1/15 had gains of chromosomes 7 and 17, and 2/8 male cases had deletion of chromosomes Y. In conclusion, our study confirms that PRNRP is an indolent renal cell neoplasm with unique morphology, consistent immunohistochemical profile, and recurrent KRAS mutation. Our study expands the morphologic spectrum of PRNRP and provides further evidence supporting it as a novel entity.