Urothelial carcinoma with squamous differentiation--the pathologists׳ perspective

Tumor necrosis in magnetic resonance imaging predicts urothelial carcinoma with squamous differentiation in muscle-invasive bladder carcinoma

PURPOSE

This study investigated radiologic features on preoperative MRI to differentiate urothelial carcinoma with squamous differentiation (UCSD) from conventional urothelial carcinoma (UC) in muscle-invasive bladder carcinoma.

METHODS

Ninety-nine patients who underwent radical cystectomy and a preoperative bladder MRI scan within three months before surgery were retrospectively enrolled. Various MRI features, including tumor length, location, multiplicity, long-to-short axis ratio, morphology, radiologic stage, and degree of severe necrosis, were analyzed. Univariable and multivariable logistic regression analyses were performed to identify MRI features predictive of UCSD. The diagnostic performance of a significant MRI feature was assessed using 5-fold cross-validation.

RESULTS

Among the MRI features, significant radiologic findings associated with UCSD in the univariable analysis included heterogeneous tumor signal intensity in T2-weighted images (odds ratio [OR], 3.365; 95% confidence interval [CI], 1.213-9.986; P = 0.022) and contrast-enhanced T1-weighted images (OR, 4.428; 95% CI, 1.519-12.730; P = 0.007), as well as marked (≥ 50%) severe necrosis (OR, 17.100; 95% CI, 4.699-73.563; P < 0.001). In the multivariable analysis, marked (≥ 50%) severe necrosis (odds ratio [OR], 13.755; 95% confidence interval [CI], 2.796-89.118; P = 0.004) was a significant predictor of UCSD. Marked (≥ 50%) severe necrosis showed a high specificity of 95.0% with a precision of 65.0% for diagnosing UCSD based on 5-fold cross-validation.

CONCLUSION

Preoperative bladder MRI revealing marked severe necrosis may be indicative of UCSD and can assist in distinguishing it from conventional UC.

Pictorial review of multiparametric MRI in bladder urothelial carcinoma with variant histology: pearls and pitfalls

Bladder cancer (BC), predominantly comprising urothelial carcinomas (UCs), ranks as the tenth most common cancer worldwide. UCs with variant histology (variant UC), including squamous differentiation, glandular differentiation, plasmacytoid variant, micropapillary variant, sarcomatoid variant, and nested variant, accounting for 5-10% of cases, exhibit more aggressive and advanced tumor characteristics compared to pure UC. The Vesical Imaging-Reporting and Data System (VI-RADS), established in 2018, provides guidelines for the preoperative evaluation of muscle-invasive bladder cancer (MIBC) using multiparametric magnetic resonance imaging (mpMRI). This technique integrates T2-weighted imaging (T2WI), dynamic contrast-enhanced (DCE)-MRI, and diffusion-weighted imaging (DWI) to distinguish MIBC from non-muscle-invasive bladder cancer (NMIBC). VI-RADS has demonstrated high diagnostic performance in differentiating these two categories for pure UC. However, its accuracy in detecting muscle invasion in variant UCs is currently under investigation. These variant UCs are associated with a higher likelihood of disease recurrence and require precise preoperative assessment and immediate surgical intervention. This review highlights the potential value of mpMRI for different variant UCs and explores the clinical implications and prospects of VI-RADS in managing these patients, emphasizing the need for careful interpretation of mpMRI examinations including DCE-MRI, particularly given the heterogeneity and aggressive nature of variant UCs. Additionally, the review addresses the fundamental MRI reading procedures, discusses potential causes of diagnostic errors, and considers future directions in the use of artificial intelligence and radiomics to further optimize the bladder MRI protocol.

A comprehensive review of 3D cancer models for drug screening and translational research

The 3D cancer models fill the discovery gap of 2D cancer models and play an important role in cancer research. In addition to cancer cells, a range of other factors include the stroma, density and composition of extracellular matrix, cancer-associated immune cells (e.g., cancer-associated fibroblasts cancer cell-stroma interactions and subsequent interactions, and a number of other factors (e.g., tumor vasculature and tumor-like microenvironment in vivo) has been widely ignored in the 2D concept of culture. Despite this knowledge, the continued use of monolayer cell culture methods has led to the failure of a series of clinical trials. This review discusses the immense importance of tumor microenvironment (TME) recapitulation in cancer research, prioritizing the individual roles of TME elements in cancer histopathology. The TME provided by the 3D model fulfills the requirements of in vivo spatiotemporal arrangement, components, and is helpful in analyzing various different aspects of drug sensitivity in preclinical and clinical trials, some of which are discussed here. Furthermore, it discusses models for the co-assembly of different TME elements in vitro and focuses on their synergistic function and responsiveness as tumors. Furthermore, this review broadly describes of a handful of recently developed 3D models whose main focus is limited to drug development and their screening and/or the impact of this approach in preclinical and translational research.

Clinicopathologic and Survival After Cystectomy Outcomes in Squamous Cell Carcinoma of the Bladder

BACKGROUND

Squamous cell carcinoma of the bladder (SqCC) is a rare disease with limited management data. Thus, we sought to characterize the clinicopathologic and survival outcomes amongst patients with SqCC and explore the association of squamous differentiation within urothelial carcinoma (UC w/Squam), as compared to muscle invasive pure UC.

METHODS

We conducted a single-center retrospective cohort study of patients, stratified by histology, who underwent cystectomy for MIBC. Baseline clinicopathologic characteristics were compared, and overall survival was assessed using Kaplan-Meier method.

RESULTS

We identified 1,034 patients; 37 (3.58%) with SqCC histology, 908 (87.81%) with UC histology, and 89 (8.61%) with UC w/ Squam histology. Among SqCC patients, a higher proportion were Black and similarly a higher proportion were women; amongst patients with UC w/ Squam a higher proportion had lower BMI; and amongst patients with UC a higher proportion had lower clinical (c) T, cN, pathological (p) T, and pN stages. Patients presenting with UC were more likely to receive intravesical therapy; patients presenting with SqCC were less likely to receive neoadjuvant chemotherapy (NAC). Adjuvant chemotherapy rates were similar. With post-hoc Bonferroni analysis, overall survival, cancer-specific survival, and recurrence-free survival were significantly worse for the UC w/ Squam cohort.

CONCLUSIONS

UC w/ Squam histology was associated with worse survival outcomes after cystectomy for muscle invasive bladder cancer compared to UC. Our results suggest that UC w/ Squam is associated with more advanced disease compared to UC, warranting further prospective work on consideration of combination therapies for patients with this disease state.

Fluorescence-Based Microendoscopic Sensing System for Minimally Invasive In Vivo Bladder Cancer Diagnosis

Bladder cancer is commonly diagnosed by evaluating the tissue morphology through cystoscopy, and tumor resection is used as the primary treatment approach. However, these methods are limited by lesion site specificity and resection margin, and can thereby fail to detect cancer lesions at early stages. Nevertheless, rapid diagnosis without biopsy may be possible through fluorescence sensing. Herein, we describe a minimally invasive imaging system capable of sensing even small tumors through a 1.2 mm diameter flexible fiber bundle microprobe. We demonstrate that this new device can be used for the early diagnosis of bladder cancer in rats. Bladder cancer was induced in rats using the carcinogen N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN), and a togglable filter capable of PpIX fluorescence sensing was installed in the microendoscopic system. Following 5-aminolevulinic acid administration, tissue in the early stages of bladder cancer was successfully identified with fluorescence detection and confirmed with hematoxylin/eosin and ferrochelatase staining. Although the time required for BBN to induce bladder cancer varied between 3 and 4 weeks among the rats, the microendoscopic system allowed the minimally invasive follow-up on cancer development.

Reduced Expression Level of GPX2 in T1 Bladder Cancer and its Role in Early-phase Invasion of Bladder Cancer

BACKGROUND/AIM

The role of glutathione peroxidase 2 (GPX2) expression in urothelial carcinoma (UC) is rarely reported. The aim of this study was to assess the expression status of GPX2 in UC of the bladder.

MATERIALS AND METHODS

We collected samples from 112 patients treated with radical cystectomy for immunohistochemical study.

RESULTS

Following immunohistochemical analysis of the specimens, 86 (76.8%) had weak GPX2 expression. In cases with consistent GPX2 expression within the same lesion, the levels of GPX2 showed significant decreases from pTa to pT1 (47.1%) compared to those from pT1 to pT2 (5.9%) (p=0.017). Specimens obtained with transurethral resection before cancer progressed to muscle invasive bladder cancer showed that pT1 had a lower expression for GPX2 than that of pTa (63.3% vs. 93.3%; p=0.009).

CONCLUSION

The decrease in GPX2 expression among those with UC of the bladder may be involved in the early step of cancer invasion.

Urothelial carcinoma in the urinary bladder of a Japanese macaque (Macaca fuscata)

Tumors of urinary origin are infrequently reported in non-human primates. Urothelial carcinoma involving the urinary bladder was diagnosed in an adult female Japanese macaque that extended transmurally to the uterus and cervix. To our knowledge, this is the first report of a primary cystic urothelial carcinoma in a Japanese macaque.

Non-Muscle Invasive Bladder Cancer with Variant Histology: Biological Features and Clinical Implications

BACKGROUND

The most common bladder cancer (BC) histotype is pure urothelial carcinoma (UC), which may undergo divergent differentiation in some cases. Variant histology (VH) presents along variable morphologies, either single or combined between them or with pure UC. From a clinical standpoint, the vast majority of BC is diagnosed at non-invasive or minimally invasive stages, namely as non-muscle invasive BC (NMIBC). There is a wide range of therapeutic options for patients with NMIBC, according to their clinical and pathological features. However, current risk stratification models do not show optimal effectiveness. Evidence from the literature suggests that VH has peculiar biological features, and may be associated with poorer survival outcomes compared to pure UC.

SUMMARY

In order to describe the biological features and prognostic/predictive role of VH in NMIBC, and to discuss current treatment options, we performed a systematic literature search through multiple databases (PubMed/Medline, Google Scholar) for relevant articles according to the following terms, single and/or in combination: "non-muscle invasive bladder cancer," "variant histology," "micropapillary variant," "glandular differentiation," "squamous differentiation," "nested variant," "plasmacytoid variant," and "sarcomatoid variant." We extracted 99 studies including original articles, reviews, and systematic reviews, and subsequently analyzed data from 16 studies reporting on the outcome of NMIBC with VH. We found that the relative rarity of these forms as well as the heterogeneity in study populations and therapeutic protocols results in conflicting findings overall. Key Messages: The presence of VH should be taken into account when counseling a patient with NMIBC, since it may upgrade the disease to high-risk tumor and thus warrant a more aggressive treatment.

BBN-driven urinary bladder cancer mouse model

Around 3% of new cancer diagnoses and 2% of all cancer deaths every year are caused by urinary bladder cancer (BC). This indicates a great need for intensive studying of BC by using different approaches including indispensable mice models. The most common preclinical mouse model of bladder carcinogenesis relies on the use of a nitrosamine compound, N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN) which causes high-grade, invasive tumors in the urinary bladder. BBN-induced bladder cancer in mice recapitulates the histology and manifests genetic alterations similar to human muscle-invasive bladder cancer. Here we present a detailed protocol for the induction of BC in mice which is based on the administration of 0.05%-0.1% BBN in drinking water. Six-to-eight-week-old mice are treated orally with BBN for 12weeks and tumors are expected 8weeks after the termination of BBN regimen. Histopathologic examination of the lesions should be routinely assessed after hematoxylin and eosin staining by an experienced pathologist and it can vary from urothelial dysplasia to invasive bladder cancer with glandular and squamous divergent differentiation, the incidence of which might depend on the mouse strain, gender, BBN concentration and the timeline of the protocol. Utilizing half of the urinary bladder tissue for the isolation and analysis of RNA, DNA and proteins provides a comprehensive insight into the biology of BC and reduces the number of mice per study. Finally, the successful use of the BC model can facilitate fundamental biomedical discoveries leading to novel diagnostic and therapeutic approaches with clinical benefits.

Activation of PPARγ and inhibition of cell proliferation reduces key proteins associated with the basal subtype of bladder cancer in As3+-transformed UROtsa cells

Environmental exposure to arsenite (As³⁺) has a strong association with the development of human urothelial cancer (UC) and is the 5^th most common cancer in men and the 12^th most common cancer in women. Muscle invasive urothelial cancer (MIUC) are grouped into basal or luminal molecular subtypes based on their gene expression profile. The basal subtype is more aggressive and can be associated with squamous differentiation, characterized by high expression of keratins (KRT1, 5, 6, 14, and 16) and epidermal growth factor receptor (EGFR) within the tumors. The luminal subtype is less aggressive and is predominately characterized by elevated gene expression of peroxisome proliferator-activated receptor- gamma (PPARγ) and forkhead box protein A1 (FOXA1). We have previously shown that As³⁺-transformed urothelial cells (As-T) exhibit a basal subtype of UC expressing genes associated with squamous differentiation. We hypothesized that the molecular subtype of the As-T cells could be altered by inducing the expression of PPARγ and/or inhibiting the proliferation of the cells. Non-transformed and As-T cells were treated with Troglitazone (TG, PPARG agonist, 10 μM), PD153035 (PD, an EGFR inhibitor, 1 μM) or a combination of TG and PD for 3 days. The results obtained demonstrate that treatment of the As-T cells with TG upregulated the expression of PPARγ and FOXA1 whereas treatment with PD decreased the expression of some of the basal keratins. However, a combined treatment of TG and PD resulted in a consistent decrease of several proteins associated with the basal subtype of bladder cancers (KRT1, KRT14, KRT16, P63, and TFAP2A). Our data suggests that activation of PPARγ while inhibiting cell proliferation facilitates the regulation of genes involved in maintaining the luminal subtype of UC. In vivo animal studies are needed to address the efficacy of using PPARγ agonists and/or proliferation inhibitors to reduce tumor grade/stage of MIUC.

Role of Neoadjuvant Chemotherapy in Squamous Variant Histology in Urothelial Bladder Cancer: Does Presence and Percentage Matter?

BACKGROUND

The purpose of this study was to evaluate the effect of neoadjuvant chemotherapy (NACT) on squamous variant (SV) bladder cancer by investigating patients presenting with SV histology at the time of transurethral resection (TUR), stratified by their receipt of NACT.

MATERIALS AND METHODS

The records of 71 patients with muscle-invasive bladder cancer and SV in the TUR specimen who underwent cystectomy between 2008 and 2018 were reviewed. Our primary outcome was pathologic response at time of cystectomy. Secondary outcomes included recurrence-free survival and overall survival stratified by receipt of NACT. A subgroup analysis was then conducted on the patients with defined SV% on TUR stratified by % involvement (< 50% SV vs. ≥ 50% SV).

RESULTS

The median age of the NACT and no-NACT groups was 60.2 and 70 years, respectively (P = .003). The complete response rate at cystectomy was 60% versus 13.7% for the NACT and no-NACT groups, respectively (P < .001). The non-organ-confined disease rate at time of radical cystectomy was 35% for the NACT group and 68.6% for the no-NACT group (P = .01). The NACT group had fewer recurrences than the no-NACT group (10% vs 47.1%; P = .003). In the subgroup analysis, the lower rate of non-organ-confined disease persisted for the patients who underwent NACT at the lower SV percentage but failed to remain significant at greater percentage involvement. This was also true for overall survival.

CONCLUSIONS

The effect of NACT in variant histology bladder cancer is variable. In patients with SV, these results favor the recommendation in favor of NACT administration, particularly when the primary tumor has < 50% involvement by the variant histology.

Histologic Variants of Urothelial Carcinoma: Morphology, Molecular Features and Clinical Implications

Bladder cancer is a heterogeneous disease including conventional urothelial carcinoma (UC) and its histologic variants, and non-urothelial carcinoma, including squamous and glandular neoplasms. Urothelial carcinoma accounts for the majority of bladder cancer cases, but morphologic variants are common and include nested, microcystic, micropapillary, lymphoepithelioma-like, plasmacytoid, sarcomatoid, giant cell, undifferentiated, clear cell and lipoid. Certain variants of UC tend to be associated with a poor prognosis and have diagnostic and potential treatment implications that make the identification of variant histology crucial to clinical decision making. While there is still uncertainty regarding the prognostic implications of many of these variants, identifying and reporting variant histology is important to develop our understanding of their biology. Unique molecular features accompany many of these morphologic variants and to better understand these tumors, we review the molecular and clinical implications of histologic variants of bladder cancer. Major efforts are underway to include variant histology and divergent differentiation of UC in clinical trials to develop evidence based approaches to treatment. The purpose of this article is to review the current literature on variant histology of urothelial cancer and to highlight molecular findings and the clinical relevance of these tumors.

BCG instillation versus radical cystectomy for high-risk NMIBC with squamous/glandular histologic variants

This study aims to evaluate the effect of Bacillus Calmette-Guérin (BCG) instillation and radical cystectomy on high-risk NMIBC with squamous or glandular variants. We retrospectively reviewed the data of high-risk (T1 or CIS or HG or TaG1/G2 with multiple, recurrent, large tumor) NMIBC patients from January 2000 to December 2017. Comparative analysis of radical cystectomy, intravesical BCG, and observation groups was conducted in high-risk NMIBC with squamous or glandular histologic variants. Among the 1263 high-risk NMIBC patient, 62 (4.9%) were reported squamous or glandular histologic variants. Thirty patients underwent BCG instillation and 15 patients were subjected to radical cystectomy. Statistically significant differences were found between the three treatment groups in terms of underlying hypertension (p = 0.031), T stage (p = 0.022) and tumor multiplicity (p = 0.019). Similar 5-year OS (p = 0.893) and CSS (p = 0.811) were observed in each of BCG instillation and radical cystectomy group. BCG instillation showed survival benefit in both OS (p = 0.019) and CSS (p = 0.038) than in the observation group. In high-risk patients diagnosed with NMIBC bladder cancer with squamous or glandular histologic variants, both intravesical BCG and radical cystectomy showed survival gain. In conclusion, BCG instillation represents an appropriate treatment option in high-risk NMIBC with squamous or glandular histologic variant.

The clinicopathological characteristics and prognostic value of squamous differentiation in patients with bladder urothelial carcinoma: a meta-analysis

PURPOSE

Urothelial carcinoma with squamous differentiation (UCSD) is the most common histologic variant in bladder cancer (BCa). Previously, some studies have linked the presence of UCSD with the risk of worse survival outcomes in BCa patients. However, such association is still controversial. In this study, we performed a meta-analysis to clarify the clinicopathological characteristics and to further investigate the prognostic value of UCSD in BCa.

METHODS

A systematic literature search was performed in electronic databases including PubMed, Embase, Chinese National Knowledge Infrastructure and Wanfang Data until October 2018. Subgroup analyses were performed according to different treatments and study outcomes.

RESULTS

Total of 13,284 patients were enrolled in 19 studies which were included in this meta-analysis. The percentage of female patients with UCSD was significantly higher than those with pure urothelial carcinoma. UCSD was correlated with tumor stage T3/T4, tumor grade 3, positive surgical margin, and lymph node involvement. Moreover, the recurrence rate was higher in patients with UCSD after surgery. UCSD was associated with poorer disease-free survival (DFS). No significant difference of cancer-specific survival (CSS) or overall survival (OS) was found on multivariable analysis between the two groups.

CONCLUSIONS

Our study demonstrated that UCSD in BCa was associated not only with unfavorable clinicopathological features, but also with high risk of recurrence and poorer prognosis for DFS. However, UCSD is not independently significant for CSS and OS. Well-designed randomized study with larger sample size is warranted to verify the findings and to further explore the role of UCSD in BCa.

Clinical Significance of Squamous Differentiation in Urothelial Carcinoma of the Bladder

The prognostic value of squamous differentiation (SD) in urothelial carcinoma (UC) of the bladder is unclear. The aim of this study was to identify the clinical significance of SD in UC in terms of oncological outcomes in patients undergoing radical cystectomy (RC). We evaluated consecutive patients with muscle-invasive bladder cancer (MIBC; clinical T2-4aN0M0) treated with RC at our institution from March 2003 to March 2017. We enrolled 20 and 81 patients with UC with SD (UCSD) and pure UC, respectively. Postoperative survival outcomes were compared between the patients with UCSD and pure UC using the Kaplan-Meier method. Pre- and postcystectomy factors that influenced the overall survival (OS) and recurrence-free survival (RFS) were investigated in these patients. Multivariate Cox regression models were used to identify the predictors of OS and RFS. With a median follow-up time of 31 months, the 5-year OS rate of the UCSD and pure UC groups was 41.1% and 69.7% (P = .002) and the 5-year RFS rate was 51.8% and 59.5% (P = .027), respectively. The shape of the Kaplan-Meier curves for UCSD suggested a more rapid course of the disease within the first 2 years than observed in pure UC. Multivariate analyses suggested that SD in UC was significantly associated with OS (hazard ratio [HR]: 4.22; 95% confidence interval [CI]: 1.20-14.8; P = .024) and close to significance for a lower RFS (HR: 2.13, 95% CI: 0.74-6.15, P = .064). Our results indicate that SD may be an independent predictor of OS and RFS in UC of MIBC in patients undergoing RC.

Tumor Evolution and Drug Response in Patient-Derived Organoid Models of Bladder Cancer

Bladder cancer is the fifth most prevalent cancer in the U.S., yet is understudied, and few laboratory models exist that reflect the biology of the human disease. Here, we describe a biobank of patient-derived organoid lines that recapitulates the histopathological and molecular diversity of human bladder cancer. Organoid lines can be established efficiently from patient biopsies acquired before and after disease recurrence and are interconvertible with orthotopic xenografts. Notably, organoid lines often retain parental tumor heterogeneity and exhibit a spectrum of genomic changes that are consistent with tumor evolution in culture. Analyses of drug response using bladder tumor organoids show partial correlations with mutational profiles, as well as changes associated with treatment resistance, and specific responses can be validated using xenografts in vivo. Our studies indicate that patient-derived bladder tumor organoids represent a faithful model system for studying tumor evolution and treatment response in the context of precision cancer medicine.

Squamous Differentiation Predicts Poor Response to Cisplatin-Based Chemotherapy and Unfavorable Prognosis in Urothelial Carcinoma of the Urinary Bladder

OBJECTIVE

The efficacy of chemotherapy on UCSD is not known. This study was conducted to investigate the efficacy of cisplatin-based chemotherapy and prognosis of patients with UC with or without SD of the bladder.

METHODS

Patients with invasive bladder cancer (clinical T3-4aN0M0) who were treated between March 2003 and March 2015 with 2 or 3 cycles of neoadjuvant chemotherapy followed by radical cystectomy were retrospectively evaluated. Treatment outcomes were compared for each pathologic type in UCSD and pure UC. The primary end point was pathologic response in the cystectomy specimens. Disease-free survival and overall survival were secondary end points.

RESULTS

We evaluated 9 patients with UCSD and 29 patients with pure UC. In the cystectomy specimens, pathologic complete response without residual tumors was not seen in any patients with UCSD, but evident in 10 patients (34.5%) with pure UC. The proportion of pathologic downstaging was significantly lower in patients with UCSD than in those with pure UC (11.1% vs. 51.7%; P = .031). Patients with UCSD had poorer disease-free survival (P < .001) and overall survival (P = .001) than those with pure UC. On multivariate Cox regression analysis, SD in UC was an independent predictor of recurrence (hazard ratio, 4.43; 95% confidence interval, 1.44-13.6, P = .009) and mortality (hazard ratio, 3.51; 95% confidence interval, 1.11-11.1, P = .032).

CONCLUSIONS

UCSD of the bladder is less sensitive to cisplatin-based chemotherapy and has poor prognosis.

Elevated connexin 43 expression in arsenite-and cadmium-transformed human bladder cancer cells, tumor transplants and selected high grade human bladder cancers

Connexin 43 has been shown to play a role in cell migration and invasion; however, its role in bladder cancer is not well defined. Previous studies from our laboratory have shown that the environmental pollutants arsenite and cadmium can cause malignant transformation of the immortalized urothelial cell line UROtsa. These transformed cells can form tumors in immune-compromised mice. The goal of the present study was to determine if connexin 43 is expressed in the normal human bladder, the arsenite and cadmiun-transformed UROtsa cells as well as human urothelial cancer. The results obtained showed that connexin 43 is not expressed in the epithelial cells of the human bladder but is expressed in immortalized cultures of human urothelial cells and the expression is variable in the arsenite and cadmium- transformed urothelial cell lines derived from these immortalized cells. Tumor heterotransplants generated from the transformed cells expressed connexin 43 and the expression was localized to areas of squamous differentiation. Immuno-histochemical analysis of human bladder cancers also showed that the expression of connexin 43 was localized to areas of the tumor that showed early features of squamous differentiation. Treatment of UROtsa cells with various concentrations of arsenite or cadmium did not significantly alter the expression level of connexin 43. In conclusion, our results show that the expression of connexin 43 is localized to the areas of the tumor that show squamous differentiation, which may be an indicator of poor prognosis. This suggests that connexin 43 has the potential to be developed as a biomarker for bladder cancer that may have the ability to invade and metastasize.