New Therapeutic Opportunities for the Treatment of Squamous Cell Carcinomas: A Focus on Novel Driver Kinases

Sox2 and βIII-Tubulin as Biomarkers of Drug Resistance in Poorly Differentiated Sinonasal Carcinomas

Poorly differentiated sinonasal carcinomas (PDCs) are tumors that have a poor prognosis despite advances in classical treatment. Predictive and prognostic markers and new personalized treatments could improve the oncological outcomes of patients. In this study, we analyzed SOX2 and βIII-tubulin as biomarkers that could have prognostic and therapeutic impacts on these tumors. The cohort included 57 cases of PDCs: 36 sinonasal undifferentiated carcinoma (SNUC) cases, 13 olfactory neuroblastoma (ONB) cases, and 8 sinonasal neuroendocrine carcinoma (SNEC) cases. Clinical follow-up data were available for 26 of these cases. Sox2 expression was detected using immunohistochemistry in 6 (75%) SNEC cases, 19 (53%) SNUC cases, and 6 (46%) ONB cases. The absence of Sox2 staining correlated with a higher rate of recurrence (p = 0.015), especially distant recurrence. The majority of cases showed βIII-tubulin expression, with strong positivity in 85%, 75%, and 64% of SNEC, ONB, and SNUC cases, respectively. Tumors with stronger βIII-tubulin expression demonstrated longer disease-free survival than those with no expression or low expression (p = 0.049). Sox2 and βIII-tubulin expression is common in poorly differentiated sinonasal tumors and has prognostic and therapeutic utility.

Protein Kinase C at the Crossroad of Mutations, Cancer, Targeted Therapy and Immune Response

The frequent PKC dysregulations observed in many tumors have made these enzymes natural targets for anticancer applications. Nevertheless, this considerable interest in the development of PKC modulators has not led to the expected therapeutic benefits, likely due to the complex biological activities regulated by PKC isoenzymes, often playing ambiguous and protective functions, further driven by the occurrence of mutations. The structure, regulation and functions of PKCs have been extensively covered in other publications. Herein, we focused on PKC alterations mostly associated with complete functional loss. We also addressed the modest yet encouraging results obtained targeting PKC in selected malignancies and the more frequent negative clinical outcomes. The reported observations advocate the need for more selective molecules and a better understanding of the involved pathways. Furthermore, we underlined the most relevant immune mechanisms controlled by PKC isoforms potentially impacting the immune checkpoint inhibitor blockade-mediated immune recovery. We believe that a comprehensive examination of the molecular features of the tumor microenvironment might improve clinical outcomes by tailoring PKC modulation. This approach can be further supported by the identification of potential response biomarkers, which may indicate patients who may benefit from the manipulation of distinctive PKC isoforms.

Invasive urothelial carcinoma with squamous differentiation and associated high-risk human papilloma virus infection: Clinical, cytologic, and histologic features of a rare entity

We correlate the fine needle aspiration (FNA) cytologic findings with the histologic features of an invasive high-grade urothelial carcinoma showing squamous differentiation in the setting of high-risk Human Papilloma Virus (hrHPV) infection. To our knowledge, only extensive urinary bladder catheterization has been associated with hrHPV-positive urothelial carcinoma with squamous differentiation, and rarely at that. Herein, we present a case arising in a patient with only sparse and intermittent catheterization. A 69-year-old woman presented with voiding difficulties, and after continued symptoms, a Foley catheter was placed, and a cystoscopy procedure revealed two 1-2 cm inflammatory masses. Excisional biopsies were interpreted as papillary urothelial carcinoma. One month follow-up pelvic imaging demonstrated a new mass involving the urinary bladder neck, with irregular wall thickening and perivesical fat stranding, as well as probable vaginal involvement. CT-guided FNA (CT-FNA) to collect smears and core biopsies revealed an invasive urothelial carcinoma with squamous differentiation. HPV-cytopathic changes amid squamous metaplasia and dysplasia were noted on FNA smears with HPV E6/E7 RNA in situ hybridization (ISH) showing on the FNA core biopsy specimen. Immunostains showed that the tumor cells were positive for P16 (strong, diffuse), CK7, p63, ER, and GATA3 (patchy). Subsequent radical cystectomy revealed the extent of the patient's carcinoma, with direct extension to the vaginal wall, and involvement of the radial soft tissue resection margins. Describing the cytomorphologic features of a hrHPV positive urothelial carcinoma with squamous differentiation, without an extensive history of urinary catheterization or prior known history of HPV infection, emphasizes the role of cytopathology as a powerful diagnostic tool for recognizing a unique and unexpected lesion.

ECT2 promotes malignant phenotypes through the activation of the AKT/mTOR pathway and cisplatin resistance in cervical cancer

Epithelial cell transforming sequence 2 (ECT2) is expressed at high levels in various malignancies and contributes to malignant phenotypes in cancers. However, ECT2 is still not fully understood regarding its function and carcinogenic mechanism in cervical cancer. This research indicated that ECT2 expression was elevated in cervical cancer based on bioinformatics analysis and clinical specimens. Experiments in vitro and in vivo confirmed that ECT2 knockdown could suppress the proliferation and metastasis of cervical carcinoma cells. In addition, we found that silencing ECT2 could enhance the sensitivity to cisplatin and promote cell apoptosis. Mechanistically, we observed that ECT2 knockdown could inhibit the AKT/mTOR pathway and activate apoptosis, while ECT2 overexpression induced the opposite effect. The relationship between ECT2 and AKT was further confirmed by immunoprecipitation and rescue experiments. We found that the ECT2 and AKT could interact to form a complex, and knockdown AKT could offset all of the effects induced by ECT2. Our study emphasized the key point of ECT2 in the reversal of cisplatin resistance, and ECT2 could become a potential therapeutic target in cervical cancer.

Degraders: The Ultimate Weapon Against Amplified Driver Kinases in Cancer

Amplification of pro-oncogenic kinases is a common genetic alteration driving tumorigenic phenotypes. Cancer cells rely on the amplified kinases to sustain cell proliferation, survival, and growth, presenting an opportunity to develop therapies targeting the amplified kinases. Utilizing small molecule catalytic inhibitors as therapies to target amplified kinases is plagued by de novo resistance driven by increased expression of the target, and amplified kinases can drive tumorigenic phenotypes independent of catalytic activity. Here, we discuss the emergence of proteolysis-targeting chimeras that provide an opportunity to target these oncogenic drivers effectively. SIGNIFICANCE STATEMENT: Protein kinases contribute to tumorigenesis through catalytic and noncatalytic mechanisms, and kinase gene amplifications are well described mechanisms of resistance to small molecule catalytic inhibitors. Repurposing catalytic inhibitors for the development of protein degraders will offer improved clinical benefits by targeting noncatalytic functions of kinases that promote tumorigenesis and overcoming resistance due to amplification.

Recent Advances in Kinase Drug Discovery Part I: The Editors' Take

This special issue on Advances in Kinase Drug Discovery provides a selection of research articles and topical reviews covering all aspects of drug discovery targeting the phosphotransferase enzyme family [...].