Intrinsic Oncogenic Function of Intracellular Connexin26 Protein in Head and Neck Squamous Cell Carcinoma Cells

It has long been known that the gap junction is down-regulated in many tumours. One of the downregulation mechanisms is the translocation of connexin, a gap junction protein, from cell membrane into cytoplasm, nucleus, or Golgi apparatus. Interestingly, as tumours progress and reinforce their malignant phenotype, the amount of aberrantly-localised connexin increases in different malignant tumours including oesophageal squamous cell carcinoma, thus suggesting that such an aberrantly-localised connexin should be oncogenic, although gap junctional connexins are often tumour-suppressive. To define the dual roles of connexin in head and neck squamous cell carcinoma (HNSCC), we introduced the wild-type connexin26 (wtCx26) or the mutant Cx26 (icCx26) gene, the product of which carries the amino acid sequence AKKFF, an endoplasmic reticulum-Golgi retention signal, at the C-terminus and is not sorted to cell membrane, into the human FaDu hypopharyngeal cancer cell line that had severely impaired the expression of connexin during carcinogenesis. wtCx26 protein was trafficked to the cell membrane and formed gap junction, which successfully exerted cell-cell communication. On the other hand, the icCx26 protein was co-localised with a Golgi marker, as revealed by immunofluorescence, and thus was retained on the way to the cell membrane. While the forced expression of wtCx26 suppressed both cell proliferation in vitro and tumorigenicity in mice in vivo, icCx26 significantly enhanced both cell proliferation and tumorigenicity compared with the mock control clones, indicating that an excessive accumulation of connexin protein in intracellular domains should be involved in cancer progression and that restoration of proper subcellular sorting of connexin might be a therapeutic strategy to control HNSCC

Clinical Outcomes of Cetuximab and Paclitaxel after Progression on Immune Checkpoint Inhibitors in Recurrent or Metastatic Head and Neck Squamous Cell Carcinoma

Background and Objectives: In recent years, the effectiveness of chemotherapy after immune checkpoint inhibitor administration has attracted attention in various cancers, including head and neck cancers. However, individual assessments of the administered chemotherapy regimens are insufficient. This study aimed to evaluate the efficacy and safety of chemotherapy after immune checkpoint inhibitor administration in recurrent metastatic head and neck cancer by focusing on a single regimen. Materials and Methods: We retrospectively reviewed clinical and radiological data from the medical records of 18 patients with recurrent or metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) who received systemic chemotherapy with weekly cetuximab and paclitaxel (Cmab + PTX) after progression following immune checkpoint inhibitor (ICI) therapy. The objective response rate (ORR) and disease control rate (DCR) were assessed using Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1. Progression-free survival (PFS) and overall survival (OS) were estimated using the Kaplan-Meier method. Adverse events (AEs) were recorded using National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.0. Results: In all patients, the ORR, DCR, median PFS, and median OS were 44.4%, 72.2%, 3.8 months, and 9.6 months, respectively. Regarding AEs, three patients developed grade 3 neutropenia. Grade 3 anemia, paronychia, asthenia, and peripheral neuropathy were observed in one patient each. There were no treatment-related deaths. Conclusions: Cmab + PTX was shown to maintain high efficacy and acceptable safety for R/M HNSCC that progressed after ICI therapy. Further research is needed to establish optimal treatment sequences and drug combinations for recurrent R/M HNSCC

Intrinsic Oncogenic Function of Intracellular Connexin26 Protein in Head and Neck Squamous Cell Carcinoma Cells

It has long been known that the gap junction is down-regulated in many tumours. One of the downregulation mechanisms is the translocation of connexin, a gap junction protein, from cell membrane into cytoplasm, nucleus, or Golgi apparatus. Interestingly, as tumours progress and reinforce their malignant phenotype, the amount of aberrantly-localised connexin increases in different malignant tumours including oesophageal squamous cell carcinoma, thus suggesting that such an aberrantly-localised connexin should be oncogenic, although gap junctional connexins are often tumour-suppressive. To define the dual roles of connexin in head and neck squamous cell carcinoma (HNSCC), we introduced the wild-type connexin26 (wtCx26) or the mutant Cx26 (icCx26) gene, the product of which carries the amino acid sequence AKKFF, an endoplasmic reticulum-Golgi retention signal, at the C-terminus and is not sorted to cell membrane, into the human FaDu hypopharyngeal cancer cell line that had severely impaired the expression of connexin during carcinogenesis. wtCx26 protein was trafficked to the cell membrane and formed gap junction, which successfully exerted cell-cell communication. On the other hand, the icCx26 protein was co-localised with a Golgi marker, as revealed by immunofluorescence, and thus was retained on the way to the cell membrane. While the forced expression of wtCx26 suppressed both cell proliferation in vitro and tumorigenicity in mice in vivo, icCx26 significantly enhanced both cell proliferation and tumorigenicity compared with the mock control clones, indicating that an excessive accumulation of connexin protein in intracellular domains should be involved in cancer progression and that restoration of proper subcellular sorting of connexin might be a therapeutic strategy to control HNSCC

INTRA-GOLGI CONNEXIN26 BEHAVES IN A PRO-ONCOGENIC MANNER IN HEAD AND NECK CANCER CELLS

Downregulation of gap junctional intercellular communication is an important hallmark of malignanttumours.　One of the downregulation mechanisms is translocation of gap junction (GJ) proteincalled connexin from cell membrane into cytoplasm, nucleus, or Golgi apparatus.　Interestingly, as tumours progress and reinforce their malignant phenotype, the amount of aberrantly-localised connexin increases in different cancers including oesophageal squamous cell carcinoma,thus suggesting that such an aberrantly-localised connexin should be oncogenic.　Todetermine the roles of aberrantly-localised connexin in head and neck squamous cell carcinoma(HNSCC), we introduced wild-type connexin26 (wtCx26) or the Golgi-retained mutant Cx26(mtCx26) gene into human SAS lingual HNSCC cell line, which had lost the expression of connexinduring carcinogenesis.　The wtCx26 protein was trafficked to cell membrane and formedGJ, which successfully exerted cell-cell communication.　On the other hand, mtCx26 protein wasretained in the Golgi apparatus on the way to cell membrane.　While the forced expression ofwtCx26 suppressed various malignant phenotypes including cell proliferation, motility, and invasivenessin vitro, mtCx26 significantly reinforced these phenotypes compared with the mock controlclone, indicating that an excessive accumulation of connexin protein in Golgi apparatus shouldbe involved in cancer progression

Clinical Outcomes of Cetuximab and Paclitaxel after Progression on Immune Checkpoint Inhibitors in Recurrent or Metastatic Head and Neck Squamous Cell Carcinoma

Background and Objectives: In recent years, the effectiveness of chemotherapy after immune checkpoint inhibitor administration has attracted attention in various cancers, including head and neck cancers. However, individual assessments of the administered chemotherapy regimens are insufficient. This study aimed to evaluate the efficacy and safety of chemotherapy after immune checkpoint inhibitor administration in recurrent metastatic head and neck cancer by focusing on a single regimen. Materials and Methods: We retrospectively reviewed clinical and radiological data from the medical records of 18 patients with recurrent or metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) who received systemic chemotherapy with weekly cetuximab and paclitaxel (Cmab + PTX) after progression following immune checkpoint inhibitor (ICI) therapy. The objective response rate (ORR) and disease control rate (DCR) were assessed using Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1. Progression-free survival (PFS) and overall survival (OS) were estimated using the Kaplan–Meier method. Adverse events (AEs) were recorded using National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.0. Results: In all patients, the ORR, DCR, median PFS, and median OS were 44.4%, 72.2%, 3.8 months, and 9.6 months, respectively. Regarding AEs, three patients developed grade 3 neutropenia. Grade 3 anemia, paronychia, asthenia, and peripheral neuropathy were observed in one patient each. There were no treatment-related deaths. Conclusions: Cmab + PTX was shown to maintain high efficacy and acceptable safety for R/M HNSCC that progressed after ICI therapy. Further research is needed to establish optimal treatment sequences and drug combinations for recurrent R/M HNSCC

Clinical Outcomes of Cetuximab and Paclitaxel after Progression on Immune Checkpoint Inhibitors in Recurrent or Metastatic Head and Neck Squamous Cell Carcinoma

Background and Objectives: In recent years, the effectiveness of chemotherapy after immune checkpoint inhibitor administration has attracted attention in various cancers, including head and neck cancers. However, individual assessments of the administered chemotherapy regimens are insufficient. This study aimed to evaluate the efficacy and safety of chemotherapy after immune checkpoint inhibitor administration in recurrent metastatic head and neck cancer by focusing on a single regimen. Materials and Methods: We retrospectively reviewed clinical and radiological data from the medical records of 18 patients with recurrent or metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) who received systemic chemotherapy with weekly cetuximab and paclitaxel (Cmab + PTX) after progression following immune checkpoint inhibitor (ICI) therapy. The objective response rate (ORR) and disease control rate (DCR) were assessed using Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1. Progression-free survival (PFS) and overall survival (OS) were estimated using the Kaplan–Meier method. Adverse events (AEs) were recorded using National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.0. Results: In all patients, the ORR, DCR, median PFS, and median OS were 44.4%, 72.2%, 3.8 months, and 9.6 months, respectively. Regarding AEs, three patients developed grade 3 neutropenia. Grade 3 anemia, paronychia, asthenia, and peripheral neuropathy were observed in one patient each. There were no treatment-related deaths. Conclusions: Cmab + PTX was shown to maintain high efficacy and acceptable safety for R/M HNSCC that progressed after ICI therapy. Further research is needed to establish optimal treatment sequences and drug combinations for recurrent R/M HNSCC