Collagens are the most abundant proteins in the body and comprise the basement membranes and stroma through which cancerous invasion occurs; however, a pro-neoplastic function for mutant collagens is undefined. Here we identify COL11A1 mutations in 66 of 100 cutaneous squamous cell carcinomas (cSCCs), the second most common U.S. cancer, concentrated in a triple helical region known to produce trans-dominant collagens. Analysis of COL11A1 and other collagen genes found that they are mutated across common epithelial malignancies. Knockout of mutant COL11A1 impairs cSCC tumorigenesis in vivo. Compared to otherwise genetically identical COL11A1 wild-type tissue, gene-edited mutant COL11A1 skin is characterized by induction of β1 integrin targets and accelerated neoplastic invasion. In mosaic tissue, mutant COL11A1 cells enhanced invasion by neighboring wild-type cells. These results suggest that specific collagens are commonly mutated in cancer and that mutant collagens may accelerate this process.

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Epithelial squamous cell carcinomas (SCC) most commonly originate in the skin, where they display disruptions in the normally tightly regulated homeostatic balance between keratinocyte proliferation and terminal differentiation. We performed a transcriptome-wide screen for genes of unknown function that possess inverse expression patterns in differentiating keratinocytes compared with cutaneous SCC (cSCC), leading to the identification of MAB21L4 (C2ORF54) as an enforcer of terminal differentiation that suppresses carcinogenesis. Loss of MAB21L4 in human cSCC organoids increased expression of RET to enable malignant progression. In addition to transcriptional upregulation of RET, deletion of MAB21L4 preempted recruitment of the CacyBP-Siah1 E3 ligase complex to RET and reduced its ubiquitylation. In SCC organoids and in vivo tumor models, genetic disruption of RET or selective inhibition of RET with BLU-667 (pralsetinib) suppressed SCC growth while inducing concomitant differentiation. Overall, loss of MAB21L4 early during SCC development blocks differentiation by increasing RET expression. These results suggest that targeting RET activation is a potential therapeutic strategy for treating SCC. Significance: Downregulation of RET mediated by MAB21L4–CacyBP interaction is required to induce epidermal differentiation and suppress carcinogenesis, suggesting RET inhibition as a potential therapeutic approach in squamous cell carcinoma.

OBJECTIVE Glioblastoma (GBM) is the most common malignant primary brain tumor in adults, with males more commonly affected than females(1.6:1). Despite advancements in treatments, prognosis is dismal with a median overall survival of 15 months. Our aim was to investigate sex as a variable in GBM patient survival after receiving incremental levels of standard-of-care treatment regimens – different extents of surgical resection and different numbers of cycles of adjuvant temozolomide chemotherapy. METHODS Drawing from our extensive multi-institutional brain tumor repository, we investigated GBM subjects with overall survival (OS), extent of resection (EOR), number of temozolomide (TMZ) cycles, and sex data (n=620, males: n=387, females: n=233). Cox proportional hazard ratios were computed to investigate the multivariable predictive value of the patient variables with OS. Patients were then divided into groups based on their sex, EOR (either biopsy, subtotal resection (STR) or gross total resection (GTR)), and TMZ cycles (I: < 6 cycles, II: 7-11 cycles and III: >12 cycles). RESULTS We observed that STR was beneficial for females (HR=0.52; CI=0.33-0.83; p-value=0.013), while for males the benefit was not detected (HR=0.73; CI=0.46-1.15; p-value=0.173) for STR but was detectable for GTR (HR=0.58, CI=0.37-0.90; p-value=0.014). Females receiving 7-11 cycles of TMZ showed a survival benefit (HR=0.52; CI=0.12-0.53; p-value=0.048) while males in the same group did not (HR=0.74; CI=0.46-1.19; p-value=0.21), in comparison to those in group I of TMZ cycles. No sex differences were identified in patients receiving < =6 cycles or >=12 cycles. CONCLUSION Together, our results contribute to the growing literature that sex differences exist in GBM patients, even in response to standard-of-care therapies. This should be accounted for when designing clinical trials for GBM so that we may advance our pursuit to deliver personalized medicine.

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