Mutations in the telomerase reverse transcriptase promoter and PIK3CA gene are common events in penile squamous cell carcinoma of Italian and Ugandan patients

• Published in: International journal of cancer 2022-06, Vol.150 (11), p.1879-1888
• Main Authors: Starita, Noemy, Pezzuto, Francesca, Sarno, Sabrina, Losito, Nunzia Simona, Perdonà, Sisto, Buonaguro, Luigi, Buonaguro, Franco M., Tornesello, Maria Lina
• Format: Article
• Language: English
• Subjects: Cancer; Carcinoma, Squamous Cell - genetics; Class I Phosphatidylinositol 3-Kinases - genetics; digital droplet PCR; Gene frequency; Genetic diversity; Genital cancers; Human papillomavirus; Humans; Infectious Causes of Cancer; Italy; Italy - epidemiology; Male; Medical research; Mutation; mutations; Notch1 protein; p53 Protein; Penile Neoplasms - genetics; penile squamous cell carcinoma; Penis; PIK3CA exon 9; Polymerase chain reaction; Promoter Regions, Genetic; RNA-directed DNA polymerase; Squamous cell carcinoma; Telomerase; Telomerase - genetics; Telomerase reverse transcriptase; TERT promoter; Tumors; Uganda; Uganda - epidemiology
• ISSN: 0020-7136; 1097-0215
• DOI: 10.1002/ijc.33990

Penile carcinoma develops either through human papillomavirus (HPV) related or unrelated carcinogenic pathways. Genetic alterations and nucleotide changes in coding regions (ie, TP53, CDKN2A, PIK3CA and NOTCH1) are main cancer driver events either in HPV positive or in HPV negative tumours. We investigated the presence of hotspot nucleotide mutations in TERT promoter (TERTp) and PIK3CA exon 9 and their relationship with HPV status in 69 penile cancer cases from Italian and Ugandan patients. Genetic variations and viral sequences have been characterised by end‐point polymerase chain reaction (PCR) and Sanger sequencing. The mutant allele frequencies (MAFs) of TERTp −124A/−146A and PIK3CA E545K have been determined by droplet digital PCR (ddPCR) assays. The results showed that TERTp mutations are highly prevalent in penile carcinoma (53.6%) and significantly more frequent in HPV negative (67.6%) than HPV positive (32.4%) cases (P = .0482). PIK3CA mutations were similarly distributed in virus‐related and unrelated cases (25.9% and 26.7%, respectively) and coexisted with TERTp changes in 15.8% of penile carcinoma samples. Notably, MAFs of co‐occurring mutations were frequently discordant indicating that PIK3CA E545K nucleotide changes are subsequent genetic events occurring in subclones of TERTp mutated cells. The frequencies of TERTp and PIK3CA mutations were higher among Italian compared to Ugandan cases and inversely correlated with the HPV status. In conclusion, TERTp mutations are very common in penile carcinoma and their coexistence with PIK3CA in a substantial number of cases may represent a novel oncogenic synergy relevant for patient stratification and use of therapeutic strategies against new actionable targets. What's new? Telomerase expression is reactivated in the majority of tumours through several mechanisms, including virus integration and TERT promoter (TERTp) mutations. This retrospective study shows that somatic mutations in TERTp are highly prevalent in penile carcinoma in both Italian and Ugandan patients and significantly more frequent in human papillomavirus (HPV)‐negative cancer cases (67.6%). Moreover, TERTp and PIK3CA hotspot changes coexisted in 15.8% of cases. The higher mutant allele frequency of TERT −124A/−146A compared to that of PIK3CA E545K suggests an asynchronous mutation timing. The coexistence of TERTp and PIK3CA mutations may represent a novel co‐actionable therapeutic target in penile carcinoma patients.