Thymopoietin-α, -β, and -γ Isoforms Increased Expression in Cervical Cancer Cells

Cervical cancer (CC) is a public health concern related to the human papillomavirus (HPV) persistent infection. Minichromosome maintenance 2 (MCM2) has been postulated as a surrogate marker for HPV infection. Thymopoietin (TMPO) is a nuclear protein regulated by E2F such as MCM2 or p16. TMPO can give rise to six different isoforms. Herein, both the mRNA and protein levels of TMPO isoforms were analyzed in cervical cells. TMPO expression was selected and analyzed through in silico in several databases from the healthy cervix and cervical lesions. TMPO RNA expression was evaluated in cervical samples and cell lines by RT-PCR and protein expression by Western-blot and immunohistochemistry assays. TMPO and MCM2 immunostaining were evaluated in cervical smears. The clinical-pathological correlation analysis was performed using Kruskal-Wallis or Χ ² tests. TMPO is overexpressed in 74% of CC cells and all CC cell lines. Moreover, negative immunostaining was observed in normal cervical tissue, compared to strong expression for cervical lesions. Interestingly, TMPO-α, -β, -δ, -ε, and -γ are expressed in all cervical cells and tissues, but a differential expression for α, -β, and -γ isoforms among the cervical cells was observed as overexpressed when HPV is present. Also, the immunostaining of both MCM2 and TMPO was quite similar, but TMPO expression was more sensitive and specific than MCM2 protein. The present study has revealed that TMPO protein expression could be a potential molecular marker for cervical transformed cells, highlighting the TMPO-α, -β, and -γ isoforms as a promising molecular marker of HPV infection.