The Relationship between Mycoplasmas and Cancer: Is It Fact or Fiction ? Narrative Review and Update on the Situation

Abstract

More than one million new cancer cases occur worldwide every year. Although many clinical trials are applied and recent diagnostic tools are employed, curing cancer disease is still a great challenge for mankind. Heredity and epigenetics are the main risk factors often related to cancer. Although, the infectious etiological role in carcinogenesis was also theorized. By establishing chronic infection and inflammation in their hosts, several microorganisms were suggested to cause cell transformation. Of these suspicious microorganisms, mycoplasmas were well regarded because of their intimate parasitism with host cells, as well as their silent and insidious role during infections. This assumption has opened many questions about the real role played by mycoplasmas in oncogenesis. Herein, we presented a sum up of many studies among the hundreds which had addressed the Mycoplasma-cancer topic over the past 50 years. Research studies in this field have first started by approving the mycoplasmas malignancy potential. Indeed, using animal models and in vitro experiments in various cell lines from human and other mammalians, many mycoplasmas were proven to cause varied modifications leading to cell transformation. Moreover, many studies have looked upon the Mycoplasma-cancer subject from an epidemiological point of view. Diverse techniques were used to assess the mycoplasmas prevalence in patients with cancer from different countries. Not less than 10 Mycoplasma species were detected in the context of at least 15 cancer types affecting the brain, the breast, the lymphatic system, and different organs in the genitourinary, respiratory, gastrointestinal, and urinary tracts. Based on these revelations, one should concede that detection of mycoplasmas often linked to ‘‘wolf in sheep’s clothing’’ is not a coincidence and might have a role in cancer. Thorough investigations are needed to better elucidate this role. This would have a substantial impact on the improvement of cancer diagnosis and its prevention.

Mycoplasmas as Host Pantropic and Specific Pathogens: Clinical Implications, Gene Transfer, Virulence Factors, and Future Perspectives

“…These studies concluded that mycoplasmas infection stimulates tumorigenesis by inducing cellular transformation. Yacoub et al (2021) have demonstrated the possible relationship between mycoplasmas infection and the development of cancers. In parallel, they reported the induction of malignant transformation by mycoplasmas infection in PMNCs (Zhang et al, 2004) and in many other human cell lines such as the uterus SK-UT-1B cells (Polianskaia et al, 1998), A549 lung cells and bone tissues (Jiang et al, 2008), prostate BPH-1 cells (Namiki et al, 2009), and neuronal cell lines (Ji et al, 2019).…”

Co-infection of human papillomavirus and other sexually transmitted bacteria in cervical cancer patients in the Philippines

“…Mycoplasmas can promote low-grade chronic inflammatory conditions without killing the cells. Thus, they were thought to be ideal for promoting carcinogenesis ( Yacoub et al, 2021 ). Xiaolei et al found that the prevalence and the pathogenic load of U. urealyticum were significantly higher in the cervical cancer group compared to the control group ( Xiaolei et al, 2014 ).…”

Eating the Enemy: Mycoplasma Strategies to Evade Neutrophil Extracellular Traps (NETs) Promoting Bacterial Nucleotides Uptake and Inflammatory Damage

“…The persistence of mycoplasma infection and the consequent chronic inflammation leads to a progressive malignant transformation, increasing the in vitro invasiveness and in vivo metastasis of different human tumor cells [ 162 ]. Epidemiologic studies demonstrated the association of several mycoplasma species with different kinds of tumors [ 163 ]. M. hominis , Ureaplasma parvum , and Ureaplasma urealyticum are tightly associated with prostate cancer [ 136 , 162 , 164 , 165 ].…”